JP7546161B2 - Pulsation reduction device and vehicle brake fluid pressure control device equipped with said pulsation reduction device - Google Patents

Description

The present invention relates to a pulsation reduction device that reduces pulsation of brake fluid pressure in a brake fluid pressure circuit of a vehicle, and to a vehicle brake fluid pressure control device equipped with the pulsation reduction device.

Conventionally, brake fluid pressure control devices for controlling the brake fluid pressure of a brake system in a vehicle include a brake fluid pressure circuit that connects brake fluid pressure between a master cylinder and wheel cylinders of the vehicle, a pump that increases the brake fluid pressure in the brake fluid pressure circuit, and an electromagnetic valve that connects and cuts off the brake fluid pressure in the brake fluid pressure circuit, and are configured to drive and control the pump to increase the brake fluid pressure supplied to the wheel cylinder when it becomes necessary to increase the brake fluid pressure supplied to the wheel cylinder, regardless of the state of operation of the vehicle's brake pedal by the driver (see, for example, Patent Document 1, etc.).

JP 2017-061246 A

In a brake fluid pressure control device as described in Patent Document 1, pulsation of the brake fluid pressure caused by driving the pump is transmitted from the brake system to the engine room of the vehicle, etc., and there is a risk of noise being generated that may cause discomfort or strangeness to the driver of the vehicle (e.g., the driver of the vehicle, passengers, people outside the vehicle, etc.). In response to this, the brake fluid pressure control device is provided with a volume chamber whose volume is variable by having a diaphragm that elastically deforms with changes in brake fluid pressure, and the pulsation of the brake fluid pressure caused by driving the pump can be reduced. However, in recent brake systems, the drive of the pump is controlled at a higher rotation speed, etc., which may increase the pulsation of the brake fluid pressure, and therefore there is a demand for further reduction in the pulsation of the brake fluid pressure.

The present invention has been made in light of the above-mentioned problems, and has an object to provide a brake fluid pressure control device that can reduce pulsation of brake fluid pressure in a vehicle brake fluid pressure circuit.

The pulsation reduction device according to the present invention is a pulsation reduction device (37, 80) that is provided in a brake system of a vehicle including a brake fluid pressure circuit (2) that supplies brake fluid pressure to a wheel cylinder (12) and a pump (60) that boosts the brake fluid pressure, and that reduces pulsation of the brake fluid pressure in the brake fluid pressure circuit (2). The pulsation reduction device (37, 80) includes a first chamber (A) to which brake fluid pressure is input from the brake fluid pressure circuit (2), a second chamber (B) connected to the first chamber (A), a third chamber (C) connected to the second chamber (B) and outputting brake fluid pressure to the brake fluid pressure circuit (2), a first connection part that connects the first chamber (A) and the second chamber (B), and a second connection part that connects the second chamber (B) and the third chamber (C), and the first connection part is a first valve seat (8 the second connection portion includes a first valve body (87) which moves between a non-connecting position where it seats on the first valve seat (83 d) and does not connect the first chamber (A) and the second chamber (B) and a connecting position where it leaves the first valve seat (84 b) and connects the first chamber (A) and the second chamber (B); the second connection portion includes a second valve body (94 b) which moves between a non-connecting position where it seats on the second valve seat (83 d) and does not connect the second chamber (B) and the third chamber (C) and a connecting position where it leaves the second valve seat (83 d) and connects the second chamber (B) and the third chamber (C); and the second chamber (B) includes an elastic member (90) which elastically changes in accordance with a change in the brake fluid pressure in the second chamber (B), and which reduces in volume when the brake fluid pressure rises and expands in volume when the brake fluid pressure drops.

According to this configuration, the elastic member (90) contained in the second chamber (B) can absorb sudden pressure fluctuations accompanying operation of the first valve body (87) and the second valve body (94b), thereby reducing pulsations of the brake fluid pressure in the vehicle's brake fluid pressure circuit.

In addition, the present invention may have only the invention-specific matters described in the claims of the present invention, or may have the invention-specific matters described in the claims of the present invention as well as configurations other than the invention-specific matters.

FIG. 2 is a diagram for explaining a configuration of a brake system according to an embodiment. 3A and 3B are diagrams for explaining a pump and a pulsation reduction device. 11 is a diagram for explaining the pulsation reduction device (pump non-driven state). FIG. 11 is a diagram for explaining the pulsation reduction device (pump driving state). FIG. 11 is a diagram for explaining the pulsation reduction device (pump driving state). FIG. 11A and 11B are diagrams for explaining the relationship between the displacement and restoring force of a biasing member.

An embodiment of a brake fluid pressure control device according to the present invention and a brake system including the brake fluid pressure control device will be described with reference to the drawings. In the following, the same or similar descriptions may be appropriately simplified or omitted. In addition, in each drawing, the same or similar members or parts may not be labeled with a reference number, or may be labeled with the same reference number. In addition, illustrations of detailed structures may be appropriately simplified or omitted.

The configuration, operation, etc. of the embodiment described below are merely examples. The present invention is not limited to such configurations, operations, etc., and can be modified as appropriate within the scope of the present invention. For example, the brake system 1 and the brake fluid pressure control device 50 of the present embodiment are configured to be mounted on a four-wheeled vehicle, but the brake fluid pressure control device according to the present invention and the brake system including the brake fluid pressure control device may be configured to be mounted on vehicles other than four-wheeled vehicles, such as one-wheeled vehicles, two-wheeled vehicles, three-wheeled vehicles, trucks, buses, construction vehicles, etc.

[Regarding Brake System 1]
A brake system 1 according to this embodiment will be described with reference to Figures 1 and 2. The brake system 1 is a system that controls braking of each wheel provided on a vehicle 100, which is a four-wheeled vehicle.

As shown in FIG. 1, the brake system 1 includes a master cylinder 11 incorporating a piston (not shown) that reciprocates in conjunction with a brake pedal 16 provided on the vehicle, wheel cylinders 12 provided corresponding to each wheel of the four-wheeled vehicle and generating a braking force for each wheel, and a brake fluid pressure control device 50 that controls the brake fluid pressure supplied to each wheel cylinder 12 independently from the state of the brake operation by the vehicle driver.

A booster 17 is provided between the brake pedal 16 and the piston of the master cylinder 11, so that the driver's depressing force transmitted to the brake pedal 16 is boosted and transmitted to the piston of the master cylinder 11. The wheel cylinder 12 is provided in a brake caliper 18. When the hydraulic pressure of the brake fluid in the wheel cylinder 12 increases, a brake pad 19 of the brake caliper 18 is pressed against a rotor 20, braking the wheel.

The brake fluid pressure control device 50 includes a base 51 in which a hydraulic circuit 2 for brake fluid is formed, which connects brake fluid pressure between a master cylinder 11 and a wheel cylinder 12. The hydraulic circuit 2 is formed inside the base 51 and includes a main flow path 13 that connects the master cylinder 11 and the wheel cylinder 12, a secondary flow path 14 that releases brake fluid from the main flow path 13, and a supply flow path 15 that supplies brake fluid to the secondary flow path 14. The hydraulic circuit 2 is filled with brake fluid.

