JP2022065211A - Brake system, brake control device, brake control method and brake control program - Google Patents

Abstract

To provide a brake system, a brake control device, a brake control method and a brake control program which can suppress the excess or shortage of thrust following the change in a vehicle state (for example, the variation in the liquid pressure) in application (namely, in holding of the brake force based on the drive of an electric motor).SOLUTION: A parking brake control device 24 temporarily stops the power supply to an electric motor 7A and then resumes the power supply to the electric motor 7A if necessary after the elapse of the temporary stop time. The parking brake control device 24 completes holding (application) of the brake force when a holding completion condition for completing holding of the brake force is established. In this case, the parking brake control device 24 determines the holding completion condition based on the change in the vehicle state when the power supply is temporarily stopped. The holding completion condition is determined with the change in the liquid pressure given to a piston 6D as the vehicle state.SELECTED DRAWING: Figure 2

Description

The present invention relates to a brake system, a brake control device, a brake control method, and a brake control program for applying a braking force to a vehicle such as an automobile.

Vehicles such as automobiles are equipped with a brake system that applies braking force to the vehicle by supplying hydraulic pressure (brake fluid pressure) toward the hydraulic brake (hydraulic braking device) on each wheel side. .. Here, in the case of a disc brake, for example, the hydraulic brake presses the brake pad (braking member) against the disc rotor (braked member) via the piston by supplying hydraulic pressure from the outside into the cylinder of the caliper. To generate braking force.

As such a disc brake, for example, not only a braking force is generated based on the hydraulic pressure when the vehicle is running, but also the electric motor (motor) is driven (rotated) when the vehicle is stopped, parked, or, if necessary, running. A hydraulic disc brake with an electric parking brake function that generates a braking force based on the above is known (Patent Document 1).

JP-A-2015-47945 (Patent No. 6227333)

In the case of the prior art, when the parking brake is applied (braking is applied), there is a possibility that the thrust based on the drive of the electric motor becomes excessive (excessive) due to the change in the vehicle state (for example, the fluctuation of the hydraulic pressure). be.

It is an object of the present invention that the thrust is excessive or insufficient due to a change in the vehicle state (for example, a fluctuation in hydraulic pressure) when applying (that is, when the braking force is maintained based on the drive of an electric motor). It is an object of the present invention to provide a brake system, a brake control device, a brake control method, and a brake control program capable of suppressing the pressure.

The present invention is a hydraulic braking device that propels a piston by hydraulic pressure to press a braking member against a braked member, and a hydraulic braking device that propels the piston by a thrust transmitted from an electric motor and presses the braking member against the braked member. The electric braking device that holds the braking force and the power supply to the motor after temporarily stopping the power supply to the motor in the section where the thrust is generated in the piston when the braking force is held. The control device comprises a control device that completes the holding of the braking force when the holding completion condition is satisfied, and the control device is provided with the control device when the power supply is temporarily stopped. In addition, the holding completion condition is determined based on the change in the vehicle state.

Further, the present invention is a brake control device having a control unit for controlling the motor in a brake mechanism in which a piston is propelled by a thrust or hydraulic pressure transmitted from the motor to press the braking member against the braked member. The control unit drives the electric motor in response to a control command for holding the braking force of the brake mechanism, and temporarily stops the power supply to the electric motor when the current in which the thrust is generated in the piston rises. After that, the power supply to the motor is restarted, the holding of the braking force is completed when the holding completion condition for completing the holding of the braking force is satisfied, and the power supply to the motor is temporarily stopped. At that time, the holding completion condition is determined based on the change in the vehicle state.

Further, the present invention is a brake control method for controlling the motor in a brake mechanism in which a piston is propelled by a thrust or hydraulic pressure transmitted from the motor to press the braking member against the braked member, and the control of the brake mechanism is controlled. A step of starting the current supply to the motor according to a control command for holding the power, and a step of temporarily stopping the power supply to the motor when the current rises when a thrust is generated in the piston. After temporarily stopping the power supply to the motor, the step of restarting the power supply to the motor and the holding completion condition for completing the holding of the braking force are satisfied, the holding of the braking force is completed. It includes a step and a step of setting the holding completion condition based on a change in the vehicle state when the power supply to the electric motor is temporarily stopped.

Further, the present invention is a brake control program to be executed by a brake control device that controls the motor in a brake mechanism that propels a piston by thrust or hydraulic pressure transmitted from the motor to press the braking member against the braked member. , The step of starting the current supply to the motor according to the control command for holding the braking force of the brake mechanism, and the power supply to the motor temporarily when the current rises when the thrust is generated in the piston. The step is controlled when the step of temporarily stopping the power supply to the motor, the step of restarting the power supply to the motor, and the holding completion condition for completing the holding of the braking force are satisfied. The step of completing the holding of the power and the step of setting the holding completion condition based on the change in the vehicle state when the power supply to the motor is temporarily stopped are executed.

According to the present invention, when the braking force is maintained based on the drive of the motor (when applied), it is possible to prevent the thrust from being excessive or insufficient due to a change in the vehicle state (for example, a fluctuation in hydraulic pressure). ..

The conceptual diagram of the vehicle equipped with the brake system according to 1st Embodiment. FIG. 1 is an enlarged vertical sectional view showing a disc brake with an electric parking brake function provided on the rear wheel side in FIG. 1. The block diagram which shows the parking brake control device in FIG. 1 together with the rear wheel side disc brake and the like. The flow chart which shows the control process by the parking brake control device in FIG. The flow chart which shows the process following "A" and "B" in FIG. The flow chart which shows "ΔP determination process" of S9 in FIG. FIG. 6 is a characteristic diagram showing an example of the relationship between the hydraulic pressure P and the apply pause current threshold value I _pause . The characteristic diagram which shows an example of the relationship between the change amount ΔP of a hydraulic pressure, and the _re -energization time tre. The characteristic diagram which shows an example of the time change of a motor current I and a hydraulic pressure P by 1st Embodiment. The flow chart which shows the control process (the process which follows "A", "B" in FIG. 4) by the 2nd Embodiment. The flow chart which shows "ΔP determination process" of S21 in FIG. The characteristic diagram which shows an example of the time change of the motor current I and the hydraulic pressure P by the 2nd Embodiment. An explanatory diagram (characteristic diagram of time change) showing a hydraulic pressure error due to a delay in the control recognition value with respect to the caliper hydraulic pressure true value.

Hereinafter, a case where the brake system and the brake control device according to the embodiment are mounted on a four-wheeled vehicle will be described as an example, and will be described with reference to the accompanying drawings. In addition, each step of the flow chart shown in FIG. 4, FIG. 5, FIG. 6, FIG. 10, and FIG. 11 uses the notation “S” (for example, step 1 = “S1”).

1 to 9 show a first embodiment. In FIG. 1, on the lower side (road surface side) of the vehicle body 1 constituting the body of the vehicle, for example, a total of four wheels including left and right front wheels 2 (FL, FR) and left and right rear wheels 3 (RL, RR). Wheels are provided. The wheels (each front wheel 2 and each rear wheel 3) constitute a vehicle together with the vehicle body 1. The vehicle is equipped with a braking system for applying braking force. Hereinafter, the vehicle braking system will be described.

The front wheels 2 and the rear wheels 3 are provided with a disc rotor 4 as a braked member (rotating member) that rotates together with the respective wheels (each front wheel 2 and each rear wheel 3). A braking force is applied to the disc rotor 4 for the front wheel 2 by the front wheel side disc brake 5, which is a hydraulic disc brake. The disc rotor 4 for the rear wheel 3 is provided with braking force by the rear wheel side disc brake 6, which is a hydraulic disc brake with an electric parking brake function.

A pair (one set) of rear wheel side disc brakes 6 provided corresponding to the left and right rear wheels 3 presses the brake pads 6C (see FIG. 2) against the disc rotor 4 by hydraulic pressure to apply braking force. It is a hydraulic brake mechanism. As shown in FIG. 2, the rear wheel side disc brake 6 includes, for example, a mounting member 6A called a carrier, a caliper 6B as a wheel cylinder, and a pair of brake pads 6C as a braking member (friction member, friction pad). , A piston 6D as a pressing member is provided. In this case, the caliper 6B and the piston 6D form a cylinder mechanism (hydraulic braking device) that propels the piston 6D by hydraulic pressure and presses the brake pad 6C against the disc rotor 4.

The mounting member 6A is fixed to the non-rotating portion of the vehicle and is formed so as to straddle the outer peripheral side of the disc rotor 4. The caliper 6B is provided on the mounting member 6A so that the disc rotor 4 can move in the axial direction. The caliper 6B includes a cylinder main body portion 6B1, a claw portion 6B2, and a bridge portion 6B3 connecting them. A cylinder (cylinder hole) 6B4 is provided in the cylinder body 6B1, and a piston 6D is inserted in the cylinder 6B4. The brake pad 6C is movably attached to the attachment member 6A and is arranged so as to be in contact with the disc rotor 4. The piston 6D presses the brake pad 6C against the disc rotor 4.

Here, the caliper 6B propels the brake pad 6C with the piston 6D by supplying (adding) the hydraulic pressure (brake hydraulic pressure) into the cylinder 6B4 based on the operation of the brake pedal 9 or the like. At this time, the brake pad 6C is pressed against both sides of the disc rotor 4 by the claw portion 6B2 of the caliper 6B and the piston 6D. As a result, braking force is applied to the rear wheels 3 that rotate together with the disc rotor 4.

Further, the rear wheel side disc brake 6 includes an electric actuator 7 and a rotary linear motion mechanism 8. The electric actuator 7 includes an electric motor 7A as an electric motor, a speed reducer (not shown) for decelerating the rotation of the electric motor 7A, and the like. The electric motor 7A serves as a propulsion source (drive source) for propelling the piston 6D. The rotary linear motion mechanism 8 constitutes a holding mechanism (pressing member holding mechanism) for holding the pressing force of the brake pad 6C.

In this case, the rotary linear motion mechanism 8 is configured to include a rotary linear motion member 8A that converts the rotation of the electric motor 7A into an axial displacement (linear displacement) of the piston 6D and propels the piston 6D. .. The rotary linear motion member 8A is composed of, for example, a screw member 8A1 made of a rod-shaped body on which a male screw is formed, and a linear motion member 8A2 which is a propulsion member having a female screw hole formed on the inner peripheral side. The rotary linear motion mechanism 8 converts the rotation of the electric motor 7A into an axial displacement of the piston 6D, and holds the piston 6D propelled by the electric motor 7A. That is, the rotary linear motion mechanism 8 applies thrust to the piston 6D by the electric motor 7A, propels the brake pad 6C by the piston 6D to press the disc rotor 4, and holds the thrust of the piston 6D.

As described above, the rear wheel side disc brake 6 includes a rotary linear motion mechanism 8 and an electric motor 7A. The rotary linear motion mechanism 8 and the electric motor 7A constitute an electric brake mechanism (electric brake device). The electric brake mechanism converts the rotational force of the electric motor 7A into thrust via the speed reducer and the rotary linear motion mechanism 8, and applies thrust to the piston 6D that presses the brake pad 6C to hold or release the braking force. do. That is, in the electric brake mechanism, the piston 6D propelled by the rotary linear motion mechanism 8 driven by the electric motor 7A presses the brake pad 6C against the disc rotor 4, and the brake pad 6C is pressed by the stop of the electric motor 7A. Hold at.

The rotary linear motion mechanism 8 and the electric motor 7A constituting the electric brake mechanism (electric brake device) are braked together with the caliper 6B and the piston 6D constituting the cylinder mechanism (hydraulic braking device) and the parking brake control device 24 described later. The system is configured. The electric brake mechanism (electric brake device) propels the piston 6D by the thrust transmitted from the electric motor 7A to press the brake pad 6C against the disc rotor 4 and hold the braking force.

The rear wheel side disc brake 6 propels the piston 6D by the brake fluid pressure generated based on the operation of the brake pedal 9, and presses the disc rotor 4 with the brake pad 6C to extend the wheels (rear wheel 3). Gives braking force to the vehicle. In addition to this, as will be described later, the rear wheel side disc brake 6 propels the piston 6D via the rotary linear motion mechanism 8 by the electric motor 7A in response to an operation request based on a signal or the like from the parking brake switch 23. And apply braking force (parking brake, auxiliary brake if necessary) to the vehicle.

