JPH08296673A - Dust cover fitting structure in drum brake - Google Patents

Abstract

PURPOSE: To effectively prevent water or the like from entering a brake by providing a projection which is projected upwardly of an inner circumferential part of the cover, and extended along the inner circumferential part. CONSTITUTION: An outer circumferential part 15a of a lower dust cover 15 fitted to an anchor bracket 10 covers the vicinity of an inner end part in the direction of an axle of a brake drum 25. A projection 18 projected inwardly in the direction of an axle is formed so as to cover the upper part of an inner circumferential part 15a of the lower dust cover 15, i.e., like eaves. The projection 18 is extended along the inner circumferential part 15b of the lower dust cover 15 at the lower part of the anchor bracket 10. Because the projection 18 is present, water or the like flowing downward passing along the inner surface 10c of the anchor bracket 10 is transmitted along the upper surface, and dropped at the position more inwardly away in the axle direction than an abutted part of the anchor bracket 10 and the lower dust cover 15. Thus, water or the like flowing from the upper part to the abutted part can be prevented from entering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust cover which is attached to an anchor bracket in a drum brake from the inner side in the axial direction and which prevents dust, water and the like from entering a space in which brake shoes are surrounded by a brake drum. Regarding mounting structure.

[0002]

2. Description of the Related Art A drum brake is composed of an anchor bracket which is fixed to a vehicle body (that is, an axle housing) and holds a brake shoe unit, and a brake drum which is arranged so as to cover the brake shoe unit from the outside in the axial direction. Composed. This drum brake is usually arranged inside the wheel rim, and the brake drum is connected to the wheel rim (or the wheel hub to which it is attached) and is rotatable with respect to the anchor bracket.

As described above, the outer side of the drum brake is covered with the wheel rim and the brake drum, but if it is left as it is, there is a problem that dust, water and the like enter the inside of the brake from the inner side in the axle direction. An annular dust cover that covers an internal space surrounded by the brake drum (a space where the brake shoe unit is arranged) is attached (see, for example, Japanese Utility Model Laid-Open No. 7-8130).

The inner peripheral portion of the dust cover is formed in a flat plate shape, and the outer surface in the axial direction of the inner peripheral portion is brought into contact with the inner surface in the axial direction of the anchor bracket (cover mounting surface) and bolted. Thus, the dust cover is fixed to the anchor bracket. FIG. 9 shows how such a dust cover is attached to the anchor bracket.
Is. In the same figure (A), the inner peripheral portion of the dust cover 95 is brought into contact with the planar cover mounting surface 90 c of the anchor bracket 90. Further, in FIG. 2B, a portion 90d 'that projects inward in the axle direction is provided on the cover mounting surface 90c' of the anchor bracket 90 '.
The inner peripheral portion of the dust cover 95 is brought into contact with d '.

[0005]

However, the cover mounting surface of the anchor bracket remains the casting surface,
In many cases, only rough processing is performed, and a gap is likely to occur at the contact portion between the cover mounting surface and the dust cover inner peripheral portion. Furthermore, the inner circumference of the dust cover is flat,
This portion is likely to be warped or deformed, and in such a case, the gap between the anchor bracket and the anchor bracket is likely to be large.

The area around the inner surface of the anchor bracket is a portion where water, etc., which is wound up by the rotation of the tire while the vehicle is running, is likely to come into direct contact with the inner surface of the anchor bracket in the axial direction (hereinafter, simply referred to as the inner surface). Water that hits) flows down this inner surface. Therefore, if there is a gap between the contact portion between the anchor bracket and the dust cover as described above, water or the like may enter the inside of the brake drum through this gap, and rust may easily occur inside. There is a problem that water may adhere to the lining surface to cause a water fade phenomenon.

The present invention has been made in view of these problems.
An object of the present invention is to provide a dust cover mounting structure capable of effectively preventing intrusion of water and the like into the inside of a brake even if a gap is created at the contact portion between the anchor bracket and the dust cover.

