Damping device, hydraulic control unit, and brake system

Abstract

The purpose of the present invention is to attenuate pressure pulsation of a hydraulic control unit. The damping device is provided in a hydraulic pressure control unit for controlling a braking force generated at a wheel, has an inlet port connected to a discharge side of a pump and an outlet port communicating with the inlet port, and attenuates a pressure pulsation, and is provided with: a first liquid chamber communicating with the inlet port via a first opening; a second liquid chamber communicating with the first liquid chamber via a communication hole and communicating with the outlet port via a second opening; a first piston slidably provided in the first liquid chamber; a first biasing member that biases the first piston toward the first opening side; a valve body provided in the second liquid chamber and capable of opening and closing a second opening side of the communication hole; a second biasing member that biases the valve body toward the first opening side; and a protruding part which is provided on the second opening side of the first piston, can be inserted into the communication hole, and can abut against the valve body.

Description

Technical Field

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

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

[0003] Prior Art Documents

[0004] Patent Documents

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

[0006] Technical Problem to be Solved by the Invention

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

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

[0009] Means for Solving the Technical Problem

[0010] In order to solve the above technical problem, the damping device is provided in a hydraulic control unit that controls the braking force generated at the wheels, and has an inlet port connected to the discharge side of the pump and an outlet port communicating with the inlet port, and is a damping device that attenuates pressure pulsation, and includes: a first liquid chamber communicating with the inlet port via a first opening; a second liquid chamber communicating with the first liquid chamber via a communication hole and communicating with the outlet port via a second opening; a first piston slidably provided in the first liquid chamber; a first biasing member biasing the first piston toward the first opening side; a valve body provided in the second liquid chamber and capable of opening and closing the second opening side of the communication hole; a second biasing member biasing the valve body toward the first opening side; and a protrusion provided on the second opening side of the first piston, capable of being inserted into the communication hole and capable of abutting against the valve body.

[0011] To solve the above technical problems, the hydraulic control unit is provided with the above damping device.

[0012] To solve the above technical problems, the braking system is provided with the above hydraulic control unit.

[0013] Advantageous Effects of the Invention

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

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

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

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

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

[0019] Figure 5 FIG. is a cross-sectional view showing a schematic configuration of a damping device according to a second embodiment of the present invention.

[0020] Figure 6 FIG. is a view showing a state in which a second piston has moved to the right as compared with the state of Figure 5 in a damping device according to a second embodiment of the present invention.

[0021] Figure 7 FIG. is a view showing a state in which a first piston has moved to the right as compared with the state of Figure 6 in a damping device according to a second embodiment of the present invention.

[0022] Figure 8 FIG. is a view showing a state in which a first piston has moved to the right as compared with the state of Figure 7 in a damping device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, while referring to the attached Figure 1The preferred embodiments of the present invention will be described in detail below. The dimensions, materials, other specific numerical values, etc. shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless specifically negated. In addition, in this specification and the drawings, elements having substantially the same functions and structures are given the same reference numerals to omit redundant descriptions, and elements not directly related to the present invention are omitted from the illustration.

[0024] In this embodiment, a vehicle having four wheels 17 is taken as an example for description, but the vehicle to which the present invention is applied is not limited to a vehicle having four wheels 17. For example, it may also be a vehicle having one, two, or three wheels 17, or a vehicle having five or more wheels 17.

[0025] <First Embodiment>

[0026] Refer to Figures 1 to 4 , and the first embodiment of the present invention will be described.

[0027] (Structure of the braking system)

[0028] Refer to Figure 1 , and the structure of the braking system 1 according to the first embodiment of the present invention will be described.

[0029] Figure 1 is a schematic diagram showing the schematic structure of the braking system 1. The braking system 1 is mounted on a vehicle and is a system for controlling the braking force generated in the vehicle. As Figure 1 shown, the braking system 1 includes a brake pedal 11, a booster device 12, a master cylinder 13, a reservoir 14, a hydraulic control unit 15, a braking device 16, and wheels 17.

[0030] 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. Moreover, the braking force generated on each wheel 17 is controlled by the hydraulic control unit 15. In Figure 1 , for ease of understanding, in the braking system 1, only the part related to one of the front wheels and the rear wheels is shown, and the illustration of the part related to the other of the front wheels and the rear wheels is omitted.

[0031] In addition, the number of wheels 17 whose braking force is controlled by the hydraulic control unit according to the present invention may also be other than four. For example, the number of wheels 17 whose braking force is controlled by the hydraulic control unit 15 may also be two. In this case, the braking system 1 can be mounted on a vehicle having two wheels 17.

[0032] The brake pedal 11 is used in a braking operation performed by a driver. During the braking operation, the brake pedal 11 is depressed by the driver. The power booster device 12 is connected to the brake pedal 11 and amplifies the stepping force of the brake pedal 11. The master cylinder 13 is connected to the power booster device 12 and has a piston that reciprocates in conjunction with the brake pedal 11, generating hydraulic pressure corresponding to the operation amount of the braking operation. The reservoir 14 is attached to the master cylinder 13 and stores the brake fluid.

[0033] The hydraulic control unit 15 includes a base body 15a that forms a flow path for the brake fluid. The master cylinder 13 and each brake device 16 are respectively connected to the base body 15a of the hydraulic control unit 15. The flow path of 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.

[0034] 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 allows the brake fluid from the master cylinder 13 to flow to the wheel cylinder of the brake device 16. The sub-flow path 22 discharges the brake fluid from the wheel cylinder of the brake device 16. The supply flow path 23 supplies the brake fluid from the master cylinder 13 to the sub-flow path 22.

[0035] In addition, in the base body 15a of the hydraulic control unit 15, a filling valve (EV) 31, a release valve (AV) 32, a first valve (USV) 33, a second valve (HSV) 34, an accumulator 35, a pump 36, and a motor 37 are provided as components for controlling the braking force generated on each wheel 17.

[0036] In addition, the structure of the hydraulic control unit related to the present invention only needs to have a pump 36, and it may also be different from the structure of the hydraulic control unit 15 shown in Figure 1 For example, the hydraulic control unit related to the present invention may also include a structure in which the supply flow path 23, the first valve 33, and the second valve 34 are omitted with respect to the hydraulic control unit 15 shown in Figure 1 The main flow path 21 connects the master cylinder 13 and the wheel cylinder of the brake device 16. The main flow path 21 includes a first main flow path 21a and two second main flow paths 21b. The first main flow path 21a is connected to the master cylinder 13. The two second main flow paths 21b branch from the first main flow path 21a and are connected to each brake device 16. The first valve 33 is provided in the first main flow path 21a. The filling valve 31 is provided in the second main flow path 21b.

[0037] The main flow path 21 connects the master cylinder 13 and the wheel cylinder of the brake device 16. The main flow path 21 includes a first main flow path 21a and two second main flow paths 21b. The first main flow path 21a is connected to the master cylinder 13. The two second main flow paths 21b branch from the first main flow path 21a and are connected to each brake device 16. The first valve 33 is provided in the first main flow path 21a. The filling valve 31 is provided in the second main flow path 21b.

[0038] The sub-flow path 22 connects the side of the main flow path 21 on the brake device 16 side relative to the filling valve 31 with the side of the main flow path 21 on the master cylinder 13 side relative to the filling valve 31 and on the brake device 16 side relative to the first valve 33. The sub-flow path 22 includes two first sub-flow paths 22a and a second sub-flow path 22b. Each first sub-flow path 22a is connected to the side of the main flow path 21 on the brake device 16 side relative to the filling valve 31. The second sub-flow path 22b connects the confluence part of the two first sub-flow paths 22a with the side of the main flow path 21 on the master cylinder 13 side relative to the filling valve 31 and on the brake device 16 side relative to the first valve 33. A release valve 32 is provided in the first sub-flow path 22a. In the second sub-flow path 22b, an accumulator 35 and a pump 36 are provided in sequence from the first sub-flow path 22a side.

