JPS623544Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a drum brake in which the operating part of the mechanical actuating device is located outside the brake. The invention relates to a mounting device.

An example of a conventional device of this kind is explained with reference to FIGS. 1 to 3. 1 is a back plate fixed to a non-rotating part, 2 is a back plate movably mounted on the back plate 1 and has a T-shaped cross section. One brake shoe,
2a is a lining fixed to the outer periphery of shoe 2;
is a strut whose other end engages with the other brake shoe (not shown), and whose one end 3a is disposed between one brake shoe 2 and the back plate 1, and whose one side 3b is It is in sliding contact with the inner surface of the back plate 1. 4 is a brake lever whose intermediate portion is rotatably supported by a pin 5 on one end 3a of the strut 3, and whose inner end 4a engages with the inner edge of the brake shoe 2; Outer end 4b
is loosely fitted through a hole 1a drilled in the back plate 1 and extends in a substantially L-shape, and its hooked end portion 4c is fixed to the end of a control cable 6 that is remotely operated by a hand lever in the vehicle interior. Latch fitting 6
It is connected to the latching hole 6b of a. 7 is a fixing member fixed to the back plate 1, and a hook 6a
The normal return position of the brake lever 4 is regulated through the brake lever 4.

Next, the operation of the mechanical actuator in the above configuration will be explained.

Now, when the driver pulls the hand lever, the first
In the figure, the brake lever 4 rotates counterclockwise about the pin 5 via the control cable 6, and the inner end 4a is connected to one brake shoe 2.
are expanded to press into engagement with a brake drum (not shown), and the reaction force is transmitted to the strut 3, causing the other brake shoe (not shown) to expand and press into engagement with a brake drum in the same way. This allows the vehicle to remain stationary.

As is clear from the above structure, foreign matter enters through the hole 1a of the back plate 1 through which the brake lever 4 passes, or in other words, foreign matter enters from the outside of the brake to the inside and damages the inner peripheral surface of the brake drum or the outer periphery of the lining 2a. If it adheres to the surface, problems such as damage to the engaging surfaces between the two and failure to obtain normal frictional force occur. A conventional example for solving this problem will be explained in detail with reference to FIGS. The inside has a brake on the outside, and
Opposing locking portions 1A each having a U-shaped cross section are formed by cutting and bending in directions that separate them from each other.

The dust boot 8, which has an elastic portion 8c in the middle, has one annular portion 8a locked with the U-shaped locking portion 1A, and the brake lever 4 is tightly fitted into the hole of the other annular portion 8b. . This completely isolates the outside and inside of the brake to prevent foreign matter from entering.

However, the above-mentioned locking portion 1A having a U-shaped cross section
The following drawbacks occurred when forming a . That is, the locking part 1A is usually formed by press working, but first, slits are provided at the four widthwise corners of the hole 1a, and at the same time, the insides in the widthwise direction are made to stand up on the outside of the brake, and then However, the locking portion 1A having a U-shaped cross section had to be formed by bending both the upright ends away from each other, which required two steps and was troublesome. Furthermore, it is clear that the difficulty in processing increases as the thickness of the back plate 1 increases.

In view of the above-mentioned drawbacks, the present invention improves the shape of the locking portion of the back plate 1 that locks one annular portion of the flexible dust boot 8, and one embodiment thereof is shown in FIG. This will be explained with reference to FIG.

The construction and operation of the brake shoe 2, strut 3, brake lever 4, pin 5, control cable 6, and fixing member 7 are the same as in the conventional embodiment described above, and therefore a description thereof will be omitted. The back plate 1 is fixed to a non-rotating part of the vehicle body and has a rectangular hole 1a through which the brake lever 4 is loosely inserted. At the same time, a substantially U-shaped cutout is provided at a position separated from the brake member, and at the same time, a locking pawl 1B is formed by making the cutout stand upright on the outside of the brake at an angle less than a right angle. The locking pawl 1B of this example has an oblique shape whose protrusion height increases as the distance from the hole 1a increases. The dust boot 8 may have one annular portion 8a' having a shape that is compatible with the locking claw 1B and closing the hole 1b made by the locking claw 1B. Furthermore, if the annular portion 8a' is appropriately thicker than the elastic portion 8c, it will remain undeformed during brake operation, thereby maintaining its close contact with the outer surface of the back plate 1 and eliminating the risk of it coming off. It disappears.

FIGS. 6 and 7 are modified examples of the present invention, and only show the vicinity of the locking pawl 1B' formed on the back plate 1. That is, the locking claw 1 of this example
In B', the cutting direction is reversed from that of the previous embodiment. In other words, the rectangular hole 1a protrudes. Furthermore, if a locking pawl 1B' is also provided in the vicinity of the rectangular hole 1a in the width direction as shown in the figure, the locking portion of the dust boot increases, so that one annular portion 8a' of the dust boot and the outer surface of the back plate 1 are connected to each other. The sealing effect can be improved by further improving the adhesion of the adhesive.

As is clear from the above, according to the present invention, since the upright angle of the locking claws 1B and 1B' is less than a right angle, cutting and raising can be done in one process by simultaneous processing, which is inexpensive, and the back plate plate Even when the thickness is large, it can be easily processed. Furthermore, the present invention is by no means limited to the above-mentioned shape; for example, in FIG. 7, the locking pawl 1B' provided in the length direction of the rectangular hole 1a is divided into two parts, Of course, it may be one continuous locking claw, and the U-shaped incision may be made in a U-shape or semicircle. Furthermore, it is clear that the rectangular hole 1a can also be applied to an oval or circular hole. Moreover, the locking pawl is bent in the middle, and the dust boot annular part 8 is formed at the bent part.
It is also possible to clamp a' to the outer surface of the back plate to further improve the sealing effect of this part.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the mechanical actuating device of a conventional drum brake, Fig. 2 is a cross-sectional view taken from - in Fig. 1, Fig. 3 is a view taken in the direction of the arrow in Fig. 1, and Fig. 4 is a machine according to the present invention. FIG. 5 is a cross-sectional view of FIG. 4, FIG. 6 and FIG. 7 show other modifications of the present invention, and FIG. FIG. 7 is a plan view of FIG. 6. 1...back plate, 1a...hole, 1A...
Locking part, 1B, 1B'...Latching pawl, 2...One brake shoe, 4...Brake lever, 4b...
Outer end, 8...dust boot, 8a, 8a'...
One annulus.

Claims (1)

[Scope of utility model registration request] A drum brake having a mechanical actuating device that extends a pair of opposing brake shoes by actuating an outer end of a brake lever extending outside the brake through a hole drilled in a back plate. A substantially U-shaped locking pawl 1 is cut and raised at an angle less than a right angle toward the outside of the brake.
A dust boot mounting device for a drum brake is characterized in that a plurality of pawls 1B and 1B' are provided, and one annular portion 8a' of a dust boot covering a hole is engaged with the pawls 1B and 1B'.