The brake system 1 according to this embodiment includes two hydraulic circuits 2a and 2b as the hydraulic circuit 2. The hydraulic circuit 2a is a hydraulic circuit that connects the master cylinder 11 to the wheel cylinders 12 of the wheels RL and FR via a main flow path 13. The hydraulic circuit 2b is a hydraulic circuit that connects the master cylinder 11 to the wheel cylinders 12 of the wheels FL and RR via a main flow path 13. These hydraulic circuits 2a and 2b have the same configuration except for the wheel cylinders 12 that they connect to.

The upstream end of the sub-flow passage 14 is connected to the midway portion 13a of the main flow passage 13, and the downstream end of the sub-flow passage 14 is connected to the midway portion 13b of the main flow passage 13. In addition, the upstream end of the supply flow passage 15 communicates with the master cylinder 11, and the downstream end of the supply flow passage 15 is connected to the midway portion 14a of the sub-flow passage 14.

In addition, the upstream side of the secondary flow path 14 refers to the upstream side of the flow of brake fluid when the pump is driven and the brake fluid is returned from the wheel cylinder to the master cylinder, and the downstream side refers to the downstream side of that flow of brake fluid.

An inlet valve (EV) 31 is provided in a region of the main flow path 13 between the midway portion 13b and the midway portion 13a (a region on the wheel cylinder 12 side with the midway portion 13b as a reference). A release valve (AV) 32 is provided in a region of the secondary flow path 14 between the midway portion 13a and the midway portion 14a. An accumulator 33 is provided in a region of the secondary flow path 14 between the release valve 32 and the midway portion 14a. The inlet valve 31 is, for example, a solenoid valve that opens in a non-energized state and closes in a powered state. The release valve 32 is, for example, a solenoid valve that closes in a non-energized state and opens in a powered state.

A pump 60 is provided in a region of the secondary flow path 14 between the intermediate portion 14a and the intermediate portion 13b. The suction side of the pump 60 is connected to the intermediate portion 14a. The discharge side of the pump 60 is connected to the intermediate portion 13b of the secondary flow path 14. In detail, the brake system 1 includes an intake flow path 142 and a discharge flow path 140, which are parts of the secondary flow path 14, as components of the brake fluid pressure control device 50. The intake flow path 142 constitutes a flow path between the intermediate portion 13a of the secondary flow path 14 and the intake side of the pump 60, and the discharge flow path 140 constitutes a flow path between the discharge side of the pump 60 and the intermediate portion 13b of the secondary flow path 14.

Here, the brake fluid pressure control device 50 is provided with a pulsation reducing section 80 on the discharge flow path 140, which attenuates the pulsation of the brake fluid discharged from the pump 60. In detail, the discharge side of the pump 60 is connected to an inflow opening 91b (see FIG. 2) into which the brake fluid of the pulsation reducing section 80 flows, and an outflow opening 91c (see FIG. 2) from which the brake fluid temporarily stored in the pulsation reducing section 80 flows out is connected to the middle portion 13b of the sub-flow path. In the following description, the flow path between the discharge side of the pump and the inflow opening 91b may be referred to as a first discharge flow path 140a, and the flow path between the outflow opening 91c and the middle portion 13b of the sub-flow path may be referred to as a second discharge flow path 140b.

A first switching valve (USV) 35 is provided in a region of the main flow path 13 on the master cylinder 11 side with respect to the intermediate portion 13b. A second switching valve (HSV) 36 and a damper unit 37 are provided in the supply flow path 15. The damper unit 37 is provided in a region of the supply flow path 15 between the second switching valve 36 and the intermediate portion 13b. The first switching valve 35 is, for example, an electromagnetic valve that opens in a non-energized state and closes in an energized state. The second switching valve 36 is, for example, an electromagnetic valve that closes in a non-energized state and opens in an energized state. In this embodiment, a configuration is shown in which the damper unit 37 and the pulsation reduction unit 80 are provided as pulsation reduction devices in both the discharge flow path 140 and the supply flow path 15, but the damper unit 37 may not be provided depending on the installation space and the required pulsation damping characteristics.

The inlet valve 31, the release valve 32, the accumulator 33, the pump 60, the first switching valve 35, the second switching valve 36, the damper unit 37, and the pulsation reduction section 80 are provided on a base 51 having therein passages formed for constituting the main passage 13, the sub passage 14, and the supply passage 15. The respective components (the inlet valve 31, the release valve 32, the accumulator 33, the pump 60, the first switching valve 35, the second switching valve 36, the damper unit 37, and the pulsation reduction section 80) may be provided collectively on one base 51, or may be provided separately on a plurality of bases 51.

Brake fluid pressure control device 50 is constituted by at least base 51, each member provided on base 51, and controller 52. In brake fluid pressure control device 50, the operation of inlet valve 31, release valve 32, pump 60, first switch valve 35, and second switch valve 36 is controlled by controller 52, thereby controlling the hydraulic pressure of the brake fluid in wheel cylinder 12. In other words, controller 52 governs the operation of inlet valve 31, release valve 32, pump 60, first switch valve 35, and second switch valve 36.

The controller 52 may be one or multiple. The controller 52 may be attached to the base 51 or may be attached to another member. A part or all of the controller 52 may be configured, for example, by a microcomputer, a microprocessor unit, or the like, may be configured by updatable firmware, or may be a program module executed by a command from a CPU, or the like.

The controller 52 performs the following hydraulic control operations in addition to known hydraulic control operations (ABS control operations, ESP control operations, etc.).

When the brake pedal 16 of the vehicle 100 is operated with the inlet valve 31 open, the release valve 32 closed, the first switching valve 35 open, and the second switching valve 36 closed, if a lack or possible lack of hydraulic pressure in the hydraulic circuit 2 is detected from the detection signal of the position sensor of the brake pedal 16 and the detection signal of the hydraulic pressure sensor in the hydraulic circuit 2, the controller 52 commences active pressure boost control operation.

In the active pressure boosting control operation, the controller 52 allows the brake fluid to flow from the intermediate portion 13b of the main flow passage 13 to the wheel cylinder 12 by keeping the inlet valve 31 open. The controller 52 also restricts the flow of brake fluid from the wheel cylinder 12 to the accumulator 33 by keeping the release valve 32 closed. The controller 52 also restricts the flow of brake fluid in the flow passage from the master cylinder 11 to the intermediate portion 13b of the main flow passage 13 without passing through the pump 60 by closing the first switching valve 35. The controller 52 also allows the brake fluid to flow in the flow passage from the master cylinder 11 to the intermediate portion 13b of the main flow passage 13 via the pump 60 by opening the second switching valve 36. The controller 52 also drives the pump 60 to increase (increase) the hydraulic pressure of the brake fluid in the wheel cylinder 12.

When it is detected that the hydraulic pressure deficiency in the hydraulic circuit 2 has been resolved or avoided, the controller 52 opens the first switching valve 35, closes the second switching valve 36, and stops driving the pump 60, thereby terminating the active pressure boost control operation.

