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 a second opening, a first piston slidably provided at the first fluid chamber, a first biasing element for biasing the first piston toward the first opening side, a valve body,which is provided on the second fluid chamber and can open and close the side of the connecting bore facing the second opening, a second biasing element for biasing the valve body towards the side of the first opening and a projection which is provided on the side of the first piston facing the second opening, can be inserted into the connecting bore and can abut against the valve body.

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 a second opening, a first piston which is slidably provided on the first fluid chamber, a first biasing element for biasing the first piston to the side of the first opening, a valve body,which is provided on the second fluid chamber and can open and close the side of the connecting bore facing the second opening, a second biasing element for biasing the valve body towards the side of the first opening and a projection which is provided on the side of the first piston facing the second opening, can be inserted into the connecting bore and can abut against the valve body.

[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 a first embodiment of the present invention. [ Fig. 2] is a sectional view showing the schematic structure of a damping device according to the first embodiment of the present invention. [ Fig. 3] is a view of the damping device according to the first 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 right. [ Fig. 4] is a view of the damping device according to the first embodiment of the present invention, illustrating a state in which the first piston is displaced compared with that in the state of Fig. 3 is moved to the right. [ Fig. 5] is a sectional view showing the schematic structure of a damping device according to a second embodiment of the present invention. [ Fig. 6] is a view of the damping device according to the second embodiment of the present invention, illustrating a state in which a second piston is displaced compared with that in the state of Fig. 5 is moved to the right. [ Fig. 7] is a view of the damping device according to the second embodiment of the present invention, illustrating a state in which a first piston is displaced compared with that in the state of Fig. 6 is moved to the right. [ Fig. 8] is a view of the damping device according to the second embodiment of the present invention, illustrating a state in which the first piston is displaced compared with that in the state of Fig. 7 moved to the right. [Embodiments of the invention]

[0010] Preferred embodiments of the present invention will be explained in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. given in the embodiments 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. <Erste Ausführungsform>

[0012] A first embodiment of the present invention is described with reference to Fig. 1 to Fig. 4 explained. (Structure of a braking system)

[0013] The structure of a brake system 1 according to the first embodiment of the present invention will be described with reference to Fig. 1 explained.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 braking 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 given 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.

[0029] 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.

[0030] Vehicle dynamics control is the control for stabilizing the behavior of the vehicle. In vehicle dynamics control, the driving force and braking force of the vehicle are appropriately controlled. For example, when the vehicle is decelerated by braking other than by applying the brakes 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.

[0031] 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.

[0032] 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. (Structure of the damping device)

[0033] The details of the structure of the damping device 100 according to the first embodiment of the present invention will be explained with reference to Fig. 2 explained.

[0034] 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.

[0035] In the Fig. 2 and the later mentioned Fig. 3 and Fig. 4, 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 a second port 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 port PO2.The second port PO2 side means the side facing the second port PO2 in the axial direction or the downstream side in the flow direction of the brake fluid directed from the first port PO1 to the second port PO2.

[0036] The damping device 100 is provided with a housing 101, a first cover 111, a second cover 112, a third cover 113, a first piston 121, a first sealing element 131, a first biasing element 141, a second biasing element 142 and a valve body 151, as shown in Fig. 2 shown.

[0037] 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, a second hole part 101b, and a third hole part 101c. The first hole part 101a, second hole part 101b, and third hole part 101c each have a cylindrical shape and are arranged coaxially with the central axis of the housing 101. The first hole part 101a, second hole part 101b, and third hole part 101c 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. The diameter of the third hole part 101c is larger than that of the second hole part 101b.

[0038] The third cover 113 is fitted into the first hole portion 101a. The third cover 113 is formed in the shape of a disc having the first opening PO1 in the center. The first opening PO1 is connected to the inlet port P1. The first opening PO1 is arranged coaxially with the center axis of the housing 101. However, the first opening PO1 need not be arranged coaxially with the center axis of the housing 101.

[0039] The first cover 111 is fitted into the third hole portion 101c. The first cover 111 is substantially cylindrical. At the right end of the outer peripheral surface of the first cover 111, the diameter is radially expanded outward. The portion of the first cover 111 whose diameter is radially expanded outward is fitted into the third hole portion 101c.

[0040] A first liquid chamber S1 is defined by the right surface of the third cover 113, the left 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 its left side. The first cover 111 covers the first liquid chamber S1 from its right side. In other words, the left surface of the first cover 111 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.

[0041] A second fluid chamber S2 is defined by the inner peripheral surface of the first cover 111. At the left end of the inner peripheral surface of the first cover 111, the diameter is reduced radially inward. This forms a connecting hole 111a in the center at the left end of the first cover 111. The second fluid chamber S2 is connected to the first fluid chamber S1 via the connecting hole 111a.

[0042] The second cover 112 is fitted to the right end of the inner peripheral surface of the first cover 111. The second cover 112 is formed substantially in the shape of a disc having the second opening PO2 in the center. The second opening PO2 is connected to the outlet port P2. The second opening PO2 is arranged coaxially with the central axis of the housing 101. However, the second opening PO2 need not be arranged coaxially with the central axis of the housing 101.

[0043] At the right end of the outer peripheral surface of the second cover 112, the diameter is expanded radially outward. The diameter is also expanded at the right end of the inner peripheral surface of the first cover 111. The portion of the outer peripheral surface of the second cover 112 whose diameter is expanded radially outward is fitted into the portion of the inner peripheral surface of the first cover 111 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 opening PO2.

