JP2557725Y2 - Slack adjuster device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slack adjuster provided in a so-called S cam brake for a vehicle.

[0002]

2. Description of the Related Art As a drum brake for a vehicle, there is a so-called S cam brake provided with an S-shaped brake shoe expanding cam. This S cam brake has a slack adjuster device built in a lever that connects between a push rod extending from a brake chamber and a cam shaft of an S-shaped brake shoe expansion cam (hereinafter simply referred to as an S cam). doing.

This slack adjuster device includes a worm wheel mounted on a cam shaft, a worm gear housed in a lever and meshing with the worm wheel, a lock mechanism for preventing rotation of the worm gear, and the like. Support shafts are integrally formed at both ends of the worm gear, and rotatably support the worm gear. A plurality of recesses are formed in one of the support shaft portions. Each recess is formed side by side in the circumferential direction.

The lock mechanism is composed of a lock ball, a compression spring and the like, and is disposed between the lever and the one support shaft. The compression spring presses the lock ball from the radial direction of the worm gear. When the lock ball fits into one of the recesses, the lock mechanism imparts rotational resistance to the worm gear, thereby preventing rotation of the worm gear.

In this slack adjuster device,
By rotating the worm gear while removing the lock ball from the recess, the worm wheel, that is, the camshaft can be rotated. That is, by rotating the worm gear when the brake lining is worn, an increase in the rotation angle of the S cam due to the wear can be suppressed, and the rotation angle of the S cam can be adjusted to be constant. .

[0006]

[Problems to be Solved by the Invention] By the way, during braking, the worm wheel of the slack adjuster device
The impact force due to the reaction force of the brake drum may be transmitted. In this case, the worm wheel may rotate against the rotational resistance provided by the lock mechanism, and the phase of the S cam with respect to the brake shoe changes, so that the so-called shoe gap may increase. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a slack adjuster device capable of preventing an increase in a shoe gap due to a reaction force of a brake drum. .

[0008]

Means for Solving the Problems] According to the present invention in order to achieve the above object, the built-in lever for connecting the push rod and the blanking Rekishu extended camshaft of the cam extending from the brake chamber of the vehicular brake In this slack adjuster device, this slack adjuster
The worm device is housed in a worm wheel attached to a camshaft, is housed in a lever, meshes with the worm wheel, and is normally in a state where rotation is prevented by applying a predetermined rotational resistance, and the rotation is performed during adjustment. A possible worm gear and spring means provided between the lever and the worm gear to increase the rotational resistance ,
The spring means is located between the end face of the worm gear and the lever
And a first compression spring that presses the worm gear in the axial direction.
I have it .

The above object is also achieved by the above-described slack adjuster.
In place of the first compression spring for the spring means of the caster device, the following
It is possible to achieve even with such a configuration. In this case, the spring means
Is disposed between the lever and the worm gear, a concave portion provided in the shaft portion of the worm gear, and a lock ball fitted into the concave portion, and disposed concentrically between the lock ball and the lever, and the radial direction of the worm gear and and a second and third compression spring against the recess of the locking balls from.

[0010] Further preferably, a first compression spring is provided.
Spring means comprises a recess provided in the shaft portion of the worm gear is disposed between the lever and the worm gear, and a lock ball fits into the recess, is disposed between the lock ball and the lever, the axis of the worm gear It is desirable to have a fourth compression spring having an action line offset to the lock ball and pressing the lock ball against the concave portion.

[0011]

When the vehicle is braked, an impact force due to the reaction force of the brake drum may be transmitted to the worm gear of the slack adjuster, and the impact force tends to rotate the worm gear. In the slack adjuster device of the present invention, the rotational resistance given to the worm gear is
The spring means further increases.

For example, when a first compression spring that presses the worm gear in the axial direction is provided as the spring means, the first compression spring presses the worm gear against the inner surface of the lever or the worm wheel to increase the rotation resistance. . In the case where the spring means includes a concave portion provided in the shaft portion of the worm gear, a lock ball fitted into the concave portion, and second and third compression springs for pressing the lock ball from the radial direction of the worm gear toward the concave portion. In the method, the rotational resistance of the worm gear generated by the second compression spring pressing the lock ball is increased by the third compression spring pressing the lock ball more strongly.

