JP2014061794A - Brake control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device for a vehicle that can improve a pedal feel.SOLUTION: An integrated control device 5, a brake control unit 2, and a motor control unit 4 are characterized in that a substitution control part which performs substitution control to increase fluid pressure braking torque by placing an actuator in operation while decreasing regenerative braking torque on the basis of a reference substitution vehicle speed line where a limit value of the regenerative braking torque corresponding to a preset vehicle speed is set executes pre-load regenerative braking torque decrease processing to decrease the regenerative braking torque before reference start timing at which regenerative braking torque determined by the reference substitution vehicle speed line is decreased during the execution of the substitution control. Consequently, operation timing of an actuator of a fluid pressure braking device A is quickened in the substitution control and a suction phenomenon of a brake pedal due to response delay is thereby suppressed to improve a pedal feel.

Description

  The present invention relates to a vehicular braking control device that controls braking torque of a regenerative braking device and a hydraulic braking device according to a detected total braking torque of a driver detected during braking.

2. Description of the Related Art Conventionally, a vehicular braking control device that performs braking by operating a regenerative braking device and a hydraulic braking device according to a detected total braking torque of a driver detected during braking is known (see, for example, Patent Document 1). ).
In addition, as a hydraulic braking device, an electric multiplier provided with an input member that moves forward and backward by operating a brake pedal, an assist member that is arranged to be relatively movable with respect to the input member, and an electric actuator that moves the assist member forward and backward. A force device is known (see, for example, Patent Document 2). This electric booster generates a brake fluid pressure boosted in the master cylinder by an assist thrust applied to the assist member by the electric actuator in accordance with the movement of the input member by the brake pedal.

JP 2004-196064 A JP 2007-112426 A

However, in the above-described conventional vehicle braking control device, when the above-described electric booster is used, the following problems occur in the situation described below.
That is, in the braking control device for a vehicle, during braking operation, regenerative braking is prioritized in the low speed range, and when the vehicle speed decreases, switching control is performed to increase the hydraulic braking torque while decreasing the regenerative braking torque.

  When executing the switching control, when the hydraulic pressure by the hydraulic braking device is increased from around 0 MPa, the response delay of the hydraulic braking torque due to the loss stroke of the wheel cylinder or the response delay of the boost motor is caused. For example, the rise of the brake fluid pressure may be delayed. In such a case, the brake pedal may be temporarily sucked due to insufficient braking fluid pressure, and the pedal feel may be temporarily deteriorated.

  The present invention has been made paying attention to the above-described problem, and an object of the present invention is to provide a vehicle brake control device that can improve pedal feel.

In order to achieve the above object, a vehicle brake control device of the present invention includes:
Based on a reference switching vehicle speed line in which a regenerative braking torque limit value corresponding to a preset vehicle speed is set, switching is performed to increase the hydraulic braking torque by operating the actuator while reducing the regenerative braking torque. The control unit
The preload regenerative braking torque reduction process for reducing the regenerative braking torque is executed at a time before the reference start timing, which is the timing for reducing the regenerative braking torque determined by the reference replacement vehicle speed line, when performing the replacement control. To do.

In the present invention, when the preload regenerative braking torque reduction process for reducing the regenerative braking torque is performed at the time before the reference start timing in the early stage of the replacement control by the replacement control unit, the hydraulic braking device The operation timing of the actuator can be advanced.
Therefore, at the time of switching control, when the brake fluid pressure is increased by driving the actuator, the increase in the brake fluid pressure can be made slower than when the preload regenerative braking torque reduction process is not executed. As a result, it is possible to suppress an insufficient rise of the brake fluid pressure due to a response delay, suppress the occurrence of a brake pedal suction phenomenon due to the insufficient brake fluid pressure, and improve the pedal feel.

1 is a system configuration diagram of a vehicle brake control device according to a first embodiment. It is sectional drawing which shows the structure of the brake device applied to the brake control apparatus for vehicles of Embodiment 1, and an electric booster. 4 is a flowchart showing a flow of processing for replacement control including preload regenerative braking torque reduction control in the vehicle brake control device of the first embodiment. FIG. 3 is a characteristic diagram showing a reference replacement vehicle speed line and a preload start vehicle speed line in the vehicle braking control apparatus of the first embodiment, and FIG. (B) has shown the more preferable example of a change of the setting of the reference | standard replacement vehicle speed line. FIG. 6 is a limit vehicle speed characteristic diagram showing another example of setting of the limit vehicle speed V4 shown in FIG. 4 in the vehicle brake control apparatus of the first embodiment. FIG. 6 is a characteristic diagram illustrating another example of the reference replacement vehicle speed line and the preload start vehicle speed line in the vehicle brake control device according to the first embodiment, and (a) shows the preload start vehicle speed line as the regenerative braking torque increases, and the reference replacement start This is an example in which the vehicle speed range with respect to the vehicle speed line is widened, and (b) is an example in which the preload start vehicle speed line is set substantially parallel to the reference replacement start vehicle speed line. It is explanatory drawing of the setting of the preload regeneration limiting torque and the preload start regenerative braking torque in the vehicle brake control device of the first embodiment. FIG. 3 is a time chart showing an operation example of a comparative example for explaining the operation of the vehicle brake control device of Embodiment 1, wherein (a) shows a change in vehicle speed, and (b) shows changes in regenerative braking torque and friction braking torque. (C) shows a change in pedal stroke. 4 is a time chart for explaining the operation of the vehicle brake control device according to Embodiment 1, wherein a) shows changes in vehicle speed, (b) shows changes in regenerative braking torque and friction braking torque, and (c) shows pedals. It shows the change in stroke.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for realizing a vehicle brake control device of the present invention will be described with reference to the drawings.
(Embodiment 1)
First, the overall configuration of the vehicle brake control device according to the first embodiment will be described with reference to FIG. 1 which is a system configuration diagram of the vehicle brake control device.

  The vehicle braking control apparatus according to the first embodiment is applied to an electric vehicle in which driving wheels (wheels WH shown in FIG. 1) are driven by a motor / generator 1 (hereinafter simply referred to as a motor 1). A braking device A and a regenerative braking device B are provided.

  The hydraulic braking device A includes a brake pedal BP, a master cylinder MC, a brake control unit 2, and a VDC control unit 3, and the regenerative braking device B includes a motor control unit 4, and each control is performed by the integrated control device 5 during braking. Units 2, 3 and 4 are controlled.

