Method and system for downshifting during recuperation

Abstract

Powertrain operating procedures for a hybrid vehicle, including: Receiving operating conditions by a controller via sensors connected to the controller; Setting a torque applied to the transmission input shaft via a closed-loop control system in response to a percentage of transmission gear shift completions based on operating conditions; and Applying torque to a transmission via a torque source, wherein the torque source is connected to the control system, wherein the percentage of transmission gear shift completion is based on the transmission output shaft speed in a new gear and the transmission output shaft speed in a current gear; and wherein the percentage of transmission gear shift completion is further based on dividing the current transmission output shaft speed by the transmission output shaft speed in the new gear minus the transmission output shaft speed in the current gear.

Description

Area

[0001] The present description relates to methods and a system for downshifting gears of a hybrid vehicle including a fixed-ratio transmission. The methods and systems may be particularly useful for hybrid vehicles that are occasionally operated in a regenerative braking mode. Background and summary

[0002] A hybrid vehicle, such as those disclosed in DE 10 2014 204 119 A1, DE 10 2013 207 828 A1, and DE 10 2011 111 135 A1, may enter a recuperation mode from time to time. In recuperation mode, the vehicle's kinetic energy may be converted into electrical energy and stored for use at a later time. The vehicle may enter recuperation mode when a driver reduces the requested torque to decelerate the vehicle or reduce the vehicle's tendency to accelerate. For example, a vehicle may enter a recuperation mode in response to the vehicle approaching a stop sign and the driver releasing the accelerator pedal. The vehicle may decelerate to a predetermined extent after entering recuperation mode.During vehicle deceleration, its transmission may downshift from a higher gear to a lower gear while vehicle speed decreases to maintain engine and / or motor speed within a desired range. However, if the transmission clutches fail to transmit a desired amount of torque during the downshift, the driver may experience undesirable driveline torque disturbance. Further, driveline torque disturbance may be amplified in powertrains that include a driveline disconnect clutch, thereby increasing driveline inertia. Therefore, it may be desirable to provide a system and method for a transmission downshift that enhances downshifting in a regenerative mode.

[0003] The present inventors have recognized the above-mentioned problems and have developed a powertrain operating method comprising adjusting a torque applied to a transmission input shaft via a closed-loop control system in response to a percentage of a transmission gear shift completed. Specifically, the present invention provides a powertrain operating method according to claim 1. Furthermore, the present invention provides a powertrain operating method according to claim 6. Furthermore, the present invention provides a system according to claim 14. Advantageous embodiments of the invention are set forth in the dependent claims.

[0004] By adjusting motor torque in response to a percentage of a completed transmission gear shift, it may be possible to provide the technical result of reducing driveline torque disturbances during gear shifts of a fixed-ratio transmission. In particular, the pressure over stroke required to depress a clutch is directly related to the torque transmitted through a gear clutch. However, a gear clutch actuator may not have sufficient bandwidth to shape clutch slip during a downshift to reduce driveline torque disturbances. On the other hand, an electric machine operating in regenerative mode may have a higher torque bandwidth that can be used to influence the torque transmitted through the gear clutch during gear shifts by adjusting the torque of the electric machine.Thus, by adjusting the torque of the electric machine, driveline torque disturbances can be reduced when a driveline is operating in regenerative braking mode.

[0005] The present description may offer several advantages. In particular, the approach may reduce driveline torque disturbances during transmission downshifts. Furthermore, the approach may incorporate closed-loop control to further reduce driveline torque disturbances. Furthermore, the approach may incorporate adjusting control parameters so that open-loop torque control can be enhanced.

[0006] The above advantages and other advantages and features of the present description will be readily apparent from the following detailed description, considered alone or in conjunction with the accompanying drawings.

[0007] It should be understood that 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 reveal critical or essential features of the claimed subject matter, the scope of which is defined solely by the claims following the Detailed Description. Furthermore, the claimed subject matter is not limited to implementations that resolve any disadvantages identified above or in any part of this disclosure. Short description of the drawings

[0008] The advantages described herein will be better 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 a schematic diagram of a power machine; Fig. 2 a schematic diagram of a hybrid vehicle powertrain; Fig. 3 is a diagram of a simulated exemplary transmission downshift; and Fig. 4 a method for operating a hybrid vehicle powertrain. Detailed description

[0009] This description relates to the control of downshifting of a fixed-ratio hybrid vehicle transmission. The hybrid vehicle may have a prime mover (internal combustion engine) as shown in Fig. 1. The power machine of Fig. 1 may be used in a drive train or power train as shown in Fig. 2. The transmission can downshift and its control parameters can be adjusted as shown in the Fig. 3 shown exemplary sequence. Fig. 4 shows a method for switching the Fig. 2 shown gearbox.