Here, when the pump 60 is driven, the pulsation generated in the brake fluid may be transmitted to the wheel cylinder 12 through the sub-flow path 14 and the main flow path 13. In addition, the pulsation may be transmitted to the engine room that houses the brake fluid pressure control device 50 of the brake system 1, causing noise. This noise may be loud enough to cause discomfort to the driver, etc. For this reason, it is important to reduce the pulsation generated when the pump 60 is driven.

Therefore, in the brake fluid pressure control device 50 of the brake system 1 of this embodiment, the brake fluid discharged from the pump 60 flows into the pulsation reduction section 80. Then, the brake fluid that has flowed into the pulsation reduction section 80 has its pulsation reduced in the pulsation reduction section 80, and then flows downstream of the pulsation reduction section 80. Therefore, the brake fluid pressure control device 50 of this embodiment is capable of reducing the pulsation that occurs when the pump 60 is driven.

In the above-described active pressure increase control, the user operates the brake pedal 16, and the pump 60 is driven with the second switching valve 36 open. As a result, pulsation generated in the brake fluid is transmitted to the brake pedal 16 via the supply flow path 15 and the master cylinder 11, causing the user to feel uncomfortable. For this reason, the brake fluid pressure control device 50 of this embodiment preferably includes a damper unit 37 as shown in Fig. 1. The damper unit 37 can reduce the pulsation of the brake fluid transmitted from the pump 60 to the brake pedal 16.

In addition, when the damper unit 37 is provided in the brake system 1 in which the booster 17 is omitted, the damper unit 37 may be provided in a region between the upstream end of the supply flow passage 15 and the second switching valve 36. By providing the damper unit 37 in such a position, when the user depresses the brake pedal 16 to operate it, the brake fluid can flow into the damper unit 37, and the reaction force of the brake fluid in the hydraulic circuit 2 transmitted to the brake pedal 16 is reduced. Therefore, when the user operates the brake pedal, the operation amount of the brake pedal 16 is obtained similar to that of the brake system 1 equipped with the booster 17. Therefore, the user can obtain the same feeling of use in the brake system 1 in which the booster 17 is omitted as in the brake system 1 equipped with the booster 17.

[Regarding pump 60]
The pump 60 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a partial cross-sectional view of the base 51 of the brake fluid pressure control device 50, on which the pump 60 and the pulsation reduction unit 80 are mounted, and in a state in which the drive shaft 57 that drives the piston 62 of the pump 60 has been removed. The two-dot chain line in Fig. 2 indicates the drive shaft 57 and the eccentric portion 57a formed on the drive shaft 57.

2, the base 51 is formed with an accommodation chamber 59 in which a drive shaft 57 for driving a piston 62 of the pump 60 is provided. The accommodation chamber 59 is a bottomed hole formed in the outer wall of the base 51. The base 51 is also formed with an accommodation chamber 53 for accommodating the pump 60. The accommodation chamber 53 is a stepped through hole that penetrates from the outer wall of the base 51 to the accommodation chamber 59.

The pump 60 accommodated in the accommodation chamber 53 includes a cylinder 61, a piston 62, and the like. The cylinder 61 is formed in a bottomed cylindrical shape having a bottom 61b. One end side of the piston 62 is accommodated in the cylinder 61. A space surrounded by the inner peripheral surface of the cylinder 61 and the one end of the piston 62 becomes a pump chamber 63. The piston 62 is capable of reciprocating in the axial direction of the cylinder 61. An end 62a, which is the end on the other end side of the piston 62, protrudes into the accommodation chamber 59. Furthermore, an annular seal member 66 is attached to a portion of the piston 62 accommodated in the cylinder 61. The seal member 66 prevents leakage of brake fluid between the outer peripheral surface of the piston 62 and the inner peripheral surface of the cylinder 61.

Further, a spring 67 is accommodated in the cylinder 61 between the bottom 61b and the piston 62, i.e., in the pump chamber 63. The spring 67 constantly biases the piston 62 toward the accommodation chamber 59. As a result, an end 62a of the piston 62 abuts against an eccentric portion 57a formed on the drive shaft 57 in the accommodation chamber 59. The central position of the eccentric portion 57a is eccentric with respect to the center of rotation of the drive shaft 57. Therefore, when the drive shaft 57 is rotated by a drive source (not shown), the eccentric portion 57a rotates eccentrically with respect to the center of rotation of the drive shaft 57. That is, as a result of the eccentric rotation of the eccentric portion 57a, the piston 62, whose end 62a abuts against the eccentric portion 57a, reciprocates in the axial direction of the cylinder 61.

The portion of the piston 62 protruding from the cylinder 61 is slidably guided by a guide member 68 provided on the inner circumferential surface of the accommodation chamber 53. In addition, an annular seal member 69 is attached to the accommodation chamber 53 adjacent to the guide member 68. This seal member 69 provides a liquid-tight seal against outflow from the outer circumferential surface of the piston 62.

The piston 62 is formed with a bottomed hole 62b that opens axially toward the pump chamber 63 of the cylinder 61. The piston 62 is also formed with a suction port 62c, which is a through hole that communicates the outer circumferential surface of the piston 62 with the bottomed hole 62b. The piston 62 is also provided with a suction valve (not shown) that closes the opening of the bottomed hole 62b in an openable and closable manner. The suction valve includes a ball valve that closes the opening of the bottomed hole 62b and a spring that biases the ball valve from the cylinder 61 side. A cylindrical filter 70 is attached to the end of the cylinder 61 on the piston 62 side so as to cover the opening of the suction port 62c of the piston 62.

A through hole 61c is formed in the bottom 61b of the cylinder 61, communicating the pump chamber 63 with the outside of the cylinder 61. A discharge valve 64 is provided at the opening side of the through hole 61c opposite the pump chamber 63. The discharge valve 64 includes a ball valve 64a, a valve seat 64b formed on the periphery of the open end of the through hole 61c and on which the ball valve 64a can be seated and separated, and a spring 64c that biases the ball valve 64a in a direction to seat it on the valve seat 64b. The discharge valve 64 is disposed between the cylinder 61 and the cover 65.

Specifically, the cover 65 is attached to the bottom 61b of the cylinder 61 by, for example, press fitting. The cover 65 is formed with a bottomed hole 65a having an opening at a position opposite to the through hole 61c of the bottom 61b. The spring 64c of the discharge valve 64 is accommodated in the bottomed hole 65a. The inner diameter of the bottomed hole 65a is larger than the outer diameter of the ball valve 64a. Therefore, when the ball valve 64a leaves the valve seat 64b, the ball valve 64a moves into the bottomed hole 65a. That is, when the hydraulic pressure of the brake fluid in the pump chamber 63 of the cylinder 61 increases and the force of the brake fluid pressing the ball valve 64a becomes larger than the biasing force of the spring 64c, the ball valve 64a leaves the valve seat 64b, and the pump chamber 63 and the bottomed hole 65a of the cover 65 communicate with each other via the through hole 61c. The brake fluid in the pump chamber 63 then flows into the bottomed hole 65a. A groove that connects the bottomed hole 65a to the outside of the cover 65 is formed in the cover 65 as a discharge port 65b. The brake fluid that has flowed into the bottomed hole 65a of the cover 65 is discharged from the discharge port 65b to the outside of the cover 65, i.e., the outside of the pump 60 (for example, a flow path continuing to the pulsation reduction unit 80).

