Vehicle braking control device

Abstract

To provide a brake control device of a vehicle which can suppress the increase / decrease of the deceleration not intended by a driver when replacing regenerative brake torque with fluid pressure brake torque in a state where the regenerative brake torque is generated with an automatic brake function.SOLUTION: Control units (90, 100) controlling a fluid pressure brake system (1), when a driver steps on a brake pedal (3) during the automatic brake control and regenerative brake torque (T_reg) decreases in a state where the regenerative brake torque (T_reg) and brake fluid pressure (P_whl) are generated, increases the brake fluid pressure (P_whl) by driving a brake fluid pressure control unit (30) and relatively retracts a valve body (15) of an electric brake booster (10).SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a braking control device for a vehicle.

Background Art

[0002] In recent years, vehicles have been equipped with an automatic braking function. As an automatic braking function, for example, a driving support device also called ADAS (Advanced Driver-Assistance System) is known to automatically generate braking torque based on information in front of the vehicle detected by a camera or sensors mounted on the vehicle. Such an automatic braking function includes an ACC (Adaptive Cruise Control) automatic braking function for automatically driving the vehicle while maintaining the inter-vehicle distance from the preceding vehicle at a target inter-vehicle distance, and an emergency braking function for avoiding a collision with an obstacle or reducing an impact.

[0003] Also, as another automatic braking function, in an electric vehicle or a hybrid electric vehicle (hereinafter collectively referred to as an "electric vehicle"), a function of automatically generating braking torque when the driver releases the accelerator pedal while depressing the accelerator pedal is known.

[0004] In an electric vehicle, as a function of automatically generating braking torque, a hydraulic brake that controls the brake hydraulic pressure of each wheel by a brake hydraulic control unit equipped with an electric oil pump and an electromagnetic control valve to generate braking torque on the wheel, and a regenerative brake that generates braking torque on the wheel by generating electricity in the motor by the rotational torque of the wheel are used in combination. In the regenerative brake, the rotational kinetic energy of the wheel is converted into electric power and charged to the battery.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When activating the automatic braking function in the above electric vehicle, the regenerative brake is preferentially used to increase the power generation efficiency by the regenerative brake (hereinafter also referred to as "regeneration efficiency"). However, the deceleration torque obtained by the regenerative brake has a limit depending on the specifications of the motor. When the required deceleration torque exceeds the maximum deceleration torque by the regenerative brake, the brake hydraulic control unit can be further controlled to generate hydraulic brake torque to satisfy the required deceleration torque. Also, as the vehicle decelerates, the rotational speed of the wheels decreases, so the regenerative brake torque is replaced by the hydraulic brake torque before the vehicle stops.

[0007] In order to compensate for the regenerative brake torque that decreases as the rotational speed of the wheels decreases, it is necessary to increase the brake hydraulic pressure. At this time, the brake fluid is replenished from the master cylinder by driving the electric oil pump, so the master cylinder pressure decreases. For this reason, the reaction force of the pedal felt by the driver becomes smaller, and there is a risk that the brake pedal may be depressed further unintentionally. Also, due to the decrease in the master cylinder pressure, the compensation of the deceleration torque by the increase in the brake hydraulic pressure for the decrease in the regenerative brake torque becomes insufficient, and there is a risk that the deceleration of the vehicle may decrease unintentionally.

[0008] An object of the present invention is to provide a braking control device for a vehicle that improves the above problems that may occur when replacing the regenerative brake torque with the hydraulic brake torque in a state where the regenerative brake torque is generated by the automatic braking function.

Means for Solving the Problems

[0009] In order to solve the above problems, according to one aspect of the present invention, an electric brake booster that multiplies the stepping force of the brake pedal by a driver by advancing a valve body by driving an electric motor to advance a piston of a master cylinder and pressurizes brake fluid in the master cylinder, and a brake fluid pressure control unit that adjusts the brake fluid pressure generated in each wheel, and a control unit that controls a hydraulic brake system including the same, wherein the control unit sets an automatic brake request torque as a target brake torque while receiving a braking request signal by an automatic brake function, and when the driver depresses the brake pedal while receiving the braking request signal by the automatic brake function, sets the sum of the automatic brake request torque and the driver request brake torque as the target brake torque and executes brake control. In a braking control device for a vehicle, while receiving a braking request signal by the automatic brake function, when the driver depresses the brake pedal , return When the regenerative brake torque decreases while the raw brake torque and the brake fluid pressure are generated, a braking control device for a vehicle is provided that drives the brake fluid pressure control unit to increase the brake fluid pressure and retracts the valve body of the electric brake booster.

Effect of the Invention

[0010] As described above, according to the present invention, in a hydraulic brake system of a vehicle including an electric brake booster and a brake fluid pressure control unit, when replacing the regenerative brake torque with the hydraulic brake torque in a state where the regenerative brake torque is generated by the automatic brake function, it is possible to suppress an increase or decrease in the deceleration unintended by the driver.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0013] <1. Configuration Example of Hydraulic Brake System> First, a configuration example of a hydraulic brake system applicable to the braking control device for a vehicle according to this embodiment will be described.

[0014] FIG. 1 is a schematic diagram showing a configuration example of a hydraulic brake system 1 for a vehicle. The hydraulic brake system 1 of the vehicle shown in Fig. 1 is a brake system for a four-wheel electric vehicle (including a hybrid electric vehicle). The hydraulic brake system 1 is configured as a brake system that includes two brake systems, and in each brake system, one front wheel and one rear wheel are grouped together to control the braking torque.

[0015] Note that the hydraulic brake system 1 may be a so-called X-type piping system brake system in which the two brake systems control the braking torque with one front wheel on either the left or right and the rear wheel at a diagonal position to the front wheel as a set. Alternatively, the hydraulic brake system 1 may be a so-called H-type piping system brake system in which one system brakes the front and rear wheels on the left and the other system brakes the front and rear wheels on the right. Also, the hydraulic brake system may be a brake system for a vehicle other than a four-wheeled vehicle.

[0016] The hydraulic brake system 1 includes an electric brake booster 10, a master cylinder 5, and a brake hydraulic control unit 30. The hydraulic brake system 1 also includes a hydraulic control device 90 that controls the brake hydraulic control unit 30 and a booster device control device 100 that controls the electric brake booster 10. The hydraulic control device 90 and the booster device control device 100 are each partially or entirely composed of, for example, a microcomputer or a microprocessor unit that includes an arithmetic processing device such as a CPU (Central Processing Unit). Part or all of the hydraulic control device 90 and the booster device control device 100 may be composed of something updatable such as firmware, or may be program modules executed according to instructions from a CPU or the like.

[0017] The hydraulic control device 90 and the booster device control device 100 are configured to be able to communicate with each other via a communication bus 140 such as a CAN (Controller Area Network), for example. Also, the hydraulic control device 90 and the booster device control device 100 are configured to be able to communicate with an operation support device 110 and a motor control device 130 via the communication bus 140.

[0018] In the hydraulic brake system 1, the depressing force applied to the brake pedal 3 is amplified by the electric brake booster 10 and transmitted to the master cylinder 5 as a hydraulic pressure source. A reservoir tank 4 for supplying brake fluid to the master cylinder 5 is attached to the upper part of the master cylinder 5. Inside the master cylinder 5, a primary chamber 8 and a secondary chamber 9, which are two pressurized chambers partitioned by a primary piston 6 and a secondary piston 7, are formed. In response to the depressing operation of the brake pedal 3 by the driver, the primary piston 6 and the secondary piston 7 are pressed, and the brake fluid stored in the primary chamber 8 and the secondary chamber 9 respectively is pressurized, and the brake fluid is supplied into the brake fluid pressure control unit 30.

[0019] The electric brake booster 10 is connected to the brake pedal 3 via an input shaft 13. The depressing force amplified by the electric brake booster 10 is transmitted to the master cylinder 5 via a push rod 14 that abuts against the primary piston 6. The axial movement of the primary piston 6 causes the secondary piston 7 to also move axially. As a result, the brake fluid in the primary chamber 8 and the secondary chamber 9 is pressurized.

[0020] Figure 2 is a cross-sectional view partially showing the inside of the electric brake booster 10. The electric brake booster 10 includes a push rod 14, a valve body 15, a return spring 18, a plunger 16, a displacement sensor 80, and an assist mechanism 20. The plunger 16 is connected to an input shaft connected to a brake pedal (not shown) and moves forward and backward in accordance with the operation amount of the brake pedal. A key member 17 is fixed to the plunger 16.

[0021] The assist mechanism 20 receives the output of an electric motor (not shown) and moves the valve body 15 forward toward the master cylinder 5. The electric motor may be, for example, a brushless DC-DC motor including a stator as a fixed element and a rotor as a movable element. The electric motor operates upon receiving power (current) supply controlled by the multiplier control device 100. The electric motor is a motor capable of forward rotation for moving the valve body 15 forward and reverse rotation for moving the valve body 15 backward by switching the direction of the current.