  Specifically, at the time of braking, the integrated control device 5 obtains a driver request total braking torque corresponding to the braking operation. And the integrated control apparatus 5 performs regeneration cooperation control as needed at the time of braking. In this regenerative cooperative control, the hydraulic pressure of the master cylinder MC is generated by reducing the hydraulic pressure corresponding to the braking torque (regenerative braking torque) generated during the regeneration of the motor 1.

Hereinafter, the hydraulic braking device A and the regenerative braking device B will be described.
(Hydraulic braking device)
First, the hydraulic braking device A will be described.
The hydraulic braking device A includes a brake device 10 and a VDC actuator 30.
In the brake device 10, a braking fluid pressure corresponding to the depression force applied to the brake pedal BP that the driver steps on is generated in the master cylinder MC, and this braking fluid pressure is transmitted via the brake fluid pressure circuit (primary circuit 11 and secondary circuit 12). It is supplied to a wheel cylinder WC provided on each wheel WH to generate a braking force.

  Further, the brake device 10 includes an electric boosting ground 20, and the depression force (operation amount) of the brake pedal BP is boosted at a boost ratio set in advance by the electric booster 20, and in the master cylinder MC, This boosted input is converted into a hydraulic pressure to form a braking hydraulic pressure.

Here, based on FIG. 2, the structure of the brake device 10 including the electric booster 20 will be described.
The brake device 10 includes a wheel cylinder WC that brakes the wheel WH, a master cylinder MC that supplies hydraulic oil to the wheel cylinder WC, a reservoir tank RES that stores hydraulic oil, and an input shaft that moves forward and backward by operating the brake pedal BP. 13. The electric booster 20 boosts the propulsive force applied to the input shaft 13. Further, the brake control unit 2 controls the electric booster 20 according to the displacement amount detected by the stroke sensor 14 that detects the displacement amount of the input shaft 13.

  The input shaft 13 is an input member that makes a stroke (advance and retreat) together with the brake pedal BP, and the primary piston 15 of the master cylinder MC is moved by the stroke of the input shaft 13.

  The master cylinder MC moves the primary piston 15 as an assist member of the input shaft 13 forward and backward.

  The electric booster 20 gives a propulsion amount to the primary piston 15 according to the movement of the input shaft 13, and boosts the hydraulic pressure in the master cylinder MC (hereinafter, master cylinder pressure Pmc) by the propulsion force.

  The stroke sensor 14 is provided at one end of the input shaft 13. The stroke sensor 14 is a detection unit that detects a displacement amount of a stroke of the input shaft 13 as an operation amount of a driver's braking operation. The stroke sensor 14 outputs a detection signal corresponding to the detected displacement amount to the brake control unit 2.

The brake control unit 2 receives a detection signal from the stroke sensor 14 and transmits displacement amount information indicating the displacement amount of the stroke of the input shaft 13 according to the detection signal to the integrated control device 5 (see FIG. 1). The brake control unit 2 drives the electric booster 20 in accordance with a control command from the integrated control device 5 (applying propulsive force corresponding to the displacement amount of the input shaft 13 to the primary piston 15.
Hereinafter, the axial direction of the master cylinder MC is the x-axis direction, the bottom side of the master cylinder MC that is the left direction in the figure is the x-axis positive direction, and the brake pedal BP side is the x-axis negative direction.

The master cylinder MC is a so-called tandem type cylinder. In the cylinder 16 of the master cylinder MC, a primary piston 15 as an assist member and a secondary piston 17 are provided, and both 15 and 17 are arranged apart from each other in the axial direction by a gap L2.
In the cylinder 16, a primary hydraulic pressure chamber 16 a is formed by the end surface of the primary piston 15 on the x-axis positive direction side and the end surface of the secondary piston 17 on the x-axis negative direction side. The primary hydraulic pressure chamber 16a is connected so as to be able to communicate with the primary circuit 11.

  The volume of the primary hydraulic chamber 16a changes as the primary piston 15 and the secondary piston 17 stroke in the cylinder 16. A return spring 15b that urges the primary piston 15 toward the negative x-axis direction is installed in the primary hydraulic chamber 16a.

In the cylinder 16, a secondary hydraulic pressure chamber 16 b is formed by the bottom surface in the cylinder 16 and the end surface of the secondary piston 17 on the x-axis positive direction side. The secondary hydraulic chamber 16b is connected so as to be able to communicate with the secondary circuit 12.
The volume of the secondary hydraulic chamber 16b changes as the secondary piston 17 strokes in the cylinder 16. In the secondary hydraulic pressure chamber 16b, a return spring 17b that urges the secondary piston 17 toward the negative x-axis direction is installed.

  The primary circuit 11 is provided with a primary hydraulic pressure sensor 11s. The primary hydraulic pressure sensor 11s detects the hydraulic pressure in the primary hydraulic pressure chamber 16a and transmits hydraulic pressure information indicating the detection result to the brake control unit 2 in order to adjust the friction braking torque.

  The secondary circuit 12 is provided with a secondary hydraulic pressure sensor 12s. The secondary hydraulic pressure sensor 12 s detects the hydraulic pressure in the secondary hydraulic pressure chamber 16 b in order to adjust the friction braking torque, and transmits hydraulic pressure information indicating the detection result to the brake control unit 2. A VDC actuator 30 is provided in the middle of both circuits 11 and 12.

  The end of the input shaft 13 on the x axis positive direction side penetrates the partition wall 15a of the primary piston 15 and is grounded in the primary hydraulic chamber 16a. The gap between the end of the input shaft 13 and the partition wall 15a of the primary piston 15 is sealed to ensure liquid tightness, and the end of the input shaft 13 is slidable in the axial direction with respect to the partition wall 15a. Is provided.

On the other hand, the end of the input shaft 13 on the x-axis negative direction side is connected to the brake pedal BP. When the driver steps on the brake pedal BP, the input shaft 13 moves to the x-axis positive direction side, and when the driver returns the brake pedal BP, the input shaft 13 moves to the x-axis negative direction side.
Further, the input shaft 13 is formed with a large-diameter portion 13a having a diameter smaller than the outer diameter of the flange portion 13f and larger than the inner circumference of the partition wall 15a of the primary piston 15. When the brake is not operated when no brake operation is performed, a gap L1 is provided between the end surface on the x-axis positive direction side of the large diameter portion 13a and the end surface on the x-axis negative direction side of the partition wall 15a. The gap L1 enables the primary piston 15 to move relative to the input shaft 13 in the negative x-axis direction. Thereby, when the regenerative cooperative control command is received from the integrated control device 5, the brake control unit 2 can reduce the friction braking torque by the regenerative braking torque.

