Control system of a vehicle

Abstract

This invention provides a vehicle control system that reliably suppresses the impact of backlash elimination in the gears of a power transmission mechanism when the vehicle transitions from deceleration to acceleration or from acceleration to deceleration. The vehicle control system (100) includes: a motor (2) that generates torque for driving the vehicle; a power transmission mechanism (4) configured to transmit the motor torque to the drive wheels (5) of the vehicle via a plurality of gears; an accelerator opening sensor (SN1) that detects the accelerator opening; and a control device (20) configured to calculate a target torque to be generated by the motor, at least based on the accelerator opening, and to control the motor based on the target torque. When the vehicle switches from a deceleration state to an acceleration state, the control device calculates a predicted backlash angle of the gears of the power transmission mechanism after a predetermined time, and temporarily reduces the target torque when the predicted backlash angle becomes a predetermined angle.

Description

Technical Field

[0001] The present invention relates to a control system for a vehicle, which performs control for eliminating backlash of gears in a power transmission mechanism disposed between a drive source and drive wheels. Background Art

[0002] Such a technology is described in, for example, Patent Document 1. Patent Document 1 discloses a technology that, in a scenario where a vehicle accelerates slowly from coasting or deceleration, can speed up the response of drive shaft torque in the gear backlash section, that is, during the elimination of gear backlash in the power transmission mechanism, even if the target torque command value increases slowly. Specifically, in this technology, a final torque command value is calculated based on a value obtained by multiplying a drive shaft torsional angular velocity by a first feedback gain and a value obtained by multiplying a drive shaft torsional angle by a second feedback gain, and a motor is controlled in accordance with the final torque command value.

[0003] Prior Art Documents Patent Documents Patent Document 1: Japanese Patent Laid-Open No. 2017-192248 Summary of the Invention

[0004] Problem to be Solved by the Invention Here, when a vehicle shifts from deceleration to acceleration, backlash elimination is performed among a plurality of gears (such as differential gears, final drive gears, etc.) located within the power transmission mechanism between the motor (the drive source) and the drive wheels. At this time, in the power transmission mechanism, a state transition occurs from the state where gear backlash is eliminated on the drive wheel side to the state where gear backlash is eliminated on the motor side.

[0005] When a vehicle shifts from deceleration to acceleration as described above, shock may occur when eliminating the gear backlash of the power transmission mechanism (in this specification, the term "shock" is used to include vibration and abnormal noise). In order to suppress such shock during backlash elimination, a method may be considered in which the timing when backlash elimination is completed is obtained according to the state of the backlash angle of the gears of the power transmission mechanism, and the torque of the motor is reduced at this timing. However, in this method, due to the time delay from when a torque reduction command is issued to the motor until the motor torque actually decreases, torque reduction at the timing when backlash elimination is completed may sometimes be too late, and shock during backlash elimination cannot be suppressed. For example, communication delay (such as CAN communication delay) among the motor control device, the inverter, and the motor can be considered as a cause of such time delay in the motor.

[0006] In addition, the above description sets forth the problem occurring when a vehicle shifts from deceleration to acceleration, and the same problem also occurs when a vehicle shifts from acceleration to deceleration.

[0007] The present invention was made to solve the problems of the prior art mentioned above, and its object is to provide a vehicle control system that can reliably suppress the impact when the backlash of the gears of the power transmission mechanism is eliminated when the vehicle changes from deceleration to acceleration or from acceleration to deceleration.

[0008] Methods for solving problems To achieve the above objectives, the present invention provides a vehicle control system, characterized by comprising: a motor that generates torque for driving the vehicle; a power transmission mechanism configured to transmit the torque of the motor to the drive wheels of the vehicle via a plurality of gears; an accelerator opening sensor that detects the amount of operation of the accelerator pedal of the vehicle, i.e., the accelerator opening; and a control device configured to calculate a target torque to be generated by the motor, at least based on the accelerator opening, and to control the motor based on the target torque; the control device is configured to: when the vehicle switches from a deceleration state to an acceleration state, calculate a predicted backlash angle of the gears of the power transmission mechanism after a predetermined time, and temporarily reduce the target torque when the predicted backlash angle becomes a predetermined angle.

