JPH0352224Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a device for preventing the key member from coming off in a brake booster.

"Prior Art" Generally, a brake booster is equipped with a valve mechanism operated by an input shaft, and a valve plunger that constitutes the valve mechanism is inserted from the outside in the radial direction into a hole formed in the valve body. A key member engaged with the valve plunger prevents the key member from coming out of the valve body, and a retaining device prevents the key member from coming out of the hole.

Conventionally, as a device for preventing the key member from coming out, the key member is inserted from the outside in the radial direction into the hole formed in the valve body and engaged with the valve plunger, thereby preventing the valve plunger from being pulled out from the valve body. and a circular arc portion of a key member integrally connected to the retaining portion and surrounding approximately half of the outer periphery of the valve body; By arranging a retainer having spring properties surrounding approximately half of the outer circumference thereof, and connecting the retainer to the key member by engaging both ends of the retainer into holes drilled in the ends of the circular arc portion, A device has been proposed in which the key member is prevented from being pulled out from the hole (Utility Model Application No. 164965/1983).

``Problems that the invention attempts to solve'' However, with such a configuration of the retaining device,
Since both ends of the retainer need to be separately engaged in holes drilled in the ends of each arcuate portion, the assembly work is complicated.

"Means for Solving the Problem" In view of such circumstances, the present invention includes a key member having the above-mentioned retaining portion and a circular arc portion, and approximately half the circumference of the outer circumference of the valve body from the opposite side of the circular arc portion of the key member. In a retaining device comprising a surrounding retainer,
Engagement recesses are formed inside both ends of the arc portion of the key member, and engagement recesses are formed on the outside of both ends of the retainer due to the elasticity of the retainer, so that the key member and the retainer are moved outward in the radial direction of the valve body. Further, both ends of the retainer in the axial direction are formed with a pair of stepped end surfaces formed on the valve body, or between the stepped end surfaces formed on the valve body and the key member. This prevents the engaging recess and the engaging pawl from being disengaged from each other in the axial direction.

"Function" According to such a configuration, the key member and the retainer are simply assembled so as to fit around the outer periphery of the valve body, and the elasticity of the retainer causes the engaging pawls formed on the retainer to engage with the key member. Since it is possible to prevent the two from being separated radially outward by engaging with the recess, the assembly work can be made much easier than in the past.

At this time, the key member is restricted from moving in the axial direction by the hole into which the retainer is inserted, and the retainer is restricted from moving in the axial direction by a pair of stepped end faces formed on the valve body or by the stepped portion formed on the valve body. Since the end face and the key member sandwich each other and axial movement is also restricted, the two may move relative to each other in the axial direction by more than the necessary amount, preventing the engagement between the engagement recess and the engagement pawl. It is prevented from coming off in the axial direction.

``Example'' An example in which the present invention is applied to a tandem brake booster will be described below. In FIG. 3: front and rear front chambers 4 and rear chambers 5
A roughly cylindrical valve body 6 made of synthetic resin is slidably secured to the shaft portions of the rear shell 2 and center plate 3 while keeping airtight with seal members 7 and 8, respectively. It penetrates.

A front power piston 9 and a rear power piston 10 housed in the front chamber 4 and rear chamber 5 are connected to the valve body 6, respectively, and a front diaphragm 11 and a rear diaphragm are connected to the back of each power piston 9, 10. 12, respectively, and the front chamber 4 and rear chamber 5 are separated by the diaphragms 11 and 12.
and are divided into two rooms each, making a total of four rooms A,
B, C, and D are formed.

The valve mechanism 15 housed within the valve body 6 is equipped with a valve plunger 16 that is slidably fitted within the valve body 6, and the end of the valve plunger 16 is connected to an input shaft 17 that is linked to a brake pedal (not shown). are doing. Also, valve plunger 1
The tip of the push rod 18 faces the end surface of a reaction disk 19 provided in the large diameter portion at the right end of the push rod 18, and the tip of the push rod 18 is slidably protruded from the shaft portion of the front shell 1 via a seal member 20. The piston is interlocked with the piston of a master cylinder (not shown).

