Vehicle control device, vehicle control method, and vehicle control system

Abstract

When the electric vehicle is decelerated, the driving force is increased by the rear motor, and when the parking time becomes zero, a control command for reducing the driving force increased by the rear motor is output.

Description

Technical Field

[0001] The invention relates to a vehicle control device, a vehicle control method and a vehicle control system. Background Art

[0002] Patent document 1 discloses the following technology: for the purpose of suppressing pitching changes of a vehicle just before it stops, a physical quantity related to the vehicle speed and a physical quantity related to the required braking force required to decelerate the vehicle are obtained, and when the vehicle is decelerated based on the physical quantity related to the required braking force, a driving force is generated by a driving device while a friction braking force is being generated.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-056583 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, in the above-mentioned conventional vehicle control device, after the driving force is generated, if the vehicle speed becomes below the specified speed and a specified time passes, a parking judgment is made and the generated driving force is reduced. Therefore, when the actual braking force actually generated by the vehicle is smaller than the estimated total braking force, there is a concern that the braking distance will increase.

[0008] One of the objects of the present invention is to provide a vehicle control device, a vehicle control method, and a vehicle control system that can achieve both suppression of pitch variation and suppression of increase in braking distance when a vehicle is parked.

[0009] Means for solving problems

[0010] A vehicle control device in one embodiment of the present invention increases driving force by a driving device, and when a physical quantity related to a parking target reaches a reference value, outputs a control command for reducing the driving force increased by the driving device.

[0011] According to one embodiment of the present invention, it is possible to achieve both suppression of pitch fluctuation and suppression of increase in braking distance when the vehicle stops. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of an electric vehicle 1 equipped with the vehicle control system according to the first embodiment.

[0013] Figure 2 This is a control block diagram of the rear motor 7 according to the first embodiment.

[0014] Figure 3 This is a control block diagram of the total braking torque calculation unit 34 according to the first embodiment.

[0015] Figure 4 This is a control block diagram of the control gain calculation unit 35 according to the first embodiment.

[0016] Figure 5 This is a control block diagram of the addition torque calculation unit 37 according to the first embodiment.

[0017] Figure 6 This is a control block diagram of the parking determination unit 54 according to the first embodiment.

[0018] Figure 7 This is a control block diagram of the control gain rate limiting unit 55 according to the first embodiment.

[0019] Figure 8 3 is a time chart of the vehicle speed, control gain, and rear motor torque in the comparative example.

[0020] Fig. 9 This is a time chart of the vehicle speed, the control gain, and the rear motor torque in the anti-jerk control of the first embodiment.

[0021] Fig.10 It is a time diagram of motor speed and stopping time under the assumed braking state.

[0022] Fig.11 It is a time diagram of motor speed and stopping time in the presence of motor vibration.

[0023] Fig.12 This is a control block diagram of the friction brake 3 according to the second embodiment.

[0024] Fig.13 This is a control block diagram of the total braking torque calculation unit 93 according to the second embodiment.

[0025] Fig.14 This is a control block diagram of the subtraction braking force calculation unit 94 according to the second embodiment.

[0026] Fig.15 It is a time chart of the vehicle speed, the control gain, and the rear motor torque in the anti-jerk control according to the second embodiment. DETAILED DESCRIPTION

[0027] [Implementation method 1]

[0028] Figure 1 This is a schematic diagram of an electric vehicle 1 equipped with the vehicle control system according to the first embodiment.

[0029] The electric vehicle 1 has front wheels 2FL, 2FR and rear wheels 2RL, 2RR; and friction brakes (friction brake devices) 3FL, 3FR, 3RL, 3RR provided on each wheel and generating friction braking force on the wheel (hereinafter, the friction brakes of each wheel are also collectively referred to and recorded as friction brakes 3).

[0030] The electric vehicle 1 has a rear motor (drive device) 7 that outputs torque to the rear wheels 2RL and 2RR. The rear wheels 2RL and 2RR are also collectively referred to and described as drive wheels 2. Power is transmitted between the rear motor 7 and the rear wheels 2RL and 2RR via a speed reducer 8, a differential 10, and rear axles 6RL and 6RR.

[0031] Each wheel 2FL, 2FR, 2RL, 2RR has a wheel speed sensor 11FR, 11FL, 11RL, 11RR for detecting the wheel speed. The rear motor 7 has a rear wheel resolver 13 for detecting the motor speed (motor speed). In addition, the electric vehicle 1 has a G sensor 5 for detecting the acceleration of the vehicle in the front-rear direction (hereinafter, also referred to as acceleration).

