Attenuation device, hydraulic control unit, and braking system

Abstract

The present invention dampens pressure pulsation in a liquid-pressure control unit. This damping device 100 is provided in a liquid-pressure control unit, has an inlet port P1 that is connected to a discharge side of a pump and an outlet port P2 that is connected to the inlet port P1, and dampens pressure pulsation. The damping device 100 comprises: a first fluid chamber S1 which is connected to the inlet port P1; a first piston 104 which is disposed within the first fluid chamber S1 so as to be slidable in a first sliding direction and which has formed therein a first through-hole 104b penetrating in the first sliding direction; a first valve body 106 which is capable of opening and closing the inlet port P1 side of the first through-hole 104b; a first biasing member 108 which biases the first valve body 106 toward the outlet port P2 side; a protruding member 109 having a protrusion 109b which is disposed on the outlet port P2 side with respect to the first valve body 106, extends in the first sliding direction, is insertable into the first through-hole 104b, and is able to come into abutment against the first valve body 106; and a second biasing member 110 which biases the first piston 104 toward the inlet port P1 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 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 1

Summary of the Invention

Problems to be Solved by the Invention

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

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

Means for Solving the Problem

[0006] To solve the above problems, a damping device is provided in a hydraulic control unit that controls the braking force generated on a wheel, and has an inlet port connected to the discharge side of a pump and an outlet port communicating with the inlet port, and is a damping device that attenuates pressure pulsations. The damping device includes a first liquid chamber communicating with the inlet port, a first piston slidably provided in the first liquid chamber in a first sliding direction and having a first through hole penetrating in the first sliding direction, a first valve body capable of opening and closing the inlet port side of the first through hole, a first biasing member that biases the first valve body toward the outlet port side, a protruding member disposed on the outlet port side with respect to the first valve body, extending in the first sliding direction, being insertable into the first through hole, and having a protruding portion capable of abutting against the first valve body, and a second biasing member that biases the first piston toward the inlet port side.

[0007] To solve the above problems, the hydraulic control unit includes the above damping device.

[0008] To solve the above problems, the brake system includes the above hydraulic control unit.

Advantages of the Invention

[0009] According to the present invention, it is possible to attenuate the pressure pulsations of the hydraulic control unit.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in such embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to omit redundant description, and elements not directly related to the present invention are not shown.

[0012] In the present embodiment, as an example of the vehicle, a vehicle having four wheels 17 will be described. However, 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 any one, two, or three wheels 17, or a vehicle having five or more wheels 17.

[0013] <Configuration of Brake System> With reference to FIGS. 1 and 2, the configuration of the brake system 1 according to an embodiment of the present invention will be described.

[0014] FIG. 1 is a schematic diagram showing a schematic 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 FIG. 1, the brake system 1 includes a brake pedal 11, a booster 12, a master cylinder 13, a reservoir 14, a hydraulic control unit 15, a brake device 16, and wheels 17.

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

[0016] Note that 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 braking system 1 can be mounted on a vehicle having two wheels 17.

[0017] The brake pedal 11 is used in a braking operation by the driver. In the braking operation, the brake pedal 11 is depressed by the driver. The booster 12 is connected to the brake pedal 11 and amplifies the depressing force of the brake pedal 11. The master cylinder 13 is connected to the booster 12 and incorporates a piston that reciprocates in conjunction with the brake pedal 11, generating a hydraulic pressure corresponding to the operation amount of the braking operation. The reservoir 14 is attached to the master cylinder 13 and stores the brake fluid.

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

[0019] In the base body 15a of the hydraulic control unit 15, a main flow path 21, a sub-flow path 22, and a supply flow path 23 are formed as flow paths for the brake fluid. The main flow path 21 circulates the brake fluid of the master cylinder 13 to the wheel cylinders of the brake device 16. The sub-flow path 22 discharges the brake fluid of the wheel cylinders 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] Further, in the base body 15a of the hydraulic control unit 15, a fill valve (EV) 31, a release valve (AV) 32, a first valve (USV) 33, a second valve (HSV) 34, an accumulator 35, a pump 36, and a motor 37 are provided as components for controlling the braking force generated in each wheel 17.

[0021] Note that the configuration of the hydraulic control unit according to the present invention may be different from the configuration of the hydraulic control unit 15 shown in FIG. 1 as long as it has a pump 36. For example, a configuration in which the supply flow path 23, the first valve 33, and the second valve 34 are omitted 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 cylinders 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 off 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 fill valve 31 is provided in the second main flow path 21b.

[0023] The sub-flow path 22 communicates with the side of the braking device 16 from the filling valve 31 in the main flow path 21, the side of the master cylinder 13 from the filling valve 31 in the main flow path 21, and the side of the braking device 16 from 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 braking device 16 from the filling valve 31 in the main flow path 21. The second sub-flow path 22b connects the confluence point of the two first sub-flow paths 22a, the side of the master cylinder 13 from the filling valve 31 in the main flow path 21, and the side of the braking device 16 from 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 order from the side of the first sub-flow path 22a.

[0024] The pump 36 is driven by a motor 37, sucks the brake fluid from the side of the first sub-flow path 22a, and discharges it to the side of the main flow path 21. The pump 36 is a reciprocating plunger pump. Specifically, the plunger of the pump 36 reciprocates by being intermittently pressed 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.

[0025] The supply flow path 23 communicates with the side of the master cylinder 13 from the first valve 33 in the main flow path 21 and 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.

[0026] 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 on each wheel 17 is controlled.

[0027] For example, during normal times when anti-lock brake control or skid prevention control, etc., which will be described later, is not being executed, the filling valve 31 is opened, the releasing valve 32 is closed, the first valve 33 is opened, and the second valve 34 is closed. As a result, 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 auxiliary flow path 22 and the supply flow path 23. In this state, when the brake pedal 11 is depressed, the piston of the master cylinder 13 is pushed in, increasing the hydraulic pressure of the brake fluid in the wheel cylinder, and a braking force is applied to the wheel 17.

