JP2002295543A - Drum brakes for vehicles - Google Patents

Abstract

(57) [Problem] To provide a drum brake using a U-shaped shoe body as a brake shoe, by increasing the rigidity of the end of the shoe body that comes into contact with an actuator such as a wheel cylinder or an anchor, for a long time. A good braking action can be performed. SOLUTION: A contact plate 30f and an engagement portion 30g are provided at one end 30d and the other end 30e of a shoe body 30, respectively. The abutment plate 30f connects the end of the rim 30c to the web 30.
The webs 30a and 30b are formed to extend beyond the webs 30a and 30b. The engagement portion 30g is formed by bending a corner portion between the rim 30c and the contact plate 30f so as to slightly bulge out of the contact plate 30f. When the brake shoe 21 is assembled to the back plate 20, the contact plates 30f, 30f come into contact with the bearing surfaces 22a, 22b of the anchor 22, and the engaging portions 30g, 3
0 g is engaged with both corners of the anchor 22 on the outer side in the radial direction of the back plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake used for a traveling vehicle such as a four-wheeled vehicle, and more particularly, to a brake shoe disposed inside a back plate.

[0002]

2. Description of the Related Art A drum brake used in an automobile is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-14925. The drum brake has a shoe body having a U-shaped cross section formed by cutting a part of a ring body having high strength elasticity from a brake shoe provided inside a back plate, and a rim of the shoe body. A duo-servo type with a lining attached to the outer peripheral surface and a one-sided wheel cylinder interposed between both ends of the shoe body folded in a waveform, compared to a drum brake using a pair of bow-shaped brake shoes Therefore, while reducing the number of parts and man-hours to reduce costs, a large braking effect by the self-energy action characteristic of the duo servo type is achieved.

[0003]

In such a drum brake, the end of the shoe body which comes into contact with the piston or the anchor of the wheel cylinder receives an expanding force or a braking reaction force. The parts need to have a certain amount of rigidity, but at the end folded into the corrugation of the prior art, the folded shape expands outward due to the load from the piston and anchor, each becoming a single thin plate Since the force is reduced, buckling may occur at the end, which may hinder smooth operation. In particular, such a phenomenon is remarkable on the side of the anchor portion of the duo servo type, which receives a large collision or braking reaction force due to the self-energy action.

Accordingly, the present invention relates to a drum brake using a U-shaped shoe main body as a brake shoe. The rigidity of the end of the shoe main body that comes into contact with an actuator such as a wheel cylinder or an anchor is improved to improve the durability for a long time. It is an object of the present invention to provide a vehicle drum brake capable of performing a proper braking action.

[0005]

According to the present invention, there is provided, in accordance with the above-mentioned object, a U-shaped cross section in which the outer peripheral edges of a pair of webs parallel to the back plate are connected by a rim perpendicular to the back plate. A brake body having a shoe body and a lining adhered to an outer peripheral surface of the rim, and supporting an end of the shoe body on an actuator or an anchor such as a wheel cylinder, thereby obtaining the brake shoe. In the vehicle drum brake which expands and contracts inward and outward directions of the back plate, an end of the shoe body is closed by a contact plate.

The above-mentioned contact plate may be formed by extending one of the pair of webs and the rim at the end of the shoe body and bending the extended portion to the other end surface. In addition, an engagement portion that engages with the actuator or the anchor may be provided protrudingly on the outer side in the radial direction of the back plate of the contact plate.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a drum-in-disk brake used for a rear wheel of an automobile will be described below with reference to the drawings. The drum-in disc brake 1 is a disc brake 2 used as a main brake.
A drum brake 3 used as a parking brake is provided inside the vehicle.
3, a drum-in-disk rotor 4 is commonly used.

The above-mentioned drum-in-disk rotor 4 is formed by integrally forming a disk rotor 4b for disk brake around the opening of a brake drum 4a for drum brake. By fixing to the hub 6 between the wheel 5 and the hub 6, the wheel 5, the hub 6, and a wheel (not shown) are attached so as to rotate integrally in the arrow A direction together with the wheel 5.

The disk brake 2 includes the disk rotor 4b and a knuckle 7 at one side of the disk rotor 4b.
And a caliper body 11 supported by the caliper bracket 10 so as to be movable in the disk axial direction in the accommodating space 25a of the packing plate 25 for a drum brake, and the operation of the caliper body 11. A pair of friction pads 12, 12 are provided between the portion 11a and the reaction portion 11b, and are opposed to each other with the disk rotor 4b interposed therebetween.

The action portion 11a of the caliper body 11 includes:
A piston 14 is housed in a cylinder hole 13 opened to the disk rotor 4b side. When a pressure liquid is supplied from a separate hydraulic master cylinder (not shown) to a hydraulic chamber 15 at the bottom of the cylinder hole 13, the piston 14 By moving in the direction of the rotor, the friction pad 12 on the action portion side is pressed against one side surface of the disk rotor 4b. Next, the caliper body 11 is moved in the direction of the action portion by the braking reaction force, and the reaction force claw 11c of the reaction portion 11b is moved to the friction pad 12 on the reaction portion side.
Is pressed against the other side surface of the disk rotor 4b to perform a braking operation as a main brake.

