WO2022138815A1

WO2022138815A1 - Brake device for vehicle

Info

Publication number: WO2022138815A1
Application number: PCT/JP2021/047853
Authority: WO
Inventors: 和俊余語
Original assignee: 株式会社アドヴィックス
Priority date: 2020-12-23
Filing date: 2021-12-23
Publication date: 2022-06-30
Also published as: JP2022099362A

Abstract

The present invention is provided with: an electric cylinder 2 that makes hydraulic connection or shutoff between a reservoir 45 and a second fluid pressure output unit 32 in accordance with the position of a piston 23 and that outputs fluid in accordance with sliding of the piston 23; and a failure determination unit 92 that determines whether or not the piston position of the electric cylinder 2 is in an uncontrollable state. If it is determined by the failure determination unit 92 that the piston position of the electric cylinder 2 is in an uncontrollable state, a control unit 93 executes, when increasing a brake force, specific assistance control for causing a first fluid pressure output unit 31 to output fluid pressure to first wheel cylinders 81, 82 in a state where a connection control valve 61 is closed and for causing a second fluid pressure output unit 32 not to output fluid pressure to second wheel cylinders 83, 84.

Description

Vehicle braking device

The present invention relates to a vehicle braking device.

For example, the brake system disclosed in Japanese Patent No. 6202741 includes a reservoir, an electric cylinder, and a foil cylinder. In this system, the reservoir and the foil cylinder are connected via an electric cylinder.

Japanese Patent No. 6202741

In the above system, for example, when an electric failure occurs in the electric cylinder, the control of the electric cylinder is prohibited, the switching valve is turned off, the master cylinder and the wheel cylinder of the first system are communicated with each other, and the master cylinder and the master cylinder. It is possible to shut off the wheel cylinder of the second system. For example, in this state, by operating the ESC device (actuator) according to the operation of the brake pedal, the fluid sucked from the master cylinder is supplied to the foil cylinder of the first system, and the electric cylinder is supplied to the foil cylinder of the second system. The fluid sucked from the reservoir can be supplied via. By doing so, the braking force can be increased even if a failure occurs in the electric cylinder.

However, in the above system, when the failure of the electric cylinder is not an electrical failure, but the piston is locked at a position where the communication between the hydraulic chamber (chamber) and the reservoir is cut off, for example, by locking the reduction gear, the second system. It is possible to increase the pressure on the wheel cylinder, but it is not possible to reduce the pressure. Specifically, when the above system detects the piston lock, prohibits the pressure adjustment by the electric cylinder, and tries to perform the assist control by the ESC device, the wheel cylinder of the second system has a seal member (rubber cup) of the electric cylinder. The fluid sucked from the reservoir is supplied through. However, even if an attempt is made to depressurize the foil cylinder of the second system, the flow of fluid from the hydraulic chamber to the reservoir is blocked by the seal member of the electric cylinder, and the decompression of the foil cylinder cannot be performed.

An object of the present invention is to provide a vehicle braking device capable of assist control by a downstream unit even when a piston lock failure occurs in an electric cylinder.

The vehicle braking device of the present invention is provided in the first liquid passage connecting the reservoir and the first wheel cylinder, and can selectively output the hydraulic pressure to the reservoir side and the first wheel cylinder side. Provided in the hydraulic pressure output unit, the master cylinder provided between the reservoir and the first hydraulic pressure output unit in the first liquid passage, and the second liquid passage connecting the reservoir and the second wheel cylinder. A second hydraulic pressure output unit capable of selectively outputting hydraulic pressure to the reservoir side and the second wheel cylinder side, and the reservoir and the second hydraulic pressure output unit in the second liquid passage. It has a cylinder and a piston that slides in the cylinder, and the reservoir and the second hydraulic output unit are hydraulically connected or disconnected according to the position of the piston. An electric cylinder that outputs fluid according to the sliding of the piston, and a liquid passage to which the fluid output from the electric cylinder is supplied. In the first liquid passage, the master cylinder and the first hydraulic pressure output. A communication control valve provided in a communication passage connected to a portion between the portions, a failure determination unit for determining whether or not the piston position of the electric cylinder is in an uncontrollable state, and the first hydraulic pressure. A control unit for controlling the output unit, the second hydraulic pressure output unit, and the communication control valve is provided, and the control unit determines that the piston position of the electric cylinder cannot be controlled by the failure determination unit. If this is the case, in order to increase the braking force, the first hydraulic pressure output unit is made to output fluid toward the first wheel cylinder with the communication control valve closed, and the second hydraulic pressure output unit is made to output fluid. A specific assist control that does not output fluid toward the second wheel cylinder is executed.

According to the present invention, when a piston lock failure occurs and the piston position cannot be controlled, the first wheel cylinder that can be hydraulically connected to the reservoir via the master cylinder is added by the first hydraulic output unit. The second wheel cylinder, which is compressed and may not be hydraulically communicated with the reservoir due to the uncontrollable piston position of the electric cylinder, is not pressurized. The braking force is increased by pressurizing the first foil cylinder.

Further, the reservoir and the master cylinder can communicate with each other hydraulically, and the first hydraulic output unit can return the fluid in the first foil cylinder to the master cylinder and the reservoir. That is, by operating the first hydraulic pressure output unit, it is possible to reduce the pressure (reduce the braking force) of the first foil cylinder. The second foil cylinder may not be hydraulically connected to the reservoir via the electric cylinder because the piston position of the electric cylinder is uncontrollable, but if the piston position is uncontrollable, the second foil No depressurization is necessary because the cylinder is not pressurized. Therefore, even if a piston lock failure occurs in the electric cylinder, the first hydraulic pressure output unit, which is one of the downstream units, performs assist control (braking force adjustment) for the first foil cylinder that can be depressurized later. By doing so, braking force can be obtained.

It is a block diagram of the braking device for a vehicle of this embodiment. It is a block diagram of the electric cylinder of this embodiment. It is a block diagram of the downstream unit of this embodiment. It is a flowchart for demonstrating the flow of control of this embodiment. It is a flowchart for demonstrating another example of control of this Embodiment. It is a block diagram of another example of the downstream unit of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the parts that are the same or equal to each other are designated by the same reference numerals in the drawings. As shown in FIG. 1, the vehicle braking device 1 of the present embodiment includes an upstream unit 11, a downstream unit 3, a first brake ECU 901, and a second brake ECU 902. The vehicle braking device 1 is a device capable of supplying fluid to the

first wheel cylinders

81 and 82 and the

second wheel cylinders

83 and 84 provided on the wheels of the vehicle. For example, the

first foil cylinders

81 and 82 are provided on the front wheels, and the

second foil cylinders

83 and 84 are provided on the rear wheels. The first brake ECU 901 controls at least the upstream unit 11. The second brake ECU 902 controls at least the downstream unit 3.

