JP7444010B2 - Vehicle braking device - Google Patents

Description

The present invention relates to a braking device for a vehicle.

For example, the brake system of US Pat. No. 9,205,821 includes a master cylinder device, a master cut valve, an electric cylinder, and a reservoir. The fluid chamber of the electric cylinder and the reservoir are connected through a master cut valve and a master cylinder device, and further through a check valve that only allows fluid to flow from the reservoir to the fluid chamber. In the brake-by-wire mode (hereinafter referred to as "by-wire mode"), the master cut valve is closed and fluid is supplied to the foil cylinder by the electric cylinder. When the master cut valve is closed, the connection between the foil cylinder and the reservoir is cut off, and fluid flow from the fluid chamber of the electric cylinder to the reservoir is prohibited.

US Patent No. 9205821

If the master cut valve is kept closed while the vehicle is running, if the fluid temperature rises due to friction of the brake pads, the fluid expands and the hydraulic pressure in the wheel cylinder increases. In such a case, unintended braking force may be applied to the vehicle. Therefore, keep the master cut valve open while driving, so that even if the wheel pressure rises, fluid can escape from the wheel cylinder to the reservoir via the opened master cut valve. is preferred. In this case, when operation of the brake pedal is started, the brake ECU closes the master cut valve to form a by-wire mode.

However, for example, if the brake pedal is depressed quickly (sudden braking), fluid may flow from the master cylinder device into the master cut valve due to a delay in detecting the pedal depression, etc., before the master cut valve is completely closed. through which it may be fed towards the foil cylinder. In this case, even if an attempt is made to reduce the wheel pressure to 0 by, for example, ABS control, the wheel pressure will remain equivalent to the amount of fluid ΔV supplied from the master cylinder device before the master cut valve closes.

Here, in order to forcibly reduce the wheel pressure to 0, this fluid amount ΔV of fluid is supplied to the fluid chamber of the electric cylinder which is expanded to the maximum extent and sealed. In this case, excessive fluid pressure is applied to the fluid chamber and fluid path of the electric cylinder. In other words, this liquid amount ΔV may cause damage to the electric cylinder or the liquid path.

An object of the present invention is to suppress the application of excessive hydraulic pressure to the electric cylinder and the liquid path in ABS control even if fluid is supplied from the master cylinder to the foil cylinder before the master cut valve closes. An object of the present invention is to provide a braking device for a vehicle.

In the vehicle braking device of the present invention, a master cut valve provided in a fluid path connecting a master cylinder and a wheel cylinder, and a piston driven by a first electric motor slide in the cylinder, and the piston and the A fluid chamber defined by a cylinder is connected to a portion of the fluid path closer to the foil cylinder than the master cut valve, and when the piston moves forward, the fluid in the fluid chamber is delivered to the fluid path, and the piston an electric cylinder configured such that the fluid in the liquid path flows into the liquid chamber when the fluid moves backward; a holding valve that opens and closes the passage; a pressure reducing valve that opens and closes the vacuum passage; a pressure reducing valve that connects the foil cylinder and a low pressure reservoir from which the fluid in the foil cylinder is discharged; an electric pump that sucks in fluid and discharges the fluid between the master cut valve and the holding valve in the fluid path; a pressurization control unit that operates a valve in a valve-closing direction and drives the electric cylinder to pressurize the foil cylinder; and ABS control in a state in which the foil cylinder is pressurized by the electric cylinder by the pressurization control unit. a pump operating section that operates the electric pump when the pump operating section is executed; and in a state where the electric pump is operated by the pump operating section, the more the piston in the cylinder is in the backward position, the more the electric pump is operated. a restriction control unit that limits a fluid discharge flow rate of the electric pump, the electric pump is a pump that operates in response to driving of a second electric motor different from the first electric motor, and the restriction control unit The fluid discharge flow rate is limited by controlling the rotational speed of the second electric motor .

When ABS control is executed, the master cut valve and holding valve are normally closed. Therefore, when ABS control is executed, the electric pump discharges fluid into a sealed liquid path connected to the liquid chamber of the electric cylinder. If the electric pump sucks in surplus fluid and discharges it into the sealed fluid path when the piston is at its rearmost position, i.e. when the volume of the fluid chamber is at its maximum, excessive fluid pressure will build up in the fluid path and fluid chamber. It takes.

However, according to the present invention, as the position of the piston is closer to the rear end, that is, as the volume of the liquid chamber approaches the maximum value, the fluid discharge flow rate by the electric pump decreases. Thereby, even if fluid is supplied from the master cylinder to the foil cylinder before the master cut valve closes, application of excessive hydraulic pressure to the liquid path and the liquid chamber is suppressed in ABS control. Even if the fluid discharge flow rate is restricted to 0, for example, during ABS control, if the pressure reducing valve is opened, the wheel pressure will drop by the amount of fluid that escapes from the wheel cylinder to the low pressure reservoir.

FIG. 1 is a configuration diagram of a vehicle braking device according to the present embodiment. It is a block diagram of the downstream unit of this embodiment. FIG. 3 is a conceptual diagram for explaining a predetermined area of a piston according to the present embodiment. It is a flowchart for explaining the control example of this embodiment.