[0032] The friction brake 3 presses the brake pad in the direction of the rotation axis of each wheel relative to the brake rotor that rotates integrally with each wheel, and generates a braking force by friction. The friction brake 3 of the first embodiment is described as a structure in which the brake pad is pressed by a wheel cylinder that works by brake hydraulic pressure, but it can also be set as a structure in which the brake pad is pressed by a ball screw mechanism driven by an electric motor, etc., without special limitation.

[0033] The electric vehicle 1 includes a low voltage power supply (battery) 14 and a high voltage power supply 15. The low voltage power supply 14 is, for example, a lead storage battery. The high voltage power supply 15 is, for example, a lithium ion battery or a nickel metal hydride battery. The high voltage power supply 15 is charged by power boosted by a DC-DC converter 16.

[0034] The electric vehicle 1 includes a vehicle control device (control unit) 17, a brake control device 18, a rear motor control device 20, and a power supply control device 19. The control devices 17, 18, and 20 share information with each other via a CAN bus 21.

[0035] The vehicle control device 17 obtains information from various sensors such as the rear wheel rotary transformer 13, the accelerator pedal sensor 22 for detecting the accelerator operation amount, the brake sensor 23 for detecting the brake operation amount, and the gear position sensor 24, and performs comprehensive control of the vehicle. The vehicle control device 17 outputs the driver's required torque to be output by the rear motor 7 according to the required torque distribution according to the driver's acceleration operation, brake operation, etc.

[0036] The brake control device 18 obtains information from various sensors such as the brake sensor 23 to set a torque conversion value of the target braking force of the vehicle, namely a target brake torque, generates brake hydraulic pressure required for each wheel according to the target brake torque, and outputs it to the friction brake 3 through the hydraulic pipe 18a.

[0037] The power supply control device 19 monitors the charge and discharge state of the high voltage power supply 15 and the single battery unit (cell) constituting the high voltage power supply 15. The power supply control device 19 calculates the power supply required torque limit value based on the charge and discharge state of the high voltage power supply 15, etc. The power supply required torque limit value is the maximum torque allowed in the rear motor 7. For example, when the charge amount of the high voltage power supply 15 decreases, the power supply required torque limit value is set to a value smaller than usual.

[0038] The rear motor control device 20 controls the electric power supplied to the rear motor 7 based on the rear required torque.

[0039] In the electric vehicle 1 of the first embodiment, the following anti-jerk control is implemented for the purpose of suppressing the uncomfortable shaking of the vehicle when parking and reducing the fatigue of the passengers: the rear motor 7 outputs a driving torque equivalent to the total braking torque obtained by estimating the braking torque actually generated in the vehicle when parking. As a result, the front and rear jerk (acceleration) generated when parking under a fixed brake operation amount can be reduced by about 68% compared with the case without anti-jerk control. That is, even without a clever brake operation, smooth parking can be achieved.

[0040] Figure 2 This is a control block diagram of the rear motor 7 according to the first embodiment.

[0041] The driver requested torque calculation unit 31 calculates the driver requested torque based on the accelerator operation amount and the vehicle speed. The wheel speed is obtained by any appropriate method based on the wheel speeds detected by the wheel speed sensors 11FR, 11FL, 11RL, and 11RR, but is obtained by referring to the motor speed detected by the rear wheel resolver 13 at low speeds.

[0042] The slope resistance calculation unit 32 calculates the resistance acting on the vehicle due to the road surface slope, i.e., the slope resistance, based on the vehicle speed, the G sensor value, and the vehicle weight. Specifically, the estimated slope acceleration due to the slope is obtained based on the deviation between the differential value of the vehicle speed and the G sensor value, and the slope resistance is calculated based on the estimated slope acceleration due to the slope and the vehicle weight.

[0043] The estimated friction braking force correction gain calculation unit 33 calculates a final correction gain for correcting an estimation error of the estimated friction braking force accompanying a change in pad μ (friction coefficient) based on the G sensor value, vehicle speed, estimated friction braking force, running resistance, vehicle weight, motor torque, and brake pad temperature. If the pad μ changes due to temperature change, humidity change, etc., the estimated friction braking force will deviate from the braking force actually applied to the vehicle by the brake. Therefore, the pad μ is estimated, and a gain for correcting the estimated friction braking force (torque conversion value) is calculated in order to offset the error of the estimated pad μ relative to the nominal value of the pad μ.

[0044] The estimated friction braking force is obtained as the sum of the estimated friction braking forces of the wheels. The estimated friction braking force Bi of each wheel is calculated using the following formula (1).

