JP2021075195A - Braking control device - Google Patents

Abstract

To provide a braking control device capable of smoothly fluctuating acceleration of a vehicle while reducing an impact and noise caused by backlash.SOLUTION: A braking control device includes: a motor control section 121 generating driving/braking torque for applying driving force or braking force from an electric motor connected to a driving wheel provided in a vehicle to the driving wheel; and a friction control section 103 controlling a friction braking device that performs friction braking of the driving wheel or a driven wheel. When the force applied to the driving wheel by the electric motor is switched from driving force to braking force, the motor control section reduces change amount of driving/braking torque and the friction control section operates the friction braking device so as to compensate for braking force that is insufficient due to the reduced driving/braking torque.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a braking control device.

In an electric vehicle, there is a control method in which when the accelerator is released to shift from a running state to a stopped state, the torque generated by the motor is gradually changed from the running torque to the regenerative torque to quickly decelerate and stop. .. At this time, when the torque generated by the motor is switched from the traveling torque to the regenerative torque, impact and noise are generated due to the backlash of gears such as a reduction gear provided between the motor and the drive wheels, and the riding comfort deteriorates. I have something to do. In order to deal with this problem, for example, in Patent Document 1 below, when the vehicle stops control, the output waveform of the start-up of the regenerative torque command signal is smoothed, so that the impact and noise caused by the backlash can be reduced. Electric vehicles to reduce are disclosed.

Japanese Unexamined Patent Publication No. 9-130911

When the vehicle is stopped, it is preferable that the acceleration of the vehicle changes smoothly in addition to reducing impact and noise in order to improve the riding comfort. However, according to the electric vehicle disclosed in Patent Document 1, the amount of change in the torque is relaxed when the traveling torque is switched to the regenerative torque, so that the braking force is insufficient and the acceleration of the vehicle fluctuates stepwise. There is a risk that the ride quality will deteriorate.

An object of the present disclosure is to provide a braking control device capable of smoothly fluctuating the acceleration of a vehicle while reducing the impact and noise caused by backlash.

The present disclosure is a braking control device, the motor control unit (121), which generates a driving braking torque for applying a driving force or a braking force to the driving wheels from an electric motor connected to the driving wheels provided in the vehicle. , A friction control unit (103) that controls a friction braking device that frictionally brakes a driving wheel or a driven wheel. When the force applied to the drive wheels by the electric motor is switched from the driving force to the braking force, the motor control unit relaxes the amount of change in the drive braking torque, and the friction control unit frictions so as to compensate for the braking force insufficient in the drive braking torque. Activate the braking device.

In the present disclosure, when the force applied to the drive wheels from the electric motor is switched from the driving force to the braking force, the amount of change in the driving braking torque is relaxed, which is caused by the backlash that occurs when the driving force is switched to the braking force. Impact and noise can be reduced. At this time, since the friction braking device operates so as to compensate for the insufficient braking force due to the decrease in the amount of change in the drive braking torque, the acceleration of the vehicle can be smoothly changed and the riding comfort is improved. Since the regenerative braking force of the electric motor can be utilized as much as possible when the vehicle is stopped, the amount of power generation can be secured.

According to the present disclosure, it is possible to provide a braking control device capable of smoothly fluctuating the acceleration of a vehicle while reducing the impact and noise caused by backlash.

FIG. 1 is a diagram showing a schematic configuration of a vehicle according to the present embodiment. FIG. 2 is a diagram for explaining the transfer of signals in FIG. FIG. 3 is a flowchart for explaining the control flow in FIG. FIG. 4 is a timing chart showing changes in various parameters in the present embodiment.

Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components are designated by the same reference numerals as much as possible in each drawing, and duplicate description is omitted.

As shown in FIG. 1, the vehicle 2 is provided with a right front wheel 215R and a left front wheel 215L, and a right rear wheel 216R and a left rear wheel 216L. The right front wheel 215R and the left front wheel 215L each function as driving wheels for driving the vehicle 2. The right rear wheel 216R and the left rear wheel 216L function as driven wheels that rotate with the driving of the right front wheel 215R and the left front wheel 215L, respectively.