Embodiments of the present invention will be described below based on the drawings. As shown in FIG. 1, the vehicle braking device 1 of this embodiment includes an upstream unit 11, a downstream unit 3, wheel cylinders 81, 82, 83, 84, a first brake ECU 91, and a second brake ECU 92. , is equipped with. The first brake ECU 91 mainly controls the upstream unit 11. The second brake ECU 92 mainly controls the downstream unit 3.

The upstream unit 11 mainly includes a master cylinder device 2, a reservoir 26, a first master cut valve 41, a second master cut valve 42, and an electric cylinder 5. The master cylinder device 2 is connected to the reservoir 26 and is configured to be able to supply fluid in response to brake operation. Brake operation means that the brake pedal Z is operated by the driver. The master cylinder device 2 includes a master cylinder 21, a first master piston 22, a second master piston 23, and biasing members 24 and 25.

The master cylinder 21 is a cylindrical member with a bottom. The master cylinder 21 is formed with input ports 211 and 212 and output ports 213 and 214. Input ports 211 and 212 are connected to reservoir 26. Inside the master cylinder 21, a first master chamber 21a and a second master chamber 21b (hereinafter also referred to as "master chambers 21a, 21b") are formed.

The first master piston 22 and the second master piston 23 (hereinafter also referred to as "master pistons 22, 23") are piston members disposed within the master cylinder 21. The master pistons 22 and 23 slide within the master cylinder 21 in response to the operation of the brake pedal Z. The first master piston 22 and the brake pedal Z are mechanically connected. Hereinafter, the direction from the first master piston 22 toward the brake pedal Z will be referred to as the rear, and the opposite direction will be referred to as the front.

The second master piston 23 is arranged in front of the first master piston 22. The first master chamber 21a is partitioned by a master cylinder 21 and master pistons 22 and 23. The second master chamber 21b is partitioned by the master cylinder 21 and the second master piston 23.

A through hole 221 is formed in the first master piston 22, and a through hole 231 is formed in the second master piston 23. When the master pistons 22 and 23 are located at the initial position (rear end position), the through hole 221 and the input port 211 communicate with each other, and the through hole 231 and the input port 212 communicate with each other. That is, when the master pistons 22 and 23 are located at the initial position, the master chamber 21a and the reservoir 26 communicate with each other through the through hole 221 and the input port 211, and the master chamber 21b communicates with the reservoir 26 through the through hole 231 and the input port 212. It communicates with the reservoir 26.

The biasing member 24 is disposed in the first master chamber 21a and biases the first master piston 22 toward the initial position. The biasing member 25 is arranged in the second master chamber 21b and biases the second master piston 23 toward the initial position.

The master cylinder device 2 is configured so that the first master chamber 21a and the second master chamber 21b have the same pressure. Communication between the reservoir 26 and the master chambers 21a, 21b is cut off when the master pistons 22, 23 move forward by a predetermined amount from their initial positions. The output port 213 connects the first master chamber 21a and the first liquid path 61. The output port 214 connects the second master chamber 21b and the second liquid path 62. When the master pistons 22, 23 move forward, the volumes of the master chambers 21a, 21b, which are isolated from the reservoir 26, become smaller, and fluid is output from the output ports 213, 214.

The first liquid path 61 is a liquid path that connects the first master chamber 21a of the master cylinder device 2 and the foil cylinders 81 and 82. The second liquid path 62 is a liquid path that connects the second master chamber 21b of the master cylinder device 2 and the foil cylinders 83 and 84. The first liquid path 61 and the second liquid path (hereinafter also referred to as "liquid paths 61 and 62") are liquid paths that connect the master cylinder device 2 and the foil cylinders 81 to 84.

The first master cut valve 41 is a normally open electromagnetic valve that is provided in the first liquid path 61 and opens in a non-energized state. The second master cut valve 42 is a normally open type solenoid valve provided in the second liquid path 62. The first master cut valve 41 and the second master cut valve 42 (hereinafter also referred to as "master cut valves 41, 42") are configured so that the hydraulic pressure on the foil cylinders 81 to 84 side acts in the direction of closing the valve body. , are arranged in corresponding liquid passages 61 and 62, respectively.

The stroke simulator 27 is connected to a portion of the first liquid path 61 between the input port 211 and the first master cut valve 41 via the liquid path 611 . The liquid path 611 is provided with a simulator cut valve 28 which is a normally closed electromagnetic valve that closes in a non-energized state. When the simulator cut valve 28 opens, the first master chamber 21a and the stroke simulator 27 communicate with each other. The stroke simulator 27 is a device that generates a reaction force against a brake operation. A pressure sensor 71 is connected to a portion of the second liquid path 62 between the input port 212 and the second master cut valve 42 .

The electric cylinder 5 is configured to be able to supply fluid by sliding a piston 53 within the cylinder 51 . The electric cylinder 5 has a portion 61a between the first master cut valve 41 and the foil cylinders 81, 82 in the first liquid path 61, and a portion 61a between the second master cut valve 42 and the foil cylinders 83, 84 in the second liquid path 62. It is connected to the portion 62a between the two. More specifically, the portion 61a of the first liquid path 61 is a portion of the first liquid path 61 between the first master cut valve 41 and the downstream unit 3. A portion 62a of the second liquid path 62 is a portion of the second liquid path 62 between the second master cut valve 42 and the downstream unit 3.

