JP7684415B2 - Damping device, hydraulic control unit and brake system - Google Patents

Description

The present invention relates to a damping device, a hydraulic control unit, and a brake system.

In a conventional vehicle, a hydraulic control unit is provided to control the braking force applied to the wheels. For example, as disclosed in Patent Document 1, a plurality of valves and a pump are provided in a flow path in the hydraulic control unit. In such a hydraulic control unit, for example, in anti-lock brake control or anti-skid control, the opening and closing states of each valve are set to specific states, and the pump is driven.

JP 2010-052519 A

In the hydraulic control unit, a reciprocating plunger pump is mainly used as the pump. Therefore, the pump intermittently pumps the brake fluid. Therefore, when the pump is driven, pressure pulsation occurs, which is a phenomenon in which the hydraulic pressure of the brake fluid pulsates in the flow path in the hydraulic control unit. The sound generated by such pressure pulsation may be perceived as noise by the vehicle occupants, and may be a factor that reduces comfort. Therefore, from the viewpoint of improving comfort, it is desirable to appropriately damp the pressure pulsation of the hydraulic control unit.

In view of the above, an object of the present invention is to provide a damping device, a hydraulic control unit, and a brake system capable of damping pressure pulsations of a hydraulic control unit.

In order to solve the above problem, the damping device is provided in a hydraulic control unit that controls the braking force generated on a wheel, and has an inlet port connected to a discharge side of a pump and an outlet port communicating with the inlet port, and is a damping device that damps pressure pulsations, and is equipped with: a first fluid chamber communicating with the inlet port; a first piston that is slidably provided in the first fluid chamber in a first sliding direction and in which a first through hole that penetrates in the first sliding direction is formed; a first valve body that can open and close the inlet port side of the first through hole; a first biasing member that biases the first valve body toward the outlet port side; a protrusion member that is arranged on the outlet port side of the first valve body, extends in the first sliding direction, is insertable into the first through hole, and has a protrusion that can abut against the first valve body; and a second biasing member that biases the first piston toward the inlet port side.

In order to solve the above problem, the hydraulic control unit includes the above damping device.

In order to solve the above problem, a brake system includes the above hydraulic control unit.

According to the present invention, it is possible to attenuate the pressure pulsation of the hydraulic control unit.

1 is a schematic diagram showing a schematic configuration of a brake system according to an embodiment of the present invention; 1 is a cross-sectional view showing a schematic configuration of a damping device according to an embodiment of the present invention. 3 is a diagram showing a state in which a first piston has moved to the right compared to the state in FIG. 2 in the damping device according to the embodiment of the present invention; FIG. 4 is a diagram showing a state in which the first piston has moved to the right compared to the state in FIG. 3 in the damping device according to the embodiment of the present invention. FIG. 5 is a diagram showing a state in which the first piston has moved to the right compared to the state in FIG. 4 in the damping device according to the embodiment of the present invention. FIG.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present invention are not shown.

In this embodiment, a vehicle having four wheels 17 will be described as an example of a vehicle, but the vehicle to which the present invention can be applied is not limited to vehicles having four wheels 17, and may be, for example, a vehicle having one, two, or three wheels 17, or a vehicle having five or more wheels 17.

<Brake system configuration>
The configuration of a brake system 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

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

The brake system 1 is mounted on a vehicle having four wheels 17, and each wheel 17 is braked by a brake device 16 provided on each wheel 17. The braking force acting on each wheel 17 is controlled by a hydraulic control unit 15. In order to facilitate understanding, only a portion of the brake system 1 related to one of the front wheels and the rear wheels is shown in Fig. 1, and a portion related to the other of the front wheels and the rear wheels is not shown.

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

The brake pedal 11 is used by the driver to apply the brakes. In applying the brakes, the driver depresses the brake pedal 11. The booster 12 is connected to the brake pedal 11 and amplifies the force applied to the brake pedal 11. The master cylinder 13 is connected to the booster 12 and contains a piston that reciprocates in conjunction with the brake pedal 11, generating a fluid pressure according to the amount of braking operation. The reservoir 14 is attached to the master cylinder 13 and stores brake fluid.

