Method for controlling a drivetrain system during overrun operation

Abstract

Method for operating a vehicle (100) comprising an internal combustion engine (40) and a torque machine (35) rotatably coupled to an input element (42) of a transmission (50), the method comprising: operating the vehicle (100) in a coasting mode in response to a zero axle torque requested by the driver; and directing the engine operation to a state without fuel supply; opening a clutch configured to transmit torque between the engine (40) and the transmission (50), and thereafter using a controller to operate the torque machine (35) such that the input element (42) rotates in order to control the engine (40) during a transition over a predetermined engine speed;wherein during the transition beyond the predetermined engine speed, the engine (40) is decelerated to achieve an engine speed that is lower than the predetermined engine speed; characterized in that, in response to the axle torque requested by the driver from zero and before the clutch is opened, the torque machine (35) is operated as a generator; wherein the vehicle (100) further comprises a hydraulic fluid pump (45) rotatably coupled to the input element (42) and fluidically connected to a hydraulic circuit of the transmission (50); wherein the engine speed that is lower than the predetermined engine speed comprises an engine speed corresponding to a speed for the hydraulic pump (45) sufficient to achieve a preferred hydraulic pressure in the hydraulic circuit.

Description

TECHNICAL AREA

[0001] This disclosure relates to the powertrain system control. BACKGROUND

[0002] The statements in this section merely provide background information regarding the present disclosure and do not constitute prior art.

[0003] Vehicles use powertrain systems to generate drive torque for propulsion. Powertrain systems can transmit torque from multiple torque-generating devices, such as a power unit and one or more non-combustion torque machines, through a transmission device to an output element coupled to a final drive. Control systems for operating such powertrain systems operate the torque-generating devices and engage torque transmission elements in the transmission to deliver torque in response to operator-specified output torque requirements, taking into account fuel economy, emissions, driving behavior, and other factors.Non-internal-engine torque machines can include electric working machines that can be operated independently of a torque input from the internal combustion engine, functioning as motors or generators to produce a torque input for the transmission. These torque machines can convert kinetic vehicle energy transmitted via the vehicle's final drive into electrical energy, which can be stored in an electrical energy storage device.A control system monitors various inputs from the vehicle and the operator and provides operational control of the hybrid powertrain, including controlling the transmission operating state and gear shifting, controlling the torque generating devices, and regulating the exchange of electrical power between the electrical energy storage device and the electric working machines to manage the transmission outputs, including torque and speed. SUMMARY

[0004] A method for operating a vehicle comprising an internal combustion engine and a torque machine rotatably coupled to an input element of a transmission includes operating the vehicle in a coasting or rolling mode in response to axle torque requested by the driver and directing the engine operation to a state without fuel supply. A controller is used to operate the torque machine such that the input element rotates in order to control the engine during a transition across a predetermined engine speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] One or more embodiments will now be described by way of example with reference to the attached drawings, in which:

[0006] Fig.1 represents a vehicle in accordance with the disclosure, comprising a drive train system having several torque-generating devices, including an internal combustion engine and an electrically powered torque machine, which are mechanically coupled to a transmission;

[0007] Fig. 2 presents a flow diagram in accordance with the disclosure showing a thrust mode control routine that is executed to control the operation of an internal combustion engine;

[0008] Fig. 3 represents several temporally coincident parameters in accordance with the disclosure, showing the operation of a drivetrain system executing the overrun mode control routine, wherein the engine speed transitions to 0 RPM during operation in overrun mode; and

[0009] Fig.4 represents several temporally coincident parameters in accordance with the disclosure, showing the operation of a drive train system that executes the overrun mode control routine, wherein the engine speed transitions to a non-zero engine speed during operation in overrun mode. DETAILED DESCRIPTION

