Brake control device

Abstract

Provided is a brake control device that makes it possible to improve redundancy of brake control when a sensor fails. A first hydraulic unit has a first control part that generates a braking request on the basis of the state quantity of a brake operator detected by a first sensor, and a second hydraulic unit has a second control part that generates a braking request on the basis of the state quantity of the brake operator detected by a second sensor.

Description

Brake control device

[0001] The present invention relates to a brake control device.

[0002] In the brake control device described in Patent Document 1, a pedal stroke sensor is connected to an electronic control unit provided in a downstream hydraulic unit.

[0003] Japanese Patent Application Publication No. 2023-39868

[0004] However, in the above-mentioned Japanese Patent Application Laid-Open No. 2023-39868, since the pedal stroke sensor does not have redundancy, there is a risk that brake control may not be performed appropriately in the event of a sensor failure. One object of the present invention is to provide a brake control device that can improve the redundancy of brake control in the event of a sensor failure.

[0005] In one embodiment of the brake control device, the first hydraulic unit has a first control unit that generates a braking request based on the state quantity of the brake operator detected by the first sensor, and the second hydraulic unit has a second control unit that generates a braking request based on the state quantity of the brake operator detected by the second sensor.

[0006] Therefore, in one embodiment of the present invention, it is possible to improve the redundancy of brake control in the event of a sensor failure.

[0007] 1 is an overall configuration diagram of a hydraulic pressure control device 1 according to a first embodiment; FIG. 2 is an overall configuration diagram of a hydraulic pressure control device 101 according to a second embodiment;

[0008] [Embodiment 1] Fig. 1 is an overall configuration diagram of a hydraulic pressure control device 1 of embodiment 1. The hydraulic pressure control device 1 is a system intended for application mainly to autonomous vehicles of Level 4 or higher, and constitutes a brake device mounted on the vehicle. The brake device of embodiment 1 employs a so-called brake-by-wire system in which the wheel cylinder 2 and the brake pedal 25 are mechanically separated.

[0009] In each part of FIG. 1 , the suffix P at the end of a reference number indicates that the part corresponds to the primary system (P system) of the wheel cylinder 2. The suffix S at the end of a reference number indicates that the part corresponds to the secondary system (S system) of the wheel cylinder 2. Hereinafter, when there is no distinction between the P and S systems, the P and S will be omitted. The suffix a at the end of a reference number indicates that the part corresponds to the left front wheel FL. Similarly, the suffix b at the end of a reference number indicates that the part corresponds to the right front wheel FR, the suffix c at the end of a reference number indicates that the part corresponds to the left rear wheel RL, and the suffix d at the end of a reference number indicates that the part corresponds to the right rear wheel RR. When there is no distinction between the individual wheels FL to RR, the suffix a to d will be omitted. The suffix f at the end of a reference number indicates that the part corresponds to the front wheels FL / FR, and the suffix r at the end of a reference number indicates that the part corresponds to the rear wheels RL / RR. When there is no distinction between the front and rear wheels, the suffix f and r will be omitted.

[0010] The hydraulic pressure control device 1 generates brake hydraulic pressure (wheel cylinder hydraulic pressure) in the wheel cylinders 2, thereby pressing the brake pads provided on each of the wheels FL to RR against brake discs provided on the wheels, thereby applying braking force to each of the wheels FL to RR. The hydraulic pressure control device 1 includes a first hydraulic pressure unit 3P and a second hydraulic pressure unit 3S. The first hydraulic pressure unit 3P and the second hydraulic pressure unit 3S are units in which a pump 4, a solenoid in valve 5, a supply valve 6, a solenoid out valve 7, and an ECU 8 are integrally provided.

[0011] The first hydraulic pressure unit 3P and the second hydraulic pressure unit 3S each have a suction port 9 and a wheel cylinder port 10. The suction port 9 is connected to a reservoir tank 12 via a suction hose 11. The reservoir tank 12 is a brake fluid source that stores brake fluid and is a low-pressure section that is open to the atmosphere. The reservoir tank 12 is divided into two compartments: a primary fluid chamber 12P and a secondary fluid chamber 12S. The primary fluid chamber 12P is connected to the first hydraulic pressure unit 3P, and the secondary fluid chamber 12S is connected to the second hydraulic pressure unit 3S.