That is, the rear wheel side disc brake 6 drives the electric motor 7A and propels the piston 6D by the rotary linear motion member 8A to press and hold the brake pad 6C against the disc rotor 4. In this case, the rear wheel side disc brake 6 propels the piston 6D with the electric motor 7A in response to the parking brake request signal (apply request signal), which is an apply request for applying the parking brake (parking brake), to the vehicle. It is possible to maintain the braking of. At the same time, the rear wheel side disc brake 6 brakes the vehicle by supplying hydraulic pressure from a hydraulic pressure source (master cylinder 12, which will be described later, and if necessary, a hydraulic pressure supply device 16) in response to the operation of the brake pedal 9. It is possible.

As described above, the rear wheel side disc brake 6 has a rotary linear motion mechanism 8 that presses the brake pad 6C against the disc rotor 4 by the electric motor 7A and holds the pressing force of the brake pad 6C, and also has the electric motor 7A. The brake pad 6C can be pressed against the disc rotor 4 by the hydraulic pressure applied separately from the pressing by.

On the other hand, the pair (one set) of front wheel side disc brakes 5 provided corresponding to the left and right front wheels 2 have almost the same configuration as the rear wheel side disc brakes 6 except for the mechanism related to the operation of the parking brake. Has been done. That is, as shown in FIG. 1, the front wheel side disc brake 5 includes a mounting member (not shown), a caliper 5A, a brake pad (not shown), a piston 5B, and the like, but the parking brake is activated and released. The electric actuator 7 (electric motor 7A), the rotary linear motion mechanism 8, and the like are not provided. However, the front wheel side disc brake 5 propels the piston 5B by the hydraulic pressure generated based on the operation of the brake pedal 9, and applies braking force to the wheels (front wheel 2) and the vehicle. It is the same as the disc brake 6. That is, the front wheel side disc brake 5 is a hydraulic brake mechanism (hydraulic brake) that presses the brake pad against the disc rotor 4 by hydraulic pressure to apply braking force.

The front wheel side disc brake 5 may be a disc brake with an electric parking brake function, similarly to the rear wheel side disc brake 6. Further, in the embodiment, a hydraulic disc brake 6 provided with an electric parking mechanism is used as the electric parking brake device. However, the electric parking brake device is not limited to this, for example, a hydraulic drum brake equipped with an electric parking mechanism, a hydraulic disc brake equipped with an electric drum parking mechanism, and an electric motor to pull a cable. A hydraulic disc brake or a drum brake provided with a cable puller type electric parking mechanism for applying the parking brake may be used. That is, the electric parking brake device presses (propulses) the friction member (pad, shoe) against the rotating member (rotor, drum) based on the drive of the electric motor (electric actuator), and holds and releases the pressing force. Various electric parking brake devices can be used as long as the configuration is provided with an electric parking mechanism that can be used.

A brake pedal 9 is provided on the front board side of the vehicle body 1. The brake pedal 9 is stepped on by the driver when the vehicle is braked. The disc brakes 5 and 6 are applied and released with braking force as a normal brake (service brake) based on the operation of the brake pedal 9. The brake pedal 9 is provided with a brake operation detection sensor (brake sensor) 10 such as a brake lamp switch, a pedal switch (brake switch), and a pedal stroke sensor.

The brake operation detection sensor 10 detects whether or not the brake pedal 9 is depressed or the amount of operation thereof, and outputs the detection signal to the ESC control device 17. The detection signal of the brake operation detection sensor 10 is transmitted, for example, via the vehicle data bus 20 or a communication line (not shown) connecting the ESC control device 17 and the parking brake control device 24 (parking brake control). Output to device 24).

The stepping operation of the brake pedal 9 is transmitted to the master cylinder 12 that functions as a hydraulic pressure source (hydraulic pressure source) via the booster 11. The booster 11 is configured as a negative pressure booster (pressure booster) or an electric booster (electric booster) provided between the brake pedal 9 and the master cylinder 12. The booster 11 increases the pedaling force and transmits it to the master cylinder 12 when the brake pedal 9 is depressed.

At this time, the master cylinder 12 generates hydraulic pressure by the brake fluid supplied (replenished) from the master reservoir 13. The master reservoir 13 serves as a hydraulic fluid tank in which the brake fluid is stored. The mechanism for generating the hydraulic pressure by the brake pedal 9 is not limited to the above configuration, and may be a mechanism for generating the hydraulic pressure in response to the operation of the brake pedal 9, for example, a brake-by-wire type mechanism. ..

The hydraulic pressure generated in the master cylinder 12 is sent to the hydraulic pressure supply device 16 (hereinafter referred to as ESC 16) via, for example, a pair of cylinder-side hydraulic pressure pipes 14A and 14B. The ESC 16 is arranged between the disc brakes 5 and 6 and the master cylinder 12. The ESC 16 supplies the hydraulic pressure output from the master cylinder 12 via the cylinder-side hydraulic pipes 14A and 14B to the disc brakes 5 and 6 via the brake-side piping portions 15A, 15B, 15C and 15D. That is, the ESC 16 applies the hydraulic pressure (brake hydraulic pressure) corresponding to the operation of the brake pedal 9 to the disc brakes 5, 6 (calipers 5A, 6B) provided on each wheel (front wheel 2, each rear wheel 3). It is what we supply. As a result, braking force can be applied to each of the wheels (each front wheel 2 and each rear wheel 3) independently of each other.

Here, the ESC 16 is a hydraulic pressure control device that controls the hydraulic pressure of the hydraulic pressure brakes (front wheel side disc brake 5, rear wheel side disc brake 6). To this end, the ESC 16 includes a plurality of control valves, a hydraulic pump that pressurizes the brake fluid pressure, an electric motor that drives the hydraulic pump, and a hydraulic pressure control reservoir that temporarily stores excess brake fluid. (Neither is shown) and is included. Each control valve and the electric motor of the ESC 16 are connected to the ESC control device 17, and the ESC 16 is configured to include the ESC control device 17.

The opening and closing of each control valve of the ESC 16 and the drive of the electric motor are controlled by the ESC control device 17. That is, the ESC control device 17 is an ESC control unit (ESC ECU) that controls the ESC 16. The ESC control device 17 includes a microcomputer and electrically drives and controls the ESC 16 (solenoid of each control valve, electric motor). In this case, the ESC control device 17 is, for example, an arithmetic circuit for controlling the hydraulic pressure supply of the ESC 16 and detecting a failure of the ESC 16, an electric motor, a drive circuit for driving each control valve (none of which is shown), and the like. Is built-in.

The ESC control device 17 individually drives and controls each control valve (solenoid) of the ESC 16 and the electric motor for the hydraulic pump. As a result, the ESC control device 17 controls to reduce the pressure, hold, increase the pressure, or pressurize the brake fluid pressure (wheel cylinder fluid pressure) supplied to the disc brakes 5 and 6 through the brake side piping portions 15A-15D. Perform individually for each disc brake 5 and 6.

In this case, the ESC control device 17 can execute the following controls (1)-(8), for example, by controlling the operation of the ESC 16.
(1) Braking force distribution control that appropriately distributes the braking force to each of the wheels 2 and 3 according to the ground contact load and the like when the vehicle is braked.
(2) Anti-lock brake control (hydraulic ABS control) that automatically adjusts the braking force of each wheel 2 and 3 during braking to prevent locking (slip) of each wheel 2 and 3.
(3) Understeer and oversteer are performed while detecting skidding of each wheel 2 and 3 during running and automatically controlling the braking force applied to each wheel 2 and 3 regardless of the operation amount of the brake pedal 9. Vehicle stabilization control that suppresses and stabilizes the behavior of the vehicle.
(4) Hill-start assist control that assists the start by maintaining the braking state on a slope (especially uphill).
(5) Traction control to prevent the wheels 2 and 3 from slipping when starting.
(6) Vehicle follow-up control that maintains a constant distance from the preceding vehicle.
(7) Lane deviation avoidance control that keeps the driving lane.
(8) Obstacle avoidance control (automatic brake control, collision damage mitigation brake control) that avoids collision with obstacles in the vehicle traveling direction.

The ESC 16 directly supplies the hydraulic pressure generated in the master cylinder 12 to the disc brakes 5 and 6 (calipers 5A and 6B) during normal operation by the driver's brake operation. On the other hand, for example, when executing anti-lock brake control or the like, the pressure boosting control valve is closed to maintain the hydraulic pressure of the disc brakes 5 and 6, and when the hydraulic pressure of the disc brakes 5 and 6 is reduced. The pressure reducing control valve is opened and the hydraulic pressure of the disc brakes 5 and 6 is discharged so as to escape to the hydraulic pressure control reservoir.

Furthermore, in order to perform stabilization control (side slip prevention control) when the vehicle is running, when increasing or pressurizing the hydraulic pressure supplied to the disc brakes 5 and 6, the electric power is applied with the supply control valve closed. The hydraulic pump is operated by a motor, and the brake fluid discharged from the hydraulic pump is supplied to the disc brakes 5 and 6. At this time, the brake fluid in the master reservoir 13 is supplied from the master cylinder 12 side to the suction side of the hydraulic pump.

The ESC control device 17 is supplied with electric power from a battery 18 (or a generator driven by an engine), which is a vehicle power source, through a power supply line 19. As shown in FIG. 1, the ESC control device 17 is connected to the vehicle data bus 20. It is also possible to use a known ABS unit instead of the ESC 16. Further, it is also possible to directly connect the master cylinder 12 and the brake side piping portion 15A-15D without providing the ESC 16 (that is, omitting it).

The vehicle data bus 20 constitutes a CAN (Controller Area Network) as a serial communication unit mounted on the vehicle body 1. A large number of electronic devices mounted on the vehicle (for example, various ECUs including the ESC control device 17, the parking brake control device 24, and the like) perform multiplex communication in the vehicle between them by the vehicle data bus 20. In this case, the vehicle information sent to the vehicle data bus 20 includes, for example, a brake operation detection sensor 10, an ignition switch, a seat belt sensor, a door lock sensor, a door open sensor, a seating sensor, a vehicle speed sensor, a steering angle sensor, and an accelerator sensor. (Accelerator operation sensor), Throttle sensor, Engine rotation sensor, Stereo camera, Millimeter wave radar, Gradient sensor (Inclination sensor), Shift sensor (Transmission data), Acceleration sensor (G sensor), Wheel speed sensor, Vehicle pitch direction Information (vehicle information) based on a detection signal (output signal) from a pitch sensor or the like that detects motion can be mentioned.

Further, as the vehicle information sent to the vehicle data bus 20, the W / C pressure sensor 21 for detecting the wheel cylinder hydraulic pressure (W / C hydraulic pressure) and the M for detecting the master cylinder hydraulic pressure (M / C hydraulic pressure). The detection signal (information) from the / C pressure sensor 22 can also be mentioned. The W / C pressure sensor 21 and the M / C pressure sensor 22 are connected to the ESC control device 17, for example, like the brake operation detection sensor 10. The detection signals of the W / C pressure sensor 21 and the M / C pressure sensor 22 are sent from the ESC control device 17 to the vehicle data bus 20 as information on the W / C hydraulic pressure and the M / C hydraulic pressure. A large number of electronic devices (various ECUs) mounted on the vehicle can obtain various vehicle information including W / C hydraulic pressure and M / C hydraulic pressure through the vehicle data bus 20. The W / C pressure sensor 21 and / or the M / C pressure sensor 22 may be directly connected to the parking brake control device 24.

Next, the parking brake switch 23 and the parking brake control device 24 will be described.

A parking brake switch (PKB-SW) 23 as a switch for the electric parking brake is provided in the vehicle body 1 at a position near the driver's seat (not shown). The parking brake switch 23 is an operation instruction unit operated by the driver. The parking brake switch 23 sends a signal (operation request signal) corresponding to a parking brake operation request (a supply request as a holding request, a release request as a release request) in response to a driver's operation instruction to the parking brake control device 24. Communicate to. That is, the parking brake switch 23 is an operation request signal (holding request) for causing the piston 6D and the brake pad 6C to be applied (held) or released (released) based on the drive (rotation) of the electric motor 7A. An apply request signal as a signal and a release request signal as a release request signal) are output to the parking brake control device 24. The parking brake control device 24 is a parking brake control unit (parking brake ECU).