[0010] On Fig. 1, the internal combustion engine 10, which comprises a plurality of cylinders, one of which is in Fig. 1, is controlled by the electronic engine control 12. The engine 10 consists of the cylinder head 35 and block 33, which contain the combustion chamber 30 and the cylinder walls 32. The piston 36 is positioned therein and reciprocates via a connection to the crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. A starter 96 (e.g., a low-voltage electrical machine (operating at less than 30 volts)) includes a pinion shaft 98 and a pinion gear 95. The pinion shaft 98 can selectively advance the pinion gear 95 to engage the ring gear 99. The starter 96 can be directly attached to the front end of the engine or the rear end of the engine. In some examples, the starter 96 can selectively supply torque to the crankshaft 40 via a belt or chain.In one example, the starter 96 is in a ground state when it is not engaged with the engine crankshaft. The combustion chamber 30 is shown communicating with the intake manifold 44 and the exhaust manifold 48 via the intake valve 52 and the exhaust valve 54, respectively. Each intake and exhaust valve may be actuated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 may be determined by the intake cam sensor 55. The position of the exhaust cam 53 may be determined by the exhaust cam sensor 57. The intake valve 52 may be selectively activated and deactivated by the valve activation device 59. The exhaust valve 54 may be selectively activated and deactivated by the valve activation device 58. The valve activation devices 58 and 59 may be electromechanical devices.

[0011] In the illustration, fuel injector 66 is positioned to inject fuel directly into cylinder 30, known to those skilled in the art as direct fuel injection. Fuel injector 66 delivers liquid fuel in proportion to the pulse width from controller 12. Fuel is delivered to fuel injector 66 by a fuel system (not shown) that includes a fuel tank, a fuel pump, and a fuel rail (not shown). In one example, a two-stage high-pressure fuel system may be used to produce higher fuel pressures.

[0012] Additionally, intake manifold 44 is shown communicating with turbocharger compressor 162 and engine air intake 42. In other examples, compressor 162 may be a supercharger compressor. Shaft 161 mechanically couples turbocharger turbine 164 to turbocharger compressor 162. Optional electronic throttle 62 adjusts a position of throttle plate 64 to control airflow from compressor 162 to intake manifold 44. Pressure in boost chamber 45 may be referred to as throttle inlet pressure because the inlet of throttle plate 62 is located within boost chamber 45. The throttle outlet is located in the intake manifold 44. In some examples, the throttle valve 62 and the throttle plate 64 may be positioned between the intake valve 52 and the intake manifold 44 such that the throttle valve 62 is a port throttle valve.A compressor recirculation valve 47 can be selectively adjusted to a plurality of positions between fully open and fully closed. The wastegate 163 can be adjusted via the controller 12 to allow exhaust gases to selectively bypass the turbine wheel 164 to control the speed of the compressor 162. An air cleaner 43 cleans air entering the engine air intake 42.

[0013] A distributorless ignition system 88 provides an ignition spark to the combustion chamber 30 via a spark plug 92 in response to the controller 12. A wideband universal exhaust gas oxygen (UEGO) sensor 126 is shown coupled to the exhaust manifold 48 upstream of a catalyst 70. Alternatively, a dual-state oxygen sensor may be substituted for the UEGO sensor 126.

[0014] In one example, the catalyst 70 may include multiple catalyst bricks. In another example, multiple emission control devices, each with multiple bricks, may be used. In one example, the catalyst 70 may be a three-way catalyst.

[0015] The control 12 is in Fig. 1 as a conventional microcomputer including a microprocessor unit 102, input / output (I / O) ports 104, a read-only memory (ROM) 106, a random access memory (RAM) 108, a retained memory (RAM) 110, and a conventional data bus.The controller 12 is shown receiving, in addition to the signals previously discussed, various signals from sensors coupled to the engine 10, including: engine coolant temperature (ECT) from a temperature sensor 112 coupled to the cooling sleeve 114; a position sensor 134 coupled to the accelerator pedal 130 for sensing a force applied by the foot 132; a position sensor 154 coupled to the brake pedal 150 for sensing a force applied by the foot 152; an intake manifold pressure (MAP) measurement from a pressure sensor 122 coupled to the intake manifold 44; engine position from a Hall sensor 118 that senses the position of the crankshaft 40; a measurement of the mass of air entering the engine from a sensor 120; and a measurement of throttle position from a sensor 68. Barometric pressure may also be sensed for processing by controller 12 (sensor not shown).In a preferred aspect of the present description, the engine position sensor 118 generates a predetermined number of evenly spaced pulses during each revolution of the crankshaft from which the engine speed (RPM) can be determined.

