Damping device, hydraulic control unit, and brake system

Abstract

The present invention dampens pressure pulsation in a liquid-pressure control unit. The present invention provides a damping device, which is provided in a liquid-pressure control unit that controls braking forces generated in wheels, the device serving to attenuate pressure pulsation and having an inlet port which is connected to a discharge side of a pump, and an outlet port which communicates with the inlet port. The damping device includes: a first liquid chamber which communicates with the inlet port via a first opening; a second liquid chamber which communicates with the first liquid chamber through a communication hole and communicates with the outlet port through a second opening; a first piston slidably provided in the first liquid chamber and placed on the opposite side from the second opening with respect to the first opening in the first liquid chamber; a first biasing member for biasing the first piston toward the first opening; a second piston slidably provided in the first liquid chamber and placed on the second opening side with respect to the first opening in the first liquid chamber; a second biasing member for biasing the second piston toward the first opening; a first valve element provided in the second liquid chamber and capable of opening and closing the second opening side of the communication hole; and a third biasing member for biasing the first valve element toward the first opening.

Description

Technical Field

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

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document No. 1

Summary of the Invention

Problems to be Solved by the Invention

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

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

[0006] To solve the above problems, the damping device is provided in a hydraulic control unit (15) that controls the braking force generated in the wheel (17), and has an inlet port (P1) connected to the discharge side of a pump (36), and an outlet port (P2) communicating with the inlet port (P1), and is a damping device (100) that dampens pressure pulsations, comprising: 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), and a slidable device provided in the first liquid chamber (S1) with respect to the first opening (PO1) of the first liquid chamber (S1) A first piston (121) positioned on the opposite side of the opening (PO2), a first biasing member (141) that biases the first piston (121) toward the first opening (PO1), a second piston (122) slidably provided in the first liquid chamber (S1) and positioned on the side of the first liquid chamber (S1) toward the second opening (PO2), a second biasing member (142) that biases the second piston (122) toward the first opening (PO1), a first valve body (151) provided 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) that biases the first valve body (151) toward the first opening (PO1), The second piston (122) is provided with a first through-hole (122d) that penetrates from the first opening (PO1) side to the second opening (PO2) side, a second valve body (152) that can open and close 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 the second valve is positioned toward the second opening (PO2) side relative to the second valve body (152) and is insertable into the first through-hole (122d), The present invention comprises a projection member (161) having a projection (161a) that can abut against the body (152), a hole (122c) formed in the second piston (122) that is recessed from the second opening (PO2) side toward the first opening (PO1) side and communicates with the first through hole (122d), a third piston (123) slidably provided in the hole (122c), and a fifth biasing member (145) that biases the third piston (123) toward the first opening (PO1), It is equipped with.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0036] As shown in Figure 2, the damping device 100 comprises a housing 101, a first cover 111, a second cover 112, a third cover 113, a fourth cover 114, a fifth cover 115, a first piston 121, a second piston 122, a third piston 123, a first seal member 131, a second seal member 132, a third seal 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 projection member 161.

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

[0038] The third cover 113 is fitted into the first hole 101a. The third cover 113 has a substantially disc shape. The left end of the outer surface of the third cover 113 is radially widened outward. The radially widened portion of the third cover 113 is fitted into the first hole 101a.

[0039] The fourth cover 114 is fitted into the second hole 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 are cylindrical in shape and are arranged coaxially with respect to each other. The first cylindrical portion 114a and the second cylindrical portion 114b are continuous in this order from the right. 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 of the second hole 101b. The outer circumferential surface of the second cylindrical portion 114b is radially separated from the inner circumferential surface of the second hole 101b. A recess 114c is formed in the center of the left side surface of the second cylindrical portion 114b. The recessed portion 114c has a cylindrical shape and is arranged coaxially with the second cylindrical portion 114b. The base portion 161b of the projection member 161, which will be described later, is fitted into the recessed portion 114c.

[0040] A first opening PO1 is formed between the third cover 113 and the fourth cover 114 in the peripheral wall portion of the housing 101. The first opening PO1 communicates with the second hole 101b. 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 101b of the housing 101 define the first liquid chamber S1. In other words, 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. To put it another way, 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.

[0041] The inner circumferential surface of the first cylindrical portion 114a of the fourth cover 114 defines the second liquid chamber S2. The second liquid chamber S2 communicates with the recessed portion 114c via the communication hole 114d. The recessed portion 114c, the communication hole 114d, and the second liquid chamber S2 are continuous in this order from left to right and are arranged coaxially with each other. The second liquid chamber S2 communicates with the first liquid chamber S1 via the communication hole 114d.

[0042] The second cover 112 is fitted to the right end of the inner circumferential 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 located radially outward from the center of the second cover 112. In the example in Figure 2, there are multiple second openings PO2. However, there may be only one second opening PO2.