[0009] In this invention, when the vehicle transitions from deceleration to acceleration, a predicted backlash angle is calculated after a predetermined time for the gears of the power transmission mechanism. When this predicted backlash angle reaches a predetermined value, the target torque is temporarily reduced. By reducing the target torque based on this predicted backlash angle, a command to reduce the motor torque can be issued at an appropriate pre-emptive time. Therefore, when the vehicle transitions from deceleration to acceleration, the actual motor torque can be reliably reduced at the moment backlash elimination of the gears in the power transmission mechanism is completed, and the impact during backlash elimination can be reliably suppressed.

[0010] In this invention, it is preferred that the control device is configured to: increase the target torque before the predicted backlash angle changes to a predetermined angle, and temporarily reduce the corrected target torque when the predicted backlash angle changes to the predetermined angle.

[0011] According to the present invention configured in this way, by making corrections to increase the target torque, the time to eliminate gear backlash can be shortened, thereby improving acceleration response.

[0012] In this invention, it is preferred that the control device is configured to increase the target torque after temporarily reducing it.

[0013] According to the present invention configured in this way, the vehicle can be rapidly accelerated after backlash elimination is completed.

[0014] In this invention, preferably, the control device is configured to: calculate the impact force when the backlash of the gears of the power transmission mechanism is eliminated based on the rotational speed and inertia of the motor; and temporarily reduce the target torque when the predicted backlash angle becomes a predetermined angle if the impact force is above a predetermined value.

[0015] According to the present invention configured in this way, it is possible to temporarily reduce the torque only when the impact force during backlash elimination of the gear is large, that is, only when the impact during backlash elimination becomes a problem.

[0016] In another embodiment, the present invention is a vehicle control system, characterized by comprising: a motor that generates torque for driving the vehicle; a power transmission mechanism configured to transmit the torque of the motor to the drive wheels of the vehicle via a plurality of gears; an accelerator opening sensor that detects the amount of operation of the accelerator pedal of the vehicle, i.e., the accelerator opening; and a control device configured to calculate a target torque to be generated by the motor based at least on the accelerator opening, and to control the motor based on the target torque; the control device is configured to: when the vehicle switches from an acceleration state to a deceleration state, calculate a predicted backlash angle of the gears of the power transmission mechanism after a predetermined time, and temporarily increase the target torque when the predicted backlash angle becomes a predetermined angle.

[0017] According to the present invention configured in this way, when the vehicle changes from acceleration to deceleration, the actual torque of the motor can reliably increase at the moment when the backlash of the gears in the power transmission mechanism is eliminated, and the impact during the elimination of backlash can be reliably suppressed.

[0018] In this invention, it is preferred that the control device is configured to: reduce the target torque before the predicted backlash angle changes to a predetermined angle, and temporarily increase the corrected target torque when the predicted backlash angle changes to the predetermined angle.

[0019] According to the present invention configured in this way, by making corrections to reduce the target torque, the time to eliminate gear backlash can be shortened, thereby improving deceleration response.

[0020] In this invention, it is preferable that the control device is configured to reduce the target torque after temporarily increasing it.

[0021] According to the present invention configured in this way, the vehicle can be rapidly decelerated after backlash elimination is completed.

[0022] In this invention, preferably, the control device is configured to: calculate the impact force when the backlash of the gears of the power transmission mechanism is eliminated based on the rotational speed and inertia of the motor; and temporarily increase the target torque when the predicted backlash angle changes to a predetermined angle if the impact force is above a predetermined value.

[0023] According to the present invention configured in this way, it is possible to control the torque to temporarily increase only when the impact force during backlash elimination of the gear is large, that is, only when the impact during backlash elimination becomes a problem.

[0024] In this invention, it is preferred that the control device is configured to calculate and predict the backlash angle based on the torsional angle of the drive shaft connected to the drive wheel and the shift of the target torque.

[0025] According to the present invention configured in this way, the predicted backlash angle of the gears in a power transmission mechanism can be calculated with high precision.

[0026] In this invention, preferably, the time for calculating the predicted backlash angle is based on the time delay from when the control device issues a command to the motor (including the inverter) to generate the target torque until the motor actually generates the target torque.

[0027] By reducing or increasing the target torque based on the predicted backlash angle specified by such a time, the actual torque of the motor can be reliably reduced or increased at the moment when backlash elimination is completed.

