JPH08338462A - Brake cylinder with automatic clearance adjuster - Google Patents

Abstract

PURPOSE: To provide a brake cylinder with an automatic clearance adjuster that is able to secure a stable shoe clearance. CONSTITUTION: In this brake cylinder with an automatic clearance adjuster which rotates an adjusting tooth 33 through an adjusting claw 41 by the rotation of an adjusting lever 40, drawing out an adjusting bolt being screwed in an adjusting nut, through which a shoe clearance is automatically adjusted, a latching pant 42 of the adjusting lever 40 and an adjusting spring 60 is offset to the side of a fulcrum shaft 44 of this adjusting lever 40 to an engaging part 45 between the adjusting lever 40 and a connecting member 50, while turning effort in the return direction is energized to the adjusting level 40, and respective rear end sides between the fulcrum shaft 44 and a fulcrum shaft hole 43 of the adjusting lever 40 are made contact with each other.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a wheel brake cylinder with an automatic clearance adjusting device has been disclosed, for example, in Japanese Utility Model No. 61-16033
According to the publication No. 5, the adjustment lever 47 is attached to the cylinder body 4
A gap is provided between the outer circumference of the shaft 48 pivotally attached to 0 and the inner circumference of the hole 47f of the adjusting lever 47 through which the shaft 48 passes. When the piston 42 slides to the outside of the cylinder body 40, this clearance causes the adjustment lever 47 to be frictionally generated between the claw 47b and the tooth 45c of the ratchet wheel portion 45b so as to be integrated with the ratchet wheel portion 45b. It is an amount that allows axial movement, and is set to be 2 to 4 times the shoe clearance adjustment amount that occurs when the adjustment nut 45 rotates by one tooth of the ratchet wheel 45b.

[0003]

However, there are the following problems. <B> The gap δ ₃ provided between the hole 47f of the adjusting lever 47 and the shaft 48 becomes a loss stroke of the adjusting lever 47 during brake operation, and as a result, the ratchet wheel portion 45b is rotated at a small operating rotation angle of the adjusting lever 47. Since it is necessary to form the teeth 45c of the ratchet wheel 45b finely or to increase the lever ratio of the adjusting lever 47, there is a problem in processing and layout of the teeth 45c. <B> It is not possible to specify in which direction around the shaft 48 the gap δ ₃ generated between the hole 47f of the adjusting lever 47 and the shaft 48 is deviated (especially when it is subjected to vibration or the like, it is freely displaced). Conversely, it does not have a function of positively biasing the gap in one direction. Therefore, the return position of the adjusting lever 47 is not fixed, and the pawl 47b of the adjusting lever 47 and the ratchet wheel 4 are not fixed.
The engagement position of the tooth 5c of 5b varies. As a result, the automatic clearance adjustment becomes over-adjusted or not adjusted, and a stable shoe clearance cannot be obtained. <C> It is necessary to control the diameter of the hole 47f of the adjusting lever 47 and the diameter of the shaft 48 to predetermined values to ensure a constant gap. Moreover, since it is necessary to set the shoe clearance adjustment amount to 2 to 4 times, the management is further complicated. (The above codes are those of Japanese Utility Model Laid-Open No. 61-160335).

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a brake cylinder with an automatic clearance adjusting device which can obtain a stable shoe clearance.

[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 between the connecting member and the adjusting lever. A tension adjusting spring is provided, and while the adjustment lever is rotated, the adjustment teeth are rotated by the adjustment claw, and an adjustment bolt screwed into the adjustment nut is screwed out to automatically adjust the shoe gap. In the brake cylinder with automatic adjustment device, with respect to the engaging portion of the coupling member and the adjusting lever,
The adjustment lever and the hooking portion of the adjustment spring are offset to the support shaft side of the adjustment lever, and the rear end sides of the support shaft and the support shaft hole of the adjustment lever are brought into contact with each other, respectively.
It is in the brake cylinder with automatic clearance adjustment device.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. <B> Outline of Drum Brake (FIG. 6) This device is applicable to a drum brake having various structures, for example, 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> Brake Cylinder (FIG. 3) In the brake cylinder 10, a cylinder body 11 is attached to a back plate 20 or an axle side member (not shown) with a mounting bolt or the like (not shown), and a piston 12 is slidable therein. It is fitted. 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.