[0043] The right end of the inner circumferential surface of the first cylindrical portion 114a of the fourth cover 114 is enlarged in diameter. The second cover 112 is fitted onto the enlarged portion of the inner circumferential surface of the first cylindrical portion 114a. As a result, the second liquid chamber S2 is partitioned by the left side surface of the second cover 112. In other words, the second cover 112 covers the second liquid chamber S2 from the right side. To put it another way, the left side surface of the second cover 112 constitutes the right side wall of the second liquid chamber S2. The second liquid chamber S2 communicates with the outlet port P2 via the second opening PO2.

[0044] The first piston 121 is housed within the second bore 101b. The first piston 121 has a substantially cylindrical shape. The first piston 121 is positioned coaxially with the central axis of the second bore 101b. The outer circumferential surface of the first piston 121 is slidable against the inner circumferential surface of the second bore 101b. Therefore, the first piston 121 is provided to be axially slidable within the first liquid chamber S1. Here, the first piston 121 is positioned to the left of the first opening PO1 within the first liquid chamber S1. In other words, the first piston 121 is positioned on the opposite side of the second opening PO2 from the first opening PO1 within the first liquid chamber S1.

[0045] An annular groove 121a is formed on the outer circumferential surface of the first piston 121. The annular groove 121a extends in the circumferential direction of the first piston 121. A 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 circumferential surface of the second hole 101b. As a result, the gap between the outer circumferential surface of the first piston 121 and the inner circumferential surface of the second hole 101b is sealed liquid-tightly.

[0046] The first piston 121 is biased to the right by the first biasing member 141. The first biasing member 141 is, for example, an elastic member such as a spring. The first biasing member 141 is positioned between the first piston 121 and the third cover 113. One end of the first biasing member 141 (the right end in Figure 2) abuts against the recess 121b of the first piston 121. The recess 121b is located in the center of the left side surface of the first piston 121. The other end of the first biasing member 141 (the left end in Figure 2) abuts against the right side surface of the third cover 113. The direction of expansion and contraction of the first biasing member 141 is left-right. The first biasing member 141 is in a contracted state relative to its natural length.

[0047] The second piston 122 is housed inside the second hole 101b. The second piston 122 has a substantially cylindrical shape. The second piston 122 is positioned coaxially with the central axis of the second hole 101b. The outer circumferential surface of the second piston 122 is slidable against the inner circumferential surface of the second hole 101b. Therefore, the second piston 122 is provided to be slidable in the axial direction within the first liquid chamber S1. Here, the second piston 122 is positioned to the right of the first opening PO1 within the first liquid chamber S1. In other words, the second piston 122 is positioned on the side of the second opening PO2 relative to the first opening PO1 within the first liquid chamber S1.

[0048] An annular groove 122a is formed on the outer circumferential surface of the second piston 122. The annular groove 122a extends in the circumferential direction of the second piston 122. A second sealing member 132 is fitted into the annular groove 122a. The second sealing member 132 is, for example, an O-ring. The second sealing member 132 is pressed against the inner circumferential surface of the second hole 101b. This seals the gap between the outer circumferential surface of the second piston 122 and the inner circumferential surface of the second hole 101b in a liquid-tight manner. In the example of Figure 2, two annular grooves 122a are arranged with an axial gap between them, and a second sealing member 132 is fitted into each annular groove 122a. However, the number of annular grooves 122a may be one or three or more.

[0049] 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 positioned between the second piston 122 and the fourth cover 114. One end of the second biasing member 142 (the left end in Figure 2) abuts against the right end surface of the second piston 122. The other end of the second biasing member 142 (the right end in Figure 2) abuts against the left side surface of the first cylindrical portion 114a of the fourth cover 114. The direction of expansion and contraction of the second biasing member 142 is left-right. The second biasing member 142 is in a contracted state relative to its natural length.

[0050] The second piston 122 has a hole 122b formed therein. The hole 122b is a recessed portion of the second piston 122 that extends from left to right. The hole 122b is recessed from the left end face of the second piston 122 to the right. The hole 122b is located coaxially with the central axis of the housing 101. However, the hole 122b does not have to be located coaxially with the central axis of the housing 101.

[0051] The fifth cover 115 is fitted to the left end of the inner circumferential surface of the hole 122b. The fifth cover 115 is formed in a disc shape with a through hole 115a in the center. The through hole 115a penetrates the fifth cover 115 from left to right. The left end of the inner circumferential surface of the hole 122b is enlarged in diameter. The fifth cover 115 is fitted to the enlarged portion of the inner circumferential surface of the hole 122b. The space to the left of the second piston 122 in the first liquid chamber S1 and the hole 122b are in communication via the through hole 115a of the fifth cover 115.