[0028] Invention Effects According to the vehicle control system of the present invention, when the vehicle changes from deceleration to acceleration or from acceleration to deceleration, the impact of backlash elimination in the gears of the power transmission mechanism can be reliably suppressed. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the configuration of a vehicle control system according to an embodiment of the present invention.

[0030] Figure 2 This is a block diagram illustrating the electrical structure of the vehicle control system according to an embodiment of the present invention.

[0031] Figure 3 This is a timing diagram illustrating the backlash elimination control according to an embodiment of the present invention.

[0032] Figure 4 This is a flowchart illustrating backlash elimination control according to an embodiment of the present invention.

[0033] Figure 5 This is a timing diagram illustrating backlash elimination control in a modified example of the present invention.

[0034] Explanation of reference numerals in the attached figures 1. Engine 2 motors 3. Transmission 4. Power transmission mechanism 5. Wheels (drive wheels) 9 drive shafts 20 Control devices 100 Vehicle control system SN1 Accelerator Opening Sensor SN2 vehicle speed sensor SN3 Motor Speed ​​Sensor Detailed Implementation

[0035] Hereinafter, the vehicle control system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0036] [System Composition] First, refer to Figure 1 and Figure 2 The configuration of the vehicle control system according to this embodiment will be described. Figure 1 This is a schematic diagram illustrating the configuration of the vehicle control system according to this embodiment. Figure 2 This is a block diagram showing the electrical structure of the vehicle control system according to this embodiment.

[0037] like Figure 1 As shown, the vehicle control system 100 of this embodiment is applied to a vehicle (hybrid vehicle) having an engine (internal combustion engine) 1 and a motor 2 as a powertrain PT. In the vehicle control system 100, the motor 2 is located downstream of the engine 1 in the vehicle's power transmission path, a transmission 3 is located downstream of the motor 2, and a power transmission mechanism 4 for transmitting torque (driving force) for driving the vehicle is located downstream of the transmission 3. For example, the transmission 3 is an automatic transmission that uses a torque converter with a lock-up clutch.

[0038] In detail, the output shaft of engine 1 and the rotating shaft of motor 2 are coaxially connected via shaft 6 through a first clutch 11 that can be disconnected or connected. The first clutch 11 is composed of a dry multi-plate clutch or a wet multi-plate clutch, etc., and can change the transmission torque capacity by continuously or stepwise controlling the clutch oil flow and / or clutch oil pressure using a motor or solenoid (not shown). The upstream end of the first clutch 11 is connected to the output shaft of engine 1 via shaft 6a, and the downstream end of the first clutch 11 is connected to the upstream end of the rotating shaft of motor 2 via shaft 6b. In addition, a flywheel with a specified weight may be provided on shaft 6a.

[0039] Furthermore, the rotating shaft of motor 2 and the rotating shaft of transmission 3 are coaxially connected via shaft 7 through a second clutch 12 that can be disengaged or reconnected. Similar to the first clutch 11, the second clutch 12 is also constructed of a dry multi-plate clutch or a wet multi-plate clutch, and can continuously or progressively control the clutch oil flow and / or clutch oil pressure using a motor or solenoid (not shown) to change the transmitted torque capacity. The upstream end of the second clutch 12 is connected to the downstream end of the rotating shaft of motor 2 via shaft portion (first shaft portion) 7a, and the downstream end of the second clutch 12 is connected to the rotating shaft of transmission 3 via shaft portion (second shaft portion) 7b. Furthermore, the second clutch 12 can be formed inside transmission 3, as long as it allows for at least disengaged or reconnected torque transmission between motor 2 and transmission 3.

[0040] Furthermore, the power transmission mechanism 4 receives torque via the output shaft 8 of the transmission 3 and transmits this torque to the wheels (drive wheels) 5 via the drive shaft (drive shaft) 9. The power transmission mechanism 4 is configured to include multiple gears from the transmission 3 to the drive shaft 9, such as differential gears and end-drive gears that distribute torque to a pair of left and right wheels 5. Shafts 6, 7, 8, and 9 are all formed in a manner capable of torsional deformation; in particular, the drive shaft 9 has the characteristic of being modelable using a spring-mass model.

