JP7476349B2 - Pumping equipment - Google Patents

Description

The present invention relates to a pump device provided in a brake hydraulic circuit.

Conventional vehicle brake systems include those equipped with a hydraulic circuit having a main flow path that connects a master cylinder and a wheel cylinder, a secondary flow path that releases brake fluid from the main flow path, and a supply flow path that supplies brake fluid to a portion of the secondary flow path.

For example, the upstream end of the secondary flow path in terms of the flow of brake fluid is connected to the area of the main flow path on the wheel cylinder side based on the inlet valve, and the downstream end of the secondary flow path is connected to the area of the main flow path on the master cylinder side based on the inlet valve. The upstream end of the supply flow path in terms of the flow of brake fluid communicates with the master cylinder, and the downstream end of the supply flow path is connected to the suction side of a pump provided in the downstream area of the secondary flow path based on the release valve. A first switching valve is provided in the area of the main flow path on the master cylinder side based on the connection with the downstream end of the secondary flow path, and a second switching valve is provided midway along the supply flow path.

For example, a hydraulic control unit is configured by an inlet valve, a release valve, a pump, a first switching valve, and a second switching valve, a base in which they are incorporated, and a controller that controls their operation. In the hydraulic control unit, the operation of the inlet valve, the release valve, the pump, the first switching valve, and the second switching valve is controlled, thereby controlling the hydraulic pressure of the hydraulic circuit.

In particular, when it becomes necessary to increase the hydraulic pressure of the brake fluid in the wheel cylinder, regardless of the state of the brake operation at the input part of the brake system (e.g., the brake pedal, etc.), the pump is driven with the inlet valve open, the release valve closed, the first switching valve closed, and the second switching valve open.

When the pump is driven, pulsation generated in the brake fluid may be transmitted from the brake system to the engine room of the vehicle, generating noise. This noise may be loud enough to be uncomfortable for the user (driver). For this reason, some conventional hydraulic control units for brake systems have been proposed that aim to reduce the pulsation generated when the pump is driven. For example, the hydraulic control unit for a brake system described in Patent Document 1 includes one pump in one hydraulic circuit, and a pulsation reduction unit on the discharge side of the pump that reduces the pulsation of the brake fluid discharged from the pump.

JP 2017-061246 A

In recent brake systems, the booster may be downsized or omitted in order to improve the ease of mounting the brake system on a vehicle. In such brake systems, the hydraulic pressure of the brake fluid in the wheel cylinder is often insufficient, so the pump is driven more frequently. In other words, in such brake systems, noise caused by pulsation generated when the pump is driven is more likely to occur. For this reason, there has been a demand in recent years for a further reduction in pulsation generated when the pump is driven.

As a configuration for achieving further reduction in pulsation generated when the pump is driven, a hydraulic braking device having a pulsation damper in which multiple metal diaphragms are stacked has been proposed, according to the configuration of the hydraulic control unit of the brake system described in Patent Document 1. However, a structure in which multiple identical metal diaphragms are stacked has limitations in dealing with pulsation caused by the characteristics of the hydraulic control unit, which is based on differences in the output and rotation speed of the pump motor.

The present invention has been made in view of the above-mentioned problems, and provides a brake system capable of reducing noise caused by pulsation generated when the pump is driven.