The electric cylinder 5 includes a cylinder 51, an electric motor 52, a piston 53, a liquid chamber 54, and a biasing member 55. The electric cylinder 5 is a single type electric cylinder in which a single liquid chamber 54 is formed within the cylinder 51. In the following description of the electric cylinder 5, the direction in which the piston 53 makes the liquid chamber 54 smaller is referred to as the front, and the direction in which the piston 53 makes the liquid chamber 54 larger is referred to as the rear.

The cylinder 51 is a bottomed cylindrical member with ports 511 and 512 formed at the front end. The electric motor 52 is connected to the piston 53 via a linear motion mechanism 52a that converts rotational motion into linear motion. The piston 53 slides within the cylinder 51 by driving the electric motor 52. The liquid chamber 54 is partitioned by the cylinder 51 and the piston 53, and its volume changes according to the movement of the piston 53. The biasing member 55 is a spring that is disposed in the liquid chamber 54 and biases the piston 53 toward the initial position. When the electric motor 52 is not driven, the biasing force of the biasing member 55 positions the piston 53 at the initial position.

A third liquid path 63 is connected to the port 511 . The third liquid path 63 is a liquid path that connects the port 511 and a portion 61a of the first liquid path 61. The third liquid path 63 is provided with a first cut valve 43 that is a normally closed electromagnetic valve. A fourth liquid path 64 branches from the third liquid path 63 .

The fourth liquid path 64 is a liquid path that connects a portion of the third liquid path 63 between the port 511 and the first cut valve 43 and a portion 62a of the second liquid path 62. The fourth liquid path 64 is provided with a second cut valve 44 that is a normally closed electromagnetic valve. When the first cut valve 43 opens, the liquid chamber 54 and the foil cylinders 81 and 82 communicate with each other via the port 511 and the downstream unit 3. When the second cut valve 44 opens, the liquid chamber 54 and the foil cylinders 83 and 84 communicate with each other via the port 511 and the downstream unit 3.

A fifth liquid path 65 is connected to the port 512 . The fifth liquid path 65 is a liquid path that connects the reservoir 26 and the port 512. The fifth liquid path 65 is provided with a check valve 45 that prohibits fluid from flowing from the liquid chamber 54 to the reservoir 26 . For example, when the liquid chamber 54 becomes negative pressure due to the retraction of the piston 53, fluid is supplied from the reservoir 26 to the liquid chamber 54 via the liquid path 65 and the check valve 45. Note that the stroke simulator 27, simulator cut valve 28, first cut valve 43, and second cut valve 44 are included in the upstream unit 11.

(downstream unit)
The downstream unit 3 will be explained with reference to FIGS. 1 and 2. The downstream unit 3 is a so-called ESC actuator, and can independently adjust the hydraulic pressure of each of the foil cylinders 81 to 84. The downstream unit 3 includes a first hydraulic pressure output section 31 configured to be able to adjust the pressure of the foil cylinders 81 and 82, and a second hydraulic pressure output section 32 configured to be able to adjust the pressure of the foil cylinders 83 and 84. We are prepared.

The first hydraulic pressure output section 31 is arranged between the connecting portion of the first liquid path 61 and the third liquid path 63 and the foil cylinders 81 and 82. The second hydraulic pressure output section 32 is arranged between the connecting portion of the second liquid path 62 and the fourth liquid path 64 and the foil cylinders 83 and 84. The first hydraulic pressure output section 31 and the second hydraulic pressure output section 32 are independent from each other on the hydraulic circuit within the downstream unit 3. 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 position of the foil cylinders 81 to 84 with respect to the downstream unit 3 is referred to as downstream.

Fluid is supplied to the first hydraulic pressure output section 31 from the upstream unit 11 . The first hydraulic pressure output section 31 is configured to be able to increase the hydraulic pressure of the foil cylinders 81 and 82 based on the basic hydraulic pressure generated by the upstream unit 11. The first hydraulic pressure output section 31 is configured to pressurize the foil cylinders 81 and 82 by generating a differential pressure between the input hydraulic pressure and the hydraulic pressure of the foil cylinders 81 and 82.

As shown in FIG. 2, the first hydraulic pressure output section 31 includes a liquid path 311, a pump liquid path 315a, a pressure sensor 75, a differential pressure control valve 312, a check valve 312a, a holding valve 313, and a check valve 312a. It includes a valve 313a, a pressure reducing fluid path 314a, a pressure reducing valve 314, a pump 315, an electric motor 316, a low pressure reservoir 317, and a reflux fluid path 317a. Pump 315 and electric motor 316 constitute an electric pump.

The liquid path 311 is a liquid path that connects a portion 61a of the first liquid path 61 and the foil cylinder 81. The liquid path 311 is a part of the first liquid path 61 , and is a portion of the first liquid path 61 located inside the downstream unit 3 . The liquid path 311 includes a branch part X connected to the pump liquid path 315a. The liquid path 311 branches at the branching portion X into a liquid path 311 connected to the foil cylinder 81 and a liquid path 311a connected to the foil cylinder 82. Since the configurations on the two liquid paths 311 are similar, only the liquid path 311 connected to the foil cylinder 81 will be described.