[0028] The anti-lock brake control is a control for avoiding the locking of the wheel 17. For example, when the anti-lock brake control is executed, first, the filling valve 31 is closed, the releasing 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 brake device 16 stops, and the brake fluid can flow from the wheel cylinder to the auxiliary 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 that has flowed into the accumulator 35 is returned to the main flow path 21 through the auxiliary flow path 22 by driving the pump 36.

[0029] Then, when both the filling valve 31 and the releasing valve 32 are closed from the above state, the flow of the brake fluid between the main flow path 21 and the auxiliary 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. After that, when the filling valve 31 is opened and the releasing valve 32 is closed, the flow of the brake fluid between the main flow path 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] The anti-skid control is a control for stabilizing the behavior of the vehicle. In the anti-skid control, the driving force and the braking force of the vehicle are appropriately controlled. For example, during the execution of the anti-skid control, when braking the vehicle without a braking operation, the charging valve 31 is opened, the releasing valve 32 is closed, the first valve 33 is closed, and the second valve 34 is opened. Thereby, the brake fluid flows through the supply passage 23 and the sub-passage 22 from the master cylinder 13 to the wheel cylinder of the brake device 16. In this state, when the pump 36 is driven, the hydraulic pressure of the brake fluid in the wheel cylinder increases, and a braking force for braking the wheel 17 is generated.

[0031] As described above, in the hydraulic control unit 15, control is performed to drive the pump 36. When the pump 36 is driven, a pressure pulsation occurs, which is a phenomenon in which the hydraulic pressure of the brake fluid pulsates in the flow path in the hydraulic control unit 15. The sound generated by such pressure pulsation may be felt as noise by the vehicle occupants and may be a factor that impairs comfort. Therefore, the hydraulic control unit 15 is provided with a damping device 100 for attenuating the pressure pulsation.

[0032] The damping device 100 is provided on the downstream side of the pump 36 in the sub-passage 22 (specifically, the second sub-passage 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 through the inlet port P1, passes through the damping device 100, and then flows out of the damping device 100 through the outlet port P2.

[0033] Hereinafter, with reference to FIG. 2, the details of the configuration of the damping device 100 will be described. FIG. 2 is a cross-sectional view showing a schematic configuration of the damping device 100. However, the damping device 100 shown in FIG. 2 is merely an example of the damping device according to the present invention, and those obtained by making various modifications to the example of FIG. 2 as described later are also included in the damping device according to the present invention.

[0034] In FIG. 2 and FIGS. 3 to 5 described later, the attenuation device 100 is shown such that the inlet port P1 side is on the left side and the outlet port P2 side is on the right side. Hereinafter, the inlet port P1 side is also referred to as the left side, and the outlet port P2 side is also referred to as the right side. Further, hereinafter, the left-right direction, which is the axial direction of the housing 101, is also simply referred to as the axial direction.

[0035] As shown in FIG. 2, the attenuation device 100 includes a housing 101, a first cover 102, a second cover 103, a first piston 104, a first seal member 105, a first valve body 106, a case member 107, a first biasing member 108, a protrusion member 109, a second biasing member 110, a second piston 111, a second seal member 112, third biasing members 113, 114, a second valve body 115, and a fourth biasing member 116.

[0036] The housing 101 has, for example, 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 101a, a second hole 101b, a third hole 101c, a fourth hole 101d, and a fifth hole 101e. Each of the first hole 101a, the second hole 101b, the third hole 101c, the fourth hole 101d, and the fifth hole 101e has a cylindrical shape and is arranged coaxially with the central axis of the housing 101. The first hole 101a, the second hole 101b, the third hole 101c, the fourth hole 101d, and the fifth hole 101e are continuous in this order from the left side.

[0037] The space corresponding to the first hole portion 101a is the first liquid chamber S1. The diameter of the second hole portion 101b is smaller than the diameter of the first hole portion 101a. The diameter of the third hole portion 101c is smaller than the diameter of the second hole portion 101b. The space corresponding to the third hole portion 101c is the second liquid chamber S2. The second liquid chamber S2 communicates with the first liquid chamber S1 and is disposed on the right side with respect to the protruding member 109, as will be described later. The diameter of the fourth hole portion 101d is smaller than the diameter of the third hole portion 101c. The fourth hole portion 101d corresponds to an example of the fifth through hole according to the present invention. The diameter of the fifth hole portion 101e is larger than the diameter of the fourth hole portion 101d. The space corresponding to the fifth hole portion 101e is the third liquid chamber S3. The third liquid chamber S3 communicates with the second liquid chamber S2 through the fourth hole portion 101d which is the fifth through hole, is disposed on the outlet port P2 side with respect to the second liquid chamber S2, and communicates with the outlet port P2.

[0038] The first cover 102 is fitted to the left end portion of the first hole portion 101a. The first cover 102 covers the first liquid chamber S1 from the left side. The first cover 102 is formed in a cylindrical shape having an open right side and a bottom surface on the left side. An inlet port P1 is formed at the center of the bottom surface of the first cover 102. The inlet port P1 penetrates the first cover 102 from the left side to the right side. Therefore, the first liquid chamber S1 communicates with the inlet port P1. The inlet port P1 is disposed coaxially with the central axis of the housing 101. However, the inlet port P1 may not be disposed coaxially with the central axis of the housing 101.

