JP2002295553A - Drum brake for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable adjustment of braking clearance in a brake drum even in a brake drum for parking brake with restricted dimension. SOLUTION: An adjusting lever 23 and a parking action lever 24 are rotatably supported at a primary side and a secondary side of a shoe main body 30, respectively. A brake clearance adjusting mechanism 26 adjusting the clearance between linings 31, 32 and a brake drum is set at the top end of the adjusting lever 23. A connecting rod 25 is intervened between the adjusting lever 23 and the parking action lever 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake which performs a braking operation using a parking operation lever in a traveling vehicle such as a four-wheeled vehicle, and more particularly to a drum brake suitable as a parking brake.

[0002]

2. Description of the Related Art A drum brake used as a parking brake of an automobile is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-149.
No. 25. This drum brake
Brake shoes arranged inside the back plate,
Consisting of a shoe body formed by cutting off one part of a ring body having high strength elasticity, and a lining adhered to the rim outer peripheral surface of the shoe body, between the ends of the web of the shoe body. A type called a single shoe with a single-sided wheel cylinder interposed, compared to a drum brake using a pair of bow-shaped brake shoes, while omitting the number of parts,
The brake effect is the same as that of the duo servo type.

[0003]

Such a drum brake is often used as a so-called drum-in-disk brake in which a disc brake applied to a main brake for a rear wheel is combined with a parking brake only for parking. Therefore, the diameter is smaller than that of the drum brake as the main brake.

For this reason, when the lining wears out due to long-term use and the braking gap between the lining and the brake drum is widened, it is desired that the gap can be adjusted inside the drum brake. Most brakes do not have a space for the adjustment mechanism because the space between the anchor and the hub hole at the center of the back plate is narrow, and the braking gap cannot be adjusted in most cases.

[0005] Some independent drum brakes, whose size is not so limited, have a connecting rod provided with a braking clearance adjusting mechanism. However, with the recent increase in size and weight of automobiles, the use of drum brakes has been increasing. It is desired to improve the braking force without increasing the size, and one of the measures is to increase the lever ratio by increasing the parking operation lever.

However, in this case, if the length of the parking operation lever is increased, the parking operation lever interferes with the connecting rod. Therefore, the braking gap adjusting mechanism which takes up space is removed to make the connecting rod thin. It is necessary to adjust the braking gap similarly to the drum-in-disk brake.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle drum brake capable of adjusting a braking clearance inside the drum brake even for a small-diameter parking brake or the like.

[0008]

According to the first aspect of the present invention, there is provided a shoe body formed by cutting a portion of a ring having a high elasticity inside a back plate, and the shoe body. A brake shoe having a lining attached to the outer peripheral surface of the rim of the main body is disposed, both ends of the shoe main body are supported by anchors, the brake shoes are expanded, and the lining is mounted on a brake drum. In the vehicle drum brake to be brought into sliding contact, a parking operation lever is rotatably supported on one of the primary side and the secondary side of the shoe main body, and an adjustment lever is rotatably supported on the other side, and a distal end side of the adjustment lever is A brake gap adjusting mechanism for adjusting a gap between the lining and the brake drum, wherein the parking operation lever and the adjustment lever are provided; Interposed a connecting rod between.

In a second aspect of the present invention, a pair of brake shoes having a shoe body having a web and a rim and a lining adhered to an outer peripheral surface of the rim are arranged inside the back plate to face each other. At least one end of the shoe body is supported by an anchor, and a parking operation lever is rotatably supported on one of the shoe bodies so that the brake shoe is expanded by the rotation of the parking operation lever. Then, in a vehicle drum brake for bringing the lining into sliding contact with a brake drum, an adjusting lever is rotatably supported on the other side of the shoe body, and the lining and the brake drum are connected to the tip side of the adjusting lever. A braking gap adjusting mechanism for adjusting a gap between the parking operating lever and the adjusting lever; Interposed a connecting rod between.

