JP2007001497A - Brake control device and brake control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device and a brake fluid control method capable of suppressing a temperature rise of the brake fluid without accompanying with large sizing of a brake calliper and increase of unsprung weight. <P>SOLUTION: The brake control device is provided with a temperature sensor 19 for detecting a temperature of the brake fluid in a wheel cylinder 7a; a discharge route for connecting the wheel cylinder 7a and a reservoir tank 9 of a master cylinder 6; and a control unit 18 for performing brake fluid exchange control that the brake fluid stored in the reservoir tank 9 is replenished into the wheel cylinder 7a from a replenishing route separately provided from the discharge route and connecting the wheel cylinder 7a and the reservoir tank 9 after the brake fluid of the wheel cylinder 7a is discharged from the discharge rout to the reservoir tank 9 when the detected temperature T of the brake fluid is a high temperature determination threshold value Ts or higher. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to the technical field of a brake control device and a brake control method for suppressing a temperature rise of brake fluid.

In a conventional brake control device, a brake caliper is provided with a Peltier element, and frictional heat generated when the brake is operated is absorbed by the Peltier element and released into the atmosphere. The vapor lock accompanying generation | occurrence | production is prevented (for example, refer patent document 1).
JP-A-1-22657

  However, the above prior art has a problem in that the structure of the Peltier element provided in the brake caliper leads to an increase in the size of the brake caliper, and the degree of freedom in designing the axle and suspension arms adjacent to the brake caliper is reduced. . Moreover, the road surface followability of the tire deteriorates due to an increase in the unsprung load.

  The present invention has been made paying attention to the above-mentioned problem, and its object is to provide a brake control method and a brake control method capable of suppressing an increase in the temperature of the brake fluid without increasing the size of the brake caliper and increasing the unsprung load. A brake fluid control device is provided.

In order to achieve the above object, the present invention provides:
Brake fluid temperature detecting means for detecting the temperature of the brake fluid in the wheel cylinder;
A discharge path connecting the wheel cylinder and the reservoir tank of the master cylinder;
A replenishment path that is provided separately from the discharge path and connects the wheel cylinder and the reservoir tank;
When the detected temperature of the brake fluid is equal to or higher than a preset high temperature determination threshold, the brake fluid stored in the reservoir tank is discharged from the replenishment route after the brake fluid in the wheel cylinder is discharged to the discharge route. Brake control means for performing brake fluid replacement control for replenishing the wheel cylinder;
It is characterized by providing.

  In the present invention, the brake fluid that has become hot in the wheel cylinder is replaced with low-temperature brake fluid stored in the reservoir tank by using a discharge path and a replenishment path provided separately from the discharge path. The temperature rise of the brake fluid in the wheel cylinder is suppressed. Therefore, it is possible to suppress the occurrence of vapor lock accompanying the increase in the temperature of the brake fluid without increasing the size of the brake caliper and increasing the unsprung load.

  Hereinafter, the best mode for carrying out the present invention will be described based on the first embodiment.

First, the configuration will be described.
FIG. 1 is a diagram illustrating a configuration of a brake circuit and a control system of a vehicle to which the brake control device of the first embodiment is applied. In the vehicle of the first embodiment, the slip state between the tire and the road surface is monitored, and the braking force is mainly controlled among the tire forces so as to obtain the highest braking force during braking (avoids locking of wheels). ABS control to control, TCS control to control the torque to be transmitted to the road surface most efficiently when driving force is output at the time of starting, etc. It is equipped with ABS / TCS / VDC control system that performs VDC control to control oversteering and understeering and to obtain the desired vehicle behavior (by giving independent braking force to each wheel) .

  The brake circuit in FIG. 1 shows one system of X-type brake piping. This X-type brake pipe is divided into two systems for supplying brake fluid as fluid to the wheel cylinder 7a of the four-wheel caliper 7, and the right front wheel and the left rear wheel are connected by these two systems. It is a pipe that connects the left front wheel and the right rear wheel.

  The caliper 7 includes a wheel cylinder 7a, a brake pad 7b, and a piston 7c. The piston 7c moves in the axial direction in the wheel cylinder 7a. The brake pad 7b is provided separately from the piston 7c, and is elastically supported by the body of the caliper 7 in contact with the brake rotor 7d by the brake shim 7e.