The right front wheel 215R, the left front wheel 215L, the right rear wheel 216R, and the left rear wheel 216L are provided with a right front friction brake 231R, a left front friction brake 231L, a right rear friction brake 232R, and a left rear friction brake 232L, respectively. .. The right front friction brake 231R, the left front friction brake 231L, the right rear friction brake 232R, and the left rear friction brake 232L are specific examples of friction braking devices that frictionally brake the wheels by applying a frictional force to the corresponding wheels, respectively. .. In the following description, when it is not necessary to distinguish between them, the right front friction brake 231R, the left front friction brake 231L, the right rear friction brake 232R, and the left rear friction brake 232L are collectively referred to as a friction brake.

The vehicle 2 is provided with an inverter 211, a motor generator 212, a battery 213, and a differential gear 214. The inverter 211 is provided between the motor generator 212 and the battery 213. When the motor generator 212 is driven by using the electric power stored in the battery 213, the inverter 211 converts the direct current output from the battery 213 into a three-phase alternating current and supplies it to the motor generator 212. When the motor generator 212 is used as a generator and regenerative braking is performed, the inverter 211 converts the three-phase alternating current output from the motor generator 212 into a direct current and supplies it to the battery 213.

The motor generator 212 is an electric generator that serves both as an electric generator and a generator. The motor generator 212 is connected to the right front wheel 215R and the left front wheel 215L, which are driving wheels, via a speed reducer (not shown) and a differential gear 214 which is a differential device. When the three-phase alternating current is supplied from the inverter 211, the motor generator 212 rotates according to the supplied three-phase alternating current and drives the right front wheel 215R and the left front wheel 215L via the reduction gear and the differential gear 214. .. When regenerative braking is performed, the rotations of the right front wheel 215R and the left front wheel 215L are transmitted to the motor generator 212 via the differential gear 214 and the speed reducer. When the battery 213 can store electricity, power is generated by the shaft rotation of the motor generator 212, and the generated three-phase AC current is converted into a direct current by the inverter 211 and supplied to the battery 213.

The differential gear 214 is provided with a certain amount of gap, so-called backlash, so that the gear on the motor generator 212 side and the gear on the drive wheel side mesh smoothly with each other. A backlash is also provided in the gear of the reduction gear that connects the motor generator 212 and the differential gear 214. When the torque generated by the motor generator 212 is switched from the driving torque to the braking torque, the directions in which these gears hit are reversed and they collide with each other, which may cause an impact or noise. The configuration for reducing this impact and noise will be described later.

The vehicle 2 is equipped with an ESC-ECU (Electronic Control-Electronic Control Unit) 10, an EV-ECU (Electronic Vehicle-Electronic Control Unit) 12, an MG-ECU (Electronic Control Unit) 12, and an MG-ECU (Motor-Electric Control Unit) 12. Has been done.

The ESC-ECU 10 is a device for stabilizing the behavior of the vehicle 2. The ESC-ECU 10 includes a G sensor 221, a yaw rate sensor 222, a right front wheel speed sensor 223R, a left front wheel speed sensor 223L, a right rear wheel speed sensor 224R, a left rear wheel speed sensor 224L, and a hydraulic pressure sensor 225. And, the detection signal is output from.

The G sensor 221 is a sensor for measuring the acceleration and deceleration of the vehicle 2. The G sensor 221 outputs a signal indicating acceleration in the front-rear direction and acceleration in deceleration of the vehicle 2 to the ESC-ECU 10. The yaw rate sensor 222 is a sensor for measuring the angular velocity around the vertical axis of the vehicle 2. The yaw rate sensor 222 outputs a signal indicating the angular velocity around the vertical axis of the vehicle 2 to the ESC-ECU 10.