[0039] The pump 36 is driven by a motor 37, sucks brake fluid from the first sub-flow path 22a side, and ejects it toward the main flow path 21 side. The pump 36 is a plunger pump that performs reciprocating motion. Specifically, the plunger of the pump 36 reciprocates by being intermittently pushed by an eccentric cam provided on the output shaft of the motor 37. Thereby, the pumping of the brake fluid by the pump 36 is performed.

[0040] The supply flow path 23 connects the side of the main flow path 21 on the master cylinder 13 side relative to the first valve 33 with the suction side of the pump 36 in the sub-flow path 22. A second valve 34 is provided in the supply flow path 23.

[0041] The filling valve 31 is, for example, an electromagnetic valve that is open in the non-energized state and closed in the energized state. The release valve 32 is, for example, an electromagnetic valve that is closed in the non-energized state and open in the energized state. The first valve 33 is, for example, an electromagnetic valve that is open in the non-energized state and closed in the energized state. The second valve 34 is, for example, an electromagnetic valve that is closed in the non-energized state and open in the energized state. By controlling the operations of these valves and the motor 37, the braking force generated at each wheel 17 is controlled.

[0042] For example, during normal times when anti-lock braking control or anti-skid control described later is not executed, the filling valve 31 is open, the release valve 32 is closed, the first valve 33 is open, and the second valve 34 is closed. Thereby, it becomes a state where the brake fluid flows from the master cylinder 13 to the wheel cylinder of the brake device 16 only through the main flow path 21 without passing through the sub-flow path 22 and the supply flow path 23. In this state, if the brake pedal 11 is depressed, the piston of the master cylinder 13 is pushed in and the hydraulic pressure of the brake fluid in the wheel cylinder increases, and a braking force is applied to the wheel 17.

[0043] Antilock braking control is control for avoiding wheel lock-up of wheel 17. For example, if antilock braking control is executed, first, the fill valve 31 is closed, the release valve 32 is opened, the first valve 33 is opened, and the second valve 34 is closed. Thereby, the flow of the brake fluid between the main flow path 21 and the wheel cylinder of the braking device 16 stops, and a state is achieved in which the brake fluid can flow from the wheel cylinder to the sub-flow path 22. Therefore, the brake fluid flows from the wheel cylinder into the accumulator 35, the hydraulic pressure of the brake fluid in the wheel cylinder decreases, and the braking force applied to the wheel 17 decreases. The brake fluid flowing into the accumulator 35 is driven by the pump 36 and returned to the main flow path 21 via the sub-flow path 22.

[0044] Next, from the above state, both the fill valve 31 and the release valve 32 are closed, the flow of the brake fluid between the main flow path 21 and the sub-flow path 22 and the wheel cylinder stops, the hydraulic pressure of the brake fluid in the wheel cylinder is maintained, and the braking force applied to the wheel 17 is maintained. Then, by opening the fill valve 31 and closing the release valve 32, the flow of the brake fluid between the main flow path 21 and the wheel cylinder restarts, the hydraulic pressure of the brake fluid in the wheel cylinder increases, and the braking force applied to the wheel 17 increases.

[0045] Anti-skid control is control for stabilizing the dynamics of the vehicle. In anti-skid control, the driving force and braking force of the vehicle are appropriately controlled. For example, during the execution of anti-skid control, when the vehicle is braked regardless of the braking operation, the fill valve 31 is opened, the release valve 32 is closed, the first valve 33 is closed, and the second valve 34 is opened. Thereby, a state is achieved in which the brake fluid flows from the master cylinder 13 to the wheel cylinder of the braking device 16 via the supply flow path 23 and the sub-flow path 22. In this state, by driving the pump 36, the hydraulic pressure of the brake fluid in the wheel cylinder increases, and a braking force for braking the wheel 17 is generated.

[0046] As described above, in the hydraulic control unit 15, control for driving the pump 36 is performed. If the pump 36 is driven, a phenomenon of hydraulic pressure pulsation of the brake fluid, i.e., pressure pulsation, occurs in the flow path within the hydraulic control unit 15. The sound generated by such pressure pulsation may be perceived as noise by the vehicle occupants and may cause discomfort. Therefore, in the hydraulic control unit 15, a damping device 100 for attenuating the pressure pulsation is provided.

[0047] The damping device 100 is provided on the downstream side of the pump 36 in the sub-flow path 22 (specifically, the second sub-flow path 22b). The damping device 100 has an inlet port P1 and an outlet port P2. The inlet port P1 is connected to the discharge side of the pump 36. The inlet port P1 communicates with the outlet port P2. Therefore, the brake fluid discharged from the pump 36 flows into the damping device 100 via the inlet port P1, and after passing through the inside of the damping device 100, flows out of the damping device 100 via the outlet port P2.

[0048] (Structure of the attenuation device)

[0049] Refer to Figure 2 , and the structure of the attenuation device 100 according to the first embodiment of the present invention will be described.

[0050] Figure 2 is a cross-sectional view showing a schematic structure of the attenuation device 100. However, Figure 2 The attenuation device 100 shown is merely an example of the attenuation device of the present invention, and structures obtained by making various changes to the Figure 2 example as described later are also included in the attenuation device of the present invention.

[0051] In Figure 2 and the following Figure 3 , Figure 4 , the attenuation device 100 is shown with the axial direction of the housing 101 as the left-right direction, the first opening PO1 connected to the inlet port P1 located on the left side in this axial direction, and the second opening PO2 connected to the outlet port P2 located on the right side in this axial direction. Hereinafter, the axial direction of the housing 101, i.e., the left-right direction, will also be simply referred to as the axial direction. The first opening PO1 side refers to the side facing the first opening PO1 in the axial direction, or the upstream side of the flow direction of the brake fluid from the first opening PO1 toward the second opening PO2. The second opening PO2 side refers to the side facing the second opening PO2 in the axial direction, or the downstream side of the flow direction of the brake fluid from the first opening PO1 toward the second opening PO2.

[0052] As Figure 2 shown, the attenuation device 100 includes a housing 101, a first cover 111, a second cover 112, a third cover 113, a first piston 121, a first sealing member 131, a first biasing member 141, a second biasing member 142, and a valve body 151.

[0053] The housing 101 is formed, for example, in a cylindrical shape having a hollow space inside. The axial direction of the housing 101 is the left-right direction. An internal space is formed in the housing 101 so as to penetrate from the left end face to the right end face. The internal space of the housing 101 includes a first hole portion 101a, a second hole portion 101b, and a third hole portion 101c. Each of the first hole portion 101a, the second hole portion 101b, and the third hole portion 101c has a cylindrical shape and is arranged coaxially with the central axis of the housing 101. The first hole portion 101a, the second hole portion 101b, and the third hole portion 101c are continuous in this order from the left side. The diameter of the second hole portion 101b is smaller than the diameter of the first hole portion 101a. The diameter of the third hole portion 101c is larger than the diameter of the second hole portion 101b.

[0054] The third cover 113 is fitted into the first hole portion 101a. The third cover 113 is formed in a disk shape having a first opening PO1 at the center. The first opening PO1 is connected to the inlet port P1. The first opening PO1 is disposed coaxially with the central axis of the housing 101. However, the first opening PO1 may not be disposed coaxially with the central axis of the housing 101.

[0055] The first cover 111 is fitted into the third hole portion 101c. The first cover 111 has a substantially cylindrical shape. The right end portion of the outer peripheral surface of the first cover 111 is expanded in diameter outward in the radial direction. The portion of the first cover 111 that is expanded in diameter outward in the radial direction is fitted into the third hole portion 101c.

