JP2573857Y2 - Drum brake with automatic shoe clearance adjustment - Google Patents

Description

[Detailed description of the invention]

[0001]

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

[0002]

2. Description of the Related Art A pair of brake shoes having a circular arc-shaped shoe rim and a plate-shaped shoe web protruding from an inner peripheral surface of the shoe rim, and arranged on a backing plate so as to be able to expand each other, An adjusting member which is formed in a longitudinal plate shape and is rotatably provided at one end to a shoe web of one of the brake shoes, and is bridged between the two brake shoes to form a longitudinal shape, and one end of which A strut for sandwiching the shoe web of the brake shoe and the longitudinal middle portion of the adjusting member in the plate thickness direction, and a strut rotatably provided on the shoe web of one of the brake shoes and formed at the tip end of the adjusting member. Engage with the denture,
There is known a drum brake with a shoe gap automatic adjusting mechanism of a type including a latching member that allows the adjusting member to rotate in the shoe gap decreasing direction but prevents the turning in the opposite direction. Japanese Utility Model Application Laid-Open No. 63-1 filed and filed by the present applicant.
No. 8639 discloses that.

[0003]

However, in such a drum brake with an automatic shoe clearance adjusting mechanism, the drum brake is provided on one of the adjusting member and the shoe web so that the adjusting member can be rotatably attached to the shoe web. And the clearance between the adjusting member and the shoe web and the fitting hole formed in the other of the adjusting member and the shoe web, and the opposing inner walls of the adjusting member and the shoe web and one end of the strut sandwiching them. In some cases, due to the clearance between the adjusting member and the shoe, the adjusting member may play a relatively large amount in the direction away from the shoe web toward the tip end side with the pin as a fulcrum. In such a case, the engagement position between the engagement teeth of the adjustment member and the latch member is shifted, the engagement area is reduced, and the rotation is prevented by the adjustment member via one end of the strut. When a force is applied, the engaging teeth and the engaging member may be damaged or deformed, or the engaging teeth of the adjusting member may be disengaged from the engaging member. It is.

On the other hand, for example, as described in Japanese Utility Model Laid-Open Publication No. 3-68639 filed by the present applicant, one end of the strut is located on the opposite side of the adjusting member from the shoe web. The above problem can be preferably solved by providing a protruding portion that protrudes toward the distal end side of the adjusting member at a portion to be adjusted, and by controlling the floating of the distal end portion of the adjusting member away from the shoe web by the protruding portion. It can be prevented. However, even in this case, there are still problems to be solved. That is, since one end of the strut provided with the protrusion is engaged with the intermediate portion in the longitudinal direction of the adjustment member, if the protrusion is short, the tip of the adjustment member will not float up in the direction away from the shoe web. It is difficult to sufficiently suppress the lift, and if the protrusion length of the protrusion is increased in order to more appropriately suppress the lift, there is a disadvantage that the weight of the strut and, consequently, the weight of the drum brake increases, and the protrusion If the protruding portion is formed as a separate member from the strut in order to increase the length, the number of parts of the drum brake increases.
In addition, the strut usually has rattling around the axis, and the rattling of the strut causes the protrusion provided on the strut to rattle in a direction approaching and separating from the adjusting member. It is not always possible to sufficiently suppress the lifting.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object the purpose of the present invention to provide a shoe web having a tip portion which meshes with a hook member of an adjusting member rotatably provided on a shoe web. It is an object of the present invention to provide a drum brake with an automatic shoe clearance adjusting mechanism which can suppress the floating in the direction away from the web without increasing the number of parts and weight of the drum brake and more suitably at the tip end side of the adjusting member. .

