JPS626344Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a wheel cylinder, an anchor, a brake shoe that is extendedly operated by the wheel cylinder using the anchor as a fulcrum, and an automatic brake shoe that compensates for the wear of the lining of the brake shoe. The present invention relates to a drum brake device equipped with an automatic adjustment device that performs expansion adjustment.

In this type of brake system, over a long period of time, a step is formed on the inner peripheral surface of the brake drum due to sliding friction with the brake shoe, and the brake shoe automatically adjusts to compensate for the wear of its lining. Expanded by the device. Therefore, when the brake drum is removed in the axial direction to replace the brake shoe, for example, the stepped portion formed on the inner circumferential surface of the brake shoe and the brake shoe may interfere with each other and obstruct removal of the brake drum. There is a problem that makes the separation work difficult.

Therefore, the applicant first interposed a retainer at the contact part between the anchor and the brake shoe, and by removing this from the outside, the brake shoe could be easily retracted from the normal non-operating position, and the brake drum could be removed. We have provided a drum brake device that is easy to use.

The feature of the present invention is that, in such a drum brake device, a pair of engaging protrusions are vertically offset on the side wall of the anchor on the brake shoe side with a width corresponding to the thickness of the brake shoe. and protrude,
The retainer is engaged with the upper engagement protrusion of the engagement part formed at the contact part with the brake shoe, and the lower end is brought into contact with the lower engagement protrusion, and further abuts with the contact part of the retainer. The brake shoe is characterized in that a contacting brake shoe is positioned between the two engaging protrusions, and movement of the brake shoe in the vertical direction is restricted.

The purpose of this invention is to prevent the brake shoe from digging into the brake drum due to wear on the inner peripheral surface of the brake drum, making it difficult to easily remove the brake drum.
The retainer interposed at the contact portion between the anchor and the brake shoe can be easily removed from the drum side, improving work efficiency, and the retainer moves as the brake shoe moves during braking, and the brake shoe also floats. To provide a drum brake which prevents damage and also allows easy positioning of a retainer during assembly.

An embodiment in which the present invention is applied to a two-leading drum brake will be described below with reference to the drawings.

On the inner surface of the back plate 1 fixed to the vehicle body, a pair of upper and lower wheel cylinders 2 (the lower part is not shown) and a pair of left and right brake shoes 3 are arranged symmetrically around the center of the back plate 1. will be established.

The wheel cylinder 2 is composed of a cylinder body 4 having a cylinder hole with only one end open, and a piston 5 that is joined to the cylinder hole to define a hydraulic chamber. fixed to the plate.

The one brake shoe 3 is fitted into the head of the piston 5, and the other brake shoe 3 is in contact with the anchor portion 8 of the cylinder body 4 via the retainer 7.

The retainer 7 is removably fixed to the anchor portion 8 by a tightening bolt 9 serving as a tightening means.

On the side wall of the anchor part 8 on the brake shoe 3 side,
The upper engaging protrusion 10 and the lower engaging protrusion 11 have a width l corresponding to the thickness of the brake shoe 3, and are provided in an offset manner. In this embodiment, the upper engagement protrusion 10 is located on the upper right side, and the lower engagement protrusion 11 is located on the left side. The height of both the engaging protrusions 10 and 11 is set larger than the thickness of the retainer 7. Further, in this embodiment, both the engaging protrusions 10 and 11 are integrally cast to form the cylinder body 4, but the present invention is not limited to this, and they may be formed of pins, bolts, or the like.

The retainer 7 has its contact portion 7a connected to the anchor portion 8.
and the corresponding brake shoe 3, and an engaging portion 7b formed by cutting out the upper right side of the contact portion 7a engages with the engaging protrusion 10.
On the other hand, the left lower end 7c of the contact portion 7a has an engaging protrusion 11.
is in contact with. The thickness of the contact portion 7a is set to be larger than the maximum allowable depth of a step formed on the inner circumferential surface of the brake drum due to wear.

A mounting portion 7c, which is bent and formed to overlap the upper surface of the anchor portion 8, is integrally formed with the contact portion 7a. This mounting portion 7d has a mounting hole 1.
2 is provided, and the tightening bolt 9 is passed through the mounting hole 12 and fixed to the anchor portion 8. The removal hook part 7e is formed integrally with the abutting part 7a at a position offset by a predetermined amount l from the engaging part 7b.

Next, the operation of this embodiment will be explained.

In order to perform braking, when a brake master cylinder (not shown) is operated and its output hydraulic pressure is supplied to the upper and lower wheel cylinders, this hydraulic pressure causes the pistons 5 to move outward and apply pressure to the corresponding brake shoes 3, 3. It is possible to expand and press against the inner circumferential surface of a brake drum (not shown) to apply braking force to the brake drum and therefore to the wheels.

When the brake lining wears out, a well-known braking gap automatic adjustment device built into the wheel cylinder 2 regulates the retraction of the piston 5 according to the amount of wear, and automatically adjusts the brake shoes 3, 3 to compensate for the wear of the brake linings. action takes place.

