JP3511157B2 - Automatic adjustment of shoe gap 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 shoe clearance adjusting device for a drum brake, and more particularly, to substantially integrate these components in order to improve the handling and assembling workability of the adjusting device. It is related to the structure.

[0002]

2. Description of the Related Art As an automatic shoe clearance adjusting device of this type, for example, Japanese Patent Publication No. 1-58374 is known, and its structure will be outlined with reference to FIG.

S1 and S2 are brake shoes movably mounted on the back plate P. A wheel cylinder C, which is a shoe expanding device, is arranged between the upper facing ends of the brake shoes, and the brake shoes are mounted between the lower facing ends. An anchor member A is disposed in
Each is fixed to the back plate P.

Brake drum and brake shoes S1, S
The automatic shoe clearance adjusting device that automatically adjusts the clearance between the strut member S and the brake shoes S1 and S2 adjacent to the wheel cylinder C, and a substantially square-shaped adjuster. It is composed of a lever L1 and an adjusting spring B and the like.

The strut member S is composed of an adjusting bolt b, an adjusting nut n and a tube member t. One side surface of the nut n screwed on the bolt b abuts on the opening end surface of the tube member t, and the bolt b projects. The portion is loosely fitted in the tube member t. Further, the ends of the adjusting bolt b and the tube member t are crushed to have a fork shape, and abuttingly engage with one of the brake shoes S1 and a brake lever L2 described later.

An intermediate portion of the adjust lever L1 is rotatably supported by one brake shoe S1 by a pin P1, one arm of which is engaged with the adjust nut n and the other arm of which is a tube member t. An adjustment spring B is stretched between the extension portion of the other arm and the one brake shoe S1 so as to come into contact with the end surface. In other words, the adjust spring B is the adjust lever L.
1 is given a counterclockwise rotational force about the pin P1 as a fulcrum, and a biasing force is applied so that one arm of the lever L1 is always engaged with the outer peripheral teeth of the adjust nut n.

L2 is a lever for a parking brake, one end of which is attached to the other brake shoe S2 by a pin P2.
Is rotatably supported, and a control cable (not shown), which is a remote control means, is connected to the other end. R
1 and R2 are shoe return springs, and H1 and H2 are shoe hold devices.

Next, the braking operation configured as described above will be described.

First, when the wheel cylinder C is pressurized during service braking, both brake shoes S1 and S2 expand with the contact point with the anchor member A as a fulcrum, and rotate the brake drum (not shown). ) To frictionally engage and brake this.

Next, when the control cable (not shown) is pulled during the parking brake, the lever L2 rotates clockwise about the pin P2 as a fulcrum, and the acting force is transmitted to one brake shoe S1 via the strut member S, The shoe S1 expands around a contact point with the anchor member A as a fulcrum and frictionally engages with a brake drum (not shown). Then, the reaction force acts on the pin P2 to similarly open the other brake shoe S2 and frictionally engages with a brake drum (not shown), thereby keeping the brake drum (not shown) in a stopped state.

Next, the operation of the shoe clearance automatic adjustment configured as described above will be described.

When the wheel cylinder C is pressed by the service brake and both brake shoes S1 and S2 are opened, the adjusting lever L1 is rotated counterclockwise by the urging force of the adjusting spring B, and the strut member S is rotated.
To follow the lever L2 that cooperates with the other brake shoe S2. Further, the pin P1 shaft supporting portion of the adjusting lever L1 cooperates with one brake shoe S1. At this time, when the rotation amount of the one arm of the adjusting lever L1 exceeds the inter-tooth pitch of the adjusting nut n, the nut n is rotated to pull out the adjusting bolt b corresponding to one tooth from the tube member t, and thus the strut member S. Of the brake drum (not shown) and the brake shoes S1, S2 are always kept constant.

[0013]

The automatic shoe clearance adjusting device having the above-mentioned structure has the following problems. <B> If the total length of the strut is set to a predetermined length in advance in the preparation stage, it is convenient because the work of adjusting the diameter of the brake shoe is unnecessary in the subsequent process. However,
Since the tube member is only loosely fitted in the adjustment bolt, it is easily pulled out when handling it, so temporary work with rubber bands etc. is required and the number of steps is increased, and the work is troublesome. I was scared. <B> Since the adjusting lever and adjusting spring that compose the automatic shoe clearance adjusting device are mounted on the brake shoe, a robot mechanism that makes complicated movements is required to automate the assembly line, which is extremely difficult to realize. It was difficult.

[0014]

According to the present invention, there is no need to increase the number of parts constituting an automatic shoe clearance adjusting device.
It is an object of the present invention to realize the above-mentioned problem solution by substantially integrating the above-mentioned device by designing.