[0044] The first piston 121 is received in the second hole portion 101b. The first piston 121 has a substantially cylindrical shape. The first piston 121 is arranged coaxially with the center axis of the second hole portion 101b. The first piston 121 includes a first cylindrical portion 121a, a second cylindrical portion 121b, and a projection 121c. The first cylindrical portion 121a, the second cylindrical portion 121b, and the projection 121c each have a cylindrical shape and are arranged coaxially with each other. The first cylindrical portion 121a, the second cylindrical portion 121b, and the projection 121c continue in this order from the left. The first cylindrical portion 121a, the second cylindrical portion 121b, and the projection 121c are smaller in outer diameter in this order. The outer peripheral surface of the first cylinder part 121a can slide on the inner peripheral surface of the second hole part 101b.Therefore, the first piston 121 is provided in the first liquid chamber S1 to be slidable in the axial direction.

[0045] An annular groove 121d is formed on the outer peripheral surface of the first cylinder portion 121a. The annular groove 121d extends in the circumferential direction of the first piston 121. The first sealing element 131 is fitted into the annular groove 121d. 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 portion 101b. As a result, the gap between the outer peripheral surface of the first cylinder portion 121a and the inner peripheral surface of the second hole portion 101b is sealed in a fluid-tight manner.

[0046] The first piston 121 is biased to the left 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 first cover 111. One end of the first biasing element 141 (the left end of which is Fig. 2) abuts a contact surface 121e provided on the right side of the first piston 121. The contact surface 121e is a right surface of the first cylinder part 121a (ie, a step surface between the first cylinder part 121a and the second cylinder part 121b). The other end of the first biasing element 141 (the right end of which is in Fig. 2) abuts a recessed portion 111b of the first cover 111. The recessed portion 111b is formed annularly along the peripheral edge of the connecting hole 111a. Therefore, the other end of the first biasing member 141 abuts the left periphery of the connecting hole 111a. The extension and contraction direction of the first biasing member 141 corresponds to the left-right direction. The first biasing member 141 is in a contracted state relative to its natural length.

[0047] A plurality of first through holes 121f are formed on the first piston 121. The first through holes 121f penetrate the first piston 121 from left to right. In the example according to Fig. 2, the first through holes 121f extend from the left surface of the first cylinder part 121a to the right surface of the second cylinder part 121b. The inner diameter of the first through hole 121f is, for example, approximately 0.4 mm - 0.5 mm in diameter. In the example according to Fig. 2, the first through-holes 121f extend in the axial direction. However, the extension of the first through-hole 121f is not subject to any particular restriction. For example, the first through-hole 121f may also extend in a direction inclined to the axial direction or be bent or curved.

[0048] The 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 uneven intervals in the circumferential direction. Furthermore, the number of first through-holes 121f may also be 1. The brake fluid can flow from the left side to the right side of the first piston 121 through the first through-holes 121f. The first through-holes 121f are provided to enhance a pressure pulsation reducing effect. The function of the first through-holes 121f will be mentioned later.

[0049] Also formed on the first cover 111 are a plurality of second through-holes 111c, which achieve the same effect as the first through-holes 121f. The second through-holes 111c penetrate the first cover 111 from left to right. In the example according to Fig. 2, the second through-holes 111c extend from locations of the recessed portion 111b that are radially inward from the location adjacent to the first biasing element 141 to the right surface of the first cover 111. The inner diameter of the second through-hole 111c is, for example, approximately 0.4 mm - 0.5 mm in diameter. In the example according to Fig. 2, the second through-holes 111c extend in the axial direction. However, the extension of the second through-hole 111c is not subject to any particular restriction. The second through-hole 111c may, for example, also extend in a direction inclined to the axial direction or be bent or curved.

[0050] The 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 uneven intervals in the circumferential direction. Furthermore, the number of second through-holes 111c 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 111c. The second through-holes 111c are provided to enhance a pressure pulsation reducing effect. The function of the second through-holes 111c will be mentioned later.

[0051] The valve body 151 is provided at the second fluid chamber S2 and can open and close the right side of the communication hole 111a. In an open state, in which the valve body 151 does not block the communication hole 111a, the 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 a closed state, in which the valve body 151 blocks the communication hole 111a, the 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.

[0052] The valve body 151 has, for example, a spherical shape. However, the shape of the valve body 151 can also be other than spherical. 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 cover 112 and the valve body 151. 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. Therefore, the valve body 151 is biased to the left by the second biasing element 142.

[0053] The valve body 151 is opened and closed by the projection 121c of the first piston 121. The projection 121c extends from the right surface of the second cylinder part 121b to the right in the axial direction. In this way, the projection 121c is provided on the right side of the first piston 121. By moving the first piston 121 from the position shown in Fig. 2 to the right, the projection 121c is inserted into the connecting bore 111a, whereby the front end of the projection 121c can abut against the valve body 151. The valve body 151 is brought into the open state by the front end of the projection 121c abutting against the valve body 151. In this way, the projection 121c can be inserted into the connecting bore 111a and abut against the valve body 151. (Operation of the damping device)

[0054] The operation of the damping device 100 according to the first embodiment of the present invention will be explained with reference to Fig. 2 to Fig. 4 explained.

[0055] The above-mentioned Fig. Figure 2 shows the damping 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 left by the first biasing element 141 and positioned on the leftmost side within the range of motion. Therefore, the projection 121c of the first piston 121 is spaced apart from the valve body 151 and therefore does not abut against the valve body 151. The valve body 151 is biased to the left by the second biasing element 142 and positioned on the leftmost side within the range of motion. Therefore, the valve body 151 is in the closed state.

[0056] 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 through the first opening PO1, thereby increasing the pressure of the space to the left of the first piston 121 in the first fluid chamber S1. This causes the first piston 121 to move to the right.