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

A main flow path 21, a sub-flow path 22, and a supply flow path 23 are formed in the base body 15a of the hydraulic control unit 15 as flow paths for the brake fluid. The main flow path 21 distributes the brake fluid in the master cylinder 13 to the wheel cylinders of the braking device 16. The sub-flow path 22 releases the brake fluid in the wheel cylinders of the braking device 16. The supply flow path 23 supplies the brake fluid in the master cylinder 13 to the sub-flow path 22.

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

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

The main flow path 21 communicates between the master cylinder 13 and the wheel cylinders of the braking devices 16. The main flow path 21 includes a first main flow path 21a and two second main flow paths 21b. The first main flow path 21a is connected to the master cylinder 13. The two second main flow paths 21b branch off from the first main flow path 21a and are connected to each braking device 16. A first valve 33 is provided in the first main flow path 21a. An inlet valve 31 is provided in the second main flow path 21b.

The sub-path 22 communicates the brake device 16 side of the main path 21 relative to the inlet valve 31 with the master cylinder 13 side of the main path 21 relative to the inlet valve 31 and with the brake device 16 side of the first valve 33. The sub-path 22 includes two first sub-paths 22a and a second sub-path 22b. Each of the first sub-paths 22a is connected to the brake device 16 side of the main path 21 relative to the inlet valve 31. The second sub-path 22b connects a joining point of the two first sub-paths 22a with the master cylinder 13 side of the main path 21 relative to the inlet valve 31 and with the brake device 16 side of the first valve 33. A release valve 32 is provided in the first sub-path 22a. An accumulator 35 and a pump 36 are provided in the second sub-path 22b in this order from the first sub-path 22a side.

The pump 36 is driven by the motor 37, and sucks the brake fluid from the first sub-channel 22a and discharges it to the main channel 21. The pump 36 is a reciprocating plunger pump. Specifically, the plunger of the pump 36 reciprocates as it is intermittently pressed by an eccentric cam provided on the output shaft of the motor 37. This causes the pump 36 to pump the brake fluid.

The supply flow passage 23 communicates the master cylinder 13 side of the first valve 33 in the main flow passage 21 with the suction side of the pump 36 in the sub flow passage 22. A second valve 34 is provided in the supply flow passage 23.

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

For example, during normal operation when anti-lock brake control or anti-skid control, which will be described later, is not being executed, the inlet valve 31 is opened, the release valve 32 is closed, the first valve 33 is opened, and the second valve 34 is closed. This allows the brake fluid to flow from the master cylinder 13 to the wheel cylinders of the braking device 16 only through the main flow path 21, without passing through the secondary flow path 22 and the supply flow path 23. In this state, when the brake pedal 11 is depressed, the piston of the master cylinder 13 is pushed in, increasing the hydraulic pressure of the brake fluid in the wheel cylinders, and applying a braking force to the wheels 17.

Antilock brake control is a control for preventing the wheels 17 from locking. For example, when antilock brake control is executed, first, the inlet 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 path 21 and the wheel cylinder of the brake device 16, and allows the brake fluid to flow from the wheel cylinder to the secondary flow path 22. Therefore, the brake fluid flows from the wheel cylinder to the accumulator 35, the hydraulic pressure of the brake fluid in the wheel cylinder decreases, and the braking force applied to the wheels 17 decreases. The brake fluid that has flowed into the accumulator 35 is returned to the main flow path 21 via the secondary flow path 22 by driving the pump 36.

Then, by closing both the inlet valve 31 and the release valve 32 from the above state, the flow of brake fluid between the main flow path 21 and the secondary flow path 22 and the wheel cylinders is stopped, the hydraulic pressure of the brake fluid in the wheel cylinders is maintained, and the braking force applied to the wheels 17 is maintained. After that, the inlet valve 31 is opened and the release valve 32 is closed, so that the flow of brake fluid between the main flow path 21 and the wheel cylinders is resumed, the hydraulic pressure of the brake fluid in the wheel cylinders is increased, and the braking force applied to the wheels 17 is increased.