[0045] Estimated friction braking force of each wheel Bi = brake fluid pressure × hydraulic cylinder area × brake effective radius × block μ (nominal value)… (1)

[0046] Here, once the nominal value of the block μ is set, it will not be changed during driving. For the nominal value, the temperature-μ characteristic of the brake pad is obtained in advance as a map, and the map is used to set it. The temperature of the brake pad when calculating the nominal value can be the outside air temperature at the start of driving, or a predetermined temperature (for example, 20°C) can be used.

[0047] The running resistance may be calculated based on changes in the running resistance with respect to changes in the vehicle weight or the vehicle speed, or may be estimated.

[0048] The estimated friction braking force may be estimated based on the amount of stroke of the driver's brake pedal instead of the brake fluid pressure.

[0049] The total braking torque calculation section 34 calculates the total braking torque based on the running resistance, the estimated friction braking force, the gradient resistance, and the final correction gain. Figure 3 This is a control block diagram of the total braking torque calculation unit 34 of the first embodiment. The braking force torque conversion unit 41 converts the estimated friction braking force into the estimated friction braking torque. The multiplier 42 multiplies the estimated friction braking torque by the final correction gain to calculate the corrected estimated friction braking torque that corrects the estimated error associated with the change in μ of the brake pad. The first adder 43 and the second adder 44 add the torque equivalent to the slope resistance and the torque equivalent to the running resistance to the corrected estimated friction braking torque. The limiter 45 compares the value obtained by adding the torque equivalent to the slope resistance and the torque equivalent to the running resistance to the corrected estimated friction braking torque with 0, and outputs the larger value as the total braking torque.

[0050] The control gain calculation section 35 calculates a control gain based on the vehicle speed, the total braking torque, the vehicle weight, and the estimated friction braking force. Figure 4 This is a control block diagram of the control gain calculation unit 35 of the first embodiment. The acceleration estimation value calculation unit 51 calculates the acceleration by differentiating the vehicle speed. The acceleration-based control gain map 52 sets the acceleration-based control gain corresponding to the acceleration. In the acceleration-based control gain map 52, in the case of a deceleration whose absolute value is smaller than the predetermined value x2 (G), the acceleration-based control gain is set to 1 (100%). On the other hand, in the case of a deceleration whose absolute value is greater than the predetermined value x2 (G), the acceleration-based control gain is gradually reduced as the absolute value of the deceleration increases. The minimum value of the acceleration-based control gain is 0 (0%). In this way, it is possible to avoid the torque being added during emergency braking. In addition, during emergency braking, it is of course preferable to ensure the braking force rather than suppress the vibration in the pitch direction.

[0051] The speed-based control gain diagram 53 sets the speed-based control gain based on a three-dimensional map corresponding to the vehicle speed and the total braking torque. The speed-based control gain has the following characteristics: only in a specified area near the total braking torque of 0, it decreases linearly as the total braking torque decreases, and in most areas exceeding the specified area, it becomes a maximum value of 1. In addition, the maximum value can also be set to a positive value other than 1. In addition, the speed-based control gain is set to increase linearly as the vehicle speed decreases. And the speed-based control gain is set so that as the total braking torque increases, the vehicle speed at which the value rises from 0 (the gain increase start speed) increases. That is, the speed-based control gain has the following characteristics: as the total braking torque increases, the vehicle speed at which the anti-jerk control instruction intervenes (the vehicle speed at which the driving force starts to be generated by the anti-jerk control) increases.

[0052] The parking determination unit 54 inputs the vehicle speed, the total braking torque, the vehicle weight, and the estimated friction braking force, and clears (clears) (=0) the parking determination flag when the parking time is not 0, and sets (sets) (=1) the parking determination flag when the parking time is 0. The parking determination unit 54 will be described in detail later.

[0053] The control gain rate limiting unit 55 limits the change speed of the control gain on the increase side and the decrease side based on the speed. In addition, when the parking determination flag is set (=1), the change speed limit value on the decrease side used previously is changed. The control gain rate limiting unit 55 will be described in detail later.

[0054] The multiplier 56 outputs a value obtained by multiplying the control gain based on acceleration by the control gain based on speed as a final control gain.

[0055] return Figure 2 The multiplier 36 multiplies the control gain by the total braking torque to calculate the total braking torque after the control gain is multiplied.

[0056] The additional torque calculation unit 37 calculates the additional torque as the anti-jerk control torque based on the driver request torque and the total braking torque after multiplication by the control gain. Figure 5 1 is a control block diagram of the addition torque calculation unit 37 of the first embodiment. The limiter 61 compares the driver request torque with 0 and outputs the larger value. The comparator 62 subtracts the output of the limiter 61 from the total braking torque after multiplication by the control gain. The limiter 63 compares the output of the comparator 62 with 0 and outputs the larger value as the addition torque.