The right front wheel speed sensor 223R is a sensor for measuring the wheel speed of the right front wheel 215R. The right front wheel speed sensor 223R outputs a signal indicating the wheel speed of the right front wheel 215R to the ESC-ECU 10.

The left front wheel speed sensor 223L is a sensor for measuring the wheel speed of the left front wheel 215L. The left front wheel speed sensor 223L outputs a signal indicating the wheel speed of the left front wheel 215L to the ESC-ECU 10.

The right rear wheel speed sensor 224R is a sensor for measuring the wheel speed of the right rear wheel 216R. The right rear wheel speed sensor 224R outputs a signal indicating the wheel speed of the right rear wheel 216R to the ESC-ECU 10.

The left rear wheel speed sensor 224L is a sensor for measuring the wheel speed of the left rear wheel 216L. The left rear wheel speed sensor 224L outputs a signal indicating the wheel speed of the left rear wheel 216L to the ESC-ECU 10.

The hydraulic pressure sensor 225 is a sensor for measuring the hydraulic pressure of an accelerator pedal (not shown). The hydraulic pressure of the accelerator pedal fluctuates according to the amount of depression of the accelerator pedal by the driver's operation, and corresponds to the accelerator opening. The hydraulic pressure sensor 225 outputs a signal indicating the hydraulic pressure of the accelerator pedal to the ESC-ECU 10. In the present embodiment, it is assumed that the vehicle is capable of so-called one-pedal control, in which the driving and braking of the vehicle 2 can be controlled by the amount of depression of the accelerator pedal. The hydraulic pressure of the accelerator pedal is an example of a parameter indicating the amount of braking operation by the driver. The parameter indicating the braking operation amount is not limited to this, and may be, for example, the amount of depression of the brake pedal instead of the accelerator pedal.

The ESC-ECU 10 uses signals output from the G sensor 221, the yaw rate sensor 222, the right front wheel speed sensor 223R, the left front wheel speed sensor 223L, the right rear wheel speed sensor 224R, the left rear wheel speed sensor 224L, and the hydraulic pressure sensor 225. Based on this, the calculation for stabilizing the behavior of the vehicle 2 and stopping the vehicle 2 is executed. The ESC-ECU 10 outputs a signal for adjusting the vehicle body speed of the vehicle 2 to the EV-ECU 12 based on the calculation result. The ESC-ECU 10 outputs a control signal for performing friction braking to the right front friction brake 231R, the left front friction brake 231L, the right rear friction brake 232R, and the left rear friction brake 232L based on the calculation result.

The EV-ECU 12 has information on the vehicle body speed output from the ESC-ECU 10, the number of revolutions of the motor generator 212 output from the MG-ECU 14, driver operations such as accelerator opening, and signals output from various sensors (not shown). The motor generator 212 outputs the torque corresponding to the rotation speed to be generated to the MG-ECU 14 based on the information indicated by.

The MG-ECU 14 outputs a control signal to the inverter 211 so that the motor generator 212 generates a predetermined torque. The MG-ECU 14 measures the rotation speed of the motor generator 212. The MG-ECU 14 outputs information indicating the rotation speed of the motor generator 212 to the EV-ECU 12.

Subsequently, the functional operations of the ESC-ECU 10, the EV-ECU 12, and the MG-ECU 14 will be described with reference to FIG.

As shown in FIG. 2, the EV-ECU 12 includes a motor control unit 121 as a functional component.

The motor control unit 121 has a driving force or a driving force from the motor generator 212, which is an electric motor connected to the right front wheel 215R and the left front wheel 215L, which are the driving wheels provided in the vehicle 2, to the right front wheel 215R and the left front wheel 215L, which are the driving wheels. This is the part that generates the driving braking torque to apply the braking force. The motor control unit 121 aggregates the information output from various sensors, the information output from the ESC-ECU 10, and the information output from the MG-ECU 14, determines the torque indicated to the motor generator 212, and sends the MG-ECU 14 to the MG-ECU 14. Output.

