Damping device, hydraulic control unit, and brake system

Abstract

The purpose of the present invention is to attenuate pressure pulsation of a hydraulic control unit. A damping device which is provided in a hydraulic control unit for controlling the braking force generated at the wheels, has an inlet port connected to the discharge side of the pump and an outlet port communicating with the inlet port, and attenuates the pressure pulsation; the damping device is provided with: a first liquid chamber that communicates with an 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 and disposed in the first liquid chamber on the opposite side from the second opening with respect to the first opening; a first biasing member that biases the first piston toward the first opening side; a second piston slidably provided in the first liquid chamber and disposed on the second opening side with respect to the first opening in the first liquid chamber; a second biasing member that biases the second piston toward the first opening side; a first valve body provided in the second liquid chamber and capable of opening and closing a second opening side of the communication hole; and a third biasing member that biases the first valve body toward the first opening side.

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 at the 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 plunger pump that mainly performs reciprocating motion is used as the pump. Therefore, the pumping of the brake fluid by the pump is performed intermittently. As a result, if 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 a reduction in comfort. 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 a wheel. 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. In the damping device, there are provided: 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 and disposed on the side opposite to the second opening with respect to the first opening in the first liquid chamber; a first biasing member biasing the first piston toward the first opening side; a second piston slidably disposed in the first liquid chamber and disposed on the second opening side with respect to the first opening in the first liquid chamber; a second biasing member biasing the second piston toward the first opening side; a first valve body disposed in the second liquid chamber and capable of opening and closing the second opening side of the communication hole; and a third biasing member biasing the first 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 is a schematic diagram showing a schematic configuration of a braking system according to an embodiment of the present invention.

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

[0017] Figure 3 is a diagram showing a state in which a first piston in a damping device according to an embodiment of the present invention has moved to the left compared with the state of Figure 2 is a diagram 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 compared with the state of

[0018] Figure 4 is a diagram 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 compared with the state of Figure 3 is a diagram 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 compared with the state of

[0019] Figure 5 is a diagram 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 compared with the state of Figure 4 is a diagram 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 compared with the state of DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, while referring to the attached Figure 1Hereinafter, preferred embodiments of the present invention will be described in detail. The dimensions, materials, other specific numerical values, etc. shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention except in cases where 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 for description, 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 a vehicle having five or more wheels 17.

[0022] <Structure of the braking system>

[0023] Refer to Figure 1 , and the structure of the braking system 1 of the 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 booster device 12, a master cylinder 13, a reservoir 14, a hydraulic control unit 15, a braking device 16, and a wheel 17.

[0025] The braking system 1 is mounted on a vehicle having four wheels 17, and each wheel 17 is braked by 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 , for the sake of easy understanding, in the braking system 1, only the part related to one of the front wheels and the rear wheels is shown, 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 according 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. Under normal circumstances, the braking system 1 can be mounted on a vehicle having two wheels 17.

[0027] The brake pedal 11 is used in the braking operation performed by the driver. During the braking operation, the brake pedal 11 is depressed by the driver. The power amplifier device 12 is connected to the brake pedal 11 to amplify the stepping force of the brake pedal 11. The master cylinder 13 is connected to the power amplifier device 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 to store 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 filling 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 the pump 36, and it may also be different from the structure of the hydraulic control unit 15 shown 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 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 filling 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 filling 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 brake 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 brake 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 brake 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 brake 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 pumping of the brake fluid by the pump 36 is performed.

[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 brake 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, thereby applying a braking force to the wheel 17.

[0038] Antilock braking control is a control for avoiding wheel lock-up of wheel 17. For example, if antilock braking control is executed, first, the fill 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 a state is achieved in which 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 returned to the main flow path 21 via the sub-flow path 22.

[0039] Next, starting from the above state, both the fill valve 31 and the release valve 32 are closed, 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, when the fill valve 31 is opened and the release valve 32 is closed, 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] Lateral skid prevention control is a control for stabilizing the dynamics of the vehicle. In lateral skid prevention control, the driving force and braking force of the vehicle are appropriately controlled. For example, during the execution of lateral skid prevention control, when the vehicle is braked regardless of the braking 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, a state is achieved in which 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, i.e., pressure pulsation, occurs in the flow path within the hydraulic control unit 15. The sound generated by such pressure pulsation may be perceived 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, 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 related to the present invention will be described.

[0045] Figure 2 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 related to the present invention, and structures obtained by various modifications of Figure 2 the example are also included in the attenuation device related to the present invention as will be described later.

[0046] In Figure 2 and the following Figures 3 - 5 , the attenuation device 100 is shown with the axial direction of the housing 101 as the left-right direction, the first opening PO1 connected to the inlet port P1 located on the left side in this axial direction, and the second opening PO2 connected to the outlet port P2 located on the right side in this axial direction. Hereinafter, the axial direction of the housing 101, i.e., 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 in the axial direction 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 in the axial direction 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 fifth cover 115, a first piston 121, a second piston 122, a third piston 123, a first sealing member 131, a second sealing member 132, a third sealing member 133, a first biasing member 141, a second biasing member 142, a third biasing member 143, a fourth biasing member 144, a fifth biasing member 145, a first valve body 151, a second valve body 152, and a protrusion member 161.

[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. An internal space is formed in the housing 101 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 third cover 113 is fitted into the first hole portion 101a. The third cover 113 has a substantially disc shape. The left end portion of the outer peripheral surface of the third cover 113 is expanded in diameter radially outward. The portion of the third cover 113 that is expanded in diameter radially outward is fitted into the first hole portion 101a.

