JPH0537895Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention relates to a reaction force mechanism of a brake booster.
More specifically, the present invention relates to a reaction force mechanism of a brake booster that transmits a brake reaction force applied to a push rod to an input shaft via a reaction disk.

"Prior Art" Conventionally, in the reaction force mechanism of a brake booster, a large diameter hole and a small diameter hole are connected to each other in the shaft of a valve body that is slidably disposed in a shell. The base of the push rod is slidably fitted into the small diameter hole, and the valve plunger constituting the valve mechanism is slidably fitted into the small diameter hole, and the brake reaction force applied to the push rod is applied to the valve plunger and the input connected thereto via the reaction disk. It is transmitted to the shaft.

Conventionally, an annular protrusion is formed protrudingly on the outer periphery of the reaction disk, and the annular protrusion is brought into close contact with the inner circumferential surface of the large diameter hole. A reaction force mechanism for a brake booster has been proposed in which the reaction disk reliably prevents communication between a constant pressure chamber on one side and a variable pressure chamber on the other side or the atmosphere (Utility Model Publication No. 1973-11). No. 40618).

Conventionally, a concave portion is formed in the base end face of the push rod to accommodate the reaction disk therein, and an annular groove is formed in the stepped end face of the large diameter hole and the small diameter hole to accommodate the push rod around the small diameter hole. A laterally projecting annular projection is formed and the annular projection is inserted into the recess of the push rod, thereby reducing the axial dimension of the reaction disk and the base of the push rod without reducing the volume of the reaction disk. A reaction force mechanism has been proposed in which the axial dimension of the brake booster can be shortened by overlapping the axial dimension of the brake booster (Utility Model Application No. 57-28059).

However, in the reaction mechanism of a brake booster in which a concave portion is formed in the base end face of the push rod and a reaction disk is accommodated therein, the reaction disk does not come into close contact with the large diameter hole. Communication between the large diameter hole and the small diameter hole could not be blocked by this reaction disk.

In order to solve these problems, a plate is connected to the reaction disk in the recess, the plate is pulled out of the valve body from the recess, and the plate is urged rearward by a return spring. It has been proposed that the reaction disk is brought into pressure contact with the annular protrusion by
Publication No. 470).

"Problem to be Solved by the Invention" However, if the reaction disk is brought into pressure contact with the annular protrusion, communication between the large diameter hole and the small diameter hole can be blocked at that part. The plate has a complicated shape and is expensive because it is necessary to interlock the reaction disk housed in the recess with the return spring disposed in the constant pressure chamber of the brake booster.

``Means for Solving the Problems'' In view of such circumstances, the present invention is a reaction force mechanism of a brake booster in which a reaction disk is housed in the recessed portion, that is, a reaction force mechanism is arranged slidably in the shell. A large-diameter hole and a small-diameter hole are connected to the shaft of the valve body, and the base of the push rod is slidably fitted into the large-diameter hole, and the valve plunger constituting the valve mechanism is fitted into the small-diameter hole, respectively. A concave portion is formed on the base end surface of the push rod, and a reaction disk is accommodated therein, and an annular groove is formed on the stepped end surface of the large diameter hole and the small diameter hole so as to protrude toward the push rod side around the small diameter hole. The annular projection is inserted into the recessed portion of the push rod, and the brake reaction force applied to the push rod is transmitted to the valve plunger and the input shaft connected thereto via the reaction disk. In the reaction force mechanism of the brake booster, a cylindrical member is fitted and tightly attached to the outer periphery of the annular protrusion, and at least a part of the reaction disk is fitted inside the cylindrical member. It comes out.

"Function" The large diameter hole and the small diameter hole communicate with each other through the gap between the annular projection and the reaction disk, and according to the above configuration, the gap is surrounded by the cylindrical member. Since the valve body can be sealed with Since it is only necessary to provide a cylindrical member to be tightly fitted,
The configuration is simple and inexpensive.

"Example" The present invention will be explained below with reference to the illustrated example.
In FIG. 1, a power piston 2 is slidably provided in a shell 1 of a brake booster, and a diaphragm 3 is stretched on the back surface of the power piston 2. The interior of the shell 1 is divided into a constant pressure chamber 4 at the front and a variable pressure chamber 5 at the rear. A valve body 6 is integrally provided on the shaft portion of the power piston 2, and a valve mechanism 7 for switching the flow path is accommodated within the valve body 6.