[0016] During operation, each cylinder within the internal combustion engine 10 typically experiences a four-stroke cycle: the cycle includes the intake stroke, the compression stroke, the power 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 (for example, 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).

[0017] 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 in the combustion chamber 30. The point at which the piston 36 is at the end of its stroke and closest to the cylinder head (for example, 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 known ignition means, such as the spark plug 92, resulting in combustion.

[0018] During the power stroke, the expanding gases push the piston 36 back to BDC. The crankshaft 40 converts piston motion into rotating shaft torque. Finally, during the exhaust stroke, the exhaust valve 54 opens to deliver 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 only as an example, and that the timing of intake and exhaust valve opening and / or closing may vary to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0019] Fig. 2 is a block diagram of a vehicle 225 including a powertrain 200. The powertrain of Fig. 2 contains the Fig. 1. The drive train 200 can be driven by the engine 10. The engine 10 can be connected to a Fig. 1 or by means of a driveline integrated starter / generator (DISG) 240. The DISG 240 (e.g., a high-voltage electrical machine (operating at over 30 volts)) may also be referred to as an electric machine, electric motor, and / or electric generator. Furthermore, the torque of the engine 10 may be adjusted via the torque actuator 204, such as a fuel injector, throttle body, etc.

[0020] Engine output torque may be transmitted through a dual-mass flywheel 215 to an input side of a driveline disconnect clutch 236. The disconnect clutch 236 may be electrically or hydraulically actuated. The downstream side of the disconnect clutch 236 is shown mechanically coupled to the DISG input shaft 237.

[0021] The DISG 240 can be operated to supply torque to the driveline 200 or to convert driveline torque into electrical energy to be stored in the electrical energy storage device 275. The DISG 240 has a higher output torque capacity than the Fig. 1. Further, the DISG 240 directly drives or is directly driven by the driveline 200. There are no belts, gears, or chains coupling the DISG 240 to the driveline 200. Instead, the DISG 240 rotates at the same speed as the driveline 200. The electrical energy storage device 275 (e.g., a high-voltage battery or power source) may be a battery, capacitor, or inductor. The downstream side of the DISG 240 is mechanically coupled to the impeller 285 of the torque converter 206 via shaft 241. The upstream side of the DISG 240 is mechanically coupled to the disconnect clutch 236.

[0022] The torque converter 206 includes a turbine 286 for delivering torque to the input shaft 270. The input shaft 270 mechanically couples the torque converter 206 to the automatic transmission 208. The torque converter 206 also includes a torque converter bypass lock-up clutch (TCC) 212. Torque is transferred from the impeller 285 directly to the turbine 286 when the TCC is locked. The TCC is electrically operated 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.

[0023] When the torque converter clutch 212 is fully disengaged, the torque converter 206 transfers engine torque to the automatic transmission 208 via fluid communication between the torque converter turbine 286 and the torque converter impeller 285, enabling torque amplification. Conversely, when the torque converter clutch 212 is fully engaged, the engine output torque is transferred directly via the torque converter clutch to an input shaft (not shown) of the transmission 208. Alternatively, the torque converter clutch 212 may be partially engaged, allowing the amount of torque sent directly to the transmission to be adjusted.The controller 12 may be configured to adjust the amount of torque transmitted by the torque converter 212 by adjusting the torque converter lock-up clutch in response to various engine operating conditions or based on a driver-based request for engine operation.

[0024] The automatic transmission 208 includes gear clutches (e.g., gears 1-6) 211 and the forward clutch 210. The gear clutches 211 (e.g., 1-10) 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. In particular, the automatic transmission 208 can transmit input drive torque at the input shaft 270 in response to a driving condition of the vehicle before transmitting output drive torque to the wheels 216.

[0025] Furthermore, a frictional force may be applied to the wheels 216 by engaging the wheel brakes 218. In one example, the wheel 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 coupled to the controller 12 may actuate the engagement of the wheel brakes. In the same way, a frictional force may be reduced to the wheels 216 by disengaging the wheel brakes 218 in response to the driver removing their foot from a brake pedal. Furthermore, the vehicle brakes may apply a frictional force to the wheels 216 via the controller 12 as part of an automated engine stop procedure.