  The piston 7c is separated from the brake pad 7b when the amount of brake fluid supplied to the wheel cylinder 7a is equal to or less than a predetermined value. When the amount of brake fluid supplied to the wheel cylinder 7a exceeds a predetermined value, a stroke is made toward the brake pad 7b, and the brake pad 7b is pressed toward the brake rotor 7d. Thereby, the braking force according to a piston stroke is provided to a wheel.

The brake circuit according to the first embodiment includes a brake circuit 1, a drain circuit 2, a suction circuit 3, a discharge circuit 4, and a supply circuit 5.
The brake circuit 1 is a circuit that connects the master cylinder 6 and the wheel cylinder 7a, and supplies brake fluid pressure from the reservoir tank 9 to the wheel cylinder 7a according to the operation amount (depression amount) of the brake pedal 8 of the driver. In the brake circuit 1, a normally open shut-off valve 10 that shuts off the brake circuit 1 is provided upstream (on the master cylinder 6 side) across the branch point 1a with the discharge circuit 4, and on the downstream (wheel cylinder 7a side). Is provided with a normally open pressure increasing valve 11 for increasing the hydraulic pressure of the wheel cylinder 7a.

  The drain circuit 2 is a circuit that connects the wheel cylinder 7a and the reservoir (decompression reservoir) 12. In the drain circuit 2, downstream of the reservoir 12, the normally closed pressure reducing valve that reduces the hydraulic pressure of the wheel cylinder 7a. 13 is provided. In the reservoir 12, the piston is urged by a spring so as to send out the stored brake fluid.

  The suction circuit 3 is a circuit that connects the reservoir 12 and the pump 14, and allows a flow of brake fluid from the drain circuit 2 to the discharge circuit 4 and checks to prevent a brake fluid flow from the discharge circuit 4 to the drain circuit 2. A valve (one-way valve) 15 is provided. The pump 14 is a return pump when the ABS control is executed, and serves as an auxiliary hydraulic pressure source during the brake assist control. For example, a plunger that is operated by an electric motor is used.

  The discharge circuit 4 is a circuit that connects the pump 14 and the brake circuit 1 and is a check valve that allows the flow of brake fluid from the pump 14 to the brake circuit 1 and blocks the flow of brake fluid from the brake circuit 1 to the pump 14. 16 is provided. The replenishment circuit 5 is a circuit connecting the reservoir tank 9 and the suction circuit 3, and is provided with a normally closed suction (suction) valve 17 for sending brake fluid stored in the reservoir tank 9 to the pump 14.

  The control unit (brake control means) 18 includes a temperature sensor (brake fluid temperature detection means) 19 for detecting the temperature of the brake pad 7b of the caliper 7, and a master cylinder pressure sensor (brake operation detection for detecting the fluid pressure of the master cylinder 6). Means) 20, accelerator opening sensor (accelerator pedal operation detecting means) 21, vehicle speed sensor 22, vehicle behavior sensor 23 for detecting vehicle behavior state quantities such as yaw rate and lateral G, inhibitor switch 24, and capacity of reservoir 12 are detected. Signals from a tank capacity sensor (brake fluid detection means) 25 and a laser radar (preceding vehicle detection means) 26 for detecting a preceding vehicle are input. As the vehicle behavior state quantity, a value estimated from the steering wheel steering angle and the vehicle speed may be used.

  The control unit 18 performs the above-described ABS / TCS / VDC control by controlling the operations of the valves 10, 11, 13, 17 and the pump 14 based on the sensor signals. In addition, about the control method, the method as described in Unexamined-Japanese-Patent No. 11-115714, Unexamined-Japanese-Patent No. 2001-18776 etc. can be used, for example.

  Further, the control unit 18 estimates the temperature of the brake fluid in the wheel cylinder 7a from the temperature of the brake pad 7b. If the temperature of the brake fluid is equal to or higher than a preset high temperature determination threshold, the control unit 18 depends on the temperature of the brake fluid. After the brake fluid in the wheel cylinder 7a is discharged to the reservoir tank 9, the brake fluid replacement control for replenishing the brake fluid stored in the reservoir tank 9 from the replenishment circuit 5 into the wheel cylinder 7a is performed. Here, the high temperature determination threshold is set to a temperature that has a margin with respect to the vapor lock, that is, a temperature lower than a temperature at which bubbles are generated in the brake fluid. Further, the amount of replacement of the brake fluid is an amount corresponding to the amount of brake fluid discharged.

