COMBUSTION AND ELECTRIC MOTOR CONTROL DURING WHEEL TORQUE REVERSAL IN A HYBRID VEHICLE

Abstract

Vehicle (10), comprising: an internal combustion engine (12) which is selectively coupled to an electric machine (14) by means of an upstream clutch, which is selectively coupled to a stepped transmission (24) by means of a downstream clutch (22); and at least one controller (42) programmed to control the internal combustion engine (12) and the electric machine (14) in anticipation of a wheel torque reversal in response to entry into a play zone, in order to set a gain applied to an active damping torque controller (670) for an electric motor to reduce vibrations and dead weight in the drivetrain, wherein the at least one controller (42) reduces the gain in advance of a torque zero point where there is air between engaging gear teeth of drivetrain components.

Description

TECHNICAL AREA

[0001] This disclosure concerns the control of a hybrid vehicle during a wheel torque reversal. BACKGROUND

[0002] Drivetrain vibrations can occur in vehicles, disrupting smooth running and leading to less than ideal handling if not properly controlled. In hybrid electric vehicles (HEVs), it is often desirable to transition quickly from drive force at the wheels to regenerative braking force at the wheels. Similarly, the vehicle may transition from a high regenerative force to drive force when the driver depresses the accelerator pedal. Play or slack in the drivetrain can occur due to a loss of motion caused by air or clearance within or between various drivetrain components associated with the transmission gears, axle drive, drivetrain links, wheels, etc., when the direction of torque changes.During the transition from driving force to regenerative force, or vice versa, the drivetrain will pass through a torque zero point where there is play, or they are not in contact, between meshing gear teeth or other coupled components. This can cause snapping or vibration in the drivetrain if this region, sometimes called the backlash zone, is traversed too quickly.

[0003] German patent application DE 101 26 348 B4 discloses a method for controlling a vehicle, in particular for reducing the muffled noise caused by torque reversal in the drivetrain of a hybrid vehicle by controlling the torque in the vehicle's drivetrain, wherein the drivetrain comprises an internal combustion engine and an electric machine, which apply torque to a wheel axle of the vehicle. Further prior art relating to the background of the invention is provided in German patent application DE 10 2013 206 174 A1. SUMMARY

[0004] In various embodiments, a system and method for controlling a hybrid vehicle with an internal combustion engine selectively coupled to an electric machine by means of an upstream clutch, which is selectively coupled to a stepped transmission by means of a downstream clutch, includes at least one controller programmed to control the internal combustion engine and the electric machine by anticipating a wheel torque reversal in response to the entry into a play zone in order to set a gain applied to an active damping torque controller for an electric motor to reduce vibrations and dead weight in the drivetrain.

[0005] Embodiments include a method for controlling a vehicle with an internal combustion engine, an electric machine, and a transmission, which, in response to a change in torque according to driver demand and to the input torque to the transmission approaching zero, involves adjusting at least one gain of a feedback torque controller of an electric machine to regulate the torque of the electric machine through a range associated with a drivetrain or wheel torque reversal. Adjusting at least one gain may involve reducing the at least one gain to near zero. Adjusting at least one gain may occur in response to a torque ratio of the transmission being within a predetermined range. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram representing a representative hybrid vehicle with combustion and electric motor control according to embodiments of this disclosure, which is associated with wheel torque reversal; Fig. Figure 2 represents a wheel torque reversal and a corresponding play zone in a representative hybrid vehicle; Fig. 3 represents a representative strategy for identifying or anticipating a wheel torque reversal or a play zone for use in an internal combustion and electric motor control system according to embodiments of the disclosure; Fig. 4 and Fig. 5 represent an active damping control system for an electric motor for damping drive train vibrations using an adjustable gain during the control of the combustion and electric motor according to embodiments of the disclosure; Fig. Figure 6 is a block diagram illustrating the operation of a representative control architecture of a combustion and electric motor control system for a hybrid vehicle according to embodiments of the disclosure; Fig. 7 represents the operation of a hybrid vehicle according to the prior art without combustion and electric motor control during a wheel torque reversal, as provided by embodiments of the disclosure; Fig. 8 represents the operation of a hybrid vehicle with combustion and electric motor control during a wheel torque reversal according to embodiments of the disclosure; and Fig. 9 describes the operation of a system or method for combustion and electric motor control during a wheel torque reversal according to embodiments of the disclosure. DETAILED DESCRIPTION

[0006] Detailed embodiments are disclosed here as needed; however, it is understood that the disclosed embodiments are merely representative and can be implemented in various and alternative forms. The figures are not necessarily to scale; some features may be enlarged or reduced to show details of certain components. Accordingly, the disclosed specific structural and functional details are not to be interpreted as limiting, but merely as a representative basis for teaching the person skilled in the art the diverse uses of the claimed subject matter.

[0007] Fig. Figure 1 shows a schematic diagram of a hybrid vehicle 10 of one or more embodiments. The vehicle 10 includes an internal combustion engine 12 and an electric machine, which are located in the Fig. In the embodiment shown in Figure 1, an electric motor / generator (M / G) 14 is used, which can alternatively be a traction motor. The M / G 14 is configured to transmit torque to the internal combustion engine 12 or the vehicle wheels 16.

[0008] The M / G 14 is connected to the internal combustion engine 12 using a first clutch 18, also known as a disengagement clutch or the upstream clutch. A second clutch 22, also known as the launch clutch or downstream clutch, connects the M / G 14 to a transmission 24, and all input torque to the transmission 24 flows through the launch clutch 22. Although the clutches 18 and 22 are described and illustrated as hydraulic clutches, other types of clutches, such as electromechanical clutches, can also be used. The clutches 18 and 22 can be wet or dry clutches. Alternatively, the clutch 22 can be replaced by a torque converter that incorporates a bypass clutch, as described below.In other 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 (lock-out) clutch. In this configuration, a different conventional automatic transmission with a torque converter can be used, and it is sometimes referred to as a modular hybrid transmission configuration. Various other configurations may also be suitable for the disclosed combustion and electric motor control, even if they are not specifically shown or described.

