JPH0524828Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a wheel cylinder with a built-in auto-adjuster in which a piston rotates.

[Conventional technology]

This type of wheel cylinder installed in conventional vehicle drum brakes is, for example, the
-There is something disclosed in Publication No. 191935. For such wheel cylinders with a built-in auto adjuster, manual adjustment of the shoe distance is as follows:
This is done by rotating a wheel that is integral with the piston with a tool, and screwing the adjuster screw, which is non-rotatably engaged with the brake shoe, into or out of the piston.

[The problem that the idea aims to solve]

However, in the case of such a conventional wheel cylinder with a built-in auto-adjuster, the dustproof boot is enclosed between the wheel cylinder body and an intermediate member that is slidably inserted into this body. Because of this structure, it is possible to manually adjust the shoe distance without removing the boot, but since the irreversible screw between the piston and adjuster screw is not covered by the boot and is exposed,
This irreversible screw was prone to rust, and there was a fear that the durability of the auto-adjuster device would be poor.

[Means to solve the problem]

This invention was made in view of such conventional technical problems, and its configuration consists of a wheel cylinder body attached to a bucking plate, and a wheel cylinder body that is slidably and rotatably inserted into the wheel cylinder body. a piston whose outward flange portion contacts the wheel cylinder body and whose return position is regulated; and the piston is screwed into the piston with an irreversible screw;
The adjuster screw is built into the wheel cylinder body and is non-rotatably engaged with the brake shoe, and the adjuster screw is screwed when braking when the distance between the shoes exceeds the normal shoe distance. A wheel cylinder with a built-in auto-adjuster that rotates the piston so as to rotate the piston, the wheel cylinder having a built-in auto-adjuster that covers the teeth formed on the outward flange of the piston, and connects the wheel cylinder body and the adjuster. This is a wheel cylinder with a built-in auto-adjuster, which is equipped with a boot that is attached to the screw and has a cut in the part facing the tool insertion hole in the bucking plate. Deformation can cause normal occlusion.

[Effect]

Therefore, manual adjustment of the shoe distance is achieved by inserting a tool inserted through the through hole in the bucking plate into the cut in the boot, and engaging it with the teeth formed on the outward flange of the piston to move the piston in one direction. It is done by rotating it.

In addition, the cut end is caused by the elastic deformation of the boot.
If it is normally closed, the dustproofing effect of the boot will be even better.

〔Example〕

Hereinafter, embodiments of this invention will be described with reference to the drawings.

1 to 5 show an embodiment in which this invention is applied to a double-opening type wheel cylinder of a two-leading brake. In the figure, reference numeral 1 is a wheel cylinder body attached to a bucking plate 2 of a drum brake, and a fluid passage hole 1c is formed for supplying brake fluid from the outside. Inward flange portion 1 having one or more through holes 1b through which liquid passes
a is formed.

A first piston 3 and an auxiliary piston 4 are fitted into the wheel cylinder body 1 so as to be able to open both ways. The first piston 3 is slidably inserted into one end side of the wheel cylinder body 1 with a cup seal 5 interposed therebetween, and the outward flange portion 3a abuts against the one end surface of the wheel cylinder body 1 to restrict the return position. One brake shoe 6 is received in the groove 3b and cannot rotate. 12 is a dustproof boot that covers between the outward flange portion 3a of the first piston 3 and the wheel cylinder body 1.

On the other hand, the auxiliary piston 4 has a cylindrical shape with a bottom, and is slidably and rotatably fitted into the other end of the wheel cylinder body 1, with the outward flange 4a abutting the other end surface of the wheel cylinder body 1. The return position is restricted by pressing the other brake shoe 14 into the groove 1.
An adjuster screw 16, which is non-rotatably received in 6a, is screwed together with a non-reversible screw 17. Here, the irreversible screw 17 is a screw that does not undergo relative rotation due to an acting force in the axial direction, and corresponds to a general single thread screw. The outer periphery of the outward flange portion 4a of the auxiliary piston 4 is provided with an annular tooth portion 4c for manually adjusting the shoe distance.