When the parking brake switch 23 is operated by the driver to the braking side (apply side), that is, when there is an apply request (braking holding request) for applying a braking force to the vehicle, the parking brake switch 23 applies. A request signal (parking brake request signal, apply command) is output. In this case, power for rotating the electric motor 7A to the braking side is supplied to the electric motor 7A of the rear wheel side disc brake 6 via the parking brake control device 24. At this time, the rotary linear motion mechanism 8 propels (presses) the piston 6D toward the disc rotor 4 based on the rotation of the electric motor 7A, and holds the propelled piston 6D. As a result, the rear wheel side disc brake 6 is in a state in which braking force as a parking brake (or auxiliary brake) is applied, that is, in an apply state (braking holding state).

On the other hand, when the parking brake switch 23 is operated by the driver to the braking release side (release side), that is, when there is a release request (braking release request) for releasing the braking force of the vehicle, the parking brake switch A release request signal (parking brake release request signal, release command) is output from 23. In this case, power for rotating the electric motor 7A in the direction opposite to the braking side is supplied to the electric motor 7A of the rear wheel side disc brake 6 via the parking brake control device 24. At this time, the rotary linear motion mechanism 8 releases the holding of the piston 6D by the rotation of the electric motor 7A (releases the pressing force by the piston 6D). As a result, the rear wheel side disc brake 6 is in a state in which the braking force applied as the parking brake (or auxiliary brake) is released, that is, in a released state (braking release state).

The parking brake is, for example, when the vehicle is stopped for a predetermined time (for example, it is determined that the parking brake is stopped when the detection speed of the vehicle speed sensor is less than 5 km / h for a predetermined time due to deceleration while driving). When the shift lever is operated to P (parking), when the door is opened, when the seatbelt is released, etc., the parking brake control device 24 automatically requests the apply by the parking brake apply determination logic. Based on this, it can be automatically given (auto-applied). Further, the parking brake is, for example, when the vehicle is running (for example, it is determined that the parking brake is running when the detection speed of the vehicle speed sensor continues for a predetermined time with the speed increased from the stop). When operated, when the clutch pedal is operated, when the shift lever is operated other than P and N, etc., based on the automatic release request by the parking brake release determination logic in the parking brake control device 24, etc. It can be automatically released (auto-released). The auto apply and auto release can be configured as a switch failure auxiliary function that automatically applies or releases the braking force when the parking brake switch 23 fails.

Further, when the parking brake switch 23 is operated while the vehicle is running, more specifically, there is a demand for a dynamic parking brake (dynamic apply) such as urgently using the parking brake as an auxiliary brake while the vehicle is running. If so, for example, the braking force can be applied and released by the ESC 16 according to the operation of the parking brake switch 23. In this case, for example, the parking brake control device 24 issues a braking command (for example, a hydraulic pressure request signal, a target hydraulic pressure signal) corresponding to the operation of the parking brake switch 23 via the vehicle data bus 20 or the communication line. , Is output to the ESC control device 17. As a result, the ESC 16 applies the braking force due to the hydraulic pressure while the parking brake switch 23 is operated to the braking side (while the operation to the braking side continues) based on the braking command from the parking brake control device 24. When the operation is completed, the braking force due to the hydraulic pressure is released.

On the other hand, when the parking brake switch 23 is operated while the vehicle is running, instead of applying and releasing the braking force by the ESC 16, for example, the braking force is applied by driving the electric motor 7A of the rear wheel side disc brake 6. It can be canceled. In this case, for example, the parking brake control device 24 applies a braking force while the parking brake switch 23 is being operated on the braking side (while the operation on the braking side is continuing), and when the operation is completed. Release the braking force. At this time, the parking brake control device 24 automatically applies and releases the braking force (ABS control) according to the state of the wheels (each rear wheel 3), that is, whether or not the wheels lock (slip). It can be configured to be performed.

The parking brake control device 24 as a control device (brake control device) constitutes a brake system together with a rear wheel side disc brake 6 (hydraulic brake device, electric brake device). The parking brake control device 24 controls the drive of the electric motor 7A. That is, the parking brake control device 24 has a control unit that controls the drive of the electric motor 7A in the rear wheel side disc brake 6. For this purpose, as shown in FIG. 3, the parking brake control device 24 has an arithmetic circuit (CPU) 25 and a memory 26 configured by a microcomputer or the like. The parking brake control device 24 is supplied with electric power from the battery 18 (or a generator driven by the engine) through the power supply line 19.

The parking brake control device 24 controls the drive of the electric motors 7A and 7A of the rear wheel side disc brakes 6 and 6, and brakes (parking brake, auxiliary brake) when the vehicle is parked or stopped (when traveling as necessary). ) Is generated. That is, the parking brake control device 24 drives the left and right electric motors 7A and 7A to operate (apply and release) the disc brakes 6 and 6 as parking brakes (auxiliary brakes if necessary). For this purpose, the parking brake control device 24 has an input side connected to the parking brake switch 23 and an output side connected to the electric motors 7A and 7A of the disc brakes 6 and 6. The parking brake control device 24 is a calculation circuit for detecting the driver's operation (operation of the parking brake switch 23), determining whether the electric motors 7A and 7A can be driven, determining whether the electric motors 7A and 7A are stopped, and the like. 25 and motor drive circuits 28, 28 for controlling the electric motors 7A, 7A are built-in.

The parking brake control device 24 is left and right based on an operation request (apply request, release request) by operating the parking brake switch 23 of the driver, an operation request by the parking brake apply / release determination logic, and an operation request by ABS control. The electric motors 7A and 7A of the above are driven, and the left and right disc brakes 6 and 6 are applied (held) or released (released). At this time, in the rear wheel side disc brake 6, the piston 6D and the brake pad 6C are held or released by the rotary linear motion mechanism 8 based on the drive of each electric motor 7A. As described above, the parking brake control device 24 responds to the operation request signal for the holding operation (apply) or the release operation (release) of the piston 6D (and thus the brake pad 6C), and the piston 6D (and by extension, the brake). The electric motor 7A is driven and controlled to propel the pad 6C).

As shown in FIG. 3, in the calculation circuit 25 of the parking brake control device 24, in addition to the memory 26 as a storage unit, the parking brake switch 23, the vehicle data bus 20, the voltage sensor unit 27, the motor drive circuit 28, and the current The sensor unit 29 and the like are connected. From the vehicle data bus 20, various state quantities of the vehicle required for controlling (operating) the parking brake, that is, various vehicle information can be acquired. Further, the parking brake control device 24 can output information and commands to various ECUs including the ESC control device 17 via the vehicle data bus 20 or the communication line.

The vehicle information acquired from the vehicle data bus 20 may be acquired by directly connecting a sensor for detecting the information to the parking brake control device 24 (calculation circuit 25). Further, in the calculation circuit 25 of the parking brake control device 24, an operation request based on the above-mentioned determination logic and ABS control is input from another control device (for example, ESC control device 17) connected to the vehicle data bus 20. It may be configured. In this case, the parking brake apply / release determination and ABS control by the above-mentioned determination logic can be performed by another control device, for example, the ESC control device 17, instead of the parking brake control device 24. .. That is, it is possible to integrate the control content of the parking brake control device 24 into the ESC control device 17.

The parking brake control device 24 includes a memory 26 as a storage unit including, for example, a flash memory, a ROM, a RAM, an EEPROM, and the like. The memory 26 stores the parking brake apply / release determination logic and the ABS control program. In addition to this, the memory 26 stores a processing program for executing the processing flow shown in FIGS. 4 to 6 described later, that is, a processing program used for control processing at the time of applying the electric parking brake. Further, the memory 26 also stores the relationship between the hydraulic pressure P shown in FIG. 7, which will be described later, and the apply _pause current threshold value I pain, and the relationship between the hydraulic pressure change amount ΔP shown in FIG. 8 and the _re -energization time tr. ing.

In the embodiment, the parking brake control device 24 is separated from the ESC control device 17, but the parking brake control device 24 and the ESC control device 17 are integrated (that is, integrally by one braking control device). ) May be configured. In this case, the functions of the parking brake control device 24 are integrated in the ESC control device 17, and the rear wheel side disc brakes 6 and 6 and the parking switch 23 are connected to the ESC control device 17. Further, the brake control program shown in FIGS. 4 to 6 described later is stored in the ESC control device 17, and the ESC control device 17 executes brake control for the electric brake device as the brake control device. The parking brake control device 24 is designed to control two rear wheel side disc brakes 6 and 6 on the left and right, but it may be provided for each of the left and right rear wheel side disc brakes 6 and 6, and in this case. Can also provide each parking brake control device 24 integrally with the rear wheel side disc brake 6.

As shown in FIG. 3, the parking brake control device 24 includes a voltage sensor unit 27 that detects the voltage from the power supply line 19, left and right motor drive circuits 28 and 28 that drive the left and right electric motors 7A and 7A, respectively, and left and right. The left and right current sensor units 29, 29 and the like for detecting the motor currents of the electric motors 7A and 7A are built-in. The voltage sensor unit 27, the motor drive circuit 28, and the current sensor unit 29 are each connected to the arithmetic circuit 25. As a result, in the arithmetic circuit 25 of the parking brake control device 24, the electric motor 7A is based on the current value (change) of the electric motor 7A detected by the current sensor unit 29 when applying or releasing the parking brake. It is possible to determine whether the drive is stopped (determination of application completion, determination of release completion), and the like. In the illustrated example, the voltage sensor unit 27 is configured to detect (measure) the power supply voltage, but for example, the voltage sensor unit (voltage sensor) has independent left and right voltage between the terminals of the electric motors 7A and 7A. It may be configured to measure.

By the way, the brake system of Patent Document 1 described above suppresses an excessive thrust generated based on the drive of an electric motor by correcting the current threshold value according to the hydraulic pressure. That is, when the electric parking brake is applied with the hydraulic pressure applied to the caliper, the piston is propelled not only by the thrust of the electric motor but also by the hydraulic pressure, and the piston thrust after the hydraulic pressure is released (hereinafter referred to as the holding thrust). ) May be excessive. In order to suppress this, it is effective to control the thrust by adjusting the thrust generated based on the drive of the electric motor according to the hydraulic pressure. However, for example, when the hydraulic pressure used for control (control recognition hydraulic pressure) deviates from the actual hydraulic pressure in the caliper (actual caliper hydraulic pressure, caliper hydraulic pressure true value) due to the delay of the hydraulic pressure information, If the thrust by the electric motor is controlled based on the control recognition hydraulic pressure, the holding thrust may be insufficient. On the other hand, in Patent Document 1, a margin is provided in advance in the thrust control amount of the electric motor with respect to the hydraulic pressure to generate a high thrust, thereby suppressing the shortage of the holding thrust. That is, in Patent Document 1, when the current threshold value is corrected, the shortage of thrust is suppressed by providing a margin in consideration of the dynamic characteristics of the hydraulic pressure.

More specifically, as shown in FIG. 13, the control recognition hydraulic pressure with respect to the caliper hydraulic pressure true value is accompanied by a communication delay due to reception (acquisition) via, for example, CAN (vehicle data bus 20), and a delay due to the filter. Therefore, an error (hydraulic pressure error) may occur when the hydraulic pressure fluctuates. According to Patent Document 1, a margin is provided in the control amount of the thrust by the electric motor with respect to the hydraulic pressure in consideration of the hydraulic pressure error due to the rapid decompression of the hydraulic pressure, thereby preventing the shortage of the holding thrust.

According to this technique, it is considered that the shortage of thrust at the time of sudden decompression can be suppressed. However, for example, when there is no fluctuation in hydraulic pressure, thrust for a margin (offset) is unnecessarily generated, and the thrust suppression effect may be reduced. On the other hand, when the hydraulic pressure is rapidly increased, the amount of thrust suppression with respect to the hydraulic pressure may be insufficient, and the holding thrust may become excessive. Further, at the time of application, the piston is propelled by the electric motor to expand the liquid chamber (hydraulic pressure chamber in the caliper), so that the hydraulic pressure inevitably fluctuates. Therefore, it is desired to be able to suppress excess / deficiency (excess / deficiency) of thrust even if the hydraulic pressure fluctuates during application.