For this purpose, an automatic shoe clearance adjusting device for a drum brake according to the first aspect of the present invention is provided.
A shoe gap is installed between the opposite ends of the pair of brake shoes, and an anchor device is placed between the opposite ends of the pair of brake shoes to detect the amount of expansion of both brake shoes and adjust automatically. An automatic shoe gap adjusting device for a drum brake, wherein the automatic shoe adjusting device is arranged between both brake shoes adjacent to the shoe expanding device. The automatic shoe gap adjusting device is a strut having an extendable screw mechanism. And an adjusting lever that automatically rotates the screw mechanism to extend the entire length of the strut, and an adjusting spring that applies a rotational force to the adjusting lever .
The end is rotatably supported and this support point
During rotation of the adjust lever during automatic clearance adjustment
To give the adjusting lever a turning force,
The automatic shoe gap adjusting device for a drum brake is characterized in that the adjusting spring is stretched between the adjusting lever and the strut to integrate the constituent members of the automatic shoe gap adjusting device.

Further, the automatic shoe clearance adjusting device for a drum brake according to a second aspect of the present invention is the above-mentioned first aspect.
In the invention, the restricting means for restricting the rotation of the adjustment lever by the adjuster preparative spring force on its way,
This regulation position is provided between the lever and the strut.
At the adjust lever, the both brake shoes
Than in the assembled condition
When installing between the brake shoes,
Push a part of the adjust lever to move the adjust lever.
Rotate in the direction opposite to the shoe clearance adjustment direction
An automatic shoe clearance adjusting device for a drum brake, which is characterized by being held.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS.

Reference numeral 1 denotes an immovable back plate, on which opposed brake shoes 2 and 3 are movably mounted. The shoes 2 and 3 are formed from rims 4 and 4 and webs 5 and 5 in a T-shaped cross section, and linings 6 and 6 are fixed to the outer circumferences of the rims 4 and 4.

Numeral 7 is a wheel cylinder which is arranged between the upper opposing ends of the brake shoes 2 and 3 and which spreads the brake shoes 2 and 3 by a service brake, and is fixed to the back plate 1 by bolts or the like. As well as
The pistons 7a, 7a are in light contact with the upper facing ends of the webs 5, 5, respectively.

An anchor device 8 supports the lower facing ends of the brake shoes 2 and 3, and is fixed to the back plate 1 by two rivets 9, 9. Although the anchor device 8 of the present embodiment has a plate shape, it may have a pin shape. In addition, 8a is an extension part extended from the anchor device 8, and is a site | part which guides the control cable for remote towing operation which is not shown in figure.

10 is a lever for a parking brake,
These are parts that are built in as needed. The lever 10 is arranged so as to overlap with the web 5 of the brake shoe 3, and its base portion 10a is located near the upper end of the web 5 and has a pin 11a.
Therefore, a U groove for connecting a control cable (not shown) for remote pulling operation is formed in a folded manner at the free end 10b. Reference numeral 10c is a protrusion that regulates the return position of the lever 10 when the brake is not operated, and is in contact with the inner surface of the rim 4.

Reference numeral 12 denotes an automatic shoe clearance adjusting device, which is a strut 13 which is adjacent to the wheel cylinder 7 and which is suspended between both brake shoes 2 and 3, and an adjust lever 1.
9 and an adjusting spring 20.
The strut 13 is composed of a bolt member 14, a nut member 15 and a tube member 16. The nut member 15 is screwed onto the male screw shaft portion 14a of the bolt member 14, and the protruding portion is loosely fitted into the tube member 16. Cage, tube member 1
The opening end surface of 6 is in contact with one side surface of the nut member 15.

Notched grooves 14b and 16b are formed in the crush plate portions at the ends of the bolt member 14 and the tube member 16, respectively, and the bottoms of the notched grooves 14b abut the lever 10 and the notched groove 16b. The bottom is in contact with the web 5 of the brake shoe 2. In addition, the outer periphery of the nut member 15 is provided with small teeth 15a, for example, saw teeth.

The adjusting lever 19 has a generally hook-like shape, and one groove 19a thereof abuts and engages with the stepped surface 16c of the cutout groove 16b portion of the tube member 16, and the other bent portion 19b has a tip end. Engages in abutting engagement with the small teeth 15a of the nut member 15. A bent portion 19c that abuts and engages with the web 5 of the brake shoe 2 is formed in an intermediate portion of the lever 19, and a portion adjacent to the other bent portion 19b can abut the outer circumference of the tube member 16. A bent portion 19d is formed.

The adjusting spring 20 has a coil portion around which the bolt member 14 is wound, and hook portions 20a, 20a at both ends are provided.
b is a stepped surface 14c of the cutout groove 14b of the bolt member 14
And a protruding hooking portion 19e adjacent to one groove 19a portion of the adjuster lever 19 are stretched. Due to this tension, a counterclockwise rotational force is applied to the adjust lever 19 with the bottom of the notched groove 16b of the tube member 16 with which the bottom of one of the grooves 19a abuts as a fulcrum, and the other bent portion 19b is minutely divided. A biasing force is applied to engage the teeth 15a, and an axial force is applied to the struts 13.

