Damping device, fluid pressure control unit and braking system

Abstract

The pressure pulsation at a fluid pressure control unit is dampened. A damping device is provided at a fluid pressure control unit for controlling braking forces generated at wheels, has an inlet port connected to the pressure side of a pump and an outlet port connected to the inlet port, and dampens the pressure pulsation, wherein the damping device is provided with a first fluid chamber connected to the inlet port via a first opening, a second fluid chamber connected to the first fluid chamber via a connecting bore and connected to the outlet port via second openings, a first piston slidably provided on the first fluid chamber and arranged in the first fluid chamber on the side opposite the second openings with respect to the first opening,a first biasing element for biasing the first piston toward the first opening side, a second piston slidably provided on the first fluid chamber and arranged on the second opening side relative to the first opening in the first fluid chamber, a second biasing element for biasing the second piston toward the first opening side, a first valve body provided on the second fluid chamber and capable of opening and closing the side of the connecting bore facing the second openings, and a third biasing element for biasing the first valve body toward the first opening side.

Description

[Technical field]

[0001] The present invention relates to a damping device, fluid pressure control unit and a braking system. [State of the art]

[0002] In existing vehicles, a fluid pressure control unit is provided to control braking forces generated at the wheels. Several valves and a pump are provided on flow channels in the fluid pressure control unit, as disclosed, for example, in Patent Document 1. This fluid pressure control unit controls the driving of the pump, for example, in anti-lock brake control or vehicle dynamics control, and each valve is set to a specific state, i.e., an open or closed state. [Prior art document][Patent document]

[0003] [Patent Document 1] JP 2010-052519 A [Summary of the invention][Problem to be solved by the invention]

[0004] A reciprocating plunger pump is primarily used as the pump in the fluid pressure control unit. Therefore, the pressure delivery of brake fluid is performed intermittently by the pump. When the pump is driven, pressure pulsation occurs, which is a phenomenon of the pulsating fluid pressure of the brake fluid in the flow channel in the fluid pressure control unit. The sound generated by this pressure pulsation may be perceived as noise by vehicle occupants and can cause a reduction in comfort. Therefore, in order to increase comfort, it is desirable to appropriately dampen the pressure pulsation of the fluid pressure control unit.

[0005] With this object in mind, the present invention aims to provide a damping device capable of damping the pressure pulsation of a fluid pressure control unit, a fluid pressure control unit, and a braking system. [Means of solving the problem]

[0006] To achieve the above object, the damping device is a damping device which is provided on a fluid pressure control unit for controlling braking forces generated on wheels, has an inlet port connected to the pressure side of a pump and an outlet port connected to the inlet port, and dampens the pressure pulsation, wherein the damping device is provided with a first fluid chamber which is connected to the inlet port via a first opening, a second fluid chamber which is connected to the first fluid chamber via a connecting bore and to the outlet port via second openings, a first piston which is slidably provided on the first fluid chamber and is arranged on the side opposite to the second openings with respect to the first opening in the first fluid chamber,a first biasing element for biasing the first piston toward the first opening side, a second piston slidably provided on the first fluid chamber and arranged on the second opening side relative to the first opening in the first fluid chamber, a second biasing element for biasing the second piston toward the first opening side, a first valve body provided on the second fluid chamber and capable of opening and closing the side of the connecting bore facing the second openings, and a third biasing element for biasing the first valve body toward the first opening side.

[0007] To achieve the above object, a fluid pressure control unit is provided with the above-mentioned damping device.

[0008] To solve the above task, a brake system is provided with the above-mentioned fluid pressure control unit. [Advantages of the invention]

[0009] According to the present invention, the pressure pulsation of the fluid pressure control unit can be damped. [Brief description of the drawings] [ Fig. 1] is a schematic view showing the schematic structure of a brake system according to an embodiment of the present invention. [ Fig. 2] is a sectional view showing the schematic structure of a damping device according to the embodiment of the present invention. [ Fig. 3] is a view of the damping device according to the embodiment of the present invention, illustrating a state in which a first piston is displaced compared with that in the state of Fig. 2 is moved to the left. [ Fig. 4] is a view of the damping device according to the embodiment of the present invention, illustrating a state in which a second piston is displaced compared with that in the state of Fig. 3 is moved to the right. [ Fig. 5] is a view of the damping device according to the embodiment of the present invention, illustrating a state in which the second piston is displaced compared with that in the state of Fig. 4 is moved to the right. [Embodiment of the invention]

[0010] A preferred embodiment of the present invention will be explained in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. indicated in the embodiment are merely examples for easy understanding of the invention and do not limit the present invention unless otherwise specified. In the present description and drawings, elements having substantially the same functions and constructions are denoted by the same reference numerals, so that repetitive explanation is omitted. Furthermore, illustration of elements not directly related to the present invention is omitted.

[0011] In the present embodiment, a vehicle with four wheels 17 is explained as an example of the vehicle. The vehicle to which the present invention is applied is not limited to the vehicle with four wheels 17 and may be, for example, a vehicle with one wheel, two or three wheels 17, or even a vehicle with five or more wheels 17. <Aufbau eines Bremssystems>

[0012] The structure of a brake system 1 according to the embodiment of the present invention will be described with reference to Fig. 1 explained.

[0013] Fig. Figure 1 is a schematic view illustrating the schematic structure of the braking system 1. The braking system 1 is a system installed in a vehicle for controlling the braking forces generated on the vehicle. The braking system 1 is provided with a brake pedal 11, a booster 12, a master cylinder 13, a reservoir 14, a fluid pressure control unit 15, braking devices 16, and wheels 17, as shown in Fig. 1 shown.

[0014] The braking system 1 is installed in a vehicle with four wheels 17, each wheel 17 being braked by the braking device 16 provided on each wheel 17. The braking force generated at each wheel 17 is controlled by the fluid pressure control unit 15. For ease of understanding, Fig. 1 shows only a part of the braking system 1 that is associated with either the front or rear wheels. The illustration of the part associated with the other front and rear wheels is omitted.

[0015] The number of wheels 17 whose braking forces are controlled by the fluid pressure control unit according to the invention may also be other than 4. For example, the number of wheels 17 whose braking forces are controlled by the fluid pressure control unit 15 may also be 2. In this case, the braking system 1 can be installed in a vehicle with two wheels 17.

[0016] The brake pedal 11 is used by the driver when applying the brakes. The brake pedal 11 is depressed by the driver when applying the brakes. The booster 12 is connected to the brake pedal 11 and amplifies the foot force on the brake pedal 11. The master cylinder 13 is connected to the booster 12, has a built-in piston that reciprocates in conjunction with the brake pedal 11, and generates a fluid pressure corresponding to the amount of brake application. The reservoir 14 is associated with the master cylinder 13 to store the brake fluid.

[0017] The fluid pressure control unit 15 is provided with a base body 15a, on which the brake fluid flow channel is formed. The master cylinder 13 and the individual brake devices 16 are connected to the base body 15a of the fluid pressure control unit 15. The brake fluid flow channel on the base body 15a of the fluid pressure control unit 15 is connected to the wheel cylinders of the brake devices 16. The braking force, which corresponds to the brake fluid pressure at the wheel cylinder of the brake device 16, is generated at the wheel 17.