[0039] The second cover 103 is fitted to the right end portion of the fifth hole portion 101e. The second cover 103 covers the third liquid chamber S3 from the right side. The second cover 103 has a substantially cylindrical shape. In the example of FIG. 2, the right end portion of the second cover 103 has a diameter expanded outward in the circumferential direction. The right end portion of the fifth hole portion 101e has a diameter expanded. The portion of the second cover 103 that has a diameter expanded outward in the circumferential direction is fitted to the portion of the fifth hole portion 101e that has a diameter expanded. An outlet port P2 is formed at the center of the second cover 103. The outlet port P2 penetrates the second cover 103 from the left side to the right side. Therefore, the third liquid chamber S3 communicates with the outlet port P2. The outlet port P2 is arranged coaxially with the central axis of the housing 101. However, the outlet port P2 may not be arranged coaxially with the central axis of the housing 101.

[0040] The first piston 104 is housed in the first hole portion 101a. The first piston 104 has a substantially cylindrical shape. The first piston 104 is arranged coaxially with the central axis of the first hole portion 101a. The outer peripheral surface of the first piston 104 is slidable with respect to the inner peripheral surface of the first hole portion 101a. Therefore, the first piston 104 is provided so as to be axially slidable in the first liquid chamber S1. Thus, in the example of FIG. 2, the first sliding direction, which is the sliding direction of the first piston 104, is the axial direction of the housing 101. However, as will be described later, the first sliding direction may be different from the axial direction of the housing 101.

[0041] An annular groove 104a is formed on the outer peripheral surface of the first piston 104. The annular groove 104a extends in the circumferential direction of the first piston 104. A first seal member 105 is fitted in the annular groove 104a. The first seal member 105 is, for example, an O-ring. The first seal member 105 is pressed against the inner peripheral surface of the first hole portion 101a. Thereby, the gap between the outer peripheral surface of the first piston 104 and the inner peripheral surface of the first hole portion 101a is sealed liquid-tightly.

[0042] A first through-hole 104b is formed in the first piston 104. The first through-hole 104b penetrates the first piston 104 in the axial direction which is the first sliding direction. Therefore, the first through-hole 104b penetrates from the left end face to the right end face of the first piston 104. In the example of FIG. 2, a groove portion 104c is formed in the left end face of the first piston 104, and a groove portion 104d is formed in the right end face of the first piston 104. The groove portion 104c and the groove portion 104d are formed annularly along the periphery of the first through-hole 104b. And the first through-hole 104b penetrates from the bottom face of the groove portion 104c to the bottom face of the groove portion 104d. However, the shapes of the left end face and the right end face of the first piston 104 are not limited to the example of FIG. 2. For example, the groove portions 104c and 104d may not be formed. Also, in the example of FIG. 2, the first through-hole 104b is arranged coaxially with the central axis of the first piston 104. However, the first through-hole 104b may not be arranged coaxially with the central axis of the first piston 104.

[0043] The first valve body 106 can open and close the left side of the first through-hole 104b. When the first valve body 106 is in an open state where it does not block the first through-hole 104b, brake fluid can flow through the first through-hole 104b. This state corresponds to the open state of the first valve body 106 and the open state of the first through-hole 104b. When the first valve body 106 is in a closed state where it blocks the first through-hole 104b, brake fluid cannot flow through the first through-hole 104b. This state corresponds to the closed state of the first valve body 106 and the closed state of the first through-hole 104b.

[0044] The case member 107 is attached to the left end face of the first piston 104. In the example of FIG. 2, the case member 107 is attached to the groove portion 104c on the left end face of the first piston 104 and covers the groove portion 104c from the left side. The case member 107 is formed in a cylindrical shape with an open right side and a bottom surface on the left side. A through hole 107a is formed at the center of the bottom surface of the case member 107. The through hole 107a penetrates the case member 107 from the left side to the right side. Therefore, the space on the left side and the space on the right side of the case member 107 communicate with each other through the through hole 107a. The through hole 107a is arranged coaxially with the central axis of the housing 101. However, the through hole 107a may not be arranged coaxially with the central axis of the housing 101.

[0045] The first valve body 106 is arranged in the space partitioned by the case member 107 and the left end face of the first piston 104. The first valve body 106 has, for example, a spherical shape. However, the shape of the first valve body 106 may be a shape other than a spherical shape. The first biasing member 108 is an elastic member such as a spring, for example. The first biasing member 108 is arranged between the case member 107 and the first valve body 106. The expansion and contraction direction of the first biasing member 108 is the left-right direction. The first biasing member 108 is in a state of being contracted with respect to its natural length. Therefore, the first valve body 106 is biased to the right by the first biasing member 108.

[0046] In the example of FIG. 2, a tapered portion 104e is formed on the left side of the first through hole 104b. The tapered portion 104e is a portion whose diameter increases as it advances to the left. The first valve body 106 can abut against the tapered portion 104e of the first through hole 104b. When the first valve body 106 abuts against the tapered portion 104e, the first through hole 104b is closed. In this case, compared with the case where the tapered portion 104e is not formed, the first valve body 106 and the first through hole 104b come into stable contact, so that the first through hole 104b can be properly closed. However, the tapered portion 104e may not be formed in the first through hole 104b.

[0047] A plurality of second through holes 104f are formed in the first piston 104. The second through holes 104f penetrate the first piston 104 from the left side to the right side and have an inner diameter smaller than that of the first through hole 104b. The inner diameter of the second through hole 104f is, for example, about 0.4 mm to 0.5 mm in diameter. In the example of FIG. 2, the second through holes 104f extend in the axial direction. However, the path of the second through holes 104f is not particularly limited. For example, the second through holes 104f may extend in a direction inclined with respect to the axial direction, or may be curved or bent.

[0048] The plurality of second through holes 104f are arranged at equal intervals in the circumferential direction of the first piston 104. However, the arrangement of the plurality of second through holes 104f is not limited to this example. For example, like the third through hole 109d described later, the plurality of second through holes 104f may be arranged separately in the circumferential direction at different radial positions. Also, the number of the second through holes 104f may be one. The brake fluid can flow from the left side to the right side of the first piston 104 through the second through holes 104f. The second through holes 104f are provided to reduce pressure pulsation. The function of the second through holes 104f will be described later.