As is clear from the assembly drawings of the shoe gap automatic adjusting device 12 shown in FIGS. 2 and 3, the excessive rotation of the adjusting lever 19 is regulated by the bent portion 19d of the adjusting lever 19 abutting the tube member 16. All the members constituting the adjusting device 12 can be substantially integrated.

Therefore, it is easy to handle and transport, and since the effective length of the strut 13 can be set in advance, the assembly of the brake in the subsequent process becomes very easy.

Numerals 21 and 22 are shoe return springs stretched between upper and lower parts of the brake shoes 2 and 3, and when the shoe gap automatic adjusting device 12 is laid between the brake shoes 2 and 3 by this tension, The bent portion 19c of the adjust lever 19 is pressed by the web 5, and the lever 19 is rotated in the clockwise direction about the contact point with the stepped surface 16c of the tube member 16 and held at a predetermined position. At this time, the rotation amount of the other bent portion 19b is set to be larger than the amount corresponding to the inter-tooth pitch of the small teeth 15a.

Reference numerals 23 and 24 are known shoe-hold devices for elastically supporting the brake shoes 2, 3 on the back plate 1.

[0030]

[Brake operation] Regarding the operation of the service brake and the operation of the parking brake in the above configuration,
Since it is the same as the above-mentioned conventional example, its description is omitted.

[0031]

[Operation of shoe clearance automatic adjustment] Next, the operation of the shoe clearance automatic adjustment in the above-described configuration will be described.

In FIG. 1, when the wheel cylinder 7 is pressurized, the brake shoes 2 and 3 spread laterally around the contact point with the anchor device 8 as a fulcrum and frictionally engage with a brake drum (not shown). . At this time, the adjusting lever 19 rotates counterclockwise about the contact point with the stepped surface 16c of the tube member 16 as a fulcrum by the acting force of the adjusting spring 20, and the bent portion 19c thereof follows the brake shoe 2. , The brake shoe 2 further rotates around the contact point with the web 5 as a fulcrum, and causes the strut 13 to follow the lever 10 moving integrally with the brake shoe 3.

However, now the linings 6 and 6 are worn,
When the amount of rotation of the other bent portion 19b of the adjust lever 19 exceeds the inter-tooth pitch of the small teeth 15a of the nut member 15, the nut member 15 is rotated by one tooth and the bolt member 1 is rotated.
4 is unscrewed from the tube member 16 and automatically adjusted so that the gap between the brake drum (not shown) and the brake shoes 2, 3 is always kept constant.

[0034]

Embodiment 2 of the Invention FIGS. 4 to 6 show an embodiment of an automatic shoe clearance adjusting device 112 applied to another strut mechanism.

In terms of function, the same members as those in the first embodiment described above will be described with reference numerals of 100s.

The strut 113 comprises a bolt member 114, a tube member 116 and a socket member 117. An adjusting toothed ring 114d is integrally formed at an intermediate portion of the bolt member 114, and a male screw shaft portion 114a on the left side thereof is screwed into a female screw 116a of the tube member 116 and a shaft portion 114e on the right side is a socket. It is loosely fitted in the hole of the member 117. Further, the tube member 116 and the socket member 1
The end portion 17 is crushed to have a flat plate shape, and the tube member 1
A cutout groove 116b for receiving the web 5 and the lever 10 is formed in the flat plate portion 16 and a cutout groove 117b for receiving the web 5 is formed in the flat plate portion of the socket member 117.

The adjusting lever 119 has the daruma hole 1
19a is a pin 1 planted on the flat plate portion of the socket member 117.
The first arm 1 is rotatably and tiltably supported by 18
Socket member 11 so that 19b abuts and engages with the adjusting toothed wheel 114d and the second arm 119c abuts on the web 5.
7 notched groove 11 extends toward the 7 b of the third arm 119
d is the first arm 11 with respect to the axis of the strut 113.
9b is extended to the opposite side, and the adjustment toothed wheel 11 is provided at this extension.
The contact portion 119f that abuts the side surface of the tube member 116 side of 4d to prevent the socket member 117 from coming off, and the adjust lever 119 that abuts the outer periphery of the tube member 116.
And a bent portion 119g that restricts excessive rotation of the.

The adjusting spring 120 includes a protruding hooking portion 119e protruding from the first arm 119b of the adjusting lever 119 and a stepped surface 117 at the end of the socket member 117.
The tension lever 114a is stretched between the adjusting lever 119c and the adjusting lever 119, and the tension is applied to the adjusting lever 119 in the counterclockwise direction about the pin 118 as a fulcrum.
A biasing force is applied so as to abut and engage with.

