Methods and systems for stopping a prime mover

Abstract

A method for stopping the rotation of a prime mover, comprising: Stopping fuel supply to engine cylinders that burn air and fuel; Commanding engagement of a starter from a non-engine-engaged state to an engine-engaged state; and Adjusting a position of a throttle valve based on whether or not the starter is engaged with the engine; wherein - the throttle valve is set to a first position when the starter does not engage the engine within a first engine speed range, wherein the throttle valve is set to a second position when the starter engages the engine within the first engine speed range, the second position being more open than the first position; and / or - the starter is commanded to engage the engine within a predetermined crankshaft angle window, the crankshaft angle window being within ± 40 crankshaft degrees of a top dead center of a cylinder stroke.

Description

Cross-reference to related applications

[0001] This application claims priority to United States Provisional Patent Application 61 / 643,125, filed May 4, 2012, the entire contents of which are hereby incorporated by reference for all purposes. Area

[0002] This description relates to a system and methods for stopping and restarting an engine of a vehicle. The methods may be particularly useful for engines that are selectively stopped automatically.

[0003] US 2011 / 0 239 974 A1 discloses an internal combustion engine with a stop and restart system. US 2011 / 0 137 544 A1 discloses a system for cranking an internal combustion engine by engagement of the pinion with a ring gear. DE 10 2012 204 095 A1 discloses a method and system for controlling an engine. DE 10 2011 007 692 A1 discloses a device and method for starting an internal combustion engine arranged in a vehicle. Background and Summary

[0004] A vehicle's engine may be stopped under selected conditions to conserve fuel. The conditions that permit engine stopping may change while the engine is stopped, allowing the engine to be restarted before engine rotation has completely stopped. For example, a driver may release a brake pedal shortly after fuel injection to the engine cylinders stops. The engine may be restarted by resuming fuel injection. However, the engine speed may be reduced to a lower level at which the engine cannot be restarted simply by reactivating fuel to the engine cylinders.One way to restart the engine at lower engine speeds is to engage a starter motor and provide engine cranking assistance if the driver changes their mind. However, engaging the starter motor can change the engine speed profile and affect engine emissions.

[0005] The inventors herein have recognized the above-mentioned disadvantages and have developed a method for stopping the rotation of an engine, comprising: stopping the supply of fuel to engine cylinders that combust air and fuel; commanding engagement of a starter from a non-engaged state to an engagement with the engine; and adjusting a position of a throttle valve based on whether or not the starter is engaged with the engine; wherein - the throttle valve is set to a first position when the starter does not engage the engine within a first engine speed range, wherein the throttle valve is set to a second position when the starter engages the engine within the first engine speed range, the second position being more open than the first position; and / or - the starter is commanded to engage the engine within a predetermined crankshaft angle window, the crankshaft angle window being within ± 40 crankshaft degrees of a top dead center of a cylinder stroke.

[0006] By adjusting a position of a throttle valve during engine stop in response to whether or not the starter engages the engine, it may be possible to improve engine stopping so that subsequent engine starting is improved. In particular, an actuator, such as a throttle valve, can be adjusted during engine stop in response to whether or not a starter engages an engine so that the engine can be made ready to start. For example, when the starter is engaged with the engine, it may be desirable to partially open the throttle valve to a greater extent so that additional torque can be supplied if a vehicle operator changes his mind.

[0007] The present description may provide several advantages. In particular, the approach may improve engine stopping by preparing the engine for restart. Furthermore, the approach may improve engine stop position control by adjusting the air entering the cylinders during an engine stop.

[0008] The above advantages and other advantages and features of the present description will be readily apparent from the following detailed description taken alone or in conjunction with the accompanying drawings.

[0009] Of course, the above summary is provided to introduce, in a simplified form, a selection of concepts further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is defined only by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages identified above or in any part of this disclosure. Brief description of the drawings

[0010] The advantages described herein will be more fully understood by reading an example of an embodiment, referred to herein as the detailed description, alone or with reference to the drawings in which: Fig. 1 is a schematic diagram of a power machine; Fig. 2 shows a first example vehicle powertrain configuration; Fig. 3 shows a second example vehicle powertrain configuration; Fig. 4 is a flowchart showing an example of operating a vehicle powertrain with the methods described in the following figures; Fig. 5-8 show flowcharts and conditions for operating a hybrid vehicle powertrain in response to driving route conditions; Fig. 9 and Fig. 10 shows a method and prediction sequence for adjusting powertrain operation in response to vehicle mass; Fig. 11 and Fig. 12 shows a method and prediction sequence for starting a hybrid vehicle; Fig. 13 and Fig. 14 shows a method and prediction sequence for adjusting fuel for a hybrid powertrain during engine start-up; Fig. 15-18 show methods and prediction sequences for starting a hybrid vehicle engine during transmission shifting; Fig. 19-22 show methods and prediction sequences for providing flywheel and driveline disconnect clutch compensation; Fig. 23-26 show methods and prediction sequences for stopping an engine of a hybrid vehicle; Fig. 27 and Fig. 28 shows a method and prediction sequence for stopping a hybrid vehicle with a stopped engine on a hill; Fig. 29A-36 show methods and prediction sequences for operating a hybrid powertrain with driveline brakes; Fig. 37-40 show methods and prediction sequences for operating a hybrid powertrain in an idle mode; Fig. 41-44 show methods and prediction sequences for adjusting driveline disconnect clutch operation; and Fig. 45-48 Show prediction functions for describing or modeling a transmission torque converter. Detailed description

[0011] This description relates to controlling a powertrain of a hybrid vehicle. The hybrid vehicle may include an engine and an electric machine, as described in Fig. 1-3. The engine can operate with or without an integrated starter / generator (e.g., an electric machine or motor, which may be abbreviated DISG) during vehicle operation. The integrated starter / generator is integrated into the driveline on the same axis as the engine crankshaft and rotates as the torque converter impeller rotates. Further, the DISG cannot be selectively engaged or disengaged with the driveline. Rather, the DISG is an integral part of the driveline. Still further, the DISG can operate with or without the engine operating. The mass and inertia of the DISG remain with the driveline when the DISG is not operating to deliver or absorb torque to or from the driveline.

[0012] The drive train can be designed according to the procedure of Fig. 4. In some examples, the driveline may be operated based on a route and vehicle mass, as in Fig. 5-10. The engine can be operated according to the Fig. 11 to 18. Drivetrain component compensation can be provided as shown in Fig. 19-22. Fuel can be saved by selectively stopping the engine, as described in Fig. 23-28. The driveline may also enter a regeneration mode, as described in Fig. 29A-36, in which the vehicle's kinetic energy is converted into electrical energy. The electrical energy can then be used to propel the vehicle. During some conditions, the vehicle powertrain can enter a sailing mode in which the engine is operating but is not mechanically coupled to the DISG or the transmission or the vehicle wheels, as described in Fig. 37-40. The operation of the driveline disconnect clutch can be adjusted as described in Fig. 41 to 44. The methods described here can be used together simultaneously to operate in a system that performs multiple methods. Finally, Fig. 45-47 Prediction functions for describing a transmission torque converter.

[0013] With reference to Fig. 1, an internal combustion engine 10 with several cylinders, one of which cylinders in Fig. 1, is controlled by an electronic engine control unit 12. The engine 10 includes a combustion chamber 30 and cylinder walls 32 with a piston 36 disposed therein and connected to a crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. A starter 96 includes a pinion shaft 98 and a pinion gear 95. The pinion shaft 98 can selectively advance the pinion gear 95 to engage it with the ring gear 99. The starter 96 can be mounted directly to the front of the engine or to the rear of the engine. In some examples, the starter 96 can selectively provide torque to the crankshaft 40 via a belt or chain. The starter 96 can be described as a lower-power starting device. In one example, the starter 96 is in a base state when not engaged with the engine crankshaft.Combustion chamber 30 is shown communicating with an intake manifold 44 and an exhaust manifold 48 via a respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be actuated by an intake cam 51 and an exhaust cam 53. The position of intake cam 51 may be determined by an intake cam sensor 55. The position of exhaust cam 53 may be determined by an exhaust cam sensor 57.

[0014] A fuel injector 66 is shown positioned to inject fuel directly into the cylinder 30, known to those skilled in the art as direct injection. Alternatively, fuel may be injected into an intake port, known to those skilled in the art as port injection. The fuel injector 66 delivers liquid fuel in proportion to the pulse width of a signal FPW from the controller 12. The fuel is delivered to the fuel injector 66 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail (not shown). The fuel injector 66 is supplied with operating power from the driver 68, which is responsive to the controller 12.Additionally, the intake manifold 44 is shown in communication with an optional electronic throttle 62 that adjusts a position of a throttle plate 64 to control airflow from the air intake 42 to the intake manifold 44. In one example, a low-pressure direct injection system may be used, wherein the fuel pressure may be increased to approximately 20-30 bar. Alternatively, a high-pressure dual-stage fuel system may be used to produce higher fuel pressures. In some examples, the throttle 62 and throttle plate 64 may be disposed between the intake valve 52 and the intake manifold 44 such that the throttle 62 is a port throttle.

[0015] A distributorless ignition system 88 provides an ignition spark to the combustion chamber 30 via a spark plug 92 in response to the control unit 12. A universal exhaust gas oxygen (UEGO) sensor 126 is shown coupled to the exhaust manifold 48 upstream of a catalytic converter 70. Alternatively, the UEGO sensor 126 may be replaced with a dual-state exhaust gas oxygen sensor.

[0016] In one example, the catalyst 70 may include multiple catalyst modules. In another example, multiple emission control devices, each with multiple modules, may be used. The catalyst 70 may be a three-way catalyst, a particulate filter, a lean NOx trap, a selective reduction catalyst, or another emission control device. An exhaust device heater 119 may also be disposed in the exhaust system to heat the catalyst 70 and / or exhaust gases.

[0017] The control unit 12 is in Fig. 1 as a conventional microcomputer comprising: a microprocessor unit 102, input / output ports 104, a read-only memory 106, a random access memory 108, a latch 110, and a conventional data bus.The control unit 12 is shown receiving various signals from sensors coupled to the engine 10, in addition to the signals previously discussed, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to a cooling sleeve 114; a position sensor 134 coupled to an accelerator pedal 130 for sensing the force and / or position applied by a foot 132; a position sensor 154 coupled to the brake pedal 150 for sensing the force and / or position applied by a foot 152; an engine manifold pressure (MAP) measurement from pressure sensor 122 coupled to the intake manifold 44; an engine position sensor from a Hall effect sensor 118 that senses the position of the crankshaft 40; a measurement of the air mass entering the engine from sensor 120; and a measurement of the throttle position from sensor 58.Barometric pressure may also be sensed for processing by control unit 12 (sensor not shown). In a preferred aspect of the present description, engine position sensor 118 generates a predetermined number of equally spaced pulses at each revolution of the crankshaft, from which engine speed (RPM) can be determined.

[0018] In some examples, the engine may be coupled to an electric motor / battery system in a hybrid vehicle, as in Fig. 2 and Fig. 3. Furthermore, in some examples, other engine configurations may be used, such as a diesel engine.

[0019] During operation, each cylinder within the engine 10 typically undergoes a four-stroke cycle: the cycle includes the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke. During the intake stroke, the exhaust valve 54 generally closes and the intake valve 52 opens. Air is introduced into the combustion chamber 30 via the intake manifold 44, and the piston 36 moves toward the bottom of the cylinder to increase the volume within the combustion chamber 30. The position where the piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., when the combustion chamber 30 is at its largest volume) is typically referred to by those skilled in the art as bottom dead center (BDC). During the compression stroke, the intake valve 52 and the exhaust valve 54 are closed. The piston 36 moves toward the cylinder head to compress the air within the combustion chamber 30.The point at which the piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when the combustion chamber 30 is at its smallest volume) is typically referred to by those skilled in the art as top dead center (TDC). In a process referred to below as injection, fuel is introduced into the combustion chamber. In a process referred to below as ignition, the injected fuel is ignited by a known ignition means such as a spark plug 92, resulting in combustion. During the expansion stroke, the expanding gases push the piston 36 back to BDC. The crankshaft 40 converts the piston motion into rotating shaft torque. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the combusted air / fuel mixture to the exhaust manifold 48, and the piston returns to TDC.It should be noted that the above is shown merely as an example and that the intake and exhaust valve opening and / or closing timing may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0020] Fig. 2 is a block diagram of a vehicle driveline 200 in a vehicle 290. The driveline 200 may be driven by the engine 10. The engine 10 may be connected to a Fig. 1 or via the DISG 240. Furthermore, the engine 10 may generate or adjust torque via a torque actuator 204, such as a fuel injector, throttle body, etc.

[0021] Engine output torque may be transmitted to an input side of a dual-mass flywheel 232. Engine speed, as well as the dual-mass flywheel input side position and speed, may be determined via the engine position sensor 118. The dual-mass flywheel 232 may include springs and separate masses (not shown) to dampen driveline torque disturbances. The output side of the dual-mass flywheel 232 is shown mechanically coupled to the input side of a driveline disconnect clutch 236. The driveline disconnect clutch 236 may be electrically or hydraulically actuated. A position sensor 234 is disposed on the driveline disconnect clutch side of the dual-mass flywheel 232 to sense the output position and speed of the dual-mass flywheel 232. In some examples, the position sensor 234 may include a torque sensor.The downstream side of the driveline disconnect clutch 236 is shown mechanically coupled to the DISG input shaft 237.

[0022] The DISG 240 may be operated to provide torque to the driveline 200 or to convert driveline torque into electrical energy to be stored in an electrical energy storage device 275. The DISG 240 has an output power greater than that of the Fig. 1. Further, the DISG 240 directly drives or is directly driven by the driveline 200. There are no belts, gears, or chains to couple the DISG 240 to the driveline 200. Rather, the DISG 240 rotates at the same rate as the driveline 200. The electrical energy storage device 275 may be a battery, a capacitor, or an inductor. The downstream side of the DISG 240 is mechanically coupled to the impeller 285 of the torque converter 206 via a shaft 241. The upstream side of the DISG 240 is mechanically coupled to the driveline disconnect clutch 236.

[0023] The torque converter 206 includes a turbine 286 for outputting torque to the input shaft 270. The input shaft 270 mechanically couples the torque converter 206 to an automatic transmission 208. The torque converter 206 also includes a torque converter lock-up clutch (TCC) 212. Torque is transferred directly from the impeller 285 to the turbine 286 when the TCC is locked. The TCC is electrically actuated by the controller 12. Alternatively, the TCC may be hydraulically locked. In one example, the torque converter may be referred to as a component of the transmission. The torque converter impeller speed and position may be determined via sensor 238. The torque converter turbine speed and position may be determined via position sensor 239. In some examples, 238 and / or 239 may be torque sensors or may be a combination of position and torque sensors.

[0024] When the torque converter clutch 212 is fully disengaged, the torque converter 206 transmits engine torque to the automatic transmission 208 via a fluid connection between the torque converter turbine 286 and the torque converter impeller 285, enabling torque multiplication. Conversely, when the torque converter clutch 212 is fully engaged, the engine output torque is transmitted directly through the torque converter clutch to an input shaft 270 of the transmission 208. Alternatively, the torque converter clutch 212 may be partially engaged, allowing the amount of torque directly transmitted to the transmission to be adjusted.The controller 12 may be configured to adjust the amount of torque transferred from the torque converter 206 by adjusting the torque converter clutch 212 in response to various engine operating conditions or based on a driver's engine operating request.

[0025] The automatic transmission 208 includes gear clutches (e.g., gears 1-6) 211 and a forward clutch 210. The gear clutches 211 and the forward clutch 210 can be selectively engaged to propel a vehicle. The torque output from the automatic transmission 208 can, in turn, be transmitted to the wheels 216 to propel the vehicle via the output shaft 260. The output shaft 260 delivers torque from the transmission 308 to the wheels 216 via the differential 255, which includes a first gear 257 and a second gear 258. The automatic transmission 208 can transmit input drive torque at the input shaft 270 in response to a vehicle driving condition before transmitting output drive torque to the wheels 216.

[0026] Further, a frictional force may be applied to the wheels 216 by engaging wheel friction brakes 218. In one example, the wheel friction brakes 218 may be engaged in response to the driver pressing their foot on a brake pedal (not shown). In other examples, the controller 12 or a controller associated with the controller 12 may apply the engagement of the wheel friction brakes. In the same way, a frictional force for the wheels 216 may be reduced by disengaging the wheel friction brakes 218 in response to the driver releasing their foot from a brake pedal. Further, the vehicle brakes may apply a frictional force to the wheels 216 via the controller 12 as part of an automated engine stop procedure.

[0027] A mechanical oil pump 214 may be in fluid communication with the automatic transmission 208 to provide hydraulic pressure to engage various clutches, such as the forward clutch 210, the gear clutches 211, and / or the torque converter clutch 212. The mechanical oil pump 214 may be operated in accordance with the torque converter 206 and may be driven, for example, by the rotation of the engine or DISG via the input shaft 241. Consequently, the hydraulic pressure generated in the mechanical oil pump 214 may increase as engine speed and / or DISG speed increases and may decrease as engine speed and / or DISG speed decreases.

[0028] The control unit 12 may be configured to receive inputs from the engine 10, as shown in Fig. 1, and consequently control engine output torque and / or operation of the torque converter, transmission, DISG, clutches, and / or brakes. As one example, engine output torque may be controlled by adjusting a combination of spark timing, fuel pulse width, fuel pulse timing, and / or air charge, by controlling throttle opening and / or valve timing, valve lift, and boost for turbocharged or supercharged engines. In the case of a diesel engine, controller 12 may control engine output torque by controlling a combination of fuel pulse width, fuel pulse timing, and air charge. In all cases, engine control may be performed on a cylinder-by-cylinder basis to control engine output torque.The control unit 12 may also control the output torque and electrical energy generation from the DISG by adjusting the current flowing to and from the DISG windings, as is known in the art.

[0029] When idle stop conditions are met, the controller 12 may initiate engine shutdown by shutting off fuel and spark to the engine. However, the engine may continue to rotate in some examples. To maintain an amount of torsion in the transmission, the controller 12 may further fix rotating elements of the transmission 208 to a housing 259 of the transmission and thereby to the frame of the vehicle. In particular, the controller 12 may engage one or more transmission clutches, such as the forward clutch 210, and lock the engaged transmission clutch(es) to the transmission housing 259 and vehicle frame, as described in U.S. Patent Application No. 12 / 833,788, "METHOD FOR CONTROLLING AN ENGINE THAT MAY BE AUTOMATICALLY STOPPED," which is hereby incorporated by reference in its entirety. A transmission clutch pressure may be varied (e.g.,increased) to adjust the engagement state of a transmission clutch and create a desired amount of transmission torsion.

[0030] Wheel brake pressure may also be adjusted during engine shutdown based on transmission clutch pressure to assist in locking the transmission while reducing torque transmitted through the wheels. In particular, by applying the wheel brakes 218 while locking one or more engaged transmission clutches, opposing forces may be applied to the transmission and consequently to the driveline, thereby keeping the transmission gears actively engaged and maintaining potential torsional energy in the transmission gear set without moving the wheels. In one example, wheel brake pressure may be adjusted to coordinate the application of the wheel brakes with the locking of the engaged transmission clutch during engine shutdown.Thus, by adjusting the wheel brake pressure and clutch pressure, the amount of torsion retained in the transmission when the engine is turned off can be adjusted.

[0031] When restart conditions are met and / or a vehicle driver wishes to launch the vehicle, the control unit 12 may reactivate the engine by resuming combustion in the cylinders. As further described with reference to Fig. 11-18, the power machine can be started in a variety of ways.

[0032] The vehicle 290 may also include a windshield heater 294 and a rear window heater 292. The window heaters 294 and 292 may be electrically operated and embedded in or coupled to the front and rear windows 295 and 293 of the vehicle. The vehicle 290 may also include lights 296 that may or may not be visible to the driver while the driver is operating the vehicle 290. The vehicle 290 may also include an electrically operated fuel pump 299 that supplies fuel to the engine 10 during selected conditions. Finally, the vehicle 290 may include an electric heater 298 that selectively supplies heat to air within a vehicle cabin or ambient air outside the vehicle 290.

[0033] With reference to Fig. 3, a second example vehicle driveline configuration is shown. Many of the elements in driveline 300 are similar to the elements of driveline 200 and use similar reference numerals. Therefore, for the sake of brevity, the description of elements that Fig. 2 and Fig. 3 are common, is omitted. The description of Fig. 3 is limited to elements that are derived from the elements of Fig. 2 are different.

[0034] The powertrain 300 includes a dual-clutch, dual-countershaft transmission 308. The transmission 308 is essentially an automatically actuated manual transmission. The control unit 12 actuates the first clutch 310, the second clutch 314, and a shift mechanism 315 to select between gears (e.g., 1st-5th gear) 317. The first clutch 310 and the second clutch 314 can be selectively opened and closed to shift between the gears 317.

[0035] The systems of Fig. 1-3 may include torque sensors, which may be the basis for adjusting driveline operation. Alternatively, the torque converter itself may be used as a torque sensor when the torque converter clutch 212 is fully disengaged. In particular, the output torque of an open torque converter is a function of the input and output speeds, the impeller and turbine speeds, where the impeller is the torque converter input and the turbine is the torque converter output. In the application of Fig. 2 / 3 the impeller speed is equal to the measured DISG speed because the DISG rotor output shaft is the impeller input shaft, and the turbine speed is measured and used in the transmission clutch control.

[0036] Additionally, given the open torque converter input and output speed characterization, the open torque converter output torque can be controlled by controlling the torque converter impeller speed as a function of the torque converter turbine speed. The DISG can be operated in a speed feedback mode to control the torque converter torque. For example, the commanded DISG speed (e.g., the same as the torque converter impeller speed) is a function of the torque converter turbine speed. The commanded DISG speed can be determined as a function of both the DISG speed and the turbine speed to deliver the desired torque at the torque converter output.

[0037] Drivetrain disturbances in the systems of Fig. 1-3 can also be reduced via the driveline disconnect clutch. One example method opens the torque converter clutch before actuating the driveline disconnect clutch. The driveline disconnect clutch may be opened, for example, when the engine is commanded to shut down, either during a vehicle regenerative braking condition and / or when the vehicle comes to a stop and the engine is shut down.

[0038] In another example, during regenerative braking, the driveline disconnect clutch may be open, the engine may be stopped, and the torque converter may be locked to increase the braking torque that can be absorbed in the DISG 240. After the engine is shut down, the driveline disconnect clutch remains open until the engine restart process begins. During engine restart, the driveline disconnect clutch may be partially closed until the first combustion event in a cylinder to start the engine. Alternatively, the driveline disconnect clutch may be partially closed until the engine reaches a predetermined speed after combustion is initiated in a cylinder. Once engine combustion is sufficiently restarted and the engine and driveline disconnect clutch speeds are sufficiently close (e.g.,within a threshold speed value), the capacity of the driveline disconnect clutch to close and hold without slippage is increased. During driveline disconnect clutch increase, torque disturbances may be present at the driveline disconnect clutch output. Consequently, torque feedback from the open torque converter or a torque sensor may be the basis for setting a DISG speed commitment. Operating the DISG in a speed control mode may allow desired torque values to be maintained with more consistency until the driveline disconnect clutch is fully closed. After the driveline disconnect clutch is closed, the torque converter clutch (TCC) may be locked based on a locking scheme (e.g., the TCC may be applied based on accelerator pedal position and vehicle speed).

[0039] In this way, the torque converter clutch can be fully opened before the engine restart process begins. The torque converter clutch can be closed after the engine restarts and the driveline disconnect clutch has fully closed. Furthermore, while the driveline disconnect clutch is being closed, the pressure at the driveline disconnect clutch is known (as it is commanded by the controller), and thus an estimate of the average driveline disconnect clutch torque is available. To further improve operation, this estimate of driveline disconnect clutch torque or capacity can be used by the controller as a feedforward input to the DISG feedback speed control to improve disturbance suppression response.The driveline disconnect clutch capacity, based on a torque estimate, can then be added as an input to an internal torque feedback loop in the electric machine (DISG). The internal loop is an internal current loop that can be the basis for improving the DISG's response when the DISG is in speed feedback mode.

[0040] In this way, an example method for operating a vehicle having a powertrain such as the one described in relation to Fig. 2-3, the method first comprises operating with the vehicle stopped or at a speed below a threshold, and with the engine at rest and the driveline disconnect clutch open. With the torque converter fully unlocked, the method next includes receiving a request to launch the vehicle, such as based on a driver pedal input increasing above a threshold amount. In response, the engine is cranked and started with one or more of the DISG 240 and a starter motor while the driveline disconnect clutch is closed, again with the torque converter still unlocked.During this process, torque feedback from the torque converter input / output speeds is used to estimate the torque at shaft 241, which is compared to a desired torque value, and creates an adjustment at a speed setting of the DISG 240, which is in speed control mode. The speed setting may, for example, be an adjustment parameter that drives a torque error between the estimated and desired torque at shaft 241 toward zero.

[0041] In addition to the above process, additional control actions may also be taken, particularly with regard to lash crossing. For example, if the driver depresses the accelerator pedal while the vehicle is in a regeneration mode with the engine off (e.g., at rest), the driveline transitions from negative torque to positive torque, the engine is started, and the driveline disconnect clutch closes, all of which are coordinated to introduce minimal torque disturbances to the wheels. Under select conditions, these actions are performed while the transmission 208 is held in a fixed gear (e.g., without changing the transmission gear). However, starting the engine and lash crossing may generate such disturbances.Intrinsically, during the transition, driveline torque can be controlled from a small negative torque to a small positive torque during the clearance transition and then to the requested torque. However, such engine torque limitation can introduce a delay in delivering the driver-requested torque, which, when added to the engine restart delay, can cause significant driver dissatisfaction.

[0042] One method may utilize coordination of the capacity of the torque converter clutch 212 and the output of the DISG 240. For example, the timing of the DISG's transition from torque control to speed control may be aligned with engine restart conditions and the transition through the lash range to mitigate driveline disturbances caused by the engine start and lash range transition.

[0043] In one example, operation is provided for conditions where the driver applies the brake and the vehicle is in a regeneration mode, the engine is off, the driveline disconnect clutch is fully open, and the DISG is absorbing torque. The DISG generates the desired level of braking torque (and stores the generated electricity, for example, in the battery). During these conditions, the driveline is subjected to negative torque and the torque converter lock-up clutch 212 is locked. The amount of negative torque at the DISG may be increased and applied by the driveline to enhance regeneration. The amount of negative torque may be based on a desired wheel braking torque for the present operating conditions. The negative braking may be based on a degree to which the driver applies a brake.However, negative braking can also occur while the driver has released both the brake pedal and the accelerator pedal.

[0044] When the driver releases the brake (if applied) and depresses the accelerator pedal, the vehicle transitions to engine-on operation, with positive driveline torque providing a requested torque level. As stated above, during this transition, without transmission gear changes, the torque traverses the zero torque (slack zone) and the engine is cranked and started. The inventors here have recognized that the engine cranking torque disturbance is upstream of clutch 212, but the lash disturbance is downstream of clutch 212. The capacity of clutch 212 can be coordinated with the speed of the DISG to mitigate these driveline disturbances.

[0045] For example, the capacity of the TCC 212 can be reduced sufficiently to allow controlled slip when the regeneration torque is reduced. Such operation can help isolate the driveline from the engine cranking torque disturbance. As the DISG regeneration torque transitions from the current value to zero torque, the driveline can transition from a large negative torque to near-zero torque. Near zero torque, the driveline can enter the lash region. Control of the DISG is then switched from torque control mode to speed control mode, and the torque converter impeller speed (Ni) is set to a fixed speed above the torque converter turbine speed (Nt).

[0046] Adjusting the torque converter impeller speed in this manner creates a small positive torque while crossing the lash range and reduces the driveline disturbance associated with crossing the lash range. The desired DISG speed may be increased to deliver torque to the wheels and provide some vehicle acceleration. An estimate of the amount of torque required to crank the engine may be determined by the controller to provide a feedforward DISG torque command. The feedforward DISG torque command may reduce speed disturbances to the torque converter impeller when the driveline disconnect clutch is engaged and the engine is cranking. The driveline disconnect clutch capacity is adjusted to reduce driveline disturbances.Once the engine has started and the driveline disconnect clutch is closed, the engine can be transferred to torque control and deliver the desired torque.

[0047] As mentioned above with regard to the system of Fig. For example, as described in sections 1-3, torque disturbances may occur when the driveline disconnect clutch is applied. Torque disturbances can lead to degraded drivability and NVH. Torque disturbances (e.g., due to clutch application error or clutch slippage, or an error between commanded and actual engine torque) at the driveline disconnect clutch output can be transmitted to the transmission input and wheels as a function of the transmission clutch state (e.g., degree of driveline disconnect clutch engagement, such as based on pressure or slip ratio) and the transmission gear ratio.

