Damping device, hydraulic control unit, and brake system

Abstract

An attenuation device (100) includes a first liquid chamber (S1) configured to communicate with an inlet port (P1) through a first opening (PO1); a second liquid chamber (S2) configured to communicate with the first liquid chamber (S1) through a communication hole (113c) and with an outlet port (P2) through a second opening (PO2); a first piston (121) provided in the first liquid chamber (S1); a first biasing member (141) configured to bias the first piston (121) toward side of the first opening (PO1); a bore portion (121e) formed in the first piston (121) to be recessed from side of the second opening (PO2) toward the side of the first opening (PO1); a second piston (122) provided in the bore portion (121e); a second biasing member (142) configured to bias the second piston (122) toward the side of the first opening (PO1); a first through hole (122c) provided through the second piston (122) from the side of the first opening (PO1) to the side of the second opening (PO2); a first valve body (151) capable of opening and closing the side of the first opening (PO1) of the first through hole (122c); a third biasing member (143) configured to bias the first valve body (151) toward the side of the second opening (PO2); a protruding member (161) that includes a protruding portion (161c) capable of being inserted into the first through hole (122c) and capable of coming into contact with the first valve body (151), and provided at part of the first piston (121) on the side of the second opening (PO2) with respect to the second piston (122); a second valve body (152) that is capable of opening and closing the side of the second opening (PO2) of the communication hole (113c); and a fourth biasing member (144) configured to bias the second valve body (152) toward the side of the first opening (PO1).

Description

Technical Field

[0001] The present invention relates to a damping device, a hydraulic control unit, and a braking system.

Background Art

[0002] In conventional vehicles, a hydraulic control unit is provided to control the braking force generated on the wheels. For example, as disclosed in Patent Document 1, a plurality of valves and a pump are provided in the flow path within the hydraulic control unit. In such a hydraulic control unit, for example, in anti-lock brake control or skid prevention control, etc., control is performed to set the opening and closing states of each valve to a specific state and drive the pump.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the hydraulic control unit, a reciprocating plunger pump is mainly used as the pump. Therefore, the pumping of the brake fluid by the pump is performed intermittently. Thus, when the pump is driven, a pressure pulsation occurs, which is a phenomenon in which the hydraulic pressure of the brake fluid pulsates in the flow path within the hydraulic control unit. The sound generated by such pressure pulsation may be felt as noise by the vehicle occupants and may be a factor that impairs comfort. Therefore, from the viewpoint of improving comfort, it is desired to appropriately attenuate the pressure pulsation of the hydraulic control unit.

[0005] Therefore, in view of such problems, an object of the present invention is to provide a damping device, a hydraulic control unit, and a braking system capable of attenuating the pressure pulsation of the hydraulic control unit. [Means for solving the problem]

[0006] To solve the above problems, the damping device is provided in a hydraulic control unit that controls the braking force generated in the wheel, and has an inlet port connected to the discharge side of a pump and an outlet port communicating with the inlet port, and is a damping device that dampens pressure pulsations, comprising: a first liquid chamber communicating with the inlet port via a first opening; a second liquid chamber communicating with the first liquid chamber via a communication hole and communicating with the outlet port via a second opening; a first piston slidably provided in the first liquid chamber; a first biasing member that biases the first piston toward the first opening side; a hole formed in the first piston that is recessed from the second opening side toward the first opening side; and a slidable portion in the hole. The device comprises a second piston provided in the valve, a second biasing member that biases the second piston toward the first opening, a first through-hole provided in the second piston that penetrates from the first opening to the second opening, a first valve body capable of opening and closing the first opening of the first through-hole, a third biasing member that biases the first valve body toward the second opening, a projection member having a projection that can be inserted into the first through-hole and can contact the first valve body, provided on the second opening side of the first piston relative to the second piston and moving integrally with the first piston, a second valve body provided in the second liquid chamber that can open and close the second opening of the communication hole, and a fourth biasing member that biases the second valve body toward the first opening.

[0007] To solve the above problems, the hydraulic control unit is equipped with the damping device described above.

[0008] To solve the above problems, the brake system is equipped with the hydraulic control unit described above. [Effects of the Invention]

[0009] According to the present invention, it is possible to attenuate the pressure pulsation of the hydraulic control unit. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the general configuration of a brake system according to an embodiment of the present invention. [Figure 2]This is a cross-sectional view showing a schematic configuration of a damping device according to an embodiment of the present invention. [Figure 3] This figure shows a damping device according to an embodiment of the present invention, in which the first piston has moved to the right compared to the state shown in Figure 2. [Figure 4] This figure shows a damping device according to an embodiment of the present invention, in which the second piston has moved to the right compared to the state shown in Figure 3. [Figure 5] This figure shows a damping device according to an embodiment of the present invention, in which the first piston and the second piston have moved to the right compared to the state shown in Figure 4. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely illustrative to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0012] In this embodiment, a vehicle having four wheels 17 is described as an example, but the vehicle to which the present invention applies is not limited to a vehicle having four wheels 17. For example, it may be a vehicle having one, two, or three wheels 17, or a vehicle having five or more wheels 17.

[0013] <Brake system configuration> Referring to Figure 1, the configuration of the brake system 1 according to an embodiment of the present invention will be described.

[0014] Figure 1 is a schematic diagram showing the general configuration of the brake system 1. The brake system 1 is a system mounted on a vehicle for controlling the braking force generated in the vehicle. As shown in Figure 1, the brake system 1 comprises a brake pedal 11, a power booster 12, a master cylinder 13, a reservoir 14, a hydraulic control unit 15, a brake device 16, and a wheel 17.

[0015] The brake system 1 is mounted on a vehicle having four wheels 17, and each wheel 17 is braked by a brake device 16 provided on each wheel 17. The braking force generated on each wheel 17 is controlled by a hydraulic control unit 15. In Figure 1, for ease of understanding, only the part of the brake system 1 related to either the front or rear wheels is shown, and the part related to the other of the front or rear wheels is omitted from the illustration.

[0016] The number of wheels 17 whose braking force is controlled by the hydraulic control unit according to the present invention may be other than four. For example, the number of wheels 17 whose braking force is controlled by the hydraulic control unit 15 may be two. In that case, the brake system 1 can be installed on a vehicle having two wheels 17.

