Vehicle control system

Abstract

The rattle is suppressed, preventing shocks and impact noises. [Solution] Vehicle control comprising a control unit configured to perform the following: acquire the drive torque from a predetermined time before the start of rattle reduction; acquire the rattle reduction torque; calculate the rattle reduction time according to the drive torque from the predetermined time before, the rattle reduction torque, and a map stored in the memory unit; output the rattle reduction torque from the start of rattle reduction until the rattle reduction time has elapsed; and increase the drive torque from the time the rattle reduction time has elapsed.

Description

Technical Field

[0001] The present disclosure relates to a vehicle control device.

Background Art

[0002] It is known to transmit backlash elimination torque for eliminating clearance in an engagement mechanism in the same direction as the engagement torque (see, for example, Patent Document 1.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problem to be Solved by the Invention

[0004] An object of the present disclosure is to suppress the occurrence of shock or impact sound due to backlash elimination.

Means for Solving the Problem

[0005] One aspect of the present disclosure is vehicle control including a control unit configured to execute: acquiring a drive torque a predetermined time before the point when backlash elimination is started; acquiring a backlash elimination torque; calculating a backlash elimination time according to the drive torque from the predetermined time before, the backlash elimination torque, and a map stored in a storage unit; outputting the backlash elimination torque from the point when backlash elimination is started until the backlash elimination time elapses; and increasing the drive torque from the point when the backlash elimination time elapses.

Effects of the Invention

[0006] According to this disclosure, it is possible to suppress the generation of shocks and impact noises due to looseness in the assembly. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram of the vehicle according to the embodiment. [Figure 2] This is a time chart showing the changes in accelerator pedal depression, driving torque, and torque applied to the axle when the play-reducing process according to the embodiment is performed. [Figure 3] This flowchart shows the control flow of the play-reducing process in the ECU according to the embodiment. [Modes for carrying out the invention]

[0008] When changing from a braking state to an acceleration state, the positive and negative signs of the driving force reverse. At this time, play in the gears and other components of the vehicle's power transmission path can become compressed, potentially causing shocks and impact noises. This play is caused, for example, by gear backlash. To suppress the shocks and impact noises caused by this play compression, a zero-crossing process is performed to bring the drive torque rise rate closer to zero. However, this zero-crossing process contributes to delaying the acceleration response. Here, the time required to eliminate the play can vary depending on the torsional return speed of the drive system, the play-eliminating torque, and the state of the vehicle. The torsional return speed of the drive system changes depending on the initial regenerative torque, torque rate, and how the accelerator is pressed. Furthermore, the play-eliminating torque changes depending on the conditions, such as when the torque is specified or when the play-eliminating torque is reduced by feedback vibration damping control. In addition, the state of the vehicle changes depending on the driving conditions (e.g., road gradient). However, conventional control systems perform play reduction without taking these factors into consideration. As a result, shocks and impact noises may occur during play reduction, and the rise of drive torque may be delayed.

[0009] Therefore, in one aspect of this disclosure, a vehicle control device outputs a play-reducing torque while play is being eliminated, and increases the drive torque at the moment the play-reducing is complete. This makes it possible to achieve both a reduction in shock and impact noise and an improvement in response. The vehicle control device calculates the play-reducing time from a map and synchronizes the timing of the completion of play-reducing with the timing of the increase in drive torque.

[0010] Therefore, the control unit of the vehicle's control device acquires the drive torque from a predetermined time before the start of play reduction. The start of play reduction is the time when the conditions for play reduction are met, and may be, for example, a time corresponding to the drive torque. The predetermined time is the time during which a drive torque sufficient to determine the time required for play reduction can be obtained. For example, the larger the drive torque before the predetermined time, the longer the time required for play reduction. The control unit also acquires the play reduction torque. The play reduction torque is the torque output during play reduction. This torque is set to a torque that reduces shock and impact noise. The control unit also calculates the play reduction time according to the drive torque before the predetermined time, the play reduction torque, and a map stored in the memory unit. This map is obtained in advance through experiments or simulations and stored in the memory unit. The control unit also outputs the play reduction torque from the start of play reduction until the play reduction time has elapsed. This suppresses the generation of shock and impact noise. The control unit then increases the drive torque from the time the play reduction time has elapsed. In other words, by increasing the drive torque from the moment the play in the suspension is eliminated, the acceleration response can be improved.