Further, when the input shaft 13 is relatively displaced by the gap L1 in the x-axis positive direction with respect to the primary piston 15 by the gap L1, the end surface on the x-axis positive direction side of the large diameter portion 13a and the partition wall 15a come into contact with each other. The input shaft 13 and the primary piston 15 move integrally. As a result, the hydraulic fluid in the primary hydraulic chamber 16 a is pressurized, and the pressurized hydraulic fluid is supplied to the primary circuit 11.
The secondary piston 17 moves to the x-axis positive direction side by the pressure of the primary hydraulic chamber 16a. As a result, the hydraulic fluid in the secondary hydraulic chamber 16 b is pressurized, and the pressurized hydraulic fluid is supplied to the secondary circuit 12.

  The wheel cylinder WC is a friction braking device that applies friction braking torque to the wheel WH. A piston (not shown) is moved by hydraulic fluid from the cylinder 16, and a pad (not shown) connected to the piston is a disk. The rotor DR (see FIG. 1) is pressed.

  The reservoir tank RES has at least two liquid chambers separated from each other by a partition wall (not shown). One of the fluid chambers in the reservoir tank RES is connected to the primary fluid pressure chamber 16a of the master cylinder MC via the brake circuit 18a. The other fluid chamber is connected to the secondary fluid pressure chamber 16b through the brake circuit 18b so as to be able to communicate therewith.

Next, the electric booster 20 will be described.
The electric booster 20 adjusts the displacement amount of the primary piston 15, that is, the master cylinder pressure Pmc in accordance with a control command from the brake control unit 2. The electric booster 20 includes a drive motor 21 that generates a rotational force according to the amount of displacement of the input shaft 13, a speed reducer 22 that increases the rotational force of the drive motor 21, and a rotational force of the speed reducer 22 that is used as a master cylinder MC. And a rotation-translation conversion device 23 for transmitting to the device.

  The drive motor 21 is a three-phase DC (Direct Current) brushless motor. The drive motor 21 generates a rotational torque according to the detection signal from the stroke sensor 14 in accordance with a control command from the brake control unit 2. The drive motor 21 serves as an actuator that moves the primary piston 15 forward and backward.

The speed reducer 22 decelerates the output rotation of the drive motor 21 by a pulley speed reduction method. The reduction gear 22 includes a small-diameter driving pulley 22a provided on the output shaft of the driving motor 21, a large-diameter driven pulley 22b provided on the ball screw nut 23a of the rotation-translation converter 23, and a driving pulley 22a. And a belt 22c wound around the driven pulley 22b.
The reduction gear 22 amplifies the rotational torque of the drive motor 21 in accordance with the reduction gear ratio determined by the radius ratio between the driving pulley 22 a and the driven pulley 22 b and transmits the amplified torque to the rotation-translation converter 23.

  The rotation-translation conversion device 23 converts the rotational power of the drive motor 21 into translation power, and presses the primary piston 15 with the translation power. The rotation-translation converter 23 employs a ball screw system, and includes a ball screw nut 23a, a ball screw shaft 23b, a movable member 23c, and a return spring 23d.

  A housing member HSG1 is provided on the x-axis negative direction side of the master cylinder MC, and a housing member HSG2 is provided on the x-axis negative direction side of the housing member HSG1. A ball screw nut 23a is rotatably installed on the inner periphery of the bearing BRG provided in the housing member HSG2.

  The ball screw nut 23a is fitted to the driven pulley 22b. A hollow ball screw shaft 23b is screwed into the ball screw nut 23a. A plurality of balls are rotatably installed in the gap between the ball screw nut 23a and the ball screw shaft 23b.

  A movable member 23c is integrally provided at the end of the ball screw shaft 23b on the x-axis positive direction side, and the primary piston 15 is joined to the end surface of the movable member 23c on the x-axis positive direction side. The primary piston 15 is accommodated in the housing member HSG1. The end of the primary piston 15 on the x-axis positive direction side protrudes from the housing member HSG1 and is fitted to the inner periphery of the master cylinder MC.

  A return spring 23d is provided between the inner periphery of the housing member HSG1 and the outer periphery of the primary piston 15. The return spring 23d has an end on the x-axis positive direction side fixed to the bottom surface on the x-axis positive direction side in the housing member HSG1, and an end on the x-axis negative direction side engaged with the movable member 23c. The return spring 23d is installed to be compressed in the axial direction between the bottom surface and the movable member 23c, and urges the movable member 23c and the ball screw shaft 23b to the x-axis negative direction side.

  When the driven pulley 22b rotates, the ball screw nut 23a rotates integrally, and the ball screw shaft 23b translates in the axial direction by the rotational movement of the ball screw nut 23a. The primary piston 15 is pressed to the x-axis positive direction side via the movable member 23c by the thrust of the translational movement of the ball screw shaft 23b to the x-axis positive direction side. FIG. 2 shows a state in which the ball screw shaft 23b is maximum displaced in the negative x-axis direction when the brake is not operated. This state is the initial position of the ball screw shaft 23b.

  On the other hand, the elastic force of the return spring 23d acts on the ball screw shaft 23b in the opposite direction (x-axis negative direction side) to the translational thrust. For example, when a brake operation is performed, that is, even when the primary piston 15 is pressed in the positive x-axis direction and the master cylinder pressure Pmc is increased, the elastic force acts on the negative x-axis direction.

  A pair of springs 19 a and 19 b are disposed in an annular space 19 defined between the input shaft 13 and the primary piston 15. One end of the spring 19 a is locked to a flange portion 13 f provided on the input shaft 13, and the other end of the spring 19 a is locked to a partition wall 15 a of the primary piston 15. One end of the spring 19b is locked to the flange portion 13f, and the other end of the spring 19b is locked to the movable member 23c.