Next, the operation will be described.
[Foil cylinder brake fluid replacement]
In the brake fluid replacement control, when the brake fluid in the wheel cylinder 7a is discharged to the reservoir tank 9, in the brake circuit of FIG. 1, the shutoff valve 10 is opened, the pressure increasing valve 11 is closed, the pressure reducing valve 13 is opened, and suction is performed. The valve 17 is closed and the pump 14 is driven. At this time, as shown in FIG. 2, the brake fluid in the wheel cylinder 7a flows from the brake circuit 1, the drain circuit 2, the suction circuit 3, the pump 14, the discharge circuit 4, the brake circuit 1, and the master cylinder 6 to the reservoir. It is discharged into the tank 9.

  Further, the piston 7c moves from the position of the solid line in FIG. 2 to the position of the broken line, and is separated from the brake pad 7b elastically supported by the brake shim 7e. Thereby, it is avoided that the heat of the brake rotor 7d is transmitted to the wheel cylinder 7a via the piston 7c.

  When the brake fluid is supplied from the reservoir tank 9 into the wheel cylinder 7a after the brake fluid is completely discharged, the shutoff valve 10 is closed and the pressure increasing valve 11 is opened from the state shown in FIG. 2 (FIG. 3). As a result, the brake fluid in the reservoir tank 9 flows from the replenishment circuit 5, the suction circuit 3, the pump 14, the discharge circuit 4, the brake circuit 1, and the brake fluid is replenished in the wheel cylinder 7a. Further, the piston 7c returns from the position of the solid line in FIG. 3 to the position of the broken line (the position of the solid line in FIG. 2).

  That is, in the first embodiment, the brake fluid discharge path from the wheel cylinder 7a to the reservoir tank 9 (wheel cylinder 7a → brake circuit 1 → drain circuit 2 → suction circuit 3 → pump 14 → discharge circuit 4 → brake circuit 1 → master cylinder 6 → reservoir tank 9) and brake fluid replenishment path from reservoir tank 9 to wheel cylinder 7a (reservoir tank 9 → replenishment circuit 5 → suction circuit 3 → pump 14 → discharge circuit 4 → brake circuit 1 → foil cylinder 7a) Is provided separately. Thereby, it is possible to suppress the high-temperature brake fluid discharged from the wheel cylinder 7a from returning to the wheel cylinder 7a again.

[Brake fluid replacement control process]
4-6 is a flowchart which shows the flow of the brake fluid replacement | exchange control processing performed with the control unit 18 of Example 1, and demonstrates each step hereafter.

  First, in FIG. 4, in step S1, the temperature T of the brake pad 7b is read from the signal of the temperature sensor 19, and the process proceeds to step S2.

  In step S2, the master cylinder pressure Pm is read, and the process proceeds to step S3 from the signal of the master cylinder pressure sensor 20.

  In step S3, the accelerator opening As is read from the signal of the accelerator opening sensor 21, and the process proceeds to step S4.

  In step S4, the shift range Sp is read from the signal of the inhibitor switch 24, and the process proceeds to step S5.

  In step S5, the vehicle speed V is read from the signal from the vehicle speed sensor 22, and the process proceeds to step S6.

  In step S6, it is determined whether or not the temperature T of the brake pad 7b read in step S1 is equal to or higher than the high temperature determination threshold value Ts. If YES, the process proceeds to step S7. If NO, the process proceeds to return.

  In step S7, it is determined from the signal from the tank capacity sensor 25 whether or not the reservoir 12 is empty. If YES, the process proceeds to step S8, and if NO, the process proceeds to return.

  In step S8, it is determined whether or not the vehicle speed V read in step S5 is zero, that is, whether or not the vehicle is stopped (corresponding to vehicle stop determination means). If YES, the process proceeds to step S12 (FIG. 5). If NO, the process proceeds to step S9.

  In step S9, it is determined whether or not the master cylinder pressure Pm read in step S2 is zero, that is, whether or not non-braking is being performed. If YES, the process proceeds to step S10. If NO, the process proceeds to step S12.

  In step S10, it is determined from the accelerator opening degree As read in step S3 whether or not the accelerator is being operated. If YES, the process proceeds to step S12. If NO, the process proceeds to return.

  In step S11, it is determined from the signal of the laser radar 26 whether the preceding vehicle is not within a predetermined distance. If YES, the process proceeds to step S12. If NO, the process proceeds to return.

