JPS6019008Y2 - Switching valve device for brake booster - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a switching valve device that changes the fluid pressure applied to a piston in response to a pressing operation of a brake pedal in a booster used in a power control device of an automobile, and particularly relates to a switching valve device that changes fluid pressure applied to a piston in response to a pressing operation of a brake pedal. The present invention relates to an improvement in the structure of a seat portion of a valve plunger and a valve member that are interlocked with each other.

The present invention makes the rear end seat surface of the valve plunger a convex spherical surface centered on the axis of the valve plunger. This allows airtightness to be ensured.

The present invention will be explained below based on an embodiment shown in FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes a closed shell body in which a front shell body 2 and a rear shell body 3 are brought into contact with each other and a diaphragm 4 is sandwiched and supported between them. A piston 5 fixed to the inner peripheral edge of the diaphragm 4 is inserted and arranged,
Inside the sealed shell 1 are the piston 5 and the diaphragm 4.
It is divided into a front chamber 6 and a rear chamber 7 by.

The rear cylindrical portion 8 of the piston 5 is slidably protruded from the opening of the rear shell 2 through a seal 9, and between the front surface of the piston 5 and the end wall of the front chamber 8, there is a A return spring 10 is interposed to press the piston 5 into contact with the stepped portion of the rear shell 3 via a spot-like projection 11 of the diaphragm 4 on the back surface thereof.

A proximal end fitting part 14 of a driven rod 13 is slidably fitted into a fitting part 12 provided at the center of the front surface of the piston 5, and the tip of the driven rod 13 is connected to the end wall of the front chamber 6. Sea 1
5, and the output is transmitted to a master cylinder (not shown).

Further, a negative pressure pipe 16 that is connected to a negative pressure source such as an engine intake pipe (not shown) is opened in the end wall of the front chamber 6.

Further, the piston 5 has a communication passage 17 passing through the inside of the piston diagonally and communicating between the inside of the cylindrical part 8 and the inside of the front chamber 6, and an internal chamber 19 communicating with the inside of the fitting part 12 and the rear chamber 7. A communication path 18 is provided in each case.

An operating rod 20 is inserted through the rear opening of the rear cylindrical portion 8 via an air cleaner 21, and a spherical tip portion 22 is formed at the tip of the operating rod 20.

The spherical end portion 22 is tightly connected to a valve plunger 23 which is slidably fitted into the internal chamber 19 of the piston 5, as shown in FIG.

The seat surface 23a of the rear end of the valve plunger 23 is formed into a convex spherical surface centered at a point on the axis of the valve plunger 23, and the seat surface 23a has an annular valve at the rear end of the rear end of the piston 5. A valve member 24, which constitutes a switching valve device together with the seat 5a, is in contact with the seat 5a.

The valve member 24 surrounds the operating rod 20 and is located behind the spherical part 22, and is constructed by covering a cylindrical plate member with an elastic member such as rubber.
5 is fixed at an intermediate inner peripheral position of the cylindrical portion 8.

The seat surface 2 of the valve plunger 23 of this valve member 24
As shown in FIG.
a and 24b, respectively, and the annular projection 24a normally blocks communication between the internal passage along the operating rod 20 and the chambers 6 and 7.

As shown in FIG. 2, a receiving portion 28 is attached to the intermediate flange portion 27 of the operating rod 20, and a valve return spring 26 is interposed between the receiving portion 28 and the enlarged portion 25 of the valve member 24. has been done.

Further, a valve biasing spring 29 is interposed between the front edge of the receiving portion 28 and the rear step portion of the valve member 24.

Further, inside the fitting part 12, as shown in FIG. 1, a reaction disk 30 made of rubber or the like is fitted onto the rear surface of the fitting part 14 of the driven rod 13 with a gap between it and the valve plunger 23. The internal chamber 19 is sealed off from the front chamber 6.

In FIG. 1, reference numeral 31 denotes a key member, 3, which spans the intermediate reduced diameter portion of the valve plunger 23, leaving a free movement interval.
Reference numeral 2 indicates a bellows provided to cover the respective open ends of the cylindrical portion 8 and the rear shell body 3.

Next, the effect will be explained.

As shown in the figure, when the booster is not operating, negative pressure is communicated to the rear chamber 7 via the front chamber 6, communication passage 17, internal chamber 19, and communication passage 18, while atmospheric pressure is communicated via the air cleaner 21 to the rear chamber 7. The seat surface 23a of the valve plunger 23 and the annular protrusion 2 of the valve member 24 have reached the inner position of the plunger 23.
Since it is in contact with 4a, it is closed here.

When the brake pedal is depressed from this state, the operating rod 20 moves forward against the valve return spring 26. First, the annular protrusion 24b of the valve member 24 abuts the annular valve seat 5a on the periphery of the internal chamber 19 of the piston 5, causing the communication passage. 17 is disconnected from the internal chamber 19, and then the valve plunger 2 is removed from the annular projection 24a of the valve member 24.
The seat surfaces 23a of the rear seats 3 and 3 are separated, and air enters the rear chamber 7 through the internal chamber 19 and the communication passage 18.