Further, as a third invention, a braking clearance adjusting mechanism used in the first and second inventions has a female screw provided on an adjust lever and a distal end abutting on the inner peripheral surface of the rim, and is screwed to the female screw. Adjustment bolt, and rotation restricting means for restricting rotation of the adjustment bolt.

[0011]

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 FIGS. The drum-in-disc brake 1 has a structure in which a drum brake 3 used as a parking brake is provided inside a disk brake 2 used as a main brake. Used.

The above-mentioned drum-in-disk rotor 4 is formed by integrally forming a disk rotor 4b for a disk brake around the opening of a brake drum 4a for a 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 on one side of the disk rotor 4b.
And a caliper body 11 that is supported by the caliper bracket 10 so as to be movable in the disk axial direction within a housing space 27a of a packing plate 27 for a drum brake, and an operation of the caliper body 11. A pair of friction pads 12 and 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 bolted to the knuckle 7 and a brake shoe 2 disposed inside the back plate 20 so as to be able to expand and contract.
1, an anchor pin 22 supporting both ends of the brake shoe 21, and a brake shoe 21 on the primary side (the left side in FIGS. 1 and 2) and the secondary side (the right side in FIGS. 1 and 2). A connecting rod 25 interposed between the adjusting lever 23 and the parking operation lever 24, the anchor pin 22 and the hub hole 20 a of the back plate 20 between the levers 23, 24, and a distal end side of the adjusting lever 24. Braking gap adjusting mechanism 26
The packing plate 27 described above is fixed to the outer periphery of the back plate 20.

The brake shoe 21 is a shoe body 30 formed by cutting off a portion of a ring having a high elasticity such as mild steel, stainless steel, and high strength plastic.
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
Oa, 30b are formed in a U-shaped cross section in which the outer peripheral edges of the webs 30a are connected by an arc-shaped rim 30c orthogonal to the back plate 20, and the webs 30b on the back plate side are formed on a plurality of guide pieces 33 fixed to the back plate 20. It is arranged to be elastic and expandable and contractible.

One end 30d and the other end 3 of the shoe body 30
Reference numeral 0e is supported by an anchor pin 22 fixed to the back plate 20. On the primary side and the secondary side between the webs 30a and 30b, the above-described adjustment lever 23 and parking operation lever 24 are provided with the webs 30.
The support shafts 34 and 35 fitted near both ends of the a and 30b are rotatably supported in the back plate inside and outside with the collar 36 interposed therebetween.

At the base ends of the adjusting lever 23 and the parking operation lever 24, a plate-like connecting rod 2 is provided.
A return spring 3 is provided between the connecting rod 25 and the web 30a on the side opposite to the back plate.
A tension member 7 urges the secondary side of the brake shoe 21, the parking operation lever 24, and the connecting rod 25 in directions approaching each other. At the tip of the parking operation lever 24, a wire cable 38 for a parking brake introduced from outside the back plate is provided.
The drum brake 3 is operated as a parking brake by pulling the wire cable 38 by a driver's parking brake operation.

The braking clearance adjusting mechanism 26 has a female screw hole 40 screwed into a cylindrical body 23a in which the tip of the adjusting lever 23 is rounded in the radial direction of the back plate, and an adjusting bolt is provided in the female screw hole 40. A male screw 41a is screwed into the adjusting lever 41, and the tip of the male screw 41a is brought into contact with the rim 30c.
The locking claw 42a of the rotation restricting member 42 fixed near the third cylindrical body 23a is engaged.

The ratchet 41b and the locking claw 42a allow only the rotation of the adjusting bolt 41 to project the male screw 41a outward of the back plate, and restrict the rotation of the male screw 41a to be pulled back inward of the back plate. When the braking gap between the linings 31 and 32 of the brake shoe 21 and the inner peripheral surface of the brake drum 4a becomes larger than a predetermined value, the adjusting bolt 41 is rotated in one direction, and the male screw 41a is connected to the back plate. By protruding outward, the adjust lever 23 and the primary side of the brake shoe 21 relatively move inward and outward of the back plate, and further, the second side of the brake shoe 21 is moved back through the connecting rod 25 and the parking operation lever 24. Move outside the plate.