  In step S12, the brake fluid discharge amount Qd is calculated, and the process proceeds to step S13. Here, the brake fluid discharge amount Qd is increased as the temperature T of the brake pad 7b detected in step S2 is higher.

  In step S13, it is determined whether or not the shift range Sp read in step S4 is the P range (creep state detection means). If YES, the process proceeds to step S14, and if NO, the process proceeds to S21 (FIG. 6). Here, the creep state refers to a state in which the vehicle starts to run when the engine idling acts on the torque converter and the driver does not perform a brake operation.

  In step S14, it is determined whether or not the fluid discharge completion flag Qdf is set (= 1), that is, whether or not the brake fluid discharge is completed. If YES, the process proceeds to step S18. If NO, the process proceeds to step S15.

  In step S15, it is determined whether or not the brake fluid discharge amount Qd has reached the specified discharge amount Qds. If YES, the process proceeds to step S16, and if NO, the process proceeds to step S17.

  In step S16, the liquid discharge completion flag Qdf is set, and the process proceeds to return.

  In step S17, the brake fluid in the caliper is discharged, and the process proceeds to return.

  In step S18, it is determined whether or not the brake fluid discharge amount Qd is zero, that is, whether or not the brake fluid supply has been completed. If YES, the process proceeds to step S20. If NO, the process proceeds to step S19.

  In step S19, the brake fluid in the caliper is replenished, and the process proceeds to return.

  In step S20, the liquid discharge completion flag Qdf is reset (= 0), and the process proceeds to return.

  In step S21, the right front / left rear wheel fluid supply completion flag QaX is read, and the process proceeds to step S22.

  In step S22, it is determined whether the right front / left rear wheel fluid replenishment completion flag QaX read in step S21 is set, that is, whether the brake fluid replenishment of the right front / left rear wheel is completed. If yes, then continue with S31, otherwise continue with step S23.

  In step S23, the right front / left rear wheel fluid discharge completion flag Qdfa is read, and the process proceeds to step S24.

  In step S24, it is determined whether the right front / left rear wheel fluid discharge completion flag Qdfa read in step S23 is set, that is, whether right front / left rear wheel fluid discharge is completed. If YES, the process proceeds to step S28, and if NO, the process proceeds to step S25.

  In step S25, it is determined whether or not the liquid discharge amount Qd has reached the diagonal wheel specified discharge amount QdsX. If YES, the process proceeds to step S26, and if NO, the process proceeds to step S27.

  In step S26, the right front / left rear wheel fluid discharge completion flag Qdfa is set, and the routine proceeds to return.

  In step S27, the brake fluid in the right front and left rear calipers is discharged, and the process proceeds to return.

  In step S28, it is determined whether or not the fluid discharge amount Qd is zero, that is, whether or not the brake fluid supply has been completed. If YES, the process proceeds to step S30, and if NO, the process proceeds to step S29.

  In step S29, the brake fluid is replenished into the right front and left rear calipers, and the process proceeds to return.

  In step S30, the right front / left rear wheel fluid replenishment completion flag QaX is set, and the routine proceeds to return.

  In step S31, the left front / right rear wheel fluid discharge completion flag Qdfb is read, and the process proceeds to step S32.

  In step S32, it is determined whether the left front / right rear wheel fluid discharge completion flag Qdfb read in step S31 is set, that is, whether the brake fluid discharge to the left front / right rear wheel is completed. If YES, the process proceeds to step S36, and if NO, the process proceeds to step S33.

  In step S33, it is determined whether or not the liquid discharge amount Qd has reached the diagonal wheel specified discharge amount QdsX. If YES, the process moves to step S34, and if NO, the process moves to step S35.

  In step S34, the front left / right rear wheel fluid discharge completion flag Qdfb is set, and the routine proceeds to return.

  In step S35, the brake fluid in the left front and right rear wheel calipers is discharged, and the process proceeds to return.

  In step S36, it is determined whether or not the fluid discharge amount Qd is zero, that is, whether or not the brake fluid supply has been completed. If YES, the process moves to step S38, and if NO, the process moves to step S37.

  In step S37, the brake fluid is replenished into the left front and right rear calipers, and the process proceeds to return.

  In step S38, the right front / left rear wheel fluid discharge completion flag Qdfa and the left front / right rear wheel fluid discharge completion flag Qdfb are cleared, and the process proceeds to step S39.

