JPH094659A - Drum brake - Google Patents

Abstract

PURPOSE: To mount simply and economically a wheel cylinder to a backing plate. CONSTITUTION: A backing plate 10 is provided with a locating lug 46 by thrust working. The locating lug 46 is inserted in a locating hole 44 formed in a wheel cylinder 28 to locate the wheel cylinder 28, while a single bolt 36 is screwed into a tapped hole 42 in the wheel cylinder 28 through a through hole 48, so that the wheel cylinder 28 is fixedly provided on the backing plate 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake,
In particular, the present invention relates to a structure for mounting a wheel cylinder on a backing plate.

[0002]

2. Description of the Related Art Wheel cylinders for drum brakes
Usually, the backing plate is positioned and fixed at a predetermined position, and generally, as shown in FIG. 4, the mounting surface 62 of the wheel cylinder 60 is subjected to cutting work or the like. By the positioning projection 6
4 and a pair of screw holes 66 are formed, a backing plate 68 is provided with a through hole 70 for positioning, and the projection 64 is provided in the through hole 70.
Is inserted to position the wheel cylinder 60, and a pair of bolts 72 are screwed into the screw holes 66 so as to be integrally fixed.

[0003]

However, in such a conventional mounting structure, since the positioning projections are formed on the mounting surface by cutting, the material cost and the processing cost are increased, and the pair of bolts are used. Since the wheel cylinder is fixed by using it, there is a problem that the number of parts is large and assembly is troublesome.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to easily and inexpensively attach a wheel cylinder to a backing plate.

[0005]

To achieve the above object, the present invention provides a drum brake including a backing plate and a wheel cylinder which is positioned and fixed at a predetermined position of the backing plate. )
The wheel cylinder is provided with a single screw hole and at least one positioning hole for attachment to the backing plate, while (b) the backing plate is inserted into the positioning hole to insert the wheel. A positioning protrusion for positioning the cylinder is provided by an extrusion process, and a through hole for inserting a bolt is formed at a position corresponding to the screw hole.

[0006]

In such a drum brake, the backing plate is provided with the positioning projection by the protrusion processing, and the positioning projection is inserted into the positioning hole provided in the wheel cylinder to position the wheel cylinder. Therefore, the material cost and the processing cost can be reduced as compared with the conventional case where the wheel cylinder is subjected to the cutting process to form the positioning projection. Also, the wheel cylinder can be fixed to the backing plate by simply screwing one bolt into the screw hole of the wheel cylinder through the through hole provided in the backing plate. Therefore, when fixing with a pair of bolts as in the conventional case Compared with, the number of parts is reduced and the assembling is easy, and the manufacturing cost can be significantly reduced in combination with the reduction in the material cost and the processing cost.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In FIG. 1, the backing plate 10
A pair of arcuate brake shoes 12 and 14 are arranged in the so as to be able to open. These brake shoes 1
Reference numerals 2 and 14 each include a shoe web 20 that is substantially parallel to the backing plate 10, a shoe rim 22 that is fixed to the outer circumferential end surface of the shoe web 20, and a lining 24 that is fixed to the outer circumferential surface of the shoe rim 22. The shoe hold down spring 16,
It is pressed against the backing plate 10 by 18. The opposite ends of the shoe webs 20 of the brake shoes 12 and 14 are in contact with the anchors 26 fixed on the backing plate 10, while the opposite shoe webs 20 of the brake shoes 12 and 14 are opposite to each other. The other end is engaged with both ends of a wheel cylinder 28 fixedly mounted on the backing plate 10. The wheel cylinder 28 spreads both brake shoes 12, 14 in the left-right direction in the drawing, When pressed by a brake drum (not shown), the brake drum and the rotation of the wheels are braked. Also, one brake shoe 1
The parking brake lever 3 is attached to the shoe web 20 of 2.
0 is rotatably connected to the brake cable 31.
Is tightened and its parking brake lever 30 is rotated counterclockwise in the figure, both brake shoes 12, 14 are similarly expanded in the left-right direction in the figure via strut 32, and are pressed by the brake drum. Generates braking force. In addition, 34 is a shoe return spring,
This is for returning both brake shoes 12, 14 to the inner peripheral side to release the braking state.

The wheel cylinder 28 is fixed to the backing plate 10 with a single bolt 36 as shown in FIG. The cylinder body 38 of the wheel cylinder 28 is formed with a flat mounting surface 40 as is apparent from FIG. 3, and the mounting surface 40 is provided with one screw hole 42 and one positioning hole 44. . The positioning hole 44 has a circular cross section, and its diameter and depth are the same as the inner diameter and the depth of the screw hole 42, that is, the same as a prepared hole for processing the screw hole 42, and they are machined at the same time when the prepared hole is machined. . In other words, one of the pair of screw holes 66 shown in FIG.
This is used as a positioning hole.