The anti-slip control is a control for stabilizing the behavior of the vehicle. In the anti-slip control, the driving force and the braking force of the vehicle are appropriately controlled. For example, when the vehicle is braked without brake operation during the execution of the anti-slip control, the inlet valve 31 is opened, the release valve 32 is closed, the first valve 33 is closed, and the second valve 34 is opened. This allows the brake fluid to flow from the master cylinder 13 to the wheel cylinder of the brake device 16 through the supply flow path 23 and the sub-flow path 22. In this state, the pump 36 is driven to increase the hydraulic pressure of the brake fluid in the wheel cylinder, generating a braking force for braking the wheels 17.

As described above, the hydraulic pressure control unit 15 controls the driving of the pump 36. When the pump 36 is driven, pressure pulsation occurs, which is a phenomenon in which the hydraulic pressure of the brake fluid pulsates in the flow path within the hydraulic pressure control unit 15. Sounds generated by such pressure pulsation may be perceived as noise by passengers in the vehicle, and may be a factor in reducing comfort. Therefore, the hydraulic pressure control unit 15 is provided with a damping device 100 that damps the pressure pulsation.

The damping device 100 is provided in the sub-flow path 22 (specifically, the second sub-flow path 22b) downstream of the pump 36. The damping device 100 has an inlet port P1 and an outlet port P2. The inlet port P1 is connected to the discharge side of the pump 36. The inlet port P1 and the outlet port P2 are communicated with each other. Therefore, the brake fluid discharged from the pump 36 flows into the damping device 100 through the inlet port P1, passes through the damping device 100, and then flows out of the damping device 100 through the outlet port P2.

Hereinafter, the details of the configuration of the damping device 100 will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view showing a schematic configuration of the damping device 100. However, the damping device 100 shown in Fig. 2 is merely one example of the damping device according to the present invention, and as will be described later, damping devices according to the present invention also include those in which various modifications are made to the example shown in Fig. 2.

2 and 3 to 5 described later, the damping device 100 is shown with the inlet port P1 side on the left side and the outlet port P2 side on the right side. Hereinafter, the inlet port P1 side is also referred to as the left side, and the outlet port P2 side is also referred to as the right side. Hereinafter, the left-right direction which is the axial direction of the housing 101 is also simply referred to as the axial direction.

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

The housing 101 has, for example, a cylindrical shape with a hollow space inside. The axial direction of the housing 101 is the left-right direction. An internal space is formed in the housing 101 so as to penetrate from the left end surface to the right end surface. The internal space of the housing 101 includes a first hole portion 101a, a second hole portion 101b, a third hole portion 101c, a fourth hole portion 101d, and a fifth hole portion 101e. Each of the first hole portion 101a, the second hole portion 101b, the third hole portion 101c, the fourth hole portion 101d, and the fifth hole portion 101e has a cylindrical shape and is arranged coaxially with the central axis of the housing 101. The first hole portion 101a, the second hole portion 101b, the third hole portion 101c, the fourth hole portion 101d, and the fifth hole portion 101e are continuous in this order from the left side.

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

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

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

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

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

A first through hole 104b is formed in the first piston 104. The first through hole 104b penetrates the first piston 104 in the axial direction, which is the first sliding direction. Therefore, the first through hole 104b penetrates from the left end surface to the right end surface of the first piston 104. In the example of FIG. 2, a groove portion 104c is formed in the left end surface of the first piston 104, and a groove portion 104d is formed in the right end surface of the first piston 104. The groove portion 104c and the groove portion 104d are formed in an annular shape along the periphery of the first through hole 104b. And, the first through hole 104b penetrates from the bottom surface of the groove portion 104c to the bottom surface of the groove portion 104d. However, the shape of the left end surface and the right end surface of the first piston 104 is not limited to the example of FIG. 2, and for example, the groove portion 104c and the groove portion 104d may not be formed. 2, the first through hole 104b is disposed coaxially with the central axis of the first piston 104. However, the first through hole 104b does not have to be disposed coaxially with the central axis of the first piston 104.