[0010] Now, based on the drawings, in which the illustrations serve only to explain certain exemplary embodiments and not to limit them, it shows Fig. 1 schematically a vehicle 100 , which is a powertrain system 20 includes a final drive 60 is coupled and controlled by a control system 10 is controlled. The powertrain system 20 includes several torque-generating devices including an internal combustion engine 40 and an electrically powered torque machine35 , which have a gearbox 50 a torque at a final drive 60 transferred. A preferred configuration of the powertrain system 20 includes the fact that the torque machine 35 with a crankshaft 36 the power machine 40 rotatably mechanically coupled, which is connected via a torque converter 52 with an input element 42 of the gearbox 50 It is mechanically coupled and rotatable. As shown, the crankshaft 36 via a pulley mechanism 38 mechanically rotatable with a torque machine 35 coupled and is a hydraulic fluid pump 45 via a direct mechanical coupling mechanism 43 directly mechanically with the input element 42 coupled. Thus, the hydraulic fluid pump rotates. 45 together with the electrically powered torque machine 35and can the electrically powered torque machine 35 used to power the hydraulic fluid pump 45 with or without torque input from the power unit 40 to rotate. Instead, other configurations of the powertrain system are possible. 20 are used, which the torque machine 35 included, which are connected to the power machine 40 rotatably mechanically coupled, which is connected to the hydraulic fluid pump 45 and with the input element 42 of the gearbox 50 It is mechanically coupled and rotatable.

[0011] The power machine 40 is preferably a multi-cylinder internal combustion engine that converts fuel into mechanical torque via a thermodynamic combustion process. The engine 40It is equipped with multiple actuators and sensing devices to monitor operation and deliver fuel to form a combustion charge, generating torque that responds to an operator torque request. The power unit 40 is configured to operate continuously during the operation of the powertrain system 20 It executes auto-start and auto-stop control schemes and fuel cut-off control schemes (FCO control schemes). When the engine 40 If it is not rotating, it is considered to be in an OFF state. If it is rotating, including one or more FCO states where it is rotating but not being fueled, the engine is considered to be in an OFF state. 40 as being in a ON state.

[0012] The electrically powered torque machine 35is preferably a high-voltage multi-phase electric motor / electric generator configured to convert stored electrical energy into mechanical power and to convert mechanical power into electrical energy stored in a high-voltage battery 25 can be stored. The torque machine 35 Includes a rotor and a stator and an attached position sensor 37 , which in one embodiment is a variable reluctance resolver. The electrically powered torque machine 35 includes an output element that uses a pulley mechanism 38 , which provides a mechanical power path in between, with the crankshaft 36 the power machine 40 It is mechanically rotatable. The pulley mechanism 38 is configured to transmit torque between the power machine 40 and the torque machine 35including torque transmission from the torque machine 35 to the power machine 40 for an auto-start and auto-stop functionality, a drive torque assist, a torque transmission for regenerative vehicle braking and a torque transmission from the power unit 40 to the torque machine 35 to effect the high-voltage electrical charge. In one embodiment, the pulley mechanism includes 38 a multi-ribbed belt that runs between a first pulley mounted on the crankshaft 36 the power machine 40 is attached, and a second pulley, which is attached to a rotor of the torque machine 35 The coupled rotating shaft is guided, which is referred to as a belt-driven starter generator system (BAS system). Alternatively, the pulley mechanism can be 38a displacement gear mechanism or other positive-locking mechanical connection. In one embodiment, the power machine can include 40 a solenoid-operated low-voltage electric starter 39 included to start the engine in response to an ignition key start event.

[0013] The high-voltage battery 25 is via a high-voltage direct current bus 29 electrically with a power converter module 32 connected to respond to control signals from the control system 10 Exit, high-voltage direct current electrical power to the torque machine 35 to transfer the power converter module 32 is via a multi-phase motor control power bus 31 electrically with the torque machine 35 connected. The power converter module 32It is configured with suitable control circuits, including power transistors such as IGBTs, for transforming high-voltage direct current (DC) power into high-voltage alternating current (AC) power and for transforming high-voltage AC power into high-voltage DC power. Preferably, the converter module utilizes 32 a pulse width modulation (PWM) control to manage stored direct current electrical power supplied by the high-voltage battery 25 outputs, in alternating current power to drive the torque machine 35 , to generate torque, to convert. Similarly, the power converter module converts 32 mechanical power applied to the torque machine 35 is transferred, including as part of a regenerative control strategy, into direct current electrical power to generate electrical energy which is stored in the high-voltage battery. 25can be stored. The power converter module 32 It is configured to receive motor control commands and to control power converter states in order to provide motor drive and regeneration functionality. In one embodiment, an electrical DC / DC power converter is used. 34 electrically with a low-voltage bus 28 and with a low-voltage battery 27 connected and electrically connected to a high-voltage bus 29 connected. Such electrical power connections are known and not described in detail. The low-voltage battery 27 is electrically powered with an additional power system 26 connected to provide low-voltage electrical power for low-voltage systems in the vehicle, including, for example, electric windows, HVAC fans, seats, and the electric starter operated by a low-voltage solenoid. 39 to provide.

