JPS645140Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overtravel spring that is a component of an automatic gap adjustment device installed in a drum brake.

As a drum brake equipped with an automatic gap adjustment device, there is a dual servo brake shown in FIG.
A piston 100 is slidably fitted into a wheel cylinder body 102 attached to a buckle plate 101, and a brake shoe 103 is secured to the outer end of the piston. Reference numeral 104 designates an adjuster lever 103a that is pivotally supported by the brake shoe 103, and is engaged with the adjuster gear 105 so that it can be moved in only one direction. 106 is a return spring for the adjuster lever 104. The adjuster screw 105 is formed integrally with an adjuster screw 107, and the adjuster screw 107 is screwed into an adjuster nut 109 that is engaged with the other brake shoe 108. Member 11
It constitutes 0.

The intermediate portion is connected to the brake shoe 1 between the anchor pin 111 and the adjuster lever 104.
An overtravel spring 113 connected to an adjuster cable 112 guided by a cable guide 114 of No. 03 is interposed, and the piston 100 is indirectly connected to the adjuster lever 104 via the overtravel spring 113. The overtravel spring 113 is given an initial tensile load by the fitting 115 as shown in FIGS.
It is a coil spring that has a load characteristic that expands only when a predetermined load is applied, that is, when preventing over-adjustment, and does not operate the adjuster lever 104. 116
is a guide that prevents the spring 113 from moving blindly. Note that 117 is a hole for attaching the backing plate 101.

Overtravel spring 113 with such a structure
In this case, since the fitting 115 made of sheet metal is attached around the spring 113, there is a problem that a large mounting space is required and it is difficult to design the arrangement of parts.

In view of this problem, the present invention aims to provide an overtravel spring structure for a drum brake that is advantageous in terms of design by incorporating a spacing member for setting an initial load in the overtravel spring.

The present invention will be explained below with reference to the illustrated embodiments.

In FIG. 4, the reference numeral 1 indicates an overtravel spring made of a barrel-shaped coil spring, with diameter-reduced openings 1a and 1 at both ends.
b. The overtravel spring 1
Connecting members 2 and 3 formed so that the inner end enlarged portions 2a and 3a do not come out of the openings 1a and 1b of the spring 1 are arranged at both inner ends of the spring 1, respectively. The outer ends have openings 1a and 1b, respectively.
Engagement parts 2b and 3b that protrude more and form hooks
It is becoming. Then, the diameter of the spacing member 4, which is formed by winding a spring plate into a cylindrical shape, is elastically expanded to provide a gap 4c, and the enlarged inner ends 2a, 3a are inserted into the accommodation portions at both ends of the spacing member 4. 4a and 4b respectively, giving a free length to the spring 1, and forming the spacing member 4.
The interior is aligned with the axis lines.

From this state, as shown in FIG. 5, both the connecting members 2 and 3 are pulled out from the spacing member 4 to reduce the diameter of the spacing member 4, and the end surfaces of the inner end enlarged portions 2a and 3a of both the connecting members are The inner end enlarged portions 2 of both connecting members are brought into contact with the end surfaces of each of the accommodating portions 4a and 4b.
Overtravel spring 1 at the shoulders of a and 3a
is extended, giving the spring 1 a predetermined tensile load, that is, a load characteristic that allows it to be further extended only when over-adjustment is to be prevented.

Thus, the assembly of the overtravel spring 1 with the initial load set to the drum brake is as follows:
The engaging portion 2b or 3b of one connecting member is connected to the adjuster cable 5, and the engaging portion 3b or 2b of the other connecting member is connected to the adjusting hole 104 of the adjusting lever.
It is done by hanging it on a.

FIG. 6 shows another example of the structure of the spacing member 6.
The spacing member 6 has a cylindrical shape, and the enlarged inner end portion 3a of one of the connecting members 3 is fixed to one end by welding or the like, and the other end has a plurality of notches 6b in the axial direction.
6c and insert the inner end enlarged portion 2a of the other connecting member 2.
A housing portion 6a is formed into which the housing 6a can be elastically inserted. With the enlarged inner end portion 2a of the other connecting member inserted into the accommodating portion 6a of the spacing member 6, the overtravel spring 1 is placed inside with a free length given, and the engaging portion 2b of both connecting members 2 and 3 is inserted. , 3b to pull out the inner end enlarged part 2a from the accommodation part 6a, the accommodation part 6a will elastically contract in diameter, and the end surface of the inner end enlargement part 2a will come into contact with the end surface of the accommodation part 6a. As in the previous embodiment, overtravel spring 1
An initial tensile load can be applied to the

As explained above, the present invention has the above-mentioned configuration, and since the initial load is set by installing a spacing member inside the overtravel spring, the installation space is significantly reduced, and the mounting hole for the backing plate is widened. This increases the degree of freedom in designing the drum brake, and in the case of drum brakes of the same type, the spring can be made larger, increasing its mechanical strength. It can improve the reliability of the system.

Note that the spacing member also functions as a guide to prevent blind movement of the overtravel spring.

[Brief explanation of drawings]

Fig. 1 is a front view of a dual servo brake equipped with a conventional overtravel spring, Fig. 2 is a front view showing the installation state of the conventional overtravel spring, Fig. 3 is a side view of the same, and Fig. 4 is the present invention. FIG. 5 is a longitudinal sectional front view of the same part, and FIG. 6 is a front view showing another example of the structure of the spacing member. 1: Overtravel spring, 1a, 1b:
Opening, 2, 3: Connection member, 2a, 3a: Inner end enlarged portion, 2b, 3b: Engagement portion, 4, 6: Spacing member, 4
a, 4b, 6a: storage section.

Claims (1)

[Scope of utility model registration request] An overtravel spring formed of a coil spring having diameter-reduced openings at both ends, and an interval that forms a housing portion whose axis is aligned with the spring and whose diameter is elastically expandable at least one end. a member, and at least one inner end enlarged portion is inserted into the enlarged diameter receiving portion to provide a free length to the spring, and both inner end enlarged portions are respectively disposed inside the opening of the spring and on both end surfaces of the spacing member. An overtravel spring structure for a drum brake, comprising a pair of connecting members that abut each other to apply a predetermined tensile load to the spring, and cause engaging portions at outer ends to respectively protrude from the openings.