As described above, the pump 60 configured in this manner is accommodated in the accommodation chamber 53 formed in the base body 51. Specifically, with the annular protrusion 61a formed on the outer periphery of the cylinder 61 abutting against the step 53a of the accommodation chamber 53, the periphery of the opening of the accommodation chamber 53 is crimped, whereby the pump 60 is fixed within the accommodation chamber 53 of the base body 51.

When the pump 60 is accommodated in the accommodation chamber 53 in this manner, a discharge chamber 54, which is a space that communicates with the discharge port 65b of the pump 60, is formed between the outer circumferential surface of the pump 60 and the inner circumferential surface of the accommodation chamber 53. That is, the discharge chamber 54 is a space that is formed in an annular shape on the outer circumferential side of the pump 60 so as to communicate with the discharge port 65b of the pump 60. The discharge chamber 54 constitutes a part of the first discharge flow path 140a, as described below.

In the pump 60, the space between the annular protrusion 61a of the cylinder 61 and the cover 65 is divided into two spaces by the partition 71. The space on the cover 65 side of the partition 71 is the discharge chamber 54. The space on the protrusion 61a side of the partition 71 is the annular flow path 55. As shown in FIG. 3, in this embodiment, the partition 71 is formed by a protrusion protruding in an annular shape on the outer circumferential surface of the cylinder 61 and an O-ring provided on the protrusion. However, as long as the space between the annular protrusion 61a of the cylinder 61 and the cover 65 can be divided into two spaces, the configuration of the partition 71 is arbitrary. For example, the partition 71 may be formed only by a protrusion protruding in an annular shape on the outer circumferential surface of the cylinder 61. For example, the partition 71 may be formed only by an O-ring provided on the outer circumferential surface of the cylinder 61.

In this embodiment, when the pump 60 is accommodated in the accommodation chamber 53, an annular flow passage 56, which is a space communicating with the suction port 62c of the pump 60, is formed between the outer circumferential surface of the pump 60 and the inner circumferential surface of the accommodation chamber 53. That is, the annular flow passage 56 is a space formed in an annular shape on the outer circumferential side of the pump 60 so as to communicate with the suction port 62c of the pump 60. The annular flow passage 56 is formed between the annular protrusion 61a of the cylinder 61 and the seal member 69. In other words, the annular flow passage 56 is formed on the outer circumferential side of the filter 70 provided so as to cover the opening of the suction port 62c.

The annular flow passage 56 communicates with the intermediate portion 14a of the secondary flow passage 14 in FIG. 1 through an internal flow passage (not shown) formed in the base 51. In other words, the annular flow passage 56 constitutes a part of the secondary flow passage 14. When the pump 60 is accommodated in the accommodation chamber 53, the suction port 62c of the pump 60 and the intermediate portion 14a must communicate with each other. By providing the annular flow passage 56, when the pump 60 is accommodated in the accommodation chamber 53, alignment for communicating the suction port 62c of the pump 60 with the intermediate portion 14a is not required. Therefore, by providing the annular flow passage 56, the brake fluid pressure control device 50 can be easily assembled. In addition, by providing the annular flow passage 56, when the accommodation chamber 53 is processed in the base 51, a part of the secondary flow passage 14 is also processed. Therefore, the processing cost of the base 51, i.e., the manufacturing cost of the brake fluid pressure control device 50 can be reduced. Furthermore, by providing the annular flow passage 56, the space on the outer periphery of the pump 60 can be effectively used as the sub-flow passage 14, so that the base body 51, i.e., the brake fluid pressure control device 50, can be made smaller in size.

As described above, the discharge chamber 54 formed on the outer peripheral surface side of the pump 60 is connected to the first discharge flow passage 140a constituting a part of the discharge flow passage 140. The accommodation chamber 58 is an accommodation chamber that accommodates the pulsation reduction part 80, and is a bottomed hole formed in the outer wall of the base body 51. The discharge chamber 54 is connected to the inflow opening 91b of the pulsation reduction part 80 via the first discharge flow passage 140a. In the figure, the brake fluid is configured to flow in from a lateral direction with respect to the axis of the accommodation chamber 58 of the pulsation reduction part 80. The outflow opening 91c located at the bottom of the accommodation chamber 58 is connected to the second discharge flow passage 140b. The second discharge flow passage 140b is connected to the middle part 13b of the main flow passage 13 in FIG. 1 by an internal flow passage (not shown) formed in the base body 51.

In the case where the pump 60 and the pulsation reducer 80 are mounted on the base body 51 as shown in FIG. 2, when the pump 60 is driven, the brake fluid flows as follows.

When the drive shaft 57 is rotated by a drive source (not shown) and the eccentric portion 57a formed on the drive shaft 57 moves toward the piston 62, the piston 62 is pressed toward the cylinder 61 against the biasing force of the spring 67. As a result, the pressure in the pump chamber 63 increases, causing the ball valve 64a to leave the valve seat 64b and open the discharge valve 64. As a result, the brake fluid in the pump chamber 63 passes through the through hole 61c and the bottomed hole 65a of the cover 65 and is discharged from the discharge port 65b to the discharge chamber 54.

When the drive shaft 57 further rotates and the eccentric portion 57a formed on the drive shaft 57 starts to rotate in a direction away from the piston 62, the piston 62 moves in a direction away from the cylinder 61 due to the biasing force of the spring 67. As a result, the pressure in the pump chamber 63 decreases, and the ball valve 64a seats on the valve seat 64b, closing the discharge valve 64, and opening the suction valve (not shown) which freely closes the opening of the bottomed hole 62b of the piston 62. As a result, the brake fluid in the annular flow passage 56 flows into the pump chamber 63 through the filter 70, the suction port 62c, and the bottomed hole 62b.

When the drive shaft 57 further rotates and the eccentric portion 57a formed on the drive shaft 57 moves toward the piston 62 again, the piston 62 is pressed toward the cylinder 61 as described above, and the brake fluid in the pump chamber 63 is discharged from the discharge port 65b to the discharge chamber 54. In this manner, the piston 62 repeatedly reciprocates in the axial direction of the cylinder 61, and the suction valve and discharge valve 64 (not shown) are selectively opened and closed, so that the brake fluid whose fluid pressure has increased, i.e., whose pressure has been increased, is discharged from the discharge port 65b to the discharge chamber 54. For this reason, pulsation occurs in the brake fluid pressurized by the pump 60. The brake fluid with this pulsation flows into the pulsation reduction unit 80 via the first discharge flow path 140a.

[About the pulsation reduction device]
The pulsation reduction device according to this embodiment will be described with reference to Figures 3 to 6. Note that the configuration of the pulsation reduction device described below will be described using an example in which it is applied to the pulsation reduction section 80, but the configuration may be applied to both the damper unit 37 and the pulsation reduction section 80, or to only one of the damper unit 37 and the pulsation reduction section 80. In addition, in this embodiment, the brake hydraulic circuit 2 is configured to include the damper unit 37 and the pulsation reduction section 80 as the pulsation reduction device, but the brake hydraulic circuit 2 may be configured to include only the pulsation reduction section 80 as the pulsation reduction device. Hereinafter, the damper unit 37 and the pulsation reduction section 80 may be collectively referred to as the pulsation reduction device.

