JP2001225782A - Drum brake device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum brake device capable of using a coil spring having a long coil length and a relatively low cost and capable of suppressing an increase of the manufacturing cost. SOLUTION: One end 55a of the coil spring 55 pressing a brake arm 53 in the brake releasing direction is put to a position near a tip section 53a between the swing center 66 and the tip section 53a of the brake arm 53, and the other end 55b of the coil spring 55 is put to a brake housing 52. A rod 56 regulating the longitudinal collapse of the coil spring 55 is inserted into the coil spring 55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake device for a vehicle, and more particularly, to an improvement in a drum brake device for a vehicle which can release a drum brake in an operating state by applying a coil spring to a brake arm.

[0002]

2. Description of the Related Art As a drum brake device for a vehicle, for example, Japanese Utility Model Registration No. 2523748, "Brake device for a motorcycle" is known. According to FIG. 3 of the publication, a spring receiving hole 31 is formed in the shoulder 8 on the left crankcase 2a side, a protrusion 33 is formed in the brake arm 6, and the protrusion 33 and the spring This is a motorcycle brake device in which a return spring 9 for returning the brake arm 6 is stretched between the receiving hole 31 and the receiving hole 31. In this case,
If the return spring 9 has a long coil length, the return spring 9 may fall down. Therefore, it is common to avoid the end of the brake cable receiver 11 connecting the brake cable 12 and to position the brake arm 6 on the shaft 6a side where the swing amount of the brake arm 6 is small. It is an effective method.

[0003]

However, since the return spring 9 has a small spring stroke (maximum length in use-minimum length in use), variation in spring load becomes remarkable. That is, it is necessary to use a high-grade (high-precision) spring in which the spring stroke and the spring load are made in good proportion. Since high-grade springs are expensive, they increase the cost of a vehicle drum brake device.

Accordingly, an object of the present invention is to provide a vehicle drum brake device that can employ an inexpensive spring.

[0005]

According to a first aspect of the present invention, a brake arm is swingably mounted on a brake housing, and the end of the brake arm is pulled by a cable to activate the drum brake. In the vehicle drum brake device, one end of a coil spring that pushes the brake arm in a direction to release the brake is applied between the swing center of the brake arm and the tip and a position near the tip, and the other end of the coil spring is A rod for restricting the coil spring from falling in the longitudinal direction is inserted into the coil spring against the brake housing.

[0006] A coil spring for releasing the brake in the operating state is disposed between the brake arm and the brake housing. At this time, one end of the coil spring is applied to a position between the swing center of the brake arm and the distal end and near the distal end, and the other end of the coil spring is applied to the brake housing. Further, a rod for restricting the coil spring from falling in the longitudinal direction is inserted into the coil spring.

[0007] By applying one end of the coil spring between the swing center of the brake arm and the tip and at a position near the tip, the overall length of the coil spring can be increased. A rod is inserted into the coil spring to regulate the longitudinal fall of the coil spring.

According to a second aspect of the present invention, the coil spring receiving surface formed on the brake arm side has a spherical convex shape.

By forming the coil spring receiving surface into a spherical convex shape, a slip can be generated between the coil spring receiving surface and one end of the coil spring with respect to the swing of the brake arm, and the coil spring can be smoothly expanded and contracted.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a side view of a motorcycle equipped with a vehicle drum brake device according to the present invention. The motorcycle 10 includes a front fork 13 attached to a head pipe 12 of a body frame 11, a front wheel 14 attached to the front fork 13, a handle 15 connected to the front fork 13, and a swing attached to a rear upper portion of the body frame 11. Unit 16, a rear wheel 17 attached to the rear part of the swing unit 16, a seat 18 arranged above the rear part of the body frame 11, a power unit 19 arranged below the body frame 11, and a body cover 21 covering the body frame 11. And a scooter type motorcycle having a main structure.