[0022] The assist mechanism 20 includes a reduction gear 21, a hub 22, a spindle nut 23, a spindle 24, and a valve body 15. The hub 22 is fixed to the spindle nut 23, and the rotational output of the electric motor is reduced via the reduction gear 21 and transmitted to the hub 22 and the spindle nut 23. A support plate 25 for holding the valve body 15 is attached to the tip of the spindle 24. The valve body 15 and the support plate 25 are displaceable relative to the plunger 16 and the key member 17. A push rod 14 is connected to the front portion (master cylinder side) of the valve body 15 via a reaction disk 27 by a retainer 26.

[0023] Depending on the rotational direction of the electric motor 11, that is, the rotational direction of the spindle nut 23, the spindle 24 moves forward or backward relative to the spindle nut 23. When the spindle 24 moves forward toward the master cylinder side, the valve body 15 is pushed in the forward direction via the support plate 25 and moves forward against the biasing force of the return spring 18. Thereby, the brake fluid in the master cylinder is pressurized. Also, when the spindle 24 moves backward, the valve body 15 moves backward by the biasing force of the return spring 18.

[0024] The displacement sensor 80 detects the relative displacement amount of the plunger 16 with respect to the valve body 15 and outputs a sensor signal to the booster control device 100. Specifically, the displacement sensor 80 includes a magnet 81 fixed to a key member 17 that moves forward and backward together with the plunger 16, and an electrode 83 fixed to the valve body 15 at a position facing the magnet 81. The key member 17 and the valve body 15 are relatively displaceable, and the displacement sensor 80 outputs a current of a magnitude corresponding to the change in the magnetic field accompanying the relative displacement between the key member 17 and the valve body 15 to the booster control device 100. The relative displacement amount between the key member 17 and the valve body 15 corresponds to the relative displacement amount between the plunger 16 and the valve body 15.

[0025] The booster control device 100 detects the relative displacement amount of the plunger 16 with respect to the valve body 15 based on the magnitude of the current input from the displacement sensor 80. In the booster control device 100, the current value input from the displacement sensor 80 generated in the non-operating state of the electric brake booster 10 is used as the reference value when the relative displacement amount is zero. When the driver depresses the brake pedal, the plunger 16 moves forward relative to the valve body 15, and the displacement sensor 80 outputs a current corresponding to the relative displacement amount to the booster control device 100.

[0026] The booster control device 100 supplies power (current) to the stator of the electric motor 11 according to the relative displacement amount of the plunger 16 with respect to the valve body 15. When the driver depresses the brake pedal and the plunger 16 is displaced in the forward direction relative to the valve body 15, the booster control device 100 rotates the electric motor forward to move the valve body 15 forward. Conversely, when the driver releases the brake pedal and the plunger 16 is displaced in the backward direction relative to the valve body 15, the booster control device 100 rotates the electric motor in reverse to move the valve body 15 backward.

[0027] Returning to FIG. 1, from the hydraulic ports communicating with the primary chamber 8 and the secondary chamber 9 of the master cylinder 5 respectively, a first hydraulic circuit 31 and a second hydraulic circuit 32 extend toward the hydraulic brakes 38a - 38d of each wheel RF, LR, LF, RR. The hydraulic circuit of the brake system 1 of the vehicle according to this embodiment is of an X - type piping system. Brake fluid is supplied to the wheel cylinder of the hydraulic brake 38a of the right front wheel RF and the wheel cylinder of the hydraulic brake 38b of the left rear wheel LR via the first hydraulic circuit 31. Also, brake fluid is supplied to the wheel cylinder of the hydraulic brake 38c of the left front wheel LF and the wheel cylinder of the hydraulic brake 38d of the right rear wheel RR via the second hydraulic circuit 32. Thereby, each of the hydraulic brakes 38a - 38d can generate a braking force on each wheel RF, LR, LF, RR by hydraulic pressure.

[0028] The brake hydraulic control unit 30 includes a first hydraulic circuit 31 and a second hydraulic circuit 32 having the same configuration. Brake fluid is supplied to the first hydraulic circuit 31 and the second hydraulic circuit 32 from the master cylinder 5. Hereinafter, the first hydraulic circuit 31 will be briefly described, and the description of the second hydraulic circuit 32 will be omitted.

[0029] The first hydraulic circuit 31 includes, as solenoid valves, a circuit control valve 36a which is normally open and linearly controllable, a suction valve 34a which is normally closed and on - off controlled, pressure - increasing valves (adjusting valves) 58aa, 58ba which are normally open and linearly controllable, and pressure - reducing valves 54aa, 54ba which are normally closed and on - off controlled. Also, the first hydraulic circuit 31 includes a pump 44a driven by a pump motor 46, a low - pressure accumulator 71a, and a damper 73a. Note that the number of pumps 44a is not limited to one.

[0030] The first pressure increasing valve 58aa and the first pressure reducing valve 54aa provided adjacent to the hydraulic brake 38a of the right front wheel RF are used for the ABS (Antilock Brake System) control or ESP (Electronic Stability Program) control of the right front wheel RF. The second pressure increasing valve 58ba and the second pressure reducing valve 54ba provided adjacent to the hydraulic brake 38b of the left rear wheel LR are used for the ABS control or ESP control of the left rear wheel LR.

[0031] The first pressure increasing valve 58aa of the right front wheel RF is provided between the circuit control valve 36a and the hydraulic brake 38a of the right front wheel RF. The linearly controllable first pressure increasing valve 58aa continuously adjusts the flow rate of the brake fluid from the circuit control valve 36a side to the wheel cylinder side of the hydraulic brake 38a of the right front wheel RF. The first pressure increasing valve 58aa is provided with a bypass flow path having a check valve that allows the brake fluid to flow from the hydraulic brake 38a side to the circuit control valve 36a side while restricting the reverse flow when the first pressure increasing valve 58aa is closed.

[0032] The first pressure reducing valve 54aa of the right front wheel RF is a solenoid valve that can be switched only between the fully open or fully closed states, and is provided between the wheel cylinder of the hydraulic brake 38a of the right front wheel RF and the low-pressure accumulator 71a. The first pressure reducing valve 54aa reduces the pressure of the brake fluid supplied to the wheel cylinder of the hydraulic brake 38a of the right front wheel RF in the open valve state. The first pressure reducing valve 54aa can adjust the flow rate of the brake fluid flowing from the wheel cylinder of the hydraulic brake 38a of the right front wheel RF to the low-pressure accumulator 71a by intermittently repeating the opening and closing of the valve.

[0033] The second pressure increasing valve 58ba of the left rear wheel LR is provided between the circuit control valve 36a and the hydraulic brake 38b of the left rear wheel LR. The linearly controllable second pressure increasing valve 58ba continuously adjusts the flow rate of the brake fluid from the circuit control valve 36a side to the wheel cylinder side of the hydraulic brake 38b of the left rear wheel LR. The second pressure increasing valve 58ba includes a bypass flow path having a check valve that restricts the reverse flow while allowing the brake fluid to flow from the hydraulic brake 38b side to the circuit control valve 36a side when the second pressure increasing valve 58ba is in a closed state.

[0034] The second pressure reducing valve 54ba of the left rear wheel LR is a solenoid valve that can be switched only between a fully open or fully closed state, and is provided between the wheel cylinder of the hydraulic brake 38b of the left rear wheel LR and the low-pressure accumulator 71a. The second pressure reducing valve 54ba reduces the pressure of the brake fluid supplied to the wheel cylinder of the hydraulic brake 38b of the left rear wheel LR in the open valve state. The second pressure reducing valve 54ba can adjust the flow rate of the brake fluid flowing from the wheel cylinder of the hydraulic brake 38b of the left rear wheel LR to the low-pressure accumulator 71a by intermittently repeating the opening and closing of the valve.

[0035] The circuit control valve 36a is provided to communicate or cut off the connection between the pressure increasing valves 58aa, 58ba and the master cylinder 5. The intake valve 34a is provided to communicate or cut off the connection between the master cylinder 5 and the suction side of the pump 44a. A hydraulic sensor 33 is provided in the pipeline between the circuit control valve 36a and the intake valve 34a and the master cylinder 5. Since these are the same as the components of the conventional brake hydraulic control unit 30, detailed description thereof is omitted.

[0036] The second hydraulic circuit 32 controls the hydraulic brakes 38c of the left front wheel LF and 38d of the right rear wheel RR. The second hydraulic circuit 32 is configured in the same manner as the first hydraulic circuit 31, except that the wheel cylinder of the hydraulic brake 38a of the right front wheel RF in the description of the first hydraulic circuit 31 is replaced with the wheel cylinder of the hydraulic brake 38c of the left front wheel LF, and the wheel cylinder of the hydraulic brake 38b of the left rear wheel LR is replaced with the wheel cylinder of the hydraulic brake 38d of the right rear wheel RR.