(Upstream unit)
The upstream unit 11 includes a master cylinder device 4, a stroke simulator 43, a simulator cut valve 44, a reservoir 45, a first liquid passage 51, an electric cylinder 2, a second liquid passage 52, and a communication passage 53. It includes a master cut valve 62, a communication control valve 61, a stroke sensor 71,

pressure sensors

72 and 73, and a level switch 74. FIG. 1 shows a non-energized state of the vehicle braking device 1.

The master cylinder device 4 is a device capable of generating hydraulic pressure according to the driver operation. The master cylinder device 4 includes a master cylinder 41, a master piston 42, a master chamber 41a, and an urging member 41b. The master cylinder 41 is a bottomed cylindrical member or portion. The master cylinder 41 is formed with an input port 411 and an output port 412. The input port 411 and the output port 412 will be described later.

The master piston 42 is a piston member arranged in the master cylinder 41 and is mechanically connected to the brake pedal Z. The master piston 42 slides in the master cylinder 41 in response to the operation of the brake pedal Z. A through hole 421 is formed in the master piston 42. The master piston 42 is urged toward the initial position by the urging member 41b described later. The initial position is the position of the master piston 42 when the volume of the master chamber 41a is maximized. When the master piston 42 is located at the initial position, the through hole 421 and the input port 411 communicate with each other.

The master chamber 41a is formed in the master cylinder 41 by the master cylinder 41 and the master piston 42. In the present embodiment, the number of master chambers 41a formed in the master cylinder 41 is one. The volume of the master chamber 41a changes according to the movement of the master piston 42. When the master piston 42 moves to one side in the axial direction, the volume of the master chamber 41a becomes smaller and the hydraulic pressure of the master chamber 41a (hereinafter referred to as “master pressure”) increases.

The urging member 41b is a spring member provided in the master chamber 41a. When no force is applied to the master piston 42, the master piston 42 is located at the initial position. The stroke simulator 43 is connected to the master cylinder device 4 via the simulator cut valve 44. The stroke simulator 43 is a device that generates a reaction force (load) with respect to the operation of the brake pedal Z. The stroke simulator 43 includes a cylinder, a piston, and an urging member. The stroke simulator 43 is connected to the output port 412 of the master cylinder 41 via the liquid passage 43a.

The simulator cut valve 44 is a normally closed type solenoid valve provided in the liquid passage 43a. When the brake pedal Z is operated while the master cut valve 62, which will be described later, is closed and the simulator cut valve 44 is open, a pedal reaction force is generated by the stroke simulator 43.

The reservoir 45 stores fluid. The pressure in the reservoir 45 is maintained at atmospheric pressure. Inside the reservoir 45, two

storage chambers

451 and 452, each of which stores fluid, are formed.

The storage chamber 451 is connected to the master cylinder device 4. Specifically, the storage chamber 451 is connected to the input port 411 of the master cylinder 41. When the master piston 42 is located in the initial position, the storage chamber 451 is hydraulically connected to the master chamber 41a via the input port 411 and the through hole 421. When the master piston 42 slides by a predetermined amount, the input port 411 and the through hole 421 are hydraulically disconnected. In this case, the master chamber 41a and the reservoir 45 are hydraulically shut off. The storage chamber 452 is connected to the electric cylinder 2 via a second liquid passage 52 (reservoir liquid passage 522 described later). The reservoir 45 may consist of two separate reservoirs instead of the two reservoirs.

The first liquid passage 51 is a liquid passage connecting the reservoir 45 (storage chamber 451) and the

first foil cylinders

81 and 82 via the master cylinder device 4 and the downstream unit 3 (first hydraulic pressure output unit 31). be. Hereinafter, the portion of the first liquid passage 51 that connects the master cylinder device 4 and the downstream unit 3 is referred to as a “first connection liquid passage 511”, and a portion that connects the downstream unit 3 and the

first foil cylinders

81 and 82. Is referred to as "first downstream liquid passage 512". When the master piston 42 slides so as to make the master chamber 41a smaller while the master chamber 41a and the reservoir 45 are not hydraulically connected, the first connection liquid passage from the master chamber 41a via the output port 412. Fluid is supplied to 511, and hydraulic pressure is generated in the first connecting liquid passage 511. The hydraulic pressure generated in the master chamber 41a is supplied to the downstream unit 3 via the first connecting liquid passage 511. The first connection liquid passage 511 includes a connection portion 50 connected to a communication passage 53, which will be described later. The first connection liquid passage 511 is provided with a master cut valve 62 and a pressure sensor 72.

The master cut valve 62 is a normally open type solenoid valve provided between the connection portion 50 and the master cylinder 41 in the first liquid passage 51. When the master cut valve 62 is closed, the master cylinder device 4 and the downstream unit 3 are hydraulically shut off.

The pressure sensor 72 is provided between the master cut valve 62 and the master cylinder 41 in the first liquid passage 51. The pressure sensor 72 detects the pressure in the first connecting liquid passage 511. The pressure detected by the pressure sensor 72 when the master cut valve 62 is closed corresponds to the master pressure, which is the pressure generated in the master chamber 41a.

The electric cylinder 2 includes a cylinder 21, an electric motor 22, a piston 23, a hydraulic chamber 24, and an urging member 25. The electric cylinder 2 is a single type electric cylinder in which a single hydraulic chamber 24 is formed in the cylinder 21. Hereinafter, in the description of the electric cylinder 2, the moving direction of the piston 23 in which the volume of the hydraulic chamber 24 is small is defined as the front, and the opposite direction is defined as the rear.

The cylinder 21 is a bottomed cylindrical member or part. The cylinder 21 is formed by utilizing, for example, a part of a housing (metal block). The cylinder 21 is formed with an input port 211 and an output port 212. As shown in FIG. 2, the input port 211 is an opening, and is formed between the seal member X1 provided on the cylinder 21 and the seal member X2. The seal member X1 and the seal member X2 are annular seal members, and their cross sections have a concave shape that opens forward (in other words, a convex arc shape that swells backward). Therefore, the seal member X1 allows the flow of fluid from the input port 211 to the hydraulic chamber 24 when the hydraulic pressure chamber 24 becomes a negative pressure, and when the pressure in the hydraulic pressure chamber 24 is equal to or higher than the atmospheric pressure, The flow of fluid from the hydraulic chamber 24 to the input port 211 is prohibited. The seal members X1 and X2 are arranged in an annular groove formed on the inner peripheral surface of the cylinder 21. The output port 212 is an opening and is formed in front of the input port 211. At least one input port 211 and one output port 212 may be formed.

