JP3458167B2 - Automatic clearance adjustment device for drum brake - Google Patents

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. 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 so that only one adjusting tooth is provided. An adjusting lever having an adjusting claw rotatably engaged with the connecting member, a connecting member provided so as to move integrally with the piston and having a rear end engaged with the adjusting lever, and a connecting member wound around the connecting member. And an adjustment spring stretched between the adjustment levers, and the adjustment teeth are rotated by the adjustment claws by the rotation of the adjustment lever, and the adjustment bolt screwed into the adjustment nut is screwed out to allow the shoe clearance. In the clearance automatic adjustment device for a drum brake for automatically adjusting the connecting member is composed of a coupling plate which is fixed to the piston, the strut was installed between the engaging portion of the coupling plate and the adjusting lever, strap
Hook the adjustment spring wrapped around the connection between the connecting plate and the adjustment lever.
Centering around the engaging position of the connecting plate and strut
The strut engaged with the adjustment lever and the adjustment lever.
When the adjustment spring that has stopped is rotated integrally, the adjustment spring
Of the connecting plate and strut so that
The latching position of the adjusting spring engaging position and the connecting plate, and wherein the kite is offset radially outwardly of the cylinder, in a gap automatic adjuster for a drum brake. further
The present invention is a cylinder body mounted on a back plate.
And a piston that is slidably inserted in the cylinder body.
Ton and rotatably fitted in the piston and outside the cylinder
Adjusting nut with adjusting teeth at the end and screwing on the adjusting nut.
Adjustment bolt that supports the brake shoe at the front end of the mating
A support shaft is rotatably supported on the cylinder body.
Adjustment so that the adjusting tooth is rotatably engaged with only one side.
Adjusting lever with pawl and move integrally with the piston
And the rear end of which is engaged with the adjusting lever
Between the connecting member and the adjusting lever wound around the connecting member
A tension adjustment spring is provided, and when the adjustment lever is rotated,
Rotate the adjusting tooth with the adjusting claw and screw it on the adjusting nut.
The matching adjustment bolt is screwed out to automatically adjust the shoe gap.
In the automatic gap adjusting device for drum brakes, the connection
The member is a connecting plate fixed to the piston and the connecting plate.
And a strut installed between the engaging portion of the adjusting lever
And the adjustment spring wound on the strut,
And the adjustment lever, and connect the connecting plate and strut
The strap engaged with the adjustment lever is centered on the engagement position.
Unit and the adjustment spring hooked on the adjustment lever
When the adjustment spring is extended,
If the engaging position of the connecting plate and the strut and the connecting plate are adjusted,
Set the locking position of the bed in the outer diameter direction of the cylinder and the cylinder.
A drum block characterized by being axially offset
It is in the automatic rake clearance adjustment device.

[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. 1) 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 comprises a connecting plate 501 and struts 502. The connecting plate 501 is the piston 1
It is attached integrally to 2. This integral mounting method is
Various methods are possible as in the case of the adjusting nut 30. The connecting plate 501 has, for example, as shown in FIG. 4, a part of an annular shape extended in the outer diameter direction to form a hook stopper 51, and a window hole 52 is bored at the base portion thereof. The strut 502 has a substantially rectangular shape and has a stepped front end to narrow the width to form an insertion portion 53 and a contact surface 54, which is inserted into the window hole 52 and abuts the connecting plate 501 at the contact surface 54. The rear end of the strut 502 and the engaging portion 42 formed by bending the rear portion of the adjusting lever 40 are in contact with and engaged with each other by the urging force of the adjusting spring 60. Adjustment spring 6
The front end hook 61 of 0 is the hook stopper 51 of the connecting plate 501.
Further, the rear end hook 62 is hooked on the engaging portion 42 of the adjusting lever 40, and the mounting length is determined by the strut 502 penetrating the coil portion thereof. Since the connecting plate 501 and the struts 502 can be formed as separate members, material removal can be improved.

<D> Adjusting Spring (FIGS. 1 to 3) The adjusting spring 60 connects the connecting plate 501, the strut 502 and the engaging portion 42 of the adjusting lever 40, and applies a force to the adjusting lever 40 to adjust the adjusting lever 40. The claw 41 is brought into contact with the adjustment tooth 33. The adjusting spring 60 connects the front end hook 61 to the connecting plate 501.
The front end of the adjusting lever 40 is engaged with the hook stopper 51, the rear end hook 62 is engaged with the engaging portion 42 of the adjusting lever 40, and is stretched between them.