The springs 19a and 19b urge the input shaft 13 toward the neutral position of the relative displacement of the primary piston 15 and hold the input shaft 13 and the primary piston 15 in the neutral position of relative movement when the brake is not operated. To play a role. When the input shaft 13 and the primary piston 15 are relatively displaced in any direction from the neutral position by the springs 19a and 19b, a biasing force for returning the input shaft 13 to the neutral position acts on the primary piston VDC (( An abbreviation of Vehicle Dynamics Control) The actuator 30 is a well-known actuator described also in Patent Document 1. That is, the VDC actuator 30 includes a pump, a pressure increasing valve, and a pressure reducing valve which are not shown in the drawing, and a wheel cylinder pressure. Therefore, it is possible to perform so-called ABS control that adjusts the wheel cylinder pressure Pwc so that the wheels WH including the driving wheels are not locked when the driver performs braking.

Further, the VDC actuator 30 incorporates a pump (not shown). Therefore, the VDC actuator 30 can generate a hydraulic braking torque on the wheels WH including the drive wheels by the braking hydraulic pressure formed by the built-in pump in a state where no braking hydraulic pressure is generated in the master cylinder MC. Then, by using this hydraulic braking torque to generate an arbitrary braking force at any of the four wheels, it is possible to execute vehicle motion control (hereinafter referred to as VDC control).
The driving of the VDC actuator 30 is controlled by the VDC control unit 3.

(Regenerative braking device)
Next, the regenerative braking device B will be described.
The regenerative braking device B converts wheel rotational energy into electric power by a motor (motor / generator) 1 that is drivingly coupled to a drive wheel (wheel WH) shown in FIG. 1 via a speed reducer and a differential 6. That is, the motor 1 is controlled through AC / DC conversion in the inverter 41 by the three-phase PWM signal from the motor control unit 4. In the EV traveling mode that requires driving of the driving wheels (wheels WH shown in FIG. 1), the motor 1 is driven as a motor by the electric power from the high-power battery 42 to rotate the driving wheels (wheels WH shown in FIG. 1). . On the other hand, in a braking mode that requires braking, regenerative braking torque control is performed to drive the motor 1 as a generator to convert vehicle kinetic energy into electric power and collect it in the high-power battery 42.

The VDC control unit 3 and the motor control unit 4 control the hydraulic braking device A and the regenerative braking device B according to a command from the integrated control device 5.
Accordingly, the motor control unit 4 controls the regenerative braking torque by the motor 1 based on the regenerative braking torque command value from the integrated control device 5.
Further, the VDC control unit 3 controls the hydraulic braking torque in the wheel cylinder WC based on command values from the integrated control device 5 and the brake control unit 2.

  In addition to the stroke sensor 14 described above, the sensor group 100 includes a battery temperature sensor, a wheel speed sensor, a master cylinder pressure sensor, a wheel cylinder hydraulic pressure sensor, etc. (not shown).

Further, the motor control unit 4 calculates the maximum allowable regenerative braking torque of the motor 1 from the battery temperature and the estimated charge capacity of the high-power battery 42 (hereinafter referred to as the battery SOC) and transmits it to the integrated control device 5. To do.
Further, the VDC control unit 3 transmits the input wheel speed Vw, master cylinder pressure Pmc and wheel cylinder pressure Pwc to the integrated control device 5.

(Braking torque control)
When the driver performs a braking operation, the integrated control device 5 obtains a driver-requested total braking torque Treq based on various input information. Based on the control of the brake control unit 2 and the motor control unit 4, the braking torque control for generating the regenerative braking torque and the hydraulic braking torque is executed according to the driver request total braking torque Treq.

In this braking torque control, the switching control characteristic of the first embodiment will be described based on the flowchart of FIG.
As shown in FIGS. 8 and 9, this replacement control increases the hydraulic braking torque (friction torque) while reducing the rotational braking torque from the state where the rotational braking torque is generated as the braking torque. Control.

The flowchart shown in FIG. 3 shows the flow of processing in this switching control, and will be described below step by step.
In step S101 (required total braking torque detecting device), the driver requested total braking torque Treq is calculated, and the process proceeds to the next step S102. In the first embodiment, based on the operation of the brake pedal BP of the driver detected by the stroke sensor 14, the hydraulic braking torque that can be generated in the stroke is calculated, and this is set as the driver requested total braking torque Treq. In addition, when an automatic deceleration control means such as cruise control is provided, the final high-required driver braking torque Treq may be set to a select high value with the hydraulic braking torque.

  In step S102, the calculated vehicle body speed Vref is input, and the process proceeds to the next step S103. Here, the vehicle body speed Vref may be obtained by applying a certain low-pass filter to the average value of the wheel speed pulse sensor obtained from the wheel speed sensor provided on each wheel of the wheel WH. Alternatively, the value obtained from the wheel speed sensor is a value obtained by applying a low-pass filter to the signal of the rotation resolver of the motor 1 if there is a problem in resolution and detection time for calculating the vehicle speed in the extremely low speed range. May be used. Note that the low-pass filter is set such that if the filter is too strong (the time constant is large), the vehicle speed is output after the vehicle stops, and regenerative braking torque may remain.

In step S103, the effective regenerative braking torque _TRB is input, and the process proceeds to the next step S104. The execution regenerative braking torque _TRB is a regenerative braking torque actually realized in the motor 1 based on the regenerative braking command value, and a regenerative braking command value output from the motor control unit 4 is input to this. Calculate based on.

This regenerative braking command value is formed based on the final target regenerative braking torque.
The final target regenerative braking torque is calculated based on the regenerative maximum limit value and the basic target regenerative braking torque. The regenerative maximum limit value is set based on the maximum output and current value of the motor 1 and the specification of the hydraulic braking device A that performs regenerative coordination, and is the maximum value of the regenerative braking torque that can be generated at that time. The basic target regenerative braking torque is a regenerative braking torque that is determined according to the driver-requested total braking torque within a range of a vehicle speed limit value that is a maximum regenerative braking torque that is obtained in advance according to the vehicle speed. It is.