The electric motor 22 is connected to the piston 23 via a linear motion mechanism 22a that converts rotary motion into linear motion. The piston 23 is a bottomed cylindrical member and slides in the cylinder 21 by being driven by an electric motor 22. A through hole 231 is formed in the piston 23. The through hole 231 communicates with the input port 211 when the piston 23 is located at the initial position.

The hydraulic chamber 24 is partitioned by a cylinder 21 and a piston 23, and the volume changes according to the movement of the piston 23. The initial position of the piston 23 is the position where the volume of the hydraulic chamber 24 is maximized (see FIG. 2).

The hydraulic chamber 24 can communicate with the reservoir 45 via the input port 211. Specifically, when the piston 23 is located in the initial position, it is hydraulically connected to the reservoir 45 via the through hole 231 and the input port 211. When the through hole 231 and the input port 211 do not communicate with each other, the hydraulic chamber 24 and the reservoir 45 are hydraulically cut off. More specifically, the hydraulic pressure in the hydraulic pressure chamber 24 is negative even when the communication between the input port 211 and the through hole 231 is cut off due to the movement of the piston 23 forward by a predetermined amount. In some cases, the flow of fluid from the reservoir 45 to the hydraulic chamber 24 via the seal member X1 is allowed. However, in order to make the explanation easy to understand, in the present embodiment, an example in which a negative pressure is not generated in the hydraulic pressure chamber 24 will be described. The hydraulic chamber 24 is connected to the second liquid passage 52 (second connection liquid passage 521 described later) via the output port 212.

The urging member 25 is a spring that is arranged in the hydraulic chamber 24 and urges the piston 23 toward the initial position. When the electric motor 22 is not driven, the piston 23 is positioned at the initial position due to the urging force of the urging member 25.

When the piston 23 is located at the initial position, the hydraulic chamber 24 is connected to the reservoir 45 via the input port 211, the through hole 231 and the second liquid passage 52 (reservoir liquid passage 522 described later). When the piston 23 moves forward by a predetermined amount from the initial position by driving the electric motor 22, the communication between the input port 211 and the through hole 231 is cut off. In this case, the hydraulic chamber 24 is hydraulically shut off from the reservoir 45. When the piston 23 slides so as to make the hydraulic chamber 24 smaller while the hydraulic chamber 24 and the reservoir 45 are hydraulically shut off, fluid is output from the hydraulic chamber 24 via the output port 212. To. The output fluid is supplied to the second liquid passage 52 (second connecting liquid passage 521) and the communication passage 53 (described later). As a result, hydraulic pressure is generated in each of the second liquid passage 52 (second connecting liquid passage 521) and the communication passage 53.

The electric cylinder 2 is input when the input port 211 is opened by the piston 23 when the relative position of the piston 23 with respect to the cylinder 21 is a predetermined open position, and when the relative position of the piston 23 with respect to the cylinder 21 is a predetermined closed position. The port 211 is configured to be closed by the piston 23. In other words, when the piston 23 is located in the "communication region" in the cylinder 21, the reservoir 45 and the hydraulic chamber 24 communicate with each other, and when the piston 23 is located in the "blocking region" in the cylinder 21, the reservoir 45 and The connection with the hydraulic chamber 24 is cut off. Of the movable area of the piston 23, the communication area is the area (including the initial position) between the initial position of the piston 23 and the position (switching position) ahead of the initial position by a predetermined amount, and the blocking area is the switching position. The area between and the front end surface of the cylinder 21.

The second liquid passage 52 is a liquid passage connecting the reservoir 45 (reservoir 452) and the

second foil cylinders

83 and 84 via the electric cylinder 2 and the downstream unit 3 (second hydraulic pressure output unit 32). .. Hereinafter, the portion of the second liquid passage 52 that connects the electric cylinder 2 and the downstream unit 3 is referred to as a “second connection liquid passage 521”, and the electric cylinder 2 and the reservoir 45 of the second liquid passage 52 are connected. The portion is referred to as "reservoir fluid passage 522", and the portion connecting the downstream unit 3 and the

second foil cylinders

83 and 84 is referred to as "second downstream fluid passage 523". The hydraulic pressure generated in the hydraulic pressure chamber 24 is supplied to the downstream unit 3 via the second connecting liquid passage 521. A hydraulic pressure sensor 73 is provided in the second connecting liquid passage 521.

The hydraulic pressure sensor 73 is a sensor that detects the pressure in the second connecting liquid passage 521. The hydraulic pressure detected by the hydraulic pressure sensor 73 corresponds to the output pressure of the electric cylinder 2 in a state where the control mode of the vehicle braking device 1 is the brake-by-wire mode (hereinafter referred to as “by-wire mode”) described later.

The communication passage 53 is a liquid passage connecting the first connecting liquid passage 511 and the second connecting liquid passage 521. The communication passage 53 is connected to the first liquid passage 51 by a connecting portion 50. A communication control valve 61 is provided in the communication passage 53. The communication control valve 61 is a normally closed type solenoid valve.

The stroke sensor 71 detects the stroke of the brake pedal Z. In this embodiment, two stroke sensors 71 are provided. The data detected by the two stroke sensors 71 is transmitted to the

brake ECUs

901 and 902. The

brake ECUs

901 and 902 acquire stroke information from the corresponding stroke sensors 71, respectively.

The level switch 74 is provided in the reservoir 45 and detects that the liquid level of the reservoir 45 is less than a predetermined position. When the liquid level of the reservoir 45 becomes less than a predetermined value, the level switch 74 transmits data indicating that the liquid level has dropped to the first brake ECU 901.

(Downstream unit)
Next, the downstream unit 3 will be described with reference to FIG. The downstream unit 3 is a so-called ESC actuator (ESC device), and can independently regulate the hydraulic pressure of each of the foil cylinders 81 to 84. Specifically, in the downstream unit 3, the first hydraulic pressure output unit 31 configured to be able to adjust the pressure of the

first wheel cylinders

81 and 82 and the

second wheel cylinder

83 and 84 configured to be able to adjust the pressure are second. A hydraulic pressure output unit 32 is provided. Hereinafter, in the description of the downstream unit 3, the position of the upstream unit 11 with respect to the downstream unit 3 is referred to as upstream, and the positions of the foil cylinders 81 to 84 with respect to the downstream unit 3 are referred to as downstream.

The first hydraulic pressure output unit 31 is connected to the first connecting liquid passage 511 on the upstream side and connected to the

first foil cylinders

81 and 82 on the downstream side. The second hydraulic pressure output unit 32 is connected to the second connecting liquid passage 521 on the upstream side and connected to the

second foil cylinders

83 and 84 on the downstream side. The first hydraulic pressure output unit 31 and the second hydraulic pressure output unit 32 are independent of each other on the hydraulic pressure circuit in the downstream unit 3.