During this braking, a force is applied to the brake shoe 3 in the direction of arrow A in FIG. Regulated. Further, lifting of the brake shoe 3 during braking is restricted by engagement protrusions 10 and 11 formed to protrude from the abutting portion 7a of the retainer 7. In this way, the retainer 7 does not move and the brake shoe 3 does not rise, so the braking gap does not become unstable and good braking is ensured.

Next, when removing the brake drum in order to replace the brake shoes 3, 3 with new parts, etc., rotate the brake drum so that the work window provided on the brake drum is in a position facing the retainer 7. ,
A suitable tool is inserted through the work window to loosen the tightening bolt 9, and then the retainer 7 is pulled out from between the anchor part 8 and the brake shoe 3 by hooking the tool on the removal hook part 7e. Then, the retainer 7 is rotated clockwise by the upper right engaging protrusion 10 and the lower left engaging protrusion 11 using the engaging protrusion 10 as a fulcrum, and is easily detached.

Each brake shoe 3, 3 is connected to a retainer 7.
Since the brake drum contracts by an amount equivalent to the thickness of the brake drum, a sufficient gap is secured between these and the brake drum to facilitate the axial removal of the brake drum.

Therefore, for example, a step is formed on the inner circumferential surface of the brake drum by the sliding of the brake lining, and interference between this and the brake shoe is reliably eliminated, making the detachment operation easier.

The pulled out retainer 7 is attached to the brake shoes 3, 3.
When it is removed, it is fixed again to the anchor part 8, but
At that time, the engaging portion 7b of the retainer 7 is
The lower end 7c is positioned by abutting the engagement protrusion 10 and the engagement protrusion 11, and the attachment can be performed easily and reliably.

Next, another embodiment shown in FIGS. 4 and 5 will be described. In this embodiment, the contact portion 7 of the retainer 7
An attaching portion 7d is integrally formed on the side opposite to the engaging portion 7b of A by being bent so as to overlap from the side to the upper part of the anchor portion 8. As a result, the detachable hook portion 7e is formed at the bent portion of the attachment portion 7d, making it unnecessary to form a special detachable hook portion.

Although both of the above embodiments have been described as being applied to a two-leading type drum brake, the present invention is not limited thereto, and can be similarly applied to all drum brakes having anchors, such as leading and trailing types. Although the engaging protrusions are provided at the upper right and lower left, it is of course possible to reverse these and provide the engaging protrusions at the upper left and lower right, and to interpose the retainers in the opposite directions accordingly. .

As described above, according to the present invention, when the retainer interposed between the anchor and the brake shoe is pulled out using the external hook part, a rotational force is generated in the retainer using the upper engagement protrusion as a fulcrum. The engaging protrusion and the lower engaging protrusion smoothly generate rotational force and are easily disengaged. Therefore, by simply pulling out the retainer, the brake shoe can be retracted from its normal non-operating position and the gap between the brake shoe and the brake drum can be increased, thereby creating a step due to wear on the inner circumferential surface of the brake drum. Even if the stepped portion is formed, the brake drum can be easily removed in the axial direction without interfering with the stepped portion and the brake shoe.

Note that the retainer is securely positioned on the anchor by a pair of engaging protrusions and does not move even when the brake shoe is used for braking, and both engaging protrusions are securely positioned on the anchor due to the braking action of the brake shoe. Since rattling and lifting are controlled, good braking can be obtained without making the braking gap unstable.

[Brief explanation of the drawing]

1 and 3 show an embodiment of the present invention,
Fig. 1 is a plan view of the main part of the drum brake, Fig. 2 is a cross-sectional view taken from Fig. 1, Fig. 3 is a perspective view of the retainer, and Figs. 4 and 5 show other embodiments of the present invention. , FIG. 4 is a sectional view at the same position as FIG. 2, and FIG. 5 is a perspective view of the retainer. 1 is the back plate, 2 is the wheel cylinder,
3 is a brake shoe, 7 is a retainer, 7a is a contact portion, 7b is an engaging portion, 7c is a lower end portion, 7d is a mounting portion, 7e is a removal hook portion, 8 is an anchor portion, 9
1 is a tightening bolt, and 10 and 11 are engaging protrusions.

Claims (1)

[Scope of utility model registration request] A wheel cylinder, an anchor, a brake shoe that is expanded and operated by the wheel cylinder using this anchor as a fulcrum, and this brake shoe,
In the drum brake device, the drum brake device includes an automatic adjustment device that automatically expands and adjusts the lining to compensate for wear, and a retainer that is removable from the outside is interposed at a contact portion between the anchor and the brake shoe. A pair of engagement protrusions are provided on the side wall of the anchor on the brake shoe side, with a width corresponding to the thickness of the brake shoe, and are offset in the vertical direction, so that the engagement protrusions come into contact with the brake shoe of the retainer. The engaging portion formed on the contact portion is engaged with the upper engaging protrusion, the lower end portion is brought into contact with the lower engaging protrusion, and the brake shoe, which is in contact with the abutting portion of the retainer, is brought into contact with the above-mentioned both engaging projections. A drum brake device characterized by being positioned between mating protrusions and regulating vertical movement of a brake shoe.