[0048] The torque generated by the DISG 240 may, in some examples, be a function of three-phase current. The torque at the DISG output shaft 241 is a sum of the DISG output torque and the torque at the DISG or electric machine input. The DISG may be commanded by a powertrain control module (e.g., controller 12) to operate in either a speed feedback mode or a torque mode. The controller provides the commanded speed or torque. The controller or an inverter uses feedback from either the DISG speed sensor or the DISG current to generate the desired speed or torque.

[0049] For example, DISG torque may be output from a function or table that includes empirically determined values of DISG torque based on DISG speed and DISG current. In some designs, the DISG output is connected to a launch clutch that is modulated during shift events to shape or smooth the DISG output torque before it is transmitted to the wheels. In other applications, the DISG output is connected to a torque converter 206 with a lock-up clutch. In designs that use a launch clutch instead of a torque converter, the launch clutch's ability to accurately and quickly control clutch torque at low torque levels can be challenging. For example, the launch clutch may slip in the presence of the maximum output torque of the engine plus DISG. Therefore, the launch clutch may be designed with a high torque capacity.However, it may be difficult to accurately control the launch clutch at low torque levels that may be used during engine restart and during vehicle launch from zero and / or low vehicle speeds.

[0050] One method for adjusting or controlling a launch clutch is to use a torque sensor mounted on the launch clutch input shaft. The torque sensor installation deposits a molded magnetic layer on the launch clutch input shaft, which produces an output voltage proportional to the shaft torque. The voltage is read by a non-contact sensor(s) and sensing system. The torque signal from the torque sensor can then be used to operate the DISG in a closed-loop torque feedback mode to cancel torque disturbances appearing at the driveline disconnect clutch output (DISG input). If the automatic transmission uses a torque converter clutch at the transmission input, a torque sensor may be mounted on the torque converter input shaft.The torque converter input shaft torque sensor can be used to provide feedback in the DISG control unit to suppress torque disturbances transmitted through the driveline disconnect clutch.

[0051] As described here, the engine can be shut down to zero speed (and the driveline disconnect clutch opened) to reduce fuel consumption when the driver releases the accelerator pedal. The engine is therefore shut down when the vehicle comes to a stop, or at another time when torque from the DISG is sufficient to accelerate the vehicle or overcome road load. When the driver applies the accelerator pedal and the desired torque exceeds that which the DISG can provide, the engine is restarted to supplement the DISG output torque. In addition, the engine can be restarted during a coasting condition when the battery state of charge drops below a minimum threshold.The engine can be restarted to provide positive driveline torque and provide torque to allow the DISG to operate as a generator to recharge the battery. During the engine restart process, depending on operating conditions, either the driveline disconnect clutch or a separate starter motor can be used to crank the engine, as described here. Once combustion begins in the engine, either the engine is accelerated to match the DISG input speed, or driveline disconnect clutch engagement / slip is controlled by controlling clutch pressure to pull the engine up to the DISG input speed. When the driveline disconnect clutch closes, a large torque disturbance can be created at the driveline disconnect clutch output, which can then be transmitted to the DISG output.A torque disturbance can potentially be transmitted to the transmission output and wheels, degrading vehicle drivability and NVH.

[0052] Various methods can be used to reduce the impact of this engine restart torque disturbance, such as those previously described herein. Alternatively, or additionally, one method for reducing the amplitude of the engine restart torque disturbance at the driveline disconnect clutch output is to match the engine crankshaft speed to the driveline disconnect clutch output or DISG speed (since the two are connected by a shaft) before the driveline disconnect clutch is closed. One such method utilizes the differential relationship of the driveline disconnect clutch output torque to the driveline disconnect clutch speed. Specifically, the driveline disconnect clutch output torque is effectively multiplied by the sign of the difference between the driveline disconnect clutch input and output speeds. For example, it is approximately equal to the sign (crankshaft speed - DISG speed).The closer these speeds are matched, the lower the driveline disconnect clutch output torque.

[0053] Although such a method can be used to reduce the driveline disconnect clutch output torque disturbance, it operates to accelerate the engine speed to the driveline disconnect clutch output speed. The driveline disconnect clutch output speed can range from 750 to 3000 rpm. -1vary. Accelerating the engine to a speed within this range can delay engine-powered launch and response to driver accelerator pedal input. For example, until the driveline disconnect clutch is closed, the engine either delivers no torque at the transmission input or acts as a drag (e.g., if crankshaft speed < DISG speed, then the driveline disconnect clutch output torque is negative). If the driver presses the accelerator pedal (e.g., presses the accelerator pedal down) and the DISG does not have sufficient torque capacity at the existing DISG speed, then the desired torque cannot be delivered until the driveline disconnect clutch is closed and the engine can deliver positive torque.

[0054] Consequently, under some conditions, it may be desirable to use the driveline disconnect clutch to boost engine speed to DISG speed in order to close the driveline disconnect clutch more quickly and deliver positive engine torque at the DISG output. The difficulty with closing the driveline disconnect clutch while the engine is accelerating to DISG speed is that the torque at the driveline disconnect clutch output is a function of sign (crankshaft speed - DISG speed).When the DISG is used to accelerate the crankshaft and dual mass flywheel inertia, the difference between the engine combustion torque and the DISG torque applied to achieve a given level of acceleration appears at the DISG output as negative torque, which then suddenly changes sign to positive torque when the crankshaft (or dual mass flywheel output) speed exceeds the DISG speed.

[0055] A change in the driveline disconnect clutch output torque may create a torque spike at the DISG input, which may be transmitted to the transmission input and / or the wheels. Therefore, the DISG may operate as a torque disturbance suppression device to mitigate the engine restart torque increase. The torque at the DISG output is the sum of the DISG output torque and the driveline disconnect clutch output torque. Control of the DISG may be based on detecting the torque disturbance at one or more of the driveline disconnect clutch output, the DISG output, the torque converter output, and / or the transmission output. The torque sensor may enable the DISG to directly suppress the torque disturbance. Such torque sensing may be provided by a non-contact transmission shaft torque sensor.

[0056] If such a sensor is applied to the shaft between the driveline disconnect clutch and the DISG rotor, the sensed torque may be input to the DISG controller to generate an opposing torque to cancel the engine restart driveline disconnect clutch output torque peak. Alternatively, the torque sensor may be located on the shaft between the DISG rotor and the torque converter (or impeller). In such an example, the inertia and acceleration of the DISG rotor are included and accounted for in the disturbance cancellation torque calculation. A transmission input or output shaft torque sensor may further be applied. If a transmission output shaft torque sensor is applied, the disturbance cancellation torque term may include compensation for the transmission inertias and, optionally, the clutch conditions.

[0057] With reference to Fig. 4 is a flowchart of an example method for operating a vehicle powertrain with the methods of Fig. 5-47. The procedure of Fig. 4 and the following methods may be implemented as executable instructions in a non-volatile memory of the type described in Fig. 1-3 shown control unit 12. Vertical markers such as T0-T8, which are shown in Fig. 10 further indicate time points of interest during the following sequences shown.

[0058] At 402, method 400 determines operating conditions. The operating conditions may include, but are not limited to, torque request, engine speed, engine torque, DISG speed and torque, vehicle speed, ambient temperature and pressure, and battery state of charge. The torque request may be determined from the accelerator pedal 130 and from the controller 12 of Fig. 1. The method 400 proceeds to 404 after the operating conditions are determined.

[0059] At 404, method 400 provides driveline operation and operating parameters according to the methods of Fig. 5-8. In particular, method 400 adjusts driveline operation in response to route conditions and / or driver behavior. Method 400 proceeds to 406 after driveline operation and operating conditions are adjusted.

[0060] At 406, method 400 sets the driveline or powertrain operation for the vehicle mass, as in Fig. 9 and Fig. 10. In one example, the timing and conditions for engine stopping may be adjusted in response to vehicle mass so that driveline wear and the number of driveline disconnect clutch state changes may be reduced. Method 400 proceeds to 408 after driveline operation is adjusted for vehicle mass.

[0061] At 408, method 400 assesses whether or not an engine start is desired. An engine start may be requested via a driver key input or driver push-button input having a single function of requesting an engine start and / or stop. Alternatively, an engine restart may be automatically requested by controller 12 based on operating conditions that do not include driver actuation of a device having a single function of requesting an engine stop or start. For example, controller 12 may request an engine start in response to a driver releasing the vehicle brake pedal or in response to a battery state of charge. Thus, a request to restart the engine may be initiated via inputs having functions other than simply requesting an engine start.If method 400 judges that an engine restart is requested, method 400 proceeds to 410. Otherwise, method 400 proceeds to 418.

[0062] At 410, method 400 selects a device for starting an engine, as in Fig. 11 and Fig. 12. In one example, the engine may be started via a starter having a lower power output than the DISG. In another example, the engine may be started via the DISG while the lower power output starter remains disabled. Method 400 proceeds to 412 after the engine starting means is selected.

[0063] At 412, method 400 adjusts the fuel injection timing of one or more direct fuel injectors that supply fuel to an engine, as in Fig. 13 and Fig. 14. The fuel injection timing is adjusted to provide a single or multiple fuel injections during a cycle of a single cylinder. By adjusting the fuel injection timing, the engine speed profile during engine startup (e.g., engine acceleration from cranking speed (e.g., 250 rpm -1 )) to the desired engine idle speed. Method 400 proceeds to 414 after the fuel injection timing is set.

[0064] At 414, method 400 judges whether or not the engine start is related to a transmission shift. For example, method 400 judges whether it is desirable to start the engine based on shifting from one transmission gear to another transmission gear. If method 400 judges that it is desirable to start the engine based on a transmission shift or predicted transmission shift, method 400 proceeds to 416. Otherwise, method 400 proceeds to 418.

[0065] At 416, method 400 starts the engine during the transmission shift, as in Fig. 15-18. In one example, the engine may be started before the gear clutches are opened or closed during a shift. Method 400 proceeds to 418 after the engine is started.

[0066] At 418, method 400 provides dual mass flywheel (DMF) compensation. Further, method 400 may provide driveline disconnect clutch compensation. DMF compensation may dampen torque transfer through the DMF by controlling DISG torque and / or DISG speed and driveline disconnect clutch torque. DMF compensation is provided as described in Fig. 19-22. Method 400 proceeds to 420 once DMF compensation is initiated.

[0067] At 420, method 400 judges whether or not it is desirable to stop engine rotation. Method 400 may judge that it is desirable to stop engine rotation during low torque demand conditions and / or other conditions. Method 400 proceeds to 422 if it is judged desirable to stop engine rotation. Method 400 proceeds to 420 if it is judged not to stop engine rotation.

[0068] At 422, method 400 adjusts the engine stop profile. In one example, the engine speed is adjusted during engine deceleration to a zero speed such that the engine position at zero engine speed is desired for restarting the engine. The engine stop profile may be adjusted as in Fig. 23-26. Method 400 proceeds to 424 after the engine stop profile is selected and / or set.

[0069] At 424, method 400 adjusts powertrain operation for rollback control conditions. In one example, the powertrain is selectively adjusted in response to vehicle road grade. Method 400 proceeds to exit after the powertrain is adjusted in response to vehicle road grade.

[0070] At 430, method 400 judges whether or not driveline vehicle braking is desired. Method 400 may judge that it is desired to provide driveline vehicle braking when the vehicle is descending a hill or during other conditions. If method 400 judges that it is desired to brake the vehicle via the driveline, method 400 proceeds to 432. Otherwise, method 400 proceeds to 434.

[0071] At 432, method 400 adjusts DISG and engine operation to provide a desired level of vehicle braking across the driveline, as in Fig. 29A-36. In one example, vehicle braking is provided via the DISG when the battery state of charge (SOC) is less than a threshold level. Method 400 proceeds to 434 after vehicle braking is provided via the powertrain.

[0072] At 434, method 400 assesses whether or not to enter or exit an idle mode. In one example, the idle mode may be described as a mode in which the engine is operating at an idle idle speed (e.g., burning air and fuel) while the driveline disconnect clutch is open. The idle idle speed is lower than the engine idle speed when the engine is combusting an air / fuel mixture and the driveline disconnect clutch is closed. Additionally, the engine may be operating in an Atkinson cycle mode while in the idle mode. Further, in some examples, spark timing may be advanced to near or to a minimum spark timing for best engine torque (MBT).In one example, the idle mode may be entered when the DISG torque is within a predetermined range of a threshold DISG torque. Method 400 proceeds to 436 if it is judged desirable to enter or exit the idle mode. Otherwise, method 400 proceeds to 438.

[0073] At 436, method 400 may operate the engine and driveline in an idle mode in which the engine is operating at an efficient operating condition and in which the driveline disconnect clutch is open while the DISG is providing torque to the vehicle driveline, as in Fig. 38. Alternatively, the method 400 may exit the idle mode as described in Fig. 39. Method 400 proceeds to 438 after entering or exiting the idle mode.

[0074] At 438, method 400 judges whether or not to adjust the driveline disconnect clutch transfer function. In one example, method 400 judges whether or not to adjust the driveline disconnect clutch transfer function during selected conditions, such as during engine idle or engine stop conditions. If method 400 judges that it is desirable to adjust the driveline disconnect clutch transfer function, method 400 proceeds to 444. Otherwise, method 400 proceeds to 440.

[0075] At 444, method 400 sets or adjusts the transfer function of the driveline disconnect clutch, as in Fig. 42-45. In one example, the driveline disconnect clutch transfer function describes the torque transfer of the driveline disconnect clutch based on the input torque to the driveline disconnect clutch and the pressure provided to the clutch (e.g., the hydraulic oil pressure provided to the driveline disconnect clutch or the duty cycle of an electrical signal provided to the driveline disconnect clutch). Method 400 proceeds to exit after the driveline disconnect clutch transfer function is set or adjusted.

[0076] At 440, method 400 operates the engine and DISG to deliver a desired torque to the input of the transmission. In one example, the engine and DISG operate depending on the driveline torque request provided by a driver and / or the controller. For example, if 35 Nm of driveline torque is requested at the torque converter impeller, the DISG may deliver 10 Nm to the driveline, while the engine delivers the remaining 25 Nm to the driveline. Alternatively, the DISG or engine may deliver the full 35 Nm to the driveline. The operating conditions of the engine and / or DISG may also be considered to determine the amounts of torque output by the engine and DISG. Method 400 proceeds to 442 after the engine and DISG operating modes, speeds, and torques are output.

[0077] At 442, method 400 adjusts the engine and DISG torque to provide a desired torque at the torque converter impeller. In one example, the torque at the torque converter impeller is estimated via a torque sensor. In other examples, the torque converter operating state is a basis for estimating the torque at the torque converter impeller. The torque converter impeller torque estimate is as in Fig. 21. The estimated transmission impeller torque is subtracted from a desired transmission impeller torque to provide a torque converter impeller torque error. The engine torque and / or the DISG torque are adjusted in response to the torque converter impeller torque error to decrease the torque converter impeller torque error toward zero. Method 400 proceeds to exit after the driveline torque is adjusted.

[0078] With reference to Fig. Figure 5 shows a schematic diagram of sample information that may be encountered while driving from one location to another. The sources of the Fig. 5 information represents the information in Fig. 6-8 are available. Furthermore, the methods shown in Fig. 6 shown information sources and devices for the Fig. 1-3 shown systems are available.

[0079] In this example, the vehicle 290 may travel route number one 501 or route number two 502 to a first or a second destination, respectively. The vehicle 290 may have a solar charging system 504 for charging the energy storage device 275 located in Fig. 2. The solar charging system may include solar panels and other associated devices. Furthermore, the vehicle 290 may include an inductive charging system 514 for charging the energy storage device 275 shown in Fig. 2. The inductive charging system 514 can receive charge from a power source external to the vehicle while the vehicle is moving. The vehicle 290 also includes a receiver 503 for receiving signals originating from outside or inside the vehicle 290.

[0080] Vehicle route number one includes multiple information sources, objects, and elements that may be the basis for selectively operating certain powertrain components. For example, vehicle 290 may receive global positioning system (GPS) information from satellite 505 during a course of travel. The GPS system may provide information to processor 12, as shown in Fig. 1, allow road gradients and distances along route number one to be determined. Processor 12 may also store information regarding vehicle stops based on signs or signals 506 during a course of travel so that when vehicle 290 retraces route number one, the information is available to determine when the vehicle stops, starts, accelerates, decelerates, or travels at a substantially constant speed (e.g., ± 5 MPH).

[0081] The vehicle 290 may also estimate an amount of charge that will be delivered by the solar system 504 via the sun 507 to the energy storage device 275 while traveling route number one. For example, if the vehicle begins traveling route number one at 1:00 p.m., generating 1 watt / minute, and it is expected to take one hour to travel route number one, it may be estimated that 60 watts will be generated during the course of traveling route number one. Further, the estimated power generated during the course of the trip may be adjusted based on the time of day and the forecast weather. For example, an amount of electrical power generated at a specific time of day may be extrapolated to an amount of power generated later that day based on empirically determined solar tables and the time of day.

[0082] The vehicle 290 may also record and store road conditions 508 in memory or receive them from external sources such as GPS. Road conditions 508 may include road gradient information, road surface information, and speed limits. The vehicle 290 may also receive or measure the ambient temperature from temperature sensor 509. The temperature sensor 509 may be integrated into the vehicle 290 or it may be located external to the vehicle 290.

[0083] Finally, on route number one, vehicle 290 may receive electrical energy at power source 510. Power source 510 may be a residential or commercial power source that supplies power to vehicle 290 from an electrical grid at destination one. Vehicle 290 may have stored information, including a stored database and / or information stored from previous trips to destination one, indicating that vehicle 290 may be recharged at destination one. Such information is useful for determining how electrical charge stored in vehicle 290 is utilized during the course of a trip.

[0084] In another example, vehicle 290 may travel to destination two via route number two. Vehicle 290 may be programmed to detect that it is traveling to destination two. Along route number two, vehicle 290 may receive weather, road condition, ambient temperature, and GPS data from infrastructure 515. The infrastructure may include broadcast towers and highway / roadside broadcast devices. Vehicle 290 may also receive road conditions from handheld devices 513 such as telephones, computers, tablet devices, and / or personal organizers. In some situations, vehicle 290 may receive road conditions and destination information (e.g., availability of electric charging stations) from other vehicles 511 providing information via a transmitter 512.

[0085] Consequently, a vehicle can receive information at the beginning of a journey and throughout the journey, which can be a basis for controlling the driveline operation. Fig. 5 may, for example, be the basis for operating the driveline disconnect clutch 236, the DISG 240 and the engine 10 described in Fig. 2 are shown.

[0086] With reference to Fig. 6 is a flowchart of a method for operating a hybrid powertrain in response to information encountered while traveling from one location to another. The method of Fig. 6 can be stored in a non-volatile memory as executable instructions in the system of Fig. 1-3 must be saved.

[0087] At 602, method 600 determines vehicle operating conditions. The vehicle operating conditions may include, but are not limited to, engine speed, vehicle speed, ambient temperature, driver demand torque (e.g., torque requested by a driver via an input, which in some examples may also be referred to as desired driveline torque), and energy storage device state of charge (SOC). Further, the operating conditions may include selecting a route to a destination based on a driver input or by adjusting a current driving route based on driving routes taken during previous trips. Method 600 proceeds to 604 after the vehicle operating conditions are determined.

[0088] At 604, the method 600 acquires route information. The method 600 may receive route information such as road gradient, traffic light locations, other vehicle speeds, traffic assist locations, electric charging station locations, ambient temperature, and related traffic information from a variety of sources. The information sources may include, but are not limited to, internal memory of a control unit in the vehicle, personal handheld devices (e.g., personal organizers, tablets, computers, telephones), satellites, infrastructure, other vehicles, and traffic communication devices. In one example, a vehicle's route may be compared with routes stored in the control unit's memory. If the vehicle's current route matches a route stored in the control unit's memory, the control unit selects the destination and driving conditions (e.g.,(e.g., traffic lights, road gradient, charging facilities, etc.) from the route stored in memory without driver input. Method 600 proceeds to 606 after route information is acquired.

[0089] At 606, method 600 prioritizes the use of stored electrical energy based on opportunities to charge the electrical energy storage device along a selected travel route. Fig. 7 shows a manner for prioritizing the use of stored electrical energy. Prioritizing the use of stored electrical energy may include using only electrical energy during selected vehicle accelerations, so that hydrocarbon fuel usage may be reduced compared to simply basing the use of electrical energy on a desired torque demand. Further, prioritizing the use of stored electrical energy may include using substantially all of the available stored charge (e.g.,Reducing the energy storage device charge to a threshold amount of charge in the electrical energy storage device when the vehicle is within a predetermined distance of a route for externally charging the energy storage device, or during conditions where the energy storage device can be charged via kinetic energy (e.g., a downhill climb). Method 600 proceeds to 608 after the use of stored electrical energy is prioritized. In this manner, method 600 schedules the use of stored electrical energy before the vehicle reaches travel route conditions that facilitate the use of the stored electrical energy.

[0090] At 608, method 600 prioritizes charging the electrical energy storage device via an engine based on a travel route. For example, method 600 may operate an engine to propel a vehicle when an energy storage device SOC is low. Method 600 may further operate the engine without charging the energy storage device if method 600 determines that the energy storage device can be charged a short time later using vehicle kinetic energy during vehicle deceleration. Fig. 8 illustrates a manner for prioritizing charging of the electrical energy storage device. Method 600 proceeds to 610 after charging of the electrical energy storage device has been prioritized. In this manner, method 600 schedules charging of the electrical energy storage device before the vehicle reaches route conditions that facilitate charging of the electrical energy storage device.

[0091] At 610, method 600 prioritizes entry into the driveline idle mode based on the vehicle's travel route. In one example, method 600 retrieves information from 702 of method 700 to determine when the vehicle is expected to stop for less than a threshold amount of time. Further, method 600 may receive information regarding when the vehicle is expected to accelerate above a threshold rate after the vehicle stops for less than the threshold amount of time. Method 600 schedules entry into the idle mode (e.g., engine idling, driveline disconnect clutch open, and DISG providing requested torque to the vehicle driveline) based on locations in the travel route where the vehicle is expected to stop for less than a threshold amount of time and where the vehicle is expected to accelerate from the vehicle stop at a rate greater than a threshold rate.Method 600 proceeds to 612 after entry into the idle mode is scheduled. In this manner, method 600 schedules entry into the idle mode before the vehicle reaches route conditions that facilitate the idle mode.

[0092] At 612, method 600 operates the driveline disconnect clutch, the DISG, and the engine based on the scheduled and prioritized use of electrical energy stored in the energy storage device, the prioritized charging of the electrical energy storage device via the engine, and the entry into the idle mode. In other words, method 600 may open and close the driveline disconnect clutch, operate the DISG, and operate the engine based on expected vehicle and road conditions along a driving route. For example, if method 600 schedules entry into the idle mode at a specific stop during a driving route, method 600 opens the driveline disconnect clutch and enters the idle mode when the vehicle stops at the specific location.Further, method 600 opens the driveline disconnect clutch when the DISG is scheduled to provide torque to accelerate the vehicle without assistance from the engine in response to prioritizing the use of electrical energy stored in the electrical energy storage device. Still further, method 600 opens the driveline disconnect clutch in response to the vehicle being within a threshold distance before arriving at an electrical charging station so that energy from the electrical storage device may be used to propel the vehicle rather than the engine and hydrocarbons. Additionally, method 600 may open the driveline disconnect clutch in response to being within a threshold distance before arriving at a downhill grade.Method 600 proceeds to 614 after the driveline disconnect clutch operation is scheduled and executed based on vehicle and route conditions.

[0093] At 614, method 600 assesses whether or not a significant change in route and / or vehicle conditions occurred. A significant change in route or vehicle conditions may be the presence of an unexpected condition (e.g., an extended vehicle stop or an unexpected loss of battery charge) or the absence of an expected condition (e.g., no vehicle stop when a vehicle stop is expected). If method 600 assesses that a change in route or vehicle conditions occurred, the answer is yes, and method 600 returns to 602 so that prioritization of stored electrical energy, energy device charging, and entry into idle mode can be determined again. Otherwise, the answer is no, and method 600 proceeds to 616.

[0094] At 616, method 600 judges whether or not the vehicle is at its final destination for the trip. In one example, method 600 compares the vehicle's current location to a programmed destination. In another example, method 600 compares the vehicle's current location to an expected destination. If method 600 judges that the vehicle is at its destination, method 600 proceeds to the end. Otherwise, method 600 returns to 614.

[0095] In this manner, the operation of a hybrid powertrain can be adjusted according to a driving route and conditions along the driving route. Adjustments to the hybrid powertrain may include, but are not limited to, opening and closing a driveline disconnect clutch, charging an energy storage device via the engine, entering idle mode, and entering and exiting other driveline operating modes.

[0096] With reference to Fig. 7 is a flowchart of a method for prioritizing the use of stored electrical energy in a hybrid vehicle. The method bases the use of stored electrical energy on opportunities to charge an electrical energy storage device over a driving route. The method of Fig. 7 can be written to non-volatile memory as executable instructions in the system of Fig. 1-3 must be saved.

[0097] At 702, method 700 determines a number of vehicle stops and their locations on a travel route and estimates the regenerative energy supplied to the electrical energy storage device during vehicle stops and during other occasions (e.g., vehicle decelerations and during downhill driving). Method 700 may also estimate an expected amount of battery charging via a solar charging system. Further, method 700 determines a number of vehicle accelerations from the stop and an estimate of the electrical energy for acceleration from each vehicle stop. In addition, method 700 may store information about vehicle stops that are less than a threshold duration.

[0098] In one example, the number of vehicle stops and their locations are estimated based on a number of traffic lights and / or signs along the route, as determined by the Fig. 5. Specifically, in one example, the number of vehicle stops is determined from the number of traffic lights and / or signs along a travel route, multiplied by a value representing a reasonable percentage (e.g., 60%) of the traffic lights at which the vehicle actually stops. The number of accelerations from the stop is equal to the estimated number of vehicle stops. The amount of energy regenerated during each vehicle stop can be calculated based on the vehicle speed before the stop, the road gradient, and the vehicle mass (e.g., using E=1 / 2 mv 2, where E is the energy, m is the vehicle mass, and v is the vehicle speed, or alternatively F = m a + m g sin(θ) over the time interval, where m is the vehicle mass, a is the vehicle acceleration, g is the acceleration due to gravity, and θ is the road angle, which can be converted into a gradient). Similarly, the amount of energy required to accelerate the vehicle can be calculated based on the speed limit, the road gradient, and the vehicle mass (e.g., using F = m a + m g sin(θ) over the time interval or E = 1 / 2 m v 2 ) and then converted into electrical charge. Furthermore, energy obtained from solar or inductive devices along the route can be added to the total amount of charge available while driving the route. The number of traffic lights, their locations, and road gradient information can be accessed via the Fig. 5. Method 700 proceeds to 704 after the number of vehicle stops, vehicle accelerations, regenerated energy, and energy used to accelerate the vehicle at each vehicle stop location are determined.

[0099] At 704, method 700 assesses whether or not the energy storage device can provide energy to accelerate the vehicle to the speed limit after each vehicle stop determined at 702. In one example, the energy stored in the energy storage device plus the estimated amount of regenerative energy available along the travel route are added together. Driveline losses are subtracted from the sum of the stored energy and the regenerative energy, and the result is compared to the estimated amount of energy to accelerate the vehicle from all vehicle stops.If the amount of energy to accelerate the vehicle from all vehicle stops is greater than the sum of the stored energy and the regenerative energy, it may be determined that engine assistance may be required along the travel route and that the energy storage device may not have enough power stored to complete the trip along the route. If the energy storage device could not have enough power to accelerate the vehicle from all stops along the selected route, the answer is no and method 700 proceeds to 706. Otherwise, the answer is yes and method 700 proceeds to 708.

[0100] At 706, method 700 selects which accelerations from stop will be performed using energy from the energy storage device. In other words, method 700 decides during which vehicle accelerations the DISG will provide torque to the driveline. In one example, the selection of vehicle accelerations at which the DISG will operate is based on which accelerations from stop, when combined, require an amount of energy that most closely matches the amount of energy available from the energy storage device. For example, at the beginning of a trip, if an energy storage device stores X coulombs of charge and the first twenty-three vehicle accelerations are expected to use X coulombs of energy, the first twenty-three vehicle accelerations will be provided via the DISG and the energy storage device.However, it should be noted that the selected vehicle accelerations do not need to be consecutive in order. Rather, individual vehicle accelerations, operated via the DISG and the energy storage device, can be selected from any acceleration during the planned vehicle route.