[0014] The gearbox 50 transmits a torque between the input element 42 and an output element 62 and can take the form of, for example, an automatic transmission, a dual-clutch transmission, a clutchless manual transmission, or a manual transmission. The transmission 50 is done using a controllable hydraulic circuit 47 , which is connected to the control module 12 either directly or via a communication bus 18 It is connected via signal technology and controlled. The hydraulic circuit 47 controls the operation of the gearbox 50in one of several selectable fixed gear operating modes with a transmission ratio that achieves a preferred match between an operator torque requirement and a power machine operating point, and which preferably uses one or more differential gear sets and hydraulically actuated clutches to transmit torque between the input element over a range of speed ratios in the operating ranges 42 and the starting element 62 to effect the gearbox 50The transmission performs upshifts to switch to an operating mode with a lower numerical multiplication ratio (gear ratio) and downshifts to switch to an operating mode with a higher numerical multiplication ratio. An upshift requires a decrease in engine speed so that the engine speed is matched to the transmission output speed multiplied by the gear ratio, at a ratio appropriate to the desired operating mode. A downshift requires an increase in engine speed so that the engine speed is matched to the transmission output speed multiplied by the gear ratio, at a ratio appropriate to the desired operating mode. 50 is configured to operate in an idle state in which the input element 42from an initial element 62 mechanically decoupled. Such a transmission configuration may include a torque converter. 52 preferably includes a controllable torque converter lock-up clutch. Alternatively, the transmission can 50 in addition to the torque converter 52 or be configured with a forward clutch element replacing it, wherein the forward clutch element engages the transmission 50 from the power machine 40 automatically disengaged when deactivated or in an open state, with the forward clutch element between the transmission 50 and the direct mechanical coupling device 43 , that the hydraulic fluid pump 45 with the input element 42 coupled, located. The hydraulic fluid pump 45 leads to one or more powertrain system elements, including, for example, the controllable hydraulic circuit 47, pressurised hydraulic fluid to, in order to control the flow of pressurised hydraulic fluid to elements of the transmission 50 to control in order to actuate selected coupling elements.

[0015] The final drive 60 can a differential gear device 65 included, which are mechanically connected to an axis 64 , coupled with a transaxle or with a half-shaft, which is mechanically connected to a wheel 66 is coupled. The final drive 60 transmits drive power between the gearbox 50 and a road surface.

[0016] The tax system 10 contains a control module 12 , which is connected to an operator interface in terms of signaling technology 14 is connected. Preferably the control module contains 12 several discrete devices located in the same position as the individual elements of the drivetrain system 20are to enable operational control of the individual elements of the powertrain system 20 to effect. Furthermore, the control module can 12 It contains a control device that provides hierarchical control of other control devices. The control module 12 In terms of signaling and functionality, it is either direct or via a communication bus. 18 for monitoring operation and determining parameter states using the high-voltage battery 25 and with the power converter module 32 and with the torque machine 35 and with the power machine 40 and with the gearbox 50 connected. The operator interface 14 of the vehicle 100 is a controller that is connected via signal technology to several human / machine interface devices, through which the vehicle operator controls the operation of the vehicle. 100instructs. The human-machine interface devices include, for example, an accelerator pedal. 15 , a brake pedal 16 , a transmission range selector (PRNDL) 17 and a vehicle cruise control system 18 Other human / machine interface devices preferably include an ignition switch to allow an operator to control the power machine. 40 starts and starts, a steering wheel and a headlight switch. The accelerator pedal 15 provides a signal input that indicates an accelerator pedal position, and the brake pedal 16 Provides a signal input that indicates a brake pedal position. The transmission range selector 17 provides a signal input that specifies the direction of the vehicle's intended movement by the operator, including a discrete number of operator-selectable positions that indicate the preferred direction of rotation of the output element. 62Specify either in a forward or in a backward direction.