Therefore, in the first embodiment, when adjusting the thrust driven by the electric motor 7A according to the hydraulic pressure, the following configuration is adopted so that the hydraulic pressure can be detected accurately and the excessive holding thrust can be suppressed. are doing. That is, in the first embodiment, the energization of the electric motor 7A is temporarily stopped during the application, that is, during the thrust generation at the time of application. At this time, the error between the caliper hydraulic pressure true value and the control recognition hydraulic pressure due to the hydraulic pressure delay is estimated from the hydraulic pressure change in the range including the temporary stop of energization. Then, based on the change in hydraulic pressure in consideration of this error, the necessity of re-driving the electric motor 7A after the temporary stop of energization (necessity of retightening) and the re-driving amount of the electric motor 7A (retightening amount) are determined. decide. In this case, for example, when the change in hydraulic pressure is reduced pressure, the thrust decreases, so the amount of retightening (re-energization time) is increased. On the other hand, when the change in hydraulic pressure is increased, the amount of retightening (re-energization time) is reduced or not retightened (re-energization time is set to 0). This makes it possible to suppress excessive holding thrust by reducing the variation in thrust caused by the delay in hydraulic pressure information. That is, when the thrust by the electric motor 7A is adjusted (suppressed) according to the hydraulic pressure, the hydraulic pressure is detected accurately (detected so as to avoid the hydraulic pressure error), and the holding thrust due to the hydraulic pressure fluctuation is excessive. It can be suppressed. As a result, the caliper 6B (hydraulic braking device) and the electric motor 7A (electric braking device) can be made smaller and lighter.

Therefore, in the first embodiment, the parking brake control device 24 (control unit) temporarily supplies electric power to the electric motor 7A in the section where thrust is generated in the piston 6D when the braking force is held. To stop. That is, the parking brake control device 24 (control unit) drives the electric motor 7A in response to the parking brake request signal (control command) that holds the braking force, and the current rise in which the thrust is generated in the piston 6D. At that time, the power supply to the electric motor 7A is temporarily stopped. In this case, the pause time is set to a time longer than the delay time of the hydraulic pressure information (and, for example, a time shorter than 1 to 2 seconds). After the pause time has elapsed, depending on the change in vehicle condition (change in hydraulic pressure), the apply may be terminated (completed) after resuming energization, or the apply may be terminated (completed) without resuming energization. ) May be done. In the following explanation, it will be suspended even if the energization is not resumed. For example, until the temporary stop time elapses, more specifically, until the power supply time ( _re -energization time tr) after the resumption of energization, which is the holding completion condition, is determined, the energization is temporarily performed, including the case where the energization is not resumed. It shall correspond to a stop.

The parking brake control device 24 (control unit) starts driving the electric motor 7A in response to a parking brake request signal (control command) by the parking brake switch 23 or the parking brake operation determination logic described above. In this case, the parking brake control device 24 first drives the electric motor 7A until the current threshold value (apply temporary stop current threshold value I _pause ) for suspending the drive of the electric motor 7A is reached. The current threshold value (apply temporary stop current threshold value I _pause ) is set so that the power supply of the electric motor 7A can be stopped in the section where thrust is generated in the piston 6D by driving the electric motor 7A. As a result, the parking brake control device 24 can temporarily stop the power supply to the electric motor 7A in the section where the thrust is generated in the piston 6D.

Here, when the parking brake control device 24 is driving and temporarily stopping the electric motor 7A, the hydraulic pressure information of the rear wheel side disc brake 6, that is, the hydraulic pressure P in the caliper 5A (of Change) is detected or estimated (calculated). The hydraulic pressure P in the caliper 5A includes the W / C hydraulic pressure P _{W /} C detected by the W / C pressure sensor 21 and the _M / C hydraulic pressure PM / C detected by the M / C pressure sensor 22. _C , M / C hydraulic pressure P W / C hydraulic pressure P _{W /} C calculated from _{M / C} , etc., hydraulic pressure P (P _{W / C} , PM _{/ C} ) that directly corresponds to the hydraulic pressure P In addition to being able to be used, information (state amount) S capable of estimating the hydraulic pressure P can be used. In the embodiment, the M / C hydraulic pressure P _{M /} C detected by the M / C pressure sensor 22 is used as the hydraulic pressure P.

The parking brake control device 24 starts driving the electric motor 7A by the parking brake request signal, and then temporarily drives the electric motor 7A according to the hydraulic pressure P (M / C hydraulic pressure PM _{/ C} ) in the caliper 5A. The current threshold to be stopped (apply temporary stop current threshold I _pause ) is determined. Specifically, when the electric motor 7A is being driven, the apply pause current threshold is based on the relationship between the hydraulic pressure P and the apply pause current threshold I _pause shown in FIG. 7 (solid characteristic line 31). I _path is determined to be a value corresponding to the hydraulic pressure P at that time (current control cycle). Then, when the current value (motor current I) of the electric motor 7A reaches (exceeds) the apply pause current threshold I _pause corresponding to the hydraulic pressure P at that time, the parking brake control device 24 determines the electric motor. The drive of 7A is temporarily stopped (the braking is temporarily held).

As described above, the parking brake control device 24 temporarily stops the power supply to the electric motor 7A according to the hydraulic pressure P applied to the piston 5B when the holding of the braking force is started. The apply pause current threshold value I _pause (hereinafter, also referred to as a pause current threshold I _pause ), which is a threshold value, is changed. That is, the parking brake control device 24 (control unit) acquires the hydraulic pressure P applied to the rear wheel side disc brake 6 when the holding of the braking force is started, and according to the acquired hydraulic pressure P. The apply temporary stop current threshold I _pause for temporarily stopping the power supply to the electric motor 7A is set. As shown in FIG. 7, the pause current threshold value I _pause is set as a value as the hydraulic pressure P becomes smaller. Therefore, when the hydraulic pressure P is small, the drive of the electric motor 7A can be temporarily stopped with a large temporary stop current threshold value I _pause . On the other hand, when the hydraulic pressure P is large, the drive of the electric motor 7A can be temporarily stopped with a small pause current threshold value I _pause . As a result, the drive of the electric motor 7A can be temporarily stopped at an appropriate pause current threshold value I _pause according to the hydraulic pressure P during the drive of the electric motor 7A.

In this case, the _pause current threshold value I pace is a section in which thrust is generated in the piston 6D based on the drive of the electric motor 7A, and the minimum value I _pmin is the idle running of the electric motor 7A. The value (for example, about 5A) is set higher than the current value (for example, about 1 to 3A) in the section (the section before the linear motion member 8A2 abuts on the piston 6D). Further, the temporary stop current threshold I _p0 when the hydraulic pressure P is 0 MPa is, for example, the final thrust (which can maintain the vehicle stop) to be applied only by driving the electric motor 7A while the hydraulic pressure P is 0 MPa. It can be set to be equal to or less than the current value corresponding to (thrust).

The parking brake control device 24 (control unit) temporarily stops the power supply to the electric motor 7A, and after the temporary stop time elapses, restarts the power supply to the electric motor 7A as needed. Then, the parking brake control device 24 completes the holding (apply) of the braking force when the holding completion condition for completing the holding of the braking force is satisfied. In this case, the parking brake control device 24 (control unit) determines the holding completion condition based on the change in the vehicle state when the power supply is temporarily stopped. That is, in the first embodiment, based on the change in the vehicle state when the power supply is temporarily stopped, more specifically, the change in the vehicle state during the temporary stop and / or before and after the temporary stop. Determines the retention completion condition after the power supply is suspended. The holding completion condition is determined by the change in the hydraulic pressure applied to the piston 6D as the vehicle state. That is, the parking brake control device 24 (control unit) acquires the change in the hydraulic pressure applied to the piston 6D as the vehicle state, and temporarily stops the power supply based on the change in the hydraulic pressure. Determine the retention completion condition.

For example, as for the holding completion condition, the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. That is, the parking brake control device 24 (control unit) holds the parking brake control device 24 (control unit) so that the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. Set the completion condition. More specifically, the larger the decrease in hydraulic pressure (decompression amount) while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. On the other hand, the larger the amount of increase in hydraulic pressure (increased pressure) while the power supply is temporarily stopped, the shorter the power supply time after restarting the power supply, or the zero (do not restart) the power supply time. The parking brake control device 24 restarts the driving of the electric motor 7A as necessary in order to establish the holding completion condition determined based on the change in the vehicle state (hydraulic pressure), and the electric motor 7A is under the determined holding completion condition. To stop.

Here, consider the case where the change in hydraulic pressure is decompression (rapid decompression). In this case, the error of the hydraulic pressure value recognized by the parking brake control device 24, that is, the hydraulic pressure error of the control recognition value due to the delay is lowered after the control recognition value is later than the true value which is the actual hydraulic pressure value. It is caused by that. Therefore, when the change in hydraulic pressure is reduced pressure, the control recognition value becomes larger than the true value. Therefore, in this case, the parking brake control device 24 detects the hydraulic pressure error (control recognition value> true value) generated by the delay of the control recognition hydraulic pressure at the time of depressurization during the temporary stop of energization, and FIG. The power supply time ( _re -energization time tre) after resuming energization is determined based on. Specifically, the shortage of thrust is avoided by lengthening the power supply time ( _re -energization time tre) after resuming energization (increasing the amount of retightening). As a result, it is possible to reduce the margin for the thrust suppression amount of the electric motor 7A, and it is possible to enhance the holding thrust suppression effect.

On the other hand, consider the case where the change in hydraulic pressure is increased (rapid increase). In this case, the hydraulic pressure error of the control recognition value due to the delay occurs because the control recognition value increases later than the true value. Therefore, when the change in hydraulic pressure is increased, the control recognition value becomes smaller than the true value. Therefore, in this case, the parking brake control device 24 detects the hydraulic pressure error (control recognition value <true value) generated by the delay of the control recognition hydraulic pressure at the time of boosting, and is described later. Based on 8, the power supply time ( _re -energization time tr) after resuming energization is determined. Specifically, by shortening the power supply time ( _re -energization time tr) after resuming energization (reducing the amount of retightening) or setting it to 0 (not retightening), it is possible to avoid excessive thrust. do. This makes it possible to enhance the effect of suppressing the holding thrust.

Further, the parking brake control device 24 detects the hydraulic pressure fluctuation by using the hydraulic pressure P in the state where the energization is temporarily stopped. Therefore, the hydraulic pressure can be monitored in a situation where the hydraulic pressure does not fluctuate due to the piston 6D being propelled by the electric motor 7A (the hydraulic pressure chamber expands). As a result, the hydraulic pressure detection accuracy can be improved, and the effect of suppressing the holding thrust can be enhanced from this aspect as well. The apply control (control process of FIGS. 4 to 6) of the electric motor 7A by the parking brake control device 24 when such a parking brake is operated (applied) will be described in detail later.

The brake system of the four-wheeled vehicle according to the first embodiment has the above-mentioned configuration, and the operation thereof will be described next.

When the driver of the vehicle depresses the brake pedal 9, the pedaling force is transmitted to the master cylinder 12 via the booster 11, and the brake fluid pressure is generated by the master cylinder 12. The brake fluid pressure generated in the master cylinder 12 is supplied to the disc brakes 5 and 6 via the cylinder side hydraulic pressure pipes 14A, 14B, ESC16 and the brake side piping portions 15A, 15B, 15C, 15D, and the left and right front wheels. Braking force is applied to 2 and the left and right rear wheels 3, respectively.

In this case, in the disc brakes 5 and 6, the pistons 5B and 6D are slidably displaced toward the brake pads 6C (only the rear wheel 3 side is shown) as the brake fluid pressure in the calipers 5A and 6B rises, and the brakes are braked. The pads 6C are pressed against the disc rotors 4 and 4. As a result, braking force based on the brake fluid pressure is applied. On the other hand, when the brake operation is released, the supply of the brake fluid pressure into the calipers 5A and 6B is stopped, so that the pistons 5B and 6D are displaced so as to be separated (backward) from the disc rotors 4 and 4. As a result, the brake pads 6C are separated from the disc rotors 4 and 4, and the vehicle is returned to the non-braking state.