[0057] 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 right. In the state according to Fig. 3, the pressure in the space on the left side of the first piston 121 is stored in the first liquid chamber S1. The pressure of the space on the left side of the first piston 121 in the first liquid chamber S1 then pushes the first piston 121 to the right and thus in comparison with the one in the state according to Fig. 2 is moved to the right. As the first piston 121 moves to the right, 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.

[0058] In condition according to Fig. 3, the brake fluid in the space on the left side of the first piston 121 in the first fluid chamber S1 is pumped through the first through holes 121f into the space on the right side of the first piston 121 in the first fluid chamber S1. The inner diameter of the first through hole 121f is small, so that the brake fluid flowing through the first through holes 121f encounters a large resistance. Therefore, the pressure pulsation is also dampened by the brake fluid flowing through the first through holes 121f.

[0059] Furthermore, the brake fluid in the space on the right side of the first piston 121 in the first fluid chamber S1 is supplied through the second through-holes 111c to the right side of the first cover 111. The brake fluid passing through the second through-holes 111c is to be supplied to the outlet port P2. The brake fluid flowing through the second through-holes 111c also encounters a large resistance in the same way as the first through-holes 121f. Therefore, the pressure pulsation is also dampened by the brake fluid flowing through the second through-holes 111c.

[0060] Fig. Fig. 4 is a view showing a state in which the first piston 121 on the damper 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 first piston 121 is compared with that in the state according to Fig. 3 is moved further to the right. Here, the projection 121c of the first piston 121 is in the state according to Fig. 4 on the valve body 151. As a result, the valve body 151 is in comparison with that in the state according to Fig. 3 is moved to the right. The valve body 151 is therefore spaced from the connecting bore 111a. Therefore, the connecting bore 111a is open, allowing the brake fluid to flow through it. The brake fluid therefore flows through the connecting bore 111a and flows out of the second fluid chamber S2 via the second opening PO2. (Advantages of the damping device)

[0061] The advantages of the damping device 100 according to the first embodiment of the present invention will be explained.

[0062] 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 hole 111a and to the outlet port P2 via the second opening PO2, the first piston 121, which is slidably provided on the first liquid chamber S1, the first biasing member 141 for biasing the first piston 121 toward the first opening PO1 side, the valve body 151, which is provided on the second liquid chamber S2 and can open and close the side of the connecting hole 111a facing the second opening PO2, the second biasing member 142 for biasing the valve body 151 toward the first opening PO1 side, and the projection 121c, which is provided on the side of the first piston 121 facing the second opening PO2.be inserted into the connecting bore 111a and can rest against the valve body 151.

[0063] As a result, when the pump 36 is driven, the pressure is first stored in a space of the first liquid chamber S1 that is closer to the first port PO1 than the first piston 121. During this time, the first biasing member 141 is gradually contracted in accordance with the movement of the first piston 121 to the second port PO2 side, thereby absorbing the energy of the pressure increase, and thus the pressure increase rate on the side closer to the second port PO2 than the first piston 121 becomes smaller than the pressure increase rate on the side closer to the first port PO1 than the first piston 121.When the first piston 121 moves to the first port PO1 side by reducing the pressure on the first port PO1 side, the first biasing member 141 is gradually expanded, whereby the decreasing speed of the pressure on the side closer to the second port PO2 than the first piston 121 becomes slower than the decreasing speed of the pressure on the side closer to the first port PO1 than the first piston 121. 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 abutting the projection 121c of the first piston 121 against the valve body 151, the communication hole 111a is set in the open state, and thus the brake fluid can flow out appropriately from the second fluid chamber S2 via the second port PO2.In this way, the pressure pulsation of the fluid pressure control unit 15 can be dampened by the damping device 100.

[0064] In the damping device 100, at least one first through-hole 121f is preferably formed on the first piston 121, penetrating from the first opening PO1 side to the second opening PO2 side. This allows pressure pulsation to be dampened by the brake fluid flowing through the first through-hole 121f. Here, a situation is assumed that the first piston 121 seizes and cannot move. In this situation, the brake fluid can flow from the side of the first piston 121 facing the first opening PO1 to the side of the second opening PO2 facing the first opening PO2 through the first through-hole 121f. Therefore, the excessive increase in pressure in the space of the first fluid chamber S1, which is closer to the first opening PO1 than the first piston 121, is suppressed.

[0065] In the damper device 100, a plurality of first through-holes 121f are preferably formed on the first piston 121, wherein the plurality of first through-holes 121f are arranged at equal intervals in the circumferential direction of the first piston 121. As a result, the force generated due to the flow of brake fluid through the first through-holes 121f acts on the first piston 121 evenly in the circumferential direction. Therefore, the inclination of the first piston 121 toward the sliding direction is suppressed by the force acting on the first piston 121 due to the flow of brake fluid through the first through-holes 121f.

[0066] The damping device 100 is preferably provided with the first cover 111, which defines the second fluid chamber S2 and covers the first fluid chamber S1 from the second opening PO2 side. At least one second through-hole 111c is formed on the first cover 111, which penetrates from the first opening PO1 side to the second opening PO2 side. This allows the pressure pulsation to be dampened by the flow of brake fluid through the second through-hole 111c.

[0067] In the damping device 100, a plurality of second through-holes 111c are preferably formed on the first cover 111, wherein the plurality of second through-holes 111c 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. <Zweite Ausführungsform>

[0068] A second embodiment of the present invention is described with reference to Fig. 5 to Fig. 8 explained.