The ESC-ECU 10 includes an acceleration detection unit 101, a stepping amount detection unit 102, a friction control unit 103, a target value calculation unit 104, and a correction unit 105 as functional components.

The acceleration detection unit 101 is a part that detects the acceleration of the vehicle 2. The acceleration of the vehicle 2 can be acquired, for example, by the output signal of the G sensor 221. Alternatively, the acceleration of the vehicle 2 may be obtained based on the wheel speeds of the right rear wheel 216R and the left rear wheel 216L, which are the driven wheels, and the vehicle body speed of the vehicle 2 obtained from any or a combination of GPS information. The wheel speed of the right rear wheel 216R can be acquired by the output signal of the right rear wheel speed sensor 224R. The wheel speed of the left rear wheel 216L can be acquired by the output signal of the left rear wheel speed sensor 224L. The wheel speed can be obtained from the average value of the wheel speed of the right rear wheel 216R and the wheel speed of the left rear wheel 216L. The GPS information of the vehicle 2 can be acquired by a GPS information acquisition device (not shown).

The acceleration of the vehicle 2 can also be obtained from the rotation speed and reduction ratio of the motor generator 212. The acceleration of the vehicle 2 can also be obtained from the output values of the rotation sensor provided on the drive wheel axle and the rotation sensor provided on the speed reducer.

The depression amount detection unit 102 is a portion that detects the depression amount of the accelerator pedal based on a signal indicating the hydraulic pressure of the accelerator pedal output from the hydraulic pressure sensor 225. The depression amount detection unit 102 calculates the accelerator opening degree based on the depression amount of the accelerator pedal.

The friction control unit 103 is a part that outputs a control signal to the friction brake to control the operation of the friction brake. In the friction brake, the brake pad moves when the oil pressure of the cylinder rises in response to the control signal, and the brake pad is pressed against the disc rotor that rotates with the wheels to generate a braking force. Therefore, a delay time occurs between the time when the oil pressure of the cylinder rises in response to the control signal from the friction control unit 103 and the time when the braking force is actually generated. Since this delay time varies depending on the temperature dependence of the seal portion of the piston that drives the brake pad and deterioration over time, the braking force due to the friction brake is generated earlier or later than the desired timing. In the following, the timing at which the friction control unit 103 outputs a control signal to the friction brake is also referred to as "the timing at which the friction brake is started", and the timing at which the braking force due to the friction brake is actually generated is "the braking force or braking torque is generated". Also called "timing".

The target value calculation unit 104 has a locus of the target acceleration which is the target value of the acceleration of the vehicle 2, a locus of the target drive braking torque which is a target value of the drive braking torque generated by the motor generator 212, and a braking torque generated by the friction brake. This is the part that calculates the trajectory of the target braking torque, which is the target value of. The target value calculation unit 104 determines the vehicle 2 based on the drive braking torque actually generated by the motor generator 212 acquired from the MG-ECU 14 and the actual acceleration of the vehicle 2 detected by the acceleration detection unit 101. Calculate the trajectory of the target acceleration of. The target value calculation unit 104 calculates the locus of the target drive braking torque of the motor generator 212 based on the calculated locus of the target acceleration. The target value calculation unit 104 calculates the locus of the target braking torque of the friction brake based on the calculated locus of the target acceleration and the locus of the target drive braking torque. In calculating the locus of the target braking torque, the target value calculation unit 104 calculates the target timing, which is the target value of the timing for generating the braking force by the friction brake.

The correction unit 105 deviates from the target timing at which the braking force by the friction brake should be generated and the timing at which the braking force is actually generated based on the calculated target acceleration and the detected actual acceleration of the vehicle 2. Is a part that corrects the timing of starting the friction brake so as to cancel the calculated deviation. The details of the correction method will be described later.

