JPS5814254Y2 - Automatic gap adjustment device for drum brake equipment - Google Patents

Description

[Detailed description of the invention] The invention expands the first and second brake shoes, which are biased in the contraction direction by spring forces disposed oppositely on the brake panel, by the operation of an expansion actuation device such as a wheel cylinder. It was designed to press against the brake drum to perform braking action.
Automatically compensates for the wear of the lining connected to the brake shoes, mainly in drum brake systems for vehicles.

This invention relates to an automatic gap adjustment device that maintains a constant gap between a lining and a brake drum during pre-kine operation.

This type of device has a retraction position regulating strut interposed between the first and second brake shoes, whose effective length is extended as the adjustment wheel rotates in a certain direction. It is known that the brake shoes are linked via an adjustment lever so that the relative movement of both brake shoes above a certain value is sensed and the adjustment wheel is rotated in the above direction.

The present invention improves the structure of the connecting part between the strut and the first brake shoe in the above-mentioned automatic gap adjustment device, prevents rattling of the strut, and reliably maintains the strut from rotating. An object of the present invention is to provide an automatic gap adjustment device that can accurately adjust the gap.

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a brake panel fixed to a stationary part of the vehicle body, and a pair of arcuate left and right brake shoes 1 and 2 are located inside the brake panel.
2a and 2b are arranged opposite to each other, and linings 3a and 3b are bonded to their outer peripheries to rub against the inner peripheral surface of a brake drum (not shown) that surrounds them and rotates with the wheels.

Both brake shoes 2a and 2b are formed in the same shape for compatibility.

Furthermore, a wheel cylinder 4 as a brake shoe expansion actuating device is provided at the inner upper part of the brake panel 1, and the upper ends of the first and second brake shoes 2 a t 2 b are respectively applied to the end surfaces of a pair of left and right pistons 5 of the wheel cylinder 4. It's a close encounter.

Further, an anchor block 6 is fixedly installed at the inner lower part of the brake panel 1 to support the lower ends of the first and second brake shoes 2at2b and serve as a fulcrum when they are expanded or contracted.

A pair of upper and lower return springs 7 a t 7 b are provided between the brake shoes 2 a t 2 b to constantly bias them in the direction of contraction.
is set up.

Now, regarding the automatic gap adjustment device, at the lower part of the wheel cylinder 4, the first strut 8a and the second strut
A contraction position regulating strut 8 consisting of a strut 8b is interposed between both brake shoes 2a and 2b.

The first strut 8a has a substantially U-shaped groove 10 in a flat part 9 at one end, and a left-hand male threaded part 11 at the other end.
A ratchet wheel 12 as an adjustment wheel is screwed onto the ratchet wheel 1.

The second strut 8b has a cylindrical portion 14 having a shaft hole 13 opening at one end surface, and a substantially U-shaped groove 16 at the other end flat portion 15. ) 8a so that the end surface of the cylindrical portion comes into contact with the side surface of the ratchet wheel 12.

In the vicinity of the ratchet wheel 12, the second strut) 8b
A detent pawl 17 is attached to the cylindrical portion 14 of the ratchet wheel 12 to prevent the ratchet wheel 12 from rotating back.

The detent pawl 17 fits the annular main body 18 into the small diameter portion 19 on the circumferential surface of the cylindrical portion 14, and brings the annular plane thereof into contact with the annular stepped portion 20 facing the side surface of the ratchet wheel 12. A pair of hook-shaped elastic claws 21 21 protruding toward the plane side are forcibly inserted into a pair of engagement holes 22 22 opening beyond the annular step 20 of the second strut 8b using elasticity. By engaging with the ratchet wheel 12, the wave-shaped elastic pawl portion 23 protruding toward the other annular plane side of the main body 18 is elastically pressed against the outer circumferential surface, that is, the tooth surface, of the ratchet wheel 12.

The strut 8 has a flat portion 9 of the first strut 8a located between the web 26 of the first brake shoe 2a and the brake panel 10, and an opening 1 of the brake panel 1.
The parking lever 24 is connected to the first brake shoe 2a via a parking lever 24 which has an abbreviated shape and projects from a portion a.

That is, one end 24a of the parking lever 24 is loosely inserted into the groove 10 of the first strut 8a, and the U-shaped notch 25 formed on one side of the parking lever 24 is brought into contact with the bottom of the groove 1o. A wide notch having a substantially U-shape and opening in the opposite direction to the opening of the groove 10 formed in the web 26 of the first brake shoe 2a at one end 24a of the parking lever. 27, and its side opposite to the notch 25 is brought into contact with the bottom of the notch 27 of the web 26.

The second strut 8b is inclined upward toward the second brake shoe 2b, and its flat portion 15 is a wide notch having the same shape as the notch 27 formed in the second brake shoe web 28. 29 , the groove 16 is brought into contact with the bottom of the notch 29 and engaged with the web 28 .

If the strut 8 is tilted in this way and inserted between both brake shoes 2a and 2b, one brake shoe 2a t
It is also possible to cope with the case where the distance between the struts 2b is not sufficient to interpose the struts 8.

mata parking lever 24 and second brake shoe 2
b web 28 and first and second struts) 8a.