[0069] The second embodiment differs from the above-mentioned first embodiment in that the damping device 100 is replaced by a damping device 200. The other points of the brake system 1 are the same as in the above-mentioned first embodiment, so the explanation is omitted. (Structure of the damping device)

[0070] The details of the structure of the damping device 200 according to the second embodiment of the present invention will be explained with reference to Fig. 5 explained.

[0071] Fig. 5 is a sectional view showing the schematic structure of the damping device 200. The damping device 200 according to Fig. 5, however, represents only one example of the damping device according to the invention. The example according to Fig. 5 with various additional modifications also falls under the damping device according to the invention, as mentioned later.

[0072] In the Fig. 5 and the later mentioned Fig. 6 to Fig. 8, the damper device 200 is illustrated such that the axial direction of its housing 201 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 a second port 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 201, 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 port PO2.The second port PO2 side means the side facing the second port PO2 in the axial direction or the downstream side in the flow direction of the brake fluid directed from the first port PO1 to the second port PO2.

[0073] The damping device 200 is provided with 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 element 231, a second sealing element 232, a first biasing element 241, a second biasing element 242, a third biasing element 243, a valve body 251 and an elastic element 261, as shown in Fig. 5 shown.

[0074] The housing 201 is formed, for example, in the shape of a roller with a hollow space inside. The axial direction of the housing 201 corresponds to the left-right direction. An internal space is formed in the housing 201, penetrating from the left end face to the right end face. The internal space of the housing 201 includes a first hole part 201a, a second hole part 201b, and a third hole part 201c. The first hole part 201a, second hole part 201b, and third hole part 201c each have a cylindrical shape and are arranged coaxially with the central axis of the housing 201. The first hole part 201a, second hole part 201b, and third hole part 201c continue in this order from the left. The diameter of the second hole part 201b is smaller than that of the first hole part 201a. The diameter of the third hole part 201c is larger than that of the second hole part 201b.

[0075] The third cover 213 is fitted into the left end of the first hole portion 201a. The third cover 213 is formed in the shape of a disc having the first opening PO1 in the center. The first opening PO1 is connected to the inlet port P1. The first opening PO1 is arranged coaxially with the center axis of the housing 201. However, the first opening PO1 need not be arranged coaxially with the center axis of the housing 201.

[0076] The first cover 211 is fitted into the third hole part 201c. The first cover 211 is substantially cylindrical. The first cover 211 has a first cylindrical part 211a and a second cylindrical part 211b. The first cylindrical part 211a and the second cylindrical part 211b each have a cylindrical shape and are arranged coaxially with each other. The first cylindrical part 211a and the second cylindrical part 211b continue in this order from the right. The outer diameter of the second cylindrical part 211b is smaller than the outer diameter of the first cylindrical part 211a. The inner diameter of the first cylindrical part 211a and the inner diameter of the second cylindrical part 211b are identical to each other. However, the inner diameter of the second cylindrical part 211b can also be smaller or larger than the inner diameter of the first cylindrical part 211a. The first roller part 211a is fitted into the third hole part 201c.The outer peripheral surface of the second roller part 211b is spaced from the inner peripheral surface of the second hole part 201b in the radial direction.

[0077] A first liquid chamber S1 is defined by the right surface of the third cover 213, the left 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 its left side. The first cover 211 covers the first liquid chamber S1 from its right side. In other words, the left surface of the first cover 211 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.

[0078] A second fluid chamber S2 is defined by the inner peripheral surface of the first cover 211. At the left end of the inner peripheral surface of the first cover 211, the diameter is reduced radially inward. This forms a connecting hole 211c in the center at the left end of the first cover 211. The second fluid chamber S2 is connected to the first fluid chamber S1 via the connecting hole 211c.

[0079] The second cover 212 is fitted to the right end of the inner peripheral surface of the first cover 211. The second cover 212 is formed substantially in the shape of a disk having the second opening PO2. The second opening PO2 is connected to the outlet port P2. The second opening PO2 is arranged radially outward from the center of the second cover 212. In the example according to Fig. 5, there are several second openings PO2. However, the number of second openings PO2 can also be 1.

[0080] The right end of the inner peripheral surface of the first cover 211 has an expanded diameter. The second cover 212 is fitted into the expanded diameter portion of the inner peripheral surface of the first cover 211. Thus, the second liquid chamber S2 is partitioned with the left surface of the second cover 212. That is, the second cover 212 covers the second liquid chamber S2 from its right side. In other words, the left surface of the second cover 212 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.

[0081] The first piston 221 is received in the first hole part 201a and the second hole part 201b. The first piston 221 has a substantially cylindrical shape. The first piston 221 is arranged coaxially with the center axis of the first hole part 201a and the second hole part 201b. The first piston 221 includes a first cylindrical part 221a, a second cylindrical part 221b, and a projection 221c. The first cylindrical part 221a, the second cylindrical part 221b, and the projection 221c each have a cylindrical shape and are arranged coaxially with each other. The first cylindrical part 221a, the second cylindrical part 221b, and the projection 221c continue in this order from the left. The first cylindrical part 221a, the second cylindrical part 221b, and the projection 221c are smaller in outer diameter in this order. The outer peripheral surface of the first cylinder part 221a can slide on the inner peripheral surface of the first hole part 201a.Therefore, the first piston 221 is provided in the first liquid chamber S1 to be slidable in the axial direction.

[0082] An annular groove 221d is formed on the outer peripheral surface of the first cylinder portion 221a. The annular groove 221d extends in the circumferential direction of the first piston 221. The first sealing element 231 is fitted into the annular groove 221d. The first sealing element 231 is, for example, an O-ring. The first sealing element 231 is pressed against the inner peripheral surface of the first hole portion 201a. As a result, the gap between the outer peripheral surface of the first cylinder portion 221a and the inner peripheral surface of the first hole portion 201a is sealed in a fluid-tight manner.