[0037] In the following description, they are collectively referred to as the intake valve 34, the circuit control valve 36, the pressure increasing valve 58, and the pressure reducing valve 54, respectively.

[0038] <2. Vehicle Braking Control Device> So far, a configuration example of the hydraulic brake system 1 to which the vehicle braking control device is applicable has been described. Subsequently, a configuration example of the vehicle braking control device according to the present embodiment will be described.

[0039] (2-1. Configuration Example) FIG. 3 is a block diagram showing an example of a functional configuration related to the automatic brake function of ACC among the configurations of the vehicle braking control device 150 according to the present embodiment. The vehicle braking control device 150 includes a driving assistance device 110, a hydraulic control device 90, a booster device control device 100, and a motor control device 130. The driving assistance device 110, the hydraulic control device 90, the booster device control device 100, and the motor control device 130 are each composed of a microcomputer or a microprocessor unit including an arithmetic processing device such as a CPU or a GPU (Graphics Processing Unit). Some or all of these devices may be composed of updatable components such as firmware, or may be program modules executed according to instructions from a CPU or the like. In addition, each device includes a drive circuit (not shown) and storage elements such as a RAM and a ROM.

[0040] In this embodiment, the automatic braking function of ACC is executed by the hydraulic control device 90, the power amplifier control device 100, and the motor control device 130 communicating with each other and controlling the driving of the brake hydraulic control unit 30, the electric brake booster 10, and the drive motor 121 respectively based on the braking request signal S_brk transmitted from the driving assistance device 110. The hydraulic brake torque is controlled by the hydraulic control device 90 and the power amplifier control device 100, and the regenerative brake torque is controlled by the motor control device 130.

[0041] Note that all or part of the driving assistance device 110, the hydraulic control device 90, the power amplifier control device 100, and the motor control device 130 may be configured as one control device, or may be further divided into a plurality of control devices.

[0042] (2-1-1. Driving Assistance Device) The driving assistance device 110 is configured to be able to acquire the information detected by the sensor device 111 for detecting information on the environment in front of the vehicle, such as other vehicles, pedestrians, bicycles, and obstacles in front of the vehicle. The sensor device 111 includes at least one of, for example, a camera, a radar, and a LiDAR. The driving assistance device 110 is configured to be able to execute emergency braking control for avoiding the collision of the host vehicle with other vehicles or obstacles or reducing the impact at the time of collision, in addition to the ACC control for automatically driving the host vehicle while maintaining the inter-vehicle distance between the host vehicle and the preceding vehicle at the target inter-vehicle distance.

[0043] During the execution of the ACC control, the driving assistance device 110 determines whether braking is necessary and calculates an instruction value (automatic brake request torque) of the required brake torque based on the information detected by the sensor device 111 such as a camera, a radar, and a LiDAR, and transmits a braking request signal S_brk indicating the information of the automatic brake request torque T_req_in to the hydraulic control device 90 and the motor control device 130.

[0044] Specifically, the driving support device 110 obtains the inter-vehicle distance D between the host vehicle and the preceding vehicle and the relative speed dV of the host vehicle with respect to the preceding vehicle based on the information detected by the sensor device 111. The driving support device 110 determines whether braking is necessary based on the calculated information on the inter-vehicle distance D and the relative speed dV. For example, the driving support device 110 determines that braking is necessary when the inter-vehicle distance D between the host vehicle and the preceding vehicle becomes less than a braking start threshold D_brk_thr set according to the vehicle speed V of the host vehicle, the relative speed dV, and the target inter-vehicle distance D_tgt. The target inter-vehicle distance D_tgt may be a variable value set according to the vehicle speed V of the host vehicle. Note that the method for determining whether braking is necessary by the driving support device 110 is not particularly limited.

[0045] Further, the driving support device 110 calculates an automatic brake request torque T_req_in based on the vehicle speed V of the host vehicle, the relative speed dV, and the difference dD between the inter-vehicle distance D and the target inter-vehicle distance D_tgt. The change speed of the inter-vehicle distance D when a brake torque is generated in the vehicle may vary depending on the relative speed dV. Also, the brake torque for decelerating the vehicle may vary depending on the vehicle speed V. For this reason, the driving support device 110 may calculate the automatic brake request torque T_req_in by referring to map information in which the automatic brake request torque T_req_in is set in advance according to the vehicle speed V, the relative speed dV, and the difference dD in the inter-vehicle distance. Note that the method for calculating the automatic brake request torque T_req_in by the driving support device 110 is not particularly limited.

[0046] (2-1-2. Motor control device) The motor control device 130 includes a regenerative brake target torque setting unit 131 and a control unit 133. Part or all of the regenerative brake target torque setting unit 131 and the control unit 133 are functions realized by executing a program by a microcomputer. The motor control device 130 is configured to be able to acquire a braking request signal S_brk including information on the automatic brake request torque T_req_in transmitted from the driving assistance device 110. Also, the motor control device 130 is configured to be able to acquire information on the rotational speed N_whl of the wheels detected by a wheel speed sensor (not shown).

[0047] The motor control device 130 controls the drive motor 121 by controlling the drive of the inverter 123. The motor control device 130 converts the DC power supplied from the battery 125 into AC power and supplies it to the drive motor 121, and outputs a drive torque from the drive motor 121 (power running drive). In this case, the control unit 133 controls the drive of the inverter 123 based on the target drive torque set based on information such as the accelerator opening and the required acceleration.

[0048] Also, the motor control device 130 generates a regenerative brake torque by converting the AC power output from the drive motor 121 into DC power and supplying it to the battery 125 during deceleration of the vehicle (regenerative drive). In this case, the control unit 133 controls the drive of the inverter 123 based on the regenerative brake target torque set based on information such as the operation amount of the brake pedal and the required deceleration. When the inverter 123 includes a boost - buck circuit, the control unit 133 converts the AC power output from the drive motor 121 into DC power during deceleration of the vehicle, and drives the boost circuit to boost the voltage to the battery charging voltage.

[0049] Regarding the automatic braking function by ACC, when the regeneration brake target torque setting unit 131 receives the braking request signal S_brk by ACC from the driving assistance device 110, it sets the automatic braking request torque T_req_in as the regeneration brake target torque T_reg_tgt. However, when the automatic braking request torque T_req_in exceeds the maximum regeneration torque T_reg_pot of the drive motor 121, the regeneration brake target torque setting unit 131 sets the maximum regeneration torque T_reg_pot as the regeneration brake target torque T_reg_tgt. Further, when the rotational speed of the wheel decreases as the vehicle speed decreases, the regeneration brake target torque setting unit 131 sets the regeneration torque depending on the rotational speed N_whl of the wheel as the regeneration brake target torque T_reg_tgt.

[0050] The control unit 133 controls the driving of the inverter 123 based on the regeneration brake target torque T_reg_tgt set by the regeneration brake target torque setting unit 131 to generate the regeneration brake torque T_reg. The control unit 133 transmits the information of the regeneration brake torque T_reg generated by the drive motor 121 to the hydraulic control device 90. The control unit 133 may calculate the regeneration brake torque T_reg based on the rotational speed of the drive motor 121 and the output voltage of the generated power and transmit the calculated information of the regeneration brake torque T_reg to the hydraulic control device 90, or may transmit the information of the regeneration brake target torque T_reg_tgt to the hydraulic control device 90.

[0051] In this way, while receiving the braking request signal S_brk of the ACC control, the motor control device 130 compares the automatic braking request torque T_req_in with the maximum regeneration torque T_reg_pot, sets the smaller torque value of either as the regeneration brake target torque T_reg_tgt, and regeneratively drives the drive motor 121.

[0052] (2-1-3. Hydraulic control device) The hydraulic control device 90 includes a hydraulic brake target torque setting unit 91 and a control unit 93. Some or all of the hydraulic brake target torque setting unit 91 and the control unit 93 are functions realized by executing a program by a microcomputer. The hydraulic control device 90 is configured to be able to acquire a braking request signal S_brk including information on the automatic brake request torque T_req_in transmitted from the driving support device 110. Further, the hydraulic control device 90 is configured to be able to acquire information on the regenerative brake torque T_reg transmitted from the motor control device 130.

[0053] The hydraulic control device 90 executes ABS control and ESP control by controlling the drive of the brake hydraulic control unit 30. Further, when the hydraulic control device 90 receives the braking request signal S_brk for ACC control from the driving support device 110, it executes automatic brake control.

[0054] Regarding the automatic brake function of ACC, the hydraulic brake target torque setting unit 91 of the hydraulic control device 90 sets a target brake torque T_tgt based on the automatic brake request torque T_req_in transmitted from the driving support device 110. Further, when the driver depresses the brake pedal while the hydraulic control device 90 is receiving the braking request signal S_brk for ACC control, the sum of the automatic brake request torque T_req_in and the driver request brake torque T_dri is set as the target brake torque T_tgt (add-on type).