<C> Piston, adjusting nut, adjusting bolt (FIG. 3) 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 adjusting nut 30 rotates, the rotation of the adjusting bolt 31 is suppressed, and the adjusting bolt 31 is screwed into or screwed into the adjusting nut 30. Adjustment teeth 33 are integrally attached to the outside of the brake cylinder at the front end of the adjustment nut 30. The method of integrally mounting is welding, gluing, caulking,
Various methods such as press fitting and odd-shaped fitting are possible. Adjusting tooth 3
When 3 rotates, the adjustment nut 30 rotates, and the adjustment bolt 31 is screwed out or screwed in depending on the rotation direction.

In addition to the above, the brake cylinder 10 has dust boots 13, 14, a washer 15, a piston cup 16, a feeling block 17, a spring 18, and an engaging groove for supporting a brake shoe 21 at the rear portion. 32
An anchor piston 19 and the like forming a ‘′ are attached.

<D> Adjustment Lever (FIGS. 1 to 3) The adjustment lever 40 is substantially L-shaped and is rotatably and swingably attached to the cylinder body 11 by means of a support shaft 44 such as a stepped bolt. ing. 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 on the front part of the adjusting lever 40,
It engages with the adjusting tooth 33. By moving the adjusting claw 41,
The adjustment tooth 33 is rotated only in one direction. Adjustment lever 40
An engagement portion 45 that abuts the rear end of the strut 502 and a hook portion 42 that hooks the rear end hook 62 of the adjustment spring 60 are formed in the rear portion. The bending piece 46 bent from one end of the rear portion of the adjusting lever 40 to the cylinder body side comes into contact with the protrusion 47 formed on the cylinder body 11 when the adjusting lever 40 excessively rotates, and the adjusting claw 41 is adjusted. This is to prevent the teeth 33 from coming off.

<E> Engagement portion and latching portion (FIGS. 1 and 5) The latching portion 42 of the adjusting lever 40 is, for example, as shown in FIG. By offsetting the force to the adjustment spring 60, a moment in the direction A (counterclockwise in FIG. 1) is applied to the adjustment lever 40 by the urging force of the adjustment spring 60. The support shaft hole 43 and the support shaft 44 of the adjusting lever 40 are always in contact with each other on the rear end side of the support shaft 44 and the support shaft hole 43. The force of the moment can be adjusted by changing the interval of the offset value d.

Alternatively, the structure of the engaging portion 45 'and the hooking portion 42' of the adjusting lever 40 'is formed in any shape such as a straight line other than the curved line so as to obtain the offset value d as shown in FIG. May be.

<F> Connecting Member (FIGS. 1 to 4) The connecting member 50 can be divided into a connecting plate 501 and a strut 502, or can be integrally formed. When divided, the connecting plate 501 is integrally attached to the piston 12, for example, in an annular shape. As the method of integrally mounting, various methods can be used as in the case of the adjusting nut 30. A hook stop 51 is formed by extending a part of the annular shape of the connecting plate 501 in the outer diameter direction, and a window hole 52 is bored at the base portion thereof.

The strut 502 has a substantially rectangular shape with a stepped front end so as to abut the window hole 52 of the connecting plate 501, and has a narrowed width to form an insertion portion 53 and a contact surface 54. The insertion portion 53 is inserted into the window hole 52 and abuts against the connecting plate 501 at the contact surface 54. The rear end of the strut 502 is in contact with the engaging portion 45 of the adjusting lever 40.

<G> Adjustment spring (FIGS. 1 to 5) In the adjustment spring 60, the front end hook 61 is locked to the hook stopper 51 of the connecting plate 501, and the rear end hook 62 is adjusted.
It is locked to the hooking portions 42, 42 'of 0, 40' and is stretched between them. Due to the tension thus tensioned, the adjusting claws 41 of the adjusting levers 40, 40 'are brought into contact with the adjusting teeth 33, and a moment in the direction A is given to the adjusting levers 40, 40' to support the adjusting levers 40, 40 '. Shaft hole 43 and support shaft 4
4 always abut on the rear end side. The tip end of the rear end hook 62 of the adjustment spring 60 is extended so as to overlap the rear end of the strut 502, and the rear end of the strut 502 is engaged with the engaging portions 45, 45.
It is also possible to prevent it from floating up and coming off (upward in FIG. 3).

The operation of the automatic gap adjusting device for the drum brake will be described below. <A> Automatic gap adjusting (FIGS. 1 to 3 and 5) When the brake operates and the piston 12 moves to the right side (in FIG. 3). Along with that, the connecting member 50 also moves to the right. Connecting member 50 (connecting plate 501, strut 50
2) and the engaging portions 45, 45 'of the adjusting levers 40, 40' and the latching portions 42, 42 'are normally integrally engaged by the urging force of the adjusting spring 60 and move to the right together. As a result, the adjusting levers 40 and 40 'rotate in the B direction around the support shaft 44, and the adjusting claws 41 of the adjusting levers 40 and 40' move to the adjusting teeth 33
Engages with the crests and moves in the direction of rotating the adjustment tooth 33.

