JP2002154420A - Plunger type master cylinder and hydraulic brake system - Google Patents

Abstract

(57) [Problem] To provide a plunger-type master cylinder in which the passage area of the relief port is increased without changing the length of the play stroke of the piston and without increasing the number of relief ports. A secondary piston (21) is provided with four relief ports (23). The four relief ports (23) extend along the outer circumference of the secondary piston (21) in the circumferential direction of the secondary piston (21). They are arranged at intervals. The relief port 23 is an elliptical hole that is long in the circumferential direction of the secondary piston 21.
As described above, since the relief port 23 is an elliptical hole, an effect of preventing damage to the sealing member 24 with which the relief port 23 slides can be obtained. Then, as compared with the circular hole in the prior art, the area of the hole is enlarged without changing the length of the hole in the direction in which the secondary piston 21 slides in the cylinder hole 2, and the working fluid flowing through the relief port 23 is reduced. It is possible to increase the flow area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger type master cylinder for converting a brake depression force into a hydraulic pressure in a hydraulic brake system used for a vehicle or the like and operating a brake mechanism provided on each wheel.

[0002]

2. Description of the Related Art A plunger-type master cylinder known in the prior art is a cylinder body having a cylinder hole, a piston partitioning a hydraulic chamber slidably inserted into the cylinder hole, and a hydraulic chamber. A communication passage communicating with the liquid reservoir through a relief port formed in the piston; and a sealing member disposed in the cylinder hole and slidably in contact with the outer periphery of the piston. When the relief port passes through the sealing member in accordance with the movement, the communication path is shut off, and hydraulic pressure is generated in the hydraulic pressure chamber.

[0003] On the other hand, a hydraulic brake system used for a vehicle or the like detects the state of a running vehicle other than when the driver applies a brake, and automatically controls each wheel of the vehicle based on the detection result. Some have automatic brake means for performing automatic brake control. Several types of automatic brakes have been developed.For example, in a hydraulic brake system, hydraulic fluid is sucked and pressurized through a communication passage and a hydraulic chamber in a master cylinder, and a generated hydraulic pressure is generated. By hydraulic fluid pressurizing means for supplying the hydraulic fluid to a brake device of a vehicle.

[0004]

However, when a hydraulic brake system having such a self-braking means is added to a hydraulic brake system having a plunger-type master cylinder, the piston is formed on the piston of the plunger-type master cylinder. If the flow area of the relief port is not sufficient, the hydraulic fluid may not be sufficiently sucked by the hydraulic fluid pressurizing means of the automatic brake means, and a necessary braking force may not be obtained in the automatic brake means.

A relief port formed in a piston of a plunger-type master cylinder is generally a circular hole. If the circular hole is simply enlarged in order to increase the flow area, the circular hole is In both the axial direction and the circumferential direction, the play stroke of the piston (the axial direction of the piston) becomes longer. Here, the idle stroke indicates a movement length of the piston from the time when the piston of the plunger type master cylinder starts to move until the time when the hydraulic pressure is generated in the hydraulic pressure chamber and the hydraulic pressure is generated in the output port. . In a hydraulic brake system equipped with this plunger-type master cylinder, this corresponds to the brake pedal play until the driver depresses the brake pedal and the brake starts to work. The reaction of operation is determined.

Accordingly, if this play is not appropriate, the response of the brake operation will be too sensitive or too slow, and by making the circular hole larger, the play stroke of the piston of the plunger type master cylinder will become longer. This causes a problem that the responsiveness of the brake operation is deteriorated.

In order to increase the flow path area without changing the length of the play stroke, it is conceivable to increase the number of relief ports without changing the size of the relief ports. However, the number of locations where the relief port slides on the sealing member that slides on the outer periphery of the piston increases, and the possibility that the sealing member is damaged due to the sliding of the relief port, which is a circular hole, on the sealing member increases. Problems will arise.

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and has as its object to solve the problem of changing the flow path of the relief port without changing the length of the idle stroke of the piston and without increasing the number of relief ports. An object of the present invention is to provide a plunger-type master cylinder having a large area.

