Powertrain play control procedure during driver application / release of the accelerator pedal

Abstract

A method for controlling a vehicle (10) having a traction motor (12, 14), the method comprising: Controlling the torque of the traction motor (12, 14), which is an internal combustion engine (12) and / or an electric motor (14), by a region (254, 264) surrounding a wheel torque reversal of the vehicle (10), Controlling the driveline input torque during torque reversal of the driveline output torque (256, 266) to limit the rate of change of the output torque, and Controlling the torque (252, 262) of the traction motor (12, 14) during a torque reversal of at least one component of the driveline to limit the rate of change of the torque applied to the component of the driveline, in which the torque of the traction motor (12, 14) is controlled to a first rate of change before the region (254, 264) and is controlled to a second rate of change via a ramp or filter function through the region (254, 264), the second rate of change being slower than the first rate of change.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of US Provisional Application No. 61 / 643,612, filed May 7, 2012, the disclosure of which is hereby incorporated in its entirety. TECHNICAL FIELD

[0002] Various embodiments relate to a hybrid vehicle and a method for controlling powertrain response to a clearance for the vehicle. STATE OF THE ART

[0003] In a vehicle, backlash can occur in the driveline when wheel torque, road load torque, and prime mover torque reverse direction. The driveline may include a transmission gear system, driveline joints, and wheels. Lash or backlash, for example, can occur due to backlash caused by play or clearance within different driveline components when torque reverses direction, such as during a vehicle acceleration or deceleration event. Ignoring the effects of backlash results in driver disturbance.

[0004] In a conventional vehicle, a slow ramp in engine torque may be used when traversing the lash range. Other methods of reducing lash may also be used, including spark retardation within the engine, which can result in reduced fuel efficiency and increased torque load or vibration within the engine, contributing to noise, vibration, and harshness (NVH). In a hybrid vehicle, controlling lash range traversal in the powertrain becomes more complex because there may be more than one main drive delivering torque to a single powertrain input shaft. Controlling lash range traversal in a hybrid vehicle is also more complex because the powertrain may be in a driving configuration to propel the vehicle or in a driven configuration to charge the battery and / or brake.Detecting or predicting operating conditions or areas where driveline play is likely to occur can be used to mitigate the impact on passing through the play range. Prior art in this area is described in documents DE 101 47 313 A1, US 2008 / 0 257 619 A1, and WO 2011 / 108 066 A1. SUMMARY

[0005] In one embodiment, a method for controlling a vehicle having a traction motor is provided. The torque of the traction motor is controlled by a range surrounding a wheel torque reversal of the vehicle. The driveline input torque is controlled during torque reversal of the driveline output torque to limit the rate of change of the output torque. The torque of the traction motor is controlled during torque reversal of at least one driveline component to limit the rate of change of the torque applied to the driveline component.

[0006] In another embodiment, a hybrid electric vehicle is provided with a traction motor, a driveline connected to a vehicle wheel, and a controller. The controller is configured to control the torque of the traction motor through a range surrounding the torque reversal of the vehicle wheel, control the driveline input torque during torque reversal of the driveline output torque to limit the rate of change of the driveline output torque, and control the torque of the traction motor during torque reversal of at least one driveline component to limit the rate of change of the torque applied to the driveline component.

[0007] In yet another embodiment, a control system for a hybrid vehicle is provided with a traction motor and a controller. The controller is configured to control the torque of the traction motor through a range surrounding the wheel torque reversal of the vehicle and to control the torque of the traction motor during torque reversal of at least one driveline component to limit the rate of change of torque applied to the driveline component.

[0008] Various embodiments according to the present disclosure therefore enable control of dead play in a powertrain through the lash range during a vehicle acceleration or deceleration event, such as an accelerator pedal application or accelerator pedal release event. The engine and / or electric machine are controlled depending on the vehicle operating mode and whether the input torque to the transmission is positive or negative. For electric-only operation of the vehicle, the torque output of the electric machine is controlled through the lash range via a ramp or filter function. For hybrid operation of the vehicle, the engine output torque is held constant through the lash range, while the electric machine output torque is controlled using a ramp or filter function. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic representation of a hybrid vehicle capable of implementing an embodiment, Fig. 2 is a graph illustrating an example of dead play occurring in a drive train, Fig. 3 is a diagram illustrating a model for detecting a play area for a vehicle, Fig. 4 is a flowchart illustrating a process for determining a play area according to an embodiment, The Fig. 5a and Fig. 5b are timing diagrams illustrating an accelerator pedal application event and an accelerator pedal release event for a vehicle without dead-play passage control. The Fig. 6a and Fig. 6b are timing diagrams illustrating an accelerator pedal application event and an accelerator pedal release event for a vehicle in electric-only operation with dead-play control. The Fig. 7a and Fig. 7b are timing diagrams illustrating an accelerator pedal application event and an accelerator pedal release event for a vehicle operating in hybrid mode with dead-play control, and Fig. Figure 8 is a flowchart illustrating a method for controlling the effect of passage through dead play in a vehicle. DETAILED DESCRIPTION

[0009] As required, detailed embodiments of the present invention are disclosed herein. It is to be understood, however, that the disclosed embodiments are merely examples of the invention and may be embodied in various and alternative forms. The figures are not necessarily to scale; certain features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed herein are therefore not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously practice the present invention.

[0010] Fig. Figure 1 shows a schematic view of a hybrid vehicle 10 according to one embodiment. The vehicle 10 includes an engine 12 and an electric machine, which in the embodiment shown in Fig. 1, is a motor-generator (M / G) 14 and may alternatively be a traction motor. The M / G 14 is configured to transmit torque to the engine 12 or to the vehicle wheels 16.