The body frame 11 lowers the down tube 22 from the head pipe 12, extends the center tube 23 backward from the middle of the down tube 22, and a pair of left and right rear pipes 24, 24 from the rear end of the center tube 23.
(24 not shown on one side)
A pair of left and right under pipes 25, 25 from the middle of 2
This is a cradle-type body frame in which the lower ends of these under pipes 25, 25 are extended rearward, and the rear ends are extended upward and joined to the left and right rear pipes 24, 24.

The power unit 19 is a unit composed of an engine 26 and a transmission 27, and is a water-cooled unit in which a cylinder head 28 of the engine 26 is disposed toward the front of the vehicle body. Specifically, the engine 26 is a front-inclined engine in which a cylinder axis (not shown) is inclined at an angle (for example, about 15 °) with respect to a horizontal line, and the cylinder head 28 is inclined forward.

In the figure, 32 is a front fender, 33 is a headlamp, 35 is a handle cover, 36 is a handle grip, 37 is an operation handle, 38 is a mirror, 39 is a rear suspension, 41 is a fuel tank, and 42 is an engine cooling. A radiator 43 is an air cleaner, 44 is a tail lamp, 45 is a rear fender, 46 is a luggage box, 47 is a battery, and 50 is a vehicle drum brake device (hereinafter abbreviated as “drum brake device 50”).

FIG. 2 is a side view of the vehicle drum brake device according to the present invention. In the drum brake device 50, a brake unit 51 as a drum brake is mounted on a brake housing 52, a brake arm 53 is rotatably mounted on the brake housing 52 via a support shaft 66, and a cable 54 is connected to a distal end 53a of the brake arm 53.
And the other end of the cable 54 is connected to the operation handle 37.
To the brake housing 51 and the brake arm 53
A coil spring 55 for returning the brake arm 53 is provided between the coil spring 55 and the rod 56 for restricting the longitudinal fall of the coil spring 55.

FIG. 3 is a side view of a brake unit of the vehicle drum brake device according to the present invention. The brake unit 51 is an expanded drum brake unit. More specifically, brake shoes 59, 59 attached to the brake housing 52 with anchor pins 58, a cam 61 for expanding the diameter of these brake shoes 59, 59, and a brake shoe 59 Return springs 62, 62 for reducing the diameter of
And a brake drum 63 attached to the rear wheel 17 (see FIG. 2). The cam 61 extends from a support shaft 66 as a swing center of the brake arm 53, as will be described later. The brake shoes 59, 59 have brake pads 64, 64, respectively.

That is, the brake unit 51 swings the brake arm 53 as shown by a white arrow a.
By rotating the cam 61 as shown by a white arrow b and expanding the diameter of the brake shoes 59, 59, the brake pad 6 is rotated.
The braking is performed by pressing the inner peripheral surface 63a of the brake drum 63 with the brake wheels 4, 64.

FIG. 4 is a detailed view around the brake housing of the vehicle drum brake device according to the present invention. The brake housing 52 includes a mounting recess 52a for mounting the brake unit 51, a support 52b for supporting the brake arm 53, a support hole 52c for supporting the cable 54,
A supporting recess 52d for supporting the other end 55b of the coil spring 55, and a through hole 5 penetrating the one end 56a of the rod 56;
2e.

The brake arm 53 has a support shaft 66 as a swing center fitted to the support portion 52b of the brake housing 52, and a mounting portion 67 for mounting the cable 54 at a tip 53a. A bracket 68 for receiving one end 55a of the coil spring 55 is attached between the tip 66 and the tip 53a and near the tip 53a. 68a is a bracket 68
A coil spring receiving surface 68b is a rod supporting portion of the bracket 68.

The cable 54 includes a wire 7 connected to a tube 71.
2, and the wire 72 has an adjusting screw shaft 73 attached to the connection side of the brake arm 53. 74 is a support hole 52 of the brake housing 52
Reference numeral 75 denotes a telescopic tube that covers the connection side of the wire 72 to the brake arm 53, and reference numeral 76 denotes a wire bush attached to the adjustment screw shaft 73 side.
The rod 56 has one end 56a formed in a straight shape,
The other end 56b is formed in an L-shape.
6a is inserted into the through hole 52e of the brake housing 52, and the other end 56b is connected to the rod support portion 68b of the bracket 68.
It is fitted to.