Strut 8 by engagement of each U-shaped groove 10, 16 of 8b
This prevents it from falling off and preventing it from rotating.

A coil spring 30 is compressed between the upper surface of the flat part 15 of the second strut 8b and the upper inner surface of the web notch 29 of the second brake shoe 2b to prevent it from coming off.
The lower surface is pressed against the lower inner protrusion 31 of the notch 29 to prevent the second strut 8b from wobbling.

A pivot shaft 32 is press-fitted and protrudes near one end of the parking lever 24, as will be described later.

An adjustment lever 33 is pivotally attached to one protrusion of the pivot 32.

The adjustment lever 33 has an oval shape, and the tip of the vertical arm 34 is loosely inserted into the U-shaped groove 10 of the first strut 8a, and the side surface of the tip is inserted into the bottom of the notch 27 of the first brake shoe 2a. Let it come into contact.

On the other hand, a feed claw portion 36 formed by bending the end of the side arm 35 is engaged with the ratchet wheel 12.

A torsion coil spring 38 is fitted into the pivot 32, and both ends of the spring 38 are connected to the head 37 and the hook 39 of the adjustment lever 33, respectively.
2 to apply a rotational force to the adjustment lever 33 in the counterclockwise direction in FIG. The engagement of the portion 36 with the ratchet wheel 12 is maintained.

When adjusting the gap between the brake shoes 2a and 2b, the adjustment lever 33 rotates counterclockwise in FIG. In addition, the teeth of the ratchet wheel 12 are inclined toward the pivot shaft 32.

As shown in FIG. 4, the pivot shaft 32 is press-fitted 40 into the parking lever 24 at its intermediate portion.

A guide roller 41 is provided on the protruding portion of the adjustment lever 33 on the side opposite to the pivoting side thereof and contacts the opposing surface of the flat portion 9 of the first strut 8a and the brake panel 1.

42 is a circlip for preventing the guide roller 41 from coming off.

When the parking lever is operated, the guide roller 41 rolls between the flat portion 9 and the brake panel 10 to smoothly operate the parking lever 24.

On the opposite side of the guide roller 41 with the parking lever 24 as a boundary, a U-shaped spring 43 is compressed between the opposing surfaces of the first brake show web 26 and the flat portion 9 of the first strut 8a.

Spring 43 is. As shown in Fig. 5, a part of the cut-and-raised arch-shaped claw part 44, 44 projects outward from one end edge of the same, and a wide cut-and-raised hook-shaped claw part projects outward from the other end edge of the part. 4
5, the arcuate claws 44, 44 are engaged with a pair of engagement holes 46. It engages with the inner surface of the notch 27 and is prevented from coming off.

By compressing the U-shaped spring 43 between the web 26 and the flat part 9 as described above, the ratchet unit 43 is attached to the flat part 9.
20 Gap Adjustment Since the rotational force in the opposite direction to the rotational direction A can be applied to reliably maintain the rotation, there is no loss of rotation of the ratchet unit 120, and the first strut (8a) is prevented from rattling to ensure accurate clearance. Adjustments can be made.

47 is a stopper of the parking lever 24, which is fixed to the brake panel 1.

One end of a parking operation wire (not shown) is connected to the outer end of the parking lever 24.

Next, to explain the operation of this embodiment, when a brake pedal (not shown) is stepped on and a mask cylinder (not shown) is actuated, the output oil pressure acts on the wheel cylinder 4 and pushes the left and right pistons 5 in the direction of protruding from inside the cylinder. do.

As a result, the left and right first and second brake shoes 2a, 2b
expands using the anchor block 6 as a fulcrum, and the linings 3a, 3b of both brake shoes 2a, 2b are pressed against the brake drum, thereby applying braking to the wheels.

During this braking, if the lining 3a>3b is worn out and the brake shoes 2a and 2b move relative to each other and expand beyond a certain value, the vertical arm 34 of the adjustment lever 33
Since the tip follows the first brake shoe 2a, the spring 3
8 rotates the adjustment lever 33 counterclockwise in FIG. 2, and while rotating the ratchet wheel 12 in the direction of arrow A using the feed pawl 36 of the adjustment lever 33, the adjustment lever 33 is moved over the male threaded portion 11 of the first strut 8a to the right in FIG. direction, and the second strut 8b is pushed in the same direction.

To release this braking, if you release the brake pedal,
Both brake shoes 2a are fixed by return springs 7a and 7b.
, 2b is retracted, and the adjustment lever 33 is moved by its longitudinal arm 34.
Since the tip is pushed back against the spring force of the spring 38, the feed pawl 36 rotates clockwise while sliding against the ratchet wheel 12 and returns to the original position.

This sliding of the feed pawl portion 36 with respect to the ratchet wheel 12 is as follows:
The waveform elastic pawl portion 23 of the detent pawl 17 is connected to the ratchet wheel 12.
Since the ratchet wheel 12 is in pressure contact with the male threaded portion 11 of the first strut 8a and frictional resistance is generated at the threaded portion thereof with the male threaded portion 11 of the first strut 8a, the ratchet wheel 12 is rotated smoothly.