[0011] The M / G 14 is connected to the engine 12 using a first clutch 18, also known as a breakaway clutch or upstream clutch. A second clutch 22, also known as a launch clutch or downstream clutch, connects the M / G 14 to a transmission 24, and all input torque to the transmission 24 passes through the launch clutch 22. Although the clutches 18, 22 are described and illustrated as hydraulic clutches, other types of clutches, such as electromechanical clutches, may be used. Alternatively, the clutch 22 may be replaced with a torque converter having a bypass clutch, as described further below. In various embodiments, the downstream clutch 22 refers to various clutch devices for the vehicle 10, including a conventional clutch and a torque converter having a bypass clutch.This configuration can use an otherwise conventional automatic transmission with a torque converter and is sometimes referred to as a modular hybrid powertrain configuration.

[0012] The output shaft of the engine 12 is connected to the disconnect clutch 18, which in turn is connected to the input shaft of the M / G 14. The output shaft of the M / G 14 is connected to the launch clutch 22, which in turn is connected to the transmission 24. The various components of the vehicle 10 are arranged sequentially in series with one another. The launch clutch 22 connects the vehicle's main drives to the driveline 26, which includes the transmission 24, a differential 28, and the vehicle wheels 16, as well as the connecting components. In other embodiments, the method described herein may be applied to hybrid vehicles having different system architectures.

[0013] In another embodiment of the vehicle 10, the downstream clutch 22 is a bypass clutch with a torque converter. The input of the M / G 14 is the impeller side of the torque converter, and the output of the torque converter to the powertrain 24 is the turbine side. The torque converter 22 transmits torque using its fluid coupling, and torque multiplication can occur depending on the degree of slippage between the impeller side and the turbine side. The bypass or lock-up clutch for the torque converter can be selectively engaged to create a mechanical or frictional connection between the impeller side and the turbine side for direct torque transfer. The bypass clutch can be slipped and / or opened to control the amount of torque transferred through the torque converter. The torque converter can also include a mechanical lock-up clutch.

[0014] In the vehicle 10, the launch clutch 22 or torque converter bypass clutch may be locked to increase fuel efficiency and may be locked when a lash range is passed through during an accelerator pedal application or accelerator pedal release event. Drivability and control of the effect of passing through the lash within the powertrain depend on controlling the powertrain torque from the engine 12 and / or the electric machine 14. The torque of the M / G 14 may be controlled with greater precision and faster response time than the torque of the engine 12. During all-electric operation of the vehicle 10, the torque of the M / G 14 may be controlled when a lash range is passed through.During a hybrid drive mode of the vehicle, in which both the engine 12 and the motor generator 14 are operating, the torque of the M / G 14 and the engine 12 may be controlled together to improve the drivability of the vehicle 10 and reduce the effect of going through the lash range in the driveline.

[0015] In the representative embodiment shown, the engine 12 is a direct injection engine. Alternatively, the engine 12 may be another type of engine or prime mover, such as a port fuel injection or fuel cell engine, or it may utilize different fuel sources, such as diesel, biofuel, natural gas, hydrogen, or the like. In certain embodiments, the vehicle 10 also includes a starter motor 30 operatively connected to the engine 12, for example, via a belt or gear drive. The starter motor 30 may be used to provide torque to crank the engine 12 without adding torque from the M / G 14, such as during a cold start or certain high-speed cranking operations.

[0016] The M / G 14 is connected to a battery 32. The battery 32 may be a high-voltage battery. The M / G 14 may be configured to charge the battery 32 in a regeneration mode through regenerative braking or the like, for example, when the vehicle's power output exceeds the driver's demand. The M / G 14 may also be placed in a generator configuration to moderate the amount of torque of the engine 12 delivered to the powertrain 26. In one example, the battery 32 is configured to be connected to an external electrical grid, such as a plug-in hybrid electric vehicle (PHEV), with the capability of charging the battery via an electrical grid that supplies power to an electrical outlet at a charging station.A low voltage battery may also be present to supply power to the starter motor or other components of the vehicle, or low voltage power may be supplied by a DC-DC converter connected to the battery 32.

[0017] In certain embodiments, the transmission 24 is an automatic transmission and is connected to the drive wheels 16 in a conventional manner, and it may include a differential 28. The vehicle 10 is also provided with a pair of non-driven wheels, but in alternative embodiments, a transfer case and a second differential may be used to positively drive all wheels of the vehicle.

[0018] The M / G 14 and clutches 18, 22 may be located within a motor-generator housing 34 that may be incorporated into the housing of the transmission 24, or, alternatively, in a separate housing within the vehicle 10. The transmission 24 includes a manual transmission to provide different gear ratios for the vehicle 10. The manual transmission of the transmission 24 may include clutches and planetary gears or other arrangements of clutches and gear trains known in the art. In alternative embodiments, the transmission 24 is a continuously variable ratio transmission or an automated mechanical transmission. The transmission 24 may be a 6-speed automatic transmission, an automatic transmission with other gears, or other manual transmission as known in the art.

[0019] The transmission 24 is controlled using a transmission control unit (TCU) 36 or the like to operate on a gear shift scheme, such as a production shift scheme, that connects and disconnects elements within the manual transmission to control the gear ratio between the transmission output and the transmission input. The gear ratio of the transmission 24 is the ideal torque ratio of the transmission 24. The TCU 36 also functions to control the M / G 14, the clutches 18, 22, and all other components within the motor-generator housing 34.

[0020] An engine control unit (ECU) 38 is configured to control the operation of the engine 12. A vehicle system controller (VSC) 40 communicates data between the TCU 36 and the ECU 38 and is also connected to various vehicle sensors. The control system 42 for the vehicle 10 may include any number of controllers and may be integrated into a single controller or include multiple modules. Some or all of the controllers may be connected by a controller area network (CAN) or other system.The control system 42 may be configured to control the operation of the various components of the transmission 24, the motor-generator assembly 34, the starter motor 30, and the engine 12 under any number of different conditions, including in a manner that reduces the effect of lash running in the powertrain 26 and the impact on the driver during accelerator pedal application or release events.