[0026] The controller 12 may be configured to receive inputs from the engine 10, as shown in Fig. 1, and accordingly control engine torque output and / or operation of the torque converter, transmission, DISG, clutches, and / or brakes. As one example, engine torque output may be controlled by adjusting a combination of spark timing, fuel pulse width, fuel pulse control, and / or air charge, by controlling throttle opening and / or valve timing, valve lift, and boost for turbocharged or mechanically boosted engines. For a diesel engine, controller 12 may control engine torque output by controlling a combination of fuel pulse width, fuel pulse control, and air charge. In any case, engine control may be performed on a cylinder-selective basis to control engine torque output.Controller 12 may also control the torque output and electrical power generation from the DISG by adjusting current flowing to and from the field and / or armature windings of the DISG, as is known in the art. Controller 12 receives the transmission input shaft position via position sensor 271. Controller 12 may convert the transmission input shaft position into input shaft speed by differentiating a signal from position sensor 271. Controller 12 may receive transmission output shaft torque from torque sensor 272. Alternatively, sensor 272 may be a position sensor or a torque and position sensor. If sensor 272 is a position sensor, controller 12 differentiates a position signal to determine transmission output shaft speed. Controller 12 may also differentiate the transmission output shaft speed to determine transmission output shaft acceleration.

[0027] When idle-stop conditions are met, the controller 12 may initiate an engine shutdown by shutting off fuel and spark to the engine. However, in some examples, the engine may continue to rotate. To maintain a degree of torsion in the transmission, the controller 12 may further anchor rotating elements of the transmission 208 to a housing 259 of the transmission and thereby to the frame of the vehicle. When engine restart conditions are met and / or a vehicle operator desires to launch the vehicle, the controller 12 may reactivate the engine 10 by tow-starting the engine 10 and resuming cylinder combustion.

[0028] The system of Fig. 1 and Fig. 2 provides a system comprising: an engine (internal combustion engine); an electric machine; a disconnect clutch positioned in a driveline between the engine and the electric machine; a torque converter including a lock-up clutch coupled to the motor; and a controller including executable instructions stored in non-volatile memory for adjusting a torque command to an electric machine during a regenerative mode in response to a closed-loop shift completion percentage error. The system includes where the closed-loop shift completion percentage error is based on a difference between a desired shift completion percentage and an actual shift completion percentage.The system further includes additional instructions for determining an adjustment term based on the percentage of shift completion error in the closed-loop control system. The system includes that the adjustment term is based on an output of a proportional-integral-derivative controller. The system includes that the adjustment torque applied to the transmission is during a transmission gear downshift in a regenerative mode.

[0029] Now on Fig. 3, a diagram of a simulated exemplary transmission downshift is shown. The hybrid system of the Fig. 1 and Fig. 2 operates in a recuperation mode, where the vehicle's kinetic energy is converted into electrical energy via an electric motor. The sequence of Fig. 3 can be accessed via the system of Fig. 1 and Fig. 2, which, according to the procedure of Fig. 4 works, are provided.

[0030] The first diagram from the top in Fig. Figure 3 is a graph of transmission input shaft speed as a function of time. The vertical axis represents the transmission input shaft speed, and the transmission input shaft speed increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time decreases from the left side in Fig. 3 to the right side in Fig. 3 to.

[0031] The second diagram from the top in Fig. Figure 3 is a graph of the percentage switching completion as a function of time. The vertical axis represents the percentage switching completion, and the percentage switching completion increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time decreases from the left side in Fig. 3 to the right side in Fig. 3. The thin line 304 represents the target percentage of shift completion, and the thick line 302 represents the actual percentage of shift completion.

[0032] The third diagram from the top in Fig. Figure 3 is a graph of the percent switching completion error as a function of time. The vertical axis represents the percent switching completion error. The horizontal axis represents time, and time decreases from the left side to Fig. 3 to the right side in Fig. 3 to.

[0033] The fourth diagram from the top in Fig. Figure 3 is a graph of the output of the proportional-integral-derivative (PID) controller as a function of time. The vertical axis represents the output of the PID controller. The horizontal axis represents time, and time decreases from the left side in Fig. 3 to the right side in Fig. 3 to.

[0034] The fifth diagram from the top in Fig. Figure 3 is a graph of the modification of the input torque of the transmission input shaft speed as a function of time. The vertical axis represents the modification of the transmission input shaft torque. The horizontal axis represents time, and time decreases from the left side in Fig. 3 to the right side in Fig. 3 to.