[0017] The brake pedal 11 is used by the driver to operate the brakes. During braking, the brake pedal 11 is pressed down by the driver. The power assist device 12 is connected to the brake pedal 11 and amplifies the force applied to the brake pedal 11. The master cylinder 13 is connected to the power assist device 12 and contains a piston that reciprocates in conjunction with the brake pedal 11, generating hydraulic pressure corresponding to the amount of braking operation. The reservoir 14 is attached to the master cylinder 13 and stores brake fluid.

[0018] The hydraulic control unit 15 includes a base body 15a in which a flow path for the brake fluid is formed. The master cylinder 13 and each brake device 16 are respectively connected to the base body 15a of the hydraulic control unit 15. The flow path for the brake fluid in the base body 15a of the hydraulic control unit 15 is connected to the wheel cylinder of the brake device 16. A braking force corresponding to the hydraulic pressure of the brake fluid in the wheel cylinder of the brake device 16 is generated on the wheel 17.

[0019] In the base body 15a of the hydraulic control unit 15, a main flow path 21, a sub-flow path 22, and a supply flow path 23 are formed as flow paths for the brake fluid. The main flow path 21 circulates the brake fluid of the master cylinder 13 to the wheel cylinder of the brake device 16. The sub-flow path 22 discharges the brake fluid of the wheel cylinder of the brake device 16. The supply flow path 23 supplies the brake fluid of the master cylinder 13 to the sub-flow path 22.

[0020] Also, in the base body 15a of the hydraulic control unit 15, a bleeding valve (EV) 31, a releasing valve (AV) 32, a first valve (USV) 33, a second valve (HSV) 34, an accumulator 35, a pump 36, and a motor 37 are provided as components for controlling the braking force generated on each wheel 17.

[0021] Note that the configuration of the hydraulic control unit according to the present invention may be different from the configuration of the hydraulic control unit 15 shown in FIG. 1 as long as it has a pump 36. For example, a configuration in which the supply flow path 23, the first valve 33, and the second valve 34 are omitted from the hydraulic control unit 15 shown in FIG. 1 is also included in the hydraulic control unit according to the present invention.

[0022] The main flow path 21 communicates the master cylinder 13 and the wheel cylinder of the brake device 16. The main flow path 21 includes a first main flow path 21a and two second main flow paths 21b. The first main flow path 21a is connected to the master cylinder 13. The two second main flow paths 21b branch from the first main flow path 21a and are connected to each brake device 16. A first valve 33 is provided in the first main flow path 21a. A bleeding valve 31 is provided in the second main flow path 21b.

[0023] The sub-flow channel 22 connects the brake device 16 side of the main flow channel 21 beyond the suction valve 31, the master cylinder 13 side of the main flow channel 21 beyond the suction valve 31, and the brake device 16 side of the first valve 33. The sub-flow channel 22 includes two first sub-flow channels 22a and a second sub-flow channel 22b. Each first sub-flow channel 22a is connected to the brake device 16 side of the main flow channel 21 beyond the suction valve 31. The second sub-flow channel 22b connects the confluence of the two first sub-flow channels 22a to the master cylinder 13 side of the main flow channel 21 beyond the suction valve 31, and the brake device 16 side of the first valve 33. A release valve 32 is provided in the first sub-flow channel 22a. An accumulator 35 and a pump 36 are provided in the second sub-flow channel 22b, in order from the first sub-flow channel 22a side.

[0024] Pump 36 is driven by motor 37 and draws brake fluid from the first sub-flow channel 22a side and discharges it to the main flow channel 21 side. Pump 36 is a reciprocating plunger pump. Specifically, the plunger of pump 36 reciprocates by being intermittently pressed by an eccentric cam provided on the output shaft of motor 37. This causes pump 36 to pump the brake fluid.

[0025] The supply passage 23 connects the master cylinder 13 side of the first valve 33 in the main passage 21 to the suction side of the pump 36 in the sub-passage 22. A second valve 34 is provided in the supply passage 23.

[0026] The suction valve 31 is, for example, a solenoid valve that is opened when de-energized and closed when energized. The release valve 32 is, for example, a solenoid valve that is closed when de-energized and opened when energized. The first valve 33 is, for example, a solenoid valve that is opened when de-energized and closed when energized. The second valve 34 is, for example, a solenoid valve that is closed when de-energized and opened when energized. The braking force generated on each wheel 17 is controlled by controlling the operation of these valves and the motor 37.

[0027] For example, under normal conditions when anti-lock brake control or anti-skid control, etc., described later, is not being performed, the loading valve 31 is opened, the release valve 32 is closed, the first valve 33 is opened, and the second valve 34 is closed. As a result, brake fluid flows from the master cylinder 13 to the wheel cylinder of the brake device 16 only through the main passage 21, without going through the sub-passage 22 and the supply passage 23. In this state, when the brake pedal 11 is pressed, the piston of the master cylinder 13 is pushed in, increasing the hydraulic pressure of the brake fluid in the wheel cylinder, and applying braking force to the wheel 17.

[0028] Anti-lock brake control is a control system designed to prevent wheel lock-up. For example, when anti-lock brake control is performed, the loading valve 31 is closed first, the release valve 32 is opened, the first valve 33 is opened, and the second valve 34 is closed. This stops the flow of brake fluid between the main passage 21 and the wheel cylinder of the brake device 16, allowing brake fluid to flow from the wheel cylinder to the sub-passage 22. As a result, brake fluid flows from the wheel cylinder to the accumulator 35, reducing the hydraulic pressure of the brake fluid in the wheel cylinder and decreasing the braking force applied to the wheel 17. The brake fluid that has flowed into the accumulator 35 is returned to the main passage 21 via the sub-passage 22 by the pump 36 being driven.

[0029] Then, when both the loading valve 31 and the release valve 32 are closed from the above state, the flow of brake fluid between the main passage 21 and the sub-passage 22 and the wheel cylinder stops, and the hydraulic pressure of the brake fluid in the wheel cylinder is maintained, thus maintaining the braking force applied to the wheel 17. Subsequently, when the loading valve 31 is opened and the release valve 32 is closed, the flow of brake fluid between the main passage 21 and the wheel cylinder resumes, the hydraulic pressure of the brake fluid in the wheel cylinder increases, and the braking force applied to the wheel 17 increases.

[0030] Anti-skid control is a control system designed to stabilize the vehicle's behavior. In anti-skid control, the vehicle's driving force and braking force are controlled as appropriate. For example, when braking the vehicle without applying the brakes while anti-skid control is in operation, the fill valve 31 is opened, the release valve 32 is closed, the first valve 33 is closed, and the second valve 34 is opened. As a result, brake fluid flows from the master cylinder 13 to the wheel cylinders of the brake system 16 via the supply passage 23 and the sub-passage 22. In this state, the pump 36 is driven, increasing the hydraulic pressure of the brake fluid in the wheel cylinders and generating a braking force to brake the wheels 17.