[0009]

In order to achieve the above object, an invention according to claim 1 of the present application comprises a cylinder body having a cylinder hole and a hydraulic chamber slidably inserted into the cylinder hole. A piston for partitioning, a communication passage communicating between the hydraulic chamber and the hydraulic fluid reservoir via a relief port formed in the piston, and a seal disposed in the cylinder hole and slidably in contact with the outer periphery of the piston With the sliding of the piston toward the hydraulic chamber side,
When the relief port passes through the sealing member, the communication path is blocked, and the plunger-type master cylinder generates a hydraulic pressure in the hydraulic chamber. A plunger-type master cylinder characterized by having a long hole in a circumferential direction.

The idle stroke of the piston of the plunger type master cylinder is determined by the length of the relief port provided on the piston in the sliding direction of the piston. Therefore, according to the plunger-type master cylinder according to the first aspect of the present invention, the relief port, which has conventionally been a circular hole, is formed into a long hole in the circumferential direction of the piston. The flow area of the relief port can be increased without changing the stroke.

The invention according to claim 2 of the present application is the plunger-type master cylinder according to claim 1, wherein the relief port is an elliptical hole elongated in the circumferential direction of the piston. As described above, by providing the relief port with the elliptical hole, according to the plunger-type master cylinder according to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, for example, a rectangular The possibility that the sealing member is damaged by sliding of the relief port on the sealing member can be reduced as compared with the case where the sealing hole is formed as a long hole.

According to a third aspect of the present invention, in the first or second aspect, a plurality of the relief ports are arranged at equal intervals along an outer periphery of the piston in a circumferential direction of the piston. And a plunger-type master cylinder. As described above, according to the plunger-type master cylinder according to the third aspect of the present invention, since the plurality of relief ports are arranged on the piston at equal intervals, the invention according to the first or second aspect of the present invention is realized. In addition to the function and effect, the frictional resistance generated between each relief port and the sealing member is equalized, and more stable piston operation is possible.

[0013] The invention described in claim 4 of the present application is the invention of claims 1 to
3. The piston according to any one of 3. According to the plunger-type master cylinder provided with the piston according to the invention of claim 4 of the present application, the plunger-type master cylinder obtains the above-described effects of any one of claims 1 to 3 of the present invention. be able to.

According to a fifth aspect of the present invention, there is provided a plunger-type master cylinder and an automatic brake means. When the automatic brake is operated by the automatic brake means, the operation is performed via the relief port via the hydraulic chamber. A hydraulic brake system in which hydraulic fluid is suctioned and pressurized from a liquid reservoir, wherein the plunger-type master cylinder is the plunger-type master cylinder according to any one of claims 1 to 3. It is a hydraulic brake system that has been developed. According to the hydraulic brake system according to the invention as set forth in claim 5 of the present application, in the hydraulic brake system, it is possible to obtain the operation and effect according to the above-described any of claims 1 to 3 of the present invention.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a plunger type master cylinder according to an embodiment of the present invention.
A sleeve 3 is provided inside the main body 1 through a sealing 33.
1 is accommodated, and the lid member 32 is fitted via the sealings 34 and 35 and is screwed and fixed to the main body 1.
The small-diameter hole 1a of the main body 1, the inner peripheral portion 31a of the sleeve 31, and the small-diameter hole 32a of the lid member 32
A cylinder hole 2 is formed.

A primary piston 11 and a secondary piston 21 are slidably inserted into the cylinder hole 2. The primary hydraulic chamber 12 is defined between the primary piston 11 and the secondary piston 21, and the secondary piston 21 and the bottom 2 a of the cylinder hole 2 are defined between the primary piston 11 and the secondary piston 21.
The second hydraulic chamber 22 is arranged so as to be partitioned between the second hydraulic chamber 22 and the second hydraulic chamber 22.

In the first hydraulic chamber 12, a pair of retainers 18a and 18b fitted to the shaft member 17 and a spring 19 therebetween are contracted. In the second hydraulic chamber 22,
A pair of retainers 28a, 28b fitted to the shaft member 27
, And a spring 29 is contracted between them. This allows
The primary piston 11 and the secondary piston 21
It is urged to the position shown.

A hydraulic fluid reservoir 51 is connected to the main body 1, and the first hydraulic chamber 12 passes through a first communication path 16,
Relief port 1 formed in primary piston 11
3 and is communicated with the hydraulic fluid reservoir 51. Further, the second hydraulic chamber 22 communicates with the hydraulic fluid reservoir 51 via a second communication passage 26 and a relief port 23 formed in the secondary piston 21.