[0083] The first piston 221 is biased to the left by the first biasing element 241. The first biasing element 241 is, for example, an elastic component such as a spring, etc. The first biasing element 241 is arranged between the first piston 221 and the first cover 211. One end of the first biasing element 241 (the left end of which is Fig. 5) abuts a contact surface 221e provided on the right side of the first piston 221. The contact surface 221e is a right surface of the second cylinder part 221b (ie, a step surface between the second cylinder part 221b and the projection 221c). The other end of the first biasing element 241 (the right end of which is in Fig. 5) abuts an annular groove 211d of the first cover 211. The annular groove 211d is formed at the left end of the outer peripheral surface of the second roller part 211b of the first cover 211 and extends in the circumferential direction. Therefore, the other end of the first biasing member 241 abuts the left periphery of the connecting hole 211c. The extension and contraction direction of the first biasing member 241 corresponds to the left-right direction. The first biasing member 241 is in a contracted state relative to its natural length.

[0084] A plurality of first through holes 221f are formed on the first piston 221. The first through holes 221f penetrate the first piston 221 from left to right. In the example according to Fig. 5, the first through-holes 221f extend from the left surface of the first cylinder part 221a to the right surface of the first cylinder part 221a (ie, to the step surface between the first cylinder part 221a and the second cylinder part 221b). The inner diameter of the first through-hole 221f is, for example, approximately 0.4 mm - 0.5 mm in diameter. In the example according to Fig. 5, the first through-holes 221f extend in the axial direction. However, the extension of the first through-hole 221f is not particularly limited. For example, the first through-hole 221f may also extend in a direction inclined to the axial direction or be bent or curved.

[0085] The 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 uneven intervals in the circumferential direction. Furthermore, the number of first through-holes 221f may also be 1. The brake fluid can flow from the left side to the right side of the first piston 221 through the first through-holes 221f. The first through-holes 221f are provided to enhance a pressure pulsation reducing effect. The function of the first through-holes 221f will be mentioned later.

[0086] The brake fluid flowing through the first through holes 221f is conveyed in a space on the right side of the first piston 221 in the first fluid chamber S1 to a space on the outer side of the first preload element 241 (specifically, a radially outer space). Connecting grooves 221g are provided on the contact surface 221e of the first piston 221 to connect a space on the inner side of the first preload element 241 (specifically, a radially inner space) with the space on the outer side of the first preload element 241. For example, the connecting grooves 221g extend in the radial direction of the first piston 221. The brake fluid can flow through the connecting grooves 221g from the space on the outer side of the first preload element 241 into the space on the inner side of the first preload element 241. In the example according to Fig. 5, several connecting grooves 221g are provided. However, the number of connecting grooves 221g can also be 1. The connecting grooves 221g are provided to properly supply the brake fluid to the connecting bore 211c and the second fluid chamber S2. The function of the connecting grooves 221g will be discussed later.

[0087] A cavity 221h is formed on the first cylinder part 221a. The cavity 221h is a section that is hollowed from left to right on the first piston 221. In the example according to Fig. 5, the cavity 221h is hollowed from the left surface of the first cylinder part 221a to the right. The cavity 221h is arranged coaxially with the central axis of the housing 201. However, the cavity 221h need not be arranged coaxially with the central axis of the housing 201.

[0088] The second piston 222 is housed in the cavity 221h. The second piston 222 has a substantially cylindrical shape. The second piston 222 is arranged coaxially with the central axis of the cavity 221h. The outer peripheral surface of the second piston 222 can slide on the inner peripheral surface of the cavity 221h. Therefore, the second piston 222 is provided to slide on the cavity 221h in the axial direction.

[0089] 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 element 232 is fitted into the annular groove 222a. The second sealing element 232 is, for example, an O-ring. The second sealing element 232 is pressed against the inner peripheral surface of the cavity 221h. As a result, the gap between the outer peripheral surface of the second piston 222 and the inner peripheral surface of the cavity 221h is sealed in a fluid-tight manner.

[0090] The second piston 222 is biased to the left by the third biasing element 243. The third biasing element 243 is, for example, an elastic component such as a spring, etc. The third biasing element 243 is arranged between the second piston 222 and the bottom surface of the cavity 221h (the right inner surface of the cavity 221h in Fig. 5). One end of the third biasing element 243 (the left end of which is Fig. 5) abuts against a recessed portion 222b of the second piston 222. The recessed portion 222b is provided in the center of the right surface of the second piston 222. The other end of the third biasing member 243 (the right end of which is in Fig. 5) rests against the bottom surface of the cavity 221h. The expansion and contraction direction of the third prestressing element 243 corresponds to the left-right direction. The third prestressing element 243 is in a contracted state relative to its natural length.

[0091] The valve body 251 is provided at the second fluid chamber S2 and can open and close the right side of the communication hole 211c. In an open state, in which 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 a closed state, in which 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.

[0092] The valve body 251 has a head portion 251a and a stem portion 251b. The head portion 251a is substantially hemispherical. The left side of the head portion 251a is a spherical surface that can open and close the communication hole 211c. The stem portion 251b extends from the right surface of the head portion 251a to the right. The sectional shape of the stem portion 251b is, for example, circular or polygonal, etc. The stem portion 251b is arranged coaxially with the central axis of the housing 201. The second biasing member 242 is, for example, an elastic member such as a spring, etc. 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 corresponds to the left-right direction. The second prestressing element 242 is in a contracted state relative to its natural length.Therefore, the valve body 251 is biased to the left by the second biasing element 242.