[0021] Under normal powertrain conditions (no faulty subsystems / components), the VSC 40 analyzes the driver's request (such as park, reverse, neutral, drive (PRND), and acceleration or deceleration requests) and then determines the wheel torque control command based on the driver request and the powertrain limits. In addition, the VSC 40 determines when and how much torque each power source must deliver to meet the driver's torque request and achieve the operating points (torque and speed) of the motor 12 and the M / G 14.

[0022] The vehicle 10 may have speed sensors 44 positioned at various locations on the propulsion system and driveline 26. The speed sensors 44 provide data regarding the speed of a shaft to the control system 42 in approximately real time, although some delay may occur due to response time and signal and data processing. In one embodiment, Fig. 1, there is a speed sensor 44 which measures the speed of the output shaft of the engine 12, the speed of the shaft connected to the M / G 14, the speed of the input shaft of the transmission 24, the speed of the output shaft of the transmission 24 and the speed of one or both axles connected to the wheels 16.

[0023] As part of the control strategy or algorithm for operating the vehicle 10, the control system 42 may provide a torque request to the engine 12 (τ e) and / or a torque request to the M / G 14 (τ m ) as in Fig. 1. The effective torque at the gearbox (τ i ) consists of the torque of the electric motor and the torque of the motor (τ i = τ m +τ e ), provided that the release clutch and starting clutch 18, 22 are locked.

[0024] In alternative embodiments, clutch 22 may be replaced by a torque converter unit including a torque converter and a lock-up or bypass clutch. The torque converter has torque multiplying effects when certain speed differentials exist across the torque converter. During torque multiplying, the torque converter output torque is greater than the input torque due to the torque multiplying across the torque converter. Torque multiplying exists, for example, when vehicle 10 is started from rest and the input shaft leading to the torque converter begins to rotate and the output shaft leading from the torque converter is still stationary or has just begun rotating.

[0025] The lock-up clutch or bypass clutch is used to lock out the torque converter so that the input and output torque to the downstream torque-transmitting device 22 are equal and the input and output speeds to the device 22 are equal. A locked clutch eliminates slippage and driveline inefficiency across the torque converter, for example, when the speed ratio across the torque converter is greater than about 0.8, and can increase fuel efficiency for the vehicle 10.

[0026] Changing torque amounts and / or torque directions can cause disturbances or vibration in the driveline 26 associated with the passage of backlash. Dead play can occur in the driveline 26 of a vehicle whenever the torque from one of the wheels 16 and the torque from the powerplants 12, 14 change their respective directions. This change in torque direction can occur when the vehicle 10 is operating with both the release clutch 18 and the launch clutch 22 or with the torque converter lock-up clutch in a locked or engaged position. For example, when the vehicle 10 decelerates, the engine braking of the engine 12 delivers negative torque to the transmission 24, which is then transmitted through the differential 28 and then to the wheels 16. At this point, the driveline 26 is twisted in the negative direction.When a power request or throttle input is made by the driver using the accelerator pedal, the torque of the engine 12 transitions from negative to positive as it begins delivering torque to propel the vehicle 10 forward. The driveline 26 spins apart as each component of the driveline transitions from transmitting negative torque to transmitting positive torque. At some point during this transition, the driveline 26 passes through a relaxed state where zero torque is applied to the wheels 16.

[0027] During this zero torque range, the gears in the transmission 24 and / or the differential 26 may not be firmly engaged with their corresponding gear teeth, and therefore, some backlash may exist in the driveline 26. Backlash across multiple gears accumulates. While the engine 12 continues to provide positive torque, the driveline 26 twists in the positive direction. The gears may quickly become coupled, resulting in a thump. The axle connecting the differential 26 to a wheel 16 may also twist slightly as a result of the higher torque on the differential side of the axle compared to the wheel 16 side. The axle may act as a torsion spring to store this energy.As the vehicle 10 begins to accelerate, the torque at wheel 16 equalizes to the torque at the differential 26, and the energy stored in the axle is quickly released, causing oscillation in the opposite direction, or deadplay. The result of going through deadplay is a thump or noise as the gear teeth collide and a reduction in wheel torque as the axle's energy is released. The thumps and vibrations may be noticeable to the driver depending on their severity. In a driveline with multiple gear meshes arranged in series, each gear tooth may have a lash region. The reaction in the driveline cascades, or propagates through the gear teeth. After one gear tooth engages, the subsequent gear tooth passes through a lash region as torque reversal occurs.The dead play can include the reaction of the main gear teeth as well as the subsequent gear teeth.

[0028] The sequence described above can also occur in the opposite direction. In this case, the driver would provide a power request, such as pressing the accelerator pedal to accelerate the vehicle, and then quickly discontinue the power request by releasing the accelerator pedal through a throttle release. The powertrain 26 transitions from twisting in the positive direction to twisting in the negative direction, experiencing a similar torque drop or torque hole and a similar thud during the transition. The effect of going through the dead play during sudden acceleration is typically more noticeable than during sudden deceleration.

[0029] Two conditions for the occurrence of a dead game are in Fig. 2 is shown graphically for vehicle 10 as an example. The accelerator pedal 60, transmission output speed 62, wheel speed 64, and wheel torque 66 are shown during a sudden deceleration at location 68 and during an acceleration at location 70. Following the deceleration request at location 68, transmission output speed 62 decreases faster than wheel speed 64. This results in the region 72 labeled "zero wheel torque," in which driveline 26 is in its relaxed state while wheel torque 66 undergoes a positive-to-negative transition. Immediately following this transition, wheel torque 66 decreases rapidly as wheel speed 64 catches up with transmission output speed 62, resulting in the region 74 labeled "torque drop."This torque drop 74 is essentially dead play and is caused by the release of energy stored in the halfshaft and by the backlash in the transmission 24 and other driveline components, in addition to the negative torque delivered by the transmission output. The effect of passing through the dead play 74 causes a resulting oscillation in the wheel torque.