[0035] At time T1, the transmission gear downshift begins. The downshift can be based on driver torque request (not shown), vehicle speed (not shown), and currently selected gear (not shown). The transmission input shaft speed is at a low value, and the actual percent shift completion is zero. The desired percent shift completion is at a high value from the previous shift. The percent shift completion error is a low constant value, reflecting that the percent shift error determination has not yet begun. The PID output is a low value, also indicating that the percent shift error determination has not yet begun. The input torque modification is also at a low value because the input torque modification has not yet begun.

[0036] Between time T1 and time T2, excessive holding pressure in the off-loading clutch is relieved. Furthermore, the off-loading clutch is stroke-adjusted to a state just before torque transfer begins via the off-loading clutch. The transmission input shaft speed, shift completion percentage, shift completion percentage error, PID output, and input torque modification values ​​remain unchanged.

[0037] At time T2, the transmission input shaft begins to increase with the off-load clutch release and the on-load clutch engagement. The actual percent shift completion begins to increase, and the desired percent shift completion is at a higher value based on the previous gear shift. The desired percent shift completion cannot be updated until the shift is partially completed, as shown in this example, because the on-load clutch engagement timing may have a greater impact on the shift completion time than the off-load clutch release. The percent shift completion error is at its previous value because it has not been updated. Likewise, the PID output remains at its previous value, and the transmission input shaft torque has not been modified.

[0038] Between times T2 and T3, the target percent shift completion value is updated based on the time since the shift started, and the actual percent shift completion increases. Furthermore, an error arises between the target percent shift completion and the actual percent shift completion because the actual shift completion is greater than the target percent shift completion after the target shift percentage for the current downshift is set to a lower value. The error starts at zero after the target percent shift completion is set and increases in a negative direction before reaching a constant value. The PID output also changes in response to the percent shift completion error. The input torque modification is set to a constant value before the target percent shift completion for the current shift is set.The torque modification of the transmission input shaft is then reduced because the desired percent shift completion is greater than the actual percent shift completion.

[0039] At time T3, the transmission input shaft speed reaches an increased value based on the new gear, the target percent shift completion, and the update of the actual percent shift completion stop. The percent shift completion error remains constant, and the PID output is also constant. The input torque modifier also reaches a final value of zero with the completion of the shift.

[0040] Thus, the open-loop input torque modification can be adjusted in response to an error between the desired percent shift completion and the actual percent shift completion. The open-loop input torque is modified by the output of a PID controller that controls the percent shift completion error. Furthermore, an adaptive term can be stored in memory that adjusts the open-loop input torque modification so that the open-loop torque modifier can be improved for subsequent downshifts.

[0041] Now on Fig. Referring to Figure 4, a method for operating a hybrid powertrain is shown. The method of Fig. 4 can be stored in a non-volatile memory of the Fig. 1 and Fig. 2 shown system. In addition, the method of Fig. 4 which in Fig. 3 Perform the operating sequence shown.

[0042] At 402, method 400 assesses whether the vehicle powertrain is in a regenerative mode. The vehicle powertrain may be in a regenerative mode when an electric machine is operating in a generator mode, in which the kinetic energy of the hybrid vehicle is converted into electrical energy. The vehicle may enter the regenerative mode during deceleration or times when the driver demand torque is below a threshold. If method 400 judges that the powertrain is in a regenerative mode, the answer is yes, and method 400 proceeds to 404; otherwise, the answer is no, and method 400 proceeds to end. Method 400 may assess whether the powertrain is in a regenerative mode to determine whether the electric machine torque can be adjusted to modify an open-loop transmission input shaft torque.

[0043] At 404, method 400 judges whether a downshift has been requested. A downshift may be requested in response to vehicle speed, driver demand torque, and a transmission shift routine, as determined from vehicle sensors. If method 400 judges that a downshift has been requested, the answer is yes, and method 400 proceeds to 406; otherwise, the answer is no, and method 400 proceeds to exit.

[0044] At 406, method 400 increases the pressure applied to the on-load clutch to stroke the on-load clutch to a position just before torque transfer through the on-load clutch begins. In one example, method 400 adjusts the solenoid valve to adjust the on-load clutch pressure. After adjusting the on-load clutch pressure to a start-up pressure, method 400 proceeds to 408.

[0045] At 408, method 400 reduces pressure applied to the off-load clutch to release the clutch holding pressure to a point just before the clutch begins to slip. In one example, method 400 adjusts operation of a solenoid valve for adjusting the off-load clutch pressure. After adjusting the off-load clutch pressure to a start-release pressure, method 400 proceeds to 410.