[0018] A main flow channel 21, a sub-flow channel 22, and a supply flow channel 23 are formed as the brake fluid flow channel on the main body 15a of the fluid pressure control unit 15. The main flow channel 21 allows the brake fluid from the master cylinder 13 to flow to the wheel cylinders of the brake devices 16. The sub-flow channel 22 allows the brake fluid to escape from the wheel cylinders of the brake devices 16. The supply flow channel 23 supplies the brake fluid from the master cylinder 13 to the sub-flow channel 22.

[0019] On the main body 15a of the fluid pressure control unit 15, charging valves (EV) 31, release valves (AV) 32, a first valve (USV) 33, a second valve (HSV) 34, an accumulator 35, a pump 36 and a motor 37 are also provided as components for controlling the braking force generated at each wheel 17.

[0020] The structure of the fluid pressure control unit according to the invention can also differ from the structure of the fluid pressure control unit 15 according to Fig. 1, provided that it has a pump 36. The fluid pressure control unit according to the invention also includes, for example, the fluid pressure control unit 15 according to Fig. 1, from which the supply flow channel 23, the first valve 33 and the second valve 34 are omitted.

[0021] The main flow channel 21 connects the master cylinder 13 to the wheel cylinders of the brake devices 16. The main flow channel 21 contains a first main flow channel 21a and two second main flow channels 21b. The first main flow channel 21a is connected to the master cylinder 13. The two second main flow channels 21b branch off from the first main flow channel 21a and are each connected to the brake device 16. The first valve 33 is provided on the first main flow channel 21a. The charging valve 31 is provided on the second main flow channel 21b.

[0022] The bypass flow channel 22 connects a portion of the main flow channel 21 that is closer to the braking device 16 than the charging valve 31 to a portion of the main flow channel 21 that is closer to the master cylinder 13 than the charging valve 31 and closer to the braking device 16 than the first valve 33. The bypass flow channel 22 includes two first bypass flow channels 22a and a second bypass flow channel 22b. Each first bypass flow channel 22a is connected to the portion of the main flow channel 21 that is closer to the braking device 16 than the charging valve 31. The second bypass flow channel 22b connects the junction point between the two first bypass flow channels 22a to the portion of the main flow channel 21 that is closer to the master cylinder 13 than the charging valve 31 and closer to the braking device 16 than the first valve 33. The release valve 32 is provided on the first secondary flow channel 22a.On the second sub-flow channel 22b, the accumulator 35 and the pump 36 are provided in the order from the side of the first sub-flow channels 22a.

[0023] Pump 36 is driven by motor 37 and draws brake fluid from the first sub-flow passages 22a and pushes it toward the main flow passage 21. Pump 36 is a reciprocating plunger pump. Specifically, the plunger of pump 36 is intermittently pressed and reciprocated by an eccentric cam provided on the output shaft of motor 37. This performs pressure-feeding of the brake fluid by pump 36.

[0024] The supply flow channel 23 connects a portion of the main flow channel 21, which is closer to the main cylinder 13 than the first valve 33, to the suction side of the pump 36 at the secondary flow channel 22. The second valve 34 is provided on the supply flow channel 23.

[0025] The charging valve 31 is a solenoid valve that, for example, is opened in a de-energized state and closed in an energized state. The release valve 32 is a solenoid valve that, for example, is closed in a de-energized state and opened in an energized state. The first valve 33 is a solenoid valve that, for example, is opened in a de-energized state and closed in an energized state. The second valve 34 is a solenoid valve that, for example, is closed in a de-energized state and opened in an energized state. By controlling the operation of these valves and the motor 37, the braking force generated at each wheel 17 is controlled.

[0026] For example, in a normal case where the later-mentioned anti-lock brake control or vehicle dynamics control, etc., is not performed, the charge valve 31 is opened, the release valve 32 is closed, the first valve 33 is opened, and the second valve 34 is closed. As a result, the brake fluid is in a state where it flows from the master cylinder 13 to the wheel cylinders of the brake devices 16 only via the main flow passage 21 without the intermediary of the sub-flow passage 22 and the supply flow passage 23. When the brake pedal 11 is depressed in this state, the piston of the master cylinder 13 is compressed, and the fluid pressure of the brake fluid at the wheel cylinders increases, thereby imparting braking force to the wheels 17.

[0027] Anti-lock brake control is the control for preventing the wheels 17 from locking. For example, when anti-lock brake control is performed, first the charge valve 31 is closed, the release valve 32 is opened, the first valve 33 is opened, and the second valve 34 is closed. This stops the flow of brake fluid between the main flow passage 21 and the wheel cylinders of the brake devices 16, and the brake fluid is placed in a state where it can flow from the wheel cylinders into the sub-flow passage 22. Therefore, the brake fluid flows from the wheel cylinders into the accumulator 35, and the fluid pressure of the brake fluid at the wheel cylinder decreases, thereby reducing the braking force applied to the wheels 17. The brake fluid flowing into the accumulator 35 is returned to the main flow passage 21 via the sub-flow passage 22 by driving the pump 36.

[0028] By closing both the charge valve 31 and the release valve 32 from the above-mentioned state, the flow of brake fluid between the main flow passage 21, the sub-flow passage 22, and the wheel cylinders is stopped, and the brake fluid pressure at the wheel cylinders is maintained, thereby maintaining the braking force applied to the wheels 17. Then, by opening the charge valve 31 and closing the release valve 32, the flow of brake fluid between the main flow passage 21 and the wheel cylinders is restarted, and the brake fluid pressure at the wheel cylinders increases, thereby increasing the braking force applied to the wheels 17.

[0029] Vehicle dynamics control is the control for stabilizing the behavior of the vehicle. Vehicle dynamics control appropriately controls the driving force and braking force of the vehicle. For example, when the vehicle is decelerated by a braking operation other than the brake application during vehicle dynamics control, 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. This causes the brake fluid to flow from the master cylinder 13 to the wheel cylinders of the braking devices 16 via the supply flow passage 23 and the sub-flow passage 22. By driving the pump 36 in this state, the fluid pressure of the brake fluid at the wheel cylinders is increased, and the braking force for braking the wheels 17 is generated.

[0030] The fluid pressure control unit 15 controls the driving of the pump 36, as mentioned above. When the pump 36 is driven, pressure pulsation occurs, which is a phenomenon of the pulsating fluid pressure of the brake fluid in the flow channel in the fluid pressure control unit 15. The sound generated by this pressure pulsation may be perceived as noise by vehicle occupants and may cause a reduction in comfort. Therefore, a damping device 100 for damping the pressure pulsation is provided on the fluid pressure control unit 15.

