Damping device, hydraulic control unit, and brake system

Abstract

A damping device (100) is provided with: a first liquid chamber (S1) configured so as to communicate 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 the outlet port (P2) via a second opening (PO2); a first piston (121) provided in the first liquid chamber (S1); a first biasing member (141) configured so as to bias the first piston (121) toward the first opening (PO1); a hole section (121e) that is recessed from the second opening (PO2) side toward the first opening (PO1) side in the first piston (121); a second piston (122) provided in the hole (121e); a second biasing member (142) configured so as to bias the second piston (122) toward the first opening (PO1); a first through-hole (122c) provided in the second piston (122) and penetrating from the first opening (PO1) side to the second opening (PO2) side; a first valve body (151) capable of opening and closing the first opening (PO1) side of the first through hole (122c); a third biasing member (143) configured so as to bias the first valve body (151) toward the second opening (PO2); a protruding member (161) that can be inserted into the first through-hole (122c), has a protruding section (161c) that can come into contact with the first valve body (151), and is provided on the second opening (PO2) side of the first piston (121) with respect to the second piston (122); a second valve body (152) capable of opening and closing a second opening (PO2) side of the communication hole (113c); and a fourth biasing member (144) configured so as to bias the second valve body (152) toward 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 by wheels. For example, as disclosed in Patent Document 1, a plurality of valves and pumps are provided in the flow path within the hydraulic control unit. In such a hydraulic control unit, for example, in anti-lock braking control or anti-skid control, the opening and closing states of the respective valves are set to specific states, and control is performed to drive the pump.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010 - 052519 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] However, 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. As a result, when the pump is driven, a phenomenon of hydraulic pulsation of the brake fluid, that is, pressure pulsation, occurs in the flow path within the hydraulic control unit. The sound generated by such pressure pulsation may be perceived as noise by the vehicle occupants and may cause discomfort. Therefore, from the viewpoint of improving comfort, it is desirable to appropriately attenuate the pressure pulsation of the hydraulic control unit.

[0008] Therefore, in view of such a technical problem, an object of the present invention is to provide a damping device, a hydraulic control unit, and a braking system that can attenuate the pressure pulsation of the hydraulic control unit.

[0009] Means for Solving the Technical Problem

[0010] In order to solve the above technical problems, a damping device is provided in a hydraulic control unit that controls the braking force generated by wheels. The damping device has an inlet port connected to the discharge side of a pump and an outlet port communicating with the inlet port, and attenuates pressure pulsations. The damping device includes: 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 disposed in the first liquid chamber; a first biasing member biasing the first piston toward the first opening side; a hole portion formed by recessing from the second opening side toward the first opening side in the first piston; a second piston slidably disposed in the hole portion; a second biasing member biasing the second piston toward the first opening side; a first through hole provided in the second piston and penetrating from the first opening side to the second opening side; a first valve body capable of opening and closing the first opening side of the first through hole; a third biasing member biasing the first valve body toward the second opening side; a protruding member having a protrusion portion that can be inserted into the first through hole and can abut against the first valve body, disposed on the first piston on the second opening side with respect to the second piston, and moving integrally with the first piston; a second valve body disposed in the second liquid chamber and capable of opening and closing the second opening side of the communication hole; and a fourth biasing member biasing the second valve body toward the first opening side.

[0011] In order to solve the above technical problems, the hydraulic control unit includes the above-described damping device.

[0012] In order to solve the above technical problems, the braking system includes the above-described hydraulic control unit.

[0013] Advantages of the Invention

[0014] According to the present invention, it is possible to attenuate the pressure pulsations of the hydraulic control unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is a schematic diagram showing a schematic configuration of a braking system according to an embodiment of the present invention.

[0016] Figure 2 FIG. is a cross-sectional view showing a schematic configuration of a damping device according to an embodiment of the present invention.

[0017] Figure 3 FIG. is a view showing a state in which a first piston in a damping device according to an embodiment of the present invention has moved to the right as compared with a state of Figure 2 FIG. is a view showing a state in which a second piston in a damping device according to an embodiment of the present invention has moved to the right as compared with a state of

[0018] Figure 4 FIG. is a view showing a state in which a second piston in a damping device according to an embodiment of the present invention has moved to the right as compared with a state of Figure 3 FIG. is a view showing a state in which a second piston in a damping device according to an embodiment of the present invention has moved to the right as compared with a state of

[0019] Figure 5It shows the state in which the first piston and the second piston in the attenuation device according to an embodiment of the present invention have moved to the right compared to the state of Figure 4 the figure. Detailed Embodiment

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached Figure 1 drawings. The dimensions, materials, and other specific numerical values shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specifically negated. In addition, in this specification and the drawings, elements having substantially the same function and structure are given the same reference numerals to omit redundant descriptions, and elements not directly related to the present invention are omitted from the illustration.

[0021] In this embodiment, a vehicle having four wheels 17 is taken as an example, but the vehicle to which the present invention is applied 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 it may be a vehicle having five or more wheels 17.

[0022] <Structure of the Braking System>

[0023] Referring to Figure 1 the drawings, the structure of the braking system 1 according to an embodiment of the present invention will be described.

[0024] Figure 1 is a schematic diagram showing the schematic structure of the braking system 1. The braking system 1 is mounted on a vehicle and is a system for controlling the braking force generated in the vehicle. As Figure 1 shown, the braking system 1 includes a brake pedal 11, a force booster 12, a master cylinder 13, a reservoir 14, a hydraulic control unit 15, a braking device 16, and wheels 17.

[0025] The braking system 1 is mounted on a vehicle having four wheels 17, and brakes each wheel 17 by means of the braking device 16 provided on each wheel 17. Moreover, the braking force generated on each wheel 17 is controlled by the hydraulic control unit 15. In Figure 1 order to facilitate understanding, only the part related to one of the front wheels and the rear wheels is shown in the braking system 1, and the illustration of the part related to the other of the front wheels and the rear wheels is omitted.

[0026] In addition, the number of wheels 17 whose braking force is controlled by the hydraulic control unit related to the present invention may also be other than four. For example, the number of wheels 17 whose braking force is controlled by the hydraulic control unit 15 may also be two. In this case, the braking system 1 can be mounted on a vehicle having two wheels 17.