[0052] The second piston 122 has a hole 122c formed therein. The hole 122c is a recessed portion of the second piston 122 that extends from the right side to the left side. The hole 122c is recessed from the right end face of the second piston 122 to the left side. The hole 122c is located coaxially with the central axis of the housing 101. However, the hole 122c does not have to be located coaxially with the central axis of the housing 101.

[0053] The first cover 111 is fitted to the rightmost part of the inner circumferential surface of the hole 122c. The first cover 111 is formed in a substantially cylindrical shape. The rightmost part of the outer circumferential surface of the first cover 111 is enlarged in diameter. The enlarged portion of the outer circumferential surface of the first cover 111 is fitted to the rightmost part of the inner circumferential surface of the hole 122c. In this way, the first cover 111 covers the hole 122c from the right side.

[0054] Holes 122b and 122c are connected via the first through-hole 122d. Thus, the first through-hole 122d penetrates the second piston 122 from left to right. Holes 122b, the first through-hole 122d, and 122c are continuous in this order from left to right and are arranged coaxially with each other. The inner diameter of the first through-hole 122d is smaller than the inner diameter of both hole 122b and hole 122c. In the example of Figure 2, the inner diameter of hole 122b is smaller than the inner diameter of hole 122c. However, the inner diameter of hole 122b may be the same as the inner diameter of hole 122c, or it may be larger than the inner diameter of hole 122c.

[0055] The second piston 122 has a plurality of fourth through holes 122e. The fourth through holes 122e penetrate the second piston 122 from left to right. In the example in Figure 2, the fourth through holes 122e are arranged around the first through hole 122d and extend from the right inner surface of hole 122b to the left inner surface of hole 122c. The inner diameter of the fourth through hole 122e is, for example, about 0.4 mm to 0.5 mm in diameter. In the example in Figure 2, the fourth through hole 122e extends in the axial direction. However, the path of the fourth through hole 122e is not particularly limited; for example, the fourth through hole 122e may extend in a direction inclined with respect to the axial direction, and may be curved or bent.

[0056] Multiple fourth through-holes 122e are arranged at equal intervals in the circumferential direction of the second piston 122. However, the arrangement of the multiple fourth through-holes 122e is not limited to this example. For example, the multiple fourth through-holes 122e may be arranged at unequal intervals in the circumferential direction. Also, there may be only one fourth through-hole 122e. Brake fluid can flow through the fourth through-holes 122e from the left side to the right side of the second piston 122. In particular, even when the second valve body 152, which will be described later, is closed, brake fluid can flow through the fourth through-holes 122e from the left side to the right side of the second piston 122. The fourth through-holes 122e are provided to enhance the effect of reducing pressure pulsation. The function of the fourth through-holes 122e will be described later.

[0057] The second valve body 152 is provided in the hole 122b and can open and close the left side of the first through hole 122d. When the second valve body 152 is in the open state and does not block the first through hole 122d, 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. When the second valve body 152 is in the closed state and blocks the first through hole 122d, 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.

[0058] The second valve body 152 has, for example, a spherical shape. However, the shape of the second valve body 152 may be other than spherical. The fourth biasing member 144 is, for example, an elastic member such as a spring. The fourth biasing member 144 is positioned between the fifth cover 115 and the second valve body 152. The direction of expansion and contraction of the fourth biasing member 144 is left-right. The fourth biasing member 144 is in a contracted state relative to its natural length. Therefore, the second valve body 152 is biased to the right by the fourth biasing member 144.

[0059] The third piston 123 is housed in the bore 122c. The third piston 123 has a substantially cylindrical shape. The third piston 123 is positioned coaxially with the central axis of the bore 122c. The outer circumferential surface of the third piston 123 is slidable against the inner circumferential surface of the bore 122c. Therefore, the third piston 123 is provided to be slidable in the axial direction within the bore 122c.

[0060] An annular groove 123a is formed on the outer circumferential surface of the third piston 123. The annular groove 123a extends in the circumferential direction of the third piston 123. A third sealing member 133 is fitted into the annular groove 123a. The third sealing member 133 is, for example, an O-ring. The third sealing member 133 is pressed against the inner circumferential surface of the hole 122c. As a result, the gap between the outer circumferential surface of the third piston 123 and the inner circumferential surface of the hole 122c is sealed liquid-tightly.