[0055] As described above, in the braking control device 150 of the vehicle according to the present embodiment, the regenerative braking torque T_reg is preferentially used. For this reason, the hydraulic control device 90 acquires information on the regenerative braking torque T_reg transmitted from the motor control device 130 and sets the value obtained by subtracting the regenerative braking torque T_reg from the target braking torque T_tgt as the hydraulic brake target torque T_hyd_tgt. When the regenerative braking torque T_reg is zero, the target braking torque T_tgt becomes the hydraulic brake target torque T_hyd_tgt. Further, when the regenerative braking torque T_reg starts to decrease from the state where the regenerative braking torque T_reg is generated, the hydraulic brake target torque T_hyd_tgt relatively increases.

[0056] After receiving the braking request signal S_brk for ACC control, the control unit 93 controls the drive of the brake hydraulic control unit 30 based on the hydraulic brake target torque T_hyd_tgt set by the hydraulic brake target torque setting unit 91 until the driver depresses the brake pedal. For example, the control unit 93 converts the hydraulic brake target torque T_hyd_tgt into the target brake hydraulic pressure P_tgt and controls the drive of the brake hydraulic control unit 30. Thereby, the braking torque of the vehicle is controlled. In the present embodiment, the control unit 93 calculates the target brake hydraulic pressure P_tgt to be generated at each wheel based on the target braking torque T_tgt, and controls the drive of the pump motor 46 and various electromagnetic control valves of the brake hydraulic control unit 30.

[0057] The control unit 93 may obtain the target brake hydraulic pressure P_tgt corresponding to the hydraulic brake target torque T_hyd_tgt by referring to the map information in which the relationship between the hydraulic brake target torque T_hyd_tgt and the target brake hydraulic pressure P_tgt is set in advance. The control unit 93 sets the target flow rate V_tgt of the brake fluid supplied from the master cylinder 5 to the brake hydraulic control unit 30 based on the calculated target brake hydraulic pressure P_tgt. The control unit 93 may set the target flow rate V_tgt of the brake fluid by referring to the map information in which the relationship between the target brake hydraulic pressure P_tgt and the target flow rate V_tgt is set in advance.

[0058] Note that the control unit 93 may set a target flow rate V_tgt according to the difference dP between the current brake hydraulic pressure P_whl and the target brake hydraulic pressure P_tgt. As the current brake hydraulic pressure P_whl, the pressure value detected by the hydraulic pressure sensor 33 can be alternatively used. When a brake hydraulic pressure sensor for detecting the brake hydraulic pressure of any wheel cylinder is provided separately from the hydraulic pressure sensor 33, the pressure value detected by the brake hydraulic pressure sensor may be used instead of the hydraulic pressure sensor 33.

[0059] When the control unit 93 operates the automatic brake function of ACC, the pressure increasing valve 58 is in the open valve state, the pressure reducing valve 54 is in the closed valve state, the circuit control valve 36 is in the closed valve state, and the suction valve 34 is in the open valve state, and a control signal is output to the drive circuit of the pump motor 46 according to the set target flow rate V_tgt to drive the pumps 44a and 44b. As a result, the brake fluid is supplied from the master cylinder 5 into the brake fluid pressure control unit 30, and the brake fluid is supplied to the wheel cylinders of each wheel. As a result, the brake hydraulic pressure of each wheel increases, and the hydraulic brake torque is generated.

[0060] When the driver depresses the brake pedal, the control unit 93 opens the circuit control valve 36, closes the suction valve 34, and stops driving the pumps 44a and 44b. As a result, the brake fluid is supplied from the master cylinder 5 to the brake fluid pressure control unit 30 along with the operation of the driver's brake pedal, and the brake hydraulic pressure P_whl increases according to the operation amount of the brake pedal.

[0061] In this way, after receiving the braking request signal S_brk for ACC control, the hydraulic control device 90 sets the value obtained by subtracting the regenerative braking torque T_reg from the automatic braking request torque T_req_in as the hydraulic brake target torque T_hyd_tgt until the driver depresses the brake pedal 3, and controls the drive of the brake hydraulic control unit 30 to generate the brake hydraulic pressure P_whl. Also, after the driver starts depressing the brake pedal 3 and until the regenerative braking torque T_reg starts to decrease, the hydraulic control device 90 stops pressurizing the brake hydraulic pressure P_whl by the brake hydraulic control unit 30. Further, when the regenerative braking torque T_reg starts to decrease after the driver starts depressing the brake pedal 3, the hydraulic control device 90 resumes pressurizing the brake hydraulic pressure P_whl by the brake hydraulic control unit 30. During this period, the hydraulic control device 90 transmits the information of the brake hydraulic pressure P_whl detected by the hydraulic sensor 33 or a brake hydraulic sensor (not shown) to the booster control device 100.

[0062] (2-1-4. Booster Control Device) The booster control device 100 includes a control unit 101. Part or all of the control unit 101 is a function realized by executing a program by a microcomputer. The booster control device 100 is configured to be able to acquire the braking request signal S_brk including the information of the automatic braking request torque T_req_in transmitted from the driving assistance device 110. Also, the booster control device 100 is configured to be able to acquire the information of the brake hydraulic pressure P_whl transmitted from the hydraulic control device 90. Further, the booster control device 100 is configured to be able to acquire the information of the relative displacement amount d_str of the plunger 16 with respect to the valve body 15 detected by the displacement sensor 80 provided in the electric brake booster 10.

[0063] The control unit 101 controls the driving of the electric motor 11 based on the information of the relative displacement amount d_str transmitted from the displacement sensor 80. Specifically, with the relative displacement amount d_str between the valve body 15 and the plunger 16 in a state where the electric motor 11 is not being driven as the reference value d_str_0, when the relative displacement amount d_str changes, the control unit 101 rotates the electric motor 11 forward or backward so that the relative displacement amount d_str becomes the reference value d_str_0. For example, the control unit 101 rotates the electric motor 11 forward or backward at a rotational speed corresponding to the change rate of the relative displacement amount d_str. Thereby, the valve body 15 moves forward or backward, and the brake fluid in the master cylinder 5 is pressurized or depressurized. When the brake fluid in the master cylinder 5 is pressurized, the brake fluid is supplied from the master cylinder 5 to the brake fluid pressure control unit 30, and hydraulic brake torque is generated on the wheels.

[0064] Also, regarding the automatic braking function of the ACC, in the braking control device 150 of the vehicle according to the present embodiment, when generating hydraulic brake torque by ACC control, the control unit 101 rotates the electric motor 11 forward in advance before the driver steps on the brake pedal, and moves the valve body 15 forward (offset) toward the master cylinder 5 side. At this time, the control unit 101 moves the valve body 15 forward within a range where the master cylinder pressure P_mc does not increase. The maximum offset amount d_ofs_max is set in advance in the booster control device 100 according to the displacement amount of the valve body 15 at which the master cylinder pressure P_mc starts to increase. Depending on the configuration of the electric brake booster 10, the relative displacement amount d_str of the valve body 15 at which the master cylinder pressure P_mc starts to increase is, for example, about 1.0 to 1.5 mm. In this case, the maximum offset amount d_ofs_max is set to, for example, 0.5 to 0.8 mm.

[0065] Specifically, after receiving the braking request signal S_brk from the driving assistance device 110, the control unit 101 controls the driving of the electric motor 11 based on the information of the brake hydraulic pressure P_whl transmitted from the brake hydraulic pressure control unit 30. There is a preset relative displacement amount d_str of the valve body 15 corresponding to the value of the brake hydraulic pressure P_whl. The control unit 101 rotates the electric motor 11 clockwise according to the acceleration rate of the received brake hydraulic pressure P_whl, and advances the valve body 15 within a range not exceeding the maximum offset amount d_ofs_max. As a result, the valve body 15 is in a state of advancing relative to the plunger 16.

[0066] Furthermore, when the driver depresses the brake pedal while the valve body 15 is offset, the control unit 101 drives the electric motor 11 according to the depression amount of the brake pedal by the driver while maintaining the maximum offset amount d_ofs_max, and advances the valve body 15. That is, taking the relative displacement amount d_str in the offset state as the offset reference value d_ofs_0, the driving of the electric motor 11 is controlled so that the relative displacement amount d_str between the valve body 15 and the plunger 16 is maintained at the offset reference value d_ofs_0. As a result, as the driver depresses the brake pedal, the master cylinder pressure P_mc increases, and the brake fluid is supplied to the brake hydraulic pressure control unit 30, causing the brake hydraulic pressure P_whl to increase.