The first valve body 106 can open and close the left side of the first through hole 104b. In an open state where the first valve body 106 does not block the first through hole 104b, brake fluid can flow through the first through hole 104b. This state corresponds to the open state of the first valve body 106 and the open state of the first through hole 104b. In a closed state where the first valve body 106 blocks the first through hole 104b, brake fluid cannot flow through the first through hole 104b. This state corresponds to the closed state of the first valve body 106 and the closed state of the first through hole 104b.

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

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

In the example of FIG. 2, a tapered portion 104e is formed on the left side of the first through hole 104b. The tapered portion 104e is a portion that expands in diameter as it moves to the left. The first valve body 106 can abut against the tapered portion 104e of the first through hole 104b. The first valve body 106 abuts against the tapered portion 104e, thereby closing the first through hole 104b. In this case, compared to the case where the tapered portion 104e is not formed, the first valve body 106 and the first through hole 104b are in stable contact with each other, so that the first through hole 104b can be appropriately closed. However, the tapered portion 104e may not be formed in the first through hole 104b.

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

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

The protruding member 109 is provided to open and close the first valve body 106. The protruding member 109 is disposed to the right of the first piston 104. The protruding member 109 has a base 109a and a protruding portion 109b. The base 109a has a generally circular plate shape. The base 109a is fitted into the second hole portion 101b. The protruding portion 109b is connected to the base 109a. The protruding portion 109b protrudes to the left from the center of the base 109a. The protruding portion 109b extends in the axial direction, which is the first sliding direction.

The protrusion 109b is disposed on the right side of the first valve body 106. The protrusion 109b is disposed coaxially with the central axis of the first through hole 104b. When the first piston 104 moves to the right from the position of FIG. 2, the protrusion 109b is inserted into the first through hole 104b, and the tip of the protrusion 109b can abut against the first valve body 106. When the tip of the protrusion 109b abuts against the first valve body 106, the position of the first valve body 106 is maintained. In this state, when the first piston 104 moves further to the right, the first valve body 106 is opened. In this way, the protrusion 109b can be inserted into the first through hole 104b and can abut against the first valve body 106.

In the example of Fig. 2, a recess 109c is formed at the tip of the protrusion 109b. The recess 109c has a spherical shape with a curvature that is approximately the same as the curvature of the first valve body 106. The recess 109c of the protrusion 109b abuts against the first valve body 106. In this case, the contact area between the first valve body 106 and the protrusion 109b is larger than when the recess 109c is not formed, so that the first valve body 106 can be appropriately maintained in an open state. However, the recess 109c does not have to be formed in the protrusion 109b.

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

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

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

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

An annular groove 111a is formed on the outer circumferential surface of the second piston 111. The annular groove 111a extends in the circumferential direction of the second piston 111. A second seal member 112 is fitted into the annular groove 111a. The second seal member 112 is, for example, an O-ring. The second seal member 112 is pressed against the inner circumferential surface of the third hole portion 101c. This causes a gap between the outer circumferential surface of the second piston 111 and the inner circumferential surface of the third hole portion 101c to be liquid-tightly sealed.

The third biasing member 113 is, for example, an elastic member such as a spring. The third biasing member 114 is, for example, an elastic member such as a rubber ring. The third biasing member 113 and the third biasing member 114 are disposed in a space in the second liquid chamber S2 to the right of the second piston 111. The third biasing member 113 and the third biasing member 114 expand and contract in the left-right direction. The third biasing member 113 and the third biasing member 114 are in a contracted state relative to their natural length.