[0031] As described above, the hydraulic control unit 15 controls the operation of the pump 36. When the pump 36 is driven, pressure pulsation occurs in the fluid passages within the hydraulic control unit 15, which is a phenomenon in which the hydraulic pressure of the brake fluid pulsates. The sound produced by such pressure pulsation may be perceived as noise by the vehicle occupants and can be a factor that impairs comfort. Therefore, the hydraulic control unit 15 is provided with a damping device 100 to reduce pressure pulsation.

[0032] The damping device 100 is located downstream of the pump 36 in the sub-flow channel 22 (specifically, the second sub-flow channel 22b). The damping device 100 has an inlet port P1 and an outlet port P2. The inlet port P1 is connected to the discharge side of the pump 36. The inlet port P1 and the outlet port P2 are in communication. Therefore, the brake fluid discharged from the pump 36 flows into the damping device 100 via the inlet port P1, passes through the damping device 100, and then flows out of the damping device 100 via the outlet port P2.

[0033] <Configuration of the damping device> Referring to Figure 2, the configuration of the damping device 100 according to an embodiment of the present invention will be described.

[0034] Figure 2 is a cross-sectional view showing the schematic configuration of the damping device 100. However, the damping device 100 shown in Figure 2 is merely one example of a damping device according to the present invention, and various modifications to the example in Figure 2, as described later, are also included in the damping device according to the present invention.

[0035] In Figure 2 and Figures 3 to 5 described later, the damping device 100 is shown such that the axial direction of the housing 101 is left-right, the first opening PO1 connected to the inlet port P1 is located on the left side in that axial direction, and the second opening PO2 connected to the outlet port P2 is located on the right side in that axial direction. Hereafter, the left-right direction, which is the axial direction of the housing 101, will also be simply referred to as the axial direction. The first opening PO1 side means the side facing the first opening PO1 with the second opening PO2 as the reference in the axial direction (left side in Figures 2 to 5), or the upstream side in the direction of brake fluid flow from the first opening PO1 to the second opening PO2. The second opening PO2 side means the side facing the second opening PO2 with the first opening PO1 as the reference in the axial direction (right side in Figures 2 to 5), or the downstream side in the direction of brake fluid flow from the first opening PO1 to the second opening PO2.

[0036] As shown in Figure 2, the damping device 100 comprises a housing 101, a first cover 111, a second cover 112, a third cover 113, a fourth cover 114, a first piston 121, a second piston 122, a first sealing member 131, a second sealing member 132, a first biasing member 141, a second biasing member 142, a third biasing member 143, a fourth biasing member 144, a first valve body 151, a second valve body 152, a projection member 161, and a buffer member 171.

[0037] The housing 101 is formed, for example, in a cylindrical shape with a hollow space inside. The axial direction of the housing 101 is left-right. The housing 101 has an internal space that extends from the left end face to the right end face. The internal space of the housing 101 includes a first hole 101a and a second hole 101b. Each of the holes, the first hole 101a and the second hole 101b, has a cylindrical shape and is arranged coaxially with the central axis of the housing 101. The first hole 101a and the second hole 101b are continuous in this order from the left side. The diameter of the second hole 101b is smaller than the diameter of the first hole 101a.

[0038] The first cover 111 is fitted into the first hole 101a. The first cover 111 has a substantially disc shape. The left end of the outer surface of the first cover 111 is radially widened outward. The radially widened portion of the first cover 111 is fitted into the first hole 101a.

[0039] The third cover 113 is fitted into the second hole 101b. The third cover 113 has a substantially cylindrical shape. The third cover 113 has a first cylindrical portion 113a and a second cylindrical portion 113b. The first cylindrical portion 113a and the second cylindrical portion 113b have a cylindrical shape and are arranged coaxially with each other. The first cylindrical portion 113a and the second cylindrical portion 113b are continuous in this order from the right. The outer diameter of the second cylindrical portion 113b is smaller than the outer diameter of the first cylindrical portion 113a. The first cylindrical portion 113a is fitted into the right end of the second hole 101b. The outer circumferential surface of the second cylindrical portion 113b is radially separated from the inner circumferential surface of the second hole 101b.

[0040] A first opening PO1 is formed between the first cover 111 and the third cover 113 in the peripheral wall portion of the housing 101. The first opening PO1 communicates with the second hole 101b. The first liquid chamber S1 is defined by the right side surface of the first cover 111, the left side surface of the third cover 113, and the inner peripheral surface of the second hole 101b of the housing 101. In other words, the first cover 111 covers the first liquid chamber S1 from the left side. In other words, the right side surface of the first cover 111 constitutes the left wall surface of the first liquid chamber S1. The third cover 113 covers the first liquid chamber S1 from the right side. In other words, the left side surface of the third cover 113 constitutes the right wall surface of the first liquid chamber S1. The first liquid chamber S1 has a substantially cylindrical shape. The first liquid chamber S1 communicates with the inlet port P1 via the first opening PO1.

[0041] The inner circumferential surface of the third cover 113 defines the second liquid chamber S2. The left end of the inner circumferential surface of the third cover 113 is tapered radially inward. As a result, a communication hole 113c is formed at the center of the left end of the third cover 113. The second liquid chamber S2 communicates with the first liquid chamber S1 through the communication hole 113c.

[0042] The second cover 112 is fitted to the rightmost end of the inner circumferential surface of the third cover 113. The second cover 112 is formed in a substantially disc shape with a second opening PO2. The second opening PO2 is connected to the outlet port P2. The second opening PO2 is located radially outward from the center of the second cover 112. In the example in Figure 2, there are multiple second openings PO2. However, there may be only one second opening PO2.

[0043] The right end of the inner circumferential surface of the third cover 113 is widened in diameter. The second cover 112 is fitted onto the widened portion of the inner circumferential surface of the third cover 113. As a result, the second liquid chamber S2 is partitioned by the left side surface of the second cover 112. In other words, the second cover 112 covers the second liquid chamber S2 from the right side. To put it another way, the left side surface of the second cover 112 forms the right side wall of the second liquid chamber S2. The second liquid chamber S2 communicates with the outlet port P2 via the second opening PO2.