[0061] The third piston 123 is biased to the left by the fifth biasing member 145. The fifth biasing member 145 is, for example, an elastic member such as a spring. The fifth biasing member 145 is positioned between the third piston 123 and the first cover 111. One end of the fifth biasing member 145 (the left end in Figure 2) abuts against the recess 123b of the third piston 123. The recess 123b is formed in an annular shape along the inner periphery of the third piston 123 on the right side surface of the third piston 123. The other end of the fifth biasing member 145 (the right end in Figure 2) abuts against the recess 111a of the first cover 111. The recess 111a is formed in an annular shape along the inner periphery of the first cover 111 on the left side surface of the first cover 111. The extension and retraction direction of the fifth biasing member 145 is left-right. The fifth biasing member 145 is in a contracted state relative to its natural length.

[0062] Multiple second through-holes 111b are formed in the first cover 111. The second through-holes 111b penetrate the first cover 111 from the left side to the right side. In the example in Figure 2, 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 the example in Figure 2, 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 extend in a direction inclined with respect to the axial direction, and may be curved or bent.

[0063] Multiple second through-holes 111b are arranged at equal intervals in the circumferential direction of the first cover 111. However, the arrangement of the multiple second through-holes 111b is not limited to this example. For example, the multiple second through-holes 111b may be arranged at unequal intervals in the circumferential direction. Also, there may be only one second through-hole 111b. Brake fluid can flow through the second through-holes 111b from the left side to the right side of the first cover 111. The second through-holes 111b are provided to enhance the effect of reducing pressure pulsation. The function of the second through-holes 111b will be described later.

[0064] The projection member 161 is provided to open and close the second valve body 152. The projection member 161 is positioned to the right of the second valve body 152. The projection member 161 has a projection 161a and a base 161b. The base 161b has a substantially disc shape. The base 161b is fitted into the recess 114c of the fourth cover 114. Therefore, the base 161b covers the left side of the communication hole 114d. The projection 161a is connected to the base 161b. The projection 161a protrudes to the left from the center of the base 161b.

[0065] The projection 161a is positioned coaxially with the first cover 111, the third piston 123, and the first through hole 122d. The projection 161a is inserted through the central cavity of the first cover 111 and the central cavity of the third piston 123. As the second piston 122 moves to the right from the position shown in Figure 2, the projection 161a is inserted into the first through hole 122d, and the tip of the projection 161a can contact the second valve body 152. The position of the second valve body 152 is maintained by the tip of the projection 161a contacting the second valve body 152. In this state, as the second piston 122 moves further to the right, the second valve body 152 opens. Thus, the projection 161a is insertable into the first through hole 122d and can contact the second valve body 152.

[0066] A third through-hole 161c is formed in the base portion 161b. The third through-hole 161c penetrates the base portion 161b from left to right. The inner diameter of the third through-hole 161c is, for example, about 0.4 mm to 0.5 mm in diameter. The path of the third through-hole 161c is not particularly limited to the example in Figure 2, and for example, the number and arrangement of the branching portions of the third through-hole 161c may differ from the example in Figure 2.

[0067] The first valve body 151 is provided in the second fluid chamber S2 and can open and close the right side of the communication hole 114d. When the first valve body 151 is in the open state and does not block the communication hole 114d, 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. When the first valve body 151 is in the closed state and blocks the communication hole 114d, 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.

[0068] The first valve body 151 has a head portion 151a, a first shaft portion 151b, and a second shaft portion 151c. The head portion 151a has a substantially hemispherical shape. The left side of the head portion 151a is spherical, allowing the communication hole 114d to be opened and closed. The first shaft portion 151b extends to the right from the right side surface of the head portion 151a. The second shaft portion 151c extends to the right from the right side surface 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 in 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, for example, an elastic member such as a spring. The third biasing member 143 is positioned between the second cover 112 and the first valve body 151. The direction of expansion and contraction of the third biasing member 143 is left-right. The third biasing member 143 is in a contracted state relative to its natural length. Therefore, the first valve body 151 is biased to the left by the third biasing member 143.

[0069] <Operation of the damping device> The operation of the damping device 100 according to an embodiment of the present invention will be described with reference to Figures 2 to 5.

[0070] Figure 2 above shows the damping device 100 in the hydraulic control unit 15 under normal conditions when the pump 36 is not driven. In this case, the first piston 121 is biased to the right by the first biasing member 141 and is located at the far right of its range of motion. The second piston 122 is biased to the left by the second biasing member 142 and is located at the far left of its range of motion. The right end face of the first piston 121 and the left end face of the second piston 122 are in contact with each other at the axial position of the first opening PO1. The second valve body 152 is not in contact with the projection 161a of the projection 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.

[0071] Here, in the hydraulic control unit 15, as described above, the pump 36 is driven when anti-lock brake control or anti-skid control is performed. In the state shown in Figure 2, when the pump 36 is driven, brake fluid flows into the damping device 100 through the first opening PO1, and the pressure in the space between the first piston 121 and the second piston 122 in the first fluid chamber S1 increases. As a result, the first piston 121 moves to the left first. For example, because the elastic modulus of the first biasing member 141 is lower than the elastic modulus of the second biasing member 142, the first piston 121 moves before the second piston 122. The elastic modulus is a physical property value that represents the resistance to deformation, and is also called the spring constant, elastic constant, or elastic modulus.