On the other hand, the backing plate 10 is provided with a bottomed cylindrical positioning protrusion 46 which is inserted into the positioning hole 44 to position the wheel cylinder 28 by an extrusion process and the screw hole 42.
A through hole 48 for inserting a bolt is formed at a position corresponding to. These positioning protrusions 46 and through holes 48
Can be processed simultaneously by pressing. Then, the positioning protrusion 46 is inserted into the positioning hole 44 and the wheel cylinder 28 is aligned so that the screw hole 42 is aligned with the through hole 48, and the bolt 36 is inserted from the through hole 48 into the screw hole 42. By screwing in, the wheel cylinder 28 is positioned at a predetermined position on the backing plate 10 and is integrally fixed. The outer diameter of the positioning protrusion 46 is the positioning hole 44.
Is slightly larger than the inner diameter of the wheel cylinder 28 so that it is press-fitted into the positioning hole 44.
It prevents misalignment and rattling.

In this embodiment, the positioning protrusion 46 is 1
Since it is an individual piece, its positioning protrusion 46 has a positioning hole 44.
When inserted therein, only the positioning hole 44 of the wheel cylinder 28 is positioned, and the bolt 36 is screwed into the threaded hole 42 through the through hole 48 to completely position the wheel cylinder 28. 2 and 3, the outlet holes and inlet holes other than those for mounting are omitted.

In such a drum brake of this embodiment, a positioning protrusion 46 is provided on the backing plate 10 by an extrusion process, and the positioning protrusion 46 is provided.
Since the wheel cylinder 28 is positioned by being inserted into the positioning hole 44 of the wheel cylinder 28, when the positioning protrusion 64 is formed by cutting like the wheel cylinder 60 of FIG. Material costs and processing costs can be reduced in comparison. In addition, through the through holes 48 provided in the backing plate 10,
The wheel cylinder 28 can be fixed to the backing plate 10 only by screwing the individual bolts 36 into the screw holes 42 of the wheel cylinder 28. Therefore, as compared with the case of fixing the pair of bolts 72 as shown in FIG. The number of parts is reduced and the assembling is easy, and the manufacturing cost can be significantly reduced in combination with the reduction of the material cost and the processing cost. Particularly, in this embodiment, the positioning hole 44 is the screw hole 4
Since it is the same as the pilot hole of No. 2 and can be machined at the same time as the pilot hole, its manufacturing becomes easier.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, although the positioning hole 44 and the positioning projection 46 are provided one by one in the above-mentioned embodiment, it is relatively easy to process them, and a plurality of them may be provided.

The positioning hole 44 and the screw hole 4 are also provided.
Although 2 is provided along the axis of the wheel cylinder 28, the positional relationship thereof can be changed as appropriate in consideration of mounting strength and the like. For example, the screw hole 42 can be provided in the central portion of the mounting surface 40. is there. The positioning protrusion 46 and the through hole 48 are provided corresponding to the positional relationship between the positioning hole 44 and the screw hole 42.

Further, the positioning hole 44 in the above embodiment
Was the same as the prepared hole of the screw hole 42, but its size and shape can be changed as appropriate. The positioning protrusion 46 can also have an irregular cross section such as an elliptical cross section or a rectangular cross section, and the mounting posture of the wheel cylinder can be defined by being inserted into the positioning hole.

Further, although the drum brake of the above-mentioned embodiment is of the leading trailing type, the present invention can be similarly applied to the mounting structure of the wheel cylinder in another type of drum brake.

Although not otherwise exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part of a drum brake according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a mounting structure of a wheel cylinder in the drum brake of FIG.

FIG. 3 is a perspective view showing a wheel cylinder of the drum brake shown in FIG. 1 alone.

FIG. 4 is a sectional view showing an example of a wheel cylinder mounting structure in a conventional drum brake.

[Explanation of symbols]

 10: Backing plate 28: Wheel cylinder 42: Screw hole 44: Positioning hole 46: Positioning protrusion 48: Through hole

Claims (1)

[Claims] 1. A drum brake comprising a backing plate and a wheel cylinder positioned and fixed at a predetermined position of the backing plate, wherein the wheel cylinder has a single screw hole for attachment to the backing plate. While at least one positioning hole is provided, the backing plate is provided with a positioning protrusion that is inserted into the positioning hole and positions the wheel cylinder by protrusion processing, and corresponds to the screw hole. A drum brake characterized in that a through hole for inserting a bolt is formed at a position to be inserted.