The pressure sensor 75 is provided on the upstream unit 11 side of the differential pressure control valve 312 in the liquid path 311 . The pressure detected by the pressure sensor 75 corresponds to the hydraulic pressure input from the upstream unit 11 to the first hydraulic pressure output section. Data detected by the pressure sensor 75 is transmitted to the second brake ECU 92.

The differential pressure control valve 312 is a normally open linear solenoid valve provided in the liquid path 311 between the branch section X and the pressure sensor 75. By controlling the opening degree of the differential pressure control valve 312, a differential pressure can be generated between upstream and downstream sides of the differential pressure control valve 312.

The check valve 312a is provided in parallel to the differential pressure control valve 312. The check valve 312a is configured to only allow fluid to flow from the upstream side to the downstream side.

The holding valve 313 is a normally open electromagnetic valve provided in the liquid path 311 between the branch part X and the foil cylinder 81. That is, the holding valve 313 is provided in the liquid path 311, which is a part of the first liquid path 61, closer to the foil cylinder 81 than the position (branch portion X) where fluid is supplied by the electric cylinder 5.

The check valve 313a is provided in parallel to the holding valve 313. The check valve 313a is configured to allow fluid to flow only from the downstream side to the upstream side.

The reduced pressure fluid path 314 a is a fluid path that connects a portion of the fluid path 311 between the holding valve 313 and the foil cylinder 81 and the low pressure reservoir 317 . A pressure reducing valve 314 is provided on the pressure reducing fluid path 314a. The pressure reducing valve 314 is a normally closed electromagnetic valve provided in the pressure reducing fluid path 314a. When the pressure reducing valve 314 is in the open state, the fluid in the foil cylinder 81 can flow into the low pressure reservoir 317 via the pressure reducing fluid path 314a. Therefore, by opening the pressure reducing valve 314, the pressure in the foil cylinder 81 can be reduced.

The low pressure reservoir 317 is a well-known pressure regulating reservoir that stores fluid, and is connected to the reduced pressure liquid path 314a and the reflux liquid path 317a. The reflux liquid path 317a is a liquid path that connects a portion of the liquid path 311 between the pressure sensor 75 and the differential pressure control valve 312 and the low pressure reservoir 317. That is, the low pressure reservoir 317 is connected to a portion of the liquid path 311 between the holding valve 313 and the foil cylinder 81 via the pressure reducing valve 314. The fluid in the low pressure reservoir 317 is sucked in by the operation of the pump 315. When the amount of fluid in the low pressure reservoir 317 decreases, the valve in the low pressure reservoir 317 opens, and fluid is supplied to the low pressure reservoir 317 from the portion 61a of the first fluid path 61 via the reflux fluid path 317a.

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

The pump 315 is a pump that operates according to the drive of the electric motor 316, and is, for example, a well-known piston pump or a gear pump. The suction side of the pump 315 is connected to the low pressure reservoir 317, and the discharge side of the pump 315 is connected to the branch part X. When the pump 315 operates, it sucks fluid in the low pressure reservoir 317 and supplies the fluid to the branch section X. For example, when each holding valve 313 is closed and the fluid in the low pressure reservoir 317 is pumped up by driving the pump 315, the fluid discharged by the pump 315 is supplied to the liquid chamber 54 of the electric cylinder 5 via the branch part X. When the pump 315 attempts to supply fluid to the electric cylinder 5 when the piston 53 is at the initial position, excessive hydraulic pressure is applied to the electric cylinder 5.

The first hydraulic pressure output section 31 is configured to be able to pressurize the foil cylinders 81 and 82 based on hydraulic pressure input from the upstream side by operating various electromagnetic valves and pumps. The second hydraulic pressure output section 32 has the same configuration as the first hydraulic pressure output section 31 except that the pressure sensor 75 is not provided, so a description thereof will be omitted. Like the first hydraulic pressure output section 31, the second hydraulic pressure output section 32 is also configured to be able to increase the hydraulic pressure of the foil cylinders 83 and 84 based on the base hydraulic pressure.

In this way, the vehicle braking device 1 includes the master cut valves 41 and 42 provided in the fluid passages 61 and 62 connecting the master cylinder 21 and the wheel cylinders 81 to 84, and the piston 53 driven by the electric motor 52. slides inside the cylinder 51, and a liquid chamber 54 defined by the piston 53 and the cylinder 51 is connected to a portion of the liquid paths 61 and 62 closer to the foil cylinders 81 to 84 than the master cut valves 41 and 42, An electric cylinder configured such that when the piston 53 moves forward, the fluid in the liquid chamber 54 is sent to the liquid passages 61 and 62, and when the piston 53 moves backward, the fluid in the liquid passages 61 and 62 flows into the liquid chamber 54. 5, a holding valve 313 that is provided closer to the foil cylinders 81 to 84 than the position connected to the electric cylinder 5 in the liquid passages 61 and 62 and opens and closes the liquid passages 61 and 62, and a holding valve 313 that opens and closes the liquid passages 61 and 62; A pressure reducing valve 314 is provided in the pressure reducing fluid path 314a that connects the low pressure reservoir 317 from which the fluid in the cylinders 81 to 84 is discharged, and opens and closes the pressure reducing fluid path 314a. At 61 and 62, an electric pump (315, 316) that discharges fluid between the master cut valves 41, 42 and the holding valve 313, a first brake ECU 91, and a second brake ECU 92 are provided.