[0101] In another example, the accelerations from the vehicle stop at which the DISG is operating with charge from the energy storage device are based on when energy from regeneration is available to charge the energy storage device and an expected amount of energy stored at the time of the vehicle stop. For example, if only a small amount of regenerative energy is expected during vehicle deceleration and the energy storage device charge at a vehicle stop is expected to be less than a threshold level, the DISG is not scheduled to accelerate the vehicle from that particular vehicle stop. Method 700 proceeds to 716 after vehicle accelerations from the vehicle stop at which the DISG is operating with charge from the energy storage device are determined.

[0102] At 708, method 700 determines a number and locations of accelerations of the moving vehicle not from the vehicle stop. Method 700 also estimates an amount of energy to accelerate the vehicle during each acceleration of the moving vehicle. The locations and number of accelerations of the moving vehicle may be determined from where changes in the speed limit occur over the course of the travel route. Thus, a number of accelerations of the moving vehicle may be determined from each increase in the speed limit posted on the travel route. The change in vehicle route speed may be stored in a map database and retrieved from memory. Further, the vehicle route may be determined based on the shortest distance or time between the current location of the vehicle and a requested destination.

[0103] Method 700 also determines the energy to accelerate the vehicle at each of the vehicle acceleration locations. The amount of energy to accelerate the vehicle can be calculated based on the speed limit, road grade, and vehicle mass (e.g., using F=m a + m g sin(θ) over the time interval or E=1 / 2 mv 2 ). Method 700 proceeds to 710 after the number of accelerations during driving, the locations of the accelerations of the moving vehicle, and the energy estimated to accelerate the vehicle at each acceleration location of the moving vehicle are determined.

[0104] At 710, method 700 assesses whether or not the energy storage device can provide the energy to accelerate the vehicle to the speed limit after each acceleration of the moving vehicle is determined at 708. In one example, any remainder of the amount of energy stored in the energy storage device plus the amount of regenerative energy estimated to be available along the travel route minus the energy to accelerate the vehicle at each stop determined from 702 is compared to an amount of energy to accelerate the vehicle at all acceleration locations of the moving vehicle.If the amount of energy to accelerate the moving vehicle at each location is greater than the remainder of 702, it may be determined that engine assistance may be required along the travel route and that the energy storage device may not have sufficient power stored to provide electrical power over the route. If the energy storage device does not have sufficient power to accelerate the vehicle from all accelerations of the moving vehicle along the selected route, the answer is no and method 700 proceeds to 714. Otherwise, the answer is yes and method 700 proceeds to 712.

[0105] At 712, method 700 selects where during the travel route the remaining energy stored in the energy storage device and generated during regeneration (e.g., during vehicle deceleration) may be consumed. For example, if the energy storage device has X coulombs of remaining charge above a threshold amount of charge and a charging source is available at the vehicle destination, method 700 determines at which location along the travel route the remaining charge will be consumed. In one example, consumption of the remaining charge stored in the energy storage device and not used to accelerate the vehicle is consumed starting at a location based on the destination.For example, if the vehicle is expected to have Z coulombs of excess charge and the vehicle is using 1 / Z coulombs per mile, the driveline disconnect clutch is opened and the DISG begins discharging Z coulombs Z miles from the destination, and the engine is stopped. In this manner, method 700 decreases the energy stored in the energy storage device in a manner that may reduce hydrocarbon fuel consumption because the stored electrical energy consumed is increased by consuming the energy storage charge down to a threshold charge level (e.g., a minimum battery charge level). Further, because the vehicle can be recharged from the grid at the destination, the energy storage device can be charged with power from a more efficient source than the engine.

[0106] On the other hand, if method 700 determines that no charging source is present at the destination, the driveline disconnect clutch is closed and the energy may remain stored in the electrical energy storage device. Method 700 proceeds to 716 after determining where excess charge not consumed during vehicle acceleration will be consumed.

[0107] At 714, method 700 selects which accelerations of the moving vehicle will be performed using energy from the energy storage device. In other words, method 700 decides during which accelerations of the moving vehicle (e.g., vehicle accelerations other than from a stop) the DISG will provide torque to the driveline. In one example, the selection of the accelerations of the moving vehicle during which the DISG will operate is based on which accelerations of the moving vehicle, in combination, require an amount of energy that most closely corresponds to the amount of energy remaining after energy has been provided to accelerate the vehicle for vehicle accelerations from the vehicle stop.For example, at the start of a trip, if an energy storage device stores X coulombs of charge and there are twenty-three vehicle accelerations from the stop that are expected to use Y coulombs of energy (e.g., if Y is less than X), the first twenty-three vehicle accelerations from the vehicle stop will be provided via the DISG and the energy storage device. If Z coulombs are expected to remain after the vehicle accelerates at each stop and the energy consumption sum of the energy of the moving vehicle's acceleration is greater than Z coulombs, Z coulombs of charge will be provided for the first few moving vehicle accelerations that consume up to Z coulombs of charge. It should be noted, however, that the selected moving vehicle accelerations at which the excess charge is supplied need not be consecutive in order.Method 700 proceeds to 716 after the accelerations of the moving vehicle, DISG assistance, and charge received from the energy storage device are selected.

[0108] At 716, method 700 schedules DISG assistance for the driveline to accelerate or maintain the vehicle in motion based on the determined acceleration locations and steady-state energy utilization. DISG assistance may be provided when the driveline disconnect clutch is in an open state or during a closed state. Further, the DISG may provide all or only a portion of the torque to propel the vehicle.

[0109] In this way, it is possible to schedule and prioritize the use of stored electrical energy. In this example, vehicle accelerations from zero speed have higher priority than accelerations of the moving vehicle or the use of stored electrical energy during steady-state driving conditions. Such operation can allow the engine to operate under more efficient operating conditions, such as steady-state speed and load conditions.

[0110] With reference to Fig. 8 is a flowchart of a method for scheduling and prioritizing charging of an electrical energy storage device via an engine based on a travel route. The method of Fig. 8 can be stored in a non-volatile memory as executable instructions in the system of Fig. 1-3 must be saved.

[0111] At 802, the method 800 retrieves information from 702 and 708 from Fig. 7 to determine when the electrical energy storage device is expected to require charging. In particular, if at 702 of Fig. 7, it is determined that the vehicle cannot accelerate from zero speed from all conditions, method 800 may determine that the electrical energy storage device needs to be recharged at a location of vehicle acceleration along the travel route where the SOC is reduced to less than a threshold level. Likewise, method 800 may estimate where along the travel route the SOC is reduced to less than a threshold level during acceleration while cruising or during steady-speed driving conditions. Method 800 proceeds to 804 after determining when the electrical energy storage device is expected to require recharging.

[0112] At 804, method 800 assesses whether or not the electrical energy storage device has sufficient charge to power the vehicle throughout the trip. In one example, the SOC is calculated using an estimate of the energy to power the vehicle throughout the trip based on F = m a + m g sin(θ) over the time interval or E = 1 / 2 mv 2 compared. If method 800 judges that the electrical energy storage device has sufficient stored charge to operate the DISG throughout the entire travel route, the answer is yes and method 800 proceeds to exit. Otherwise, the answer is no and method 800 proceeds to 806.

[0113] At 806, the method 800 determines sections and locations of the driving route where charging of the energy storage device via the engine is most efficient and where the SOC is expected to be low. It may be determined at 702, 708, and 714 of Fig. 7 certain locations, the SOC is expected to be low. The locations and sections of the driving route where charging of the energy storage device may be most efficient may be based on empirically determined engine speeds and loads where the engine consumes the least fuel for each mile driven. For example, if it is determined that the engine consumes the least fuel for each mile driven at 2200 rpm -1operates between an engine load of 0.2 and 0.3, it can be determined that the energy storage device should be recharged via the engine at a vehicle speed at which the engine is at 2200 min -1and between 0.2 and 0.3 load when the DISG charges the energy storage device. Thus, in one example, method 800 selects locations and portions of the driving route for charging the energy storage device based on locations of roads with constant vehicle speeds (e.g., a 55 MPH speed limit) for extended durations (e.g., 10 miles) that correspond to efficient engine operating conditions. In some examples, vehicle speeds are selected where engine efficiency is expected to be greater than a threshold efficiency. The engine efficiency at a particular vehicle speed may be empirically determined and stored in memory. Method 800 proceeds to 808 after portions of the driving route where charging of the energy storage device via the engine is most efficient are determined.

[0114] At 808, method 800 determines locations and portions of the travel route where the charge supplied by the engine to the energy storage device can be fully utilized. For example, method 800 estimates the amount of energy that can be used to propel the vehicle from its current location, where charging of the energy storage device via the engine is considered, to the final destination. The energy storage device can be recharged at any location along the travel route where the engine efficiency is greater than a threshold efficiency and where the amount of energy to propel the vehicle from its current location to its destination is greater than a threshold amount of charge (e.g., the charge capacity of the energy storage device).Method 800 proceeds to 810 after identifying portions of the travel route where the charge supplied from the engine to the energy storage device can be fully utilized.

[0115] At 810, the method 800 selects locations and portions of the travel route where the engine can most efficiently supply charge to the energy storage device and where the charge supplied by the engine to the energy storage device can be fully utilized during the travel route. For example, if the energy storage device is determined to store enough energy to propel the vehicle for 10 miles, and the vehicle is 20 miles from the destination and operating at an efficiency greater than a threshold efficiency, the location 20 miles from the destination may be selected as the location for charging the energy storage device via the engine. The driveline disconnect clutch is closed when the engine charges the electrical energy storage device via the engine. The method 800 proceeds to the end after locations for charging the electrical energy storage device via the engine are selected.

[0116] In this way, charging of the energy storage device via the engine may be prioritized based on where the engine can operate efficiently during charging and based on the vehicle location being a distance from the destination that allows for the use of any charge that can be delivered to the energy storage device via the engine. Furthermore, prioritization may be the basis for determining locations of driveline mode changes.

[0117] Consequently, the procedures and systems of Fig. 1-8 operating a hybrid vehicle, comprising: actuating a driveline disconnect clutch in response to a vehicle destination. In this way, driveline operation may be improved. The method includes actuating the driveline disconnect clutch comprising opening the driveline disconnect clutch in response to information that a charging device is available at the vehicle destination. The method further includes stopping an engine and decreasing an amount of charge stored in an energy storage device in response to an estimate of energy used by the hybrid vehicle powertrain to reach the vehicle destination. The method includes decreasing the amount of charge via operating a starter / generator integrated with the driveline.The method includes actuating the driveline disconnect clutch comprising closing the driveline disconnect clutch in response to information indicating that a charging device is not available at the destination. The method further includes closing the driveline disconnect clutch and charging an energy storage device in response to a location of the vehicle destination.

[0118] The procedures and systems of Fig. 1-8 also allow the operation of a hybrid vehicle, comprising: Receiving route information at a controller; and selectively actuating a driveline disconnect clutch in response to the route information. The method includes where the route information includes whether or not a charging station is available at a destination, and where selectively actuating the driveline disconnect clutch includes opening the driveline disconnect clutch in response to an amount of energy expected to be consumed by the hybrid vehicle to reach the destination.

[0119] In some examples, the method includes where the route information includes an indication of a hill grade and where the driveline disconnect clutch is maintained open in response to the indication of the hill grade. The method includes storing the route information in the controller from a previous trip over the route. The method further includes accessing the route information based on a current route of a vehicle and opening or closing the driveline disconnect clutch in response to the availability of charging facilities at a destination. The method also includes where selectively actuating the driveline disconnect clutch includes opening and closing the driveline disconnect clutch in response to a number of expected vehicle stops during routes.

[0120] In one example, the method includes where selectively actuating the driveline disconnect clutch comprises opening and closing the driveline disconnect clutch in response to a number of accelerations of the moving vehicle that do not include vehicle accelerations from the vehicle stop. The method includes where selectively actuating the driveline disconnect clutch comprises opening and closing the driveline disconnect clutch in response to a number of vehicle accelerations from the vehicle stop. Further, the method includes where the travel route information includes road grade information, and further includes storing charge in an electrical energy storage device in response to the travel route information.

[0121] The procedures and systems of Fig. 1-8 additionally provide operating a hybrid vehicle, comprising: assessing the state of charge (SOC) of an electrical energy storage device; receiving travel route information at a controller; and scheduling charging of the electrical energy storage device at a first location in response to the SOC and the travel route information prior to reaching the first location. The method also includes the hybrid vehicle receiving travel route information from a vehicle other than the hybrid vehicle. The method further includes operating a driveline disconnect clutch in response to the travel route information. The method further includes updating the scheduling of charging of the electrical energy storage device in response to a change in driving conditions. The method further includes scheduling discharging of the electrical energy storage device at a second location prior to reaching the second location.

[0122] With reference to Fig. 9 is a flowchart of a method for an example sequence for operating a hybrid vehicle powertrain in response to a varying vehicle mass. The method of Fig. 8 can be stored as executable instructions in a non-volatile memory in the system of Fig. 1-3. Furthermore, the procedure of Fig. 9 which in Fig. Provide the sequence shown in Figure 10.

[0123] At 902, method 900 determines vehicle operating conditions. The vehicle operating conditions may include, but are not limited to, engine speed, vehicle speed, energy storage device SOC, engine load, engine torque request, and vehicle acceleration. The operating conditions may depend on the Fig. 1-3. Method 900 proceeds to 904 after the vehicle operating conditions are determined.

[0124] At 904, method 900 determines the vehicle mass. In one example, the vehicle mass is based on the following equations:

[0125] When the vehicle acceleration is zero, Engine / driveline torque≈road load+grade-based torque Using: T_wh1=R_rr⋅M_v⋅g⋅sin(θ1)+T_rl1 where: T_wh1 = wheel torque at inclination angle = θ1 T_wh2 = wheel torque at inclination angle = θ2 R_rr = rolling radius of the driven wheel M_v = vehicle mass estimate g = gravitational constant θ1 = angle of inclination T_rl1 = Road load torque on the driven wheel on slope 1 T_rl2 = Road load torque on the driven wheel on slope 2

[0126] Then the vehicle mass estimate is: M_v=[(T_wh1−T_wh2)+(T_rl2−T_rl1)] / [R_rr*g*(θ1−θ2)]

[0127] In some examples, vehicle mass includes the mass of a vehicle and a trailer being towed by the vehicle. In other examples, vehicle mass is the mass of only the vehicle without a trailer. In some examples, vehicle mass may further include the mass of passengers in the vehicle and vehicle cargo. Engine / driveline torque may be determined from empirically determined torque maps or functions indexed using engine speed and load. For example, engine torque may be estimated by indexing a map of engine output torque indexed by engine speed and load. Method 900 proceeds to 906 after vehicle mass is estimated.

[0128] At 906, method 900 sets the energy storage device SOC threshold at which automatic engine stopping is permitted. In one example, the energy storage device SOC threshold is increased when the mass of the vehicle is increased, such that the vehicle's engine stops during vehicle deceleration conditions when the energy storage device is higher than a first threshold level. When the mass of the vehicle is decreased, the energy storage device SOC threshold is decreased such that the vehicle's engine stops during vehicle deceleration conditions when the energy storage device is higher than a second threshold level, where the second threshold level is less than the first threshold level. The energy storage device SOC threshold may be set proportional to a change in vehicle mass or as a function of vehicle mass. Fig. 10 shows two SOC threshold levels based on different vehicle masses. Method 900 proceeds to 908 after the energy storage device SOC threshold for engine stopping is set.

[0129] At 908, method 900 judges whether or not engine auto-stop conditions exist. In some examples, engine auto-stop conditions include conditions indicating vehicle deceleration, brake pedal depressing, the absence of accelerator pedal depressing, and an energy storage device SOC greater than a threshold level. If method 900 judges that engine auto-stop conditions exist, the answer is yes, and method 900 proceeds to 910. Otherwise, the answer is no, and method 900 proceeds to 912.

[0130] At 910, method 900 automatically stops the engine. The engine may be automatically stopped via stopping fuel and / or spark to the engine, without the driver requesting the engine stop via a device having a single function of stopping and / or starting the engine. Method 900 proceeds to 912 after the engine is stopped.

[0131] At 912, method 900 judges whether or not the engine has been automatically stopped. In one example, a bit is set in controller memory if the engine has been automatically stopped. If method 900 judges that the engine has been automatically stopped, the answer is yes, and method 900 proceeds to 914. Otherwise, the answer is no, and method 900 ends.

[0132] At 914, method 900 judges whether or not the vehicle mass is less than a threshold mass. In one example, the threshold mass is the vehicle mass of an unloaded vehicle plus mass adjustments for one or more people and a specified amount of cargo. If method 900 judges that the vehicle mass is less than a threshold mass, the answer is yes and method 900 proceeds to 916. Otherwise, the answer is no and method 900 proceeds to 922.

[0133] At 916, method 900 judges whether or not a friction brake application force is less than a threshold. Alternatively, at 916, method 900 judges whether or not a brake pedal is applied. If the friction brake application force is less than a threshold or if the brake pedal is not applied, the answer is yes, and method 900 proceeds to 918. Otherwise, the answer is no, and method 900 proceeds to exit.

[0134] At 918, method 900 maintains the engine in a stopped state and delivers a threshold amount of creep torque (e.g., a torque that moves the vehicle at a predetermined slow speed rate (2 mph) on a gentle incline) to the vehicle wheels via the DISG. Method 900 proceeds to 920 after the creep torque is output via the DISG.

[0135] At 920, method 900 provides a base amount of torque converter impeller torque in response to a driver demand torque. The base amount of torque converter impeller torque does not account for a change in vehicle mass. Further, in one example, the base amount of torque converter impeller torque is based on a driver input to an accelerator pedal (e.g., driver demand torque), and an amount of accelerator pedal deflection is converted to a torque converter impeller torque. In other examples, wheel torque, engine braking torque, and / or driveline-related torques may take the place of the torque converter impeller torque. The torque converter impeller torque is converted to a desired DISG current, and the current is provided to the DISG to provide the torque converter impeller torque.

[0136] At 922, method 900 judges whether or not the friction brake application force is less than a threshold. Alternatively, at 922, method 900 judges whether or not a brake pedal is applied. If the friction brake application force is less than a threshold, or if the brake pedal is not applied, the answer is yes, and method 900 proceeds to 924. Otherwise, the answer is no, and method 900 proceeds to exit.

[0137] At 924, the engine is restarted, the driveline disconnect clutch is closed, and at least a portion of the vehicle creep torque is provided by the engine. In some examples, the vehicle creep torque may be provided via the engine and the DISG. In other examples, the vehicle creep torque is provided via the engine only. Method 900 proceeds to 926 after the engine is started and at least a portion of the vehicle creep torque is provided by the engine.

[0138] At 926, method 900 provides an amount of torque converter impeller torque adjusted for vehicle mass in response to a driver demand torque. For example, method 900 provides a base amount of torque converter impeller torque plus an additional amount of torque based on the increase in vehicle mass. In one example, the additional amount of torque is empirically determined and stored in a table or function in controller memory indexed by vehicle mass exceeding the base vehicle mass. The torque converter impeller torque may be provided via the engine only or via the engine and the DISG. In one example, the desired torque converter impeller torque is provided by opening the engine throttle and supplying fuel to the engine in response to the desired torque converter impeller torque.In other examples, the desired torque converter impeller torque is provided via supplying an amount of current to the DISG and fuel to the engine and an amount of throttle opening. Method 900 proceeds to exit after the desired torque converter impeller torque is provided.

[0139] In this way, engine and driveline disconnect operation can be adjusted in response to a change in vehicle mass. Furthermore, engine stopping conditions based on SOC can also be adjusted based on vehicle mass.

[0140] With reference to Fig. 10 shows an example sequence for operating a hybrid vehicle powertrain in response to a varying vehicle mass. The sequence of Fig. 10 can be found in Fig. 10 shown procedure can be carried out, which is in the Fig. 1-3 described system is executed.

[0141] The first diagram from the top in Fig. Figure 10 is a graph of vehicle speed versus time. The Y-axis represents vehicle speed, and vehicle speed increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases in the direction of the X-axis arrow.

[0142] The second diagram from the top in Fig. Figure 10 is a graph of engine operating state as a function of time. The Y-axis represents the engine operating state. The engine is on and operating to combust an air / fuel mixture when the curve is at a higher level. The engine is off and not combusting when the curve is at a lower level. The X-axis represents time, and time increases in the direction of the X-axis arrow.

[0143] The third diagram from the top in Fig. Figure 10 is a graph of the vehicle brake application state as a function of time. The Y-axis represents the vehicle brake state. The vehicle brake pedal is applied when the curve is at a higher level. The vehicle brake pedal is not applied when the curve is at a lower level. The X-axis represents time, and time increases in the direction of the X-axis arrow.

[0144] The fourth diagram from the top in Fig. Figure 10 is a graph of the desired torque converter impeller torque as a function of time. The Y-axis represents the desired torque converter impeller torque, and the desired torque converter impeller torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases in the direction of the X-axis arrow.

[0145] The fifth diagram from the top in Fig. 10 is a graph of energy storage device state of charge (SOC) as a function of time. The Y-axis represents energy storage device SOC, and energy storage device SOC increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases in the direction of the X-axis arrow. Horizontal marker 1002 represents a minimum energy storage device SOC level at which the engine may be stopped and the driveline disconnect clutch opened when the vehicle mass increases, for example, via an increase in vehicle payload. Horizontal marker 1004 represents a minimum energy storage device SOC level at which the engine may be stopped and the driveline disconnect clutch opened when the vehicle mass is that of the unloaded base vehicle.Consequently, at lower SOC levels, the engine can be stopped and the driveline disconnect clutch opened when the vehicle is at its base mass. Conversely, as the vehicle mass increases, the engine can be stopped at a higher SOC level and the driveline disconnect clutch opened, allowing the engine to continue operating unless the energy storage device is at a higher SOC level.

[0146] The sixth diagram from the top in Fig. Figure 10 is a graph of vehicle mass as a function of time. The Y-axis represents vehicle mass, and vehicle mass increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases in the direction of the X-axis arrow.

[0147] The seventh diagram from the top in Fig. Figure 10 is a graph of the driveline disconnect clutch state as a function of time. The driveline disconnect clutch is in an open state when the curve is at a lower level. The driveline disconnect clutch is in a closed state when the curve is at a higher level. The x-axis represents time, and time increases in the direction of the x-axis arrow.

[0148] At time T0, the vehicle speed is zero, the engine is stopped, the brake pedal is applied, the energy storage device SOC is relatively high, the driveline disconnect clutch is open, and the vehicle mass is at a lower level. In this example, the engine was automatically stopped in response to the vehicle speed being zero and the brake pedal being applied.

[0149] At time T1, the driver releases the brake pedal, and vehicle speed gradually increases as the DISG (not shown) applies torque to the vehicle driveline in response to the driver releasing the brake pedal. The engine remains in a de-energized state, and the driveline disconnect clutch remains open. Desired torque converter impeller torque increases in response to the driver releasing the brake pedal and subsequently increasing driver demand torque. The driver demand torque may be engine braking torque, torque converter impeller torque, wheel torque, or other driveline torque. Vehicle mass remains at a lower level, and energy storage device SOC begins to decrease as the DISG alone powers the vehicle.

[0150] At time T2, the desired torque converter impeller torque has increased in response to a driver torque request (not shown) to a level at which the engine is automatically started and the driveline disconnect clutch is closed. The engine may be automatically started without direct driver input to a device that has a sole purpose of starting and / or stopping the engine (e.g., an ignition switch) when the driver request torque exceeds a threshold torque level. Vehicle speed continues to increase in response to the increasing torque converter impeller torque. Vehicle mass remains at a lower level, and the energy storage device SOC continues to decrease as the vehicle accelerates. The vehicle brake pedal remains in an inactive position.

[0151] At time T3, the vehicle begins to decelerate in response to a decreased driver torque demand. The vehicle mass is at a lower level and the energy storage device SOC is greater than the threshold level 1004, so in response to the vehicle entering a deceleration mode when the driver demand torque is decreased, the driveline disconnect clutch is opened and the engine is stopped. The desired torque converter impeller torque is decreased in response to the decreased driver demand torque. The vehicle brake pedal state remains off, and the energy storage device begins to charge via the DISG, which converts vehicle inertia into electrical energy.

[0152] Between time T3 and time T4, the vehicle stops and the driver applies the vehicle brake. The energy storage device SOC has increased and the driveline disconnect clutch remains in an open state. The engine also remains in a shut-off state.

[0153] At time T4, the vehicle mass is increased. Vehicle mass may increase if the driver or anyone adds cargo or passengers to the vehicle, for example. Vehicle speed remains at zero and the engine remains off. The desired torque converter impeller torque remains at a lower level and the energy storage device SOC remains unchanged. The driveline disconnect clutch also remains in an open state.

[0154] At time T5, the driver releases the brake pedal, and the DISG output torque increases as the desired torque converter impeller torque increases. The desired torque converter impeller torque increases in response to the driver releasing the brake and increasing the driver demand torque. The energy storage device SOC begins to decrease as the DISG applies torque to the vehicle driveline. The vehicle speed gradually begins to increase. However, because the vehicle mass has increased, the vehicle accelerates at a slower rate. The controller begins to estimate the change in vehicle mass based on the torque applied to the driveline and the rate of vehicle acceleration.

[0155] Between time T5 and time T6, the engine is automatically restarted in response to the torque converter impeller torque increasing to more than a threshold level. The driveline disconnect clutch is also closed in response to the torque converter impeller torque being greater than a threshold level. The energy storage device SOC decreases, and the DISG delivers torque to the driveline.

[0156] At time T6, the driver reduces the driver demand torque and applies the vehicle brake. The engine remains operating and the driveline disconnect clutch remains engaged so that the engine can provide braking during vehicle deceleration. The engine remains operating because the vehicle mass has increased and because the energy storage device SOC is less than the threshold level 1002. Thus, the driveline disconnect clutch opening timing may be delayed or retarded as the vehicle mass increases. Likewise, the driveline disconnect clutch opening timing may be advanced as the vehicle mass decreases. The vehicle mass remains at the higher level and the vehicle decelerates toward zero speed. The energy storage device SOC increases as the vehicle decelerates.

[0157] At time T7, the driveline disconnect clutch is opened and the engine is stopped as the vehicle speed approaches zero. The vehicle brake remains in an applied state, and the desired torque converter impeller torque remains at a lower level. The vehicle mass remains unchanged when the vehicle is stopped.

[0158] At time T8, the brake pedal is released by the driver, and the engine is automatically started. In the present example, the driveline disconnect clutch is opened when the engine is stopped; however, in some examples, the driveline disconnect clutch remains closed, allowing the engine and DISG to accelerate to operating speed simultaneously. The engine is restarted upon release of the brake pedal in response to the increased vehicle mass. In this manner, it may be possible to reduce the possibility of the vehicle accelerating at less than a desired rate because the engine and DISG are available when the brake pedal is released. Further, the engine and DISG may apply creep torque that propels the vehicle at the same rate as when the vehicle is unloaded and powered only by the DISG when the driver is not depressing the vehicle accelerator pedal.

[0159] The desired torque converter impeller torque is also increased in response to the increase in estimated vehicle mass. The desired torque converter impeller torque is increased so that the vehicle accelerates in a manner similar to when the vehicle is accelerated at a time when the vehicle mass is lower (e.g., at time T1). Consequently, for a similar accelerator pedal input, the vehicle accelerates similarly to when the vehicle mass is reduced and the accelerator pedal input is the same. In this way, the driver can experience similar vehicle acceleration for an equivalent accelerator pedal input, even when the vehicle mass changes.

[0160] Consequently, the procedures and systems of Fig. 1-3 and 9-10, operating a hybrid vehicle, comprising: adjusting actuation of a driveline disconnect clutch in response to a change in vehicle mass. The method further comprises adjusting engine stop timing in response to the change in vehicle mass. The method includes adjusting actuation of the driveline disconnect clutch comprising retarding driveline disconnect clutch opening timing in response to an increase in vehicle mass. The method includes adjusting actuation of the driveline disconnect clutch comprising advancing driveline disconnect clutch opening timing in response to a decrease in vehicle mass. The method further comprises adjusting an energy storage device state of charge threshold in response to vehicle mass.The method includes wherein adjusting the energy storage device state of charge threshold comprises increasing the energy storage device state of charge threshold in response to vehicle mass.

[0161] In another example, the procedures and systems of Fig. 1-8 operating a hybrid vehicle, comprising: adjusting actuation of a driveline disconnect clutch in response to a change in vehicle mass; and automatically stopping an engine at a time responsive to the change in vehicle mass. The method further comprises not restarting the engine in response to the vehicle mass when the vehicle mass is a first vehicle mass. The method further comprises restarting the engine in response to the vehicle mass when the vehicle mass is a second vehicle mass. The method further comprises where the second vehicle mass is greater than the first vehicle mass. The method further comprises providing at least a portion of a creep torque via the engine after restarting the engine.