As a result, the inoperative positions of the brake shoe 21 on the primary side and the secondary side are shifted to the lining 31,
It is changed to the outside of the back plate to fill in the wear of 32,
A predetermined braking gap is reset between the brake drum 4a and the inner peripheral surface.

This embodiment is configured as described above. In the parking drum brake 3, when the wire cable 38 is pulled and the parking operation lever 24 is rotated, the connecting rod 25 is moved to the position shown in FIGS. Pushed to the left, the primary side of the brake shoe 21 (FIG. 1,
2) is expanded while the one end 30d of the web 30a is separated from the anchor pin 22 to form the lining 31.
Is pressed against the inner peripheral surface of the brake drum 4a.

Next, when the pulling of the wire cable 38 is continued and the parking operation lever 24 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 other end 30e is expanded to the right in FIGS. 1 and 2 while being separated from the anchor pin 22, and the lining 32 is pressed against the inner peripheral surface of the brake drum 4a.

Then, 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 the other end 30e of the web 30a of the brake shoe 21 abuts on the anchor pin 22,
The co-rotation of the brake shoe 21 is restricted. As a result,
A braking torque is generated between the linings 31 and 32 and the inner peripheral surface of the brake drum 4a, and the rotation of the brake drum 4a is regulated. The braking torque generated with the brake drum 4a is transmitted to the anchor pin 22 from the other end 30e through the web 30a of the brake shoe 21.

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. Note that this servo force also acts when the brake drum 4a tries to rotate in the direction opposite to the arrow A.

Further, the lining 31, 31 of the brake shoe 21
If the wear gap 32 is worn and the braking gap between the linings 31, 32 and the inner peripheral surface of the brake drum 4a is expanded beyond a predetermined value, the adjust bolt 41 is rotated in one direction by a manual operation of an operator. By projecting the male screw 41a outward of the back plate, the inoperative position of the brake shoe 21 is changed to the outside of the back plate to fill in the wear of the linings 31, 32, and between the inner surface of the brake drum 4a and The predetermined braking gap is reset.

As described above, in the drum-in-disc brake 1 of the present embodiment, even if the drum brake 3 is a small-diameter parking brake integrated with the disc brake 2 as the main brake, the lining of the brake shoe 21 3
A predetermined braking gap can be favorably set between the inner peripheral surface of the brake drum 4a and the wear portion of the brake drum 4a.

Next, another embodiment of the present invention will be described with reference to FIG. Note that the same components as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The drum-in disc brake 50 is configured by combining the disc brake 2 as a main brake and a drum brake 51 as a parking brake.

The drum brake 51 is connected to the back plate 2
0, a pair of brake shoes 52, 53 are disposed to face each other, and the brake shoes 52, 53 are expanded in opposite directions to each other with the anchor 54 as a fulcrum with respect to the brake drum 4a rotating in the direction of arrow A. Both brake shoes 5
Brake drum 4a
The leading and trailing brake shoes 52 and the trailing brake shoes 53 are provided on the outer periphery of an arcuate web 55a parallel to the back plate 20. On the surface, a shoe main body 55 having a rim 55b fixed in a direction perpendicular to the back plate 20 is provided, and the above-mentioned lining 56 is attached to the outer peripheral edge of the rim 55b.

The shoe bodies 55, 55 have one ends 55c,
55c is connected to the anchor pin 22, and the other ends 55d, 55
d are respectively supported by the anchors 54 described above. The adjusting lever 23 is provided on the web 55a of the leading brake shoe 52 on the back plate 20 side, and the parking operation lever 24 is provided on the web 55a of the trailing brake shoe 53 on the back plate 20 side. It is supported so as to be rotatable in and out of the back plate.

A braking gap adjusting mechanism 26 is attached to the tip side of the adjusting lever 23. A connecting rod with a braking gap adjusting mechanism conventionally provided near the anchor 54 on the fulcrum of the drum brake in the expanding position. Has been omitted. The parking operation lever 24 has a longer overall length than the conventional one by using a space expanded by omitting a connecting rod with a braking clearance adjusting mechanism.
By adopting a large lever ratio, the drum brake 5
A large braking force can be obtained without increasing the diameter of 1.