(Brake ECU)
The first brake ECU 91 and the second brake ECU 92 (hereinafter also referred to as "brake ECUs 91 and 92") are electronic control units each including a CPU and a memory. Each brake ECU 91, 92 includes one or more processors that execute various controls. The first brake ECU 91 and the second brake ECU 92 are separate ECUs, and are connected to each other so that they can communicate information (control information, etc.) with each other.

The first brake ECU 91 controls the electric cylinder 5 and each electromagnetic valve 28, 41 to 44 based on detected values of various sensors including pressure sensors 71 and 72. The first brake ECU 91 establishes a by-wire mode in response to a brake operation, and controls the electric cylinder 5 to increase and decrease the pressure in the wheel cylinders 81 to 84. The second brake ECU 92 controls the downstream unit 3 based on detection values of various sensors including the pressure sensor 75. The second brake ECU 92 drives the downstream unit 3 depending on the situation, and executes, for example, ABS control (also called anti-skid control), ESC control, etc.

(By-wire mode)
The first brake ECU 91 includes a valve control section 911 and a pressurization control section 912. The valve control unit 911 controls each electromagnetic valve 28, 41 to 44, and switches the control mode between a by-wire mode and a non-by-wire mode. In the by-wire mode, the master cut valves 41 and 42 are closed, and the simulator cut valve 28, the first cut valve 43, and the second cut valve 44 are open.

For example, the valve control unit 911 opens the simulator cut valve 28 when the first brake ECU 91 is started, closes the master cut valves 41 and 42 when a brake operation is started, and closes the first cut valve 43 and the second cut valve. 44 (hereinafter also referred to as "cut valves 43, 44"). That is, when a brake operation is started, the master cylinder device 2 and the wheel cylinders 81 to 84 are hydraulically disconnected, and the by-wire mode is in which the pressure of the wheel cylinders 81 to 84 is regulated by at least one of the electric cylinder 5 and the downstream unit 3. is formed. In this way, the valve control unit 911 closes the master cut valves 41 and 42 when a brake operation is started.

In the by-wire mode, the pressurization control unit 912 drives the electric motor 52 to move the piston 53 according to the target pressure calculated based on the brake operation. In this way, after the valve control unit 911 establishes the by-wire mode (closing the master cut valves 41, 42, etc.), the pressurization control unit 912 adjusts the output pressure of the electric cylinder 5 to the target pressure according to the brake operation. Adjust to.

In this way, the first brake ECU 91 operates the master cut valves 41 and 42 in the valve closing direction when the brake pedal Z connected to the master cylinder 21 is operated, and drives the electric cylinder 5 to close the wheel cylinder. 81 to 84 are pressurized. In other words, when a brake operation is started, the first brake ECU 91 operates the master cut valves 41 and 42 in the valve closing direction, and adjusts the output pressure of the electric cylinder 5 to a target pressure according to the brake operation.

In the non-by-wire mode, the master cut valves 41 and 42 are open, the first cut valve 43 and the second cut valve 44 are closed, and the simulator cut valve 28 is closed. When the master cut valves 41 and 42 open, the master cylinder device 2 and the foil cylinders 81 to 84 communicate with each other. For example, if the electromagnetic valves 41 to 44, 28 and the electric cylinder 5 do not operate due to a power failure, etc., the non-by-wire mode will be maintained even if the brake operation is started, and fluid will flow from the master cylinder device 2 to the wheel in response to the brake operation. It is supplied to cylinders 81-84.

When the master pistons 22 and 23 are at the initial position in the non-by-wire mode, the reservoir 26 communicates with the foil cylinders 81 to 84 and the electric cylinder 5 via the master cylinder 21. When each electromagnetic valve 41 to 44 is open, the liquid chamber 54 of the electric cylinder 5 communicates with the reservoir 26 via the third liquid path 63, the first liquid path 61, and the first master chamber 21a, and It communicates with the reservoir 26 via the fourth liquid path 64, the second liquid path 62, and the second master chamber 21b.

(Limit control of fluid discharge flow rate)
The second brake ECU 92 includes a pump actuation section 921, a restriction control section 922, and an increase control section 923. The pump operating section 921 operates the pump 315 when the ABS control is executed with the wheel cylinders 81 to 84 pressurized by the electric cylinder 5 by the pressurization control section 912. In ABS control, the second brake ECU 92 executes pressure reduction control to control the downstream unit 3 to reduce the wheel pressure. When ABS control is executed, pump 315 is activated.

The restriction control section 922 limits the fluid discharge flow rate by the pump 315 as the position of the piston 53 in the cylinder 51 is on the backward side (rearward) while the pump 315 is being operated by the pump operation section 921 . The restriction control unit 922 decreases the fluid discharge flow rate, for example, stepwise or functionally as the position of the piston 53 becomes more rearward. The fluid discharge flow rate can be controlled by controlling the rotation speed of the electric motor 316. Note that the discharge flow rate means the discharge amount per unit time.