[0162] In some examples, the method includes providing creep torque via a DISG only when the engine is not restarting and when the hybrid vehicle is moving. The method further includes adjusting a desired torque converter impeller torque in response to the change in vehicle mass. The method includes where adjusting the desired torque converter impeller torque includes increasing the desired torque converter impeller torque when the change in vehicle mass increases vehicle mass. The method includes where adjusting the torque converter impeller torque includes decreasing the torque converter impeller torque when the change in vehicle mass decreases vehicle mass.

[0163] In another example, the processes and systems of Fig. 1-8, operating a hybrid vehicle, comprising: adjusting actuation of a driveline disconnect clutch in communication with an engine in response to a change in vehicle mass; automatically stopping the engine in response to a first energy storage device state of charge being greater than a first threshold state of charge, wherein the first threshold state of charge is based on a first vehicle mass before the change in vehicle mass; and automatically stopping the engine in response to a second energy storage device state of charge being greater than a second threshold state of charge, wherein the second threshold state of charge is based on a second vehicle mass after the change in vehicle mass. Thus, the driveline disconnect clutch may be actuated based on the vehicle mass to improve vehicle performance.

[0164] In some examples, the method includes where the second threshold state of charge is greater than the first threshold state of charge. The method includes where the second vehicle mass is greater than the first vehicle mass. The method includes where the driveline disconnect clutch is open when the engine is stopped. The method also includes where the driveline disconnect clutch is closed when the engine is stopped.

[0165] With reference to Fig. 11 is a flowchart of a method for starting an engine via a first electric machine or a second electric machine. The method of Fig. 11 can be stored in a non-volatile memory of the control unit 12 of Fig. 1-3 must be stored as executable commands.

[0166] At 1102, method 1100 determines vehicle operating conditions. The vehicle operating conditions may include, but are not limited to, engine speed, DISG speed, vehicle speed, driveline torque request, engine coolant temperature, and driveline disconnect clutch actuation state (e.g., open, partially open, or closed). Method 1100 proceeds to 1104 after the operating conditions are determined.

[0167] At 1104, method 1100 judges whether or not conditions exist to stop engine rotation. In one example, engine rotation may stop if the desired driveline torque (e.g., a combined torque delivered via the engine and / or the DISG) is less than a threshold torque amount. If method 1100 judges that conditions do not exist to stop engine rotation, method 1100 proceeds to 1106. Otherwise, method 1100 proceeds to 1110.

[0168] At 1106, method 1100 operates the engine. The engine is operated via supplying a spark and / or fuel to the engine based on engine operating conditions. In some examples, where the engine is a diesel engine or a homogeneous charge compression ignition (HCCI) engine, the engine may be operated without a spark. Method 1100 proceeds to 1108 after the engine is operated.

[0169] At 1108, method 1100 delivers torque from the engine to the vehicle wheels. The engine torque may be delivered to the vehicle wheels by closing the driveline disconnect clutch and routing the engine output through the transmission to the vehicle wheels. In some examples, the engine and DISG torque may be delivered to the vehicle wheels simultaneously. Method 1100 proceeds to exit after the engine torque is delivered to the vehicle wheels.

[0170] At 1110, method 1100 stops engine rotation and opens or disengages the driveline disconnect clutch. Engine rotation may be stopped by preventing fuel and / or air flow to the engine cylinders. Method 1100 proceeds to 1112 after the engine is stopped. Note that the DISG may continue to provide torque to the vehicle wheels in response to a driver request while the engine is stopped.

[0171] At 1112, method 1100 judges whether or not engine restart conditions exist. In one example, the engine may be restarted when the driveline torque command exceeds a threshold torque amount. In other examples, the engine may be started when a temperature of a catalyst is reduced to less than a threshold temperature. If method 1100 judges that selected engine restart conditions exist, method 1100 proceeds to 1114. Otherwise, method 1100 returns to 1104.

[0172] At 1114, method 1100 determines an available amount of torque from the DISG. The amount of torque available from the DISG is based on the DISG rated torque, the battery state of charge, the DISG speed, and the DISG temperature. A table describing the torque available from the DISG is stored in memory and is indexed by the battery state of charge (e.g., battery voltage and amp-hour rating), the DISG speed, and the DISG temperature. The table outputs the amount of torque available from the DISG. Method 1100 proceeds to 1116 after the amount of available DISG torque is determined.

[0173] At 1116, method 1100 assesses whether or not the DISG has the capacity to start the engine and would provide the desired amount of torque. In one example, the desired amount of torque is determined at least in part by an accelerator pedal, which the driver can adjust to vary the desired driveline torque. The torque to start the engine may be empirically determined and stored in a table or function in memory. The table or function may be indexed by engine temperature and time since the last engine stop. The table returns a torque to achieve a desired engine cranking speed (e.g., 250 rpm). -1) from zero speed. The engine starting torque is added to the desired driveline torque supplied by the driver, and the amount of available DISG torque is subtracted from the sum of the engine starting torque and the desired driveline torque. If the result is positive, the DISG lacks the capacity to supply the engine starting torque and the desired driveline torque. Consequently, method 1100 proceeds to 1124. If the result is negative, the DISG has the capacity to supply the engine starting torque and the desired driveline torque. Therefore, method 1100 proceeds to 1118.

[0174] At 1118, method 1100 judges whether or not an engine start has been requested. If so, method 1100 proceeds to 1120. Otherwise, method 1100 proceeds to 1122. Method 1100 may judge that an engine start request is being performed if, for example, an engine torque request increases or if a driver releases a brake pedal.

[0175] At 1120, method 1100 delivers DISG torque to the vehicle wheels and the engine. DISG torque is delivered to the engine via closing the driveline disconnect clutch and transferring torque from the DISG to the engine. The driveline disconnect clutch may partially close to control engine speed during engine startup. The engine may be at a cranking speed (e.g., 250 rpm -1 ) or with a base idle speed (e.g. 800 min -1) before fuel and spark are delivered to the engine. Method 1100 returns to 1104 after DISG torque is delivered to the engine and vehicle wheels.

[0176] At 1122, method 1100 delivers DISG torque only to the vehicle wheels. The DISG torque delivered to the vehicle wheels may be based on an accelerator pedal input and / or an input from a controller. Method 1100 returns to 1104 after the DISG torque is delivered to the vehicle wheels.

[0177] At 1124, method 1100 judges whether or not an engine start request is present. An engine start request may occur as described at 1118. If an engine start is requested, method 1100 proceeds to 1126. Otherwise, method 1100 proceeds to 1122.

[0178] At 1126, method 1100 starts the engine via a second electric machine having a lower power output capacity than the DISG. The engine may be started, for example, via a conventional starter motor including a pinion shaft and a pinion gear that is selectively engaged with the engine flywheel to start the engine. The driveline disconnect clutch is closed when the second electric machine alone provides torque to rotate the engine. Further, at 1126, fuel and a spark are delivered to the engine to initiate combustion in the engine so that the engine rotates under its own power. Method 1100 proceeds to 1128 after the engine is started.

[0179] At 1128, method 1100 engages the driveline disconnect clutch to enable the transfer of torque from the engine to the vehicle wheels. In one example, the engine speed is increased until the engine speed equals the DISG speed. The driveline disconnect clutch is closed when the engine speed equals the DISG speed to reduce the possibility of introducing a torque disturbance to the driveline. Method 1100 proceeds to exit after the engine has started and is delivering torque to the vehicle wheels.

[0180] It should be noted that the procedure of Fig. 11 shows only one example of starting an engine solely by a lower power capacity electric machine (starter motor) or solely by a higher power capacity electric machine (DISG). Other examples are also anticipated. For example, if both the DISG and the lower power capacity starter motor are operational, the DISG and the lower power capacity starter motor may start the engine during different operating conditions. However, if the DISG is disabled, the lower power capacity starter may start the engine after the engine is automatically stopped from rotating during conditions where the DISG would otherwise start the engine.For example, the lower-power capacity starter motor may start the engine if the DISG is capable of starting the engine and delivering torque to the driveline but is disabled. On the other hand, if the lower-power capacity starter motor is disabled, the DISG may start the engine if the driveline torque request is at a lower threshold level because the lower-power capacity starter motor is unavailable.

[0181] With reference to Fig. 12 is a diagram of an example sequence for starting an engine according to the method of Fig. 11. The vertical markings T 10 -T 17 represent points of interest in the sequence. The sequence of Fig. 12 can be achieved through the system of Fig. 1-3 are provided.

[0182] The first diagram from the top in Fig. Figure 12 illustrates DISG torque as a function of time. The x-axis represents time, and time increases from the left side of the figure to the right side of the figure. The y-axis represents DISG torque, and DISG torque increases in the direction of the y-axis arrow. Horizontal line 1202 represents an amount of available DISG torque. Horizontal line 1204 represents an amount of torque the DISG can deliver to the transmission input while the DISG is cranking the engine. The difference between horizontal lines 1202 and 1204 represents an amount of torque to crank the engine for starting.

[0183] The second diagram from the top in Fig. Figure 12 represents engine speed as a function of time. The x-axis represents time, and time increases from the left side of the figure to the right side. The y-axis represents engine speed, and engine speed increases in the direction of the y-axis arrow.

[0184] The third diagram from the top in Fig. Figure 12 illustrates the driveline disconnect clutch state (e.g., open or closed) as a function of time. The x-axis represents time, and time increases from the left side of the figure to the right side of the figure. The y-axis represents the driveline disconnect clutch state, and the driveline disconnect clutch state is open at the top and closed near the x-axis, as indicated.

[0185] The fourth diagram from the top in Fig. Figure 12 shows the low-output starter motor state as a function of time. The x-axis represents time, and time increases from the left side of the figure to the right side of the figure. The y-axis represents the low-output starter motor state, and the low-output starter motor state is engaged when the curve is at a higher level and disengaged when the curve is at a lower level.

[0186] The fifth diagram from the top in Fig. Figure 12 shows the engine start request state as a function of time. The x-axis represents time, and time increases from the left side of the figure to the right side of the figure. The y-axis represents the engine start request state, and the engine start request state is enabled for starting or running when the curve is at a higher level. The engine start request is not enabled or indicates an engine stop when the curve is at a lower level.

[0187] At time T 10DISG torque is at a lower level in response to a low driveline torque request (not shown). The driveline torque request may be from an accelerator pedal or other device and may be responsive to driver input. The engine is also stopped and the driveline disconnect clutch is open. The lower output starter motor is not engaged, and there is no engine start request.

[0188] At time T 11An engine start request is provided while DISG torque is less than a threshold 1204. The engine start request may be made in response to a battery state of charge (SOC) or other condition. The low-output starter remains inactive, and the driveline disconnect clutch is closed shortly thereafter. Closing the driveline disconnect clutch transfers torque from the DISG to the engine, thereby cranking the engine. The engine starts shortly after the DISG is at least partially closed. The driveline disconnect clutch may drag during engine cranking and during engine startup from engine stop to DISG speed.

[0189] At time T 12The engine start / run request transitions to a low level in response to vehicle operating conditions (e.g., a charged battery and an applied vehicle brake pedal). The driveline disconnect clutch opens in response to the engine start / run request, and the engine is stopped. The DISG continues to deliver torque to the vehicle driveline.

[0190] Between time T 12 and the time T 13 DISG output torque increases in response to increased driver demand torque (not shown). The engine remains off and the driveline disconnect clutch remains open.

[0191] At time T 13The engine start / run request is enabled in response to the battery SOC being less than a threshold charge level (not shown). The low output starter is enabled as indicated because the DISG torque is greater than the threshold torque at 1204. The driveline disconnect clutch is open while the engine is being cranked by the low output starter. The low output starter is disabled when the engine speed exceeds the engine cranking speed.

[0192] At time T 14 The driveline disconnect clutch is closed after the engine speed reaches the DISG speed. The engine start / run request remains enabled, and both the DISG and the engine deliver torque to the vehicle driveline.

[0193] At time T 15The engine start / run request transitions to a lower level to indicate that the engine should be stopped. Shortly thereafter, in response to the engine start / run request transitioning to a lower level, the engine is stopped and the driveline disconnect clutch is opened. The DISG continues to deliver torque to the vehicle driveline.

[0194] At time T 16The engine start / run request is activated in response to the driver demand torque exceeding a threshold torque (not shown). The engine is restarted so that the engine can output torque to the driveline to augment the DISG torque. The low output starter is engaged in response to the engine start / run request transitioning to a higher level. The low output starter is disengaged in response to the engine speed exceeding a threshold speed.

[0195] At time T 17 The driveline disconnect clutch is closed in response to the engine speed reaching the DISG speed. The engine and DISG deliver torque to the vehicle driveline after the driveline disconnect clutch is closed.

[0196] In this way, the engine can be started via the DISG or the starter motor with lower output. The lower output starter allows the DISG to deliver a greater amount of torque to the driveline than would be possible if only the DISG had the ability to crank the engine. Furthermore, the lower output starter allows the engine speed to reach the DISG speed before the driveline disconnect clutch is closed, so little torque disturbance can be noticed in the vehicle's driveline.

[0197] Consequently, the procedures and systems of Fig. 1-3 and 11-12, starting an engine, comprising: during a first condition, starting an engine with a first electric machine while a driveline disconnect clutch is closed; and during a second condition, starting the engine with a second electric machine while the driveline disconnect clutch is open. The method includes where the second electric machine has a lower power output capacity than the first electric machine. The method includes where the first electric machine is a driveline integrated starter / generator (DISG), and where the driveline disconnect clutch has a first side mechanically coupled to a dual mass flywheel and a second side mechanically coupled to the DISG.

[0198] In some examples, the method includes where the first condition is a desired driveline torque that is less than a driveline torque during the second condition. The method includes opening the driveline disconnect clutch in response to a desired driveline torque. The method includes closing the driveline disconnect clutch when a sum of a desired driveline torque and an engine cranking torque is greater than a threshold torque amount. The method includes where the first electric machine is disposed downstream of an engine and provides torque through a torque converter that turns the vehicle wheels, and where the second electric machine is disposed at the engine and does not provide torque through the torque converter to turn the vehicle wheels above an engine cranking speed that is lower than the engine idle speed.

[0199] In other examples, the procedures and systems of Fig. 1-3 and 11-12, starting an engine, comprising: starting an engine via a first electric machine when a desired torque request is less than a first threshold amount; starting the engine via the second electric machine when the desired torque request is greater than the first threshold amount; and providing torque sufficient to rotate the vehicle wheels via only the first electric machine during selected operating conditions. Thus, different electric machines can start the engine during different conditions.

[0200] The method includes where the first electric machine is a driveline integrated starter / generator (DISG), and where the DISG is disposed in the hybrid vehicle driveline at a location between a driveline disconnect clutch and a transmission. The method includes where the DISG provides torque to start rotation of the stopped engine via at least partially closing the driveline disconnect clutch. The method further includes decoupling the second electric machine from the engine when the engine speed reaches a threshold speed. The method includes where the second electric machine includes a pinion shaft and a pinion gear. The method includes where the first threshold amount varies with the battery state of charge. The method also includes where the first threshold amount varies with the speed of the first electric machine.

[0201] The procedures and systems of Fig. 1-3 and 11-12 also provide a hybrid vehicle system comprising: an engine; a starter motor selectively engaged with the engine and including a pinion gear; a dual mass flywheel (DMF) having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side mechanically coupled to a second side of the dual mass flywheel; a driveline integrated starter / generator (DISG) having a first side coupled to a second side of the driveline disconnect clutch; and a controller having non-transitory instructions executable to start the engine via the starter motor during a first start and via the DISG during a second start.

[0202] In some examples, the hybrid vehicle system further includes additional commands to start the engine via the starter motor during conditions of a desired torque greater than a threshold. The hybrid vehicle system includes starting the engine by rotating the engine via the DISG and further includes additional commands to decouple the DISG from the engine after a predetermined number of combustion events. The hybrid vehicle system further includes additional commands to couple the engine to the DISG after the engine speed reaches the DISG speed. The hybrid vehicle system includes the available power output from the starter motor being less than the available power output from the DISG.The hybrid vehicle system further includes additional commands to automatically stop the engine and start the engine via the DISG based on an available amount of DISG output torque.

[0203] With reference to Fig. 13 is a flowchart of a method for adjusting fuel injection to provide a desired engine speed curve during engine start. The method of Fig. 13 can be stored as executable instructions in a non-volatile memory of the Fig. 1-3 shown control unit 12.

[0204] At 1302, method 1300 judges whether or not an engine start is requested and the driveline disconnect clutch is disengaged. Method 1300 may judge that an engine start is desired if an engine start variable is enabled in memory. Method 1300 may judge that the driveline disconnect clutch is disengaged if a driveline disconnect clutch state variable is not enabled in memory. If method 1300 judges that an engine start is desired and a driveline disconnect clutch is not engaged, method 1300 proceeds to 1304. Otherwise, method 1300 proceeds to 1316.

[0205] At 1304, method 1300 determines operating conditions. The operating conditions may include, but are not limited to, DISG speed, engine temperature, time since engine rotation stopped, and driveline disconnect clutch state. Method 1300 proceeds to 1306 after the operating conditions are determined.

[0206] At 1306, method 1300 determines the desired engine speed based on the torque converter impeller speed. Further, a desired cylinder air charge may be determined at 1306 so that the desired engine speed may be achieved. In one example, the desired engine speed is set to the torque converter impeller speed after engine startup (e.g., from cranking speed to a desired idle speed). Consequently, after engine startup during an engine start, the engine speed is controlled to the torque converter impeller speed so that the driveline disconnect clutch may be closed to transfer engine torque to the vehicle wheels without creating a torque disturbance. The engine may be started via spinning the engine with a starter other than a DISG (e.g.,A starter motor with lower output may be used to crank the engine, if desired. Method 1300 proceeds to 1308 after the desired engine speed is selected. It should be noted that the torque converter impeller speed is equivalent to the DISG speed because the DISG is coupled to the torque converter impeller.

[0207] At 1308, fuel injection is set for the first combustion event. In one example where the engine includes a near-centrally located fuel injector at the top of the combustion chamber, fuel is injected into at least one cylinder via a single fuel pulse during a compression stroke of the cylinder and during a single cycle of the cylinder. The injected fuel then participates in a first combustion event since engine shutdown for the cylinder receiving the fuel. After the single fuel pulse is injected into the cylinder, fuel injections may be injected during startup in a series of pulses during the intake and compression strokes of the cylinder receiving the fuel, as described at 1310.In one example, a single pulse of fuel is injected into each of a predetermined number of engine cylinders during the compression strokes of the cylinders. Thus, the fuel is injected into each of the predetermined number of cylinders in one or more pulses during a cycle of the cylinder receiving the fuel. For example, for a four-cylinder engine, two engine cylinders receive a single injection of fuel during the respective compression strokes of the cylinders receiving the single injection of fuel. The other two engine cylinders receive multiple injections of fuel during the intake and / or compression strokes of the cylinder receiving the fuel.

[0208] In a second example, where the engine includes a fuel injector located on the side of the combustion chamber, multiple fuel injections for each cylinder are delivered to a predetermined number of engine cylinders during the compression stroke of the cylinder receiving the fuel for the first combustion event in the cylinder since engine shutdown. After a predetermined number of cylinders receive multiple fuel injections during the compression stroke of the cylinder receiving the fuel, multiple injections of fuel may be delivered to each cylinder during the intake and / or compression stroke of the cylinder receiving the fuel. Additionally, the position of the engine throttle may be adjusted at 1308 based on the desired engine speed.In one example, the engine throttle opening amount is increased as the desired engine speed increases during engine cranking. Method 1300 proceeds to 1310 after fuel is injected for the first combustion events of each engine cylinder.

[0209] At 1310, method 1300 adjusts split fuel injection timing and split fuel amounts based on the desired engine speed and a speed difference between the actual engine speed and the desired engine speed. In particular, at lower engine speeds (e.g., between a cranking speed of 250 rpm -1 and 400 min -1 ) two or more injections are delivered to each engine cylinder during the compression stroke of each cylinder receiving the fuel. At medium engine speeds (e.g., between 400 min -1and 700 min -1 ), multiple fuel injections are delivered during both the intake and compression strokes of each cylinder receiving the fuel. At higher engine speeds (e.g., 700 rpm -1 up to 1000 min -1 ), multiple fuel injections are delivered only during the intake stroke of the cylinder receiving the fuel. The lower, medium, and higher engine speeds may, of course, vary between applications. The lower engine speed for other applications may, for example, be between 200 rpm -1 and 300 min -1 The average engine speed can be between 300 min -1 and 800 min -1 and the higher engine speed can be between 800 min -1 and 1100 min -1Consequently, when the desired engine speed is a higher engine speed, the fuel injection timing is adjusted to deliver multiple fuel injections only during the intake stroke of the cylinder receiving the fuel when the engine reaches the desired engine speed. When the desired engine speed is a mid-engine speed, the fuel injection timing is adjusted to deliver multiple fuel injections during the intake and compression strokes of the cylinder receiving the fuel. The split fuel injection timing at higher engine speeds creates improved fuel mixing and reduced engine emissions. The split fuel injection during the compression and intake strokes creates improved combustion stability and reduced possibility of engine misfire.

[0210] If the engine speed during engine start-up differs from the starting speed (e.g. 250 min -1) to the desired idle speed increases, the amount of time between the end of injection (EOI) (e.g., the time at which the last fuel pulse injected into a cylinder during a cycle of the cylinder occurs) and the spark initiation is maintained substantially constant (e.g., ± 3 degrees). Since the time between various crankshaft positions decreases as engine speed increases, the EOI timing is advanced with respect to the crankshaft timing to maintain a substantially constant amount of time (e.g., ± 0.05 seconds) between the EOI and the spark initiation. Further, when multiple fuel injections are performed, the timing of each of the fuel injections during a cylinder cycle may be advanced as engine speed increases.Consequently, the start of fuel injection (SOI) can be advanced during a cylinder cycle as engine speed increases during engine startup.

[0211] When the desired engine speed is greater than the actual engine speed, fuel injection amounts are increased by increasing the fuel injection duration. Additionally, additional air may be supplied to the engine by opening the throttle. When the desired engine speed is less than the actual engine speed, fuel injection amounts are decreased by decreasing the fuel injection duration. Engine air quantity may be decreased by closing the throttle. Further, fuel injection timing and fuel amounts may be adjusted in response to driveline disconnect clutch operating conditions to preemptively adjust fuel injection timing.For example, when the driveline disconnect clutch closes and the engine side of the driveline disconnect clutch is rotating slower than the DISG side of the driveline disconnect clutch, the fuel injection amount may be increased to accelerate the engine closer to the DISG speed and thereby reduce driveline torque disturbances. On the other hand, when the driveline disconnect clutch closes and the engine side of the driveline disconnect clutch is rotating faster than the DISG side of the driveline disconnect clutch, the fuel injection amount may be decreased to decelerate the engine closer to the DISG speed. When the driveline disconnect clutch is opened, the fuel injection amount may be further decreased as a function of the driveline disconnect clutch application force to decelerate the engine to idle speed and thereby reduce driveline torque disturbances.Likewise, when the driveline disconnect clutch is opened, the fuel injection amount may be increased as a function of the driveline disconnect clutch application force to accelerate the engine to idle speed and thereby reduce driveline torque disturbances.

[0212] In some examples, the fuel injection timing of an engine cylinder is adjusted to a stroke of a cylinder that changes as engine speed changes. For example, if a speed difference between the actual and desired engine speeds increases, method 1300 adjusts the fuel from a compression stroke to an intake stroke. By varying the injection stroke based on a speed difference between the actual and desired engine speeds, it may be possible to improve the air / fuel mixture and promote more complete combustion, so the speed difference may be reduced.

[0213] Additionally, engine throttle position may be adjusted in response to the timing at which fuel is injected into a cylinder. For example, a port throttle may be partially closed to enhance charge motion when fuel is only injected during an intake stroke. The port throttle may be partially opened when fuel injection transitions from injecting fuel during a compression stroke to injecting fuel during an intake stroke. Further, the amount of fuel injected into the cylinder during the cylinder cycle is adjusted based on an amount of air flowing through a throttle. Method 1300 proceeds to 1312 after the fuel injection timing is adjusted.

[0214] At 1312, method 1300 adjusts the spark timing in response to the state of the driveline disconnect clutch and the speed difference between the desired engine speed and the actual engine speed. In particular, when the engine speed is substantially at the DISG speed (e.g., ± 100 rpm -1 ), the spark is retarded to a level to produce zero torque at the driveline disconnect clutch. Furthermore, spark retard can also be provided based on the speed difference between the DISG and the engine. As the speed difference between the engine and the DISG is reduced, the amount of spark retard is increased.

[0215] At 1314, method 1300 judges whether or not the driveline disconnect clutch has been closed to a threshold extent (e.g., 80% of the clutch holding torque is provided). The driveline disconnect clutch may be closed when the engine speed is within a predetermined torque converter impeller speed so that torque disturbances from the driveline may be reduced. If method 1300 judges that the driveline disconnect clutch has been closed to a threshold extent, method 1300 proceeds to 1316. Otherwise, method 1300 returns to 1304.

[0216] At 1316, method 1300 advances spark timing and transitions to injecting fuel in a single fuel injection during a cylinder's cycle based on a number of combustion events since engine stop or based on a torque ratio. For example, after the driveline disconnect clutch closes, method 1300 may transition from split fuel injection to a single fuel injection after 10 combustion events during a cylinder cycle. Alternatively, method 1300 may transition from split fuel injection to single fuel injection during a cylinder cycle after advancing spark timing to a time at which a torque ratio between spark timing and fuel injection timing is less than a threshold amount.Method 1300 proceeds to the end after the fuel injection timing and spark timing are converted to base timings that are empirically determined and stored in memory.

[0217] With reference to Fig. 14 is a diagram of an example sequence for supplying fuel to an engine according to the method of Fig. 13. The sequence of Fig. 14 can be achieved through the system of Fig. 1-3 are provided.

[0218] The first diagram from the top in Fig. Figure 14 shows the fuel injection timing for cylinder number one. The X-axis represents the cylinder stroke for cylinder number one, and individual cylinder strokes are indicated by representative letters. For example, the intake stroke is represented by I, the compression stroke is represented by C, the power stroke is represented by P, and the exhaust stroke is represented by E. The Y-axis represents the fuel injection.

[0219] The second diagram from the top in Fig. Figure 14 represents the desired torque converter impeller speed as a function of cylinder number one stroke. The X-axis timing corresponds to the timing of the first graph from the top of the figure. The Y-axis represents the desired torque converter impeller speed, and the desired torque converter impeller speed increases in the direction of the Y-axis arrow.

[0220] The third diagram from the top in Fig. Figure 14 represents the desired engine speed as a function of cylinder number one stroke. The X-axis timing corresponds to the timing of the first graph from the top of the figure. The Y-axis represents the desired engine speed, and the desired engine speed increases in the direction of the Y-axis arrow.

[0221] The fourth diagram from the top in Fig. Figure 14 represents the actual engine speed as a function of cylinder number one stroke. The X-axis timing corresponds to the timing of the first graph from the top of the figure. The Y-axis represents the actual engine speed, and the actual engine speed increases in the direction of the Y-axis arrow.

[0222] The fifth diagram from the top in Fig. Figure 14 shows the difference between the desired engine speed and the actual engine speed (delta engine speed) as a function of cylinder number one stroke. The X-axis timing corresponds to the timing of the first graph from the top of the figure. The Y-axis represents the desired engine speed, and the desired engine speed increases in the direction of the Y-axis arrow.

[0223] At time T 18 the engine is stopped and the desired torque converter impeller speed is zero. The engine rotates to T 18in the cycle due to the different stroke of cylinder number one. A first single fuel injection quantity is delivered directly to cylinder number one during the compression stroke of cylinder number one. The engine begins to accelerate from an initial combustion event during the first compression stroke since engine stop.

[0224] At time T 19Two fuel injections are delivered during the second compression stroke of cylinder number one. Fuel injection transitions to two injections in response to a speed difference between the desired engine speed and the actual engine speed. Further, fuel injection is delivered during a cylinder stroke that depends on the speed difference between the actual and desired engine speeds. In one example, fuel injection timing for the cylinder stroke is stored in a table based on the difference between the actual and desired engine speeds and outputs a cylinder stroke based on the speed difference.By adjusting the cylinder stroke at which fuel injection occurs based on a difference between the actual and desired engine speed, it may be possible to improve fuel mixing and engine speed control during engine start-up.

[0225] Between time T 19 and the time T 20 The fuel injection timing is further adjusted in response to the difference between the desired engine speed and the actual engine speed. It can be observed that the fuel injection changes from injecting fuel twice during a compression stroke of the cylinder to injecting fuel once during an intake stroke and once during a compression stroke. Furthermore, the fuel injection transitions to injecting fuel twice during an intake stroke.

[0226] At time T20 the engine speed error between the desired engine speed and the actual engine speed goes to zero and fuel is injected once per cylinder cycle. In this manner, the fuel injection timing may be adjusted to deliver fuel during various engine strokes in response to the engine speed error. Further, the fuel injection timing and spark timing may be adjusted in response to the driveline disconnect clutch state or the applied force, as described with reference to Fig. 13 discussed.