[0046] At 410, method 400 enters a torque transfer phase of the downshift, where on-coming clutch pressure is further increased and off-coming clutch pressure is further decreased. Torque provided at the transmission input shaft is transferred to the transmission output shaft to provide driveline braking via the on-coming clutch. As the on-coming clutch pressure begins to increase and the off-coming clutch pressure decreases, method 400 proceeds to 412.

[0047] At 412, method 400 judges whether the transmission gear downshift is complete. In one example, method 400 judges that the downshift is complete when the transmission input speed is a speed indicating that the new gear is engaged. For example, method 400 may judge that the shift is complete when the transmission input shaft speed is equal to the transmission output shaft speed multiplied by the new gear ratio. Alternatively, method 400 may judge that the transmission downshift is complete when pressure applied to the on-load clutch is greater than a threshold pressure. If method 400 judges that the shift is complete, the answer is yes, and the method proceeds to 430; otherwise, the answer is no, and method 400 proceeds to 414.

[0048] At 414, method 400 retrieves an adaptive transmission input shaft torque modifier term from memory. The adaptive transmission input shaft torque modifier may be determined as described at 420 or via an alternative method. After retrieving the adaptive transmission input shaft torque modifier term from memory, method 400 proceeds to 416.

[0049] At 416, method 400 determines the open-loop transmission input shaft torque based on driveline braking and the expected inertia change from the downshift from the current transmission gear to the new transmission gear. In one example, the open-loop transmission input shaft torque modifier is given by the following equation: OL_Tq_Mod=f(shift_id, input_speed, input_torq)+Adaptive_term where OL_Tq_Mod is the open-loop torque modification to the transmission input shaft torque, shift_id identifies the current gear and the new gear for downshifting, input_speed the current

[0050] Transmission input shaft speed, and input_torq is the current torque of the transmission input shaft. The transmission input torque can be a sum of the engine torque and the electric machine torque. Furthermore, the shift_id parameter indicates whether the engine and electric machine are coupled to the transmission input shaft, or whether only the electric machine is coupled to the transmission input shaft. Therefore, the different torque values ​​can be provided in an open-loop control system when only the electric machine is coupled to the transmission input shaft, as opposed to when the engine and electric machine are coupled to the transmission input shaft.

[0051] The function f outputs an empirically determined torque modification value that can be added to the desired transmission input torque (for example, a sum of engine torque and electric machine torque) to provide a set desired transmission input torque. Alternatively, the torque modification value can be multiplied by the desired transmission input torque in an open-loop control system to provide a set desired transmission input torque. The electric machine torque is adjusted in response to the set desired transmission input torque such that the engine and electric machine provide the set desired transmission input torque. In one example, the desired transmission input torque is based on the driver demand torque (for example, based on the accelerator pedal position and vehicle speed).After setting the open loop torque to the transmission input shaft, procedure 400 proceeds to 418.

[0052] At 418, method 400 determines an error between a desired percent shift completion and an actual percent shift completion. In one example, the desired percent shift completion is empirically determined and stored in memory. The desired percent shift completion is a value ranging from 0 (e.g., zero percent shift completion) to 1 (e.g., one hundred percent shift completion). The desired percent shift completion is based on a time from the start of the downshift. For example, the desired percent shift completion may begin increasing X milliseconds after the start of the downshift. Multiple desired percent shift completion values ​​are stored in memory, and the values ​​may be based on the shift_id, input_speed, and input_torq parameters.

[0053] The actual percentage switching completion is based on the following equation: Act_shift_comp=pres_input_speedinput_speed_ng−input_speed_pg where Act_shft_comp is the actual percent shift completion, pres_input_speed is the current transmission input shaft speed, input_speed_ng is the transmission input shaft speed in the new gear, and input_speed_pg is the transmission input shaft speed in the current gear. In one example, input_speed_ng and input_speed_pg can be determined by multiplying the output shaft speed by the respective new gear ratio and the current gear ratio. The transmission input shaft speed can be determined using a speed sensor.

[0054] The percent shift completion error is the target percent shift completion minus the actual percent shift completion. After determining the percent shift completion error, the procedure proceeds from step 400 to step 420.

[0055] At 420, method 400 determines the closed-loop transmission input shaft torque setting based on the percent shift completion error plus the open-loop input torque (e.g., the desired transmission input torque setting determined at 416). In one example, the closed-loop transmission input shaft torque setting is given by the following equation: CL_torq_adj=des_is_torq+PID_torq where CL_torq_adj is the closed-loop transmission input shaft torque setting, des_is_torq is the desired transmission input shaft torque determined at 416, and PID_torque is the output of a proportional-integral-derivative controller. The PID_torque value can be expressed as follows: PID_torq=Kp(psc_error(t))+Ki∫(psc_error(t)+Kdd(psc_error(t))dt where psc_error is the percent shift completion error determined at 418, Kp is a proportional gain, Ki is an integral gain, Kd is a derivative gain, and t is time. The current electric machine torque is adjusted based on the closed-loop transmission input shaft torque setting.