[0056] The first liquid chamber S1 is delimited by the right side surface of the third cover 113, the left side surface of the first cover 111, and the inner peripheral surface of the second hole portion 101b of the housing 101. That is, the third cover 113 covers the first liquid chamber S1 from the left side. The first cover 111 covers the first liquid chamber S1 from the right side. In other words, the left side surface of the first cover 111 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.

[0057] The second liquid chamber S2 is delimited by the inner peripheral surface of the first cover 111. The left end portion of the inner peripheral surface of the first cover 111 is reduced in diameter inward in the radial direction. Thereby, a communication hole 111a is formed at the center of the left end portion of the first cover 111. The second liquid chamber S2 communicates with the first liquid chamber S1 via the communication hole 111a.

[0058] The second cover 112 is fitted into the right end portion of the inner peripheral surface of the first cover 111. The second cover 112 is formed in a substantially disk shape having a second opening PO2 at the center. The second opening PO2 is connected to the outlet port P2. The second opening PO2 is disposed coaxially with the central axis of the housing 101. However, the second opening PO2 may not be disposed coaxially with the central axis of the housing 101.

[0059] The right end portion of the outer peripheral surface of the second cover 112 is expanded in diameter outward in the radial direction. The right end portion of the inner peripheral surface of the first cover 111 is also expanded in diameter. The portion of the outer peripheral surface of the second cover 112 that is expanded in diameter outward in the radial direction is fitted into the portion of the inner peripheral surface of the first cover 111 that is expanded in diameter. Thereby, the second liquid chamber S2 is delimited by the left side surface of the second cover 112. That is, the second cover 112 covers the second liquid chamber S2 from the right side. In other words, the left side surface of the second cover 112 constitutes the right side wall surface of the second liquid chamber S2. The second liquid chamber S2 communicates with the outlet port P2 via the second opening PO2.

[0060] The first piston 121 is housed in the second hole portion 101b. The first piston 121 has a substantially cylindrical shape. The first piston 121 is arranged coaxially with the central axis of the second hole portion 101b. The first piston 121 has a first cylindrical portion 121a, a second cylindrical portion 121b, and a protrusion portion 121c. The first cylindrical portion 121a, the second cylindrical portion 121b, and the protrusion portion 121c have a cylindrical shape and are arranged coaxially with each other. The first cylindrical portion 121a, the second cylindrical portion 121b, and the protrusion portion 121c are continuous in this order from the left side. The outer diameters of the first cylindrical portion 121a, the second cylindrical portion 121b, and the protrusion portion 121c become smaller in this order. The outer peripheral surface of the first cylindrical portion 121a can slide relative to the inner peripheral surface of the second hole portion 101b. Therefore, the first piston 121 is slidably arranged in the first liquid chamber S1 in the axial direction.

[0061] An annular groove 121d is formed on the outer peripheral surface of the first cylindrical portion 121a. The annular groove 121d extends in the circumferential direction of the first piston 121. The first sealing member 131 is fitted in the annular groove 121d. The first sealing member 131 is, for example, an O-ring. The first sealing member 131 is pressed against the inner peripheral surface of the second hole portion 101b. Thereby, the gap between the outer peripheral surface of the first cylindrical portion 121a and the inner peripheral surface of the second hole portion 101b is hermetically sealed.

[0062] The first piston 121 is biased to the left by the first biasing member 141. The first biasing member 141 is, for example, an elastic member such as a spring. The first biasing member 141 is arranged between the first piston 121 and the first cover 111. One end ( Figure 2 the left end in) of the first biasing member 141 abuts against the abutting surface 121e provided on the right side of the first piston 121. The abutting surface 121e is the right side surface of the first cylindrical portion 121a (i.e., the stepped surface between the first cylindrical portion 121a and the second cylindrical portion 121b). The other end ( Figure 2 the right end in) of the first biasing member 141 abuts against the recessed portion 111b of the first cover 111. The recessed portion 111b is formed in a ring shape along the periphery of the communication hole 111a. Therefore, the other end of the first biasing member 141 abuts against the periphery on the left side of the communication hole 111a. The expansion and contraction direction of the first biasing member 141 is the left-right direction. The first biasing member 141 is in a state of being contracted relative to its natural length.

[0063] A plurality of first through holes 121f are formed in the first piston 121. The first through holes 121f penetrate the first piston 121 from the left side to the right side. In Figure 2 the example of, the first through hole 121f extends from the left side surface of the first cylindrical portion 121a to the right side surface of the second cylindrical portion 121b. The inner diameter of the first through hole 121f is, for example, about 0.4 mm to 0.5 mm in diameter. In Figure 2In the example, the first through-hole 121f extends axially. However, the path of the first through-hole 121f is not particularly limited. For example, the first through-hole 121f may also extend in a direction inclined with respect to the axial direction, or may be bent or folded.

[0064] A plurality of first through-holes 121f are arranged at equal intervals in the circumferential direction of the first piston 121. However, the arrangement of the plurality of first through-holes 121f is not limited to this example. For example, the plurality of first through-holes 121f may also be arranged at unequal intervals in the circumferential direction. In addition, the number of the first through-holes 121f may also be one. Brake fluid can flow from the left side to the right side of the first piston 121 through the first through-hole 121f. The first through-hole 121f is provided to improve the effect of reducing pressure pulsation. In addition, the function of the first through-hole 121f will be described later.

[0065] In the first cover 111, a plurality of second through-holes 111c that achieve the same effect as the first through-hole 121f are also formed. The second through-holes 111c penetrate the first cover 111 from the left side to the right side. In Figure 2 In the example, the second through-hole 111c extends from a position radially inside the contact portion with the first biasing member 141 in the recessed portion 111b to the right side surface of the first cover 111. The inner diameter of the second through-hole 111c is, for example, about 0.4 mm to 0.5 mm in diameter. In Figure 2 In the example, the second through-hole 111c extends axially. However, the path of the second through-hole 111c is not particularly limited. For example, the second through-hole 111c may also extend in a direction inclined with respect to the axial direction, or may be bent or folded.

[0066] A plurality of second through-holes 111c are arranged at equal intervals in the circumferential direction of the first cover 111. However, the arrangement of the plurality of second through-holes 111c is not limited to this example. For example, the plurality of second through-holes 111c may also be arranged at unequal intervals in the circumferential direction. In addition, the number of the second through-holes 111c may also be one. Brake fluid can flow from the left side to the right side of the first cover 111 through the second through-hole 111c. The second through-hole 111c is provided to improve the effect of reducing pressure pulsation. In addition, the function of the second through-hole 111c will be described later

[0067] The valve body 151 is provided in the second liquid chamber S2 and can open and close the right side of the communication hole 111a. In the open state where the valve body 151 does not block the communication hole 111a, brake fluid can flow through the communication hole 111a. This state corresponds to the open state of the valve body 151 and the open state of the communication hole 111a. In the closed state where the valve body 151 blocks the communication hole 111a, brake fluid cannot flow through the communication hole 111a. This state corresponds to the closed state of the valve body 151 and the closed state of the communication hole 111a.

[0068] The valve body 151 has a spherical shape, for example. However, the shape of the valve body 151 may also be a shape other than a spherical shape. The second biasing member 142 is an elastic member such as a spring, for example. The second biasing member 142 is disposed between the second cover 112 and the valve body 151. The expansion and contraction direction of the second biasing member 142 is the left-right direction. The second biasing member 142 is in a state of being contracted relative to its natural length. Therefore, the valve body 151 is biased to the left by the second biasing member 142.