[0050] The fourth cover 114 is fitted into the second hole portion 101b. The fourth cover 114 has a substantially cylindrical shape. The fourth cover 114 has a first cylindrical portion 114a and a second cylindrical portion 114b. The first cylindrical portion 114a and the second cylindrical portion 114b have a cylindrical shape and are arranged coaxially with each other. The first cylindrical portion 114a and the second cylindrical portion 114b are continuous in this order from the right side. The outer diameter of the second cylindrical portion 114b is smaller than the outer diameter of the first cylindrical portion 114a. The first cylindrical portion 114a is fitted into the right end portion of the second hole portion 101b. The outer peripheral surface of the second cylindrical portion 114b is radially spaced from the inner peripheral surface of the second hole portion 101b. At the center of the left side surface of the second cylindrical portion 114b, a recessed portion 114c is formed. The recessed portion 114c has a cylindrical shape arranged coaxially with the second cylindrical portion 114b. The base portion 161b of a protruding member 161 described later is fitted into the recessed portion 114c.

[0051] Between the third cover 113 and the fourth cover 114 in the peripheral wall portion of the housing 101, a first opening PO1 is formed. The first opening PO1 communicates with the second hole portion 101b. A first liquid chamber S1 is delimited by the right side surface of the third cover 113, the left side surface of the fourth cover 114, and the inner peripheral surface of the second hole portion 101b of the housing 101. That is, the third cover 113 covers the first liquid chamber S1 from the left side. The fourth cover 114 covers the first liquid chamber S1 from the right side. In other words, the left side surface of the fourth cover 114 constitutes the right 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 first cylindrical portion 114a of the fourth cover 114. The second liquid chamber S2 communicates with the recessed portion 114c via a communication hole 114d. The recessed portion 114c, the communication hole 114d, and the second liquid chamber S2 are continuous in this order from the left side and are arranged coaxially with each other. The second liquid chamber S2 communicates with the first liquid chamber S1 via the communication hole 114d.

[0053] The second cover 112 is fitted into the right end portion of the inner peripheral surface of the first cylindrical portion 114a of the fourth cover 114. The second cover 112 is formed in a substantially disc shape having a second opening PO2. The second opening PO2 is connected to the outlet port P2. The second opening PO2 is arranged radially outside the center of the second cover 112. In Figure 2In the example, the number of the second openings PO2 is plural. However, the number of the second openings PO2 can also be one.

[0054] The right end portion of the inner peripheral surface of the first cylindrical portion 114a of the fourth cover 114 has an enlarged diameter. The second cover 112 is fitted into the enlarged diameter portion of the inner peripheral surface of the first cylindrical portion 114a. 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 through 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 outer peripheral surface of the first piston 121 can slide relative to the inner peripheral surface of the second hole portion 101b. Therefore, the first piston 121 is slidably disposed in the first liquid chamber S1 in the axial direction. Here, the first piston 121 is disposed on the left side of the first opening PO1 in the first liquid chamber S1. That is, the first piston 121 is disposed on the side opposite to the second opening PO2 with respect to the first opening PO1 in the first liquid chamber S1.

[0056] An annular groove 121a is formed on the outer peripheral surface of the first piston 121. The annular groove 121a extends in the circumferential direction of the first piston 121. The first sealing member 131 is fitted into the annular groove 121a. The first sealing member 131 is, for example, an O-ring. The first sealing member 131 is pressed against the inner peripheral surface of the second hole portion 101b. Thus, the gap between the outer peripheral surface of the first piston 121 and the inner peripheral surface of the second hole portion 101b is sealed in a liquid-tight manner.

[0057] The first piston 121 is urged to the right by the first urging member 141. The first urging member 141 is, for example, an elastic member such as a spring. The first urging member 141 is disposed between the first piston 121 and the third cover 113. One end ( Figure 2 the right end in this case) of the first urging member 141 abuts against the recessed portion 121b of the first piston 121. The recessed portion 121b is provided at the center of the left side surface of the first piston 121. The other end ( Figure 2 the left end in this case) of the first urging member 141 abuts against the right side surface of the third cover 113. The expansion and contraction direction of the first urging member 141 is the left-right direction. The first urging member 141 is in a state of being contracted with respect to the natural length.

[0058] The second piston 122 is received inside the second hole portion 101b. The second piston 122 has a substantially cylindrical shape. The second piston 122 is arranged coaxially with the central axis of the second hole portion 101b. The outer peripheral surface of the second piston 122 can slide relative to the inner peripheral surface of the second hole portion 101b. Therefore, the second piston 122 is slidably arranged in the first liquid chamber S1 in the axial direction. Here, the second piston 122 is arranged on the right side of the first opening PO1 in the first liquid chamber S1. That is, the second piston 122 is arranged on the side of the second opening PO2 relative to the first opening PO1 in the first liquid chamber S1.

[0059] On the outer peripheral surface of the second piston 122, an annular groove 122a is formed. 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, for example, an O-ring. The second sealing member 132 is pressed against the inner peripheral surface of the second hole portion 101b. Thereby, the gap between the outer peripheral surface of the second piston 122 and the inner peripheral surface of the second hole portion 101b is sealed in a liquid-tight manner. In Figure 2 the example, two annular grooves 122a are arranged at intervals in the axial direction, and the second sealing member 132 is fitted in each annular groove 122a. However, the number of the annular grooves 122a may be one, or may be three or more.