  In step S39, the right front / left rear wheel fluid replenishment completion flag QaX is cleared, and the process proceeds to return.

[Brake fluid replacement control processing operation]
1. When the vehicle is stopped When it is determined that there is a brake temperature increasing wheel while the vehicle is stopped, if the shift range is the P range, steps S1 → step S2 → step S3 → step in the flowcharts of FIGS. Step S5 → Step S5 → Step S6 → Step S7 → Step S8 → Step S12 → Step S13 → Step S14 → Step S15 → Step S17 and the wheel cylinder 7a until the brake fluid discharge amount reaches the specified discharge amount Qds. The brake fluid is discharged.

  When the brake fluid discharge amount reaches the specified discharge amount Qds, step S1 → step S2 → step S3 → step S4 → step S5 → step S6 → step S7 → step S8 → step S12 → step S13 → step S14 → Proceeding from step S18 to step S19, the brake fluid is supplied into the wheel cylinder 7a until the brake fluid discharge amount Qd becomes zero.

2. When the vehicle is running If it is determined that there is a brake temperature rising wheel while the vehicle is running, if the driver is operating the accelerator, no preceding vehicle is detected in front of the vehicle, and it is not immediately after the execution of ABS control, step S1 → Step S2 → Step S3 → Step S4 → Step S5 → Step S6 → Step S7 Step S8 → Step S9 → Step S10 → Step S11 → Step S12 → Step S13 → Step S21 → Step S22 → Step S23 → Step S24 → Step S25 → Proceed to step S27, and the brake fluid discharge in the right front and left rear wheel wheel cylinders 7a is executed until the brake fluid discharge amount Qd of the right front and left rear wheels reaches the specified diagonal wheel discharge amount QdsX. .

  When the brake fluid discharge amount Qd for the right front and left rear wheels reaches the specified diagonal wheel discharge amount QdsX, Step S1 → Step S2 → Step S3 → Step S4 → Step S5 → Step S6 → Step S7 → Step S8 → Step S9 → Step S10 → Step S11 → Step S12 → Step S13 → Step S21 → Step S22 → Step S23 → Step S24 → Step S28 → Go to Step S29 until the brake fluid discharge Qd reaches zero -Brake fluid is replenished in the wheel cylinder 7a of the left rear wheel.

  When the right front and left rear wheel brake fluid supply is completed, step S1, step S2, step S3, step S4, step 5, step S7, step S8, step S9, step S10, step S11, step S12, and so on. Step S13-> Step S21-> Step S22-> Step S31-> Step S32-> Step S33-> Step S35 and go to the left front until the brake fluid discharge amount Qd for the left front wheel and the right rear wheel reaches the specified diagonal wheel discharge amount QdsX -Brake fluid discharge in the wheel cylinder 7a of the right rear wheel is executed.

  When the brake fluid discharge amount Qd of the left front wheel and the right rear wheel reaches the specified diagonal wheel discharge amount QdsX, step S1 → step S2 → step S3 → step S4 → step 5 → step S7 → step S8 → step S9 → Step S10 → Step S11 → Step S12 → Step S13 → Step S21 → Step S22 → Step S31 → Step S32 → Step S36 → Step S37, the front left and the rear right until the brake fluid discharge Qd becomes zero The brake fluid is supplied into the wheel cylinder 7a.

[Brake fluid replacement when the vehicle is stopped]
In the first embodiment, when the vehicle is stopped and the shift range is not the P range, or when the driver is operating the brake while driving at an extremely low speed, if it is determined that there is a brake temperature rising wheel, the right front After replacing the brake fluid in the left rear wheel wheel cylinder 7a, the brake fluid in the left front wheel wheel cylinder 7a is replaced.

  That is, if the brake fluid of each wheel is replaced in the creep state, the vehicle may start with a decrease in braking force. Therefore, the brake fluid is replaced by shifting the brake fluid by two wheels. While performing the replacement control, a braking force capable of maintaining the stop can be secured.

[Brake fluid replacement during vehicle travel]
In the first embodiment, the brake fluid replacement control is performed only when the accelerator pedal is operated and the brake pedal 8 is not operated and when there is no preceding vehicle. Normally, the driver does not perform the accelerator operation and the brake operation at the same time. When performing the brake operation, the driver depresses the brake pedal 8 with his / her foot removed from the accelerator pedal. Further, when there is a preceding vehicle, the driver is likely to perform a brake operation. Therefore, the brake fluid replacement control is performed only when it is predicted that the driver does not perform the brake operation, so that the response of the braking force generation due to the invalid stroke until the force of the piston 7c is transmitted to the brake rotor 7d via the brake pad 7b. Delay can be avoided.