[0027] The brake pedal 11 is used in a braking operation performed by a driver. During the braking operation, the brake pedal 11 is depressed by the driver. The force amplifier 12 is connected to the brake pedal 11 and amplifies the stepping force of the brake pedal 11. The master cylinder 13 is connected to the force amplifier 12 and has a piston that reciprocates in conjunction with the brake pedal 11, generating hydraulic pressure corresponding to the operation amount of the braking operation. The reservoir 14 is attached to the master cylinder 13 and stores the brake fluid.

[0028] The hydraulic control unit 15 includes a base 15a that forms a flow path for the brake fluid. The master cylinder 13 and each brake device 16 are respectively connected to the base 15a of the hydraulic control unit 15. The flow path of the brake fluid in the base 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.

[0029] In the base 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 allows the brake fluid from the master cylinder 13 to flow to the wheel cylinder of the brake device 16. The sub-flow path 22 discharges the brake fluid from the wheel cylinder of the brake device 16. The supply flow path 23 supplies the brake fluid from the master cylinder 13 to the sub-flow path 22.

[0030] In addition, in the base 15a of the hydraulic control unit 15, a fill valve (EV) 31, a release 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.

[0031] In addition, the structure of the hydraulic control unit related to the present invention only needs to have a pump 36, and it may also be different from the structure of the hydraulic control unit 15 shown in Figure 1 For example, the hydraulic control unit related to the present invention also includes a structure in which the supply flow path 23, the first valve 33, and the second valve 34 are omitted with respect to the hydraulic control unit 15 shown in Figure 1 The main flow path 21 connects 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. The first valve 33 is provided in the first main flow path 21a. The fill valve 31 is provided in the second main flow path 21b.

[0032] The main flow path 21 communicates the master cylinder 13 with 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. The first valve 33 is provided in the first main flow path 21a. The fill valve 31 is provided in the second main flow path 21b.

[0033] The sub-flow path 22 connects the side of the main flow path 21 closer to the braking device 16 than the filling valve 31 with the side of the main flow path 21 closer to the master cylinder 13 than the filling valve 31 and closer to the braking device 16 than the first valve 33. The sub-flow path 22 includes two first sub-flow paths 22a and a second sub-flow path 22b. Each first sub-flow path 22a is connected to the side of the main flow path 21 closer to the braking device 16 than the filling valve 31. The second sub-flow path 22b connects the confluence part of the two first sub-flow paths 22a with the side of the main flow path 21 closer to the master cylinder 13 than the filling valve 31 and closer to the braking device 16 than the first valve 33. A release valve 32 is provided in the first sub-flow path 22a. In the second sub-flow path 22b, an accumulator 35 and a pump 36 are provided in sequence from the first sub-flow path 22a side.

[0034] The pump 36 is driven by a motor 37, sucks the brake fluid from the first sub-flow path 22a side, and ejects it toward the main flow path 21 side. The pump 36 is a plunger pump that performs reciprocating motion. Specifically, the plunger of the pump 36 reciprocates by being intermittently pushed by an eccentric cam provided on the output shaft of the motor 37. Thereby, the brake fluid is pumped by the pump 36.

[0035] The supply flow path 23 connects the side of the main flow path 21 closer to the master cylinder 13 than the first valve 33 with the suction side of the pump 36 in the sub-flow path 22. A second valve 34 is provided in the supply flow path 23.

[0036] The filling valve 31 is, for example, an electromagnetic valve that is open in the non-energized state and closed in the energized state. The release valve 32 is, for example, an electromagnetic valve that is closed in the non-energized state and open in the energized state. The first valve 33 is, for example, an electromagnetic valve that is open in the non-energized state and closed in the energized state. The second valve 34 is, for example, an electromagnetic valve that is closed in the non-energized state and open in the energized state. By controlling the operations of these valves and the motor 37, the braking force generated at each wheel 17 is controlled.

[0037] For example, during normal times when anti-lock braking control or anti-skid control described later is not executed, the filling valve 31 is open, the release valve 32 is closed, the first valve 33 is open, and the second valve 34 is closed. Thereby, a state is achieved in which the brake fluid flows from the master cylinder 13 to the wheel cylinder of the braking device 16 only through the main flow path 21 without passing through the sub-flow path 22 and the supply flow path 23. In this state, if the brake pedal 11 is depressed, the piston of the master cylinder 13 is pushed in and the hydraulic pressure of the brake fluid in the wheel cylinder increases, and a braking force is applied to the wheel 17.

[0038] Antilock braking control is a control used to avoid wheel 17 from locking up. For example, if antilock braking control is executed, first, the filling valve 31 is closed, the release valve 32 is opened, the first valve 33 is opened, and the second valve 34 is closed. As a result, the flow of the brake fluid between the main flow path 21 and the wheel cylinder of the braking device 16 stops, and it becomes a state where the brake fluid can flow from the wheel cylinder to the sub-flow path 22. Therefore, the brake fluid flows from the wheel cylinder into the accumulator 35, the hydraulic pressure of the brake fluid in the wheel cylinder decreases, and the braking force applied to the wheel 17 decreases. The brake fluid flowing into the accumulator 35 is driven by the pump 36 and sent back to the main flow path 21 via the sub-flow path 22.

[0039] Next, from the above state, by closing both the filling valve 31 and the release valve 32, the flow of the brake fluid between the main flow path 21 and the sub-flow path 22 and the wheel cylinder stops, the hydraulic pressure of the brake fluid in the wheel cylinder is maintained, and the braking force applied to the wheel 17 is maintained. Then, by opening the filling valve 31 and closing the release valve 32, the flow of the brake fluid between the main flow path 21 and the wheel cylinder restarts, the hydraulic pressure of the brake fluid in the wheel cylinder increases, and the braking force applied to the wheel 17 increases.

