JPH07317818A - Drum brake device - Google Patents

Abstract

PURPOSE:To enhance the durability of an adjusting lever and avoid drop of the adjusting function by forming a buffer part admitting an elastic deformation in the contacting part of the adjusting lever to be in contact with a brake lever. CONSTITUTION:The force of an adjust spring acts on the base 51 of an adjusting lever 50, which is thereby given a rotational motive clockwise round a stepped pin 15, and an adjust pawl 52a formed on an adjust arm 52 is put in elastic contact with an adjust tooth 42a of a strut 40 so as to hinder the tooth 42a from rotating. In this situation, the buffer part 53a of a detent arm 53 constituting the adjusting lever 50 comes in contact with the contacting part 32 of a brake lever 30 so that the return position of the lever 50 is restricted. At this time, the contracting force of the adjust spring acts on the detent arm 53, bunt it can be absorbed elastic deformation of the buffer part 53a, so that the adjusting lever 50 is free from deflection, shaving, etc., and its durability can be enhanced.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a drum brake device of this type,
JP-B-62-25551 and the like are mentioned.

In the above-mentioned drum brake device, one end of a pair of brake shoes slidably supported on the back plate abuts on the wheel cylinder and the other end abuts on the anchor.
Further, both ends of the strut are brought into contact with the shoe web near the wheel cylinder, and the adjusting lever of the strut is rotated by an adjusting lever rotatably provided on the shoe web to adjust the braking gap. It is composed of a base portion, a rising portion continuing from the base portion, and a lever portion continuing to the rising portion, and a pin is inserted into a pin hole formed in the base portion to rotatably attach to a shoe web on the leading side, The tongue piece formed on the base is struted by engaging the claw formed at the tip with the adjusting gear, and by locking the other end of the adjusting lever spring whose one end is locked by the leading side shoe web at the rising part. Of the tongue on the leading side of the tongue at all times, and at the tip of the tongue in the strut axial direction. A stopper projecting to exist bets with a predetermined gap is configured by integrally formed.

When the adjusting lever rotates clockwise and exceeds the proper range, the stopper of the adjusting lever comes into contact with the side surface of the strut on the wheel cylinder side,
By restricting the excessive rotation of the adjusting lever, the adjusting lever is kept in the normal position without being disengaged from the adjusting gear.

[0005]

The above-mentioned drum brake device has the following problems.

<A> When the stopper for restricting over-rotation comes into contact with the side surface of the strut, the contracting force of the adjust lever spring acts, so that the stopper or scraping occurs, which causes a problem in durability.

<B> Since the operating force for rotating the adjusting lever and rotating the adjusting gear to extend the strut is the spring force of the adjusting lever spring, it is the rotating shaft of the adjusting lever due to abrasion powder or rust of the lining. If the area around the support pin is stuck, the rotational resistance of the adjust lever increases, and misadjustment is likely to occur.

<C> The clearance between the brake shoe and the brake drum is too large when the brake shoe is mounted on the vehicle or replaced, and when the brake lever is operated in this state, the adjustment lever faces the member. For example, it may interfere with a brake shoe, a back plate, or the like, and may further deform or damage the adjusting lever.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve the durability of the adjusting lever and avoid the deterioration of the adjusting function. To provide.

[0010]

According to the present invention, the brake shoes are mounted between a pair of brake shoes, and the brake shoes are respectively supported from the inner peripheral side in notches formed at both ends thereof, and a male screw member A strut having a screw member, one of which has adjusting teeth formed thereon, and one of the brake shoes rotatably supported by one of the brake shoes. A brake lever for expanding operation and a support shaft common to the brake lever are pivotally supported on the brake shoe, and an engaging arm formed at one end abuts on the brake lever and is integrally rotatable. The adjusting claw formed on the adjustment lever engages the adjusting tooth of the strut and the adjusting lever is biased in the return direction, and the adjusting claw of the adjusting lever is adjusted to the strut. A drum having an automatic gap adjusting function for adjusting the gap of the brake shoe by rotating the adjusting teeth to extend the struts when the amount of rotation of the adjusting lever exceeds a certain amount. In the brake device, when the brake lever is rotated and a force of a certain amount or more is applied between the adjustment lever and a member facing the adjustment lever, the engagement arm of the adjustment lever comes into contact with the brake lever. The drum brake device is characterized in that a buffer portion that allows elastic deformation is formed in the.