[0030] During acceleration following the accelerator pedal request at location 70, a similar sequence occurs, only in the reverse direction. The increase in transmission output speed 62 results in an increase in wheel speed 64, leading to a region 76 of zero torque and then a rapid torque increase or "torque spike" at location 78, causing a dead-play effect, or noise and vibration, that the driver may notice.

[0031] The control system 42 is configured to detect, sense, and / or predict the lash range to reduce or mitigate the impact of passing through the deadplay. The deadplay in the vehicle 10 may be sensed by monitoring the ratio of transmission input and output torque as described below. In other embodiments, the deadplay may also be sensed using speed sensors or other techniques known in the art.

[0032] Fig. Figure 3 shows the relationship of input torque to output torque across the transmission 24. An ideal or perfect transmission 24 has a perfect torque ratio, as represented by line 100 passing through zero. However, in a real transmission 24, there are proportional and non-proportional losses that must be taken into account. The losses cause the ideal torque ratio to shift to an actual ratio of output torque to input torque. The actual torque ratio is the ideal torque ratio with the addition of losses. When the input and output torques are both negative (generating), the transmission losses provide assistance in slowing the vehicle. When the input torque and output torque are positive (driving), the losses inhibit drive performance.Line 118 represents the actual ratio during drive, taking losses into account. Line 120 represents the actual ratio during generation, taking losses into account. Line 122 is the range of ratios in which the gearbox 24 carries a torque close to zero and in which the potential for the occurrence of the backlash effect is highest, and line 122 represents the backlash range.

[0033] Region 124 represents the input region for the backlash region from the drive side, or positive input torque side. Region 126 represents the input region for the backlash from the generation side, or negative input torque side. It can be seen that line 122 between regions 124 and 126 is bounded by a zero input torque (at 126) and a scalar input torque (at 124). In other embodiments, other boundaries may be set to define the backlash region. By controlling the input torque when the vehicle 10 is operating on line 122 as the vehicle accelerates or decelerates along it, the effects of the backlash event can be reduced or mitigated. Line 122 may be linear or non-linear.For example, line 122 may be a step function with multiple steps caused by the backlash in each gear in the drive train.

[0034] The input and output torque model for a gear ratio as shown in Fig. 3, can be determined as described below. During acceleration events, the powertrain is in a driving configuration such that torque is transferred from the engine and / or the M / G 14 through the transmission 24 to the wheels 16. During deceleration events, the powertrain is in a driven configuration such that torque is transferred from the wheels 16 through the transmission 24 to the M / G 14. However, the amount of torque transferred via the transmission 24 and the powertrain 26 depends on the gear ratio and losses in the transmission 24 and the powertrain 26. Fig. 3 graphically illustrates the torque, gear ratio and losses of the gearbox 24. The gear ratio of the gearbox 24 is equal to a ratio of the incoming torque (τ in ) and the outgoing torque (τ out ), where τ in the torque at the input shaft 46 to the gearbox 24 and τ out is the torque at the output shaft 48 of the gearbox 24, and where there are no losses in the system. The gear ratio can be based on a speed ratio and calculated directly from the number of teeth of the various gears meshing in the gearbox 24. The gear ratio can be considered an ideal gear ratio. For example, if the gear ratio is 4:1 for an input torque (τ in ) of +100 Nm (Newton-meter), the output torque (τ out ) 400 Nm. The ideal torque ratio is therefore from line 100 in Fig. 3, where the slope of the line is the ideal torque ratio or gear ratio.

[0035] A linear relationship can be used to create the relationship between torque input and torque output in a gearbox, where the linear line can be described by the following formula: y=m*x+b where y is the output torque (τ out ) and x is the input torque (τ in ). The slope m is the output / input torque ratio or gear ratio, and b is the output torque when the input torque is zero.

[0036] Ideally, or in a gearbox 24 without losses, the pitch would be the ideal torque ratio and the offset is zero, as shown by line 100. The pitch without losses is the ideal torque ratio or gear ratio (TR ideal) . The formula for line 100 is therefore: τout=(τin*TRideal)

[0037] However, the transmission 24 is not completely efficient and exhibits some losses. Losses in the transmission can depend on friction, heat, rotational losses, or many other factors. Losses in the transmission can be characterized as "proportional losses" and "non-proportional losses." The "proportional losses" vary depending on the current gear and speed, while the "non-proportional losses" are independent of torque. The efficiency of a transmission 24 is usually measured via the transmission 24. The efficiency of the driveline 26 is typically measured with the launch clutch 22 or the torque converter bypass clutch locked, or it can be modeled without a torque converter.

[0038] The section b is equal to the non-proportional loss, Ts , which in Fig. 2 at point 112 for each gear of a transmission. Line 114 illustrates the ideal torque ratio or transmission ratio when non-proportional losses T s in the gearbox 24. Non-proportional losses T s may be specified in units of output torque. The non-proportional losses or rotational losses in the driveline may depend on the driveline output speed, the driveline oil temperature, and the gear the driveline is in. The driveline output speed may depend on the driveline input speed and a driveline gear ratio. The formula for line 114 is therefore: τout=(τin*TRideal)−Ts

[0039] Proportional power transmission losses should also be considered in the model. The current torque ratio of the gearbox 24 of τ out to τ incan be measured empirically in various gears. Empirical modeling of the transmission 24 without the torque converter 22 (locked or not included) allows the representation of the "torque proportional" losses separately from the "non-torque proportional" losses, which can be represented using a linear relationship between output torque and input torque. Proportional losses can depend on the driveline oil temperature, the gear the driveline is in, and the input torque at the driveline. Proportional losses are represented by the slope of the output-to-input torque ratio for each gear. The slope, including the proportional losses, is equal to the actual torque ratio across the transmission 24.