[0040] Anti-skid control is a control used to stabilize the vehicle's dynamics. In anti-skid control, the driving force and braking force of the vehicle are appropriately controlled. For example, during the execution of anti-skid control, when the vehicle is braked regardless of the braking operation, the filling 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, it becomes a state where the brake fluid flows from the master cylinder 13 to the wheel cylinder of the braking device 16 via the supply flow path 23 and the sub-flow path 22. In this state, by driving the pump 36, the hydraulic pressure of the brake fluid in the wheel cylinder increases, and a braking force for braking the wheel 17 is generated.

[0041] As described above, in the hydraulic control unit 15, control for driving the pump 36 is performed. If the pump 36 is driven, a phenomenon of hydraulic pressure pulsation of the brake fluid, that is, pressure pulsation, occurs in the flow path within the hydraulic control unit 15. The sound generated by such pressure pulsation may be felt as noise by the vehicle occupants and may cause discomfort. Therefore, in the hydraulic control unit 15, a damping device 100 for attenuating the pressure pulsation is provided.

[0042] The damping device 100 is provided on the downstream side of the pump 36 in the sub-flow path 22 (specifically, the second sub-flow path 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 communicates with the outlet port P2. Therefore, the brake fluid discharged from the pump 36 flows into the damping device 100 via the inlet port P1, and after passing through the inside of the damping device 100, it flows out of the damping device 100 via the outlet port P2.

[0043] <Structure of the attenuation device>

[0044] Refer to Figure 2 , and the structure of the attenuation device 100 of the embodiment of the present invention will be described.

[0045] Figure 2 It is a cross-sectional view showing the schematic structure of the attenuation device 100. However, Figure 2 The attenuation device 100 shown is merely an example of the attenuation device of the present invention, and structures with various modifications for the Figure 2 example described later are also included in the attenuation device of the present invention.

[0046] In Figure 2 and the following Figures 3 to 5 , the axial direction of the housing 101 is the left-right direction, and the attenuation device 100 is shown with the first opening PO1 connected to the inlet port P1 on the left side in this axial direction and the second opening PO2 connected to the outlet port P2 on the right side in this axial direction. Hereinafter, the axial direction of the housing 101, that is, the left-right direction, 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 a reference in the axial direction (the left side in Figures 2 to 5 ), or the upstream side of the flow direction of the brake fluid from the first opening PO1 toward the second opening PO2. The second opening PO2 side means the side facing the second opening PO2 with the first opening PO1 as a reference in the axial direction (the right side in Figures 2 to 5 ), or the downstream side of the flow direction of the brake fluid from the first opening PO1 toward the second opening PO2.

[0047] As Figure 2 shown, the attenuation device 100 includes 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 protrusion member 161, and a buffer member 171.

[0048] The housing 101 is formed, for example, in a cylindrical shape having a hollow space inside. The axial direction of the housing 101 is the left - right direction. In the housing 101, an internal space is formed so as to penetrate from the left end face to the right end face. The internal space of the housing 101 includes a first hole portion 101a and a second hole portion 101b. Each of the first hole portion 101a and the second hole portion 101b has a cylindrical shape and is arranged coaxially with the central axis of the housing 101. The first hole portion 101a and the second hole portion 101b are continuous in this order from the left side. The diameter of the second hole portion 101b is smaller than the diameter of the first hole portion 101a.

[0049] The first cover 111 is fitted into the first hole portion 101a. The first cover 111 has a substantially circular plate shape. The left end portion of the outer peripheral surface of the first cover 111 is expanded in diameter radially outward. The portion of the first cover 111 that is expanded in diameter radially outward is fitted into the first hole portion 101a.

[0050] The third cover 113 is fitted into the second hole portion 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 side. 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 portion of the second hole portion 101b. The outer peripheral surface of the second cylindrical portion 113b is radially spaced from the inner peripheral surface of the second hole portion 101b.

[0051] 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 portion 101b. A first liquid chamber S1 is delimited by the right - hand side face of the first cover 111, the left - hand side face of the third cover 113, and the inner peripheral surface of the second hole portion 101b of the housing 101. That is, the first cover 111 covers the first liquid chamber S1 from the left side. In other words, the right - hand side face of the first cover 111 constitutes the left - hand side 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 - hand side face of the third cover 113 constitutes the right - hand side 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.

[0052] A second liquid chamber S2 is delimited by the inner peripheral surface of the third cover 113. The left end portion of the inner peripheral surface of the third cover 113 is reduced in diameter radially inward. As a result, a communication hole 113c is formed at the center of the left end portion of the third cover 113. The second liquid chamber S2 communicates with the first liquid chamber S1 via the communication hole 113c.

[0053] The second cover 112 is fitted into the right end portion on the inner circumferential surface of the third cover 113. The second cover 112 is formed in a substantially disk shape having a second opening PO2. The second opening PO2 is connected to the outlet port P2. The second opening PO2 is disposed radially outside the center of the second cover 112. In Figure 2 the example of, the number of the second openings PO2 is plural. However, the number of the second openings PO2 may also be one.

[0054] The right end portion of the inner circumferential surface of the third cover 113 is enlarged in diameter. The second cover 112 is fitted into the enlarged portion on the inner circumferential surface of the third cover 113. Thus, the second liquid chamber S2 is partitioned by the left side surface of the second cover 112. That is, the second cover 112 covers the second liquid chamber S2 from the right side. In other words, the left side surface of the second cover 112 constitutes the right side wall surface of the second liquid chamber S2. The second liquid chamber S2 communicates with the outlet port P2 via the second opening PO2.

[0055] The first piston 121 is housed in the second hole portion 101b. The first piston 121 has a substantially cylindrical shape. The first piston 121 is disposed coaxially with the central axis of the second hole portion 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 disposed coaxially with each other. The first cylindrical portion 121a and the second cylindrical portion 121b are continuous in this order from the left side. The outer diameter of the first cylindrical portion 121a is smaller than the outer diameter of the second cylindrical portion 121b.

[0056] The outer circumferential surface of the second cylindrical portion 121b can slide relative to the inner circumferential surface of the second hole portion 101b. Therefore, the first piston 121 is slidably provided in the first liquid chamber S1 in the axial direction. Here, the outer circumferential surface of the first piston 121 abuts on the inner circumferential surface of the second hole portion 101b on the right side of the first opening PO1. Therefore, the first opening PO1 communicates with the portion on the left side of the first piston 121 in the first liquid chamber S1.

