JPH08108843A - Master cylinder - Google Patents

Abstract

PURPOSE: To prevent a sealing cup from being injured even under severe service condition such as that of an ABS vehicle by opening a valve when the pressure and the flow speed at a relief port rise, so that the sealing cup does not bite in the relief port. CONSTITUTION: A poppet type valve 17 provided with a ball l7a opening by the dead weight is arranged on the passage communicating to the reservoir of a relief port 16. This valve 17 is opened when the pressure and the flow speed at the relief port 16 rise to fixed values, so that a sealing cup 3b provided on a piston 3 does not bite in the relief port 16 when the pressure of a pressure chamber rises. Consequently, even under severe service conditions such as that of an ABS vehicle, the sealing cup 3b does not bite in the relief port, and hence the sealing cup 3b can be prevented from being injured. Hence, durability of the sealing cup 3b can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder used in various braking devices for motor vehicles.

[0002]

2. Description of the Related Art Conventionally, as a conventional type master cylinder of this type, for example, there is a tandem master cylinder shown in FIG. The master cylinder 100 has a cylinder hole 10 formed in a cylinder housing 101.
2, an operating piston 103 having a sealing cup 103a and an operating piston 104 having a sealing cup 104a are slidably arranged, and the pistons 103, 104 and the inner wall surface of the cylinder housing 101 are connected to each other. In between, a pressure chamber 105 that fills the working fluid and a similar pressure chamber 106 are formed between the piston 104 and the inner wall surface of the cylinder housing 101. Then, in the pressure chambers 105 and 106, the piston 10
Return spring 10 for biasing 3, 104 in the backward direction
7, 108 are arranged respectively.

A small-diameter relief port (compensating port) 113, which has one end connected to the pressure chamber 105 or 106 and the other end connected to the hydraulic fluid supply port 111 or 112, is provided in the upper portion of the cylinder housing 101. , 114 are provided respectively, and when the master cylinder 100 is not operated, that is, when the pistons 103 and 104 are at the standby position (brake release position) as shown in FIG. 5, as shown in FIG. The relief ports 113, 114 are opened from the respective sealing cups 103a, 104a, and thus the pressure chambers 105, 1 are connected via the relief ports 113, 114.
06 and the hydraulic fluid supply ports 111 and 112 are connected to each other.

Further, when the master cylinder 100 is operated, that is, when the pistons 103 and 104 are pushed in the P direction in FIG. 5 through a push rod (not shown), the sealing cups 103a and 104a are pushed into the relief ports 113 and 104, respectively. Moving over 114, the relief ports 113, 114 are closed. Therefore, the hydraulic pressure in each of the pressure chambers 105 and 106 rises, and the hydraulic fluid is
Each pressure chamber 105, 106 is pressure-fed to a brake system (not shown) from each outlet 115, 116 provided at one end.

[0005]

In the conventional conventional type master cylinder 100, the flow rate of the hydraulic fluid flowing into the relief ports 113 and 114 immediately before the relief ports 113 and 114 are closed during the sudden braking. As the speed increases, the pressure chambers 105 and 106
The pressure in the sealing cup 1 rises sharply,
03a and 104a may be bitten by the relief ports 113 and 114 and may be damaged. For this reason,
A center valve type is used.

ABS (Anti-lock Brake System)
In the case of a mounted vehicle, particularly when braking on a low friction coefficient road such as on ice, at the position where the sealing cups 103a, 104a block the relief ports 113, 114, the pulsating pressure of the ABS actuator is the sealing cup 103.
a, 104a, which causes the sealing cups 103a, 104a to relieve the relief ports 113, 1
The center valve type is used on the secondary side of the master cylinder that is installed in a vehicle equipped with ABS. Many,
On the other hand, there was the problem of becoming a factor in raising costs.

The present invention has been made in view of the above points,
It is an object of the present invention to solve the above problems and provide a master cylinder that prevents damage to the sealing cup even under severe operating conditions such as an ABS vehicle.