[0072] Figure 3 shows the damping device 100 in a state where the first piston 121 has moved to the left compared to the state in Figure 2. In the state in Figure 3, pressure is stored in the space between the first piston 121 and the second piston 122 in the first liquid chamber S1. The pressure in the space between the first piston 121 and the second piston 122 pushes the first piston 121 to the left, causing it to move to the left compared to the state in Figure 2. As the first piston 121 moves to the left, the first biasing member 141 expands and contracts, and consequently shrinks. As a result, the force acting on the first piston 121 is absorbed by the first biasing member 141. In this way, the pressure pulsation is dampened as the first biasing member 141 expands and contracts in conjunction with the movement of the first piston 121.

[0073] Figure 4 shows the damping device 100 in a state where the second piston 122 has moved to the right compared to the state in Figure 3. In the state in Figure 4, pressure is stored in the space between the first piston 121 and the second piston 122 in the first liquid chamber S1. The pressure in the space between the first piston 121 and the second piston 122 in the first liquid chamber S1 pushes the second piston 122 to the right, causing it to move to the right compared to the state in Figure 3. As the second piston 122 moves to the right, the second biasing member 142 expands and contracts, and consequently shrinks. As a result, the force acting on the second piston 122 is absorbed by the second biasing member 142. In this way, the pressure pulsation is dampened as the second biasing member 142 expands and contracts in conjunction with the movement of the second piston 122.

[0074] Furthermore, in the state shown in Figure 4, the tip of the projection 161a of the projection member 161 is in contact with the second valve body 152. As a result, the movement of the second valve body 152 to the right is restricted by the projection 161a. Therefore, even if the second piston 122 moves to the right, the second valve body 152, which is in contact with the projection 161a, does not move to the right. Thus, the position of the second valve body 152 is maintained in contact with the projection 161a, and the second valve body 152 has moved to the left relative to the second piston 122 compared to the state shown in Figure 3. As a result, the second valve body 152 moves away from the first through hole 122d. Therefore, the second valve body 152 opens, and brake fluid can flow through the first through hole 122d.

[0075] As brake fluid flows into the hole 122c through the first through-hole 122d, pressure is accumulated in the space to the left of the third piston 123 within the hole 122c. This pressure in the space to the left of the third piston 123 within the hole 122c pushes the third piston 123 to the right, causing it to move to the right relative to the second piston 122 compared to the state shown in Figure 3. As the third piston 123 moves to the right, the fifth biasing member 145 expands and contracts, resulting in a contraction. As a result, the force acting on the third piston 123 is absorbed by the fifth biasing member 145. In this way, the expansion and contraction of the fifth biasing member 145 in conjunction with the movement of the third piston 123 also dampens the pressure pulsation.

[0076] Here, a small gap exists between the inner circumferential surface of the third piston 123 and the projection 161a of the projection member 161. Therefore, in the hole 122c, brake fluid flows from the left to the right of the third piston 123. The brake fluid sent to the right of the third piston 123 passes through the second through hole 111b of the first cover 111 and is sent to the space to the right of the second piston 122 in the first fluid chamber S1. Here, the inner diameter of the second through hole 111b is small, and the brake fluid flowing through the second through hole 111b experiences significant resistance. Therefore, the flow of brake fluid through the second through hole 111b also dampens pressure pulsation.

[0077] Furthermore, as described above, the second piston 122 has a fourth through-hole 122e. Brake fluid can flow through the fourth through-hole 122e of the second piston 122 from hole 122b to hole 122c. In particular, even when the tip of the projection 161a of the projection member 161 is not in contact with the second valve body 152 and the second valve body 152 is in a closed state, brake fluid is sent through the fourth through-hole 122e from hole 122b to hole 122c. Here, the inner diameter of the fourth through-hole 122e is small, and the brake fluid flowing through the fourth through-hole 122e faces significant resistance. Therefore, the flow of brake fluid through the fourth through-hole 122e also dampens pressure pulsation.

[0078] Figure 5 shows the damping device 100 in a state where the second piston 122 has moved to the right compared to the state in Figure 4. In the state in Figure 5, the second piston 122 has moved further to the right compared to the state in Figure 4. Here, the brake fluid sent to the space to the right of the second piston 122 in the first fluid chamber S1 is sent to the communication hole 114d through the third through hole 161c of the base 161b of the projection member 161. As a result, the pressure in the communication hole 114d increases, and the first valve body 151 is pushed to the right and moves. Therefore, as shown in Figure 5, the first valve body 151 moves away from the communication hole 114d, the first valve body 151 becomes open, and brake fluid can flow through the communication hole 114d. Thus, the brake fluid flows out from the second fluid chamber S2 through the second opening PO2 via the communication hole 114d.