[0057] The adder 38 adds the addition torque to the driver requested torque, and sets the added torque to be the post-requested torque.

[0058] Figure 6 This is a control block diagram of the parking determination unit 54 according to the first embodiment.

[0059] Below the prescribed speed, the parking time calculation unit 71 calculates the time until the vehicle stops in each control cycle (parking target time) based on the vehicle speed and the total braking torque, with reference to the parking time calculation map (parking target time acquisition map) prepared in advance for each vehicle weight. Here, in the anti-jerk control of the first embodiment, the control gain is determined for the vehicle speed and the total braking torque by the speed-based control gain map 53. Therefore, the subsequent deceleration change can be predicted based on the vehicle speed and the total braking torque. Therefore, the parking time calculation map is a map for setting the parking time in consideration of the subsequent acceleration change.

[0060] The last calculated time holding unit 72 holds the parking time estimated in the last control cycle, and forgets the last estimated time when the vehicle speed becomes above the prescribed speed Z1 after the parking time calculated last time becomes below 0, or when the estimated friction braking force becomes 0. In addition, the following structure may be adopted: when the estimated friction braking force becomes below the prescribed value, or when the brake is pressed back to above the prescribed value, the last estimated time is forgotten.

[0061] The comparator 73 calculates the stop time in the current control cycle by subtracting one control execution cycle time from the stop time estimated in the previous control cycle.

[0062] The first limiter 74 compares the parking time calculated by the parking time calculation unit 71 with the parking time calculated based on the parking time estimated in the previous control cycle as the output of the comparator 73 , and outputs the smaller value.

[0063] The second limiter 75 compares the output of the first limiter 74 with 0, and outputs the larger value as the final parking time.

[0064] The parking flag setting unit 76 clears the parking determination flag (=0) when the final parking time is other than 0, and sets the parking determination flag (=1) when the final parking time is 0.

[0065] In addition, the timing of clearing and setting the parking determination flag may not be the timing when the time until the vehicle stops becomes 0, but may be set when the time is below a specified value and cleared when the time is above a specified value.

[0066] Figure 7 This is a control block diagram of the control gain rate limiting unit 55 according to the first embodiment.

[0067] The predetermined time after parking judgment unit 81 calculates the time after the parking judgment flag is set, and clears the predetermined time passing flag (=0) when the predetermined time has not passed, and sets the predetermined time passing flag (=1) when the predetermined time has passed. The first signal switch 82 outputs the output value of the speed-based control gain map 53 when the parking judgment flag is cleared, and outputs 0 when the parking judgment flag is set. The comparator 83 outputs a value obtained by subtracting the previous speed-based control gain from the output of the first signal switch 82. The first limiter 84 compares the predetermined gain increase rate with the output value of the comparator 83, and outputs the smaller value. The second signal switch 85 outputs the predetermined first parking judgment gain reduction rate (first reduction gradient) when the predetermined time passing flag is cleared, and outputs the predetermined second parking judgment gain reduction rate (second reduction gradient) when the predetermined time passing flag is set. The second parking judgment gain reduction rate is set to a value greater than the first parking judgment gain reduction rate.

[0068] The third signal switch 86 outputs the gain reduction rate when the parking determination flag is cleared, and outputs the output value of the second signal switch 85 (the first parking determination gain reduction rate or the second parking determination gain reduction rate) when the parking determination flag is set. The second limiter 87 compares the output value of the third signal switch 86 with the output value of the first limiter 84, and outputs the larger value. The adder 88 outputs the value obtained by adding the previous speed-based control gain to the second limiter 87. The third limiter 89 compares the output value of the adder 88 with 0, and outputs the larger value as the speed-based control gain.

[0069] Here, the prescribed time of the prescribed time elapsed after parking judgment unit 81, the gain reduction rate in the first parking judgment, and the gain reduction rate in the second parking judgment may not be prescribed values, but may be set to a structure that changes according to, for example, the outside air temperature, the oil temperature of the suspension, etc. This is because the response characteristics of the suspension change according to the oil temperature of the suspension, and thus, even if the motor torque is increased, the recovery time of the pitch angle of the vehicle caused by braking will also change, and it will not be possible to set the pitch angle of the vehicle to 0 before parking, and shock may occur when parking. Therefore, at low temperatures, when the pitch angle is difficult to recover, the prescribed elapsed time is extended or the gain reduction rate is reduced (the gain reduction rate in the first parking judgment may be set to 0, and the gain is maintained for a prescribed time), and the motor torque is extended. Thus, by lengthening the time for generating the anti-squat force, the time until the pitch angle returns to 0 after parking can be extended, and the shock can be suppressed.

