JPH11171003A - Master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sleeve from being abraded by projecting sections of a spring retainer even when they slide to come in contact with the guide groove wall of the sleeve while a master cylinder is in operation. SOLUTION: In this master cylinder MC, a body 2 and a cap 3 constitute a cylinder housing 1, and a 1st piston 4 and a 2nd piston are installed so that they are guided by and slidable by a sleeve 8 which is fitted into the cylinder housing g1. At the same time, a 1st and 2nd pressure chambers 9, 10 are partitioned to arranged spring mechanisms 11, 12 to energize the 1st piston 4 and the 2nd piston toward retreating direction, and further, a plurality of projecting sections 27C are formed at the periphery of a spring retainer of the spring mechanism 11 which energizes the 1st piston 4 in an radially outward direction and both side edges of the width direction of respective projecting sections 27C are rounded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a master cylinder used for various brake devices of an automobile.

[0002]

2. Description of the Related Art Conventionally, as this type of master cylinder, for example, there is a tandem master cylinder mc shown in FIG. 5, and a brake booster (brake booster) not shown.
Mounted on the front of the MV. The cylinder housing 1 of the master cylinder mc includes a body 2 having an opening at one end, and a cap 3 which is secured to the opening of the body 2 by a retainer so as to be prevented from falling off.

[0003] A sleeve 8 is fitted in the cylinder housing 1, and a primary piston 4 and a secondary piston 5 are fitted with the cap 3 so that a piston guide portion 3a formed in the cap 3 is fitted. , Are guided and supported by the sleeve 8, and are slidably disposed.

A first pressure chamber 9 is defined inside the cylinder housing 1 by a primary piston 4, a secondary piston 5 and the cap 3. A first pressure chamber 9 is defined by the secondary piston 5 and an inner wall surface of the body 2.
A second pressure chamber 10 is defined. In addition, the primary piston 4 and the secondary piston 5 are formed with concave portions 4a, 5a each having an open end.
Small holes 4b, 5b are formed in the peripheral wall forming the recesses 4a, 5a.
Are provided to form replenishing liquid passages from the oil reservoir 23 to the first and second pressure chambers 9 and 10 at the brake release position.

[0005] The first pressure chamber 9 and the second pressure chamber 10 are provided with spring mechanisms 11 and 12, respectively. Between the piston 5 and between the recess 5a of the secondary piston 5 and the body 2
The primary piston 4 and the secondary piston 5 are respectively urged in the retreating direction.

The spring mechanism 11 includes a return spring 15, a guide pin 16 having a large head 16a, and a spring retainer 17 in the shape of a mountain hat (or cylindrical with a flange).
And a guide pin engaging member 18. The return spring 15 is contracted between a peripheral edge of the guide pin engaging member 18 and a peripheral edge 17a of the spring retainer 17,
One end thereof is fitted to an enlarged diameter portion formed on the bottom surface of the concave portion 4a of the primary piston 4. The guide pin 16 is arranged so as to protrude in the axial direction of the piston at a predetermined distance from the bottom surface of the concave portion 4a. Is being worn. In the spring retainer 17, the hole 17b provided at the top of the mountain hat shape slides freely on the guide pin 16 within a predetermined stroke range (a range slightly exceeding the retreat limit of the primary piston 4). , Its large head 16
a. The spring mechanism 12 includes:
There is only a return spring.

In such a master cylinder mc, the primary piston 4 and the secondary piston 5 move in the left direction in the figure against the urging force of the spring mechanisms 11 and 12, respectively. When pushed into the chamber 10, the hydraulic pressure in the pressure chambers 9, 10 rises, and the hydraulic fluid is fed from the outlets 13, 14 to a brake system (not shown).

Incidentally, the conventional master cylinder mc
Peripheral portion 17a of spring retainer 17 of spring mechanism 11
As shown in FIGS. 6A and 6B, a plurality of (for example, four) protruding end portions 1 protruding outward in the radial direction are provided.
7c is formed integrally with the sleeve 8, and a guide groove 20 having a fixed width or a trapezoidal shape penetrating through the outer peripheral surface thereof in the axial direction in which the protruding end portion 17c is inserted and engaged with the sleeve 8 (FIG. 6). In FIG. 6A and FIG. 6B, a guide groove having a constant width is formed. In these guide grooves 20,
A locking portion 20a is formed at a position slightly beyond the retreat limit of the primary piston 4 from the end of the sleeve 8 to abut and lock the protruding end 17c.