Next, when the driver of the vehicle operates the parking brake switch 23 to the braking side (apply side), power is supplied from the parking brake control device 24 to the electric motors 7A of the left and right rear wheel side disc brakes to be electric. The motor 7A is rotationally driven. In the rear wheel side disc brake 6, the rotary motion of the electric motor 7A is converted into a linear motion by the rotary linear motion mechanism 8, and the piston 6D is propelled by the rotary linear motion member 8A. As a result, the disc rotor 4 is pressed by the brake pads 6C. At this time, the rotary linear motion mechanism 8 (linear motion member 8A2) is maintained in a braking state by, for example, a frictional force (holding force) due to screwing. As a result, the rear wheel side disc brake 6 is operated (applied) as a parking brake. That is, even after the power supply to the electric motor 7A is stopped, the piston 6D is held at the braking position by the rotary linear motion mechanism 8.

On the other hand, when the driver operates the parking brake switch 23 to the braking release side (release side), power is supplied from the parking brake control device 24 to the electric motor 7A so that the motor reverses. By this power supply, the electric motor 7A is rotated in the direction opposite to that when the parking brake is operated (when applied). At this time, the holding of the braking force by the rotary linear motion mechanism 8 is released, and the piston 6D can be displaced in the direction away from the disc rotor 4. As a result, the operation of the rear wheel side disc brake 6 as a parking brake is released (released).

Next, the apply control process performed by the arithmetic circuit 25 of the parking brake control device 24 will be described with reference to FIGS. 4 to 6. Note that FIG. 5 is a process following FIG. FIG. 6 corresponds to the “ΔP determination process” of S9 in FIG. The control process of FIGS. 4 to 6 is repeatedly executed in a predetermined control cycle (for example, 10 msec) while the parking brake control device 24 is energized, for example. These processes are a brake control method for controlling the electric motor 7A, and are executed by the parking brake control device 24, which is a brake control device, as a brake control program.

When the parking brake control device 24, which is an ECU (Electronic Control Unit), is activated, the apply control process of FIG. 4 is started. When the processing routine is started, the parking brake control device 24 determines in S1 whether or not the apply operating flag is ON. The apply flag is a determination flag for determining whether or not the apply is in operation. The apply flag is turned on during the apply operation, that is, during the period from the start to the completion of the apply, including the temporary stop of the drive of the electric motor 7A. Specifically, it is turned on in the process of S3 described later, and turned off in the process of S15 (FIG. 5).

If it is determined in S1 that "NO", that is, the applying flag is OFF, the process proceeds to S2. If "YES" in S1, that is, if it is determined that the apply operation flag is ON, the process proceeds to S4. In S2, it is determined whether or not there is an apply command (control command). In this S2, it is determined whether or not the apply command is output from the parking brake switch 23, the parking brake apply determination logic, or the like. If "YES" in S2, that is, if it is determined that there is an apply command, the process proceeds to S3. On the other hand, if it is determined in S2 as "NO", that is, there is no apply command, a return is made. That is, the process returns to the start of FIG. 4 via the “B” of FIG. 4, the “B” of FIG. 5, and the return of FIG. 5, and the processing after S1 is repeated.

In S3, the flag during apply operation is turned ON. Further, the electric motor 7A is driven in the apply direction. In S3, when the applying flag is turned on and the electric motor 7A is started to be driven in the applying direction, the process proceeds to S4. S3 corresponds to a step of starting power supply to the electric motor 7A in response to a control command (apply command) for holding the braking force of the rear wheel side disc brake 6. At this time, that is, in S3, when the driving of the electric motor 7A is started, the counting of the timer (timer for determining the inrush current progress) is started. In S4, it is determined whether or not the inrush current mask time has elapsed. The inrush current mask time is the time after the electric motor 7A starts operating in the apply direction, and sets the time for the inrush current to sufficiently converge. If it is determined in S4 as "NO", that is, the elapsed time by the inrush current progress determination timer has not elapsed the inrush current mask time, the process returns. This makes it less susceptible to the inrush current when determining the apply _pause current threshold I path in subsequent S6, that is, the current value is applied by the inrush current to the apply _pause current threshold I path or the apply completion current threshold I _cut . This is to prevent the application from being suspended or erroneously detected when the application is completed. On the other hand, if it is determined in S4 that "YES", that is, the inrush current mask time has elapsed, the process proceeds to S5.

In S5, it is determined whether or not the apply pause flag is ON. The apply temporary stop flag is a determination flag for determining whether or not the energization is temporarily stopped during the apply operation, and is turned on when the power supply to the electric motor 7A is temporarily stopped. Specifically, it is turned ON in the process of S7 described later, and turned OFF in the process of S15.

If it is determined in S5 that "NO", that is, the apply pause flag is not ON (OFF), the process proceeds to S6. If "YES" in S5, that is, if it is determined that the apply pause flag is ON, the process proceeds to S8. In S6, it is determined whether or not the motor current I exceeds (exceeds) the pause current threshold value I _pause . Here, the pause current threshold value I _pause is determined using the map (characteristic diagram) shown in FIG. 7. That is, in S6, the hydraulic pressure value P when advancing to S6, specifically, the hydraulic pressure P (M / C liquid of the M / C pressure sensor 22) received (acquired) via CAN (vehicle data bus 20). From the pressure PM _{/ C} ), the pause current threshold I _pause is set (determined) based on the characteristic line 31 shown by the solid line in FIG. 7. Then, the "pause current threshold value I _pause corresponding to the hydraulic pressure P when advancing to S6" and the "motor current value I at the present time (when advancing to S6)" are compared, and the motor current I is the pause current. It is determined whether or not it is larger than the threshold value I _pain . S6 acquires the hydraulic pressure applied to the rear wheel side disc brake 6 when the current supply to the electric motor 7A is started, and temporarily supplies the electric power to the electric motor 7A according to the acquired hydraulic pressure. Corresponds to the step of setting the current threshold for stopping the motor.

Here, as shown in FIG. 7, the pause current threshold value I _pause is set lower as the hydraulic pressure P (master cylinder hydraulic pressure) acquired via CAN (vehicle data bus 20) increases. However, it is not suppressed below the lower limit value I _{p min} so that the pause is not erroneously determined by the current in the no-load state. The lower limit value I _pmin is a reliable current value at which braking force (thrust) is generated (thrust is generated when the linear motion member 8A2 abuts on the piston 6D), in other words, the piston 6D is driven by the electric motor 7A. It corresponds to the certain current value that the thrust is generated. The lower limit value I _pmin is set as a value (for example, about 5 A) higher than the current value (idle running current I ₀ , for example, 1 A to 3 A) in the idle period before the braking force is generated.

Further, in FIG. 7, the solid characteristic line 31 is P ₀ in the X-axis direction with respect to the broken line characteristic line 32, which is the relationship between the ideal hydraulic pressure P and the pause current threshold value I _pause without considering the error. It is offset by a minute. That is, the offset _P0 is provided in the calculation of the pause current threshold value I _pause . This offset P ₀ (margin) is set to be larger than the hydraulic pressure error (hydraulic pressure recognition value is larger than the true value) in the thrust decreasing direction that occurs in the hydraulic pressure P due to “factors other than delay”. This prevents the thrust from becoming insufficient due to an error due to "factors other than delay". Here, the "delay" is, for example, a communication delay by the vehicle data bus 20, a calculation delay (processing delay) of an electronic device (control unit: ESC control device 17, parking brake control device 24) that processes the hydraulic pressure P. Can be mentioned. In the embodiment, the offset P ₀ is based on an error due to a "factor other than the delay" that does not include such a delay, for example, a hydraulic pressure error due to an unavoidable detection error (sensor error) of the M / C pressure sensor 22. Is also set large.

If "YES" in S6, that is, if it is determined that the motor current I is larger than the pause current threshold value I _pause , the process proceeds to S7. If it is determined in S6 that "NO", that is, the motor current I is equal to or less than the pause current threshold value I _pause , the motor returns. In S7, the apply temporary stop flag is turned ON, and the energization of the electric motor 7A is temporarily stopped. S7 corresponds to a step of temporarily stopping the power supply to the electric motor 7A when the current in which thrust is generated in the piston 6D rises. Further, the hydraulic pressure P (M / C hydraulic pressure PM _{/ C} ) acquired via the CAN (vehicle data bus 20) at that time point (time point when the process proceeds to S7, time point t ₁ in FIG. 9) is used as the hydraulic pressure P ₁ . Remember as. In S8 following "YES" in S7 or S5, it is determined whether or not the preset apply pause time has elapsed since the apply pause flag was turned ON. If it is determined in S8 that "YES", that is, the apply suspension time has elapsed, the process proceeds to S9 in FIG. 5 via "A" in FIG. 4 and "A" in FIG. If it is determined in S8 that "NO", that is, the apply suspension time has not elapsed, a return is made. Here, the apply pause time is set to be longer than the delay time of the hydraulic pressure P. As a result, in the subsequent ΔP determination process of S9, it is possible to determine the occurrence of an error due to the delay of the hydraulic pressure P.

In S9, the ΔP determination process is performed. The ΔP determination process of S9 is the process shown in FIG. In the ΔP determination process of S9, the power supply time ( _re -energization time tre) after resumption of energization is determined based on the change amount ΔP (P2 _- P ₁ ) of the hydraulic pressure during the temporary stop of energization. That is, in S9, the re-energization time tr including whether or not to _re -energize after the elapse of the energization suspension time is determined based on the change amount ΔP of the hydraulic pressure when the power supply is temporarily stopped. When the result is determined to be "YES" in S8 and the process proceeds to S9, that is, S9-1 in FIG. 6, S9-1 determines whether or not the _re -energization time tr has been calculated. If it is determined in S9-1 that "NO", that is, the _re -energization time tre has not been calculated, the process proceeds to S9-2. If "YES" in S9-1, that is, if it is determined that the _re -energization time tr has been calculated, the process proceeds to S10 in FIG. 5 via the return in FIG. The _re -energization time tr is a time (power supply time) for supplying power to the electric motor 7A after restarting the power supply.

In S9-2, the hydraulic pressure P (M / C hydraulic pressure PM _{/ C} ) received via the CAN (vehicle data bus ₂₀ ) at that time point (time point when proceeding to S9-2, time point t2 in FIG. 9). Is stored as the hydraulic pressure P ₂ . _In S9-2, the difference in hydraulic pressure between the hydraulic pressure P1 stored in S7 and P2 stored in S9-2, that is, the amount of change in hydraulic pressure ΔP ( ₌ P2 _{- P1} ) is calculated. Here, when ΔP> 0 (P ₂ > P ₁ ), the hydraulic pressure P is increasing, and when ΔP <0 (P ₂ <P ₁ ), the hydraulic pressure P is decreasing. When ΔP = 0, the hydraulic pressure P has not changed (the hydraulic pressure P is constant). After calculating the change amount ΔP of the hydraulic pressure in S9-2, the process proceeds to S9-3.

In S9-3, the _re -energization time tr is determined (calculated). S9-3 corresponds to a step of setting a holding completion condition based on a change in the vehicle state when the power supply to the electric motor 7A is temporarily stopped. _{The re} -energization time tr, which is a holding completion condition, is determined (calculated) using, for example, the map (characteristic diagram) shown in FIG. That is, in S9-3, based on the relationship between the _re -energization time tre and the change amount ΔP shown in FIG. 8 (solid line characteristic line 41), the change amount ΔP of the hydraulic pressure calculated in S9-2 immediately before is re-started. Determine the energization time _tr . Here, as shown in FIG. 8, when the change amount ΔP is smaller than the hydraulic pressure change threshold value ΔP _max (when the change in pressure increase is small, when it is 0, when the pressure is reduced), the _re -energization time tr is 0. Become bigger. In this case, the smaller the change amount ΔP is with respect to the hydraulic pressure change threshold value ΔP _max (on the reduced pressure side), the longer the _re -energization time tre (the amount of retightening due to re-energization increases). On the other hand, when the change amount ΔP is equal to or greater than the hydraulic pressure change threshold value ΔP _max (when the change in pressure increase is large), the re-energization time _tr becomes 0 (not re-energized and not retightened). As a result, the larger the amount of change ΔP (toward the reduced pressure side), the longer the power supply time after re-energization. The ΔP _max can be set so that necessary re-energization (retightening) can be performed after the energization suspension, for example, in relation to the apply pause current threshold value I _pause and the change amount ΔP. S9-3 corresponds to a step of acquiring a change in the hydraulic pressure applied to the piston 6D as a vehicle state and setting a holding completion condition based on the change in the hydraulic pressure. Further, S9-3 is a step of setting a holding completion condition so that the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. Equivalent to.