In the example of this embodiment, the restriction control unit 922 stops the pump 315 when the position of the piston 53 is within a predetermined region while the pump 315 is being operated by the pump operating unit 921 . Here, the predetermined area in this embodiment is an area from a predetermined position on the forward movement side of the initial position of the piston 53 to the initial position. In other words, the predetermined region is, for example, a region between the initial position of the piston 53 and a position where the piston 53 has moved forward by a predetermined amount from the initial position, with the front end of the piston 53 as a reference. When the position of the piston 53 (reference position, for example, front end position) is in a predetermined area within the cylinder 51, the restriction control unit 922 stops the operation of the pump 315 and sets the fluid discharge flow rate to zero. It can also be said that the restriction control unit 922 limits the fluid discharge flow rate when the position of the piston 53 is behind (including the predetermined position) a predetermined position. In this way, the restriction control section 922 of the present embodiment controls the pump 315 when the position of the piston 53 with respect to the cylinder 51 is in a predetermined region due to the retraction of the piston 53 while the pump 315 is being operated by the pump operation section 921. stop.

As shown in FIG. 3, the predetermined region is set on the rear end side of the cylinder 51, and includes a position where the piston 53 is advanced by a predetermined amount from its initial position. The brake ECUs 901 and 902 calculate the position of the piston 53 based on the detected value of the rotation angle sensor 56 of the electric motor 52, for example. Note that the predetermined area may be set at the initial position of the piston 53 (ie, the position where the volume of the liquid chamber 54 is at its maximum value).

Even after the pump 315 has stopped, by opening the pressure reducing valve 314 and communicating the foil cylinders 81 to 84 with the low pressure reservoir 317, the foil cylinder 314 is kept open until the foil pressure and the pressure in the low pressure reservoir 317 become the same pressure. Fluids 81-84 are discharged to low pressure reservoir 317. Fluid is stored in the low pressure reservoir 317.

The increase control unit 923 increases the fluid discharge flow rate of the pump 315 when the ABS control ends with the fluid discharge flow rate of the pump 315 being restricted by the restriction control unit 922. In this embodiment, the pump 315 is stopped when the piston 53 is located in a predetermined area during ABS control. After the ABS control is completed and the pressure reducing valve 314 is closed and the holding valve 313 is opened, the increase control unit 923 operates the pump 315 for a predetermined time, sucks the fluid remaining in the low pressure reservoir 317, and then closes the pressure reducing valve 314 and opens the holding valve 313. , 62. At this time, even if the master cut valves 41 and 42 are closed and the piston 53 is at the initial position, the holding valve 313 is open, so the discharged fluid is supplied to the foil cylinders 81 to 84, and the fluid passages 61 and 62 are Excessive pressure is not applied to the liquid chamber 54 of the electric cylinder 5. In other words, excess fluid can be discharged from the low pressure reservoir 317.

In addition, in the configuration of the downstream unit 3 of this embodiment, if fluid remains in the low pressure reservoir 317 in a situation where the brake operation is completed and the master cut valves 41 and 42 are opened, due to the structure (the low pressure reservoir 317), the fluid in the low pressure reservoir 317 is automatically returned to the reservoir 26 via the liquid passages 61 and 62.

An example of pump control according to this embodiment will be explained with reference to FIG. 4. The vehicle braking device 1 determines whether or not ABS control is being performed (S101), and if ABS control is being performed (S101: Yes), determines whether the position of the piston 53 of the electric cylinder 5 is within a predetermined region. (S102). If the position of the piston 53 is not in the predetermined region (S102: No), the vehicle braking device 1 operates the pump (S103). On the other hand, if the position of the piston 53 is within the predetermined region (S102: Yes), the vehicle braking device 1 stops the pump 315 (S104). In step S101, if the ABS control is not in progress (S101: No), the process proceeds to S105, and the vehicle braking device 1 determines whether a predetermined time or more has elapsed after the ABS control ended (S105). If the predetermined time or more has not elapsed (S105: No), the vehicle braking device 1 operates the pump (S106). On the other hand, if the predetermined time or more has elapsed (S105: Yes), the vehicle braking device 1 stops the pump 315 (S107). The predetermined time may be set, for example, to a time during which the pump 315 can suck in surplus fluid estimated in advance.

(Effects of this embodiment)
When ABS control is executed, the master cut valves 41 and 42 are closed, and the holding valve 313 is closed when the hydraulic pressure of the foil cylinders 81 to 84 is maintained and reduced, other than when the pressure is increased. When ABS control is executed, the pump 315 discharges fluid into the sealed liquid passages 61 and 62 connected to the liquid chamber 54 of the electric cylinder 5. When the holding valve 313 is closed and the piston 53 is at its rearmost position, that is, when the volume of the liquid chamber 54 is at its maximum, the pump 315 sucks in excess fluid and fills the sealed liquid passages 61 and 62. When the liquid is discharged, excessive liquid pressure is applied to the liquid passages 61 and 62 and the liquid chamber 54.

However, according to the present embodiment, the fluid discharge flow rate of the pump 315 decreases as the position of the piston 53 is closer to the rear end, that is, as the volume of the liquid chamber 54 approaches the maximum value. As a result, even if fluid is supplied from the master cylinder 21 to the foil cylinders 81 to 84 before the master cut valves 41 and 42 are closed, excessive fluid pressure to the fluid passages 61 and 62 and the fluid chamber 54 can be prevented during ABS control. The application of is suppressed. Even if the fluid discharge flow rate is restricted to zero, for example, during ABS control, if the pressure reducing valve 314 is opened, the wheel pressure will drop by the amount of fluid that escapes from the wheel cylinders 81 to 84 to the low pressure reservoir. In other words, even if the pump 315 is stopped, the wheel pressure can be brought close to 0, and the wheel lock avoidance function by ABS control is maintained.