The fluid is supplied from the upstream unit 11 to the first hydraulic pressure output unit 31 via the first connection liquid passage 511. The first hydraulic pressure output unit 31 is configured to be able to increase the hydraulic pressure of the

first foil cylinders

81 and 82 based on the basic hydraulic pressure generated by the upstream unit 11. The first hydraulic pressure output unit 31 is configured to pressurize the

first wheel cylinders

81 and 82 by generating a differential pressure between the input hydraulic pressure and the hydraulic pressures of the

first wheel cylinders

81 and 82. ing.

The first hydraulic pressure output unit 31 includes a liquid passage 311, a pump liquid passage 315a, a pressure sensor 75, a differential pressure control valve 312, a check valve 312a, a holding valve 313, a check valve 313a, and a pressure reducing liquid passage. It includes a 314a, a pressure reducing valve 314, a pump 315, an electric motor 316, a reservoir 317, and a recirculation liquid passage 317a.

The liquid passage 311 is a liquid passage connecting the first connecting liquid passage 511 and the first downstream liquid passage 512. The liquid passage 311 includes a branch portion X connected to the pump liquid passage 315a. The liquid passage 311 is a branch portion X, and branches into a liquid passage connected to one first foil cylinder 81 and a liquid passage connected to the other first foil cylinder 82. Since the configurations of the liquid passages 311 on the two liquid passages are the same, only the liquid passages connected to the first foil cylinder 81 will be described (referred to as the liquid passages 311).

The pressure sensor 75 is provided on the upstream unit 11 side of the differential pressure control valve 312 in the liquid passage 311. The pressure sensor 75 detects the pressure in the liquid passage 311. The pressure detected by the pressure sensor 75 corresponds to the hydraulic pressure input from the first connecting liquid passage 511 to the first hydraulic pressure output unit 31. The data detected by the pressure sensor 75 is transmitted to the second brake ECU 902.

The differential pressure control valve 312 is a normally open type linear solenoid valve provided between the branch portion X and the pressure sensor 75 in the liquid passage 311. By controlling the opening degree of the differential pressure control valve 312, it is possible to generate a differential pressure between the upstream and downstream sides of the differential pressure control valve 312. The check valve 312a is provided in parallel with the differential pressure control valve 312. The check valve 312a is configured to allow only fluid flow from the upstream side to the downstream side.

The holding valve 313 is a normally open type solenoid valve provided between the branch portion X and the first foil cylinder 81 in the liquid passage 311. The check valve 313a is provided in parallel with the holding valve 313. The check valve 313a is configured to allow only fluid flow from the downstream side to the upstream side.

The decompression liquid passage 314a is a liquid passage that connects the portion of the liquid passage 311 between the holding valve 313 and the first foil cylinder 81 and the reservoir 317. A pressure reducing valve 314 is provided in the pressure reducing liquid passage 314a.

The pressure reducing valve 314 is a normally closed type solenoid valve provided in the pressure reducing liquid passage 314a. When the pressure reducing valve 314 is in the valve open state, the fluid in the first foil cylinder 81 can flow into the reservoir 317 via the pressure reducing liquid passage 314a. Therefore, the pressure of the first foil cylinder 81 can be reduced by opening the pressure reducing valve 314.

Reservoir 317 is a well-known pressure-regulating reservoir that stores fluid, and is connected to a decompression fluid passage 314a and a reflux fluid passage 317a. The reflux liquid passage 317a is a liquid passage that connects a portion of the liquid passage 311 between the pressure sensor 75 and the differential pressure control valve 312 and the reservoir 317. The fluid in the reservoir 317 is sucked by the operation of the pump 315. When the amount of fluid in the reservoir 317 decreases, the valve in the reservoir 317 opens, and the fluid is supplied to the reservoir 317 from the first connecting liquid passage 511 via the reflux liquid passage 317a.

The pump liquid passage 315a is a liquid passage that connects the portion between the pressure reducing valve 314 and the reservoir 317 in the pressure reducing liquid passage 314a and the branch portion X of the liquid passage 311. A pump 315 is provided in the pump liquid passage 315a.

The pump 315 is a pump that operates in response to the drive of the electric motor 316, and is, for example, a well-known piston pump or gear pump. The suction side of the pump 315 is connected to the reservoir 317, and the discharge side of the pump 315 is connected to the branch portion X. When the pump 315 is activated, the fluid in the reservoir 317 is sucked in to supply the fluid to the branch X.

The first hydraulic pressure output unit 31 is configured to be able to pressurize the

first foil cylinders

81 and 82 based on the hydraulic pressure input from the upstream side by operating various solenoid valves and pumps. Since the second hydraulic pressure output unit 32 has the same configuration as the first hydraulic pressure output unit 31 except that the pressure sensor 75 is not provided, the description thereof will be omitted. Like the first hydraulic pressure output unit 31, the second hydraulic pressure output unit 32 is also configured to be able to pressurize the

second foil cylinders

83 and 84 based on the basic hydraulic pressure.

(Summary of composition)
The vehicle braking device 1 of the present embodiment includes a first hydraulic pressure output unit 31, a master cylinder 41, a second hydraulic pressure output unit 32, an electric cylinder 2, a communication control valve 61, a first brake ECU 901, and a second brake ECU 902. It is equipped with. The first hydraulic pressure output unit 31 is provided in the first liquid passage 51 connecting the reservoir 45 and the

first foil cylinders

81 and 82, and selectively liquids on the reservoir 45 side and the

first foil cylinders

81 and 82 sides. It is a device that can output pressure. The master cylinder 41 is provided between the reservoir 45 and the first hydraulic pressure output unit 31 in the first liquid passage 51. The reservoir 45 and the first hydraulic pressure output unit 31 can be hydraulically connected via the master cylinder 41. The second hydraulic pressure output unit 32 is provided in the second liquid passage 52 connecting the reservoir 45 and the

second foil cylinders

83, 84, and selectively liquids on the reservoir 45 side and the

second foil cylinders

83, 84 side. It is a device that can output pressure. The electric cylinder 2 is provided between the reservoir 45 and the second hydraulic pressure output unit 32 in the second liquid passage 52, and has a cylinder 21 and a piston 23 that slides in the cylinder 21. The reservoir 45 and the second hydraulic pressure output unit 32 are hydraulically connected or disconnected according to the position, and the fluid is output according to the sliding of the piston 23. The communication control valve 61 is a liquid passage to which the fluid output from the electric cylinder 2 is supplied, and is connected to a portion of the first liquid passage 51 between the master cylinder 41 and the first hydraulic pressure output unit 31. It is provided in the passage 53. More specifically, the communication control valve 61 is electrically operated in the portion between the master cylinder 41 and the first hydraulic pressure output unit 31 (that is, the first connecting liquid passage 511) in the first liquid passage 51 and in the second liquid passage 52. It is provided in a communication passage 53 connecting a portion between the cylinder 2 and the second hydraulic pressure output unit 32 (that is, the second connecting liquid passage 521).