<E> Attaching and removing the adjusting spring (FIGS. 1 and 2) When attaching the adjusting spring 60, the strut 502 engaged with the adjusting lever 40 and the adjusting spring 60 are integrally formed in FIG.
By rotating the adjusting spring 60 in the direction of arrow A, the adjusting spring 60 is attached while being extended by the offset between the engaging position of the strut 502 with respect to the connecting plate 501 and the hooking position of the adjusting spring 60. When removing the adjustment spring 60, the adjustment spring 60 is removed while being contracted by rotating the adjustment spring 60 in the direction opposite to the arrow A direction in FIG.

<F> Operation of the automatic gap adjusting device for the drum brake (FIGS. 1 to 3) 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 direction, and a force acts on the rear end portion of the adjusting lever 40 via the engaging portion 42, and the adjusting lever 40 moves right around the support shaft 44. Direction (direction B in FIG. 3). 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. 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 is performed when the piston 12 retracts. Good.

When a high hydraulic pressure is applied to the piston 12 or a thrust force larger than a predetermined value is applied by the reaction force from the brake shoe 21, the torque for rotating the adjusting nut 30 becomes large, and the urging force of the adjusting spring 60 causes the adjusting nut 30 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, so the strut 50
The rear end of 2 and the engaging portion 42 of the adjusting lever 40 are separated from each other. 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> 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 of the double-sided opening cylinder in FIG. 1 may be eliminated and replaced with a single-sided opening cylinder.

[0019]

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 forming the connecting member with the connecting plate and the strut, the material removal can be improved and waste can be eliminated.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional plan view showing a state in which an adjustment spring is attached.

FIG. 2 is a plan view showing a state in which an adjusting spring is attached.

[Fig. 3] Front view of the brake cylinder

FIG. 4 is a partially enlarged view of a connecting plate and a strut.

[Fig. 5] Front view of the drum brake

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Sho 61-182428 (JP, U) Rikai Hei 7-1340 (JP, U) Rikai Hei 6-18739 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) F16D 65/56

Claims (2)

(57) [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 that is screwed to the adjusting nut and supports a brake shoe at a front end thereof; and an adjusting claw that is rotatably supported by a supporting shaft on the cylinder body and that rotatably engages the adjusting tooth only to one side. An adjusting lever, a connecting member provided so as to move integrally with the piston and having a rear end engaged with the adjusting lever, and an adjusting member wound around the connecting member and stretched between the connecting member and the adjusting lever. A drum brake that includes a spring and rotates the adjustment lever to rotate the adjustment teeth by the adjustment claw, and an adjustment bolt screwed into the adjustment nut is screwed out to automatically adjust the shoe gap. In the automatic gap adjusting device, the connecting member includes a connecting plate fixed to the piston, and a strut installed between the connecting plate and the engaging portion of the adjusting lever, and the adjusting spring wound around the strut. The connecting plate and adjusting lever
Looped in between around the engaging position of the coupling plate and the struts, adjusting
The strut engaged with the lever and the adjustment hooked on the adjustment lever.
When the adjusting spring and the adjusting spring are rotated together, the adjusting spring
Engagement position of the connecting plate and the strut so that the extension amount is obtained.
And the connecting plate and the locking position of the adjustment spring, and wherein the kite is offset radially outwardly of the cylinder, the gap automatic adjuster for a drum brake. 2. A cylinder attached to a back plate.
The body and the cylinder body are slidably inserted into the cylinder body.
Piston and rotatably fitted on the piston and outside the cylinder
Adjusting nut having adjusting teeth at the front end of the
Adjusting bolt that is screwed onto and supports the brake shoe at the front end
And rotatably support the spindle on the cylinder body.
Is held to rotatably engage the adjusting tooth on one side only
Adjustment lever with adjustment claw and the piston integrally
Movable and rear end engaged with said adjusting lever
Connecting member and connecting member wound around the connecting member and adjusting lever
Rotation of the adjusting lever with an adjusting spring stretched between
Rotate the adjusting tooth with the adjusting claw by
Automatically adjust the shoe clearance by adjusting bolt is out screw screwed into the
In the clearance automatic adjustment device for a drum brake that, the connecting member is composed of a coupling plate which is fixed to the piston, the strut was installed between the engaging portion of the coupling plate and the adjusting lever, wrapped strut Connect the adjustment spring to the connecting plate and adjustment lever.
Looped in between around the engaging position of the coupling plate and the struts, adjusting
The strut engaged with the lever and the adjustment hooked on the adjustment lever.
When the adjusting spring and the adjusting spring are rotated together, the adjusting spring
Engagement position of the connecting plate and the strut so that the extension amount is obtained.
And the position where the connecting plate and the adjusting spring are hooked,
Offset in the outer diameter direction and the axial direction of the cylinder.
An automatic gap adjustment device for drum brakes , characterized by