[0044] The first piston 121 is housed within the second hole 101b. The first piston 121 has a substantially cylindrical shape. The first piston 121 is positioned coaxially with the central axis of the second hole 101b. The first piston 121 has a first cylindrical portion 121a and a second cylindrical portion 121b. The first cylindrical portion 121a and the second cylindrical portion 121b have a cylindrical shape and are positioned coaxially with each other. The first cylindrical portion 121a and the second cylindrical portion 121b are continuous in this order from left to right. The outer diameter of the first cylindrical portion 121a is smaller than the outer diameter of the second cylindrical portion 121b.

[0045] The outer circumferential surface of the second cylindrical portion 121b is slidable with respect to the inner circumferential surface of the second hole portion 101b. Therefore, the first piston 121 is provided to be slidable in the axial direction within the first liquid chamber S1. Here, the outer circumferential surface of the first piston 121 is in contact with the part of the inner circumferential surface of the second hole portion 101b that is to the right of the first opening PO1. Therefore, the first opening PO1 communicates with the part of the first liquid chamber S1 that is to the left of the first piston 121.

[0046] An annular groove 121c is formed on the outer circumferential surface of the second cylindrical portion 121b. The annular groove 121c extends in the circumferential direction of the first piston 121. A first sealing member 131 is fitted into the annular groove 121c. The first sealing member 131 is, for example, an O-ring. The first sealing member 131 is pressed against the inner circumferential surface of the second hole portion 101b. This seals the gap between the outer circumferential surface of the second cylindrical portion 121b and the inner circumferential surface of the second hole portion 101b in a liquid-tight manner. In the example of Figure 2, two annular grooves 121c are arranged with an axial gap between them, and a first sealing member 131 is fitted into each annular groove 121c. However, the number of annular grooves 121c may be one or three or more.

[0047] The first piston 121 is biased to the left by the first biasing member 141. The first biasing member 141 is, for example, an elastic member such as a spring. The first biasing member 141 is positioned between the first piston 121 and the third cover 113. One end of the first biasing member 141 (the left end in Figure 2) abuts against the right end surface of the first piston 121. The other end of the first biasing member 141 (the right end in Figure 2) abuts against the left side surface of the first cylindrical portion 113a of the third cover 113. The direction of expansion and contraction of the first biasing member 141 is left-right. The first biasing member 141 is in a contracted state relative to its natural length.

[0048] A hole 121d is formed on the left side of the first piston 121. The hole 121d is a recessed portion of the first piston 121 extending from the left to the right. The hole 121d is recessed from the left end face of the first piston 121 to the right. The hole 121d has a cylindrical shape and is positioned coaxially with the central axis of the housing 101. However, the hole 121d does not have to be positioned coaxially with the central axis of the housing 101.

[0049] A hole 121e is formed on the right side of the first piston 121. The hole 121e is a recessed portion of the first piston 121 extending from the right side to the left side. The hole 121e is recessed from the right end face of the first piston 121 to the left side. The hole 121e has a cylindrical shape and is positioned coaxially with the central axis of the housing 101. However, the hole 121e does not have to be positioned coaxially with the central axis of the housing 101.

[0050] Holes 121d and 121e are in communication with each other. Therefore, holes 121d and 121e penetrate the first piston 121 from left to right. Holes 121d and 121e are continuous from left to right and are arranged coaxially with each other. The inner diameter of hole 121d is smaller than the inner diameter of hole 121e.

[0051] The second piston 122 is housed in the bore 121e. The second piston 122 has a substantially cylindrical shape. The second piston 122 is positioned coaxially with the central axis of the bore 121e. The outer circumferential surface of the second piston 122 is slidable against the inner circumferential surface of the bore 121e. Therefore, the second piston 122 is provided to be slidable in the axial direction within the bore 121e.

[0052] An annular groove 122a is formed on the outer circumferential surface of the second piston 122. The annular groove 122a extends in the circumferential direction of the second piston 122. A second sealing member 132 is fitted into the annular groove 122a. The second sealing member 132 is, for example, an O-ring. The second sealing member 132 is pressed against the inner circumferential surface of the hole 121e. As a result, the gap between the outer circumferential surface of the second piston 122 and the inner circumferential surface of the hole 121e is sealed liquid-tightly.

[0053] The second piston 122 is biased to the left by the second biasing member 142. The second biasing member 142 is, for example, an elastic member such as a spring. As will be described later, a projection member 161 is fitted to the right end of the inner circumferential surface of the hole 121e. The second biasing member 142 is positioned between the second piston 122 and the projection member 161. One end of the second biasing member 142 (the left end in Figure 2) abuts against the right side surface of the second piston 122. Specifically, in the example in Figure 2, the center of the right side surface of the second piston 122 protrudes to the right, and one end of the second biasing member 142 abuts against the surface around this protruding portion. The other end of the second biasing member 142 (the right end in Figure 2) abuts against the left side surface of the first cylindrical portion 161a of the projection member 161, which will be described later. Specifically, in the example shown in Figure 2, an annular groove extending in the circumferential direction is provided on the left side surface of the first cylindrical portion 161a of the projection member 161, and the other end of the second biasing member 142 abuts against the bottom surface of the groove. The expansion and contraction direction of the second biasing member 142 is in the left-right direction. The second biasing member 142 is in a contracted state relative to its natural length.

[0054] A hole 122b is formed on the left side of the second piston 122. The hole 122b is a recessed portion of the second piston 122 that extends from left to right. The hole 122b is recessed from the left end face of the second piston 122 to the right. The hole 122b has a substantially cylindrical shape and is positioned coaxially with the central axis of the hole 121e. However, the hole 122b does not have to be positioned coaxially with the central axis of the hole 121e.

[0055] The fourth cover 114 is fitted to the left end of the inner circumferential surface of the hole 122b. The fourth cover 114 is formed in a disc shape with a through hole 114a in the center. The through hole 114a penetrates the fourth cover 114 from left to right. The left end of the inner circumferential surface of the hole 122b is enlarged in diameter. The fourth cover 114 is fitted to the enlarged portion of the inner circumferential surface of the hole 122b. The space to the left of the second piston 122 in the first liquid chamber S1 and the hole 122b are in communication via the through hole 114a of the fourth cover 114.

[0056] The second piston 122 is provided with a first through-hole 122c that penetrates from the bottom of the hole 122b (the right-hand portion in Figure 2) to the right end face of the second piston 122. The first through-hole 122c penetrates the second piston 122 from left to right. The hole 122b and the first through-hole 122c are continuous from left to right and are arranged coaxially with each other. The inner diameter of the first through-hole 122c is smaller than the inner diameter of the hole 122b.