The acceleration of the vehicle 2 detected by the acceleration detection unit 101, the accelerator opening detected by the depression amount detection unit 102, the trajectory of the target acceleration calculated by the target value calculation unit 104, and the trajectory of the target drive braking torque of the motor generator 212 are It is output to the EV-ECU 12.

Subsequently, with reference to FIGS. 3 and 4, specific control contents of the acceleration detection unit 101, the stepping amount detection unit 102, the friction control unit 103, the target value calculation unit 104, the correction unit 105, and the motor control unit 121 are specified. Will be described. FIG. 4 is a timing chart showing fluctuations of various parameters. In FIG. 4, (a) shows the accelerator opening degree (%), (b) shows the drive braking torque (Nm) generated by the motor generator 212, and (c) shows the oil pressure (MPa) of the cylinder of the friction brake. ), (D) indicates the braking torque (Nm) generated by the friction brake, and (e) indicates the acceleration (G) of the vehicle 2.

In FIG. 4B, the drive braking torque of the motor generator 212 is assumed to give a driving force when it is positive and to give a braking force when it is negative. In FIG. 4D, the braking torque of the friction brake is assumed to give a braking force when it is positive. In FIG. 4E, the acceleration of the vehicle 2 is assumed to be the acceleration generated when the traveling direction of the vehicle 2 is positive.

In FIGS. 4D and 4E, the trajectories 201 and 301 show the case where the braking torque of the friction brake is generated earlier than the target timing. Trajectories 202 and 302 show the case where the braking torque of the friction brake is generated according to the target timing. Trajectories 203 and 303 indicate the case where the braking torque of the friction brake is generated later than the target timing. In FIG. 4E, the locus 304 shows a case where the friction brake is not used as a comparative example.

As shown in FIG. 3, in step S101, the stepping amount detecting unit 102 detects that the drive control is switched to the braking control based on the change in the accelerator opening degree. Switching from drive control to braking control may be detected, for example, based on the accelerator opening being less than a predetermined threshold value. When the depression amount detection unit 102 detects the switch from the drive control to the braking control (YES in step S101), the process proceeds to step S102. When the depression amount detection unit 102 does not detect the switch from the drive control to the braking control (NO in step S101), the process of step S101 is repeated.

In step S102 following step S101, the target value calculation unit 104 trajectories of the target acceleration of the vehicle 2 based on the drive braking torque of the motor generator 212 and the actual acceleration of the vehicle 2 detected by the acceleration detection unit 101. Is calculated. The locus of the target acceleration is a locus that smoothly fluctuates as shown in the locus 302 of FIG. 4 (e) without the acceleration increasing or decreasing until the vehicle 2 stops.

In step S103 following step S102, the target value calculation unit 104 calculates the locus of the target drive braking torque of the motor generator 212 based on the calculated locus 302 of the target acceleration.

As shown in FIG. 4B, the target drive braking torque decreases by a predetermined amount of change, for example, in the section A1 where the accelerator opening starts to decrease. In the section A2 following the section A1, the change amount may be lessened than the change amount in the section A1, or may be substantially constant without change. The target drive braking torque in the section A2 may be approximately 0 (Nm). In the section A3 following the section A2, the change amount is larger than that of the section A2 again. The section A2 includes a time when the drive braking torque generated by the motor generator 212 is switched from positive to negative, that is, a time when the force applied to the drive wheels by the motor generator 212 is switched from the driving force to the braking force. By making the amount of change in the target drive braking torque smaller in the section A2 than in the other sections, it is possible to alleviate the collision of the gears caused by the backlash and reduce the impact and noise.

The target value calculation unit 104 outputs a signal indicating the calculated target drive braking torque of the motor generator 212 to the motor control unit 121. Instead of the target value calculation unit 104, the motor control unit 121 may calculate the locus of the target drive braking torque. It is assumed that the motor generator 212 can generate the drive braking torque substantially according to the trajectory of the target drive braking torque.