[0049] The projection member 109 is provided to open and close the first valve body 106. The projection member 109 is arranged on the right side of the first piston 104. The projection member 109 has a base portion 109a and a projection portion 109b. The base portion 109a has a substantially disc shape. The base portion 109a is fitted into the second hole portion 101b. The projection portion 109b is connected to the base portion 109a. The projection portion 109b projects leftward from the center of the base portion 109a. The projection portion 109b extends in the axial direction, which is the first sliding direction.

[0050] The protrusion 109b is disposed on the right side with respect to the first valve body 106. The protrusion 109b is coaxially arranged with the central axis of the first through-hole 104b. When the first piston 104 moves to the right from the position shown in FIG. 2, the protrusion 109b is inserted into the first through-hole 104b, and the tip of the protrusion 109b can contact the first valve body 106. By the tip of the protrusion 109b contacting the first valve body 106, the position of the first valve body 106 is maintained. In that state, when the first piston 104 further moves to the right, the first valve body 106 becomes open. Thus, the protrusion 109b can be inserted into the first through-hole 104b and can contact the first valve body 106.

[0051] In the example of FIG. 2, a recessed portion 109c is formed at the tip of the protrusion 109b. The recessed portion 109c has a spherical shape with a curvature substantially matching the curvature of the first valve body 106. The recessed portion 109c of the protrusion 109b contacts the first valve body 106. In this case, compared with the case where the recessed portion 109c is not formed, the contact area between the first valve body 106 and the protrusion 109b becomes larger, so that the first valve body 106 can be appropriately maintained in the open state. However, the recessed portion 109c may not be formed on the protrusion 109b.

[0052] A plurality of third through-holes 109d are formed in the base portion 109a. The third through-holes 109d penetrate the base portion 109a from the left side to the right side and have an inner diameter smaller than the inner diameter of the first through-hole 104b. The inner diameter of the third through-hole 109d is, for example, about 0.4 mm to 0.5 mm in diameter. In the example of FIG. 2, the third through-holes 109d extend in the axial direction. However, the path of the third through-holes 109d is not particularly limited. For example, the third through-holes 109d may extend in a direction inclined with respect to the axial direction, or may be curved or bent.

[0053] The plurality of third through holes 109d are arranged at equal intervals in the circumferential direction of the base portion 109a. In the example of FIG. 2, the plurality of third through holes 109d are arranged separately in the circumferential direction at different radial positions. However, the arrangement of the plurality of third through holes 109d is not limited to this example. Also, the number of the third through holes 109d may be one. The brake fluid can flow from the left side to the right side of the protruding member 109 through the third through hole 109d. The third through hole 109d is provided to reduce pressure pulsation. The function of the third through hole 109d will be described later.

[0054] The second biasing member 110 is an elastic member such as a spring, for example. The second biasing member 110 is arranged between the first piston 104 and the protruding member 109. The expansion and contraction direction of the second biasing member 110 is the left - right direction. The second biasing member 110 is in a state of being contracted with respect to its natural length. In the example of FIG. 2, the left end of the second biasing member 110 is in contact with the bottom surface of the groove portion 104d of the first piston 104. The right end of the second biasing member 110 is in contact with the left end surface of the base portion 109a of the protruding member 109. Therefore, the first piston 104 is biased to the left by the second biasing member 110.

[0055] The second piston 111 is accommodated in the third hole portion 101c. The second piston 111 has a substantially cylindrical shape. The second piston 111 is arranged coaxially with the central axis of the third hole portion 101c. The outer peripheral surface of the second piston 111 is slidable with respect to the inner peripheral surface of the third hole portion 101c. Therefore, the second piston 111 is provided to be axially slidable in the second liquid chamber S2. Thus, in the example of FIG. 2, the second sliding direction, which is the sliding direction of the second piston 111, is the axial direction of the housing 101. However, as will be described later, the second sliding direction may be different from the axial direction of the housing 101.

[0056] An annular groove 111a is formed on the outer peripheral surface of the second piston 111. The annular groove 111a extends in the circumferential direction of the second piston 111. A second seal member 112 is fitted in the annular groove 111a. The second seal member 112 is, for example, an O-ring. The second seal member 112 is pressed against the inner peripheral surface of the third hole portion 101c. Thereby, the gap between the outer peripheral surface of the second piston 111 and the inner peripheral surface of the third hole portion 101c is sealed in a liquid-tight manner.

[0057] The third biasing member 113 is, for example, an elastic member such as a spring. The third biasing member 114 is, for example, an elastic member such as a rubber ring. The third biasing member 113 and the third biasing member 114 are disposed in the space on the right side of the second piston 111 in the second liquid chamber S2. The expansion and contraction directions of the third biasing member 113 and the third biasing member 114 are in the left-right direction. The third biasing member 113 and the third biasing member 114 are in a state of being contracted with respect to their natural lengths.

[0058] In the example of FIG. 2, an annular protrusion 111b is formed on the right end surface of the second piston 111. The annular protrusion 111b is disposed coaxially with the central axis of the second piston 111 and protrudes to the right from the right end surface of the second piston 111. The left end of the third biasing member 113 abuts against the radially inner side of the right end surface of the second piston 111 with respect to the annular protrusion 111b. The third biasing member 114 is disposed so as to cover the outer peripheral portion of the third biasing member 113. The left end of the third biasing member 114 abuts against the radially outer side of the right end surface of the second piston 111 with respect to the annular protrusion 111b. The right ends of the third biasing member 113 and the third biasing member 114 abut against the step portion between the third hole portion 101c and the fourth hole portion 101d. Therefore, the second piston 111 is biased to the left by the third biasing member 113 and the third biasing member 114.