[0041] Next, as Figure 2 As shown, the vehicle control system 100 of this embodiment also includes a control device 20 based on a known microcomputer and composed of circuits. The control device 20 includes one or more processors 20a that serve as a central processing unit (CPU) for executing programs, a memory 20b consisting of, for example, RAM (Random Access Memory) or ROM (Read Only Memory) that stores programs and data, and an input / output bus for inputting and outputting electrical signals. For example, the control device 20 may be composed of an ECU (Electronic Control Unit).

[0042] The control device 20 primarily receives signals from the accelerator pedal opening sensor SN1, vehicle speed sensor SN2, and motor speed sensor SN3, and outputs control signals based on these signals to control the motor 2. The accelerator pedal opening sensor SN1 detects the amount of operation by the driver on the accelerator pedal, i.e., the accelerator opening; the vehicle speed sensor SN2 detects the vehicle speed; and the motor speed sensor SN3 detects the rotational speed of the motor 2. Essentially, the control device 20 calculates the target torque to be generated by the motor 2 based at least on the accelerator pedal opening, and controls the motor 2 based on this target torque. In particular, in this embodiment, when the vehicle transitions from deceleration to acceleration, the control device 20 controls the torque of the motor 2 (backlash elimination control) to eliminate backlash in the multiple gears within the power transmission mechanism 4. Specifically, the torque of the motor 2 is controlled in a manner that achieves shock suppression and improved acceleration responsiveness during backlash elimination. Furthermore, the control device 20 initiates backlash elimination control essentially based on the accelerator pedal operation performed by the driver, preferably further utilizing a request from ADAS (Advanced Driver-Assistance Systems).

[0043] In addition, Figure 1 The invention is shown as an example of applying the invention to a hybrid vehicle having an engine 1 and a motor 2 as power sources, but the invention can also be applied to electric vehicles that do not have an engine 1 but only have a motor 2 as power sources.

[0044] [Backlash Elimination Control] Next, in this embodiment, the backlash elimination control performed by the control device 20 will be described. In this embodiment, when the vehicle transitions from deceleration to acceleration, the control device 20 temporarily reduces the torque of the motor 2 at the moment backlash elimination is completed in order to suppress the impact generated during backlash elimination of the gears in the power transmission mechanism 4. If the torque is temporarily reduced at the moment backlash elimination is completed in this way, the impact during backlash elimination can be offset, that is, the impact force when the gear backlash is completely eliminated (hereinafter referred to as "backlash elimination impact force") can be offset.

[0045] To achieve the aforementioned control, it can be said that the moment of backlash elimination is determined based on the backlash angle of the gears in the power transmission mechanism 4, and the torque of the motor 2 is reduced at that moment. However, due to the time delay from issuing the command to reduce the torque to the actual reduction of the motor 2's torque, sometimes reducing the torque only at the moment of backlash elimination may not be timely enough to suppress the impact during backlash elimination. For example, the causes of this time delay include the communication delay between the control device 20 and the motor 2 (including the inverter) (communication delay of CAN, etc.), and the time delay from when the motor 2 receives the command to when it actually outputs torque.

[0046] Therefore, in this embodiment, the control device 20 calculates the predicted backlash angle of the gear in the power transmission mechanism 4 after a predetermined time. When this predicted backlash angle becomes a predetermined angle (for example, corresponding to the backlash angle before backlash elimination is completed), the target torque used to control the motor 2 is temporarily reduced. This predicted backlash angle is not the current backlash angle of the gear in the power transmission mechanism 4, but rather a backlash angle that is advanced by the time corresponding to the aforementioned time delay (that is, a backlash angle that advances the current backlash angle by that time). By reducing the target torque based on such a predicted backlash angle, a command to reduce the torque of the motor 2 can be issued at an appropriate time in advance. As a result, the actual torque of the motor 2 can be reliably reduced at the moment backlash elimination is completed, and the impact during backlash elimination can be reliably suppressed.

[0047] In this embodiment, the control device 20 uses a model capable of estimating various states of the drive system (including at least the power transmission mechanism 4, drive shaft 9, etc.) based on the input torque to calculate (estimate) the torsion angle of the drive shaft 9, the backlash angle of the gears in the power transmission mechanism 4, etc. Specifically, the control device 20 uses the torque (target torque) of the motor 2, driving resistance, etc., as inputs, and further uses the motor speed to compensate for model errors, to calculate the torsion angle of the drive shaft 9 and the current backlash angle (hereinafter referred to as "estimated backlash angle"). Furthermore, based on these torsion angles and backlash angles, the control device 20 controls the torque of the motor 2 (F / B control) at least during the backlash elimination process of the gears. Moreover, in this embodiment, the control device 20 calculates the predicted backlash angle of the gears in the power transmission mechanism 4 after a predetermined time based on the shift of the torsion angle of the drive shaft 9 and the target torque of the motor 2 (changes over time). And, as described above, the control device 20 temporarily reduces the target torque when the predicted backlash angle becomes a predetermined angle.