[0011] The following describes in detail, with reference to the drawings, embodiments for carrying out this disclosure. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc., of the components described in this embodiment are not intended to limit the scope of this disclosure to those.

[0012] <Embodiment> Figure 1 is a schematic diagram of a vehicle 1 according to an embodiment. The vehicle 1 comprises wheels 2, an accelerator pedal 3, a motor 4, an inverter 5, a transmission 6, a battery 8, and an ECU 100. The vehicle 1 is an electric vehicle that drives the wheels 2 by operating the motor 4, which is powered by the battery 8 via the inverter 5. Note that the vehicle 1 only needs to be a vehicle capable of running on at least the motor 4 (for example, a BEV, PHEV, or HEV). The output shaft 41 of the motor 4 is connected to a clutch 61 provided in the transmission 6. The motor 4 drives the wheels 2 via the output shaft 41, clutch 61, transmission 6, propeller shaft 62, differential gear 63, and axle 64. This causes the vehicle 1 to move.

[0013] Vehicle 1 is capable of regenerative braking using motor 4. When regenerative braking is performed in vehicle 1, motor 4 generates torque in the opposite direction to that during driving. This brakes the wheels 2. At this time, motor 4 functions as a generator, using this torque to supply power to battery 8.

[0014] Vehicle 1 is further equipped with an accelerator sensor 91 that detects the amount the user depresses the accelerator pedal 3. The values ​​detected by these sensors are transmitted to the ECU 100.

[0015] The ECU100 is a computer that controls the drive torque of motor 4. ECU 100 may be composed of multiple computers. ECU 100 includes a control unit 110 and a storage unit 120. The control unit 110 can be implemented by a hardware processor such as a CPU. The control unit 110 may also include RAM, ROM, cache memory, etc. The storage unit 120 is a means for storing information and is composed of a storage medium such as RAM or flash memory. The storage unit 120 stores programs executed by the control unit 110, data used by the program, etc. ECU 100 is an example of a vehicle control device.

[0016] The memory unit 120 of the ECU 100 stores a map (hereinafter referred to as the "backlash reduction time map") 121 for calculating backlash reduction time according to the backlash reduction torque (vertical axis) and the drive torque before a predetermined time (horizontal axis). The backlash reduction time map 121 is obtained by experiment or simulation and stored in the memory unit 120. The predetermined time here is set as the time at which a drive torque sufficient to determine the time required for backlash reduction can be obtained. Alternatively, the predetermined time may be set as the time at which a difference in drive torque occurs according to the pressing speed of the accelerator pedal 3. "Strong accelerator" refers to the time when the accelerator pedal is pressed suddenly from a state in which relatively strong regenerative torque is being generated. In this case, the rate of change of drive torque is relatively high. "Weak accelerator" refers to the time when the accelerator pedal is pressed slowly from a state in which relatively low regenerative torque is being generated. In this case, the rate of change of drive torque is relatively low.

[0017] Figure 2 is a time chart showing the changes in accelerator pedal depression, driving torque, and torque applied to the axle 64 when the play reduction process according to the embodiment is performed. The driving torque is the torque output from the motor 4. In Figure 2, the solid line represents strong acceleration, and the dashed line represents weak acceleration. In Figure 2, T1 represents a predetermined time before T2, the time when play reduction begins. T3 represents the time when play reduction is completed during strong acceleration, and T4 represents the time when play reduction is completed during weak acceleration. Therefore, the time from T2 to T3 is the play reduction time during strong acceleration, and the time from T2 to T4 is the play reduction time during weak acceleration. During the play reduction time, the torque applied to the axle 64 to reduce play becomes 0. In Figure 2, this time is shown as the time of "play reduction during strong acceleration" and "play reduction during weak acceleration". After this period of coasting with strong and weak acceleration, the axle torque changes from a negative value to a positive value.