With such a structure, the conventional master cylinder mc is formed by the guide groove 20 formed through the outer peripheral surface of the sleeve 8 during the brake operation.
While preventing deformation of the sleeve 8, the guide groove 20
The ineffective stroke can be freely set in combination with the brake booster (brake booster) MV without restricting the retreat limit of the primary piston 4 and the secondary piston 5. (Japanese Patent Application No. 8
-187081)

[0010]

However, in the conventional master cylinder mc, when the protruding end portion 17c of the spring retainer 17 inserted through the guide groove 20 formed in the sleeve 8 is actuated, the spring groove 17 is in contact with the guide groove. There is a possibility that there is a possibility of sliding contact with the wall surface of the sleeve 20. At that time, there is a problem that the corner of the cut surface of the protruding end portion 17c may be caught on the sleeve 8 or the sleeve 8 may be worn.

In addition, there is a secondary piston 5 formed with a projection having a low height for positioning the spring retainer 17 on a rear end surface of the secondary piston 5. However, a contact portion with the spring retainer 17 is simply tapered. When an excessive pulling force acts on the primary piston 4, there is a problem that the deformation of the protruding end portion 17c cannot be prevented.

[0012] The present invention has been made in view of such a point.
The object of the present invention is to solve the above problem, and to prevent the spring retainer from being caught on the sleeve or worn out even when the protrusion of the spring retainer slides on the guide groove wall surface of the sleeve during operation. To provide a cylinder.

Another object of the present invention is to provide a master cylinder which prevents deformation of the spring retainer even when an excessive pulling force acts on the primary piston.

[0014]

According to a first aspect of the present invention, there is provided a cylinder housing comprising a body having an opening at one end and a cap coupled to the opening of the body. First and second pistons, which are inserted into the cap and guided by a sleeve fitted in the cylinder housing, are slidably provided. The first and second pistons and the cap are used to slide the first and second pistons. A first pressure chamber, a second pressure chamber is defined by the second piston and the body body, and a spring mechanism is disposed in each of the first and second pressure chambers; 1. A spring mechanism disposed in the first pressure chamber for biasing the second piston in a backward direction, the spring mechanism having a substantially cylindrical spring retainer abutting a rear end surface of the second piston, A guide pin whose head is inserted in the retainer is engaged with the recess bottom surface formed at the tip end of the first piston as well as locked in the retainer,
A return spring contracted between the spring retainer and the first piston, and a peripheral portion of the spring retainer includes:
A protruding end portion that protrudes outward in the radial direction is formed, and in the sleeve, in the axial direction in which the protruding end portion is inserted and engaged, a guide groove that penetrates an inner peripheral surface thereof,
The following is a description of a master cylinder in which a locking portion for abutting the protruding end portion is formed at a position slightly beyond the retreat limit.

(1) A round portion is formed at both ends in the width direction of the protruding end portion formed on the peripheral edge portion of the spring retainer.

(2) In the above (1), the rounded portion formed at the protruding end is formed by bending or folding the both side ends inward to each other.

(3) In the above (1), a column or a cylindrical projection is formed on the rear end surface of the second piston so that the inner peripheral surface of the spring retainer is loosely fitted. It is characterized by.

Since the present invention is constructed as described above, when the master cylinder is operated, the spring retainer is formed with rounded portions at both ends in the width direction of the projected end. Can be prevented from being caught on the sleeve and abrasion of the sleeve even if the sleeve slides on the guide groove wall surface of the sleeve.

Further, since the inner peripheral surface of the spring retainer is loosely fitted to a cylindrical or cylindrical projection formed on the rear end surface of the second piston, an excessive pulling force acts on the primary piston. Also, the spring retainer is not deformed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. That is, in the master cylinder, both ends of the protruding end portion of the spring retainer that is inserted into the guide groove of the sleeve are bent or turned inward to each other, or are welded or coated with resin to form a rounded portion. Therefore, at the time of operation, even if the protruding portion slides on the guide groove wall surface of the sleeve, the protruding portion does not catch on the sleeve or wear the sleeve. Further, a columnar or cylindrical protrusion is formed on the rear end surface of the second piston, and the inner peripheral surface of the spring retainer is loosely fitted to the protrusion, so that the first piston (primary piston) is excessively large. Even if a strong pull-out force acts, the deformation of the spring retainer can be prevented.