As shown in Fig. 3, the base 51 of the brake fluid pressure control device 50 is provided with an accommodation chamber 58 formed by a cylindrical hole drilled along the axis Ax1 and accommodating the pulsation reducer 80. The accommodation chamber 58 includes a large diameter portion 58a formed on the outer circumferential surface side of the base 51 and a small diameter portion 58b having a smaller diameter than the large diameter portion 58a and formed on the inner side of the base 51 than the large diameter portion 58a. The large diameter portion 58a and the small diameter portion 58b are drilled with the axis Ax1 as a common central axis. An opening 58d of the accommodation chamber 58 continuing to the outer circumferential surface of the base 51 is blocked by a blocking member 81.

The accommodation chamber 58 includes a first partition member 82 having a disk portion 82a with an outer diameter substantially equal to the inner diameter of the large diameter portion 58a, and a second partition member 83 having a disk portion 83a with an outer diameter substantially equal to the inner diameter of the small diameter portion 58b. The first partition member 82 is fitted along the inner circumferential surface of the large diameter portion 58a on the small diameter portion 58b side relative to the inflow opening 91b inside the large diameter portion 58a, and the second partition member 83 is fitted along the inner circumferential surface of the small diameter portion 58b at a predetermined interval from the connection portion between the large diameter portion 58a and the small diameter portion 58b.

By fitting and arranging the first partition member 82 inside the accommodation chamber 58, a first chamber A is formed in the accommodation chamber 58, which is partitioned by the blocking member 81, the inner circumferential surface of the large diameter portion 58a, and the first partition member 82. By fitting and arranging the first partition member 82 and the second partition member 83 inside the accommodation chamber 58, a second chamber B is formed in the accommodation chamber 58, which is partitioned by the first partition member 82, the inner circumferential surface of the small diameter portion 58b, and the second partition member 83. By fitting and arranging the second partition member 83 inside the accommodation chamber 58, a third chamber C is formed in the accommodation chamber 58, which is partitioned by the second partition member 83 and the bottom surface 58c of the small diameter portion 58b.

An inflow opening 91b is provided on the side surface of the large diameter portion 58a, through which the brake fluid F1 compressed by the pump 60 and discharged from the discharge port 65b flows in, so that the brake fluid pressure is input from the pump 60 to the first chamber A. In addition, an outflow opening 91c is provided on the bottom surface 58c of the small diameter portion 58b, which communicates with the main flow path 13 and allows the brake fluid F2 to flow out from the pulsation reduction portion 80 to the main flow path 13, so that the brake fluid pressure in the third chamber C is output to the main flow path 13.

The first partition member 82 comprises a disk portion 82a, an edge portion 82b formed on the outer edge portion of the disk portion 82a and extending along the inner surface of the large diameter portion 58a toward the opening 58d of the accommodating chamber 58 when the first partition member 82 is fitted into the large diameter portion 58a, a protrusion 82c formed in a central portion of the disk portion 82a and extending so as to protrude along the axis Ax1 toward the opening 58d of the accommodating chamber 58 when the first partition member 82 is fitted into the large diameter portion 58a, and a communication hole 82d provided in the region between the edge portion 82b and the protrusion 82c in the disk portion 82a, and communicating from the first chamber A side to the second chamber B side, i.e., from the large diameter portion 58a side to the small diameter portion 58b side, when the first partition member 82 is fitted into the large diameter portion 58a. At least one communication hole 82d is formed in the region between the edge portion 82b and the protruding portion 82c. The first partition member 82 may be configured to have one communication hole 82d or a plurality of communication holes 82d.

The second partition member 83 is made up of a disk portion 83a, an edge portion 83b formed on the outer edge portion of the disk portion 83a and extending along the inner circumferential surface of the small diameter portion 58b when the second partition member 83 is fitted into the small diameter portion 58b, and a center portion of the disk portion 83a and extending from the second chamber B side to the third chamber C side, i.e., the large diameter portion 58a side and the small diameter portion 58b side when the second partition member 83 is fitted into the small diameter portion 58b. a second valve seat 83d formed on the third chamber C side of the communicating hole 83c, i.e., on the bottom surface 58c side of the small diameter portion 58b, and seated and released by a second valve body 94b described below; and an annular groove portion 83e formed on the edge portion of the second chamber B side of the disk portion 83a, i.e., on the large diameter portion 58a side, when the second partition member 83 is fitted into the small diameter portion 58b.

In the pulsation reduction section 80, the first partition member 82 has a communication hole 82d, which connects the first chamber A and the second chamber B, and the second partition member 83 has a communication hole 83c, which connects the second chamber B and the third chamber C. By connecting the first chamber A and the second chamber B, and the second chamber B and the third chamber C, respectively, the brake fluid that has flowed into the first chamber A from the inlet opening 91b passes through the second chamber B and the third chamber C and flows out from the outlet opening 91c.

Inside the first chamber A, i.e., the large diameter portion 58a, there are arranged a first moving body 84 which is formed in a disk shape with an outer diameter approximately equal to the inner diameter of the large diameter portion 58a and moves in the direction of the axis Ax1, a sealing member 85 which seals between the outer peripheral surface of the first moving body 84 and the inner peripheral surface of the large diameter portion 58a, a first biasing member 86 which is arranged between the first moving body 84 and the first partition member 82 and biases the first moving body 84 toward the blocking member 81, a spherical first valve body 87 which is arranged at the tip portion of the protrusion 82c of the first partition member 82 and seats and releases from the first valve seat 84b described below, a surrounding member 88 which is fixed to the first moving body 84 and surrounds the first valve body 87, and a second biasing member 89 which is arranged between the first valve body 87 and the surrounding member 88 and biases the surrounding member 88 toward the blocking member 81.

The first movable body 84 has a seal member 85 disposed on its outer circumferential surface, and slides in the direction of the axis Ax1 along the inner circumferential surface of the large diameter portion 58a on the side of the small diameter portion 58b from the inlet opening 91b, with the seal member 85 interposed therebetween. For example, PTFE can be used as the material of the seal member 85 in order to ensure smooth sliding.

The outer peripheral surface of the first moving body 84 and the inner peripheral surface of the large diameter portion 58a are sealed by the seal member 85, and the first chamber A is divided into two regions by the first moving body 84 and the seal member 85, forming a first region A1 defined by the inner peripheral surface of the large diameter portion 58a, one end face of the blocking member 81, and one end face of the first moving body 84 facing the one end face of the blocking member 81, and forming a second region A2 defined by the inner peripheral surface of the large diameter portion 58a, one end face of the first moving body 84, and one end face of the first partition member 82 facing the one end face of the first moving body 84. When the first moving body 84 moves toward the blocking member 81, the volume of the first region A1 is reduced and the volume of the second region A2 is increased, while when the first moving body 84 moves toward the first partition member 82, the volume of the first region A1 is increased and the volume of the second region A2 is reduced.