[0056] At 422, method 400 requests the vehicle system controller (VSC) to provide the requested transmission input shaft torque based on the closed-loop transmission input shaft torque setting. For example, the currently commanded transmission input shaft torque is set by the closed-loop transmission input shaft torque setting. The VSC may command an electric machine controller, or alternatively, the VSC may directly command the electric machine setting. After setting the current transmission input shaft torque, method 400 returns to 412.

[0057] At 430, method 400 assesses whether to adjust the adaptive transmission input shaft torque modifier stored in memory (e.g., the value retrieved at 414). In one example, method 400 determines a control effort by multiplying an integrated percent shift completion error by a weighting factor. The result is then compared to an upper and lower threshold. If the result exceeds the upper threshold, the adaptive transmission input shaft torque modifier is increased by a value of one (e.g., the adaptive adjustment term). On the other hand, if the result is below the lower threshold, the adaptive transmission input shaft torque modifier is decreased by a value of one (e.g., the adaptive adjustment term).The adaptive adjustment term is zero if the result is between the upper and lower thresholds or if the shift is not terminated. After determining the adaptive adjustment term, method 400 proceeds to 432.

[0058] At 432, method 400 stores the adaptive transmission input shaft torque modifier in memory. The value is stored in a memory location based on shift_id, input_speed, and input_torq. Thus, the revised adaptive transmission input shaft torque modifier term can be expressed as follows: Adaptive_term_m(shift_id, input_speed, input_torq)=Adaptive_term_old(shift_id, input_speed, input_torq)+add_inc where Adaptive_term_m is the newly adapted transmission input shaft torque modifier, shift_id is the shift identification as described at 416, input_speed is the transmission input shaft speed, input_torq is the transmission input shaft torque, Adaptive_term_old is the adapted transmission input shaft torque modifier retrieved from memory at 414, and add_inc is an increment or decrement value (for example, 1 or -1). Shift_id, input_speed, and input_torque are the basis for determining a unique address in memory that holds the adapted transmission input shaft torque for the current downshift conditions. After storing the adapted transmission input shaft torque in memory, method 400 exits.

[0059] In this way, torque at the transmission input shaft can be adjusted to improve shifting under conditions where the hybrid vehicle is in regenerative braking mode and during downshifts. Furthermore, multiple transmission shift torque settings can be provided based on specific transmission downshifts and transmission input conditions.

[0060] Thus, the procedure of Fig. 4 provides a powertrain operating method comprising: receiving, by a controller, vehicle operating conditions via sensors in communication with the controller; adjusting a torque applied to the transmission input shaft via a closed-loop control (for example, a closed-loop feedback control based on percent shift completion error or a difference between a desired shift completion profile and an actual shift completion) in response to a percentage of transmission gear shift completion; and applying the torque to the transmission via a torque source, the torque source in communication with the controller. The method includes where the percentage of transmission gear shift completion is based on the transmission output shaft speed in a new gear and the transmission output shaft speed in a current gear.The method includes where the transmission gear shift percentage is further based on dividing the current transmission output shaft speed by the transmission output shaft speed in a new gear minus the transmission output shaft speed in the current gear. The method includes where adjusting the torque applied to the transmission input shaft comprises adjusting a torque of an electric machine.

[0061] In some examples, the method includes adjusting the torque applied to the transmission input shaft during a downshift of a fixed-ratio transmission. The method includes the transmission input shaft being part of a transmission of a powertrain operating in a regenerative braking mode. The method includes converting the kinetic energy of the vehicle into electrical energy in the regenerative braking mode.

[0062] Furthermore, the procedure of Fig. 4 provides a powertrain operating method comprising: receiving, by a controller, operating conditions via sensors in communication with the controller; operating an electric machine in a generator mode based on the operating conditions; downshifting a transmission coupled to the electric machine while the electric machine is operating in generator mode; adjusting, via a controller, torque applied to a transmission input shaft in response to a transmission gear shift completion percentage error; and applying the torque to the transmission via a torque source, the torque source in communication with the controller.