Then, a pressure difference is generated between the two chambers 6 and 7, and the piston 5 moves forward against the return spring 10, and the driven rod 13 operates the master cylinder to supply brake fluid pressure to the brake cylinder to perform a braking action. let

When the pedal force is removed from the brake pedal, contrary to the aforementioned operation, the seat surface 23a of the valve plunger 23 and the valve member 24
The atmosphere side is closed due to the close contact with the annular projection 24a of the valve member 24, and the annular projection 24b of the valve member 24 is separated from the annular valve seat 5a on the periphery of the internal chamber 19, and the rear chamber 7 communicates with the front chamber 6 again and the inside of the rear chamber 7 is closed. Air is sucked out to the engine side, and the piston 5, operating rod 20, etc. return to the non-moving position shown.

By the way, when the brake pedal is depressed halfway, the operating rod 20 moves forward against the valve return spring 26, and the annular protrusion 24b of the valve member 24 first moves into the internal chamber 19 of the piston 5.
The inner chamber 19 of the communication passage 17 abuts against the annular valve seat 5a on the periphery.
The annular projection 24 of this valve member 24 is then cut off.
The seat surface 23a of the valve plunger 23 is separated from the position a, and air enters the rear chamber 7 via the internal chamber 19 and the communication passage 18.

Then, when the piston 5 moves forward and operates the master cylinder, the brake fluid pressure generated in the master cylinder is transmitted as a reaction force to the valve plunger 23 via the driven rod 13 and the reaction disc 30, and the valve plunger 23 acts against the piston 5. The valve member 24 moves relatively to the right in the figure, and its seat surface 23a tends to come into close contact with the annular protrusion 24a of the valve member 24.

At this time, since there is a certain clearance between the diameter of the internal chamber 19 and the outer diameter of the valve plunger 23, the valve plunger 23
3 will tilt and return to the right in the figure.

Since the inclination of the valve plunger 23 is slight, even in conventional switching valve devices, the inclination is absorbed by the elasticity of the valve member 24 and almost never causes airtight leakage.
If the valve member 24 is used for a long time beyond its usage limit, the elastic force of the valve member 24 will decrease and it will no longer be able to absorb the inclination of the valve plunger 23, which may cause a slight airtight leak.

That is, in the intermediate load state where the input is maintained at a constant value as described above, both of the two valves making up the switching valve device are in a closed balance state, and therefore the valve plunger 23 is tilted as described above. If you try to sit in this state, the adhesion force between the valve plunger 23 and the valve member 24 may not be uniform on the circumference, or the valve plunger 23 and the valve member 24 may not have a uniform contact force on the circumference.
4 or a slight positional deviation between the valve seat 5a of the piston and the valve member 24 may cause airtight leakage.

However, in the present invention, the seat surface 23 of the valve plunger 23
Since a is a convex spherical surface whose center is on the axis of the valve plunger 23, even if the valve plunger 23 is tilted, it will surely come into close contact with the valve member 24, and even if the elastic force of the valve member 24 is reduced, , it is possible to always ensure airtightness between the two.

Since the seat surface 23a on the side of the valve plunger 23, which is a special balance and operating force transmission member and is made of a hard material such as metal, is formed as a convex spherical surface having its center on its axis.
Even if the valve plunger 23 is tilted, the hard seat surface 23a is always kept in a spherical position aligned with the valve plunger axis, and not only does it not apply any force that would cause lateral displacement to the valve member 24, but also prevents operation. The valve member 24, which is made of a hard elastic member that follows the force, flexibly adapts to the hard seat surface 23a having a convex spherical surface, and maintains a secure state of contact with the valve seat 5a of the piston. There is no risk of compromising airtightness.

In the above embodiment, the annular projections 24a and 24b were provided on the seat surface of the valve member 24, but these may be omitted and the seat surface of the valve member 24 may be made flat.

Further, as shown by imaginary line A in FIG. 2, the seat surface of the piston 5 relative to the valve member 24 may be made into a spherical surface.

The present invention has been described above based on preferred embodiments, and the present invention can be expected to have the effect of ensuring long-term reliable airtightness between the valve plunger and the valve member. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a brake booster according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the section ``■'' in FIG. 5...Zeston, 5a...Annular valve seat, 1
3... Driven rod, 20... Operating rod, 23
... Valve plunger, 23a... Seat surface, 24... Valve member.

Claims (1)

[Scope of utility model registration request] The valve plunger is provided at the tip of an operating rod that is linked to a brake pedal and is slidably fitted to a piston, and a valve member that is always in contact with a seat surface at the rear end of the valve plunger. A brake that includes a valve mechanism that comes into contact with a valve seat of a piston and separates from a seat surface of the valve plunger as the valve plunger is displaced, and that controls fluid pressure applied to the piston by this valve mechanism to operate in conjunction with the piston. A brake booster for generating operating pressure in a side driven rod, characterized in that the rear end seat surface of the valve plunger is a convex spherical surface having a center on the axis of the valve plunger. Device switching valve device.