[0017] The powertrain system 20 contains a communication scheme that includes the communication bus 18 to effect communication in the form of sensor signals and actuator command signals between the control system 10 and elements of the powertrain system 20 The communication scheme utilizes one or more communication systems and communication devices, including, for example, the communication bus. 18 , a direct connection, a local network bus, a serial peripheral interface bus and wireless communications to effect information transmission.

[0018] Control module, module, control unit, controller, control unit, processor, and similar terms mean any combination of one or more application-specific integrated circuits (ASICs), electronic circuits, central processing units (preferably microprocessors), and associated memory and storage (read-only, programmable read-only, write-read, hard disk, etc.) that execute one or more software or firmware programs or software or firmware routines, combination logic circuits, input / output circuits and devices, suitable signal conditioning and buffering circuits, and other components for providing the described functionality. Software, firmware, programs, instructions, routines, code, algorithms, and similar terms mean any sets of instructions that include calibrations and lookup tables.The control module contains a set of control routines that are executed to provide the desired functions. These routines are executed similarly to a central processing unit and can be used to monitor inputs from sensing devices and other networked control modules, as well as to perform control and diagnostic routines for managing actuator operation. The routines can be executed at regular intervals during continuous power engine and vehicle operation, for example, every 100 microseconds, 3.125, 6.25, 12.5, 25, and 100 milliseconds. Alternatively, the routines can be executed in response to the occurrence of an event.

[0019] Vehicle operation in response to operator requests includes acceleration, braking, coasting, and idling modes. The acceleration mode includes an operator request to increase vehicle speed. The braking mode includes an operator request to decrease vehicle speed. The coasting mode includes vehicle operation where the vehicle is currently moving at a velocity rate without an operator request to either brake or accelerate, with the vehicle speed determined based on the current vehicle speed and momentum, current vehicle wind resistance, current vehicle rolling resistance, and current final drive inertial resistance.The idle operating mode includes a vehicle operation in which the vehicle speed is at or near zero, wherein the transmission range selector is in a non-propulsion range or in one of the propulsion ranges, wherein the operator request includes the input of zero into the accelerator pedal and a minimal or slight input into the brake pedal.

[0020] In overrun mode, the controller, in response to an output torque request that includes a zero torque request input to an accelerator pedal, executes one or more control routines to control the powertrain system. This includes instructing the engine to operate in a non-fueled state and opening a clutch configured to directly couple the engine and transmission rotations, such as a torque converter lock-up clutch. The engine causes the input element to rotate to control the engine rotation, including decelerating the engine to overcome a disturbing final drive resonance, which may contain a resonant frequency. This may include operating the engine to cause the input element to rotate in order to control the engine to achieve a zero engine speed condition.

[0021] Fig. 2 is a flowchart that includes a thrust mode control routine (control routine) 200 shows, which are used to control the operation of a powertrain system, e.g., the one based on Fig. 1 described powertrain system 20 , is executed. The control routine 200 The electric working machine controls the system to effect smooth entry into and exit from overrun mode and preferably includes maintaining transmission oil pressure in overrun mode, including operation with a calibratable deceleration rate for overrun mode when applied to an automatic transmission in gear with the torque converter lock-up clutch disengaged. Table 1 is a key to Fig. 2 provided, wherein the numbered blocks and their corresponding functions are set out as follows. Table 1 BLOCK BLOCK CONTENT 202 Monitoring of Vss, BPP, PPS, RPM, TCC clutch status 204 Calculating DRAT 206 In push mode? – BPP = 0% – DRAT < A 210 Operating the drivetrain system in overrun mode 212 Calculating X = vehicle acceleration with engine OFF 214 DRAT < X? 216 Determining variable thrust operating state operating parameters 218 Operating the powertrain system in variable overrun mode 220 Monitoring the DRAT and setting the assigned vehicle speed 222 Entering the push-pull preparation mode 224 Operating the drivetrain system in the engine-off overrun condition 226 Is BPP > 0? 230 Exiting the engine's overrun mode