In S9-4 following S9-3, it is determined whether or not the _re -energization time tre calculated in S9-3 is larger than 0 ( _tre > 0). When "YES" in S9-4, that is, when it is determined that the _re -energization time tr is 0 or larger, it corresponds to the case where re-energization is necessary. In this case, the process proceeds to S10 in FIG. 5 via the return in FIG. On the other hand, when it is determined in S9-4 that "NO", that is, the re-energization time _tr is 0 ( _tre = 0), it corresponds to the case where re-energization is not necessary. In this case, after turning on the apply completion flag in S9-5, the process proceeds to S10 in FIG. 5 via the return in FIG.

As shown in FIG. 5, in S10 following S9, it is determined whether or not the apply completion flag is ON. If "YES" in S10, that is, if it is determined that the apply completion flag is ON, the process proceeds to S15. If it is determined in S10 that "NO", that is, the apply completion flag is not ON, the process proceeds to S11.

In S11, it is determined whether or not the temporarily stopped electric motor 7A is being re-energized. If "YES" in S11, that is, if it is determined that the electric motor 7A is being re-energized, the process proceeds to S13. If it is determined in S11 that "NO", that is, the electric motor 7A is not being re-energized, the process proceeds to S12. In S12, energization of the electric motor 7A is resumed, and the process proceeds to S13. At this time, that is, in S12, when the energization is restarted, the timer (energization restart timer) starts counting. S12 corresponds to a step of temporarily stopping the power supply to the electric motor 7A and then restarting the power supply to the electric motor 7A.

In S13, it is determined whether or not the elapsed time after restarting the energization (counting time of the energization restart timer) exceeds the _re -energization time tr calculated in S9-3 of FIG. In other words, in S13, the holding completion condition for completing the holding of the braking force (stopping the electric motor 7A), more specifically, the holding completion condition determined when the power supply is temporarily stopped is set. Determine if it holds. In S13, it was determined that "YES", that is, the time after restarting the energization of the electric motor 7A (counting time of the energization restart timer) has elapsed the _re -energization time tr (the holding completion condition is satisfied). In that case, the process proceeds to S14. In S13, it was determined that "NO", that is, the time after resuming the energization of the electric motor 7A (count time of the energization restart timer) does not exceed the _re -energization time tr (the holding completion condition is not satisfied). If so, return.

In S14, in order to stop the re-driving (re-energization) of the electric motor 7A, the apply completion flag is turned ON and the process proceeds to S15. In S15, each timer (timer for determining inrush current progress, timer for restarting energization) and flags (apply operating flag, apply pause flag, apply complete flag flag) are cleared. That is, each timer is set to 0 and each flag is set to OFF. Further, in S15, the energization of the electric motor 7A is stopped (completely stopped even during the temporary stop of energization). That is, in S15, the holding of the braking force is completed (the application is completed), and the return is performed. S15 corresponds to a step of completing the holding of the braking force when the holding completion condition for completing the holding of the braking force is satisfied.

Next, FIG. 9 shows an example of a time chart (time change of motor current I and hydraulic pressure P at the time of application) when the processing shown in FIGS. 4 to 6 is performed by the parking brake control device 24. In FIG. 9, the hydraulic pressure chamber is expanded by the piston 6D propelling based on the drive of the electric motor 7A in a state where a constant hydraulic pressure is applied, and the hydraulic pressure decreases as the hydraulic pressure chamber expands. It shows the case of doing. It should be noted that, for example, the case where the hydraulic pressure P changes (decreases) based on the operation of the brake pedal 9 or the like can be considered in the same manner. Further, the hydraulic pressure P indicates a hydraulic pressure (control recognition hydraulic pressure) recognized by the parking brake control device 24 via CAN (vehicle data bus 20).

As shown in FIG. 9, when the parking brake control device 24 receives an apply command, it supplies electric power to the electric motor 7A and drives the electric motor 7A in the apply direction. At this time, since the electric motor 7A shifts from the stopped state to the driven state, a large inrush current is generated once, and then it decreases and is maintained at a constant value (current value I ₀ ). When the current is constant (current value I ₀ ), it corresponds to the idle period before the linear motion member 8A2 abuts on the piston 6D. When the linear motion member 8A2 comes into contact with the piston 6D, the motor current I starts to increase. From here, the section where the thrust is generated in the piston 6D starts, and the current supplied to the motor 7A increases as the transmitted thrust to the piston 6D increases. At this time, the hydraulic pressure P decreases as the hydraulic pressure chamber expands due to the propulsion of the piston 6D. In this case, the hydraulic pressure P recognized by the parking brake control device 24 starts to decrease after the motor current I starts to increase due to the above-mentioned delay.

The parking brake control device 24 temporarily stops the electric motor 7A during the application based on the "hydraulic pressure P at that time" and the "characteristic line 31 of FIG. 7" by the process of S6 in FIG. The pause current threshold I _pause is set. When the motor current I exceeds the apply temporary stop current threshold value I _pause corresponding to the hydraulic pressure P at the time point t ₁ , the power supply to the electric motor 7A is stopped. As a result, the rotation of the electric motor 7A is stopped. At this time, the decrease in the hydraulic pressure P does not stop immediately, but stops later _than the time point t1 due to the delay. _At the time t2 when the apply suspension time has elapsed, the parking brake control device 24 is subjected to the processing of S9-2 and S9-3 in _FIG . The _re -energization time tre (retention completion condition) is determined based on the difference ΔP (= P2 _- P ₁ ) from the hydraulic pressure P ₂ when the time elapses and the “characteristic line 41 in FIG. 8”. .. When the _re -energization time tr is larger than 0, the parking brake control device 24 restarts the energization of the electric motor 7A at the _time t2 when the apply suspension time elapses. When the _re -energization time tr elapses after the parking brake control device 24 restarts the energization, the energization (re-energization) of the electric motor 7A is stopped, and the apply process is completed. When the _re -energization time tr is 0, the holding completion condition is that the energization is not restarted. Therefore, the apply process ends at t2 when the apply suspension _time elapses. As a result, the re-energization including the necessity of restarting the energization is based on the change amount ΔP (= P ₂ -P ₁ ) of the hydraulic pressure during the temporary stop of the electric motor 7A (more specifically, before and after the temporary stop). Excess or deficiency of thrust can be suppressed by determining the time and re-energizing as necessary.

As described above, in the first embodiment, the holding completion condition (re-energization time tr) for completing the holding of the braking force when the power supply to the electric motor 7A is temporarily stopped is set to the vehicle state (re-energization time _tr ). Determined based on changes in hydraulic pressure P). As a result, the holding of the braking force can be completed under the holding completion condition ( _re -energization time tr) corresponding to the change in the vehicle state (hydraulic pressure P). In this case, by suspending the power supply, the influence (error) due to the delay of the vehicle state information (for example, hydraulic pressure information) is suppressed, and it is appropriate according to the vehicle state (change) at that time. Holding can be completed by braking force. As a result, it is possible to suppress excess / deficiency (excess / deficiency) of thrust due to a change in the vehicle state (hydraulic pressure P) when the braking force is maintained based on the drive of the electric motor 7A.

In the first embodiment, the apply temporary stop current threshold value I _pause for temporarily stopping the power supply to the electric motor 7A is changed according to the hydraulic pressure P. Therefore, the power supply to the electric motor 7A can be temporarily stopped at an appropriate apply temporary stop current threshold value I _pause according to the hydraulic pressure P. That is, the power supply can be temporarily stopped before the thrust becomes excessive. When it is necessary to restart the power supply based on the change in the vehicle state (hydraulic pressure P) when the vehicle is temporarily stopped, the power supply can be restarted to prevent the thrust from becoming insufficient.

In the first embodiment, the holding completion condition for completing the holding of the braking force is determined by the change in the hydraulic pressure P. Therefore, the holding of the braking force can be completed under the holding completion condition ( _re -energization time tr) corresponding to the change in the hydraulic pressure P. Moreover, as for the holding completion condition ( _re -energization time tre), the larger the change amount ΔP of the hydraulic pressure P while the power supply is temporarily stopped, the larger the hydraulic pressure P becomes on the decompression side. The more it changes (the larger the decompression amount), the longer the _re -energization time tr, which is the power supply time after restarting the power supply. Therefore, even if the power supply is temporarily stopped in a state where the thrust is low in order to suppress the excessive thrust, it is possible to suppress the shortage of the thrust when the holding of the braking force is completed.

Next, FIGS. 10 to 12 show a second embodiment. The feature of the second embodiment is that when the power supply is temporarily stopped during the application, the application is terminated by restarting the power supply and stopping the power supply after reaching a predetermined current threshold value. It is to decide whether to "do" or "end the apply without restarting". In the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

Similar to the first embodiment, the second embodiment also determines the holding completion condition for completing the application based on the change in the vehicle state (hydraulic pressure) when the power supply is temporarily stopped. .. In the first embodiment described above, the _re -energization time tre (retention completion condition) after the energization suspension is determined based on the pressure difference before and after the energization suspension during the application. On the other hand, in the second embodiment, it is determined whether or not to restart the energization after the energization suspension is based on the pressure difference before and after the energization suspension during the application. In this case, as the holding completion condition, "holding is completed by restarting the power supply and stopping the power supply when the apply completion current threshold value I _cut is reached" or "holding is completed without restarting the power supply". Decide whether to do it.

Here, in the second embodiment, when the power supply is temporarily stopped, the apply temporary stop current threshold value I _pause is determined based on a map (not shown) similar to the map shown in FIG. 7 described above. .. In this case, in the second embodiment, the offset P ₀ is not only the hydraulic pressure error in the thrust decreasing direction (the hydraulic pressure recognition value is larger than the true value) due to factors other than the delay such as the sensor error generated in the hydraulic pressure P. , It is set larger than the hydraulic pressure error due to the delay that occurs in the normal range. That is, the offset P ₀ of the second embodiment has a larger value than the offset P ₀ shown in FIG. 7 of the first embodiment. Therefore, the relationship between the hydraulic pressure P and the apply pause current threshold value I _pause in the second embodiment is, for example, a characteristic line in which the characteristic line 31 of FIG. 7 of the first embodiment is translated to the right as a whole. Can be set as. As a result, it is possible to suppress a shortage of thrust while reducing the frequency of retightening. Further, for example, the temporary stop current threshold value I _p0 when the hydraulic pressure P is 0 MPa can also be made larger than the temporary stop current threshold value I _p0 of the characteristic line 31 of FIG. 7.

Further, in the second embodiment, when it is determined that the power supply is restarted based on the change in the hydraulic pressure P in the vehicle state when the power supply is temporarily stopped, the current of the electric motor 7A is restarted after the restart. When the value (motor current I) reaches (exceeds) the apply completion current threshold I _cut , the drive of the electric motor 7A is stopped. The apply completion current threshold value I _cut is a current threshold value after restarting the power supply, that is, a current threshold value for stopping the restarted power supply to complete the apply. The apply completion current threshold value I _cut is set as, for example, a current threshold value I _max that can apply the necessary thrust (thrust that can maintain the stop of the vehicle) by driving the electric motor 7A when the hydraulic pressure P is 0 MPa. Can be done. This makes it possible to avoid a shortage of thrust when a hydraulic pressure error occurs due to a delay.