[0008]

The structure of the present invention for achieving the above object is such that a single or plural sets of pistons and pressure chambers are arranged vertically in a cylinder body, and the pistons and pressure chambers are arranged in a brake release position. In the master cylinder in which the relief port is provided in the cylinder body in order to independently return the hydraulic fluid from each pressure chamber to the reservoir, the following is performed.

(1) A poppet-type valve having a ball that opens by its own weight is provided in a passage of the relief port that communicates with the reservoir, and the valve is provided with the piston when the pressure in the pressure chamber rises. In order to prevent the sealing cup provided in the relief port from being bitten into the relief port, it is closed when the pressure and the flow velocity of the relief port increase to a predetermined value.

(2) In the above (1), a cutout passage is provided in a part of the valve seat surface of the poppet type valve.

(3) A poppet-type valve having a ball and a pressing spring is disposed in a passage of the relief port communicating with the reservoir, and the valve is provided in the piston when the pressure in the pressure chamber rises. In order to prevent the provided sealing cup from being caught in the relief port, the sealing cup is closed when the pressure and the flow velocity of the relief port rise to a predetermined value.

(4) In the above item (3), a cutout passage is provided in a part of the valve seat surface of the poppet type valve.

[0013]

Since the present invention is constructed as described above,
Even under severe operating conditions such as a BS vehicle, when the pressure and flow velocity of the relief port rise to a predetermined pressure, the poppet type valve is closed to prevent the sealing cup from being bitten into the relief port. Therefore, it is possible to prevent the sealing cup from being damaged. Further, since the valve is normally open, the return of the hydraulic fluid from the brake system (for example, the wheel cylinder) is promptly returned to the reservoir via the hydraulic fluid supply port.

Further, since the cutout passage is provided in a part of the valve seat surface of the valve, the valve remains closed, residual pressure is generated, and the piston does not return properly. There is no fear.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. 1 is a vertical sectional view showing an embodiment of a master cylinder of the present invention, and FIG. 2 is an enlarged view of a portion A of FIG.

In FIG. 1, reference numeral 1 denotes a tandem master cylinder in which a plurality of sets (two sets in this embodiment) of pistons 2 and 3 and pressure chambers 4 and 5 are vertically arranged. On the upper side of the cylinder housing 6, working fluid supply ports 8 and 9 for supplying a working fluid from a reservoir 7 to the pressure chambers 4 and 5 are formed.

A primary piston 2 and a secondary piston 3 are slidably disposed in a cylinder hole 10 formed in the cylinder housing 6, and the primary piston 2 is provided inside the cylinder housing 6. And the secondary piston 3, the first pressure chamber 4
The secondary pressure chamber 5 is formed by the secondary piston 3 and the inner wall surface of the cylinder housing 6.

In order to urge the primary piston 2 and the secondary piston 3 in the retreating direction, the spring mechanism 11 is respectively pushed into the first pressure chamber 4 and the second pressure chamber 5.
And a return spring 12 is provided. The spring mechanism 1
The reference numeral 1 includes a return spring 13, a guide screw 14, and a retainer 15 in the shape of a cap. One end of the return spring 13 is held by the end face of the primary piston 2 and the other end is held by the peripheral edge of the retainer 15. The guide screw 14 is provided on the end surface of the primary piston 2,
It is screwed so as to project from the end face in the axial direction of the piston by a predetermined length. The retainer 15 has a hole 15a provided at the top of the cap-shaped cap, which freely slides on the guide screw 14 within a predetermined stroke range and engages with the end thereof.

A cross section of a passage communicating with the cylinder hole 10 is provided in the working fluid supply ports 8 and 9 formed on the upper side of the cylinder housing 6 for returning the working fluid from the pressure chambers to the reservoir 7. A relief port 16 having a circular shape with a small inner diameter, a poppet type valve 17 arranged in series with the relief port 16, and an inlet port 18 having a large inner diameter are provided for each of the hydraulic fluid supply ports 8 and 9. Formed or disposed.

The poppet type valve 17 normally has a ball 17a which is opened by its own weight and a mounting screw 17 on the outer peripheral surface.
and a valve body 17b provided with c, the poppet-type valve 17 is provided in the cylinder housing 6 so as to be connected in series to the passage from the relief port 16 to the reservoir 7, that is, the relief port 16. The mounting screw 17 of the valve body 17b is provided in the provided screw hole 6a.
c is screwed on.