[0060] 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. The second biasing member 142 is arranged between the second piston 122 and the fourth cover 114. One end ( Figure 2 the left end in Figure 2 ) of the second biasing member 142 abuts against the right end surface of the second piston 122. The other end (

[0061] the right end in

[0062] ]]) of the second biasing member 142 abuts against the left side surface of the first cylindrical portion 114a of the fourth cover 114. 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.

[0061] In the second piston 122, a hole portion 122b is formed. The hole portion 122b is a portion that is recessed from the left side toward the right side in 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 is arranged coaxially with the central axis of the housing 101. However, the hole portion 122b may not be arranged coaxially with the central axis of the housing 101.

[0062] The fifth cover 115 is fitted into the left end portion on the inner peripheral surface of the hole portion 122b. The fifth cover 115 is formed in a disc shape having a through hole 115a at the center. The through hole 115a penetrates the fifth cover 115 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 fifth cover 115 is fitted into the enlarged diameter portion on the inner peripheral surface of the hole portion 122b. The space in the first liquid chamber S1 to the left of the second piston 122 communicates with the hole portion 122b via the through hole 115a of the fifth cover 115.

[0063] In the second piston 122, a hole portion 122c is formed. The hole portion 122c is a portion that is recessed from the right side toward the left side in the second piston 122. The hole portion 122c is recessed from the right end face of the second piston 122 toward the left side. The hole portion 122c is arranged coaxially with the central axis of the housing 101. However, the hole portion 122c may not be arranged coaxially with the central axis of the housing 101.

[0064] The first cover 111 is fitted into the right end portion on the inner peripheral surface of the hole portion 122c. The first cover 111 is formed in a substantially cylindrical shape. The right end portion of the outer peripheral surface of the first cover 111 has an enlarged diameter. The enlarged diameter portion of the outer peripheral surface of the first cover 111 is fitted into the right end portion on the inner peripheral surface of the hole portion 122c. In this way, the first cover 111 covers the hole portion 122c from the right side.

[0065] The hole portion 122b communicates with the hole portion 122c via the first through hole 122d. In this way, the first through hole 122d penetrates the second piston 122 from the left side to the right side. The hole portion 122b, the first through hole 122d, and the hole portion 122c are continuous in this order from the left side and are arranged coaxially with each other. The inner diameter of the first through hole 122d is smaller than the inner diameters of both the hole portion 122b and the hole portion 122c. In Figure 2 the example, the inner diameter of the hole portion 122b is smaller than the inner diameter of the hole portion 122c. However, the inner diameter of the hole portion 122b may be the same as the inner diameter of the hole portion 122c or may be larger than the inner diameter of the hole portion 122c.

[0066] In the second piston 122, a plurality of fourth through holes 122e are formed. The fourth through holes 122e penetrate the second piston 122 from the left side to the right side. In Figure 2 the example, the fourth through holes 122e are arranged around the first through hole 122d and extend from the right side surface in the inner surface of the hole portion 122b to the left side surface in the inner surface of the hole portion 122c. The inner diameter of the fourth through hole 122e is, for example, about 0.4 mm to 0.5 mm in diameter. In Figure 2 the example, the fourth through holes 122e extend in the axial direction. However, the path of the fourth through holes 122e is not particularly limited. For example, the fourth through holes 122e may also extend in a direction inclined with respect to the axial direction, or may be bent or kinked.

[0067] A plurality of fourth through holes 122e are arranged at equal intervals in the circumferential direction of the second piston 122. However, the arrangement of the plurality of fourth through holes 122e is not limited to this example. For example, the plurality of fourth through holes 122e may be arranged at unequal intervals in the circumferential direction. In addition, the number of the fourth through holes 122e may also be one. The brake fluid can flow from the left side to the right side of the second piston 122 through the fourth through holes 122e. In particular, in the closed state of the second valve body 152 described later, the brake fluid can also flow from the left side to the right side of the second piston 122 through the fourth through holes 122e. The fourth through holes 122e are provided to improve the effect of reducing pressure pulsation. In addition, the function of the fourth through holes 122e will be described later.

[0068] The second valve body 152 is provided in the hole portion 122b and can open and close the left side of the first through hole 122d. In the open state where the second valve body 152 does not block the first through hole 122d, the brake fluid can flow through the first through hole 122d. This state corresponds to the open state of the second valve body 152 and the open state of the first through hole 122d. In the closed state where the second valve body 152 blocks the first through hole 122d, the brake fluid cannot flow through the first through hole 122d. This state corresponds to the closed state of the second valve body 152 and the closed state of the first through hole 122d.

[0069] The second valve body 152 has, for example, a spherical shape. However, the shape of the second valve body 152 may also be a shape other than a spherical shape. The fourth biasing member 144 is an elastic member such as a spring, for example. The fourth biasing member 144 is disposed between the fifth cover 115 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 relative to its natural length. Therefore, the second valve body 152 is biased to the right by the fourth biasing member 144.

[0070] The third piston 123 is housed in the hole portion 122c. The third piston 123 has a substantially cylindrical shape. The third piston 123 is disposed coaxially with the central axis of the hole portion 122c. The outer peripheral surface of the third piston 123 can slide relative to the inner peripheral surface of the hole portion 122c. Therefore, the third piston 123 can be slidably disposed in the hole portion 122c in the axial direction.

