JPH09295570A - Servo unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of part items as well as to lessen operation processes in time of manufacturing. SOLUTION: A sealing member 3 is provided with a contact part 3d being more projected up to the front side than a stopper part 1B of a shell. When a key member 27 is situated in a nonoperational position, first of all, it contacts with this contact part 3d of the sealing member 3, then this contact part 3d is compressed to some extent and thereby the key member 27 contacts with the stopper part 1B of the shell and thus it is stopped at this nonoperational position. Accordingly, it is unnecessary to install a knocking preventing stopper in the key member 27. Therefore, the number of part items of a brake servo unit and manufacturing processes are reducible as compared with the part, and thus this brake servo unit can be made inexpensive in cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a booster used for an automobile brake or the like, and more particularly to a booster capable of preventing a hitting sound when a key member is in a non-actuated position.

[0002]

2. Description of the Related Art Conventionally, a booster having the following configuration has been known. That is, a shell having an opening portion and a stopper portion on the rear side, a valve body slidably provided in the shell and having an outer peripheral portion on the rear side projected from the opening portion of the shell to the outside of the shell,
An annular seal member made of an elastic member, which is provided on the rear side of the engaging portion of the shell and which maintains airtightness between the opening of the shell and the outer peripheral portion of the valve body,
A doubler comprising a valve plunger that forms a part of the valve mechanism and is slidably provided on the valve body, and a key member that engages with the valve plunger and prevents the valve plunger from falling out of the valve body. Force devices are known. In such a conventional booster, rubber stoppers are attached to the key member at a plurality of locations facing the stopper portion of the shell. Then, when the key member is biased toward the stopper portion when the booster is not in operation, the rubber stopper provided on the key member abuts the stopper portion of the shell, so that the key member is not locked. It is designed to stop in the operating position. As described above, conventionally, the stopper provided on the key member prevents the key member and the stopper portion of the shell from directly contacting each other, and prevents the tapping sound when they contact each other. .

[0003]

As described above, in the conventional booster, a plurality of stoppers are attached to the key member, so that the number of parts constituting the booster increases and the booster increases. There is a drawback in that the number of working steps in manufacturing the device increases, which in turn increases the cost of the booster.

[0004]

In view of the above-mentioned circumstances, the present invention provides a shell having an opening portion and a stopper portion on the rear side, and a shell provided slidably in the shell and having an outer peripheral portion on the rear side. Of the valve body protruding from the opening to the outside of the shell, and an elastic member, which is provided on the rear side of the engaging portion of the shell and between the opening of the shell and the outer peripheral portion of the valve body. An annular seal member that maintains airtightness, a valve plunger that forms a part of the valve mechanism and is slidably provided on the valve body, and the valve plunger are engaged, and the valve plunger falls off from the valve body. In the booster having a key member for preventing the key member, a contact portion is formed in the seal member so as to project toward the front side from the stopper portion of the shell and come into contact with the key member. Member, which is constituted so as to abut against the stopper portion of the shell from contact with the contact portion of the seal member.

[0005]