Further, in this embodiment, the front end of the predetermined region where the fluid discharge flow rate is restricted is set at a position where the piston 53 is advanced by a predetermined amount from the initial position. That is, in this embodiment, the fluid discharge flow rate is limited before the volume of the liquid chamber 54 reaches its maximum. This suppresses overshoot (fluid discharge by the pump 315 after the volume of the liquid chamber 54 reaches the maximum) even if there is a delay in operation with respect to the stop command of the pump 315. In other words, application of excessive hydraulic pressure to the liquid channels 61 and 62 and the liquid chamber 54 can be suppressed more reliably.

Note that, for example, if some overshoot is within the permissible range (for example, below the permissible pressure resistance of the liquid chamber 54) or if the control responsiveness of the pump 315 is high, the predetermined region is the initial position of the piston 53 (the volume of the liquid chamber 54). may be set at a position where the maximum value is reached. Thereby, the amount of fluid remaining in the low pressure reservoir 317 can be minimized. The predetermined area is set such that, for example, (1/2 of the maximum volume of the liquid chamber 54)<(volume of the liquid chamber 54 when the piston 53 is in the predetermined area)≦(maximum volume of the liquid chamber 54). be done. The front end of the predetermined region in this embodiment is set at a position close to the position where the volume of the liquid chamber 54 is maximum (the initial position of the piston 53).

(others)
The present invention is not limited to the above embodiments. For example, the downstream unit 3 is not limited to an ESC actuator, but may be an ABS actuator without a pressurizing function (eg, differential pressure control valve 312, etc.). Further, the low pressure reservoir 317 may be a reservoir without a valve mechanism. In other words, a well-known actuator can be used for the downstream unit 3. Furthermore, in the electric cylinder 5, the piston 53 can be moved backward by driving the electric motor 52, so the biasing member 55 may be omitted.

Further, the increase control section 923 controls the master cut valves 41 and 42 when the brake pedal (corresponding to a "brake operating member") Z is switched from an operated state to a non-operated state while the fluid discharge flow rate is restricted by the limit control section 922. When the valve is opened, the fluid discharge flow rate may be increased. For example, if the low pressure reservoir 317 of the downstream unit 3 is a simple reservoir without a valve, the fluid in the reservoir will not automatically return to the fluid paths 61, 62. Especially in such a configuration, the above control is effective.

Further, the restriction control unit 922 may gradually reduce the fluid discharge flow rate of the pump 315 as the piston 53 moves back, instead of stopping the pump 315 depending on the position of the piston 53. During ABS control, for example, while the piston 53 is retracting from a predetermined position to the initial position, the restriction control unit 922 gradually controls the flow rate as the piston 53 retreats so that the fluid discharge flow rate of the pump 315 becomes 0 at the initial position. The fluid discharge flow rate may be reduced. According to this configuration, the amount of fluid remaining in the low pressure reservoir 317 can be minimized and overshoot can be suppressed.

In this way, the fluid discharge flow rate may be reduced functionally (eg, linearly). As an example, the restriction control unit 922 starts reducing the fluid discharge flow rate when the piston 53 retreats to a set position, and stops the pump 315 when the piston 53 reaches the initial position (or a position advanced by a predetermined amount from the initial position). You may.

DESCRIPTION OF SYMBOLS 1... Vehicle braking device, 2... Master cylinder device, 21... Master cylinder, 22, 23... Master piston, 313... Holding valve, 315... Pump, 317... Low pressure reservoir, 41, 42... Master cut valve, 5... Electric Cylinder, 51...Cylinder, 52...Electric motor, 53...Piston, 54...Liquid chamber, 61, 62...Liquid path, 91...First brake ECU (pressurization control unit), 921...Pump operation unit, 922...Limit control Section, 923...Increase control section.

Claims (5)