[0059] A plurality of fourth through holes 111c are formed in the second piston 111. The fourth through holes 111c penetrate the second piston 111 from the left side to the right side and have an inner diameter smaller than the inner diameter of the first through hole 104b. The inner diameter of the fourth through holes 111c is, for example, about 0.4 mm to 0.5 mm in diameter. In the example of FIG. 2, the fourth through holes 111c extend in the axial direction. However, the path of the fourth through holes 111c is not particularly limited. For example, the fourth through holes 111c may extend in a direction inclined with respect to the axial direction, or may be curved or bent.

[0060] The plurality of fourth through holes 111c are arranged at equal intervals in the circumferential direction of the second piston 111. However, the arrangement of the plurality of fourth through holes 111c is not limited to this example. For example, like the third through hole 109d described above, the plurality of fourth through holes 111c may be arranged separately in the circumferential direction at different radial positions. Also, the number of the fourth through holes 111c may be one. The brake fluid can flow from the left side to the right side of the second piston 111 through the fourth through holes 111c. The fourth through holes 111c are provided to reduce pressure pulsation. The function of the fourth through holes 111c will be described later.

[0061] The second valve body 115 can open and close the right side of the fourth hole portion 101d which is the fifth through hole. In the open state where the second valve body 115 does not block the fourth hole portion 101d, the brake fluid can flow through the fourth hole portion 101d. This state corresponds to the open state of the second valve body 115 and the open state of the fourth hole portion 101d. In the closed state where the second valve body 115 blocks the fourth hole portion 101d, the brake fluid cannot flow through the fourth hole portion 101d. This state corresponds to the closed state of the second valve body 115 and the closed state of the fourth hole portion 101d.

[0062] The second valve body 115 is disposed in the space on the left side of the second cover 103 in the third liquid chamber S3. The second valve body 115 has, for example, a spherical shape. However, the shape of the second valve body 115 may be a shape other than the spherical shape. The fourth biasing member 116 is, for example, an elastic member such as a spring. The fourth biasing member 116 is disposed between the second cover 103 and the second valve body 115. The expansion and contraction direction of the fourth biasing member 116 is the left-right direction. The fourth biasing member 116 is in a state of being contracted with respect to its natural length. Therefore, the second valve body 115 is biased to the left by the fourth biasing member 116.

[0063] In the example of FIG. 2, a tapered portion 101f is formed on the right side of the fourth hole portion 101d. The tapered portion 101f is a portion whose diameter increases as it advances to the right. The second valve body 115 can abut against the tapered portion 101f of the fourth hole portion 101d. When the second valve body 115 abuts against the tapered portion 101f, the fourth hole portion 101d is closed. In this case, compared with the case where the tapered portion 101f is not formed, the second valve body 115 and the fourth hole portion 101d come into stable contact, so that the fourth hole portion 101d can be properly closed. However, the tapered portion 101f may not be formed in the fourth hole portion 101d.

[0064] <Operation of the damping device> With reference to FIGS. 2 to 5, the operation of the damping device 100 according to the embodiment of the present invention will be described.

[0065] In FIG. 2 described above, the damping device 100 in a normal state where the pump 36 is not driven in the hydraulic control unit 15 is shown. In this case, the first piston 104 is biased to the left by the second biasing member 110 and is located at the leftmost position in the movable range. Therefore, the first valve body 106 does not abut against the protrusion 109b of the protrusion member 109 and is in a closed state. The second piston 111 is biased to the left by the third biasing members 113 and 114 and is located at the leftmost position in the movable range. The second valve body 115 is biased to the left by the fourth biasing member 116 and is in a closed state.

[0066] Here, in the hydraulic control unit 15, as described above, when anti-lock brake control or skid prevention control or the like is executed, the pump 36 is driven. In the state of FIG. 2, when the pump 36 is driven, the brake fluid flows into the damper device 100 through the inlet port P1, and the pressure in the space on the left side of the first piston 104 in the first liquid chamber S1 increases. Thereby, the first piston 104 moves to the right side.

[0067] FIG. 3 is a view showing a state in which the first piston 104 has moved to the right side in the damper device 100 as compared with the state of FIG. 2. In the state of FIG. 3, since the first through hole 104b is in a closed state, pressure is stored in the space on the left side of the first piston 104 in the first liquid chamber S1. Then, the first piston 104 is pressed to the right side by the pressure in the space on the left side of the first piston 104 in the first liquid chamber S1, and the first piston 104 has moved to the right side as compared with the state of FIG. 2. When the first piston 104 moves to the right side, the second biasing member 110 contracts as it expands and contracts. Thereby, the force acting on the first piston 104 is absorbed by the second biasing member 110. In this way, as the second biasing member 110 expands and contracts with the movement of the first piston 104, the pressure pulsation is attenuated.

[0068] Here, in the state of FIG. 3, the brake fluid in the space on the left side of the first piston 104 in the first liquid chamber S1 is sent through the second through hole 104f to the space on the right side of the first piston 104 in the first liquid chamber S1. Here, the inner diameter of the second through hole 104f is smaller than the inner diameter of the first through hole 104b, and a large resistance is applied to the brake fluid flowing through the second through hole 104f. Therefore, the pressure pulsation is also attenuated by the brake fluid flowing through the second through hole 104f.

[0069] Also, the brake fluid in the space between the first piston 104 and the protrusion member 109 is sent through the third through hole 109d to the second liquid chamber S2. A large resistance is also applied to the brake fluid flowing through the third through hole 109d, similar to the second through hole 104f. Therefore, the pressure pulsation is also attenuated by the brake fluid flowing through the third through hole 109d.

[0070] Also, the brake fluid in the space on the left side of the second piston 111 in the second liquid chamber S2 is sent through the fourth through-hole 111c to the space on the right side of the second piston 111 in the second liquid chamber S2. A large resistance is also applied to the brake fluid flowing through the fourth through-hole 111c, similar to the second through-hole 104f and the third through-hole 109d. Therefore, the pressure pulsation is also attenuated when the brake fluid flows through the fourth through-hole 111c.