According to this structure, the contact portion is originally provided on the seal member of the booster so that the contact portion serves as a cushioning material when the key member is in the non-actuated position. Can be used. That is, when the key member is in the non-actuated position, it first contacts the contact portion of the seal member and then contacts the stopper portion of the shell, so that when the key member and the stopper portion of the shell contact each other. A tap sound can be prevented. Therefore, since it is not necessary to provide a stopper for preventing the tapping sound on the key member, it is possible to reduce the number of parts of the constituent members of the booster and also to reduce the work steps when manufacturing the booster. it can. Therefore, the cost of the booster can be reduced as compared with the conventional case.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, reference numeral 1 is a shell of a brake booster, and the shell 1 extends rearward (rightward) toward the rear side. The cylindrical portion 1A is formed. The cylindrical portion 1A has a large-diameter portion 1a on the front side thereof and a small-diameter portion 1b on the rear side thereof, and a stopper portion 1B extending in the radial direction is formed at a boundary portion thereof. The stopper portion 1B is formed by folding back in the radial direction. The opening 1c is formed by the rear end of the small diameter portion 1b. Shell 1
A valve body 2 having a substantially cylindrical shape is slidably provided therein, and an outer peripheral portion on the rear side of the valve body 2 penetrates the cylindrical portion 1A of the shell 1 to extend from the opening 1c to the shell 1
Project outside. As shown in an enlarged manner in FIG. 2, an annular seal member 3 is fitted from the rear side to the small-diameter portion 1b of the cylindrical portion 1A of the shell 1, and the outer peripheral portion of the valve body 2 on the rear side is fitted. The inner peripheral portion of the seal member 3 is slidably penetrated. The seal member 3 is made of rubber, and the seal member 3 allows the outer peripheral portion of the valve body 2 and the opening 1c (small diameter portion 1b) of the shell 1 to be formed.
Holds airtightness between. An annular retainer 4 is integrally embedded in the rear end surface of the seal member 3, and the radial portion 4a of the retainer 4 is brought into contact with the rear end of the small diameter portion 1c from the rear side. There is. A generally cup-shaped conventionally known dust cover 5 covers the opening 1c of the shell 1 and the outer peripheral portion of the valve body 2 protruding from the opening 1c on the rear side. The dust cover 5 has a tubular inner peripheral portion fitted on the small-diameter portion 1c of the shell 1 from the rear side, and in this state, the inner peripheral portion on the front side and the taper on the rear side. The outer peripheral edge of the radial direction portion 4a of the retainer 4 is engaged with the boundary portion 5a with the portion. This prevents the dust cover 5 from falling off the small diameter portion 1c of the shell 1. Next, a power piston 6 is connected to the outer peripheral portion of the valve body 2, and a diaphragm 7 is stretched on the back surface of the power piston 6. The diaphragm 7 divides the inside of the shell 1 into a constant pressure chamber A on the front side and a variable pressure chamber B on the rear side. Further, in the valve body 2, a conventionally known valve mechanism 11 for switching a fluid circuit among the constant pressure chamber A, the variable pressure chamber B and the atmosphere is provided. That is, the valve mechanism 1
1 is an annular vacuum valve seat 12 provided on the valve body 2,
A valve plunger 14 slidably fitted to the valve body 2 and having a rear end connected to the input shaft 13, an annular atmosphere valve seat 15 formed on the valve plunger 14, and both valve seats A substantially cylindrical valve body 16 seated on 12, 15
And a spring 17 for biasing the valve body 16 toward both valve seats 12 and 15 for seating. The vacuum valve 21 is formed by the vacuum valve seat 12 and the seat portion of the valve body 16 that comes in contact with and separates from the vacuum valve
The constant pressure passage 21 formed in the valve body 2 constantly communicates the outer peripheral side of the vacuum valve 21 with the constant pressure chamber A. Negative pressure is constantly introduced into the constant pressure chamber A through the negative pressure introducing pipe 22. In addition, the atmosphere valve 2 is constituted by the atmosphere valve seat 6 and the seat portion of the valve body 16 which is brought into contact with and separated from the atmosphere valve 2.
3, the intermediate portion between the atmosphere valve 23 and the vacuum valve 21 is in constant communication with the variable pressure chamber B via the variable pressure passage 24 formed by the radial hole 2a of the valve body 2. Further, the inner peripheral side of the atmosphere valve 23 is in constant communication with the atmosphere via an atmosphere passage 25 formed by the internal space of the valve body 2. A filter 26 is provided in the air passage 25.
Is provided. A key member 27 inserted into the radial hole 2a (transformation passage 24) of the valve body 2 is engaged with the valve plunger 14 to prevent the valve plunger 14 from falling off the valve body 2. ing. The input shaft 13 is connected to the rear side of the valve plunger 14, while the front end surface of the valve plunger 14 faces a reaction disc 32 arranged to face the base of the output shaft 31. Further, the return spring 33 is mounted over the front end of the valve body 2 and the front wall surface of the shell 1, so that the inactive valve body 2 is biased toward the rear side. The key member 27 is stopped at the non-operating position shown in the drawing in which the key member 27 contacts the stopper portion 1B of the shell 1. The above-described configuration and the operation based thereon are the same as those of the conventionally known brake booster. Therefore, in this embodiment, as shown in FIG.
As shown in the enlarged view, the seal member 3 is improved so that the rubber stopper 34 (FIG. 3) provided in the conventional general key member 27 is omitted. That is, the seal member 3 of the present embodiment is provided with the annular groove 3a at the axially central position of its inner peripheral portion, and the inner peripheral portion on the front side of this annular groove 3a is the front lip portion 3b. The inner peripheral portion on the rear side of the annular groove 3a is a rear lip portion 3c. The front lip portion 3b and the rear lip portion 3c are brought into close contact with the outer peripheral surface of the valve body 2. Further, the seal member 3 of the present embodiment has an abutting portion 3d in which an inner side portion of the end face on the front side (left side) is projected toward the front side rather than the outer side. The contact portion 3d is continuous in the circumferential direction, and as shown in FIG. 2, the seal member 3 is attached to the small diameter portion 1 of the shell 1.
When it is fitted in b and is brought into contact with the stopper portion 1B from the rear side, the contact portion 3d becomes the stopper portion 1B of the shell 1.
It is located closer to the front side than the inner peripheral edge of. When the key member 27 returns from the operating state to the non-operating position shown in FIG. 1, first, the key member 27 contacts the contact portion 3d of the seal member 3 as shown in FIG. The contact portion 3d is compressed in the axial direction and then contacts the stopper portion 1B to stop at the non-operating position. As described above, in this embodiment, since the seal member 3 is provided with the contact portion 3d, the key member 27 is made of rubber such as the conventional device shown in FIG. 3 at the position facing the stopper portion 1B. The stopper 34 is not provided. According to the seal member 3 configured as described above, the key member 27 that is biased toward the rear side together with the valve body 2 and the like by the return spring 33, as shown in FIG.
It abuts the abutting portion 3d of the seal member 3. Thereafter, since the contact portion 3d is axially compressed as the return spring 33 continuously urges the key member 27, the key member 27 comes into contact with the stopper portion 1B and stops. . That is, as a result, the key member 27 is stopped at the non-actuated position, and the valve body 2 and the like are also stopped at the non-actuated position shown in FIG. When the input shaft 13 is moved forward from the non-operating state shown in FIG. 1, the key member 2
7 is first separated from the stopper portion 1B of the shell 1, and accordingly, the contact portion 3d is elastic by its own.
It swells to the front side from B, and eventually this contact portion 3
The key member 27 is separated from d. As described above, in the present embodiment, when the key member 27 is located in the non-actuated position, the key member 27 first contacts the rubber contact portion 3d and then contacts the stopper portion 1B. Therefore, it is possible to prevent the tapping sound from being generated when the key member 27 contacts the stopper portion 1B. By forming the contact portion 3d on the seal member 3,
Unlike the conventional case shown in FIG. 3, it is not necessary to provide the key member 27 with the rubber stopper 34. In other words, the number of parts of the brake booster can be reduced and the number of work steps at the time of manufacturing the brake booster can be reduced as compared with the related art shown in FIG. Therefore, the cost of the brake booster can be reduced as compared with the conventional case. In addition, although the above-mentioned embodiment explained the case where the present invention was applied to a single type booster, a tandem type booster and a triple type booster provided with a plurality of constant pressure chambers and variable pressure chambers in the shell 1. It can also be applied to the booster.