[0048] Furthermore, it is not limited to calculating the torsion angle of the drive shaft 9; the torsion angle of the drive shaft 9 can also be detected by a sensor.

[0049] Next, refer to Figure 3 A timing diagram illustrating the backlash elimination control of this embodiment will be explained. Figure 3 The following parameters are shown from top to bottom: accelerator opening, torsion angle of drive shaft 9, backlash angle of gears in power transmission mechanism 4 (obtained by summing the backlash of multiple gears), target torque of motor 2, and actual torque of motor 2. Furthermore, in... Figure 3 In the diagram, solid lines represent the time-varying parameters of the basic backlash elimination control (which also partially includes the backlash elimination control of this embodiment), while dashed and single-dotted lines represent the time-varying characteristic parameters of the backlash elimination control of this embodiment. In particular, single-dotted lines represent the predicted backlash angle and the target torque that is temporarily reduced.

[0050] First, at time t1, the accelerator opening begins to increase, and along with this, the target torque begins to increase. Immediately following at time t2, the actual torque begins to increase. Then, at time t3, the backlash of the gears in the power transmission mechanism 4 begins to be eliminated; that is, the backlash angle begins to change. During this change in backlash angle, the torsional angle of the drive shaft 9 becomes 0. In this embodiment, a correction to increase the target torque is performed just before time t3 (arrow A11), so that the actual torque increases at time t3 when backlash elimination begins (arrow A12), thereby applying a larger torque during backlash elimination to shorten the backlash elimination time. Specifically, a correction is performed to increase the target torque by a predetermined torque (increasing the base value). According to this embodiment of correcting the target torque in this way, compared to the case without correcting the target torque (hereinafter referred to as the "comparative example"), the rate of change of the backlash angle is faster (refer to arrow A14 in this embodiment, and arrow A15 in the comparative example).

[0051] Furthermore, in this embodiment, starting from time t3, based on the torsion angle of the drive shaft 9 and the shift of the target torque, the predicted backlash angle of the gear in the power transmission mechanism 4 is calculated after a predetermined time (e.g., 10 to 50 ms later) (arrow A13). Then, at time t4, the predicted backlash angle reaches a predetermined angle An1 (close to the backlash angle at which backlash elimination is completed), thereby temporarily reducing the target torque; specifically, the target torque is reduced in a pulse-like manner (arrow A16). For example, based on the inertia of the motor 2 and the current motor speed, the amount and duration of the reduction in target torque are set so that the motor speed (rotational speed) is temporarily 0 when the gear backlash is eliminated.

[0052] If the target torque is temporarily reduced at time t4 as described above, the actual torque will also temporarily decrease at the subsequent time t5 (arrow A17). Therefore, at time t6, when backlash elimination is completed (at which point the actual backlash angle (arrow A14) reaches its maximum), the actual torque decreases. As a result, the impact during backlash elimination can be suppressed. Furthermore, in this embodiment, at time t6, the torsion angle of the drive shaft 9 increases (arrow A18) because backlash elimination is completed. In contrast, in the comparative example, the torsion angle of the drive shaft 9 only increases at time t7, after time t6 (arrow A19). Therefore, according to this embodiment, the backlash elimination time is shorter than in the comparative example, resulting in higher acceleration response.

[0053] Next, refer to Figure 4A flowchart illustrating the backlash elimination control of this embodiment will be described. This process is repeatedly executed by the control device 20 at a predetermined cycle. Specifically, the processor 20a within the control device 20 reads the program stored in the memory 20b and executes the program, thereby realizing the control involved in this process.

[0054] First, in step S11, the control device 20 acquires various information from the vehicle's control system 100. In particular, the control device 20 acquires the accelerator opening detected by the accelerator opening sensor SN1, the vehicle speed detected by the vehicle speed sensor SN2, and the motor speed detected by the motor speed sensor SN3.