[0009] The output shaft of the internal combustion engine 12 is connected to the release clutch 18, which in turn is connected to the input shaft for the M / G 14. The output shaft of the M / G 14 is connected to the starting clutch 22, which in turn is connected to the transmission 24. The various components of the vehicle 10 are positioned sequentially or in series with one another. The starting clutch 22 connects the vehicle's drive motors to the drivetrain 26, which includes the transmission 24, the differential 28, the vehicle wheels 16, and the components that connect them.

[0010] In another embodiment of the vehicle 10, the downstream clutch 22 is a bypass clutch with a torque converter. The input from the M / G 14 is the pump side of the torque converter, and the output from the torque converter to the transmission 24 is the turbine side. The torque converter transmits torque using a fluid coupling, and torque multiplication can occur depending on the degree of slip between the pump and turbine sides. The bypass or lock-up clutch for the torque converter can be selectively engaged to establish a mechanical or frictional connection between the pump and turbine sides for direct torque transmission. The bypass clutch can be disengaged and / or opened to control the amount of torque transmitted by the torque converter.The torque converter may also include a mechanical lock-up clutch.

[0011] In the vehicle 10, the starting clutch 22 or bypass clutch for the torque converter can be locked to increase fuel efficiency, and it can be locked when a wheel torque reversal or a backlash zone is traversed, depending on the specific application and implementation. The driving behavior and the control of the effect of a backlash traversal in the powertrain depend on the control of the drive torque from the internal combustion engine 12 and / or the electric machine 14. The torque of the M / G 14 can be controlled with greater accuracy and a faster response time than the torque of the internal combustion engine 12. In a purely electric operating mode for the vehicle 10, the torque of the M / G 14 can be controlled when a backlash zone is traversed.In a hybrid operating mode of the vehicle, where both the internal combustion engine 12 and the M / G 14 are operated, the torque from the M / G 14 and the torque from the internal combustion engine 12 can be controlled together to improve the driving behavior of the vehicle 10 and to reduce the effect of crossing the play zone on drivetrain vibrations and the possibility of drivetrain snapping.

[0012] In the representative embodiment shown, the internal combustion engine 12 is a direct injection engine. Alternatively, the internal combustion engine 12 can be a different type of internal combustion engine or drive motor, such as a port fuel injection engine or a fuel cell, or it can use different fuel sources such as diesel, biofuel, natural gas, hydrogen, or the like. In some embodiments, the vehicle 10 also includes a starter motor 30, which is operatively connected to the internal combustion engine 12, for example, by a belt or gear drive. The starter motor 30 can be used to provide torque to start the internal combustion engine 12 without adding torque from the M / G 14, such as for a cold start or certain high-speed starting events.

[0013] The M / G 14 is connected to a battery 32. The battery 32 can be a high-voltage battery. The M / G 14 can be configured to recharge the battery 32 in a regeneration mode, for example, when the vehicle's power output exceeds the driver's needs, through regenerative braking or the like. The M / G 14 can also be arranged in a generator configuration to moderate the amount of torque from the internal combustion engine 12 supplied to the drive 26. In one example, the battery 32 is configured to be connected to an external power grid, such as for a plug-in hybrid electric vehicle (PHEV) with the capability to recharge the battery from an electrical grid that supplies power to a socket at a charging station.A low-voltage battery may also be present to provide energy for the starter motor or other vehicle components, or low-voltage energy may be provided by a DC / DC converter connected to the battery 32.

[0014] In some 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 transmission 24 may be a gear transmission, and it may be a stepped transmission or a continuously variable transmission. The vehicle 10 is also provided with a pair of non-driven wheels; however, in alternative embodiments, a transfer case and a second differential may be used to positively drive all of the vehicle's wheels.

[0015] The M / G 14 and the clutches 18, 22 can be located in an electric motor generator housing 34, which can be integrated into the housing of the transmission 24 or alternatively constitute a separate housing in the vehicle 10. The transmission 24 has a gearbox to provide different gear ratios for the vehicle 10. The gearbox of the transmission 24 can include clutches and planetary gear sets or other arrangements of clutches and gear sets as known in the art. In alternative embodiments, the transmission 24 is a continuously variable transmission (CVT) or an automated mechanical transmission. The transmission 24 can be a six-speed automatic transmission, an automatic transmission with a different number of gears, or a different gearbox as known in the art.

[0016] The gearbox 24 is controlled by a gearbox control unit (TCU) 36 or the like to operate according to a circuit diagram, such as a production circuit diagram, which connects and disconnects elements in the gearbox housing to control the gear ratio between the gearbox output and the gearbox input. The TCU 36 also acts to control the M / G 14, the clutches 18, 22, and any other components in the electric motor generator housing 34.

[0017] An engine control unit (ECU) 38 is configured to control the operation of the internal combustion engine 12. A vehicle system controller (VSC) 40 transmits data between the TCU 36 and the ECU 38 and also communicates with various vehicle sensors. The control system 42 for the vehicle 10 can include any number of controllers and be integrated into a single controller or comprise various modules. Some or all of the controllers can be connected via a CAN bus (Controller Area Network - CAN) or another system.The control system 42 can be configured to control the operation of the various components of the transmission 24, the electric motor generator assembly 34, the starter motor 30 and the internal combustion engine 12 under any of a range of different conditions, including in a manner that minimizes or reduces the effects of any play in the drivetrain 26 and the influence on the driver during accelerator pedal actuation or release events.

[0018] The VSC 40 receives signals indicating driver input. An accelerator pedal position sensor (APPS) communicates with the VSC 40 and provides information regarding the accelerator pedal position, or whether the accelerator pedal is engaged or released. Engagement can be used by the driver to request higher engine speed, higher power, and / or higher torque, while release can be used to request lower engine speed, lower power, and / or lower torque. The brake pedal position sensor (BPPS) and gear selection sensor (PRND) also communicate with the VSC 40 to provide driver input information. In some applications, other sensors may be used, such as an internal combustion engine torque sensor or a transmission input torque sensor.Alternatively, different operating parameters such as the combustion engine torque or transmission input torque can be calculated or indirectly determined using TCU 36, ECU 38 and / or VSC 40 based on inputs from other sensors and calculated or estimated parameters.

[0019] Under normal drive conditions (no subsystems / components flagged), the VSC 40 interprets the driver's requirements (e.g., PRND and acceleration or braking needs) and then determines the wheel torque command based on the driver's requirements and the drive system's limits. Additionally, the VSC 40 determines when and how much torque each power source must provide to meet the driver's torque demands and to achieve the operating points (torque and speed) of the internal combustion engine 12 and the M / G 14.