[0093] The valve body 251 is opened and closed by the projection 221c of the first piston 221. The projection 221c extends from the right surface of the second cylinder part 221b to the right in the axial direction. In this way, the projection 221c is provided on the right side of the first piston 221. By moving the first piston 221 from the position shown in Fig. 5 to the right, the projection 221c is inserted into the connecting bore 211c, whereby the front end of the projection 221c can abut against the valve body 251. The valve body 251 is brought into the open state by the front end of the projection 221c abutting against the valve body 251. In this way, the projection 221c can be inserted into the connecting bore 211c and abut against the valve body 251.

[0094] The elastic member 261 is provided on the left side of the first cover 211 and has a shape of a ring extending in the circumferential direction of the first cover 211. In the example according to Fig. 5, the elastic element 261 rests against the left surface of the first roller part 211a of the first cover 211. The elastic element 261 is also clamped between the outer peripheral surface of the second roller part 211b of the first cover 211 and the inner peripheral surface of the second hole part 201b. The elastic element 261 is, for example, an O-ring. (Operation of the damping device)

[0095] The operation of the damping device 200 according to the second embodiment of the present invention will be explained with reference to Fig. 5 to Fig. 8 explained.

[0096] The above-mentioned Fig. 5 shows the damping device 200 in the normal state, where the pump 36 on the fluid pressure control unit 15 is not driven. In this case, the first piston 221 is biased to the left by the first biasing element 241 and positioned on the leftmost side within the movement range. Therefore, the projection 221c of the first piston 221 is spaced apart from the valve body 251 and therefore does not abut against the valve body 251. The valve body 251 is biased to the left by the second biasing element 242 and positioned on the leftmost side within the movement range. Therefore, the valve body 251 is in the closed state. Furthermore, the second piston 222 is biased to the left by the third biasing element 243 and positioned on the leftmost side within the movement range.

[0097] 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. 5, the brake fluid flows into the damping device 200 through the first opening PO1, increasing the pressure of the space to the left of the first piston 221 in the first fluid chamber S1. This causes the second piston 222 to move to the right first. For example, because the elastic modulus of the second preload element 242 is smaller than the elastic modulus of the first preload element 241, the second piston 222 moves earlier than the first piston 221. 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.

[0098] Fig. Fig. 6 is a view showing a state in which the second piston 222 on the damper device 200 is displaced in comparison with that in the state of Fig. 5 is moved to the right. In the state according to Fig. 6, the pressure in the space on the left side of the first piston 221 is stored in the first liquid chamber S1. The pressure of the space on the left side of the first piston 221 in the first liquid chamber S1 then pushes the second piston 222 to the right and thus in comparison with the one in the state according to Fig. 5 to the right. As the second piston 222 moves to the right, the third biasing element 243 expands and contracts, eventually contracting. As a result, the force acting on the second piston 222 is absorbed by the third biasing element 243. In this way, the pressure pulsation is dampened by the expansion and contraction of the third biasing element 243 in accordance with the movement of the second piston 222.

[0099] In condition according to Fig. 6, the brake fluid in the space on the left side of the first piston 221 in the first fluid chamber S1 is pumped through the first through holes 221f into the space on the right side of the first piston 221 in the first fluid chamber S1. The inner diameter of the first through hole 221f is small, so that the brake fluid flowing through the first through holes 221f encounters a large resistance. Therefore, the pressure pulsation is also dampened by the brake fluid flowing through the first through holes 221f.

[0100] Fig. Fig. 7 is a view showing a state in which the first piston 221 on the damper device 200 is displaced in comparison with that in the state of Fig. 6 is moved to the right. In the state according to Fig. 7, the pressure in the space on the left side of the first piston 221 is stored in the first liquid chamber S1. The pressure of the space on the left side of the first piston 221 in the first liquid chamber S1 then pushes the first piston 221 to the right and thus compared to the one in the state according to Fig. 6 is moved to the right. The second piston 222 can also be moved or not moved relative to the first piston 221. As the first piston 221 moves to the right, the first preload element 241 expands and contracts, eventually contracting. As a result, the force acting on the first piston 221 is absorbed by the first preload element 241. In this way, the pressure pulsation is dampened by the expansion and contraction of the first preload element 241 in accordance with the movement of the first piston 221.

[0101] As the first piston 221 moves to the right, not only the first preload element 241 but also the annular elastic element 261 expands and contracts, eventually contracting. As a result, the force acting on the first piston 221 is also absorbed by the elastic element 261. In this way, the pressure pulsation is dampened by the expansion and contraction of the elastic element 261 according to the movement of the first piston 221.

[0102] Fig. Fig. 8 is a view showing a state in which the first piston 221 on the damper device 200 is displaced in comparison with that in the state of Fig. 7 is moved to the right. In the state according to Fig. 8, the first piston 221 is compared with the one in the state according to Fig. 7 is moved further to the right. In the state according to Fig. 8, the projection 221c of the first piston 221 rests against the valve body 251. As a result, the valve body 251 is in comparison with that in the state according to Fig. 7 is moved to the right. The valve body 251 is therefore spaced from the connecting bore 211c. Therefore, the connecting bore 211c is open, allowing the brake fluid to flow through it. The brake fluid therefore flows through the connecting bore 211c and flows out of the second fluid chamber S2 via the second opening PO2.