The valve 17 prevents the sealing cups 2b and 3b provided on the pistons 2 and 3 from being bitten into the relief port 16 when the pressure in the pressure chambers 4 and 5 rises. Therefore, when the pressure and the flow velocity of the relief port 16 increase to a predetermined value,
The ball 17a is selected so as to be closed.

The relief port 16 is connected to the reservoir 7 via the poppet type valve 17 at the brake release position so that the first and second pressure chambers 4 and 5 are released.
To form a passage for returning the hydraulic fluid from the.

In such a master cylinder 1, when the brake is actuated, the primary piston 2 and the secondary piston 3 are moved leftward in FIG.
When the sealing cups 2b and 3b of the pistons 2 and 3 close the relief ports 16 and 16, respectively, and the second pressure chambers 5 are pushed into the second pressure chambers 5, the hydraulic pressures in the pressure chambers 4 and 5 rise and the operation is performed. Liquid is delivered from the outlet 19 (not shown), 2
The pressure is sent from 0 to a brake system (not shown).

When the brake operation is released, the pistons 2 and 3 are pushed back by the urging force of the return springs 13 and 12, and the pressures in the first and second pressure chambers 4 and 5 are temporarily negative. It becomes pressure. At this time, the hydraulic fluid from the reservoir 7 passes from the inlet ports 18, 18 through the outer peripheries of the through holes 2a, 3a provided in the pistons 2, 3 and the shilling cups 2b, 3b thereof, and The first and second pressure chambers 4 and 5 flow into the first and second pressure chambers 4 and 5 to quickly return the pistons 2 and 3.

In this case, when the brake of the master cylinder 1 is actuated, especially when the sudden brake is actuated or the ABS (Anti-l
(ock Brake System) operation, the sealing cups 2b and 3b of the pistons 2 and 3 close the relief ports 16 and 16. Immediately before that, the flow velocity of the hydraulic fluid flowing through the relief ports 16 and 16 is changed. Try to get faster. Therefore, the pressure of each of the relief ports 16 and 16 also rises, and the poppet type valve 17 is closed by the ball 17a rising at a predetermined pressure. Therefore, the hydraulic fluid that tries to flow into the relief ports 16 and 16 is stopped, so that the sealing cups 2b and 3b are prevented from being bitten into the relief ports 16 and 16.

FIG. 3 shows an ABS (Anti-lock Brake Syste).
m) C in the pressure chamber 4 or 5 of FIG. 2 during operation
In the figure showing the test result of the pressure difference between the point and the point D in the relief port 16, the dotted line shows the pressure difference of the conventional example, and the solid line shows the test result of the present example. The pointed portion is improved by this embodiment, the poppet type valve 17 is closed, and the hydraulic fluid that tries to flow into the relief ports 16 and 16 is stopped.

Further, in FIG. 2, a cutout passage 17d is provided in a part of the valve seat surface of the valve body 17a of the poppet type valve 17. Therefore, even if the valve 17 remains closed, the hydraulic fluid flows into the reservoir 7 through the notch passage 17d at a minute flow rate, and a residual pressure is generated in the pressure chamber 4 or 5. There is no possibility that the piston 2 or 3 will return poorly.

FIG. 4 shows the poppet type valve 17 of FIG.
It is sectional drawing of the poppet type valve 27 which shows another example.
The poppet type valve 27 has a ball 27a for opening and closing the valve.
And a valve body 27b having a mounting screw 27c on the outer peripheral surface
And one end engages with the outer peripheral end groove 27e of the valve body 27b,
The other end is composed of a pressing spring 27f that presses the ball 27a in the opening direction, and the poppet-type valve 27 is connected in series to the passage from the relief port 16 to the reservoir 7, that is, to the relief port 16. As described above, the mounting screw 27c of the valve body 27b is screwed into the screw hole 6a provided in the cylinder housing 6.