  In step S104, after setting a reference replacement vehicle speed line, the process proceeds to step S105. The reference replacement vehicle speed line is a limit value of the regenerative braking torque set corresponding to the vehicle speed, as shown in FIG. As shown in the figure, the reference replacement vehicle speed line has a regenerative braking torque limit value set to 0 at a low vehicle speed lower limit vehicle speed Vmin or lower, and a regenerative braking torque limit value at an upper vehicle speed Vmax or higher. It is set to a constant value. Between the vehicle speeds Vmin and Vmax, the limit value of the regenerative braking torque is a first-order proportional characteristic that is proportional to the increase in the vehicle speed and goes toward the constant value. In addition, as shown in FIG. 4 (a), the reference replacement vehicle speed line is not in a fixed proportional relationship with the regenerative braking torque limit value Tlim corresponding to the vehicle speed, and as shown in FIG. The higher the torque Treq, the higher the vehicle speed side (that is, the wider the width of the reference replacement vehicle speed line) may be set. In FIG. 4B, the limit vehicle speed V4 may be set to a higher vehicle speed as the driver request total braking torque Treq is larger in accordance with the driver request total braking torque Treq, as shown in FIG.

In step S105, after setting the preload start vehicle speed line, the process proceeds to step S106.
Here, the preload start vehicle speed line will be described.
As shown by the dotted line in FIG. 4A, the preload start vehicle speed line is set with a width on the high vehicle speed side with respect to the reference replacement vehicle speed line. That is, in the first embodiment, the width of the reference switching vehicle speed line is set wider as the limit value of the regenerative braking torque is larger than the reference switching starting vehicle speed line. Further, in the first embodiment, the inclination of the preload start vehicle speed line is changed according to the driver requested total braking torque Treq. That is, the larger the driver required total braking torque Treq, the wider the vehicle speed width from the reference replacement start vehicle speed line. At this time, an upper limit value is set for the vehicle speed range, and when the driver-requested total braking torque Treq is equal to or greater than a certain value, the vehicle speed range is set not to increase beyond the upper limit value.

  The preload starting vehicle speed line may be set constant regardless of the driver required total braking torque Treq without changing the width from the reference replacement starting vehicle speed line according to the driver required total braking torque Treq as described above. Good. In this case, as shown in FIG. 6A, the vehicle speed width with respect to the reference switching start vehicle speed line may be set wider as the regenerative braking torque is larger. Alternatively, as shown in FIG. 6B, it may be set so as to be substantially parallel to the reference replacement start vehicle speed line.

Incidentally, so that the difference between the driver request total braking torque Treq and execution regenerative braking torque T _RB acts as a friction braking torque T _FB. When this friction braking torque _TFB is applied to a certain level or more, it exceeds the initial non-linear region (region R1 in FIG. 8B) of the hydraulic braking device A to some extent, and preloading by preload regenerative braking torque reduction processing is performed. Even if it is not given, the pedal feel is hardly deteriorated. For this reason, in the first embodiment, in the setting of the preload start vehicle speed line in step S105, the driver-requested total braking torque Treq is equal to or greater than a preset setting value or the friction braking torque _TFB is equal to or greater than a preset setting value. In this case, the preload start vehicle speed line is matched with the reference replacement vehicle speed line. As a result, when the driver-requested total braking torque Treq is equal to or greater than a preset value or the friction braking torque _TFB is equal to or greater than a preset value, the preload regenerative braking torque reduction process described later is not executed.

Incidentally, in the setting of preload start speed line of the step S105, the driver request total braking torque Treq or frictional braking torque T _FB is in the case of more than the set value, be set to match the preload start speed line reference swap speed line processing Instead of the above, the following processing can be performed.
That is, in step S108 described later, when the above condition is satisfied, the preload regeneration limiting torque _TRATE is pasted to the upper limit value. Thus, when the above condition is satisfied, the preload regenerative braking torque reduction process is not substantially performed.

At step S106, after calculating the preload start regenerative braking torque _{T PRE,} the process proceeds to step S107. That is, as shown in FIG. 7, the preload start regenerative braking torque T _PRE is obtained from the intersection of the current vehicle body speed Vref and the preload start vehicle speed line.
In step S107, it is determined whether or not the current execution regenerative braking torque _TRB exceeds the preload start regenerative braking torque _TPRE . If the current execution regenerative braking torque _TRB exceeds the preload start regenerative braking torque _TPRE , it is determined that the preload regenerative braking torque reduction process needs to be performed, and the process proceeds to step S108, where the preload regenerative limiting torque _TRATE is set. Calculate.
Note that the preload regenerative limiting torque T _RATE is a regenerative braking torque when the preload regenerative braking torque reduction process is executed.

On the other hand, if the execution regenerative braking torque T _RB at step S107 does not exceed beyond the preload start regenerative braking torque T _PRE, since it is not necessary to apply a preload, the upper limit value of the preload regeneration limit torque T _RATE, according to the vehicle speed Step S108 is skipped and the process proceeds to Step S109.

Note that the preload regeneration limitation torque _{T RATE} in step S108 is for determining the current executing regenerative braking torque _{T RB} by subtracting the predetermined amount (Tstep), specifically, computed by the following formula (1) ( (See FIG. 7).
T _RATE = T _RB -Tstep (1)
The constant amount Tstep is an inclination that applies preload per control cycle, and this inclination (change speed) is a phenomenon in which the brake pedal BP is sucked due to a response delay of the hydraulic pressure in the initial nonlinear region of the brake device 10. Is set to be limited to a predetermined value or less. Therefore, the decreasing slope of the regenerative braking torque due to the preload regeneration limiting torque T _RATE is a gentler slope than the inclination due to the reference regenerative limiting torque T _DEC described later based on the reference replacement vehicle speed line.

In step S109, the reference regeneration limit torque _TDEC is set from the intersection (see FIG. 7) between the current vehicle speed Vref and the reference replacement vehicle speed line, and the process proceeds to step S110.
In step S110, after the low speed region regeneration limit torque T _VEL is determined, the process proceeds to step S111. The low speed range regeneration limit torque _TVEL is used to switch the braking torque from the regenerative braking torque to the hydraulic braking torque (friction braking torque) according to the vehicle speed in the low vehicle speed range just before the vehicle stops. Specifically, the low speed range regeneration limit torque T _VEL is determined by a select low of the preload regeneration limit torque T _RATE and the reference regeneration limit torque T _DEC . Therefore, when the preload regenerative braking torque reduction process is executed, the low speed range regenerative limit torque T _VEL is set to the preload regenerative limit torque T _RATE , and when the preload regenerative braking torque reduction process is not executed, the low speed range regenerative limit torque T _VEL = reference. Regeneration limit torque T _DEC is set.

In step S111, the regeneration limit value other than that including the low speed region regeneration limit torque _TVEL determined in step S110 is selected to determine the final regeneration limit torque. The final regenerative limiting torque is transmitted to the motor control unit as a regenerative braking torque command value.