[0057] The second piston 122 has multiple third through holes 122d, which are different from the first through hole 122c. The third through holes 122d penetrate the second piston 122 from left to right. In the example in Figure 2, the third through holes 122d are arranged around the first through hole 122c and extend from the right side of the inner surface of the hole 122b to the right end surface of the second piston 122. The inner diameter of the third through holes 122d is, for example, about 0.4 mm to 0.5 mm in diameter. In the example in Figure 2, the third through holes 122d extend in the axial direction. However, the path of the third through holes 122d is not particularly limited; for example, the third through holes 122d may extend in a direction inclined with respect to the axial direction, and may be curved or bent.

[0058] Multiple third through-holes 122d are arranged at equal intervals in the circumferential direction of the second piston 122. However, the arrangement of the multiple third through-holes 122d is not limited to this example. For example, the multiple third through-holes 122d may be arranged at unequal intervals in the circumferential direction. Also, there may be only one third through-hole 122d. Brake fluid can flow through the third through-holes 122d from the left side to the right side of the second piston 122. In particular, even when the first valve body 151, which will be described later, is closed, brake fluid can flow through the third through-holes 122d from the left side to the right side of the second piston 122. The third through-holes 122d are provided to enhance the effect of reducing pressure pulsation. The function of the third through-holes 122d will be described later.

[0059] The first valve body 151 is provided in the hole 122b and can open and close the left side of the first through hole 122c. When the first valve body 151 is in the open state and does not block the first through hole 122c, brake fluid can flow through the first through hole 122c. This state corresponds to the open state of the first valve body 151 and the open state of the first through hole 122c. When the first valve body 151 is in the closed state and blocks the first through hole 122c, brake fluid cannot flow through the first through hole 122c. This state corresponds to the closed state of the first valve body 151 and the closed state of the first through hole 122c.

[0060] The first valve body 151 has, for example, a spherical shape. However, the shape of the first valve body 151 may be other than spherical. The third biasing member 143 is, for example, an elastic member such as a spring. The third biasing member 143 is positioned between the fourth cover 114 and the first valve body 151. The direction of expansion and contraction of the third biasing member 143 is left-right. The third biasing member 143 is in a contracted state relative to its natural length. Therefore, the first valve body 151 is biased to the right by the third biasing member 143.

[0061] The projection member 161 is provided to open and close the first valve body 151. The projection member 161 is attached to the first piston 121 and moves integrally with the first piston 121. The projection member 161 is located to the right of the first piston 121 relative to the second piston 122. Specifically, the projection member 161 is fitted to the right end of the inner circumferential surface of the hole 121e.

[0062] The projection member 161 has a first cylindrical portion 161a, a second cylindrical portion 161b, and a projection portion 161c. The first cylindrical portion 161a, the second cylindrical portion 161b, and the projection portion 161c are substantially cylindrical in shape and are arranged coaxially with each other. The first cylindrical portion 161a, the second cylindrical portion 161b, and the projection portion 161c are continuous in this order from right to left. The outer diameters of the first cylindrical portion 161a, the second cylindrical portion 161b, and the projection portion 161c decrease in this order. The first cylindrical portion 161a is fitted into the right end of the inner circumferential surface of the hole portion 121e. The outer circumferential surface of the second cylindrical portion 161b is radially separated from the inner circumferential surface of the hole portion 121e. The projection portion 161c protrudes to the left from the left side surface of the second cylindrical portion 161b.

[0063] The projection 161c is positioned coaxially with the first through-hole 122c of the second piston 122. As the second piston 122 moves to the right relative to the first piston 121 from the position shown in Figure 2, the projection 161c is inserted into the first through-hole 122c, and the tip of the projection 161c can contact the first valve body 151. The contact of the tip of the projection 161c with the first valve body 151 maintains the relative position of the first valve body 151 with respect to the first piston 121. In this state, as the second piston 122 moves further to the right relative to the first piston 121, the first valve body 151 opens. Thus, the projection 161c is insertable into the first through-hole 122c and can contact the first valve body 151.

[0064] A hole 161d is formed on the right side of the projection member 161. The hole 161d is a recessed portion of the projection member 161 extending from the right side to the left side. The hole 161d is recessed from the right end face of the projection member 161 to the left side. The hole 161d is positioned coaxially with the central axis of the hole 121e. However, the hole 161d does not have to be positioned coaxially with the central axis of the hole 121e.

[0065] The projection member 161 has a plurality of second through holes 161e formed therein. The second through holes 161e penetrate the projection member 161 from the left side to the right side. In the example in Figure 2, the second through holes 161e extend from the left side surface of the second cylindrical portion 161b to the bottom of the hole portion 161d (the left side in Figure 2). The inner diameter of the second through holes 161e is, for example, about 0.4 mm to 0.5 mm in diameter. In the example in Figure 2, the second through holes 161e extend in the axial direction. However, the path of the second through holes 161e is not particularly limited; for example, the second through holes 161e may extend in a direction inclined with respect to the axial direction, or they may be curved or bent.

[0066] Multiple second through-holes 161e are arranged at equal intervals in the circumferential direction of the projection member 161. However, the arrangement of the multiple second through-holes 161e is not limited to this example. For example, the multiple second through-holes 161e may be arranged at unequal intervals in the circumferential direction. Also, there may be only one second through-hole 161e. Brake fluid can flow through the second through-holes 161e from the left side to the right side of the projection member 161. The second through-holes 161e are provided to enhance the effect of reducing pressure pulsation. The function of the second through-holes 161e will be described later.

[0067] The second valve body 152 is provided in the second fluid chamber S2 and can open and close the right side of the communication hole 113c. When the second valve body 152 is in the open state and does not block the communication hole 113c, brake fluid can flow through the communication hole 113c. This state corresponds to the open state of the second valve body 152 and the open state of the communication hole 113c. When the second valve body 152 is in the closed state and blocks the communication hole 113c, brake fluid cannot flow through the communication hole 113c. This state corresponds to the closed state of the second valve body 152 and the closed state of the communication hole 113c.

[0068] The second valve body 152 has a head portion 152a, a first shaft portion 152b, and a second shaft portion 152c. The head portion 152a has a substantially hemispherical shape. The left side of the head portion 152a is spherical, allowing the communication hole 113c to be opened and closed. The first shaft portion 152b extends to the right from the right side surface of the head portion 152a. The second shaft portion 152c extends to the right from the right side surface of the first shaft portion 152b. The outer diameter of the second shaft portion 152c is smaller than the outer diameter of the first shaft portion 152b. The cross-sectional shapes of the first shaft portion 152b and the second shaft portion 152c are, for example, circular or polygonal. The first shaft portion 152b and the second shaft portion 152c are arranged coaxially with the central axis of the housing 101. A through hole 112a is formed in the center of the second cover 112, and the second shaft portion 152c is inserted through the through hole 112a.

