JPS5845377B2 - Master cylinder residual pressure mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a residual pressure mechanism that applies a constant brake fluid pressure to a brake system in a vehicle such as an automobile.

Generally, in the brake system of automobiles, brake fluid is always maintained at a pressure slightly higher than atmospheric pressure, which increases the boiling point temperature of the brake fluid and increases the heat capacity of the brake, causing vapor lock or leaking into the brake system. Prevents air from being sucked in.

The brake fluid pressure for this purpose is called residual pressure, and the mechanism that applies this residual pressure is a residual pressure mechanism.

As shown in FIG. 1, a conventional residual pressure mechanism of this type has a boss portion 3a that is integrated with a mask cylinder 3 having a piston 1, a reservoir tank 2, etc., and a boss portion 3a that is connected to an outlet of the mask cylinder 3, that is, a wheel cylinder (not shown). A communication hole 4 is provided,
The valve body 6 and the reed valve 7 are connected to each other by the spring 5 in this communication hole 4.
A residual pressure check valve 9 is constructed by urging the valve plug 8 into pressure contact with the valve plug 8.

When operating the brake, pressurized fluid flows through the hole 6a of the valve body 6 by pushing open the reed valve 7. When releasing the brake, the valve body 6 is pushed up together with the reed valve 7 against the spring 5 to mask the fluid. The structure is such that the flow returns into the cylinder 3.

By setting the force of this spring 5 to an appropriate value, the pressure on the wheel cylinder side is prevented from becoming less than the set value, and residual pressure is generated.

However, the residual pressure mechanism described above, especially in factory assembly lines, uses a vacuum pump to suck out waste oil and air in the brake system before filling the brake fluid when assembling the brakes or at the end of maintenance. A method is known in which brake fluid is supplied after the system is evacuated.

During this vacuum suction, due to the residual pressure function of the residual pressure check valve 9, the wheel cylinder side may not be completely vacuumed or it takes time to suction, so the brake fluid is then pumped out and the brake fluid is However, even if the system is filled with liquid, it is difficult to fill it to the end of the system.

The present invention eliminates the above-mentioned drawbacks, and when a one-way seal is press-fitted into the residual pressure check valve from the mask cylinder to the wheel cylinder, the function of the check valve is disabled and vacuum can be drawn. To provide a residual pressure mechanism for a brake mask cylinder in which a press-fitted one-way seal is automatically removed when the cylinder is filled with brake fluid to apply the residual pressure effect of a check valve.

Embodiments of the present invention will be described below with reference to the drawings.

2 to 6 show longitudinal sectional front views of an embodiment of the residual pressure mechanism of the brake mask cylinder according to the present invention.

A double check valve 11 having a structure as shown in FIG. 2 is constructed in the second communication hole 4 of the boss portion 3a integral with the brake mask cylinder 3 and connected to the wheel cylinder when assembled.

That is, the residual pressure check valve 11 is a first one-way valve 12 formed of an elastic member for allowing fluid to pass in one direction only from the bottom to the top (from the wheel cylinder side to the mask cylinder 3 side). It is integrally held by a holder 13, and this valve holder 13
A small hole 3 is a first communication hole provided at the bottom of the boss portion 3a.
b is fitted with a light press fit.

This first one-way valve 12 is designed to be easily opened with a pressure difference of 1 atmosphere or less in the opening direction.

A spring 14 is installed between the valve holder 13 and the earthen wall of the boss portion 3a.
is loaded with a bullet, but the small hole 3b resists this repulsive force.
The valve holder 13 and one-way valve 12 are held in the position shown in FIG. 2 by being press-fitted into the valve holder 13 and the one-way valve 12.

The valve holder 13 is provided with a hole 13a.

Below the valve holder 13 is a check valve plug 1.
A second one-way valve 16 made of an elastic member is placed above the open end 15a of the valve 5.

This second one-way valve 16 operates only from the top to the bottom (only from the mask cylinder 3 side to the wheel cylinder side)
It allows fluid to pass in one direction.

Now, with the configuration shown in Figure 2, when the brake is assembled and the vacuum is drawn, the second one-way valve 1
6 rises as shown in FIG. flows in the direction of the arrow through
It also passes through the hole 13a of the valve holder 13, and then is sucked through the opening 12a of the first one-way valve 12 by pushing it open.

After complete evacuation is completed by the suction operation, when brake fluid is pressurized into the second communication hole 4 from the mask cylinder side, hydraulic pressure is applied to the closed first one-way valve 12 and valve holder 13. Due to the pressure, the valve holder 13 is integrated with the first one-way valve 12 into the small hole 3.
b, and is pressed against the lower second one-way valve 16 by the elastic force of the spring 14, as shown in FIG.

As a result, the second one-way valve 16 is crimped onto the open end 15a of the check valve plug 15.