[0031] The damping device 100 is provided on the downstream side of the pump 36 at the bypass flow passage 22 (specifically, at the second bypass flow passage 22b). The damping device 100 has an inlet port P1 and an outlet port P2. The inlet port P1 is connected to the pressure side of the pump 36. The inlet port P1 is connected to the outlet port P2. Therefore, the brake fluid pushed by the pump 36 flows into the damping device 100 via the inlet port P1, passes through the interior of the damping device 100, and then flows out of the damping device 100 via the outlet port P2. <Aufbau der Dämpfungsvorrichtung>

[0032] The structure of the damping device 100 according to the embodiment of the present invention will be described with reference to Fig. 2 explained.

[0033] Fig. 2 is a sectional view showing the schematic structure of the damping device 100. The damping device 100 according to Fig. 2, however, represents only one example of the damping device according to the invention. The example according to Fig. 2 with various additional modifications also falls under the damping device according to the invention, as mentioned later.

[0034] In the Fig. 2 and the later mentioned Fig. 3 to Fig. 5, the damper device 100 is illustrated such that the axial direction of its housing 101 corresponds to the left-right direction, with a first port PO1 connected to the inlet port P1 positioned on the left side in the axial direction, and second ports PO2 connected to the outlet port P2 positioned on the right side in the axial direction. Hereinafter, the left-right direction, which corresponds to the axial direction of the housing 101, is also simply referred to as the axial direction. The first port PO1 side means the side facing the first port PO1 in the axial direction or the upstream side in the flow direction of the brake fluid directed from the first port PO1 to the second ports PO2.The second opening PO2 side means the side facing the second openings PO2 in the axial direction or the downstream side in the flow direction of the brake fluid directed from the first opening PO1 to the second openings PO2.

[0035] The damping device 100 is provided with a housing 101, a first cover 111, a second cover 112, a third cover 113, a fourth cover 114, a fifth cover 115, a first piston 121, a second piston 122, a third piston 123, a first sealing element 131, second sealing elements 132, a third sealing element 133, a first biasing element 141, a second biasing element 142, a third biasing element 143, a fourth biasing element 144, a fifth biasing element 145, a first valve body 151, a second valve body 152 and a projecting element 161, as shown in Fig. 2 shown.

[0036] The housing 101 is formed, for example, in the shape of a roller with a hollow space inside. The axial direction of the housing 101 corresponds to the left-right direction. An internal space is formed in the housing 101, which penetrates from the left end face to the right end face. The internal space of the housing 101 includes a first hole part 101a and a second hole part 101b. The first hole part 101a and second hole part 101b each have a cylindrical shape and are arranged coaxially with the central axis of the housing 101. The first hole part 101a and second hole part 101b continue in this order from the left. The diameter of the second hole part 101b is smaller than that of the first hole part 101a.

[0037] The third cover 113 is fitted into the first hole portion 101a. The third cover 113 is substantially disc-shaped. At the left end of the outer peripheral surface of the third cover 113, the diameter is radially expanded outward. The portion of the third cover 113 whose diameter is radially expanded outward is fitted into the first hole portion 101a.

[0038] The fourth cover 114 is fitted into the second hole part 101b. The fourth cover 114 is substantially cylindrical. The fourth cover 114 has a first cylindrical part 114a and a second cylindrical part 114b. The first cylindrical part 114a and the second cylindrical part 114b each have a cylindrical shape and are arranged coaxially with each other. The first cylindrical part 114a and the second cylindrical part 114b continue in this order from the right. The outer diameter of the second cylindrical part 114b is smaller than the outer diameter of the first cylindrical part 114a. The first cylindrical part 114a is fitted into the right end of the second hole part 101b. The outer peripheral surface of the second cylindrical part 114b is spaced radially from the inner peripheral surface of the second hole part 101b. In the center of the left surface of the second roller part 114b, a recessed part 114c is formed.The recessed portion 114c has a cylindrical shape arranged coaxially with the second roller portion 114b. A base portion 161b of the later-mentioned protruding member 161 is fitted into the recessed portion 114c.

[0039] The first opening PO1 is formed between the third cover 113 and the fourth cover 114 in the peripheral wall portion of the housing 101. The first opening PO1 is connected to the second hole portion 101b. The right surface of the third cover 113, the left surface of the fourth cover 114, and the inner peripheral surface of the second hole portion 101b of the housing 101 define the first liquid chamber S1. That is, the third cover 113 covers the first liquid chamber S1 from its left side. The fourth cover 114 covers the first liquid chamber S1 from its right side. In other words, the left surface of the fourth cover 114 forms the right wall surface of the first liquid chamber S1. The first liquid chamber S1 has a substantially cylindrical shape. The first liquid chamber S1 is connected to the inlet port P1 via the first opening PO1.

[0040] A second liquid chamber S2 is defined by the inner peripheral surface of the first roller portion 114a of the fourth cover 114. The second liquid chamber S2 is connected to the recessed portion 114c via a connecting hole 114d. The recessed portion 114c, the connecting hole 114d, and the second liquid chamber S2 continue in this order from the left and are arranged coaxially with each other. The second liquid chamber S2 is connected to the first liquid chamber S1 via the connecting hole 114d.

[0041] The second cover 112 is fitted to the right end of the inner peripheral surface of the first roller part 114a of the fourth cover 114. The second cover 112 is formed substantially in the shape of a disc having the second openings PO2. The second openings PO2 are connected to the outlet port P2. The second openings PO2 are arranged radially outward from the center of the second cover 112. In the example according to Fig. 2, several second openings PO2 are provided. However, the number of second openings PO2 can also be 1.

[0042] At the right end of the inner peripheral surface of the first roller part 114a of the fourth cover 114, the diameter is expanded. The second cover 112 is fitted into the portion of the inner peripheral surface of the first roller part 114a whose diameter is expanded. Thus, the second liquid chamber S2 is partitioned with the left surface of the second cover 112. That is, the second cover 112 covers the second liquid chamber S2 from its right side. In other words, the left surface of the second cover 112 forms the right wall surface of the second liquid chamber S2. The second liquid chamber S2 is connected to the outlet port P2 via the second openings P02.

[0043] 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 outer peripheral surface of the first piston 121 can slide on the inner peripheral surface of the second hole portion 101b. Therefore, the first piston 121 is provided slidably in the axial direction in the first liquid chamber S1. The first piston 121 is arranged on the left side of the first opening PO1 in the first liquid chamber S1. That is, the first piston 121 is arranged on the side opposite the second openings PO2, relative to the first opening PO1, in the first liquid chamber S1.

[0044] An annular groove 121a is formed on the outer peripheral surface of the first piston 121. The annular groove 121a extends in the circumferential direction of the first piston 121. The first sealing element 131 is fitted into the annular groove 121a. The first sealing element 131 is, for example, an O-ring. The first sealing element 131 is pressed against the inner peripheral surface of the second hole part 101b. As a result, the gap between the outer peripheral surface of the first piston 121 and the inner peripheral surface of the second hole part 101b is sealed in a fluid-tight manner.