In order to perform such control processing, the memory 26 of the parking brake control device 24 stores a processing program for executing the processing flow shown in FIGS. 4, 10, and 11. Note that FIG. 10 is a process following FIG. FIG. 11 corresponds to the “ΔP determination process” of S21 in FIG. Since the control process of FIG. 4 has been described in the first embodiment, the description thereof will be omitted. Further, the processing of S10, S11, S12, S14, and S15 in FIG. 10 is the same as the processing of S10, S11, S12, S14, and S15 in FIG. Since -4 is the same as the processing of S9-2 and S9-5 in FIG. 6, the description thereof will be omitted.

In S21 (FIG. 10) following “YES” in S8 (FIG. 4), ΔP determination processing is performed. The ΔP determination process of S21 is the process shown in FIG. In the ΔP determination process of S21, it is determined whether or not to re-energize after the elapse of the energization suspension time based on the change amount ΔP (P2 _- P ₁ ) of the hydraulic pressure during the energization suspension. Specifically, if "YES" is determined in S8 (FIG. 4) and the process proceeds to S21 in FIG. 10, that is, S21-1 in FIG. 11, S21-1 determines whether or not the amount of change ΔP has been calculated. do. If it is determined in S21-1 that "YES", that is, the amount of change ΔP has already been calculated, the process proceeds to S10 in FIG. 10 via the return in FIG. If it is determined in S21-1 that "NO", that is, the amount of change ΔP has not been calculated, the process proceeds to S21-3 via S21-2.

In S21-3, it is determined whether or not the amount of change ΔP during the suspension of energization is smaller than the hydraulic pressure change threshold value ΔP _max (ΔP <ΔP _max ). The hydraulic pressure change threshold value ΔP _max is set smaller than the offset P ₀ , which is the hydraulic pressure error margin. If "YES" in S21-3, that is, if the change amount ΔP is determined to be smaller than the hydraulic pressure change threshold value ΔP _max (ΔP <ΔP _max ), the process proceeds to S10 in FIG. 10 via the return in FIG. If it is determined in S21-3 that "NO", that is, the amount of change ΔP is equal to or greater than the hydraulic pressure change threshold value ΔP _max (ΔP ≧ ΔP _max ), the process proceeds to S21-4.

Here, if "YES" in _S21-3 , that is, if it is determined that the amount of change ΔP (change in hydraulic pressure) during the temporary stop of energization is smaller than the hydraulic pressure change threshold value ΔP _max , the hydraulic pressure error sets the margin P0. May exceed. Therefore, in S21-3, it is detected (determined) whether or not the margin P ₀ is exceeded, and if it exceeds the margin P 0, energization is restarted (retightened) in the subsequent processing. On the other hand, if it is determined in S21-3 that "NO", that is, the amount of change ΔP (change in hydraulic pressure) during suspension of energization is equal to or greater than the hydraulic pressure change threshold value ΔP _max , the application is completed in the process of S21-4. Turn on the flag to prevent the energization from being restarted (retightened) in the subsequent processing. In this way, in S21-3, the holding completion condition for ending (completed) the apply is determined.

In S22 of FIG. 10, it is determined whether or not the inrush current mask time has elapsed after the resumption of energization. The inrush current mask time after resuming energization is the time after resuming energization in S12, and sets the time for the inrush current for resuming energization to sufficiently converge. If "YES" in S22, that is, if it is determined that the inrush current mask time has elapsed after resuming energization, the process proceeds to S23. If it is determined in S22 that "NO", that is, the inrush current mask time has not elapsed after the resumption of energization, the process returns.

In S23, it is determined whether or not the motor current I exceeds the apply completion current threshold value I _cut (I> I _cut ). That is, in S23, it is determined whether or not the holding completion condition determined when the power supply is temporarily stopped is satisfied. When it is determined in S23 that "NO", that is, the motor current I is equal to or less than the apply completion current threshold value I _cut (I ≦ I _cut ), the holding completion condition is not satisfied, and the process returns. When "YES" in S23, that is, when it is determined that the motor current I exceeds the apply completion current threshold value I _cut (I> I _cut ), the holding completion condition is satisfied, and the holding completion condition is satisfied. Proceed to S15.

FIG. 12 shows an example of a time chart (time change of motor current I and hydraulic pressure P at the time of application) when the processing shown in FIGS. 4, 10 and 11 is performed by the parking brake control device 24. At the time point t ₁ , when the motor current I exceeds the apply temporary stop current threshold value I _pause corresponding to the hydraulic pressure P at that time, the power supply to the electric motor 7A is temporarily stopped. In the second embodiment, the parking brake control device 24 is "liquid when the electric motor 7A is stopped by the processing of S21-2 and S21-3 of _FIG . 11 at the time t2 when the apply suspension time has elapsed. The holding completion condition is determined based _on the difference ΔP _{( =} P2 _- P1) between the pressure P1 and the hydraulic pressure P2 when the apply suspension time has elapsed.

Specifically, when the change amount ΔP is smaller than the hydraulic pressure change threshold value ΔP _max , the parking brake control device 24 resumes energization after the apply suspension time elapses, and the motor current I exceeds the apply completion current threshold value I _cut . It is decided as a retention completion condition. The parking brake control device 24 resumes energization of the electric motor 7A at t2 when the apply suspension _time has elapsed. When the motor current I exceeds the current threshold value I _cut , the parking brake control device 24 stops energization (re-energization) of the electric motor 7A and ends the apply process. When the change amount ΔP of the hydraulic pressure P is larger _than the hydraulic pressure change threshold value ΔP _max , the holding completion condition is that the energization is not restarted. .. As a result, it is determined whether or not to restart the energization based on the amount of change in hydraulic pressure ΔP (= P ₂ -P ₁ ) during the temporary stop (more specifically, before and after the temporary stop) of the electric motor 7A. Excess or deficiency of thrust can be suppressed by re-energizing as necessary.

The second embodiment performs an apply process including a temporary stop of power supply based on the processes of FIGS. 4, 10 and 11 as described above, and the basic operation thereof is the first embodiment. There is no particular difference from the one by form. That is, the second embodiment can also suppress the excess or deficiency of the thrust at the time of completion of the application, as in the first embodiment.

In each embodiment, the parking brake control device 24 receives the hydraulic pressure P (M / C hydraulic pressure PM / _C ) via the CAN (vehicle data bus 20), and the hydraulic pressure P is used for apply control. The case where the processing is performed has been described as an example. However, the present invention is not limited to this, and if the recognition master hydraulic pressure of the ESC 16 can be received without going through the CAN, for example, when the electric parking brake is controlled by the ESC control device 17 (apply control processing is performed), the case is not limited to this. Control (apply control) may be performed based on the hydraulic pressure value.

In each embodiment, the case where _{M / C hydraulic pressure PM / C} is used as the hydraulic pressure P has been described as an example. However, the present invention is not limited to this, and for example, a hydraulic pressure other than _M / C hydraulic pressure PM _{/ C such as W / C hydraulic pressure P W / C} may be used as the hydraulic pressure P. In each embodiment, the case where the hydraulic pressure P is used as the vehicle state has been described as an example. However, not limited to this, the vehicle state includes, for example, the operation amount of the brake pedal, the displacement amount of the input member (input rod) of the booster, the rotation amount of the electric motor of the electric booster, and the displacement of the piston of the master cylinder. A vehicle state other than the hydraulic pressure (vehicle state amount) such as an amount may be used.

In each embodiment, the change amount ΔP is calculated from the hydraulic pressure difference from the time when the energization is temporarily stopped (time point t ₁ ) to the time when the power is restarted (time point t ₂ ) (and the holding completion condition is determined based on the change amount ΔP). This was explained by taking the case of. However, the present invention is not limited to this, and for example, the hydraulic pressure value before the energization suspension or after the energization stop may be referred to (the holding completion condition is determined based on the hydraulic pressure value before the energization suspension or after the energization stop). May be). As a result, it is possible to prevent the apply suspension time from becoming excessively long when the delay time of the hydraulic pressure information is large for the hydraulic pressure change. Further, the difference between the maximum hydraulic pressure and the minimum hydraulic pressure in the determination section during the temporary stop of energization may be set as the change amount ΔP. As a result, it is possible to improve the robustness against insufficient thrust due to the hydraulic pressure information becoming larger than the true value.

In the second embodiment, the apply completion current threshold value I _cut is constant regardless of the hydraulic pressure P (for example, the current threshold value I _max that can apply the required thrust by the electric motor 7A when the hydraulic pressure P is 0 MPa). ) Was set as an example. However, the present invention is not limited to this, and for example, the apply completion current threshold value I _cut may be set to be lower as the hydraulic pressure is higher, as in the apply pause current threshold value I _pause shown in FIG. 7. As a result, the thrust suppression effect can be obtained even when a hydraulic pressure error occurs due to a delay.

In each embodiment, the holding completion condition (apply completion condition) is determined when the power supply is temporarily stopped during the application, and the holding of the braking force is completed when the holding completion condition is satisfied (apply). The case where the configuration is completed) has been described as an example. In this case, the temporary stop of the power supply corresponds to the temporary stop in the middle of the application, that is, the temporary stop of the power supply from the start of the application to the completion of the application. On the other hand, after the application including the temporary stop of the power supply is completed, the reapply (rehold, reclamp) may be performed as necessary. For example, in consideration of a decrease in braking force due to heat shrinkage after the application is completed, a reapply (for example, a few minutes after the temperature of the braking member and the braked member decreases) after a predetermined time has passed from the application completion (for example, a few minutes after the temperature of the braking member and the applied member decreases). Re-holding, reclamping) may be performed. The time from the completion of application to the re-apply (re-apply start time) does not correspond to the apply pause time.

In each embodiment, a case where the rear wheel side disc brake 6 is a hydraulic disc brake with an electric parking brake function and the front wheel side disc brake 5 is a hydraulic disc brake without an electric parking brake function is taken as an example. I mentioned and explained. However, the present invention is not limited to this, and for example, the rear wheel side disc brake 6 may be a hydraulic disc brake without an electric parking brake function, and the front wheel side disc brake 5 may be a hydraulic disc brake with an electric parking brake function. good. Further, both the front wheel side disc brake 5 and the rear wheel side disc brake 6 may be used as hydraulic disc brakes with an electric parking brake function. In short, the brakes of at least a pair of left and right wheels of the wheels of the vehicle can be configured by the electric parking brake.

In each embodiment, a hydraulic disc brake, that is, a rear wheel side disc brake 6 has been described as an example as a hydraulic braking device. However, the present invention is not limited to this, and various hydraulic braking devices such as a hydraulic drum brake may be used as the hydraulic braking device. In each embodiment, a case where the electric brake device is provided with the electric motor 7A and the rotary linear motion mechanism 8 has been described as an example. However, the present invention is not limited to this, and various electric brake devices (electric brake mechanism, electric parking mechanism) such as a configuration including an electric motor and a ratchet mechanism may be used. That is, a hydraulic disc brake with an electric parking brake function, a hydraulic drum brake with an electric parking brake function, a drum-in disc brake with a drum type electric parking brake on the disc brake, and parking by pulling a cable with an electric motor. Various electric parking brake devices composed of a hydraulic braking device and an electric braking device, such as a configuration for holding a brake, can be adopted. Furthermore, it is needless to say that each embodiment is exemplary and the configurations shown in different embodiments can be partially replaced or combined.

As the brake system, the brake control device, the brake control method, and the brake control program based on the embodiments described above, for example, the ones described below can be considered.

The first aspect is a hydraulic braking device that propels the piston by hydraulic pressure to press the braking member against the braked member, and the piston is propelled by the thrust transmitted from the electric motor to press the braking member against the braked member. An electric braking device that presses against a member to hold a braking force, and when the braking force is held, the power supply to the motor is temporarily stopped in a section where a thrust is generated in the piston, and then to the motor. The control device comprises a control device that completes the holding of the braking force when the holding completion condition for restarting the power supply and completing the holding of the braking force is satisfied, and the control device temporarily stops the power supply. At that time, the holding completion condition is determined based on the change in the vehicle state.