(Brake ECU)
The first brake ECU 901 and the second brake ECU 902 (hereinafter, also referred to as "

brake ECUs

901 and 902") are electronic control units including a CPU and a memory, respectively. Each

brake ECU

901, 902 includes one or more processors that perform various controls. The first brake ECU 901 and the second brake ECU 902 are separate ECUs, and are connected to each other so that information (control information, etc.) can be communicated with each other.

The first brake ECU 901 is configured to be able to control the upstream unit 11. Specifically, the first brake ECU 901 can control the electric cylinder 2 and the

solenoid valves

61, 62, 44 based on the data detected by the plurality of

sensors

71, 72, 73, 74 of the upstream unit. The first brake ECU 901 can calculate each foil pressure based on the detection results of the

pressure sensors

72 and 73 and the control state of the downstream unit 3.

The second brake ECU 902 is configured to be able to control the downstream unit 3 based on the data detected by the stroke sensor 71 and the pressure sensor 75. The second brake ECU 902 also receives data detected by a wheel speed sensor (not shown), an acceleration sensor (not shown), or the like provided in the vehicle. When the second brake ECU 902 pressurizes the first wheel cylinder 81 by the downstream unit 3, the second brake ECU 902 sets the target differential pressure (hydraulic pressure of the first wheel cylinder 81> hydraulic pressure of the first connecting liquid passage 511) to the differential pressure control valve 312. The corresponding control current is applied to close the differential pressure control valve 312. At this time, the holding valve 313 is open and the pressure reducing valve 314 is closed. Further, by operating the pump 315, the fluid is supplied from the first connection liquid passage 511 to the branch portion X via the reservoir 317. As a result, the first foil cylinder 81 is pressurized.

When the wheel pressure is reduced by the downstream unit 3 by anti-skid control or the like, the second brake ECU 902 operates the pump 315 in a state where the pressure reducing valve 314 is opened and the holding valve 313 is closed, and the first wheel cylinder is operated. Pump back the fluid in 81. The second brake ECU 902 closes the holding valve 313 and the pressure reducing valve 314 when the foil pressure is held by the downstream unit 3. When the wheel pressure is pressurized or reduced only by the operation of the electric cylinder 2 or the master cylinder device 4, the second brake ECU 902 opens the differential pressure control valve 312 and the holding valve 313, and closes the pressure reducing valve 314.

The second brake ECU 902 can calculate each foil pressure based on the control state of the pressure sensor 75 and the downstream unit 3. The detected values of the various sensors may be transmitted to both

brake ECUs

901 and 902.

The vehicle braking device 1 is configured to be capable of executing normal control. Normal control is also called by-wire mode. In normal control, the output pressure of the upstream unit 11 is the hydraulic pressure output by the electric cylinder 2. The downstream unit 3 can output a hydraulic pressure to the foil cylinders 81 to 84 based on the output pressure of the upstream unit 11. Hereinafter, normal control will be described.

(Normal control)
The first brake ECU 901 includes a normal control unit 91 that controls an upstream unit 11 including an electric motor 22 and the like, and a failure determination unit 92. The normal control unit 91 is configured to be able to execute normal control. The normal control is a control in which the master cylinder device 4 and the foil cylinders 81 to 84 are hydraulically shut off, and the foil cylinders 81 to 84 are pressurized by at least one of the electric cylinder 2 and the downstream unit 3. Normal control includes preparation control and normal pressurization control.

Preparation control is a control that forms a so-called by-wire mode. In the preparatory control, the normal control unit 91 closes the master cut valve 62 and opens the communication control valve 61 and the simulator cut valve 44. The preparatory control is executed when the vehicle provided with the vehicle braking device 1 is ready to start. The ready-to-start state is, for example, the case where the ignition of the vehicle is turned on or the case where the electric vehicle is started. More specifically, the preparatory control of the first embodiment is executed when the first brake ECU 901 is started (power is turned on).

Note that the preparatory control may be executed when the brake pedal is operated, not when the ignition of the vehicle is turned on or when the electric vehicle is started. In this case, the by-wire mode may be formed when the brake pedal is operated, and the by-wire mode may not be formed when the brake pedal is not operated.

Normal pressurization control is control that pressurizes the foil cylinders 81 to 84 in the by-wire mode (when the preparation control is completed). In the normal pressurization control, the normal control unit 91 sets the target output pressure based on the data detected by the stroke sensor 71 and the pressure sensor 72. The electric cylinder 2 is controlled based on the set target output pressure. The second brake ECU 902 operates the downstream unit 3 when executing anti-skid control or the like. As described above, in the normal control, the electric cylinder 2, the first hydraulic pressure output unit 31, and the second hydraulic pressure output unit 32 are controlled based on the set target value, so that the liquids in the foil cylinders 81 to 84 are liquid. The pressure can be adjusted.

(Failure detection of electric cylinder)
The failure determination unit 92 determines whether or not the position of the piston 23 of the electric cylinder 2 (also referred to as “piston position”) is in an uncontrollable state. Further, the failure determination unit 92 of the present embodiment determines whether or not the reservoir 45 and the second hydraulic pressure output unit 32 are hydraulically connected via the electric cylinder 2 based on the determination result. The failure determination unit 92 estimates the position of the piston 23 at least when it is determined that the piston position is in an uncontrollable state.

More specifically, the failure determination unit 92 determines whether or not the piston 23 of the electric cylinder 2 is locked (which can be said to be stuck) based on the detection result of the rotation angle sensor 22b provided for the electric motor 22. .. The rotation angle sensor 22b is a sensor that detects the rotation angle (rotation position) of the electric motor 22. When the piston 23 is mechanically locked (that is, when the piston 23 becomes physically immovable with respect to the cylinder 21) due to the reduction gear forming a part of the linear motion mechanism 22a being locked or the like. Even if the operation instruction (control current) is output to the electric motor 22, the electric motor 22 does not rotate and the detected value of the rotation angle sensor 22b does not change. Using this principle, the failure determination unit 92 can determine whether or not the piston 23 is locked based on the content of the control instruction to the electric motor 22 and the detection result of the rotation angle sensor 22b. Hereinafter, in the description, the mechanical locking of the piston 23 is also referred to as “piston lock”.