[0020] The vehicle 10 can have speed sensors 44 positioned at different locations on the drive and drivetrain 26. The speed sensors 44 provide the control system 42 with information regarding the rotational speed of a shaft in near real time, although there may be some delay due to response time and signal and data processing. In the embodiment described in Fig. As shown in Figure 1, a speed sensor 44 measures the speed of the output shaft of the internal combustion engine 12, the speed of the shaft connected to the M / G 14, the speed of the input shaft of the gearbox 24, the speed of the output shaft of the gearbox 24 and the speed of one or both axles connected to the wheels 16.

[0021] As part of the control strategy or control algorithm for the operation of the vehicle 10, the control system 42 can provide an internal combustion engine torque request (τ e) and / or an M / G torque requirement (τ m ) place, as in Fig. 1 shown. The net gearbox input torque (τ i ) is the adjusted torque of the electric motor plus the torque of the internal combustion engine (τ i = τ m +τ e ), assuming that the release and starting clutch 18, 22 are locked.

[0022] In alternative embodiments, the clutch 22 can be replaced by a torque converter, which includes a torque converter and a lock-up clutch or bypass clutch. The torque converter exhibits torque multiplication effects when certain rotational speed differentials exist across the torque converter. During torque multiplication, the output torque of the torque converter is greater than the input torque due to torque multiplication across the torque converter. Torque multiplication occurs, for example, when the vehicle 10 is started from a standstill and the input shaft to the torque converter begins to rotate, while the output shaft of the torque converter is still at rest or has just begun to rotate.

[0023] The lock-up clutch, or bypass clutch, is used to lock out the torque converter such that the input and output torques for the downstream torque transmission device 22 are equal, and the input and output rotational speeds for the device 22 are equal. A locked clutch eliminates slippage and inefficiency of the drive via the torque converter, for example, when the rotational speed ratio across the torque converter is greater than approximately 0.8, and it can increase the fuel efficiency of the vehicle 10.

[0024] A change in the proportion and / or direction of the torque can lead to disturbances or vibration in the drivetrain 26, which is associated with backlash. Backlash can occur in a vehicle's drivetrain 26 whenever either the wheel torque 16 or the engine torque, supplied by the internal combustion engine 12 and the M / G 14, changes direction relative to each other. This change in torque direction can occur when the vehicle 10 is operated with both the disengagement clutch 18 and the launch clutch 22 (or lock-out clutch for the torque converter) in a locked or engaged position. For example, when the vehicle 10 brakes, the compression braking effect of the internal combustion engine 12 provides a negative torque to the transmission 24, which is then transmitted through the differential 28 and then to the wheels 16.At this point, the drivetrain 26 is wound or twisted in the negative direction. When the driver makes a power demand or actuation using the accelerator pedal, the torque of the internal combustion engine 12 changes from negative to positive as it begins to supply torque to propel the vehicle 10. The drivetrain 26 unwinds or untwists as each drive component transitions from transmitting negative torque to transmitting positive torque. At a certain point during this transition, the drivetrain 26 passes through a relaxed state in which no torque is applied to the wheels 16.

[0025] In this region of zero torque, the gearing in the transmission 24 and / or the differential 28 may not be tightly coupled to the matching gears or components, and some play or free rotation may be present in the drivetrain 26. Play across multiple sets may be cumulative. If the internal combustion engine 12 continues to supply positive torque, the drivetrain 26 will wind up in the positive direction. The gears may engage quickly, resulting in a snapping sound. Additionally, the axle connecting the differential 28 to a wheel 16 may twist slightly as a result of higher torque on the differential 28 side of the axle compared to the wheel 16 side. The axle may act as a torsional spring to store this energy.When the vehicle 10 begins to accelerate, the torque of the wheel 16 catches up with the torque at the differential 28, and energy stored in the axle is rapidly released, resulting in an oscillation in the opposite direction, or backlash. The result of this backlash traversal is a snapping or noise as the gear teeth engage and a reduction in wheel torque as axle energy is applied. The snapping and oscillations can be noticed by a driver, depending on their severity. For a drive with multiple gear teeth arranged in series, each gear tooth can have a backlash zone. The backlash in the drive either decreases or propagates through the gear teeth. After one gear tooth engages, the next gear tooth will traverse a backlash zone as the torque reversal passes through the component.Dead gear can include play in the main gearbox as well as in subsequent gearboxes.

[0026] The scenario described above can also occur in the opposite direction. In this case, the driver would make a power request, such as pressing the accelerator pedal to accelerate the vehicle, and then suddenly withdraw the power request by releasing the accelerator pedal. The drive shaft 26 transitions with a similar torque loss or gap and a snapping sound during the change from a wound state in the positive direction to a wound state in the negative direction. The effect of backlash due to sudden acceleration is usually more noticeable than during sudden deceleration.

[0027] Two game conditions for vehicle 10 are graphically represented in Fig. Figure 2 is shown as an example. The accelerator pedal 60, the transmission output speed 62, the wheel speed 64, and the wheel torque 66 are shown at 68 during a sudden deceleration and a sudden acceleration at 70. After the deceleration request at 68, the transmission output speed 62 decreases more rapidly than the wheel speed 64. This leads to region 72, labeled "zero-value wheel torque," where the drivetrain 26 is in its relaxed state as the wheel torque 66 transitions from positive to negative. Immediately following this transition, the wheel torque 66 decreases rapidly as the wheel speed 64 catches up with the transmission output speed 62, leading to region 74, labeled "torque loss."This torque loss 74 is essentially the dead load and is caused by the energy stored in the half-shaft, which is released and causes play in the gearbox 24 and other drivetrain components, in addition to the negative torque supplied by the gearbox output. The effect of the dead load traversal 74 leads to a resulting vibration with respect to the wheel torque.

[0028] During acceleration, a similar scenario occurs after an activation request at 70, only in reverse. The increase in the transmission output speed 62 leads to an increase in the wheel speed 64, resulting in region 76 with zero torque and then, at 78, a rapid torque increase or "torque peak," causing a backlash effect or noise and vibration that can be perceived by the driver.