[0071] An annular groove 123a is formed on the outer peripheral surface of the third piston 123. The annular groove 123a extends in the circumferential direction of the third piston 123. The third sealing member 133 is fitted in the annular groove 123a. The third sealing member 133 is an O-ring, for example. The third sealing member 133 is pressed against the inner peripheral surface of the hole portion 122c. Thereby, the gap between the outer peripheral surface of the third piston 123 and the inner peripheral surface of the hole portion 122c is sealed in a liquid-tight manner.

[0072] The third piston 123 is urged to the left by a fifth urging member 145. The fifth urging member 145 is an elastic member such as a spring, for example. The fifth urging member 145 is disposed between the third piston 123 and the first cover 111. One end ( Figure 2 the left end in) of the fifth urging member 145 abuts against the recessed portion 123b of the third piston 123. The recessed portion 123b is formed in a ring shape along the inner peripheral edge of the third piston 123 in the right side surface of the third piston 123. The other end ( Figure 2 the right end in) of the fifth urging member 145 abuts against the recessed portion 111a of the first cover 111. The recessed portion 111a is formed in a ring shape along the inner peripheral edge of the first cover 111 in the left side surface of the first cover 111. The expansion and contraction direction of the fifth urging member 145 is the left-right direction. The fifth urging member 145 is in a state of being contracted relative to its natural length.

[0073] In the first cover 111, a plurality of second through holes 111b are formed. The second through holes 111b penetrate the first cover 111 from the left side to the right side. In Figure 2 the example, the second through holes 111b extend from the recessed portion 111a to the right side surface of the first cover 111. The inner diameter of the second through holes 111b is, for example, about 0.4 mm to 0.5 mm in diameter. In Figure 2 the example, the second through holes 111b extend in the axial direction. However, the path of the second through holes 111b is not particularly limited. For example, the second through holes 111b may also extend in a direction inclined with respect to the axial direction, or may be bent or kinked.

[0074] The plurality of second through holes 111b are arranged at equal intervals in the circumferential direction of the first cover 111. However, the arrangement of the plurality of second through holes 111b is not limited to this example. For example, the plurality of second through holes 111b may also be arranged at unequal intervals in the circumferential direction. In addition, the number of the second through holes 111b may also be one. Brake fluid can flow from the left side to the right side of the first cover 111 through the second through holes 111b. The second through holes 111b are provided to improve the effect of reducing pressure pulsation. In addition, the function of the second through holes 111b will be described later.

[0075] The protruding member 161 is provided to open and close the second valve body 152. The protruding member 161 is disposed on the right side with respect to the second valve body 152. The protruding member 161 has a protruding portion 161a and a base portion 161b. The base portion 161b has a substantially disc shape. The base portion 161b is fitted into the recessed portion 114c of the fourth cover 114. Therefore, the base portion 161b covers the left side of the communication hole 114d. The protruding portion 161a is connected to the base portion 161b. The protruding portion 161a protrudes to the left from the center of the base portion 161b.

[0076] The protrusion 161a is arranged coaxially with the first cover 111, the third piston 123, and the first through hole 122d. The protrusion 161a is inserted through the hollow portion at the center of the first cover 111 and the hollow portion at the center of the third piston 123. When the second piston 122 moves to the right from Figure 2 its position, the protrusion 161a is inserted through the first through hole 122d, and the front end of the protrusion 161a can abut against the second valve body 152. By the front end of the protrusion 161a abutting against the second valve body 152, the position of the second valve body 152 is maintained. In this state, when the second piston 122 further moves to the right, the second valve body 152 becomes an open state. Thus, the protrusion 161a can be inserted through the first through hole 122d and can abut against the second valve body 152.

[0077] In the base portion 161b, a third through hole 161c is formed. The third through hole 161c penetrates the base portion 161b from the left side to the right side. The inner diameter of the third through hole 161c is, for example, about 0.4 mm to 0.5 mm in diameter. In addition, the path of the third through hole 161c is not limited to Figure 2 the example, and for example, the number and arrangement of the branched portions of the third through hole 161c may also be different from Figure 2 the example.

[0078] The first valve body 151 is disposed in the second fluid chamber S2 and can open and close the right side of the communication hole 114d. In the open state where the first valve body 151 does not block the communication hole 114d, the brake fluid can flow through the communication hole 114d. This state corresponds to the open state of the first valve body 151 and the open state of the communication hole 114d. In the closed state where the first valve body 151 blocks the communication hole 114d, the brake fluid cannot flow through the communication hole 114d. This state corresponds to the closed state of the first valve body 151 and the closed state of the communication hole 114d.

[0079] The first valve body 151 has a head 151a, a first shaft portion 151b, and a second shaft portion 151c. The head 151a has a substantially hemispherical shape. The left side of the head 151a is spherical and can open and close the communication hole 114d. The first shaft portion 151b extends rightward from the right-facing side of the head 151a. The second shaft portion 151c extends rightward from the right-facing side of the first shaft portion 151b. The outer diameter of the second shaft portion 151c is smaller than the outer diameter of the first shaft portion 151b. The cross-sectional shapes of the first shaft portion 151b and the second shaft portion 151c are, for example, circular or polygonal. The first shaft portion 151b and the second shaft portion 151c are arranged coaxially with the central axis of the housing 101. A through hole 112a is formed at the center of the second cover 112, and the second shaft portion 151c is inserted through the through hole 112a. The third biasing member 143 is an elastic member such as a spring. The third biasing member 143 is arranged between the second cover 112 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 being contracted relative to its natural length. Therefore, the first valve body 151 is biased to the left by the third biasing member 143.

[0080] <Operation of the damping device>

[0081] Refer to Figures 2 - 5 , and the operation of the damping device 100 according to the embodiment of the present invention will be described.