Further, the failure determination unit 92 can estimate where the piston 23 is located in the cylinder 21 based on the detection result of the rotation angle sensor 22b. That is, the failure determination unit 92 can estimate whether the piston 23 is located in the communication region or the cutoff region in the cylinder 21 based on the detection result of the rotation angle sensor 22b. Therefore, when the failure determination unit 92 detects the piston lock, it can also estimate at which position the piston 23 is locked. However, when it is difficult to estimate which region the rotation angle sensor 22b is located in, for example, when the detection result of the rotation angle sensor 22b indicates the vicinity of the boundary (switching position) between the communication region and the cutoff region, the failure determination unit 92 The judgment result is "unknown (position cannot be determined)". In this way, the failure determination unit 92 selects any of "communication", "blocking", and "unknown" for the lock position of the piston 23.

(Assistance control when the piston is locked)
The

brake ECUs

901 and 902 include a control unit 93 that controls the first hydraulic pressure output unit 31, the second hydraulic pressure output unit 32, and the communication control valve 61. In the assist control at the time of piston lock, for example, the control unit 93 of the first brake ECU 901 controls the communication control valve 61, and the control unit 93 of the second brake ECU 902 controls the downstream unit 3. Both

brake ECUs

901 and 902 cooperate to execute various controls.

The control unit 93 sets the control mode to the assist mode when the brake operation is started (the brake pedal Z is depressed) and the piston lock is detected by the failure determination unit 92. The assist mode is a mode in which the assist control by the downstream unit 3 is executed when the piston is locked. The assist control is a control in which the foil pressure is adjusted by the downstream unit 3 according to the required braking force. In the assist mode (each assist control described below), the master cut valve 62 is opened and the simulator cut valve 44 is closed in common.

(Assistance control when the judgment result is "unknown")
In the control unit 93, the failure determination unit 92 determines that the piston position of the electric cylinder 2 is in an uncontrollable state, and the reservoir 45 and the second hydraulic output unit 32 are hydraulically connected via the electric cylinder 2. If it is not determined to be the case (only when the determination result is "unknown" in this embodiment), the first hydraulic pressure output unit 31 with the communication control valve 61 closed in order to increase the braking force. Is made to output the hydraulic pressure toward the

first wheel cylinders

81 and 82, and the second hydraulic pressure output unit 32 is not made to output the hydraulic pressure toward the

second wheel cylinders

83 and 84. That is, when the failure determination unit 92 determines that the lock position of the piston 23 is unknown, the control unit 93 outputs the first hydraulic pressure with the communication control valve 61 closed in order to increase the braking force. The unit 31 is operated, and the second hydraulic pressure output unit 32 is not operated.

In this assist control, fluid is supplied from the master cylinder 41 to the

first foil cylinders

81 and 82 by the operation of the first hydraulic pressure output unit 31, and only the

first foil cylinders

81 and 82 are pressurized. The first hydraulic pressure output unit 31 pressurizes the

first foil cylinders

81 and 82 using the master pressure generated by the driver's brake operation as the basic hydraulic pressure.

The reservoir 45 (reservoir 451) and the master cylinder 41 can communicate with each other, and the first hydraulic pressure output unit 31 can return the fluid in the

first foil cylinders

81 and 82 to the master cylinder 41 and the reservoir 45. That is, the control unit 93 can also operate the first hydraulic pressure output unit 31 to reduce the pressure of the first foil cylinders 81 and 82 (reduce the braking force). Hereinafter, the assist control when the determination result is "unknown" is referred to as "unknown assist control (corresponding to" specific assist control ")".

(Assistance control when the judgment result is "blocking")
The control unit 93 is determined by the failure determination unit 92 that the piston position of the electric cylinder 2 is in an uncontrollable state, and that the reservoir 45 and the second hydraulic output unit 32 are hydraulically shut off. If so, in order to increase the braking force, with the communication control valve 61 open, the first hydraulic pressure output unit 31 is made to output the hydraulic pressure toward the

first wheel cylinders

81 and 82, and the second hydraulic pressure output unit is 32 is made to output the hydraulic pressure toward the

second wheel cylinders

83 and 84. That is, when the failure determination unit 92 determines that the lock position of the piston 23 is the cutoff region, the control unit 93 has the first hydraulic pressure output unit with the communication control valve 61 open in order to increase the braking force. Both 31 and the second hydraulic pressure output unit 32 are operated.

In this assist control, fluid is supplied from the master cylinder 41 to the

first foil cylinders

81 and 82 by the operation of the first hydraulic pressure output unit 31, and the communication control valve 61 is supplied from the master cylinder 41 by the operation of the second hydraulic pressure output unit 32. The fluid is supplied to the

second foil cylinders

83 and 84 via the above. The first hydraulic pressure output unit 31 and the second hydraulic pressure output unit 32 pressurize the target wheel cylinders 81 to 84, respectively, using the master pressure generated by the brake operation of the driver as the basic hydraulic pressure. As a result, all the foil cylinders 81 to 84 are pressurized.

The control unit 93 operates the first hydraulic pressure output unit 31 to return the fluid in the

first foil cylinders

81 and 82 to the master cylinder 41 and the reservoir 45 (storage chamber 451), whereby the

first foil cylinders

81 and 82 are returned. Can be depressurized. Further, when the pressure of the

second foil cylinders

83 and 84 is reduced, the control unit 93 opens the communication control valve 61 to allow the fluid in the

second foil cylinders

83 and 84 to pass through the communication control valve 61 to the master cylinder. It can be returned to 41 and the reservoir 45 (reservoir 451). As described above, the control unit 93 opens the communication control valve 61 when the second hydraulic pressure output unit 32 outputs the hydraulic pressure toward the reservoir 45. As a result, the

second foil cylinders

83 and 84 can also be depressurized. As described above, in the assist control when the determination result is "disconnection" (hereinafter referred to as "disruption assist control"), acceleration / depressurization is possible in all the foil cylinders 81 to 84.

In the present embodiment, the execution condition of the assist control at the time of interruption is that the failure determination unit 92 does not determine "communication" (first condition) and the failure determination unit 92 determines that "blocking" (blocking). It can be said that the second condition) is included. When the two conditions are satisfied, the assist control at the time of interruption is executed. When neither "communication" nor "blocking" is determined by the failure determination unit 92, that is, when only the first condition is satisfied, the assist control when the determination cannot be made is executed.