Further, a communication hole 84a is provided in the center of the first moving body 84, which communicates from the first area A1 side to the second area A2 side, i.e., from the blocking member 81 side to the first partition member 82 side. A first valve seat 84b on which the first valve body 87 is seated and separated is formed at the end of the communication hole 84a on the first area A1 side. The first valve seat 84b is surrounded by a surrounding member 88 together with the first valve body 87. The surrounding member 88 is fixed to the first moving body 84. A communication hole 88a is provided in the peripheral surface of the surrounding member 88, which communicates from the inside side to the outside side of the surrounding member 88, and the brake fluid pressure input from the inlet opening 91b reaches the first valve seat 84b through the communication hole 88a, as described later. At least one communication hole 88a is formed in the peripheral surface of the surrounding member 88. The surrounding member 88 may be configured to have one communication hole 88a or a plurality of communication holes 88a.

The first biasing member 86 is an elastomer spring made of a resin material such as silicon as described later, and the second biasing member 89 is a coil-shaped elastic body made of a metal material. When the first moving body 84 is biased by the first biasing member 86 and the second biasing member 89 and the first valve seat 84b is seated on the first valve body 87, the brake fluid pressure is not transmitted from the first area A1 to the second area A2 of the first chamber A (see FIG. 3). However, when the brake fluid pressure in the first area A1 increases, the first moving body 84 moves against the biasing forces of the first biasing member 86 and the second biasing member 89, and when the brake fluid pressure exceeds a predetermined first pressure value, the first valve body 87 is released from the first valve seat 84b, and the brake fluid pressure is transmitted from the first area A1 to the second area A2 of the first chamber A (see FIG. 4).

An elastic member 90, which is an elastomer spring formed in a ring shape from a resin material such as silicone as described later and has an outer diameter substantially equal to the inner diameter of the small diameter portion 58b, is disposed inside the second chamber B, i.e., the area of the small diameter portion 58b on the side of the large diameter portion 58a partitioned by the second partition member 83. The elastic member 90 is fitted and positioned in the groove portion 83e of the second partition member 83. By disposing the elastic member 90 in the second chamber, the volume of the elastic member 90 is reduced as the brake fluid pressure in the second chamber B increases, thereby increasing the volume of the brake fluid contained in the second chamber B. On the other hand, the volume of the elastic member 90 is increased as the brake fluid pressure in the second chamber B decreases, thereby decreasing the volume of the brake fluid contained in the second chamber B.

Inside the third chamber C, i.e., the area of the small diameter portion 58b on the bottom surface 58c side of the small diameter portion 58b separated by the second partition member 83, there are arranged a second moving body 94 having a disk portion 94a with an outer diameter smaller than the inner diameter of the second partition member 83 and moving in the direction of the axis Ax1, and a third biasing member 92 and a fourth biasing member 93 which are arranged between the second moving body 94 and the bottom surface 58c of the small diameter portion 58b and bias the second moving body 94 toward the large diameter portion 58a.

The second movable body 94 comprises a disk portion 94a, a second valve body 94b that seats and releases from the second valve seat 83d of the second partition member 83 on the second chamber B side of the disk portion 94a, a protrusion 94c that protrudes from the disk portion 94a toward the second chamber B side along the axis Ax1 and abuts against the first partition member 82 when the second valve body 94b is seated on the second valve seat 83d, a first edge portion 94d that is formed on the outer edge portion of the disk portion 94a and extends toward the bottom surface 58c of the small diameter portion 58b, a contact portion 94e that is provided at the end of the first edge portion 94d on the bottom surface 58c side of the small diameter portion 58b and abuts against the fourth biasing member 93, and a second edge portion 94f that extends from the inner edge portion of the contact portion 94e toward the bottom surface 58c of the small diameter portion 58b.

The disk portion 94a of the second moving body 94 abuts against the third biasing member 92 from the bottom surface 58c side of the small diameter portion 58b. In addition, the abutment portion 94e of the second moving body 94 abuts against the fourth biasing member 93 from the bottom surface 58c side of the small diameter portion 58b. Therefore, the second moving body 94 is biased toward the second chamber B by the third biasing member 92 and the fourth biasing member 93.

A communication hole 94g is provided on the side peripheral surface of the first edge portion 94d of the second movable body 94, which communicates from the outer peripheral surface side to the inner peripheral surface side when the second valve body 94b is seated on or unseated from the second valve seat 83d. At least one communication hole 94g is formed on the first edge portion 94d. The first edge portion 94d may be configured to have one communication hole 94g or a plurality of communication holes 94g.

The third biasing member 92 is a coil-shaped elastic body made of a metal material, and the fourth biasing member 93 is an elastomer spring made of a resin material such as silicon, as will be described later.

The fourth biasing member 93 is formed in a ring shape, and the fourth biasing member 93 abuts against the bottom surface 58c of the small diameter portion 58b and the abutment portion 94e of the second moving body 94, so that the third chamber C is divided into two regions by the second moving body 94 and the fourth biasing member 93. That is, by arranging the second moving body 94 and the fourth biasing member 93 in the third chamber C, a third region C1 is formed which is defined by the bottom surface 58c of the small diameter portion 58b, the inner peripheral surface of the second partition member 83, the outer peripheral surface of the second moving body 94, and the outer peripheral surface of the fourth biasing member 93, and a fourth region C2 is formed which is defined by the bottom surface 58c of the small diameter portion 58b, the inner peripheral surface of the second moving body 94, and the inner peripheral surface of the fourth biasing member 93.

When the second moving body 94 moves in a direction in which the second valve body 94b moves away from the second valve seat 83d, the volume of the third region C1 is enlarged and the volume of the fourth region C2 is reduced, whereas when the second moving body 94 moves in the opposite direction, i.e., in a direction in which the second valve body 94b moves toward the second valve seat 83d, the third region C1c is reduced and the volume of the fourth region C2 is enlarged.

When the second moving body 94 is biased by the third biasing member 92 and the fourth biasing member 93 and the second valve seat 83d is seated on the second valve body 94b, brake fluid pressure is not transmitted from the second chamber B to the third chamber C (see Figure 4). On the other hand, when the brake fluid pressure in the second region A2 increases, the second moving body 94 moves against the biasing forces of the third biasing member 92 and the fourth biasing member 93, and when the brake fluid pressure exceeds a predetermined second pressure value, the second valve body 94b is separated from the second valve seat 83d, and the brake fluid pressure is transmitted from the second chamber B to the fourth region C2 via the third region C1 of the third chamber C (see Figure 5).

The first biasing member 86, the fourth biasing member 93, and the elastic member 90 are formed as ring-shaped members, and are made of elastic bodies having a hysteresis characteristic R1 in which the restoring force p in the loading process (the process in which the displacement changes from 0 to s1) and the restoring force p in the unloading process (the process in which the displacement changes from s1 to 0) are different in magnitude when the displacement s is the same in the loading process (the process in which the displacement changes from s1 to 0). The first biasing member 86, the fourth biasing member 93, and the elastic member 90 may be made of an elastomer spring made of a material such as ethylene propylene diene rubber (EPDM) or silicon. The first biasing member 86, the fourth biasing member 93, and the elastic member 90 may be made of one material or a plurality of materials. For example, they may be made by sandwiching EPDM, which has a relatively low resilience modulus, between silicon, which has a relatively high resilience modulus. Depending on the combination of materials and the shape, the resilience of the urging member can be adjusted to match the specific pulsation frequency that occurs due to the performance of the pump 60 for brake hydraulic pressure.