[0029] The control system 42 is configured to detect, monitor, and / or predict the backlash in order to reduce or mitigate the effect of dead-gear traversing. The dead-gear in the vehicle 10 can be detected by monitoring the transmission input and output torque ratios, as described below. In one example, the control system 42 detects or monitors a dead-gear condition for the vehicle as described in U.S. Patent No. 9,037,329 B2, issued on May 19, 2015, and incorporated herein by reference in its entirety. In other embodiments, dead-gear can also be detected using speed sensors or other methods known by the art, such as those described in U.S. Patent No. 7,223,203 B2, issued on May 29, 2007, and incorporated herein by reference in its entirety.

[0030] Fig. Figure 3 shows the ratio of input torque to output torque across the transmission 24. An ideal or perfect transmission 24 has a perfect torque ratio, as shown by line 100 passing through zero. However, in a real transmission 24, there are proportional and non-proportional losses that can be captured to improve accuracy. These losses cause the ideal torque ratio to change or modify to an actual ratio of output torque to input torque. The actual torque ratio is the same as the ideal torque ratio with the losses included. When both the input and output torque are negative (generating), the transmission losses act in such a way that they contribute to slowing the vehicle. When both the input and output torque are positive (driving), the losses hinder driving efforts.Line 118 represents the actual ratio during drive operation, taking losses into account. Line 120 represents the actual ratio during generation, also taking losses into account. Line 122 corresponds to the range of ratios in which the gearbox 24 carries an approximately zero torque and the probability of the play zone effect occurring is highest; line 122 represents the play zone.

[0031] Region 124 represents the entry region for the game zone from the drive side, or the positive input torque side. Region 126 represents the entry region for a game from the generating side, or the negative input torque side. Line 122 between regions 124 and 126 is bounded by an input torque of zero (at 126) to an input torque with a positive scalar value (at 124) and by an output torque with a negative scalar value (at 126) to an output torque of zero (at 124). In other embodiments, other boundaries may be specified to define the game zone. By controlling the input torque when the vehicle 10 is operating on line 122 while accelerating or decelerating along it, the effects of a game crossing event can be reduced or attenuated. Line 122 may be linear or nonlinear.For example, line 122 can be a step function with multiple steps caused by backlash in each tooth engagement in the drive train.

[0032] The model of input torque to output torque for a transmission, as in Fig. Figure 3 shows that the torque can be determined as described below. During acceleration, the powertrain is in a drive configuration, so that torque is transmitted from the internal combustion engine 12 and / or the M / G 14 through the transmission 24 to the wheels 16. During deceleration, the powertrain is in a driven configuration, so that torque is transmitted from the wheels 16 through the transmission 24 to the M / G 14. However, the amount of torque transmitted through the transmission 24 and the powertrain 26 depends on the gear ratio and the losses in the transmission 24 and the powertrain 26. Fig. Figure 3 graphically represents the torque, gear ratio, and losses of the gearbox 24. The gear ratio of the gearbox 24 corresponds to a ratio of the torque input (τ) ein ) and torque output (τ aus ), where τ ein the torque at the input shaft 46 to the gearbox 24 corresponds to and τ aus The torque at the output shaft 48 of the gearbox 24 corresponds to the torque, and there are no losses in the system. The gear ratio can be based on a speed ratio and calculated from the number of teeth of the various gears meshing in the gearbox 24. The gear ratio can also be considered an ideal torque ratio. For example, the output torque (τ) corresponds to aus ), if the translation is 4:1, for an input torque (τ ein ) of +100 Nm to 400 Nm. Therefore, the ideal torque ratio is in Fig. 3 represented by line 100, where the slope of the line corresponds to the ideal torque ratio or translation.

[0033] A linear relationship can be used to relate the torque input to the torque output of a gearbox, where the linear line can be described by the following formula: y=m*x+b where y is the output torque (τ aus ) corresponds and x is the input torque (τ ein ). The slope m corresponds to the torque ratio for output / input or the gear ratio, and b corresponds to the output torque when the input torque is zero. Ideally, or in a lossless gearbox 24, the slope would correspond to the ideal torque ratio and the displacement would be zero, as shown by line 100. The lossless slope corresponds to the ideal torque ratio or gear ratio (DV). ideal). Therefore, the formula for line 100 is: τout=(τin*DVideal)

[0034] However, the transmission 24 is not perfectly efficient and exhibits some losses. The losses in the transmission can be a function of friction, heat, circulation losses, or many other factors. The losses in the transmission can be characterized as "proportional losses" and "non-proportional losses." Proportional losses vary depending on the current gear and speed, while non-proportional losses are independent of the torque. The efficiency of a transmission 24 is normally measured by the transmission 24 itself. The efficiency of the drivetrain 26 is usually measured using the locked starting clutch 22 or the locked bypass clutch for a torque converter, or it can be modeled without a torque converter.

[0035] The y-intercept b corresponds to the non-proportional loss, T s , shown at 112 in Fig. 2, for each gear in a gear stage. Line 114 represents the ideal torque ratio or gear ratio when non-proportional losses, T s , in which gearbox 24 is taken into account. The non-proportional losses, Ts, can correspond to units of the output torque. The non-proportional losses or circulating losses in the drivetrain can depend on the output speed of the drivetrain, the oil temperature of the drivetrain, and the gear in which the drivetrain is located. The output speed of the drivetrain can depend on the input speed of the drivetrain and a gear ratio of the drivetrain. Therefore, the formula for line 114 is: τaus=(τin*DVideal)−Ts

[0036] Proportional transmission losses can also be taken into account in the model. The actual torque ratio of transmission 24 to τ aus to τ eincan be empirically measured in different gears. Empirical modeling of the transmission 24 without the torque converter (locked or not engaged) allows for a representation of the losses "proportional to the torque" separately from the losses "non-proportional to the torque," which can be represented using a linear relationship between the output torque and the input torque. Proportional losses can depend on the drivetrain oil temperature, the gear in which the drivetrain is operating, and the input torque to the drivetrain. Proportional losses are represented by the slope of the output torque-to-input torque ratio for each gear. The slope, including proportional losses, corresponds to the actual torque ratio across the transmission 24.