[0079] Here, the inner diameter of the third through-hole 161c is small, and the brake fluid flowing through the third through-hole 161c experiences significant resistance. Therefore, the flow of brake fluid through the third through-hole 161c also dampens the pressure pulsation.

[0080] Furthermore, as shown in Figure 5, when the first valve body 151 is in the open state, the first valve body 151 can come into contact with 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 addition to the second opening PO2, the second cover 112 has a through hole 112a. Here, the inner diameter of the through hole 112a is larger than the outer diameter of the second shaft portion 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 of the first valve body 151 can come into contact with the second cover 112. As a result, even when the first valve body 151 is in the open state, the first valve body 151 does not vibrate and its posture is stabilized.

[0081] <Effects of the damping device> The effects of the damping device 100 according to an embodiment of the present invention will be described below.

[0082] 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 mounted in the first liquid chamber S1 and positioned on the side of the first liquid chamber S1 opposite to the second opening PO2 relative to the first opening PO1, and a first attachment that biases the first piston 121 toward the first opening PO1. The device comprises a biasing member 141, a second piston 122 slidably provided in the first liquid chamber S1 and positioned on the second opening PO2 side relative to the first opening PO1 in the first liquid chamber S1, a second biasing member 142 that biases the second piston 122 toward the first opening PO1, a first valve body 151 provided 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 that biases the first valve body 151 toward the first opening PO1.

[0083] As a result, when the pump 36 is driven, pressure is first stored in the space between the first piston 121 and the second piston 122 in the first liquid chamber S1. During this time, as the first piston 121 moves, the first biasing member 141 gradually contracts, absorbing the energy of the pressure rise. Then, as the second piston 122 moves, the second biasing member 142 gradually contracts, absorbing the energy of the pressure rise. As a result, the rate of pressure rise on the second opening PO2 side is slower than the rate of pressure rise on the first opening PO1 side than the rate of pressure rise on the second piston 122. Furthermore, when the pressure on the first opening PO1 side decreases and the second piston 122 moves toward the first opening PO1 side, the first biasing member 141 and the second biasing member 142 gradually extend, so that the rate of pressure decrease on the second opening PO2 side is slower than the rate of pressure decrease on the first opening PO1 side than the rate of pressure decrease on the second piston 122. This allows the pressure pulsation on the second opening PO2 side to be attenuated relative to the pressure pulsation on the first opening PO1 side. Furthermore, by increasing the pressure in the communication hole 114d, the first valve body 151 can be opened, allowing brake fluid to flow out appropriately from the second fluid chamber S2 through the second opening PO2. In this way, the damping device 100 can attenuate the pressure pulsation of the hydraulic control unit 15.

[0084] Preferably, the damping device 100 is provided in the second piston 122 and includes a first through hole 122d that penetrates from the first opening PO1 side to the second opening PO2 side, a second valve body 152 that can open and close 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 projection member 161 that is positioned toward the second opening PO2 side relative to the second valve body 152, is insertable into the first through hole 122d, and has a projection 161a that can contact the second valve body 152. As a result, in the process of the pump 36 being driven and the second piston 122 moving toward the second opening PO2 side, the projection 161a of the projection member 161 can open the second valve body 152. Thus, brake fluid can be properly delivered from the second piston 122 toward the second opening PO2 side.

[0085] Preferably, the damping device 100 includes a hole 122c formed in the second piston 122 that is recessed from the second opening PO2 side toward the first opening PO1 side and communicates with the first through hole 122d, a third piston 123 slidably mounted in the hole 122c, and a fifth biasing member 145 that biases the third piston 123 toward the first opening PO1 side. As a result, when the pump 36 is driven, in addition to the movement of the first piston 121 and the second piston 122, the third piston 123 also moves. Then, as the fifth biasing member 145 expands and contracts in conjunction with the movement of the third piston 123, pressure pulsations can be further damped. Therefore, pressure pulsations can be damped more effectively.

[0086] Preferably, the damping device 100 includes a first cover 111 that covers the hole 122c from the second opening PO2 side, and the first cover 111 has at least one second through hole 111b that penetrates from the first opening PO1 side to the second opening PO2 side. As a result, pressure pulsation can also be dampened by the flow of brake fluid through the second through hole 111b.

[0087] Preferably, in the damping device 100, the first cover 111 has a plurality of second through holes 111b, and the plurality of second through holes 111b are arranged at equal intervals in the circumferential direction of the first cover 111. As a result, the flow field of brake fluid around the first cover 111 is made uniform in the circumferential direction. Therefore, the brake fluid can flow smoothly within the damping device 100.