[0012] The wheel cylinder ports 10 are connected to the wheel cylinders 2 via wheel cylinder piping 13. In the first embodiment, a so-called X-piping configuration is adopted, in which the P system is connected to the wheel cylinders 2a, 2d of the left front wheel and the right rear wheel, and the S system is connected to the wheel cylinders 2b, 2c of the right front wheel and the left rear wheel. The wheel cylinder ports 10 are connected to a supply valve 6 via a supply fluid path 14. The supply valve 6 is a normally closed on / off valve.

[0013] The suction side of pump 4 is connected to suction port 9 via suction fluid path 15. Pump 4 is composed of five plunger pumps driven by motor 16. The discharge side of pump 4 is connected to gate-in valve 5 via discharge fluid path 17. Gate-in valve 5 is a normally open solenoid valve. Gate-in valve 5 is connected to supply valve 6 via connecting fluid path 18. Gate-in valve 5 is also connected to gate-out valve 7 via connecting fluid path 19.

[0014] The gate-out valve 7 is a normally open solenoid valve. The gate-out valve 7 is connected to the suction port 9 via a drain pressure fluid line 20. A fluid pressure sensor 21 for detecting the wheel cylinder fluid pressure is provided in the supply fluid line 14. In addition, a fluid pressure sensor 22 for detecting the discharge pressure of the pump 4 is provided in the discharge fluid line 17.

[0015] The ECU 8 is an electronic control unit that controls the operation of the hydraulic unit 3, and drives and controls each actuator (the pump 4 and each valve 5 to 7) based on a signal from a pedal stroke sensor 23 and a request from another on-vehicle controller 24. The pedal stroke sensor 23 detects the amount of operation (pedal stroke) of the brake pedal 25. The hydraulic control device 1 of the first embodiment has redundant pedal stroke sensors 23. The first pedal stroke sensor 23P is connected to the first ECU 8P, and the second pedal stroke sensor 23S is connected to the second ECU 8S.

[0016] The first ECU 8P generates a brake request in response to the pedal stroke detected by the first pedal stroke sensor 23P. The first ECU 8P calculates target wheel cylinder hydraulic pressures to realize the generated brake request, determines brake commands (command values ​​to each actuator) to obtain the target wheel cylinder hydraulic pressures, and controls each actuator of the P system. The second ECU 8S generates a brake request in response to the pedal stroke detected by the second pedal stroke sensor 23S. The second ECU 8S calculates target wheel cylinder hydraulic pressures to realize the generated brake request, determines brake commands to obtain the target wheel cylinder hydraulic pressures, and controls each actuator of the S system.

[0017] The brake pedal 25 is connected to a reaction force generator 26. The reaction force generator 26 generates a reaction force on the brake pedal 25 when the driver steps on the brake pedal 25. Any mechanism can be used to generate the reaction force, and a spring or an actuator such as a motor may be used. By connecting the reaction force generator 26 to the brake pedal 25, the number of parts (hydraulic components) other than the brake pedal 25 can be reduced, thereby improving collision safety.

[0018] Next, the effects of the first embodiment will be described. Recently, brake-by-wire systems have been adopted more and more in response to demands for autonomous driving and the like, and there is a demand for electric pedals that are simpler, less expensive, and offer higher collision safety. In conventional brake-by-wire systems, a brake pedal is provided with a status sensor and an upstream ECU that calculates a brake request based on the sensor value. A final brake command is calculated by another downstream ECU provided downstream of the upstream ECU, which controls each brake. Therefore, if the upstream ECU fails, the brake request cannot be sent to the downstream ECU, and there is a risk that brake control will not be performed appropriately.