That is, in the drum brake device 50, a brake arm 53 is swingably attached to a brake housing 52, and a distal end 53a of the brake arm 53 is provided.
In the vehicle drum brake device 50 that activates the brake unit 51 by pulling the
A coil spring 55 that pushes the brake arm 53 in the direction of opening the brake unit 51 between the support shaft 66 of the brake arm 53 and the distal end 53a and at a position close to the distal end 53a.
And the other end 55b of the coil spring 55 is applied to the brake housing 52, and a rod 56 for restricting the coil spring 55 from falling in the longitudinal direction is inserted into the coil spring 55.

The operation of the above-described drum brake device 50 will now be described. FIGS. 5A to 5C are explanatory views of the operation of the vehicle drum brake device according to the present invention.
(B) shows a comparative example, and (c) shows an example.
1A, a drum brake device 100 includes a coil spring 10 for releasing an active brake between a brake arm 101 and a brake housing 102.
At this time, one end 103a of the coil spring 103 is applied to a position between the swing center 101a and the tip end 101b of the brake arm 101 and closer to the swing center 101a.
The other end 103b of 03 is brought into contact with the brake housing 102.

However, in the drum brake device 100, one end 103a of the coil spring 103 is connected to the swing center 1
The coil spring 103 is used in a range where the swing amount of the brake arm 103 is smaller than that of the distal end portion 101b because the coil spring 103 is located closer to 01a. Accordingly, since the amount of deflection of the coil spring 103 is small, it is necessary to use a high-grade (high-precision) coil spring 103 in which the spring stroke and the spring load are favorably proportioned.
That is, it causes a cost increase of the drum brake device 100.

In (b), the drum brake device 11
0 is the brake arm 111 and the brake housing 11
2, a coil spring 113 for releasing the brake in the operating state is arranged.
One end 113a of the coil spring 113 is applied between the swing center 111a of the brake arm 111 and the front end 111b and at a position close to the front end 111b, and the other end 113b of the coil spring 113 is connected to the brake housing 112.
It is intended to be applied to.

In the drum brake device 110, the one end 113a of the coil spring 113 is positioned closer to the front end portion 101b, so that the coil spring 113 can be used by sufficiently bending it. Therefore, a relatively low cost coil spring 113 can be used. However, since the length of the coil spring 113 increases, the coil spring 113 may fall down in the longitudinal direction.

In (c), the drum brake device 50
Has a coil spring 55 disposed between the brake arm 53 and the brake housing 52 for releasing the brake in the operating state. At this time, the coil spring 55
Of the coil spring 55 between the support shaft 66 of the brake arm 53 and the distal end 53a and near the distal end 53a.
3 and a rod 56 for restricting the coil spring 55 from falling down in the longitudinal direction is inserted into the coil spring 53.

Therefore, one end 55 of the coil spring 55
a is applied between the support shaft 66 of the brake arm 53 and the distal end portion 53a and near the distal end portion 53a, and the rod 56 is inserted into the coil spring 55 to restrict the coil spring 55 from falling in the longitudinal direction. Thus, the coil spring 55 having a long coil length can be used. As a result, the relatively low-cost coil spring 55 can be used, and a rise in the manufacturing cost of the drum brake device 50 can be suppressed. Further, the drum brake device 50 can easily make the overall length of the coil spring 55 long. That is, by making the coil spring 55 long, a change in the load of the coil spring 55 during the brake operation can be suppressed to a small value.

Here, L1 is a support shaft 66 (swing center).
L2 is the horizontal distance from one end 55a of the coil spring 55 to the tip 53a of the brake arm 53.