[0227] The procedures and systems of Fig. 1-3 and 13-14 also provide for adjusting cylinder air charge of an engine, comprising: positioning a throttle valve for engine start; and adjusting fuel injection timing of a cylinder to a stroke of the cylinder that changes as a difference between a desired engine speed and an actual engine speed changes; and adjusting an amount of fuel delivered to the cylinder in response to an amount of air flowing through the throttle valve. The method includes where the stroke of the cylinder changes from a compression stroke to an intake stroke. The method includes where the throttle valve is a port throttle.

[0228] In some examples, the method further includes at least partially closing the port throttle during fuel injection during a compression stroke. The method further includes opening the port throttle during fuel injection during an intake stroke of the cylinder. The method also includes providing fuel injection timing to at least two fuel injections during a cycle of the cylinder. The method includes providing fuel injection timing to a fuel injector that injects fuel directly into the cylinder.

[0229] The procedures and systems of Fig. 1-3 and 13-14 also provide for adjusting the cylinder air charge of an engine, comprising: positioning a throttle valve for engine start; delivering an ignition spark to a combustion chamber of a cylinder during a cycle of the cylinder; and adjusting fuel injection timing to maintain a substantially constant amount of time between the ignition spark and an end of the fuel injection timing as engine speed increases during engine start-up while injecting multiple fuel pulses during the cycle of the cylinder; and adjusting an amount of fuel delivered to the cylinder in response to an amount of air flowing through the throttle valve. In this manner, combustion consistency may be maintained.

[0230] The method also includes advancing the fuel injection timing as engine speed increases. The method further includes fuel injection timing responsive to a desired engine speed, and the desired engine speed based on a torque converter impeller speed. The method further includes closing a driveline disconnect clutch when the engine speed is within a threshold speed of the torque converter impeller speed. The method includes varying a cylinder stroke during which the plurality of fuel pulses are injected as engine speed varies. The method further includes varying spark timing during engine startup. The method includes the throttle being a port throttle disposed downstream of an intake manifold.

[0231] The procedures and systems of Fig. 1-3 and 13-14 also include a hybrid vehicle system comprising: an engine; a dual mass flywheel (DMF) having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side coupled to a second side of the dual mass flywheel; a driveline integrated starter / generator (DISG) having a first side coupled to a second side of the driveline disconnect clutch; and a controller having non-transitory instructions executable to adjust fuel injection timing in a cylinder in response to a desired engine speed based on a torque converter impeller speed while the torque converter impeller is not mechanically coupled to the engine.By adjusting the fuel injection timing based on the torque converter impeller speed, it may be possible to adjust the fuel injection timing so that the desired fuel injection timing is provided when the engine reaches the torque converter impeller speed. Such operation may improve engine emissions.

[0232] The hybrid vehicle system further includes additional instructions for closing the driveline disconnect clutch after the engine speed is within a threshold speed of the torque converter impeller speed. The hybrid vehicle system includes starting the engine by rotating the engine via a starter motor other than the DISG. The hybrid vehicle system further includes additional instructions for adjusting fuel injection timing to maintain a substantially constant amount of time between the time of a spark delivered to a cylinder and the time of the end of fuel injection delivered to the cylinder during a cycle of the cylinder as the engine speed increases during engine startup and during the injection of multiple fuel pulses during the cycle of the cylinder.The hybrid vehicle system also further includes additional instructions for adjusting fuel injection timing of a cylinder to a stroke of the cylinder that varies as a difference between the desired engine speed and an actual engine speed varies, and adjusting an amount of fuel delivered to the cylinder in response to an amount of air flowing through the throttle. The hybrid vehicle system further includes additional instructions for injecting a single pulse of fuel into the cylinder during a compression stroke of the cylinder prior to a first combustion event of the cylinder since engine shutdown.

[0233] With reference to Fig. 15 is a flowchart of a method for starting an engine when the torque provided via an electric machine cannot provide a desired amount of torque after a transmission gear shift. The method of Fig. 15 can be stored as executable instructions in the non-volatile memory of the control unit 12 in Fig. 1-3 must be saved.

[0234] At 1502, method 1500 assesses whether or not a transmission upshift is desired or commanded. In one example, a transmission upshift command may be determined by monitoring the state of a control variable that changes state in response to vehicle speed, demand torque, and the currently selected gear. If the control variable indicates that a transmission shift is desired, method 1500 proceeds to 1506. Otherwise, method 1500 proceeds to 1504.

[0235] At 1504, method 1500 determines the transmission output shaft speed and the torque converter impeller speed for a next upcoming transmission shift based on the desired torque. In one example, the desired torque delivered via an accelerator pedal, the currently selected transmission gear, and the vehicle speed are the basis for determining the transmission output speed and impeller speed for a next transmission upshift. In particular, the transmission output speed and the next gear may be determined from the currently selected gear and the vehicle speed at which the transmission is scheduled to upshift to the next gear at a desired engine torque level. A shift schedule may be empirically determined and stored in memory that outputs which gear will be selected at a current vehicle speed at a desired torque level.The vehicle speed can be extrapolated to a future time based on the current vehicle speed and the rate of change or gradient of the vehicle speed according to the equation y = mx+b, where y is the projected vehicle speed, m is the vehicle speed gradient, and b is the vehicle speed offset. Likewise, the desired impeller speed can be extrapolated to a future time. As the extrapolation time increases from the current time (e.g., current time plus 0.2 seconds and assuming increasing vehicle speed and / or increasing desired torque), the shift pattern can command an upshift to a higher gear (e.g., from 1st gear to 2nd gear) when variables indexing the shift pattern change. The extrapolated amount of time at which the transmission shift occurs (e.g.,The projected shift time, as well as the new gear number, extrapolated vehicle speed, and extrapolated desired torque are stored in memory when the selected transmission gear changes according to the shift pattern. The transmission output shaft speed is determined from the new gear (e.g., the upshift gear), any axle ratio, and vehicle speed. The transmission impeller speed can be predicted from the DISG speed because the DISG is mechanically coupled to the impeller. Method 1500 proceeds to 1506 after the transmission impeller speed and the transmission output shaft speed are determined.

[0236] At 1506, method 1500 determines transmission speeds (e.g., impeller speed and output shaft speed) and gear ratios for the torque request in the next transmission upshift. In one example, method 1500 determines the transmission output shaft speed based on the following equations: OSS=OSS_when_commanded+OSS_rateofchange*time_to_shift; Commanded_gear=gearfn(vs,dsd_tor); TSS_after_upshift=OSS*Commanded_gear;

[0237] Where OSS is the transmission output shaft speed, OSS_when_commanded is the transmission output shaft speed when the upshift is commanded, time_to_shift is the amount of time a shift takes, Commanded_gear is the active gear after the upshift, gearfn is a function that returns the commanded gear, vs is the vehicle speed, dsd_tor is the desired transmission input torque, and TSS_after_upshift is the transmission output shaft speed after the upshift. The function fn empirically maintains determined gears at which the transmission operates. Method 1500 proceeds to 1508 after the transmission speeds and gear ratio after the shift are determined.

[0238] At 1508, method 1500 determines the desired transmission output shaft torque and the desired transmission turbine shaft torque after an upshift. In one example, method 1500 determines the transmission output torque and the turbine shaft torque based on the following equations: OUTq_dsd=outfn(accel_pedal,TSS_after_upshift); Turq_dsd=OUTq_dsd*mult+offset;

[0239] Where OUTq_dsd is the desired transmission output shaft torque, outfn is a function that returns the desired transmission output shaft torque, accel_pedal is the accelerator pedal position that provides a desired torque, TSS_after_upshift is the transmission output shaft speed after the upshift, Turq_dsd is the desired transmission turbine shaft torque, mult and offset are empirically determined parameters stored in functions indexed by the commanded gear, transmission oil temperature, and transmission output shaft speed. Method 1500 proceeds to 1510 after the desired transmission output shaft torque and the desired transmission turbine shaft torque after the upshift are determined.

[0240] At 1510, method 1500 judges whether or not the torque converter clutch (TCC) is open after an upshift. In one example, method 1500 judges whether or not the TCC is open after an upshift based on an empirically determined shift schedule stored in memory. For example, based on the current gear, the next scheduled gear, and the desired torque, the shift schedule may schedule a closed torque converter. If method 1500 judges that the TCC is open after the upshift, the answer is yes and method 1500 proceeds to 1512. Otherwise, the answer is no and method 1500 proceeds to 1514.

[0241] At 1512, method 1500 determines the requested torque converter impeller torque. In one example, the requested torque converter impeller torque is retrieved from a table stored in memory. The table contains empirically determined values of torque converter impeller torque indexed by the transmission output shaft speed after the upshift and the desired turbine shaft torque. Method 1500 proceeds to 1516 after the requested impeller torque is determined.

[0242] At 1514, method 1500 sets the desired torque converter impeller torque to the desired torque converter turbine torque because the TCC is in a locked state. Method 1500 proceeds to 1516 after the desired torque converter impeller torque is determined.

[0243] At 1516, method 1500 judges whether or not the desired torque converter impeller torque after the transmission upshift requires the engine to combust an air / fuel mixture. In one example, method 1500 compares an amount of torque that the DISG has the capacity to deliver at the current battery state of charge to the desired torque converter impeller torque. If the desired torque converter impeller torque is greater than or within a threshold torque amount of the DISG torque capacity, the answer is yes and method 1500 proceeds to 1520. Otherwise, the answer is no and method 1500 proceeds to 1518.

[0244] At 1518, method 1500 may allow the engine to stop rotating based on current operating conditions, or method 1500 may allow the engine to continue combusting an air / fuel mixture. In one example, where the engine has reached warm operating conditions, the engine stops rotating because the desired torque converter impeller torque does not require engine operation. The engine may continue combusting if the engine has not reached warm operating conditions. Method 1500 proceeds to exit after allowing or preventing engine rotation based on operating conditions unrelated to transmission shifting.

[0245] At 1520, method 1500 assesses whether or not to start the engine prior to the transmission upshift. The engine may be started before the states of transmission clutches (e.g., not including the driveline disconnect clutch 236) are set so that engine torque can be transferred to the vehicle wheels at the end of the gear upshift. Alternatively, the engine may be started during the upshift at a time when one or more transmission clutches are changing operating state. In one example, the engine may be started before the transmission upshift begins and before the transmission clutches begin changing state if the engine is expected to take a longer amount of time to produce positive torque than the time expected to shift gears.If method 1500 judges that it is desirable to start the engine prior to the transmission upshift, method 1500 proceeds to 1522. Otherwise, method 1500 proceeds to 1526.

[0246] At 1522, method 1500 starts the engine and engages the driveline disconnect clutch. The engine may be started via rotating the engine via a starter motor that has a lower power output capacity than the DISG or via cranking the engine via the DISG. Further, the transmission shift may be delayed until the engine speed is synchronized with the DISG or impeller speed. Delaying the transmission shift may reduce driveline torque disturbance that may occur if engine torque increases before the off-going clutch is fully released. Method 1500 proceeds to 1524 after the engine is started and the driveline disconnect clutch is released.

[0247] At 1524, method 1500 upshifts the transmission after the driveline disconnect clutch is engaged. The transmission may be upshifted via applying and / or releasing pressure to one or more clutches that affect torque transfer through the transmission. Method 1500 ends after the transmission is shifted.

[0248] At 1526, method 1500 prevents an engine stop if conditions other than the impending transmission upshift exist to stop engine rotation. In other words, if the engine would be commanded to stop without a transmission upshift, then stopping the transmission's rotation is prevented. Additionally, the engine may be started at a time after the upshift has begun (e.g., during off-going clutch release (torque phase) or during on-going clutch application (inertia phase)) to provide additional torque to the driveline to meet the torque request. The engine and DISG torque may be adjusted to provide the desired amount of torque converter impeller torque.Method 1500 proceeds to end after engine stopping is prevented or after the engine is started, after the transmission upshift begins.

[0249] In this way, method 1500 may predict the transmission shift and the desired torque converter impeller torque to determine when to close the driveline disconnect clutch and start the engine. Method 1500 may enable engine torque to be seamlessly combined with DISG torque to create smooth acceleration during the transmission shift.

[0250] With reference to Fig. 16 is a diagram of an example sequence for determining when to start an engine according to the method of Fig. 15. The sequence of Fig. 16 can be achieved through the system of Fig. 1-3 are provided.

[0251] The first diagram from the top in Fig. 16 illustrates the desired driveline torque as a function of time. The desired driveline torque may be a desired torque converter impeller torque, a desired torque converter turbine torque, a desired wheel torque, or another driveline torque. The desired driveline torque may be determined from an accelerator pedal position or other input device. The solid curve 1602 represents the desired driveline torque. The dashed curve 1604 represents the predicted desired driveline torque (e.g., the desired driveline torque after a transmission gear shift). The Y-axis represents the desired driveline torque, and the desired driveline torque increases in the Y-axis direction. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.The horizontal line 1606 represents a limit of the torque that can be delivered to the driveline via the DISG.

[0252] The second diagram from the top in Fig. Figure 16 illustrates the transmission gear as a function of time. The Y-axis represents the transmission gear, and specific transmission gears are indicated along the Y-axis. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure. The solid curve 1608 represents the current or actual transmission gear. The dashed curve 1610 represents the predicted or future transmission gear.

[0253] The third diagram from the top in Fig. Figure 16 shows the desired engine state without transmission gear shift conditions as a function of time. The Y-axis represents the desired engine state, and the desired engine state is on for higher curve levels and off for lower curve levels. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0254] The fourth diagram from the top in Fig. Figure 16 represents the desired engine state based on all conditions as a function of time. The Y-axis represents the desired engine state, and the desired engine state is on for higher curve levels and off for lower curve levels. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0255] The fifth diagram from the top of Fig. Figure 16 represents the engine state as a function of time. The Y-axis represents the engine state, and the engine state is on for higher curve levels and off for lower curve levels. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0256] At time T 21 The desired driveline torque is greater than the amount of torque that can be delivered from the DISG to the driveline. The transmission is in 5th gear, and the desired engine state and the desired engine state without gear conditions are both at higher levels, indicating that it is desired for the engine to operate. The engine state is at a higher level, indicating that the engine is operating.

[0257] Between time T 21 and the time T 22The desired driveline torque decreases in response to a decreasing driver input (not shown). The transmission downshifts from 5th to 2nd gear, and the predicted transmission gear precedes the current or actual transmission gear. The desired engine state without gear conditions and the desired engine state remain at higher levels.

[0258] At time T 22The desired transmission state transitions to a lower level without gear conditions in response to vehicle speed and desired driveline torque to indicate that the engine can be stopped without transmission gear conditions in response to vehicle and engine operating conditions (e.g., brake applied, accelerator pedal not applied, and a vehicle speed less than a threshold speed). The desired engine state also transitions to a lower level to indicate stopping the engine in response to operating conditions, including the predicted transmission gear. The engine is stopped in response to the desired engine state.

[0259] Between time T 22 and the time T 23The desired driveline torque levels off and then increases. The predicted transmission gear increases from 2nd gear to 3rd gear as the desired driveline torque increases. The current transmission gear is held in 2nd gear. The engine remains stopped because the desired engine state and the desired engine state remain at a lower level without gear conditions.

[0260] At time T 23The desired engine state transitions to a higher level in response to the predicted desired driveline torque increasing after the shift to a level greater than 1606. The engine is started in response to the desired engine state transition. The desired engine state without gear conditions remains at a lower level to indicate that the engine would remain off without the increase in desired driveline torque expected after the transmission shift.

[0261] Between time T 23 and the time T 24The desired driveline torque increases and then decreases in response to a reduced driver demand (not shown). The desired driveline torque decreases to a level less than 1606 and remains near the 1606 level. The transmission downshifts from 5th gear to 3rd gear. The desired engine state and the desired engine state without gear conditions remain at higher levels, so the engine remains on.

[0262] At time T 24In the absence of gear conditions, the desired engine state transitions to a lower level to indicate that the engine may be stopped in response to the desired driveline torque, vehicle speed (not shown), and applied braking (not shown). However, the desired engine state remains at a high level in response to the predicted desired driveline torque increasing to a level greater than 1606, as predicted for the transmission shift to 4th gear. Consequently, an engine stop is prevented. Such conditions may exist when a vehicle is moving and when a driver decreases (e.g., eases off or reduces) an accelerator pedal command.

[0263] Between time T 24 and the time T 25The desired driveline torque increases and then decreases. The transmission shifts gears between 3rd and 5th gears in response to driver demand torque, vehicle speed (not shown), and brake condition (not shown). The desired engine state without gear conditions and the desired engine state remain at higher levels in response to the desired driveline torque.

[0264] After time T 25the desired driveline torque is decreased to less than level 1606 in response to a lower driver demand (not shown). The desired engine state without gear conditions and the desired engine state transition to a lower level to indicate that the engine should be stopped in response to the desired driveline torque, the brake pedal state (not shown), and the vehicle speed (not shown). The engine is stopped in response to the desired engine state.

[0265] Between time T 25 and the time T 26The desired driveline torque gradually increases, and the predicted transmission gear increases from 2nd gear to 3rd gear in response to the increasing desired driveline torque. The desired engine state and the desired engine state without gear conditions remain at a lower level, and the engine remains stopped.

[0266] At time T 26The desired engine state transitions to a higher level, and the engine is started in response to the increasing desired driveline torque and the predicted transmission gear. The desired engine state without gear conditions remains at a lower level, indicating that the engine would not be started without considering the predicted desired driveline torque after a predicted transmission gear shift being greater than 1606. By starting the engine prior to the actual gear shift, it may be possible to provide the desired driveline torque after a shift.

[0267] In this way, the engine may be started prior to a gear shift to provide a desired driveline torque after the gear shift. Further, the method predicts the shift so that the engine may be started before the desired driveline torque is actually requested. Starting the engine early may allow the engine to reach conditions where it can output torque to meet the desired driveline torque.

[0268] The procedures and systems of Fig. 1-3 and 15-16 provide a method for starting an engine, comprising: predicting a desired torque after a transmission upshift; and starting rotation of a stopped engine when the predicted desired torque after the transmission upshift is greater than a threshold amount of torque. The method includes where the desired torque is a torque converter impeller torque, and where predicting the desired torque and starting rotation occur during conditions where a driveline-integrated starter / generator is providing torque to the wheels, the transmission is in a forward gear, and the vehicle is moving. The method includes predicting the desired torque based on a predetermined transmission shift pattern.

[0269] In some examples, the method includes initiating rotation of the engine via a driveline disconnect clutch. The method includes disengaging the driveline disconnect clutch prior to rotating the engine. The method includes disposing the driveline disconnect clutch in the hybrid vehicle powertrain between a dual-mass flywheel and a driveline-integrated starter / generator. The method includes rotating the engine in response to the predicted desired driveline torque prior to shifting a transmission.

[0270] The procedures and systems of Fig. 1-3 and 15-16 provide for starting an engine, comprising: delivering torque to a vehicle driveline via an electric machine; scheduling a transmission upshift; and starting rotation of a stopped engine in response to the scheduled transmission upshift when a desired torque after the scheduled transmission upshift is greater than a threshold torque amount, and wherein the desired torque is based on torque of an in-driveline starter / generator after a transmission upshift time for engaging a transmission clutch relative to starting the engine. The method includes where the electric machine is an in-driveline starter / generator (DISG), and where the DISG is disposed in the hybrid vehicle driveline at a location between a driveline disconnect clutch and a transmission.

[0271] In some examples, the method includes the DISG providing torque to start rotation of the stopped engine via at least partially closing the driveline disconnect clutch. The method further includes upshifting the transmission after starting rotation of the engine. The method also includes the transmission being a dual countershaft dual-clutch transmission. The method includes the transmission being an automatic transmission. The method further includes enabling the engine to stop rotation if the desired torque is less than the threshold amount of torque after the transmission upshift timing for engaging the transmission clutch relative to starting the engine.

[0272] The procedures and systems of Fig. 1-3 and 15-16 provide a hybrid vehicle system comprising: an engine; a dual-mass flywheel having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side mechanically coupled to a second side of the dual-mass flywheel; a driveline-integrated starter / generator having a first side mechanically coupled to a second side of the driveline disconnect clutch; and a controller having non-transitory instructions executable to start the engine via closing the driveline disconnect clutch in response to a desired torque following a scheduled transmission upshift, wherein the engine is started in response to the scheduled transmission upshift before the transmission shifts. Such a system may improve driveline response time.

[0273] In one example, the hybrid vehicle system further includes additional instructions for preventing engine rotation from stopping if the engine is rotating prior to the scheduled transmission upshift. The hybrid vehicle system includes starting the engine by rotating the engine via the driveline integrated starter / generator in response to closing the driveline disconnect clutch. The hybrid vehicle system further includes additional instructions for upshifting the transmission after the engine is started. The hybrid vehicle system further includes additional instructions for enabling the engine to stop rotating in response to the desired torque after the scheduled transmission upshift. The hybrid vehicle system further includes additional instructions for delaying engine start until the scheduled transmission upshift is scheduled for a time less than a threshold amount of time.

[0274] With reference to Fig. 17 is a flowchart of a method for starting an engine to reduce transmission input torque during a transmission shift. The method of Fig. 17 can be stored as executable instructions in non-volatile memory in the Fig. 1-3 shown system. The procedure of Fig. 17 may decrease the amplitude and / or number of times torque changes are made to a DISG during vehicle operation to limit the torque applied to a transmission during transmission shifting.

[0275] At 1702, method 1700 judges whether or not an engine restart and transmission upshift are desired. An engine restart may be requested, for example, when a requested driveline torque is increased or when a driver releases a brake pedal. A transmission upshift may be requested, for example, in response to vehicle speed and a driveline torque request. In one example, a transmission shift schedule is empirically determined and stored in memory to be indexed by the vehicle speed and the driveline torque request. If method 1700 determines that a transmission upshift and engine start are requested, method 1700 proceeds to 1704. Otherwise, method 1700 proceeds to exit.

[0276] At 1704, method 1700 judges whether the DISG is available or not. Method 1700 may judge whether the DISG is available or not based on a DISG state flag stored in memory. Alternatively, method 1700 may judge whether a DISG is available or not based on operating conditions such as a battery state of charge. For example, if the SOC is less than a threshold level, the DISG may not be available. In another example, the DISG may not be available if the DISG temperature is greater than a threshold. If method 1700 judges that the DISG is available, the answer is yes and method 1700 proceeds to 1712. Otherwise, the answer is no and method 1700 proceeds to 1706.

[0277] At 1706, method 1700 releases a disengaging clutch at a scheduled rate. The disengaging clutch is a lower gear during an upshift. For example, the disengaging clutch releases a 2nd gear clutch during a 2nd to 3rd gear upshift. The clutch release rate may be empirically determined and stored in memory so that when the upshift occurs, the disengaging clutch may be released at a rate stored in memory. The disengaging clutch may be released via decreasing the oil pressure supplied to the disengaging clutch. Method 1700 proceeds to 1708 after the disengaging clutch is released.

[0278] At 1708, method 1700 begins applying the on-coming clutch to engage a higher gear after a predetermined amount of time since the off-coming clutch began to release. The on-coming clutch may be applied by increasing the pressure of the oil supplied to the on-coming clutch. The predetermined amount of time may be determined empirically and stored in memory for use during an upshift. In one example, the on-coming clutch is applied at a time that reduces the possibility of wear on the off-coming clutch by accelerating the output side of the off-coming clutch. Method 1700 proceeds to 1710 after application of the on-coming clutch is initiated.

[0279] At 1710, method 1700 applies or begins closing the driveline disconnect clutch at a controlled rate to reduce transmission input shaft torque. Specifically, the engine applies a load to the input side of the torque converter by closing the driveline disconnect clutch to reduce the torque converter impeller speed. In this manner, the amount of torque transferred through the torque converter to the transmission input shaft is reduced. In one example, the driveline disconnect clutch rate is adjusted based on the torque converter impeller speed when the driveline disconnect clutch is applied. For example, the driveline disconnect clutch application pressure is increased until the torque converter impeller speed is reduced to a threshold amount, and then the driveline disconnect clutch application pressure is no longer increased.Because the driveline disconnect clutch transfers torque from the input side of the transmission to the engine, the amount of torque transferred from the transmission to the engine is limited based on the impeller speed. Method 1700 proceeds to 1722 after the driveline disconnect clutch application pressure is increased and the driveline disconnect clutch is at least partially closed.

[0280] At 1712, method 1700 releases a disengaging clutch at a scheduled rate. Releasing the disengaging clutch allows a higher gear to be applied without transferring torque across two different gears. The disengaging clutch release rate may be determined empirically and stored in memory for retrieval during the upshift. Method 1700 proceeds to 1714 after disengaging the disengaging clutch is initiated.

[0281] At 1714, method 1700 increases the DISG output torque to increase the torque delivered to the torque converter impeller. In one example, the DISG torque is increased by an amount of torque used to accelerate the engine to a desired engine speed. The DISG torque may be increased via increasing an amount of current delivered to the DISG. In other examples, the DISG output torque may be decreased to a lower transmission input torque. Method 1700 proceeds to 1716 after the DISG torque is increased.

[0282] At 1716, method 1700 begins applying the on-coming clutch to engage a higher gear after a predetermined amount of time since the off-coming clutch began to release. The on-coming clutch may be applied by increasing the pressure of the oil supplied to the on-coming clutch. The predetermined amount of time may be determined empirically and stored in memory for use during an upshift. In one example, the on-coming clutch is applied at a time that reduces the possibility of wear on the off-coming clutch by accelerating the output side of the off-coming clutch. Method 1700 proceeds to 1718 after application of the on-coming clutch is initiated.

[0283] At 1718, method 1700 applies or begins closing the driveline disconnect clutch at a controlled rate to reduce transmission input torque and accelerate the engine to a desired cranking speed. Specifically, the engine applies a load to the input side of the torque converter by closing the driveline disconnect clutch to reduce the torque converter impeller speed. The driveline disconnect clutch application pressure may be modulated to control torque transfer across the driveline disconnect clutch. Further, the driveline disconnect clutch may be applied at any time during the inertia phase of the shift when the on-coming clutch is closed.

[0284] In one example, the driveline disconnect clutch application rate may be adjusted based on the torque converter impeller speed when the driveline disconnect clutch is applied. Since the driveline disconnect clutch transfers torque from the input side of the transmission to the engine, the amount of torque transferred to the engine is limited based on the impeller speed. In another example, a driveline disconnect clutch transfer function, which relates the transferred torque based on the amount of input torque provided to the driveline disconnect clutch and the driveline disconnect clutch application pressure, is multiplied by the DISG torque to determine an amount of torque transferred to the engine to start the engine.The driveline disconnect clutch application rate can be adjusted to deliver a desired cranking torque to the engine via the DISG and the driveline disconnect clutch.

[0285] In yet another example, the driveline disconnect clutch application rate may be controlled based on the DISG speed and a desired engine speed ramp-up rate. For example, a driveline disconnect clutch application rate may be retrieved from an empirically determined table that outputs the driveline disconnect clutch application rate when indexed by the DISG speed and desired engine acceleration. Method 1700 proceeds to 1720 after the driveline disconnect clutch application is initiated.

[0286] At 1720, method 1700 adjusts the DISG torque to provide a desired transmission input torque via the torque converter impeller during or after the inertia phase of the transmission upshift. When engine mass is relatively high, DISG output may be increased so that transmission input torque is not reduced more than desired. When engine mass is relatively low, DISG torque may be decreased so that transmission input torque is reduced by a desired amount. DISG torque may be adjusted by increasing or decreasing the current supplied to the DISG. Method 1700 proceeds to 1722 after DISG torque is adjusted.

[0287] At 1722, method 1700 starts the engine when the engine speed reaches a threshold speed by supplying fuel and a spark to the engine. In some examples, a starter other than the DISG may be engaged with the engine to provide torque to the engine in addition to the torque provided by the driveline disconnect clutch when the engine is started so that a desired engine cranking speed may be achieved. Method 1700 proceeds to exit after the engine is started.

[0288] In this way, the transmission output shaft torque can be reduced during an inertia phase of the shift, thus reducing driveline torque disturbances. Starting the engine by closing the driveline disconnect clutch reduces the transmission input shaft torque, thus reducing the transmission output shaft torque during the inertia phase of the shift.

[0289] With reference to Fig. 18 is an example sequence for starting an engine during a transmission gear shift according to the method of Fig. 17. The sequence of Fig. 18 can be achieved through the system of Fig. 1-3. The dashed curves are equivalent to the solid curves when the dashed curves are not visible.