The power piston 2, valve body 6, etc. mentioned above are
Normally, the return spring 21 holds the valve plunger 16 in the non-operating position shown in the figure. The valve plunger 16 is in contact with the valve body 6 to restrict the free movement of the valve plunger 16 to the right, so that when the input shaft 17 and the valve plunger 16 are next operated, the valve mechanism 15 can immediately switch the fluid circuit. .

That is, in the free state, the key member 22 moves back greatly with respect to the valve body 6 to ensure a large gap between the valve body 23 and the valve seat 24 of the valve mechanism 15, but in the non-operating state, the key member 22 is advanced against the valve body 6 by contacting the inner surface of the valve plunger 16, thereby restricting the free retreat of the valve plunger 16 and keeping the gap between the valve body 23 and the valve seat 24 at a slight or substantially zero level. , then input shaft 1
7 and the valve plunger 16 are adapted to immediately switch the fluid circuit when actuated.

Next, the aforementioned chamber A is a constant pressure chamber into which negative pressure is constantly introduced, and communicates with an intake manifold (not shown) via a negative pressure introducing pipe 25 attached to the front shell 1. Further, this constant pressure chamber A is always in communication with the constant pressure chamber C via an axial passage 26 and a radial passage 27 formed in the valve body 6.

Furthermore, when the brake booster is not in operation, these constant pressure chambers A and C are connected to the axial passage 26, the gap between the valve body 23 and the valve seat 24 of the valve mechanism 15, and the radial passage 28 formed in the valve body 6. It communicates with the variable pressure chamber D through the valve body 6, and further communicates with the variable pressure chamber B through an axial passage 29 formed in the valve body 6.

In this state, negative pressure is introduced into each of the constant pressure chambers A, C and variable pressure chambers B, D, and the pressure becomes equal, and there is no pressure difference between the front and back of each diaphragm 11, 12, so that the return spring 21 is held in the non-operating position shown.

The key member 22, which prevents the valve plunger 16 from being pulled out of the valve body 6, is inserted from the outside into the radial hole 34 formed in the valve body 6, engages with the valve plunger 16, and locks the valve plunger 16. A retaining portion 22a that prevents the valve plunger 16 from being pulled out from the valve body 6, and a retaining portion 22a that is integrally connected to the outer end of the retaining portion 22a as shown in FIG. A pair of surrounding arcuate portions 22b and each of the arcuate portions 22
It is provided with engagement recesses 22c formed inside both ends of b.

On the other hand, the retainer 35 that prevents the key member 22 from coming out from the hole 34 is inserted from the opposite side of the key member 22 from the arcuate portion 22b, as shown in FIGS. 1 to 3. Valve body 6
The arcuate main body 35a surrounds approximately half of the outer periphery of the main body 35a, and the engaging claws 35b are formed by folding both ends of the arcuate main body 35a outward. The engagement recess 22
c. And each engagement claw 35
The axial width of b is set to such a width that even if the key member 22 moves a required amount with respect to the valve body 6, the two will not separate in the axial direction.

Further, the arcuate main body 35a of the retainer 35
A pair of abutting portions 35c are formed at both ends of the engaging claw 35b at positions shifted in the axial direction, and each abutting portion 35c extends in an arc shape radially outward from both ends of the arc-shaped main body 35a. , is formed to protrude further outward than the engaging claw 35b. Each contact part 35
C is an axial passage 29 formed in the valve body 6;
When the retainer 35 is assembled to a predetermined position of the valve body 6, the end surface opposite to the engaging claw 35b is set to a size that can be accommodated in the opening on the side of the pressure variable chamber D. The width is set to be adjacent to the step end face 29a formed inside the step part 29,
The step end face 29a and the key member 22 allow the retainer 35 to be held from both sides in the axial direction.