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is as follows. (A) An arc-shaped shroud
-Rim and plate-shaped protruding from the inner peripheral surface of the shoe rim
Of shoe webs on a backing plate
A pair of brake shoes arranged so as to be expandable, and (b) a length
Formed as a hand plate and used as a shoe web for one brake shoe
An adjusting member rotatably provided at one end, and (c)
It is spanned between a pair of brake shoes forming a longitudinal shape,
At one end, the adjusting member has a predetermined gap.
And a pair of brake shoes
Struts that define the position when the diameter is reduced, and (d) the struts
The brake shoe opposite to the one brake shoe
And (e) one of the brakes.
It is rotatably provided on the shoe web of
Engage with the engagement teeth formed at the tip of the joint member, and adjust the engagement teeth.
The rotation of the member in the direction of reducing the shoe gap is allowed, but the rotation in the opposite direction is allowed.
(F) the pair of shakers.
-When the shoe is expanded, the strut and the adjusting member
Are engaged, and the adjusting member moves in the shoe clearance decreasing direction.
By being rotated, the pair of brake shoes
In the drum brake with an automatic shoe gap adjusting mechanism of automatically adjusting the shoe gap by separating the positions at the time of diameter reduction, at least one of the shoe web and the shoe rim of the one brake shoe is cut off. The adjusting member is formed on the opposite side from the shoe web so as to cover a part of the adjusting member from the side opposite to the shoe web and to suppress the floating of the tip of the adjusting member in the direction away from the shoe web. That is, a rise suppressing portion is provided.

[0007]

In this manner, the adjusting member rotatably provided on the shoe web of one of the brake shoes is loose in the direction approaching and separating from the shoe web with the rotation center side as a fulcrum. Even if it is used, a part of the tip end side (locking member side) of the adjusting member is brought into contact with the lift suppressing portion provided on at least one of the shoe web and the shoe rim of the one brake shoe. Based on this, it is possible to suitably suppress the tip of the adjustment member from rising in the direction away from the shoe web. In this case, since the lift suppressing portion is formed based on cutting and raising at least a part of at least one of the shoe web and the shoe rim of the brake shoe, the above-described effect can be obtained without increasing the number of parts and weight of the drum brake. can get. In addition, since the lift suppressing portion is configured to abut against the distal end portion of the adjusting member to suppress the floating of the distal end portion of the adjusting member, and is formed integrally with the brake shoe and has no backlash, The lifting of the distal end of the adjusting member can be more suitably suppressed as compared with the case where a protruding portion as a lifting suppressing portion is provided at one end of the strut.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a view showing an example of a drum brake having an automatic shoe gap adjusting mechanism to which the present invention is applied.
A pair of brake shoes 12, 14 are supported on the backing plate 10 by shoe hold-down devices 16, 18 so as to be able to expand from each other. Brake shoe 1
Reference numerals 2 and 14 denote a shoe rim 20 formed by bending a plate material in an arc shape, a plate-shaped shoe web 22 protruding from an inner peripheral surface of the shoe rim 20 , and a lining 24 fixed to an outer peripheral surface of the shoe rim 20. And each is provided. Opposite ends of the shoe webs 22 of the brake shoes 12 and 14 are connected to anchors 2 fixed on the backing plate 10.
6, and the other ends of the shoe webs 22 of the brake shoes 12, 14 are respectively engaged with a pair of pistons (not shown) of a wheel cylinder 28 fixed on the backing plate 10. Have been combined. As a result, the hydraulic pressure is supplied into the wheel cylinder 28, and the pistons protrude in the direction away from each other, whereby the brake shoes 12, 14 are expanded and pressed against the inner peripheral surface of the rotating drum (not shown). Braking is performed.

A parking brake lever 32 having a parking cable 30 connected to one end thereof is rotatably attached to a shoe web 22 of one brake shoe 12 by a pin 34 at the other end. As shown in FIGS. 1 and 2, the shoe web 22 of the other brake shoe 14 is provided with an adjusting member 38 having a long plate shape and having an engaging tooth 36 at a tip end thereof.
0 and a locking member 44 having a locking tooth 42 is rotatably mounted by a pin 46, and the locking member 44 is locked by a torsion spring 48. Reference numeral 42 is constantly urged in a rotational direction (clockwise direction in FIG. 2) in which the engaging member 36 engages with the engaging teeth 36. As a result, the engaging teeth 36 and the locking teeth 42
The rotation of the adjusting member 38 in the shoe clearance decreasing direction (clockwise direction in FIG. 2) is permitted by the engagement with the control member 38, but the opposite rotation in the shoe clearance increasing direction is prevented. Hanging member 4
The mounting position of No. 4, the shapes of the engaging teeth 36 and the engaging teeth 42, and the like are determined in advance as such. In the present embodiment, as shown in FIG. 1, the pin 40 is protruded from the adjusting member 38, and the pin 40 has a predetermined clearance in a hole 50 formed in the shoe web 22. It is inserted and stopped by the retaining ring 52.