[0057] 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. The 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. Thus, the gap between the outer circumferential surface of the second cylindrical portion 121b and the inner circumferential surface of the second hole portion 101b is liquid-tightly sealed. In Figure 2 the example of, two annular grooves 121c are disposed at intervals in the axial direction, and the first sealing member 131 is fitted into each annular groove 121c. However, the number of the annular grooves 121c may also be one, or may be three or more.

[0058] The first piston 121 is biased to the left by a first biasing member 141. The first biasing member 141 is an elastic member such as a spring, for example. The first biasing member 141 is disposed between the first piston 121 and the third cover 113. One end of the first biasing member 141 ( Figure 2 the left end in) abuts against the right end face of the first piston 121. The other end of the first biasing member 141 ( Figure 2 the right end in) abuts against the left side face of the first cylindrical portion 113a of the third cover 113. The expansion and contraction direction of the first biasing member 141 is the left-right direction. The first biasing member 141 is in a state of being contracted relative to its natural length.

[0059] A hole portion 121d is formed on the left side of the first piston 121. The hole portion 121d is a portion that is recessed from the left side toward the right side of the first piston 121. The hole portion 121d is recessed from the left end face of the first piston 121 toward the right side. The hole portion 121d has a cylindrical shape and is disposed coaxially with the central axis of the housing 101. However, the hole portion 121d may not be disposed coaxially with the central axis of the housing 101.

[0060] A hole portion 121e is formed on the right side of the first piston 121. The hole portion 121e is a portion that is recessed from the right side toward the left side of the first piston 121. The hole portion 121e is recessed from the right end face of the first piston 121 toward the left side. The hole portion 121e has a cylindrical shape and is disposed coaxially with the central axis of the housing 101. However, the hole portion 121e may not be disposed coaxially with the central axis of the housing 101.

[0061] The hole portion 121d and the hole portion 121e communicate with each other. Therefore, the hole portion 121d and the hole portion 121e penetrate the first piston 121 from the left side to the right side. The hole portion 121d and the hole portion 121e are continuous in this order from the left side and are disposed coaxially with each other. The inner diameter of the hole portion 121d is smaller than the inner diameter of the hole portion 121e.

[0062] The second piston 122 is housed in the hole portion 121e. The second piston 122 has a substantially cylindrical shape. The second piston 122 is disposed coaxially with the central axis of the hole portion 121e. The outer peripheral surface of the second piston 122 can slide relative to the inner peripheral surface of the hole portion 121e. Therefore, the second piston 122 is slidably provided in the hole portion 121e in the axial direction.

[0063] An annular groove 122a is formed on the outer peripheral surface of the second piston 122. The annular groove 122a extends in the circumferential direction of the second piston 122. The second sealing member 132 is fitted in the annular groove 122a. The second sealing member 132 is an O-ring, for example. The second sealing member 132 is pressed against the inner peripheral surface of the hole portion 121e. Thereby, the gap between the outer peripheral surface of the second piston 122 and the inner peripheral surface of the hole portion 121e is hermetically sealed.

[0064] The second piston 122 is biased to the left by a second biasing member 142. The second biasing member 142 is an elastic member such as a spring, for example. As will be described later, the protruding member 161 is fitted into the right end portion of the inner peripheral surface of the hole portion 121e. The second biasing member 142 is disposed between the second piston 122 and the protruding member 161. One end ( Figure 2 the left end in) of the second biasing member 142 abuts against the right side surface of the second piston 122. Specifically, in Figure 2 the example of, the central portion 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 such a protruding portion. The other end ( Figure 2 the right end in) of the second biasing member 142 abuts against the left side surface of the first cylindrical portion 161a of the protruding member 161 described later. Specifically, in Figure 2 the example of, an annular groove portion extending in the circumferential direction is provided on the left side surface of the first cylindrical portion 161a of the protruding member 161, and the other end of the second biasing member 142 abuts against the bottom surface of the groove portion. The expansion and contraction direction of the second biasing member 142 is the left-right direction. The second biasing member 142 is in a state of being contracted relative to its natural length.

[0065] A hole portion 122b is formed on the left side of the second piston 122. The hole portion 122b is a portion that is recessed from the left side toward the right side of the second piston 122. The hole portion 122b is recessed from the left end surface of the second piston 122 toward the right side. The hole portion 122b has a substantially cylindrical shape and is disposed coaxially with the central axis of the hole portion 121e. However, the hole portion 122b may not be disposed coaxially with the central axis of the hole portion 121e.

[0066] The fourth cover 114 is fitted into the left end portion of the inner peripheral surface of the hole portion 122b. The fourth cover 114 is formed in a disk shape having a through hole 114a at the center. The through hole 114a penetrates the fourth cover 114 from the left side to the right side. The left end portion of the inner peripheral surface of the hole portion 122b has an enlarged diameter. The fourth cover 114 is fitted into the enlarged diameter portion of the inner peripheral surface of the hole portion 122b. The space on the left side of the second piston 122 in the first liquid chamber S1 communicates with the hole portion 122b via the through hole 114a of the fourth cover 114.

[0067] In the second piston 122, a first through hole 122c that penetrates from the bottom ( Figure 2 the right side portion in) of the hole portion 122b to the right end surface of the second piston 122 is provided. The first through hole 122c penetrates the second piston 122 from the left side to the right side. The hole portion 122b and the first through hole 122c are continuous in this order from the left side and are disposed coaxially with each other. The inner diameter of the first through hole 122c is smaller than the inner diameter of the hole portion 122b.

[0068] In the second piston 122, a plurality of third through holes 122d different from the first through hole 122c are formed. The third through holes 122d penetrate the second piston 122 from the left side to the right side. In Figure 2 the example of, the third through holes 122d are arranged around the first through hole 122c and extend from the right surface in the inner surface of the hole portion 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 Figure 2 the example of, 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 also extend in a direction inclined with respect to the axial direction, or may be bent or folded.