The pump device according to the present invention comprises:
A pump device including a pulsation reducing portion provided in a base body and configured to reduce pulsation of brake fluid discharged from a pump,
The pulsation reduction unit includes:
A cylindrical storage chamber provided in the base body;
a fixing member that divides the storage chamber into an upstream region and a downstream region and has a hole in the center;
an upstream movable member provided in the upstream region and slidable in the axial direction; an inlet opening side damper portion communicating with an inlet opening through which the brake fluid flows and formed between the upstream movable member and a cover portion of the accommodation chamber; and a fixed member side damper portion formed between the upstream movable member and the fixed member;
a downstream side movable member provided in the downstream side region and movable in an axial direction; an outflow opening side damper portion communicating with an outflow opening through which the brake fluid flows out and formed between the fixed member and a bottom of the accommodation chamber;
an inlet opening side elastic body provided in the inlet opening side damper portion and configured to bias the upstream side movable member toward the fixed member;
a fixed member side elastic body provided in the fixed member side damper portion and configured to bias the upstream side movable member toward the lid portion;
an outlet opening side elastic body provided in the outlet opening side damper portion and capable of closing a hole of the fixed member by biasing the downstream side movable member toward the fixed member;
a cylindrical member formed on a central axis of the accommodation chamber, penetrating the downstream side movable member, and including a cylindrical portion extending from the bottom portion to the fixed member side damper portion;
Including,
the upstream movable member includes a through hole having a seat portion configured to be closed by a valve member pressed from the lid portion side and seated thereon,
In the process of the upstream movable member moving toward the fixed member due to the pressure of the brake fluid flowing into the inlet opening side damper portion, the valve member abuts against the cylindrical portion and leaves the seat portion, whereby the brake fluid flows in through the through hole and the pressure in the fixed member side damper portion increases,
A pressure increase in the fixed member side damper portion causes the downstream movable member, which was in contact with the fixed member, to move toward the bottom side, and the brake fluid passes through the outflow opening side damper portion and flows out from the outflow opening.

In a brake system, noise caused by pulsation of brake fluid generated when the pump is driven can be reduced.

1 is a diagram showing an example of a system configuration of a brake system according to an embodiment of the present invention; 3 is a partial cross-sectional view showing an example of a state in which a pump and a damper unit are mounted on a base body in a hydraulic control unit of a brake system according to an embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a pulsation reduction portion according to an embodiment of the present invention when the pump is not driven. FIG. 11 is an enlarged cross-sectional view of a pulsation reducer in a state where an upstream movable member is midway through movement after the pump starts to be driven, according to an embodiment of the present invention. FIG. 10 is an enlarged cross-sectional view of a pulsation reducing portion in a state in which brake fluid flows out from the outflow opening after the pump starts to be driven, according to an embodiment of the present invention. FIG.

The hydraulic control unit according to the present invention will be described below with reference to the drawings. In the following, a brake system including the hydraulic control unit according to the present invention is described as being mounted on a four-wheeled vehicle, but the brake system including the hydraulic control unit according to the present invention may be mounted on vehicles other than four-wheeled vehicles (two-wheeled vehicles, trucks, buses, etc.). The configurations, operations, etc. described below are merely examples, and the brake system including the hydraulic control unit according to the present invention is not limited to such configurations, operations, etc. In addition, in each drawing, the same or similar members or parts are given the same reference numerals, or the reference numerals are omitted. In addition, illustrations of detailed structures are appropriately simplified or omitted.

<Configuration and Operation of Brake System 1>
The configuration and operation of a brake system 1 according to this embodiment will be described below. Fig. 1 is a diagram showing an example of the system configuration of a brake system according to an embodiment of the present invention.

1, the brake system 1 is mounted on a vehicle 100, and includes a hydraulic circuit 2 having a main flow path 13 that connects a master cylinder 11 and a 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, 2b as the hydraulic circuit 2. The hydraulic circuit 2a is a hydraulic circuit that communicates the master cylinder 11 with the wheel cylinders 12 of the wheels RL, FR via a main flow path 13. The hydraulic circuit 2b is a hydraulic circuit that communicates the master cylinder 11 with the wheel cylinders 12 of the wheels FL, RR via a main flow path 13. These hydraulic circuits 2a, 2b have the same configuration except for the wheel cylinders 12 that they communicate with.

The master cylinder 11 contains a piston (not shown) that reciprocates in conjunction with a brake pedal 16, which is an example of an input section of the brake system 1. A booster 17 is interposed between the brake pedal 16 and the piston of the master cylinder 11, and the user's depressing force is boosted and transmitted to the piston. 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 upstream end of the sub-flow passage 14 is connected to a first intermediate portion 13a of the main flow passage 13, and the downstream end of the sub-flow passage 14 is connected to a second intermediate portion 13b, which is upstream of the first intermediate portion 13a, in the main flow passage 13. 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 a third intermediate portion 14a of the sub-flow passage 14.