The relief port 13 is a through hole that communicates between the outer peripheral side of the primary piston 11 that slides in the cylinder hole 2 and the inside of the primary piston 11 that defines the first hydraulic chamber. The sealing member 14 is in sliding contact with the outer periphery of the primary piston 11 in the cylinder hole 2 so that the communication of the hydraulic fluid between the relief port 13 and the hydraulic fluid reservoir 51 can be shut off according to the movement of the primary piston 11. Are located in Similarly, the relief port 23 is provided between the outer peripheral side of the secondary piston 21 and
Secondary piston 2 defining the second hydraulic chamber
1 is a through-hole communicating with the inside of the first member 1, and the sealing member 24 is
It is arranged in the cylinder hole 2 so as to be in slidable contact with the outer periphery of the secondary piston 21 so as to be able to cut off the communication of the hydraulic fluid between the relief port 23 and the hydraulic fluid reservoir 51 in accordance with the movement of the secondary piston 21.

The first hydraulic chamber 12 is connected to the first output port 1
When a hydraulic pressure is generated in the first hydraulic chamber 12, the hydraulic pressure is generated in the first output port 15. Also,
Similarly, the second hydraulic chamber 22 is in communication with the second output port 25, and when hydraulic pressure is generated in the second hydraulic chamber 22, hydraulic pressure is generated in the second output port 25. .

The primary piston 11 and the secondary piston 21 are connected to the springs 19 and 29 as described above.
In this state, the first hydraulic chamber 12 and the second hydraulic chamber 22 are in communication with the hydraulic fluid reservoir 51 in this state. FIG. 2 is an enlarged cross-sectional view of the vicinity of the relief port 13 in a state where the first hydraulic chamber 12 and the hydraulic fluid reservoir 51 communicate with each other through the first communication passage 16 and the relief port 13. FIG. The positional relationship between the first communication path 16 provided in the lid member 32 and the relief port 13 is as shown in FIG.
Are in communication with each other along the path indicated by the arrow indicated by.

In this state, when the primary piston 11 is moved in the direction of the first hydraulic chamber 12, the first hydraulic chamber 1
The communication between the hydraulic fluid reservoir 2 and the hydraulic fluid reservoir 51 is blocked by the sealing member 14.

FIG. 3 shows that the relief port 13 is
4 is an enlarged cross-sectional view of the vicinity of the relief port 13 in a state in which communication between the first hydraulic pressure chamber 12 and the hydraulic fluid reservoir 51 is completely blocked by the fluid pressure chamber 4. When the primary piston 11 moves from the state shown in FIG. 2 in the direction of the first hydraulic chamber 12 indicated by the reference symbol X, the first port 11 is closed when the relief port 13 is completely closed by the sealing member 14. The first hydraulic pressure chamber 12 is connected to the hydraulic fluid reservoir 51.
The communication with the communication passage 15 is interrupted.

FIG. 4 shows that the relief port 13 is
4, the piston moves further from the state in which the communication between the first hydraulic pressure chamber 12 and the hydraulic fluid reservoir 51 is interrupted, and the hydraulic pressure in the first hydraulic pressure chamber 12 is reduced. It is sectional drawing to which the vicinity of the relief port 13 in the state where it occurred was expanded. From the state shown in FIG.
However, when the fluid further moves in the direction indicated by the symbol X, the communication between the first hydraulic chamber 12 and the first communication passage 15 is blocked by the sealing member 14, so that the first Hydraulic chamber 1
2, a hydraulic pressure is generated in the first output port 15
Will occur.

Although not shown, the relief port 23 provided on the secondary piston 21 is the same as the relief port 13 and is the same as that described with reference to FIGS.

FIG. 5 shows the secondary piston 21 of the plunger-type master cylinder according to the present invention having the above-mentioned structure. FIG. 5 (a) is a front view and FIG. 5 (b)
FIG. 5 is a sectional view taken along line II in FIG. The secondary piston 21 is provided with four relief ports 23. The four relief ports 23 are arranged at equal intervals along the outer circumference of the secondary piston 21 in the circumferential direction of the secondary piston 21. ing.