At the base ends of the adjusting lever 23 and the parking operation lever 24, a plate-like connecting rod 2 is provided.
A return spring 37 is stretched between the connecting rod 25 and the web 55a of the trailing brake shoe 53.

In this embodiment, by adopting the parking operation lever 24 which is longer than the conventional one, a large lever ratio is adopted, and a large braking force can be obtained without increasing the diameter of the drum brake 51 as a whole. Filling the wear of the 53 linings 56, 56, the brake drum 4a
The predetermined braking gap can be set well with the inner peripheral surface of the vehicle.

Although the above embodiment has been described with reference to a drum-in-disk brake combined as a disk brake, the present invention can be widely applied to a drum brake used alone.

[0036]

As described above, according to the present invention,
Even if the drum brake is a small-diameter parking brake integrated with the disc brake as the main brake, the braking gap between the brake shoe lining and the brake drum can be maintained well. In addition, the independent drum brake adopts a longer parking operation lever than the conventional one and adopts a large lever ratio, so that a large braking force can be obtained without increasing the diameter of the entire drum brake, and the brake shoe lining and A predetermined braking gap can be favorably maintained between the brake drum and the brake drum.

[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 exploded perspective view of a braking gap adjusting mechanism showing one embodiment of the present invention.

FIG. 6 is a front view of a drum brake showing another 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 pin, 23: Adjust lever, 23a: Cylindrical body,
24 parking actuating lever, 25 connecting rod, 26 braking gap adjustment mechanism, 27 packing plate, 30 shoe body, 30a, 30b web,
30c: rim, 30d: one end of shoe body 30, 30
e: the other end of the shoe body 30, 31, 32: lining, 38: wire cable, 40: female screw hole, 41: adjusting bolt, 41a: male screw of the adjusting bolt 41, 41b: ratchet, 42: rotation restricting member , 42a
... locking claw, 50 ... drum-in-disc brake, 51 ...
Drum brakes, 52, 53 ... brake shoes, 54 ...
Anchor, 55 ... Shoe body, 55a ... Web, 55b
... Rim, 55c ... One end, 55d ... Other end, 56 ... Lining

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference)

Claims (3)

[Claims] An inside of a back plate includes a shoe main body formed by cutting off a portion of a ring body having high strength elasticity, and a lining adhered to an outer peripheral surface of a rim of the shoe main body. A brake drum for a vehicle, in which both ends of the shoe body are supported by anchors, the brake shoe is expanded, and the lining slides on the brake drum, A parking operation lever is rotatably supported on one of the side and the secondary side, and an adjustment lever is rotatably supported on the other side, and a brake for adjusting a gap between the lining and the brake drum is provided on a tip side of the adjustment lever. A gap adjusting mechanism is provided, and a connecting rod is interposed between the parking operation lever and the adjustment lever. Drum brakes for vehicles. 2. A pair of brake shoes each having a shoe body having a web and a rim and a lining adhered to an outer peripheral surface of the rim are disposed inside a back plate to face each other. While supporting one end with an anchor, a parking operation lever is rotatably supported on one of the shoe bodies, and the brake shoe is expanded by the rotation of the parking operation lever. In a vehicle drum brake in which a lining slides on a brake drum, an adjusting lever is rotatably supported on the other side of the shoe body, and a gap between the lining and the brake drum is provided at a tip end side of the adjusting lever. A brake clearance adjusting mechanism for adjusting the distance between the parking operation lever and the adjustment lever; A drum brake for a vehicle, characterized by interposing a thrust rod. 3. The braking gap adjusting mechanism includes: an internal thread provided on the adjustment lever; an adjustment bolt having a tip abutting on an inner peripheral surface of the rim and being screwed to the internal thread; The vehicle drum brake according to claim 1 or 2, further comprising a rotation restricting unit that restricts rotation of the vehicle.