[0070] Next, the effects of the first embodiment will be described.

[0071] Figure 8 As a comparative example of the first embodiment, after the driving force is generated by the anti-jerk control, if the vehicle speed becomes less than the prescribed speed, a parking judgment is made after a prescribed time, and the generated driving force is reduced, and a time diagram of the vehicle speed, control gain, and rear motor torque is shown. In this comparative example, the increase of the rear motor torque (addition torque) based on the anti-jerk control starts at time t1, but because the torque adapted to the actual braking force is smaller than the estimated total braking torque, the vehicle speed is not reduced to the prescribed speed, and the braking distance is greatly increased.

[0072] Fig. 9 This is a time chart of the vehicle speed, the control gain, and the rear motor torque in the anti-jerk control according to the first embodiment.

[0073] At time t1, the vehicle speed decreases to the anti-jerk control intervention speed, so the added torque increases. The control gain is a value obtained by multiplying the output value of the control gain map 52 based on acceleration by the output value of the control gain map 53 based on speed, but the upper limit of the increase rate and decrease rate of the control gain based on speed is limited to a specified gain increase rate or gain decrease rate.

[0074] At time t2, the parking time calculated by the parking time calculation unit 71 becomes 0, so the control gain rate limiting unit 55 switches the rate of the speed-based control gain from the reduction rate to the first parking determination gain reduction rate, and the added torque starts to decrease.

[0075] At time t3, a predetermined time has passed since the parking time became 0, and therefore, in the control gain rate limiting unit 55, the ratio of the speed-based control gain is switched to a second parking judgment gain reduction rate greater than the first parking judgment gain reduction rate, and the added torque is reduced with a greater gradient.

[0076] At time t4, the anti-jerk control is terminated.

[0077] As described above, the vehicle control device 17 of the first embodiment monitors the physical quantity related to the parking target, and after starting to increase the rear motor torque based on the anti-jerk control, when the physical quantity related to the parking target reaches the reference value, the rear motor torque is reduced. Thus, even when the actual braking force is smaller than the force equivalent to the estimated total braking torque, or when there is an error in the slope estimation, the rear motor torque is reduced if the parking target reaches the reference value. As a result, it is possible to suppress the pitch change when the vehicle stops, and to suppress a significant increase in the braking distance. That is, in the vehicle control device 17 of the first embodiment, it is possible to take into account both the suppression of the pitch change when the vehicle is parked and the suppression of the increase in the braking distance.

[0078] In the first embodiment, the physical quantity related to the parking target is set as the parking time until the vehicle stops. The speed-based control gain that determines the rear motor torque is set according to the vehicle speed and the total braking torque, so that the deceleration change of the vehicle can be predicted according to the current vehicle speed and the total braking torque, and the parking time can be estimated according to the predicted deceleration change.

[0079] Here, if the reduction of the rear motor torque starts before the vehicle stops, the pitch change may not be effectively suppressed. On the other hand, if the start timing of the reduction of the rear motor torque is determined according to the vehicle speed, the braking distance may increase. In contrast, in the first embodiment, by estimating the time required until the vehicle stops, the motor torque starts to be reduced at the timing when the estimated time until the vehicle stops becomes 0 (the timing when the vehicle stops), thereby effectively achieving both the suppression of the pitch change and the suppression of the increase in the braking distance.

[0080] In the first embodiment, the parking time is obtained based on a parking time calculation map prepared in advance with the vehicle speed and the total braking torque as input. Since the parking time corresponding to the vehicle speed and the total braking torque can be actually measured in advance through experiments, etc., the calculation load can be suppressed and the calculation time can be shortened by mapping.

[0081] A plurality of parking time calculation maps are prepared in advance according to vehicle weight. Since the parking time depends on the vehicle weight, by preparing a parking time calculation map corresponding to each vehicle weight, the parking time can be estimated more accurately without depending on the vehicle weight.

[0082] When reducing the rear motor torque, the vehicle control device 17 outputs a control command so that the torque reduction gradient gradually increases. Specifically, the following control command is output: the rear motor torque is reduced at a first parking judgment reduction rate for a specific time (prescribed time), and if the specific time is exceeded, the rear motor torque is reduced at a second parking judgment reduction rate that is greater than the first parking judgment reduction rate. Here, in the first embodiment, the motor speed is referred to as the vehicle speed at low speeds, so if Fig.10 As shown in FIG. 1 , in the case of the assumed braking state, the motor speed is consistent with the stop timing of the target speed, and the reduction of the rear motor torque can be started at the optimal timing. Fig.11 In the case where motor vibration exists, it is difficult to distinguish between motor vibration and actual vehicle speed change. In the first embodiment, when a motor speed corresponding to a vehicle speed higher than the actual speed is detected due to motor vibration, in order to suppress the increase of the braking distance, the parking time is calculated by selecting the lower of the parking time calculated last time and the parking time calculated this time. Therefore, there is a possibility that the reduction of torque starts earlier than the actual parking timing, and the effect of anti-jerk control is reduced. Therefore, in the first embodiment, if the calculated parking time becomes 0, the reduction rate of torque is reduced within a specified time, and the reduction rate is increased after the specified time has passed, so that even if the reduction of torque starts earlier than the actual parking timing, the reduction of the effect of anti-jerk control can be suppressed.