The second urging member 89 and the third urging member 92 are made of an elastic body having a characteristic R2 in which the restoring force p in the unloading process (the process in which the displacement changes from s2 to 0) when the displacement s is the same as that of the first urging member 86 and the fourth urging member 93 is larger than the restoring force p in the unloading process (the process in which the displacement changes from s1 to 0) or the loading process (the process in which the displacement changes from 0 to s1) of the first urging member 86 and the fourth urging member 93 when the displacement s is the same as that of the first urging member 86 and the fourth urging member 93, as shown in FIG. 6. For example, a metal spring can be used as the first urging member 86 and the fourth urging member 93. In addition, the first urging member 86 and the fourth urging member 93 may be formed of one material or a plurality of materials. The resilience modulus of the urging member can be adjusted according to the inherent pulsation frequency generated due to the performance of the pump 60 of the brake hydraulic pressure by the combination of materials and the shape.

The first biasing member 86, the second biasing member 89, the third biasing member 92, the fourth biasing member 93 and the elastic member 90 are appropriately designed in terms of characteristics such as spring constant according to the pulsating tendency of the brake fluid pressure in the brake fluid pressure control device.

Next, the operation of the pulsation reducing device of this embodiment will be described with reference to FIGS.

3, when the pump 60 is not driven or when the brake fluid pressure output pressure on the discharge side of the pump 60 does not exceed a predetermined first pressure value P1 immediately after the pump 60 starts to be driven, the first valve body 87 is seated on the first valve seat 84b and the second valve body 94b is seated on the second valve seat 83d. In this state, the brake fluid pressure on the discharge side of the pump 60 is supplied only up to the first area A1 of the first chamber A.

Thereafter, as shown in FIG. 4, during the period from immediately after the start of driving of the pump 60 until the brake fluid pressure on the discharge side of the pump 60 rises to a predetermined first pressure value P1, the brake fluid pressure acts on the first moving body 84 as the brake fluid pressure on the discharge side of the pump 60 rises, and the first moving body 84 moves against the biasing forces of the first biasing member 86 and the second biasing member 89. At this time, the first moving body 84 moves against the biasing forces of the first biasing member 86 and the second biasing member 89, and thus a part of the energy of the brake fluid pressure is consumed. In addition, a part of the energy of the brake fluid pressure is consumed by the sliding resistance of the seal member 85 disposed on the outer circumferential surface of the first moving body 84 as the first moving body 84 moves. Due to these energy consumptions, the fluctuation of the brake fluid pressure in the first region A1 is reduced compared to the fluctuation of the brake fluid pressure on the discharge side of the pump 60.

Then, as the pump 60 is driven, the brake fluid pressure on the discharge side of the pump 60 increases and the first moving body 84 moves further toward the first partition member 82, and when the brake fluid pressure exceeds the first pressure value P1, the first valve body 87 leaves the first valve seat 84b, the first area A1 and the second area A2 of the first chamber A are connected, and the brake fluid pressure input from the inlet opening 91b is transmitted from the first area A1 to the second area A2 via the communication hole 88a of the surrounding member 88 and the communication hole 84a of the first moving body 84. At this time, since the first moving body 84 moves against the biasing forces of the first biasing member 86 and the second biasing member 89, part of the energy of the brake fluid pressure is consumed by these biasing members, and the fluctuation of the brake fluid pressure in the second area A2 of the first chamber A is reduced compared to the fluctuation of the brake fluid pressure in the first area A1 of the first chamber A.

Then, the brake fluid pressure in the second area A2 of the first chamber A passes through the communication hole 82d of the first partition member 82 and is transmitted to the second chamber B. At this time, a pressure loss occurs in the brake fluid as it passes through the restriction created by the communication hole 82d of the first partition member 82, and a part of the energy of the brake fluid pressure is consumed, and the fluctuation of the brake fluid pressure in the second chamber B is reduced compared to the fluctuation of the brake fluid pressure in the first chamber A.

5, when the brake fluid pressure on the discharge side of the pump 60 is further increased with the operation of the pump 60 and the brake fluid pressure in the second chamber B exceeds a second pressure value P2 higher than a first pressure value P1, the second movable body 94 is moved against the biasing forces of the third biasing member 92 and the fourth biasing member 93, the second valve body 94b is separated from the second valve seat 84d, and the second chamber B is connected to the third region C1 of the third chamber C. The third region C1 and the fourth region C2 of the third chamber C are connected by a communication hole 94g, and the brake fluid pressure increased with the operation of the pump 60 is output from the pulsation reducing device to the brake fluid pressure circuit 2 via the third region C1 and the fourth region C2. At this time, since the second valve body 94b is moved against the biasing forces of the third biasing member 92 and the fourth biasing member 93, a part of the energy of the brake fluid pressure is consumed by the third biasing member 92 and the fourth biasing member 93, and the fluctuation of the brake fluid pressure in the fourth region C2 of the third chamber C is reduced compared to the fluctuation of the brake fluid pressure in the second chamber B and the third region C1 of the third chamber C. Therefore, since the fluctuation of the brake fluid pressure is reduced by the biasing forces of the first biasing member 86, the second biasing member 89, the third biasing member 92, and the fourth biasing member 93 and the sliding resistance of the seal member 85 within the pulsation reduction device, the pulsation of the brake fluid pressure output from the pulsation reduction device to the brake fluid pressure circuit 2 is reduced compared to the pulsation of the brake fluid pressure on the discharge side of the pump 60.

If the brake fluid pressure in the fourth region C2 exceeds the second pressure value P2 and then falls below the second pressure value P2 again, the second valve body 94b is moved by the biasing force of the third biasing member 92 and seats on the second valve seat 83d, and the second valve body 94b and the second valve seat 83d act as a check valve, reducing the drop in brake fluid pressure in the fourth region C2.

Thereafter, when the brake fluid pressure in the second region A2 further decreases, the first moving body 84 is moved by the biasing force of the second biasing member 89, and the first valve body 87 is moved toward the first valve seat 85b. At this time, since the first biasing member 86 has hysteresis in the restoring force during the loading process and the unloading process as described above, the first biasing member 86 is contracted by the pressing force of the first moving body 84, and it takes a predetermined period of time for the first biasing member 86 to return to a displacement that allows it to apply a biasing force to the second moving body 94. Thereafter, if the brake fluid pressure in the first region of the first chamber A and the second chamber B starts to rise before the biasing force of the first biasing member 86 starts to act on the first moving body 84 and the first valve body 87, the first moving body 84 and the second moving body 94 will be moved only against the biasing forces of the second biasing member 89 and the third biasing member 92, respectively, and the brake fluid pressure in the third region C1 can exceed the second pressure value P2 in a shorter period of time than when the biasing forces of the second biasing member 89 and the third biasing member 92 are acting. This makes it possible to reduce the amount of drop in the brake fluid pressure in the fourth region C2.