[0063] The method includes where the transmission gear shift completion percentage error is based on a difference between a desired transmission gear shift completion value and an actual transmission gear shift completion value. The method includes where adjusting the torque applied to the transmission input shaft comprises adjusting a torque of the electric machine.

[0064] The method further includes inputting the transmission gear shift completion percentage error to a proportional-integral-derivative controller. The method further includes providing an adaptive adjustment value based on the output of the proportional-integral-derivative controller. The method further includes adjusting the output torque of the electric machine in response to the adaptive adjustment value. The method includes storing and applying the adaptive adjustment value during a subsequent downshift. The method includes selectively coupling the electric machine to an engine.

[0065] It should be appreciated that the exemplary control and estimation routines included herein may be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be performed by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The particular routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Thus, various illustrated acts, operations, and / or functions may be performed in the order illustrated, in parallel, or in some cases, omitted.Likewise, the order of processing is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and / or functions may be performed repeatedly depending on the particular strategy employed. Further, the described acts, operations, and / or functions may graphically represent code to be programmed into the non-transitory memory of the computer-readable storage medium in the engine control system, wherein the described acts are performed by execution of the instructions in a system including the various engine hardware components in combination with the electronic controller.

[0066] This concludes the description. A reading of it by one skilled in the art would reveal many changes and modifications without departing from the spirit and scope of the description. For example, I3, I4, I5, V6, V8, V10, and V12 engines powered by natural gas, gasoline, diesel, or alternative fuel configurations could advantageously utilize the present description.

Claims

[1] A powertrain operating method for a hybrid vehicle, comprising: Receiving operating conditions by a controller via sensors connected to the controller; Adjusting a torque applied to the transmission input shaft via a closed-loop control system in response to a percentage of transmission gear shift completion based on operating conditions; and Applying the torque to a transmission via a torque source, the torque source in communication with the controller, wherein the percentage of transmission gear shift completion is based on the transmission output shaft speed in a new gear and the transmission output shaft speed in a current gear; and wherein the percentage of transmission gear shift completion is further based on dividing the current transmission output shaft speed by the transmission output shaft in the new gear minus the transmission output shaft speed in the current gear. [2] The method of claim 1, wherein adjusting the torque applied to the transmission input shaft comprises adjusting a torque of an electric machine. [3] The method of claim 1, wherein adjusting the torque applied to the transmission input shaft is performed during a downshift of a fixed ratio transmission. [4] The method according to claim 3, wherein the transmission input shaft is part of a transmission of a drive train operating in a recuperation mode. [5] Method according to claim 4, wherein the kinetic energy of the vehicle is converted into electrical energy in the recuperation mode. [6] A powertrain operating method for a hybrid vehicle, comprising: Receiving operating conditions by a controller via sensors connected to the controller; Operating an electrical machine in a generator mode based on operating conditions; Downshifting a transmission coupled to the electric machine while the electric machine is operating in generator mode; Adjusting the torque applied to a transmission input shaft via the controller in response to a transmission gear shift completion percentage error; and Applying torque to the transmission via a torque source, whereby the torque source is connected to the controller. [7] The method of claim 6, wherein the transmission gear shift completion percentage error is based on a difference between a desired transmission gear shift completion value and an actual transmission gear shift completion value. [8] The method of claim 6, wherein adjusting the torque applied to the transmission input shaft comprises adjusting a torque of the electric machine, and wherein the torque source is the electric machine. [9] The method of claim 6, wherein the transmission gear shift completion percentage error is further input to a proportional-integral-derivative controller. [10] The method of claim 9, further comprising: providing an adaptive adjustment value based on the output of the proportional-integral-derivative controller. [11] The method of claim 10, further comprising adjusting the output torque of the electric machine in response to the adaptive adjustment value. [12] The method of claim 11, wherein the adaptive adjustment value is stored and applied during a subsequent downshift. [13] The method of claim 6, wherein the electric machine is selectively coupled to a prime mover. [14] System comprising: an internal combustion engine; an electrical machine; a separating clutch positioned in a drive train between the internal combustion engine and the electric machine; a torque converter including a lock-up clutch coupled to the engine; and a controller including executable instructions stored in non-volatile memory for setting a torque command for the electric machine during a regenerative mode in response to a percentage of the closed-loop shift completion error. [15] The system of claim 14, wherein the closed-loop shift completion error percentage is based on a difference between a desired shift completion percentage and an actual shift completion percentage. [16] The system of claim 15, further comprising additional instructions for determining an adjustment term based on the percentage of closed-loop switch completion error. [17] The system of claim 16, wherein the adjustment term is based on an output of a proportional-integral-derivative controller.

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