The valve 27 prevents the sealing cups 2b and 3b provided on the pistons 2 and 3 from being caught in the relief port 16 when the pressure in the pressure chambers 4 and 5 rises. The relief port 16
The pressing force of the pressing spring 27f is set so that the valve is closed when the pressure increases to a predetermined value. The operation of the poppet type valve 27 is the same as that of the above embodiment.

Further, in FIG. 4, a cutout passage 27d is provided in a part of the valve seat surface of the valve body 27b of the poppet type valve 27. Therefore, the valve 17
Similarly, even if the valve 27 remains closed, the hydraulic fluid flows through the cutout passage 27d at a minute flow rate,
The pressure chamber 4 or 5 flows into the reservoir 7.
There is no risk of residual pressure occurring in the cylinder or the piston 2 or 3 returning poorly.

Incidentally, the technique of the present invention is not limited to the technique in the above-described embodiment, but may be implemented by means of other modes which perform the same function. Can be changed or added.

[0032]

As is apparent from the above description, according to the master cylinder of the present invention, in the first, second, third, and fourth embodiments, a ball that opens by its own weight is provided in the passage communicating with the reservoir of the relief port. A poppet-type valve provided with, or a poppet-type valve provided with a ball and a pressing spring is provided, and when the pressure of the pressure chamber rises,
When the pressure and the flow velocity of the relief port increase to a predetermined value in order to prevent the sealing cup provided in the piston from being bitten into the relief port,
Since the valve is closed, the sealing cup is prevented from being bitten into the relief port even under a severe use condition such as an ABS vehicle, and damage to the sealing cup can be prevented. Therefore, the durability of the sealing cup can be improved.

According to the present invention, since the notched passage is provided in a part of the valve seat surface of the poppet type valve, the valve remains closed and residual pressure occurs, and the piston There is no risk of the return failure of the above, and the same operating state as the conventional master cylinder is maintained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a tandem master cylinder showing an embodiment of a master cylinder of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a pressure chamber 4 or 5 and a relief port 16 of FIG.
It is a figure which shows the test result of the pressure difference between them.

FIG. 4 is a cross-sectional view of a poppet type valve showing another example of the poppet type valve 17 of FIG.

FIG. 5 is a vertical sectional view of a conventional master cylinder.

FIG. 6 is an enlarged view of part B in FIG.

[Explanation of symbols]

 1 Tandem Master Cylinder 2 Primary Piston 2b, 3b Sealing Cup 3 Secondary Piston 4 1st Pressure Chamber 5 2nd Pressure Chamber 6 Cylinder Housing 7 Reservoir 8, 9 Hydraulic Fluid Supply Port 16 Relief Port 17, 27 Poppet Valve 17a, 27a Ball 17b, 27b Valve body 17d, 27d Cutout passage 27f Pressing spring

Claims (4)

[Claims] 1. A single or plural sets of pistons and pressure chambers are vertically arranged in a cylinder body, and the hydraulic fluid is independently returned from each pressure chamber to a reservoir at a brake release position. In a master cylinder having a relief port provided in a cylinder body, a poppet-type valve having a ball that opens by its own weight is provided in a passage of the relief port communicating with the reservoir. Rises,
When the pressure and the flow velocity of the relief port increase to a predetermined value in order to prevent the sealing cup provided in the piston from being bitten into the relief port,
A master cylinder characterized by being closed. 2. The master cylinder according to claim 1, wherein a cutout passage is provided in a part of a valve seat surface of the poppet type valve. 3. A single body or a plurality of pairs of pistons and pressure chambers are vertically arranged in the cylinder body, and in order to independently replenish the hydraulic fluid from the reservoir to the respective pressure chambers at the brake release position, In a master cylinder in which a relief port is provided in the cylinder body, a poppet-type valve including a ball and a pressing spring is arranged in a passage communicating with the reservoir of the relief port,
When the pressure in the pressure chamber rises and the pressure and flow velocity in the relief port rise to a predetermined value, the sealing cup provided in the piston is prevented from being bitten into the relief port when the pressure in the pressure chamber rises. , A master cylinder characterized by being closed. 4. The master cylinder according to claim 3, wherein a cutout passage is provided in a part of a valve seat surface of the poppet type valve.