JPH08312702A - Automatic clearance adjuster for drum brake - Google Patents

Abstract

PURPOSE: To easily attach an adjusting spring of an automatic clearance adjuster for a drum brake. CONSTITUTION: An adjusting spring 60 is attached by locking one side of the adjusting spring 60 on a hooking piece 42 projecting rearward from the engaging part of an adjusting lever 40 rotatably supported to the rear end of a connecting member 50 so provided as to be moved together with a piston and whose rear end is engaged with the adjusting lever 40, and rotating the adjusting lever 40 centered on the engaging part of the adjusting lever 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic clearance adjusting device for a drum brake.

[0002]

2. Description of the Related Art Conventionally, a brake cylinder has been assembled,
It is necessary to attach and detach the adjusting spring to disassemble it. For the purpose of easily attaching and detaching this adjusting spring, the actual flat opening 6-1873
No. 9 publication is disclosed. According to this, the end portion of the adjusting spring 3 locked to the receiving piece 2 is screwed into the insert 13 to be coupled, the insert 13 is inserted into the hole 2a of the receiving piece 2, and the snap ring 20 is used to prevent it from coming off. The adjustment spring 3 is attached to the receiving piece 2 so that the adjustment spring 3 can be easily removed and attached.

[0003]

However, there are the following problems. <A> A pair of inserts 1 attached to both ends of the adjusting spring 3.
3 and 14 are required respectively, and the insert 13 on the left side has a structure in which bolts are screwed in, and the number of parts is large and the structure is complicated. For example, the snap ring 20 that prevents the bolt 15 from coming off the hole 2a of the receiving piece 2 is also required. <B> To adjust the adjusting spring 3 to the set load, use the bolt 1
It is necessary to pinch 5 with a tool and rotate it, and this operation becomes complicated. (The above-mentioned codes are those of Japanese Utility Model Laid-Open No. 6-18739.)

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic gap adjusting device for a drum brake, which has a simple structure and is easy to install and remove the adjusting spring.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a cylinder body mounted on a back plate, a piston slidably fitted in the cylinder body, and a front end outside the cylinder rotatably fitted in the piston. An adjusting nut having an adjusting tooth on its part, an adjusting bolt screwed on the adjusting nut to support the brake shoe at the front end, and a rotatably supported on the cylinder body with a support shaft to support the adjusting tooth on one side. An adjusting lever having an adjusting claw that rotatably engages only with the connecting member, a connecting member that is provided so as to move integrally with the piston, and has a rear end engaged with the adjusting lever, and is wound around the connecting member and connected. A adjusting spring that is stretched between the member and the adjusting lever, and the adjusting tooth is rotated by the adjusting claw by the rotation of the adjusting lever, and the adjusting bolt screwed into the adjusting nut is screwed out and the shoe gap is provided. In an automatic gap adjusting device for a drum brake that automatically adjusts, one of the adjusting springs is hooked on a hooking piece projecting rearward from an engaging portion of the adjusting lever pivotally supported by a rear end of the connecting member. Then, the automatic gap adjusting device for the drum brake is characterized in that the adjusting lever is rotated around the engaging portion of the adjusting lever to tension the adjusting spring.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. <B> Outline of Drum Brake (FIG. 5) This device can be applied to a drum brake having various structures. For example, the device is applied to a dual-to-leading (D2L) type drum brake as shown in FIG. In this case, the pair of brake cylinders 10 and 10 are arranged on the back plate 20, and the operation of the brake cylinders 10 and 10 increases or decreases the interval between the pair of brake shoes 21 and 21 to increase the inner circumference of the drum of the wheel. The brake operation is performed on the surface. A pair of brake shoes 21,
21 is held on the back plate 20 by shoe hold springs 22 and 22, and the shoe return spring 2
It is urged in the direction in which the interval is reduced at 3, 23. A gap adjusting device for the drum brake is arranged in the brake cylinders 10 and 10 to automatically adjust the gap between the brake shoes 21 and 21 and the inner peripheral surface of the drum.

<B> Piston, Adjustment Nut, Adjustment Bolt (FIG. 4) In the brake cylinder 10, the cylinder body 11 is attached to the back plate 20 with an attachment bolt or the like (not shown), and the piston 12 is slidably fitted therein. Have been combined. Note that, for convenience of description, the outside direction of the brake cylinder 10 of the piston 12 will be referred to as the front part and the inside direction will be referred to as the rear part.

An adjusting nut 30 is rotatably fitted in the piston 12, and an adjusting bolt 31 is screwed into the adjusting nut 30. An engaging groove 32 is formed in the front end portion of the adjusting bolt 31, and the brake shoe 21 is supported.
Therefore, even if the adjustment nut 30 rotates, the adjustment bolt 31
Is suppressed, and the adjustment bolt 31 is screwed into or screwed into the adjustment nut 30. Adjustment teeth 33 are integrally attached to the outside of the brake cylinder at the front end of the adjustment nut 30. As a method of integrally mounting, various methods such as welding, adhesion, caulking, press fitting, and odd-shaped fitting are possible. When the adjustment teeth 33 rotate, the adjustment nut 30 rotates, and the adjustment bolt 31 is screwed out or screwed in depending on the rotation direction.