Next, the operation of the first embodiment will be described based on the time charts of FIGS.
<Comparative example>
Here, for comparison with the first embodiment, an example of the operation in the case of the prior art to which the present invention is not applied will be described with reference to FIG.
That is, when executing the switching control for reducing the regenerative braking torque and raising the hydraulic braking torque (friction braking torque) from the braking state of only regenerative braking according to the decrease in the vehicle speed during braking, FIG. The case where it executes based only on the reference change vehicle speed line shown in a) will be described.

The operation example shown in FIG. 8 shows that the braking operation has been executed from the time t0, and the regenerative braking torque satisfies the driver request total braking torque Treq at the time t0.
In this case, as shown in FIG. 8A, the vehicle speed decreases from the time point t0, and the vehicle speed intersects the reference replacement vehicle speed line at the time point t01. Therefore, from the time t01, the regenerative braking torque is reduced, while the hydraulic braking torque (friction braking torque) is raised. At this time, the regenerative braking torque is decreased until the regenerative braking torque becomes zero with a decreasing gradient shown in FIG. This decrease gradient is defined as a reference decrease gradient (replacement decrease gradient).

When this replacement control is performed, the master cylinder pressure Pmc is very close to 0 MPa or 0 MPa. In this case, since the pedal stroke amount is within or near the gap L1, the hydraulic braking torque is raised by driving the drive motor 21 to raise the wheel cylinder pressure Pwc.
That is, when the driver-requested total braking torque Treq can be generated by the regenerative braking torque, the pedal stroke amount is within the range of the gap L1, and the primary piston 15 is shown in FIG. It has not moved from the initial position shown. Therefore, the drive motor 21 is driven to move the primary piston 15 in the positive x-axis direction, thereby raising the master cylinder pressure Pmc.

At this time, hydraulic braking as shown in FIG. 8B occurs due to idle running of the operating portion in the hydraulic pressure transmission path leading to the wheel cylinder WC and a response delay in the drive motor 21 in the initial movement of the primary piston 15. Torque rise delay occurs. That is, although the primary piston 15 is moving, the state where the master cylinder pressure Pmc corresponding to the position is not generated occurs, and thereby the rise of the hydraulic braking torque becomes nonlinear (in the region of R1 in the figure). ).
In this case, the reaction force due to the master cylinder pressure Pmc acting on the input shaft 13 is insufficient, causing the input shaft 13 to move in the positive x-axis direction, which leads to the suction of the brake pedal BP.
As a result, the pedal feel may be deteriorated.

FIG. 9 is a time chart showing an operation example of the first embodiment, and a braking operation similar to that of the comparative example shown in FIG. 8 is performed at time T1.
In the first embodiment, a preload start vehicle speed line is set on the high speed side in addition to the setting of the reference replacement vehicle speed line based on the processing of steps S104 and S105.
Therefore, as shown in FIG. 7, as the vehicle speed decreases during braking similar to the comparative example described above, the effective regenerative braking torque _TRB reaches the preload start vehicle speed line before reaching the reference replacement vehicle speed line as shown in FIG. When crossing, the preload regeneration limiting torque T _RATE is calculated (steps S107 → S108). Then, this is determined as the low speed region regeneration limit torque T _VEL and is further determined as the final regeneration limit torque (steps S110 → S111). In this case, as shown in FIG. 7, the preload regeneration limit torque T _RATE has a value lower than the reference regeneration limit torque T _DEC .
Therefore, as shown in FIG. 9B, the regenerative braking torque is reduced to the preload regenerative limiting torque T _RATE at the time T2 earlier than the reference timing T3 that is the regenerative braking torque reduction timing by the reference replacement vehicle speed line. .
In this case, reducing the amount of the regenerative braking torque, based on the processing of the step S108, the calculated value according to equation (1), i.e., a value obtained by subtracting a certain amount (Tstep) from the current execution regenerative braking torque T _RB. The preload decreasing gradient, which is a decreasing gradient in this case, is a gentler gradient than the reference decreasing gradient as the replacement decreasing gradient.

Accordingly, the hydraulic braking torque corresponding to the decrease is started from the time T2 when the reduction of the regenerative braking torque is started. The rise of the hydraulic braking torque in this case, that is, the rise of the master cylinder pressure Pmc in the brake device 10 is slower than in the conventional case where the regenerative braking torque is reduced based on the reference decreasing gradient. Get up.
In this case, the moving speed of the primary piston 15 is also slow compared to the comparative example, so that the rising delay of the hydraulic braking torque is alleviated. Therefore, the reaction force shortage due to the master cylinder pressure Pmc on the input shaft 13 is less likely to occur.

Thereafter, the reference regeneration limit torque T _DEC determined on the basis of the reference replacement vehicle speed line is lower than the preload regeneration limit torque T _RATE due to a further decrease in the vehicle speed. That is, for example, in the case where the vehicle speed is reduced to the current vehicle speed Vref2 in FIG.
This time point corresponds to the time point T4 in FIG. 9B, that is, the reference start timing, and after this time point, it is lowered by the reference decrease gradient based on the reference regeneration limit torque _TDEC .
Therefore, the hydraulic braking torque is increased from the time point T4 with a rising slope during the conventional switching control.
Thereafter, the regenerative braking torque is set to 0 at the timing of T5 when the vehicle speed is reduced to the preset lower limit vehicle speed Vmin. This vehicle speed is an extremely low speed of 10 km / h or less, for example.

As described above, in the first embodiment, at the time of braking in a state where the driver requested total braking torque Treq is low, the regenerative braking torque reduction timing at the time of replacement control is advanced and the amount of decrease is moderate.
Therefore, the rising timing of the hydraulic braking torque (friction braking torque) is also advanced, and the rising change amount is also gradual.
As a result, the rise of the friction braking torque becomes gentle as shown in FIG. 9B, and the moving speed of the primary piston 15 by the drive motor 21 is reduced. As a result, as shown in FIG. 9C, the amount of change in the pedal stroke amount can be suppressed to a small value.
Therefore, deterioration of the pedal feel can be suppressed.