[0069] The valve body 151 is opened and closed by the protrusion 121c of the first piston 121. The protrusion 121c extends axially toward the right from the right-side surface of the second cylindrical portion 121b. In this way, the protrusion 121c is provided on the right side of the first piston 121. As the first piston 121 moves to the right from Figure 2 its position, the protrusion 121c is inserted into the communication hole 111a, and the tip of the protrusion 121c can abut against the valve body 151. When the tip of the protrusion 121c abuts against the valve body 151, the valve body 151 is in an open state. In this way, the protrusion 121c can be inserted into the communication hole 111a and can abut against the valve body 151.

[0070] (Operation of the damping device)

[0071] Refer to Figures 2 to 4 to describe the operation of the damping device 100 according to the first embodiment of the present invention.

[0072] In the above Figure 2 , the damping device 100 in the normal state where the pump 36 is not driven in the hydraulic control unit 15 is shown. In this case, the first piston 121 is biased to the left by the first biasing member 141 and is located at the leftmost position in the movable range. Therefore, the protrusion 121c of the first piston 121 moves away from the valve body 151 and does not abut against the valve body 151. The valve body 151 is biased to the left by the second biasing member 142 and is located at the leftmost position in the movable range. Therefore, the valve body 151 is in a closed state.

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

[0074] Figure 3 is a diagram showing a state in which the first piston 121 in the damping device 100 has moved to the right compared to the state of Figure 2 . InFigure 3 In the state of Figure 2 , pressure is accumulated in the space on the left side of the first piston 121 in the first liquid chamber S1. Moreover, the first piston 121 is pushed to the right by the pressure in the space on the left side of the first piston 121 in the first liquid chamber S1, and

[0075] Here, in Figure 3 the state of

[0076] the brake fluid in the space on the left side of the first piston 121 in the first liquid chamber S1 is sent to the space on the right side of the first piston 121 in the first liquid chamber S1 through the first through hole 121f. Here, the inner diameter of the first through hole 121f is small, and a large resistance acts on the brake fluid flowing through the first through hole 121f. Therefore, the pressure pulsation is also attenuated by the brake fluid flowing through the first through hole 121f.

[0077] Figure 4 is a diagram showing a state in which the first piston 121 has moved to the right compared to the state of Figure 3 in the attenuation device 100. In Figure 4 the state of Figure 3 the first piston 121 has moved further to the right compared to the state of Figure 4 Here, in Figure 3 the state of

[0078] (Effect of the attenuation device)

[0079] The effects of the attenuation device 100 according to the first embodiment of the present invention will be described.

[0080] 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 111a and communicating with an outlet port P2 via a second opening PO2; a first piston 121 slidably disposed in the first liquid chamber S1; a first biasing member 141 biasing the first piston 121 toward the first opening PO1 side; a valve body 151 disposed in the second liquid chamber S2 and capable of opening and closing the second opening PO2 side of the communication hole 111a; a second biasing member 142 biasing the valve body 151 toward the first opening PO1 side; and a protrusion 121c provided on the first piston 121 on the second opening PO2 side, capable of being inserted into the communication hole 111a and capable of abutting against the valve body 151.

[0081] Thus, when the pump 36 is driven, first, pressure is accumulated in the space on the first opening PO1 side of the first piston 121 in the first liquid chamber S1. Next, during this period, as the first piston 121 moves toward the second opening PO2 side, the first biasing member 141 gradually contracts, whereby the energy of the rising pressure is absorbed, and the rising speed of the pressure on the second opening PO2 side of the first piston 121 becomes slower than the rising speed of the pressure on the first opening PO1 side of the first piston 121. In addition, when the pressure on the first opening PO1 side decreases and the first piston 121 moves toward the first opening PO1 side, the first biasing member 141 gradually extends, and the decreasing speed of the pressure on the second opening PO2 side of the first piston 121 becomes slower than the decreasing speed of the pressure on the first opening PO1 side of the first piston 121. Thereby, the pressure pulsation on the second opening PO2 side can be attenuated with respect to the pressure pulsation on the first opening PO1 side. Further, by the protrusion 121c of the first piston 121 abutting against the valve body 151, the communication hole 111a is brought into an open state, and the brake fluid can appropriately flow out from the second liquid chamber S2 via the second opening PO2. In this way, according to the damping device 100, the pressure pulsation of the hydraulic control unit 15 can be attenuated.

[0082] Preferably, in the damping device 100, at least one first through hole 121f penetrating from the first opening PO1 side to the second opening PO2 side is formed in the first piston 121. Thereby, the pressure pulsation can also be attenuated by the brake fluid flowing through the first through hole 121f. Here, a situation where the first piston 121 is fixed and no longer movable can be considered. In such a situation, the brake fluid can flow from the first opening PO1 side to the second opening PO2 side of the first piston 121 through the first through hole 121f. Therefore, the pressure in the space on the first opening PO1 side of the first piston 121 in the first liquid chamber S1 is prevented from becoming excessively high.

[0083] Preferably, in the damping device 100, a plurality of first through holes 121f are formed in the first piston 121, and the plurality of first through holes 121f are arranged at equal intervals in the circumferential direction of the first piston 121. Thus, the force generated due to the flow of the brake fluid in the first through holes 121f acts on the first piston 121 evenly in the circumferential direction. Therefore, the inclination of the first piston 121 with respect to the sliding direction is suppressed by the force acting on the first piston 121 due to the flow of the brake fluid in the first through holes 121f.

[0084] Preferably, the damping device 100 includes a first cover 111 that divides the second liquid chamber S2 and covers the first liquid chamber S1 from the second opening PO2 side; at least one second through hole 111c that penetrates from the first opening PO1 side to the second opening PO2 side is formed in the first cover 111. Thus, the pressure pulsation can also be attenuated by the flow of the brake fluid in the second through hole 111c.

[0085] Preferably, in the damping device 100, a plurality of second through holes 111c are formed in the first cover 111; the plurality of second through holes 111c are arranged at equal intervals in the circumferential direction of the first cover 111. Thus, the flow region of the brake fluid is homogenized in the circumferential direction around the first cover 111. Therefore, the brake fluid can flow smoothly within the damping device 100.

[0086] <Second Embodiment>

[0087] Refer to Figures 5 to 8 , and a second embodiment of the present invention will be described.

[0088] In the second embodiment, compared with the above-described first embodiment, the damping device 100 is replaced with a damping device 200. Other points of the braking system 1 are the same as those of the above-described first embodiment, so the description thereof is omitted.

[0089] (Structure of the damping device)

[0090] Refer to Figure 5 , and details of the structure of the damping device 200 according to the second embodiment of the present invention will be described.

[0091] Figure 5 is a cross-sectional view showing a schematic structure of the damping device 200. However, Figure 5 the damping device 200 shown is merely an example of the damping device according to the present invention, and structures in which various modifications are made to the example of Figure 5 as described later are also included in the damping device according to the present invention.

[0092] In Figure 5 and the following Figures 6 to 8In the figure, the attenuation device 200 is shown in such a way that the axial direction of the housing 201 is the left - right direction, the first opening PO1 connected to the inlet port P1 is located on the left side of the axial direction, and the second opening PO2 connected to the outlet port P2 is located on the right side of the axial direction. Hereinafter, the axial direction of the housing 201, that is, the left - right direction, will also be simply referred to as the axial direction. The first - opening PO1 side refers to the side facing the first opening PO1 in the axial direction, or the upstream side of the flow direction of the brake fluid from the first opening PO1 toward the second opening PO2. The second - opening PO2 side refers to the side facing the second opening PO2 in the axial direction, or the downstream side of the flow direction of the brake fluid from the first opening PO1 toward the second opening PO2.