A strut 54 in the form of a long plate is bridged between the brake shoes 12 and 14 at a position located on the wheel cylinder 28 side. Notches 56 (only one is shown in FIG. 1) are provided at both ends of the strut 54, and the shoe web 2 of the brake shoe 14 is provided in the notch 56 at one end of the strut 54.
2 and the intermediate portion in the longitudinal direction of the adjusting member 38 are sandwiched with a predetermined clearance, and the strut 54
The shoe web 22 of the brake shoe 12 and the parking brake lever 32 in the notch 56 on the other end side of the
Are sandwiched with a predetermined clearance. Thus, when the parking brake lever 32 is rotated counterclockwise in FIG.
When the pin 34 is rotated counterclockwise in FIG. 2 with the contact point with the other end of the brake shoe as a fulcrum, one of the brake shoes 1
2 is pushed to the outer peripheral side, and the strut 54 is moved rightward in FIG. 2 to push the brake shoe 14 to the outer peripheral side via the adjusting member 38 and the like, the rotation of which is prevented by the latching member 44. The braking is performed in the same manner as in the case of the wheel cylinder 28.

The strut 54 and the brake shoe 12
A spring 58 for constantly urging the strut 54 toward the brake shoe 12 is stretched between the brake shoe 12 and the brake shoe 1 by the wheel cylinder 28.
The struts 54 are moved together with the brake shoes 12 in a direction away from the brake shoes 14 when the two and 14 are expanded. Spring 58 is a biasing hand
Corresponds to a column. An engagement projection (not shown) projecting into the cutout 56 is provided at the one end of the strut 54, and the engagement projection is formed in an engagement hole ( (Not shown) with a predetermined gap. Thereby, the wheel cylinder 2
When the brake shoes 12 and 14 are expanded by using the linings 8, the struts are
The adjusting member 38 is rotated clockwise in FIG. 2 via the engaging projection by the engagement protrusion 54, and a gap (a shoe gap) between the outer peripheral surfaces of the brake shoes 12, 14 and the inner peripheral surface of the rotary drum is provided. ) Exceeds a predetermined value, the engaging teeth 36 of the adjusting member 38 ride over one engaging tooth 42 of the engaging member 44 and the return position of the adjusting member 38 is updated in the shoe clearance decreasing direction. It has become. In FIG. 2, reference numeral 60 denotes a shoe return spring that is stretched between the brake shoes 12 and 14 and constantly urges them in the diameter reducing direction.

When the drum brake constructed as described above is not braked, the opposing side end surfaces of the parking brake lever 32 and the adjusting member 38 and the strut 54
The diameter of the brake shoes 12, 14 is reduced by the shoe return spring 60 based on the contact with the both ends of the adjusting member 38.
A force corresponding to the urging force of the shoe return spring 60 is applied to the latching teeth 42 of. On the other hand, at the time of parking brake braking, the parking brake operation force is transmitted from the strut 54 to the brake shoe 14 via the adjusting member 38, the rotation of which is prevented by the locking member 44, so that the engaging teeth of the adjusting member 38 A relatively large force corresponding to the parking brake operating force is applied to the engaging teeth 36 of the engaging member 36 and the engaging member 44.