[0040] Knowing the ideal torque ratio or gear ratio and the ratio between input and output torque, and measuring only a few points of the actual ratios of input and output torque, the difference between the slopes of the ideal torque ratio (TRi deal ) and the actual torque ratio (TR actual ) can be determined. By subtracting the part of τ in , which results from the difference between the slopes of the ideal torque ratio and the actual torque ratio, one can determine the proportional torque losses. Non-proportional losses are determined by T s The linear formula for the power transmission taking into account proportional and non-proportional losses, as shown as line 116 in Fig. 2 could be written as follows: τout=(τin*TRideal)−Ts−τin*(TRideal−TRactual)

[0041] By solving the terms on the right side of the loss equation, the formula for line 116 can be written as Fig. 3 can be simplified as follows: τout=(τin*TRactual)−Ts

[0042] For example, for an input torque of +100 Nm, an actual torque ratio of 4.0, an ideal torque ratio of 4.1 and a non-proportional loss of 5 τ out as described below. Please note that the numbers in the example are truncated for simplicity.

[0043] First, using equation (3A), the output torque is calculated as: τout=(100*4.1)−5−(100*(4.1−4.0))=395 Nm

[0044] Using equation (3B), the output torque is calculated as: τout=(100*4.0)−5=395 Nm

[0045] The power can be determined by multiplying the torque by the speed of the shafts 46, 48, as illustrated by the following equation: P=τ*ω

[0046] With an input speed of 400 rad / s, the power calculations can be carried out. Pin=100*400=40,000 watts Pout=395*(400 / 4.1)=38,536 watts

[0047] The difference between the power at the transmission input 46 and the transmission output 48 is the amount of power lost due to transmission inefficiencies Pin−Pout=1.464 watts

[0048] The loss formulas in Equation (3) can generally accurately describe the transmission, including losses, in a conventional powertrain. The loss formulas in Equation (3) can also accurately describe the transmission, including losses, in an HEV powertrain when the vehicle 10 is moving. However, a problem can arise when the vehicle 10 is inputting power to the transmission output 62 and receiving it from the transmission input 60, such as during regenerative powertrain braking in an HEV. In this situation, the torque values ​​through the powertrain 26 are negative, the powertrain is in a driven configuration, and the loss formulas in Equation (3) must be applied differently.

[0049] The problem with the loss formulas in equation (3) during regenerative powertrain braking can be illustrated by another example. For negative torques, where the input torque τin -100 Nm, the current ratio is 4.0, the ideal ratio is 4.1 and non-proportional losses (T s ) 5, τ out calculated as: t out = (-100 * 4.1) - 5 - (100 * (4.1 - 4.0)) = -405 Nm, using equation (3A) or t out = (-100* 4.0) - 5 = -405 Nm, using equation (3B).

[0050] With an input speed of 400 rad / s, the power calculations can be done as: Pin=−100*400=−40,000 watts Pout=−405*(400 / 4.1)=−39,512 watts Pin−Pout=Ploss=−488 watts

[0051] Using standard formulas results in a negative loss calculation, which is not possible because the power input to the output shaft 48 of the transmission 24 is less than the power output from the transmission input shaft 46. In this example, 40,000 watts of regenerative power are tapped at the transmission input 46, but only 39,512 watts of regenerative power are fed from the wheels 16 to the transmission output 48.

[0052] For modeling the torque ratio, two lines fit the data better than one. The first line, designated as line 118 in Fig. 3 represents the positive output and input torque τ out or τ in , for example, if the vehicle is traveling 10. The second line, which is Fig. 2 as line 120 represents a negative output and input torque, as when the vehicle 10 is braking regeneratively.

[0053] The non-proportional losses 112 are calculated during driving in the same way as during regeneration. Therefore, lines 118 and 120 both contain the same offset term b for non-proportional torque loss T s However, during regeneration, the proportional losses are not properly taken into account when using the standard driving equations.

[0054] The correct τ in for a given τ out -value is only calculated correctly if the proportional torque losses are summed in the correct direction. The term for proportional loss in equation (3A), i.e. τ in * (TRi deal - TR actual ), must be a positive value, regardless of whether the gearbox transmits positive or negative torque. Since τ inis negative during regeneration and the proportional loss term in equation (3A) must be positive, the ideal torque ratio must be less than the actual torque ratio during regeneration to provide the correct calculation that more energy goes into the transmission output 48 than is received at the transmission input 46 during the negative torque transfer.

[0055] For example, during a negative torque transmission where the transmission input torque τ in -100 Nm, the current torque ratio is 4.2, the ideal torque ratio, which is smaller than the current ratio, is 4.1 and the non-proportional losses T s 5 are, τ out be determined as: t out = (-100 * 4.1) - 5 - (-100 * (4.1 - 4.2)) = -425 Nm, using equation (3A), or t out= (-100 * 4.2) - 5 = -425 Nm, using equation (3B). Note that the previous loss of -405 has approximately a five percent error.

[0056] Using an input speed of 400 rad / s, the power can be calculated as follows: Pin=−100*400=−40,000 watts Pout=−425*(400 / 4.1)=−41,463 watts Pin−Pout=Ploss=1463 watts

[0057] When the output torque and the input torque are both positive, the actual measured gradient is less than the ideal torque ratio, as can be seen by comparing line 118 with line 114. However, when the output torque and the input torque are both negative, the actual measured gradient or TR actual greater than the mechanical torque ratio or TR ideal,as can be seen by comparing line 120 with line 114. The actual torque ratio for a negative torque condition is determined by measurement to be 4.2. Using the measured positive torque ratio of 4.0 for the negative torque situation, equation (3) calculates that more energy is being extracted at the transmission input 60 than is being input to the transmission output 62 during regeneration (as shown by comparing line 116 with line 114).