The drum brake 3 includes a back plate 20 which is bolted to the knuckle 7 and a brake shoe 2 which is disposed inside the back plate 20 so as to be able to expand and contract.
1, an anchor 22 for supporting both ends of the brake shoe 21, and a secondary side of the brake shoe 21 (FIG. 1,
Parking actuating lever 23 disposed on the right side of 2)
And the primary side of the brake shoe 21 on the radially inner side of the back plate of the anchor 22 (the left side in FIGS. 1 and 2).
A single shoe duo-servo type having a connecting rod 24 interposed between the parking operation lever 23 and the packing plate 25 is fixed to the outer periphery of the back plate 20.

The brake shoe 21 is formed by cutting off a portion of a ring having a high elasticity such as mild steel, stainless steel, and high-strength plastic, and the shoe body 30 is formed.
And a pair of linings 31 and 32 attached to the outer peripheral surface of the rim of the shoe body 30. Shoe body 3
0 is a pair of arcuate webs 3 parallel to the back plate 20
A plurality of shoe clamps 33 each having a U-shaped cross section formed by connecting the outer peripheral edges of Oa and 30b with an arc-shaped rim 30c orthogonal to the back plate 20 and fixing the web 30b on the back plate side to the back plate 20. It is arranged to be elastic and expandable and contractible.

The shoe body 30 has one end 30d and the other end 30e supported by an anchor 22 having a rectangular section fixed to the back plate 20. The webs 30a and 30b near the other end 30e have the above-described structure. The parking operation lever 23 is rotatably supported by a support shaft 34 and a collar 35 so as to be rotatable in and out of the back plate.

A parking brake wire cable 36 introduced from the outside of the back plate is connected to the tip of the parking operation lever 23. When the driver pulls the wire cable 36 by the parking brake operation, the drum is pulled. The brake 3 operates as a parking brake. A return spring 37 is stretched between the connecting rod 24 and the web 30a on the side opposite to the back plate.
The second secondary side, the parking operation lever 23 and the connecting rod 24 are urged in directions approaching each other.

One end 30d and the other end 3 of the shoe body 30
0e is provided with a contact plate 30f and an engagement portion 30g, respectively. When the shoe body 30 is press-formed, the abutment plate 30f connects the ends of the rim 30c with the webs 30a, 3a.
The webs 30a, 30b are formed by bending the extended portions so as to overlap the end surfaces of the webs 30a, 30b, and the tips thereof are brought into close contact with the inner edges of the webs 30a, 30b. Also, when the extending portion of the rim 30c is bent to form the contact plate 30f, the engaging portion 30g causes the corner between the rim 30c and the contact plate 30f to slightly bulge out of the contact plate 30f. It is formed by bending back.

The contact plate 30f has one end 30d and the other end 3d.
0e are provided so as to cover the whole of the U-shape of the webs 30a, 30b and the rim 30c, and the rigidity of the shoe body 30 is larger than that of the conventional one as the end of the shoe body 30. When assembled, the contact plates 30f, 30f are
2a and 22b are contacted. Further, the engaging portions 30g, 30g are engaged with both corners of the anchor 22 on the outer side in the radial direction of the back plate, and the brake shoes 30
d, 30e are prevented from coming off the anchor 22, and the contact between the contact plate 30f and the bearing surface 22a is maintained.

This embodiment is constructed as described above. In the parking drum brake 3, when the wire cable 36 is pulled by the driver's parking brake operation, the parking operation lever 23 moves the support shaft 34. Rotating clockwise in FIGS. 1 and 2 around the fulcrum, pushing the connecting rod 24 to the left in FIGS. 1 and 2, the primary side of the brake shoe 21 (the left side in FIGS.
a, while separating the abutment plate 30f at one end 30d from the support surface 22a of the anchor 22 to the left in FIGS.
a on the inner peripheral surface.

Next, when the pulling of the wire cable 36 is continued and the parking operation lever 23 is further rotated, the secondary side of the brake shoe 21 (the right side in FIGS. 1 and 2) of the web 30a is The contact plate 30f of the other end 30e is expanded to the right in FIGS. 1 and 2 while being separated from the anchor 22, and the lining 32 on the secondary side is pressed against the inner peripheral surface of the brake drum 4a.

From such a state, when a rotational force in the direction of arrow A, for example, acts on the brake drum 4a,
The brake shoe 21 integrally rotates with the brake drum 4a in the same direction, and slightly rotates in the same direction.
The contact plate 30f of e contacts the bearing surface 22b of the anchor 22, and the co-rotation of the brake shoe 21 is regulated. As a result, a braking torque is generated between the linings 31, 32 and the inner peripheral surface of the brake drum 4a, and the rotation of the brake drum 4a is restricted. Brake drum 4
a generated by the brake shoe 21
Is transmitted to the anchor 22 from the contact plate 30f at the other end 30e through the web 30a.

