JP2543712Y2 - Drum brake shoe hold-down device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shoe hold-down device for a drum brake, and more particularly to an improved shoe hold-down device for holding a shoe web of a brake shoe substantially parallel to a backing plate. It is about.

2. Description of the Related Art A brake shoe which has an arc shape as a whole including (a) a backing plate and (b) a plate-shaped shoe web, and is disposed on the backing plate along the outer peripheral edge of the backing plate. Drum brakes that generate a braking force when the brake shoes are pushed out to the outer peripheral side of the backing plate have been generally used. One type of such a drum brake includes a shoe hold-down device that holds the brake shoe so that the shoe web is substantially parallel to the backing plate. The drum brake described in Japanese Utility Model Laid-Open Publication No. 58-35028 is an example of this, in which a spacer is interposed between a backing plate and a shoe web, and a holding pin is disposed so as to penetrate them. A compression coil spring or a spring receiver that presses the shoe web downward to adhere to the spacer is attached to a portion of the holding pin that protrudes upward from the shoe web.

Problems to be Solved by the Invention However, such a conventional shoe hold-down device has a large number of parts and requires a plurality of members to be aligned and a holding pin to be inserted therethrough. There was a problem that the manufacturing cost of the drum brake was increased. Further, since it is necessary to provide a long hole (or a notch) for allowing the holding pin to pass through the shoe web, the strength of the brake shoe is reduced correspondingly, and the thickness of the shoe web is required to satisfy the predetermined required strength. Measures such as thickening were necessary.

The present invention has been made in view of the above circumstances, and its purpose is to provide an easy and quick assembling work with a small number of parts and to provide a long hole or a notch in the shoe web. An object of the present invention is to provide a shoe hold-down device that does not need to be provided.

Means for Solving the Problems In order to achieve the above object, the present invention provides the above (a)
A drum brake that includes a backing plate and (b) a brake shoe and generates a braking force when the brake shoe is pushed out to the outer peripheral side of the backing plate to position a height of an intermediate portion in a longitudinal direction of the brake shoe. (C) a shoe hold-down device that holds the brake shoe so that the shoe web is substantially parallel to the backing plate, together with a pair of support portions that support both ends in the longitudinal direction. A contact portion which is brought into contact with the lower surface of the shoe web, a mounting portion which is press-fitted and fixed to the packing plate, and the mounting portion and the contact portion are integrally connected and arranged on the backing plate. In the installed state, such as a connecting portion positioned near the inner peripheral edge of the shoe web (D) a substantially L-shaped support member, one end of which is engaged with the connecting portion, and which protrudes upward from inside the inner peripheral edge of the shoe web and extends to the outer peripheral side. It has a leaf spring that presses the shoe web downward by its own spring force when the other end of the shoe web is brought into contact with the upper surface of the shoe web.

In addition, the above-mentioned height means a distance from the backing plate, and the lower side, upper side, and lower side means upper side far from the backing plate and lower side closer to the backing plate.

In such a shoe hold-down device for a drum brake, the shoe web of the brake shoe is supported by the abutting portion of the support member, the mounting portion of which is press-fitted and fixed to the backing plate, and one end is connected to the connecting portion of the support member. When the other end of the leaf spring is brought into contact with the upper surface of the shoe web, the shoe web is pressed downward by the spring force of the leaf spring. Thereby, the height of the intermediate part in the longitudinal direction of the brake shoe is positioned by the support member and the leaf spring, and both ends in the longitudinal direction are supported by the pair of support parts. It is held in a constant posture that is substantially parallel.