[0067] Also, when the regenerative braking torque T_reg decreases while the control unit 101 is receiving the braking request signal S_brk of the ACC control, and the pressurization of the brake hydraulic pressure P_whl is restarted by driving the brake hydraulic pressure control unit 30, the control unit 101 drives the electric motor 11 to cancel the state where the valve body 15 is offset in the forward direction. That is, the control unit 101 rotates the electric motor 11 counterclockwise and retracts the valve body 15 in the direction of returning the relative displacement amount d_str between the valve body 15 and the plunger 16 to zero (reference value d_str_0).

[0068] In this way, while the booster control device 100 is receiving the braking request signal S_brk of the ACC control, based on the information of the brake hydraulic pressure P_whl transmitted from the brake hydraulic pressure control unit 30, if the brake hydraulic pressure P_whl rises before the driver steps on the brake pedal 3, the valve body 15 is offset within a range where the master cylinder pressure P_mc is not increased. Further, when the driver steps on the brake pedal 3 while the booster control device 100 is receiving the braking request signal S_brk of the ACC control, the electric motor 11 is driven based on the relative displacement amount d_str between the valve body 15 and the plunger 16 so as to maintain the relative displacement amount d_str between the valve body 15 and the plunger 16 at the offset reference value d_ofs_0 (or the reference value d_str_0). Furthermore, when the regenerative brake torque T_reg that has occurred while the driver is stepping on the brake pedal starts to decrease while the booster control device 100 is receiving the braking request signal S_brk of the ACC control, the valve body 15 is retracted in accordance with the increase in the brake hydraulic pressure P_whl caused by the drive of the brake hydraulic pressure control unit 30 to cancel the offset state.

[0069] (2-2. Operation example) Subsequently, a specific operation example of the braking control device 150 of the vehicle according to the present embodiment will be described.

[0070] (2-2-1. Detailed description of conventional operation and problems) First, before describing the operation example of the control process by the braking control device of the vehicle according to the present embodiment, the operation and problems of the conventional control process will be described in detail.

[0071] FIG. 4 shows the automatic brake request torque T_req_in, the brake torque T_act, the regenerative brake torque T_reg, and the hydraulic brake torque T_hyd during the execution of the ACC control, and the operating states of the pump (pmp) 44, the suction valve (HSV) 34, and the circuit control valve (USV) 36 of the brake hydraulic pressure control unit (ESP) 20. FIG. 4 shows an example of the basic operation when the driver does not step on the brake pedal 3 during the execution of the ACC control.

[0072] At time t1, after the execution of ACC control is started, in section a where the maximum regenerative torque T_reg_pot exceeds the automatic brake request torque T_req_in, the braking torque T_act is generated by the regenerative brake torque T_reg.

[0073] At time t2, when the automatic brake request torque T_req_in exceeds the maximum regenerative torque T_reg_pot, in subsequent section b, the braking torque T_act is generated by the regenerative brake torque T_reg and the hydraulic brake torque T_hyd. Specifically, at time t2, the intake valve 34 of the brake hydraulic control unit 30 is opened and the circuit control valve 36 is closed, and further the pump 44 is driven to generate a hydraulic brake torque T_hyd corresponding to the shortage with respect to the automatic brake request torque T_req_in.

[0074] At time t3, when the automatic brake request torque T_req_in becomes constant, the driving of the pump 44 is stopped and the hydraulic brake torque T_hyd is held in a constant state. Thereafter, at time t4, when the regenerative brake torque T_reg starts to decrease as the vehicle decelerates, the pump 44 is driven again and the hydraulic brake torque T_hyd increases to compensate for the decrease in the regenerative brake torque T_reg.

[0075] At time t5, when the regenerative brake torque T_reg is replaced by the hydraulic brake torque T_hyd and the regenerative brake torque T_reg becomes zero, in subsequent section c, the pump 44 is stopped again and the hydraulic brake torque T_hyd is held in a constant state. In section c, the braking torque T_act is generated by the hydraulic brake torque T_hyd.

[0076] Figure 5 shows an example when the driver depresses the brake pedal 3 during the execution of ACC control. Figure 5 is an example of generating the brake torque T_act by the above-described add-on type, and shows the automatic brake request torque T_req_in, the brake torque T_act, the regenerative brake torque T_reg, the brake fluid pressure P_whl and the master cylinder pressure P_mc, and the operating states of the pump (pmp) 44, the intake valve (HSV) 34 and the circuit control valve (USV) 36 of the brake fluid pressure control unit (ESP) 20. For ease of understanding, in Figure 5, the values of the hydraulic pressure (Prs) and the brake torque (Trq) are shown on the same scale, and the hydraulic brake torque T_hyd is shown by the brake fluid pressure P_whl.

[0077] At time t11, after the execution of ACC control is started, in section a where the maximum regenerative torque T_reg_pot exceeds the automatic brake request torque T_req_in, the brake torque T_act is generated by the regenerative brake torque T_reg.

[0078] At time t12, when the automatic brake request torque T_req_in exceeds the maximum regenerative torque T_reg_pot, in the subsequent section b, the brake torque T_act is generated by the regenerative brake torque T_reg and the brake fluid pressure P_whl. Specifically, at time t12, the intake valve 34 of the brake fluid pressure control unit 30 is opened and the circuit control valve 36 is closed, and further the pump 44 is driven to generate a brake fluid pressure P_whl corresponding to the torque shortage for the automatic brake request torque T_req_in. At time t13, when the automatic brake request torque T_req_in becomes constant, the driving of the pump 44 is stopped and the brake fluid pressure P_whl is held in a constant state.

[0079] At time t14, assuming that the driver depresses the brake pedal 3, in section α where the operation amount of the brake pedal 3 increases, the electric motor 11 of the electric brake booster 10 rotates forward to drive and the master cylinder pressure P_mc rises, and brake fluid is supplied from the master cylinder 5 to the brake fluid pressure control unit 30. In section α, the pump 44 of the brake fluid pressure control unit 30 is driven to supply the brake fluid supplied from the master cylinder 5 to the wheel cylinder, and the brake fluid pressure P_whl rises. The brake fluid pressure P_whl is the sum of the brake fluid pressure P_whl_org caused by the drive of the brake fluid pressure control unit 30 and the master cylinder pressure P_mc. Also, the generated brake torque T_act is the sum of the brake fluid pressure P_req corresponding to the automatic brake request torque T_req_in and the master cylinder pressure P_mc.

[0080] At time t15, when the operation amount of the brake pedal 3 becomes constant, the drive of the pump 44 of the brake fluid pressure control unit 30 is stopped, and the brake fluid pressure P_whl is maintained. Accordingly, the brake torque T_act is also maintained at a constant value. Thereafter, at time t16, when the regenerative brake torque T_reg begins to decrease as the vehicle decelerates, the pump 44 is driven again while narrowing the opening degree of the circuit control valve 36 in order to compensate for the decrease in the regenerative brake torque T_reg with the brake fluid pressure P_whl.

[0081] In section β after time t16, while the brake fluid pressure P_whl rises, since the increased brake fluid is inhaled from the master cylinder 5, the master cylinder pressure P_mc decreases. For this reason, the pedal feeling of the driver depressing the brake pedal 3 suddenly becomes lighter, and the operation amount of the brake pedal 3 increases despite the driver not intending it. Furthermore, since the increase amount of the brake fluid pressure P_whl is insufficient due to the decrease in the master cylinder pressure P_mc, the deceleration decreases despite the driver not intending it.

[0082] Thereafter, when the regenerative braking torque T_reg becomes zero at time t17, in the subsequent section c, the pump 44 is stopped again, and the brake hydraulic pressure P_whl is maintained in a constant state. In section c, the brake torque T_act is generated by the brake hydraulic pressure P_whl.

[0083] According to the operation of the control process of the conventional add-on type automatic brake torque in this way, when replacing the regenerative braking torque T_reg with the brake hydraulic pressure P_whl, the driver's pedal feeling suddenly becomes lighter due to the decrease in the master cylinder pressure P_mc, which may cause an increase in the operation amount of the brake pedal 3 not intended by the driver or a decrease in the deceleration rate.

[0084] (2-2-2. First Example According to this Embodiment) Next, a first example of the control process of the braking control device 150 of the vehicle according to this embodiment will be described.

[0085] FIG. 7 is an explanatory diagram showing the operation of the first example. The braking control device 150 of the vehicle according to this embodiment generates the brake torque T_act in an add-on manner when the driver depresses the brake pedal during the execution of the ACC control. FIG. 7 shows the automatic brake request torque T_req_in, the brake torque T_act, the regenerative braking torque T_reg, the brake hydraulic pressure P_whl, the master cylinder pressure P_mc, and the virtual master cylinder pressure P_mc_vrt, and the operating states of the pump (pmp) 44, the intake valve (HSV) 34, and the circuit control valve (USV) 36 of the brake hydraulic pressure control unit (ESP) 20, and the relative displacement amount d_str of the valve body 15 of the electric brake booster 10. For ease of understanding, in FIG. 7, the values of the hydraulic pressure (Prs) and the brake torque (Trq) are shown on the same scale, and the hydraulic brake torque T_hyd is shown by the brake hydraulic pressure P_whl.