[0011]

Embodiment 1 An embodiment of the present invention will be described below with reference to FIGS.

<A> Overall Structure of Drum Brake Device FIG. 2 is a front view of a leading / trailing type drum brake device having both a mechanical type and a hydraulic type.

A back plate 10 is fixed to a non-rotating member of the vehicle, and a pair of brake shoes 20a and 20b are mounted on the back plate 10.

The brake shoes 20a, 20b have a shoe web 22 integrally fixed to the inner peripheral side of an arc-shaped shoe rim 21, and a lining 2 on the outer peripheral surface of the shoe rim 21.
3 is fixed.

One end of each brake shoe 20a, 20b abuts on the wheel cylinder 11, and the other end abuts on the anchor portion 12, and the pair of brake shoes 20a, 20b expands in diameter due to the extension of the wheel cylinder 11 so that a brake (not shown) is formed. The pair of brake shoes 20a, 20b are contracted by the spring force of the shoe return springs 13a, 13b stretched between the brake shoes 20a, 20b when the drum is braked or not braking.

Between the brake shoes 20a and 20b on the side of the wheel cylinder 11, an automatic gap adjusting device, which will be described later, is provided, and the amount of the gap with the brake drum can be automatically adjusted according to the amount of wear of the lining 23. It is like this.

Further, the drum brake device is equipped with a mechanical actuation mechanism, and the back plate 10 is inserted into a connecting portion 31 formed at a free end of a brake lever 30 pivotally supported on one brake shoe 20a on the left side of FIG. Then, connect the end portions of the cables guided by the cable guide portion 14,
By counterclockwise swinging operation of the brake lever 30, the pair of brake shoes 20a, 20b can be mechanically expanded in diameter for braking.

<B> Automatic clearance adjusting device The automatic clearance adjusting device is, as shown in FIG. 2, a strut 40 which is placed horizontally between a pair of brake shoes 20a and 20b.
And an adjusting lever 50 pivotally supported on one of the brake shoes 20a, and an adjusting spring 60 for biasing the adjusting lever 50 in the clockwise direction.

<C> Strut As shown in FIGS.
The sleeve member 41, the male screw member 42, and the female screw member 43 are three elements, and the stepped notch 41 is provided on the left side of the sleeve member 41.
a is formed, and one brake shoe 20a is supported from the inner peripheral side. The sleeve member 41 and the male screw member 42 are rotatably fitted together, and the side surface of the adjustment tooth 42a formed on the male screw member 42 is in contact with the right end surface of the sleeve member 41.

The male screw member 42 and the female screw member 43 are screwed together, and the entire length of the strut 40 is expanded and contracted by the turning operation of the adjusting tooth 42a integral with the male screw member 42. Female thread member 4
3 has a notch 43a formed on the right side thereof, and the other brake shoe 20b is fitted and supported from the inner peripheral side.

<D> Brake Lever As shown in FIGS. 3 and 4, the brake lever 30 is pivotally supported together with the adjusting lever 50 on one brake shoe 20a via the stepped pin 15 and the retainer 16. A connecting portion 31 which is bent in a substantially J shape at its lower portion is connected to a mechanical operating means such as a cable or a link (not shown).

As shown in FIGS. 1 and 2, the brake lever 30
The intermediate portion of the strut 40 is housed in one of the stepped notches 41a of the sleeve member 41 of the strut 40, and the counterclockwise rotation of the brake lever 30 about the stepped pin 15 causes the strut 40 to move to the right and the other brake. As the shoe 20b expands, the stepped pin 15 rotates counterclockwise around the contact portion between the sleeve member 41 and the brake lever 30 as a fulcrum to expand one brake shoe 20a.

A contact portion 32 is formed in the middle of the inner side of the brake lever 30 so that the return position of the adjusting lever 50 can be regulated by engaging with the adjusting lever 50. Further, a protruding portion 33 is provided on the outer peripheral side of the free end of the brake lever 30, and the protruding portion 33 can be brought into contact with the inside of the shoe rim 21 to regulate the return position of the brake lever 30. ing.