However, the assembled state of the shoe clearance automatic adjusting device 112 is as shown in FIG.
It is set that the right end surface of the second arm 119c thereof projects from the bottom of the notch groove 117b of the socket member 117 by a predetermined amount when the bent portion 119g of the ninth member abuts on the outer periphery of the tube member 116. The protrusion amount may be set so that the rotation amount of the second arm 119c is equal to or larger than the inter-tooth pitch of the adjustment toothed wheel 114d. As is apparent from the above-described configuration, the automatic adjustment device 112 can be substantially integrated, and thus the same effect as that of the first embodiment described above can be obtained.

[0040]

[Operation of automatic shoe clearance adjustment] As shown in FIG. 6, the adjust lever 119 during the assembly of the drum brake is driven by the tension of the shoe return spring 21 to cause the second arm 119c to move.
Has a right end surface flush with the bottom of the notch groove 117b of the socket member 117.

Although the first embodiment described above shows the type of automatic adjustment when the brake is actuated, the so-called on-stroke type, the present embodiment shows the type of automatic adjustment when the brake is released, the so-called off-stroke type. ing. The change between the on-stroke type and the off-stroke type can be easily performed by changing the direction of the serrated teeth and the screw.

Now, from the state shown in FIG. 6, the brake shoes 2, 3
When the brake shoe 2 is opened, the tension of the adjusting spring 120 causes the second arm 119c of the adjusting lever 119 to rotate counterclockwise around the pin 118 as a fulcrum and to rotate the brake shoe 2
The strut 113 follows the brake shoe 3 via the pin 118 with this contact point as a fulcrum. At this time, if the rotation amount of the first arm 119b exceeds the inter-tooth pitch of the adjustment toothed wheel 114d, the adjustment toothed wheel 114d is rotated to extend the strut 113 when the brake is released.

[0043]

According to the present invention, the following effects can be obtained. <A> Since the strut length can be set to a predetermined length in advance, the shoe clearance adjustment work in the subsequent step is unnecessary, and the number of steps can be reduced. <B> Since the shoe clearance automatic adjusting device can be handled as one assembly, it is particularly easy to automate the brake assembly line. <C> Since all the constituent members of the shoe clearance automatic adjusting device are substantially integrated, there is no risk of separation and loss or damage during handling. <2> Further, since it is not necessary to separately provide a strut separation preventing means during transportation, the cost can be reduced accordingly.

[Brief description of drawings]

FIG. 1 is an example of a front view of a drum brake device according to a first embodiment of the invention.

FIG. 2 is an enlarged view showing an assembled state of the automatic shoe clearance adjusting device of FIG.

FIG. 3 is a bottom view of FIG.

FIG. 4 is a bottom view of an example of an enlarged view showing an assembled state of the shoe clearance automatic adjusting device according to the second embodiment of the invention.

5 is a state diagram when the shoe clearance automatic adjusting device of FIG. 4 is a drum brake assembly.

FIG. 6 is a bottom view of FIG.

FIG. 7 is a front view of a drum brake device according to a conventional embodiment.

[Explanation of symbols]

1 back plate A few brake shoes 7 wheel cylinder 8 anchor device 10 Lever for parking brake 12,112 Automatic shoe clearance adjustment device 13,113 struts 14,114 bolt members 15 Nut member 16,116 Tube member 19,119 Adjust lever 20,120 Adjust spring 21,22 Shoe return spring 117 Socket member

Claims (2)

(57) [Claims] 1. A shoe expanding device is provided between one opposing ends of a pair of brake shoes, and an anchor device is provided between the other opposing ends of the pair of brake shoes. In the automatic shoe gap adjusting device of a drum brake, wherein the automatic shoe gap adjusting device is arranged between both brake shoes adjacent to the shoe expanding device. A strut having a screw mechanism, an adjust lever that automatically rotates the screw mechanism to extend the entire length of the strut, and an adjust spring that applies a rotational force to the adjust lever . It is rotatably supported at the end and this support point automatically adjusts the shoe clearance.
At the center of rotation of the adjusting lever
A shoe for a drum brake, characterized in that the adjust spring is stretched between the adjust lever and the strut so as to apply a rotational force to the adjust lever, and the constituent members of the shoe clearance automatic adjusting device are integrated. Automatic gap adjustment device. 2. A regulating means for regulating the rotation of the adjusting lever by the adjusting spring force in the middle thereof is provided between the lever and the strut, and in this regulating position, the adjusting lever has both It is over-rotating in the shoe clearance adjustment direction compared to the state where it is mounted between the brake shoes, and when it is mounted between both brake shoes, it pushes part of the adjust lever to adjust the shoe clearance. An automatic shoe clearance adjusting device for a drum brake, which is rotated in the opposite direction and held in a fixed position.