[0290] The first diagram from the top in Fig. Figure 18 represents the transmission input shaft torque as a function of time. The torque at the transmission input shaft is equal to the transmission torque converter turbine torque. The Y-axis represents the transmission input shaft torque, and the transmission input shaft torque increases in the Y-axis direction. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure. The solid curve 1802 represents the transmission input shaft torque without starting the engine via closing the driveline disconnect clutch or providing a transmission input shaft torque reduction. The dashed curve 1804 represents the transmission input shaft torque when starting the engine via closing the driveline disconnect clutch and shifting to a higher gear.

[0291] The second diagram from the top in Fig. Figure 18 illustrates the transmission output shaft torque as a function of time. The Y-axis represents the transmission output shaft torque, and the transmission output shaft torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure. The solid curve 1806 represents the transmission output shaft torque without starting the engine via closing the driveline disconnect clutch or providing a transmission input shaft torque reduction. The dashed curve 1808 represents the transmission output shaft torque when starting the engine via closing the driveline disconnect clutch and shifting to a higher gear.

[0292] The third diagram from the top in Fig. Figure 18 depicts the driveline disconnect clutch state as a function of time. The Y-axis represents the driveline disconnect clutch state, with the driveline disconnect clutch open near the X-axis and closed near the top of the Y-axis. The amount of torque transmitted through the driveline disconnect clutch increases as the driveline disconnect clutch is closed. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0293] The fourth diagram from the top in Fig. Figure 18 represents engine speed as a function of time. The Y-axis represents engine speed, and engine speed increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0294] The fifth diagram from the top in Fig. Figure 18 represents DISC torque as a function of time. The Y-axis represents DISC torque, and DISC torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0295] At time T 27 The transmission does not shift and the engine is stopped. The DISG outputs torque to the driveline, and the transmission input shaft and output shaft torques are constant.

[0296] At time T 28The transmission begins shifting in response to a transmission shift pattern, the desired driveline torque (not shown), and the vehicle speed (not shown). The shift begins by releasing an off-going clutch. For example, during an upshift from 2nd gear to 3rd gear, the 2nd gear clutch (off-going clutch) releases before the 3rd gear clutch (on-going clutch) is applied. The transmission input shaft torque is held constant, although in some examples it may be increased to better maintain the transmission output shaft torque. The transmission output torque begins to decrease in response to the off-going clutch being released. The driveline disconnect clutch is shown open and the engine is stopped. The DISG torque is shown held at a constant value.

[0297] At time T 29The inertia phase begins by applying the oncoming clutch in response to the offcoming clutch being released. The driveline disconnect clutch begins to close as the oncoming clutch is applied and begins to close. Transmission input shaft torque is also shown decreasing in response to the driveline disconnect clutch closing because some DISG torque is transferred via the driveline disconnect clutch to rotate the engine. Engine speed begins to increase in response to driveline torque being applied to the engine. DISG torque is shown at a constant level.

[0298] Between time T 29 and the time T 30The driveline disconnect clutch state is shown modulated to control the amount of driveline torque applied to the engine. The driveline disconnect clutch application pressure may be modulated in response to engine speed and / or transmission output shaft speed to reduce driveline torque disturbances during shifting and engine starting. Spark and fuel (not shown) are also supplied to the engine so that the engine speed approaches the DISG speed. The transmission output shaft torque gradually increases when the driveline disconnect clutch is applied to restart the engine, as indicated by dashed line 1808. When the driveline disconnect clutch is not applied during the inertia phase, the transmission output shaft torque increases in response to the gear ratio change.Consequently, applying the driveline disconnect clutch during the inertia phase can reduce driveline torque disturbances.

[0299] At time T 30 The inertia phase of the transmission shift is completed when the engaging clutch (not shown) is fully applied, as indicated by the transmission output torque converging to a constant value. DISG torque is also shown increasing in response to the completion of the shift, allowing vehicle acceleration to continue.

[0300] In this way, driveline torque disturbance during shifting can be reduced. Furthermore, the driveline energy can be used to start the engine, allowing the DISG to provide less torque to start the engine.

[0301] The procedures and systems of Fig. 1-3 and 17-18 provide for shifting a transmission, comprising: coupling an engine to a transmission in response to a transmission upshift request. In this way, transmission input shaft torque may be reduced to control transmission output shaft torque during a shift. The method includes uncoupled the engine to the transmission prior to the transmission upshift request, the transmission being in a moving vehicle and in a forward drive gear, and the vehicle continuing to move and the transmission being upshifted to a higher gear. The method includes coupling the engine to the transmission via the driveline disconnect clutch disposed in a driveline between the engine and a torque converter.

[0302] In some examples, the method includes coupling the engine to the transmission during an inertia phase of the upshift. The method includes coupling the engine to the transmission after initiating release of an off-going clutch during the upshift. The method further includes starting the engine when engine speed reaches a threshold speed. The method includes the transmission being an automatic transmission and reducing input torque to the automatic transmission during the upshift.

[0303] The procedures and systems of Fig. 1-3 and 17-18 also provide shifting a transmission, comprising: decreasing input torque to a transmission in response to a transmission upshift request via selectively coupling an engine to an input shaft of the transmission, wherein the engine is not coupled to the transmission prior to the transmission upshift request. The method includes coupling the engine to the transmission via a driveline disconnect clutch. The method further includes a torque converter in a driveline disposed between the engine and the transmission. The method further includes increasing or decreasing torque from a driveline-integrated starter / generator during the upshift. The method includes increasing torque from the driveline-integrated starter / generator to maintain an impeller speed of a torque converter greater than a threshold speed.The method includes stopping engine rotation prior to the transmission upshift request.

[0304] The procedures and systems of Fig. 1-3 and 17-18 also provide a hybrid vehicle system comprising: an engine; a dual mass flywheel having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side mechanically coupled to a second side of the dual mass flywheel; a driveline integrated starter / generator (DISG) having a first side coupled to a second side of the driveline disconnect clutch and a second side; a transmission coupled to the DISG; and a controller having non-transitory instructions executable to initiate a transmission shift request and couple the engine to the transmission in response to the transmission shift request.

[0305] In some examples, the hybrid vehicle system further includes a torque converter disposed in a driveline between the transmission and the DISG. The hybrid vehicle system further includes additional commands to start the engine. The hybrid vehicle system further includes additional commands to couple the engine to the transmission via the driveline disconnect clutch. The hybrid vehicle system further includes additional commands to increase DISG torque in response to the transmission upshift request. The hybrid vehicle system further includes additional commands to decrease DISG torque in response to the transmission upshift request. The hybrid vehicle system further includes additional commands to accelerate the engine to a desired cranking speed.

[0306] With reference to Fig. 19 shows a method for improving vehicle driveline response when the driveline includes a dual mass flywheel. The method of Fig. 19 can be stored as executable instructions in the non-volatile memory of the Fig. 1-3 shown control unit 12.

[0307] At 1902, method 1900 determines operating conditions. The operating conditions may include, but are not limited to, engine speed, DMF input and output speed, requested driveline torque, DISG torque, driveline disconnect clutch state, and engine torque. Method 1900 proceeds to 1904 after the operating conditions are determined.

[0308] At 1904, method 1900 determines the speed and / or position of the upstream or engine side of the DMF. In alternative examples, the torque on the upstream side of the DMF may be determined. The speed and / or position on the downstream side of the DMF may be determined via a position sensor. The torque on the downstream side of the DMF may be determined via a torque sensor. Method 1900 proceeds to 1906 after the speed and / or position of the downstream side of the DMF are determined.

[0309] At 1906, method 1900 determines the speed and / or position downstream or on the driveline disconnect clutch side of the DMF. Alternatively, the torque on the downstream side of the DMF may be determined. The speed and / or position on the downstream side of the DMF may be determined via a position sensor. The torque on the downstream side of the DMF may be determined via a torque sensor. Method 1900 proceeds to 1908 after the speed and / or position of the downstream side of the DMF is determined.

[0310] At 1908, method 1900 determines a speed, position, or torque difference between the upstream side of the DMF and the downstream side of the DMF. In one example, the driveline disconnect clutch side of the DMF is a side of the DMF with desired speed and / or position. The speed and / or position on the engine side of the DMF is subtracted from the speed and / or position of the engine side of the DMF to provide a DMF speed and / or position error across the DMF. Alternatively, the torque on the engine side of the DMF may be subtracted from the torque on the upstream side of the DMF to provide a torque error.In some examples, a speed / position difference between a first side of the DMF and a second side of the DMF during driveline operation is compared to a position of the first side of the DMF and a position of the second side of the DMF when no torque is being transferred across the DMF.

[0311] In another example, a fast Fourier transform of the DMF upstream and downstream speed signals may be performed to determine the amplitude, or magnitude, and frequency of any speed oscillations on the upstream and downstream sides of the DMF. Method 1900 proceeds to 1910 after the speed error across the DMF and / or the frequencies and amplitudes of the speed upstream and downstream of the DMF are determined.

[0312] At 1910, method 1900 judges whether the speed and / or position error, or the amplitudes and frequencies on the upstream and downstream sides of the DMF, are greater than threshold levels. If so, method 1900 proceeds to 1912. Otherwise, method 1900 proceeds to exit.

[0313] At 1912, method 1900 judges whether or not driveline operating conditions are within a first operating window. For example, whether the upstream and downstream DMF speed error is greater than a first threshold level. In other examples, the torque difference or position difference across the DMF may be the basis for determining whether or not the driveline operating conditions are within a first operating window. In still other examples, the frequencies or frequency amplitudes are compared to threshold values. If the driveline operating conditions are within a first operating window, method 1900 proceeds to 1914. Otherwise, method 1900 proceeds to 1916.

[0314] At 1914, method 1900 modulates the transmission torque converter clutch (TCC) to dampen speed and / or torque oscillations across the DMF. The TCC is modulated via varying a duty cycle of a TCC command signal. In other examples, the frequency of the TCC is adjusted. The duty cycle of the TCC command is decreased to increase slip across the torque converter clutch, thereby increasing damping of the DMF. However, if the TCC is slipping by a threshold amount when the speed / position difference across the DMF is detected, the TCC may be commanded to a locked position by increasing the TCC duty cycle command. The amount of TCC adjustment may be based on an error between the desired value and an actual value. For example, the TCC duty cycle may be adjusted based on a difference between the upstream and downstream DMF speeds.The 1900 procedure continues to the end after the TCC is set.

[0315] At 1916, method 1900 assesses whether or not driveline operating conditions are within a second operating window. For example, whether the upstream and downstream DMF speed error is greater than a second threshold level. If the driveline operating conditions are within a second operating window, method 1900 proceeds to 1918. Otherwise, method 1900 proceeds to 1920.

[0316] At 1918, method 1900 adjusts the slip of the driveline disconnect clutch to adjust the damping across the DMF. In one example, the amount of slip across the driveline disconnect clutch is increased to increase the damping across the DMF. However, if the driveline disconnect clutch is dragging by a threshold amount when the speed / position error is detected, the driveline disconnect clutch is fully closed to stiffen the driveline. The driveline disconnect clutch application force or pressure may be adjusted based on a difference between the upstream and downstream DMF speeds or differences between desired and actual values of previously discussed variables, such as driveline frequency amplitude. Method 1900 proceeds to exit after the driveline disconnect clutch application force or pressure is adjusted.The procedure 1900 continues to the end after the driveline disconnect clutch is adjusted.

[0317] At 1920, method 1900 assesses whether or not driveline conditions are within a third operating window. For example, whether the upstream and downstream DMF speed error is greater than a third threshold level. If so, method 1900 proceeds to 1922. Otherwise, method 1900 proceeds to 1924.

[0318] At 1922, method 1900 adjusts the DISG torque to compensate for the speed / position or torque difference across the DMF. In one example, the DISG output torque is increased when the speed on the engine side of the DMF is greater than the speed on the driveline disconnect clutch side of the DMF. The output torque from the DISG is decreased when the speed on the engine side of the DMF is less than the speed on the driveline disconnect clutch side of the DMF. In one example, the DMF speed, DMF position, or DMF torque error is input to a function or table that outputs a current need to adjust the DISG torque. Further, the DISG torque is increased when the sign of the error signal is negative. The DISG torque is decreased when the sign of the error signal is positive.If an undesirable frequency or amplitude is detected, the torque applied to the DISG can be adjusted to be 180 degrees out of phase with the speed signal error to dampen the undesirable speed oscillations. Method 1900 proceeds to the end after the DISG torque is adjusted.

[0319] At 1924, method 1900 increases the application rate of the driveline disconnect clutch if the driveline disconnect clutch is not closed. The driveline disconnect clutch may be closed and the application pressure increased by increasing a duty cycle of the driveline disconnect clutch control signal. Method 1900 proceeds to exit after the driveline disconnect clutch is closed.

[0320] In other examples, driveline disconnect clutch slip, TCC, and DISG torque may be adjusted simultaneously to adjust damping across the DMF. In this way, method 1900 may adjust one or more actuators to increase damping or stiffen a driveline when a difference or error in speed / position, frequency, or torque across a DMF is greater than a threshold level.

[0321] With reference to Fig. 20 is an example sequence for compensating a DMF in a drive train according to the method of Fig. 19. The sequence of Fig. 20 can be achieved through the system of Fig. 1-3 are provided.

[0322] The first diagram from the top in Fig. Figure 20 represents vehicle speed as a function of time. The Y-axis represents vehicle speed, and vehicle speed increases in the direction of the Y-axis. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0323] The second diagram from the top in Fig. Figure 20 plots the driveline disconnect clutch application force as a function of time. The Y-axis represents the driveline disconnect clutch application force, and the driveline disconnect clutch application force increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0324] The third diagram from the top in Fig. Figure 20 represents the DMF speed as a function of time. The Y-axis represents the DMF speed, and the DMF speed increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0325] The fourth diagram from the top in Fig. Figure 20 represents the TCC application force as a function of time. The Y-axis represents the TCC application force, and the TCC application force increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0326] The fifth diagram from the top in Fig. Figure 20 represents DISC torque as a function of time. The Y-axis represents DISC torque, and DISC torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0327] At time T 31 The vehicle speed increases and the driveline disconnect clutch is fully applied, indicated by the driveline disconnect clutch application force being at the increased level. The DMF speed is also at a higher level, and the TCC clutch is closed, as indicated by the TCC application force being at the increased level. The DISG torque is also at a higher level, indicating that the DISG is delivering torque to the vehicle driveline.

[0328] At time T 32Vehicle speed reaches zero and the driveline disconnect clutch is opened in response to a low driveline torque request (not shown) to allow the engine to stop. The DMF speed is also reduced to zero when engine speed goes to zero. The TCC application force is reduced, so slip exists across the torque converter. DISG torque is also reduced, but the DISG continues to provide torque to the driveline so that oil pressure in the transmission can be maintained. In other words, DISG torque is transferred through the torque converter while the vehicle and engine are stopped. The DISG torque turns the transmission oil pump to maintain transmission oil pressure.

[0329] At time T 33DISG torque increases in response to increasing demand torque requested by the driver (not shown). Vehicle speed begins to increase in response to the increased DISG torque, and the driveline disconnect clutch begins to close in response to the increasing demand torque. DMF speed increases as driveline disconnect clutch application force increases to close the driveline disconnect clutch. Actual DMF speed begins to oscillate, and an error between the desired DMF speed and the actual DMF speed, or between the desired driveline vibration amplitude and the actual driveline vibration, increases to a level greater than a first threshold. TCC application force is further decreased to reduce DMF vibration and / or speed error.

[0330] Between time T 33 and the time T34 The engine and DISG deliver torque to the vehicle driveline. Furthermore, the driveline disconnect clutch remains fully closed, and the DMF speed varies as the engine speed varies.

[0331] At time T 34 Vehicle speed reaches zero and the driveline disconnect clutch is opened to allow the engine to stop in response to a low driveline torque request (not shown). DMF speed is also reduced to zero when engine speed goes to zero. TCC application force is again reduced, so slip exists across the torque converter. DISG torque is also reduced.

[0332] At time T 35DISG torque increases in response to an increasing demand torque (not shown) requested by the driver. Vehicle speed begins to increase in response to the increased DISG torque, and the driveline disconnect clutch begins to close in response to the increasing demand torque. DMF speed increases as driveline disconnect clutch application force increases to close the driveline disconnect clutch. Actual DMF speed begins with a greater amplitude than at time T 33 to oscillate and an error between the desired DMF speed and the actual DMF speed, or between the desired driveline vibration amplitude and the actual driveline vibration, increases to a level greater than a second threshold. The driveline disconnect clutch application force is reduced to reduce the DMF vibration and / or the speed error.

[0333] Between time T 35 and the time T 36 The engine and DISG deliver torque to the vehicle driveline. Furthermore, the driveline disconnect clutch remains fully closed, and the DMF speed varies as the engine speed varies.

[0334] At time T 36 Vehicle speed reaches zero, and the driveline disconnect clutch is opened in response to a low driveline torque request (not shown) to allow the engine to stop. DMF speed is also reduced to zero when engine speed goes to zero. TCC application force is again reduced, so slip is present across the torque converter. DISG torque is also reduced.

[0335] At time T 37DISG torque increases in response to increasing demand torque requested by the driver (not shown). Vehicle speed begins to increase in response to the increased DISG torque, and the driveline disconnect clutch begins to close in response to the increasing demand torque. DMF speed increases as driveline disconnect clutch application force increases to close the driveline disconnect clutch. Actual DMF speed begins at a greater amplitude than at time T 35to oscillate, and an error between the desired DMF speed and the actual DMF speed, or between the desired driveline vibration amplitude and the actual driveline vibration, increases to a level greater than a third threshold. The DISG output torque is adjusted (e.g., modulated) to dampen the DMF speed, frequency, or torque errors. Additionally, the application rate of the increasing driveline disconnect clutch application force may be increased to stiffen the driveline.

[0336] In this way, different actuators can be adjusted to control driveline torque disturbances that may be present at a DMF. The different actuators can be adjusted according to the disturbance (e.g., speed error, torque error, vibration) measured at the DMF.

[0337] The procedures and systems of Fig. 1-3 and 19-20 provide for adjusting the operation of a hybrid vehicle powertrain, comprising: adjusting an actuator in response to a speed or torque differential across a dual-mass flywheel (DMF) disposed in the hybrid vehicle powertrain between an engine and a driveline disconnect clutch, the DMF being a driveline component disposed between the engine and the driveline disconnect clutch. In this manner, driveline NVH may be reduced.

[0338] In one example, the method includes where the actuator is a torque converter clutch. The method includes where the actuator is a driveline integrated starter / generator. The method includes where the actuator is a driveline disconnect clutch. The method includes where the speed differential across the DMF is determined from an engine position sensor and a position sensor disposed in the hybrid vehicle driveline between the DMF and a driveline disconnect clutch. The method includes where the driveline disconnect clutch is disposed in the hybrid vehicle driveline between the DMF and a driveline integrated starter / generator. The method includes where the driveline disconnect clutch selectively disconnects the engine from a driveline integrated starter / generator and a transmission.

[0339] The procedures and systems of Fig. 1-3 and 19-20 also provide adjusting operation of a hybrid vehicle powertrain, comprising: engaging a driveline disconnect clutch to rotate an engine via an electric machine; and adjusting an actuator in response to a speed or torque differential across a dual mass flywheel (DMF) disposed in the hybrid vehicle powertrain between the engine and a driveline disconnect clutch, the DMF being a driveline component between the engine and the driveline disconnect clutch. The method includes where the electric machine is a driveline integrated starter / generator (DISG) disposed in the hybrid vehicle powertrain at a location between the driveline disconnect clutch and a transmission. The method includes where the actuator is the DISG.The method includes the DMF transmitting engine torque to an automatic transmission or a dual-countershaft dual-clutch transmission. The method includes the actuator being a different actuator for different conditions. The method includes a frequency component of an engine speed signal being a basis for adjusting the actuator. The method includes determining the frequency component via a fast Fourier transform (FFT).

[0340] The procedures and systems of Fig. 1-3 and 19-20 provide a hybrid vehicle system comprising: an engine; a dual mass flywheel (DMF) having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side mechanically coupled to a second side of the dual mass flywheel; a driveline integrated starter / generator (DISG) having a first side coupled to a second side of the driveline disconnect clutch; and a controller having non-transitory instructions executable to adjust an actuator in response to a differential across the DMF.

[0341] In one example, the hybrid vehicle system further comprises a transmission coupled to a second side of the DISG. The hybrid vehicle system includes where the difference is a position difference between a first side of the DMF and a second side of the DMF compared to a position of the first side of the DMF and a position of the second side of the DMF when no torque is being transferred across the DMF. The hybrid vehicle system includes where the actuator is the DISG. The hybrid vehicle system further comprises additional executable instructions to increase slip across the driveline disconnect clutch when a difference in speed between the first side and the second side of the DMF exceeds a threshold speed.The hybrid vehicle system further includes additional executable instructions to increase slip across a torque converter clutch when a difference in speed between the first side and the second side of the DMF exceeds a threshold speed.

[0342] The procedures and systems of Fig. 1-3 and 19-20 also provide adjusting operation of a vehicle driveline, comprising: adjusting an actuator in response to engagement of a driveline disconnect clutch to dampen vibration of a dual mass flywheel (DMF) disposed between an engine and the driveline disconnect clutch, and the DMF disposed between the engine and the driveline disconnect clutch.

[0343] With reference to Fig. 21 shows a method for suppressing driveline torque disturbances with respect to the application of a driveline disconnect clutch and its transfer function. The method of Fig. 21 can be stored as executable instructions in the non-volatile memory of the Fig. 1-3 shown control unit 12.

[0344] At 2102, method 2100 determines operating conditions. The operating conditions may include, but are not limited to, engine speed, DMF input and output speed, requested driveline torque, DISG torque, DISG speed, driveline disconnect clutch state, engine speed, torque converter impeller speed, torque converter turbine speed, and engine torque. Method 2100 proceeds to 2104 after the operating conditions are determined.

[0345] At 2104, method 2100 judges whether or not a driveline disconnect clutch is open. A driveline disconnect clutch may be determined to be open based on a variable stored in memory or based on a difference between engine speed and DISG speed. If method 2100 judges that the driveline disconnect clutch is not open, the answer is no and method 2100 proceeds to exit. If method 2100 judges that the driveline disconnect clutch is open, the answer is yes and method 2100 proceeds to 2106.

[0346] At 2106, method 2100 judges whether or not an engine start is requested via the DISG or whether or not engine torque should be applied to the driveline. An engine start may be requested if the requested driveline torque is greater than a threshold torque. Likewise, a request to deliver engine torque to the driveline may be present if the requested driveline torque is greater than a threshold torque. If method 2100 judges that an engine start is requested via the DISG or if engine torque should be applied to the driveline, the answer is yes and method 2100 proceeds to 2108. Otherwise, the answer is no and method 2100 proceeds to exit.

[0347] At 2108, method 2100 assesses whether a torque sensor in the vehicle driveline is at the Fig. 1-3 is present or not. If it is judged that a torque sensor is present, the answer is yes and process 2100 proceeds to 2110. Otherwise, the answer is no and process 2100 proceeds to 2130.

[0348] At 2110, method 2100 determines a difference between a desired driveline input torque and an actual driveline input torque at a selected location along the driveline. In some examples, the selected location for the driveline input torque may be at a torque converter impeller, a location between a driveline disconnect clutch and a DISG, a transmission output shaft, a torque converter turbine, a launch clutch input, or another driveline location. The actual or measured driveline input torque at the selected driveline location is determined from a torque sensor. The desired driveline input torque may be determined from an accelerator pedal position or another source. The difference in torque is the desired driveline input torque minus the actual driveline input torque.

[0349] Alternatively, if the torque sensor is located in the driveline between the DISG and the driveline disconnect clutch, the torque measured by a torque sensor may be added to a DISG torque command, causing the DISG to output additional torque to start the engine, thereby delivering the desired transmission input torque to the transmission. Method 2100 proceeds to 2112.

[0350] At 2112, method 2100 adjusts the current supplied to the DISG so that the desired driveline input torque is delivered to the driveline at a specified location, even if the driveline disconnect clutch transfer function is degraded. When the driveline torque sensor is used to feed back driveline input torque, the DISG torque is increased when the actual driveline input torque is less than the desired driveline input torque. The DISG torque is decreased when the actual driveline input torque is greater than the desired driveline input torque. In this manner, the DISG torque is adjusted in response to a difference between the desired driveline input torque and the actual or measured driveline input torque.

[0351] When the driveline torque sensor is implemented as a feedforward sensor, the torque sensor output is combined with the desired DISG torque to provide the desired DISG torque at the transmission input or another specified driveline location. In this manner, a torque sensor may be employed as a feedback or feedforward device. Method 2100 proceeds to 2114 after the DISG torque is adjusted.

[0352] At 2114, method 2100 increases the driveline disconnect clutch pressure to close the driveline disconnect clutch so that the engine may be cranked by the DISG or the driveline. The driveline disconnect clutch pressure is adjusted by indexing a function that outputs a driveline disconnect command or driveline disconnect application force based on a desired torque for transmission through the driveline disconnect clutch. Spark and fuel may also be supplied at 2114 after the engine is at a predetermined speed or in a predetermined position. Method 2100 proceeds to 2118 after the driveline disconnect clutch pressure begins to increase.

[0353] At 2116, method 2100 judges whether or not the engine has started. In one example, the engine may be judged to have started if the engine speed exceeds a threshold speed. If method 2100 judges that the engine has started, the answer is yes and method 2100 proceeds to 2118. Otherwise, the answer is no and method 2100 returns to 2110.

[0354] At 2118, method 2100 judges whether or not the engine speed has accelerated to and is equal to the DISG speed. The engine speed may be judged to be equal to the DISG speed when an engine speed sensor and a DISG speed sensor are substantially the same speed (e.g., ± 20 rpm -1). If method 2100 judges the engine speed to be equal to the DISG speed, the answer is yes and method 2100 proceeds to 2122. Otherwise, the answer is no and method 2100 proceeds to 2120.

[0355] At 2120, method 2100 adjusts the engine speed to the DISG speed. The engine speed may be adjusted to the DISG speed by adjusting engine torque via a throttle and fuel injection. Further, the engine speed may be adjusted to achieve the DISG speed by fully closing the driveline disconnect clutch. However, fully closing the driveline disconnect clutch before the engine speed matches the DISG may increase driveline torque disturbances. Method 2100 returns to 2118 after the engine is adjusted to match the DISG speed.

[0356] At 2122, method 2100 locks the driveline disconnect clutch. The driveline disconnect clutch may be locked by supplying more than a threshold amount of pressure to the driveline disconnect clutch. Method 2100 proceeds to exit after the driveline disconnect clutch is locked.

[0357] At 2130, method 2100 opens the torque converter clutch (TCC). The torque converter clutch is opened so that torque at the torque converter impeller can be estimated based on torque converter operating conditions. Alternatively, torque converter turbine torque can be estimated, if desired. Method 2100 proceeds to 2132 after the TCC is opened.

[0358] At 2132, method 2100 transitions the DISG from a torque control mode to a speed control mode such that the DISG follows a desired speed. The DISG follows the desired speed by making torque adjustments to the DISG based on a difference between the desired DISG speed and the actual DISG speed. Thus, the DISG speed is controlled by adjusting the DISG torque in response to the actual or measured DISG speed. Additionally, method 2100 estimates an amount of torque the driveline disconnect clutch will provide to start the engine. The desired amount of torque to start the engine may be determined empirically and stored in memory as a transfer function.The desired amount of torque to start the engine may be transferred to the engine via the driveline disconnect clutch by indexing a function describing the driveline disconnect clutch transfer function. The function outputs a driveline disconnect clutch actuation command that provides the desired driveline disconnect clutch torque. The function is indexed via the desired driveline disconnect clutch torque. Method 2100 proceeds to 2134 after the DISG enters the speed control mode from torque control mode and determines an amount of torque to supply to the engine via the driveline disconnect clutch so that the engine can be cranked.

[0359] At 2134, method 2100 commands the DISG to a desired speed that is a function of the torque converter turbine speed and the desired torque converter impeller torque to achieve a desired torque converter impeller torque. The desired torque converter impeller torque may be determined from an accelerator pedal input or a controller (e.g., desired driveline torque). The desired DISG speed is determined via indexing one or more functions that describe the operation of a torque converter (e.g., see Fig. 45-47). Specifically, a ratio of the torque converter turbine speed to the torque converter impeller speed is multiplied by a torque converter capacity factor (e.g., a torque converter transfer function). The result is then multiplied by the torque converter impeller speed squared to provide the torque converter impeller torque.

[0360] Consequently, if the torque converter capacity factor, the torque converter impeller torque, and the torque converter turbine speed are known, the torque converter impeller speed that provides the torque converter impeller torque can be determined. In this manner, the torque converter transfer function is the basis for providing a desired torque converter impeller torque when no driveline torque sensor is provided. The DISG is commanded to the torque converter impeller speed that can provide the desired torque converter impeller torque, even if the driveline disconnect clutch application force that provides a desired engine cranking torque is incorrect. Additionally, the amount of torque determined at 2132 to be applied by the driveline disconnect clutch can be added to the DISG torque command that provides the desired DISG speed in the speed control mode.In this manner, the torque transferred from the DISG to the engine via the driveline disconnect clutch may be added to the DISG torque command so that the DISG achieves the desired torque converter impeller speed and torque even when the driveline disconnect clutch is applied. Method 2100 proceeds to 2136 after the DISG speed is set.