[0082] 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 biased to the right by the first biasing member 141 and is located at the rightmost position in the movable range. Moreover, the second piston 122 is biased to the left by the second biasing member 142 and is located at the leftmost position in the movable range. The right end surface of the first piston 121 and the left end surface of the second piston 122 abut against each other at the axial position of the first opening PO1. In addition, the second valve body 152 does not abut against the protrusion portion 161a of the protrusion member 161 and is biased to the right by the fourth biasing member 144, and is in a closed state. The first valve body 151 is biased to the left by the third biasing member 143 and is in a closed state.

[0083] Here, in the hydraulic control unit 15, as described above, when anti-lock braking control or anti-skid control is executed, the pump 36 is driven. In Figure 2In the state, if the pump 36 is driven, the brake fluid flows into the attenuation device 100 through the first opening PO1, and the pressure of the space between the first piston 121 and the second piston 122 in the first liquid chamber S1 becomes higher. As a result, first, the first piston 121 moves to the left. For example, the elastic modulus of the first force member 141 becomes lower than the elastic modulus of the second force member 142, and the first piston 121 moves before the second piston 122. In addition, the elastic modulus is a physical property value that indicates the difficulty of deformation, and is also called a spring constant, an elastic constant, or an elastic coefficient.

[0084] Figure 3 It indicates that the first piston 121 and the attenuation device 100 Figure 2 The state is shifted to the left compared to the state of Figure 3 In the state, pressure is accumulated in the space between the first piston 121 and the second piston 122 in the first liquid chamber S1. Moreover, the first piston 121 is pushed to the left by the pressure in the space between the first piston 121 and the second piston 122, and Figure 2 Compared with the state of the first piston 121, the first piston 121 moves to the left. When the first piston 121 moves to the left, the first force member 141 expands and contracts, but as a result, it contracts. As a result, the force acting on the first piston 121 is absorbed by the first force member 141. In this way, the pressure pulsation is attenuated by the expansion and contraction of the first force member 141 as the first piston 121 moves.

[0085] Figure 4 It shows that the second piston 122 and the attenuation device 100 Figure 3 The state is shifted to the right compared to the state of Figure 4 In the state of , pressure is accumulated in the space between the first piston 121 and the second piston 122 in the first liquid chamber S1. And, by the pressure of the space between the first piston 121 and the second piston 122 in the first liquid chamber S1, the second piston 122 is pushed to the right, and Figure 3 Compared with the state of the second piston 122, the second piston 122 moves to the right. When the second piston 122 moves to the right, the second force applying member 142 expands and contracts, but the result is contraction. As a result, the force acting on the second piston 122 is absorbed by the second force applying member 142. In this way, the pressure pulsation is attenuated by the expansion and contraction of the second force applying member 142 as the second piston 122 moves.

[0086] Furthermore, in Figure 4In the state where, the front end of the protruding portion 161a of the protruding member 161 abuts against the second valve body 152. Thus, the movement of the second valve body 152 to the right is restricted by the protruding portion 161a. Therefore, even if the second piston 122 moves to the right, the second valve body 152 in the state of abutting against the protruding portion 161a does not move to the right. Thus, the position of the second valve body 152 is maintained at the position where it abuts against the protruding portion 161a, and the second valve body 152 moves relatively to the left with respect to the second piston 122 as compared with the Figure 3 state. As a result, the second valve body 152 moves away from the first through hole 122d. Therefore, the second valve body 152 becomes an open state, and the brake fluid can flow through the first through hole 122d.

[0087] Moreover, as the brake fluid flows into the hole portion 122c through the first through hole 122d, pressure is accumulated in the space on the left side of the third piston 123 in the hole portion 122c. Moreover, by the pressure in the space on the left side of the third piston 123 in the hole portion 122c, the third piston 123 is pushed to the right, and as compared with the Figure 3 state, the third piston 123 moves relatively to the right with respect to the second piston 122. When the third piston 123 moves to the right, the fifth biasing member 145 expands and contracts, but as a result, it contracts. Thus, the force acting on the third piston 123 is absorbed by the fifth biasing member 145. In this way, by the expansion and contraction of the fifth biasing member 145 as the third piston 123 moves, the pressure pulsation also attenuates.

[0088] Here, a small gap is interposed between the inner peripheral surface of the third piston 123 and the protruding portion 161a of the protruding member 161. Therefore, in the hole portion 122c, the brake fluid flows from the left side of the third piston 123 to the right side. The brake fluid sent to the right side of the third piston 123 is sent to the space on the right side of the second piston 122 in the first fluid chamber S1 through the second through hole 111b of the first cover 111. Here, the inner diameter of the second through hole 111b is small, and a large resistance acts on the brake fluid flowing through the second through hole 111b. Therefore, by the brake fluid flowing through the second through hole 111b, the pressure pulsation also attenuates.

[0089] In addition, as described above, a fourth through-hole 122e is formed in the second piston 122. Moreover, the brake fluid can flow from the hole portion 122b to the hole portion 122c through the fourth through-hole 122e of the second piston 122. In particular, even when the front end of the protruding portion 161a of the protruding member 161 does not abut against the second valve body 152 and the second valve body 152 is in a closed state, the brake fluid is also sent from the hole portion 122b to the hole portion 122c through the fourth through-hole 122e. Here, the inner diameter of the fourth through-hole 122e is small, and a relatively large resistance acts on the brake fluid flowing through the fourth through-hole 122e. Therefore, the pressure pulsation is attenuated as the brake fluid flows through the fourth through-hole 122e.