20 is a cylindrical second piston, which is inserted into the wheel cylinder body 1 with a cup seal 21 interposed therebetween.
It is slidably inserted into the other end in a fluid-tight manner, and pushes out the auxiliary piston 4 from inside. Further, a cylindrical sleeve nut 22 is press-fitted into the inward flange portion 1a of the wheel cylinder body as shown in detail in FIG. 17 by a reversible screw 24 which is threaded in the same direction, and the backlash of this reversible screw 24 forms an operating interval δ corresponding to the normal operating interval. Here, reversible screw 24
is a screw that inevitably undergoes relative rotation due to relative movement in the forward and reverse directions in the axial direction between the sleeve nut 22 and the spindle 23, and corresponds to a multi-thread screw.
Note that the sleeve nut 22 may be attached to the wheel cylinder body 1 so as to be non-rotatable and non-movable in the center axis direction, and may be made non-rotatable by serration coupling or with a width across flats, and cannot be moved in the center axis direction using a C clip or the like. It can also be installed in a restrained manner.

Further, the spindle 23 is connected to the second piston 20 in a state where the seal ring 25 is interposed to maintain liquid tightness.
The outward protruding portion 23a at the other end is removably engaged with the auxiliary piston 4 via a roller clutch 26, which is a one-way clutch. As shown in FIG. 3, the roller clutch 26 has an outer ring formed by the rear end concave wall surface 4b of the auxiliary piston 4, an inner ring formed by the outwardly protruding portion 23a of the spindle 23, and a ring between the inner and outer rings 23a and 4b. It has a plurality of interposed rollers 26a and a spring 26b that urges the rollers 26a to engage between the inner and outer rings 23a and 4b, and the direction in which the adjuster screw 16 is screwed out from the auxiliary piston 4. The rotation of the spindle 23 in one direction is transmitted to the auxiliary piston 4. 27 is a washer made of a material with a low coefficient of friction, and the wall surface 4 of the rear end recess of the auxiliary piston 4
It is supported by a retainer 28 which is ring-attached to b and supports a roller clutch 26. Thus, the auxiliary piston 4 and the spindle 23 move together in the central axis direction together with the roller clutch 26. The sleeve nut 22, the reversible screw 24, the spindle 23, the roller clutch 26, etc. constitute the rotational drive mechanism 7.

A dustproof boot 18 covers between the adjuster stapler 16 and the wheel cylinder body 1.
is provided. In other words, the dustproof boots 18 are
One end is elastically attached to the annular groove 1c of the wheel cylinder body 1, and the other end is elastically attached to the annular groove 16b of the adjuster screw 16, covering the teeth 4c of the auxiliary piston 4. It's on. The boot 18 is made of an elastic material such as rubber or elastomer, has a cut 18a for inserting a tool, and is assembled so that the cut 18a faces the backing plate 2. In addition, a through hole 2a is formed in the bucking plate 2 in correspondence with this cut 18a, and this through hole 2a is normally closed by a removable plug 29 made of an elastic material, so that muddy water , prevents the intrusion of dust, etc.

Next, the effect will be explained.

When brake fluid is supplied from the fluid passage hole 1c of the wheel cylinder body during braking, the first piston 3 moves to the right in the figure and strokes, causing the brake shoe 6 to come into sliding contact with a brake drum (not shown). While generating a braking force, the second piston 20, the auxiliary piston 4, the spindle 23, and the adjuster screw 16 collectively move to the left in the figure and stroke,
The brake shoe 14 is brought into sliding contact with a brake drum (not shown) to generate braking force.

Now, if the forward stroke of the second piston 20 during braking is smaller than the operating interval δ given by the backlash of the reversible screw 24, that is, if the shu interval is smaller than the regular shu interval, then the second piston 20 During this operation, the piston 20 strokes within the range .delta. to generate the required braking force. When the brake is released, the adjuster screw 16, the auxiliary piston 4, the spindle 23, and the second piston 2 are
0 strokes back in one piece, and the outward flange portion 4a of the auxiliary piston 4 is connected to the wheel cylinder body 1.
It returns to the original position where it touched.

On the other hand, if the forward stroke of the second piston 20 during the braking operation is larger than the operation interval δ, the second piston 20, the auxiliary piston 4, the spindle 23, and the adjuster screw 16 are After a forward stroke in the range of δ, a further forward stroke is made, and the spindle 23 is screwed out while being rotated in one direction by the reversible screw 24. However, in this case, the inner ring 2 of the roller clutch 26
3a rotates in the direction of arrow A in FIG. 3, and since the roller clutch 26 is disconnected, the auxiliary piston 4 does not rotate.