[0055] Next, in step S12, the control device 20 calculates the target torque to be generated by the motor 2 based on the accelerator opening and vehicle speed obtained in step S11. For example, the control device 20 uses a mapping defined by the accelerator opening and vehicle speed to determine the target acceleration corresponding to the current accelerator opening and vehicle speed, and calculates the target torque to achieve the target acceleration. Preferably, the control device 20 calculates the target jump in a way that makes the acceleration change smoothly according to the rate of change of the accelerator opening, and calculates the target torque based on the target jump in addition to the target acceleration.

[0056] Next, in step S13, the control device 20 uses a model capable of estimating various states of the drive system to calculate the estimated backlash angle of the gears in the power transmission mechanism 4. Specifically, the control device 20 uses the torque (target torque) of the motor 2, driving resistance, etc., as inputs, and takes into account the current motor speed (obtained in step S11) to compensate for model errors, to calculate the estimated backlash angle, and calculates the torsional angle of the drive shaft 9.

[0057] Next, in step S14, the control device 20 calculates the predicted backlash angle of the gears in the power transmission mechanism 4 after a predetermined time. Specifically, the control device 20 calculates the predicted backlash angle after a predetermined time based on the torsional angle of the drive shaft 9 and the shift of the target torque (as time changes). The predetermined time for calculating this predicted backlash angle is based on the time delay (e.g., including communication delays such as CAN) from when the control device 20 issues a command to the motor 2 to generate the target torque until the motor 2 actually generates the target torque. For example, this predetermined time can be 10 to 50 ms.

[0058] Next, in step S15, the control device 20 determines whether the gear of the power transmission mechanism 4 will pass through the backlash region. Specifically, the control device 20 determines whether the gear will pass through the backlash region from the deceleration side to the acceleration side. Specifically, the control device 20 determines whether the target torque will subsequently cross 0 (N) based on the change in target torque calculated in step S12 (determining whether the target torque crosses 0 in the direction from negative to positive), thus performing this determination in step S15. If the result of step S15 is that the control device 20 determines that the gear will pass through the backlash region (step S15: Yes), the process proceeds to step S16; if it does not determine that the gear will pass through the backlash region (step S15: No), the process exits.

[0059] Next, in step S16, the control device 20 determines whether the impact force (backlash elimination impact force) when the backlash of the gears in the power transmission mechanism 4 is completely eliminated is above a predetermined value. Here, the control device 20 determines whether a relatively large backlash elimination impact will occur, requiring a temporary reduction in the torque of the motor 2 to cope with it. Furthermore, the control device 20 calculates the backlash elimination impact force based on the inertia and rotational speed of the motor 2. If the result of step S16 is that the control device 20 determines the backlash elimination impact force is above the predetermined value (step S16: Yes), then proceeds to step S17 to temporarily reduce the torque of the motor 2. Conversely, if the control device 20 does not determine that the backlash elimination impact force is above the predetermined value (step S16: No), that is, if the backlash elimination impact force is less than the predetermined value, then since a temporary reduction in the torque of the motor 2 is not required, the process exits.

[0060] Next, in step S17, the control device 20 determines whether the predicted backlash angle calculated in step S14 has reached a predetermined angle An1. This predetermined angle An1 uses a backlash angle close to the point at which backlash elimination is achieved; it is preset so that if the torque is reduced at this angle, the backlash elimination impact can be reliably offset. If the result of step S17 is that the control device 20 determines that the predicted backlash angle has reached the predetermined angle An1 (step S17: Yes), it proceeds to step S18. Conversely, if the control device 20 does not determine that the predicted backlash angle has reached the predetermined angle An1 (step S17: No), it returns to step S17. In this case, the control device 20 repeatedly performs the determination in step S17 until the predicted backlash angle reaches the predetermined angle An1.

[0061] Next, in step S18, in order to suppress the impact during backlash elimination, the control device 20 temporarily reduces the target torque; specifically, the target torque is reduced in a pulsed manner. For example, the control device 20 temporarily reduces the target torque by a pre-set reduction amount and reduction time (10-20 ms in one example).

