JPH0451225Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a drum brake device, and more particularly to a drum brake device equipped with a single brake shoe.

Prior Art Generally, in a drum brake, a brake shoe provided on a bucking plate is pushed outward by a wheel cylinder or a parking brake lever, so that the brake shoe is attached to the inner circumferential surface of a rotating drum. Braking is performed by being pressed.

Problems to be solved by this invention However, such drum brakes are usually configured so that a pressing force is applied to the end of the brake shoe in the outer circumferential direction, and a single wheel cylinder is used when moving forward or backward. In order to secure a relatively large braking force in a stable manner, a pair of brake shoes would be required, which would inevitably be relatively heavy and costly.

Means for Solving the Problems The present invention was developed against the background of the above circumstances, and its main points are (a) a bucking plate, and (b) a device facing the bucking plate. and (c) a rotating drum provided to be relatively rotatable around an axis; (c) fixed to the bucking plate;
(d) a wheel cylinder in which a pair of pistons are fitted so that they can respectively protrude in a direction that separates them from each other;
a single brake shoe provided on the bucking plate so as to be able to approach and separate from the inner circumferential surface of the rotating drum on the inner circumferential side of the rotating drum, and having one end engaged with one of the pistons; e) a rotating member rotatably provided on the bucking plate with an intermediate portion as a rotation center and having one end engaged with the other of the piston; and (f) each of the brake shoe and the rotating member. The drum brake device is configured to include a connecting member that connects the other end.

Effect: With this arrangement, when the pair of pistons fitted in the wheel cylinder are pushed out in the direction away from each other, the brake shoe and one end of the rotating member are pushed out in the direction away from each other. As a result, one end of the brake shoe is pressed against the inner circumferential surface of the rotating drum, and the rotating member is rotated about its intermediate portion as a rotation center, so that the other end of the rotating member is pressed against the inner circumferential surface of the rotating drum. The other end of the brake shoe is pressed against the inner peripheral surface of the rotating drum. At this time, the braking torque generated in the brake shoe is applied directly to one end of the brake shoe, or indirectly to the piston and wheel cylinder at the other end of the brake shoe via a connecting member and a rotating member. I can accept it.

Effects of the invention As a result, regardless of the rotational direction of the rotating drum, brake operating force is input to both ends of a single brake shoe using a single wheel cylinder, and the brake operation force is input to both ends of a single brake shoe in the rotational direction of the brake shoe. Since the brake operating force is always input, a relatively large braking force can be stably ensured in both forward and backward movement, even though the brake shoe and wheel cylinder are each single. As a result, the drum brake device can be made lighter and lower in cost than conventional drum brake devices.

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

In FIG. 1, a single arc-shaped brake shoe 12 is supported on a bucking plate 10 by a shoe hold-down device 14 so as to be movable by predetermined amounts in the radial direction and the circumferential direction. Along with the punching plate 10
At a position facing the brake shoe 12 with the center in between, a longitudinal plate-shaped rotating member 16 is provided so as to be rotatable by a rotating pin 18 at its intermediate portion. This pivot pin 18 is used in conjunction with a mounting bolt used in this embodiment to attach the bucking plate 10 to a non-rotating member. A wheel cylinder 20 is further fixed on the bucking plate 10. Inside this wheel cylinder 20, a pair of pistons 22,
24 are fitted so as to be able to protrude from each other in the direction of separation from each other, and the piston 22 has a rotating member 1
One end of the brake shoe 12 is engaged with the piston 24, and one end of the brake shoe 12 is engaged with the piston 24.
2 are connected to each other via an adjustment member 30 that has an adjustment wheel 28 and performs a shoe gap adjustment function by being urged toward each other by a spring 26. .
In this embodiment, the adjusting member 30 constitutes a connecting member.

A parking brake lever 32 is rotatably attached to one end of the rotating member 16 by a pin 34.
A strut 36 is stretched between the brake shoe 12 and a portion located approximately in the middle of the pin 34 and the rotation pin 18. In addition, at a position opposite to the side where the brake shoe 12 and the like are provided on the bucking plate 10, there is a rotating drum (not shown) inside which the brake shoe 12 and the rotating member 1 are provided.
6 etc. and the bucking plate 1
It is arranged in a state where it can rotate relative to the axis around the axis. Further, 38 is a return spring that constantly urges one end side of each of the brake shoe 12 and the rotating member 16 in a direction toward each other.