[0083] [Implementation method 2]

[0084] The basic structure of the second embodiment is the same as that of the first embodiment, and therefore only the parts different from the first embodiment will be described.

[0085] In the vehicle control system of the second embodiment, in order to suppress the uncomfortable shaking of the vehicle when parking and reduce the fatigue of the occupants, anti-jerk control is implemented to reduce the friction braking force from the friction braking force that serves as a reference (reference friction braking force). Here, the reference friction braking force is an estimated friction braking force estimated based on the stroke of the brake pedal.

[0086] Fig.12 This is a control block diagram of the friction brake 3 according to the second embodiment.

[0087] The disturbance estimation unit 91 estimates disturbance based on the slope resistance, the driver's required torque, the G sensor value, the running resistance, and the vehicle weight. The disturbance is estimated using the following equation (2) when the brakes are basically not used.

[0088] Disturbance = G sensor value × vehicle weight - braking force equivalent to the torque required by the driver - slope resistance - driving resistance... (2)

[0089] Furthermore, a configuration may be adopted in which estimation is performed even when the influence of the block μ change is small, such as when the estimated friction braking force is extremely small.

[0090] The estimated friction braking force correction gain calculation unit 92 calculates a final correction gain for correcting an estimated error in the estimated friction braking force associated with a change in the pad μ (friction coefficient) based on disturbance, G sensor value, running resistance, vehicle speed, estimated friction braking force (reference friction braking force), vehicle weight, motor torque, and brake pad temperature. The calculation method of the final correction gain is the same as that of the estimated friction braking force correction gain calculation unit 33 of the first embodiment, but in the estimated friction braking force correction gain calculation unit 92, the estimated friction braking force correction gain is calculated by further considering the error associated with the disturbance.

[0091] The total braking torque calculation section 93 calculates the total braking torque based on the estimated friction braking force, the running resistance, the gradient resistance, the disturbance, and the final correction gain. Fig.13 This is a control block diagram of the total braking torque calculation unit 93 according to Embodiment 2. The third adder 101 adds the torque corresponding to the disturbance to the value obtained by adding the torque corresponding to the slope resistance and the torque corresponding to the running resistance to the corrected estimated friction braking torque.

[0092] The subtraction braking force calculation section 94 calculates the subtraction braking force based on the estimated friction braking force, the disturbance, the driver's required torque, and the final correction gain. Fig.14 This is a control block diagram of the subtraction braking force calculation unit 94 of the fourth embodiment. The comparator 111 subtracts the slope resistance from the braking driving force equivalent to the driver's required torque, and calculates the braking driving force equivalent to the driver's required torque taking into account the slope resistance. The absolute value of the output of the comparator 111 is calculated in the absolute value calculation unit 112. The multiplier 113 divides the output of the absolute value calculation unit 112 by the final correction gain, and calculates the absolute value of the driving force equivalent to the corrected driver's required torque. The comparator 114 subtracts the absolute value of the driving force equivalent to the corrected driver's required torque from the estimated friction braking force. The limiter 115 compares the value obtained by subtracting the absolute value of the driving force equivalent to the corrected driver's required torque from the estimated friction braking force with 0, and outputs the larger value as the subtraction braking force.

[0093] The multiplier 95 multiplies the control gain by the subtraction braking force to calculate the control gain multiplied subtraction braking force. The comparator 96 subtracts the control gain multiplied subtraction braking force from the estimated friction braking force to calculate the subtraction friction braking force. The brake control device 18 sets the torque conversion value of the subtraction friction braking force, that is, the subtraction friction braking torque, as the target friction braking torque.

[0094] Next, the effects of the second embodiment will be described.

[0095] Fig.15 It is a time chart of the vehicle speed, the control gain, and the rear motor torque in the anti-jerk control according to the second embodiment.

[0096] At time t1 , since the vehicle speed decreases to the anti-jerk control intervention speed, the post-subtraction braking torque starts to decrease.