[0069] The plurality of third through holes 122d are arranged at equal intervals in the circumferential direction of the second piston 122. However, the arrangement of the plurality of third through holes 122d is not limited to this example. For example, the plurality of third through holes 122d may also be arranged at unequal intervals in the circumferential direction. In addition, the number of the third through holes 122d may also be one. The brake fluid can flow from the left side to the right side of the second piston 122 through the third through holes 122d. In particular, in the closed state of the first valve body 151 described later, the brake fluid can flow from the left side to the right side of the second piston 122 through the third through holes 122d. The third through holes 122d are provided to improve the effect of reducing pressure pulsation. In addition, the function of the third through holes 122d will be described later.

[0070] The first valve body 151 is provided in the hole portion 122b and can open and close the left side of the first through hole 122c. In the open state where the first valve body 151 does not block the first through hole 122c, the 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. In the closed state where the first valve body 151 blocks the first through hole 122c, the 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.

[0071] The first valve body 151 has, for example, a spherical shape. However, the shape of the first valve body 151 may also be a shape other than a spherical shape. The third biasing member 143 is an elastic member such as a spring, for example. The third biasing member 143 is arranged between the fourth cover 114 and the first valve body 151. The expansion and contraction direction of the third biasing member 143 is the left-right direction. The third biasing member 143 is in a state of contracting with respect to its natural length. Therefore, the first valve body 151 is biased to the right side by the third biasing member 143.

[0072] The protruding member 161 is provided to open and close the first valve body 151. The protruding member 161 is mounted on the first piston 121 and moves integrally with the first piston 121. The protruding member 161 is disposed on the right side of the first piston 121 with respect to the second piston 122. Specifically, the protruding member 161 is fitted into the right end portion of the inner peripheral surface of the hole portion 121e.

[0073] The protruding member 161 has a first cylindrical portion 161a, a second cylindrical portion 161b, and a protruding portion 161c. The first cylindrical portion 161a, the second cylindrical portion 161b, and the protruding portion 161c have a substantially cylindrical shape and are arranged coaxially with each other. The first cylindrical portion 161a, the second cylindrical portion 161b, and the protruding portion 161c are continuous in this order from the right side. The outer diameters of the first cylindrical portion 161a, the second cylindrical portion 161b, and the protruding portion 161c become smaller in this order. The first cylindrical portion 161a is fitted into the right end portion of the inner peripheral surface of the hole portion 121e. The outer peripheral surface of the second cylindrical portion 161b is radially spaced from the inner peripheral surface of the hole portion 121e. The protruding portion 161c protrudes leftward from the left side surface of the second cylindrical portion 161b.

[0074] The protruding portion 161c is disposed coaxially with the first through hole 122c of the second piston 122. When the second piston 122 moves relatively rightward with respect to the first piston 121 from Figure 2 a certain position, the protruding portion 161c is inserted into the first through hole 122c, and the tip of the protruding portion 161c can abut against the first valve body 151. By the tip of the protruding portion 161c abutting against the first valve body 151, the relative position of the first valve body 151 with respect to the first piston 121 is maintained. In this state, when the second piston 122 further moves relatively rightward with respect to the first piston 121, the first valve body 151 becomes an open state. In this way, the protruding portion 161c can be inserted into the first through hole 122c and can abut against the first valve body 151.

[0075] A hole portion 161d is formed on the right side of the protruding member 161. The hole portion 161d is a portion that is recessed from the right side toward the left side of the protruding member 161. The hole portion 161d is recessed leftward from the right end surface of the protruding member 161. The hole portion 161d is disposed coaxially with the central axis of the hole portion 121e. However, the hole portion 161d may not be disposed coaxially with the central axis of the hole portion 121e.

[0076] A plurality of second through holes 161e are formed in the protruding member 161. The second through holes 161e penetrate the protruding member 161 from the left side to the right side. In Figure 2 an example, the second through hole 161e extends from the left side surface of the second cylindrical portion 161b to the bottom of the hole portion 161d ( Figure 2the left part in). The inner diameter of the second through hole 161e is, for example, about 0.4 mm to 0.5 mm in diameter. In Figure 2 In the example of, the second through hole 161e extends in the axial direction. However, the path of the second through hole 161e is not particularly limited. For example, the second through hole 161e may also extend in a direction inclined with respect to the axial direction, or may be bent or kinked.

[0077] A plurality of second through holes 161e are arranged at equal intervals in the circumferential direction of the protruding member 161. However, the arrangement of the plurality of second through holes 161e is not limited to this example. For example, the plurality of second through holes 161e may also be arranged at unequal intervals in the circumferential direction. In addition, the number of the second through holes 161e may also be one. The brake fluid can flow from the left side to the right side of the protruding member 161 through the second through hole 161e. The second through hole 161e is provided to improve the effect of reducing pressure pulsation. In addition, the function of the second through hole 161e will be described later.

[0078] The second valve body 152 is provided in the second liquid chamber S2 and can open and close the right side of the communication hole 113c. In the open state where the second valve body 152 does not block the communication hole 113c, the 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. In the closed state where the second valve body 152 blocks the communication hole 113c, the 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.

[0079] The second valve body 152 has a head 152a, a first shaft portion 152b, and a second shaft portion 152c. The head 152a has a substantially hemispherical shape. The left side of the head 152a is spherical and can open and close the communication hole 113c. The first shaft portion 152b extends to the right from the right surface of the head 152a. The second shaft portion 152c extends to the right from the right 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.

[0080] The fourth biasing member 144 is an elastic member such as a spring. The fourth biasing member 144 is disposed between the second cover 112 and the second valve body 152. The expansion and contraction direction of the fourth biasing member 144 is the left-right direction. The fourth biasing member 144 is in a state of being contracted with respect to its natural length. Therefore, the second valve body 152 is biased to the left by the fourth biasing member 144.

[0081] The buffer member 171 is provided to buffer the impact when the first piston 121 collides with the first cover 111. The buffer member 171 is a member that easily absorbs impact, such as rubber. The buffer member 171 is provided on the left side of the first piston 121. Specifically, the buffer member 171 is mounted on the left end portion of the first piston 121 and moves integrally with the first piston 121. As Figure 2 shown, when the first piston 121 is at the leftmost position in the movable region, the buffer member 171 abuts against the first cover 111. In this way, the buffer member 171 is provided so as to be able to abut against the first cover 111.