In the example of FIG. 2, an annular protrusion 111b is formed on the right end surface of the second piston 111. The annular protrusion 111b is arranged coaxially with the center axis of the second piston 111 and protrudes to the right from the right end surface of the second piston 111. The left end of the third biasing member 113 abuts on the right end surface of the second piston 111, radially inward from the annular protrusion 111b. The third biasing member 114 is arranged to cover the outer periphery of the third biasing member 113. The left end of the third biasing member 114 abuts on the right end surface of the second piston 111, radially outward from the annular protrusion 111b. The right ends of the third biasing member 113 and the third biasing member 114 abut on the step portion between the third hole portion 101c and the fourth hole portion 101d. Therefore, the second piston 111 is biased to the left by the third biasing member 113 and the third biasing member 114.

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

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

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

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

In the example of FIG. 2, a tapered portion 101f is formed on the right side of the fourth hole portion 101d. The tapered portion 101f is a portion that expands in diameter as it moves to the right. The second valve body 115 can abut against the tapered portion 101f of the fourth hole portion 101d. The second valve body 115 abuts against the tapered portion 101f to close the fourth hole portion 101d. In this case, the second valve body 115 and the fourth hole portion 101d are in stable contact with each other compared to the case where the tapered portion 101f is not formed, so that the fourth hole portion 101d can be appropriately closed. However, the tapered portion 101f does not have to be formed in the fourth hole portion 101d.

<Operation of the damping device>
The operation of the damping device 100 according to the embodiment of the present invention will be described with reference to FIGS.

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

Here, as described above, when antilock brake control, anti-skid control, or the like is executed, the hydraulic control unit 15 drives the pump 36. When the pump 36 is driven in the state shown in Fig. 2, brake fluid flows into the damping device 100 via the inlet port P1, and the pressure in the space to the left of the first piston 104 in the first fluid chamber S1 increases. As a result, the first piston 104 moves to the right.

3 is a diagram showing a state in which the first piston 104 has moved to the right in the damping device 100 compared to the state shown in FIG. 2. In the state shown in FIG. 3, the first through-hole 104b is in a closed state, so pressure is stored in the space to the left of the first piston 104 in the first liquid chamber S1. The first piston 104 is pressed to the right by the pressure in the space to the left of the first piston 104 in the first liquid chamber S1, and the first piston 104 has moved to the right compared to the state shown in FIG. 2. When the first piston 104 moves to the right, the second biasing member 110 expands and contracts, and as a result, it contracts. As a result, the force acting on the first piston 104 is absorbed by the second biasing member 110. In this way, the second biasing member 110 expands and contracts with the movement of the first piston 104, thereby attenuating the pressure pulsation.

3, the brake fluid in the space in the first fluid chamber S1 to the left of the first piston 104 passes through the second through hole 104f and is sent to the space in the first fluid chamber S1 to the right of the first piston 104. The inner diameter of the second through hole 104f is smaller than the inner diameter of the first through hole 104b, and the brake fluid flowing through the second through hole 104f is subjected to a large resistance. Therefore, the pressure pulsation is attenuated by the brake fluid flowing through the second through hole 104f.

In addition, the brake fluid in the space between the first piston 104 and the protruding member 109 is sent to the second fluid chamber S2 through the third through hole 109d. The brake fluid flowing through the third through hole 109d is also subjected to a large resistance, similar to the second through hole 104f. Therefore, the pressure pulsation is also attenuated by the brake fluid flowing through the third through hole 109d.

In addition, the brake fluid in the space in the second fluid chamber S2 to the left of the second piston 111 is sent through the fourth through hole 111c to the space in the second fluid chamber S2 to the right of the second piston 111. The brake fluid flowing through the fourth through hole 111c is also subjected to a large resistance, similar to the second through hole 104f and the third through hole 109d. Therefore, the pressure pulsation is also attenuated by the brake fluid flowing through the fourth through hole 111c.