[0088] Preferably, in the damping device 100, the projection member 161 has a base portion 161b connected to the projection 161a and covering the first opening PO1 side of the communication hole 114d, and a third through hole 161c is formed in the base portion 161b that penetrates from the first opening PO1 side to the second opening PO2 side. As a result, pressure pulsation can also be dampened by the flow of brake fluid through the third through hole 161c.

[0089] Preferably, in the damping device 100, the second piston 122 has at least one fourth through-hole 122e that penetrates from the first opening PO1 side to the second opening PO2 side. As a result, pressure pulsation can also be dampened by the flow of brake fluid through the fourth through-hole 122e. Here, a situation can be considered in which the second piston 122 becomes stuck and unable to move. In such a situation, brake fluid can flow from the first opening PO1 side to the second opening PO2 side of the second piston 122 through the fourth through-hole 122e. Therefore, it is suppressed that the pressure in the space of the first fluid chamber S1 on the first opening PO1 side of the second piston 122 becomes excessively high.

[0090] Preferably, in the damping device 100, the second piston 122 has a plurality of fourth through holes 122e, and the plurality of fourth through holes 122e are arranged at equal intervals in the circumferential direction of the second piston 122. As a result, the force generated due to the flow of brake fluid through the fourth through holes 122e acts uniformly on the second piston 122 in the circumferential direction. Therefore, the force acting on the second piston 122 due to the flow of brake fluid through the fourth through holes 122e suppresses tilting of the second piston 122 with respect to the sliding direction.

[0091] Preferably, the damping device 100 includes a second cover 112 that covers the second liquid chamber S2 from the second opening PO2 side, and the first valve body 151 is capable of contacting the second cover 112. As a result, when the first valve body 151 is in the open state, the first valve body 151 does not vibrate and its posture is stabilized. Therefore, the opening and closing operation of the first valve body 151 can be made smoother.

[0092] Preferably, in the damping device 100, the elastic modulus of the first biasing member 141 is lower than that of the second biasing member 142. This ensures that the first piston 121 moves before the second piston 122. Thus, it is possible to suppress situations in which the first piston 121 does not move and energy is not absorbed by the first biasing member 141.

[0093] Preferred embodiments of the present invention have been described above with reference to the attached drawings. However, it goes without saying that the present invention is not limited to the embodiments described above, and that various modifications or alterations within the scope of the claims also fall within the technical scope of the present invention.

[0094] The configuration of the damping device 100 was described above with reference to Figure 2. However, various modifications to the example in Figure 2 may also be included in the damping device according to the present invention.

[0095] For example, the sliding directions of the first piston 121 and the second piston 122 may differ from the axial direction of the housing 101. For example, if the central axis of the first liquid chamber S1 is not coaxial with the housing 101, the sliding directions of the first piston 121 and the second piston 122 will be different from the axial direction of the housing 101.

[0096] Furthermore, for example, the cross-sectional shape perpendicular to the sliding direction of the first liquid chamber S1, the first piston 121, and the second piston 122 does not have to be circular. The cross-sectional shape may be, for example, elliptical or polygonal. In that case as well, the circumferential direction of the first piston 121 and the second piston 122 is the direction along the outer periphery of the first piston 121 and the second piston 122, and is the direction around the central axis of the first piston 121 and the second piston 122.

[0097] Furthermore, for example, the cross-sectional shape perpendicular to the axial direction of the first cover 111 does not have to be circular. The cross-sectional shape may be, for example, elliptical or polygonal. In that case as well, the circumferential direction of the first cover 111 is the direction along the outer edge of the first cover 111, and is the direction around the central axis of the first cover 111.

[0098] Furthermore, for example, a damping device according to the present invention may also be included in the example in Figure 2 in which the second through-hole 111b is omitted. Even when the second through-hole 111b is omitted, a small gap exists between the inner circumferential surface of the first cover 111 and the projection 161a of the projection member 161, allowing brake fluid to flow through this gap from the left side to the right side of the first cover 111.

[0099] Furthermore, for example, a damping device according to the present invention may also be included in which the fourth through-hole 122e is omitted from the example in Figure 2. In the case where the fourth through-hole 122e is omitted, for example, a groove extending in the axial direction may be provided on the inner circumferential surface of the second hole 101b, and the brake fluid may be able to flow through the groove from the left side to the right side of the second piston 122.

[0100] Furthermore, for example, in the example shown in Figure 2, 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 come into contact with the second cover 112.