[0071] In the state of FIG. 3, the second valve body 115 is basically biased to the left by the fourth biasing member 116 and is in a closed state. However, when the brake fluid is sent to the right side of the second piston 111 through the fourth through-hole 111c and the pressure in the fourth hole portion 101d increases, the second valve body 115 may move to the right and be temporarily opened. In that case, the brake fluid passes through the fourth hole portion 101d and flows out from the third liquid chamber S3 through the outlet port P2.

[0072] FIG. 4 is a diagram showing a state in which the first piston 104 has moved to the right in the damping device 100 compared to the state of FIG. 3. In the state of FIG. 4, the first piston 104 has moved to the right compared to the state of FIG. 3. Further, in the state of FIG. 4, the second piston 111 is pressed to the right by the pressure in the space on the left side of the second piston 111 in the second liquid chamber S2, and the second piston 111 has moved to the right compared to the state of FIG. 3. When the second piston 111 moves to the right, the third biasing member 113 and the third biasing member 114 expand and contract and consequently contract. Thereby, the force acting on the second piston 111 is absorbed by the third biasing member 113 and the third biasing member 114. In this way, as the second piston 111 moves, the third biasing member 113 and the third biasing member 114 expand and contract, thereby attenuating the pressure pulsation.

[0073] Note that in the state of FIG. 4, similar to the state of FIG. 3, although the second valve body 115 is basically in a closed state, it may also be temporarily opened.

[0074] FIG. 5 is a diagram showing a state in which the first piston 104 has moved to the right in the damping device 100 as compared with the state of FIG. 4. In the state of FIG. 5, the first piston 104 and the second piston 111 have moved to the right as compared with the state of FIG. 4. Here, in the state of FIG. 5, the recessed portion 109c at the tip of the protrusion 109b is in contact with the first valve body 106. Thereby, the movement of the first valve body 106 to the right is restricted by the protrusion 109b. For this reason, even if the first piston 104 moves to the right, the first valve body 106 in contact with the protrusion 109b does not move to the right. Therefore, the position of the first valve body 106 is maintained at the position where it contacts the protrusion 109b, and the first valve body 106 has moved relatively to the left with respect to the first piston 104 as compared with the state of FIG. 4. As a result, the first valve body 106 is separated from the tapered portion 104e of the first through hole 104b. Therefore, the first through hole 104b is in an open state, and the brake fluid can flow through the first through hole 104b.

[0075] Therefore, in the state of FIG. 5, the brake fluid in the space on the left side of the first piston 104 in the first liquid chamber S1 is sent through the first through hole 104b to the space on the right side of the first piston 104 in the first liquid chamber S1. Thereby, the pressure on the right side of the first piston 104 in the damping device 100 increases to the same level as the pressure on the left side of the first piston 104 in the damping device 100. Therefore, when the pressure in the fourth hole portion 101d increases, the second valve body 115 is pushed to the right and moves. Thereby, the second valve body 115 is separated from the tapered portion 101f of the fourth hole portion 101d. Therefore, the fourth hole portion 101d is in an open state, and the brake fluid can flow through the fourth hole portion 101d. Therefore, the brake fluid passes through the fourth hole portion 101d and flows out from the third liquid chamber S3 through the outlet port P2.

[0076] <Effect of the damping device> The effect of the damping device 100 according to the embodiment of the present invention will be described.

[0077] In the damping device 100, a first liquid chamber S1 communicating with the inlet port P1, a first piston 104 slidably provided in the first liquid chamber S1 in a first sliding direction (in the above example, the axial direction of the housing 101), and having a first through hole 104b penetrating in the first sliding direction, a first valve body 106 capable of opening and closing the inlet port P1 side of the first through hole 104b, a first biasing member 108 biasing the first valve body 106 toward the outlet port P2 side, a projection member 109 disposed on the outlet port P2 side with respect to the first valve body 106, extending in the first sliding direction, being insertable into the first through hole 104b, and having a projection 109b capable of abutting against the first valve body 106, and a second biasing member 110 biasing the first piston 104 toward the inlet port P1 side are provided.

[0078] Thereby, when the pump 36 is driven and the pressure on the input port P1 side rises, the projection 109b of the projection member 109 abuts against the first valve body 106, and until the first valve body 106 becomes open, pressure is stored in the space on the inlet port P1 side of the first piston 104 in the first liquid chamber S1. And during this time, as the first piston 104 moves toward the outlet port P2 side, the second biasing member 110 gradually contracts, whereby the energy of the pressure rise is absorbed and the pressure rise rate on the outlet port P2 side of the first piston 104 becomes slower than the pressure rise rate on the inlet port P1 side of the first piston 104. When the pressure on the inlet port P1 side decreases and the first piston 104 moves toward the inlet port P1 side, the second biasing member 110 gradually extends, whereby the pressure decrease rate on the outlet port P2 side of the first piston 104 becomes slower than the pressure decrease rate on the inlet port P1 side of the first piston 104. Thereby, the pressure pulsation on the outlet port P2 side can be attenuated with respect to the pressure pulsation on the inlet port P1 side. Thus, according to the damping device 100, the pressure pulsation of the hydraulic control unit 15 can be attenuated.

[0079] Preferably, in the damping device 100, the first piston 104 is formed with a second through hole 104f that penetrates from the inlet port P1 side to the outlet port P2 side and has an inner diameter smaller than the inner diameter of the first through hole 104b. Thereby, even when the brake fluid flows through the second through hole 104f, the pressure pulsation can be attenuated. Here, a situation where the first piston 104 is fixed and cannot move is conceivable. In such a situation, the brake fluid can flow from the inlet port P1 side of the first piston 104 to the outlet port P2 side through the second through hole 104f. Therefore, an excessive increase in the pressure of the space on the inlet port P1 side of the first piston 104 in the first fluid chamber S1 is suppressed.