An inlet valve (EV) 31 is provided in a region of the main flow path 13 between the second intermediate portion 13b and the first intermediate portion 13a. A release valve (AV) 32 is provided in a region of the secondary flow path 14 between the first intermediate portion 13a and the third intermediate portion 14a. An accumulator 33 is provided in a region of the secondary flow path 14 between the release valve 32 and the third intermediate portion 14a. The inlet valve 31 is, for example, a solenoid valve that opens in a non-energized state and closes in an energized state. The release valve 32 is, for example, a solenoid valve that closes in a non-energized state and opens in an energized state.

A pump 60 is provided in a region of the sub-flow path 14 between the third midway portion 14a and the second midway portion 13b. The suction side of the pump 60 is connected to the third midway portion 14a. The discharge side of the pump 60 is connected to the second midway portion 13b of the main flow path 13. A pulsation reduction portion 80 is provided in a region between the discharge side of the pump 60 and the second midway portion 13b, which is a part of the sub-flow path 14.

The pulsation reduction unit 80 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 95b (see FIG. 2) through which the brake fluid of the pulsation reduction unit 80 flows in, and an outflow opening 95c (see FIG. 2) through which the brake fluid temporarily stored in the pulsation reduction unit 80 flows out is connected to the second intermediate portion 13b of the main flow path 13. In the following description, the flow path between the discharge side of the pump 60 and the inflow opening 95b is referred to as a first discharge flow path 140a, and the flow path between the outflow opening 95c and the second intermediate portion 13b of the main flow path 13 is 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 second 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 third intermediate portion 14a of the sub-flow path 14. The first switching valve 35 is, for example, a solenoid valve that opens in a non-energized state and closes in an energized state. The second switching valve 36 is, for example, a solenoid valve that closes in a non-energized state and opens in an energized state.

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.

A hydraulic pressure control unit 50 is configured by at least a base 51, each member provided on the base 51, and a controller (ECU) 52. In the hydraulic pressure control unit 50, the operation of the inlet valve 31, the release valve 32, the pump 60, the first switching valve 35, and the second switching valve 36 is controlled by the controller 52, thereby controlling the hydraulic pressure of the brake fluid in the wheel cylinder 12. In other words, the controller 52 governs the operation of the inlet valve 31, the release valve 32, the pump 60, the first switching valve 35, and the second switching 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.

Controller 52 performs the following hydraulic control operations in addition to well-known hydraulic control operations (ABS control operation, ESP control operation, etc.), for example: When brake pedal 16 of vehicle 100 is operated with inlet valve 31 open, release valve 32 closed, first switching valve 35 open, and second switching valve 36 closed, if a lack or possible lack of hydraulic pressure in hydraulic circuit 2 is detected from the detection signal of the position sensor of brake pedal 16 and the detection signal of the hydraulic pressure sensor of hydraulic circuit 2, controller 52 starts an active pressure boost control operation.

In the active pressure boosting control operation, the controller 52 allows the brake fluid to flow from the second intermediate portion 13b of the main flow path 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 path from the master cylinder 11 to the second intermediate portion 13b of the main flow path 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 path from the master cylinder 11 to the second intermediate portion 13b of the main flow path 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.

When the pump 60 is driven, 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. This pulsation may also be transmitted to the engine compartment that houses the hydraulic control unit 50 of the brake system 1, generating noise. This noise may be loud enough to be uncomfortable for the user (driver). For this reason, it is important to reduce the pulsation generated when the pump 60 is driven.

Therefore, in the brake system 1 according to this embodiment, that is, in the hydraulic control unit 50, 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 attenuated in the pulsation reduction section 80, and then flows downstream from the pulsation reduction section 80. Therefore, the brake system 1 according to this embodiment, that is, the hydraulic control unit 50, can reduce the pulsation that occurs when the pump 60 is driven.

In the above-mentioned active pressure boosting control, the user operates (depresses) 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, it is preferable that the brake system 1 according to this embodiment, that is, the hydraulic control unit 50, includes a damper unit 37 as shown in FIG. 1. This is because the damper unit 37 can attenuate 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, 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 depresses the brake pedal, the same amount of depression of the brake pedal 16 as in the brake system 1 equipped with the booster 17 can be obtained. 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.

