JPH0529382Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inwardly expanding drum brake for a vehicle that performs a braking action by expanding a pair of brake shoes disposed opposite to each other on a back plate.

[Conventional technology]

Conventionally used leading and trailing or two-leading type internally expanding vehicle drum brakes connect a pair of bow-shaped brake shoes to a back plate via a shoe hold down pin and a shoe hold spring. One end of each brake shoe is brought into contact with an actuator for expansion such as a wheel cylinder, and the other end is supported by an anchor (for example, as disclosed in Japanese Utility Model Publication No. 62-21132). reference).

In the brake shoe mentioned above, when the actuator operates, one end of the actuator side expands with the other end of the anchor side as a fulcrum, and the outer lining is pressed against the inner peripheral surface of the brake drum to perform braking action. The maximum surface pressure of each brake shoe is generated near the other end on the anchor side.

[The problem that the idea attempts to solve]

However, in these systems in which a bow-shaped brake shoe with a substantially semicircular length is expanded using an actuator and an anchor, the maximum braking force is naturally limited, and for example, in order to increase the braking force, it is necessary to The only option was to use large drum brakes.

The present invention was developed against this background, and its purpose is to increase the surface pressure of the brake shoe against the brake drum to improve braking force without increasing the size of the brake shoe. An object of the present invention is to provide an inwardly expanding drum brake for a vehicle.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention has a pair of brake shoes formed in an arch shape, which are supported oppositely to a back plate via a shoe hold down pin and a shoe hold spring, and each brake shoe is In an inwardly expanding vehicle drum brake in which one end of the shoe is brought into contact with an actuator such as a wheel cylinder and the other end is supported by an anchor, each brake shoe is divided into two into an actuator side and an anchor side, Connect the split-side inner ends of both split shoes with the shoe hold down pin, and attach the first split-side inner end of the split shoe on the actuator side.
At the same time as forming an engaging part, a second engaging part is formed at the inner end of the split side of the split shoe on the anchor side, and the second engaging part
It is characterized in that the first engaging portion is engaged with the inner diameter side of the drum of the engaging portion.

[Effect]

When the actuator is operated, the split shoe on the actuator side of each brake shoe is pushed towards the split shoe on the anchor side, while the outer end portion on the actuator side opens outward. The split shoe on the anchor side receives this pressure via the first and second engagement portions and rotates outward with the outer end portion on the anchor side as a fulcrum. Both inner ends on the split side connected to the shoe hold down pins protrude towards the outer diameter side of the drum.
The brake shoe shape is bent in an L-shape, and each split shoe comes into sliding contact with the brake drum.

As a result, in the split shoe on the actuator side, surface pressure is generated by expansion using the inner end of the split side as a fulcrum, and in the split shoe on the anchor side, which expands using the outer end on the anchor side as a fulcrum, the maximum surface The pressure is increased, and the brake shoe as a whole has a large braking force.

When the brake shoe is a leading shoe, each divided brake shoe receives a leading action due to sliding contact with the brake drum, further increasing the surface pressure of each segment and exerting a larger braking force.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

The drum brake 1 is a leading and trailing type in which a pair of bow-shaped brake shoes 3 and 4 arranged opposite to each other on a back plate 2 are expanded at the same side ends by a wheel cylinder 5, and has a substantially semicircular shape. The long brake shoes 3 and 4 are divided into two long and short shoes 6, one on the wheel cylinder side and the other on the anchor side.
It is divided into 7 parts.

Each brake shoe 3, 4 has a long split shoe 6 on the wheel cylinder side, a short split shoe 7 on the anchor side, and a rim 6 fixed to the outer edge.
a, 7a have linings 6b, 7b,
Assuming that the thickness of the lining 6b is t and the thickness of the lining 7b is T, they are formed in the relationship t<T. Further, in this embodiment, the brake shoe 3 serves as a leading shoe and the brake shoe 4 serves as a trailing shoe for a brake drum (not shown) that rotates in the direction of arrow A.

The split shoes 6 and 7 have inner ends 6 on the split side.
c, 7c are elastically supported by the back plate 2 via the shoe hold down pin 8 and the U-shaped shoe hold spring 9, and the outer end 6d of the split shoe 6 on the wheel cylinder side is held against the wheel cylinder. The split shoe 7 is attached to the back plate 2 with the outer end 7d of the split shoe 7 on the anchor side supported by the anchor 10.

The inner end 7c of the split shoe 7 on the anchor side has a bifurcated shape in which the end plates 11 are overlapped with a gap, and both the split shoes 6 and 7 have a wheel cylinder between the plates at the inner end 7c. Insert the inner end 6c of the side split shoe 6, and open the through holes 7e of both inner ends 6c, 7c.
A shoe hold down pin 8 is inserted into 6e and 7e, and they are rotatably connected.

A shoe hold down pin 8 connecting the split shoes 6 and 7 is attached to the ledge surface 2a of the back plate 2.
It is inserted into a large diameter through hole 2b that opens into the through hole 2b.
The tip protruding from b to the outer surface of the back plate 2 is prevented from coming out with a shew hold spring 9.
It is installed offset by a length l on the anchor 10 side from the line L that equally divides the brake shoes 3 and 4, and is movable in the drum inner and outer radial directions together with the inner ends 6c and 7c of the divided shoes 6 and 7. will be placed in

Split shoe 6 on the opposing wheel cylinder side,
7 and the split shoe 7, 7 on the anchor side,
Return springs 12 and 13 are tensioned, and the divided shoes 6 and 7 are biased in the diameter reduction direction by the tensile force of these return springs 12 and 13.
The above-mentioned show hold down pin 8 connecting these is in contact with the inner diameter side of the drum of the through hole 2b,
The retraction limit of the inner ends 6c, 7c is regulated.