[0022] Various vehicle operating parameters are monitored, including vehicle speed (Vss), brake pedal position (BPP), accelerator pedal position (PPS), engine speed (RPM), and torque converter lock-up clutch state (TCC clutch state). 202 ) monitored, from which a current vehicle operating state is determined ( 204 This includes determining a driver-requested axle torque (DRAT). The driver-requested axle torque and the brake pedal position are evaluated to determine whether the powertrain system should operate in a coasting mode ( 206). If either the brake pedal position is not zero (BPP > 0%) or the axle torque requested by the driver is equal to or greater than a calibratable threshold torque (A), (DRAT > A), the operating conditions are such that the powertrain system cannot operate in overrun mode ( 206 ) (0), where no further action is taken in this iteration with respect to operation in the overrun mode. The calibratable threshold torque (A) is determined on the basis of operating conditions including vehicle speed, gear range, environmental conditions including temperature and altitude, and other factors.

[0023] The vehicle operating parameters will continue to be monitored ( 202), to determine whether such operation is possible at a future time. If the brake pedal position is zero (BPP = 0%) and the axle torque requested by the driver is less than the calibratable threshold torque (DRAT < A) ( 206 ) (1), the powertrain system can operate in overrun mode ( 210 The thrust operating mode includes a power-engine-off thrust operating state and a variable thrust operating state.

[0024] Operating the powertrain system in overrun mode involves determining a preferred vehicle acceleration with the engine in the OFF state (X) ( 212 ), which is compared with the axle torque requested by the driver ( 214The preferred vehicle acceleration with the power unit in the OFF state is a calibrated value selected for a vehicle design, taking into account vehicle aerodynamics, rolling resistance, operator expectations for deceleration, and other factors related to vehicle speed. If the axle torque requested by the driver is less than the vehicle acceleration with the power unit in the OFF state (DRAT < X) ( 214 ) (1), the operation of the powertrain system includes preparing for the operation of the powertrain system in the engine-off overrun condition ( 222). This includes disabling the torque converter lock-up clutch, performing a power engine fuel cut-off in preparation for the power engine transitioning to the OFF state, and operating the torque engine to decelerate the power engine in order to bring the power engine speed down to 0 RPM to achieve the power engine OFF state ( 224This operation involves operating the torque machine to decelerate the power machine through one or more power machine speeds associated with an undesired frequency detected between the power machine's normal operating mode and a power machine OFF mode of 0 RPM. An undesired frequency may, for example, include a power machine speed associated with one or more resonant or natural frequencies of the powertrain, final drive, or other vehicle components and systems, such as the vehicle body structure, resulting in a disturbing resonance such as a low-frequency noise generated by the final drive, often described as a droning or squealing noise, final drive imbalances, vehicle judder, powertrain start-up judder, and axle whine.A disturbing resonance includes an audible sound, a physical vibration, and other signs perceptible to a vehicle operator and / or vehicle occupants during vehicle operation. The operation of the engine can excite one or more such disturbing resonances by achieving one or more final drive speeds corresponding to one or more resonant frequencies. Operating the torque machine to control the engine speed and engine deceleration rate across one or more final drive resonant speeds includes a preferred engine deceleration, which is specifically selected for a vehicle design and engine / powertrain configuration based on its one or more resonant frequencies.

[0025] If the axle torque requested by the driver is not less than the vehicle acceleration with the engine in the OFF state (X), (DRAT < X) ( 214 ) (0), the powertrain system operates in the variable overrun operating state ( 216 ), which includes continuing engine operation in the engine fuel cut-off state and determining a target engine speed associated with the powertrain system operation that achieves the axle torque requested by the driver, with the torque engine operating in a speed control mode that maintains engine operation at a target speed and deceleration rate. The target engine speed is determined based on the vehicle speed, the transmission gear position, the transmission oil temperature, and the operating characteristics of the torque converter.