[0062] [Functions and Effects] Next, the operation and effects of the vehicle control system 100 of this embodiment will be explained. According to this embodiment, the control device 20 calculates the target torque based at least on the accelerator opening, and controls the motor 2 based on this target torque. Furthermore, when the vehicle switches from a deceleration state to an acceleration state, it calculates the predicted backlash angle of the gears in the power transmission mechanism 4 after a predetermined time, and temporarily reduces the target torque when the predicted backlash angle becomes a predetermined angle An1. By reducing the target torque based on such a predicted backlash angle, a command to reduce the torque of the motor 2 can be issued at an appropriate pre-emptive time. Therefore, the actual torque of the motor 2 can be reliably reduced at the moment backlash elimination is completed, and the impact during backlash elimination can be reliably suppressed.

[0063] Furthermore, according to this embodiment, the control device 20 performs a correction to increase the target torque before the predicted backlash angle becomes a predetermined angle An1, and temporarily reduces the corrected target torque when the predicted backlash angle becomes the predetermined angle An1. By performing this correction to increase the target torque, the time to eliminate gear backlash can be shortened, and acceleration response can be improved.

[0064] Furthermore, according to this embodiment, the control device 20 increases the target torque after temporarily reducing it. This allows the vehicle to accelerate rapidly after backlash elimination is completed.

[0065] Furthermore, according to this embodiment, the control device 20 calculates the impact force (backlash elimination impact force) during backlash elimination of the gears in the power transmission mechanism 4 based on the motor speed and the inertia of the motor 2. When the impact force is above a predetermined value, the target torque is temporarily reduced when the predicted backlash angle becomes a predetermined angle An1. Thus, the control to temporarily reduce the torque can be performed only when the backlash elimination impact force is large, that is, only when the impact during backlash elimination becomes a problem.

[0066] Furthermore, according to this embodiment, the control device 20 calculates the predicted backlash angle based on the torsional angle of the drive shaft 9 and the shift of the target torque. Therefore, the predicted backlash angle of the gears in the power transmission mechanism 4 can be calculated with high accuracy.

[0067] Furthermore, according to this embodiment, the predetermined time for calculating the predicted backlash angle is determined based on the time delay from when the control device 20 issues a command to the motor 2 to generate the target torque until the motor 2 actually generates the target torque. By reducing the target torque based on the predicted backlash angle determined by such a predetermined time, the actual torque of the motor 2 can be reliably reduced at the moment when backlash elimination is completed.

[0068] [Variation Example] In the above embodiments, backlash elimination control during the transition from deceleration to acceleration of the vehicle has been described, and this backlash elimination control can also be performed during the transition from acceleration to deceleration. (See also...) Figure 5 A timing diagram illustrating backlash elimination control in a modified example of this embodiment will be explained. Figure 5 The following parameters are shown from top to bottom: accelerator opening, torsion angle of drive shaft 9, backlash angle of gears in power transmission mechanism 4 (obtained by summing the backlash of multiple gears), target torque of motor 2, and actual torque of motor 2. Furthermore, in... Figure 5 In the diagram, solid lines represent the time-varying parameters of the basic backlash elimination control (which also partially includes the backlash elimination control of the modified examples of this embodiment), while dashed lines and single-dot lines represent the time-varying characteristic parameters of the backlash elimination control of the modified examples of this embodiment. In particular, single-dot lines represent the predicted backlash angle and the temporarily increased target torque.

[0069] First, at time t1, the accelerator opening begins to decrease, and consequently, the target torque begins to decrease. At the following time t2, the actual torque begins to decrease. Then, at time t3, the backlash of the gears in the power transmission mechanism 4 begins to disappear; that is, the backlash angle begins to change. During this change in backlash angle, the torsional angle of the drive shaft 9 becomes 0. In a modified example, a correction to reduce the target torque is performed just before time t3 (arrow A21), so that the actual torque is reduced at time t3 when backlash elimination begins (arrow A22). This allows for the application of a smaller torque during backlash elimination, shortening the backlash elimination time. Specifically, a correction is made to lower the target torque by a predetermined torque (reducing the base value). According to this modified example of target torque correction, compared to the case without target torque correction (hereinafter referred to as the "comparative example"), the rate of change of the backlash angle is faster (see arrow A24 in the modified example and arrow A25 in the comparative example).