The inner end 6c of the divided shoe 6 has a first engaging portion 1.
4 is provided by implanting a pin, and a divided shoe 7 is provided.
A second engaging portion 15 is formed on the inner end portion 7c of the end plate 11 by protruding the tip of the end plate 11.
4 is disposed in constant contact with the drum inner diameter side of the second engaging portion 15.

This embodiment is constructed as described above, and when the wheel cylinder 5 is hydraulically actuated to cause the pistons 5a, 5a to project outward, the divided shoe 6 on the wheel cylinder side of each brake shoe 3, 4 is moved outward. End 6d
While opening outward, open the split shoe 7 on the anchor side.
being pushed in a direction.

The operation of the split shoe 6 is to move the shoe hold down pin 8, which is offset by a length l from the split line L toward the anchor, in the direction of the split shoe 7 on the anchor side and in the direction of the outer diameter of the drum. The first engaging portion 14 pushes the second engaging portion 15 of the divided shoe 7 on the anchor side in the direction of the outer diameter of the drum.

The split shoe 7 on the anchor side rotates outward about the outer end 7d as a fulcrum in response to the push of the split shoe 6,
The inner ends 6c, 7c of both split sides protrude toward the outer diameter side of the drum, and the brake shoes 3, 4 are bent into a dogleg shape, and the linings 6b, 7 of the split shoes 6, 7 are bent.
b are pressed against the inner circumferential surface of the brake drum.

As a result, in the split shoe 6 on the wheel cylinder side, surface pressure is generated by expanding with the inner end 6c on the split side as a fulcrum, and the outer end 7d on the anchor side
In the split shoes 7 on the anchor side that expand around the fulcrum, the maximum surface pressure is further increased, and the brake shoes 3 and 4 as a whole brake the rotation of the brake drum with a large braking force.

In the brake shoe 3 which is on the leading side with respect to the brake drum rotating in the direction of arrow A, the leading action due to sliding contact with the brake drum is applied to each of the divided brake shoes 6 and 7.
Each surface pressure is further increased, delivering greater braking power.

As described above, in this embodiment, each of the divided shoes 6 and 7 has its own braking force, and in particular, the maximum surface pressure of the divided shoe 7 on the anchor side is further increased, so it is different from a conventional brake of the same shape. In comparison, a large braking force can be obtained. Therefore, it is possible to reduce the weight of the vehicle body, reduce vehicle cost, or improve the freedom of layout and assembly around the wheels.

In the above embodiment, the through hole in the back plate is made larger in diameter for the shoe hold down pin that connects the inner ends of the split sides of both split shoes, and the shoe hold down pin is moved together with the split shoe. However, a shoe hold down pin may be installed in the back plate, and the through holes of both the divided shoes may be formed to have a large diameter, so that only the divided shoes can be moved.

The first and second engaging portions formed in the split shoe may be configured to transmit the operation of the split shoe on the actuator side to the split shoe on the anchor side to expand, for example, by uneven engagement or protrusion. Other shapes such as combinations of parts and notches may also be used.

Further, the present invention may be applied to a mechanical drum brake in addition to a hydraulic type using a wheel cylinder, and is also applicable to a two-leading type drum brake.

[Effect of idea]

The internal expansion type vehicle drum brake of the present invention has a bow-shaped brake shoe disposed facing the back plate divided into two parts, one on the actuator side and the other on the anchor side. They are connected by a U-hold down pin, and a first engaging part is formed at the inner end of the split side of the split shoe on the actuator side, and a second engagement part is formed at the inner end of the split side of the split shoe on the anchor side. However, since the first engaging part is engaged with the inner diameter side of the drum of the second engaging part, and each of the divided shoes has its own braking force, it has greater braking force than a conventional brake of the same shape. You can get power.

Furthermore, it has many excellent effects, such as reducing the weight of the vehicle body, reducing vehicle costs, and improving the freedom of layout and assembly around the wheels.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a front view of a drum brake, and Fig. 2 is a cross-sectional view taken from the side of Fig. 1. 1... Drum brake, 2... Back plate, 2b... Through hole, 3, 4... Brake shoe,
5...Wheel cylinder serving as the actuator,
6, 7...Divided shoe, 6b, 7b...Lining, 6c, 7c...Inner end of divided shoe 6, 7, 6d...Outer end of split shoe 6, 7d...
...outer end of split shoe 7, 6e, 7e...through hole,
8...Show hold down pin, 9...Show hold spring, 10...Anchor, 11...
... end plate, 14 ... first engagement part, 15 ... second engagement part, L ... line that equally divides the brake shoes 3 and 4,
l...Offset length of the hold down pin 8 from the equal dividing line L, t...Thickness of the lining 6b, T...Thickness of the lining 7b.

Claims (1)

[Scope of utility model registration request] A pair of arch-shaped brake shoes are resiliently supported against a back plate via a shoe hold down pin and a shoe hold spring, and one end of each brake shoe is placed in contact with an actuator such as a wheel cylinder. In an internally expanding vehicle drum brake in which the brake shoes are in contact with each other and the other end is supported by an anchor, each brake shoe is divided into two parts, one on the actuator side and the other on the anchor side, and the inner ends of the divided shoes are attached to the shaft. They are connected by a U-hold down pin, and a first engaging part is formed at the inner end of the split side of the split shoe on the actuator side, and a second engagement part is formed at the inner end of the split side of the split shoe on the anchor side. An inwardly expanding drum brake for a vehicle, characterized in that the first engaging portion is engaged with the drum inner diameter side of the second engaging portion.