3, the second valve body 115 is basically biased leftward by the fourth biasing member 116 and is in a closed state. However, there are cases where brake fluid is sent to the right of the second piston 111 via the fourth through hole 111c, and the pressure in the fourth hole portion 101d increases, causing the second valve body 115 to move rightward and temporarily open. In that case, the brake fluid passes through the fourth hole portion 101d and flows out from the third fluid chamber S3 via the outlet port P2.

4 is a diagram showing a state in which the first piston 104 has moved to the right in the damping device 100 compared to the state in FIG. 3. In the state in FIG. 4, the first piston 104 has moved to the right compared to the state in FIG. 3. Furthermore, in the state in FIG. 4, the second piston 111 is pressed to the right by the pressure in the space to the left of the second piston 111 in the second liquid chamber S2, and the second piston 111 has moved to the right compared to the state in FIG. 3. When the second piston 111 moves to the right, the third biasing member 113 and the third biasing member 114 expand and contract and ultimately shrink. As a result, the force acting on the second piston 111 is absorbed by the third biasing member 113 and the third biasing member 114. In this way, the third biasing member 113 and the third biasing member 114 expand and contract with the movement of the second piston 111, thereby attenuating the pressure pulsation.

In the state of FIG. 4, similarly to the state of FIG. 3, the second valve body 115 is basically in a closed state, but may be temporarily in an open state.

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

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

<Effects of the damping device>
The effects of the damping device 100 according to the embodiment of the present invention will be described.

The damping device 100 includes a first fluid chamber S1 communicating with the inlet port P1, a first piston 104 slidably arranged in the first fluid chamber S1 in a first sliding direction (in the above example, the axial direction of the housing 101) and having a first through hole 104b penetrating in the first sliding direction, a first valve body 106 capable of opening and closing the inlet port P1 side of the first through hole 104b, a first biasing member 108 biasing the first valve body 106 toward the outlet port P2, a protrusion member 109 arranged on the outlet port P2 side relative to the first valve body 106, extending in the first sliding direction, capable of being inserted into the first through hole 104b, and having a protrusion portion 109b capable of abutting against the first valve body 106, and a second biasing member 110 biasing the first piston 104 toward the inlet port P1.

As a result, when the pump 36 is driven and the pressure on the input port P1 side rises, the protrusion 109b of the protruding member 109 comes into contact with the first valve body 106, and pressure is stored in the space of the first fluid chamber S1 on the inlet port P1 side of the first piston 104 until the first valve body 106 is opened. During this time, the second biasing member 110 gradually contracts as the first piston 104 moves toward the output port P2 side, absorbing the energy of the pressure rise, and the pressure rise rate on the output port P2 side of the first piston 104 becomes slower than the pressure rise rate on the input port P1 side of the first piston 104. When the pressure on the input port P1 side falls and the first piston 104 moves toward the input port P1 side, the second biasing member 110 gradually expands, and the pressure drop rate on the output port P2 side of the first piston 104 becomes slower than the pressure drop rate on the input port P1 side of the first piston 104. As a result, the pressure pulsation on the output port P2 side can be attenuated relative to the pressure pulsation on the input port P1 side. In this manner, the damping device 100 can attenuate the pressure pulsation of the hydraulic control unit 15.

Preferably, in the damping device 100, the first piston 104 is formed with a second through hole 104f that penetrates from the inlet port P1 side to the outlet port P2 side and has an inner diameter smaller than the inner diameter of the first through hole 104b. As a result, the pressure pulsation can be damped by the brake fluid flowing through the second through hole 104f. Here, a situation in which the first piston 104 is stuck and cannot move is considered. In such a situation, the brake fluid can flow from the inlet port P1 side of the first piston 104 to the outlet port P2 side through the second through hole 104f. Therefore, the pressure in the space on the inlet port P1 side of the first piston 104 in the first fluid chamber S1 is suppressed from increasing excessively.