In addition to the first compression spring,
The spring means having a lock ball and a fourth compression spring.
In this configuration , the fourth compression spring obliquely presses the lock ball against the concave portion, and a rotational moment in a direction opposite to the rotational direction of the worm gear is generated by the impact force, thereby increasing the rotational resistance of the worm gear.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of an S cam brake to which the slack adjuster device according to the present invention is applied. A push rod 3 extending from a brake chamber 2 of the S cam brake 1 and an S cam for expanding a pair of brake shoes 4 are shown.
In the lever 11 connecting the cam 5 to the camshaft 6 (FIG. 2), a slack adjuster device 20 shown in FIG.
Is built-in.

When the driver depresses a brake pedal (not shown), the lever 11 opens the brake chamber 2.
Is rotated. When the lever 11 rotates, the camshaft 6 rotates and the S cam 5 causes each brake shoe 4 to expand. As shown in FIG. 2, a space for accommodating the slack adjuster device 20 is formed inside the lever 11. This space includes a wheel housing space 12 and a worm gear housing space 13.
The wheel accommodating space 12 includes a worm wheel 2 described later.
It is set slightly larger than 4. One end of the camshaft 6 is inserted into the wheel housing space 12. Further, the worm gear housing space 13 is
It is set slightly larger than the gear portion 25a of the worm shaft 25, which will be described later, and communicates with the outside of the lever 11 through the shaft holes 15 and 16.

Further, a hole 17 is formed in the lever 11. The hole 17 opens in the middle of one shaft hole 15 and extends in the radial direction to open on the outer surface of the lever 11. This hole 17 is closed by a plug 22. The plug 22 is screwed and fixed to the hole 17. The slack adjuster device 20 includes a worm wheel 24, a worm shaft 25, a lock mechanism 27, a spring means 28, and the like. The worm wheel 24 is disposed in the wheel housing space 12 and is spline-fitted to one end of the camshaft 6.

The worm shaft 25 includes a gear 25a.
And shaft portions 25b and 25c extending from both ends of the gear portion 25a, respectively, which are integrally formed and extend along the same axis. Gear part 25a
Are arranged in the worm gear housing space 13. Further, each of the support shaft portions 25b and 25c is provided with each of the shaft holes 1.
5 and 16 are rotatably inserted. One spindle 2
5b protrudes to the outside of the lever 11, and a bolt head 25d is formed on the protruding portion. Also,
At the position facing the hole 17 of the support shaft portion 25b, concave portions 25e are formed at six positions at equal intervals in the circumferential direction (FIG. 3). On the other hand, the end surface of the other support shaft portion 25c is
6 is located substantially at the center in the axial direction.

As shown in FIG. 3, the lock mechanism 27 includes a lock ball 30, a compression spring 31, and the like, which are housed in a hole 17 formed in the lever 11. The compression spring 31 is disposed between the plug 22 and the lock ball 30, and pushes the lock ball 30 from the radial direction into the recess 2.
5e. That is, the action line F of the compression spring 31
1 is set so as to pass through the center O of the transverse section of the worm shaft 25.

As shown in FIG. 4, the spring means 28 comprises a snap ring 33, a plate 34 and a compression spring 35, which are housed in the other shaft hole 16. The compression spring 35 is disposed between the plate 34 and the support shaft 25c, and presses the end face of the support shaft 25c in the axial direction. Therefore, the gear portion 25 of the worm shaft 25
a is pressed against the inner surface of the lever 11 and the worm wheel 24.

Hereinafter, the operation will be described. The lock ball 30 of the lock mechanism 27 is moved by the compression spring 31 to the support shaft portion 25b.
Of the worm shaft 25, and imparts rotational resistance to the worm shaft 25. Further, the compression spring 35 of the spring means 28 presses the gear portion 25a against the inner surface of the lever 11 or the worm wheel 24 to increase the rotation resistance.