[0090] Figure 5 is a diagram showing a state in which the second piston 122 in the attenuation device 100 has moved to the right compared with the state of Figure 4 . In the state of Figure 5 , the second piston 122 has moved further to the right compared with the state of Figure 4 . Here, the brake fluid sent to the space on the right side of the second piston 122 in the first liquid chamber S1 is sent to the communication hole 114d through the third through-hole 161c of the base portion 161b of the protruding member 161. As a result, the pressure in the communication hole 114d becomes high, and the first valve body 151 is pushed and moved to the right. Therefore, as shown in Figure 5 , the first valve body 151 moves away from the communication hole 114d, the first valve body 151 becomes an open state, and the brake fluid can flow through the communication hole 114d. As a result, the brake fluid can flow out through the communication hole 114d from the second liquid chamber S2 via the second opening PO2.

[0091] Here, the inner diameter of the third through-hole 161c is small, and a relatively large resistance acts on the brake fluid flowing through the third through-hole 161c. Therefore, the pressure pulsation is attenuated as the brake fluid flows through the third through-hole 161c.

[0092] In addition, as shown in Figure 5 , when the first valve body 151 becomes an open state, the first valve body 151 can abut against the second cover 112. In the example of Figure 5 , the first shaft portion 151b and the second shaft portion 151c of the first valve body 151 move along the central axis of the housing 101. Here, as described above, in the second cover 112, in addition to the second opening PO2, a through-hole 112a is also formed. Here, the inner diameter of the through-hole 112a is larger than the outer diameter of the second shaft portion 151c and smaller than the outer diameter of the first shaft portion 151b. Therefore, the stepped surface between the first shaft portion 151b and the second shaft portion 151c in the first valve body 151 can abut against the second cover 112. As a result, when the first valve body 151 becomes an open state, the first valve body 151 does not vibrate, and the posture of the first valve body 151 is stabilized.

[0093] <Effect of the damping device>

[0094] The effect of the damping device 100 according to the embodiment of the present invention will be described.

[0095] 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 114d and communicating with an outlet port P2 via a second opening PO2; a first piston 121 slidably disposed in the first liquid chamber S1 and disposed on the side opposite to the second opening PO2 with respect to the first opening PO1 in the first liquid chamber S1; a first biasing member 141 biasing the first piston 121 toward the first opening PO1 side; a second piston 122 slidably disposed in the first liquid chamber S1 and disposed on the second opening PO2 side with respect to the first opening PO1 in the first liquid chamber S1; a second biasing member 142 biasing the second piston 122 toward the first opening PO1 side; a first valve body 151 disposed in the second liquid chamber S2 and capable of opening and closing the second opening PO2 side of the communication hole 114d; and a third biasing member 143 biasing the first valve body 151 toward the first opening PO1 side.

[0096] Thus, when the pump 36 is driven, first, pressure is accumulated in the space between the first piston 121 and the second piston 122 in the first liquid chamber S1. Then, during this period, as the first piston 121 moves, the first biasing member 141 gradually contracts, and the energy of the rising pressure is absorbed. Then, as the second piston 122 moves, the second biasing member 142 gradually contracts, and 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 second piston 122 becomes slower than the rising speed of the pressure on the first opening PO1 side with respect to the second piston 122. In addition, when the pressure on the first opening PO1 side decreases and the second piston 122 moves toward the first opening PO1 side, as the first biasing member 141 and the second biasing member 142 gradually extend, the decreasing speed of the pressure on the second opening PO2 side with respect to the second piston 122 becomes slower than the decreasing speed of the pressure on the first opening PO1 side with respect to the second piston 122. 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. Further, by increasing the pressure in the communication hole 114d to make the first valve body 151 in an open state, the brake fluid can be appropriately discharged from the second liquid chamber S2 via 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.

[0097] Preferably, the damping device 100 includes: a first through-hole 122d provided in the second piston 122 and penetrating from the first opening PO1 side to the second opening PO2 side; a second valve body 152 capable of opening and closing the first opening PO1 side of the first through-hole 122d; a fourth biasing member 144 that biases the second valve body 152 toward the second opening PO2 side; and a protruding member 161 disposed on the second opening PO2 side with respect to the second valve body 152, capable of being inserted into the first through-hole 122d and having a protruding portion 161a capable of abutting against the second valve body 152. Thus, during the driving of the pump 36 and the movement of the second piston 122 toward the second opening PO2 side, the second valve body 152 can be brought into an open state by means of the protruding portion 161a of the protruding member 161. Therefore, the brake fluid can be appropriately delivered to the second opening PO2 side relative to the second piston 122.

[0098] Preferably, the damping device 100 includes: a hole portion 122c formed by being recessed from the second opening PO2 side toward the first opening PO1 side in the second piston 122 and communicating with the first through-hole 122d; a third piston 123 slidably provided in the hole portion 122c; and a fifth biasing member 145 that biases the third piston 123 toward the first opening PO1 side. Thus, when the pump 36 is driven, in addition to the movement of the first piston 121 and the second piston 122, the movement of the third piston 123 also occurs. Moreover, by the expansion and contraction of the fifth biasing member 145 as the third piston 123 moves, the pressure pulsation can be further attenuated. Therefore, the pressure pulsation can be attenuated more effectively.

[0099] Preferably, the damping device 100 includes a first cover 111 that covers the hole portion 122c from the second opening PO2 side; in the first cover 111, at least one second through-hole 111b penetrating from the first opening PO1 side to the second opening PO2 side is formed. Thus, the pressure pulsation can also be attenuated by the brake fluid flowing through the second through-hole 111b.