[0093] As Figure 5 shown, the attenuation device 200 includes a housing 201, a first cover 211, a second cover 212, a third cover 213, a first piston 221, a second piston 222, a first sealing member 231, a second sealing member 232, a first biasing member 241, a second biasing member 242, a third biasing member 243, a valve body 251, and an elastic member 261.

[0094] The housing 201 is formed, for example, in a cylindrical shape having a hollow space inside. The axial direction of the housing 201 is the left - right direction. An internal space is formed in the housing 201 so as to penetrate from the left end face to the right end face. The internal space of the housing 201 includes a first hole portion 201a, a second hole portion 201b, and a third hole portion 201c. Each of the first hole portion 201a, the second hole portion 201b, and the third hole portion 201c has a cylindrical shape and is arranged coaxially with the central axis of the housing 201. The first hole portion 201a, the second hole portion 201b, and the third hole portion 201c are continuous in this order from the left side. The diameter of the second hole portion 201b is smaller than the diameter of the first hole portion 201a. The diameter of the third hole portion 201c is larger than the diameter of the second hole portion 201b.

[0095] The third cover 213 is fitted into the left end portion of the first hole portion 201a. The third cover 213 is formed in a disk shape having a first opening PO1 at the center. The first opening PO1 is connected to the inlet port P1. The first opening PO1 is arranged coaxially with the central axis of the housing 201. However, the first opening PO1 may not be arranged coaxially with the central axis of the housing 201.

[0096] The first cover 211 is fitted into the third hole portion 201c. The first cover 211 has a substantially cylindrical shape. The first cover 211 has a first cylindrical portion 211a and a second cylindrical portion 211b. The first cylindrical portion 211a and the second cylindrical portion 211b have a cylindrical shape and are arranged coaxially with each other. The first cylindrical portion 211a and the second cylindrical portion 211b are continuous in this order from the right side. The outer diameter of the second cylindrical portion 211b is smaller than the outer diameter of the first cylindrical portion 211a. The inner diameters of the first cylindrical portion 211a and the second cylindrical portion 211b are the same as each other. However, the inner diameter of the second cylindrical portion 211b may also be smaller than the inner diameter of the first cylindrical portion 211a or may be larger than it. The first cylindrical portion 211a is fitted into the third hole portion 201c. The outer peripheral surface of the second cylindrical portion 211b is radially spaced from the inner peripheral surface of the second hole portion 201b.

[0097] The first liquid chamber S1 is delimited by the right side surface of the third cover 213, the left side surface of the first cover 211, the inner peripheral surface of the first hole portion 201a of the housing 201, and the inner peripheral surface of the second hole portion 201b of the housing 201. That is, the third cover 213 covers the first liquid chamber S1 from the left side. The first cover 211 covers the first liquid chamber S1 from the right side. In other words, the left side surface of the first cover 211 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.

[0098] The second liquid chamber S2 is delimited by the inner peripheral surface of the first cover 211. The left end portion of the inner peripheral surface of the first cover 211 is reduced in diameter radially inward. Thereby, a communication hole 211c is formed at the center of the left end portion of the first cover 211. The second liquid chamber S2 communicates with the first liquid chamber S1 via the communication hole 211c.

[0099] The second cover 212 is fitted into the right end portion of the inner peripheral surface of the first cover 211. The second cover 212 is formed in a substantially disc shape having a second opening PO2. The second opening PO2 is connected to the outlet port P2. The second opening PO2 is arranged radially outside the center of the second cover 212. In Figure 5 the example, the number of the second openings PO2 is plural. However, the number of the second openings PO2 may also be one.

[0100] The right end portion of the inner peripheral surface of the first cover 211 is enlarged in diameter. The second cover 212 is fitted into the enlarged portion of the inner peripheral surface of the first cover 211. Thereby, the second liquid chamber S2 is delimited by the left side surface of the second cover 212. That is, the second cover 212 covers the second liquid chamber S2 from the right side. In other words, the left side surface of the second cover 212 constitutes the right side wall surface of the second liquid chamber S2. The second liquid chamber S2 communicates with the outlet port P2 via the second opening PO2.

[0101] The first piston 221 is housed inside the first hole portion 201a and the second hole portion 201b. The first piston 221 has a substantially cylindrical shape. The first piston 221 is arranged coaxially with the central axes of the first hole portion 201a and the second hole portion 201b. The first piston 221 has a first cylindrical portion 221a, a second cylindrical portion 221b, and a protrusion portion 221c. The first cylindrical portion 221a, the second cylindrical portion 221b, and the protrusion portion 221c have a cylindrical shape and are arranged coaxially with each other. The first cylindrical portion 221a, the second cylindrical portion 221b, and the protrusion portion 221c are continuous in this order from the left side. The outer diameters of the first cylindrical portion 221a, the second cylindrical portion 221b, and the protrusion portion 221c become smaller in this order. The outer peripheral surface of the first cylindrical portion 221a can slide relative to the inner peripheral surface of the first hole portion 201a. Therefore, the first piston 221 can be slidably arranged in the first liquid chamber S1 in the axial direction.

[0102] An annular groove 221d is formed on the outer peripheral surface of the first cylindrical portion 221a. The annular groove 221d extends in the circumferential direction of the first piston 221. The first sealing member 231 is fitted in the annular groove 221d. The first sealing member 231 is, for example, an O-ring. The first sealing member 231 is pressed against the inner peripheral surface of the first hole portion 201a. Thereby, the gap between the outer peripheral surface of the first cylindrical portion 221a and the inner peripheral surface of the first hole portion 201a is hermetically sealed.

[0103] The first piston 221 is urged to the left side by the first biasing member 241. The first biasing member 241 is an elastic member such as a spring, for example. The first biasing member 241 is arranged between the first piston 221 and the first cover 211. One end ( Figure 5 the left end in it) of the first biasing member 241 abuts against the abutting surface 221e provided on the right side of the first piston 221. The abutting surface 221e is the right side surface of the second cylindrical portion 221b (that is, the step surface between the second cylindrical portion 221b and the protrusion portion 221c). The other end ( Figure 5 the right end in it) of the first biasing member 241 abuts against the annular groove 211d of the first cover 211. The annular groove 211d is formed at the left end portion of the outer peripheral surface of the second cylindrical portion 211b of the first cover 211 and extends in the circumferential direction. Therefore, the other end of the first biasing member 241 abuts against the periphery on the left side of the communication hole 211c. The expansion and contraction direction of the first biasing member 241 is the left-right direction. The first biasing member 241 is in a state of being contracted relative to its natural length.

[0104] A plurality of first through holes 221f are formed in the first piston 221. The first through holes 221f penetrate the first piston 221 from the left side to the right side. In Figure 5In the example, the first through hole 221f extends from the left side surface of the first cylindrical portion 221a to the right side surface of the first cylindrical portion 221a (i.e., the step surface between the first cylindrical portion 221a and the second cylindrical portion 221b). The inner diameter of the first through hole 221f is, for example, about 0.4 mm to 0.5 mm in diameter. In Figure 5 In the example, the first through hole 221f extends in the axial direction. However, the path of the first through hole 221f is not particularly limited. For example, the first through hole 221f may also extend in a direction inclined with respect to the axial direction, or may be bent or kinked.

[0105] A plurality of first through holes 221f are arranged at equal intervals in the circumferential direction of the first piston 221. However, the arrangement of the plurality of first through holes 221f is not limited to this example. For example, the plurality of first through holes 221f may also be arranged at unequal intervals in the circumferential direction. In addition, the number of the first through holes 221f may also be one. The brake fluid can flow from the left side to the right side of the first piston 221 through the first through hole 221f. The first through hole 221f is provided to improve the effect of reducing pressure pulsation. In addition, the function of the first through hole 221f will be described later.