While the braking force is transmitted to the worm shaft 25 during braking, the rotational resistance is increased. The worm shaft 25 is hard to rotate. When the phase of the S cam 5 with respect to each brake shoe 4 is adjusted by the slack adjuster device 20, the bolt head 25d of the worm shaft 25 is rotated while the compression spring 31 of the lock mechanism 27 is contracted. When the bolt head 25d rotates, the gear 25
As a rotates, the worm wheel 24, that is, the S cam 5 rotates. Thus, the phase of the S cam 5 can be adjusted according to the state of wear of the lining of each brake shoe 4.

Next, a second embodiment of the slack adjuster device to which the present invention is applied will be described. In the slack adjuster device 40 shown in FIG. 5, the function of the spring means 28 of the slack adjuster device 20 shown in FIG. Therefore, in the slack adjuster device 40, the slack adjuster device 2 described above is used.
The spring means corresponding to the spring means 28 provided at 0 is omitted.

The lock mechanism 42 includes a lock ball 43, a compression spring 44, and the like, similarly to the lock mechanism 27 of the slack adjuster device 20 described above. However, in the lock mechanism 27 described above, the lock ball 3
6, the compression spring 31 presses the lock ball 43 obliquely with respect to the radial direction, as shown in FIG.

That is, the action line F2 of the compression spring 44 is offset by the distance L from the axis of the worm shaft 25, that is, the center O of the transverse section of the worm shaft 25. The direction of this offset is set to a direction in which a rotational moment is generated in the direction of arrow CC as shown in the figure. This rotational moment is set to a predetermined magnitude, and is not large enough to rotate the worm shaft 25.

An impact force may be transmitted to the worm shaft 25 when the vehicle is being braked. Since the impact force is caused by a reaction force of the brake drum, the worm shaft 25 is connected to the so-called shoe gap. An attempt is made to rotate in the increasing direction (the direction of arrow C in the figure). Hereinafter, the operation will be described.

The line of action F2 of the compression spring 44 corresponds to the center O
, The lock ball 43 is pressed obliquely against the recess 25e to generate a rotational moment in the direction of arrow CC in the figure. The direction of the rotational moment is opposite to the direction in which the shoe gap increases. Therefore, the lock mechanism 42
Generates the rotational moment in addition to the rotational resistance of the worm shaft 25 generated by fitting the lock ball 43 into the concave portion 25e. That is, the rotational resistance increases the rotational resistance, and the rotation of the worm shaft 25 is prevented.

Next, a third embodiment of the slack adjuster device to which the present invention is applied will be described. The slack adjuster device 50 differs from the slack adjuster device 40 shown in FIG. 5 in the configuration of the lock mechanism. As shown in FIG. 7, the lock mechanism 52 of the slack adjuster device 50 includes a lock ball 53, a spring seat 54, three compression springs 55 to 57, and the like. Also, lever 1
A cylindrically extending spring seat 55a is integrally formed on the inner end surface of the plug 55 which is screwed and fixed to the one hole 17 and closes the plug. The hole 17 extends in the radial direction of the worm shaft 25, similarly to the hole 17 shown in FIG.
The lock ball 53 is pressed from the radial direction.

The first compression spring 55 is disposed between the plug 55 and the lock ball 53, as in the case of the compression spring 31 shown in FIG. 3, and presses the lock ball 53 against the recess 25e. Also, the second and third compression springs 56, 57
It is shorter than the first compression spring 55 and has a smaller diameter. These second and third compression springs 56, 57
The compression spring 55 is arranged inside the compression spring 55 in the axial direction. Therefore, the second and third compression springs 56, 57
It is arranged concentrically with the compression spring 55. The set load of the second and third compression springs 56 and 57 is set smaller than the set load of the first compression spring 55.