[0082] <Operation of the damping device>

[0083] Refer to Figures 2 to 5 and the operation of the damping device 100 according to the embodiment of the present invention will be described.

[0084] In the above Figure 2 , the damping device 100 in the normal state where the pump 36 is not driven in the hydraulic control unit 15 is shown. In this case, the first piston 121 is urged to the left by the first biasing member 141 and is at the leftmost position in the movable region. The second piston 122 is urged to the left by the second biasing member 142 and is at the leftmost position in the movable region. The left end surface of the first piston 121 abuts against the first cover 111 via the buffer member 171. The left end surface of the second piston 122 abuts against the bottom of the hole portion 121e ( Figure 2 the left portion in ) abuts. The first valve body 151 does not abut against the protrusion portion 161c of the protrusion member 161 and is urged to the right by the third biasing member 143, and is in a closed state. The second valve body 152 is urged to the left by the fourth biasing member 144 and is in a closed state.

[0085] Here, in the hydraulic control unit 15, when anti-lock braking control or anti-skid control is performed as described above, the pump 36 is driven. In Figure 2 this state, if the pump 36 is driven, the brake fluid flows into the damping device 100 through the first opening PO1, and the pressure in the space on the left side of the first piston 121 in the first liquid chamber S1 increases. As a result, first, the first piston 121 moves to the right.

[0086] In addition, an example in which the second piston 122 starts to move relative to the first piston 121 after the movement of the first piston 121 starts will be described below. However, the timing when the first piston 121 starts to move and the timing when the second piston 122 starts to move relative to the first piston 121 may be the same, or the first piston 121 may start to move after the second piston 122 starts to move relative to the first piston 121.

[0087] Figure 3 This is a diagram showing the state where the first piston 121 has moved to the right compared to the state in Figure 2 . In the state of Figure 3 , pressure is accumulated in the space on the left side of the first piston 121 in the first liquid chamber S1. Moreover, the first piston 121 is pushed to the right by the pressure in the space on the left side of the first piston 121 in the first liquid chamber S1, and the first piston 121 has moved to the right compared to the state in Figure 2 . When the first piston 121 moves to the right, the first biasing member 141 expands and contracts, but as a result, it contracts. Thus, the force acting on the first piston 121 is absorbed by the first biasing member 141. In this way, by the expansion and contraction of the first biasing member 141 as the first piston 121 moves, pressure pulsations are attenuated.

[0088] In the state of Figure 3 , the brake fluid is sent from the space on the left side of the second piston 122 to the space on the right side of the second piston 122 through the third through-hole 122d of the second piston 122. In this way, even when the tip of the protrusion 161c of the protrusion member 161 does not contact the first valve body 151 and the first valve body 151 is in a closed state, the brake fluid can also flow from the space on the left side of the second piston 122 to the space on the right side of the second piston 122 through the third through-hole 122d. Here, the inner diameter of the third through-hole 122d is small, and a large resistance acts on the brake fluid flowing through the third through-hole 122d. Therefore, by the brake fluid flowing through the third through-hole 122d, pressure pulsations are also attenuated.

[0089] In addition, in the state of Figure 3 , the brake fluid is sent from the space on the left side of the protrusion member 161 to the space on the right side of the protrusion member 161 through the second through-hole 161e of the protrusion member 161. Here, the inner diameter of the second through-hole 161e is small, and a large resistance acts on the brake fluid flowing through the second through-hole 161e. Therefore, by the brake fluid flowing through the second through-hole 161e, pressure pulsations are also attenuated.

[0090] Figure 4 This is a diagram showing the state where the second piston 122 has moved to the right compared to the state in Figure 3 . In the state of Figure 4In the state of [[ID=]], the second piston 122 is pushed to the right by the pressure in the space on the left side of the second piston 122 in the first liquid chamber S1, and moves to the right relative to the first piston 121. When the second piston 122 moves to the right relative to the first piston 121, the second biasing member 142 expands and contracts, but as a result, it contracts. Thus, the force acting on the second piston 122 is absorbed by the second biasing member 142. In this way, by the expansion and contraction of the second biasing member 142 as the second piston 122 moves, the pressure pulsation is attenuated.

[0091] In addition, when the second piston 122 moves to the right relative to the first piston 121, actually the first piston 121 also moves to the right. Therefore, the pressure pulsation is attenuated not only by the absorption of force by the second biasing member 142, but also by the absorption of force by the first biasing member 141.

[0092] Figure 5 is a diagram showing a state in which the first piston 121 and the second piston 122 in the attenuation device 100 have moved to the right compared to the state of Figure 4 In the state of Figure 5 compared to the state of Figure 4 the first piston 121 has further moved to the right, and the second piston 122 has further moved to the right relative to the first piston 121. In the state of Figure 5 the tip of the protrusion 161c of the protrusion 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 moves away from the first through-hole 122c and becomes an open state, and the brake fluid flows from the left side to the right side in the first through-hole 122c.

[0093] Furthermore, in the state of Figure 5 the pressure in the communication hole 113c becomes high, and as a result, the second valve body 152 is pushed to the right and moves. Thus, the second valve body 152 moves away from the communication hole 113c and becomes an open state, and the brake fluid flows from the left side to the right side in the communication hole 113c. Then, the brake fluid that has passed through the communication hole 113c flows out from the second liquid chamber S2 through the second opening PO2.

[0094] As Figure 5 shown, when the second valve body 152 becomes an open state, the second valve body 152 can abut against the second cover 112. In the state of Figure 5In the example, 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 the second cover 112, through holes 112a are formed in addition to the second opening PO2. 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 in the second valve body 152 can abut against 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 the posture of the second valve body 152 is stabilized.

[0095] As described above, if the 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 located on the right side inside the damping device 100 moves to the left side and returns to Figure 2 the state. Then, as the brake fluid flows into the damping device 100 through the first opening PO1, the operations described with reference to Figures 2 to 5 are repeated. Here, on the left side of the first piston 121, a buffer member 171 that can abut against the first cover 111 is provided as described above. Therefore, when the first piston 121 moves to the right side and then returns to the left side, the impact generated by the collision between the first piston 121 and the first cover 111 can be alleviated.