During a brake operation using the wheel cylinder 20 of the drum brake device configured as described above, when both the pistons 22 and 24 are pushed out, the ends of the brake shoe 12 and the rotating member 16 are moved in a direction in which they are separated from each other. being pushed out. As a result, one end side of the brake shoe 12 is pressed against the inner peripheral surface of the rotating drum, and
As the rotating member 16 is rotated counterclockwise in the figure around the rotating pin 18, the other end of the rotating member 16 controls the other end of the brake shoe 12 via the adjusting member 30. Pressed against the inner peripheral surface. At this time, when the rotating drum is rotating in the direction A in the figure, the braking torque generated in the brake shoe 12 is directly received by the piston 24 and the wheel cylinder 20 at the other end of the brake shoe 12. When the rotating drum is rotating in the direction opposite to the direction A, the braking torque is indirectly applied to the piston 22 and the wheel cylinder 20 at one end of the brake shoe 12 via the adjusting member 30 and the rotating member 16. It will be accepted by

On the other hand, when operating the parking brake,
When a parking cable (not shown) connected to the end of the parking brake lever 32 opposite to the side where the pin 34 is provided is pulled in and the parking brake lever 32 is rotated counterclockwise in the figure, the strut 36 One end of the brake shoe 12 is pressed against the rotating drum, and the pin 34 is rotated counterclockwise in the figure using one end of the strut 36 (the left end in the figure) as a fulcrum, and the rotating member 16 is rotated. Since it can be rotated counterclockwise in the figure around the pin 18, the brake shoe 12
The other end is pressed against the rotating drum. Even in this case, the braking torque is
directly at one end of the brake shoe 12 and indirectly at the other end of the brake shoe 12 by the wheel cylinder 20 .

As described above, according to this embodiment, when operating the service brake, the brake operating force is applied to both ends of the single brake shoe 12 by the single wheel cylinder 20, regardless of the rotating direction of the rotating drum. Since the brake operating force is always input to the input side of the brake shoe 12 in the rotational direction, the brake operation force is always input to the input side of the brake shoe 12 in the rotational direction. A relatively large braking force is stably ensured. As a result, a drum brake device having a braking force similar to that of a so-called leading-trailing drum brake can be provided at a lighter weight and lower cost than conventional drum brake devices. Brake shoe 12
is usually manufactured by fixing a shew web member and a shew rim member together by welding and attaching a friction material to the outer peripheral surface of the shew rim member, and also includes a shew hold down device 14 for attaching it to the bucking plate 10. The rotating member 16 is made of a single plate and is simply attached to be rotatable around a single axis, so the cost and weight are lower than the conventional one, as described above. Therefore, it is reduced.

Further, according to this embodiment, even when the parking brake is operated, the brake operating force is input to both ends of the single brake shoe 12 regardless of the rotation direction of the rotating drum, and the brake operation force is input to both ends of the single brake shoe 12. Since the brake operating force is input to the turning side in the rotational direction, a relatively large braking force is stably ensured in both forward and backward movement, even though there is a single brake shoe.

Further, according to this embodiment, as shown in FIG. 1, since the rotation center is approximately at the center of the rotation member 16, the pressing force of the pistons 22 and 24 on both ends of the brake shoe 12 is reduced. There is an effect that can be considered to be approximately the same.

Further, according to this embodiment, the rotation pin 18 for rotatably attaching the rotation member 16 to the bucking plate 10 is a mounting bolt used for fixing the bucking plate 10 to a non-rotation member. Since they are used together, there is an advantage that the number of parts and the number of work steps can be reduced.

In addition, in the above-mentioned embodiment, the connecting member is constituted by the adjustment member 30 that is extendable and retractable in the longitudinal direction, but this is not necessarily necessary; for example, it may be a member that is not extendable and retractable in the longitudinal direction, Alternatively, it may be a pin or the like that connects the other ends of the brake shoe 12 and the rotating member 16 so as to be rotatable and loosely fitted to each other.

In the above-described embodiment, the rotation center of the rotation member 16 is moved a predetermined distance toward the other end (adjustment member 30
It is also possible to further increase the pressing force against the other end of the brake shoe 12 by the piston 22.

Further, in the above embodiment, the parking brake mechanism is not necessarily required and may be omitted, and the parking brake lever 32 may be provided on the brake shoe 12.

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 a front view showing the main parts of a drum brake device to which the present invention is applied. 10...Bucking plate, 12...Brake shoe, 16...Rotating member, 18...Rotating pin, 20...Wheel cylinder, 22, 24...
Piston, 30...adjustment member.

Claims (1)

[Claims for Utility Model Registration] A bucking plate, a rotating drum facing the bucking plate and provided to be relatively rotatable around an axis, and a pair of pistons fixed to the bucking plate and spaced apart from each other. a wheel cylinder fitted so as to be able to protrude in each direction, and a wheel cylinder provided on the inner circumferential side of the rotating drum so as to be able to approach and separate from the inner circumferential surface of the rotating drum, and one end of which is disposed on the backing plate so as to be able to approach and separate from the inner circumferential surface of the rotating drum; a single brake shoe that is engaged with one of the pistons; a rotating member that is rotatably provided on the bucking plate about an intermediate portion thereof and that has one end engaged with the other piston; A drum brake device comprising a brake shoe and a connecting member connecting each other end of a rotating member.