[0008]

In order to achieve the above object, according to the present invention, an anchor bracket that is fixed to a vehicle body and holds a brake shoe unit, and an anchor bracket that covers the brake shoe unit from the outside in the axial direction is used. An anchor in a drum brake including a brake drum rotatably disposed with respect to the brake drum, and an annular dust cover attached to an anchor bracket to cover an inner space surrounded by the brake drum from the inner side in the axial direction. The attachment surface of the dust cover in the lower part of the bracket is provided with a protrusion that projects above the inner peripheral portion of the dust cover and extends along the inner peripheral portion.

[0009]

In such a dust cover mounting structure, the projections serve as eaves protruding above the inner peripheral portion of the dust cover. Therefore, the water that hits the inner side surface of the anchor bracket and flows downward on the inner side surface flows along the upper surface of the protrusion and falls below the contact portion between the anchor bracket and the dust cover inward in the axle direction. Therefore, it is possible to prevent water from splashing on the contact portion as much as possible, and it is possible to efficiently prevent water from entering the inside of the brake.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. First, an example of a drum brake adopting the dust cover mounting structure according to the present invention is shown in FIGS. This drum brake is fixed to an axle housing (vehicle body) 1 and is attached to an outer surface in the axial direction (see FIG. 1).
Then, the anchor bracket 10 that holds the brake shoe unit 20 on the left side surface and the brake bracket 20 that covers the brake shoe unit 20 from the outer side in the axle direction (the left side in FIG. 1) are rotatably arranged with respect to the anchor bracket 10. Brake drum 25 and an internal space surrounded by the brake drum 25, that is, the brake shoe unit 2
The dust cover 15 is attached to the anchor bracket 10 so as to cover the space in which 0 is arranged from the inner side in the axial direction (right side in FIG. 1).

An axle shaft (axle) 2 projects outward from the axle housing 1 and a pair of taper roller bearings 3a, 3 are mounted on the axle shaft 2.
The wheel hub 4 is rotatably attached via b. A wheel rim 5 is attached to the wheel hub 4, and a tire (not shown) is attached to the wheel rim 5. Further, the brake drum 25 is connected to the wheel hub 4, and as a result, the brake drum 25 is rotatable integrally with the wheel.

As can be seen from FIG. 3 (B), the anchor bracket 10 has an intermediate portion having a shaft hole 10a for allowing the axle housing 1 to pass therethrough, and extends to the lower side of this portion, as shown in FIG. 3 (A). ), It is composed of a bifurcated support arm portion 11 formed inside and outside in the axle direction, and an upper portion formed with a hole 10b for sending pressure oil to an expansion piston device 23 described later. The both arm portions 11 are formed with pin insertion holes 11a so that their positions overlap with each other in the axle direction. Further, as can be seen from FIG. 1A, a cover mounting surface 12 is formed on the outer periphery of the upper portion and the intermediate portion so as to extend further toward the inner side in the axial direction than the portion other than the outer periphery.

As shown in FIGS. 1 and 2, the brake shoe unit 20 has its proximal end pivoted by an anchor pin 21 inserted into a pin insertion hole 11a of the support arms 11 and 11 and swings left and right. It has a pair of left and right brake shoes 22, 22 freely attached. A tension spring 24 is disposed between the tip ends of the brake shoes 22, and normally (when the brake is not operated), the brake shoes 22 receive the biasing force of the tension springs 24 and swing inward. It's in the right position.

Between the tips of the brake shoes 22,
An expansion piston device 23 is also arranged. The expansion piston device 23 expands by receiving hydraulic pressure, and swings the brake shoes 22 and 22 about the support portion of the anchor pin 21 in the direction away from each other, that is, in the outer peripheral side. The hydraulic pressure to the expansion piston device 23 is supplied when the brake is operated, and when the brake is operated, the expansion piston device 23 swings the brake shoe 22 in the expansion direction against the tension spring 24.

A brake drum 25 is arranged so as to surround the brake shoe 22, and thus the brake shoe 2 is provided.
When 2 is swung in the expansion direction, the brake lining on the outer periphery of the brake shoe 22 is pressed against the inner surface of the brake drum 25, and the frictional force between the two brakes the rotation of the brake drum 25. As a result, the wheel to which the brake drum 25 is attached is braked.