[0100] Preferably, in the damping device 100, a plurality of second through-holes 111b are formed in the first cover 111, and the plurality of second through-holes 111b are arranged at equal intervals in the circumferential direction of the first cover 111. Thus, around the first cover 111, the flow region of the brake fluid is homogenized in the circumferential direction. Therefore, the brake fluid can flow smoothly within the damping device 100.

[0101] Preferably, in the damping device 100, the protruding member 161 has a base portion 161b that is connected to the protruding portion 161a and covers the first opening PO1 side of the communication hole 114d; in the base portion 161b, a third through hole 161c is formed that penetrates from the first opening PO1 side to the second opening PO2 side. Thus, by allowing the brake fluid to flow through the third through hole 161c, it is also possible to attenuate the pressure pulsation.

[0102] Preferably, in the damping device 100, at least one fourth through hole 122e that penetrates from the first opening PO1 side to the second opening PO2 side is formed in the second piston 122. Thus, by allowing the brake fluid to flow through the fourth through hole 122e, it is also possible to attenuate the pressure pulsation. Here, consider the situation where the second piston 122 adheres and can no longer move. In such a situation, the brake fluid can flow from the first opening PO1 side of the second piston 122 to the second opening PO2 side through the fourth through hole 122e. Therefore, an excessive increase in the pressure of the space on the first opening PO1 side of the second piston 122 in the first liquid chamber S1 is suppressed.

[0103] Preferably, in the damping device 100, a plurality of fourth through holes 122e are formed in the second piston 122, and the plurality of fourth through holes 122e are arranged at equal intervals in the circumferential direction of the second piston 122. Thus, the force generated due to the flow of the brake fluid through the fourth through hole 122e acts equally on the second piston 122 in the circumferential direction. Therefore, the inclination of the second piston 122 with respect to the sliding direction is suppressed by the force acting on the second piston 122 due to the flow of the brake fluid through the fourth through hole 122e.

[0104] Preferably, the damping device 100 includes a second cover 112 that covers the second liquid chamber S2 from the second opening PO2 side; the first valve body 151 can abut against the second cover 112. Thus, when the first valve body 151 is in the open state, the first valve body 151 does not vibrate, and the posture of the first valve body 151 is stabilized. Therefore, the opening and closing operation of the first valve body 151 can be made smooth.

[0105] Preferably, in the damping device 100, the elastic modulus of the first biasing member 141 is lower than the elastic modulus of the second biasing member 142. Thus, it is possible to appropriately achieve the movement of the first piston 121 before the second piston 122. Therefore, it is possible to suppress the occurrence of a situation where the first piston 121 does not move and the energy absorption by the first biasing member 141 is not performed.

[0106] As described above, while referring to the Figure 1 preferred embodiments of the present invention have been described, the present invention is of course not limited to the above embodiments, and 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.

[0107] In the above, with reference to Figure 2 the structure of the attenuation device 100 has been described. However, structures with various modifications to the Figure 2 example can also be included in the attenuation device according to the present invention.

[0108] 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.

[0109] 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. This cross-sectional shape may, for example, also be an ellipse or a polygon, etc. 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 respective central axes of the first piston 121 and the second piston 122.

[0110] In addition, for example, the cross-sectional shape of the first cover 111 orthogonal to the axial direction may not be circular. This cross-sectional shape may, for example, also be an ellipse or a polygon, etc. Also, in this case, the circumferential direction of the first cover 111 is also the direction along the outer peripheral edge of the first cover 111, and is the direction around the central axis of the first cover 111.

[0111] In addition, for example, a structure in which the second through-hole 111b is omitted with respect to the Figure 2 example can also be included in the attenuation device according to the present invention. Also, when the second through-hole 111b is omitted, a small gap is also formed between the inner peripheral surface of the first cover 111 and the protruding portion 161a of the protruding member 161, and the brake fluid can flow through this gap from the left side to the right side of the first cover 111.

[0112] In addition, for example, a structure in which the fourth through-hole 122e is omitted with respect to the Figure 2 example can also be included in the attenuation device according to the present invention. Also, when the fourth through-hole 122e is omitted, for example, a groove extending in the axial direction may be provided on the inner peripheral surface of the second hole portion 101b, and the brake fluid can flow through this groove from the left side to the right side of the second piston 122.

[0113] In addition, for example, with respect to the Figure 2 example, the shape of the first valve body 151 may be changed to another shape such as a spherical shape, and the first valve body 151 may not be in contact with the second cover 112.

[0114] In addition, for example, it is also possible to change the structure of the second piston 122 with respect to Figure 2 the example of Figure 2 and omit the third piston 123 from the second piston 122. In addition, for example, it is also possible to omit the first through-hole 122d, the second valve body 152, the fourth biasing member 144, and the protruding member 161 with respect to Figure 2 the example of. In this case, for example, it is also possible to provide a groove extending in the axial direction on the inner peripheral surface of the second hole portion 101b, and the brake fluid can flow from the left side to the right side of the second piston 122 through this groove. In addition, for example, it is also possible that the second piston 122 can abut against the first valve body 151, and the first valve body 151 is opened by being pushed by the second piston 122.