FIG. 6 is a side view of a brake unit of another embodiment of the vehicle drum brake device according to the present invention. Note that the same parts as those of the drum brake device are denoted by the same reference numerals, and detailed description thereof will be omitted. A drum brake device 80 is provided in a vehicle drum brake device 50 in which a brake arm 53 is attached to a brake housing 52 so as to be swingable, and a distal end portion 53a of the brake arm 53 is pulled by a cable 54 so as to activate the brake unit 51. One end 55a of a coil spring 55 that pushes the brake arm 53 in the opening direction of the brake unit 51 is applied to a position between the support shaft 66 of the brake arm 53 and the tip 53a and near the tip 53a, and the other end of the coil spring 55 55b is applied to the brake housing 52, and a rod 56 for restricting the coil spring 55 from falling down in the longitudinal direction is inserted into the coil spring 55.
The coil spring receiving surface 81a of the bracket 81 provided on the brake arm side has a spherical convex shape.

That is, in the drum brake device 80, the coil spring receiving surface 81 a and the one end 55 a of the coil spring 55
And the coil spring 55 can be smoothly expanded and contracted. As a result, the drum brake device 80 with a good operation feeling can be realized.

In the embodiment, as shown in FIG. 4, the other end of the coil spring 55 is attached to the brake housing 52. However, the present invention is not limited to this.
What is necessary is just to stop the other end 55b of 5 at the vehicle body side such as the rear part of the crankcase of the engine.

[0031]

According to the present invention, the following effects are exhibited by the above configuration. According to a first aspect of the present invention, one end of a coil spring that pushes the brake arm in a direction to release the brake is applied between the swing center of the brake arm and the tip and a position near the tip, and the other end of the coil spring is applied to the brake housing. Since the rod for restricting the longitudinal fall of the coil spring is inserted into the contact spring, a coil spring having a long coil length can be used.
As a result, a relatively low-cost coil spring can be used, and a rise in the manufacturing cost of the drum brake device can be suppressed.

According to a second aspect of the present invention, the coil spring receiving surface formed on the brake arm side has a spherical convex shape, so that a slip can be generated between the coil spring receiving surface and one end of the coil spring when the brake arm swings. Thus, the coil spring can be smoothly expanded and contracted. As a result, a vehicle drum brake device with a good operation feeling can be realized.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle equipped with a vehicle drum brake device according to the present invention.

FIG. 2 is a side view of the vehicle drum brake device according to the present invention.

FIG. 3 is a side view of a brake unit of the vehicle drum brake device according to the present invention.

FIG. 4 is a detailed view around a return spring of the vehicle drum brake device according to the present invention.

FIG. 5 is an explanatory view of the operation of the vehicle drum brake device according to the present invention.

FIG. 6 is a side view of another embodiment of the vehicle drum brake device according to the present invention.

[Explanation of symbols]

50: drum brake device, 51: drum brake (brake unit), 52: brake housing, 53:
Brake arm, 53a ... tip, 55 ... coil spring, 55a ... one end, 55b ... other end, 56 ... rod, 6
6 ... Swing center (support shaft), 68a, 81a ... Coil spring receiving surface.

Continued on the front page (72) Inventor Atsuhiko Shinohara 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3J058 AA03 AA07 AA13 AA17 AA24 AA30 AA37 BA61 CC08 CC66 CC76 CD27 FA02

Claims (2)

[Claims] 1. A drum brake device for a vehicle, wherein a brake arm is swingably mounted on a brake housing, and a tip end of the brake arm is pulled by a cable to activate a drum brake. One end of a coil spring that pushes the brake arm in the direction to release the brake between the tip and the position near the tip is applied, and the other end of the coil spring is applied to the brake housing. A drum brake device for a vehicle, wherein a rod for restricting the vehicle from falling is inserted. 2. The drum brake device for a vehicle according to claim 1, wherein a coil spring receiving surface formed on the brake arm side has a spherical convex shape.