[0070] In a modified example, starting from time t3, based on the torsion angle of the drive shaft 9 and the shift of the target torque, the predicted backlash angle of the gear in the power transmission mechanism 4 is calculated after a predetermined time (e.g., 10-50 ms later) (arrow A23). Then, at time t4, the predicted backlash angle reaches a predetermined angle An2 (close to the backlash angle at which backlash elimination is completed), causing the target torque to temporarily increase; specifically, the target torque increases in a pulse-like manner (arrow A26). For example, based on the inertia of the motor 2 and the current motor speed, the increase in the target torque and the increase time are set so that the motor speed (rotational speed) is temporarily 0 when the gear backlash is eliminated.

[0071] If the target torque is temporarily increased at time t4 as described above, the actual torque will also temporarily increase at the subsequent time t5 (arrow A27). Therefore, at time t6, when backlash elimination is complete (at which point the actual backlash angle (arrow A24) reaches its minimum), the actual torque increases. As a result, the impact during backlash elimination can be suppressed. Furthermore, in the modified example, at time t6, the torsional angle of the drive shaft 9 decreases due to the completion of backlash elimination (arrow A28). In contrast, in the comparative example, the torsional angle of the drive shaft 9 decreases only at time t7, after time t6 (arrow A29). Therefore, according to the modified example, the backlash elimination time is shorter than that of the comparative example, indicating a higher deceleration response.

Claims

1. A vehicle control system, characterized in that, have: A motor, which generates torque to drive a vehicle; A power transmission mechanism configured to transmit the torque of the motor to the drive wheels of the vehicle via a plurality of gears; An accelerator pedal operation sensor detects the amount of accelerator pedal operation, i.e., the accelerator pedal opening; and A control device configured to calculate, at least based on the accelerator opening, a target torque to be generated by the motor, and to control the motor based on the target torque; The control device is configured to: when the vehicle switches from a deceleration state to an acceleration state, calculate the predicted backlash angle of the gears of the power transmission mechanism after a predetermined time, and temporarily reduce the target torque when the predicted backlash angle becomes a predetermined angle.

2. The vehicle control system according to claim 1, characterized in that, The control device is configured to: increase the target torque before the predicted backlash angle becomes the predetermined angle, and temporarily reduce the corrected target torque when the predicted backlash angle becomes the predetermined angle.

3. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured to temporarily reduce the target torque and then increase the target torque.

4. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured to: calculate the impact force when the backlash of the gears of the power transmission mechanism is eliminated based on the rotational speed and inertia of the motor; and temporarily reduce the target torque when the predicted backlash angle becomes the predetermined angle if the impact force is above a specified value.

5. A vehicle control system, characterized in that, have: A motor, which generates torque to drive a vehicle; A power transmission mechanism configured to transmit the torque of the motor to the drive wheels of the vehicle via a plurality of gears; An accelerator pedal operation sensor detects the amount of accelerator pedal operation, i.e., the accelerator pedal opening; and A control device configured to calculate, at least based on the accelerator opening, a target torque to be generated by the motor, and to control the motor based on the target torque; The control device is configured to: when the vehicle switches from an acceleration state to a deceleration state, calculate the predicted backlash angle of the gears of the power transmission mechanism after a predetermined time, and temporarily increase the target torque when the predicted backlash angle becomes a predetermined angle.

6. The vehicle control system according to claim 5, characterized in that, The control device is configured to: reduce the target torque before the predicted backlash angle becomes the predetermined angle, and temporarily increase the corrected target torque when the predicted backlash angle becomes the predetermined angle.

7. The vehicle control system according to claim 5 or 6, characterized in that, The control device is configured to temporarily increase the target torque and then decrease the target torque.

8. The vehicle control system according to claim 5 or 6, characterized in that, The control device is configured to: calculate the impact force when the backlash of the gears of the power transmission mechanism is eliminated based on the rotational speed and inertia of the motor; and when the impact force is above a predetermined value, temporarily increase the target torque when the predicted backlash angle becomes the predetermined angle.

9. The vehicle control system according to claim 1 or 5, characterized in that, The control device is configured to calculate the predicted backlash angle based on the torsional angle of the drive shaft connected to the drive wheel and the shift of the target torque.

10. The vehicle control system according to claim 1 or 5, characterized in that, The specified time for calculating the predicted backlash angle is defined based on the time delay from when the control device issues a command to the motor to generate the target torque until the motor actually generates the target torque.

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