Here, in this embodiment, FIG.
As shown in FIG. 3 to FIG. 3, a part of the shoe web 22 is cut and raised toward the backing plate 10 at a portion of the brake shoe 14 located on the tip end side of the shoe web 22, and the adjusting member is A lifting suppressing portion 62 for suppressing the rising of the distal end of the shoe 38 in the direction away from the shoe web 22 is integrally formed. The lifting suppressing portion 62 projects from the shoe web 22 toward the backing plate 10 and
Protruding portion 64 located on the opposite side of the pin 40 of the engagement tooth 36
And extends from the tip of the projection 64 to the pin 40 side substantially in parallel with the plate surface of the shoe web 22 to cover a portion of the adjustment member 38 on the tip end side with a predetermined gap from the side opposite to the shoe web 22. A cover 66 is provided, and the lifting of the tip of the adjustment member 38 is suppressed based on the contact between the cover 66 and the tip of the adjustment member 38.
The formation position of the lifting restraint portion 62 in the turning direction of the adjusting member 38 (substantially radial direction of the brake shoe 14) and the width dimension of the cover portion 66 in the turning direction of the adjusting member 38 are determined by the lining 24 of the brake shoes 12, 14. The maximum allowable rotation of the adjusting member 38 in the direction of reducing the shoe gap so that the lifting of the distal end of the adjusting member 38 can be suitably suppressed and the strength of the shoe web 22 can be suitably maintained even during the maximum allowable wear of the shoe. It is determined in advance in relation to the moving position and the shape of the distal end of the adjustment member 38. A projection 68 is provided on the surface of the cover 66 on the shoe web 22 side so as to protrude substantially along the rotation direction of the adjustment member 38.
8.

As described above, according to the present embodiment, the adjusting member 3
8 due to the clearance between the pin 40 projecting from the hole 8 and the hole 50 and the clearance between the opposing inner walls of the notch 56 at one end of the strut 54 and the shoe web 22 and the adjusting member 38. Even if the member 38 rattles in the direction approaching and separating from the shoe web 22 with the pin 40 side as a fulcrum, the tip of the adjusting member 38 on the side of the engaging tooth 36 is provided on the shoe web 22.
Of the adjusting member 38 in the direction away from the shoe web 22 (in the direction indicated by the arrow A in FIG. 1) based on being brought into contact with the cover portion 66. . In FIG. 1, the dashed line indicates the maximum floating position of the adjusting member 38 in the case of the present embodiment in which the lifting suppression portion 62 is provided, and the two-dot chain line indicates the conventional case in which the lifting suppression portion 62 is not provided. 5 shows the maximum floating position of the adjusting member 38 in FIG. Note that the maximum lifting position in the case where the lifting suppressing portion 62 is not provided is based on the assumption that there is no backlash around the axis of the strut 54. Based on the backlash around the center, it becomes even larger than the floating position indicated by the two-dot chain line. As a result, the floating position of the distal end portion of the adjusting member 38 is appropriately suppressed. As a result, the engaging teeth 36 of the adjusting member 38 and the engaging members 44
Can be more suitably maintained with the engaging teeth 42 than before, so that a relatively large force is applied to the engaging teeth 36 and the engaging teeth 42 during non-braking or parking brake braking. However, the engagement teeth 36 and the locking teeth 42 can be suitably prevented from being damaged or deformed, and the engagement teeth 36 and the locking teeth 42 can be prevented.
Is prevented from being disengaged.

Further, according to the present embodiment, the lift suppressing portion 62 is formed based on cutting and raising a part of the shoe web 22, so that the number of parts and the weight of the drum brake are not increased. The effect is obtained.

Further, according to the present embodiment, the lifting suppressing portion 62 suppresses the floating of the distal end portion of the adjusting member 38 by bringing the cover portion 66 into contact with the distal end portion of the adjusting member 38. And since it is formed integrally with the shoe web 22 and has no backlash, a protruding portion is provided at one end of the strut which engages with the intermediate portion in the longitudinal direction of the adjusting member so as to protrude toward the distal end of the adjusting member. As compared with the conventional case in which the protruding portion functions as the lifting suppressing portion, the rising of the distal end portion of the adjusting member 38 can be more suitably suppressed.

Further, according to the present embodiment, the projection 68 provided on the cover 66 of the lift suppressing portion 62 along the rotating direction of the adjusting member 38 is configured to be brought into contact with the adjusting member 38. Therefore, when the adjustment member 38 rotates, the protrusion 6
There is an advantage that the sliding resistance of the adjusting member 38 does not increase so much even when the adjusting member 38 slides.