Here, the shoe hold-down device of the present invention is composed of a support member press-fitted and fixed to the backing plate, and a leaf spring disposed over the support member and the shoe web.
Since it is mainly composed of members, the number of parts is significantly reduced as compared with a conventional shoe hold-down device. Moreover, for the support member, the mounting portion may be press-fitted and fixed to the backing plate. For the leaf spring, one end side is engaged with the connection portion of the support member and the other end is brought into contact with the upper surface of the shoe web. Therefore, assembling work is easier and easier than when a plurality of members are aligned and a holding pin is inserted and a compression coil spring or the like is arranged on the holding pin as in the related art. Can be done quickly. Further, since the leaf spring protrudes upward from the inside of the inner peripheral edge of the shoe web, there is no need to provide a long hole or a notch in the shoe web for passing the holding pin as in the related art, and the brake shoe The strength is improved and the thickness of the shoe web can be reduced if the strength is the same.

As described above, according to the shoe hold-down device of the present invention, the number of parts is small, and the assembling work can be performed easily and quickly, so that the manufacturing cost of the drum brake is greatly reduced. Further, since there is no need to provide a long hole or a notch in the shoe web, the strength of the brake shoe is improved by that much, and the thickness of the shoe web can be reduced with the same required strength.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a view showing a main part of a drum brake provided with a shoe hold-down device according to one embodiment of the present invention,
On the backing plate 10, a pair of brake shoes 12, 14 each having an arc shape as a whole are arranged along the outer peripheral edge of the backing plate 10 in a state where they face each other. The brake shoes 12 and 14 are formed in a plate-shaped shoe rim 16 curved in an arc shape, and are formed in a plate shape. The brake shoes 12 and 14 are protruded from the inner peripheral surface of the shoe rim 16 and are substantially parallel to the plate surface of the backing plate 10. Shoe web 18 and a lining 19 fixed to the outer peripheral surface of the shoe rim 16 so that the shoe web 18 can be expanded by the shoe hold down devices 20 and 22 at the longitudinal middle portion of the shoe web 18. Supported. The opposite ends of the shoe webs 18 of the brake shoes 12 and 14, that is, the lower ends in FIG. 3 are respectively brought into contact with the side surfaces of the anchor 28 fixed on the backing plate 10 according to the biasing forces of the springs 24 and 26. In addition, the other ends of the shoe webs 18 of the brake shoes 12 and 14, that is, the upper ends in FIG. 3 are respectively engaged with both ends of the wheel cylinder 30 fixed on the backing plate 10. . Also,
A pair of ledges 58, 60 is provided at portions of the backing plate 10 located at both ends in the longitudinal direction of the brake shoes 12, 14.
Are protruded integrally, and the brake shoes 12,1
One (lower) side end face of the shoe rim 16 in the width direction is provided on the top faces of the ledges 58 and 60. The ledges 58 and 60 correspond to a pair of supports.

A parking brake lever 32 is provided on the surface of the shoe web 18 of the brake shoe 12 facing the backing plate 10.
The other end of the parking brake lever 32 is connected to a parking cable 36 at one end thereof. A strut 38 is bridged between the middle portion of the parking brake lever 32 in the longitudinal direction and the shoe web 18 of the brake shoe 12 and the shoe web 18 of the brake shoe 14, and the brake shoes 12, 14 are internally formed by the strut 38. It is supported from the circumferential side. Reference numeral 40 denotes a shoe return spring.

Next, the operation of the drum brake configured as described above will be described.

The brake shoes 12, 14 are pushed outward by the wheel cylinder 30 against the urging force of the shoe return spring 40, so that the brake shoes
The outer peripheral surfaces of 12, 14 are pressed against the inner peripheral surface of a rotating drum (not shown), and braking by a service brake is performed. On the other hand, when the parking brake lever 32 is rotated in the parking brake operation direction (counterclockwise direction in FIG. 3) by the parking cable 36, the brake shoe 14 is pushed out to the outer peripheral side via the strut 38 and the strut 38 is parked. When the pin 34 is rotated counterclockwise in FIG. 3 with the end of contact with the brake lever 32 as a fulcrum, the brake shoe 12 is pushed outward by the pin 34, whereby the brake shoes 12, 14 Is pressed against the rotating drum, and braking by the parking brake is performed. At the time of the parking brake braking, one of the brake shoes 12 has a direction in which the shoe web 18 is inclined so as to approach the backing plate 10 toward the inner peripheral side as shown by an arrow A in FIG. Rotational force acts. For this reason, the pressing area of the brake shoe 12 against the rotating drum (the pressing area at which a suitable pressing force is obtained) is reduced, and the braking torque is reduced, or an excessive force may act on the brake shoe 12 or the like. Was.