According to this first aspect, the holding completion condition for completing the holding of the braking force when the power supply to the electric motor is temporarily stopped is determined based on the change in the vehicle state. As a result, the holding of the braking force can be completed under the holding completion condition corresponding to the change in the vehicle state. In this case, by suspending the power supply, the influence (error) due to the delay of the vehicle state information (for example, hydraulic pressure information) is suppressed, and it is appropriate according to the vehicle state (change) at that time. Holding can be completed by braking force. As a result, it is possible to suppress excess / deficiency (excess / deficiency) of thrust due to a change in the vehicle state when the braking force is maintained based on the drive of the electric motor.

As a second aspect, in the first aspect, the control device temporarily stops the power supply to the electric motor according to the hydraulic pressure applied to the piston when the holding of the braking force is started. Change the current threshold to make it. According to this second aspect, the power supply to the electric motor can be temporarily stopped at an appropriate current threshold value according to the hydraulic pressure. That is, the power supply can be temporarily stopped before the thrust becomes excessive. When it is necessary to restart the power supply based on the change in the vehicle state when the vehicle is temporarily stopped, the power supply can be restarted to prevent the thrust from becoming insufficient.

As a third aspect, in the first aspect, the holding completion condition is determined by the change in the hydraulic pressure applied to the piston as the vehicle state. According to this third aspect, the holding of the braking force can be completed under the holding completion condition corresponding to the change in the hydraulic pressure.

As a fourth aspect, in the third aspect, the holding completion condition is that the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. do. According to this fourth aspect, for example, the shortage of thrust can be suppressed by lengthening the power supply time after restarting the power supply as the hydraulic pressure changes significantly to the decompression side (the larger the decompression amount). In this case, even if the power supply is temporarily stopped in a state where the thrust is low in order to suppress the excessive thrust, it is possible to suppress the shortage of the thrust when the holding of the braking force is completed.

A fifth aspect is a brake control device having a control unit for controlling the electric motor in a brake mechanism that propels a piston by thrust or hydraulic pressure transmitted from the electric motor to press the braking member against the braked member. The control unit drives the electric motor in response to a control command for holding the braking force of the brake mechanism, and temporarily supplies electric power to the electric motor when a current rise in which a thrust is generated in the piston. After stopping, the power supply to the motor is restarted, and when the holding completion condition for completing the holding of the braking force is satisfied, the holding of the braking force is completed, and the power supply to the motor is temporarily stopped. At that time, the holding completion condition is determined based on the change in the vehicle state. According to this fifth aspect, it is possible to suppress excess / deficiency (excess / deficiency) of thrust due to a change in the vehicle state when the braking force is maintained based on the drive of the electric motor.

As a sixth aspect, in the fifth aspect, the control unit acquires the hydraulic pressure applied to the braking mechanism when the holding of the braking force is started, and the hydraulic pressure is applied according to the acquired hydraulic pressure. Set a current threshold to temporarily stop the power supply to the motor. According to this sixth aspect, the power supply to the electric motor can be temporarily stopped at an appropriate current threshold value according to the hydraulic pressure.

As a seventh aspect, in the fifth aspect, the control unit acquires the change in the hydraulic pressure applied to the piston as the vehicle state, and the holding completion condition is based on the change in the hydraulic pressure. To set. According to this seventh aspect, the holding of the braking force can be completed under the holding completion condition corresponding to the change in the hydraulic pressure.

As an eighth aspect, in the seventh aspect, the control unit increases the power supply time after the restart of the power supply as the amount of change in the hydraulic pressure while the power supply is temporarily stopped is large. As described above, the holding completion condition is set. According to this eighth aspect, it is possible to suppress a shortage of thrust when the holding of the braking force is completed.

A ninth aspect is a brake control method for controlling the motor in a brake mechanism in which a piston is propelled by a thrust or hydraulic pressure transmitted from the motor to press the braking member against the braked member. A step of starting the current supply to the motor according to a control command for holding the braking force, and a step of temporarily stopping the power supply to the motor when the current rises when a thrust is generated in the piston. And, after temporarily stopping the power supply to the motor, the step of restarting the power supply to the motor and the holding of the braking force are completed when the holding completion condition for completing the holding of the braking force is satisfied. The step includes a step of setting the holding completion condition based on a change in the vehicle state when the power supply to the electric motor is temporarily stopped. According to this ninth aspect, it is possible to suppress excess / deficiency (excess / deficiency) of thrust due to a change in the vehicle state when the braking force is maintained based on the drive of the electric motor.

As the tenth aspect, in the ninth aspect, when the current supply to the electric motor is started, the hydraulic pressure applied to the brake mechanism is acquired, and the hydraulic pressure applied to the electric motor is increased according to the acquired hydraulic pressure. Includes a step to set a current threshold for temporarily shutting down the power supply. According to this tenth aspect, the power supply to the electric motor can be temporarily stopped at an appropriate current threshold value according to the hydraulic pressure.

As the eleventh aspect, in the ninth aspect, as the vehicle state, a step of acquiring a change in the hydraulic pressure applied to the piston and setting the holding completion condition based on the change in the hydraulic pressure is performed. include. According to this eleventh aspect, the holding of the braking force can be completed under the holding completion condition corresponding to the change in the hydraulic pressure.

As a twelfth aspect, in the eleventh aspect, the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. Includes steps to set retention completion conditions. According to this twelfth aspect, it is possible to suppress a shortage of thrust when the holding of the braking force is completed.

A thirteenth aspect is a brake control program executed by a brake control device that controls the electric motor in a brake mechanism that propels the piston by thrust or hydraulic pressure transmitted from the electric motor to press the braking member against the braked member. Then, in the step of starting the current supply to the motor in response to the control command for holding the braking force of the brake mechanism, and when the current in which the thrust is generated in the piston rises, the power is supplied to the motor. When the step of temporarily stopping, the step of restarting the power supply to the motor after temporarily stopping the power supply to the motor, and the holding completion condition for completing the holding of the braking force are satisfied. The step of completing the holding of the braking force and the step of setting the holding completion condition based on the change in the vehicle state when the power supply to the electric motor is temporarily stopped are executed. According to this thirteenth aspect, it is possible to suppress excess or deficiency (excess or deficiency) of thrust due to a change in the vehicle state when the braking force is maintained based on the drive of the electric motor.

According to the fourteenth aspect, in the thirteenth aspect, when the current supply to the electric motor is started, the hydraulic pressure applied to the brake mechanism is acquired, and the hydraulic pressure applied to the electric motor is increased according to the acquired hydraulic pressure. This includes the step of setting a current threshold for temporarily stopping the power supply of the power supply. According to this fourteenth aspect, the power supply to the electric motor can be temporarily stopped at an appropriate current threshold value according to the hydraulic pressure.

As a fifteenth aspect, in the thirteenth aspect, there is a step of acquiring a change in the hydraulic pressure applied to the piston as the vehicle state and setting the holding completion condition based on the change in the hydraulic pressure. Include and execute. According to this fifteenth aspect, the holding of the braking force can be completed under the holding completion condition corresponding to the change in the hydraulic pressure.

As a sixteenth aspect, in the fifteenth aspect, the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. Execute including the step of setting the retention completion condition. According to this sixteenth aspect, it is possible to suppress a shortage of thrust when the holding of the braking force is completed.

4 Disc rotor (braked member)
6 Rear wheel side disc brake (brake mechanism)
6B caliper (hydraulic braking device)
6C Brake pad (braking member)
6D piston (hydraulic braking device)
7A electric motor (electric brake device, motor)
8 Rotational linear motion mechanism (electric brake device)
24 Parking brake control device (control device, brake control device)

Claims (16)

A hydraulic braking device that propels the piston by hydraulic pressure and presses the braking member against the braked member.
An electric braking device that propels the piston by the thrust transmitted from the motor to press the braking member against the braked member and holds the braking force.
When the braking force is held, the power supply to the motor is temporarily stopped in the section where the thrust is generated in the piston, and then the power supply to the motor is restarted to complete the holding of the braking force. It is equipped with a control device that completes the holding of braking force when the completion condition is satisfied.
The control device is a brake system, characterized in that, when the power supply is temporarily stopped, the holding completion condition is determined based on a change in the vehicle state. In the brake system according to claim 1,
The control device is characterized in that the current threshold value for temporarily stopping the power supply to the electric motor is changed according to the hydraulic pressure applied to the piston when the holding of the braking force is started. Brake system. In the brake system according to claim 1,
The brake system, characterized in that the holding completion condition is determined by a change in hydraulic pressure applied to the piston as the vehicle state. In the brake system according to claim 3,
The holding completion condition is a brake system characterized in that the larger the amount of change in hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply. A brake control device having a control unit for controlling the motor in a brake mechanism that propels a piston by thrust or hydraulic pressure transmitted from the motor to press the braking member against the braked member.
The control unit drives the electric motor in response to a control command for holding the braking force of the brake mechanism, and temporarily supplies electric power to the electric motor when a current rise in which a thrust is generated in the piston. After stopping, the power supply to the motor is restarted, and when the holding completion condition for completing the holding of the braking force is satisfied, the holding of the braking force is completed.
A brake control device that determines the holding completion condition based on a change in the vehicle state when the power supply to the electric motor is temporarily stopped. In the brake control device according to claim 5,
The control unit acquires the hydraulic pressure applied to the brake mechanism when the holding of the braking force is started, and temporarily stops the power supply to the electric motor according to the acquired hydraulic pressure. Brake control device that sets the current threshold. In the brake control device according to claim 5,
The control unit is a brake control device that acquires a change in hydraulic pressure applied to the piston as the vehicle state and sets the holding completion condition based on the change in hydraulic pressure. In the brake control device according to claim 7,
The control unit sets the holding completion condition so that the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply is performed. Device. A brake control method for controlling the motor in a brake mechanism that propels the piston by thrust or hydraulic pressure transmitted from the motor to press the braking member against the braked member.
A step of starting current supply to the motor in response to a control command for holding the braking force of the brake mechanism, and
A step of temporarily stopping the power supply to the motor when a current rise in which thrust is generated in the piston, and a step of temporarily stopping the power supply to the motor.
A step of temporarily stopping the power supply to the motor and then restarting the power supply to the motor.
A step to complete the holding of the braking force when the holding completion condition for completing the holding of the braking force is satisfied, and
A step of setting the holding completion condition based on a change in the vehicle state while the power supply to the motor is temporarily stopped, and a step of setting the holding completion condition.
Brake control methods, including. In the brake control method according to claim 9,
When the current supply to the motor is started, the hydraulic pressure applied to the brake mechanism is acquired, and the current threshold for temporarily stopping the power supply to the motor according to the acquired hydraulic pressure is set. Brake control method, including steps to set. In the brake control method according to claim 9,
A brake control method comprising a step of acquiring a change in hydraulic pressure applied to the piston as the vehicle state and setting the holding completion condition based on the change in hydraulic pressure. In the brake control method according to claim 11,
A brake control method including a step of setting a holding completion condition so that the larger the amount of change in hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after restarting the power supply. .. A brake control program executed by a brake control device that controls a motor in a brake mechanism that propels a piston by thrust or hydraulic pressure transmitted from the motor to press the braking member against the braked member.
A step of starting current supply to the motor in response to a control command for holding the braking force of the brake mechanism, and
A step of temporarily stopping the power supply to the motor when a current rise in which thrust is generated in the piston, and a step of temporarily stopping the power supply to the motor.
A step of temporarily stopping the power supply to the motor and then restarting the power supply to the motor.
A step to complete the holding of the braking force when the holding completion condition for completing the holding of the braking force is satisfied, and
A step of setting the holding completion condition based on a change in the vehicle state while the power supply to the motor is temporarily stopped, and a step of setting the holding completion condition.
Brake control program to run. In the brake control program according to claim 13,
When the current supply to the motor is started, the hydraulic pressure applied to the brake mechanism is acquired, and the current threshold for temporarily stopping the power supply to the motor according to the acquired hydraulic pressure is set. A brake control program that is executed including the steps to be set. In the brake control program according to claim 13,
A brake control program that includes and executes a step of acquiring a change in hydraulic pressure applied to the piston as the vehicle state and setting the holding completion condition based on the change in hydraulic pressure. In the brake control program according to claim 15,
The step of setting the holding completion condition is executed so that the larger the amount of change in the hydraulic pressure while the power supply is temporarily stopped, the longer the power supply time after the restart of the power supply is performed. Brake control program.

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