The relief port 23 is an elliptical hole that is long in the circumferential direction of the secondary piston 21. As described above, since the relief port 23 is an elliptical hole,
The effect of preventing damage to the sealing member 24 with which the relief port 23 slides is obtained. Then, as compared with the circular hole in the prior art, the area of the hole is enlarged without changing the length of the hole in the direction in which the secondary piston 21 slides in the cylinder hole 2, and the working fluid flowing through the relief port 23 is reduced. This makes it possible to increase the flow area.

As a result, the flow area of the working fluid flowing through the relief port 23 can be increased without increasing the number of the relief ports 23 of the secondary piston 21. In addition, since the relief port 23 is an elliptical hole that is long in the circumferential direction of the secondary piston 21, the secondary piston 21 is determined by the length of the relief port 23 in the direction in which the secondary piston 21 slides in the cylinder hole 2. The flow passage area of the relief port 23 can be increased without changing the length of the idle stroke.
The relief port 13 of the primary piston 11 not shown is the same as the relief port 23 of the secondary piston, and a description thereof will be omitted.

In the second embodiment, the relief ports 13 and 23 have long holes. FIG. 6 shows the secondary piston 21 of the plunger-type master cylinder according to the second embodiment. FIG. 6 (a) is a front view, and FIG.
FIG. 7 is a sectional view taken along line II-II in FIG. As in the first embodiment, the secondary piston 21 has 4
Four relief ports 23 are provided, and the four relief ports 23 are provided along the outer circumference of the secondary piston 21 in the circumferential direction of the secondary piston 21.
They are arranged at equal intervals.

The relief port 23 is a long hole that is long in the circumferential direction of the secondary piston 21. In addition, the shape of the long hole has a rectangular shape with rounded corners, so that the relief port 23 according to the present embodiment is similar to the relief port 23 according to the first embodiment. The effect of preventing damage to the sealing member 24 with which the port 23 slides is obtained, and the length of the hole in the direction in which the secondary piston 21 slides in the cylinder hole 2 is changed as compared with the conventional circular hole. Without
The area of the hole is enlarged, and the flow area of the working fluid flowing through the relief port 23 can be increased.
The relief port 13 of the primary piston 11 (not shown) is the same as the relief port 23 of the secondary piston 21 and will not be described.

Further, as a third embodiment, a hydraulic brake system including a plunger type master cylinder according to the present invention and an automatic brake system will be described. FIG.
1 schematically shows a schematic configuration of a hydraulic brake system including a plunger-type master cylinder and an automatic brake system according to the present invention.

The brake depression force of the brake pedal 41 is transmitted to the primary piston 11 of the plunger type master cylinder 1 via the brake pressure increasing device 42. The brake pressure increasing device 42 assists the brake depressing force when the brake pedal 41 operates. That is, it has the function of reducing the necessary brake pedal depression force. The hydraulic fluid reservoir 51 containing the hydraulic fluid is connected to the plunger-type master cylinder 1, and connected to the first hydraulic chamber 12 via the first communication path 15 and the second hydraulic chamber 12 via the second communication path 25. 2 hydraulic chambers 2
2 and each is in liquid communication.

The automatic brake system in this embodiment controls the hydro unit 43, which is a component of the ABS (anti-lock brake system), so that the automatic brake system automatically operates under conditions other than the operation of the driver's brake pedal 41. To apply a braking force to the vehicle. The first output port 15 of the plunger type master cylinder 1 is connected to two of the four brake devices 47 via the hydro unit 43, and the second output port 25 is connected via the hydro unit 43 The first hydraulic chamber 12 and the second hydraulic chamber 22 are connected to the remaining two of the brake devices 47.
The hydraulic fluid pressure generated by the
7 is supplied.

The hydro unit 43 includes an on-off valve 4
4, including a motor 45, a pump 46 and an ABS control valve 48, which prevent the wheels from locking. When the automatic brake system operates, the state of the vehicle is detected by a steering angle of the vehicle (not shown) or a yaw rate sensor of the vehicle, and an appropriate brake pressure is supplied to each of the brake devices 47 based on the information. can do. At this time, since the brake pedal 41 is not operated, the hydraulic fluid reservoir 51 is not operated.
And the first hydraulic chamber 1 of the plunger-type master cylinder 1
The second and second hydraulic chambers 22 are in fluid communication.