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 levers 40 and 40 'rotate in the direction opposite to the B direction, and the adjusting pawl 41 crosses the ridge of the adjacent adjusting tooth 33 and returns to the original position. Return to. If the clearance between the brake shoe 21 and the drum is proper, the adjusting pawl 41 does not go over the ridge of the adjusting tooth 33, so that the adjusting tooth 33 does not rotate.

When the piston 12 advances, the adjusting teeth 41 of the adjusting nut 30 are adjusted by the adjusting claws 41 of the adjusting levers 40 and 40 '.
Although the case where 3 is rotated for automatic adjustment has been described, 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 urging force of the adjusting spring 60 causes the adjusting nut 30 to rotate. Adjustment lever 4
The adjustment teeth 33 of the adjustment nut 30 cannot be rotated by rotating 0, 40 '. At this time, the piston 12 and the connecting member 50 advance, but the adjusting levers 40 and 40 'do not rotate, so the rear end of the strut 502 and the adjusting levers 40 and 40'.
The engaging portions 45 and 45 'are separated from each other. This is to prevent over-adjustment by stopping the automatic gap adjustment device when the hydraulic pressure is high or the brake load is large.

<B> Action of abutment of the support shaft on the rear end side (FIGS. 1 and 5) When the adjusting levers 40 and 40 'rotate about the support shaft 44 in the B direction (clockwise in FIG. 1), Adjustment lever 40, 40
Since the hooking portions 42, 42 'of ′ are offset to the support shaft side of the adjustment lever, the support shaft hole 43 and the support shaft 44 of the adjustment lever rotate while the rear ends thereof slide. That is,
Adjustment lever 4 both when the brake is not activated and when the brake is activated
Since the support shaft hole 43 and the support shaft 44 of 0 abut on the rear end side, there is no influence of backlash due to the gap between the support shaft hole 43 and the support shaft 44. Therefore, it is possible to form the support shaft hole 43 and the support shaft 44 with a sufficient gap without strictly controlling the fitting state and the dimensional tolerance.

<A> 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. 6 may be eliminated and replaced with a single-sided opening cylinder.

[0022]

According to the present invention, the following effects can be obtained. <B> The hooking portion of the adjusting lever is offset to the support shaft side with respect to the engaging portion, and the urging force of the adjusting spring applies a rotational force to the adjusting lever. Due to this rotational force, the adjusting lever always secures the return position where the rear end sides of the supporting shaft and the supporting shaft hole of the adjusting lever contact. If the brake is operated from this state, no loss stroke occurs in the adjustment lever,
The piston stroke can be effectively used. As a result, there is no need to make the adjusting teeth fine or to increase the lever ratio of the adjusting lever, which is advantageous in processing and layout. <B> Similarly, since the return position of the adjusting lever is always constant, the engaging position of the adjusting claw and the adjusting tooth is stable, and a stable shoe gap can be obtained. <C> Since the return position of the adjusting lever is not affected by the diameter of the supporting shaft of the adjusting lever and the diameter of the supporting shaft (or the gap between them), it is not necessary to tighten the fitting and the dimensional tolerance control.
As a result, a sufficient clearance can be secured, and the assembling property of the adjusting lever is also improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of an engaging portion and a hooking portion of an adjusting lever.

[Fig. 2] Front view of the brake cylinder

FIG. 3 is a partially sectional plan view of a brake cylinder.

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

FIG. 5 is an explanatory view of another engaging portion and a latch portion of the adjusting lever.

FIG. 6 is a front view of a drum brake.

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 an adjusting spring stretched between the connecting member and the adjusting lever, A brake system with an automatic clearance adjusting device that automatically adjusts the shoe clearance by rotating the adjustment teeth with the adjustment claws by the rotation of the adjustment lever and screwing out the adjustment bolt that engages with the adjustment nut. The engaging portion between the adjusting lever and the connecting member, the engaging portion of the adjusting lever and the adjusting spring is offset to the supporting shaft side of the adjusting lever, and the supporting shaft and the supporting shaft hole of the adjusting lever are provided. A brake cylinder with an automatic clearance adjusting device, characterized in that the rear end sides of and are brought into contact with each other.