[0069] The fourth biasing member 144 is, for example, an elastic member such as a spring. The fourth biasing member 144 is positioned between the second cover 112 and the second valve body 152. The direction of expansion and contraction of the fourth biasing member 144 is left-right. The fourth biasing member 144 is in a contracted state relative to its natural length. Therefore, the second valve body 152 is biased to the left by the fourth biasing member 144.

[0070] The cushioning member 171 is provided to mitigate the impact when the first piston 121 collides with the first cover 111. The cushioning member 171 is made of a material that easily absorbs impact, such as rubber. The cushioning member 171 is located on the left side of the first piston 121. Specifically, the cushioning member 171 is attached to the left end of the first piston 121 and moves integrally with the first piston 121. As shown in Figure 2, the cushioning member 171 comes into contact with the first cover 111 when the first piston 121 is in the leftmost position within its range of motion. In this way, the cushioning member 171 is provided so as to be able to come into contact with the first cover 111.

[0071] <Operation of the damping device> The operation of the damping device 100 according to an embodiment of the present invention will be described with reference to Figures 2 to 5.

[0072] Figure 2 above shows the damping device 100 in the hydraulic control unit 15 under normal conditions when the pump 36 is not driven. In this case, the first piston 121 is biased to the left by the first biasing member 141 and is located at the leftmost position in its range of motion. The second piston 122 is biased to the left by the second biasing member 142 and is located at the leftmost position in its range of motion. The left end face of the first piston 121 is in contact with the first cover 111 via the buffer member 171. The left end face of the second piston 122 is in contact with the bottom of the hole 121e (the left side in Figure 2). The first valve body 151 is not in contact with the projection 161c of the projection member 161, and is biased to the right by the third biasing member 143, and is in a closed state. The second valve body 152 is biased to the left by the fourth biasing member 144, and is in a closed state.

[0073] Here, in the hydraulic control unit 15, as described above, the pump 36 is driven when anti-lock brake control or anti-skid control is performed. In the state shown in Figure 2, when the pump 36 is driven, brake fluid flows into the damping device 100 through the first opening PO1, and the pressure in the space to the left of the first piston 121 in the first fluid chamber S1 increases. As a result, the first piston 121 first moves to the right.

[0074] In the following, we will describe an example in which the second piston 122 begins to move relative to the first piston 121 after the first piston 121 has started to move. However, the timing of when the first piston 121 starts to move and the timing of when the second piston 122 starts to move relative to the first piston 121 may be simultaneous, and the first piston 121 may start to move after the second piston 122 has started to move relative to the first piston 121.

[0075] Figure 3 shows the damping device 100 in a state where the first piston 121 has moved to the right compared to the state in Figure 2. In the state in Figure 3, pressure is stored in the space to the left of the first piston 121 within the first liquid chamber S1. The pressure in the space to the left of the first piston 121 within the first liquid chamber S1 pushes the first piston 121 to the right, causing it to move to the right compared to the state in Figure 2. As the first piston 121 moves to the right, the first biasing member 141 expands and contracts, and consequently shrinks. As a result, the force acting on the first piston 121 is absorbed by the first biasing member 141. In this way, the pressure pulsation is dampened as the first biasing member 141 expands and contracts in conjunction with the movement of the first piston 121.

[0076] In the state shown in Figure 3, the brake fluid is sent from the space to the left of the second piston 122 to the space to the right of the second piston 122, through the third through-hole 122d of the second piston 122. Thus, even when the tip of the projection 161c of the projection member 161 is not in contact with the first valve body 151 and the first valve body 151 is in a closed state, the brake fluid can still flow through the third through-hole 122d from the space to the left of the second piston 122 to the space to the right of the second piston 122. Here, the inner diameter of the third through-hole 122d is small, and the brake fluid flowing through the third through-hole 122d faces significant resistance. Therefore, the flow of brake fluid through the third through-hole 122d also dampens pressure pulsation.

[0077] Furthermore, in the state shown in Figure 3, the brake fluid is sent from the space to the left of the projection member 161 to the space to the right of the projection member 161, through the second through-hole 161e of the projection member 161. Here, the inner diameter of the second through-hole 161e is small, and the brake fluid flowing through the second through-hole 161e experiences significant resistance. Therefore, the flow of brake fluid through the second through-hole 161e also dampens the pressure pulsation.

[0078] Figure 4 shows the damping device 100 in a state where the second piston 122 has moved to the right compared to the state in Figure 3. In the state in Figure 4, the pressure in the space to the left of the second piston 122 in the first liquid chamber S1 pushes the second piston 122 to the right, causing it to move to the right relative to the first piston 121. As the second piston 122 moves to the right relative to the first piston 121, the second biasing member 142 expands and contracts, resulting in contraction. As a result, the force acting on the second piston 122 is absorbed by the second biasing member 142. In this way, the pressure pulsation is dampened as the second biasing member 142 expands and contracts in conjunction with the movement of the second piston 122.

[0079] Furthermore, when the second piston 122 moves to the right relative to the first piston 121, the first piston 121 also actually moves to the right. Therefore, the pressure pulsation is attenuated not only by the force absorption by the second biasing member 142, but also by the force absorption by the first biasing member 141.

[0080] Figure 5 shows the damping device 100 in a state where the first piston 121 and the second piston 122 have moved to the right compared to the state in Figure 4. In the state in Figure 5, the first piston 121 has moved further to the right compared to the state in Figure 4, and the second piston 122 has moved further to the right relative to the first piston 121. In the state in Figure 5, the tip of the projection 161c of the projection member 161 abuts against the first valve body 151, and the relative position of the first valve body 151 with respect to the first piston 121 is maintained. As a result, the first valve body 151 is in an open state, separated from the first through hole 122c, and brake fluid flows through the first through hole 122c from left to right.

[0081] Furthermore, in the state shown in Figure 5, the pressure in the communication hole 113c increases, causing the second valve body 152 to be pushed and moved to the right. As a result, the second valve body 152 separates from the communication hole 113c and opens, allowing brake fluid to flow through the communication hole 113c from left to right. The brake fluid that has passed through the communication hole 113c then flows out from the second fluid chamber S2 through the second opening PO2.