[0037] The ideal torque ratio, or ideal transmission ratio, and the relationship between torque input and torque output can then be used in combination with just a few measured points of the actual torque ratio relationships from input to output to determine the difference between the rises of the ideal torque ratio (DV). ideal ) and the actual torque ratio (DV) tatsächlich ) to determine. Proportional torque losses can be taken into account by considering the proportion of τ ein subtracted, which is derived from the difference in the slopes between the ideal torque ratio and the actual torque ratio. Non-proportional losses are accounted for by T s The linear formula for the gear ratio, taking proportional and non-proportional losses into account, is represented as line 116 in [reference]. Fig. 2, can be represented according to the following equation: τout=(τin*DVideal)−Ts−τin*(DVideal−DVactual)

[0038] By canceling out the terms on the right-hand side of the loss equation, the formula for line 116 can be obtained. Fig. 3. can be simplified to the following: τout=(τon*DVactual)−Ts

[0039] For example, τ aus With 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, the following values ​​are determined. It should be noted that the figures in the following example are simplified for the sake of simplicity.

[0040] First, the output torque is calculated using equation (3A) as follows: τout=(100*4.1)−5−(100*(4.1−4.0))=395 Nm

[0041] Using equation (3B), the output torque is calculated as follows: τaus=(100*4,0)−5=395 Nm

[0042] The power can be determined by multiplying the torque by the rotational speed of shafts 46, 48, illustrated by the following equation: P=τ*ω

[0043] Using an input speed of 400 rad / s, the input and output power can be calculated according to the following equations: Pain = 100 * 400 = 40,000 watts Paus=395*(400 / 4.1)=38,536 watts

[0044] The difference between the power at the gearbox input 46 and the gearbox output 48 corresponds to the amount of power loss due to gearbox inefficiency and can be determined according to the following equation: Pain-Pause = 1,464 watts

[0045] The loss formulas in equations (3A) and (3B) are generally accurate when describing the transmission, including losses in a traditional drive. The loss formulas in equations (3A) and (3B) can also accurately describe the transmission, including losses in a HEV drive, when the vehicle is in motion. However, a problem arises when the vehicle supplies power to the transmission output 62 and extracts it from the transmission input 60, as in regenerative braking in an HEV. In this situation, the values ​​for the torque through the drivetrain 26 are negative, the transmission is in a driven configuration, and the loss formulas in equations (3A) and (3B) are applied differently.

[0046] The problem regarding the loss formulas in equations (3A) and (3B) for regenerative drive braking is illustrated by another example, as shown below. For example, for negative torques, where the input torque τ ein an input torque of -100 Nm corresponds to the actual ratio 4.0, the ideal ratio corresponds to 4.1, and non-proportional losses (T s ) 5 correspond, τ aus calculated as follows: τ aus = (-100 * 4.1) - 5 - (100 * (4.1 - 4.0)) = -405 Nm, using equation (3A), or τ aus = (-100* 4.0) - 5 = -405 Nm, using equation (3B).

[0047] Using an input speed of 400 rad / s, the power calculations can be determined as follows: Pain = -100 * 400 = -40,000 watts Paus=−405*(400 / 4.1)=−39,512 watts Pain−Paus=Ploss=−488 watts

[0048] Using the standard formula results in a negative loss calculation, which is not possible because the power entering the output shaft 48 of the gearbox 24 is less than the power exiting the gearbox through the input shaft 46. In this example, 40,000 watts of renewable energy are captured at the gearbox input 46 when only 39,512 watts of renewable energy from the wheels 16 enter the gearbox output 48.

[0049] For modeling the torque relationship, two lines are better suited to the data than one. The first line is shown as line 118 in Fig. 3 represents the positive output torque τ aus and input torque τ ein , such as when vehicle number 10 is running. The second line, illustrated as line 120 in Fig. 2 represents the negative output torque and input torque, such as when the vehicle is regeneratively braking.

[0050] The non-proportional losses 112 are calculated so that they are the same during driving and regeneration. Therefore, the same shifted term b is used for a non-proportional torque loss T in both line 118 and line 120. s used. However, the proportional losses during regeneration are not correctly captured using the standard driving equations.

[0051] The correct τ ein for a given value τ aus The calculation is correct if the proportional torque losses are added in the correct direction. The term for the proportional loss in equation (3A), that is, τ ein * (DV ideal - DV tatsächlich ), must correspond to a positive value, regardless of whether the gearbox τ eintransmits positive or negative torque. Since τ ein Since the torque is negative during regeneration and the expression of the proportional loss in equation (3A) must be positive, the ideal torque ratio during regeneration must be smaller than the actual torque ratio to provide the correct calculation for more energy going into the gearbox output 48 than is received at the gearbox input 46 during the transmission of a negative torque.

[0052] For example, τ aus during a transmission of a negative torque, where the transmission input torque τ ein -100 Nm corresponds to the actual torque ratio 4.2, the ideal torque ratio, which is smaller than the actual torque ratio, corresponds to 4.1, and non-proportional losses T s 5 correspond to the following: τ aus= (-100 * 4.1) - 5 - (-100 * (4.1 - 4.2)) = -425 Nm, using equation (3A) or τ aus = (-100 * 4.2) - 5 = -425 Nm, using equation (3B). It is noted that the previous loss of -405 corresponds to a deviation of approximately five percent.

[0053] Using an input speed of 400 rad / s, the input power, output power and power loss can be calculated according to the following equations: Pain = -100 * 400 = -40,000 watts Paus=−425*(400 / 4.1)=−41,463 watts Pain−Paus=Ploss=1463 watts

[0054] If both the output torque and input torque are positive, the actual measured rise is smaller than the ideal torque ratio, as can be seen from line 118 compared to line 114. However, if both the output torque and input torque are negative, the actual measured rise, or DV, istatsächlich greater than the mechanical torque ratio or DV ideal , as can be seen from line 120 compared to line 114. The actual torque ratio for a negative torque is measured 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 captured at the transmission input 60 than is fed into the transmission output 62 during regeneration (as shown by line 116 compared to line 114).