[0086] At time t31, after the execution of ACC control is started, in section a where the maximum regenerative torque T_reg_pot exceeds the automatic brake request torque T_req_in, the braking torque T_act is generated by the regenerative brake torque T_reg.

[0087] At time t32, when the automatic brake request torque T_req_in exceeds the maximum regenerative torque T_reg_pot, in subsequent section b, the braking torque T_act is generated by the regenerative brake torque T_reg and the brake hydraulic pressure P_whl. Specifically, at time t32, the suction valve 34 of the brake hydraulic pressure control unit 30 is opened and the circuit control valve 36 is closed, and further the pump 44 is driven to generate a brake hydraulic pressure P_whl corresponding to the torque shortage with respect to the automatic brake request torque T_req_in. At time t33, when the automatic brake request torque T_req_in becomes constant, the drive of the pump 44 is stopped and the brake hydraulic pressure P_whl is held in a constant state.

[0088] In the present embodiment, in section δ from time t32 when the brake hydraulic pressure P_whl rises due to the drive of the brake hydraulic pressure control unit 30 to time t33, even before the driver steps on the brake pedal, the electric motor 11 is rotated forward in advance to offset the valve body 15 toward the master cylinder 5 side. The relative displacement amount d_str at this time increases as the brake hydraulic pressure P_whl rises. After the relative displacement amount d_str reaches the maximum offset amount d_ofs_max, the relative displacement amount d_str is held at the maximum offset amount d_ofs_max.

[0089] Thereafter, assuming that the driver depresses the brake pedal 3 at time t34, the intake valve 34 is closed and the circuit control valve 36 is opened. Also, in the section ε where the operation amount of the brake pedal 3 increases from time t34 to time t35, based on the offset state between the valve body 15 and the plunger 16 as the reference position, as the plunger 16 advances due to the increase in the operation amount of the brake pedal 3, the electric motor 11 is driven to rotate forward based on the relative displacement amount d_str between the valve body 15 and the plunger 16. As a result, the master cylinder pressure P_mc rises, and brake fluid is supplied from the master cylinder 5 to the brake fluid pressure control unit 30.

[0090] At this time, in this embodiment, since the brake torque T_act is controlled in an add-on manner, the brake fluid supplied from the master cylinder 5 is supplied to the wheel cylinder via the brake fluid pressure control unit 30. When the rigidity between the brake fluid pressure control unit 30 and the master cylinder 5 is high, the master cylinder pressure P_mc quickly rises to the brake fluid pressure P_whl_org with a slight operation of the brake pedal 3. After time t34, the sum of the brake fluid pressure P_whl_org generated by the drive of the brake fluid pressure control unit 30 and the virtual master cylinder pressure P_mc_vir that rises due to the driver's operation of the brake pedal 3 becomes the brake fluid pressure P_whl.

[0091] At this time, since the intake valve 34 is closed and the circuit control valve 36 is open, the master cylinder pressure P_mc becomes equal to the brake fluid pressure P_whl. However, since the output torque of the electric motor 11 corresponding to the relative displacement amount d_str (= maximum offset amount d_ofs_max) of the valve body 15 when the driver starts depressing the brake pedal 3 serves as a force to assist the driver's stepping force on the brake pedal 3, the reaction force that the driver feels on the brake pedal 3 is the reaction force corresponding to the virtual master cylinder pressure P_mc_vir that rises due to the driver's operation of the brake pedal 3.

[0092] At time t35, when the operation amount of the brake pedal 3 reaches a constant state, the rotational amount of the electric motor 11 is maintained, thereby maintaining the position of the valve body 15 and the brake hydraulic pressure P_whl. Accordingly, the brake torque T_act is also maintained at a constant value. Thereafter, at time t36, when the regenerative brake torque T_reg starts to decrease as the vehicle decelerates, in order to compensate for the decrease in the regenerative brake torque T_reg with the brake hydraulic pressure P_whl, the intake valve 34 of the brake hydraulic pressure control unit 30 is opened again and the circuit control valve 36 is closed, and the driving of the pump 44 is restarted.

[0093] In the section ζ after time t36, while the brake hydraulic pressure P_whl increases, since the increased brake fluid is sucked from the master cylinder 5, the master cylinder pressure P_mc decreases. At this time, in the present embodiment, the relative displacement amount d_str (= maximum offset amount d_ofs_max) of the valve body 15 that has been offset in the forward direction in advance is decreased in accordance with the decrease in the master cylinder pressure P_mc. Specifically, the electric motor 11 of the electric brake booster 10 is driven to rotate in the reverse direction, and the valve body 15 moves backward relative to the plunger 16. Thereby, it is possible to suppress the reduction of the driver's pedal feeling due to the decrease in the master cylinder pressure P_mc and prevent an unintentional reduction of the driver-requested brake torque. And since the driving of the brake hydraulic pressure control unit 30 does not affect the reaction force of the brake pedal 3 felt by the driver, it is not necessary to estimate the driver-requested brake torque.

[0094] Thereafter, at time t37, when the regenerative brake torque T_reg becomes zero, in the subsequent section c, the pump 44 is stopped again, and the brake hydraulic pressure P_whl is maintained in a constant state. In the section c, the brake torque T_act is generated by the brake hydraulic pressure P_whl. Note that in the section c, the driving of the electric motor 11 is controlled in accordance with the operation of the driver's brake pedal 3 so that the relative displacement amount d_str between the valve body 15 and the plunger 16 at time t37 is maintained, and the brake hydraulic pressure P_whl is adjusted.

[0095] Figure 8 shows a flowchart of a first example of the control process of the braking control device 150 of the vehicle according to the present embodiment. First, when the automatic braking function of ACC becomes active, the motor control device 130 regeneratively drives the drive motor 121 and starts increasing the regenerative braking torque T_reg (step S11). Specifically, when the regenerative braking target torque setting unit 131 of the motor control device 130 receives the braking request signal S_brk by ACC control from the driving assistance device 110, it sets the automatic braking request torque T_req_in as the regenerative braking target torque T_reg_tgt. However, when the automatic braking request torque T_req_in exceeds the maximum regenerative torque T_reg_pot of the drive motor 121, the regenerative braking target torque setting unit 131 sets the maximum regenerative torque T_reg_pot as the regenerative braking target torque T_reg_tgt. The control unit 133 of the motor control device 130 controls the driving of the inverter 123 based on the set regenerative braking target torque T_reg_tgt to generate the regenerative braking torque T_reg.

[0096] Next, the hydraulic control device 90 determines whether the automatic braking request torque T_req_in exceeds the maximum regenerative torque T_reg_pot (step S13). When the automatic braking request torque T_req_in is less than or equal to the maximum regenerative torque T_reg_pot (S13 / No), the process returns to step S11 and the determination in step S13 is repeated until the automatic braking request torque T_req_in exceeds the maximum regenerative torque T_reg_pot.

[0097] On the other hand, when the automatic brake demand torque T_req_in exceeds the maximum regenerative torque T_reg_pot (S13 / Yes), the hydraulic control device 90 starts to increase the brake hydraulic pressure P_whl (step S15). Specifically, the hydraulic brake target torque setting unit 91 of the hydraulic control device 90 sets, as the hydraulic brake target torque T_hyd_tgt, a value obtained by subtracting the regenerative brake torque T_reg from the automatic brake demand torque T_req_in transmitted from the driving support device 110. The control unit 93 of the hydraulic control device 90 controls the drive of the brake hydraulic pressure control unit 30 based on the set hydraulic brake target torque T_hyd_tgt. The control unit 93 closes the circuit control valve 36 of the brake hydraulic pressure control unit 30 and opens the suction valve 34, and drives the pump 44.

[0098] Furthermore, the booster control device 100 offsets the valve body 15 of the electric brake booster 10 toward the master cylinder 5 in advance before the driver depresses the brake pedal 3 in accordance with the increase in the brake hydraulic pressure P_whl (step S17). Specifically, the control unit 101 of the booster control device 100 rotates the electric motor 11 forward in accordance with the rate of increase in the brake hydraulic pressure P_whl transmitted from the brake hydraulic pressure control unit 30, and advances the valve body 15 within a range not exceeding the maximum offset amount d_ofs_max.

[0099] Next, the booster control device 100 determines whether or not the relative displacement amount d_str between the valve body 15 and the plunger 16 has reached the maximum offset amount d_ofs_max (step S19). The booster control device 100 repeats the determination in step S19 until the relative displacement amount d_str between the valve body 15 and the plunger 16 reaches the maximum offset amount d_ofs_max. When the relative displacement amount d_str between the valve body 15 and the plunger 16 reaches the maximum offset amount d_ofs_max (S19 / Yes), the drive of the electric motor 11 is stopped, and the relative displacement amount d_str between the valve body 15 and the plunger 16 is held at the maximum offset amount d_ofs_max (step S21).