[0080] Preferably, in the damping device 100, the first piston 104 is formed with a plurality of second through holes 104f, and the plurality of second through holes 104f are arranged at equal intervals in the circumferential direction of the first piston 104. Thereby, the force generated due to the brake fluid flowing through the second through hole 104f acts evenly on the first piston 104 in the circumferential direction. Therefore, the force acting on the first piston 104 due to the brake fluid flowing through the second through hole 104f suppresses the inclination of the first piston 104 with respect to the first sliding direction.

[0081] Preferably, in the damping device 100, the protruding member 109 has a base portion 109a connected to the protruding portion 109b, and the base portion 109a is formed with a third through hole 109d that penetrates from the inlet port P1 side to the outlet port P2 side and has an inner diameter smaller than the inner diameter of the first through hole 104b. Thereby, even when the brake fluid flows through the third through hole 109d, the pressure pulsation can be attenuated.

[0082] Preferably, in the damping device 100, the base portion 109a is formed with a plurality of third through holes 109d, and the plurality of third through holes 109d are arranged at equal intervals in the circumferential direction of the base portion 109a. Thereby, the flow field of the brake fluid is made uniform in the circumferential direction around the protruding member 109. Therefore, the brake fluid can flow smoothly in the damping device 100.

[0083] Preferably, in the damping device 100, a second liquid chamber S2 that communicates with the first liquid chamber S1 and is disposed on the outlet port P2 side with respect to the protruding member 109, a second piston 111 that is slidably provided in the second liquid chamber S2 in the second sliding direction (in the above example, the axial direction of the housing 101), and third biasing members 113 and 114 that bias the second piston 111 toward the inlet port P1 side are provided. Thereby, even when the third biasing members 113 and 114 expand and contract as the second piston 111 moves, pressure pulsation can be attenuated in the same manner as when the second biasing member 110 expands and contracts as the first piston 104 moves. Note that one of the third biasing members 113 and 114 may be omitted, and even in this case, the same effect as described above can be achieved.

[0084] Preferably, in the damping device 100, a fourth through hole 111c that penetrates the second piston 111 from the inlet port P1 side to the outlet port P2 side and has an inner diameter smaller than the inner diameter of the first through hole 104b is formed in the second piston 111. Thereby, pressure pulsation can also be attenuated by the brake fluid flowing through the fourth through hole 111c.

[0085] Preferably, in the damping device 100, a plurality of fourth through holes 111c are formed in the second piston 111, and the plurality of fourth through holes 111c are arranged at equal intervals in the circumferential direction of the second piston 111. Thereby, the force generated due to the brake fluid flowing through the fourth through holes 111c acts evenly on the second piston 111 in the circumferential direction. Therefore, the force acting on the second piston 111 due to the brake fluid flowing through the fourth through holes 111c suppresses the second piston 111 from tilting with respect to the second sliding direction.

[0086] Preferably, in the damping device 100, a second liquid chamber S2 that communicates with the first liquid chamber S1 and is disposed on the outlet port P2 side with respect to the protruding member 109, and a fifth through-hole (the fourth hole portion 101d in the above example) communicate with the second liquid chamber S2, and is disposed on the outlet port P2 side with respect to the second liquid chamber S2, and a third liquid chamber S3 that communicates with the outlet port P2, a second valve body 115 that can open and close the outlet port P2 side of the fifth through-hole, and a fourth biasing member 116 that biases the second valve body 115 toward the inlet port P1 side are provided. Thereby, when the first through-hole 104b is in an open state and the brake fluid can flow through the first through-hole 104b, the fifth through-hole is in an open state, and the brake fluid can be appropriately discharged from the third liquid chamber S3 through the outlet port P2.

[0087] As described above, the preferred embodiments of the present invention have been described with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications or corrections within the scope described in the claims also belong to the technical scope of the present invention.

[0088] In the above, the configuration of the damping device 100 has been described with reference to FIG. 2. However, those obtained by making various modifications to the example of FIG. 2 may also be included in the damping device according to the present invention.

[0089] For example, the first sliding direction, which is the sliding direction of the first piston 104, may be different from the axial direction of the housing 101. When the central axis of the first liquid chamber S1 is not disposed coaxially with the housing 101, the first sliding direction is the axial direction of the first liquid chamber S1, which is different from the axial direction of the housing 101.

[0090] Further, for example, the cross-sectional shape perpendicular to the first sliding direction of the first liquid chamber S1 and the first piston 104 may not be circular. The cross-sectional shape may be, for example, an elliptical shape or a polygonal shape. Even in that case, the circumferential direction of the first piston 104 is a direction along the outer peripheral edge of the first piston 104 and is a direction around the central axis of the first piston 104.

[0091] Further, for example, the cross-sectional shape of the base portion 109a of the protruding member 109 that is orthogonal to the axial direction does not have to be circular. The cross-sectional shape may be, for example, an elliptical shape or a polygonal shape, etc. Even in that case, the circumferential direction of the base portion 109a is the direction along the outer peripheral edge of the base portion 109a and is the direction around the central axis of the base portion 109a.

[0092] Further, for example, the second sliding direction, which is the sliding direction of the second piston 111, may be different from the axial direction of the housing 101. When the central axis of the second liquid chamber S2 is not arranged coaxially with the housing 101, the second sliding direction is the axial direction of the second liquid chamber S2, which is different from the axial direction of the housing 101. Also, the second sliding direction does not have to coincide with the first sliding direction. When the central axis of the second liquid chamber S2 is not arranged coaxially with the first liquid chamber S1, the second sliding direction is the axial direction of the second liquid chamber S2, which is different from the first sliding direction.