Further, in the drum brake 3 of this embodiment employing the duo-servo type, the brake shoes 21
The self-energizing action generated on the primary side of the brake drum acts as a self-energizing force on the secondary side, and the brake drum 4
a is braked by a large servo force.

For this reason, on the other end 30e, which is the fulcrum of the expansion of the brake shoe 21, the bearing surface 22 of the anchor 22
A large impact force or braking reaction force due to the self-energy action acts on the contact plate 30f that contacts the contact end b.
0e of the contact plate 30f is composed of the webs 30a and 30b and the rim 3
0c while supporting the end face of the anchor 22
b, so that the folded shape like the conventional folded end does not expand, and the contact plate 30
Since f is in contact with the bearing surface 22b to spread the stress widely, buckling and wear can be prevented as much as possible, and a favorable braking action can be smoothly performed for a long period of time. Further, the servo force due to the self-energy action described above also acts on the one end 30d side, which is the fulcrum of the expansion of the brake shoe 21, even when the brake drum 4a rotates in the direction opposite to the arrow A. Similarly, buckling and wear can be prevented as much as possible with the contact plate 30f on the one end 30d side.

Further, in the present embodiment, the engaging portions 30g, 30g are protruded from the contact plate 30f to be engaged with both corners of the anchor 22 on the outer side in the radial direction of the back plate. 22 can be effectively prevented from falling off, and the contact between the contact plate 30f and the bearing surface 22a can be maintained well.

In the above embodiment, the drum-in-disc brake combined with the disc brake has been described. However, the present invention may be a single-type drum brake, and a pair of arcuate brake shoes are used to face each other. It is also applicable to drum brakes.

Further, the contact plate at the end of the shoe body can be formed by extending either the web or the rim. Further, in the present invention, it is advantageous in terms of manufacturing and cost to use a part of the web or rim of the shoe body as a contact plate, but the contact plate is formed separately from the brake shoe and used for welding or the like. You may make it fix by suitable connection means.

[0025]

As described above, according to the vehicle drum brake of the present invention, even when the brake shoe has a U-shaped cross section, the rigidity of the end of the shoe main body that comes into contact with the actuator or the anchor is increased by the contact plate. As a result, buckling and wear can be prevented as much as possible with respect to the impact force and the braking reaction force with the actuator and the anchor, and a favorable braking operation can be smoothly performed for a long period of time. In addition, if the contact plate at the end of the shoe body is integrally formed using a web or rim, the number of manufacturing steps, parts, and assembly steps can be reduced.
This is beneficial in terms of manufacturing and cost.

Further, by protruding an engaging portion for engaging with the actuator or the anchor on the radially outer side of the back plate of the contact plate, it is possible to effectively prevent the brake shoe from falling off from the actuator or the anchor. The contact between the contact plate and the bearing surface can be maintained well.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part of FIG. 1 showing an embodiment of the present invention.

FIG. 2 is a front view of a drum-in-disk brake showing one embodiment of the present invention.

FIG. 3 shows one embodiment of the present invention in FIG.
I cross section

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1 showing one embodiment of the present invention.

FIG. 5 is an enlarged perspective view of a main part of a brake shoe showing one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Drum-in disc brake, 2 ... Disc brake, 3 ... Drum brake, 4 ... Drum-in disc rotor, 4a ... Brake drum, 4b ... Disc rotor, 2
0: back plate, 21: brake shoe, 22: anchor, 22a, 22b bearing surface, 23: parking operation lever, 24: connecting rod, 30: shoe body, 30a, 30b: web, 30c rim, 30d: shoe body 30 , 30e ... the other end of the shoe body 30, 30f ... abutment plate, 30g ... engagement part, 31, 32 ... lining, 36 ... wire cable

Continued on front page F-term (reference)

Claims (3)

[Claims] 1. A shoe body having a U-shaped cross section in which the outer peripheral edges of a pair of webs parallel to the back plate are connected by a rim perpendicular to the back plate, and adhered to the outer peripheral surface of the rim. Drum brake for a vehicle, wherein a brake shoe having a lining is provided, an end of the shoe body is supported by an actuator or an anchor such as a wheel cylinder, and the brake shoe expands and contracts in and out of a back plate. 3. The vehicle drum brake according to claim 1, wherein an end of the shoe body is closed by a contact plate. 2. The device according to claim 1, wherein the contact plate is formed by extending one of a pair of webs and a rim at an end of the shoe body and bending the extended portion to another end surface. 4. A drum brake for a vehicle according to claim 1. 3. The vehicle drum brake according to claim 1, wherein an engagement portion that engages with the actuator or the anchor protrudes outward of the contact plate in a back plate radial direction.