[0103] In the first prestressing element 241 in the state according to Fig. 8, which is fully contracted, the gaps between the spring wires constituting the first biasing member 241 are closed if necessary. Also in this case, the brake fluid supplied through the first through-holes 221f into the space on the right side of the first piston 221 in the first fluid chamber S1 can flow from the space on the outer side of the first biasing member 241 into the space on the inner side of the first biasing member 241 through the connecting grooves 221g. Therefore, the brake fluid can be supplied from the space on the inner side of the first biasing member 241 into the connecting hole 211c and thus properly flow out of the second fluid chamber S2 via the second opening PO2.

[0104] The valve body 251 may also abut against the second cover 212 when the valve body 251 is in the open state, as shown in Fig. 8. In the example according to Fig. 8, the stem portion 251b of the valve body 251 is moved along the center axis of the housing 201. As mentioned above, the second openings PO2 are located radially outward from the center of the second cover 212. Therefore, the front end of the stem portion 251b of the valve body 251 can abut against the second cover 212. This stabilizes the posture of the valve body 251 without vibration of the valve body 251, even when the valve body 251 is in the open state. (Advantages of the damping device)

[0105] The advantages of the damping device 200 according to the second embodiment of the present invention will be explained.

[0106] The damping device 200 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 hole 211c and to the outlet port P2 via the second opening PO2, the first piston 221 slidably provided on the first liquid chamber S1, the first biasing member 241 for biasing the first piston 221 toward the first opening PO1 side, the valve body 251, which is provided on the second liquid chamber S2 and can open and close the side of the connecting hole 211c facing the second opening PO2, the second biasing member 242 for biasing the valve body 251 toward the first opening PO1 side, and the projection 221c provided on the side of the first piston 221 facing the second opening PO2.can be inserted into the connecting bore 211c and can abut against the valve body 251. This allows the pressure pulsation of the fluid pressure control unit 15 to be dampened, just as with the above-mentioned damping device 100.

[0107] The damping device 200 is further provided with a concave 221h formed on the first piston 221 from the first port PO1 side to the second port PO2 side, a second piston 222 slidably provided on the concave 221h, and a third biasing member 243 for biasing the second piston 222 toward the first port PO1 side. Thus, when the pump 36 is driven, the movement of the second piston 222 toward the second port PO2 side occurs in addition to the movement of the first piston 221 toward the second port PO2 side. The pressure pulsation can be further dampened by expansion and contraction of the third biasing member 243 according to the movement of the second piston 222. Therefore, the pressure pulsation can be dampened more effectively.

[0108] The damper device 200 is preferably provided with the second cover 212 for covering the second fluid chamber S2 from the second opening PO2 side, and the valve body 251 can abut against the second cover 212. This stabilizes the posture of the valve body 251 without causing vibration of the valve body 251 even when the valve body 251 is in the open state. Therefore, the opening and closing operation of the valve body 251 can be made smooth.

[0109] In the damping device 200, a contact surface 221e, which abuts one end of the first biasing element 241, is preferably provided on the side of the first piston 221 facing the second opening PO2, wherein the other end of the first biasing element 241 abuts the circumference of the connecting bore 211c facing the first opening PO1, and wherein the connecting grooves 221g for connecting between a space on the inner side of the first biasing element 241 and a space on the outer side of the first biasing element 241 are provided on the contact surface 221e.Therefore, even when the gaps between the spring wires constituting the first biasing member 241 are closed at the first biasing member 241 which is fully contracted, the brake fluid can be supplied from the space on the outer side of the first biasing member 241 to the space on the inner side of the first biasing member 241, so that the brake fluid can flow out from the second fluid chamber S2 via the second opening PO2 more appropriately.

[0110] The damping device 200 is preferably provided with the first cover 211 that defines the second fluid chamber S2 and covers the first fluid chamber S1 from the second opening PO2 side. An annular elastic member 261 extending in the circumferential direction of the first cover 211 is provided on the side of the first cover 211 facing the first opening PO1. As a result, the force acting on the first piston 221 when the first piston 221 moves toward the second opening PO2 side can be absorbed not only by the first biasing member 241 but also by the annular elastic member 261. Therefore, the pressure pulsation can be dampened more effectively.

[0111] So far, the preferred embodiments of the present invention have been explained with reference to the accompanying drawings. However, it should be understood that the present invention is not limited to the above-mentioned embodiments. Needless to say, various altered or modified examples within the scope of the claims are also within the technical scope of the present invention.

[0112] In the above, the structure of the damping device 100 is described with reference to Fig. 2 and the structure of the damping device 200 based on the Fig. 5. The example according to Fig. 2 or according to Fig. 5 with various additional modifications also falls under the damping device according to the invention.

[0113] For example, the sliding direction of the first piston 121, 221 may also differ from the axial direction of the housing 101, 201. For example, if the center axis of the first fluid chamber S1 is not coaxial with the housing 101, 201, the sliding direction of the first piston 121, 221 is a direction different from the axial direction of the housing 101, 201.

[0114] For example, the sectional shape of the first fluid chamber S1 and the first piston 121, 221, which is perpendicular to the sliding 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 piston 121, 221 corresponds to the direction along the outer peripheral edge of the first piston 121, 221 and represents the direction around the central axis of the first piston 121, 221.

[0115] For example, the sectional shape of the first cover 111, 211, 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, 211 corresponds to the direction along the outer peripheral edge of the first cover 111, 211 and represents the direction around the central axis of the first cover 111, 211.

[0116] For example, the sliding direction of the second piston 222 may also differ from the sliding direction of the first piston 221. For example, if the cavity 221h is not arranged coaxially with the housing 201, the sliding direction of the second piston 222 is a different direction from the sliding direction of the first piston 221.