[0082] As shown in Figure 5, when the second valve body 152 is in the open state, the second valve body 152 can contact the second cover 112. In the example of Figure 5, the first shaft portion 152b and the second shaft portion 152c of the second valve body 152 move along the central axis of the housing 101. As described above, in addition to the second opening PO2, the second cover 112 has a through hole 112a. Here, the inner diameter of the through hole 112a is larger than the outer diameter of the second shaft portion 152c and smaller than the outer diameter of the first shaft portion 152b. Therefore, the stepped surface between the first shaft portion 152b and the second shaft portion 152c of the second valve body 152 can contact the second cover 112. As a result, even when the second valve body 152 is in the open state, the second valve body 152 does not vibrate and its posture is stabilized.

[0083] As described above, when brake fluid flows out from the second fluid chamber S2 through the second opening PO2, the pressure inside the damping device 100 decreases. As a result, the first piston 121, which is located on the right side inside the damping device 100, moves to the left side and returns to the state shown in Figure 2. Subsequently, brake fluid flows into the damping device 100 through the first opening PO1, and the operation described with reference to Figures 2 to 5 is repeated. Here, as described above, the left side of the first piston 121 is provided with a cushioning member 171 that can come into contact with the first cover 111. Therefore, when the first piston 121 moves to the right side and then returns to the left side, the impact caused by the collision between the first piston 121 and the first cover 111 can be mitigated.

[0084] <Effects of the damping device> The effects of the damping device 100 according to an embodiment of the present invention will be described below.

[0085] The damping device 100 includes a first liquid chamber S1 communicating with an inlet port P1 via a first opening PO1, a second liquid chamber S2 communicating with the first liquid chamber S1 via a communication hole 113c and communicating with an outlet port P2 via a second opening PO2, a first piston 121 slidably mounted in the first liquid chamber S1, a first biasing member 141 that biases the first piston 121 toward the first opening PO1, a hole 121e formed in the first piston 121 that is recessed from the second opening PO2 toward the first opening PO1, a second piston 122 slidably mounted in the hole 121e, a second biasing member 142 that biases the second piston 122 toward the first opening PO1, and a second piston 122 provided on the second piston 122. The device comprises a first through-hole 122c that penetrates from the first opening PO1 side to the second opening PO2 side, a first valve body 151 that can open and close the first opening PO1 side of the first through-hole 122c, a third biasing member 143 that biases the first valve body 151 toward the second opening PO2 side, a projection member 161 that is insertable into the first through-hole 122c and has a projection 161c that can contact the first valve body 151, is provided on the second opening PO2 side of the first piston 121 relative to the second piston 122 and moves integrally with the first piston 121, a second valve body 152 provided in the second liquid chamber S2 that can open and close the second opening PO2 side of the communication hole 113c, and a fourth biasing member 144 that biases the second valve body 152 toward the first opening PO1 side.

[0086] As a result, when the pump 36 is driven, pressure is first accumulated in the space to the left of the first piston 121 in the first liquid chamber S1. During this time, the energy of the pressure rise is absorbed as the first biasing member 141 gradually contracts as the first piston 121 moves. Furthermore, the energy of the pressure rise is absorbed as the second biasing member 142 gradually contracts as the second piston 122 moves relative to the first piston 121. Consequently, the rate of pressure rise on the second opening PO2 side relative to the first piston 121 becomes slower than the rate of pressure rise on the first opening PO1 side relative to the first piston 121.

[0087] Furthermore, when the pressure on the first opening PO1 side decreases and the first piston 121 moves toward the first opening PO1 side, the first biasing member 141 and the second biasing member 142 gradually extend, so that the rate of pressure decrease on the second opening PO2 side is slower than that on the first opening PO1 side than on the first piston 121 side. This makes it possible to attenuate the pressure pulsation on the second opening PO2 side relative to the pressure pulsation on the first opening PO1 side.

[0088] Furthermore, during the process in which the first piston 121 and the second piston 122 move toward the second opening PO2, the projection 161c of the projection member 161 can open the first valve body 151. Therefore, brake fluid can be properly delivered from the first piston 121 toward the second opening PO2. Thus, by increasing the pressure in the communication hole 113c, the second valve body 152 can be opened, allowing brake fluid to properly flow out from the second fluid chamber S2 through the second opening PO2. In this way, the damping device 100 can dampen the pressure pulsation of the hydraulic control unit 15.

[0089] Preferably, in the damping device 100, the projection member 161 has at least one second through-hole 161e that penetrates from the first opening PO1 side to the second opening PO2 side. This allows pressure pulsation to be dampened by the flow of brake fluid through the second through-hole 161e.

[0090] Preferably, in the damping device 100, the projection member 161 has a plurality of second through holes 161e formed therein, and the plurality of second through holes 161e are arranged at equal intervals in the circumferential direction of the projection member 161. As a result, the flow field of brake fluid around the projection member 161 is made uniform in the circumferential direction. Therefore, the brake fluid can flow smoothly within the damping device 100.

[0091] Preferably, in the damping device 100, the second piston 122 has at least one third through-hole 122d that penetrates from the first opening PO1 side to the second opening PO2 side and is different from the first through-hole 122c. This allows pressure pulsation to be dampened by the flow of brake fluid through the third through-hole 122d.

[0092] Preferably, in the damping device 100, the second piston 122 has a plurality of third through holes 122d, and the plurality of third through holes 122d are arranged at equal intervals in the circumferential direction of the second piston 122. As a result, the flow field of brake fluid around the second piston 122 is made uniform in the circumferential direction. Therefore, the brake fluid can flow smoothly within the damping device 100.

[0093] Preferably, the damping device 100 includes a first cover 111 that covers the first liquid chamber S1 from the first opening PO1 side, and a cushioning member 171 that can come into contact with the first cover 111 is provided on the first piston 121 on the first opening PO1 side. This reduces the impact when the first piston 121 collides with the first cover 111.

[0094] Preferably, the damping device 100 includes a second cover 112 that covers the second liquid chamber S2 from the second opening PO2 side, and the second valve body 152 is capable of contacting the second cover 112. As a result, when the second valve body 152 is in the open state, the second valve body 152 does not vibrate and its posture is stabilized. Therefore, the opening and closing operation of the second valve body 152 can be made smoother.

[0095] Preferred embodiments of the present invention have been described above with reference to the attached drawings. However, it goes without saying that the present invention is not limited to the embodiments described above, and that various modifications or alterations within the scope of the claims also fall within the technical scope of the present invention.