Preferably, in the damping device 100, a plurality of second through holes 104f are formed in the first piston 104, and the plurality of second through holes 104f are arranged at equal intervals in the circumferential direction of the first piston 104. As a result, a force generated due to the brake fluid flowing through the second through holes 104f acts evenly in the circumferential direction on the first piston 104. Therefore, the force acting on the first piston 104 due to the brake fluid flowing through the second through holes 104f suppresses the first piston 104 from tilting with respect to the first sliding direction.

Preferably, in the damping device 100, the protruding member 109 has a base 109a connected to the protruding portion 109b, and a third through hole 109d is formed in the base 109a, the third through hole 109d penetrating from the inlet port P1 side to the outlet port P2 side and having an inner diameter smaller than the inner diameter of the first through hole 104b. Thereby, the pressure pulsation can be damped by the brake fluid flowing through the third through hole 109d.

Preferably, in the damping device 100, a plurality of third through holes 109d are formed in the base 109a, and the plurality of third through holes 109d are arranged at equal intervals in the circumferential direction of the base 109a. This allows the flow field of the brake fluid to be uniform in the circumferential direction around the protruding member 109. Therefore, the brake fluid can flow smoothly in the damping device 100.

Preferably, the damping device 100 includes a second fluid chamber S2 that communicates with the first fluid chamber S1 and is disposed on the outlet port P2 side with respect to the protruding member 109, a second piston 111 that is provided slidably in the second sliding direction (in the above example, the axial direction of the housing 101) in the second fluid chamber S2, and third biasing members 113 and 114 that bias the second piston 111 toward the inlet port P1 side. As a result, the pressure pulsation can be damped by the third biasing member 113 and the third biasing member 114 expanding and contracting with the movement of the second piston 111, similar to the case where the second biasing member 110 expands and contracts with the movement of the first piston 104. Note that one of the third biasing member 113 and the third biasing member 114 may be omitted, and even in that case, the same effect as described above can be achieved.

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

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

Preferably, the damping device 100 includes a second fluid chamber S2 communicating with the first fluid chamber S1 and disposed on the outlet port P2 side with respect to the protruding member 109, a third fluid chamber S3 communicating with the second fluid chamber S2 via a fifth through hole (fourth hole portion 101d in the above example), disposed on the outlet port P2 side with respect to the second fluid chamber S2, and communicating with the outlet port P2, a second valve body 115 capable of opening and closing the outlet port P2 side of the fifth through hole, and a fourth biasing member 116 biasing the second valve body 115 toward the inlet port P1 side. Thereby, when the first through hole 104b is opened and the brake fluid is allowed to flow through the first through hole 104b, the fifth through hole is opened and the brake fluid can be appropriately discharged from the third fluid chamber S3 via the outlet port P2.

The above describes a preferred embodiment of the present invention with reference to the attached drawings. However, it goes without saying that the present invention is not limited to the above-described embodiment, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention.

The configuration of the damping device 100 has been described above with reference to Fig. 2. However, damping devices according to the present invention may also include those in which various modifications have been made to the example of Fig. 2.

For example, the first sliding direction, which is the sliding direction of the first piston 104, may be different from the axial direction of the housing 101. When the central axis of the first fluid chamber S1 is not arranged coaxially with the housing 101, the first sliding direction becomes the axial direction of the first fluid chamber S1, which is different from the axial direction of the housing 101.

Also, for example, the cross-sectional shape perpendicular to the first sliding direction of the first fluid chamber S1 and the first piston 104 does not have to be circular. The cross-sectional shape may be, for example, an elliptical shape or a polygonal shape. Note that even in this case, the circumferential direction of the first piston 104 is a direction along the outer circumferential edge of the first piston 104, and is a direction around the central axis of the first piston 104.

Also, for example, the cross-sectional shape perpendicular to the axial direction of the base 109a of the protrusion member 109 does not have to be circular. The cross-sectional shape may be, for example, an ellipse or a polygon. Even in this case, the circumferential direction of the base 109a is the direction along the outer periphery of the base 109a, and is the direction around the central axis of the base 109a.