[0106] The brake fluid after passing through the first through hole 221f is sent to the space outside the first biasing member 241 (specifically, the radially outer space) in the space on the right side of the first piston 221 in the first liquid chamber S1. Here, on the abutting surface 221e of the first piston 221, a communication groove 221g is provided that communicates the space inside the first biasing member 241 (specifically, the radially inner space) with the space outside the first biasing member 241. For example, the communication groove 221g extends in the radial direction of the first piston 221. The brake fluid can flow from the space outside the first biasing member 241 to the space inside the first biasing member 241 through the communication groove 221g. In Figure 5 In the example, the number of the communication grooves 221g is plural. However, the number of the communication grooves 221g may also be one. The communication groove 221g is provided to appropriately send the brake fluid to the communication hole 211c and the second liquid chamber S2. In addition, the function of the communication groove 221g will be described later.

[0107] In the first cylindrical portion 221a, a hole portion 221h is formed. The hole portion 221h is a portion that is recessed from the left side toward the right side in the first piston 221. In Figure 5 In the example, the hole portion 221h is recessed from the left side surface of the first cylindrical portion 221a toward the right side. The hole portion 221h is arranged coaxially with the central axis of the housing 201. However, the hole portion 221h may not be arranged coaxially with the central axis of the housing 201.

[0108] The second piston 222 is received in the hole portion 221h. The second piston 222 has a substantially cylindrical shape. The second piston 222 is arranged coaxially with the central axis of the hole portion 221h. The outer peripheral surface of the second piston 222 can slide relative to the inner peripheral surface of the hole portion 221h. Therefore, the second piston 222 is slidably arranged in the hole portion 221h in the axial direction.

[0109] An annular groove 222a is formed on the outer peripheral surface of the second piston 222. The annular groove 222a extends in the circumferential direction of the second piston 222. The second sealing member 232 is fitted in the annular groove 222a. The second sealing member 232 is, for example, an O-ring. The second sealing member 232 is pressed against the inner peripheral surface of the hole portion 221h. Thereby, the gap between the outer peripheral surface of the second piston 222 and the inner peripheral surface of the hole portion 221h is sealed in a liquid-tight manner.

[0110] The second piston 222 is urged to the left by a third urging member 243. The third urging member 243 is an elastic member such as a spring, for example. The third urging member 243 is arranged between the second piston 222 and the bottom surface of the hole portion 221h (in Figure 5 this case, the right side surface among the inner surfaces of the hole portion 221h). One end of the third urging member 243 ( Figure 5 the left end in this case) abuts against the recessed portion 222b of the second piston 222. The recessed portion 222b is provided at the center of the right side surface of the second piston 222. The other end of the third urging member 243 ( Figure 5 the right end in this case) abuts against the bottom surface of the hole portion 221h. The expansion and contraction direction of the third urging member 243 is the left-right direction. The third urging member 243 is in a state of being contracted relative to its natural length.

[0111] The valve body 251 is arranged in the second liquid chamber S2 and can open and close the right side of the communication hole 211c. In the open state where the valve body 251 does not block the communication hole 211c, the brake fluid can flow through the communication hole 211c. This state corresponds to the open state of the valve body 251 and the open state of the communication hole 211c. In the closed state where the valve body 251 blocks the communication hole 211c, the brake fluid cannot flow through the communication hole 211c. This state corresponds to the closed state of the valve body 251 and the closed state of the communication hole 211c.

[0112] The valve body 251 has a head 251a and a shaft portion 251b. The head 251a has a substantially hemispherical shape. The left side of the head 251a is a spherical surface, which can open and close the communication hole 211c. The shaft portion 251b extends rightward from the right-facing surface of the head 251a. The cross-sectional shape of the shaft portion 251b is, for example, circular or polygonal. The shaft portion 251b is arranged coaxially with the central axis of the housing 201. The second biasing member 242 is an elastic member such as a spring, for example. The second biasing member 242 is arranged between the second cover 212 and the valve body 251. The expansion and contraction direction of the second biasing member 242 is the left-right direction. The second biasing member 242 is in a state of contracting relative to its natural length. Therefore, the valve body 251 is biased to the left by the second biasing member 242.

[0113] The valve body 251 is opened and closed by the protrusion 221c of the first piston 221. The protrusion 221c extends axially rightward from the right-facing surface of the second cylindrical portion 221b. In this way, the protrusion 221c is provided on the right side in the first piston 221. When the first piston 221 moves rightward from Figure 5 the position, the protrusion 221c is inserted into the communication hole 211c, and the tip of the protrusion 221c can abut against the valve body 251. When the tip of the protrusion 221c abuts against the valve body 251, the valve body 251 is in an open state. In this way, the protrusion 221c can be inserted into the communication hole 211c and can abut against the valve body 251.

[0114] The elastic member 261 is provided on the left side in the first cover 211 and has an annular shape extending in the circumferential direction of the first cover 211. In Figure 5 this example, the elastic member 261 abuts against the left-facing surface of the first cylindrical portion 211a of the first cover 211. In addition, the elastic member 261 is sandwiched between the outer peripheral surface of the second cylindrical portion 211b of the first cover 211 and the inner peripheral surface of the second hole portion 201b. The elastic member 261 is an O-ring, for example.

[0115] (Operation of the damping device)

[0116] Refer to Figures 5 to 8 to describe the operation of the damping device 200 according to the second embodiment of the present invention.

[0117] In the above Figure 5In [the figure], the damping device 200 in the normal state where the pump 36 is not driven in the hydraulic control unit 15 is shown. In this case, the first piston 221 is biased to the left by the first biasing member 241 and is located at the leftmost position in the movable range. Therefore, the protrusion 221c of the first piston 221 separates from the valve body 251 and does not contact the valve body 251. The valve body 251 is biased to the left by the second biasing member 242 and is located at the leftmost position in the movable range. Therefore, the valve body 251 is in the closed state. In addition, the second piston 222 is biased to the left by the third biasing member 243 and is located at the leftmost position in the movable range.

[0118] Here, in the hydraulic control unit 15, when anti-lock braking control or anti-skid control is performed as described above, the pump 36 is driven. In Figure 5 this state, if the pump 36 is driven, the brake fluid flows into the damping device 200 through the first opening PO1, and the pressure in the space to the left of the first piston 221 in the first liquid chamber S1 increases. As a result, first, the second piston 222 moves to the right. For example, since the elastic modulus of the second biasing member 242 is lower than that of the first biasing member 241, the second piston 222 moves before the first piston 221. In addition, the elastic modulus is a physical property value indicating the difficulty of deformation and is also referred to as the spring constant, elastic constant, or elastic coefficient.

[0119] Figure 6 is a diagram showing the state in which the second piston 222 in the damping device 200 has moved to the right compared to the Figure 5 state. In Figure 6 this state, pressure is accumulated in the space to the left of the first piston 221 in the first liquid chamber S1. Moreover, the second piston 222 is pushed to the right by the pressure in the space to the left of the first piston 221 in the first liquid chamber S1 and has moved to the right compared to the Figure 5 state. When the second piston 222 moves to the right, the third biasing member 243 expands and contracts, but as a result, it contracts. Thus, the force acting on the second piston 222 is absorbed by the third biasing member 243. In this way, the pressure pulsation is attenuated by the expansion and contraction of the third biasing member 243 as the second piston 222 moves.

[0120] Here, in Figure 6 this state, the brake fluid in the space to the left of the first piston 221 in the first liquid chamber S1 is sent to the space to the right of the first piston 221 in the first liquid chamber S1 through the first through-hole 221f. Here, the inner diameter of the first through-hole 221f is small, and a large resistance acts on the brake fluid flowing through the first through-hole 221f. Therefore, the pressure pulsation is attenuated by the brake fluid flowing through the first through-hole 221f.