Below, the effect of the vehicle braking control apparatus of Embodiment 1 is demonstrated.
(1) The vehicle brake control device of the first embodiment is
A part that executes the process of step S101 in the stroke sensor 14 and the integrated control device 5 as a requested total braking force detection device that detects a driver requested total braking torque Treq at the time of a driver's braking operation in the vehicle;
A regenerative braking device B for controlling a regenerative braking torque applied to the wheel WH of the vehicle;
A hydraulic braking device A capable of generating a braking hydraulic pressure in accordance with a braking operation and increasing the braking hydraulic pressure by driving a drive motor 21 as an actuator;
The integrated control device 5 and each control unit 2 as a braking torque control unit that controls the driving of the regenerative braking device B and the hydraulic braking device A to control the regenerative braking torque and the hydraulic braking torque during the braking operation of the driver. 4 and
Based on a reference replacement vehicle speed line that is included in this braking torque control unit and sets a limit value of the regenerative braking torque corresponding to a preset vehicle speed, the drive motor 21 is operated while reducing the regenerative braking torque, and the hydraulic pressure is reduced. A change control unit (a part for executing the processes of steps S102 to S111) for executing a change control for increasing the braking torque;
A vehicle brake control device comprising:
The replacement control unit performs preload regenerative braking torque reduction processing for reducing the regenerative braking torque at a time before the reference start timing, which is a time when the regenerative braking torque determined by the reference replacement vehicle speed line is decreased when the replacement control is executed (S105). To S110).
In the first embodiment, as described above, the reference start is the timing at which the regenerative braking torque based on the reference replacement vehicle speed line is reduced when the replacement control for increasing the hydraulic braking torque is performed while reducing the regenerative braking torque. The preload regenerative braking torque reduction process (the processes of S105 to S110) for reducing the regenerative braking torque before the timing (T4 in FIG. 9B) (T3 in FIG. 9B) is executed.
Thereby, in the brake device 10 of the hydraulic braking device A, the timing for moving the primary piston 15 by driving the drive motor 21 is advanced. Therefore, the timing at which the master cylinder pressure Pmc rises due to the movement of the primary piston 15 becomes earlier, and the rising characteristic of the hydraulic braking torque at the time of rising can be made closer to linear. Therefore, it is possible to suppress the phenomenon of the brake pedal BP being sucked in due to the delay in the rise of the master cylinder pressure Pmc, and the pedal feel can be improved.

(2) The vehicle brake control device of the first embodiment is
In executing the preload regenerative braking torque reduction process, the replacement control unit sets a preload start vehicle speed line on the higher vehicle speed side than the reference replacement vehicle speed line, and executes the regenerative braking torque T that is actually generated. when _RB reaches the preload start speed lines, reducing the regenerative braking torque at moderate preload swap decreasing gradient than swap decreasing gradient when the reference start timing reduces the regenerative braking torque, execution regenerative braking torque T _RB is, When reaching the reference replacement vehicle speed line, the regenerative braking torque is decreased with a replacement decrease gradient.
Therefore, during the replacement control, in addition to advancing the regenerative braking torque reduction timing by the preload regenerative braking torque reduction process, the decreasing gradient becomes gentle.
As a result, the moving speed when moving the primary piston 15 by driving the drive motor 21 in the brake device 10 is slower than in the control by the reference replacement vehicle speed line, and the rise of the master cylinder pressure Pmc becomes gentle.
As described above, by slowly increasing the master cylinder pressure Pmc with sufficient time, the delay in the rise of the master cylinder pressure Pmc with respect to the position of the primary piston 15 can be further suppressed. Thereby, it becomes possible to suppress more effectively the phenomenon in which the input shaft 13 and the brake pedal BP are sucked, and the pedal feel can be further improved.

(3) The vehicle brake control device of the first embodiment is
The replacement control unit sets the preload start vehicle speed line, and the preload start vehicle speed line setting unit (execution part of step S105) increases the width of the preload start vehicle speed line with the reference replacement vehicle speed line as the regenerative braking torque increases. Widely set on the high speed side.
Therefore, as the execution regenerative braking torque _TRB is larger, the preload regenerative braking torque reduction process is executed at a timing earlier than the pressure reduction timing by the reference replacement vehicle speed line, thereby setting the rising timing of the hydraulic braking torque earlier. The
Accordingly, the control by the reference swap speed line, as performed regenerative braking torque T _RB is large, but the movement speed of the primary piston 15 is increased, it becomes possible to make the moving velocity more slowly. As a result, the above-described phenomenon of the brake pedal BP being sucked in can be more effectively suppressed.

(4) The vehicle brake control device of the first embodiment is
The preload start vehicle speed line setting unit (the execution part of the process of step S105) increases the width of the preload start vehicle speed line with the reference replacement vehicle speed line as the driver request total brake torque Treq increases in accordance with the driver request total brake torque Treq. Widely set on the side.
Accordingly, as the driver-requested total braking torque Treq is larger, the preload regenerative braking torque reduction process is executed at a timing earlier than the pressure reducing timing by the reference replacement vehicle speed line, and thereby the rising timing of the hydraulic braking torque is also set earlier. The
Therefore, as the driver requested total braking torque Treq is larger, the moving speed of the primary piston 15 can be made more gentle, and thereby the above-described phenomenon of the brake pedal BP being sucked in can be more effectively suppressed. Become.

(5) The vehicle brake control device of the first embodiment is
The preload start vehicle speed line setting unit (the execution part of the processing of step S105) is an upper limit value that does not change the preload start vehicle speed line to the higher speed side when the driver-requested total braking torque Treq is greater than or equal to a preset set value. It is characterized by having.
When the driver's requested total braking torque Treq is large to some extent, the deceleration is realized by using the hydraulic braking torque by the hydraulic braking device A as well, so that the start timing of the preload regenerative braking torque reduction process is not accelerated during the switching control. However, the deterioration of the pedal feel can be suppressed. Therefore, when the driver-requested total braking torque Treq is large to some extent, the regeneration efficiency is kept high by reducing the preload time (= time for reducing regeneration) by setting an upper limit value for the preload start vehicle speed line. Is possible.