It should be noted that in the above-described embodiment, the lifting restraint 6
The two protrusions 64 are provided on the shoe web 22 at the tip of the adjustment member 38 on the side opposite to the pins 40, but may be provided on the shoe web 22 between the tip of the adjustment member 38 and the shoe rim 20. .

In the above-described embodiment, the lifting restraint 6
The second cover 66 is formed so as to be brought into contact with only the tip of the adjusting member 38, but this is not always necessary. For example, as shown in FIG. It is also possible to provide a lift suppressing portion 72 having a cover portion 70 that can be in contact with the tip of the 44. With this configuration, it is possible to appropriately suppress the floating of the tip end of the hooking member 44 in the direction away from the shoe web 22, so that the engaging teeth 36 of the adjusting member 38 and the hooking teeth 42 of the hooking member 44. Thus, it is possible to more reliably prevent the engagement teeth 36 and the locking teeth 42 from being damaged, deformed, and disengaged during non-braking or parking brake braking. Can be.

In the above-described embodiment, the lifting restraint 6
2 is formed by cutting a part of the shoe web 22 of the brake shoe 14 toward the backing plate 10, but this is not always necessary, and a part of the shoe rim 20 of the brake shoe 14 is The lifting suppression portion may be formed based on the cut-off, or the lifting suppression portion may be provided on both the shoe web 22 and the shoe rim 20.

In the above-described embodiment, the adjusting member 38 is rotatably provided in a state where the pin 40 projecting from the adjusting member 38 is inserted into the hole 50 of the shoe web 22 with a predetermined gap. However, the adjustment member is not necessarily required. For example, the adjustment member is rotatably provided in a state where a pin protruding from the shoe web 22 is inserted through a hole of the adjustment member with a predetermined gap. In this case, the effect of the present invention can be obtained.

In the above-described embodiment, the effects of the present invention can be obtained even when the parking brake lever 28 and the parking cable 32 are not provided.

In addition, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is an enlarged view of an adjusting member, a latching member, and the like in FIG. 2 viewed from a side opposite to a parking brake lever, and is a diagram in which a part of a brake shoe and the like is cut away.

FIG. 2 is a view showing an example of a drum brake with an automatic shoe gap adjusting mechanism to which the present invention is applied, and is a view showing a main part.

FIG. 3 is a view taken in the direction of the arrow III in FIG. 1, showing a main part.

FIG. 4 is a diagram showing another example of the present invention, and is a diagram corresponding to FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Backing plate 12, 14 Brake shoe 20 Shoe rim 22 Shoe web 36 Engaging tooth 38 Adjusting member 44 Hook member 54 Strut 58 Spring (biasing means) 62, 72 Lifting restraining part

Claims (1)

(57) [Scope of request for utility model registration] 1. A shoe rim having an arc shape and a plate-shaped shoe web protruding from an inner peripheral surface of the shoe rim,
A pair of brake shoes arranged on the backing plate so as to be expandable with each other, an adjusting member having a longitudinal plate shape, and being rotatably provided at one end to a shoe web of one of the brake shoes; the bridged between the pair of brake shoes to form, in the control member at one end
While being engaged with a predetermined gap,
A strap that defines the position of the pair of brake shoes when the diameter is reduced
And the strut opposite the one brake shoe
A biasing means for constantly biasing the brake shoe toward the brake shoe; and an engaging tooth rotatably provided on the shoe web of the one brake shoe and engaging with an engaging tooth formed at a tip end of the adjusting member, and A locking member for allowing rotation of the member in the direction of decreasing the shoe gap but preventing rotation of the member in the opposite direction;
-When the shoe is expanded, the strut and the adjusting member
Are engaged, and the adjustment member rotates in the shoe clearance decreasing direction.
Being moved, the pair of brake shoes shrink.
In a drum brake with an automatic shoe gap adjusting mechanism of a type in which a shoe gap is automatically adjusted by separating a position at the time of diameter, formed based on cutting and raising at least a part of at least one of a shoe web and a shoe rim of the one brake shoe. And a lifting suppressing portion that covers a part of the distal end portion side of the adjusting member from the side opposite to the shoe web and suppresses floating of the distal end portion of the adjusting member in a direction away from the shoe web. A drum brake with an automatic shoe clearance adjusting mechanism.