<Mounting Configuration of Pump 60 and Pulsation Reducer 80 on Base 51>
An example of a configuration for mounting the pump 60 and the pulsation reducer 80 on the base 51 in the hydraulic control unit 50 of the brake system 1 according to the present embodiment will be described. Fig. 2 is a partial cross-sectional view showing an example of a state in which the pump 60 and the pulsation reducer 80 are mounted on the base in the hydraulic control unit of the brake system according to the embodiment of the present invention. Fig. 2 shows a state in which the drive shaft 57 that drives the piston 62 of the pump 60 has been removed. For this reason, in Fig. 2, the drive shaft 57 and the eccentric portion 57a formed on the drive shaft 57 are shown by imaginary lines (two-dot chain lines).

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

The pump 60 accommodated in the pump accommodating chamber 53 includes a cylinder 61, a piston 62, and the like. The cylinder 61 is formed in a cylindrical shape having a cylinder 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 forms 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 other end side of the piston 62, protrudes into the drive shaft accommodating chamber 59. Furthermore, an annular cylinder side seal member 66 is attached to a portion of the piston 62 accommodated in the cylinder 61. The cylinder side 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 piston spring 67 is accommodated in the cylinder 61 between the cylinder bottom 61b and the piston 62, i.e., in the pump chamber 63. The piston spring 67 constantly biases the piston 62 toward the drive shaft accommodating 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 drive shaft accommodating chamber 59. The center 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 driving 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 piston guide member 68 provided on the inner circumferential surface of the pump accommodating chamber 53. In addition, an annular drive shaft side seal member 69 is attached to the pump accommodating chamber 53 adjacent to the piston guide member 68. This drive shaft side seal member 69 prevents brake fluid from leaking from the outer circumferential surface of the piston 62 to the drive shaft accommodating chamber 59 side.

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 that communicates the outer circumferential surface of the piston 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 so as to be freely opened and closed. The suction valve includes a suction valve member that is a ball valve that closes the opening of the bottomed hole 62b, and a suction valve spring that biases the suction valve member 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 communication hole 61c that communicates between the pump chamber 63 and the outside of the cylinder 61 is formed in the cylinder bottom 61b. An opening side discharge valve 64 is provided on the opening side of the communication hole 61c opposite the pump chamber 63. The opening side discharge valve 64 includes an opening side valve member 64a which is a ball valve, an opening side valve seat 64b formed on the periphery of the open end of the communication hole 61c and on which the opening side valve member 64a can be seated and separated, and an opening side spring 64c that biases the opening side valve member 64a in a direction to seat it on the opening side valve seat 64b. The opening side discharge valve 64 is disposed between the cylinder 61 and the cover 65.

Specifically, the cover 65 is attached to the cylinder bottom 61b side by, for example, press fitting. A bottomed hole 65a having an opening at a position facing the communication hole 61c of the cylinder bottom 61b is formed in the cover 65. The opening side spring 64c of the opening side 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 opening side valve member 64a. Therefore, when the opening side valve member 64a leaves the opening side valve seat 64b, the opening side valve member 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 opening side valve member 64a becomes larger than the biasing force of the opening side spring 64c, the opening side valve member 64a leaves the opening side valve seat 64b, and the pump chamber 63 and the bottomed hole 65a of the cover 65 communicate with each other via the communication hole 61c. The brake fluid in the pump chamber 63 then flows into the bottomed hole 65a. A groove that serves as a discharge port 65b connecting the outside of the cover 65 to the bottomed hole 65a is formed in the cover 65. 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 pump 60 through the discharge chamber 54, which will be described later.

As described above, the pump 60 configured in this manner is accommodated in the pump accommodation chamber 53 formed in the base body 51. Specifically, the annular protrusion 61a formed on the outer periphery of the cylinder 61 is press-fitted into the pump accommodation chamber 53 at a position where it abuts against the stepped portion 53a of the pump accommodation chamber 53, whereby the pump 60 is fixed within the pump accommodation chamber 53 of the base body 51.

When the pump 60 is accommodated in the pump accommodation chamber 53 in this manner, a discharge chamber 54, which is a space that communicates with a 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 pump accommodation chamber 53. 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 is connected to a 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 a partition 71. The space on the cover 65 side of the partition 71 serves as the discharge chamber 54. In this embodiment, an O-ring (not shown) is provided in an annular groove formed in the partition 71.