(6) The vehicle brake control device of the first embodiment is
The switching control unit executes the preload regenerative braking torque reduction process only when either the driver-requested total braking torque Treq or the hydraulic braking torque as the friction braking torque is equal to or less than a preset set value. Features.
Specifically, the preload start vehicle speed line setting unit (the execution part of the process of step S105) sets the preload start vehicle speed line as the reference water change vehicle speed when the driver-requested total braking torque Treq is equal to or greater than a preset set value. It is characterized by matching with the line.
In other words, when the driver-requested total braking torque Treq is equal to or greater than a predetermined value, and when the hydraulic pressure braking torque has a predetermined abnormality, the master cylinder pressure Pmc is also generated to some extent. In this state, even if the drive motor 21 is driven and the primary piston 15 is moved, there is no response delay corresponding to the loss stroke of the wheel cylinder WC, and the pedal suction phenomenon hardly occurs. Therefore, in such a case, it is possible to cancel the preload regenerative braking torque reduction process by making the preload start vehicle speed line coincide with the reference water change vehicle speed line, and to keep the regeneration efficiency higher.

(7) The vehicle braking control device of the first embodiment is
The hydraulic braking device A includes an input shaft 13 as an input member that moves forward and backward by an operation of a brake pedal BP, a primary piston 15 as an assist member that is disposed so as to be relatively movable with respect to the input shaft 13, and the primary piston 15 And a drive motor 21 as an actuator for moving the actuator forward and backward, and generates a brake fluid pressure boosted in the master cylinder MC by an assist thrust applied to the primary piston 15 in accordance with the movement of the input shaft 13 by the brake pedal BP. An electric booster 20 is provided.
When switching control is performed using such an electric booster 20, in a state where almost no hydraulic braking torque is generated, the drive motor 21 is driven to move the primary piston 15 to move the master cylinder pressure Pmc. When the brake pedal is started up, the brake pedal BP is sucked and a phenomenon is likely to occur.
Therefore, the pedal suction phenomenon can be effectively suppressed by executing the above-described preload regenerative braking torque reduction process.

  As mentioned above, although the vehicle brake control apparatus of the present invention has been described based on the first embodiment, the specific configuration is not limited to the first embodiment, and each claim of the claims Design changes and additions are allowed without departing from the gist of the invention.

In the first embodiment, an example in which the vehicle braking control device of the present invention is applied to an electric vehicle has been described. However, the application target of the present invention may be a vehicle including a hydraulic braking device and a regenerative braking device. For example, it is not limited to an electric vehicle. For example, in a so-called hybrid vehicle equipped with an engine and a motor / generator as a drive source for the drive wheels, or a vehicle that can drive the drive wheels only by the driving force of the engine but can perform regenerative braking. Can also be applied.
In addition, a reference decrease gradient that is 0 at a preset vehicle speed is shown as a change decrease gradient that is a decrease gradient at the time of the change control, but the point is that the change is limited to this gradient as long as it decreases at the change control. It is not something.

2 Brake control unit (braking torque control unit)
4 Motor control unit (braking torque controller)
5 Integrated control device (braking torque control unit)
DESCRIPTION OF SYMBOLS 10 Brake apparatus 11 Primary circuit 12 Secondary circuit 13 Input shaft (input member)
15 Primary piston (assist member)
20 Electric Booster 21 Drive Motor (Actuator)
A fluid pressure braking device B regenerative braking apparatus BP brake pedal MC master cylinder _{T RB} perform regenerative braking torque Treq driver demand total braking torque WC wheel cylinder WH wheel

Claims (7)

A requested total braking torque detection device for detecting a driver requested total braking torque at the time of a driver's braking operation in a vehicle;
A regenerative braking device that controls regenerative braking torque applied to the wheels of the vehicle;
A hydraulic brake device that generates a brake hydraulic pressure in association with the braking operation and can increase the brake hydraulic pressure by driving an actuator;
A braking torque control unit that controls driving of the regenerative braking device and the hydraulic braking device to control the regenerative braking torque and the hydraulic braking torque during a braking operation of the driver;
Based on a reference replacement vehicle speed line that is included in the braking torque control unit and sets a limit value of the regenerative braking torque corresponding to the preset vehicle speed, the actuator is operated while reducing the regenerative braking torque. A change control unit for executing a change control for increasing the hydraulic braking torque;
A vehicle brake control device comprising:
The replacement control unit, when executing the replacement control, preload regenerative braking that decreases the regenerative braking torque at a time before a reference start timing, which is a time when the regenerative braking torque determined by the reference replacement vehicle speed line is decreased. A braking control device for a vehicle, which executes a torque reduction process. The vehicle brake control device according to claim 1,
In executing the preload regenerative braking torque reduction process, the replacement control unit sets a preload start vehicle speed line at a higher vehicle speed side than the reference replacement vehicle speed line, and executes an actual regeneration regenerative braking torque. When the braking torque reaches the preload start vehicle speed line, the regenerative braking torque is decreased at a preload replacement decreasing gradient that is gentler than the replacement decreasing gradient in the case of decreasing the regenerative braking torque from the reference start timing, and the execution regeneration is performed. When the braking torque reaches the reference replacement vehicle speed line, the regenerative braking torque is reduced with the replacement decreasing gradient, wherein the vehicle braking control device is characterized. The vehicle brake control device according to claim 2,
The preload start vehicle speed line setting unit that sets the preload start vehicle speed line sets the width of the preload start vehicle speed line to the reference replacement vehicle speed line wider on the high speed side as the regenerative braking torque increases. A vehicle brake control device. The vehicle brake control device according to claim 3, wherein
The preload start vehicle speed line setting unit sets the width of the preload start vehicle speed line to the reference replacement vehicle speed line wider on the high speed side as the driver request total brake torque increases in accordance with the driver request total brake torque. Brake control device for vehicle characterized by the above. The vehicle brake control device according to claim 4, wherein
The preload start vehicle speed line setting unit has an upper limit value that does not change the preload start vehicle speed line to the higher speed side when the driver-requested total braking torque is equal to or greater than a preset set value. A vehicle brake control device. In the vehicle brake control device according to any one of claims 1 to 5,
The replacement control unit executes the preload regenerative braking torque reduction process only when either the driver-requested total braking torque or the friction braking torque is equal to or less than a preset set value. Brake control device for vehicles. In the vehicle brake control device according to any one of claims 1 to 6,
The hydraulic braking device includes an input member that moves forward and backward by an operation of the brake pedal, an assist member that is arranged to be relatively movable with respect to the input member, and the actuator that moves the assist member forward and backward. Brake for a vehicle, comprising: an electric booster that generates a brake fluid pressure boosted in a master cylinder by an assist thrust applied to the assist member in response to movement of the input member by a pedal Control device.