[0093] Further, for example, the cross-sectional shape of the second liquid chamber S2 and the second piston 111 that is orthogonal to the second sliding direction does not have to be circular. The cross-sectional shape may be, for example, an elliptical shape or a polygonal shape, etc. Even in that case, the circumferential direction of the second piston 111 is the direction along the outer peripheral edge of the second piston 111 and is the direction around the central axis of the second piston 111.

[0094] Further, for example, with respect to the example of FIG. 2, an attenuation device according to the present invention may also include one in which the second piston 111, the second seal member 112, and the third biasing members 113 and 114 are omitted. In this case, the second liquid chamber S2 may also be omitted.

[0095] Also, for example, in the example of FIG. 2, a damping device according to the present invention may include one in which at least one of the second through hole 104f, the third through hole 109d, and the fourth through hole 111c is omitted. However, when the third through hole 109d is omitted, it is necessary to allow the brake fluid to flow from the inlet port P1 side to the outlet port P2 side beyond the protruding member 109. Also, when the fourth through hole 111c is omitted, it is necessary to allow the brake fluid to flow from the inlet port P1 side to the outlet port P2 side beyond the second piston 111.

Explanation of Signs

[0096] 1 Brake system 11 Brake pedal 12 Multiplier device 13 Master cylinder 14 Reservoir 15 Hydraulic control unit 16 Brake device 17 Wheel 21 Main flow path 22 Sub-flow path 23 Supply flow path 31 Filling valve 32 Bleeding valve 33 First valve 34 Second valve 35 Accumulator 36 Pump 37 Motor 100 Damping device 101 Housing 101a First hole portion 101b Second hole portion 101c Third hole portion 101d Fourth hole portion (fifth through hole) 101e Fifth hole portion 102 First cover 103 Second cover 104 First piston 104b First through hole 104f Second through hole 105 First seal member 106 First valve body 107 Case member 108 First biasing member 109 Protrusion member 109a Base portion 109b Protrusion 109d Third through-hole 110 Second biasing member 111 Second piston 111c Fourth through-hole 112 Second seal member 113 Third biasing member 114 Third biasing member 115 Second valve body 116 Fourth biasing member P1 Inlet port P2 Outlet port S1 First liquid chamber S2 Second liquid chamber S3 Third liquid chamber

Claims

1. A damping device provided in a hydraulic control unit (15) for controlling the braking force generated in a wheel (17), having an inlet port (P1) connected to the discharge side of a pump (36) and an outlet port (P2) communicating with the inlet port (P1), the damping device (100) for attenuating pressure pulsations, a first liquid chamber (S1) communicating with the inlet port (P1), a first piston (104) slidably provided in the first liquid chamber (S1) in a first sliding direction, and having a first through hole (104b) penetrating in the first sliding direction, a first valve body (106) capable of opening and closing the inlet port (P1) side of the first through hole (104b), a first biasing member (108) biasing the first valve body (106) toward the outlet port (P2) side, a protrusion member (109) disposed on the outlet port (P2) side with respect to the first valve body (106), extending in the first sliding direction, being insertable into the first through hole (104b), and having a protrusion (109b) capable of abutting against the first valve body (106), a second biasing member (110) biasing the first piston (104) toward the inlet port (P1) side, comprising a damping device.

2. The damping device according to claim 1, wherein a second through hole (104f) penetrating from the inlet port (P1) side to the outlet port (P2) side and having an inner diameter smaller than the inner diameter of the first through hole (104b) is formed in the first piston (104). The damping device according to claim 1.

3. The damping device according to claim 2, wherein a plurality of the second through holes (104f) are formed in the first piston (104), and the plurality of second through holes (104f) are arranged at equal intervals in the circumferential direction of the first piston (104). The damping device according to claim 2.

4. The damping device according to any one of claims 1 to 3, wherein the protrusion member (109) has a base portion (109a) connected to the protrusion (109b), and a third through hole (109d) penetrating from the inlet port (P1) side to the outlet port (P2) side and having an inner diameter smaller than the inner diameter of the first through hole (104b) is formed in the base portion (109a). The damping device according to any one of claims 1 to 3.

5. The damping device according to claim 4, wherein a plurality of the third through holes (109d) are formed in the base portion (109a), and the plurality of third through holes (109d) are arranged at equal intervals in the circumferential direction of the base portion (109a). The damping device according to claim 4.

6. A second liquid chamber (S2) that communicates with the first liquid chamber (S1) and is disposed on the outlet port (P2) side with respect to the protruding member (109), A second piston (111) that is slidably provided in the second liquid chamber (S2) in a second sliding direction, A third biasing member (113, 114) that biases the second piston (111) toward the inlet port (P1), Comprising, The damping device according to claim 1.

7. A fourth through hole (111c) is formed in the second piston (111) so as to penetrate from the inlet port (P1) side to the outlet port (P2) side and have an inner diameter smaller than the inner diameter of the first through hole (104b). The damping device according to claim 6.

8. A plurality of the fourth through holes (111c) are formed in the second piston (111), The plurality of fourth through holes (111c) are arranged at equal intervals in the circumferential direction of the second piston (111). The damping device according to claim 7.

9. A second liquid chamber (S2) that communicates with the first liquid chamber (S1) and is disposed on the outlet port (P2) side with respect to the protruding member (109), A third liquid chamber (S3) that communicates with the second liquid chamber (S2) via a fifth through hole (101d), is disposed on the outlet port (P2) side with respect to the second liquid chamber (S2), and communicates with the outlet port (P2), A second valve body (115) that can open and close the outlet port (P2) side of the fifth through hole (101d), A fourth biasing member (116) that biases the second valve body (115) toward the inlet port (P1), Comprising, The damping device according to claim 1.

10. A hydraulic control unit including the damping device (100) according to claim 1.

11. A brake system including the hydraulic control unit (15) according to claim 10.

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