In this embodiment, when the pump 60 is accommodated in the pump 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 pump 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 drive shaft side 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 third 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 pump accommodation chamber 53, the suction port 62c of the pump 60 and the third intermediate portion 14a need to communicate with each other. By having the annular flow passage 56, when the pump 60 is accommodated in the pump accommodation chamber 53, alignment for communicating the suction port 62c of the pump 60 with the third intermediate portion 14a is not required. Therefore, by having the annular flow passage 56, the assembly of the hydraulic control unit 50 becomes easier. In addition, by having the annular flow passage 56, when the pump 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 hydraulic control unit 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 51, i.e., the hydraulic control unit 50, can be made smaller in size.

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. 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 that constitutes a part of the discharge flow passage 140. The discharge chamber 54 is connected to the inflow opening 95b of the pulsation reduction part 80 via the first discharge flow passage 140a. In FIG. 2, 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 95c 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 second intermediate portion 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 piston spring 67. As a result, the pressure in the pump chamber 63 increases, causing the opening side valve member 64a to separate from the opening side valve seat 64b and opening side discharge valve 64 to open. As a result, the brake fluid in the pump chamber 63 passes through the communication 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 piston spring 67. As a result, the pressure in the pump chamber 63 decreases, and the opening-side valve member 64a seats on the opening-side valve seat 64b, closing the opening-side discharge valve 64 and opening the suction valve (not shown) that 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 the opening-side discharge valve 64 (not shown) are selectively opened and closed, so that the brake fluid whose fluid pressure has increased, that is, 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.

<Configuration example and operation of pulsation reduction unit 80>
3 to 5, a configuration example and operation of the pulsation reduction unit 80 will be described below. As described above, the pulsation reduction unit 80 is intended to reduce the pulsation of the brake fluid generated when the pump 60 is driven, and to reduce noise caused by the pulsation.

3 shows the pulsation reducer 80 when the pump 60 is not in operation. The cylindrical accommodation chamber 58 that accommodates the pulsation reducer 80 is formed in the base body 51. The pulsation reducer 80 has an inflow opening 95b through which the brake fluid flows in and an outflow opening 95c through which the brake fluid flows out. The pulsation reducer 80 also has a fixing member 83 that divides the interior of the pulsation reducer 80 into an upstream region on the inflow opening 95b side and a downstream region on the outflow opening 95c side.

The cylindrical shape forming the accommodation chamber 58 is a stepped shape including a small diameter portion 58b and a large diameter portion 58d. The large diameter portion 58d is formed on the side of the lid portion 82 that closes the opening 58e of the accommodation chamber 58, and the small diameter portion 58b is formed on the side of the bottom portion 58a opposite to the opening 58e of the accommodation chamber 58. A step portion 58c is formed between the small diameter portion 58b and the large diameter portion 58d in parallel with the bottom portion 58a, in other words, in a direction perpendicular to the longitudinal axis Axc of the pulsation reduction portion 80. The inflow opening 95b is formed in the large diameter portion 58d. The outflow opening 95c is formed on the bottom portion 58a radially outward of the damper member 90 described later.

The fixed member 83 includes a fixed member disk portion 83a having a cylindrical hole portion 83b in the center. The hole portion 83b is formed as a cylinder extending from the fixed member disk portion 83a to the upstream region. The fixed member 83 also includes a fixed member outer cylindrical portion 83d extending from the outer periphery of the fixed member disk portion 83a to the bottom portion 58a side. The fixed member disk portion 83a, the hole portion 83b, and the fixed member outer cylindrical portion 83d are integrally formed. The fixed member 83 is fixed to the small diameter portion 58b of the accommodation chamber 58 by an appropriate method such as press fitting or welding. At that time, the fixed member outer cylindrical portion 83d is arranged so as to abut against the small diameter portion 58b.

The pulsation reducing unit 80 also includes a columnar member 86 extending from the center of the bottom 58a to the upstream region. The columnar member 86 includes a columnar member fixing portion 86b that fixes the columnar member 86 to the bottom 58a, and a columnar portion 86d that extends from the columnar member fixing portion 86b to the upstream region. The columnar portion 86d has a diameter smaller than the inner diameter of the hole 83b, and is disposed so that its tip is located closer to the lid portion 82 than the lower end of the hole 83b. The columnar member fixing portion 86b also includes a disk-shaped portion to which the columnar portion 86d is connected, and a cylindrical portion that extends from the outer diameter portion of the disk-shaped portion to the opposite side to the bottom 58a. The disk-shaped portion and the cylindrical portion are fixed by an appropriate method such as welding while being inserted into a recess 58f formed in the bottom 58a. This configuration makes it easy to position the columnar member 86.