As described above, the pulsation reduction device of the present embodiment sequentially transitions between a state in which the first valve body 87 is seated on the first valve seat 84b, a state in which the first valve body 87 is separated from the first valve seat 84b, a state in which the second valve body 94b is seated on the second valve seat 83d, and a state in which the second valve body 94b is separated from the second valve seat 83d in response to fluctuations in the brake fluid pressure associated with the operation of the pump 60, thereby reducing pulsation of the brake fluid pressure associated with the operation of the pump 60. As a result, noise caused by pulsation generated in association with the operation of the pump 60 can be reduced.

[Effects of the pulsation reduction device]
A vehicle brake system 1 includes a brake fluid pressure circuit 2 that supplies brake fluid pressure from a master cylinder 11 to wheel cylinders 12, a pump 60 that increases the brake fluid pressure in the brake fluid pressure circuit 2, and a brake fluid pressure control device 50 that controls the brake fluid pressure. In the brake system 1 configured as described above, pulsation of the brake fluid pressure may occur as the pump 60 is driven, and the pulsation of the brake fluid pressure may be transmitted through the brake fluid pressure circuit 2 to the wheel cylinders 12 or to an engine room or the like of the vehicle that includes the brake system 1 that includes the pump 60, possibly generating noise that may cause discomfort or strangeness to the driver of the vehicle or the like (e.g., the driver of the vehicle, passengers, people outside the vehicle, etc.).

In contrast, the brake fluid pressure control device 50 of the brake system 1 of this embodiment is provided with a pulsation reduction device that reduces pulsation of the brake fluid pressure in the brake fluid pressure circuit 2. The pulsation reduction device is provided in a vehicle brake system that includes a brake fluid pressure circuit (2) that supplies brake fluid pressure to a wheel cylinder (12) and a pump (60) that boosts the brake fluid pressure, and is a pulsation reduction device (37, 80) that reduces pulsation of the brake fluid pressure in the brake fluid pressure circuit (2), a first chamber (A) to which brake fluid pressure is input from the brake fluid pressure circuit (2), a second chamber (B) connected to the first chamber (A), a third chamber (C) connected to the second chamber (B) and outputting brake fluid pressure to the brake fluid pressure circuit (2), a first connection portion connecting the first chamber (A) and the second chamber (B), and a second connection portion connecting the second chamber (B) and the third chamber (C), and the first connection portion has a non-connection position in which it is seated on a first valve seat (84b) to not connect the first chamber (A) and the second chamber (B) and a second connection portion connecting the second chamber (B) and the third chamber (C), and the first connection portion has a non-connection position in which it is seated on a first valve seat (84b) to not connect the first chamber (A) and the second chamber (B) and a non-connection position in which it is lifted off the first valve seat (84b) to connect the first chamber (A) and the second chamber (B). the second connection portion includes a first valve body (87) which moves to a non-connecting position where the second chamber (B) and the third chamber (C) are connected, and the second connection portion includes a second valve body (94b) which moves to a non-connecting position where the second chamber (B) and the third chamber (C) are not connected by being seated on a second valve seat (83d) and to a connecting position where the second chamber (B) and the third chamber (C) are connected by being lifted from the second valve seat (83d), and the second chamber (B) includes an elastic member (90) which elastically changes in response to a change in the brake fluid pressure in the second chamber (B), and which reduces in volume when the brake fluid pressure increases and expands in volume when the brake fluid pressure decreases.

In this configuration, the second chamber (B) connected between the first chamber (A) and the third chamber (C) includes an elastic member (90) that elastically changes in response to changes in the brake fluid pressure in the second chamber (B), reducing its volume when the brake fluid pressure increases and expanding its volume when the brake fluid pressure decreases. Therefore, fluctuations in the brake fluid pressure caused by operation of the first valve body (87) in the first chamber (A) and the second valve body (94b) in the third chamber (C) can be absorbed by utilizing the elastic change of the elastic member (90), thereby reducing the rate and range of change in the brake fluid pressure in the third chamber (C) that is output to the brake fluid pressure circuit (2), and reducing the pulsation of the brake fluid pressure in the vehicle's brake fluid pressure circuit (2).

The elastic member (90) provided in the second chamber (B) of the pulsation reduction device (37, 80) of the brake fluid pressure control device 50 of this embodiment is an elastomer spring, and is configured to be formed from a material such as ethylene propylene diene rubber (EPDM), silicon, etc. With such a configuration, the elastic change of the elastic member (90) accompanying the change in the brake fluid pressure in the second chamber (B) is utilized to reduce the fluctuation of the brake fluid pressure, thereby reducing the pulsation of the brake fluid pressure in the brake fluid pressure circuit 2 of the vehicle.

Although an example of an embodiment of the present invention has been described above, the present invention is not limited to this example of an embodiment, and it goes without saying that modifications and additions that do not deviate from the spirit of the present invention are also included in the present invention.

REFERENCE SIGNS LIST 1 Brake system 2 Brake hydraulic circuit 50 Brake hydraulic control device 37 Damper unit 50 Brake hydraulic control device 60 Pump 80 Pulsation reducing portion 81 Blocking member 82 First partition member 83 Second partition member 84 First moving body 85 Seal member 86 First biasing member 87 First valve body 88 Surrounding member 89 Second biasing member 90 Elastic member 91b Inflow opening 91c Outflow opening 92 Third biasing member 93 Fourth biasing member

Claims (3)

A pulsation reduction device (37, 80) is provided in a brake system of a vehicle including a brake fluid pressure circuit (2) that supplies brake fluid pressure to a wheel cylinder (12) and a pump (60) that boosts the brake fluid pressure, the device reducing pulsation of the brake fluid pressure in the brake fluid pressure circuit (2),
a first chamber (A) to which brake fluid pressure is input from the brake fluid pressure circuit (2);
A second chamber (B) connected to the first chamber (A);
a third chamber (C) connected to the second chamber (B) and outputting a brake fluid pressure to the brake fluid pressure circuit (2);
A first connection portion that connects the first chamber (A) and the second chamber (B);
A second connection portion that connects the second chamber (B) and the third chamber (C);
Equipped with
the first connection portion includes a first valve body (87) that moves between a non-connection position where the first chamber (A) and the second chamber (B) are not connected by being seated on a first valve seat (84b) and a connection position where the first chamber (A) and the second chamber (B) are connected by being separated from the first valve seat (84b),
the second connection portion includes a second valve body (94b) that moves between a non-connection position where the second connection portion is seated on a second valve seat (83d) and does not connect the second chamber (B) and the third chamber (C) and a connection position where the second connection portion is separated from the second valve seat (83d) and connects the second chamber (B) and the third chamber (C),
The second chamber (B) includes an elastic member (90) that elastically changes in response to a change in the brake fluid pressure in the second chamber (B), and the volume of the elastic member decreases when the brake fluid pressure increases and increases when the brake fluid pressure decreases.
Pulsation reduction device. The elastic member (90) is formed by an elastomer spring.
The pulsation reducing device according to claim 1 . A brake fluid pressure control device (50) for a vehicle, comprising the pulsation reducing device according to claim 1 or 2.

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