<E> Adjusting lever The adjusting lever 50 includes a base portion 51, an adjusting arm 52 extending from the base portion 51, and an engaging arm 53 bent from the adjusting arm 52 toward the base portion 51 in substantially the same plane. The brake shoe 20a is integrally formed in a substantially U shape, and an upper portion thereof is rotatably supported by one brake shoe 20a by a stepped pin 15 common to the brake lever 30. An adjusting spring 60 is stretched between the hooking portion 51a formed at the free end of the base 51 and the brake lever 30, and the adjusting spring 60 urges the adjusting lever 50 in the returning direction (clockwise in FIG. 2). And adjust arm 52
The adjusting claw 52a formed at the tip of the is always elastically attached to the adjusting tooth 42a of the strut 40.

The shape of the adjusting lever 50 is not necessarily limited to the substantially U shape, and it is also conceivable that the engaging arm 53 is extended from the base 51, for example. Further, the adjustment spring 60 may be hooked on one brake shoe 20 a or the back plate 10 in addition to the brake lever 30.

A holding piece 51b formed by bending in a substantially U-shape on the inner peripheral side of the base portion 51 holds the brake lever 30 and prevents the adjusting lever 50 from separating from the brake lever 30. There is.

A buffer portion 53a which allows elastic deformation is formed at the free end of the engaging arm 53, and the buffer portion 53a is brought into contact with the contact portion 32 of the brake lever 30 to adjust the lever 50.
The turning position in the return direction (clockwise direction) can be regulated.

The shape of the buffer portion 53a is not limited to the substantially U shape,
Any shape is acceptable as long as it can be elastically deformed, and the buffer portion 53a
The formation position of is not limited to the free end of the engaging arm 53, and may be on the way.

[0029]

Next, the operation of the automatic gap adjusting device will be described.

<A> Non-braking FIG. 2 shows a front view of the drum brake device during non-braking. 1 and 2, the adjusting lever 50 has a base portion 51.
A rotating force acts clockwise around the stepped pin 15 by the spring force of the adjusting spring 60 acting on the adjusting spring 60, and the adjusting claw 52a formed on the adjusting arm 52 elastically contacts the adjusting tooth 42a of the strut 40 to move the adjusting tooth 42a. Prevents rotation. In this state, the buffer portion 53a of the engaging arm 53 that constitutes the adjustment lever 50 contacts the contact portion 32 of the brake lever 30, and the return position of the adjustment lever 50 is restricted. At this time, the adjusting spring 60 is attached to the engaging arm 53 of the adjusting lever 60.
Although the contracting force is applied, it can be absorbed by the elastic deformation of the buffer portion 53a, so that the adjusting lever 50 is unlikely to be settled or scraped.

<B> During braking: The connecting portion 3 of the brake lever 30 is mechanically operated.
1 tow the adjustment lever 50 to rotate the adjustment tooth 42a.
It is the same as before that the strut 40 is extended by rotating the and to automatically adjust the gap between the brake shoes 20a and 20b and the brake drum to a constant value. Further, when the brake lever 30 is actuated, the adjusting lever 50 is also integrally rotated, so that even if the periphery of the stepped pin 15 is fixed, the automatic gap adjusting action is not lost.

<C> Over-rotation of the brake lever During assembly to the vehicle or replacement of the brake shoes 20a, 20b, the gap between the brake shoes 20a, 20b and the brake drum becomes excessively large. When the vehicle is pulled, the brake lever 30 rotates excessively.
The adjusting lever 50 that abuts the abutting portion 32 of the brake lever 30 also tries to rotate excessively, but the adjusting lever 50 and the members facing the adjusting lever 50 (brake shoe, back plate, shoe return spring, wheel cylinder, etc.).
When a force of a certain amount or more is applied between and, the buffer portion 53a of the adjusting lever 50 is elastically deformed to prevent the adjusting lever 50 from over rotating.

[0033]

Second Embodiment In the first embodiment, when the adjusting lever 50 is returned (see FIG.
To the strut 4 by rotating the adjusting tooth 42a in the clockwise direction of
Although the case where 0 is extended has been described, it is also possible to apply to a form in which the strut 40 is extended by rotating the adjustment tooth 42a when the adjustment lever 50 is operated (counterclockwise direction in FIG. 5) as shown in FIG. Is. In this embodiment, the basic configuration of the adjusting lever 50 is the same as that of the first embodiment except that the operating direction of the adjusting lever 50 is different. Therefore, the same parts as those of the first embodiment are designated by the same reference numerals. And its description is omitted.