[0097] At time t2, the parking time calculated by the parking time calculation unit 71 becomes 0, so the control gain rate limiting unit 55 switches the rate of the speed-based control gain from the decreasing rate to the decreasing rate in the first parking determination, and the post-subtraction friction braking torque starts to increase.

[0098] At time t3, since a specified time has passed since the parking time became 0, in the control gain rate limiting unit 55, the ratio of the speed-based control gain is switched to a second parking judgment gain reduction rate that is greater than the first parking judgment gain reduction rate, and the friction braking torque after subtraction increases with a larger gradient.

[0099] At time t4, the anti-jerk control is terminated.

[0100] As described above, the vehicle control device 17 of the second embodiment monitors the parking time, and after starting to reduce the friction braking torque based on the anti-jerk control, the friction braking torque is increased when the parking time becomes 0. At this time, the friction braking torque is increased at a first parking judgment reduction rate for a specific time (prescribed time), and if the prescribed time is exceeded, a control instruction is output to increase the friction braking torque at a second parking judgment reduction rate greater than the first parking judgment reduction rate. As a result, as in the first embodiment, it is possible to take into account both the suppression of the pitch change when the vehicle is parked and the suppression of the increase in the braking distance.

[0101] [Other implementation methods]

[0102] Although the embodiments for carrying out the present invention have been described above, the specific configuration of the present invention is not limited to the configuration of the embodiments, and design changes and the like that do not depart from the gist of the invention are also included in the present invention.

[0103] In the embodiment, an example of applying the present invention to a rear-wheel drive electric vehicle is shown, but it may also be a front-wheel drive electric vehicle or a four-wheel drive electric vehicle. In addition, it is not limited to electric vehicles, and it may also be a vehicle having an engine as an internal combustion engine, or a hybrid vehicle that can use both an engine and a motor to travel. That is, as long as it is a structure that can apply torque from the drive source side or a structure that can reduce friction braking within the range where the vehicle can stop or within the range where the braking force acts between the drive wheel and the road surface when the vehicle stops using the friction brake.

[0104] In the implementation, the estimated friction braking force is used as input, but since the braking force and braking torque are values ​​that can be converted by vehicle parameters such as the effective radius of the tire, the estimated friction braking torque can also be input. In this case, the effective radius of the tire can also be an estimate instead of a specified value.

[0105] In the first embodiment, the output is output as a driving torque, but similarly to the relationship between the braking force and the braking torque, it may be a driving force that can be converted by the effective tire radius, or it may be a longitudinal acceleration or longitudinal jerk converted using vehicle parameters such as vehicle weight.

[0106] In the second embodiment, the output is the friction braking force, but since it is a value that can be converted using vehicle parameters such as the effective radius of the tire, the output may be friction braking torque or longitudinal acceleration or longitudinal jerk converted using vehicle parameters such as vehicle weight.

[0107] In the embodiment 1-2, the speed-based control gain map may be configured such that a speed-based control gain map is prepared for each vehicle weight and an appropriate map is selected.

[0108] The physical quantity related to the parking target is not limited to the time until the vehicle stops, and may be a distance or a speed.

[0109] Vehicle weight can be detected by sensors such as the suspension height sensor, or it can be estimated.

[0110] As for the brake pad temperature, the temperature of the brake pad can be obtained by a sensor, or the change of the pad temperature at each moment can be estimated.

[0111] In Embodiment 2, the disturbance may be estimated by detecting the roughness of the road surface by a stereo camera, etc. In addition, when the state of the road surface is detected by a stereo camera, etc. and it is assumed that the disturbance increases due to the road surface, a structure may be provided to start reducing the braking force earlier than intervening with the original braking torque.

[0112] In addition, the present invention is not limited to the above-mentioned embodiments, and includes various modified examples. For example, the above-mentioned embodiments are embodiments described in detail in order to explain the present invention in an easy-to-understand manner, and are not limited to all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of other embodiments, and in addition, the structure of other embodiments can be added to the structure of a certain embodiment. In addition, with respect to a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0113] This application claims priority based on Japanese Patent Application No. 2022-138911 filed on September 1, 2022. The entire disclosure of Japanese Patent Application No. 2022-138911 filed on September 1, 2022 including specification, claims, drawings, and abstract is incorporated herein by reference in its entirety.

[0114] Description of Reference Numerals

[0115] 1 ... electric vehicle (vehicle), 3 ... friction brake (friction brake device), 7 ... rear motor (drive device), 17 ... vehicle control device (control unit).

