JPH032014Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a brake shoe used in a drum brake.

Prior Art A brake shoe is provided with a pair of brake shoe webs each having an arcuate shape and a notch opening toward the inner circumference in the longitudinal middle portion thereof, and is swingably attached to a bucking plate at one end. a show-hold down pin which has a middle portion inserted into the notch of the show web, and a predetermined preload is applied between the show web and the other end of the show web; A drum brake equipped with a shoe hold down device that has a coil spring interposed in a state where a u hold down pin is inserted, and supports the brake shoes on the bucking plate in a state where they can be mutually expanded. It has been known. A rotary drum is disposed on the outer circumferential side of the pair of brake shoes with a predetermined gap between the outer circumferential surfaces and the respective outer circumferential surfaces.

The above-mentioned coil spring is usually sandwiched between a pair of cups in the axial direction, and is interposed between the other end of the shoe hold down pin and the shoe web, and is mounted on a rotating drum on the outer periphery of the brake shoe. If the brake shoe is pushed out in the outer circumferential direction when the brake shoe is not installed, the shoe hold down pin will largely protrude from the opening of the notch, causing the cup and coil spring to fall off the shoe web. It was hot.

For this reason, conventionally, an engaging hole is formed at a predetermined position on the outer circumferential side of the notch in the show web, and an engaging claw is provided on the outer peripheral edge of the cup on the side that contacts the show web to protrude toward the backing plate. By inserting the engaging claw into the engaging hole, the cup and the coil spring are prevented from falling off from the show web based on the engagement between the engaging hole and the engaging claw. .

Problems to be solved by this invention However, in this case, two types of cups are required, which requires a relatively large number of parts and assembly work, and it is also necessary to provide the above-mentioned engaging claws on the cup on the show web side. The provision of such a drum brake increases the number of steps involved in molding the cup, making it difficult to provide a drum brake at a low cost.

Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is to provide a drum brake as described above, in which one end of the coil spring is attached to the shew web. The present invention is characterized in that a protrusion is provided which engages with the shew web in a manner immovable in the inner circumferential direction of the shew web.

Operation and Effect of the Invention By doing this, one end of the coil spring inserted between the other end of the shew-hold down pin and the shew web with the shew-hold down pin inserted therein can be attached to the shew web. Since the shoe web is engaged with the protruding portion of the shoe web so that it cannot move relative to the inner circumference, even if a rotating drum is not disposed on the outer circumference of the brake shoe, the brake shoe will move relatively far toward the outer circumference. Even if pushed out, the cup and coil spring can be prevented from falling off the shoot web. In addition, since only one cup of one type is required, the number of parts and assembly work can be reduced compared to conventional methods, and there is no need to form engagement claws on the cup, unlike drum brakes. can be provided at a lower cost overall.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 3 is a diagram showing an example of a drum brake equipped with a brake shoe to which the present invention is applied,
On the bucking plate 10 is the show web 1.
A pair of brake shoes 16 and 18 having numbers 2 and 14, respectively, serve as shoe hold down devices 20 and 22.
are supported so that they can expand with respect to each other. One end of the shew webs 12, 14 that are close to each other is brought into contact with a side surface of an anchor pin 24 fixed on the bucking plate 10, and the other ends of the shew webs 12, 14 are arranged so as to be in contact with the sides of an anchor pin 24 fixed on the bucking plate 10. The brake shoes 16,1 are extended as the wheels 26 rotate.
8 to the outer circumferential side to adjust the shoe gap, respectively, and are engaged with both ends of a connecting member 28 according to the biasing force of a spring (not shown).

Shoe web 12 of one brake shoe 16
A parking brake lever 32 having one end connected to a parking cable 30 is rotatably attached to the other end by a pin 34 near the end on the bucking plate 10 side and the anchor pin 24 side. A strut 36 spans between the intermediate portion of the parking brake lever 32 and the shoe web 14 of the brake shoe 18. When the parking cable 30 is pulled in and the parking brake lever 32 is rotated counterclockwise in FIG.
6 and 18 to perform braking, but such parking brake operation is well known and not necessarily necessary for understanding the present invention, so a detailed explanation thereof will be omitted. . In addition, 38 and 40 are both brake shoes 1
The brake shoes 1
This is a return spring that reduces the diameter of 6 and 18.

Next, the above-mentioned shew hold down devices 20, 22
will be explained in detail. Note that since each of the hold-down devices 20 and 22 is configured in the same way, the following explanation will be given only for one of the hold-down devices 20.