The brake cylinder 10 is additionally provided with dust boots 13, 14, a washer 15, a piston cup 16, a feeling block 17, a spring 18, an anchor piston 19, and the like.

<C> Adjustment Lever, Connecting Member (FIGS. 1 to 4) The adjustment lever 40 is rotatably and swingably attached to the cylinder body 11 by means of a support shaft 44 such as a stepped bolt. That is, the adjustment lever 40 is attached to the support shaft 44 so that the adjustment lever 40 can rotate about the support shaft 44 as a fulcrum and the end portion of the adjustment lever 40 can move up and down. An adjusting claw 41 is provided at the front end portion of the adjusting lever 40 and is engaged with the adjusting tooth 33. The movement of the adjusting claw 41 causes the adjusting tooth 33 to rotate only in one direction.

The connecting member 50 has an annular front end portion 52 integrally attached to the piston 12. As the method of integrally mounting, various methods can be used as in the case of the adjusting nut 30. The connecting member 50 moves integrally with the piston 12, and a rear end portion 53 obtained by extending a part of the front end portion 52 is pivotally supported by an engaging portion 45 of the adjusting lever 40 and an engaging pin 61.

In this engaging means, for example, the engaging pin 61 is inserted into the engaging holes 54 and 47 formed in the connecting member 50 and the adjusting lever 40, and the retaining ring 62 is attached to prevent the stopper from coming off. You Notches 55 and 48 are provided in at least one of the engaging holes 54 and 47 to connect the connecting member 50 and the adjusting lever 40.
Engage separably. Instead of the notches 55 and 48, long holes may be used as long as they are movable with respect to each other.
Alternatively, with respect to the engaging means of the adjusting lever 40 and the connecting member 50, the convex portion formed on the adjusting lever 40 and the concave portion formed on the connecting member 50 are engaged so as to be rotatably supported, or the unevenness is reversed. May be engaged with.

A hooking piece 42 is provided at a predetermined distance d from the engaging hole 47 of the adjusting lever 40. The hooking piece 42 has a structure in which the rear end hook 64 of the adjusting spring 60 can be hooked, and is formed by bending the rear end portion 46 of the adjusting lever 40, for example.

<D> Adjusting Spring (FIGS. 1 to 3) The adjusting spring 60 exerts a force for rotating the adjusting lever 40 in the direction of arrow B in FIG. To do. The front end hook 63 of the adjusting spring 60 is locked to the hook stopper 51 of the front end portion 52 of the connecting member 50, and the rear end hook 64 is locked to the hooking piece 42 of the adjusting lever 40.
It is stretched between these. Locking piece 42 of adjusting lever 40
Is protruded rearward from the engaging hole 47 at the rear end portion 46 of the adjusting lever 40 and is provided at a predetermined distance d from the engaging hole 47.

<E> Attaching and removing the adjusting spring (FIGS. 1 and 2) When attaching the adjusting spring 60, the front end hook 63 of the adjusting spring 60 is hooked to the connecting member 50 as in the state of FIG. Then, the rear end hook 64 of the adjusting spring 60 is locked to the hooking piece 42 of the adjusting lever 40. Then, the adjusting lever 40 is rotated around the engaging pin 61 in the direction A to tension the adjusting spring 60, and the adjusting lever 40 can be rotated with respect to the cylinder body 11 by passing the supporting shaft 44 through the supporting shaft hole 43. Install on.

When removing the adjusting spring 60, the support shaft 44 of the adjusting lever 40 is removed and rotated around the engaging pin 61. As a result, the hooking piece 42 of the adjusting lever 40 moves in the direction of the front end portion 52 of the connecting member 50, that is, in the direction in which the adjusting spring 60 easily comes off. In this state, the front end and the rear end hooks 63 and 64 of the adjusting spring 60 are removed from the hook stopper 51 of the connecting member 50 and the hooking piece 42 of the adjusting lever 40, respectively.

<F> Operation of the automatic gap adjusting device for the drum brake (FIGS. 1 to 4) When the piston 12 slides outward from the brake cylinder 10 and the brake shoe 21 is expanded to the circumferential surface of the drum,
The connecting member 50 fixed to the piston 12 also moves in the front end direction, and a force acts on the rear end portion 46 of the adjusting lever 40 via the engaging pin 61, so that the adjusting lever 40 uses the support shaft 44 as an axis. Rotate in the right direction (direction B in FIG. 2). By this rotation, the adjusting claw 41 of the adjusting lever 40 moves in the direction in which the adjusting claw 41 engages with the crest of the adjusting tooth 33 and rotates.

If the gap between the brake shoe 21 and the drum is large, the adjusting claw 41 rotates the adjusting tooth 33.
As a result, the adjusting bolt 31 is screwed out, and the adjustment is automatically performed so as to reduce the gap between the brake shoe 21 and the drum. When the brake is released, when the piston 12 returns to the original position, the adjusting lever 40 rotates in the direction opposite to the B direction and the adjusting claw 41 returns to the original position over the mountain of the adjacent adjusting teeth 33. .