[0096] The configuration of the damping device 100 was described above with reference to Figure 2. However, various modifications to the example in Figure 2 may also be included in the damping device according to the present invention.

[0097] For example, the sliding directions of the first piston 121 and the second piston 122 may differ from the axial direction of the housing 101. For example, if the central axis of the first liquid chamber S1 is not coaxial with the housing 101, the sliding directions of the first piston 121 and the second piston 122 will be different from the axial direction of the housing 101.

[0098] Furthermore, for example, the cross-sectional shape perpendicular to the sliding direction of the first liquid chamber S1, the first piston 121, and the second piston 122 does not have to be circular. The cross-sectional shape may be, for example, elliptical or polygonal. In that case as well, the circumferential direction of the first piston 121 and the second piston 122 is the direction along the outer periphery of the first piston 121 and the second piston 122, and is the direction around the central axis of the first piston 121 and the second piston 122.

[0099] Furthermore, for example, the cross-sectional shape perpendicular to the axial direction of the projection member 161 does not have to be circular. The cross-sectional shape may be, for example, elliptical or polygonal. In that case as well, the circumferential direction of the projection member 161 is the direction along the outer edge of the projection member 161 and is the direction around the central axis of the projection member 161.

[0100] Furthermore, for example, a damping device according to the present invention may also be included in which the second through-hole 161e is omitted from the example in Figure 2. In the case where the second through-hole 161e is omitted, for example, a groove extending in the axial direction may be provided on the inner circumferential surface of the hole 121e, and the brake fluid may be able to flow through the groove from the left side to the right side of the projection member 161.

[0101] Furthermore, for example, a damping device according to the present invention may also be included in which the third through-hole 122d is omitted from the example in Figure 2. In the case where the third through-hole 122d is omitted, for example, a groove extending in the axial direction may be provided on the inner circumferential surface of the hole 121e, and the brake fluid may be able to flow through the groove from the left side to the right side of the second piston 122.

[0102] Furthermore, for example, a damping device according to the present invention may also be included in the example shown in Figure 2, in which the buffer member 171 is omitted.

[0103] Furthermore, for example, in the example shown in Figure 2, the shape of the second valve body 152 may be changed to another shape such as a spherical shape, and the second valve body 152 may not come into contact with the second cover 112.

[0104] Furthermore, for example, in the example shown in Figure 2, the first opening PO1 may be modified so that it is provided on the first cover 111 instead of the peripheral wall portion of the housing 101. [Explanation of Symbols]

[0105] 1. Brake System 11 Brake pedal 12 Booster 13 Master Cylinder 14 Reservoir 15. Hydraulic control unit 16 Brake system 17 wheels 21 Main channel 22 Subchannel 23 Supply channel 31. Encapsulation valve 32. Loosening valve 33 First valve 34. Second valve 35 Accumulator 36 pumps 37 Motor 100 Damping device 101 Housing 111 First Cover 112 Second Cover 113 Third Cover 113c Communication hole 114. Cover 4 121 First Piston 121e Hole 122 Second piston 122c 1st through hole 122d 3rd through hole 131 First sealing member 132 Second sealing member 141 First biasing member 142 Second biasing member 143 Third biasing member 144 Fourth biasing member 151 First valve body 152 Second valve body 161 Protruding member 161c Protrusion 161e 2nd through hole 171 Cushioning material P1 Entrance Port P2 Exit Port PO1 1st opening PO2 Second Opening S1 1st liquid chamber S2 2nd liquid chamber

Claims

1. A damping device (100) is provided in a hydraulic control unit (15) that controls the braking force generated in the wheel (17), and has an inlet port (P1) connected to the discharge side of a pump (36), and an outlet port (P2) communicating with the inlet port (P1), and damping device (100) that dampens pressure pulsations, A first liquid chamber (S1) is in communication with the inlet port (P1) via a first opening (PO1), A second liquid chamber (S2) is connected to the first liquid chamber (S1) via a communication hole (113c) and to the outlet port (P2) via a second opening (PO2), A first piston (121) is slidably provided in the first liquid chamber (S1), A first biasing member (141) biases the first piston (121) toward the first opening (PO1), In the first piston (121), there is a hole (121e) that is recessed from the second opening (PO2) side toward the first opening (PO1) side, A second piston (122) is slidably provided in the aforementioned hole (121e), A second biasing member (142) biases the second piston (122) toward the first opening (PO1), The second piston (122) has a first through hole (122c) that penetrates from the first opening (PO1) side to the second opening (PO2) side, A first valve body (151) that can open and close the first opening (PO1) side of the first through hole (122c), A third biasing member (143) biases the first valve body (151) toward the second opening (PO2), A projection member (161) is provided on the second opening (PO2) side of the first piston (121) relative to the second piston (122), and moves integrally with the first piston (121), having a projection (161c) that can be inserted into the first through hole (122c) and can abut against the first valve body (151), A second valve body (152) is provided in the second liquid chamber (S2) and is capable of opening and closing the second opening (PO2) side of the communication hole (113c), A fourth biasing member (144) biases the second valve body (152) toward the first opening (PO1), Equipped with, Damping device.

2. The projection member (161) has at least one second through-hole (161e) that penetrates from the first opening (PO1) side to the second opening (PO2) side. The damping device according to claim 1.

3. The projection member (161) has a plurality of the second through holes (161e) formed therein. The plurality of second through holes (161e) are arranged at equal intervals in the circumferential direction of the projection member (161). The damping device according to claim 2.

4. The second piston (122) has at least one third through hole (122d) that penetrates from the first opening (PO1) side to the second opening (PO2) side and is different from the first through hole (122c). The damping device according to claim 1.

5. The second piston (122) has a plurality of the third through holes (122d) formed therein. The plurality of third through holes (122d) are arranged at equal intervals in the circumferential direction of the second piston (122). The damping device according to claim 4.

6. The first liquid chamber (S1) is provided with a first cover (111) that covers it from the side of the first opening (PO1), A buffer member (171) is provided on the first piston (121) side facing the first opening (PO1), which can come into contact with the first cover (111). The damping device according to claim 1.

7. The second liquid chamber (S2) is provided with a second cover (112) that covers it from the second opening (PO2) side, The second valve body (152) is capable of contacting the second cover (112). The damping device according to claim 1.

8. A hydraulic control unit comprising a damping device (100) according to any one of claims 1 to 7.

9. A brake system comprising the hydraulic control unit (15) according to claim 8.

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