[0055] To account for the difference between the actual torque ratio and the ideal torque ratio (or gear ratio), a proportional loss coefficient C1 is calculated for each gear using the following formula: C1=τin*(DVideal−DVactual)

[0056] When driving / operating or with a positive torque through the gearbox 24, the proportional loss coefficient C1 is included in equation (3B) to derive the loss equation as follows: τout=(τon*(DVactual−C1))−Ts

[0057] Alternatively, equation (5) can be rearranged to find a τ ein due to a desired torque output τ aus to be determined as follows while driving: τin=(τout+Ts) / (DVideal−C1)

[0058] If the torque through transmission 24 is negative, as during regenerative braking, the actual torque ratio is greater than the ideal torque ratio (or gear ratio) by the same amount by which 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. Thus, τ is... ein during the transmission of a negative torque through the gearbox due to a desired torque output τ aus as follows: τein=(τaus+Ts) / (DVideal+C1)

[0059] The relationship between the input torque and the output torque for transmission 24 is therefore better characterized by the two lines 118 and 120, in order to distinguish between driving and regeneration, or between positive and negative torque. Line 120 in Fig. Line 3 represents the line that takes into account proportional losses added to regenerative braking. Line 120 can be characterized by rearranging equation (7) as follows: τout=(τon*(DVideal+C1))−Ts

[0060] The inclusion of a torque converter, pumping losses, and dynamic inertial losses can be consistent throughout the entire development process for the transmission control system. For example, if the vehicle includes a torque converter, the torque input τ can be ein , when the vehicle is moving, can be determined as follows: τin=((τout+Ts) / (DVideal−C1))*(1 / DVDrehtorque converter)+lossPump+lossdyn_inertia

[0061] When the M / G 14 is generated or when the vehicle is regeneratively braking, so that the transmission output torque is negative, equation (9) is modified so that the torque input τ ein can be determined starting from the following equation: τin=((τout+Ts) / (DVideal−C1))*(1 / DVDrehtorque converter)+lossPump+lossdyn_inertia

[0062] The torque converter can be connected between the M / G 14 and the gearbox 24. The torque converter can also be installed inside the gearbox 24. When the torque converter is locked by a locking mechanism on the bypass clutch, the torque ratio of the torque converter is 1:1.

[0063] The control system 42 is configured to determine a play zone for the vehicle 10 based on the gear of the transmission and to use the determined play zone during vehicle operation to predict or detect an impending play zone, which in turn can be used in a control strategy to mitigate the effect of the drivetrain play traversal by controlling an adjustable gain of an active damping system for an electric motor, as described in more detail below.

[0064] Active Motor Damping (AMD) can be used to control drivetrain vibration caused by crossing play zones or wheel torque reversal. Fig. Figure 4 shows a control loop block diagram according to an embodiment of a damping control system that may include one or more adjustable gains for adjusting the electric motor torque and reducing drive vibrations during play zone crossings. The control loop 400 may include a filter 402 (shown here in a forward loop) that removes frequency content and limits the damping function to a predetermined frequency range, with the filter effectively acting as a bandpass filter. The predetermined frequency range can be selected to encompass any scenario of drive torque variation identified as exciting a drive resonance that leads to undesirable vehicle behavior. Thus, the selected frequency range can vary depending on the vehicle configuration.Filter 402 can be implemented using a narrowband stop filter, which limits the damping function to a narrow frequency range, such as 5 Hz to 7 Hz. However, the frequency ranges can vary and, depending on the specific application and implementation, could include frequencies between 1 Hz and 100 Hz. Filter 402 can also be adjusted or varied based on the selected gears and ratios for gearbox 24 to compensate for variations in the resonant frequency associated with a currently selected gear and its associated ratio.

[0065] A simplified model of the dynamics of the mechanical system of the M / G 14 can be represented by a transfer function within the controller 400, as generally represented in block 404, such as: P(s)=1Jms2+cs+k where J mThe inertia of the M / G 14 is given by c, the damping constant of the mechanical system by k, and the spring constant of the mechanical system by k. The transfer function 404 can be used to determine an angular position Θ of the M / G 14 corresponding to an electric motor input torque command τ. m This corresponds to the angular position Θ of the M / G 14 being entered into a derivative block 406, where the derivative is an output ω. m exhibits the electric motor speed of the M / G 14 (where the electric motor speed is an electric motor angular velocity). The electric motor speed ω m Although shown as an output of derivation block 406, this is merely a representation of the mechanical system. The electric motor speed ω m is typically a measured value of the rotation of the motor shaft, which is determined using a corresponding sensor 44 and is also referred to as the measured electric motor speed ω mcan be described.

[0066] With reference to Fig. 5 is the measured electric motor speed ω m shown with a representation of the vibrations that occur at the electric motor speed ω m of the M / G 14. Also a desired electric motor speed ω m_des is calculated by generating a smooth line that corresponds to the measured electric motor speed ω m approximates. The desired electric motor speed ω m_des This can be created using numerical analysis methods such as curve fitting, interpolation, or smoothing. Once the desired electric motor speed ω is reached... m_des Once calculated, a twist number ω is obtained. m_twist calculated, where it is the difference between the measured electric motor speed ω m and the desired electric motor speed ω m_des it.

[0067] As soon as the number of twists ω m_twist , again with reference to Fig. 4, which was calculated, is used as an input in a feedback loop. The feedback loop can include a feedback controller 408, which can be a proportional-differentiating (PD) controller, represented by the following transfer function: H(s)=kmdss+p+kmp where k md a differentiating term relative to the number of twists, ω m_twist is, ss+p a main filter is and k mp is a proportional member that is based on the number of twists ω m_twist is based on. The differentiating element k md and the proportional term k m , can be either constant values ​​or outputs from one or more tables, which are stored, for example, in the TCU 36 or VSC 40, where the input to the table(s) is the twist rate ω m_twistThe output of the feedback controller 408 is a setting of the torque of the electric motor τ. m_adj . Setting the electric motor torque τ m_adj At 410, the desired electric motor torque τ m_des subtracts, which is an electric motor torque command τ m This results in the desired electric motor torque τ. m_des This will be the amount of torque provided by the M / G 14 when it operates as a generator in hybrid mode or in purely electric mode. The electric motor torque command τ m After passing through filter 402, it is also used as input for transfer function 404.

[0068] Alternatively, k md be a differentiating element that depends on the electric motor speed ω m based on mp can be a proportional element that depends on the electric motor speed ω m is based on, and the differentiating element k mdand the proportional term k mp These can be either constant values ​​or outputs from tables stored in the TCU 36 or VSC 40, where the input to the table(s) is the electric motor speed ω. m is.