[0058] To take into account the difference between the actual torque ratio and the ideal torque ratio (or gear ratio), a coefficient C1 for proportional losses is calculated for each gear using the following formula: C1=τin*(TRideal−TRactual)

[0059] During driving / travel or positive torque through the gearbox 24, the coefficient C1 for proportional losses is added to equation (3B) to obtain the following loss equation: τout=(τin*(TRactual−C1))−Ts

[0060] Or alternatively, equation (5) can be rearranged to find τ in based on a desired torque output value τ out while driving as: τin=(τout+Ts) / (TRideal−C1)

[0061] When the torque through the transmission 24 is negative, such as during a regenerative braking event, the actual torque ratio is greater than the ideal torque ratio (or gear ratio) by the same amount as the ideal torque ratio is greater than the actual torque ratio during driving. Therefore, the sign of C1 changes during regenerative braking, but the absolute value of C1 remains the same. Therefore, τ in based on a desired torque output value τ out during negative torque transmission through the transmission: τin=(τout+Ts) / (TRideal−C1)

[0062] The input torque to output torque ratio for transmission 24 is therefore better represented by lines 118, 102 to distinguish between driving and regeneration or positive and negative torque. Line 120 in Fig. Figure 3 illustrates the line that accounts for the proportional losses contributing to regenerative braking. Line 120 can be characterized by rearranging equation (7) as follows: τout=(τin*(TRideal+C1))−Ts

[0063] Considering a torque converter, pumping losses, and dynamic inertia losses can be consistent throughout the transmission control system development process. For example, if the vehicle has a torque converter 22, the torque input value τ in when the vehicle is moving, can be determined as: τin=((τout+Ts) / (TRideal−C1))*(1 / TRtorque_converter)+Losspump+Lossdyn_inertia

[0064] When the M / G 14 is generating power or when the vehicle is regeneratively braking so that the transmission output torque is negative, equation (9) is changed so that the torque input value τ incan be determined from the following equation: τin=((τout+Ts) / (TRideal+C1))*(1 / TRtorque_converter)Losspump+Lossdyn_inertia

[0065] The torque converter 56 can be connected between the M / G 14 and the transmission 24. The torque converter 56 can also be included in the transmission 24. When the torque converter 56 is locked, the torque ratio of the torque converter is 1:1.

[0066] The control system 42 is configured to determine a lash range for the vehicle based on the gear of the transmission and to use the determined lash range during operation of the vehicle to predict or detect an impending lash range, which in turn can be used in a control strategy to mitigate the effect of the lash passing through the driveline.

[0067] The controller 42 first receives a vehicle torque request at 150, such as a torque request from the driver through an accelerator pedal application event or accelerator pedal release event. The vehicle torque request is a request for wheel torque, which is expressed as τ out The control device converts τ out based on the ideal torque ratio of the power transmission 24 in τ in as represented by block 152.

[0068] The controller 42 determines the value for the current gear or, alternatively, the current torque ratio, as represented by block 156. The current torque ratio may be stored in a mapping table corresponding to the current gear or whether the vehicle is cruising or undergoing regenerative powertrain braking, as described above.

[0069] The current torque ratio, along with the transmission gears, which are either estimated or actual gears, is used to determine the non-proportional loss, as represented by block 154. The non-proportional loss values ​​may be stored in a lookup table corresponding to the current gear and accessed or indexed by transmission gears when later calculating the current torque ratio 156, as described above.

[0070] The controller 42 determines the proportional torque loss as determined by block 158 of the Fig. 4. The proportional loss values, as well as negative torque values ​​or positive torque values, can be stored in a mapping table with a separate set of values ​​for each of the available gears or each of the available torque ratios.

[0071] Block 160 represents the determination of the proportional loss coefficient based on the currently selected gear. This factor can be used to fine-tune or calibrate the torque determination for any additional losses not included in the torque loss terms described above.

[0072] The controller 42 then determines at 162 whether torque is applied in a positive or negative direction across the transmission and driveline, that is, whether the vehicle is cruising or generating / braking, or whether the driveline is in a drive configuration or a driven configuration. If the vehicle 10 is cruising with the driveline in a drive configuration or has positive torque flowing from the engine 12 and / or the M / G 14 to the wheels 16, the controller 42 proceeds to 164 to determine τ inusing equation (6). The entry point into the game area is determined at block 166 by calculating τ in calculated if τ out is zero or another specified value.

[0073] When the vehicle 10 is generating / braking with the powertrain in a driven configuration or has torque flowing from wheels 16 to the engine 12 and / or the M / G 14, the controller 42 proceeds to 168 to determine τ in using equation (8). The entry point into the game area is determined at block 170 by calculating τ out (or the torque input value to the driveline or transmission) when τ in is zero or another specified value.

[0074] The entry points in the game area from 166 and 170 are used at block 172 to provide the control system 42 with a game area for use in a control algorithm for passing the dead game.

[0075] The control of passing through the play range can be handled differently by a control algorithm based on whether the engine 12 is stopped, so that the vehicle 10 operates exclusively in electric mode, or whether the engine 12 is running, so that the vehicle operates in a hybrid mode in which the M / G 14 is also operating. In the case where the engine is not running, the only drive is the M / G 14, so that the transmission net input torque τ in , is equal to the engine torque of the M / G 14. In the case where the combustion engine is in operation, there are two drives acting on the input shaft of the gearbox, so that the gearbox net input τ inis equal to the torque of the M / G 14 plus the torque of the combustion engine 12. Therefore, only the engine torque of the M / G 14 14 is controlled in the electric drive, whereas in a hybrid drive both the engine torque of the M / G 14 and the torque of the combustion engine are controlled and mixed.