In this embodiment having the above configuration, in order to assemble the key member 22 and the retainer 35, first, the arcuate main body 35a of the retainer 35 is fitted into the outer periphery of the hole 34 formed in the valve body 6 on the opposite side to the opening side. At the same time, both end abutting portions 35c of the retainer 35 are housed in the axial passage 29 and brought into contact with or close to the step end face 29a.

Next, the retaining part 22a of the key member 22 is inserted into the hole 34 from the opposite side and its tip is engaged with the valve plunger 16, and the engaging recesses formed inside both ends of each arcuate part 22b are Assembling is completed by engaging the engaging claws 35b of the retainer 35 into the retainers 22c.

In this state, the key member 22 and the retainer 3
5 and 5 are prevented from being separated from each other in the radial direction by the engagement between the engagement recesses 22c and the engagement claws 35b formed respectively. Moreover, the key member 2
2, the movement in the axial direction is limited to a required amount by the hole 34 into which the retainer 22a is inserted, and the abutting portion 35c of the retainer 35 is connected to the valve body 6.
Since the axial movement is limited to the required amount by being sandwiched between the step end face 29a formed in the key member 22 and the arcuate portion 22b of the key member 22, the relative movement of both in the axial direction by more than the required amount is prevented. the above-mentioned engagement recess 2
2c and the engagement claw 35b are prevented from disengaging in the axial direction.

As shown in FIG. 4, an annular groove 36 is formed on the outer periphery of the valve body 6, and the arcuate main body 35a of the retainer 35 is fitted into the annular groove 36, so that both sides thereof are connected to the stepped end surfaces of the annular groove. 36a may be used. In this case, if a contact portion 35c is formed in the retainer 35, the contact portion 35c
The annular groove 36 can effectively prevent the retainer 35 from tilting when the key member 22 is displaced in the axial direction with respect to the valve body 6, but the contact portion 35c can be omitted if necessary. It is also possible to do so.

"Effect of the invention" As described above, according to the invention, the key member can be extremely easily prevented from coming off from the valve body simply by assembling the key member and the retainer so as to fit around the outer periphery of the valve body. This effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is a sectional view taken along the - line in FIG. 2, and FIG.
3 is a perspective view of the retainer 35, and FIG. 4 is a sectional view of main parts showing another embodiment of the present invention. 1...Front shell, 2...Rear shell, 6
... Valve body, 15 ... Valve mechanism, 16 ... Valve plunger, 22 ... Key member, 22a ... Stopping portion, 22b ... Arc portion, 22c ... Engagement recess, 2
9a... Step end surface, 34... Hole, 35... Retainer, 35a... Arc-shaped main body, 35b... Engaging claw,
35c... Contact portion, 36... Annular groove, 36a...
Step end face.

Claims (1)

[Scope of Claim for Utility Model Registration] A valve plunger of a valve mechanism that is slidably fitted into a valve body, and a valve plunger that is inserted from the outside in the radial direction into a hole formed in the valve body and engaged with the valve plunger. A retaining portion of a key member that prevents the plunger from being pulled out from the valve body; a circular arc portion of the key member that is integrally connected to the retaining portion and surrounds approximately half of the outer circumference of the valve body; Preventing the key member from coming out in a brake booster, which includes a retainer that surrounds approximately half of the outer periphery of the valve body and has both ends connected to each of the arcuate portions to prevent the key member from coming out of the hole. In the device, engaging recesses are formed inside both ends of the arcuate portion of the key member, and engagement recesses are formed outside both ends of the retainer due to the elasticity of the retainer, so that the key member and the retainer are connected to the valve body. an engaging pawl for preventing the retainer from being separated in the radial direction outward; and the key member to prevent the key member from coming off in the axial direction of the engagement between the engagement recess and the engagement pawl. Device.