The valve mechanism 7 has a first valve formed in the valve body 6.
The valve chamber 10, the second valve seat 12 formed on the valve plunger 11, and the power piston 2 on both valve seats 10, 12.
A valve body 14 is provided which is seated from the rear side, that is, from the right side in FIG. 1, by the elastic force of a spring 13. The outside of the seat portion of the first valve seat 10 and the valve body 14 is communicated with the constant pressure chamber 4 through a passage 15 formed in the valve body 6, and the inside of the constant pressure chamber 4 is connected to a negative pressure chamber provided in the shell 1. It is connected to a negative pressure source such as an engine intake manifold via a pressure introduction pipe 16.

On the other hand, the intermediate portions of the seals between the first valve seat 10 and the valve body 14 and between the second valve seat 12 and the valve body 14 are communicated with the variable pressure chamber 5 through a passage 17 formed in the valve body 6, and further The inner side of the seat portion between the second valve seat 12 and the valve body 14 is communicated with the atmosphere via a filter 18.

Also, a valve plunger 1 constituting the valve mechanism 7
1 is connected to an input shaft 24 that is linked to a brake pedal (not shown), and the tip of the valve plunger 11 is connected to a cylindrical member 25 and a reaction disk 26.
It is linked to the push rod 27 via.
This push rod 27 is connected to a sealing member 28.
It penetrates through and projects to the outside of the shell 1, and is linked to a piston of a master cylinder (not shown).

Further, the power piston 2, the valve body 6, etc. are normally held in the non-operating position shown in the figure by a return spring 29, and in this non-operating state, the valve plunger 11 cannot be pulled out from the valve body 6. Key member 30 that prevents
is in contact with the inner wall surface of shell 1, and then press valve body 6.
The free movement of the valve plunger 11 to the right is restricted, so that when the input shaft 24 and the valve plunger 11 are operated next, the valve mechanism 7 can immediately switch the fluid circuit.

The tip of the valve plunger 11 is slidably fitted into a small diameter hole 6a formed in the shaft of the valve body 6, and the push rod is fitted into a large diameter hole 6b connected to the front of the small diameter hole 6a. The right end base 27a of No. 27 is slidably fitted thereto.

The shaft portion 27b of the push rod 27 is slidably passed through a disc-shaped retaining plate 31 that covers the opening of the large diameter hole 6b, and the retaining plate 31 is connected to the valve body 6 by the return spring 29. By crimping and fixing the push rod 27, the base 27a of the push rod 27 is prevented from falling out of the large diameter hole 6b.

Further, an annular groove 6c is formed at the step between the small diameter hole 6a and the large diameter hole 6b, and an annular projection 6d is formed at the tip of the small diameter hole 6a, while the right end surface of the base 27a of the push rod 27 A recessed portion 27c is formed in the recessed portion 27c, and the reaction disk 26 is accommodated within this recessed portion 27c. Then, the cylindrical member 32 is lightly press-fitted into the outer periphery of the annular projection 6d, and the reaction disk 26 is placed inside the cylindrical member 32, as shown in FIG. By compressing and fitting the parts, the left end opening of the cylindrical member 32 is sealed.

Therefore, the gap between the annular projection 6d and the reaction disk 26 is surrounded by the cylindrical member 32.
The left end opening of is sealed by the reaction disk 26, and the gap between the annular projection 6d and the cylindrical member 32 is sealed by bringing the cylindrical member 32 into close contact with the outer periphery of the annular projection 6d. Even in the non-operating state of the device, the large diameter hole 6b
Communication between the small diameter hole 6a and the small diameter hole 6a can be reliably blocked.

Note that the part of the reaction disk 26 fitted into the cylindrical member 32 may simply be fitted inside the cylindrical member 32, or the fitting portion may be baked to form a part of the cylindrical member 32. It may also be integrally connected to the inside of the .