[0121] Figure 7shows the state in which the first piston 221 has moved to the right compared to the state of Figure 6 In the state of Figure 7 pressure is accumulated in the space on the left side of the first piston 221 in the first liquid chamber S1. Moreover, by the pressure in the space on the left side of the first piston 221 in the first liquid chamber S1, the first piston 221 is pushed to the right, and compared to the state of Figure 6 the first piston 221 has moved to the right. At this time, the second piston 222 can either move relative to the first piston 221 or not move. When the first piston 221 moves to the right, the first biasing member 241 expands and contracts, but as a result, it contracts. Thus, the force acting on the first piston 221 is absorbed by the first biasing member 241. In this way, by the expansion and contraction of the first biasing member 241 as the first piston 221 moves, the pressure pulsation is attenuated.

[0122] Here, when the first piston 221 moves to the right, not only the first biasing member 241 but also the annular elastic member 261 expands and contracts, but as a result, it contracts. Thus, the force acting on the first piston 221 is also absorbed by the elastic member 261. In this way, by the expansion and contraction of the elastic member 261 as the first piston 221 moves, the pressure pulsation is also attenuated.

[0123] Figure 8 shows the state in which the first piston 221 has moved to the right compared to the state of Figure 7 In the state of Figure 8 compared to the state of Figure 7 the first piston 221 has moved further to the right. Here, in the state of Figure 8 the protrusion 221c of the first piston 221 abuts against the valve body 251. As a result, the valve body 251 has moved to the right compared to the state of Figure 7 As a result, the valve body 251 moves away from the communication hole 211c. Therefore, the communication hole 211c becomes an open state, and the brake fluid can flow through the communication hole 211c. Thus, the brake fluid flows out from the second liquid chamber S2 through the communication hole 211c via the second opening PO2.

[0124] Here, in Figure 8In the state where [the relevant condition], there is a case where the first biasing member 241 is fully contracted and the gaps between the spring wires of the first biasing member 241 are blocked. In such a case, the brake fluid in the space on the right side of the first piston 221 that is sent to the first fluid chamber S1 through the first through hole 221f can also flow from the space outside the first biasing member 241 to the space inside the first biasing member 241 through the communication groove 221g. Therefore, the brake fluid can be sent from the space inside the first biasing member 241 to the communication hole 211c, so that the brake fluid can flow out appropriately from the second fluid chamber S2 through the second opening PO2.

[0125] In addition, as Figure 8 shown, when the valve body 251 is in the open state, the valve body 251 can abut against the second cover 212. In Figure 8 the example, the shaft portion 251b of the valve body 251 moves along the central axis of the housing 201. Here, as described above, the second opening PO2 is arranged radially outside the center of the second cover 212. Therefore, the tip of the shaft portion 251b of the valve body 251 can abut against the second cover 212. Thereby, when the valve body 251 is in the open state, the valve body 251 does not vibrate and the posture of the valve body 251 is stabilized.

[0126] (Effect of the damping device)

[0127] The effect of the damping device 200 according to the second embodiment of the present invention will be described.

[0128] The damping device 200 includes: a first fluid chamber S1 communicating with the inlet port P1 through the first opening PO1; a second fluid chamber S2 communicating with the first fluid chamber S1 through the communication hole 211c and communicating with the outlet port P2 through the second opening PO2; a first piston 221 slidably disposed in the first fluid chamber S1; a first biasing member 241 biasing the first piston 221 toward the first opening PO1 side; a valve body 251 disposed in the second fluid chamber S2 and capable of opening and closing the second opening PO2 side of the communication hole 211c; a second biasing member 242 biasing the valve body 251 toward the first opening PO1 side; and a protrusion 221c provided on the second opening PO2 side of the first piston 221, capable of being inserted into the communication hole 211c and capable of abutting against the valve body 251. Thus, similar to the above-described damping device 100, the pressure pulsation of the hydraulic control unit 15 can be attenuated.

[0129] Furthermore, the damping device 200 includes: a hole portion 221h formed by being recessed from the first opening PO1 side toward the second opening PO2 side in the first piston 221; a second piston 222 slidably provided in the hole portion 221h; and a third biasing member 243 that biases the second piston 222 toward the first opening PO1 side. Thus, when the pump 36 is driven, in addition to the movement of the first piston 221 toward the second opening PO2 side, the movement of the second piston 222 toward the second opening PO2 side also occurs. Moreover, by expanding and contracting the third biasing member 243 as the second piston 222 moves, the pressure pulsation can be further attenuated. Therefore, the pressure pulsation can be attenuated more effectively.

[0130] Preferably, the damping device 200 includes a second cover 212 that covers the second liquid chamber S2 from the second opening PO2 side; the valve body 251 can abut against the second cover 212. Thus, when the valve body 251 is in the open state, the valve body 251 does not vibrate, and the posture of the valve body 251 is stabilized. Therefore, the opening and closing operation of the valve body 251 can be made smoother.

[0131] Preferably, in the damping device 200, on the second opening PO2 side in the first piston 221, an abutting surface 221e that abuts against one end of the first biasing member 241 is provided, the other end of the first biasing member 241 abuts against the periphery of the first opening PO1 side of the communication hole 211c, and a communication groove 221g that communicates the space inside the first biasing member 241 with the space outside the first biasing member 241 is provided on the abutting surface 221e. Thus, even when the first biasing member 241 is fully contracted and the gap between the spring wires of the first biasing member 241 is blocked, the brake fluid can be conveyed from the space outside the first biasing member 241 to the space inside the first biasing member 241. Therefore, the brake fluid can flow out more appropriately from the second liquid chamber S2 via the second opening PO2.

[0132] Preferably, the damping device 200 includes a first cover 211 that partitions the second liquid chamber S2 and covers the first liquid chamber S1 from the second opening PO2 side; on the first opening PO1 side in the first cover 211, an annular elastic member 261 extending in the circumferential direction of the first cover 211 is provided. Thus, when the first piston 221 moves toward the second opening PO2 side, not only the first biasing member 241 but also the annular elastic member 261 can absorb the force acting on the first piston 221. Therefore, the pressure pulsation can be attenuated more effectively.

[0133] As above, while referring to the attached Figure 1The preferred embodiments of the present invention have been described, but the present invention is of course not limited to the above-described embodiments. Various variations or modifications within the scope described in the claims also of course fall within the technical scope of the present invention.

[0134] In the above, with reference to Figure 2 the structure of the attenuation device 100 has been described, and with reference to Figure 5 the structure of the attenuation device 200 has been described. However, for Figure 2 the examples of Figure 5 structures with various modifications can also be included in the attenuation device related to the present invention.

[0135] For example, the sliding directions of the first pistons 121 and 221 may also be different from the axial direction of the housings 101 and 201. For example, when the central axis of the first liquid chamber S1 is not arranged coaxially with the housings 101 and 201, the sliding directions of the first pistons 121 and 221 are directions different from the axial direction of the housings 101 and 201.

[0136] In addition, for example, the cross-sectional shapes of the first liquid chamber S1 and the first pistons 121 and 221 orthogonal to the sliding direction may not be circular. This cross-sectional shape may for example also be elliptical or polygonal, etc. Also, in this case, the circumferential direction of the first pistons 121 and 221 is also the direction along the outer peripheral edge of the first pistons 121 and 221, and is the direction around the central axis of the first pistons 121 and 221.

[0137] In addition, for example, the cross-sectional shapes of the first covers 111 and 211 orthogonal to the axial direction may not be circular. This cross-sectional shape may for example also be elliptical or polygonal, etc. Also, in this case, the circumferential direction of the first covers 111 and 211 is also the direction along the outer peripheral edge of the first covers 111 and 211, and is the direction around the central axis of the first covers 111 and 211.