[Brake fluid replacement prohibited immediately after ABS control]
The reservoir 12 temporarily stores high-temperature brake fluid drawn from the wheel cylinder 7a during the ABS control pressure reduction control, and is gradually discharged after the pressure reduction control. Therefore, when the brake fluid replacement control is performed in a state where the brake fluid is stored in the reservoir 12, the high-temperature brake fluid stored in the reservoir 12 is supplied to the wheel cylinder 7a. In the first embodiment, when the brake fluid is stored in the reservoir 12, the replacement of the brake fluid is prohibited, thereby preventing the responsiveness of the braking force from being lowered due to the unnecessary replacement of the brake fluid.

Next, the effect will be described.
In the brake control device according to the first embodiment, the following effects can be obtained.

  (1) A temperature sensor 19 for detecting the temperature of the brake fluid in the wheel cylinder 7a and a discharge path (the wheel cylinder 7a → the brake circuit 1 → the drain circuit 2 → the suction circuit) connecting the wheel cylinder 7a and the reservoir 9 of the master cylinder 6 3 → pump 14 → discharge circuit 4 → brake circuit 1 → master cylinder 6 → reservoir tank 9) and when the detected temperature T of the brake fluid is equal to or higher than a preset high temperature determination threshold value Ts, the brake fluid in the wheel cylinder 7a Is discharged from the discharge path to the reservoir tank 9, and the brake fluid stored in the reservoir tank 9 is supplied to the supply path (reservoir tank 9 → supply circuit 5 → suction circuit 3 → pump 14 → discharge circuit 4 → brake circuit 1 → foil. A control unit 18 for controlling the brake fluid replacement to be supplied from the cylinder 7a) into the wheel cylinder 7a. , Comprising a. Thereby, the temperature rise of a brake fluid can be suppressed, without causing the caliper 7 to enlarge.

  (2) Since the control unit 18 increases the brake fluid discharge amount Qd as the detected brake fluid temperature T increases, the control unit 18 can suppress the occurrence of vapor lock regardless of the brake fluid temperature T.

  (3) An accelerator opening sensor 21 that detects the presence / absence of an accelerator operation by the driver and a master cylinder pressure sensor 20 that detects the presence / absence of a brake operation are provided. The control unit 18 operates an accelerator pedal and applies a brake. When not in operation, brake fluid replacement control is performed. Thereby, the response delay of the braking force accompanying brake fluid replacement control can be avoided.

  (4) A laser radar 26 for detecting the presence of a preceding vehicle ahead of the host vehicle is provided, and the control unit 18 performs brake fluid replacement control when there is no preceding vehicle ahead of the host vehicle. That is, when there is a possibility that the brake operation may be performed due to deceleration of the preceding vehicle or the like, the brake fluid replacement control is not performed, so that a response delay of the braking force accompanying the brake fluid replacement control can be avoided.

  (5) A reservoir 12 for storing brake fluid during the pressure reduction control of ABS control and a tank capacity sensor 25 for detecting the presence or absence of the brake fluid in the reservoir 12 are provided. The control unit 18 has a brake fluid in the reservoir 12. When it is not stored, brake fluid replacement control is performed. That is, when the brake fluid temperature rise suppressing effect cannot be expected, it is possible to reduce a decrease in the response of the braking force by prohibiting the replacement of the brake fluid.

  (6) Vehicle stop reversing means (step S8) for determining vehicle stop and creep state detecting means (step S13) for detecting the creep state are provided, and the control unit 18 controls the right front and left rear wheels in the creep state. Since the brake fluid for the left front and right rear wheels is replaced after the brake fluid is replaced, the vehicle can be prevented from moving forward with the brake fluid replacement control, and the stopped state can be maintained.

(Other examples)
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment and does not depart from the gist of the present invention. Any change in the design of the range is included in the present invention.

  For example, as the brake pad temperature increases, the brake fluid discharge amount can be further increased by increasing the discharge time, increasing the supply time, increasing the discharge speed, increasing the supply speed, etc. It may be used.