[0115] Description of Reference Numerals

[0116] 1 Brake system

[0117] 11 Brake pedal

[0118] 12 Force multiplier

[0119] 13 Master cylinder

[0120] 14 Reservoir

[0121] 15 Hydraulic control unit

[0122] 16 Brake device

[0123] 17 Wheel

[0124] 21 Main flow path

[0125] 22 Sub-flow path

[0126] 23 Supply flow path

[0127] 31 Filling valve

[0128] 32 Release valve

[0129] 33 First valve

[0130] 34 Second valve

[0131] 35 Accumulator

[0132] 36 Pump

[0133] 37 Motor

[0134] 100 Damping device

[0135] 101 Housing

[0136] 111 First cover

[0137] 111b Second through-hole

[0138] 112th second cover

[0139] 113th third cover

[0140] 114th fourth cover

[0141] 114d communication hole

[0142] 115th fifth cover

[0143] 121st first piston

[0144] 122nd second piston

[0145] 122c hole part

[0146] 122d first through-hole

[0147] 123rd third piston

[0148] 131st first sealing member

[0149] 132nd second sealing member

[0150] 133rd third sealing member

[0151] 141st first biasing member

[0152] 142nd second biasing member

[0153] 143rd third biasing member

[0154] 144th fourth biasing member

[0155] 145th fifth biasing member

[0156] 151st first valve body

[0157] 152nd second valve body

[0158] 161 projection member

[0159] 161a projection portion

[0160] 161b base portion

[0161] 161c third through-hole

[0162] P1 inlet port

[0163] P2 outlet port

[0164] PO1 first opening

[0165] PO2 second opening

[0166] S1 first liquid chamber

[0167] S2 second liquid chamber

Claims

1. An attenuation device (100) is provided in a hydraulic control unit (15) that controls the braking force generated at a wheel (17). The attenuation 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 (114d) and communicating with the outlet port (P2) via a second opening (PO2); A first piston (121) slidably disposed in the first liquid chamber (S1) and disposed on the side opposite to the second opening (PO2) with respect to the first opening (PO1) in the first liquid chamber (S1); A first biasing member (141) biasing the first piston (121) toward the first opening (PO1) side; A second piston (122) slidably disposed in the first liquid chamber (S1) and disposed on the second opening (PO2) side with respect to the first opening (PO1) in the first liquid chamber (S1); A second biasing member (142) biasing the second piston (122) toward the first opening (PO1) side; A first valve body (151) disposed in the second liquid chamber (S2) and capable of opening and closing the second opening (PO2) side of the communication hole (114d); and A third biasing member (143) biasing the first valve body (151) toward the first opening (PO1) side.

2. The attenuation device according to claim 1, It is characterized in that: It includes: A first through hole (122d) disposed in the second piston (122) and penetrating from the first opening (PO1) side to the second opening (PO2) side; A second valve body (152) capable of opening and closing the first opening (PO1) side of the first through hole (122d); A fourth biasing member (144) biasing the second valve body (152) toward the second opening (PO2) side; and A protrusion member (161) disposed on the second opening (PO2) side with respect to the second valve body (152), capable of being inserted into the first through hole (122d), and having a protrusion portion (161a) capable of abutting against the second valve body (152).

3. The attenuation device according to claim 2, It is characterized in that: It includes: A hole portion (122c) formed by recessing the second piston (122) from the second opening (PO2) side toward the first opening (PO1) side and communicating with the first through hole (122d); A third piston (123) slidably disposed in the hole portion (122c); and A fifth biasing member (145) biasing the third piston (123) toward the first opening (PO1) side.

4. The attenuation device according to claim 3, It is characterized in that: A first cover (111) capable of covering the aforementioned hole portion (122c) from the side of the aforementioned second opening (PO2); In the aforementioned first cover (111), at least one second through-hole (111b) penetrating from the side of the aforementioned first opening (PO1) to the side of the aforementioned second opening (PO2) is formed.

5. The attenuation device according to claim 4, characterized in that in the aforementioned first cover (111), a plurality of the aforementioned second through-holes (111b) are formed; the plurality of the aforementioned second through-holes (111b) are arranged at equal intervals in the circumferential direction of the aforementioned first cover (111).

6. The attenuation device according to claim 2, characterized in that the aforementioned protruding member (161) has a base portion (161b) connected to the aforementioned protruding portion (161a) and covering the side of the aforementioned first opening (PO1) of the aforementioned communication hole (114d); in the aforementioned base portion (161b), a third through-hole (161c) penetrating from the side of the aforementioned first opening (PO1) to the side of the aforementioned second opening (PO2) is formed.

7. The attenuation device according to claim 1, characterized in that in the aforementioned second piston (122), at least one fourth through-hole (122e) penetrating from the side of the aforementioned first opening (PO1) to the side of the aforementioned second opening (PO2) is formed.

8. The attenuation device according to claim 7, characterized in that in the aforementioned second piston (122), a plurality of the aforementioned fourth through-holes (122e) are formed; the plurality of the aforementioned fourth through-holes (122e) are arranged at equal intervals in the circumferential direction of the aforementioned second piston (122).

9. The attenuation device according to claim 1, characterized in that it includes a second cover (112) capable of covering the aforementioned second liquid chamber (S2) from the side of the aforementioned second opening (PO2); the aforementioned first valve body (151) can abut against the aforementioned second cover (112).

10. The attenuation device according to claim 1, characterized in that the elastic modulus of the aforementioned first biasing member (141) is lower than that of the aforementioned second biasing member (142).

11. A hydraulic control unit, characterized in that it includes the attenuation device (100) according to any one of claims 1 to 10.

12. A braking system, characterized in that it includes the hydraulic control unit (15) according to claim 11.

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