When the automatic brake control is performed by the operation of the automatic brake system, the path indicated by reference D is formed by controlling the on-off valve 44. At the same time,
The motor 45 is operated to drive the pump 46, and the hydraulic fluid in the hydraulic fluid reservoir 51 is supplied to the relief port 13 and the relief port 23, the first hydraulic chamber 12, the second hydraulic chamber 22, and the first output port. 15 and second output port 2
5, the pressure is suctioned and increased by a pump 46, and supplied to a brake device 47 via an ABS control valve 48, so that appropriate brake control is performed. The flow of the hydraulic fluid when the automatic brake is released is finally returned to the hydraulic fluid reservoir 51 in the reverse order of the flow of the hydraulic fluid described above.

As described above, in the automatic brake system according to the present embodiment, when the hydraulic fluid is suctioned and pressurized by the pump 46 via the above-described path during operation of the system, the relief port 13 and the relief port 23 are closed. With the plunger-type master cylinder 1 according to the present invention having a large flow passage area, there is no fear that the hydraulic fluid pressure during automatic brake control becomes insufficient due to the shortage of the hydraulic fluid passage area.

[0037]

According to the present invention, there is provided a plunger-type master cylinder in which the passage area of the relief port is increased without changing the length of the play stroke of the piston and without increasing the number of relief ports. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view of a plunger type master cylinder according to the present invention.

FIG. 2 is an enlarged sectional view of the vicinity of a relief port in a state where a first hydraulic chamber and a hydraulic fluid reservoir are in communication with each other.

FIG. 3 is an enlarged sectional view of the vicinity of the relief port in a state where the relief port is completely closed by a sealing member and communication between the first hydraulic chamber and the hydraulic fluid reservoir is cut off.

FIG. 4 shows a state in which the relief port is completely closed by the sealing member and the communication between the first hydraulic chamber and the hydraulic fluid reservoir is interrupted, and a hydraulic pressure is generated in the first hydraulic chamber. It is sectional drawing which expanded the vicinity of the relief port in the state.

FIG. 5A is a front view showing a secondary piston of the plunger-type master cylinder according to the first embodiment of the present invention. (B) in (a)
FIG. 2 is a sectional view taken along line II.

FIG. 6A is a front view showing a secondary piston of a plunger-type master cylinder according to a second embodiment of the present invention. (B) in (a)
FIG. 2 is a sectional view taken along line II-II.

FIG. 7 schematically shows a schematic configuration of a hydraulic brake system including a plunger-type master cylinder and an automatic brake system according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plunger type master cylinder main body 11 Primary piston 12 First hydraulic chamber 13, 23 Relief port 14, 24 Sealing member 15 First output port 16 First communication passage 17, 27 Shaft member 18, 28 Retainer 19, 29 Spring 21 Secondary piston 22 Second hydraulic chamber 25 Second output port 26 Second communication path 31 Sleeve 32 Cover member 33, 34, 35 Seal ring 41 Brake pedal 42 Brake booster 43 Hydro unit 44 Open / close valve 45 Motor 46 Pump 47 Brake device 48 ABS control valve 51 Hydraulic fluid reservoir

Claims (5)

[Claims] 1. A cylinder body having a cylinder hole, a piston partitioning a hydraulic chamber slidably inserted into the cylinder hole, and a piston formed between the hydraulic chamber and the hydraulic fluid reservoir. A communication passage communicating through a relief port provided, and a sealing member disposed in the cylinder hole and slidably in contact with the outer periphery of the piston, with the sliding of the piston toward the hydraulic pressure chamber, By passing the relief port through the sealing member,
A plunger-type master cylinder in which the communication path is shut off and a hydraulic pressure is generated in the hydraulic chamber, wherein the piston has a relief port that is a long hole that is long in a circumferential direction of the piston. Plunger type master cylinder. 2. The plunger-type master cylinder according to claim 1, wherein the relief port is an elliptical hole elongated in a circumferential direction of the piston. 3. The piston according to claim 1, wherein a plurality of the relief ports are arranged at equal intervals along a circumference of the piston in a circumferential direction of the piston. Plunger type master cylinder. 4. A piston according to claim 1, wherein said piston is a piston. 5. A hydraulic cylinder, comprising: a plunger-type master cylinder; and automatic brake means. When the automatic brake is operated by the automatic brake means, hydraulic fluid is suctioned from the hydraulic fluid reservoir through the hydraulic chamber through the relief port. A hydraulic brake system to be pressurized, wherein the plunger-type master cylinder is the plunger-type master cylinder according to any one of claims 1 to 3.