[0100] Next, the power booster control device 100 determines whether the brake pedal 3 has been depressed by the driver (step S23). For example, the control unit 101 of the power booster control device 100 determines whether the relative displacement amount d_str detected by the displacement sensor 80 has decreased from the maximum offset amount d_ofs_max. Based on the output of the sensor that detects the depressing force of the brake pedal 3, it may also be determined whether the brake pedal 3 has been depressed by the driver.

[0101] The power booster control device 100 repeats the determination in step S23 until it is determined that the brake pedal 3 has been depressed by the driver. When the brake pedal 3 is depressed (S23 / Yes), the hydraulic control device 90 closes the suction valve 34 of the brake hydraulic control unit 30 and opens the circuit control valve 36, and stops the pump 44. Also, the power booster control device 100 controls the drive of the electric motor 11 so as to maintain the relative displacement amount d_str between the valve body 15 and the plunger 16 at the maximum offset amount d_ofs_max (step S25). As a result, the valve body 15 further moves forward and the master cylinder pressure P_mc increases, and the brake fluid is supplied to the wheel cylinder via the brake hydraulic control unit 30, and the brake hydraulic pressure P_whl increases.

[0102] Next, the hydraulic control device 90 determines whether the regenerative brake torque T_reg has begun to decrease as the vehicle decelerates based on the information on the regenerative brake torque T_reg transmitted from the motor control device 130 (step S27). The hydraulic control device 90 repeats the determination in step S27 until the regenerative brake torque T_reg begins to decrease. When the regenerative brake torque T_reg begins to decrease (S27 / Yes), the circuit control valve 36 is closed and the suction valve 34 is opened, and the pump 44 is driven to increase the brake hydraulic pressure P_whl (step S29). At this time, the hydraulic control device 90 increases the brake hydraulic pressure P_whl so as to compensate for the decrease in the regenerative brake torque T_reg.

[0103] Next, the booster control device 100 determines whether the master cylinder pressure P_mc is lower than the virtual master cylinder pressure P_mc_vrt (step S31). When the master cylinder pressure P_mc is lower than the virtual master cylinder pressure P_mc_vrt (S31 / Yes), the booster control device 100 decreases the relative displacement amount d_str of the valve body 15 that has been advancing toward the master cylinder 5 side (step S33). The booster control device 100 decreases the relative displacement amount d_str of the valve body 15 in accordance with the master cylinder pressure P_mc that decreases due to the drive of the brake hydraulic control unit 30.

[0104] Next, the hydraulic control device 90 determines whether the regenerative brake torque T_reg has become zero (step S35). When the master cylinder pressure P_mc is not lower than the virtual master cylinder pressure P_mc_vrt in step S31 (S31 / No), the process of step S33 is skipped, and it is determined whether the regenerative brake torque T_reg has become zero (step S35).

[0105] When the regenerative brake torque T_reg has not become zero (S35 / No), the process returns to step S29, and the processes from step S29 to step S35 are repeated until the regenerative brake torque T_reg becomes zero. On the other hand, when the regenerative brake torque T_reg has become zero (S35 / Yes), the booster control device 100 stops the reverse rotation drive of the electric motor 11 and controls the drive of the electric motor 11 so as to maintain the relative displacement amount d_str at that time. Thereby, thereafter, the brake hydraulic pressure P_whl is adjusted according to the operation amount of the driver's brake pedal 3.

[0106] As described above, according to the first example of the control process by the vehicle braking control device 150 according to the present embodiment, when replacing the regenerative brake torque T_reg generated during the execution of the automatic brake control of ACC with the hydraulic brake torque T_hyd, the valve body 15 of the electric brake booster 10 that was offset toward the master cylinder 5 side is relatively moved in the backward direction with respect to the plunger 57. As a result, the output torque of the electric motor 11 that moves the valve body 15 backward acts as a reaction force, suppressing a decrease in the driver's pedal feeling due to a decrease in the master cylinder pressure P_mc. Further, since the valve body 15 is moved backward in accordance with the decrease in the master cylinder pressure P_mc, it is possible to prevent a decrease in the unintended driver-requested brake torque. And since the driving of the brake hydraulic control unit 30 does not affect the reaction force of the brake pedal 3 felt by the driver, the brake hydraulic control unit 30 can be driven without estimating the driver-requested brake torque.

[0107] (2-2-3. Second Example according to the Present Embodiment) Next, a second example of the control process of the vehicle braking control device 150 according to the present embodiment will be described. The second example is an example in which the hydraulic brake torque T_hyd is not generated until the driver depresses the brake pedal 3 after the start of execution of the automatic brake control of ACC. In the second example, since the master cylinder pressure P_mc and the virtual master cylinder pressure P_mc_vrt are equal, the control for offsetting the valve body 15 toward the master cylinder 5 side in advance before the driver depresses the brake pedal 3 is not required.

[0108] FIG. 9 is an explanatory diagram showing the operation of the second example, and shows a diagram corresponding to FIG. 7 shown in the first example. At time t51, when the execution of the automatic braking control of the ACC is started, a braking torque T_act corresponding to the automatic braking required torque T_req_in is generated by the regenerative braking torque T_reg. At time t52, when the automatic braking required torque T_req_in becomes constant before the regenerative braking torque T_reg reaches the maximum regenerative torque T_reg_pot, the regenerative braking torque T_reg is held in a constant state. In the second example, in the section a from time t51 to time t53, the braking torque T_act is generated by the regenerative braking torque T_reg.

[0109] At time t53, assuming that the driver depresses the brake pedal 3, in the subsequent section b, the braking torque T_act is generated by the regenerative braking torque T_reg and the brake hydraulic pressure P_whl. Specifically, at time t53, as the plunger 16 advances due to an increase in the operation amount of the brake pedal 3, the electric motor 11 is driven to rotate forward based on the relative displacement amount d_str between the valve body 15 and the plunger 16. As a result, the master cylinder pressure P_mc rises, and the brake fluid is supplied from the master cylinder 5 to the brake hydraulic control unit 30.

[0110] At this time, in this embodiment, since the braking torque T_act is controlled in an add-on manner, the brake fluid supplied from the master cylinder 5 is supplied to the wheel cylinder via the brake hydraulic control unit 30. Also, since the brake hydraulic pressure P_whl has not been generated until time t53, the master cylinder pressure P_mc rises gently without rising rapidly. Therefore, the reaction force of the brake pedal 3 felt by the driver does not become excessive.

[0111] At time t54, when the operation amount of the brake pedal 3 reaches a constant state, the brake fluid pressure P_whl is maintained at a constant value. Thereafter, at time t55, when the regenerative brake torque T_reg begins to decrease as the vehicle decelerates, in order to compensate for the decrease in the regenerative brake torque T_reg with the brake fluid pressure P_whl, the intake valve 34 of the brake fluid pressure control unit 30 is opened and the circuit control valve 36 is closed, and the drive of the pump 44 is started.

[0112] In the section ι after time t55, while the brake fluid pressure P_whl increases, since the increased brake fluid is sucked from the master cylinder 5, the master cylinder pressure P_mc decreases. At this time, also in the second example, the valve body 15 is retracted to the side opposite to the master cylinder 5. Specifically, the electric motor 11 of the electric brake booster 10 is driven to rotate reversely, and the valve body 15 moves relatively backward with respect to the plunger 16. Thereby, it is possible to suppress the reduction of the driver's pedal feeling due to the decrease in the master cylinder pressure P_mc and prevent an unintended decrease in the driver-requested brake torque. And since the drive of the brake fluid pressure control unit 30 does not affect the reaction force of the brake pedal 3 felt by the driver, it is not necessary to estimate the driver-requested brake torque.

[0113] Thereafter, at time t56, when the regenerative brake torque T_reg becomes zero, in the subsequent section c, the pump 44 is stopped again, and the brake fluid pressure P_whl is maintained in a constant state. In section c, the brake torque T_act is generated by the brake fluid pressure P_whl. Note that in section c, the drive of the electric motor 11 is controlled according to the operation of the driver's brake pedal 3 so that the relative displacement amount d_str between the valve body 15 and the plunger 16 at time t56 is maintained, and the brake fluid pressure P_whl is adjusted.

[0114] FIG. 10 shows a flowchart of a second example of the control process by the vehicle braking control device 150. First, when the automatic braking function of the ACC becomes active, the motor control device 130 regeneratively drives the drive motor 121 and starts to increase the regenerative braking torque T_reg (step S11). Specifically, when the regenerative braking target torque setting unit 131 of the motor control device 130 receives a braking request signal S_brk by ACC control from the driving assistance device 110, it sets the automatic braking request torque T_req_in as the regenerative braking target torque T_reg_tgt. The control unit 133 of the motor control device 130 controls the drive of the inverter 123 based on the set regenerative braking target torque T_reg_tgt to generate the regenerative braking torque T_reg.