[0007]

As described above, according to the present invention, the number of parts can be reduced as compared with the conventional one, and
The effect that the working process at the time of manufacture can be reduced is acquired.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state immediately before the main part shown in FIG. 1 stops at an inoperative position.

FIG. 3 is a sectional view showing a conventional technique.

[Explanation of symbols]

 1 ... Shell 2 ... Valve body 3 ... Seal member 3d ... Contact part 14 ... Valve plunger 27 ... Key member

Claims (2)

[Claims] 1. A shell having an opening and a stopper on the rear side, and a valve slidably provided in the shell and having an outer peripheral portion on the rear side projected from the opening of the shell to the outside of the shell. An annular seal member, which includes a body and an elastic member, is provided on the rear side of the engaging portion of the shell, and maintains airtightness between the opening of the shell and the outer peripheral portion of the valve body, and the valve mechanism. A booster comprising a valve plunger that constitutes a portion and is slidably provided on the valve body, and a key member that engages with the valve plunger and prevents the valve plunger from falling off the valve body, The seal member is formed with an abutting portion projecting toward the front side with respect to the stopper portion of the shell and abutting the key member,
The booster, wherein the non-actuated key member is configured to come into contact with the contact portion of the seal member and then with the stopper portion of the shell. 2. The contact portion is formed so as to be continuous in the circumferential direction, and the stopper portion is formed by folding back a cylindrical portion on the rear side of the shell in the radial direction. An annular retainer is embedded in the rear side of the seal member, the seal member is brought into contact with the stopper portion from the rear side, and is fitted into the cylindrical portion of the shell at the rear side position of the stopper portion, and The booster according to claim 1, wherein, in that state, the radial portion of the retainer is brought into contact with the rear end of the shell from the rear side.