Claims

1. A vehicle control device, the vehicle control device being provided for a vehicle, the vehicle comprising: a friction braking device for generating a friction braking force for the vehicle; and a driving device for generating a driving force for the vehicle, The vehicle control device includes a control unit that outputs a result calculated based on input information. The control unit Obtaining a physical quantity related to the speed of the vehicle, obtaining a physical quantity related to a total braking force for decelerating the vehicle, obtaining a physical quantity related to a parking target of the vehicle based on a physical quantity related to the speed of the vehicle and a physical quantity related to the total braking force, When the vehicle is decelerated based on a physical quantity related to the total braking force, When the driving force is increased by the driving device and the physical quantity related to the parking target reaches a reference value, a control instruction for reducing the driving force increased by the driving device is output, Alternatively, when the friction braking force is reduced from a reference friction braking force by the friction braking device and the physical quantity related to the parking target reaches the reference value, a control command for increasing the friction braking force reduced by the friction braking device is output.

2. The vehicle control device according to claim 1, wherein: The control unit When the vehicle is decelerated based on a physical quantity related to the total braking force, When the driving force is increased by the driving device and the physical quantity related to the parking target reaches the reference value, the control command for reducing the driving force increased by the driving device is output.

3. The vehicle control device according to claim 1, wherein: The physical quantity related to the parking target is a parking target time until the vehicle is parked.

4. The vehicle control device according to claim 3, wherein: The time when the target parking time reaches zero is set as the reference value.

5. The vehicle control device according to claim 4, wherein: The parking target time is acquired based on a parking target time acquisition map prepared in advance that takes as input a physical quantity related to the speed of the vehicle and a physical quantity related to the total braking force.

6. The vehicle control device according to claim 5, wherein: A plurality of the parking target time acquisition maps are prepared in advance according to the weight of the vehicle.

7. The vehicle control device according to claim 1, wherein: The control unit When the driving force increased by the driving device is reduced, the control instruction is output so that the reduction gradient of the driving force gradually increases, Alternatively, when increasing the friction braking force reduced by the friction braking device, the control command is output so that the increase gradient of the friction braking force gradually increases.

8. The vehicle control device according to claim 7, wherein: The control unit When reducing the driving force increased by the driving device, the control instruction is outputted so that: the driving force is reduced at a first reduction gradient within a specified time, and if the specified time is exceeded, the driving force is reduced at a second reduction gradient greater than the first reduction gradient, Alternatively, when increasing the friction braking force reduced by the friction brake device, the control instruction is output so that: the friction braking force is increased with a first increase gradient within the specified time, and if the specified time is exceeded, the friction braking force is increased with a second increase gradient greater than the first increase gradient.

9. The vehicle control device according to claim 1, wherein: The control unit When the vehicle is decelerated based on a physical quantity related to the total braking force, When the friction braking force is reduced from a reference friction braking force by the friction braking device and the physical quantity related to the parking target reaches the reference value, the control command for increasing the friction braking force reduced by the friction braking device is output.

10. A vehicle control method, which is a vehicle control method executed by a control unit mounted on a vehicle, wherein the vehicle comprises: a friction braking device for generating a friction braking force for the vehicle; and a driving device for generating a driving force for the vehicle, wherein: By means of the control unit Obtaining a physical quantity related to the speed of the vehicle, obtaining a physical quantity related to a total braking force for decelerating the vehicle, obtaining a physical quantity related to a parking target of the vehicle based on a physical quantity related to the speed of the vehicle and a physical quantity related to the total braking force, When the vehicle is decelerated based on a physical quantity related to the total braking force, When the driving force is increased by the driving device and the physical quantity related to the parking target reaches a reference value, a control instruction for reducing the driving force increased by the driving device is output, Alternatively, when the friction braking force is reduced from a reference friction braking force by the friction braking device and the physical quantity related to the parking target reaches the reference value, a control command for increasing the friction braking force reduced by the friction braking device is output.

11. A vehicle control system comprising: The friction brake device generates friction braking force on the vehicle; a driving device for causing the vehicle to generate driving force; and The control device outputs a result calculated based on the input information, The control device Obtaining a physical quantity related to the speed of the vehicle, obtaining a physical quantity related to a total braking force for decelerating the vehicle, obtaining a physical quantity related to a parking target of the vehicle based on a physical quantity related to the speed of the vehicle and a physical quantity related to the total braking force, When the vehicle is decelerated based on a physical quantity related to the total braking force, The driving force is increased by the driving device, and when the physical quantity related to the parking target reaches a reference value, a control instruction for reducing the driving force increased by the driving device is output, Alternatively, the friction braking force is reduced from a reference friction braking force by the friction braking device, and when the physical quantity related to the parking target reaches the reference value, a control command for increasing the friction braking force reduced by the friction braking device is output.

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