[0045] The first piston 121 is biased to the right by the first biasing element 141. The first biasing element 141 is, for example, an elastic component such as a spring, etc. The first biasing element 141 is arranged between the first piston 121 and the third cover 113. One end of the first biasing element 141 (the right end of which is Fig. 2) abuts against a recessed portion 121b of the first piston 121. The recessed portion 121b is provided in the center of the left surface of the first piston 121. The other end of the first biasing member 141 (the left end of which is in Fig. 2) rests against the right surface of the third cover 113. The expansion and contraction direction of the first prestressing element 141 corresponds to the left-right direction. The first prestressing element 141 is in a contracted state relative to its natural length.

[0046] The second piston 122 is housed inside the second hole portion 101b. The second piston 122 has a substantially cylindrical shape. The second piston 122 is arranged coaxially with the central axis of the second hole portion 101b. The outer peripheral surface of the second piston 122 can slide on the inner peripheral surface of the second hole portion 101b. Therefore, the second piston 122 is provided slidably in the axial direction in the first liquid chamber S1. The second piston 122 is arranged on the right side of the first opening PO1 in the first liquid chamber S1. That is, the second piston 122 is arranged on the second opening PO2 side with respect to the first opening PO1 in the first liquid chamber S1.

[0047] Annular grooves 122a are formed on the outer peripheral surface of the second piston 122. The annular grooves 122a extend in the circumferential direction of the second piston 122. The second sealing element 132 is fitted into the annular groove 122a. The second sealing element 132 is, for example, an O-ring. The second sealing elements 132 are pressed against the inner peripheral surface of the second hole part 101b. As a result, the gap between the outer peripheral surface of the second piston 122 and the inner peripheral surface of the second hole part 101b is sealed in a liquid-tight manner. In the example according to Fig. 2, two annular grooves 122a are arranged at a distance in the axial direction, with the second sealing element 132 fitted into each annular groove 122a. However, the number of annular grooves 122a may also be 1 or 3 or more.

[0048] The second piston 122 is biased to the left by the second biasing element 142. The second biasing element 142 is, for example, an elastic component such as a spring, etc. The second biasing element 142 is arranged between the second piston 122 and the fourth cover 114. One end of the second biasing element 142 (the left end of which is Fig. 2) rests against the right end face of the second piston 122. The other end of the second preload element 142 (the right end of which is Fig. 2) rests against the left surface of the first roller part 114a of the fourth cover 114. The extension and contraction direction of the second biasing element 142 corresponds to the left-right direction. The second biasing element 142 is in a contracted state relative to its natural length.

[0049] A cavity 122b is formed on the second piston 122. The cavity 122b is a portion of the second piston 122 that is hollowed from left to right. The cavity 122b is hollowed from the left end surface of the second piston 122 to the right. The cavity 122b is arranged coaxially with the central axis of the housing 101. However, the cavity 122b does not need to be arranged coaxially with the central axis of the housing 101.

[0050] The fifth cover 115 is fitted to the left end of the inner peripheral surface of the cavity 122b. The fifth cover 115 is formed in the shape of a disc having a through-hole 115a in the center. The through-hole 115a penetrates the fifth cover 115 from left to right. At the left end of the inner peripheral surface of the cavity 122b, the diameter is enlarged. The fifth cover 115 is fitted into the portion of the inner peripheral surface of the cavity 122b whose diameter is enlarged. The space on the left side of the second piston 122 in the first fluid chamber S1 is connected to the cavity 122b via the through-hole 115a of the fifth cover 115.

[0051] A cavity 122c is formed on the second piston 122. The cavity 122c is a section of the second piston 122 that is hollowed from right to left. The cavity 122c is hollowed from the right end surface of the second piston 122 to the left. The cavity 122c is arranged coaxially with the central axis of the housing 101. However, the cavity 122c need not be arranged coaxially with the central axis of the housing 101.

[0052] The first cover 111 is fitted to the right end of the inner peripheral surface of the cavity 122c. The first cover 111 is formed in a substantially cylindrical shape. The outer peripheral surface of the first cover 111 has an expanded diameter at the right end. The expanded diameter portion of the outer peripheral surface of the first cover 111 is fitted into the right end of the inner peripheral surface of the cavity 122c. In this way, the first cover 111 covers the cavity 122c from its right side.

[0053] The cavity 122b and the cavity 122c are connected to each other via a first through-hole 122d. In this way, the first through-hole 122d penetrates the second piston 122 from left to right. The cavity 122b, the first through-hole 122d, and the cavity 122c continue in this order from the left and are arranged coaxially with each other. The inner diameter of the first through-hole 122d is smaller than the inner diameter of the cavity 122b and the inner diameter of the cavity 122c. In the example according to Fig. 2, the inner diameter of the cavity 122b is smaller than the inner diameter of the cavity 122c. However, the inner diameter of the cavity 122b may be equal to or larger than the inner diameter of the cavity 122c.

[0054] A plurality of fourth through holes 122e are formed on the second piston 122. The fourth through holes 122e penetrate the second piston 122 from left to right. In the example according to Fig. 2, the fourth through-holes 122e are arranged around the first through-hole 122d and extend from the right inner surface of the cavity 122b to the left inner surface of the cavity 122c. The inner diameter of the fourth through-hole 122e is, for example, approximately 0.4 mm - 0.5 mm in diameter. In the example according to Fig. 2, the fourth through-holes 122e extend in the axial direction. However, the shape of the fourth through-hole 122e is not particularly limited. The fourth through-hole 122e may, for example, also extend in a direction inclined to the axial direction or be bent or curved.

[0055] The plurality of fourth through-holes 122e are arranged at equal intervals in the circumferential direction of the second piston 122. However, the arrangement of the plurality of fourth through-holes 122e is not limited to this example. For example, the plurality of fourth through-holes 122e may also be arranged at uneven intervals in the circumferential direction. Furthermore, the number of fourth through-holes 122e may also be 1. The brake fluid can flow from the left side to the right side of the second piston 122 through the fourth through-holes 122e. In particular, even in the closed state of the later-mentioned second valve body 152, the brake fluid can flow from the left side to the right side of the second piston 122 through the fourth through-holes 122e. The fourth through-holes 122e are provided to increase a pressure pulsation reducing effect. The function of the fourth through-holes 122e will be mentioned later.

[0056] The second valve body 152 is provided in the cavity 122b and can open and close the left side of the first through-hole 122d. In an open state in which the second valve body 152 does not block the first through-hole 122d, the brake fluid can flow through the first through-hole 122d. This state corresponds to the open state of the second valve body 152 and the open state of the first through-hole 122d. In a closed state in which the second valve body 152 blocks the first through-hole 122d, the brake fluid cannot flow through the first through-hole 122d. This state corresponds to the closed state of the second valve body 152 and the closed state of the first through-hole 122d.

[0057] The second valve body 152 has, for example, a spherical shape. However, the shape of the second valve body 152 may be other than spherical. The fourth biasing element 144 is, for example, an elastic member such as a spring, etc. The fourth biasing element 144 is arranged between the fifth cover 115 and the second valve body 152. The extension and contraction direction of the fourth biasing element 144 corresponds to the left-right direction. The fourth biasing element 144 is in a contracted state relative to its natural length. Therefore, the second valve body 152 is biased to the right by the fourth biasing element 144.