The drum brake configured as described above is disposed inside the wheel rim 5, and is covered from the outside by the wheel rim 5 and the wheel hub 4.
Therefore, dust, water, etc. do not directly enter the inside of the drum brake from the outside of the vehicle body. Particularly, since the brake shoe unit 20 is covered from the outside by the brake drum 25, in which dust, water, and the like tend to be a problem, intrusion of dust, water, and the like into the brake shoe unit 20 from the vehicle body becomes a problem. There is no such thing.

On the other hand, there is an anchor bracket 10 for holding the brake shoe unit 20 on the inner side in the axial direction of the brake shoe unit 20, but this alone tends to cause a problem of intrusion of dust, water and the like from the inside. For this reason, the brake shoe unit 2 is surrounded by the brake drum 25 from the outside.
An annular dust cover (comprising a lower dust cover 15 and an upper dust cover 16) is attached to the anchor bracket 10 so as to cover the space in which 0 is arranged from the inner side in the axle direction.

The lower dust cover 15 is made of a semi-annular plate as shown in FIG. 4 (B). As shown in FIG. 4 (A), the outer peripheral portion 15a is narrowed in a U-shape with respect to the inner peripheral portion 15b. It is formed like a flange. Furthermore, the inner peripheral portion 15
Mounting bolt holes 15d for attaching to the anchor bracket 10 are formed at a plurality of positions of b. On the other hand, as shown in FIG. 5, the upper dust cover 16 is also made of a semi-annular plate, and the outer peripheral portion 16a is formed in a U-shaped flange shape narrowed with respect to the inner peripheral portion 16b.

As shown in FIGS. 1 and 5, the dust covers 15 and 16 are bolted by contacting the outer surfaces of the inner peripheral portions 15b and 16b in the axial direction with the cover mounting surface 12 above and below the anchor bracket 10. It is fixed by 13. At this time, both ends 16e in the circumferential direction of the upper dust cover 16 are overlapped on both ends in the circumferential direction of the lower dust cover 15, and these are collectively put together by the bolt 13 to the anchor bracket 10.
Fixed to. Therefore, even if water or the like hits the upper dust cover 16 and flows downward, the water or the like does not flow into both circumferential ends 16e of the lower dust cover 15 and water is prevented from entering the inside of the brake from here. .

As can be seen from FIG. 1, the outer peripheral portions 15a and 16a of the upper and lower dust covers 15 and 16 attached to the anchor bracket 10 cover the periphery of the inner end portion of the brake drum 25 in the axial direction as shown in FIG. As a result, dust, water, and the like can be removed from the brake shoe unit 2 through the gap between the anchor bracket 10 and the brake drum 25.
It is possible to effectively prevent the invasion into the 0 installation space.

By the way, the anchor bracket 10 is formed by casting into a shape as shown in FIG. 3, and the cover mounting surface 1 to which the dust covers 15 and 16 are mounted.
No. 2 has a casting surface as it is, or is only rough processed. For this reason, a gap is likely to be formed at the contact portion between the cover mounting surface 12 and the inner peripheral portions 15b and 16b of the dust covers 15 and 16. Further, for example, as shown in FIG. 7, when the inner peripheral portion 15b of the lower dust cover 15 originally formed in a flat plate shape is warped or deformed, a gap is generated between the cover mounting surface 12 and the contact portion of the dust cover 15. S may occur. And thus, the lower dust cover 1
If there is a gap between the abutting portions of the cover mounting surface 12 and the cover mounting surface 12, water or the like flowing down along the axle inner surface (hereinafter referred to simply as the inner surface) 10c of the anchor bracket 10 will pass through this gap. It may get inside the brakes.

In view of the above, in this example,
As shown in detail in FIG. 6, a protrusion 18 is formed so as to cover the upper portion of the inner peripheral portion 15a of the lower dust cover 15, that is, in the shape of an eave, and protrudes inward in the axle direction. As shown in FIG. 5, the protrusion 18 extends along the inner peripheral portion 15b of the lower dust cover 15 in the lower half of the middle portion of the anchor bracket 10. Further, the projection amount t1 of the protrusion 18 extending in the semi-annular shape from the cover mounting surface 12 is set to be somewhat larger than the thickness t2 of the inner peripheral portion 15b of the lower dust cover 15.