A master cut valve provided in a liquid path connecting the master cylinder and the foil cylinder,
A piston driven by a first electric motor slides within the cylinder, and a liquid chamber defined by the piston and the cylinder is connected to a portion of the liquid path closer to the foil cylinder than the master cut valve. an electric cylinder configured such that when the piston moves forward, the fluid in the liquid chamber is delivered to the liquid path, and when the piston moves back, the fluid in the liquid path flows into the liquid chamber;
a holding valve that is provided in the liquid path closer to the foil cylinder than a position connected to the electric cylinder and opens and closes the liquid path;
a pressure reducing valve provided in a pressure reducing fluid path connecting the foil cylinder and a low pressure reservoir from which fluid in the foil cylinder is discharged, and opening and closing the pressure reducing fluid path;
an electric pump that sucks fluid from the low pressure reservoir and discharges the fluid between the master cut valve and the holding valve in the liquid path;
a pressure control unit that operates the master cut valve in a valve closing direction when a brake operating member connected to the master cylinder is operated, and drives the electric cylinder to pressurize the foil cylinder;
a pump operating unit that operates the electric pump when ABS control is executed with the foil cylinder being pressurized by the electric cylinder by the pressurization control unit;
a restriction control unit that limits the fluid discharge flow rate of the electric pump as the position of the piston in the cylinder is on the backward side while the electric pump is operated by the pump operation unit;
Equipped with
The electric pump is a pump that operates in accordance with the drive of a second electric motor different from the first electric motor,
The restriction control unit is a vehicle braking device that limits the fluid discharge flow rate by controlling the rotation speed of the second electric motor . A master cut valve provided in a liquid path connecting the master cylinder and the foil cylinder,
A piston driven by an electric motor slides inside the cylinder, and a liquid chamber defined by the piston and the cylinder is connected to a portion of the liquid path closer to the foil cylinder than the master cut valve, and an electric cylinder configured such that when the piston moves forward, the fluid in the liquid chamber is delivered to the liquid path, and when the piston moves back, the fluid in the liquid path flows into the liquid chamber;
a holding valve that is provided in the liquid path closer to the foil cylinder than a position connected to the electric cylinder and opens and closes the liquid path;
a pressure reducing valve provided in a pressure reducing fluid path connecting the foil cylinder and a low pressure reservoir from which fluid in the foil cylinder is discharged, and opening and closing the pressure reducing fluid path;
an electric pump that sucks fluid from the low pressure reservoir and discharges the fluid between the master cut valve and the holding valve in the liquid path;
a pressure control unit that operates the master cut valve in a valve closing direction when a brake operating member connected to the master cylinder is operated, and drives the electric cylinder to pressurize the foil cylinder;
a pump operating unit that operates the electric pump when ABS control is executed with the foil cylinder being pressurized by the electric cylinder by the pressurization control unit;
a restriction control unit that limits the fluid discharge flow rate of the electric pump as the position of the piston in the cylinder is on the backward side while the electric pump is operated by the pump operation unit;
Equipped with
A braking device for a vehicle, further comprising an increase control section that increases the fluid discharge flow rate when the ABS control ends with the fluid discharge flow rate being restricted by the restriction control section. A master cut valve provided in a liquid path connecting the master cylinder and the foil cylinder,
A piston driven by an electric motor slides inside the cylinder, and a liquid chamber defined by the piston and the cylinder is connected to a portion of the liquid path closer to the foil cylinder than the master cut valve, and an electric cylinder configured such that when the piston moves forward, the fluid in the liquid chamber is delivered to the liquid path, and when the piston moves back, the fluid in the liquid path flows into the liquid chamber;
a holding valve that is provided in the liquid path closer to the foil cylinder than a position connected to the electric cylinder and opens and closes the liquid path;
a pressure reducing valve provided in a pressure reducing fluid path connecting the foil cylinder and a low pressure reservoir from which fluid in the foil cylinder is discharged, and opening and closing the pressure reducing fluid path;
an electric pump that sucks fluid from the low pressure reservoir and discharges the fluid between the master cut valve and the holding valve in the liquid path;
a pressure control unit that operates the master cut valve in a valve closing direction when a brake operating member connected to the master cylinder is operated, and drives the electric cylinder to pressurize the foil cylinder;
a pump operating unit that operates the electric pump when ABS control is executed with the foil cylinder being pressurized by the electric cylinder by the pressurization control unit;
a restriction control unit that limits the fluid discharge flow rate of the electric pump as the position of the piston in the cylinder is on the backward side while the electric pump is operated by the pump operation unit;
Equipped with
an increase control unit that increases the fluid discharge flow rate when the brake operating member switches from an operating state to a non-operation state and the master cut valve opens while the fluid discharge flow rate is restricted by the restriction control unit; The vehicle further comprises a braking device for a vehicle . A master cut valve provided in a liquid path connecting the master cylinder and the foil cylinder,
A piston driven by an electric motor slides inside the cylinder, and a liquid chamber defined by the piston and the cylinder is connected to a portion of the liquid path closer to the foil cylinder than the master cut valve, and an electric cylinder configured such that when the piston moves forward, the fluid in the liquid chamber is delivered to the liquid path, and when the piston moves back, the fluid in the liquid path flows into the liquid chamber;
a holding valve that is provided in the liquid path closer to the foil cylinder than a position connected to the electric cylinder and opens and closes the liquid path;
a pressure reducing valve provided in a pressure reducing fluid path connecting the foil cylinder and a low pressure reservoir from which fluid in the foil cylinder is discharged, and opening and closing the pressure reducing fluid path;
an electric pump that sucks fluid from the low pressure reservoir and discharges the fluid between the master cut valve and the holding valve in the liquid path;
a pressure control unit that operates the master cut valve in a valve closing direction when a brake operating member connected to the master cylinder is operated, and drives the electric cylinder to pressurize the foil cylinder;
a pump operating unit that operates the electric pump when ABS control is executed with the foil cylinder being pressurized by the electric cylinder by the pressurization control unit;
a restriction control unit that limits the fluid discharge flow rate of the electric pump as the position of the piston in the cylinder is on the backward side while the electric pump is operated by the pump operation unit;
Equipped with
The restriction control section is configured to stop the electric pump when the piston is moved back and the position of the piston relative to the cylinder is in a predetermined area while the electric pump is being operated by the pump operation section. Braking device. The vehicle braking device according to any one of claims 1 to 4, wherein the restriction control section gradually reduces the fluid discharge flow rate as the piston retreats.

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