In step S104 following step S103, the target value calculation unit 104 calculates the locus 202 of the target braking torque of the friction brake based on the calculated locus 302 of the target acceleration and the locus of the target drive braking torque. The target value calculation unit 104 outputs a signal to the friction control unit 103 so as to start the friction brake before the target braking torque is generated in consideration of the delay time of the friction brake estimated in advance. In response to the signal from the target value calculation unit 104, the friction control unit 103 activates the friction brake _{t N} seconds after the drive braking torque of the motor generator 212 starts to decrease, as shown in FIG. 4 (c). It shall be.

If the friction brake is not used, the acceleration of the vehicle 2 will change stepwise with the drive braking torque generated by the motor generator 212, as shown in the locus 304 of FIG. 4 (e). .. In this respect, in the present embodiment, the friction brake operates so as to compensate for the shortage of the regenerative braking force of the motor generator 212 in the section A2, so that the fluctuation of the acceleration of the vehicle 2 becomes smooth. Specifically, the locus 202 of the target braking torque of the friction brake may be, for example, a locus that starts to increase from the section A2, reaches a peak at the boundary between the section A2 and the section A3, and starts to decrease in the section A3.

In step S105 following step S104, the correction unit 105 brakes by the friction brake based on the actual acceleration locus detected by the acceleration detection unit 101 and the target acceleration locus 302 calculated by the target value calculation unit 104. Calculate the deviation between the timing when the torque is actually generated and the target timing. The method for calculating the deviation is not particularly limited, but two methods will be described below as an example. In the following description, for example, it is assumed that the locus of the actual braking torque of the friction brake is the locus 201 of FIG. 4 (d), and the locus of the actual acceleration of the vehicle 2 is the locus 301 of FIG. 4 (e).

As the first method, the correction unit 105 sets a predetermined threshold value for the acceleration of the vehicle in advance, and compares the time P1 at which the actual acceleration exceeds the threshold value with the time P2 at which the target acceleration exceeds the threshold value. Exceeding the threshold includes exceeding the threshold in the positive direction and exceeding the threshold in the negative direction. For example, when the traveling direction is positive in the acceleration of the vehicle 2, exceeding the threshold value means that the speed is below the threshold value. The threshold value may be, for example, about −0.05 G.

_{The correction unit 105 calculates the difference t G} = P2-P1 (> 0) between the time P1 and the time P2. Assuming that the drive braking torque of the motor generator 212 fluctuates according to the target drive braking torque, the difference t _G is considered to be due to the variation in the delay time of the friction brake. Therefore, the correction unit 105 acquires in advance data on the correspondence between the _{difference t G} obtained from the acceleration and the timing deviation t _{F at} which the braking torque is generated, and refers to the data to correspond to the _{difference t G.} The deviation t _F can be calculated.

As the second method, the correction unit 105 calculates the difference between the actual acceleration of the vehicle 2 and the target acceleration at any time, _{and takes the maximum value G MAX} of the difference of the acceleration and the target at the time P3 to take the maximum value G _MAX. Acquire the amount of change in acceleration. Similar to the first method, this difference in acceleration is considered to be due to the variation in the delay time of the friction brake. At time P3 difference of the acceleration takes a maximum value G _MAX, it is possible driving braking torque of the motor generator 212 is be assumed to be approximately 0 (N · m), the change amount of the target acceleration of the vehicle 2 , It is considered that it depends on the braking torque of the friction brake. Accordingly, the correction unit 105, the maximum value _{G MAX,} by dividing a change amount of the target acceleration at time P3, it is possible to calculate the deviation _{t F} corresponding to the maximum value _{G MAX.} Instead of this, the correction unit 105 acquires in advance data on the correspondence between the _{maximum value G MAX and the timing deviation t F} where the braking torque is generated, and refers to the data to correspond _{to the maximum value G MAX.} The deviation t _F may be calculated.