[0117] For example, the example according to Fig. 2, in which at least either the first through-holes 121f or the second through-holes 111c are omitted, fall under the damping device according to the invention. If the first through-holes 121f are omitted, for example, grooves extending in the axial direction may be provided on the inner peripheral surface of the second hole part 101b so that the brake fluid can also flow through these grooves from the left side to the right side of the first piston 121.

[0118] For example, in the example according to Fig. 2 also the valve body 251 and the second cover 212 according to Fig. 5 instead of the valve body 151 and the second cover 112. Furthermore, in the example according to Fig. 5 also the valve body 151 and the second cover 112 according to Fig. 2 instead of the valve body 251 and the second cover 212.

[0119] For example, in the example according to Fig. 2 the brake fluid flowing through the first through holes 121f in the space on the right side of the first piston 121 in the first fluid chamber S1 is conveyed into the space on the outer side of the first preload element 141, wherein connecting grooves 221g may also be provided on the contact surface 121e of the first piston 121.

[0120] For example, the elastic element 261 can also be used in the example according to Fig. 2 also added or in the example according to Fig. 5 can also be omitted.

[0121] For example, the example according to Fig. 5, in which the first through holes 221f are omitted, fall under the damping device according to the invention. If the first through holes 221f are omitted, for example, grooves extending in the axial direction can be provided on the inner peripheral surface of the first hole part 201a so that the brake fluid can also flow through these grooves from the left side to the right side of the first piston 221.

[0122] For example, the first cover 211 in the example according to Fig. 5 through holes penetrating from the side of the first opening PO1 to the side of the second opening PO2 (e.g. second through holes 111c in Fig. 2), be educated.

[0123] For example, in the example according to Fig.5 the brake fluid flowing through the first through holes 221f in the space on the right side of the first piston 221 in the first fluid chamber S1 is conveyed into the space on the inner side of the first preload member 241, wherein the connecting grooves 221g may also be omitted. [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 111a Connecting hole 111c Second through hole 112 Second cover 113 Third cover 121 First piston 121c lead 121e contact surface 121f First through hole 131 First sealing element 141 First prestressing element 142 Second prestressing element 151 valve body 200 Damping device 201 housing 211 First cover 211c connecting hole 212 Second cover 213 Third cover 221 First piston 221c lead 221e contact surface 221f First through hole 221g connecting groove 221h cavity 222 Second piston 231 First sealing element 232 Second sealing element 241 First prestressing element 242 Second prestressing element 243 Third prestressing element 251 valve body 261 Elastic element 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, 200) 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 (111a, 211c) and connected to the outlet port (P2) via a second opening (PO2), a first piston (121, 221) slidably provided on the first liquid chamber (S1), a first biasing element (141, 241) for biasing the first piston (121, 221) to the side of the first opening (PO1), a valve body (151, 251) provided on the second liquid chamber (S2) and capable of opening and closing the side of the connecting bore (111a, 211c) facing the second opening (PO2), a second biasing element (142, 242) for biasing the valve body (151, 251) to the side of the first opening (PO1) and a projection (121c, 221c) which is provided on the side of the first piston (121, 221) facing the second opening (PO2), can be inserted into the connecting bore (111a, 211c) and can bear against the valve body (151, 251). [2] A damping device according to claim 1, wherein at least one first through-hole (121f, 221f) penetrating from the side of the first opening (PO1) to the side of the second opening (PO2) is formed on the first piston (121, 221). [3] A damping device according to claim 2, wherein a plurality of first through holes (121f, 221f) are formed on the first piston (121, 221), the plurality of first through holes (121f, 221f) being arranged at equal intervals in the circumferential direction of the first piston (121, 221). [4] Damping device according to claim 1, which is provided with a first cover (111) which defines the second liquid chamber (S2) and covers the first liquid chamber (S1) from the side of the second opening (PO2), wherein at least one second through-hole (111c) penetrating from the side of the first opening (PO1) to the side of the second opening (PO2) is formed on the first cover (111). [5] The damping device according to claim 4, wherein a plurality of second through-holes (111c) are formed on the first cover (111), the plurality of second through-holes (111c) being arranged at equal intervals in the circumferential direction of the first cover (111). [6] Damping device according to claim 1, which is provided with a cavity (221h) formed on the first piston (221) from the side of the first opening (PO1) to the side of the second opening (PO2), a second piston (222) slidably provided on the cavity (221h), and a third biasing element (243) for biasing the second piston (222) to the side of the first opening (PO1) is provided. [7] Damping device according to claim 1, which is provided with a second cover (212) for covering the second liquid chamber (S2) from the side of the second opening (PO2) is provided, wherein the valve body (251) can abut against the second cover (212). [8] Damping device according to claim 1, wherein on the side of the first piston (221) facing the second opening (PO2), a contact surface (221e) is provided which bears against one end of the first biasing element (241), wherein the other end of the first prestressing element (241) abuts against the periphery of the connecting bore (211c) facing the first opening (PO1), and wherein connecting grooves (221g) for connecting between a space on the inner side of the first prestressing element (241) and a space on the outer side of the first prestressing element (241) are provided on the contact surface (221e). [9] Damping device according to claim 1, which is provided with a first cover (211) which defines the second liquid chamber (S2) and covers the first liquid chamber (S1) from the side of the second opening (PO2), wherein an annular elastic element (261) extending in the circumferential direction of the first cover (211) is provided on the side of the first cover (211) facing the first opening (PO1). [10] A fluid pressure control unit comprising a damping device (100, 200) according to any one of claims 1 to 9. [11] A braking system comprising a fluid pressure control unit (15) according to claim 10.

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