[0058] The third piston 123 is housed in the cavity 122c. The third piston 123 is substantially cylindrical. The third piston 123 is arranged coaxially with the center axis of the cavity 122c. The outer peripheral surface of the third piston 123 can slide on the inner peripheral surface of the cavity 122c. Therefore, the third piston 123 is provided to slide axially in the cavity 122c.

[0059] An annular groove 123a is formed on the outer peripheral surface of the third piston 123. The annular groove 123a extends in the circumferential direction of the third piston 123. The third sealing element 133 is fitted into the annular groove 123a. The third sealing element 133 is, for example, an O-ring. The third sealing element 133 is pressed against the inner peripheral surface of the cavity 122c. This seals the gap between the outer peripheral surface of the third piston 123 and the inner peripheral surface of the cavity 122c in a fluid-tight manner.

[0060] The third piston 123 is biased to the left by the fifth biasing element 145. The fifth biasing element 145 is, for example, an elastic component such as a spring, etc. The fifth biasing element 145 is arranged between the third piston 123 and the first cover 111. One end of the fifth biasing element 145 (the left end of which is Fig. 2) abuts against a recessed portion 123b of the third piston 123. The recessed portion 123b is formed annularly along the inner peripheral edge of the third piston 123 on the right surface of the third piston 123. The other end of the fifth biasing member 145 (the right end of which is in Fig. 2) rests against a recessed portion 111a of the first cover 111. The recessed portion 111a is formed in a ring shape along the inner peripheral edge of the first cover 111 on the left surface of the first cover 111. The expansion and contraction direction of the fifth biasing element 145 corresponds to the left-right direction. The fifth biasing element 145 is in a contracted state relative to its natural length.

[0061] A plurality of second through-holes 111b are formed on the first cover 111. The second through-holes 111b penetrate the first cover 111 from left to right. In the example according to Fig. 2, the second through-holes 111b extend from the recessed portion 111a to the right surface of the first cover 111. The inner diameter of the second through-hole 111b is, for example, approximately 0.4 mm - 0.5 mm in diameter. In the example according to Fig. 2, the second through-holes 111b extend in the axial direction. However, the extension of the second through-hole 111b is not subject to any particular restriction. The second through-hole 111b may, for example, also extend in a direction inclined to the axial direction or be bent or curved.

[0062] The plurality of second through-holes 111b are arranged at equal intervals in the circumferential direction of the first cover 111. However, the arrangement of the plurality of second through-holes 111b is not limited to this example. For example, the plurality of second through-holes 111b may also be arranged at uneven intervals in the circumferential direction. Furthermore, the number of second through-holes 111b may also be 1. The brake fluid can flow from the left side to the right side of the first cover 111 through the second through-holes 111b. The second through-holes 111b are provided to enhance a pressure pulsation reducing effect. The function of the second through-holes 111b will be mentioned later.

[0063] The protruding member 161 is provided to open and close the second valve body 152. The protruding member 161 is arranged on the right side of the second valve body 152. The protruding member 161 includes a protrusion 161a and a base portion 161b. The base portion 161b is substantially disc-shaped. The base portion 161b is fitted into the recessed portion 114c of the fourth cover 114. Therefore, the base portion 161b covers the left side of the connecting hole 114d. The protrusion 161a is connected to the base portion 161b. The protrusion 161a protrudes from the center of the base portion 161b to the left.

[0064] The projection 161a is arranged coaxially with the first cover 111, the third piston 123, and the first through-hole 122d. The projection 161a is inserted into the cavity in the center of the first cover 111 and the cavity in the center of the third piston 123. By moving the second piston 122 from the position shown in Fig. 2 to the right, the projection 161a is inserted into the first through-hole 122d, and thus the front end of the projection 161a can abut against the second valve body 152. By abutting the front end of the projection 161a against the second valve body 152, the position of the second valve body 152 is maintained. By moving the second piston 122 further to the right in this state, the second valve body 152 is placed in the open state. In this way, the projection 161a can be inserted into the first through-hole 122d and abut against the second valve body 152.

[0065] A third through-hole 161c is formed on the base part 161b. The third through-hole 161c penetrates the base part 161b from left to right. The inner diameter of the third through-hole 161c is approximately 0.4 mm - 0.5 mm in diameter, for example. The course of the third through-hole 161c is not particularly limited to the example according to Fig. 2. The number of branches of the third through-hole 161c and its arrangement may also be different from those in the example according to Fig. 2 distinguish.

[0066] The first valve body 151 is provided in the second fluid chamber S2 and can open and close the right side of the communication hole 114d. In an open state in which the first valve body 151 does not block the communication hole 114d, the brake fluid can flow through the communication hole 114d. This state corresponds to the open state of the first valve body 151 and the open state of the communication hole 114d. In a closed state in which the first valve body 151 blocks the communication hole 114d, the brake fluid cannot flow through the communication hole 114d. This state corresponds to the closed state of the first valve body 151 and the closed state of the communication hole 114d.

[0067] The first valve body 151 has a head portion 151a, a first stem portion 151b, and a second stem portion 151c. The head portion 151a is substantially hemispherical. The left side of the head portion 151a is a spherical surface that can open and close the communication hole 114d. The first stem portion 151b extends rightward from the right surface of the head portion 151a. The second stem portion 151c extends rightward from the right surface of the first stem portion 151b. The outer diameter of the second stem portion 151c is smaller than the outer diameter of the first stem portion 151b. The sectional shape of the first stem portion 151b and second stem portion 151c is, for example, B. circular or polygonal, etc. The first shaft part 151b and second shaft part 151c are arranged coaxially with the central axis of the housing 101. A through hole 112a is formed in the center of the second cover 112, into which the second shaft part 151c is inserted.The third biasing element 143 is, for example, an elastic component such as a spring, etc. The third biasing element 143 is arranged between the second cover 112 and the first valve body 151. The extension and contraction direction of the third biasing element 143 corresponds to the left-right direction. The third biasing element 143 is in a contracted state relative to its natural length. Therefore, the first valve body 151 is biased to the left by the third biasing element 143. <Betrieb der Dämpfungsvorrichtung>

[0068] The operation of the damping device 100 according to the embodiment of the present invention will be explained with reference to Fig. 2 to Fig. 5 explained.

[0069] The above-mentioned Fig. 2 shows the damper device 100 in the normal state, where the pump 36 on the fluid pressure control unit 15 is not driven. In this case, the first piston 121 is biased to the right by the first biasing element 141 and positioned on the rightmost side in the movement range. The second piston 122 is biased to the left by the second biasing element 142 and positioned on the leftmost side in the movement range. The right end surface of the first piston 121 and the left end surface of the second piston 122 abut each other in the axial direction of the first port PO1. The second valve body 152 does not abut the projection 161a of the projecting member 161, is biased to the right by the fourth biasing element 144, and is therefore in the closed state. The first valve body 151 is biased to the left by the third biasing element 143 and is therefore in the closed state.