(Assistance control when the judgment result is "communication")
In the control unit 93, the failure determination unit 92 determines that the piston position of the electric cylinder 2 is in an uncontrollable state, and the reservoir 45 and the second hydraulic output unit 32 are hydraulically connected via the electric cylinder 2. When it is determined that the braking force is increased, the first hydraulic pressure output unit 31 is made to output the hydraulic pressure toward the

first wheel cylinders

81 and 82 with the communication control valve 61 closed. The second hydraulic pressure output unit 32 is made to output the hydraulic pressure toward the

second wheel cylinders

83 and 84. That is, when the failure determination unit 92 determines that the lock position of the piston 23 is the communication region, the control unit 93 has the first hydraulic pressure output unit with the communication control valve 61 closed in order to increase the braking force. Both 31 and the second hydraulic pressure output unit 32 are operated.

In this assist control, fluid is supplied from the master cylinder 41 to the

first foil cylinders

81 and 82 by the operation of the first hydraulic pressure output unit 31, and from the reservoir 45 (storage chamber 452) by the operation of the second hydraulic pressure output unit 32. The fluid is supplied to the

second foil cylinders

83 and 84 via the electric cylinder 2. Since the communication control valve 61 is closed, the first liquid passage 51 and the second liquid passage 52 are independent of each other.

The first hydraulic pressure output unit 31 pressurizes the

first foil cylinders

81 and 82 using the master pressure generated by the driver's brake operation as the basic hydraulic pressure. The second hydraulic pressure output unit 32 pressurizes the

second foil cylinders

83 and 84 by using the fluid of the reservoir 45 (reservoir 452). As a result, all the foil cylinders 81 to 84 are pressurized.

Similar to the assist control when unknown, the control unit 93 operates the first hydraulic pressure output unit 31 with the communication control valve 61 closed to remove the fluid in the

first foil cylinders

81 and 82 from the master cylinder 41 and the reservoir 45 ( By returning to the storage chamber 451), the pressure of the

first foil cylinders

81 and 82 can be reduced. Further, when the pressure of the

second foil cylinders

83 and 84 is reduced, the control unit 93 operates the second hydraulic pressure output unit 32 with the communication control valve 61 closed, and the control unit 93 operates the

second foil cylinders

83 and 84 in the

second foil cylinders

83 and 84. The fluid can be returned to the reservoir 45 (reservoir 452) via the electric cylinder 2. The control unit 93 closes the communication control valve 61 when at least one of the first hydraulic pressure output unit 31 and the second hydraulic pressure output unit 32 outputs the hydraulic pressure toward the reservoir 45. As described above, even in the assist control when the determination result is "communication" (hereinafter referred to as "communication assist control"), acceleration / depressurization is possible in all the foil cylinders 81 to 84.

(Control flow)
The control flow of the present embodiment will be described with reference to FIG. As shown in FIG. 4, the brake operation is started, and it is determined whether or not the piston lock is detected by the failure determination unit 92 (S100). When the piston lock is detected (S100: Yes), the assist mode is started (S101). The control unit 93 confirms whether or not the failure determination unit 92 can determine (estimate) the position of the piston 23 (S102). When the failure determination unit 92 determines that the control unit 93 is "unknown (position determination impossible)" (S102: No), the control unit 93 executes assistive control when unknown (S103).

When the failure determination unit 92 determines "communication" (S102: Yes, S104: Yes), the control unit 93 executes the assist control during communication (S105). When it is determined by the failure determination unit 92 to be "blocked" (S102: Yes, S104: No), the control unit 93 executes the assist control at the time of interruption (S106). As described above, when the determination result is "communication", the control unit 93 executes the communication assist control instead of the unknown assist control, and when the determination result is "block", the control unit 93 interrupts instead of the unknown assist control. Perform time assist control.

(Effect of this embodiment)
According to the present embodiment, a lock failure of the piston 23 has occurred, and the judgment result of the failure determination unit 92 is not "the reservoir 45 and the second hydraulic pressure output unit 32 are in communication" (determined in the present embodiment). (Only when the result is "unknown"), only the

first wheel cylinders

81 and 82 are pressurized by the assist control, and the

second wheel cylinders

83 and 84 that do not communicate with the reservoir 45 are not pressurized. The braking force (braking force of the front wheels in this embodiment) is increased by pressurizing the

first foil cylinders

81 and 82.

Further, the first hydraulic pressure output unit 31 can return the fluid in the

first foil cylinders

81 and 82 to the master cylinder 41 and the reservoir 45. That is, by operating the first hydraulic pressure output unit 31, depressurization (reduction of braking force) of the

first foil cylinders

81 and 82 is also possible. No depressurization is required for the

second foil cylinders

83 and 84 that are not pressurized. Therefore, even if a lock failure of the piston 23 occurs in the electric cylinder 2, assist control (braking force adjustment) by the first hydraulic pressure output unit 31, which is one of the downstream units 3, is possible.

Further, in the assist control at the time of interruption and the assist control at the time of communication, the control unit 93 can pressurize and depressurize the foil cylinders 81 to 84 as described above. As described above, according to the present embodiment, even if a lock failure of the piston 23 occurs in the electric cylinder 2, assist control (braking force adjustment) by the downstream unit 3 becomes possible.

(others)
The present invention is not limited to the above embodiment. For example, the assist control at the time of interruption may have the same control content as the assist control at the time of unknown. Examples of cases where the determination result of the failure determination unit 92 is not "the reservoir 45 and the second hydraulic pressure output unit 32 communicate with each other" include "unknown" and "blocking". In the above embodiment, the assist control is executed differently depending on the case of "unknown" and the case of "blocking", but it may be set so that the assist control at the time of unknown is executed regardless of the judgment result. .. For example, as shown in FIG. 5, when the failure determination unit 92 determines “unknown” (S202: No) or determines “blocking” (S203: No), the control unit 93 executes assist control when unknown. Then, only the

first foil cylinders

81 and 82 are pressurized (S204). When the failure determination unit 92 determines “communication” (S203: Yes), the control unit 93 executes the assist control during communication (S205). This also enables assist control (braking force adjustment) by the downstream unit 3 even when a lock failure of the piston 23 occurs. For example, if the failure determination unit 92 does not estimate the lock position of the piston 23, the control unit 93 may execute the assist control when the failure determination unit 92 detects the piston lock. In the case of this configuration, the assist control is only the assist control when unknown (specific assist control). That is, when the failure determination unit 92 determines that the piston position of the electric cylinder 2 is in an uncontrollable state, the control unit 93 increases the braking force by using the first liquid with the communication control valve 61 closed. The pressure output unit 31 is made to output the fluid toward the

first wheel cylinders

81 and 82, and the second hydraulic pressure output unit 32 executes the specific assist control not to output the fluid toward the

second wheel cylinders

83 and 84.