[0096] <Effect of the damping device>

[0097] The effect of the damping device 100 according to the embodiment of the present invention will be described.

[0098] The attenuation 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 disposed in the first liquid chamber S1; a first biasing member 141 biasing the first piston 121 toward the first opening PO1; a hole portion 121e formed by the first piston 121 being recessed from the second opening PO2 side toward the first opening PO1 side; a second piston 122 slidably disposed in the hole portion 121e; a second biasing member 142 biasing the second piston 122 toward the first opening PO1; a first through hole 122c provided in the second piston 122 and penetrating from the first opening PO1 side to the second opening PO2 side; a first valve body 151 capable of opening and closing the first opening PO1 side of the first through hole 122c; a third biasing member 143 biasing the first valve body 151 toward the second opening PO2 side; a protrusion member 161 having a protrusion portion 161c that can be inserted into the first through hole 122c and can abut against the first valve body 151, disposed on the first piston 121 on the second opening PO2 side with respect to the second piston 122, and moving integrally with the first piston 121; a second valve body 152 disposed in the second liquid chamber S2 and capable of opening and closing the second opening PO2 side of the communication hole 113c; and a fourth biasing member 144 biasing the second valve body 152 toward the first opening PO1 side.

[0099] Thus, when the pump 36 is driven, first, pressure is accumulated in the space on the left side of the first piston 121 in the first liquid chamber S1. Then, during this period, as the first biasing member 141 gradually contracts as the first piston 121 moves, the energy of the rising pressure is absorbed. Further, as the second biasing member 142 gradually contracts as the second piston 122 moves relative to the first piston 121, the energy of the rising pressure is absorbed. As a result, the rising speed of the pressure on the second opening PO2 side with respect to the first piston 121 is slower than the rising speed of the pressure on the first opening PO1 side with respect to the first piston 121.

[0100] In addition, when the pressure on the first opening PO1 side drops and the first piston 121 moves toward the first opening PO1 side, as the first biasing member 141 and the second biasing member 142 gradually extend, the dropping speed of the pressure on the second opening PO2 side with respect to the first piston 121 is slower than the dropping speed of the pressure on the first opening PO1 side with respect to the first piston 121. Thus, the pressure pulsation on the second opening PO2 side can be attenuated with respect to the pressure pulsation on the first opening PO1 side.

[0101] Furthermore, during the process in which the first piston 121 and the second piston 122 move toward the second opening PO2 side, the first valve body 151 can be brought into an open state by the protrusion portion 161c of the protrusion member 161. Therefore, the brake fluid can be appropriately sent to the second opening PO2 side relative to the first piston 121. As a result, by increasing the pressure in the communication hole 113c, the second valve body 152 can be brought into an open state, and the brake fluid can appropriately flow out from the second liquid chamber S2 through the second opening PO2. In this way, according to the damping device 100, the pressure pulsation of the hydraulic control unit 15 can be attenuated.

[0102] Preferably, in the damping device 100, at least one second through hole 161e penetrating from the first opening PO1 side to the second opening PO2 side is formed in the protrusion member 161. Thereby, the pressure pulsation can also be attenuated by the brake fluid flowing through the second through hole 161e.

[0103] Preferably, in the damping device 100, a plurality of second through holes 161e are formed in the protrusion member 161, and the plurality of second through holes 161e are arranged at equal intervals in the circumferential direction of the protrusion member 161. Thereby, the flow field of the brake fluid is homogenized in the circumferential direction around the protrusion member 161. Therefore, the brake fluid can flow smoothly within the damping device 100.

[0104] Preferably, in the damping device 100, at least one third through hole 122d different from the first through hole 122c and penetrating from the first opening PO1 side to the second opening PO2 side is formed in the second piston 122. Thereby, the pressure pulsation can also be attenuated by the brake fluid flowing through the third through hole 122d.

[0105] Preferably, in the damping device 100, a plurality of third through holes 122d are formed in the second piston 122, and the plurality of third through holes 122d are arranged at equal intervals in the circumferential direction of the second piston 122. Thereby, the flow field of the brake fluid is homogenized in the circumferential direction around the second piston 122. Therefore, the brake fluid can flow smoothly within the damping device 100.

[0106] Preferably, the damping device 100 includes a first cover 111 that covers the first liquid chamber S1 from the first opening PO1 side; a buffer member 171 capable of abutting against the first cover 111 is provided on the first opening PO1 side of the first piston 121. Thereby, the impact when the first piston 121 collides with the first cover 111 can be alleviated.

[0107] Preferably, the damping device 100 includes a second cover 112 that covers the second liquid chamber S2 from the second opening PO2 side; the second valve body 152 can abut against the second cover 112. Thus, when the second valve body 152 is in the open state, the second valve body 152 does not vibrate, and the posture of the second valve body 152 is stabilized. Therefore, the opening and closing operation of the second valve body 152 can be made smooth.

[0108] As described above, while referring to the attached Figure 1 the preferred embodiments of the present invention have been described, but the present invention is of course not limited to the above embodiments. In particular, various modification examples or correction examples within the scope described in the claims also of course belong to the technical scope of the present invention.

[0109] In the above, with reference to Figure 2 the structure of the damping device 100 has been described. However, structures with various modifications to the Figure 2 example can also be included in the damping device related to the present invention.

[0110] For example, the sliding directions of the first piston 121 and the second piston 122 may also be different from the axial direction of the housing 101. For example, when the central axis of the first liquid chamber S1 is not arranged coaxially with the housing 101, the sliding directions of the first piston 121 and the second piston 122 become directions different from the axial direction of the housing 101.

[0111] In addition, for example, the cross-sectional shapes of the first liquid chamber S1, the first piston 121, and the second piston 122 orthogonal to the sliding direction may not be circular. The cross-sectional shape may be, for example, elliptical or polygonal. Also, in this case, the circumferential directions of the first piston 121 and the second piston 122 are also the directions along the outer peripheral edges of the first piston 121 and the second piston 122, respectively, and are the directions around the central axes of the first piston 121 and the second piston 122.