In the second method, if it cannot be assumed that the drive braking torque of the motor generator 212 at time P3 is almost 0 (Nm), the correction unit 105 sets the maximum value _GMAX by the amount of change in the target acceleration. _{Instead of dividing, the deviation t F} may be calculated by dividing by the value obtained by subtracting the contribution of the drive braking torque from the amount of change in the target acceleration.

In step S106 following step S105, the correction unit 105 corrects the timing at which the friction brake is started so as to cancel the deviation t _{F based on the deviation t F of the timing at which the braking torque is generated.} The correction unit 105 updates _{, for example, the time t N + 1 at} which the N + 1th (N is an integer) friction brake is started _{to t N + 1} = t _N + t _F. For example, when the braking torque is generated earlier than the target as in the locus 201 of FIG. 4 (d), t _F > 0, and the time for starting the N + 1th friction brake is delayed. For example, when the generation of the braking torque is slower than the target as shown in the locus 203 of FIG. 4 (d), t _F <0, and the time for starting the N + 1th friction brake is earlier. The vehicle 2 learns the appropriate start timing of the friction brake by repeating the correction while traveling.

In step S107 following step S106, the correction unit 105 determines whether or not the learning of correction is completed. The determination of the end of learning may be performed, for example, based on the correction of a predetermined number of times, or may be performed based on the deviation of the generation of the braking torque within a predetermined threshold value. When it is determined that the learning is completed (YES in step S107), the process returns. If it is determined that the learning has not been completed (NO in step S107), the process returns to the process of step S101.

In the present embodiment, the braking control device includes the ESC-ECU 10, the EV-ECU 12, and the MG-ECU 14. The braking control device includes a motor control unit 121 that generates a driving braking torque for applying a driving force or a braking force to the driving wheels from a motor generator 212 that is an electric motor connected to the driving wheels provided in the vehicle 2. A friction control unit 103 that controls a friction braking device that frictionally brakes a wheel or a driven wheel is provided. When the force applied to the drive wheels by the electric motor is switched from the driving force to the braking force, the motor control unit 121 relaxes the amount of change in the drive braking torque, and the friction control unit 103 compensates for the braking force insufficient in the drive braking torque. Activates the friction braking device.

In the present embodiment, when the force applied to the drive wheels from the electric motor is switched from the driving force to the braking force, the amount of change in the driving braking torque is relaxed, which is caused by the backlash that occurs when the driving force is switched to the braking force. It is possible to reduce the impact and noise. At this time, since the friction braking device operates so as to compensate for the insufficient braking force due to the decrease in the amount of change in the drive braking torque, the acceleration of the vehicle can be smoothly changed and the riding comfort is improved. Since the regenerative braking force of the electric motor can be utilized as much as possible when the vehicle is stopped, the amount of power generation can be secured.

In the present embodiment, the braking control device includes an acceleration detection unit 101 that detects the acceleration of the vehicle 2, a locus of the target acceleration that is a target value of the acceleration of the vehicle 2, and a timing at which the friction braking device generates a braking force. Based on the target value calculation unit 104 that calculates the target timing, which is the target value, the detected acceleration of the vehicle 2, and the target acceleration, the deviation between the timing at which the braking force is actually generated and the target timing is calculated. A correction unit 105 that corrects the timing at which the friction braking device is started so as to cancel the deviation is further provided.

When the friction braking device generates braking force on the wheels by pressing the brake pads, the timing at which the braking force of the friction braking device is actually generated due to the temperature dependence of the seal part of the piston that drives the brake pads and deterioration over time. May deviate from the target timing. In the present embodiment, by correcting the timing at which the friction braking device is started so that the correction unit 105 cancels the deviation, the variation in the timing at which the braking force is generated by the friction braking device is suppressed, and the accuracy of braking control is improved. To do.

In the present embodiment, the correction unit 105 may calculate the deviation based on the difference between the time when the detected acceleration of the vehicle 2 exceeds the predetermined threshold value and the time when the target acceleration exceeds the predetermined threshold value.