Further, the downstream unit 3 may have a configuration as shown in FIG. 6, for example (the reference numeral of the check valve is omitted). The portion different from the above embodiment will be briefly described below by taking the first hydraulic pressure output unit 31 as an example. The reflux fluid channel 317a is a fluid channel in which one is connected to the first connecting liquid passage 511 and the other is connected to the suction port of the pump 315 without passing through the reservoir 317. A normally closed type solenoid valve 318 is arranged in the reflux liquid passage 317a. Reservoir 317 is a reservoir that does not have a valve function like a pressure regulating reservoir and is provided with a cylinder, a piston, and an urging member. In the downstream unit 3, the upstream unit 11 and the suction port of the pump 315 can communicate with each other by opening the solenoid valve 318. When the pump 315 operates with the solenoid valve 318 opened, the pump 315 sucks fluid from the upstream unit 11 and discharges it to the branch portion X. The second hydraulic pressure output unit 32 has the same configuration as the first hydraulic pressure output unit 31.

In such a downstream unit 3, when the control unit 93 executes assistive control when unknown, the solenoid valve 318 of the first hydraulic pressure output unit 31 is opened, and the solenoid valve 318 of the second hydraulic pressure output unit 32 is opened. Do not open the valve. As a result, only the first hydraulic pressure output unit 31 capable of controlling the depressurization can suck the fluid from the master cylinder 41 and supply it to the

first foil cylinders

81 and 82. Further, the control unit 93 opens both the solenoid valves 318 of the first hydraulic pressure output unit 31 and the second hydraulic pressure output unit 32 when executing the assist control at the time of interruption or the assist control at the time of communication. As a result, both the first hydraulic pressure output unit 31 and the second hydraulic pressure output unit 32 can suck the fluid from the upstream unit 11, respectively.

Further, instead of the electric cylinder 2, an electric cylinder not provided with the urging member 25 may be adopted. In this case, it is preferable that the energization configuration for the electric motor 22 is a redundant configuration. Further, the downstream unit 3 may be provided with an electric cylinder instead of the pump 315. The present invention can also be applied to, for example, a vehicle including a regenerative braking device (hybrid vehicle or electric vehicle), a vehicle that executes automatic brake control, or an autonomous driving vehicle.

Further, in the above embodiment, the

first wheel cylinders

81 and 82 are provided on the front wheels and the

second wheel cylinders

83 and 84 are provided on the rear wheels, but the

first wheel cylinders

81 and 82 are provided on the right front wheel and the left rear wheel. The

second wheel cylinders

83 and 84 may be provided on the left front wheel and the right rear wheel. The communication passage 53 may be, for example, a liquid passage connecting the first liquid passage 51 and the electric cylinder 2. In this case, it can be said that the communication passage 53 connects the first liquid passage 51 and the second liquid passage 52 via the electric cylinder 2. It can be said that the communication passage 53 is a liquid passage in which the fluid output from the electric cylinder 2 is supplied directly or via the second liquid passage 52.

Claims

A first hydraulic pressure output unit provided in the first liquid passage connecting the reservoir and the first foil cylinder and capable of selectively outputting the hydraulic pressure to the reservoir side and the first foil cylinder side.
A master cylinder provided between the reservoir and the first hydraulic pressure output unit in the first liquid passage, and
A second hydraulic pressure output unit provided in the second liquid passage connecting the reservoir and the second foil cylinder and capable of selectively outputting the hydraulic pressure to the reservoir side and the second foil cylinder side.
It has a cylinder and a piston that slides in the cylinder, which is provided between the reservoir and the second hydraulic pressure output unit in the second liquid passage, and has the reservoir according to the position of the piston. An electric cylinder that hydraulically connects or disconnects the second hydraulic output unit and outputs fluid according to the sliding of the piston.
A liquid passage to which the fluid output from the electric cylinder is supplied, which is provided in a communication passage connected to a portion between the master cylinder and the first hydraulic pressure output portion in the first liquid passage. Communication control valve and
A failure determination unit that determines whether or not the piston position of the electric cylinder is in an uncontrollable state.
A control unit that controls the first hydraulic pressure output unit, the second hydraulic pressure output unit, and the communication control valve.
Equipped with
When the failure determination unit determines that the piston position of the electric cylinder is in an uncontrollable state, the control unit increases the braking force by the first hydraulic pressure with the communication control valve closed. A vehicle braking device that causes an output unit to output fluid toward the first wheel cylinder and does not cause the second hydraulic pressure output unit to output fluid toward the second wheel cylinder.
The failure determination unit determines whether or not the reservoir and the second hydraulic pressure output unit are hydraulically connected via the electric cylinder.
The control unit
When it is determined by the failure determination unit that the piston position of the electric cylinder is in an uncontrollable state and the reservoir and the second hydraulic pressure output unit are hydraulically cut off.
In increasing the braking force, the first hydraulic pressure output unit is made to output the hydraulic pressure toward the first wheel cylinder with the communication control valve open instead of the specific assist control, and the second hydraulic pressure is output. The assist control at the time of shutoff, which causes the hydraulic pressure output unit to output the hydraulic pressure toward the second wheel cylinder, is executed.
The vehicle braking device according to claim 1, wherein in the shutoff assist control, when the second hydraulic pressure output unit is to output the hydraulic pressure toward the reservoir, the communication control valve is opened.
The failure determination unit determines whether or not the reservoir and the second hydraulic pressure output unit are hydraulically connected via the electric cylinder.
The control unit
It is determined by the failure determination unit that the piston position of the electric cylinder is in an uncontrollable state, and that the reservoir and the second hydraulic pressure output unit are hydraulically connected via the electric cylinder. If so,
In increasing the braking force, instead of the specific assist control, the communication control valve is closed, and the first hydraulic pressure output unit outputs the hydraulic pressure toward the first wheel cylinder and the second hydraulic pressure is output. The assist control at the time of communication is executed to output the hydraulic pressure toward the second wheel cylinder to the hydraulic pressure output unit.
The communication control valve is closed when at least one of the first hydraulic pressure output unit and the second hydraulic pressure output unit outputs the hydraulic pressure toward the reservoir in the communication assist control. The vehicle braking device according to 1 or 2.
The failure determination unit determines whether or not the reservoir and the second hydraulic pressure output unit are hydraulically connected via the electric cylinder.
In the control unit, the failure determination unit determines that the piston position of the electric cylinder is in an uncontrollable state, and the reservoir and the second hydraulic output unit are hydraulically connected via the electric cylinder. The vehicle braking device according to any one of claims 1 to 3, which executes the specific assist control in increasing the braking force when it cannot be determined whether or not the braking force is applied.