1 to 3 show an embodiment of a master cylinder according to the present invention. FIG. 1 is a longitudinal sectional view of the master cylinder MC, FIG. 2 is an enlarged view of a portion A in FIG. 1, and FIG. It is a figure which shows the spring retainer 27. 1 and 2,
5 and 6 are denoted by the same reference numerals, and description thereof will be omitted.

In FIGS. 1 and 2, a plurality (two in this embodiment) of the master cylinder MC protruding radially outward is provided on a peripheral portion 27a of a spring retainer 27 instead of the spring retainer 17. The protrusions 27c are integrally formed, and as shown in FIG.
The widthwise side edges of the master cylinder in the retreating direction of the master cylinder,
Bending or folding is performed inside each other so that the bent or folded portion forms a round portion 27d having a cylindrical shape. At the same time, the entire rounded portion 27d has substantially the center of its radial length at the center of the sleeve 8d.
And is formed in a trapezoidal shape having a large width outward in the radial direction. 27b is a hole provided on the top of the spring retainer 27, and the guide pin 16 is inserted into the hole 27b.

The sleeve 8 has the protruding end 2
In the axial direction in which the rounded portion 7c and the rounded portion 27d are inserted and engaged with each other, the guide groove 20 which is formed to have a constant width and penetrates the outer peripheral surface thereof is inserted from the end of the sleeve 8 into the primary piston. At a position slightly beyond the retreat limit of No. 4, a locking portion 20a is formed to make the rounded portion 27d abut and lock. Therefore, even when the master cylinder MC is operated, even if the master cylinder MC slides on the guide groove wall surface of the sleeve, the rounded portion 27d of the protruding end portion 27c does not catch on the sleeve or wear the sleeve 8.

Further, as shown in FIG. 2, the guide groove 20 formed in the sleeve 8 penetrates the inner and outer peripheral surfaces thereof and becomes wider than the width of the protruding end 27c and the rounded portion 27d. Therefore, even if the protruding end portion 27c and the rounded portion 27d are inserted along the guide groove 20,
The primary piston 4
With the reciprocation of, there is no hindrance to the movement of the spring retainer 27.

The rounded portion 27d is formed by the above-described bending or folding process, and also by forming the protruding end portion 2d.
Both ends in the width direction of 7c may be formed by welding or coating a synthetic resin having oil resistance and abrasion resistance and having a small friction coefficient.

As another example of the guide groove 20 having a constant width and a large width formed in the sleeve 8, a trapezoidal guide groove 21 as shown in FIG. 4 can be formed. That is,
The trapezoidal guide groove 21 is a guide groove having a wide groove width at the end of the sleeve 8 and a narrow groove width at the locking portion 21a. And, as described above, the primary piston 4 is inserted into the guide groove 21 from the end of the sleeve 8.
The locking portion 2 which abuts the rounded portion 27d of the spring retainer 27 at a position slightly beyond the retreat limit and locks it.
1a is formed.

Next, in FIG. 1, a cylindrical or cylindrical shape (see FIG. 1) is formed such that the outer peripheral surface of the secondary piston 5 is loosely fitted to the inner peripheral surface of the spring retainer 27 in the primary piston 4 direction. 1 indicates a columnar shape). The protrusion 5c is
The secondary piston 5 is formed so as to be substantially perpendicular to the rear end face of the rear end face thereof from the base thereof, and has a height equal to a protruding end portion 27c formed on a peripheral edge portion 27a of the spring retainer 27.
Even if an excessive force is applied to the rounded portion 27d, for example, an excessive release force acts on the primary piston 4, the spring retainer 27 is not deformed and the primary piston 4 has a height that does not hinder the normal stroke. is there.