[0115] Next, the motor control device 130 determines whether the regenerative braking torque T_reg has reached the maximum regenerative torque T_reg_pot (step S12). If the regenerative braking torque T_reg is less than the maximum regenerative torque T_reg_pot (S12 / No), it returns to step S11 and repeats the determination in step S12 until the regenerative braking torque T_reg reaches the maximum regenerative torque T_reg_pot. On the other hand, when the regenerative braking torque T_reg reaches the maximum regenerative torque T_reg_pot (S12 / Yes), the motor control device 130 maintains the regenerative braking torque T_reg at the maximum regenerative torque T_reg_pot (step S14).

[0116] Next, the booster control device 100 determines whether the brake pedal 3 has been depressed by the driver (step S23). For example, the control unit 101 of the booster control device 100 determines whether the relative displacement amount d_str detected by the displacement sensor 80 has decreased from the maximum offset amount d_ofs_max. Based on the output of the sensor that detects the stepping force of the brake pedal 3, it may also be determined whether the brake pedal 3 has been depressed by the driver.

[0117] The booster control device 100 repeats the determination in step S23 until it is determined by the driver that the brake pedal 3 has been depressed. When the brake pedal 3 is depressed (S23 / Yes), the booster control device 100 controls the drive of the electric motor 11 so as to maintain the relative displacement amount d_str between the valve body 15 and the plunger 16 at the reference value d_str_0 (step S24). As a result, the valve body 15 moves forward and the master cylinder pressure P_mc increases, and the brake fluid is supplied to the wheel cylinder via the brake fluid pressure control unit 30, and the brake fluid pressure P_whl increases.

[0118] Next, the hydraulic control device 90 determines whether or not the regenerative brake torque T_reg has begun to decrease as the vehicle decelerates, based on the information of the regenerative brake torque T_reg transmitted from the motor control device 130 (step S27). The hydraulic control device 90 repeats the determination in step S27 until the regenerative brake torque T_reg begins to decrease. When the regenerative brake torque T_reg begins to decrease (S27 / Yes), the circuit control valve 36 is closed and the intake valve 34 is opened, and the pump 44 is driven to increase the brake fluid pressure P_whl (step S29). At this time, the hydraulic control device 90 increases the brake fluid pressure P_whl so as to compensate for the decrease in the regenerative brake torque T_reg.

[0119] Next, the booster control device 100 drives the electric motor 11 in reverse rotation to relatively move the valve body 15 backward with respect to the plunger 16 (step S32). At this time, the booster control device 100 moves the valve body 15 backward in accordance with the master cylinder pressure P_mc that decreases due to the drive of the brake fluid pressure control unit 30.

[0120] Next, the hydraulic control device 90 determines whether or not the regenerative brake torque T_reg has become zero (step S35). If the regenerative brake torque T_reg has not become zero (S35 / No), the process returns to step S29, and the processes from step S29 to step S35 are repeated until the regenerative brake torque T_reg becomes zero. On the other hand, if the regenerative brake torque T_reg has become zero (S35 / Yes), the booster device control device 100 stops the reverse rotation drive of the electric motor 11, and thereafter controls the drive of the electric motor 11 so as to maintain the relative displacement amount d_str at that time. Thereby, in the section c after the time t66, the brake hydraulic pressure P_whl is adjusted according to the operation amount of the driver's brake pedal 3.

[0121] As described above, according to the second example of the control process by the braking control device 150 of the vehicle according to the present embodiment, when replacing the regenerative brake torque T_reg generated during the execution of the automatic braking control of the ACC with the hydraulic brake torque T_hyd, the valve body 15 of the electric brake booster 10 is relatively moved in the backward direction with respect to the plunger 57. Thereby, the output torque of the electric motor 11 that moves the valve body 15 backward serves as a reaction force, and it is suppressed that the driver's pedal feeling becomes lighter due to the decrease in the master cylinder pressure P_mc. Further, since the valve body 15 is moved backward in accordance with the decrease in the master cylinder pressure P_mc, it is possible to prevent an unintended decrease in the driver-requested brake torque. And since the drive of the brake hydraulic control unit 30 does not affect the reaction force of the brake pedal 3 felt by the driver, the brake hydraulic control unit 30 can be driven without estimating the driver-requested brake torque.

[0122] <3. Effects> As described above, according to the braking control device 150 for a vehicle according to the present embodiment, when increasing the hydraulic brake torque T_hyd as the generated regenerative brake torque T_reg decreases during the execution of the automatic brake control of ACC, the valve body 15 of the electric brake booster 10 is relatively moved in the retreat direction with respect to the plunger 57. Thereby, the output torque of the electric motor 11 that moves the valve body 15 in the retreat direction acts as a reaction force, and it is suppressed that the pedal feeling of the driver becomes lighter due to the decrease in the master cylinder pressure P_mc. Further, since the valve body 15 is moved in the retreat direction in accordance with the decrease in the master cylinder pressure P_mc, it is possible to prevent a decrease in the unintended driver-requested brake torque. Therefore, it is possible to suppress an increase or decrease in the deceleration unintended by the driver.

[0123] Further, in the braking control device 150 for a vehicle according to the present embodiment, since the drive of the brake hydraulic control unit 30 when replacing the regenerative brake torque T_reg with the hydraulic brake torque T_hyd does not affect the reaction force of the brake pedal 3 felt by the driver, the brake hydraulic control unit 30 can be driven without estimating the driver-requested brake torque.

[0124] Further, in the braking control device 150 for a vehicle according to the present embodiment, when the driver depresses the brake pedal 3 during the execution of the automatic brake control of ACC, the additional brake torque T_act is generated in an add-on manner. Therefore, the brake torque T_act increases as the driver depresses the brake pedal 3, and it is possible to suppress the discomfort felt by the driver.

[0125] Further, according to the braking control device 150 for a vehicle according to the present embodiment, during the execution of the automatic brake control of ACC, the regenerative brake torque T_reg can be utilized to the maximum extent, and a decrease in the regenerative efficiency can be prevented.

[0126] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present invention pertains can conceive various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present invention.

[0127] For example, the above embodiment was a braking control device applicable to an electric vehicle or a hybrid electric vehicle equipped with a driving motor as a driving source of the vehicle, but the present invention is not limited to such an example. Also in a vehicle such as an engine vehicle that cannot generate a regenerative braking torque, by controlling the driving of the electric brake booster 10 and the brake hydraulic control unit 30 according to the above second example, the same effects as the above embodiment can be obtained.

Explanation of Reference Numerals

[0128] 1... Hydraulic brake system, 3... Brake pedal, 5... Master cylinder, 6... Primary piston, 7... Secondary piston, 10... Electric brake booster, 11... Electric motor, 15... Valve body, 30... Brake hydraulic control unit, 90... Hydraulic control device, 100... Multiplier device control device, 121... Driving motor, 130... Motor control device, 150... Braking control device

Claims

1. An electric brake booster (10) that doubles the stepping force of the brake pedal (3) by a driver by advancing a valve body (15) by driving an electric motor (11) to advance pistons (6, 7) of a master cylinder (5) and pressurize the brake fluid in the master cylinder (5); A brake hydraulic pressure control unit (30) that adjusts the brake hydraulic pressure (P_whl) generated in each wheel; A control unit (90, 100) that controls a hydraulic brake system (1); In a vehicle braking control device (150), while receiving a braking request signal (S_brk) by an automatic braking function, the control unit (90, 100) sets an automatic braking request torque (T_req_in) to a target braking torque (T_tgt), and when the driver depresses the brake pedal (3) while receiving the braking request signal (S_brk) by the automatic braking function, the control unit (90, 100) sets the sum of the automatic braking request torque (T_req_in) and the driver request braking torque (T_dri) to the target braking torque (T_tgt) and executes braking control. While receiving a braking request signal (S_brk) by the automatic braking function, when the driver depresses the brake pedal (3) and the regenerative braking torque (T_reg) and the brake hydraulic pressure (P_whl) are generated, and when the regenerative braking torque (T_reg) decreases, the control unit (90, 100) drives the brake hydraulic pressure control unit (30) to increase the brake hydraulic pressure (P_whl) and retract the valve body (15) of the electric brake booster (10). A vehicle braking control device characterized by the above.

2. The control unit (90, 100, 130) retracts the valve body (15) in accordance with a decrease in the pressure (P_mc) in the master cylinder (5). Let it retract. The vehicle braking control device according to Claim 1.

3. While the control units (90, 100, 130) are receiving the braking request signal (S_brk) by the automatic braking function, when the driver depresses the brake pedal (3), the driving of the brake hydraulic pressure control unit (30) is stopped, The braking control device for a vehicle according to claim 2, characterized in that.

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