Therefore, the amount of feed of the ratchet wheel 12 during the braking process is maintained as it is, and the positions of both brake shoes 2a, 2b after the brake is released are half the amount of feed of the ratchet wheel 12, based on the position before braking. This means that the two brake shoes 2at2b are moved closer to the brake drum by 1, and the displacement of both brake shoes 2at2b is caused by the braking of both linings 3at.
This is the amount of compensation for the wear of 3b.

(Thus, the gap between the brake drum and each lining 3a, 3b in the non-braking state is automatically adjusted in substantially the same way as before braking, and the operating stroke of the wheel cylinder 4 is maintained appropriately even during the primary braking. It is.

A good braking effect can be obtained.

When the parking brake is activated, the parking lever 24 swings counterclockwise in FIG. 2 about the pivot shaft 32 by operating an operating lever (not shown) and pulling a parking wire (not shown).

This causes the tip 24a of the parking lever 24 to move to the first position.
Since the bottom of the notch 27 of the brake shoe 2a is pushed to the left, the first brake shoe 2a expands using the anchor block 6 as a fulcrum, and presses its lining 3a against the brake drum.

The subsequent swinging of the parking lever 24 causes the parking lever 24 to swing using the bottom of the notch 27 of the first brake shoe 2a as a fulcrum. 2nd through
is transmitted to the brake shoe 2b, and the second brake shoe 2
b expands using the anchor lock 6 as a fulcrum, and presses its lining 3b against the brake drum to apply braking.

If the lining 3at3b is worn during this braking, the adjustment lever 33 rotates counterclockwise when the first brake shoe 2a expands, so that the ratchet wheel 12 rotates in the direction of arrow A. Each action of sending it out is performed on one side of the lining 3a.

3b is compensated for wear.

Note that the ratchet wheel 12 may be rotated and sent out when the brake is released.

As described above, according to the present invention, since the U-shaped spring is contracted in the opposing surface between the first brake shoe web and the end of the strut, By applying a rotational force in the opposite direction, it is possible to reliably maintain rotation prevention, eliminate rotation loss of the adjustment wheel, prevent rattling of the strut, and perform accurate gap adjustment.

Further, since the U-shaped spring has one claw portion engaged with the engagement hole of the strut and the other claw portion engaged with the inner surface of the notch portion of the first brake shoe web, it will not fall off.

[Brief explanation of the drawing]

Figure 1 is a front view of one embodiment of the present invention, and Figure 2 is the same as Figure 1.
3 is a cross-sectional view taken along the line ■--■ in FIG. 1, FIG. 4 is a cross-sectional view taken along the line IV--N in FIG. 1, and FIG. 5 is an exploded perspective view of the strut and the U-shaped spring. 1... Brake panel, 2a... 1st
Brake shoe, 2b...Second brake shoe, 4...: Wheel cylinder as expansion actuation device, 8... Contraction position regulating strut, 10...
... Groove, 12 ... Ratchet wheel as adjustment wheel, 24 ... Parking lever, 24a ...
... Parking lever tip, 26 ... Web, 27 ... Notch, 32 ... Pivot, 33 ... Adjustment lever, 41 ... ...Guide roller. 43...U-shaped spring, 44...Claw portion,
45...Claw portion, 46...Engagement hole.

Claims (1)

[Claims for Utility Model Registration] Between the first and second flexible wheels, which are disposed opposite to each other on the brake panel, are biased in the contraction direction by a spring force, and can be expanded by the operation of an expansion actuating device, there is a constant adjustment wheel. A contraction position regulating strut whose effective length is extended as the direction rotates is interposed, and the first brake shoe and the adjustment wheel are connected to each other by sensing a relative movement of both brake shoes of a certain value or more. In an automatic gap adjustment device for a drum brake device which is interlocked via an adjustment lever configured to rotate an adjustment wheel in the aforementioned direction, a substantially U-shaped notch is formed in the web of the first brake shoe. Further, a substantially U-shaped groove is formed at the end of the strut on the first brake shoe side, and the end of the strut is arranged such that the opening of the groove is in the opposite direction to the opening of the notch. is disposed between the first brake show web and the brake panel, one end of the parking lever is loosely inserted between the notch and the groove, and both sides of the parking lever are connected to the bottom of the notch and the groove, respectively. A guide roller is provided on a protruding portion of the pivot of the adjustment lever protruding from the parking lever and contacts a surface facing the end of the strut and the brake panel, and the guide roller is provided with the parking lever as a boundary. K between the opposing surfaces of the first brake show web and the end of the strut on the opposite side.
A U-shaped spring is compressed, and a claw part protruding outward from one end edge of the spring is engaged with an engagement hole raised in the end of the strut, and a claw part protruding outward from the other end edge of the spring. an automatic gap adjustment device for a drum brake device, wherein the gap adjustment device is engaged with an inner surface of the notch portion of the first brake shoe web.