[0070] When the anti-lock brake control or vehicle dynamics control, etc., is performed at the fluid pressure control unit 15, the pump 36 is driven as mentioned above. If the pump 36 is in the state according to Fig. 2, the brake fluid flows into the damping device 100 via the first opening PO1, thereby increasing the pressure of the space between the first piston 121 and the second piston 122 in the first fluid chamber S1. As a result, the first piston 121 is moved to the left first. For example, because the elastic modulus of the first preload element 141 is smaller than the elastic modulus of the second preload element 142, the first piston 121 is moved earlier than the second piston 122. The elastic modulus is a physical value that represents the difficulty of deformation and is also referred to as the spring constant, elastic constant, or elastic coefficient.

[0071] Fig. Fig. 3 is a view showing a state in which the first piston 121 on the damping device 100 is displaced in comparison with that in the state of Fig. 2 is moved to the left. In the state according to Fig. 3, the pressure in the space between the first piston 121 and the second piston 122 is stored in the first liquid chamber S1. The pressure of the space between the first piston 121 and the second piston 122 then forces the first piston 121 to the left, thus increasing the pressure compared to the state shown in FIG. Fig. 2 is moved to the left. As the first piston 121 moves to the left, the first preload element 141 expands and contracts, eventually contracting. As a result, the force acting on the first piston 121 is absorbed by the first preload element 141. In this way, the pressure pulsation is dampened by the expansion and contraction of the first preload element 141 in accordance with the movement of the first piston 121.

[0072] Fig. Fig. 4 is a view showing a state in which the second piston 122 on the damping device 100 is displaced in comparison with that in the state of Fig. 3 is moved to the right. In the state according to Fig. 4, the pressure in the space between the first piston 121 and the second piston 122 is stored in the first liquid chamber S1. The pressure of the space between the first piston 121 and the second piston 122 in the first liquid chamber S1 then presses the second piston 122 to the right and thus, compared to the state according to Fig. 3 to the right. As the second piston 122 moves to the right, the second biasing element 142 expands and contracts, eventually contracting. As a result, the force acting on the second piston 122 is absorbed by the second biasing element 142. In this way, the pressure pulsation is dampened by the expansion and contraction of the second biasing element 142 in accordance with the movement of the second piston 122.

[0073] In condition according to Fig. 4, the front end of the projection 161a of the projecting element 161 abuts against the second valve body 152. As a result, the movement of the second valve body 152 to the right is restricted by the projection 161a. The second valve body 152, which is in a state of abutment with the projection 161a, is therefore not moved to the right even if the second piston 122 is moved to the right. Therefore, the position of the second valve body 152 is maintained at the position of abutment with the projection 161a, so that the second valve body 152 is in a state of abutment with the projection 161a, compared to that in the state according to Fig. 3 is moved to the left relative to the second piston 122. The second valve body 152 is therefore spaced from the first through-hole 122d. Therefore, the second valve body 152 is in the open state, and the brake fluid can flow through the first through-hole 122d.

[0074] According to the inflow of the brake fluid into the cavity 122c through the first through-hole 122d, the pressure in the space on the left side of the third piston 123 is stored in the cavity 122c. By the pressure of the space on the left side of the third piston 123 in the cavity 122c, the third piston 123 is then pressed to the right and thus compared to that in the state according to Fig. 3 is moved to the right relative to the second piston 122. As the third piston 123 moves to the right, the fifth biasing element 145 is ultimately contracted by expanding and contracting. As a result, the force acting on the third piston 123 is absorbed by the fifth biasing element 145. In this way, the pressure pulsation is also dampened by the expansion and contraction of the fifth biasing element 145 in accordance with the movement of the third piston 123.

[0075] Here, a small gap exists between the inner peripheral surface of the third piston 123 and the projection 161a of the projecting member 161. Therefore, the brake fluid in the concavity 122c flows from the left side of the third piston 123 to the right side thereof. The brake fluid discharged to the right side from the third piston 123 is discharged through the second through-holes 111b of the first cover 111 into the space on the right side of the second piston 122 in the first fluid chamber S1. The inner diameter of the second through-hole 111b is small, so that the brake fluid flowing through the second through-holes 111b is subjected to great resistance. Therefore, the pressure pulsation is also dampened by the brake fluid flowing through the second through-holes 111b.

[0076] The second piston 122 is also formed with the fourth through-holes 122e, as mentioned above. Brake fluid can flow from the concavity 122b into the concavity 122c through the fourth through-holes 122e of the second piston 122. Specifically, even in a state where the front end of the protrusion 161a of the protruding member 161 is not abutting against the second valve body 152 and the second valve body 152 is therefore in the closed state, brake fluid is supplied from the concavity 122b into the concavity 122c through the fourth through-holes 122e. The inner diameter of the fourth through-hole 122e is small, so that the brake fluid flowing through the fourth through-holes 122e faces a large resistance. Therefore, the pressure pulsation is also dampened by the brake fluid flowing through the fourth through-holes 122e.

[0077] Fig. Fig. 5 is a view showing a state in which the second piston 122 on the damping device 100 is displaced in comparison with that in the state of Fig. 4 is moved to the right. In the state according to Fig. 5, the second piston 122 is in comparison with the one in the state according to Fig. 4 is moved further to the right. The brake fluid, which is delivered into the space on the right side by the second piston 122 in the first fluid chamber S1, is delivered through the third through-hole 161c of the base part 161b of the protruding element 161 into the connecting hole 114d. This increases the pressure of the connecting hole 114d, thereby pressing and moving the first valve body 151 to the right. Therefore, the first valve body 151 is spaced from the connecting hole 114d and placed in the open state, so that the brake fluid can flow through the connecting hole 114d, as shown in Fig. 5. The brake fluid therefore flows through the connecting hole 114d and flows out of the second fluid chamber S2 via the second openings PO2.

[0078] The inner diameter of the third through-hole 161c is small, so the brake fluid flowing through the third through-hole 161c encounters a large resistance. Therefore, the pressure pulsation is also dampened by the brake fluid flowing through the third through-hole 161c.

[0079] The first valve body 151 may abut against the second cover 112 when the first valve body 151 is in the open state, as shown in Fig. 5. In the example according to Fig. 5, the first shaft portion 151b and second shaft portion 151c of the first valve body 151 are moved along the central axis of the housing 101. As mentioned above, the through-hole 112a is formed adjacent to the second openings PO2 on the second cover 112. The inner diameter of the through-hole 112a is larger than the outer diameter of the second shaft portion 151c and smaller than the outer diameter of the first shaft portion 151b. Therefore, the step surface between the first shaft portion 151b and the second shaft portion 151c of the first valve body 151 can abut against the second cover 112. This stabilizes the posture of the first valve body 151 without causing vibration of the first valve body 151, even when the first valve body 151 is set in the open state. <Vorteile der Dämpfungsvorrichtung>

[0080] The advantages of the damping device 100 according to the embodiment of the present invention will be explained.