[0361] At 2136, method 2100 increases the driveline disconnect clutch pressure to close the driveline disconnect clutch so that the engine may be cranked by the DISG or the driveline. The driveline disconnect clutch pressure is closed to provide the desired amount of torque to crank the engine, as determined at 2132. Driveline spark and fuel may also be supplied at 2136 after the engine is at a predetermined speed or in a predetermined position. Method 2100 proceeds to 2138 after the driveline disconnect clutch pressure begins to increase.

[0362] At 2138, method 2100 judges whether or not the engine has started. In one example, the engine may be judged to have started if the engine speed exceeds a threshold speed. If method 2100 judges that the engine has started, the answer is yes and method 2100 proceeds to 2140. Otherwise, the answer is no and method 2100 returns to 2132.

[0363] At 2140, method 2100 judges whether or not the engine speed has accelerated to and is equal to the DISG speed. The engine speed may be judged to be equal to the DISG speed when an engine speed sensor and a DISG speed sensor are substantially the same speed (e.g., ± 20 rpm -1). If method 2100 judges that the engine speed is equal to the DISG speed, the answer is yes and method 2100 proceeds to 2144. Otherwise, the answer is no and method 2100 proceeds to 2142.

[0364] At 2142, method 2100 adjusts the engine speed to the DISG speed. The engine speed may be adjusted to the DISG speed by adjusting engine torque via a throttle and fuel injection. Further, the engine speed may be adjusted to achieve the DISG speed by fully closing the driveline disconnect clutch. However, fully closing the driveline disconnect clutch before the engine speed matches the DISG may increase driveline torque disturbances. Method 2100 returns to 2140 after the engine is adjusted to match the DISG speed.

[0365] At 2144, method 2100 locks the driveline disconnect clutch. The driveline disconnect clutch may be locked by supplying more than a threshold amount of pressure to the driveline disconnect clutch. Method 2100 proceeds to exit after the driveline disconnect clutch is locked.

[0366] In this way, the torque converter transfer function may be a basis for estimating and delivering the desired torque converter impeller torque when a driveline torque sensor is not present and when the driveline disconnect clutch torque transfer function is degraded. On the other hand, when a driveline torque sensor is available, the torque sensor output may be a basis for adjusting the DISG torque so that a desired torque converter impeller torque can be delivered even when the driveline disconnect clutch torque transfer function is degraded.

[0367] With reference to Fig. 22 is an example sequence for compensating a driveline disconnect clutch transfer function according to the method of Fig. 21. The sequence of Fig. 22 can be achieved through the system of Fig. 1-3 are provided.

[0368] The first diagram from the top in Fig. Figure 22 illustrates the base DISG torque demand as a function of time. The base DISG demand, in one example, is DISG torque delivered to the driveline without feedback from a driveline torque sensor or feedback from torque converter operating conditions. The Y-axis represents the base DISG torque, and the base DISG torque increases in the Y-axis direction. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0369] The second diagram from the top in Fig. Figure 22 represents the torque converter impeller torque as a function of time. The Y-axis represents the torque converter impeller torque, and the torque converter impeller torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure. The solid curve 2202 represents the desired torque converter impeller torque. The dashed curve 2204 represents the actual torque converter impeller torque. The actual torque converter impeller torque is equal to the desired torque converter impeller torque when only the desired torque converter impeller torque is visible.

[0370] The third diagram from the top in Fig. Figure 22 shows the driveline disconnect clutch force as a function of time. The Y-axis represents the driveline disconnect clutch force, and the driveline disconnect clutch force increases in the direction of the Y-axis arrow. The driveline disconnect clutch is closed at higher force and open at lower force. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0371] The fourth diagram from the top in Fig. Figure 22 depicts a DISC torque setting as a function of time. Increasing the torque setting increases the DISC torque. The Y-axis represents the DISC setting torque, and the DISC setting torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0372] The fifth diagram from the top in Fig. Figure 22 represents engine speed as a function of time. The Y-axis represents engine speed, and engine speed increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0373] At time T 38 DISG torque is at a higher level, as is torque converter impeller torque. The driveline disconnect clutch is closed, and there is no DISG torque adjustment because the actual torque converter impeller torque is equal to the desired torque converter impeller torque. Engine speed is at an elevated level to indicate that the engine is operating.

[0374] At time T 39the base DISG torque is reduced to zero; however, in some examples, the base DISG torque may be greater than zero to provide transmission fluid pressure. The engine is stopped, and the torque converter impeller torque is also reduced to zero. The driveline disconnect clutch is opened, decoupled from the DISG. Between time T 39 and the time T 40 the power machine and the DISG remain switched off.

[0375] At time T 40The base DISG torque increases in response to increasing driver demand torque (not shown) and in response to the driveline disconnect clutch force, which can be converted into an amount of torque transferred to the engine through the driveline disconnect clutch. The engine is also rotated in response to the driver demand torque so that it is started. The engine is rotated by increasing the driveline disconnect clutch application force in response to the driver demand torque so that torque can be transferred from the DISG to rotate the engine. The DISG torque transferred to the engine is estimated based on the driveline disconnect clutch force. Specifically, an empirically determined transfer function indexed by the driveline disconnect clutch force outputs a driveline disconnect clutch torque.The commanded DISG torque is the sum of the driveline disconnect clutch torque and the driver demand torque. In one example, the driver demand torque is a desired torque converter impeller torque. If the driveline disconnect clutch torque is overestimated or underestimated, the actual torque converter impeller torque will differ from the desired torque converter impeller torque.

[0376] In this example, the actual torque converter impeller torque is less than the desired torque converter impeller torque because the driveline disconnect clutch force is increased. Consequently, the driveline disconnect clutch torque was underestimated, and less torque is being supplied from the DISG to the torque converter impeller. As a result, the DISG torque is increased to correct the difference between the desired torque converter impeller torque and the actual torque converter impeller torque. The DISG torque increase is shown in the DISG torque adjustment graph, added to the base DISG torque request shown in the first graph and output to the DISG. In some examples, the estimated driveline disconnect clutch transfer function is further adjusted in response to the DISG torque adjustment.For example, if the DISG torque is increased by 2 Nm, the driveline disconnect clutch transfer function is adjusted to reflect the driveline disconnect clutch transferring an additional 2 Nm at the current driveline disconnect clutch application force.

[0377] The actual torque converter impeller torque can be determined via a torque sensor or alternatively from the torque converter impeller speed, the torque converter turbine speed and the torque converter capacity factor, as described with regard to Fig. 21 and 45-47. The desired torque converter impeller torque can be determined from an accelerator pedal position or a control unit request.

[0378] At time T 41The engine is started and the engine has accelerated to the same speed as the DISG. Further, the driveline disconnect clutch is closed in response to the engine speed equal to the DISG speed. The DISG torque setting is decreased after the driveline disconnect clutch is closed in response to the actual torque converter impeller torque being substantially equal (e.g., ± 10 Nm) to the desired torque converter impeller torque.

[0379] Consequently, the procedures and systems of Fig. 1-3 and 21-22, operating a hybrid vehicle powertrain, comprising: opening a torque converter clutch in response to an engine start request; and adjusting a speed of a driveline integrated starter / generator (DISG) in response to a desired torque converter impeller speed. In this manner, compensation for a driveline disconnect clutch may be provided. The method includes where adjusting the DISG speed comprises adjusting the DISG speed as a function of the torque converter turbine speed and the desired torque converter impeller torque. The method includes where the desired torque converter impeller torque is based on a driver demand torque. The method includes adjusting the DISG speed via adjusting a DISG torque.

[0380] In some examples, the method further includes adjusting the DISG torque in response to an estimated driveline disconnect clutch torque. The method includes basing the estimated driveline disconnect clutch torque on a driveline disconnect clutch application force. The method further includes operating the DISG in a speed control mode when adjusting the DISG speed.

[0381] The procedures and systems of Fig. 1-3 and 21-22 provide for operating a hybrid vehicle powertrain, comprising: opening a torque converter clutch in response to an engine start request; operating a driveline integrated starter / generator (DISG) in a speed control mode; adjusting DISG speed in response to a desired torque converter impeller speed; and starting an engine via closing the driveline disconnect clutch. The method includes partially closing the driveline disconnect clutch in response to a driveline disconnect clutch application force, and estimating driveline disconnect clutch torque based on a driveline disconnect clutch application force.

[0382] In some examples, the method includes adjusting the DISG torque in response to the estimated driveline disconnect clutch torque. The method further includes adjusting the DISG speed in response to a desired torque converter impeller torque. The method includes adjusting the DISG speed concurrent with driveline disconnect clutch closing. The method further includes adjusting a driveline disconnect clutch transfer function in response to a DISG adjustment torque output during driveline disconnect clutch closing.The method includes where starting the engine via closing the driveline disconnect clutch includes partially closing the driveline disconnect clutch and then fully closing the driveline disconnect clutch such that the driveline disconnect clutch input speed equals the driveline disconnect output speed when the engine speed is substantially equal to the DISG speed.

[0383] The procedures and systems of Fig. 1-3 and 21-22 provide a hybrid vehicle powertrain system comprising: a torque converter; a driveline integrated starter / generator (DISG); an engine; a driveline disconnect clutch disposed in a driveline between the engine and the DISG; and a controller having executable non-transitory instructions for operating the DISG in a speed control mode and providing a desired torque converter impeller torque via adjusting the DISG speed in response to a torque converter turbine speed and the desired torque converter impeller torque.

[0384] In some examples, the hybrid vehicle powertrain system further includes additional executable non-transitory instructions for closing the driveline disconnect clutch at a first time when, following an engine stop, the engine speed is substantially equal to the DISG speed. The hybrid vehicle powertrain system further includes additional executable non-transitory instructions for closing the driveline disconnect clutch in response to a request to start the engine. The hybrid vehicle powertrain system further includes additional executable non-transitory instructions for estimating driveline disconnect clutch torque based on a driveline disconnect clutch application force. The hybrid vehicle powertrain system further includes a DISG speed sensor and a torque converter turbine speed sensor for determining torque converter turbine speed.The hybrid vehicle powertrain system includes that the speed control mode includes adjusting DISG torque to adjust DISG speed.

[0385] The procedures and systems of Fig. 1-3 and 21-22 provide operation of a hybrid vehicle powertrain, comprising: adjusting an output torque of a driveline integrated starter / generator (DISG) in response to a difference between a desired driveline torque and an actual driveline torque during at least partial closure of a driveline disconnect clutch. In this manner, a desired torque may be delivered even if the estimate of the driveline disconnect torque includes an error. The method includes where the desired driveline torque is a desired torque converter impeller torque and where the actual driveline torque is an actual torque converter impeller torque.

[0386] In one example, the method includes where the desired driveline torque is based on a driver demand torque. The method further includes adjusting an output torque of the DISG based on an estimate of the driveline disconnect clutch open-loop torque. The method further includes where the estimate of the driveline disconnect clutch open-loop torque is based on a driveline disconnect clutch apply command. The method further includes cranking an engine via closing the driveline disconnect clutch. The method further includes starting the engine via supplying fuel and a spark to the engine before the driveline disconnect clutch is fully closed.

[0387] The procedures and systems of Fig. 1-3 and 21-22 provide operation of a hybrid vehicle powertrain, comprising: adjusting an output torque of a driveline integrated starter / generator (DISG) in response to a difference between a desired driveline torque and an actual driveline torque during at least partial engagement of a driveline disconnect clutch; and adjusting a driveline disconnect clutch transfer function based on the difference between the desired driveline torque and the actual driveline torque. The method includes where the transfer function describes a driveline disconnect clutch torque as a function of the driveline disconnect clutch application force.

[0388] In some examples, the method further includes starting an engine via at least partially closing the driveline disconnect clutch. The method further includes starting the engine via supplying spark and fuel to the engine prior to fully closing the driveline disconnect clutch. The method further includes fully closing the driveline disconnect clutch in response to engine speed being substantially equal to the DISG speed at a first time since the engine stop. The method includes basing the desired driveline torque on an accelerator pedal input. The method includes basing the actual driveline torque on an output of a torque sensor.

[0389] The procedures and systems of Fig. 1-3 and 21-22 provide a hybrid vehicle powertrain system comprising: a driveline torque sensor; a driveline integrated starter / generator (DISG); an engine; a driveline disconnect clutch disposed in a driveline between the engine and the DISG; and a controller having executable non-transitory instructions for adjusting DISG output torque in response to a difference between a desired driveline torque and a driveline torque sensor output during application of the driveline disconnect clutch. The hybrid vehicle powertrain system further includes additional executable non-transitory instructions for closing the driveline disconnect clutch at a first time after an engine start at which engine speed is substantially equal to DISG speed.

[0390] In some examples, the hybrid vehicle powertrain system further includes additional executable non-transitory instructions for closing the driveline disconnect clutch in response to a request to start the engine. The hybrid vehicle powertrain system further includes additional executable non-transitory instructions for adjusting a driveline disconnect clutch transfer function in response to the difference between the desired driveline torque and the output of the driveline torque sensor. The hybrid vehicle powertrain system includes where the driveline torque sensor is disposed between a torque converter impeller and the DISG. The hybrid vehicle powertrain system includes where the driveline torque sensor is disposed between a torque converter turbine and a transmission gear set.

[0391] With reference to Fig. 23 is a flowchart of a method for improving engine restart after stopping combustion in an engine. The method of Fig. 23 can be stored as executable instructions in a non-volatile memory of the control unit 12 in Fig. 1-3 must be saved.

[0392] At 2302, method 2300 determines operating conditions. The operating conditions may include, but are not limited to, engine speed, engine position, driveline disconnect clutch state, DISG speed, and ambient temperature. Method 2300 proceeds to 2304 after the operating conditions are determined.

[0393] At 2304, method 2300 judges whether or not conditions exist to automatically stop engine rotation. In one example, engine rotation may stop when the desired driveline torque is less than a threshold. In another example, engine rotation may be stopped when the vehicle speed is less than a threshold speed and when the engine torque is less than a threshold torque. If method 2300 judges that conditions exist to automatically stop engine rotation, method 2300 proceeds to 2306. Otherwise, method 2300 proceeds to exit.

[0394] At 2306, method 2300 sequentially terminates fuel injection to the engine cylinders so that combustion of fuel in the engine cylinders is not stopped in the middle of fuel injection to a particular cylinder. Method 2300 proceeds to 2308 after fuel injection is terminated.

[0395] At 2308, method 2300 judges whether the engine speed is below an upper noise, vibration, and harshness (NVH) threshold speed and above a lower NVH threshold speed. If so, the answer is yes, and method 2300 proceeds to 2310. Otherwise, the answer is no, and method 2300 returns to 2330.

[0396] At 2310, method 2300 judges whether or not the engine crankshaft angle is at a predetermined position when the engine is rotating. In one example, the predetermined position is a crankshaft angle within a predetermined number of crankshaft degrees after a particular cylinder rotates through the compression stroke at top dead center (e.g., within 90 crankshaft degrees after the compression stroke at top dead center of a cylinder for a four-cylinder engine). If method 2300 judges that the engine crankshaft angle is not at a predetermined position, the answer is no and method 2300 returns to 2308. Otherwise, the answer is yes and method 2300 proceeds to 2312.

[0397] At 2312, method 2300 commands the starter to engage the starter pinion shaft and the starter pinion gear with the engine flywheel ring gear. The starter pinion shaft may be moved via a solenoid, and the starter pinion gear may begin rotating when the pinion shaft is fully extended. In other examples, the starter pinion shaft and the starter pinion gear may be separately controlled to enable independent activation. Method 2300 proceeds to 2314 after the starter pinion shaft and the starter pinion gear are commanded to engage the engine.

[0398] At 2314, method 2300 judges whether the pinion shaft and pinion gear are fully engaged with the engine flywheel. In one example, it may be determined that the pinion shaft and pinion gear have engaged the engine via sensor outputs (e.g., a limit switch) or via starter current. If method 2300 judges that the pinion shaft and pinion gear have engaged the engine, the answer is yes and method 2300 proceeds to 2316. Otherwise, the answer is no and method 2300 proceeds to 2322.

[0399] At 2316, method 2300 sets the engine throttle to a second position based on the pinion shaft and pinion gear engaging the engine flywheel in preparation for a possible driver change of mind regarding stopping the engine. In one example, the second throttle position is more open than a first throttle position at 2322. The engine throttle position is set to a more open position to provide higher engine torque if a driver change of mind occurs after starter engagement. Engine torque may be affected when the pinion gear is engaged with the flywheel. Adjusting the engine air amount may compensate for the effect an engaged pinion gear may have on engine restart and engine deceleration.Method 2300 proceeds to 2318 after the engine throttle position is set.

[0400] At 2318, method 2300 judges whether or not a driver change of mind has occurred since the starter pinion shaft and starter pinion engagement was commanded. A driver change of mind indicates that the driver wishes to continue applying torque to the vehicle wheels to maintain or increase vehicle speed. In one example, a driver change of mind may be indicated by releasing a brake pedal or increasing an engine torque command via an accelerator pedal. If method 2300 judges that a driver change of mind is requested before engine rotation stops, the answer is yes and method 2300 proceeds to 2320. Otherwise, the answer is no and method 2300 returns to 2308.

[0401] At 2320, method 2300 cranks the engine via the starter motor and restarts the engine because the starter pinion shaft and pinion have engaged the engine flywheel. Fuel and an ignition spark are also again delivered to the engine cylinders to facilitate combustion in the engine cylinders. Method 2300 ends after the engine is cranked and restarted.

[0402] At 2322, method 2300 sets the engine throttle to a first position based on the pinion shaft and pinion not engaging the engine flywheel. In one example, the first throttle position is more closed than a second throttle position at 2316. The engine throttle position is set to a more closed position to reduce engine airflow and reduce oxidation within an exhaust system catalyst. Method 2300 returns to 2308 after the engine throttle position is set to the first position.

[0403] At 2330, method 2300 judges whether the engine speed is less than the lower NVH speed threshold and whether or not the engine speed is above an engagement speed threshold. The engagement speed is an engine speed below which the engine can rotate in a reverse direction while the engine is stopped. If the engine speed is above the engagement speed and below the lower NVH speed threshold, the answer is yes and method 2300 proceeds to 2332. Otherwise, the answer is no and method 2300 proceeds to 2350. Method 2300 also terminates the attempt to engage the starter at engine speeds below the engagement speed and above zero engine speed.

[0404] At 2332, method 2300 commands the starter pinion shaft and starter pinion to engage the engine flywheel ring gear. The starter pinion shaft and starter pinion may be commanded to engage the engine flywheel ring gear as described at 2312. Method 2300 proceeds to 2334 after the starter pinion shaft and starter pinion are commanded to engage the engine flywheel.

[0405] At 2334, method 2300 judges whether or not the pinion shaft and pinion gear are engaged with the engine flywheel ring gear. Method 2300 judges whether the pinion shaft and pinion gear are engaged with the flywheel ring gear, as described at 2314. If method 2300 judges that the flywheel is engaged with the pinion and pinion shaft, the answer is yes and method 2300 proceeds to 2336. Otherwise, the answer is no and method 2300 proceeds to 2342.

[0406] At 2336, method 2300 adjusts the throttle position to a fourth position. Because engagement of the starter pinion shaft and starter pinion with the engine flywheel occurs at a lower engine speed, it may be desirable to adjust engine braking via controlling engine air volume via the throttle to a different extent compared to when attempting engagement of the starter pinion shaft and starter pinion with the engine flywheel ring gear at a higher engine speed. Further, adjusting engine air volume may compensate for pinion engagement. In one example, the fourth position is a position where the throttle is more closed than in the first and second positions at 2322 and 2316.Further, the fourth throttle position is more open than the third throttle position at 2342 to prepare for a driver change of mind condition. Adjusting the throttle based on engine speed may also provide finer control of the engine position at engine stop. Method 2300 proceeds to 2338 after the throttle is adjusted to the fourth position.

[0407] At 2338, method 2300 judges whether or not a driver change of mind is present. A driver change of mind may be determined as described at 2318. If method 2300 judges that a driver change of mind is present, the answer is yes and method 2300 proceeds to 2340. Otherwise, the answer is no and method 2300 returns to 2310.

[0408] At 2340, method 2300 cranks the engine for starting and provides spark and fuel to the engine. Method 2300 may crank the engine via the starter or the DISG, as described at 2320. Method 2300 proceeds to exit after the engine cranks and restarts in response to the driver change of mind.

[0409] At 2342, method 2300 sets the throttle to a third position. The third position may be a throttle position that is more closed-open than the fourth position described at 2336. The third position may also be a throttle position that is more closed than the first and second positions described at 2322 and 2316. Method 2300 returns to 2310 after the engine throttle position is set.

[0410] At 2350, method 2300 commands the starter pinion shaft and starter pinion to engage the engine flywheel ring gear after the engine stops rotating if not engaged. Engaging the starter pinion shaft and starter pinion after the engine stops may reduce starter and / or ring gear wear. By engaging the starter pinion shaft and starter pinion before the engine is restarted, it may be possible to further reduce engine startup time. Method 2300 proceeds to 2352 after the starter pinion shaft and starter pinion are commanded to engage the engine flywheel ring gear.

[0411] At 2352, the engine is automatically restarted in response to operating conditions after the engine stops rotating. The engine may be restarted in response to an engine torque request by a driver or in response to a driver releasing a brake. An automatic engine start occurs when the engine is restarted without a driver actuating or operating a device that has a single function of starting an engine (e.g., a start key switch). An automatic engine start may be initiated by a driver actuating or operating a device that has more than one function, such as a brake pedal that can apply vehicle braking, or secondarily as an indication of when to start the engine. Method 2300 restarts the engine via a starter motor or via the DISG and proceeds to exit.

[0412] In this way, the procedure of Fig. 23 adjust a position of a throttle valve in response to the starter intervention to further improve engine restart in the event of a driver change of mind. Furthermore, the method of Fig. 23 adjusts the throttle position during engine stop according to the engine speed to improve the engine stop position by limiting the engine reverse rotation.

[0413] With reference to Fig. 24 is an example sequence for improving engine restart and engine after stopping combustion according to the method of Fig. 23. The sequence of Fig. 24 can be achieved through the system of Fig. 1-3 are provided.

[0414] The first diagram from the top in Fig. Figure 24 illustrates engine speed as a function of time. The Y-axis represents engine speed, and engine speed increases in the direction of the Y-axis. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure. Horizontal line 2402 represents an upper NVH engine speed threshold. Horizontal line 2404 represents a lower NVH engine speed threshold. Horizontal line 2406 represents a pinion engagement speed threshold, wherein the pinion is not engaged when engine speed is below horizontal line 2406 unless the engine has stopped spinning. The engagement threshold may reduce starter degradation.

[0415] The second diagram from the top in Fig. Figure 24 shows the fuel injection state as a function of time. The Y-axis represents the fuel injection state. Fuel injection is active when the curve is at a higher level. Fuel injection is stopped when the curve is at a lower level. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0416] The third diagram from the top in Fig. Figure 24 depicts engine throttle position as a function of time. The Y-axis represents engine throttle position, and engine throttle position increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0417] The fourth diagram from the top in Fig. Figure 24 illustrates the starter pinion state as a function of time. The Y-axis represents the starter pinion state, and mesh levels are described alongside the Y-axis. The pinion is retracted when the curve is at the RET level. The pinion is advanced but not engaged when the curve is at the ADV level. The pinion is engaged with the engine flywheel when the curve is at the ENG level. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0418] The fifth diagram from the top in Fig. Figure 24 represents the vehicle brake state (e.g., friction brake state) as a function of time. The Y-axis represents the vehicle brake state, and the brake is applied when the curve is at a higher level. The brake is released when the curve is at a lower level. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0419] At time T 42 The engine speed is increased, fuel injection is active, the throttle is partially open, the starter is not engaged, and the brake is not applied. These conditions indicate a vehicle traveling at a moderate speed (e.g., 40 MPH). Between time T 42 and the time T 43 the vehicle brakes are applied to slow the vehicle. Under the conditions shown, the vehicle can be between time T42 and the time T 43 drive or may have stopped.

[0420] At time T 43Engine combustion is stopped in response to the application of the vehicle brake and a decrease in throttle position based on the driver demand torque. Consequently, the engine speed is reduced to be at or less than the upper NVH engine speed threshold 2402. The starter pinion is commanded to engage the engine flywheel, but the pinion only moves forward and does not fully engage the engine flywheel. The throttle position is reduced in response to the engine speed being less than the upper NVH threshold and greater than the lower NVH threshold. Further, the throttle position is adjusted in response to the starter pinion position being advanced but not engaged. The throttle is opened to a first position 2410.The engine speed continues to decrease and the pinion comes into contact with the flywheel just before time T. 44 engaged. The engine throttle position is adjusted to a second position 2412 in response to the pinion gear engaging the engine flywheel. The second throttle position is more open than the first position. By further opening the throttle after the pinion gear is engaged, it may be possible to prepare for a driver change of mind so that engine restart may be improved.

[0421] At time T 44The brake pedal is released by the driver, which is interpreted as a change of mind regarding stopping the engine. Fuel injection is reactivated, and the starter motor delivers engine starting torque via the engaged pinion. The engine restarts, and the pinion is returned shortly thereafter. Between time T 44 and the time T 45 The engine is accelerated and decelerated under varying driving conditions. The brake is applied again directly before time T 45 applied.

[0422] At time T 45Combustion in the engine is stopped and the engine begins to decelerate. Shortly thereafter, the engine speed is reduced to less than the upper NVH engine speed threshold 2402. The pinion gear is advanced in response to the engine speed being less than the upper NVH engine speed threshold and greater than the lower NVH engine speed threshold, but the pinion gear does not fully engage the engine flywheel. The engine throttle is set to a first position 2410 in response to the engine speed and the pinion gear state. The engine speed continues to decrease, and the throttle is set to a third position 2414 when the engine speed is less than the lower NVH engine speed threshold 2404 and greater than the engagement threshold 2406.The third position 2414 is less open than the first position 2410 and the second position 2412. The pinion gear engages the engine flywheel while the engine speed is less than the lower NVH engine speed threshold 2404 and greater than the engagement threshold 2406. Consequently, the throttle is adjusted to a fourth position in response to the pinion gear position and the engine speed. The fourth position 2416 is more open than the third position 2414. The fourth position may provide additional air to the engine so that the engine can be more easily restarted in the event of a driver change of mind. The engine speed reaches zero without a driver change of mind, and the pinion gear remains engaged.

[0423] At time T 46The driver releases the brake, and the engine is restarted via the engaged pinion gear in response to the brake being released. Fuel injection is also reactivated in response to the brake being released and a subsequent request to start the engine.

[0424] In this way, an engine throttle position may be adjusted to improve engine restart while an engine is stopped. Adjusting the engine throttle position in response to engine speed and pinion gear condition during engine stop may help provide the engine with an amount of air that may improve engine start. Additionally, if the pinion gear does not engage prior to engine stop, the adjusted throttle position may improve engine stop by controlling the amount of engine air predictably during engine stop.

[0425] The procedures and systems of Fig. 1-3 and 23-24 provide for stopping the rotation of an engine, comprising: terminating fuel supply to engine cylinders that combust air and fuel; commanding engagement of a starter from a disengaged state to engagement with the engine; and adjusting a position of a throttle based on whether or not the starter is engaged with the engine. In this way, the engine may be better prepared for starting if a driver has a change of mind. The method includes engaging the starter with the engine via a pinion gear. The method according to the invention includes adjusting the throttle to a first position if the starter does not engage the engine within a first engine speed range.According to the invention, the method includes setting the throttle valve to a second position when the starter engages the engine within the first engine speed range, the second position being more open than the first position.

[0426] According to the invention, the method further comprises commanding the starter to engage the engine within a predetermined crankshaft angle window. According to the invention, the method comprises the crankshaft angle window being within ± 40 crankshaft degrees of top dead center of a cylinder stroke. The method comprises decreasing engine speed during the command to engage the starter.

[0427] The procedures and systems of Fig. 1-3 and 23-24 provide for stopping rotation of an engine, comprising: terminating fueling to engine cylinders that combust air and fuel; commanding engagement of a starter that is not engaged with the engine to engage the engine; and adjusting a position of a throttle based on whether or not the starter engages the engine and engine speed. The method includes adjusting the throttle position to a more closed position at engine speeds less than a threshold speed and a more open position at engine speeds greater than the threshold speed. The method includes adjusting the throttle to a first position when the starter does not engage the engine within a first engine speed range.According to the invention, the method includes setting the throttle valve to a second position when the starter engages the engine within the first engine speed range, the second position being more open than the first position. The method includes setting the throttle valve to a third position when the starter does not engage the engine within a second engine speed range. The method includes setting the throttle valve to a fourth position when the starter engages the engine within the second engine speed range, the fourth position being more open than the third position.