In the above configuration, when the brake pedal (not shown) is depressed and the input shaft 24 and the valve plunger 11 move to the left, the valve body 6
The valve body 14 is seated on the first valve seat 10 of the valve plunger 11 to block communication between the variable pressure chamber 5 and the constant pressure chamber 4, and the valve body 14 is lifted off the second valve seat 12 of the valve plunger 11 to communicate between the atmosphere and the variable pressure chamber 5.

As a result, atmospheric air is supplied into the variable pressure chamber 5,
Similar to the conventionally known brake booster, the power piston 2 is increased by the pressure difference before and after the power piston 2.
is advanced against the repulsive force of the return spring 29, and a braking action is performed. At this time, the brake reaction force applied to the push rod 27 is transmitted from the push rod 27 to the input shaft 24 via the reaction disk 26, the cylindrical member 25, and the valve plunger 11.

Next, when the force on the brake pedal is released from the brake operating state, the second valve plunger 11
The valve seat 12 seats on the valve element 14 to cut off communication between the variable pressure chamber 5 and the atmosphere, and the valve element 14 separates from the first valve seat 10 to communicate the variable pressure chamber 5 with the constant pressure chamber 4. The power piston 2 is returned to its original non-operating position by a return spring 29.

When the key member 30 comes into contact with the inner wall surface of the shell 1 due to the retraction of the power piston 2, the retraction of the valve plunger 11 that is linked to this stops, but the retraction of the power piston 2 and the valve body 6 continues. When the first valve seat 10 of the valve body 6 approaches the valve element 14 due to the retreat of the valve body 6, and the gap between the two becomes almost zero, the valve body 6
If the valve body 6 comes into contact with the key member 30 and stops, or if the valve body 6 does not come into contact with the key member 30 and the valve body 6 can retreat further, the power is applied with both the first valve seat and the second valve seat closed. piston 2
The backward movement of the machine stops. Therefore, the next time the input shaft 24 is moved forward again, the flow path of the valve mechanism 7 is immediately switched.

When the brake booster is inactive,
Even if the valve body 6 comes into contact with the key member 30 and stops, as described above, the cylindrical member 32 blocks communication between the large diameter hole 6b and the small diameter hole 6a, so that the large diameter It is possible to reliably prevent communication between the constant pressure chamber 4 on one side of the valve body and the variable pressure chamber 5 or the atmosphere on the other side of the valve body through the hole 6b and the small diameter hole 6a.

"Effect of the invention" As described above, according to the invention, communication between the large-diameter hole and the small-diameter hole can be interrupted by the cylindrical member fitted and tightly attached to the outer periphery of the annular projection. It is possible to reliably prevent one side of the valve body from communicating with the other side through the large diameter hole and the small diameter hole, and since it is only necessary to provide the above-mentioned cylindrical member, the configuration is simple and inexpensive. You can get the effect of becoming.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is an enlarged sectional view of the main part of FIG. 1. 1... Ciel, 6... Valve body, 6a...
Small diameter hole, 6b... Large diameter hole, 6c... Annular groove, 6d
... Annular projection, 7 ... Valve mechanism, 11 ... Valve plunger, 24 ... Input shaft, 26 ... Reaction disk, 27 ... Push rod, 27a ... Base, 27c ... Recessed part, 32 ... Cylinder shaped member.

Claims (1)

[Scope of Claim for Utility Model Registration] A large-diameter hole and a small-diameter hole are connected to the shaft of a valve body that is slidably disposed within the shell, and the base of the push rod is placed in the large-diameter hole and the valve body is placed in the small-diameter hole. The valve plungers constituting the mechanism are slidably fitted into each other, and a recess is formed in the base end face of the push rod to house a reaction disk therein, and a stepped portion between the large diameter hole and the small diameter hole is formed. forming an annular groove on the end face and protruding an annular projection protruding toward the push rod around the small diameter hole, and inserting the annular projection into the recess of the push rod;
In the reaction force mechanism of the brake booster, the reaction force of the brake force applied to the push rod is transmitted to the valve plunger and the input shaft connected thereto via the reaction disk, wherein a cylindrical member is provided on the outer periphery of the annular projection. A reaction force mechanism for a brake booster, characterized in that the reaction disk is fitted tightly into the cylindrical member and at least a portion of the reaction disk is fitted inside the cylindrical member.