[0081] The damping device 100 is provided with the first liquid chamber S1, which is connected to the inlet port P1 via the first opening PO1, the second liquid chamber S2, which is connected to the first liquid chamber S1 via the connecting bore 114d and to the outlet port P2 via the second openings PO2, the first piston 121, which is slidably provided on the first liquid chamber S1 and arranged on the side opposite the second openings PO2 with respect to the first opening PO1, the first biasing element 141 for biasing the first piston 121 to the side of the first opening PO1, the second piston 122, which is slidably provided on the first liquid chamber S1 and arranged on the side of the second openings PO2 with respect to the first opening PO1,the second biasing element 142 for biasing the second piston 122 toward the first opening PO1 side, the first valve body 151 provided at the second fluid chamber S2 and capable of opening and closing the side of the connecting bore 114d facing the second openings PO2, and the third biasing element 143 for biasing the first valve body 151 toward the first opening PO1 side.

[0082] As a result, when the pump 36 is driven, the pressure in the space between the first piston 121 and the second piston 122 is stored in the first liquid chamber S1. During this time, the first biasing member 141 is gradually contracted in accordance with the movement of the first piston 121, thereby absorbing the energy of the pressure increase. The second biasing member 142 is gradually contracted in accordance with the movement of the second piston 122, thereby absorbing the energy of the pressure increase. As a result, the pressure increase rate on the side closer to the second orifices PO2 than the second piston 122 becomes smaller than the pressure increase rate on the side closer to the first orifice PO1 than the second piston 122.When the second piston 122 moves to the first port PO1 side by reducing the pressure on the first port PO1 side, the first biasing member 141 and the second biasing member 142 are gradually expanded, whereby the decreasing speed of the pressure on the side closer to the second ports PO2 than the second piston 122 becomes slower than the decreasing speed of the pressure on the side closer to the first port PO1 than the second piston 122. This allows the pressure pulsation on the second port PO2 side to be dampened compared to the pressure pulsation on the first port PO1 side. By increasing the pressure in the communication hole 114d, the first valve body 151 is brought into the open state, and thus the brake fluid can flow out appropriately from the second fluid chamber S2 via the second ports PO2.In this way, the pressure pulsation of the fluid pressure control unit 15 can be dampened by the damping device 100.

[0083] The damping device 100 is preferably provided with the first through-hole 122d provided on the second piston 122 and penetrating from the first port PO1 side to the second port PO2 side, the second valve body 152 capable of opening and closing the first port PO1 side of the first through-hole 122d, the fourth biasing member 144 for biasing the second valve body 152 toward the second port PO2 side, and the protruding member 161 disposed on the second port PO2 side with respect to the second valve body 152, insertable into the first through-hole 122d, and having the projection 161a capable of abutting against the second valve body 152.As a result, during the movement of the second piston 122 toward the second ports PO2 side by the drive of the pump 36, the second valve body 152 can be opened by the projection 161a of the projecting member 161. Therefore, the brake fluid can be properly discharged to the side closer to the second ports PO2 than the second piston 122.

[0084] The damping device 100 is preferably provided with the concave 122c formed on the second piston 122 from the second port PO2 side to the first port PO1 side and connected to the first through-hole 122d, the third piston 123 slidably provided on the concave 122c, and the fifth biasing member 145 for biasing the third piston 123 toward the first port PO1 side. Thus, the movement of the third piston 123 occurs alongside the movements of the first piston 121 and the second piston 122 when driving the pump 36. The fifth biasing member 145 expands and contracts in accordance with the movement of the third piston 123, thereby damping the pressure pulsation. Therefore, the pressure pulsation can be dampened more effectively.

[0085] The damping device 100 is preferably provided with the first cover 111 for covering the concavity 122c from the second opening PO2 side, and at least one second through-hole 111b penetrating from the first opening PO1 side to the second opening PO2 side is formed on the first cover 111. This allows the pressure pulsation to be dampened by the brake fluid flowing through the second through-hole 111b.

[0086] In the damping device 100, a plurality of second through-holes 111b are preferably formed on the first cover 111, wherein the plurality of second through-holes 111b are arranged at equal intervals in the circumferential direction of the first cover 111. This homogenizes the flow field of the brake fluid around the first cover 111 in the circumferential direction. Therefore, the brake fluid can flow smoothly in the damping device 100.

[0087] In the damping device 100, the protruding element 161 preferably includes the base part 161b, which is connected to the projection 161a and covers the side of the connecting bore 114d facing the first opening PO1. The third through-hole 161c is formed on the base part 161b and penetrates from the first opening PO1 side to the second opening PO2 side. This allows the pressure pulsation to be dampened by the brake fluid flowing through the third through-hole 161c.

[0088] In the damping device 100, at least one fourth through-hole 122e is preferably formed on the second piston 122, penetrating from the first port PO1 side to the second port PO2 side. This allows pressure pulsation to be dampened even when brake fluid flows through the fourth through-hole 122e. Here, assume a situation where the second piston 122 seizes and cannot move. In this situation, brake fluid can flow through the fourth through-hole 122e from the second piston 122 side facing the first port PO1 to the second port PO2 side of the second piston 122. Therefore, excessive pressure increase in the space in the first fluid chamber S1, which is closer to the first port PO1 than the second piston 122, is suppressed.

[0089] In the damper device 100, a plurality of fourth through-holes 122e are preferably formed on the second piston 122, wherein the plurality of fourth through-holes 122e are arranged at equal intervals in the circumferential direction of the second piston 122. As a result, the force generated due to the flow of the brake fluid through the fourth through-holes 122e acts on the second piston 122 evenly in the circumferential direction. Therefore, the inclination of the second piston 122 toward the sliding direction is suppressed by the force acting on the second piston 122 due to the flow of the brake fluid through the fourth through-holes 122e.

[0090] The damping device 100 is preferably provided with the second cover 112 for covering the second fluid chamber S2 from the second opening PO2 side, and the first valve body 151 can abut against the second cover 112. This stabilizes the posture of the first valve body 151 without causing vibration of the first valve body 151 when the first valve body 151 is in the open state. Therefore, the opening and closing operation of the first valve body 151 can be made smooth.

[0091] In the damping device 100, the elastic modulus of the first preload element 141 is preferably smaller than the elastic modulus of the second preload element 142. This can suitably realize that the first piston 121 is moved earlier than the second piston 122. Therefore, the occurrence of the situation in which the first piston 121 is not moved and the energy is not absorbed by the first preload element 141 can be suppressed.

[0092] So far, the preferred embodiment of the present invention has been explained with reference to the accompanying drawings. However, it should be understood that the present invention is not limited to the above-mentioned embodiment. Needless to say, various altered or modified examples within the scope of the claims are also within the technical scope of the present invention.

[0093] In the above, the structure of the damping device 100 is based on the Fig. 2. The example according to Fig. 2 with various additional modifications also falls under the damping device according to the invention.

[0094] For example, the sliding direction of the first piston 121 and the second piston 122 may also differ from the axial direction of the housing 101. For example, if the center axis of the first fluid chamber S1 is not coaxial with the housing 101, the sliding direction of the first piston 121 and the second piston 122 is a direction different from the axial direction of the housing 101.