[0026] During this period, the vehicle operates in variable overrun mode ( 218 ), with the torque converter lock-up clutch open and the engine rotating in the fuel cut-off state. The axle torque requested by the driver is monitored to determine that it falls within a range between the vehicle acceleration with the engine in an OFF state (X) and the calibratable threshold torque (A). Based on these conditions, the torque engine speed and the corresponding engine speed are adjusted in response to the driver-requested axle torque and the target engine speed ( 220) set. In this way, the vehicle deceleration rate can be controlled using the torque converter to adjust the strength of the engine's driving resistance via speed control by the torque converter, in order to meet the coasting requirements associated with a vehicle's technical specifications. For example, a vehicle driving resistance and an associated deceleration rate during coasting can be in the range of 0.05 g to 0.10 g to produce vehicle deceleration. Such operation allows the torque converter to facilitate smooth entry into and exit from coasting mode and to maintain or otherwise control the transmission oil pressure in the automatic transmission during coasting.Furthermore, the engine speed is inversely proportional to the engine's rolling resistance, so the rate of vehicle deceleration can be controlled by adjusting the engine speed. When the torque converter lock-up clutch is engaged in gear on the automatic transmission, the acceleration rate for coasting operation is calibrated.

[0027] During operation, both in the engine-off overrun condition ( 224 ) as well as in the variable thrust operating state ( 218 ) the brake pedal position (BPP) is monitored ( 226 This operation will continue as long as ( 226) (0), as the brake pedal position is zero (BPP = 0%). Such operation can also change in response to the axle torque requested by the driver. If the brake pedal position becomes other than zero (BPP > 0%), this operation is stopped ( 226 (1) The control routine interrupts operation in overrun mode and initiates regenerative braking. In the drive train consisting of Fig. 1. This operation may include using the torque machine to increase the engine speed to a target speed in order to lock the torque converter lock-up clutch for regenerative braking. Increasing the engine speed is performed to operate the hydraulic pump to achieve sufficient hydraulic pressure in the torque converter to engage the torque converter lock-up clutch. Furthermore, this may include the engine auto-start ( 230 ).

[0028] Fig. Figure 3 graphically shows several temporally coincident parameters that illustrate the operation of a vehicle representing an embodiment of the powertrain system. 20 uses an implementation of the control routine 200 out of Fig. 2 operates during a vehicle operating cycle that includes a power engine start / run event, vehicle acceleration, steady state, deceleration, and vehicle stop. In this representation, the powertrain system operates in a power engine-off overrun operating state, in which the power engine speed transitions to 0 RPM during operation in overrun mode.

[0029] The parameters shown include the vehicle speed (km / h) 302 , the engine speed (RPM) 304 , the engine fuel flow 306 (Nm) (which indicates the engine torque), the engine torque (Nm) 308, the torque converter lock-up clutch status (locked = 1, unlocked or open = 0) 310 , one accelerator pedal position (%) 303 and a brake pedal position (%) 305 , all in relation to time 320 , shown on the horizontal axis. The data displayed reflects vehicle operation during the execution of the control routine. 200 including vehicle speed 312 , the engine speed 314 , the engine fuel flow 316 (which indicates the engine torque), the torque engine torque 318 and the torque converter lock-up clutch status 330 , which respond to signals from the human / machine interface devices, including an operator acceleration request 313 and an operator brake request 315address. In contrast, the data presented also reflects the vehicle operation, which includes the control routine. 200 does not use, including vehicle speed 332 , the engine speed 334 , the engine fuel flow 336 (which indicates the engine torque), the torque engine torque 338 and the torque converter lock-up clutch status 340 , which respond to signals from the human / machine interface devices, including the operator acceleration request 313 and the operator brake request 315 address.