[0019] In contrast, in the hydraulic pressure control device 1 of the first embodiment, two pedal stroke sensors 23P, 23S are provided on the brake pedal 25. The sensor output values ​​are input to the ECUs 8P, 8S provided in the downstream hydraulic units 3P, 3S, which then calculate the brake request and brake command to control the brakes. In other words, by providing redundancy for the pedal stroke sensor 23, the redundancy of brake control can be improved in the event of a sensor failure. Furthermore, by calculating the brake request and brake command in the ECUs 8P, 8S downstream of the brake pedal 25, costs can be reduced by reducing the number of upstream ECUs, and a situation in which brake control becomes impossible due to a failure of an upstream ECU can be avoided. Furthermore, because the first pedal stroke sensor 23P is connected to the first ECU 8P and the second pedal stroke sensor 23S is connected to the second ECU 8S, even if one of them fails, brake control can be continued by the other. In addition, each of the ECUs 8P and 8S can be equipped with a low-cost CPU with a slow calculation speed, which contributes to cost reduction.

[0020] [Embodiment 2] The basic configuration of embodiment 2 is the same as embodiment 1, so only the differences from embodiment 1 will be described. Figure 2 is an overall configuration diagram of a hydraulic control device 101 of embodiment 2. The first hydraulic unit 3P and the second hydraulic unit 3S have unit connection ports 27. The unit connection ports 27 are connected to unit connection pipes 28 and are connected to a shutoff valve 30 via a connecting fluid path 29. The first hydraulic unit 8P and the second hydraulic unit 8S are connected via the unit connection pipes 28. The shutoff valve 30 is a normally open on / off valve. The shutoff valve 30 is connected to the supply fluid path 14.

[0021] When the system is operating normally, the ECU 8 closes the shutoff valve 30 to isolate the fluid supply lines 14a, 14b between the left and right front wheels and the fluid supply lines 14c, 14d between the left and right rear wheels. This allows for independent control of the wheel cylinder fluid pressures of all four wheels. Meanwhile, each ECU 8P, 8S opens the shutoff valve 30 if the other hydraulic unit fails. Because the shutoff valve 30 is normally open, the shutoff valve remains open even if the actuators of the failed hydraulic unit become uncontrollable. This allows brake fluid to be supplied from a functioning hydraulic unit to the wheel cylinders of the failed hydraulic unit via the unit connection pipe 28, enabling control of the wheel cylinder fluid pressures of all four wheels and ensuring reliable deceleration and stopping of the vehicle.

[0022] While the above describes an embodiment for carrying out the present invention, the specific configuration of the present invention is not limited to the configuration of the embodiment, and design changes and the like that do not deviate from the gist of the invention are also included in the present invention. For example, the configuration of the hydraulic unit (fluid passages, pumps, and valves) is not limited to that of the embodiment. Also, two pedal stroke sensors may be connected to both ECUs.

[0023] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0024] This application claims priority to Japanese Patent Application No. 2024-115427, filed July 19, 2024. The entire disclosure of Japanese Patent Application No. 2024-115427, filed July 19, 2024, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety.

[0025] 3P...First hydraulic pressure unit 3S...Second hydraulic pressure unit 8P...First ECU (first control unit) 8S...Second ECU (second control unit) 23P...First pedal stroke sensor (first sensor) 23S...Second pedal stroke sensor (second sensor) 25...Brake pedal (brake operator)

Claims

1. A brake control device mounted on a vehicle, comprising: a brake operator; a first sensor and a second sensor that detect a state quantity of the brake operator; a first hydraulic unit that supplies brake fluid to a first brake; and a second hydraulic unit that supplies brake fluid to a second brake, wherein the first hydraulic unit has a first control unit that generates a braking request based on the state quantity detected by the first sensor, and the second hydraulic unit has a second control unit that generates a braking request based on the state quantity detected by the second sensor.

2. A brake control device as described in claim 1, wherein the first hydraulic unit and the second hydraulic unit have a connecting pipe that connects the first hydraulic unit and the second hydraulic unit to allow the brake fluid to circulate therebetween, and a first shut-off valve and a second shut-off valve that shut off the connecting pipe, and wherein the first control unit and the second control unit open the first shut-off valve and the second shut-off valve when a failure is detected in the other control unit.

3. A brake control device according to claim 1, wherein the brake operator is connected to a reaction force generating device.

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