[0101] Furthermore, for example, the configuration of the second piston 122 may be changed compared to the example in Figure 2. For example, compared to the example in Figure 2, the third piston 123 may be omitted from the second piston 122. Also, for example, compared to the example in Figure 2, the first through hole 122d, the second valve body 152, the fourth biasing member 144, and the projection member 161 may be omitted. In this case, for example, a groove extending axially may be provided on the inner circumferential surface of the second hole 101b, and brake fluid may be able to flow through the groove from the left side to the right side of the second piston 122. Also, for example, the second piston 122 may be able to contact the first valve body 151, and the first valve body 151 may be opened by being pressed by the second piston 122. [Explanation of Symbols]

[0102] 1. Brake System 11 Brake pedal 12 Booster 13 Master Cylinder 14 Reservoir 15. Hydraulic control unit 16 Brake system 17 wheels 21 Main channel 22 Subchannel 23 Supply channel 31. Encapsulation valve 32. Loosening valve 33 First valve 34. Second valve 35 Accumulator 36 pumps 37 Motor 100 Damping device 101 Housing 111 First Cover 111b 2nd through hole 112 Second Cover 113 Third Cover 114. Cover 4 114d Communication hole 115. Cover of Chapter 5 121 First Piston 122 Second piston 122c Hole 122d 1st through hole 123 Third piston 131 First sealing member 132 Second sealing member 133 Third sealing member 141 First biasing member 142 Second biasing member 143 Third biasing member 144 Fourth biasing member 145 Fifth biasing member 151 First valve body 152 Second valve body 161 Protruding member 161a Protrusion 161b base 161c 3rd through hole P1 Entrance Port P2 Exit Port PO1 1st opening PO2 Second Opening S1 1st liquid chamber S2 2nd liquid chamber

Claims

1. A damping device (100) is provided in a hydraulic control unit (15) that controls the braking force generated in the wheel (17), and has an inlet port (P1) connected to the discharge side of a pump (36), and an outlet port (P2) communicating with the inlet port (P1), and damping device (100) that dampens pressure pulsations, A first liquid chamber (S1) is in communication with the inlet port (P1) via a first opening (PO1), A second liquid chamber (S2) is connected to the first liquid chamber (S1) via a communication hole (114d) and to the outlet port (P2) via a second opening (PO2), A first piston (121) is slidably provided in the first liquid chamber (S1) and is positioned in the first liquid chamber (S1) on the side opposite to the second opening (PO2) relative to the first opening (PO1), A first biasing member (141) biases the first piston (121) toward the first opening (PO1), A second piston (122) is slidably provided in the first liquid chamber (S1) and positioned on the side of the first opening (PO2) relative to the first opening (PO1) within the first liquid chamber (S1), A second biasing member (142) biases the second piston (122) toward the first opening (PO1), A first valve body (151) is provided in the second liquid chamber (S2) and is capable of opening and closing the second opening (PO2) side of the communication hole (114d), A third biasing member (143) biases the first valve body (151) toward the first opening (PO1), The second piston (122) has a first through hole (122d) that penetrates from the first opening (PO1) side to the second opening (PO2) side, A second valve body (152) that can open and close the first opening (PO1) side of the first through hole (122d), A fourth biasing member (144) biases the second valve body (152) toward the second opening (PO2), The present invention comprises a projection member (161) positioned on the second opening (PO2) side of the second valve body (152), which is insertable into the first through hole (122d) and has a projection (161a) that can contact the second valve body (152), The second piston (122) has a recessed portion (122c) formed from the second opening (PO2) side toward the first opening (PO1) side, which communicates with the first through hole (122d), A third piston (123) is slidably provided in the aforementioned hole (122c), A fifth biasing member (145) biases the third piston (123) toward the first opening (PO1), Equipped with, Damping device.

2. The hole (122c) is covered by a first cover (111) from the second opening (PO2) side, The first cover (111) has at least one second through hole (111b) that penetrates from the first opening (PO1) side to the second opening (PO2) side. The damping device according to claim 1.

3. The first cover (111) has a plurality of the second through holes (111b) formed therein. The plurality of second through holes (111b) are equally spaced in the circumferential direction of the first cover (111). to be placed The damping device according to claim 2.

4. The projection member (161) is connected to the projection (161a) and has a base (161b) that covers the first opening (PO1) side of the communication hole (114d), The base portion (161b) has a third through-hole (161c) that penetrates from the first opening (PO1) side to the second opening (PO2) side. The damping device according to claim 1.

5. The second piston (122) has at least one fourth through hole (122e) that penetrates from the first opening (PO1) side to the second opening (PO2) side. The damping device according to claim 1.

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

7. The second liquid chamber (S2) is provided with a second cover (112) that covers it from the second opening (PO2) side, The first valve body (151) is capable of contacting the second cover (112). The damping device according to claim 1.

8. The elastic modulus of the first biasing member (141) is lower than the elastic modulus of the second biasing member (142). The damping device according to claim 1.

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

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

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