Here, in the present embodiment, the shoe hold down devices 20, 22 are configured as follows. Since the shoe hold-down devices 20 and 22 have the same configuration, the description of the configuration will be made for one shoe hold-down device 20. As shown in FIGS. 1 and 2 in an enlarged manner, the shoe hold-down device 20 has an L-shape, a leaf spring 44 having an engagement hole 42 formed at one end 44a side, and a substantially parallel to each other. And a U-shaped member 52 having a connecting portion 50 for connecting one end of each of the parallel portions 46 and 48 to each other, and a part of the backing plate 10. One parallel portion 48 is press-fitted and fixed between the L-shaped projection 54 formed by cutting and raising and the backing plate 10, and the upper surface of the other parallel portion 46, that is, opposite to the backing plate 10 side. Side surface is the shoe web of brake shoe 12
The lower surface 18, that is, the surface facing the backing plate 10, is brought into contact with a portion located on the inner peripheral side. Thereby, the U-shaped member 52 prevents the brake chute 12 from tilting so that the shoe web 18 approaches the backing plate 10 as the shoe web 18 moves toward the inner peripheral side during the packing brake operation. In the present embodiment, the U-shaped member 52 constitutes a support member, and the parallel portions 46, 4
Reference numeral 8 functions as a contact portion and a mounting portion, respectively.

As is apparent from FIG. 1, the connecting portion 50 of the U-shaped member 52 is located near the inner peripheral edge of the shoe web 18 of the brake shoe 12, and the connecting portion 50 has An L-shaped projection 56 is provided by cutting and raising the portion, and the engagement hole 4 formed in one end 44a of the leaf spring 44 is formed.
2 is engaged with the projection 56. The other end 44b of the leaf spring 44 protruding upward from the inside of the inner peripheral edge of the shoe web 18, i.e., in a direction away from the backing plate 10 and extending to the outer peripheral side, is brought into contact with the upper surface of the shoe web 18. The shoe web 18 with its own spring force
Is pressed downward, that is, toward the side approaching the backing plate 10, and the shoe web 18 is brought into contact with the parallel portion 46 of the U-shaped member 52. As a result, the height of the intermediate portion in the longitudinal direction of the brake shoe 12 is determined, and both ends in the longitudinal direction are supported by the ledges 58 and 60. Is maintained in a constant posture substantially parallel to
The leaf spring 44 is, for example, elastically deformed in a state where the other end 44b is in contact with the upper surface of the shoe web 18, while the one end 44a
Side down along the connecting part 50 to project the engaging hole 42
By engaging with 56, it can be assembled to the U-shaped member 52.

The parking brake lever 32 is configured to be rotated between the parallel portions 46 and 48 of the U-shaped member 52, and the parking brake lever 32 when the lining 19 of the brake shoes 12 and 14 is worn to the wear limit. 32
In order to prevent the parking brake lever 32 from interfering with the connecting portion 50 of the U-shaped member 52 even when turning, and to prevent the shoe web 18 from coming off from the parallel portion 46 during braking, The dimensions and mounting position of the U-shaped member 52 are determined in advance.