As shown in FIGS. 1 and 3, the show hold down device 20 includes a semicircular and plate-shaped head 4.
2 and a shaft portion 44 whose intermediate portion is bent in a direction away from the axis.
The whole has a disk shape and an annular groove 48.
It consists of a cup 50 and a coil spring 52. The shoe hold down pin 46 is swingably attached to a through hole 54 formed in the bucking plate 10 at the end opposite to the head 42, and is prevented from coming off. An intermediate portion of the hold-down pin 46 is inserted into a notch 56 formed in the longitudinal center of the shew web 12 so as to open toward the inner circumference. The cup 50 is attached to the head 42 side of the show hold down pin 46 in a state where it is prevented from coming off, and the coil spring 52 is placed between the annular groove 48 of the cup 50 and the show web 12. It is installed with a preload of .

As shown in FIGS. 1 and 2, on the surface of the shew web 12 opposite to the backing plate 10, a substantially C-shaped projection is formed so as to surround the portion of the notch 56 located on the outer peripheral side of the shew web 12. 58 is provided protrudingly. This protrusion 58 constitutes the protrusion of this embodiment, has an outer diameter slightly smaller than the inner diameter of the coil spring 52, and is formed integrally with the shew web 12 by, for example, coining. . By inserting the protrusion 58 into one end of the coil spring 52, relative movement of the coil spring 52 and the cup 50 in the inner circumferential direction of the shew web 12 is almost prevented.

As described above, according to this embodiment, the protrusion 58 protruding from the shew web 12 and the coil spring 5
2, the relative movement of the coil spring 52 and the cup 50 in the inner circumferential direction of the shoe web 12 is almost prevented, even if the brake shoes 16, 18 In a state where a rotating drum is not arranged on the outer circumferential side of the brake shoe 1 (the state shown in Fig. 3), the brake shoe 1
Even if 6 and 18 are pushed out relatively far to the outer circumferential side, the cup 50 and the coil spring 52
is prevented from falling off the shew web 12. Moreover, since it is only necessary to use one cup 50 of one type, the number of parts and assembly work are reduced compared to the conventional method, and there is no need to form an engaging pawl on the cup as in the conventional case. Brakes are provided at a lower cost overall.

Furthermore, according to this embodiment, it is possible to perform the coining process of the protrusion 58 at the same time as the punching process using a press such as a hole for attaching the parking brake lever 32 in the shew webs 12, 14. Drum brakes are provided at a lower cost.

In addition, in the above-mentioned embodiment, the protrusion is constituted by a substantially C-shaped protrusion 58;
is inserted into one end of the coil spring 52, but it is not necessary; for example, the fourth
As shown in the figure, a protrusion 60 may be integrally provided near the bottom of the notch 56 of the shew web 12, and the protrusion 60 may be engaged with the inner circumferential surface of one end of the coil spring 52. As shown in the figure, a pair of protrusions 62 may be provided integrally or integrally on both edges of the open side of the notch 56 of the show web 12, and the protrusions 62 may be engaged with the outer peripheral surface of the coil spring 52.

Further, the protruding portion is provided at a predetermined position on the outer circumferential side of the shoot web 12 than the notch 56, and a hook portion extending from one end of the wire constituting the coil spring in the outer circumferential direction of the coil spring is provided, and this hook portion is attached to the protruding portion. You can also hook it up.

Furthermore, the protruding portion may be a pin, bolt, or the like protruding from the shew web 12.

Furthermore, in the above-mentioned embodiments, the present invention was applied to a dual-servo type drum brake equipped with only a parking brake mechanism, but this is not necessarily necessary. The effects of the present invention can be obtained if the drum brake is equipped with a brake shoe in which a shoe-hold down device is attached with a shoe-hold down pin inserted into the notch. It is.

In addition, various changes may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view of main parts of a cross section taken along the line - in FIG. 3. FIG. 2 is a view of the show web shown in FIG. 1 viewed from the coil spring side. FIG. 3 is a front view showing an example of a drum brake equipped with a brake shoe to which the present invention is applied. Figures 4 and 5
The figures are diagrams showing other examples of the present invention, respectively,
This is a diagram corresponding to FIG. 2. 10: Bucking plate, 12, 14: Show web, 16, 18: Brake show, 20,
22: Shuhold down device, 46: Shuhold down pin, 52: Coil spring, 5
6: Notch, 58, 60, 62: Protrusion.

Claims (1)

[Scope of Claim for Utility Model Registration] A pair of brake shoes each having an arc-shaped shoe web with a notch opening toward the inner circumference in the longitudinally intermediate portion; A predetermined preload is applied between a shew-hold down pin that is movably attached and whose intermediate portion is inserted into the notch of the shew web, and the other end of the shew-hold down pin and the shew web. and a coil spring interposed in a state in which the shoe hold down pin is inserted, the shoe hold down supporting the brake shoes on the bucking plate in a state where they can be mutually expanded. The brake system for a drum brake is characterized in that the show web is provided with a protrusion that engages with one end of the coil spring in a manner immovable relative to the show web in an inner circumferential direction. You.