[0030] Vehicle operation includes engine start / run and vehicle acceleration, which at the time 321 in response to operator commands, including an increase in the operator acceleration requirement 313 begin. At the time 322The operating conditions become conducive to the locking of the torque converter lock-up clutch, which is achieved by a change in the torque converter lock-up clutch status. 330 is specified from 0 to 1. Before the time 323 The powertrain operation is unaffected by whether the control routine 200 is executed. At the time 323 Does the operator acceleration requirement change? 313 to 0%, which allows the vehicle to enter overrun mode. The torque converter lock-up clutch status 330 The value changes from 1 to 0, thus deactivating the torque converter lock-up clutch. The control routine responds to specific operating conditions. 200 by controlling the fuel flow in the engine 316 to zero and the engine speed 314 reduced to zero, whereby the torque machine torque 318is controlled in such a way that the transition is effected. Immediately before the point in time 324 The operator brake request is being processed 315 This is determined by an operator input into the brake pedal. In response, the torque motor's torque increases. 318 to make the power engine rotate, which is achieved by increasing the speed of the power engine 314 This is specified. Since the torque engine provides the torque to rotate the power engine, there is no corresponding increase in the power engine fuel flow. 316 Before the time 325 The power unit, with its associated damping via the torque converter, has transitioned through one or more rotational speeds corresponding to one or more final drive resonant frequencies. At the time 325The torque converter lock-up clutch is engaged, indicated by a change in the torque converter lock-up clutch status from 0 to 1, enabling operation in regenerative braking mode. The torque machine torque 318 changes from a torque-generating state, i.e., from a positive net value, to a state of electrical power generation, i.e., to a negative net value. At or near the point in time 326 When the vehicle's forward movement stops, the torque converter lock-up clutch is deactivated and the engine speed decreases to 0 RPM with the associated action by the torque engine.

[0031] In contrast, the torque converter lock-up clutch status remains unchanged. 340 during powertrain system operation, which uses the control routine that the control routine 200not used, activated (i.e., equal to 1) after the operator acceleration request. 313 was reduced to 0%. The engine speed 334 The engine speed reaches and remains proportional to the vehicle speed, with the torque converter synchronized with the associated engine fuel flow. 336 It is locked to maintain engine operation. The engine fuel flow 336 will only be activated in response to the vehicle braking at the time 324 reduced to 0 g / s.

[0032] Fig. Figure 4 graphically shows several temporally coincident parameters that illustrate the operation of a vehicle representing an embodiment of the powertrain system. 20 uses an embodiment of the based on Fig. 2 described tax routine 200The vehicle operates during a vehicle operating cycle that includes a power engine start / run event, vehicle acceleration, a steady state, deceleration, and a vehicle stop. In this representation, the vehicle operates in a variable overrun operating state, in which the power engine speed transitions to a non-zero speed during overrun operation to maintain the hydraulic fluid pressure in the torque converter.

[0033] The parameters shown include the vehicle speed (km / h) 302 , the engine speed (RPM) 304 , the engine fuel flow 306 (Nm) (which indicates the engine torque), the engine torque (Nm) 308 , the torque converter lock-up clutch status (locked = 1, unlocked = 0) 310 , one accelerator pedal position (%) 303 and a brake pedal position (%) 305, all in relation to time 420 , which is shown on the horizontal axis.

[0034] The data shown reflects vehicle operation during the execution of the control routine. 200 including vehicle speed 312 , the engine speed 414 , the engine fuel flow 416 (which indicates the engine torque), the torque engine torque 418 and the torque converter lock-up clutch status 330 , which respond to signals from the human / machine interface devices, including an operator acceleration request 313 and an operator brake request 315 address. In contrast, the data presented also reflects the powertrain system operation, which includes the control routine. 200 does not use, including vehicle speed 332 , the engine speed 334, the engine fuel flow 336 (which indicates the engine torque), the torque engine torque 338 and the torque converter lock-up clutch status 340 , which respond to signals from the human / machine interface devices, including the operator acceleration request 313 and the operator brake request 315 address. Vehicle operation is analogous to that based on... Fig. 3 shown.