Thus, according to the present embodiment, the backing plate 10
The parallel portion 46 of the U-shaped member 52 fixed to the
The surface of the shoe web 18 facing the backing plate 10 and a portion located on the inner peripheral side of the twelve shoe webs 18 are abutted, and the other end 44b of the leaf spring 44 presses the shoe web 18 downward. Therefore, the brake shoe 12 is held in a fixed posture in which the shoe web 18 is substantially parallel to the backing plate 10, and for example, the A
Even if a rotational force is generated in the direction, the brake shoe 12 is prevented from tilting so that the shoe web 18 approaches the backing plate 10 as it goes toward the inner peripheral side. As a result, when the parking brake is operated, the pressing area of the lining 19 of the brake shoe 12 against the inner peripheral surface of the rotating drum,
More precisely, the pressing area of the brake shoe 12 for obtaining a suitable pressing force against the rotating drum is sufficiently ensured, and the braking torque is appropriately ensured.
It is possible to prevent an excessive force from acting on the portion 12 and the engagement portion of the wheel cylinder 30 with the brake shoe 12 and the like.

Here, the shoe hold down devices 20 and 22 of the present embodiment
Is a U-shaped member press-fitted and fixed to the backing plate 10.
52 and a leaf spring 44 disposed over the U-shaped member 52 and the shoe web 18 as a main component. The score is greatly reduced. In addition, for the U-shaped member 52, one of the parallel portions 48 may be press-fitted and fixed to the backing plate 10.For the leaf spring 44, the other end 44b is brought into contact with the upper surface of the shoe web 18 and one end 44a is formed. Can be engaged with the connecting portion 50 of the U-shaped member 52.Therefore, a plurality of members are aligned and a holding pin is inserted therethrough as in the related art, or a compression coil spring or the like is disposed on the holding pin. As compared with the case of the above, the assembling operation can be performed easily and quickly, and the manufacturing cost of the drum brake is greatly reduced in combination with the reduction in the number of parts. Further, since the leaf spring 44 protrudes upward from the inside of the inner peripheral edge of the shoe web 18, there is no need to provide a long hole or a notch in the shoe web 18 for passing the holding pin as in the related art,
The strength of the brake shoes 12, 14 is improved, and the thickness of the shoe web 18 can be reduced if the strength is the same.

The above is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a cross section taken along the line II in FIG. 3, and is a diagram showing a main part. FIG. 2 is a perspective view of the shoe hold-down device in FIG. FIG. 3 is a diagram showing an example of a drum brake provided with a shoe hold-down device according to an embodiment of the present invention, and is a front view showing a main part. FIG. 4 is a view of the brake shoe 12 and the like in FIG. 3 as viewed from the shoe web side, and is a view in which a parking brake lever and the like are removed. 10: Backing plate 12, 14: Brake shoe 18: Shoe web 20, 22: Shoe hold down device 44: Leaf spring 44a: One end 44b: Other end 46: Parallel part (contact part) 48: Parallel part (mounting) Part) 50: Connecting part 52: U-shaped member (supporting member) 58,60: Lead part (supporting part)

Claims (1)

(57) [Scope of request for utility model registration] 1. A backing plate (10) and a plate-shaped shoe web (18) are formed into an arc shape as a whole, and are formed on the backing plate (10) at an outer peripheral edge of the backing plate (10). The brake shoes (1
2), wherein the brake shoe (12) is pushed to the outer peripheral side of the backing plate (10) to generate a braking force, and the height of the intermediate portion in the longitudinal direction of the brake shoe (12) is increased. The shoe web (18) is positioned together with a pair of supporting portions (58, 60) for supporting both ends in the longitudinal direction.
Is a shoe hold-down device that holds the posture of the brake shoe (12) so as to be substantially parallel to the backing plate (10), wherein the contact portion ( 46), a mounting part (48) press-fitted and fixed to the backing plate (10), and the mounting part (48) and the contact part (4
6) and a connecting portion (5) positioned near the inner peripheral edge of the shoe web (18) in the state of being disposed on the backing plate (10).
0), which is substantially L-shaped, is engaged with the connecting portion (50) at one end (44a) side, and is on the inner peripheral side of the shoe web (18). The other end (44b) projecting upward from the inside of the edge and extending to the outer peripheral side is brought into contact with the upper surface of the shoe web (18), so that the shoe web (18) is lowered by its own spring force. And a leaf spring (44) for pressing the shoe brake down.