[0069] The feedback controller 408 is not limited to a PD controller and can instead include other controller types, such as PI (proportional integrating) controllers or PID (proportional integrating-differential) controllers. Likewise, other control loop configurations with different positive and / or negative feedback elements can also be used.

[0070] As further below with reference to Fig. As described in section 6, the control loop 400 can include one or more adjustable gains that change in response to operation through a play zone. The control algorithm coordinates the control of the combustion and electric motors to attenuate powertrain slack during a torque reversal, while also damping vibrations caused by rapid torque changes in the powertrain. The control loop 400 will continue to operate to provide active electric motor damping and reduce powertrain vibrations, either for a predetermined elapsed time or until the speed error is reduced below a predetermined threshold. The speed error is a difference between the measured electric motor speed ω and the actual speed ω. m and the desired electric motor speed ω m_des (the twist number ω) m_twist) and can be represented by the following equations: e=ωm−ωm_des or e=ωm_twist

[0071] Fig. Figure 6 is a block diagram illustrating a control architecture for combustion and electric motor control during wheel torque reversal according to at least one embodiment of the disclosure. The control 600 can be implemented by one or more control algorithms executed by a programmed microprocessor such as, for example, TCU 36, ECU 38, and / or VSC 40. Block 602 represents a determination of the transmission input torque according to driver demand based on inputs 604, which in this embodiment include the accelerator pedal position, the powertrain ratio, and the vehicle speed. Block 602 determines a transmission input torque request, as represented by 606, which is provided to Block 608.In block 608, an internal combustion engine torque request 610 and an electric motor torque request 612 are determined to meet the transmission input torque request 606, based on current operating parameters such as the current operating mode, battery charge state (SOC), vehicle speed, transmission gear selection, etc. The internal combustion engine torque request 610 is subject to internal combustion engine subsystem limitations, as represented by 620, to provide an internal combustion engine torque command, represented by 622, to the internal combustion engine subsystem 624. The internal combustion engine subsystem control provides internal combustion engine torque control 626 for the internal combustion engine or system 630, as well as an estimate of the internal combustion engine output torque, as represented by 628.

[0072] Similarly, the electric motor torque request 612 at 640 is limited by electric motor torque upper and / or lower limits to provide an electric motor torque command 642 for the electric motor subsystem 644. The electric motor controller 646 controls the electric motor or the system 650 to provide electric motor torque to fulfill the electric motor torque command 642.

[0073] The detection of a play zone or wheel torque reversal occurs, as represented in 660, based on various vehicle inputs 662, which may include, for example, an estimate of the internal combustion engine torque, an estimate of the electric motor torque, a transmission torque ratio, transmission input and output speeds, and the wheel speed. The resulting torque estimate 664 is used to predict a wheel torque reversal or play zone crossing, thus enabling active electric motor damping (AMD) by scheduling one or more AMD gains, as represented in block 666. The AMD gain(s) may be scheduled using one or more reference tables or calculated otherwise based on one or more equations. As in Fig. As shown in Figure 8, in one embodiment the AMD gain(s) used in the vibration control algorithm implemented by the AMD controller 670 are adjusted at block 666 to provide a gain setting 668 that reduces the gain(s) to near zero when the drivetrain torque is near zero during a transition from driving force to regenerative force or vice versa. The gain(s) are then increased to smoothly and gradually introduce vibration control by the AMD controller 670 after the torque reversal occurs.

[0074] Fig. Figure 7 represents a representative operation of a state-of-the-art hybrid vehicle during a wheel torque reversal associated with accelerator pedal release. The control system represented by graph 700 does not include one or more adjustable gains of the AMD controller. Graph A represents the accelerator pedal position 710 before, during, and after crossing the play zone 716. As shown, releasing or decreasing the accelerator pedal position 710 in this example will trigger the wheel torque reversal within the play zone 716. Graph B represents the transmission input speed request 720 and depicts a oscillation 722 at the powertrain resonance. The transmission input torque request 730 is shown in graph C. The rate of the transmission input torque request changes to slow the rate for a smooth crossing of the torque zero point at the beginning of the play zone 716, as generally indicated in 732.The electric motor torque is applied in the opposite direction to the speed change by the active electric motor damping control, as represented by figure 734, to dampen the drivetrain resonance. The expected wheel torque is shown in graph D by line 740, which indicates the expected region of zero torque at figure 742, where there is clearance between the engaging gear teeth. The actual wheel torque is shown in graph E by line 750. The AMD controller, which uses a constant gain, as shown in graph F by line 760, causes the wheel torque to cross the zero torque multiple times, as indicated by figure 752, resulting in drivetrain snapping.

[0075] Fig. Figure 8 represents a representative operation of a hybrid vehicle during a wheel torque reversal associated with accelerator pedal release, using an AMD with adjustable gain(s) according to an embodiment of the disclosure. The control system represented by the curves or graphs 800 includes an AMD system with one or more adjustable gains. Curve A represents the accelerator pedal position, represented by line 810, resulting in a wheel torque reversal within the operating zone 816. Curve B represents a transmission input speed request, as represented by line 820, and the associated powertrain resonance vibration, as represented by line 822. Curve C represents a transmission input torque request, as represented by line 830.The AMD torque used to dampen drivetrain vibrations is represented by line 832 and is reduced by setting one or more AMD gains to near zero in the zero-valued torque region, indicated at 834. The gain(s) are then increased to provide a smooth AMD torque transition, as indicated at 836. Trajectory D represents the expected wheel torque 840 and the expected zero-valued torque region 842, where there is clearance between meshing gear teeth. Trajectory E represents the actual wheel torque 850. The reduced AMD torque near the zero-valued torque region 852 enables a smooth torque transition.

[0076] The curve F represents a representative gain 860 of the AMD control system, which is reduced or gradually decayed as the gearbox input torque approaches the play zone 816, as represented in 862. One or more gains are reduced to near zero, as indicated in 864, and then increased or gradually built up, as indicated in 866. Although shown as a piecewise linear function in this example, the one or more gains may be reduced differently depending on the specific application. Likewise, the reduction or gradual decay of the gain may occur at a rate that differs from the gradual build-up or increase of the gain.