[0112] In addition, for example, the cross-sectional shape of the protrusion member 161 orthogonal to the axial direction may not be circular. The cross-sectional shape may be, for example, elliptical or polygonal. Also, in this case, the circumferential direction of the protrusion member 161 is also the direction along the outer peripheral edge of the protrusion member 161 and is the direction around the central axis of the protrusion member 161.

[0113] In addition, for example, the damping device related to the present invention may also include a structure in which the second through hole 161e is omitted with respect to the Figure 2 example. Also, when the second through hole 161e is omitted, for example, a groove extending in the axial direction may be provided on the inner peripheral surface of the hole portion 121e, and the brake fluid can flow from the left side to the right side of the protrusion member 161 through this groove.

[0114] In addition, for example, in the attenuation device related to the present invention, it may also include relative to Figure 2 In the example of Figure 2 , the structure of the third through hole 122d is omitted. Additionally, when the third through hole 122d is omitted, for example, a groove extending in the axial direction may be provided on the inner peripheral surface of the hole portion 121e, and the brake fluid can flow from the left side to the right side of the second piston 122 through this groove.

[0115] In addition, for example, in the attenuation device related to the present invention, it may also include relative to Figure 2 In the example of Figure 2 , the structure of the buffer member 171 is omitted.

[0116] In addition, for example, relative to Figure 2 In the example of Figure 2 , the shape of the second valve body 152 may be changed to another shape such as a spherical shape, or the second valve body 152 may not be in contact with the second cover 112.

[0117] In addition, for example, relative to Figure 2 In the example of Figure 2 , it may be changed so that the first opening PO1 is provided not on the peripheral wall portion of the housing 101 but on the first cover 111.

[0118] Explanation of reference numerals

[0119] 1 Brake system

[0120] 11 Brake pedal

[0121] 12 Booster device

[0122] 13 Master cylinder

[0123] 14 Reservoir

[0124] 15 Hydraulic control unit

[0125] 16 Brake device

[0126] 17 Wheel

[0127] 21 Main flow path

[0128] 22 Sub - flow path

[0129] 23 Supply flow path

[0130] 31 Filling valve

[0131] 32 Release valve

[0132] 33 First valve

[0133] 34 Second valve

[0134] 35 Accumulator

[0135] 36 Pump

[0136] 37 Motor

[0137] 100 Attenuation device

[0138] 101 Housing

[0139] 111 First cover

[0140] 112 Second cover

[0141] 113 Third cover

[0142] 113c Communication hole

[0143] 114 Fourth cover

[0144] 121 First piston

[0145] 121e Hole part

[0146] 122 Second piston

[0147] 122c First through-hole

[0148] 122d Third through-hole

[0149] 131 First sealing member

[0150] 132 Second sealing member

[0151] 141 First biasing member

[0152] 142 Second biasing member

[0153] 143 Third biasing member

[0154] 144 Fourth biasing member

[0155] 151 First valve body

[0156] 152 Second valve body

[0157] 161 Protrusion member

[0158] 161c Protrusion part

[0159] 161e Second through-hole

[0160] 171 Buffer member

[0161] P1 Inlet port

[0162] P2 Outlet port

[0163] PO1 First opening

[0164] PO2 Second opening

[0165] S1 First liquid chamber

[0166] S2 Second liquid chamber

Claims

1. A damping device (100) is provided in a hydraulic control unit (15) that controls the braking force generated at a wheel (17). The damping device 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 attenuates pressure pulsations. It is characterized in that it includes: a first liquid chamber (S1) communicating with the 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 the outlet port (P2) via a second opening (PO2); a first piston (121) slidably provided in the first liquid chamber (S1); a first biasing member (141) biasing the first piston (121) toward the first opening (PO1); a hole portion (121e) formed by recessing from the second opening (PO2) side toward the first opening (PO1) side in the first piston (121); a second piston (122) slidably provided in the hole portion (121e); a second biasing member (142) biasing the second piston (122) toward the first opening (PO1); a first through hole (122c) provided in the second piston (122) and penetrating from the first opening (PO1) side to the second opening (PO2) side; a first valve body (151) capable of opening and closing the first opening (PO1) side of the first through hole (122c); a third biasing member (143) biasing the first valve body (151) toward the second opening (PO2) side; a protrusion member (161) having a protrusion portion (161c) that can be inserted into the first through hole (122c) and can abut against the first valve body (151). The protrusion member (161) is provided on the first piston (121) on the second opening (PO2) side with respect 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) and capable of opening and closing the second opening (PO2) side of the communication hole (113c); and a fourth biasing member (144) biasing the second valve body (152) toward the first opening (PO1) side.

2. The damping device according to claim 1, characterized in that at least one second through hole (161e) penetrating from the first opening (PO1) side to the second opening (PO2) side is formed in the protrusion member (161).

3. The damping device according to claim 2, characterized in that a plurality of the second through holes (161e) are formed in the protrusion member (161); the plurality of second through holes (161e) are arranged at equal intervals in the circumferential direction of the protrusion member (161).

4. The damping device according to claim 1, characterized in that In the aforementioned second piston (122), at least one third through-hole (122d) different from the aforementioned first through-hole (122c) is formed, penetrating from the side of the aforementioned first opening (PO1) to the side of the aforementioned second opening (PO2).

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

6. The damping device according to claim 1, wherein a first cover (111) that covers the aforementioned first liquid chamber (S1) from the side of the aforementioned first opening (PO1) is provided; a buffer member (171) capable of abutting against the aforementioned first cover (111) is provided on the side of the aforementioned first opening (PO1) in the aforementioned first piston (121).

7. The damping device according to claim 1, wherein a second cover (112) that covers the aforementioned second liquid chamber (S2) from the side of the aforementioned second opening (PO2) is provided; the aforementioned second valve body (152) can abut against the aforementioned second cover (112).

8. A hydraulic control unit, wherein the damping device (100) according to any one of claims 1 to 7 is provided.

9. A braking system, wherein the hydraulic control unit (15) according to claim 8 is provided.

Images