An upstream movable member 84 having a disk shape and slidable in the direction of the axis Axc of the accommodation chamber 58 is provided on the large diameter portion 58d closer to the fixed member 83 than the inflow opening 95b. A sliding member 84a is attached to the side surface of the upstream movable member 84 facing the large diameter portion 58d. When the upstream movable member 84 moves, the sliding member 84a slides against the large diameter portion 58d. To facilitate smooth sliding, for example, PTFE can be used as the material for the sliding member 84a.

The upstream movable member 84 has a through hole 84b in the center, which penetrates in the direction of the axis Axc of the accommodation chamber 58. The through hole 84b has a seat portion 84d on the lid portion 82 side, on which the valve member 94 can be seated. The valve member 94 is pressed against the seat portion 84d with a predetermined set force by a valve spring 93 provided between the valve member 94 and a lid portion inner surface 82a, which is the surface of the lid portion 82 on the upstream movable member 84 side. A plurality of upstream orifices 84c having a smaller diameter than the through hole 84b are formed radially outward of the through hole 84b, which penetrate the upstream movable member 84 in the direction of the axis Axc of the accommodation chamber 58.

In this embodiment, in the accommodation chamber 58, the region between the upstream movable member 84 and the lid portion 82 is referred to as the inflow opening side damper portion 81a, the region between the upstream movable member 84 and the fixed member 83 is referred to as the fixed member side damper portion 81b, and the region between the fixed member 83 and the bottom portion 58a is referred to as the outflow opening side damper portion 81c. That is, in the accommodation chamber 58, the inflow opening side damper portion 81a and the fixed member side damper portion 81b form the upstream region of the accommodation chamber 58, and the outflow opening side damper portion 81c forms the downstream region of the accommodation chamber 58.

The inflow opening side damper portion 81a is provided with an inflow opening side elastic body 92 which is an elastic body that urges the upstream side movable member 84 toward the fixed member 83. The fixed member side damper portion 81b is provided with a fixed member side elastic body 91 which is an elastic body that urges the upstream side movable member 84 toward the lid portion 82.

A coil spring can be used as the inflow opening side elastic body 92. The inflow opening side elastic body 92 is disposed circumferentially outward of the valve spring 93 and the upstream orifice 84c.

The fixed member side elastic body 91 may be a cylindrical cushion member. The cushion member may be made of, for example, ethylene propylene diene rubber (EPDM) and/or silicon. The fixed member side elastic body 91 is disposed such that its inner diameter portion contacts the outer diameter portion of the hole 83b. In other words, the fixed member side elastic body 91 is guided by the hole 83b.

When a cushion member is used as the elastic body, the cushion member may be made of one material or may be made of multiple materials. For example, the cushion member may be configured by sandwiching EPDM, which has a relatively low resilience modulus, between silicon, which has a relatively high resilience modulus. By combining materials, it is possible to adjust the resilience modulus of the cushion member to match the inherent pulsation frequency generated due to the performance of the brake fluid pump.

The outflow opening side damper portion 81c is provided with a downstream side movable member 85 that is movable in the direction of the axis Axc of the accommodation chamber 58. The downstream side movable member 85 has a downstream side movable member disk portion 85a having a hole in the center, and a downstream side movable member cylindrical portion 85b extending from the inner diameter portion of the hole in the center of the downstream side movable member disk portion 85a toward the bottom portion 58a. The downstream side movable member 85 also has a downstream side movable member expanded diameter portion 85c that extends from the outer periphery of the downstream side movable member disk portion 85a toward the bottom portion 58a and has a diameter that increases as it approaches the bottom portion 58a. The downstream side movable member disk portion 85a, the downstream side movable member cylindrical portion 85b, and the downstream side movable member expanded diameter portion 85c are formed integrally.

The cylindrical portion 86d is inserted through the inside of the cylindrical portion 85b of the downstream movable member. In other words, the cylindrical portion 86d guides the movement of the downstream movable member 85.