[0018] As shown in Figure 2, the value of the drive torque at the time point T1 varies depending on the initial regenerative torque and the accelerator operation. Therefore, the arguments of the backlash elimination time map 121 differ for each of the heavy accelerator operation and the light accelerator operation. In the present embodiment, the backlash elimination time can be set from the backlash elimination time map 121 in accordance with the respective arguments.

[0019] Figure 3 is a flowchart illustrating a control flow of backlash elimination processing in the ECU 100 according to the embodiment. The routine illustrated in Figure 3 is repeatedly executed in the ECU 100. In step S101, the control unit 110 acquires the drive torque from a predetermined time ago. The drive torque is stored in the storage unit 120. The predetermined time is obtained in advance through experiments, simulations or the like, and stored in the storage unit 120.

[0020] In step S102, the control unit 110 acquires the backlash elimination torque. The backlash elimination torque is set to be equal to or less than a predetermined allowable torque that can suppress an excessive collision noise or shock during backlash elimination. Specifically, the torque is not an excessive torque that outputs the required driving force, for example, but a torque of a degree sufficient to eliminate backlash. The backlash elimination torque may be a value corresponding to the gear ratio or the travel mode. The backlash elimination torque may be obtained in advance through experiments, simulations or the like, mapped, and stored in the storage unit 120. Note that the backlash elimination torque is may be acquired using a known technique.

[0021] In step S103, the control unit 110 calculates the backlash elimination time. The control unit 110 calculates the backlash elimination time from the backlash elimination time map 121, using the drive torque from the predetermined time ago acquired in step S101 and the backlash elimination torque acquired in step S102 as arguments.

[0022] In step S104, the control unit 110 acquires a state value related to the occurrence of play. For example, it acquires the command value of the drive torque after the accelerator pedal has been pressed as a state value. In step S105, the control unit 110 determines whether or not it is the start of play reduction. This determination is made according to the state acquired in step S104. For example, if the command value of the drive torque reaches a threshold, the control unit 110 determines that it is the start of play reduction. If the control unit 110 makes a positive determination in step S105, the process proceeds to step S106; if it makes a negative determination, this routine terminates. Note that the determination of whether or not it is the start of play reduction is not limited to this method and can also be made using known techniques.

[0023] In step S106, the control unit 110 counts the elapsed time from the start of the play reduction. In step S107, the control unit 110 determines whether the elapsed time counted in step S106 is equal to or greater than the play reduction time calculated in step S103. If the control unit 110 determines in step S107 that the play reduction is complete, the process proceeds to step S108; if it determines in negative terms, the process returns to step S106. In step S108, the control unit 110 determines that the play reduction is complete and terminates this routine. When the control unit 110 determines that the play reduction is complete, it increases the command value of the drive torque.

[0024] As explained above, according to this embodiment, since the backlash reduction time is set according to the conditions, the timing of backlash reduction and the rise of the drive torque can be synchronized. This makes it possible to improve responsiveness while suppressing the generation of impact noise or shock due to backlash. [Explanation of Symbols]

[0025] 1 vehicle 3. Accelerator pedal 4 motors 64 axles 100 ECU 110 Control Unit 120 Storage section

Claims

[Claim 1] To obtain the drive torque from the time when play reduction begins to a predetermined time, To obtain the torque for reducing play, The process involves calculating the play-reducing time according to the drive torque before the predetermined time, the play-reducing torque, and the map stored in the memory unit. The system outputs the play-reducing torque from the time play-reducing is initiated until the play-reducing time has elapsed. The drive torque is increased from the point when the aforementioned play reduction time has elapsed, A vehicle control system comprising a control unit configured to perform the following:

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