[0077] Fig. Figure 9 is a simplified flowchart illustrating the operation of a combustion and electric motor control system or method during a wheel torque reversal in a representative embodiment. The diagrams from Fig.Figure 9 presents a representative control strategy or control algorithm for a hybrid vehicle, which, according to representative embodiments of the present disclosure, comprises an internal combustion engine and one or more electric machines. The presented control strategy and / or logic is generally stored as instructions or code that are executed by software and / or hardware in one or more vehicle controllers, such as TCU36, ECU38, and VSC40, and / or related vehicle controllers. The instructions or code can be processed using any of a number of known strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Accordingly, different steps or functions shown can be performed in the illustrated sequence or in parallel, or in some cases, omitted.Although not explicitly shown, the average person will recognize that one or more of the illustrated steps or functions may be repeated, depending on the processing strategy used. Likewise, the processing sequence is not necessarily required to achieve the features and benefits described in this document and is intended instead to facilitate presentation and description. Naturally, the control logic or algorithm shown may be implemented in software, hardware, or a combination of both, in one or more controllers, depending on the specific application. In the case of software implementation, the following may be possible:The control logic or instructions can be stored in one or more non-volatile, computer-readable storage media containing data representing code or instructions that are executed by a computer to control the vehicle. The computer-readable storage media can include one or more from a range of known physical devices that employ electrical, magnetic, optical, and / or mixed storage to store executable instructions and associated calibration information, operating variables, and the like.

[0078] The control system or procedure 900 determines whether the transmission input torque is below zero at 910 and, if so, whether the driver requirement increases at 912. Block 914 determines whether the transmission input torque is approaching zero. If so, one or more gains of the active electric motor damping controller, as represented by 916, are reduced or gradually phased out. If the transmission input torque is not approaching zero at 914, block 918 determines whether the transmission input torque has crossed zero and, if so, one or more gains of the active electric motor damping controller are increased or gradually built up at block 920.

[0079] If the transmission input torque is above or at zero, as specified in 910, block 930 determines whether the driver requirement decreases. Block 932 then determines whether the transmission input torque is approaching zero. If the transmission input torque is not approaching zero at 932, block 934 determines whether the transmission input torque has crossed zero. If so, block 936 gradually builds up or increases at least one gain of the active electric motor damping controller. If the transmission input torque is approaching zero at 932, at least one gain of the active electric motor damping is reduced or gradually decreased, as specified in 938. If the result of any block 912, 918, 930, or 934 is "no," the process ends and repeats, as specified in 950.Similarly, the process ends and repeats itself after one or more gains for the active electric motor damping controller have been set, as indicated for blocks 916, 920, 936 and 938.

[0080] Although representative embodiments are described above, this is not intended to describe all possible forms of the claimed subject matter. Rather, the terms used in the patent specification are descriptive rather than limiting, and it is understood that various modifications can be made without deviating from the spirit and scope of the disclosure. Furthermore, the features of different implemented embodiments can be combined to form further embodiments that are not expressly described or illustrated.Although various embodiments have been described as advantageous or preferred over other embodiments or implementations in the prior art with respect to one or more desired properties, it is apparent to the person skilled in the art that one or more features or properties may be compromised in order to achieve the desired overall attributes of the system, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, strength, service life, life cycle costs, marketability, appearance, packaging, size, operability, weight, manufacturability, ease of assembly, etc.Embodiments which are described as less desirable than other embodiments or implementations according to the prior art with regard to one or more properties are not necessarily outside the scope of protection of the disclosure and may be desirable for certain applications.

Claims

[1] Vehicle (10), comprising: an internal combustion engine (12) which is selectively coupled to an electric machine (14) by means of an upstream clutch, which is selectively coupled to a stepped transmission (24) by means of a downstream clutch (22); and at least one controller (42) programmed to control the internal combustion engine (12) and the electric machine (14) in anticipation of a wheel torque reversal in response to entry into a play zone, in order to set a gain applied to an active damping torque controller (670) for an electric motor to reduce vibrations and dead weight in the drivetrain, wherein the at least one controller (42) reduces the gain in advance of a torque zero point where there is air between engaging gear teeth of drivetrain components. [2] Vehicle (10) according to claim 1, wherein the gain is reduced linearly. [3] Vehicle (10) according to claim 1, wherein the at least one control (42) increases the gain after a torque zero point where there is air between engaging gear teeth of drive train components. [4] Vehicle (10) according to claim 3, wherein the amplification is increased linearly. [5] Vehicle (10) according to claim 1, wherein the at least one control (42) for adjusting the gain is programmed, which is applied to an active damping torque controller (670) for an electric motor, which regulates the torque of an electric machine to counteract speed oscillations of the drive and to guide a measured speed of the electric machine (14) to the desired speed of the electric machine (14) using a damping function based on a difference between the measured and a desired speed of the electric machine (14). [6] Vehicle (10) according to claim 1, wherein the at least one control (42) adjusts the amplification based on an estimate of the internal combustion engine torque, an estimate of the torque of the electric machine (14) and a torque ratio of the step transmission (24). [7] Vehicle (10) according to claim 6, wherein the at least one control further adjusts the gain based on input and output speeds of the step transmission and the vehicle wheel speed. [8] Vehicle (10) according to claim 1, wherein the at least one control is further programmed to adjust the gain such that no torque is requested from the electric machine when the drive train torque passes a torque zero point at which there is air between engaging gear teeth of drive train components. [9] Vehicle (10) according to claim 1, wherein the at least one controller is programmed to identify the play zone based on a change in the accelerator pedal position and a torque ratio of the step transmission (24). [10] Vehicle (10) according to claim 1, wherein the downstream clutch is arranged inside a torque converter of the step transmission (24). [11] Method for controlling a vehicle (10) comprising an internal combustion engine (12), an electric machine (14) and a transmission (24), comprising: as a response to a change in torque according to driver requirements; and to the fact that the input torque to the transmission (24) approaches zero, an adjustment of at least one gain of a feedback torque controller (408) of an electric machine to control the torque of the electric machine through a range associated with a drivetrain or wheel torque reversal, characterized by , that Adjusting at least one gain includes reducing at least one gain. [12] Method according to claim 11, wherein adjusting at least one gain comprises adjusting the at least one gain in response to a torque ratio of the transmission (24). [13] Method according to claim 11, further comprising increasing the at least one gain in response to the fact that the input torque into the transmission (24) passes through a zero-valued torque section.

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