[0035] Vehicle operation includes engine start / run and vehicle acceleration, which at the time 421 in response to operator commands, including an increase in the operator acceleration requirement 313 begin. At the time 422 Are the operating conditions conducive to the locking of the torque converter lock-up clutch, which is indicated by a change in the torque converter lock-up clutch status? 330is specified from 0 to 1. Before the time 423 Vehicle operation is unaffected by whether the tax routine 200 is executed. At the time 423 Does the operator acceleration requirement change? 313 to 0%, thus enabling the vehicle to operate in overrun mode. The control routine 200 It addresses the fact that it controls the fuel flow in the engine. 416 reduced to zero, while the torque machine speed 418 is controlled in such a way that the engine speed 414 is maintained to operate the hydraulic pump in such a way that it is sufficient to maintain the hydraulic pressure above a minimum threshold pressure. The torque converter lock-up clutch status 330 The value can change from 1 to 0, indicating deactivation of the torque converter lock-up clutch. This occurs when the operator brakes are requested. 315 at the time 424as the number increases, operations will continue as before based on Fig. 3 continued as described. This includes the following. At the time 425 The torque converter lock-up clutch is engaged, indicated by a change in the torque converter lock-up clutch status from 0 to 1, enabling operation in regenerative braking mode. The torque machine torque 418 changes from a torque-generating state, i.e., a positive net value, to a state of electrical power generation, i.e., a negative net value. At or near the time 426 When the vehicle's forward movement stops, the torque converter lock-up clutch is deactivated and the engine speed decreases to 0 RPM with the associated action by the torque engine.

[0036] The tax routine 200Provides a vehicle overrun mode function that utilizes additional torque from a torque motor to smooth out final drive vibration during motor autostart and motor autostop transitions. Additionally, the overrun mode control routine can 200 provide a minimum transmission oil pressure to enable variable vehicle overrun deceleration rates that are calibratable and therefore selectable.

[0037] The disclosure has described certain preferred embodiments and modifications thereto. Further modifications and adaptations may occur to others upon reading and understanding the description. Therefore, the disclosure is not intended to be limited to the particular embodiment(s) disclosed as the best embodiment(s) for carrying out this disclosure, but rather to include all embodiments within the scope of the appended claims.

Claims

[1] Method for operating a vehicle comprising an internal combustion engine and a torque machine rotatably coupled to an input element of a transmission, the method comprising: Operating the vehicle in a coasting mode in response to axle torque requested by the driver; Instructing the engine to operate in a state without fuel supply; and Using a controller to operate the torque machine so that the input element rotates in order to control the power machine during a transition across a predetermined power machine speed. [2] Method according to claim 1, wherein the controller is used to operate the torque machine to rotate the input element in order to control the power machine during the transition above the predetermined power machine speed when the axle torque requested by the driver is less than a predetermined axle torque. [3] Method according to claim 1, further comprising using the controller to operate the torque machine such that the torque machine driving resistance is adjusted to control the vehicle deceleration in response to the axle torque requested by the driver when the axle torque requested by the driver is greater than a predetermined axle torque. [4] Method according to claim 3, wherein the torque machine is operated in a speed control mode. [5] Method according to claim 1, wherein the use of the controller to operate the torque machine such that the input element rotates in order to control the power machine during the transition over a predetermined power machine speed comprises decelerating the power machine during the transition over the predetermined power machine speed in order to achieve a power machine speed of zero condition. [6] Method according to claim 1, wherein the use of the controller to operate the torque machine in such a way that the input element rotates in order to control the power machine during the transition over a predetermined power machine speed comprises decelerating the power machine during the transition over the predetermined power machine speed in order to achieve a power machine speed which is less than the predetermined power machine speed. [7] Method according to claim 6, wherein the vehicle further comprises a hydraulic fluid pump rotatably coupled to the input element and fluidically connected to a hydraulic circuit of the transmission; and wherein the engine speed, which is less than the predetermined engine speed, comprises an engine speed corresponding to a speed for the hydraulic pump sufficient to achieve a preferred hydraulic pressure in the hydraulic circuit. [8] The method of claim 1, further comprising opening a clutch configured to transmit torque between the engine and the transmission prior to transitioning beyond the predetermined engine speed. [9] Method according to claim 8, wherein opening the clutch comprises opening a clutch of a torque converter configured to transmit torque between the engine and the transmission. [10] The method of claim 1, further comprising interrupting the operation of the vehicle in overrun mode in response to an operator brake request and operating the torque machine to rotate the input element in order to accelerate the power machine so that it passes over the predetermined power machine speed, activating a clutch configured to transmit a torque between the power machine and the transmission, and subsequently operating the torque machine in response to the operator brake request.

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