If the gap between the brake shoe 21 and the drum is appropriate, the adjusting pawl 41 does not go over the ridge of the adjusting tooth 33, so that the adjusting tooth 33 does not rotate. In addition, although the case where the adjusting teeth 33 of the adjusting nut 30 are rotated by the adjusting claw 41 of the adjusting lever 40 to automatically adjust when the piston 12 advances, the same automatic adjustment may be performed when the piston moves backward.

When a high hydraulic pressure is applied to the piston 12 or a thrust force larger than a predetermined value is exerted by the reaction force from the brake shoe 21, the torque for rotating the adjusting nut 30 becomes large and the biasing force of the adjusting spring 60 causes the adjusting nut 60 to rotate. Adjustment lever 4
The adjustment tooth 33 of the adjustment nut 30 cannot be rotated by rotating 0. At this time, the piston 12 and the connecting member 50 advance, but the adjusting lever 40 does not rotate. Therefore, the engaging hole 54 ′ of the rear end portion 53 of the connecting member 50 and the engaging hole 4 of the adjusting lever 40.
7 are separated. This is to prevent over-adjustment by stopping the automatic interval adjustment device when the hydraulic pressure is high or the brake load is large.

<G> Example in which the connecting member 50 is divided (FIGS. 6 and 7) The connecting member 50 can be divided into a connecting plate 501 and a strut 502. In that case, the connecting plate 501 is integrally attached to the piston 12. As the method of integrally mounting, various methods can be used as in the case of the adjusting nut 30.

For example, as shown in FIG. 7, the connecting plate 501 has a hook portion 51 'formed by extending a part of an annular shape in the outer diameter direction, and a window hole 56 is bored at the base portion thereof. Strut 5
Reference numeral 02 is a substantially rectangular shape, and the front end is stepped to narrow the width to form an insertion portion 57 and a contact surface 58, which is inserted into the window hole 56,
The contact plate 501 abuts at 8. The rear end portion 53 'of the strut 502 has an engaging hole 54' and a notch portion 55 if necessary.
'Or a long hole is formed.

Rear end of strut 502 and adjusting lever 40
The rear portions are engaged with each other via engagement pins 61. The front end hook 63 of the adjusting spring 60 is hooked to the hook stopper 51 ′ of the connecting plate 501, and the rear end hook 64 is hooked to the hooking piece 42 of the adjusting lever 40, and the strut 5 penetrating the coil portion thereof.
The mounting length is determined by 02. Since the connecting plate 501 and the struts 502 can be formed as separate members, material removal can be improved.

<G> Other Embodiments Besides the dual-to-leading (D2L) type, for example, the present invention can be applied to a two-leading (2L) type drum brake. In this case, the anchor piston 19 of the double-sided opening cylinder in FIG. 4 may be eliminated and replaced with a single-sided opening cylinder.

[0025]

According to the present invention, the following effects can be obtained. <A> The adjustment spring can be easily attached and detached without using a tool. <B> The adjustment spring can be attached and detached easily without adding any parts. <C> By dividing the connecting member, material removal is improved,
Waste can be saved.

[Brief description of drawings]

FIG. 1 is a partially omitted front view showing a mounting state of an adjustment spring.

[Fig. 2] Front view of the brake cylinder

FIG. 3 is a partially enlarged view of an adjusting lever and a connecting member.

FIG. 4 is a partial sectional plan view of a brake cylinder.

[Fig. 5] Front view of the drum brake

FIG. 6 is a partial cross-sectional plan view in which the connecting member is divided into a connecting plate and a strut.

FIG. 7 is a partially enlarged view of a connecting plate and a strut.

Claims (1)

[Claims] 1. A cylinder body attached to a back plate, a piston slidably fitted in the cylinder body, and an adjusting nut rotatably fitted in the piston and having adjusting teeth at a front end portion outside the cylinder. An adjusting bolt which is screwed to the adjusting nut and supports a brake shoe at a front end thereof, and an adjusting bolt which is rotatably supported by a supporting shaft on the cylinder body and rotatably engages the adjusting tooth with only one side. An adjusting lever having a claw, a connecting member provided so as to move integrally with the piston and having a rear end engaged with the adjusting lever, and wound around the connecting member and stretched between the connecting member and the adjusting lever. A drum brake including an adjusting spring, and rotating the adjusting lever to rotate the adjusting teeth by the adjusting claw, and an adjusting bolt screwed into the adjusting nut is screwed out to automatically adjust the shoe gap. In the automatic gap adjusting device, one of the adjusting springs is hooked on a hooking piece projecting rearward from an engaging portion of the adjusting lever pivotally supported by the rear end of the connecting member, and the adjusting lever is engaged. An automatic gap adjusting device for a drum brake, wherein an adjusting spring is stretched by rotating an adjusting lever around the joint.