Hereinafter, the operation will be described. The first compression spring 55 of the lock mechanism 52 is
The lock ball 53 is pressed against e to impart rotational resistance to the worm shaft 25. Similarly to the first compression spring 55, the second and third compression springs 56 and 57 press the lock ball 53 against the recess 25e to increase the rotation resistance.

That is, when the vehicle is braked, the impact force caused by the reaction force of the brake drum is applied to the worm shaft 25.
Is transmitted to the worm shaft 25 and the lock ball 5
3 is pushed into the hole 17 and tries to rotate in a direction to increase the shoe gap. Second and third compression springs 5
6 and 57, since the set load is smaller than that of the first compression spring 55, the impact force is small.
When the amount of contraction is small, mainly the first compression spring 55, and when the impact force is large, and when the amount of contraction is large, each compression spring 55 to 57 presses the lock ball 53 to rotate the rotation. Generate resistance.

Therefore, when the impact force transmitted to the worm shaft 25 is large, the rotation resistance applied to the worm shaft 25 increases, and the rotation of the worm shaft 25 is prevented. The second and third compression springs 56, 5
7 is set shorter than the first compression spring 55, so that when the compression springs 55 to 57 contract, they do not interfere with each other.

[0032]

[Effect of the Invention] As described above, according to the present invention ,
The rack adjuster reduces the rotational resistance of the worm gear.
In increasing, the spring means with the first compression spring or the
The spring means having the second and third compression springs.
Thus, rotation of the worm gear caused by the reaction force of the brake drum can be prevented. As a result, there is an excellent effect that the increase in the shoe gap caused by the reaction force of the brake drum can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of an S cam brake of a vehicle to which a slack adjuster device according to the present invention is applied.

FIG. 2 is a sectional view showing a first embodiment of the slack adjuster device according to the present invention.

FIG. 3 is a cross-sectional view of the slack adjuster device taken along a line III-III in FIG. 2;

FIG. 4 is an enlarged view of a portion indicated by an ellipse IV in FIG. 2;

FIG. 5 is a sectional view showing a second embodiment of the slack adjuster device according to the present invention.

6 is a cross-sectional view of the slack adjuster device taken along the line VI-VI in FIG.

FIG. 7 is a sectional view of a third embodiment of the slack adjuster device according to the present invention, corresponding to FIG. 6;

[Explanation of symbols]

 Reference Signs List 1 S cam brake 2 Brake chamber 3 Push rod 4 Brake shoe 5 S cam 6 Cam shaft 11 Lever 20, 40, 50 Slack adjuster device 24 Worm wheel 25 Worm shaft 28 Spring means 30, 43 Lock ball 31, 35, 44, 55 ~ 57 Compression spring 42 Lock mechanism

Claims (2)

(57) [Scope of request for utility model registration] 1. A slack adjuster device built into a lever for connecting the push rod and the blanking Rekishu expansion cam of a cam shaft extending from the brake chamber of the vehicle brakes, and the worm wheel mounted on the camshaft, It is housed in the lever and meshes with the worm wheel, and is normally in a state where rotation is prevented by applying a predetermined rotational resistance, and is provided between the lever and the worm gear, which is rotatable at the time of adjustment. Spring means for increasing the rotational resistance , wherein the spring means
Is located between the end face of the worm gear and the lever.
A slack adjuster device comprising a first compression spring that presses the worm gear in the axial direction . 2. A brake chamber for a vehicle brake.
Extension push rod and cam for brake shoe extension cam
Built into the lever that connects the
In click adjuster device, a worm wheel mounted on the camshaft, Les
It is housed in the bar and meshes with the worm wheel, usually
Rotation is hindered by the given rotation resistance.
A worm that is stopped and rotatable during adjustment
Gear, and between the lever and the worm gear,
Spring means for increasing rolling resistance, said spring means
Is a recess provided in the shaft of the worm gear,
A lock that is located between the worm gear and the recess
Concentrically between the ball and the rock ball and lever.
The lock ball is recessed from the radial direction of the worm gear
And second and third compression springs that press against
Slack adjuster device according to claim.