Due to the presence of such a protrusion 18, water or the like flowing down along the inner side surface 10c of the anchor bracket 10 is transmitted along the upper surface of the protrusion 18 and is brought into contact with the anchor bracket 10 and the lower dust cover 15. It falls downward at a position further inward in the axial direction than the part. For this reason,
It is possible to prevent water or the like flowing from above from flowing into the contact portion. Therefore, it is possible to suppress the intrusion of water or the like into the installation space of the brake shoe unit 20 and effectively prevent the internal parts from rusting or the water fade phenomenon.

Further, since the protrusion amount t1 of the protrusion 18 is somewhat larger than the thickness t2 of the lower dust cover 15, FIG.
As shown in FIG. 5, even if the inner peripheral portion 15b of the lower dust cover 15 is deformed so that a relatively large gap S is generated, the inner peripheral portion 1 of the lower dust cover 15 is
The upper part of 5b can be surely covered, and the intrusion of water or the like through the gap S can be prevented.

The dust cover mounting structure according to the present invention is not limited to that shown in the above embodiment. For example, as shown in FIG. 8A, the inner side surface 10c 'of the anchor bracket 10' may be pushed inward in the axial direction to the same position as the cover mounting surface 12 '. Also in this case, the protrusion amount t of the protrusion 18 'from the cover mounting surface 12' is t.
1 is larger than the thickness t2 of the lower dust cover 15 '.
Further, as shown in FIG.
The inner surface 10c ″ of 0 ″ may be formed integrally with the protrusion 18 ″, and these may be protruded from the cover mounting surface 12 ″ by the protrusion amount t1. In either case, the cover mounting surface 1
It is possible to prevent water or the like flowing from above from flowing into the contact portion between the 2'and 12 "and the dust cover 15.

[0026]

As described above, in the present invention, the dust cover is attached to the anchor bracket by covering the brake shoe unit installation space (internal space) surrounded by the brake drum from the inside in the axial direction. In the drum brake, a protrusion is formed above the dust cover attachment surface at the lower portion of the anchor bracket to cover the inner periphery of the dust cover. Therefore, water or the like that hits the inner side surface of the anchor bracket and flows downward on the inner side surface flows down on the upper surface of the protrusion and falls below the contact portion between the anchor bracket and the dust cover in the axial direction. Therefore, it is possible to prevent water from splashing on the contact portion as much as possible, it is possible to efficiently prevent water from entering the inside of the brake, and it is possible to prevent the occurrence of rust and the water fade phenomenon inside the brake. it can.

[Brief description of drawings]

FIG. 1 is a sectional view showing a drum brake adopting a dust cover mounting structure according to the present invention.

FIG. 2 is a front view of the drum brake.

FIG. 3 is a side sectional view and a rear view of an anchor bracket used for the drum brake.

4A and 4B are a plan view and a rear view of a dust cover used for the drum brake.

FIG. 5 is a rear view of the drum brake.

FIG. 6 is a side sectional view of a protrusion provided on the anchor bracket.

FIG. 7 is a partial plan view showing a structure for attaching a dust cover to the anchor bracket.

FIG. 8 is a side sectional view showing second and third embodiments of the mounting structure according to the present invention.

FIG. 9 is a side sectional view showing a conventional mounting structure.

[Explanation of symbols]

 5 Wheel rim 10 Anchor bracket 15, 16 Dust cover 18 Protrusion 20 Brake shoe unit 25 Brake drum

Claims (1)

[Claims] 1. An anchor bracket which is fixed to a vehicle body and holds a brake shoe unit, a brake drum which covers the brake shoe unit from the outside in the axial direction and is rotatably arranged with respect to the anchor bracket, and the brake. A drum brake having an annular dust cover attached to the anchor bracket to cover the inner space surrounded by the drum from the inner side in the axle direction, wherein the attachment surface of the dust cover in the lower part of the anchor bracket has: A dust cover mounting structure for a drum brake, characterized in that a protrusion is provided so as to cover an upper portion of an inner peripheral portion of the dust cover and extends along the inner peripheral portion.