When the valve holder 13 is removed from the small hole 3b, the brake fluid flows from the small hole 3b of the boss 3a to the valve holder 1 in the direction of the arrow.
The liquid flows into the hole 13a of No. 3, pushes open the second one-way valve 16, passes through the opening 16a, and further passes through the hole 15b of the check valve plug 15 to be directly sent to the end of the brake system on the wheel cylinder side.

Through the above operations, the brake system can be filled with brake fluid without mixing air.

Note that brake fluid may be sucked in using negative pressure in the brake system instead of being pumped, but since there is flow resistance in the brake system, it takes time to fill the brake fluid, so on factory lines, etc., the brake fluid is sucked in after vacuum suction. It is common to pump the liquid.

Next, the operation of the residual pressure mechanism during brake operation will be described.

When the brake pedal (not shown) is stepped on, the hydraulic pressure generated in the hydraulic pressure generating chamber 3C of the mask cylinder 3 passes through the small hole 3b1 hole 13a and reaches the second one-way valve 1 as shown in FIG.
6 is pushed open, and the brake fluid is supplied to the wheel cylinder through the hole 15b to apply braking force to the wheel.

When the brake pedal is released, the piston 1 also returns and the hydraulic pressure in the hydraulic pressure generating chamber 3c decreases. Therefore, while the brake hydraulic pressure in the wheel cylinder is high, the brake fluid flows through the hole 15b of the check valve plug 15 from the wheel cylinder side. As shown in FIG. 5, the second one-way valve 16 is pushed up against the elastic force of the spring 14, passes through the gap between the valve plug 15 and the second one-way valve 16, and the valve holder 13 is pushed up. The gas flows through the hole 13a in the direction of the arrow, and is further sucked into the mask cylinder 3 through the opening 12a of the first one-way valve 12.

Then, when the hydraulic pressure on the wheel cylinder side gradually decreases to below the pressure set by the spring 14, the elastic force of the spring 14 overcomes the hydraulic pressure pushing up the second one-way valve 16, as shown in FIG. As shown in FIG. 2, the valve holder 13 and the first one-way valve 12 move downward, pushing down the second one-way valve 16 and closing the open end 15a of the check valve plug 15.

Therefore, there is a spring 1 in the brake system on the wheel cylinder side.
The constant residual pressure set by 4 is maintained.

As described above, according to the residual pressure mechanism of the brake mask cylinder according to the present invention, when the mask cylinder is assembled, the first one-way valve is installed by light press-fitting into the communication hole to the brake system on the wheel cylinder side, and the second Since the spring force acting on the one-way valve is eliminated, the residual pressure function does not work during vacuuming, allowing complete vacuuming without residual pressure.Then, when the brake fluid is pumped, the Since the press-fitting and holding of one one-way valve is released and the spring force acts on the second one-way valve, it has the advantage that the residual pressure function by the spring force can be maintained during pressure reduction, and air can be prevented from entering.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of an example of a conventional brake mask cylinder residual pressure mechanism, and FIGS. 2 to 6 are operating states of essential parts of an embodiment of the brake mask cylinder residual pressure mechanism according to the present invention. FIG. 3... Brake mask cylinder, 3a...
...Boss portion, 3b...Small hole that is the first communication hole, 4...Second communication hole, 11...Residual pressure check valve, 12... ...First one-way valve, 13...Valve holder, 14...
・Spring, 15...Check valve plaque, 16
...Second one-way valve.

Claims (1)

[Claims] 1. A second communication hole that communicates with the hydraulic pressure generation chamber of the master cylinder via the first communication hole and communicates with the brake system on the wheel cylinder side, and a second communication hole provided within the second communication hole,
a first one-way valve held by a valve holder that can be fitted into the first communication hole by light press-fitting, and formed of an elastic member that allows fluid to pass in one direction only from the wheel cylinder side to the mask cylinder side; a spring that biases the first one-way valve toward the second communication hole; and a spring provided on the wheel cylinder side of the first one-way valve within the second communication hole that urges the first one-way valve toward the wheel cylinder from the mask cylinder side. a second one-way valve formed of an elastic member that allows fluid to pass in one direction only to the side;
The first one-way valve is press-fitted into the first communication hole when assembling the brake, and allows flow only in a pressure reduction direction from the brake system toward the fluid pressure generation chamber, and allows flow in a pressure reduction direction opposite to the pressure reduction direction. After a liquid pressure of a certain value or more is generated and the liquid is removed from the first communication hole, the liquid flows in the second communication hole to allow flow in both the pressure reduction direction and the pressure application direction,
The second one-way valve is not pressed against the second communication hole by the spring when the first one-way valve is press-fitted into the first communication hole, and allows both flows; After the first one-way valve is removed from the first communication hole, it engages with the first one-way valve and is pressed against the second communication hole by the spring, reducing the hydraulic pressure of the brake system. A residual pressure mechanism for a mask cylinder, characterized in that the second communication hole is closed only when the residual pressure is below a certain level.