Between the downstream movable member disk portion 85a and the cylindrical member fixed portion 86b, there is disposed an outflow opening side elastic body 96 which is a coil spring that biases the downstream movable member 85 toward the fixed member 83. As shown in Fig. 3, the outflow opening side elastic body 96 is disposed on the outer periphery of the downstream movable member cylindrical portion 85b and is guided by the downstream movable member cylindrical portion 85b.

A damper member 90 is provided between the downstream movable member disk portion 85a and the bottom portion 58a, and on the circumferential outside of the outflow opening side elastic body 96. The damper member 90 is arranged so that its outer periphery is in contact with the downstream movable member enlarged diameter portion 85c, and is guided by the downstream movable member enlarged diameter portion 85c. For the damper member 90, an elastic body having the same conditions as the fixed member side elastic body 91 described above can be used.

3, that is, when the pump 60 is not driven, the upstream movable member 84 receives a biasing force from the fixed member side elastic body 91 toward the lid portion 82, and also receives a biasing force from the valve spring 93 and the inflow opening side elastic body 92 toward the fixed member 83. As a result, the biasing forces of the elastic bodies are adjusted so that the upstream movable member 84 is located between the step portion 58c and the inflow opening 95b in the large diameter portion 58d. In this state, the valve member 94 and the cylindrical portion 86d are not in contact. In addition, the downstream movable member disk portion 85a of the downstream movable member 85 abuts against the fixed member disk portion 83a of the fixed member 83 by the biasing force received from the outflow opening side elastic body 96 and the damper member 90, and closes the hole portion 83b.

When the pump 60 starts to operate, brake fluid flows in through the inlet opening 95b, and the pressure in the inlet opening damper portion 81a increases. When the pressure in the inlet opening damper portion 81a increases, the valve member 94 and the upstream movable member 84 move toward the fixed member 83 while the valve member 94 is seated on the seat portion 84d.

Then, the valve member 94 comes into contact with the cylindrical portion 86d of the cylindrical member 86, but the upstream movable member 84 continues to move. Therefore, at this timing, the valve member 94 leaves the seat portion 84d. Thereafter, the upstream movable member 84 comes into contact with the step portion 58c, thereby ending its movement. In other words, the dimensions of each member are set in advance so that the amount of movement of the upstream movable member 84 is greater than the amount of movement of the valve member 94.

4 shows a state in which the valve member 94 abuts against the cylindrical portion 86d, but also against the seat portion 84d. After passing through this state, the upstream movable member 84 moves further and abuts against the step portion 58c.

As the valve member 94 and the upstream movable member 84 rise, the pressure in the fixed-member damper portion 81b also rises. Then, as the valve member 94 leaves the seat portion 84d, brake fluid flows from the inflow opening damper portion 81a to the fixed-member damper portion 81b through the through hole 84b, so that the pressure in the fixed-member damper portion 81b rises further. The increased pressure in the fixed-member damper portion 81b acts on the downstream movable member 85, moving the downstream movable member 85 toward the bottom portion 58a against the biasing force of the outflow opening elastic body 96 and the damper member 90.

5 shows a state in which the downstream movable member 85 has moved toward the bottom portion 58a. As the downstream movable member 85 moves toward the bottom portion 58a, the brake fluid flows out from the fixed member damper portion 81b to the outflow opening damper portion 81c. The brake fluid that has flowed into the outflow opening damper portion 81c flows out of the pulsation reduction portion 80 from the outflow opening 95c.

In this embodiment, even immediately after the pump 60 is driven and the valve member 94 is seated on the seat portion 84d, the brake fluid in the inlet opening side damper portion 81a flows out little by little to the fixed member side damper portion 81b through the upstream side orifice 84c formed in the upstream side movable member 84. This makes it possible to prevent a sudden increase in pressure in the fixed member side damper portion 81b after the valve member 94 leaves the seat portion 84d.

Furthermore, the action of each elastic body prevents the upstream movable member 84 and the downstream movable member 85 from suddenly moving, making it possible to smooth the flow of brake fluid.

Furthermore, since the damper member 90 functions as a resistance against the outflow opening side elastic body 96, the movement of the downstream side movable member 85 can be stabilized.