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

Also, for example, the cross-sectional shape perpendicular to the second sliding direction of the second fluid chamber S2 and the second piston 111 does not have to be circular. The cross-sectional shape may be, for example, an elliptical shape or a polygonal shape. Note that even in this case, the circumferential direction of the second piston 111 is a direction along the outer circumferential edge of the second piston 111, and is a direction around the central axis of the second piston 111.

2, the damping device according to the present invention may also include a damping device in which the second piston 111, the second seal member 112, and the third biasing members 113 and 114 are omitted. In this case, the second fluid chamber S2 may also be omitted.

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

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

Claims (11)

A damping device (100) for damping pressure pulsation, the damping device (100) being provided in a hydraulic control unit (15) for controlling a braking force acting on a wheel (17), the damping device having an inlet port (P1) connected to a discharge side of a pump (36) and an outlet port (P2) communicating with the inlet port (P1),
a first liquid chamber (S1) communicating with the inlet port (P1);
a first piston (104) provided slidably in a first sliding direction in the first liquid chamber (S1) and having a first through hole (104b) penetrating in the first sliding direction;
a first valve body (106) capable of opening and closing the inlet port (P1) side of the first through hole (104b);
a first biasing member (108) that biases the first valve body (106) toward the outlet port (P2);
a protrusion member (109) disposed on the outlet port (P2) side with respect to the first valve body (106), extending in the first sliding direction, capable of being inserted into the first through hole (104b), and having a protrusion portion (109b) capable of coming into contact with the first valve body (106);
a second biasing member (110) that biases the first piston (104) toward the inlet port (P1);
Equipped with
Damping device. A second through hole (104f) is formed in the first piston (104), the second through hole (104f) penetrating from the inlet port (P1) side to the outlet port (P2) side and having an inner diameter smaller than the inner diameter of the first through hole (104b).
The damping device of claim 1 . The first piston (104) is formed with a plurality of the second through holes (104f),
The plurality of second through holes (104f) are arranged at equal intervals in the circumferential direction of the first piston (104).
The damping device of claim 2. The protruding member (109) has a base (109a) connected to the protruding portion (109b),
A third through hole (109d) is formed in the base portion (109a), the third through hole (109d) penetrating from the inlet port (P1) side to the outlet port (P2) side and having an inner diameter smaller than the inner diameter of the first through hole (104b).
A damping device according to any one of claims 1 to 3. A plurality of the third through holes (109d) are formed in the base portion (109a),
The third through holes (109d) are arranged at equal intervals in the circumferential direction of the base portion (109a).
The damping device of claim 4. a second liquid chamber (S2) communicating with the first liquid chamber (S1) and disposed on the outlet port (P2) side with respect to the protruding member (109);
a second piston (111) slidably provided in the second liquid chamber (S2) in a second sliding direction;
a third biasing member (113, 114) that biases the second piston (111) toward the inlet port (P1);
Equipped with
The damping device of claim 1 . The second piston (111) is formed with a fourth through hole (111c) that penetrates from the inlet port (P1) side to the outlet port (P2) side and has an inner diameter smaller than the inner diameter of the first through hole (104b).
The damping device of claim 6. The second piston (111) is formed with a plurality of the fourth through holes (111c),
The plurality of fourth through holes (111c) are arranged at equal intervals in the circumferential direction of the second piston (111).
The damping device of claim 7. a second liquid chamber (S2) communicating with the first liquid chamber (S1) and disposed on the outlet port (P2) side with respect to the protruding member (109);
a third liquid chamber (S3) communicating with the second liquid chamber (S2) via a fifth through hole (101d), disposed on the outlet port (P2) side with respect to the second liquid chamber (S2), and communicating with the outlet port (P2);
a second valve body (115) capable of opening and closing the outlet port (P2) side of the fifth through hole (101d);
a fourth biasing member (116) that biases the second valve body (115) toward the inlet port (P1);
Equipped with
The damping device of claim 1 . A hydraulic control unit comprising a damping device (100) according to claim 1 . A brake system comprising a hydraulic control unit (15) according to claim 10.

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