[0076] The M / G 14 may provide better control of the clearance range than the internal combustion engine 12. The improved control is clearly evident during deceleration because the internal combustion engine 12 is typically controlled using spark retard or a similar technique. The M / G 14 generally performs well at zero torque and / or at an engine speed at or near zero. The M / G 14 has a faster response time than the internal combustion engine 12, which may lag due to throttle response or the like. Additionally, the M / G 14 may have more precise control of the amount of torque it delivers compared to the internal combustion engine 12.

[0077] Fig. Figure 5 illustrates an example of input torque and output torque during a lash event without any control implemented to mitigate any lash defect. In the case of the accelerator pedal application in Fig. 5a, an accelerator pedal command is shown at 200. The input and output torques 202, 204 transition from a negative value, i.e., boost, regeneration, or cruising, to a positive value with propulsion or drive. As the net input torque 202 passes through the lash range 206 from R1 to R2, the gears in the transmission and driveline are not meshed, and the torque at the output does not exhibit a linear increase, as shown at 208. When R2 is reached at the end of the lash range 206, the gears suddenly mesh, causing a sudden increase in output torque at 210. The sudden increase winds up the driveline like a spring, and then the spring energy is released, causing a resultant oscillation at 212.

[0078] A similar phenomenon occurs during the case of accelerator pedal release, which is Fig. 5b without lash control. During accelerator release, as shown by an accelerator release command in line 214, the input torque and output torque 216, 218 transition from positive, i.e., drive or cruising, to negative, i.e., boost or regeneration. As the net input torque 216 passes through the lash range 220 from R1 to R2, the gears in the transmission and driveline are disengaged. When R2 is reached at the end of the lash range 220, the gears suddenly mesh, causing a sudden drop in output torque at 222. The sudden drop pulls the driveline like a spring into the Fig. 5a in the opposite direction, and then the spring energy is released, causing a resulting oscillation at 224.

[0079] Fig. Figure 6 shows a game pass event while the combustion engine 12 is out of operation, while the torque control of the engine 14 is used to control the game event in the case of an accelerator pedal operation in Fig. 6a and the accelerator pedal release in Fig. 6b. The net input torque to the transmission 24 is equal to the torque of the engine 14 because the internal combustion engine 12 is inoperative. The internal combustion engine 12 can be disconnected by opening the disconnect clutch 18. During the accelerator pedal application event at 250 in Fig. 6a, engine torque 252 increases rapidly as the driver demand increases until the input torque point R1 is reached. From R1 to R2, within the clearance range 254, engine torque 252 is slowly increased according to a ramp or filter function until the net input torque R2 is reached. Although engine torque 252 is shown as a line along 254, engine torque 252 can be modulated according to any desired profile, and in one embodiment, it is provided by a two-dimensional map with vehicle-adapted response.

[0080] After the lash region 254, normal torque control resumes, with a fast ramp or filter to quickly ramp the torque 252 up to the driver demand. By controlling the ramp or load in the input torque 252 through the lash region 254, the transmission 24 is guided through its non-engaged state, which slowly engages the gear teeth in one or more meshes from the non-engaged state so that, as shown by the output torque 256, little or no slap occurs. Once the gear teeth effectively mesh in R2, more engine torque 252 can be applied without a harsh event and the resulting harsh vibration.

[0081] A similar type of control for passing through a game area occurs in the case of accelerator pedal release in Fig. 6b Use. Following an accelerator release event at 260, engine torque 262 is rapidly reduced to match the driver request or charge / regeneration request until point R2 is reached. From R2 to R1 within lash range 264, torque 262 is controlled according to a slow ramp or filter function until point R1 is reached. Engine torque 262 may be controlled according to any profile through lash range 264. In one embodiment, engine torque 262 is rapidly reduced by a large amount before lash range 264 and is reduced by a much smaller amount throughout the lash range to control and reduce lash in the driveline. At point R1, the teeth of the gears effectively mesh, and more engine torque 262 can be applied in the negative direction without a harsh event or oscillation, as evidenced by the smooth output torque 266.

[0082] Fig. Figure 7 illustrates a lash-through event while the engine 12 is operating and the vehicle 10 is operating in a hybrid mode. In this case, the net input torque is equal to the torque of the motor 14 plus the torque of the engine 12. It is therefore necessary to control both the torque of the motor 14 and the torque of the engine 12 to mitigate a lash-through event. Because the M / G 14 has faster response time and more precise control over the torque provided, the torque of the M / G 14 generally leads through the lash range and the torque of the engine 12 is generally held. The torque of the engine 12 is controlled to a constant or primarily constant value while the torque of the motor 14 is modulated to achieve the desired effect on the transmission net input torque.In the clearance range from R1 to R2, the engine torque response precedes the machine torque response in both the case of accelerator pedal application and the case of accelerator pedal release.

[0083] During the accelerator pedal operation event at 300, which is in Fig. 7a, engine torque 302 increases rapidly as the driver demand increases until the input torque point R1 for net input torque 304 is reached. Engine torque 302 is typically increased rapidly to meet the driver demand and precedes any throttle-triggered increase in engine torque response, which is called "torque transient fill." From R1 to R2 within lash range 306, engine torque 308 is controlled to be generally constant, and engine torque 302 is slowly increased according to a ramp or filter function to control torque through the lash range until net input torque R2 is reached and the gear teeth smoothly mesh effectively.Of course, motor torque 302 can be controlled according to any profile to match engine torque 308 and control the torque through lash range 306. After lash range 306, normal torque control resumes, with engine torque 304 rising smoothly until the driver requests it. Note that output torque 310 has no noticeable dead play.