[0428] The procedures and systems of Fig. 1-3 and 23-24 provide a vehicle system comprising: an engine having a throttle; a dual mass flywheel (DMF) having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side mechanically coupled to a second side of the dual mass flywheel; a starter having a base state in which the starter is not engaged with the engine; a transmission selectively coupled to the engine via the driveline disconnect clutch; and a controller having non-transitory instructions executable to adjust a position of the throttle during an engine stop based on whether the starter is engaged with the engine, in response to an engine stop request and prior to an engine stop.

[0429] In some examples, the vehicle system includes adjusting the throttle to a first position in response to the starter not engaging the engine. The vehicle system includes adjusting the throttle to a second position in response to the starter engaging the engine, wherein the second position is more open than the first position. The vehicle system further includes additional commands to adjust the throttle position in response to engine speed. According to the invention, the vehicle system further includes additional commands to engage the starter at a predetermined crankshaft position. According to the invention, the vehicle system includes wherein the predetermined crankshaft position is ± 40 crankshaft degrees from top dead center of a cylinder compression stroke.The vehicle system further includes additional commands to stop, at engine speeds below an engagement speed and above zero engine speed, the attempt to engage the starter.

[0430] With reference to Fig. 25 is a flowchart of a method for setting an engine shutdown speed profile and an engine rotation stop position. The method of Fig. 25 can be stored as executable instructions in a non-volatile memory of the control unit 12 in Fig. 1-3 must be saved.

[0431] At 2502, method 2500 judges whether or not an engine spin stop request has occurred. An engine spin stop request may be provided by a controller or a driver. The controller may automatically stop the engine without the driver providing input from a dedicated actuator that has a sole function of stopping and / or starting the engine. For example, an automatic engine stop does not occur when a driver places an ignition switch in an off state. Alternatively, an automatic engine stop may occur when a driver releases an accelerator pedal. If method 2500 judges that an engine stop is requested, the answer is yes and method 2500 proceeds to 2504. Otherwise, the answer is no and method 2500 proceeds to exit.

[0432] At 2504, method 2500 judges whether or not to stop engine rotation with the driveline disconnect clutch slipping. Method 2500 judges, based on operating conditions, whether or not to stop the engine while the driveline disconnect clutch is slipping. In one example, the engine may be stopped without the driveline disconnect clutch slipping if it is desired to stop the engine in a short period of time. For example, it may be desirable to stop the engine quickly if the engine speed is relatively low at the time of the engine stop request. On the other hand, the engine may be stopped while the driveline disconnect clutch is slipping if the engine speed is relatively high at the time of the engine stop request.It should also be noted that engine rotation may be stopped during some conditions with an open driveline disconnect clutch. If method 2500 judges that engine rotation should be stopped with the driveline disconnect clutch slipping, the answer is yes and method 2500 proceeds to 2530. Otherwise, the answer is no and method 2500 proceeds to 2506.

[0433] At 2530, method 2500 determines the desired transmission clutch rail pressure. In one example, the desired transmission clutch rail pressure may be based on an amount of clutch pressure that keeps a vehicle stopped on a road while the engine has stopped rotating. Consequently, the desired transmission clutch rail pressure may increase when the vehicle is stopped on a hill. In one example, the desired transmission clutch rail pressure is empirically determined and stored in a table or function indexed by the road grade and vehicle mass. The table outputs the desired transmission clutch rail pressure in response to the road grade and vehicle mass. Method 2500 proceeds to 2532 after the desired transmission clutch rail pressure is determined.

[0434] At 2532, method 2500 rotates the DISG at a speed that provides the desired transmission clutch oil rail pressure by rotating the transmission oil pump. The DISG is coupled to a torque converter impeller, and the torque converter impeller is fluidly coupled to the torque converter turbine. The transmission oil pump is driven by the torque converter impeller, and the transmission oil pump provides oil pressure to the transmission clutches when rotated. In one example, the desired transmission oil rail pressure indexes a table that includes empirically determined values of DISG speed that provide the desired transmission clutch oil rail pressure. The DISG speed is output from the table, and the DISG speed is controlled to the value output from the table. Method 2500 proceeds to 2534 after the DISG begins rotation at the desired speed.

[0435] At 2534, method 2500 stops fuel flow and spark to the engine cylinders. Fuel flow to the cylinders may be stopped by closing the fuel injectors. Further, fuel flow may be stopped in a sequential order based on the engine combustion order so that the cylinders are not partially fueled when engine rotation is commanded to stop. Method 2500 proceeds to 2536 after fuel flow and spark to the engine cylinders stop.

[0436] At 2536, method 2500 slips the driveline disconnect clutch to achieve a desired engine speed curve. In one example, empirically determined driveline disconnect clutch application or slip curves are stored in memory and applied to the driveline disconnect clutch when engine stop is requested. The slip curve table applies pressure to the driveline disconnect clutch at various rates depending on engine speed when the engine stop request is performed. Alternatively, an empirically determined transfer function that outputs a driveline disconnect clutch application force or pressure based on a desired driveline disconnect clutch pressure is the basis for actuating the driveline disconnect clutch.Additionally, the slip curve may include a timing of when pressure should be applied to the driveline disconnect clutch. For example, pressure may be applied to the driveline disconnect clutch a set number of crankshaft degrees after a final amount of fuel is applied to an engine cylinder prior to engine stop. Consequently, the initial time of driveline disconnect clutch pressure application and the rate at which pressure is applied to the driveline disconnect clutch are stored in memory and applied when an engine stop request is issued. Method 2500 proceeds to 2538 after application of the driveline disconnect clutch pressure profile is initiated.

[0437] At 2538, method 2500 commands transmission clutches to connect the transmission output shaft to the transmission case. The transmission output shaft may be connected to the transmission by simultaneously applying other transmission clutches than the driveline disconnect clutch, as described in U.S. Patent Application No. 12 / 833,788. Method 2500 proceeds to 2540 after the transmission is commanded to a connected state.

[0438] At 2540, method 2500 opens the driveline disconnect clutch. The driveline disconnect clutch may be opened when engine speed is substantially zero (e.g., 100 rpm -1or less) and the engine has stopped in a desired position. Alternatively, the driveline disconnect clutch may be opened when the engine speed drops to a predetermined value. Thus, by varying the actuation of the driveline disconnect clutch, method 2500 may partially or completely control the engine speed curve down to zero engine speed. Method 2500 proceeds to exit after the driveline disconnect clutch is opened.

[0439] At 2506, method 2500 closes the driveline disconnect clutch if the driveline disconnect clutch is not already closed. The driveline disconnect clutch may be closed by increasing a duty cycle signal that increases the driveline disconnect clutch application pressure. Method 2500 proceeds to 2508 after the driveline disconnect clutch is closed.

[0440] At 2508, method 2500 stops fuel flow and spark to the engine cylinders. Fuel flow and spark may be stopped as described at 2534. Method 2500 proceeds to 2510 after fuel and spark supply to the engine cylinders are stopped.

[0441] At 2510, method 2500 adjusts the DISG speed and DISG torque to create a desired engine speed profile during stopping engine rotation. In one example, an empirically determined set of engine speed curves is stored in memory and used as a basis for stopping the engine. For example, if the engine speed is greater than that of the engine speed curve retrieved from memory, DISG torque absorption is increased to steer the engine speed toward the desired engine speed profile. If the engine speed is less than that of the engine speed curve retrieved from memory, DISG torque is increased to steer the engine speed toward the desired engine speed profile.The engine speed curve table decelerates the engine speed at various rates depending on the engine speed when the engine stop request is made. Additionally, the engine speed curve may include the timing to which the engine speed curve is to be controlled via the DISG. For example, the engine speed curve may be controlled by the DISG for a set number of crankshaft degrees after a final amount of fuel is delivered to an engine cylinder prior to the engine stop. Consequently, the initial application time of the engine speed profile and the rate of engine speed reduction are stored in memory and controlled by the DISG when an engine stop request is issued. Method 2500 proceeds to 2512 after application of the driveline disconnect clutch pressure profile is initiated.

[0442] At 2512, method 2500 commands transmission clutches to firmly connect the transmission output shaft to the transmission case. The transmission output shaft may be connected to the transmission by simultaneously applying other transmission clutches than the driveline disconnect clutch at the same time, as described in U.S. Patent Application No. 12 / 833,788, which is incorporated herein by reference in its entirety. Method 2500 proceeds to 2514 after the transmission is commanded to a firmly connected state.

[0443] At 2514, method 2500 opens the driveline disconnect clutch at a predetermined engine speed. The driveline disconnect clutch is opened so that the engine can coast to zero speed while the DISG continues to rotate and provide pressure to transmission clutches while the engine is stopped. In one example, the driveline disconnect clutch is opened at a predetermined engine speed based on the engine speed at which the engine stop was initiated (e.g., the engine speed at which fuel flow to the engine cylinders is stopped) and the rate of engine speed decay. Further, the driveline disconnect clutch may be opened at a specific crankshaft angle to further control the engine stop position.A table or function indexed by the rate of engine speed decay and the engine speed at which the engine stop was requested outputs the engine position at which the driveline disconnect clutch is opened. In one example, the position corresponds to an engine position that enhances the possibility of stopping at the desired engine position (e.g., during a predetermined crankshaft interval of a cylinder in a compression stroke). Method 2500 proceeds to 2516 after the driveline disconnect clutch is opened.

[0444] At 2516, method 2500 determines a desired transmission clutch line pressure. The desired transmission clutch line pressure is determined as described at 2530. Method 2500 proceeds to 2518 after the desired transmission clutch oil line pressure is determined.

[0445] At 2518, method 2500 rotates the DISG to maintain the desired transmission clutch rail pressure. The DISG may be rotated as described at 2532. Method 2500 proceeds to end after the DISG is commanded to deliver the desired transmission clutch rail pressure. It should be noted that the DISG may be periodically stopped and restarted to maintain the transmission clutch rail pressure. If the transmission clutch rail pressure has a slow leak rate, the DISG may be commanded to turn off. The DISG may be reactivated when the transmission clutch rail pressure drops to a threshold level.

[0446] In this way, the engine stop position for a hybrid vehicle can be controlled. The driveline disconnect clutch can adjust an engine stop profile from idle speed to zero speed by periodically delivering torque from the DISG to the engine so that the engine stops in a desired position.

[0447] With reference to Fig. 26 is an example sequence for stopping a prime mover according to the method of Fig. 25. The sequence of Fig. 26 can be achieved through the system of Fig. 1-3 are provided.

[0448] The first diagram from the top in Fig. Figure 26 represents engine speed as a function of time. The Y-axis represents engine speed, and engine speed increases in the Y-axis direction. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0449] The second diagram from the top in Fig. Figure 26 represents DISC speed as a function of time. The Y-axis represents DISC speed, and DISC speed increases in the direction of the Y-axis. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0450] The third diagram from the top in Fig. Figure 26 plots the driveline disconnect clutch application force (e.g., the force applied to close the driveline disconnect clutch) as a function of time. The Y-axis represents the driveline disconnect clutch application force, and the driveline disconnect clutch application force increases in the Y-axis direction. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0451] The fourth diagram from the top in Fig. Figure 26 shows the fuel supply state as a function of time. The Y-axis represents the fuel supply state, and fuel is supplied to the engine when the curve is at a higher level. Fuel is not supplied to the engine when the curve is at a lower level. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0452] The fifth diagram from the top in Fig. Figure 26 shows the gear connection state as a function of time. The Y-axis represents the gear connection state, and the gear is firmly connected when the curve is at a higher level. The gear is not firmly connected when the curve is at a lower level. The X-axis represents time, and time increases from the left side of the figure to the right side of the figure.

[0453] At time T 47the engine speed and the DISG speed are equal and at an elevated level. The engine is mechanically coupled to the DISG via the driveline disconnect clutch. The driveline disconnect clutch is fully closed when the driveline disconnect clutch input speed is equal to the driveline disconnect clutch output speed. Furthermore, the driveline disconnect clutch is fully closed when the driveline disconnect force is at a higher level. Fuel is being supplied to the engine, as indicated by the fueling state being at a higher level. The transmission is not locked connected because the transmission connection state is at a lower level.

[0454] At time T 48The engine is commanded to an off state in response to operating conditions (e.g., a low engine torque request and applied vehicle braking). Fueling to the engine is stopped, as indicated by the fueling state transitioning to a lower level. Additionally, the DISG speed / torque is adjusted to control the engine speed and position curve in response to the engine stop request. In one example, the engine speed / position curve is stored in memory, and the DISG torque is adjusted in response to a difference between the actual engine speed and the desired engine speed curve stored in memory.For example, if at a particular time after the engine stop request, the actual engine speed is less than the desired engine speed, DISG torque is increased to move the actual engine speed toward the desired engine speed. In another example, if a particular engine position (e.g., top dead center of the number one cylinder compression stroke) is ahead of where it is desired at a particular time after the engine stop request, negative DISG torque may be increased to decelerate the engine at a greater rate.

[0455] At time T 49The driveline disconnect clutch is opened in response to the engine reaching a predetermined speed. Further, clutches of the transmission begin to be applied such that the transmission output shaft is fixedly connected to the transmission housing and the vehicle chassis. By opening the driveline disconnect clutch at a predetermined speed, it may be possible to better control engine speed during engine stop while allowing the DISG to operate. In this example, the DISG is stopped, but in other examples, it may continue to rotate to provide motive power to operate the transmission oil pump. The engine and DISG are stopped shortly after the disconnect clutch is opened.

[0456] In this way, an engine can be stopped in such a way that the engine position can be controlled during stopping. By controlling the engine stop position, it may be possible to improve engine restart performance consistency.

[0457] At time T 50The DISG accelerates and delivers torque to the vehicle driveline in response to a driver releasing a brake pedal (not shown). The DISG also assists in engine starting. Specifically, the driveline disconnect clutch is partially closed to transfer torque from the DISG to the engine. Fuel and spark are delivered to the engine to support combustion in the engine, as indicated by the fueling state transitioning to a higher level. Finally, the transmission clutches are also opened in response to brake release to release the transmission. The driveline disconnect clutch is fully closed when the engine speed reaches the DISG speed.

[0458] In this manner, the engine can be restarted while torque is delivered to the vehicle driveline to accelerate the vehicle. Furthermore, the driveline disconnect clutch is actuated in a manner that can reduce driveline torque disturbances.

[0459] Between time T 50 and the time T 51 The engine and DISG deliver torque to the vehicle driveline based on driver demand. In this example, the driveline disconnect clutch remains closed; however, it may occasionally open without stopping the engine.

[0460] At time T 51The engine is commanded to an off state in response to operating conditions (e.g., a low engine torque request and applied vehicle braking). Fueling to the engine is stopped, as indicated by the fueling state transitioning to a lower level. The driveline disconnect clutch is also commanded to slip via decreasing the driveline disconnect clutch application force. In one example, the driveline disconnect clutch slip rate is stored in memory as a function of time since the engine stop request. The slip rate may be increased or decreased as engine speed deviates from a desired engine speed.For example, if at a particular time after the engine stop request, the engine speed is less than a desired engine speed, driveline disconnect clutch slip may be reduced by increasing the driveline disconnect clutch application force. In this way, additional torque may be delivered to the engine by the DISG, adjusting the engine speed to the desired engine speed. The DISG speed is commanded to a speed that allows the transmission oil pump to provide a desired oil pressure.

[0461] At time T 52 When the engine speed reaches a predetermined speed, the transmission clutches are applied to secure the transmission output shaft to the vehicle chassis. The DISG continues to rotate, delivering oil pressure to the transmission clutches.

[0462] In this way, a driveline disconnect clutch may slip during an engine stop procedure to provide a desired engine stop position. In some examples, the desired engine stop position is where a particular cylinder piston stops within a predetermined number of degrees before top dead center of the cylinder's compression stroke.

[0463] The procedures and systems of Fig. 1-3 and 25-26 provide an engine stopping method comprising: setting a speed of a driveline integrated starter / generator (DISG) to a desired speed that provides a desired transmission clutch oil rail pressure in response to a request to stop engine rotation; and slipping a driveline disconnect clutch in a driveline between the DISG and the engine to stop the engine in a desired position. The method includes where the desired position is a predetermined number of crankshaft degrees before top dead center of the compression stroke of a selected cylinder. The method further includes terminating fuel flow and spark to the engine cylinders in response to the request to stop engine rotation.The method further includes securing a transmission output shaft to a transmission housing in response to the request to stop engine rotation.

[0464] In some examples, the method further comprises opening the driveline disconnect clutch at an engine speed of substantially zero. The method also further comprises continuing to rotate the DISG while the engine speed is at zero. The method further comprises enabling and disabling the DISG while the engine speed is zero.

[0465] The procedures and systems of Fig. 1-3 and 25-26 also provide an engine stop method comprising: closing a driveline disconnect clutch in response to a request to stop engine rotation; setting a speed of a driveline integrated starter / generator (DISG) to a desired engine speed profile that decelerates toward zero engine speed; and opening the driveline disconnect clutch at a predetermined engine speed. The method further includes securing a transmission output shaft to a transmission housing in response to a request to stop the engine. The method further includes terminating fuel flow and spark to the engine cylinders in response to the request to stop the engine. The method includes where the driveline disconnect clutch is disposed in a driveline between an engine and the DISG.

[0466] In some examples, the method further comprises opening the driveline disconnect clutch in a predetermined position. The method includes increasing the speed of the DISG when the engine speed is less than the desired engine speed profile. The method includes decreasing the speed of the DISG when the engine speed is greater than the desired engine speed profile.

[0467] The procedures and systems of Fig. 1-3 and 25-26 provide a vehicle system comprising: an engine; a dual mass flywheel (DMF) having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side mechanically coupled to a second side of the dual mass flywheel; a driveline integrated starter / generator (DISG) having a first side coupled to a second side of the driveline disconnect clutch; a transmission selectively coupled to the engine via the driveline disconnect clutch; and a controller having executable instructions stored in non-volatile memory to adjust actuation of the driveline disconnect clutch in response to a request to stop engine rotation.

[0468] In some examples, the vehicle system includes at least partially closing the driveline disconnect clutch. The vehicle system includes fully closing the driveline disconnect clutch. The vehicle system further includes additional instructions to open the driveline disconnect clutch at a predetermined engine speed. The vehicle system further includes operating the DISG at a speed that provides a desired transmission clutch oil rail pressure. The vehicle system further includes additional instructions to selectively deactivate the DISG at zero engine speed.

[0469] With reference to Fig. 27 shows a method for stopping a prime mover when a vehicle in which the prime mover is operating is parked on variable slopes. The method of Fig. 27 can be stored as executable instructions in the non-volatile memory of the control unit 12 in Fig. 1-3 must be saved.

[0470] At 2702, method 2700 judges whether or not a vehicle in which an engine is operating is stopped. In one example, the vehicle may be determined to be stopped if the vehicle speed is zero. If method 2700 judges that the vehicle is stopped, the answer is yes, and method 2700 proceeds to 2704. Otherwise, the answer is no, and method 2700 proceeds to exit.

[0471] At 2704, method 2700 judges whether or not engine stop conditions are met. In one example, the engine stop conditions may include, but are not limited to, a driver demand torque being less than a threshold torque, engine speed being less than a threshold speed, and vehicle braking being applied. In other examples, other engine stop conditions may be applied. If engine stop conditions exist, the answer is yes, and method 2700 proceeds to 2706. Otherwise, the answer is no, and method 2700 proceeds to exit.

[0472] At 2706, method 2700 estimates the road grade and the vehicle mass. In one example, the road grade may be determined via an inclinometer. The vehicle mass may be determined as at 904 by Fig. 9. Additionally, method 2700 stops engine rotation. Method 2700 proceeds to 2708 after the vehicle mass and road grade are determined.

[0473] At 2708, method 2700 judges whether or not the road grade is greater than a first threshold road grade. In one example, the first threshold and other threshold road grades may be a function of vehicle mass. For example, as vehicle mass increases, the first threshold road grade may decrease. If method 2700 judges that the current road grade is greater than a first threshold road grade, the answer is yes and method 2700 proceeds to 2716. Otherwise, the answer is no and method 2700 proceeds to 2710.

[0474] At 2710, method 2700 maintains transmission oil pressure to enable the transmission gear shift and shifts from a lower gear (e.g., first gear) to a higher gear (e.g., second gear) if the transmission is not already in second gear. Shifting to a higher gear effectively increases vehicle mass at the vehicle wheels, making it more difficult to move the vehicle. Transmission oil pressure may be maintained via an electric oil pump. Method 2700 proceeds to 2712 after the transmission is shifted.

[0475] At 2712, method 2700 judges whether or not vehicle acceleration or an increased torque request is requested. In one example, an increased driver request is determined by an accelerator pedal position. If method 2700 judges that vehicle acceleration or an increased torque request is requested, the answer is yes and method 2700 proceeds to 2714. Otherwise, method 2700 returns to 2710.

[0476] At 2714, method 2700 increases the torque delivered to the driveline and downshifts the transmission to a lower gear (e.g., first gear) to accelerate the vehicle. Driveline torque may be increased via the DISG or via the engine after the engine is started. The engine may be started via cranking by the DISG or a starter with lower power output capacity. Method 2700 proceeds to end after the transmission is shifted to first gear and driveline torque is increased.

[0477] At 2716, method 2700 judges whether or not the road grade is greater than a second threshold road grade. If method 2700 judges that the current road grade is greater than a second threshold road grade, the answer is yes and method 2700 proceeds to 2724. Otherwise, the answer is no and method 2700 proceeds to 2718.

[0478] At 2718, method 2700 maintains transmission oil pressure to enable transmission gear shifts and shifts to a gear higher than second gear (e.g., third gear) if the transmission is not already in a higher gear. Shifting to a gear higher than second gear effectively increases vehicle mass at the vehicle wheels, making it more difficult to move the vehicle. Transmission oil pressure may be maintained via an electric oil pump. Method 2700 proceeds to 2718 after the transmission downshifts.

[0479] At 2720, method 2700 judges whether or not vehicle acceleration or an increased torque request is requested. In one example, an increased driver request is determined by an accelerator pedal position. If method 2700 judges that vehicle acceleration or an increased torque request is requested, the answer is yes and method 2700 proceeds to 2722. Otherwise, method 2700 returns to 2718.

[0480] At 2722, method 2700 increases the torque delivered to the driveline and downshifts the transmission to first gear to accelerate the vehicle. Driveline torque may be increased via the DISG or via the engine after the engine is started. The engine may be started via cranking by the DISG or a starter with a lower power output capacity. Method 2700 proceeds to end after the transmission is shifted to first gear and the amount of torque delivered to the driveline is increased.

[0481] At 2724, method 2700 applies the vehicle brakes, maintains transmission oil pressure to enable the transmission gear shift, and shifts into first if not already in first gear. By shifting into first gear and applying the brakes, the vehicle may be ready to accelerate while stopped on a grade. Further, by not applying the brakes on lesser grades, brake wear may be reduced while reducing vehicle motion. Transmission oil pressure may be maintained via an electric oil pump. Method 2700 proceeds to 2726 after the vehicle brakes are applied.

[0482] At 2726, method 2700 judges whether or not vehicle acceleration or increased torque request is requested. If method 2700 judges that vehicle acceleration or increased torque request is requested, the answer is yes and method 2700 proceeds to 2728. Otherwise, method 2700 returns to 2724.

[0483] At 2728, method 2700 increases the torque delivered to the driveline and releases the vehicle brakes so that the vehicle can accelerate. Driveline torque may be increased via the DISG or via the engine after the engine is started. The engine may be started via cranking by the DISG or a starter with a lower power output capacity. Method 2700 proceeds to exit after the vehicle brakes are released.

[0484] As described herein, an engine shutdown or engine stop operation, such as when a vehicle is stopped, may be used to conserve fuel. During such an operation, the driveline disconnect clutch may be opened. Therefore, when the vehicle is at rest, perhaps on an uphill grade, the engine is often shut down to rest. An alternative pressure source other than the engine may thus be used to maintain transmission hydraulic pressure while the engine is off. In some examples, an electric auxiliary pump may be used to maintain transmission hydraulic pressure. In other examples, the DISG speed does not drop to zero when the vehicle is stopped, but is maintained at a low speed, typically well below idle (e.g., 200-500 rpm). -1) to maintain transmission hydraulic pressure. Under these conditions, the torque converter output torque is either zero (because the input speed is zero) or a value that may be insufficient to prevent the vehicle from rolling backward when the brake is released. One method applies the wheel brakes to prevent the vehicle from rolling backward; although effective in some cases, this may also result in degraded vehicle launch performance or require a tilt sensor.

[0485] Another issue may be that when the driver depresses the brake pedal, the vehicle brakes and / or regenerative braking may be applied based on operating conditions. For example, the braking torque generated by the DISG during regenerative braking (with or without engine shutdown and driveline disconnect clutch open) may be balanced with friction wheel braking torque to create a desired deceleration rate corresponding to brake pedal pressure. Because regenerative braking torque decreases when the vehicle comes to a stop to perform a rollback control function, a larger portion of the friction braking torque must be "reversed," thus reducing the benefit of regenerative braking. Consequently, alternative rollback control methods may be desirable to enhance the ability to utilize regenerative braking.

[0486] In one example, the torque converter-based automatic transmission may be equipped with a one-way clutch. In this manner, if transmission fluid pressure is maintained while the vehicle is stationary and if the transmission is held in gear (as opposed to, for example, neutral), then the one-way clutch acts as a mechanical rollback prevention device to prevent the vehicle from rolling backward when the vehicle is on an uphill grade. However, depending on the vehicle mass and the grade angle, holding the transmission in a lower gear, such as first gear, may only slow vehicle rollback when the brake is released on a steeper grade, such as a 6% grade. In this example, with the transmission in first gear, the torque, which is a function of the sine of the grade angle and the vehicle m...

Claims

[1] A method for stopping the rotation of a prime mover, comprising: Stopping fuel supply to engine cylinders that burn air and fuel; Commanding engagement of a starter from a non-engine-engaged state to an engine-engaged state; and Adjusting a position of a throttle valve based on whether or not the starter is engaged with the engine; wherein - the throttle valve is set to a first position when the starter does not engage the engine within a first engine speed range, wherein the throttle valve is set to a second position when the starter engages the engine within the first engine speed range, the second position being more open than the first position; and / or - the starter is commanded to engage the engine within a predetermined crankshaft angle window, the crankshaft angle window being within ± 40 crankshaft degrees of a top dead center of a cylinder stroke. [2] The method of claim 1, wherein the starter engages the engine via a pinion gear. [3] The method of claim 1, wherein the engine speed decreases during the starter engagement command. [4] A method for stopping the rotation of a prime mover, comprising: Stopping fuel supply to engine cylinders that burn air and fuel; Commanding the engagement of a starter that is not engaged with the engine to engage the engine; and Adjusting a position of a throttle valve based on whether or not the starter is engaged with the engine and the engine speed; wherein the throttle valve is adjusted to a first position when the starter is not engaging the engine within a first engine speed range, wherein the throttle valve is adjusted to a second position when the starter is engaging the engine within the first engine speed range, the second position being more open than the first position. [5] The method of claim 4, wherein the throttle position is adjusted to a more closed position at engine speeds less than a threshold speed and a more open position at engine speeds greater than the threshold speed. [6] The method of claim 4, wherein the throttle is set to a third position when the starter does not engage the engine within a second engine speed range. [7] The method of claim 6, wherein the throttle is set to a fourth position when the starter engages the engine within the second engine speed range, the fourth position being more open than the third position. [8] Vehicle system comprising: an engine with a throttle valve; a dual mass flywheel (DMF) having a first side mechanically coupled to the engine; a driveline disconnect clutch having a first side mechanically coupled to a second side of the dual-mass flywheel; a starter having a base state in which the starter is not engaged with the engine; a transmission selectively coupled to the engine via the driveline disconnect clutch; and a control unit having non-volatile instructions executable to determine a position of the throttle valve during an engine stop based on whether or not the starter is engaged with the engine in response to an engine stop request and prior to an engine stop; wherein - the throttle valve is set to a first position in response to the starter not engaging the engine, wherein the throttle valve is set to a second position in response to the starter engaging the engine, wherein the second position is more open than the first position; and / or - further comprising additional commands to engage the starter at a predetermined crankshaft position, wherein the predetermined crankshaft location is ± 40 crankshaft degrees from top dead center of a cylinder compression stroke. [9] The vehicle system of claim 8, further comprising additional commands for adjusting throttle position in response to engine speed. [10] The vehicle system of claim 8, further comprising additional commands to stop attempting to engage the starter at engine speeds below an engagement speed and above zero engine speed.

Images