[0095] For example, the sectional shape of the first fluid chamber S1, as well as the first piston 121 and the second piston 122, perpendicular to the sliding direction, does not need to be circular. This sectional shape can also be elliptical, polygonal, etc. In this case, too, each circumferential direction of the first piston 121 and the second piston 122 corresponds to the direction along each outer peripheral edge of the first piston 121 and the second piston 122 and represents the direction around each central axis of the first piston 121 and the second piston 122.

[0096] For example, the sectional shape of the first cover 111, which is perpendicular to the axial direction, does not have to be circular. This sectional shape can also be elliptical or polygonal, etc. In this case, too, the circumferential direction of the first cover 111 corresponds to the direction along the outer peripheral edge of the first cover 111 and represents the direction around the central axis of the first cover 111.

[0097] For example, the example according to Fig. 2, in which the second through-holes 111b are omitted, fall under the damping device of the invention. Even if the second through-holes 111b are omitted, a small gap exists between the inner peripheral surface of the first cover 111 and the projection 161a of the projecting member 161, through which the brake fluid can flow from the left side of the first cover 111 to the right side.

[0098] For example, the example according to Fig. 2, in which the fourth through holes 122e are omitted, fall under the damping device according to the invention. If the fourth through holes 122e are omitted, grooves extending in the axial direction may also be provided on the inner peripheral surface of the second hole part 101b, for example, so that the brake fluid can flow through these grooves from the left side to the right side of the second piston 122.

[0099] For example, the shape of the first valve body 151 in the example according to Fig. 2 may be replaced by another shape, such as spherical, etc., and the first valve body 151 may be designed so that it does not abut against the second cover 112.

[0100] For example, the structure of the second piston 122 in the example according to Fig. 2. For example, the third piston 123 can be moved away from the second piston 122 in the example according to Fig. 2 may be omitted. For example, the first through hole 122d, the second valve body 152, the fourth biasing element 144 and the projecting element 161 may also be different from the example according to Fig. 2 can be omitted. In this case, for example, grooves extending in the axial direction can also be provided on the inner peripheral surface of the second hole part 101b so that the brake fluid can flow through these grooves from the left side to the right side of the second piston 122. For example, the second piston 122 can also abut against the first valve body 151, which can therefore be pressed by the second piston 122 and thus brought into the open state. [List of reference symbols] 1 braking system 11 Brake pedal 12 amplifiers 13 master cylinders 14 storage containers 15 Fluid pressure control unit 16 Braking device 17 wheels 21 Main flow channel 22 Bypass channel 23 Supply flow channel 31 Charging valve 32 release valve 33 First valve 34 Second valve 35 accumulator 36 Pump 37 Engine 100 Damping device 101 housings 111 First cover 111b Second through hole 112 Second cover 113 Third cover 114 Fourth cover 114d connecting hole 115 Fifth cover 121 First piston 122 Second piston 122c cavity 122d First through hole 123 Third piston 131 First sealing element 132 Second sealing element 133 Third sealing element 141 First prestressing element 142 Second prestressing element 143 Third prestressing element 144 Fourth prestressing element 145 Fifth prestressing element 151 First valve body 152 Second valve body 161 Projecting element 161a projection 161b Base part 161c Third through hole P1 inlet connection P2 outlet connection PO1 First Opening PO2 Second opening S1 First liquid chamber S2 Second liquid chamber QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2010-052519 A

[0003]

Claims

[1] Damping device (100) provided on a fluid pressure control unit (15) for controlling braking forces generated on wheels (17), having an inlet port (P1) connected to the pressure side of a pump (36) and an outlet port (P2) connected to the inlet port (P1) and damping the pressure pulsation, wherein the damping device with a first liquid chamber (S1) connected to the inlet port (P1) via a first opening (PO1), a second liquid chamber (S2) connected to the first liquid chamber (S1) via a connecting bore (114d) and connected to the outlet port (P2) via second openings (PO2), a first piston (121) slidably provided on the first liquid chamber (S1) and arranged on the side opposite the second openings (PO2) with respect to the first opening (PO1) in the first liquid chamber (S1), a first biasing element (141) for biasing the first piston (121) to the side of the first opening (PO1), a second piston (122) slidably provided on the first liquid chamber (S1) and arranged on the side of the second openings (PO2) relative to the first opening (PO1) in the first liquid chamber (S1), a second biasing element (142) for biasing the second piston (122) towards the side of the first opening (PO1), a first valve body (151) provided on the second liquid chamber (S2) and capable of opening and closing the side of the connecting bore (114d) facing the second openings (PO2), and a third biasing element (143) for biasing the first valve body (151) to the side of the first opening (PO1) is provided. [2] Damping device according to claim 1, which is provided with a first through-hole (122d) provided on the second piston (122) and penetrating from the side of the first opening (PO1) to the side of the second openings (PO2), a second valve body (152) which can open and close the side of the first through-hole (122d) facing the first opening (PO1), a fourth biasing element (144) for biasing the second valve body (152) to the side of the second openings (PO2) and a projecting element (161) arranged on the side of the second openings (PO2) with respect to the second valve body (152), which can be inserted into the first through-hole (122d) and has a projection (161a) which can abut against the second valve body (152), is provided. [3] Damping device according to claim 2, which is provided with a cavity (122c) formed on the second piston (122) from the side of the second openings (PO2) to the side of the first opening (PO1) and connected to the first through hole (122d), a third piston (123) slidably provided on the cavity (122c), and a fifth biasing element (145) for biasing the third piston (123) toward the side of the first opening (PO1) is provided. [4] Damping device according to claim 3, which is provided with a first cover (111) for covering the cavity (122c) from the side of the second openings (PO2) is provided, wherein at least one second through-hole (111b) penetrating from the side of the first opening (PO1) to the side of the second openings (PO2) is formed on the first cover (111). [5] The damping device according to claim 4, wherein a plurality of second through holes (111b) are formed on the first cover (111), the plurality of second through holes (111b) being arranged at equal intervals in the circumferential direction of the first cover (111). [6] Damping device according to claim 2, wherein the projecting element (161) has a base part (161b) which is connected to the projection (161a) and covers the side of the connecting bore (114d) facing the first opening (PO1), wherein a third through-hole (161c) penetrating from the side of the first opening (PO1) to the side of the second openings (PO2) is formed on the base part (161b). [7] The damping device according to claim 1, wherein at least one fourth through-hole (122e) penetrating from the first opening (PO1) side to the second opening (PO2) side is formed on the second piston (122). [8] Damping device according to claim 7, in which a plurality of fourth through holes (122e) are formed on the second piston (122), wherein the plurality of fourth through holes (122e) are arranged at equal intervals in the circumferential direction of the second piston (122). [9] Damping device according to claim 1, which is provided with a second cover (112) for covering the second liquid chamber (S2) from the side of the second openings (PO2) is provided, wherein the first valve body (151) can abut against the second cover (112). [10] Damping device according to claim 1, wherein the elastic modulus of the first prestressing element (141) is smaller than the elastic modulus of the second prestressing element (142). [11] Fluid pressure control unit with a damping device (100) according to one of claims 1 to 10. [12] A braking system comprising a fluid pressure control unit (15) according to claim 11.

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