[0084] During an accelerator pedal release event 350, which is Fig. 7b, engine torque 352 is rapidly reduced to meet the driver's request until input torque point R2 is reached. From R2 to R1 within lash range 354, engine torque 352 is held constant at a nominal or other value greater than zero. Motor torque 356 is controlled through lash range 354 according to a slow ramp, filter function, or other profile until point R1 is reached. Input torque 358 is the sum of engine torque 352 and motor torque 354. At point R1, the gear teeth smoothly mesh, and more drive torque can be applied from the motor and / or engine in the negative direction without a harsh event or oscillation, as shown by output torque 360. Engine torque 352 is allowed to drop to an idle value.

[0085] The control algorithm of the game area passage is in Fig. 8 is shown in the form of a flowchart. The left part of the flowchart generally shows the operation in the case of increasing driver demand or in the case of accelerator pedal application conditions, and the right part of the flowchart generally shows the operation in the case of decreasing driver demand or in the case of accelerator pedal release conditions.

[0086] The controller 42 begins at block 400 and proceeds to block 402 where it determines whether the input torque τ inpositive or negative. If the input torque is positive, the controller 42 proceeds to 404 where it determines if the driver request is decreasing, such as through an accelerator pedal release event. If the driver request is decreasing at 404, the controller 42 monitors the transmission input torque compared to the lash range. When the transmission input torque enters the lash range at 406, the controller 42 determines at 408 whether the internal combustion engine 12 is operating and providing torque. If the internal combustion engine 12 is not operating, corresponding to all-electric operation of the vehicle, the controller 42 controls the reduction in torque of the motor 14 until the lash range is exited at 412.When the internal combustion engine 12 is operating at 408, which corresponds to hybrid operation of the vehicle, the controller 42 maintains the torque output of the internal combustion engine 12 constant or at a steady value at 410 and also controls the reduction of the torque of the motor 14 until the clearance range is exited at 412.

[0087] If the input torque is negative at 402, the controller 42 proceeds to 414 where it determines if the driver request is increasing, such as through an accelerator pedal application event. If the driver request is increasing at 414, the controller 42 monitors the transmission input torque compared to the lash range. If the transmission input torque enters the lash range at 416, the controller 42 determines at 418 whether the internal combustion engine 12 is operating and providing torque. If the internal combustion engine 12 is not operating, corresponding to all-electric operation of the vehicle, the controller 42 controls the increase in torque of the motor 14 until the lash range is exited at 422.When the internal combustion engine 12 is operating at 418, corresponding to hybrid operation of the vehicle, the controller 42 maintains the torque output of the internal combustion engine 12 constant or at a steady value at 420 and also controls the increase of the torque of the motor 14 until the clearance range is exited at 422.

[0088] Various embodiments according to the present disclosure provide control of the passage of dead play in a powertrain when passing through the lash range during a vehicle acceleration or deceleration event, such as for an accelerator pedal application or release event. The internal combustion engine and / or the electric motor are controlled depending on the vehicle operating mode and whether the input torque to the transmission is positive or negative. For electric-only operation of the vehicle, the torque output of the electric motor is controlled through the lash range according to a ramp or filter function or other profile.For hybrid vehicle operation, the engine output torque is generally held constant across the backlash range, while the electric motor output torque is controlled and modulated using a ramp, filter function, or other profile to reduce backlash response. Generally, the engine torque leads, while the engine torque is generally held constant across the backlash range to control the input torque and reduce backlash response.

[0089] Although exemplary embodiments have been described above, it is not intended that these embodiments describe all possible forms of the invention. The words used in the specification are words of description rather than limitation, and it is to be understood that various changes may be made without departing from the spirit and scope of the invention. In addition, the features of the various embodiments may be combined to form further embodiments of the invention.

Claims

[1] A method for controlling a vehicle (10) having a traction motor (12, 14), the method comprising: Controlling the torque of the traction motor (12, 14), which is an internal combustion engine (12) and / or an electric motor (14), by a region (254, 264) surrounding a wheel torque reversal of the vehicle (10), Controlling the driveline input torque during torque reversal of the driveline output torque (256, 266) to limit the rate of change of the output torque, and Controlling the torque (252, 262) of the traction motor (12, 14) during a torque reversal of at least one component of the driveline to limit the rate of change of the torque applied to the component of the driveline, in which the torque of the traction motor (12, 14) is controlled to a first rate of change before the region (254, 264) and is controlled to a second rate of change via a ramp or filter function through the region (254, 264), the second rate of change being slower than the first rate of change. [2] The method of claim 1, further comprising controlling the torque of the traction motor (12, 14) according to a profile through the region (254, 264). [3] A method according to any one of claims 1 to 2, in which the vehicle (10) has an internal combustion engine (12), the method further comprising: Controlling the engine torque through the region (254, 264) surrounding the wheel torque reversal of the vehicle (10) and Controlling the engine torque during torque reversal of the at least one component of the powertrain to control the rate of change of the torque, applied to the drivetrain component. [4] The method of claim 3, wherein the input torque is based on the torque of the traction motor (12, 14) and the torque of the internal combustion engine (12). [5] A method according to claim 3 or claim 4, in which the wheel torque reversal of the vehicle (10) is from negative to positive torque, and wherein the engine torque is maintained (420) at a generally constant value over the range (254, 264). [6] The method of claim 5, wherein the engine torque is increased after the region (254, 264). [7] The method of claim 3 or claim 4, wherein the wheel torque reversal of the vehicle (10) is from positive to negative torque, and wherein the engine torque is maintained (410) at a generally constant value over the range (254, 264). [8] The method of claim 7, wherein the engine torque is controlled to the first rate of change prior to the region (254, 264), thereby controlling the input torque through the region (254, 264).

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