[0034]

Third Embodiment Further, the strut 40 in the above embodiment.
The configuration of FIG.
It is also conceivable to form the adjusting tooth 42a of No. 3 as the adjusting tooth 43a on the female screw member 43 as shown in FIG.

[0035]

Fourth Embodiment The present invention is an LT having both a hydraulic type and a mechanical type.
Besides the (leading / trailing) type, it can be applied to DS (duo servo) type and two-wheeled vehicles. The point is that at least a drum brake device having a mechanical automatic gap adjusting device can be applied.

[0036]

Since the present invention is as described above, the following effects can be obtained.

<B> Since the engaging arm that restricts the excessive rotation of the adjusting lever is provided with the cushioning portion that allows the elastic deformation, the force that strikes the adjusting lever and the member that opposes it with a certain amount or more. When acts, the buffer portion is elastically deformed, and an excessive impact force can be buffered and absorbed. Therefore, the adjusting lever is free from settling and scraping, and the durability is significantly improved.

<B> Even when the support shaft that supports the adjusting lever is fixed by abrasion powder or rust, the adjusting lever rotates integrally with the operation of the brake lever, so that the automatic gap adjusting operation is adjusted. There is no fear of being disabled.

<C> Even when the brake lever is actuated when the brake shoe gap is excessive during assembly to the vehicle or replacement of the brake shoe, the adjustment portion is adjusted by contacting the contact portion of the brake lever with the buffer portion of the adjustment lever. Since the excessive rotation of the lever can be restricted, it is possible to avoid interference, deformation, and damage between the adjustment lever and the member facing the adjustment lever.

[Brief description of drawings]

FIG. 1 is an explanatory diagram according to a first embodiment and is represented by I- in FIG.
Sectional view of I

FIG. 2 is a front view of a drum brake device.

[Fig. 3] Assembly drawing of adjustment lever and brake lever

4 is a sectional view of IV-IV in FIG.

FIG. 5 is an explanatory view of another embodiment in which the adjusting teeth are rotated when the adjusting lever is operated to extend the strut.

FIG. 6 is an explanatory view of another embodiment applied to a strut having adjusting teeth provided on an internal thread member.

[Explanation of symbols]

 10 ... Back plate 11 ... Wheel cylinder 12 ... Anchor part 13a ... Shoe return spring 13b ... Shoe return spring 14 ... Cable guide part 15 ... Stepped pin 16 ... Retainer 20a ... Brake shoe 20b ... Brake shoe 21 ... Shoe rim 22 ... Shoe web 23 ... Lining 30 ... Brake lever 31 ... Connection part 32 ... Abutment part 33 ... Overhanging part 40 ... Strut 41 ... Sleeve material 41a ... Stepped notch 42 ... Male screw member 42a ... Adjusting tooth 42b ... Adjusting tooth 43 ... Female screw Member 50 ... Adjusting lever 51 ... Base 51a ... Latching part 51b ... Holding piece 52 ... Adjusting arm 52a ... Adjusting claw 53 ... Engaging arm 53a ... Cushioning part 60 ... Adjusting spring

Claims (1)

[Claims] 1. Mounted between a pair of brake shoes,
One of the brake shoe and the strut that supports the brake shoe from the inner peripheral side in the notches formed at both ends and that has a male screw member and a female screw member, and has adjusting teeth formed on one of them. One of which is rotatably pivotally supported and is pivotally supported by the brake shoe by a brake lever that abuts on one end side of the strut to expand and open the pair of brake shoes, and a shaft common to the brake lever. An engaging arm formed at one end abuts on the brake lever so as to be integrally rotatable, and an adjusting claw formed at the other end returns the adjusting lever to engage with the adjusting tooth of the strut and the adjusting lever. When the amount of rotation of the adjusting lever exceeds a certain amount, the adjusting lever is biased in the direction and the adjusting spring of the adjusting lever is elastically attached to the adjusting teeth of the strut. In a drum brake device having an automatic clearance adjusting function in which the adjusting teeth are rotated to extend the struts and adjust the clearance of the brake shoes, the brake lever is rotated to rotate the adjusting lever and a member facing the adjusting lever. The drum brake device is characterized in that a buffer portion is formed in the engaging arm of the adjusting lever that abuts against the brake lever to allow elastic deformation when a force of a certain amount or more is applied to the brake lever.