[0138] In addition, for example, the sliding direction of the second piston 222 may also be different from the sliding direction of the first piston 221. For example, when the hole portion 221h is not arranged coaxially with the housing 201, the sliding direction of the second piston 222 is a direction different from the sliding direction of the first piston 221.

[0139] In addition, for example, the structure in which the first through hole 121f and the second through hole 111c are omitted with respect to Figure 2 the examples can also be included in the attenuation device related to the present invention. Also, when the first through hole 121f is omitted, for example, a groove extending in the axial direction may be provided on the inner peripheral surface of the second hole portion 101b, and the brake fluid can flow from the left side to the right side of the first piston 121 through this groove.

[0140] Extension. For example, it can also be relative to Figure 2 In the example of, instead of the valve body 151 and the second cover 112, Figure 5 the valve body 251 and the second cover 212 in Figure 5 are adopted. In addition, it can also be relative to Figure 2 In the example of, instead of the valve body 251 and the second cover 212,

[0141] the valve body 151 and the second cover 112 in Figure 2 are adopted.

[0142] In addition, for example, it can also be relative to Figure 2 In the example of, an elastic member 261 can be added, and it can also be relative to Figure 5 In the example of, the elastic member 261 can be omitted.

[0143] In addition, for example, relative to Figure 5 In the example of, the structure in which the first through hole 221f is omitted can also be included in the damping device according to the present invention. In addition, when the first through hole 221f is omitted, for example, a groove extending in the axial direction can be provided on the inner peripheral surface of the first hole portion 201a, and the brake fluid can flow from the left side to the right side of the first piston 221 through the groove.

[0144] In addition, for example, it can also be relative to Figure 5 In the example of, a through hole (for example, Figure 2 the second through hole 111c in

[0145] is formed in the first cover 211 so as to penetrate from the first opening PO1 side to the second opening PO2 side. Figure 5 In addition, for example, it can also be relative to

[0146] Description of Reference Numerals

[0147] 1 Brake system

[0148] 11 Brake pedal

[0149] 12 Force multiplier

[0150] 13 Master cylinder

[0151] 14 Reservoir

[0152] 15 Hydraulic control unit

[0153] 16 Brake device

[0154] 17 Wheel

[0155] 21 Main flow path

[0156] 22 Sub-flow path

[0157] 23 Supply flow path

[0158] 31 Filling valve

[0159] 32 Release valve

[0160] 33 First valve

[0161] 34 Second valve

[0162] 35 Accumulator

[0163] 36 Pump

[0164] 37 Motor

[0165] 100 Damping device

[0166] 101 Housing

[0167] 111 First cover

[0168] 111a Communication hole

[0169] 111c Second through-hole

[0170] 112 Second cover

[0171] 113 Third cover

[0172] 121 First piston

[0173] 121c Protrusion

[0174] 121e Contact surface

[0175] 121f First through-hole

[0176] 131 First sealing member

[0177] 141 First biasing member

[0178] 142 Second biasing member

[0179] 151 Valve body

[0180] 200 Damping device

[0181] 201 Housing

[0182] 211 First cover

[0183] 211c communication hole

[0184] 212 second cover

[0185] 213 third cover

[0186] 221 first piston

[0187] 221c protrusion

[0188] 221e abutting surface

[0189] 221f first through-hole

[0190] 221g communication groove

[0191] 221h hole part

[0192] 222 second piston

[0193] 231 first sealing member

[0194] 232 second sealing member

[0195] 241 first biasing member

[0196] 242 second biasing member

[0197] 243 third biasing member

[0198] 251 valve body

[0199] 261 elastic member

[0200] P1 inlet port

[0201] P2 outlet port

[0202] PO1 first opening

[0203] PO2 second opening

[0204] S1 first liquid chamber

[0205] S2 second liquid chamber

Claims

1. An attenuation device (100, 200) is provided in a hydraulic control unit (15) that controls the braking force generated at a wheel (17). It has an inlet port (P1) connected to the discharge side of a pump (36) and an outlet port (P2) communicating with the aforementioned inlet port (P1), and attenuates pressure pulsations. It is characterized in that: A first liquid chamber (S1) communicates with the aforementioned inlet port (P1) via a first opening (PO1); A second liquid chamber (S2) communicates with the aforementioned first liquid chamber (S1) via communication holes (111a, 211c) and communicates with the aforementioned outlet port (P2) via a second opening (PO2); A first piston (121, 221) is slidably disposed in the aforementioned first liquid chamber (S1); A first biasing member (141, 241) biases the aforementioned first piston (121, 221) toward the aforementioned first opening (PO1) side; A valve body (151, 251) is disposed in the aforementioned second liquid chamber (S2) and can open and close the aforementioned second opening (PO2) side of the aforementioned communication holes (111a, 211c); A second biasing member (142, 242) biases the aforementioned valve body (151, 251) toward the aforementioned first opening (PO1) side; And A protrusion (121c, 221c) is provided on the aforementioned first piston (121, 221) on the aforementioned second opening (PO2) side, can be inserted into the aforementioned communication holes (111a, 211c), and can abut against the aforementioned valve body (151, 251).

2. The attenuation device according to claim 1, It is characterized in that: At least one first through hole (121f, 221f) penetrating from the aforementioned first opening (PO1) side to the aforementioned second opening (PO2) side is formed in the aforementioned first piston (121, 221).

3. The attenuation device according to claim 2, It is characterized in that: A plurality of the aforementioned first through holes (121f, 221f) are formed in the aforementioned first piston (121, 221); The plurality of the aforementioned first through holes (121f, 221f) are arranged at equal intervals in the circumferential direction of the aforementioned first piston (121, 221).

4. The attenuation device according to claim 1, It is characterized in that: A first cover (111) is provided, and the first cover (111) divides the aforementioned second liquid chamber (S2) and covers the aforementioned first liquid chamber (S1) from the aforementioned second opening (PO2) side; At least one second through hole (111c) penetrating from the aforementioned first opening (PO1) side to the aforementioned second opening (PO2) side is formed in the aforementioned first cover (111).

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

6. The attenuation device according to claim 1, It is characterized in that: It includes: The hole portion (221h) is formed by being recessed from the side of the first opening (PO1) toward the side of the second opening (P02) in the first piston (221). The second piston (222) is slidably disposed in the hole portion (221h). And The third biasing member (243) biases the second piston (222) toward the first opening (PO1) side.

7. The damping device according to claim 1,[[]] wherein it includes a second cover (212) that covers the second liquid chamber (S2) from the side of the second opening (PO2); The valve body (251) can abut against the second cover (212).

8. The damping device according to claim 1,[[]] wherein on the side of the second opening (PO2) in the first piston (221), there is provided a contact surface (221e) that abuts against one end of the first biasing member (241); The other end of the first biasing member (241) abuts against the periphery on the side of the first opening (PO1) of the communication hole (211c); on the contact surface (221e), there is provided a communication groove (221g) that communicates the space inside the first biasing member (241) with the space outside the first biasing member (241).

9. The damping device according to claim 1,[[]] wherein it includes a first cover (211) that divides the second liquid chamber (S2) and covers the first liquid chamber (S1) from the side of the second opening (PO2); on the side of the first opening (PO1) in the first cover (211), there is provided an annular elastic member (261) that extends in the circumferential direction of the first cover (211).

10. A hydraulic control unit,[[]] wherein it includes the damping device (100, 200) according to any one of claims 1 to 9.

11. A braking system,[[]] wherein it includes the hydraulic control unit (15) according to claim 10.

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