After the brake shoe 14 is sufficiently pushed out and a braking force is generated, when the brake is released, the adjuster screw 16, the auxiliary piston 4, the spindle 23, and the second piston 20 are integrated for the duration of the operation 〓δ. After the return stroke, the spindle 23 is screwed in while being rotated in the other direction by the reversible screw 24. This causes the roller clutch 26 to connect,
The auxiliary piston 4 is rotationally driven, and the irreversible screw 17
The adjuster screw 16, which is screwed together and non-rotatably engaged with the brake shoe 14, is screwed out to automatically adjust the shoe distance. However, since the pitch of the irreversible screw 17 is smaller than the pitch of the reversible screw 24, the amount of adjustment is minute, and over-adjustment due to thermal expansion of the brake drum or the like is effectively prevented. In this way, it functions as a negative type auto-adjuster device that automatically adjusts the shift distance when the brake is released.

Next, manual adjustment of the show distance will be explained.
To manually adjust the shoe distance, remove the plug 29 from the state shown in FIG. 18a, and the outward flange portion 4a of the auxiliary piston 4.
The roller clutch 26 engages with the tooth portion 4c formed in
Rotate it in the opposite direction (A direction in the diagram). As a result, the adjuster screw 16 is screwed into the auxiliary piston 4 by the irreversible screw 17, and the distance between the brake shoe 14 and the brake drum is adjusted to be larger. In this way, the brake shoe 14 can be easily removed from the brake drum where stepped wear has occurred.

By the way, the through hole 2a of the bucking plate is
Since it is normally closed by the plug 29, there is little risk that muddy water and dust will enter through the hole 2a and enter the boot 18 through the cut 18a.
If the boot 18 is configured to be normally closed by the elastic deformation of the boot 18, the dustproof effect of the boot 18 will be even better. Furthermore, if the boot 18 is made of a transparent material, the shoe distance can be manually adjusted while visually confirming the state of engagement between the teeth 4c and the tool.

In this embodiment, the present invention was applied to a wheel cylinder equipped with a negative type auto-adjuster device, but if the present invention is applied to a wheel cylinder equipped with a positive type auto-adjuster device, it is possible to manually adjust the shift distance. You can adjust the size using .

[Effect of idea]

As understood from the above explanation, according to this invention, since the irreversible screw between the adjuster screw and the piston is covered by the boot, the durability of the irreversible screw and the automatic The durability of the adjuster device is improved. In addition, manual adjustment of the shoe distance can be performed by inserting a tool through the cut in the boot without removing the boot, making the manual adjustment work of the shoe distance extremely efficient.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of this invention, Fig. 2 is a sectional view showing the sleeve nut installed, Fig. 3 is a sectional view showing the roller clutch, and Fig. 4 is a sectional view showing the main parts. The enlarged sectional view and FIG. 5 are also explanatory views of the operation. DESCRIPTION OF SYMBOLS 1... Wheel cylinder body, 2... Bucking plate, 2a... Through hole, 4... Auxiliary piston (piston), 4a... Flange portion, 4c... Teeth portion, 14... Brake shoe, 16... ... Adjuster screw, 17 ... Irreversible screw, 18 ... Boot, 18a ... Cut, 22 ... Sleeve nut, 23 ... Spindle, 24 ... Reversible screw, 2
9...Plug.

Claims (1)

[Claims for Utility Model Registration] (1) A wheel cylinder body attached to a bucking plate, which is slidably and rotatably fitted into the wheel cylinder body, and whose outward flange portion abuts the wheel cylinder body. A piston whose return position is regulated by a piston, an adjuster screw that is screwed onto the piston with an irreversible screw and non-rotatably engaged with the brake shoe, and an adjuster screw that is built into the wheel cylinder body and is connected between the shoe and the brake shoe. A wheel cylinder with a built-in auto-adjuster, comprising a rotary drive mechanism that rotates the piston so as to screw out the adjuster screw when braking is performed in a state where the adjustment screw exceeds the normal shift interval,
A cut hole is formed at a location that covers the teeth formed on the outward flange portion of the piston, is attached to the wheel cylinder body and the adjuster screw, and faces the through hole for inserting a tool in the backing plate. A wheel cylinder with a built-in auto adjuster characterized by having a formed boot. (2) The auto-adjuster built-in wheel cylinder according to claim 1, wherein the cut is normally closed by elastic deformation of the boot.