  In addition, the brake circuit is not limited to the configuration shown in FIG. 1, and a discharge path for discharging brake fluid in the wheel cylinder to the reservoir tank and a supply path for supplying brake fluid from the reservoir tank to the wheel cylinder are different systems. The circuit configuration provided in (1) may be used.

  In the first embodiment, an example is shown in which X-type brake pipes that connect the right front wheel and the left rear wheel, and the left front wheel and the right front wheel, respectively, and the brake fluid is alternately replaced in the creep state. Any configuration that does not perform the brake fluid replacement control at the same time may be used.

It is a figure which shows the structure of the brake circuit of the vehicle to which the brake control apparatus of Example 1 is applied, and its control system. It is a figure which shows the operating state of each valve when discharging brake fluid from a wheel cylinder. It is a figure which shows the operating state of each valve when supplying brake fluid to a wheel cylinder. 3 is a flowchart showing a flow of a brake fluid replacement control process executed by a control unit 18 according to the first embodiment. 3 is a flowchart showing a flow of a brake fluid replacement control process executed by a control unit 18 according to the first embodiment. 3 is a flowchart showing a flow of a brake fluid replacement control process executed by a control unit 18 according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brake circuit 2 Drain circuit 3 Suction circuit 4 Discharge circuit 5 Replenishment circuit 6 Master cylinder 7a Wheel cylinder 7b Brake pad 7c Piston 7d Brake rotor 7e Brake shim 8 Brake pedal 9 Reservoir tank 10 Shut-off valve 11 Booster valve 12 Reservoir 13 Pressure-reducing valve 14 Pumps 15 and 16 Check valve 17 Suction valve 18 Control unit 19 Temperature sensor 20 Master cylinder pressure sensor 21 Accelerator opening sensor 22 Vehicle speed sensor 23 Vehicle behavior sensor 24 Inhibitor switch 25 Tank capacity sensor 26 Laser radar

Claims (7)

Brake fluid temperature detecting means for detecting the temperature of the brake fluid in the wheel cylinder;
A discharge path connecting the wheel cylinder and the reservoir tank of the master cylinder;
A replenishment path that is provided separately from the discharge path and connects the wheel cylinder and the reservoir tank;
When the detected temperature of the brake fluid is equal to or higher than a preset high temperature determination threshold, the brake fluid stored in the reservoir tank is discharged from the replenishment route after the brake fluid in the wheel cylinder is discharged to the discharge route. Brake control means for performing brake fluid replacement control for replenishing the wheel cylinder;
A brake control device comprising: The brake control device according to claim 1,
The brake control device, wherein the brake control unit increases the replacement amount of the brake fluid as the detected temperature of the brake fluid is higher. In the brake control device according to claim 1 or 2,
An accelerator pedal operation detecting means for detecting the presence or absence of the driver's accelerator operation;
Brake operation detecting means for detecting presence or absence of brake operation;
With
The brake control device according to claim 1, wherein the brake control means performs the brake fluid replacement control when an accelerator pedal is operated and a brake is not operated. The brake control device according to any one of claims 1 to 3,
A preceding vehicle detection means for detecting the presence or absence of a preceding vehicle ahead of the host vehicle;
The brake control device, wherein the brake control unit performs the brake fluid replacement control when there is no preceding vehicle ahead of the host vehicle. In the brake control device according to any one of claims 1 to 4,
A reservoir for decompression that stores brake fluid during decompression control of ABS control;
Brake fluid detection means for detecting the presence or absence of brake fluid in the decompression reservoir;
With
The brake control device according to claim 1, wherein the brake control means performs the brake fluid replacement control when no brake fluid is stored in the pressure reducing reservoir. In the brake control device according to any one of claims 1 to 4,
Vehicle stop determination means for determining vehicle stop;
A creep state detecting means for detecting a creep state;
With
The brake control device according to claim 1, wherein the brake control means does not permit brake fluid replacement control of at least one wheel when the vehicle is stopped and in a creep state. Detecting the temperature of the brake fluid in the wheel cylinder;
When the detected brake fluid temperature is equal to or higher than a preset high temperature judgment threshold, the brake fluid in the wheel cylinder is discharged from the discharge path connecting the wheel cylinder and the reservoir tank of the master cylinder to the reservoir tank. When,
Replenishing brake fluid in the reservoir tank into the wheel cylinder from a replenishment path that is provided separately from the discharge path and connects the wheel cylinder and the reservoir tank;
A brake control method comprising:

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