As described above, according to the present invention, the action of each elastic body and the orifice prevents sudden movement of the upstream movable member 84 and the downstream movable member 85, and also prevents a sudden flow of brake fluid. This makes it possible to smooth the flow of brake fluid in the pulsation reduction section 80 and reduce the pressure pulsation of the brake fluid. As a result, it is possible to reduce noise caused by pulsation generated when the pump 60 is driven.

51: base, 58: storage chamber, 58a: bottom, 60: pump, 80: pulsation reduction section, 81a: inflow opening side damper section, 81b: fixed member side damper section, 81c: outflow opening side damper section, 82: lid section, 83: fixed member, 83b: hole section, 84: upstream side movable member, 84b: through hole, 84c: upstream side orifice, 84d: seat section, 85: downstream side movable member, 86: cylindrical member, 86d: cylindrical section, 90: damper member, 91: fixed member side elastic body, 92: inflow opening side elastic body, 94: valve member, 95b: inflow opening, 95c: outflow opening, 96: outflow opening side elastic body

Claims (5)

A pump device including a pulsation reducing section (80) provided in a base body (51) and configured to reduce pulsation of brake fluid discharged from a pump (60),
The pulsation reduction unit (80)
A cylindrical storage chamber (58) provided in the base body (51);
a fixing member (83) that divides the storage chamber (58) into an upstream region and a downstream region and has a hole (83b) in the center;
an upstream movable member (84) provided in the upstream region and slidable in the axial direction; an inlet opening side damper portion (81a) communicating with an inlet opening (95b) through which the brake fluid flows and formed between the upstream movable member (84) and a lid portion (82) of the accommodation chamber (58); and a fixed member side damper portion (81b) formed between the upstream movable member (84) and the fixed member (83);
a downstream movable member (85) provided in the downstream region and movable in an axial direction; and an outflow opening side damper portion (81 c) communicating with an outflow opening (95 c) through which the brake fluid flows out and formed between the fixed member (83) and a bottom portion (58 a) of the accommodation chamber (58);
an inlet opening side elastic body (92) provided in the inlet opening side damper portion (81 a) for biasing the upstream side movable member (84) toward the fixed member (83);
a fixed member side elastic body (91) provided in the fixed member side damper portion (81b) for biasing the upstream side movable member (84) toward the lid portion (82);
an outflow opening side elastic body (96) provided in the outflow opening side damper portion (81 c) and capable of closing a hole portion (83 b) of the fixed member (83) by biasing the downstream side movable member (85) toward the fixed member (83);
a cylindrical member (86) formed on a central axis of the accommodation chamber (58), penetrating the downstream side movable member (85), and including a cylindrical portion (86d) extending from the bottom portion (58a) to the fixed member side damper portion (81b);
Including,
the upstream movable member (84) is provided with a through hole (84b) having a seat portion (84d) configured to be able to be closed by a valve member (94) pressed from the lid portion (82) side being seated thereon;
In the process of the upstream movable member (84) moving toward the fixed member (83) due to the pressure of the brake fluid flowing into the inlet opening side damper portion (81 a), the valve member (94) abuts against the cylindrical portion (86 d) and leaves the seat portion (84 d), whereby the brake fluid flows in from the through hole (84 b) and the pressure in the fixed member side damper portion (81 b) increases,
a pump device in which, due to an increase in pressure in the fixed member side damper portion (81b), the downstream side movable member (85) that was in contact with the fixed member (83) moves toward the bottom (58a), and the brake fluid passes through the outflow opening side damper portion (81c) and flows out from the outflow opening (95c). 2. The pump device according to claim 1, wherein the outflow opening side elastic body (96) is a coil spring, and a damper member (90) is provided between the downstream movable member (85) and a bottom (58a) of the storage chamber (58) to absorb vibrations of the outflow opening side elastic body (96). 3. The pump device according to claim 1, wherein the outlet opening (95c) communicates with the outlet opening side damper portion (81c) radially outward of the outlet opening side elastic body (96) and the damper member (90). 4. The pump device according to claim 1, wherein the upstream movable member (84) has an upstream orifice (84c) radially outside the through hole (84b) that connects the inlet opening damper portion (81a) and the fixed member damper portion (81b). The pump arrangement of any one of claims 1 to 4, wherein the cylindrical member (86) guides the movement of the downstream moveable member (85).

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