It is considered that the deviation between the actual acceleration of the vehicle 2 and the target acceleration is caused by the difference between the timing at which the friction braking device actually generates the braking force and the target timing. Therefore, by detecting the difference in time between the actual acceleration of the vehicle 2 and the target acceleration exceeding a predetermined threshold value, it is possible to calculate the difference in timing at which the friction braking device generates the braking force.

In the present embodiment, the correction unit 105 may calculate the deviation based on the maximum value of the difference between the detected acceleration of the vehicle 2 and the target acceleration and the amount of change in the target acceleration when the maximum value is taken. ..

It is considered that the deviation between the actual acceleration of the vehicle 2 and the target acceleration is caused by the difference between the timing at which the friction braking device actually generates the braking force and the target timing. Therefore, by detecting the maximum value of the difference between the actual acceleration of the vehicle 2 and the target acceleration and the amount of change in the target acceleration when the maximum value is taken, the timing shift at which the friction braking device generates the braking force. Can be calculated.

In the present embodiment, a method of correcting the timing at which the correction unit 105 starts the friction brake has been described as an example, but the parameter corrected by the correction unit 105 is not limited to the timing at which the friction brake is started, and can be obtained by, for example, the friction brake. It may be the amount of change in torque or the like.

In the present embodiment, the acceleration detection unit 101, the depression amount detection unit 102, the friction control unit 103, the target value calculation unit 104, and the correction unit 105 are provided in the ESC-ECU 10, and the motor control unit 121 is provided in the EV-ECU 12. However, the physical components that realize these functional parts are not limited to this. For example, all or part of these functional parts may be realized by different components, and these components may be communicably connected via a network.

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those skilled in the art with appropriate design changes to these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each of the above-mentioned specific examples, its arrangement, conditions, shape, and the like are not limited to those illustrated, and can be changed as appropriate. The combinations of the elements included in each of the above-mentioned specific examples can be appropriately changed as long as there is no technical contradiction.

2: Vehicle 10: ESC-ECU (braking control device)
101: Acceleration detection unit 102: Depression amount detection unit 103: Friction control unit 104: Target value calculation unit 105: Correction unit 12: EV-ECU (braking control device)
121: Motor control unit 14: MG-ECU (braking control device)
211: Inverter 212: Motor generator 213: Battery 214: Differential gear 221: G sensor 222: Yaw rate sensor 225: Hydraulic pressure sensor

Claims (4)

It is a braking control device
A motor control unit (121) that generates a drive braking torque for applying a drive force or a braking force to the drive wheels from an electric motor connected to the drive wheels provided in the vehicle.
A friction control unit (103) for controlling a friction braking device that frictionally brakes the driving wheel or the driven wheel is provided.
When the force applied to the drive wheels by the electric motor is switched from the drive force to the braking force, the motor control unit relaxes the amount of change in the drive braking torque and compensates for the braking force insufficient by the drive braking torque. A braking control device in which the friction control unit operates the friction braking device. The braking control device according to claim 1.
An acceleration detection unit (101) that detects the acceleration of the vehicle, and
A target value calculation unit (104) that calculates a target acceleration locus, which is a target value of the vehicle acceleration, and a target timing, which is a target value of a timing at which the friction braking device generates a braking force.
Based on the detected acceleration of the vehicle and the target acceleration, the deviation between the timing at which the braking force is actually generated and the target timing is calculated, and the friction braking device is started so as to cancel the deviation. A braking control device further comprising a correction unit (105) for correcting timing. The braking control device according to claim 2.
The correction unit is a braking control device that calculates the deviation based on the difference between the detected time when the acceleration of the vehicle exceeds a predetermined threshold value and the time when the target acceleration exceeds the predetermined threshold value. The braking control device according to claim 2.
The correction unit calculates the deviation based on the maximum value of the difference between the detected acceleration of the vehicle and the target acceleration and the amount of change in the target acceleration when the maximum value is taken. ..

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