When the protrusion 5c has a cylindrical shape,
The guide pin 16 of the spring mechanism 11 is
If the large head 16a has an outer diameter such that the large head 16a can be loosely fitted, the height of the protruding portion 5c is limited (the height is limited so as not to interfere with the normal stroke of the primary piston 4). Is eliminated.

As described above, the projecting portion 5c is formed on the rear end surface of the secondary piston 5, and the projecting portion 5c
The inner peripheral surface of the spring retainer 27 is loosely fitted,
Even if an excessive pulling force acts on the primary piston 4, the spring retainer 27 is not deformed.

The technique of the present invention is not limited to the technique in the above-described embodiment, but may be implemented by means of other modes that perform the same function. Can be changed or added.

[0031]

As is apparent from the above description, according to the master cylinder of the present invention, the rounded portions are formed at both ends in the width direction of the protruding end formed on the peripheral portion of the spring retainer. When the master cylinder is operated, the protrusion of the spring retainer is prevented from being caught on the sleeve, and the sleeve is not worn even if the protrusion contacts the guide groove wall surface of the sleeve. That is, wear of the sleeve is prevented.

According to the master cylinder of the present invention,
Since a cylindrical or cylindrical protrusion is formed on the rear end surface of the second piston such that the inner peripheral surface of the spring retainer is loosely fitted, even if an excessive force is applied to the primary piston, The spring retainer is prevented from being deformed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a master cylinder of the present invention.

2 is an enlarged view of a portion A in FIG. 1, wherein FIG. 2 (a) is a sectional view thereof, and FIG. 2 (b) is a bottom view thereof.

3 (a) is a side view of the spring retainer, FIG. 3 (b) is a sectional view taken along line IIIb-IIIb of FIG. 3 (a), and FIG. FIG. 3B is a bottom view of FIG.

4 is an enlarged view showing another example of FIG. 2, wherein FIG. 4 (a) is a cross-sectional view thereof, and FIG. 4 (b) is a bottom view thereof.

FIG. 5 is a longitudinal sectional view showing a conventional master cylinder.

6 is an enlarged view of a portion B in FIG. 5, where FIG. 6 (a) is a cross-sectional view thereof, and FIG. 6 (b) is a bottom view thereof.

[Explanation of symbols]

 MC Master cylinder 1 Cylinder housing 2 Body 3 Cap 4 Primary piston 5 Secondary piston 5c Projection 8 Sleeve 9 First pressure chamber 10 Second pressure chamber 11 Spring mechanism 12 Spring mechanism (return spring) 15 Return spring 16 Guide pin 16a Large Head 17, 27 Spring retainer 17a, 27a Peripheral edge 17b, 27b Hole 17c, 27c Protrusion 18 Guide pin engaging member 20, 21 Guide groove 20a, 21a Locking portion 27d Round portion

Claims (3)

[Claims] 1. A cylinder housing comprising a body having an opening at one end and a cap coupled to the opening of the body, which is inserted into the cap and fitted into the cylinder housing. First and second pistons guided by the sleeve are slidably provided, and a first pressure chamber is formed by the first and second pistons and the cap. A second pressure chamber is defined by each of the first and second pressure chambers, and a spring mechanism is disposed in each of the first and second pressure chambers to urge the first and second pistons in a retreating direction, The spring mechanism disposed in the first pressure chamber includes:
A substantially cylindrical spring retainer that abuts a rear end surface of the second piston; a concave bottom surface that is inserted into the retainer, the head of which is engaged with the retainer, and that is formed on the distal end side of the first piston; And a return spring contracted between the spring retainer and the first piston, and a peripheral end of the spring retainer has a protruding end protruding radially outward. At the same time, the sleeve comes into contact with the guide groove which penetrates the outer peripheral surface thereof in the axial direction in which the protrusion is inserted and engages with the sleeve, at a position slightly beyond the retreat limit. A master cylinder in which a locking portion to be formed is formed, wherein a rounded portion is formed at both ends in the width direction of the protruding end portion formed in a peripheral portion of the spring retainer. 2. The master cylinder according to claim 1, wherein the rounded portion formed at the protruding end is formed by bending or folding the both ends inwardly. 3. A column or a cylindrical projection to which an inner peripheral surface of the spring retainer is loosely fitted is formed on a rear end surface of the second piston. Master cylinder described in 1.