JPH0710106Y2 - Drum brake - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake, and more particularly to a drum brake having a parking brake mechanism.

2. Description of the Related Art Conventionally, in a drum brake equipped with a parking brake mechanism, a parking lever is rotatably provided on one of a pair of brake shoes that are arranged on one side of a backing plate so as to be able to open each other. And a strut is laid between the parking lever and the other brake shoe, and an L-shaped bell crank is attached to the one side of the backing plate on the other side of the backing plate. The bell crank is rotatably provided at an intermediate portion, and one end of the bell crank and the parking lever are connected by a connecting member and a parking cable is connected to the other end of the bell crank. Then, when the parking brake operation force is applied and the parking cable is pulled in, the bell crank is rotated and the parking lever is rotated through the connecting member, so that the parking lever and the strut both brake shoes. Are designed to be spread apart from each other.

However, the rotating part of the bell crank is usually
Since it will be exposed to the outside on the other side of the backing plate, in order to prevent rusting etc. of its rotating part, attach a relatively large dust boot to the bell crank or protect it from the surface of the bell crank etc. Although rust treatment is performed, if rust prevention treatment is not sufficient, the dust boot is damaged, or the sealing property between the dust boot and the bell crank is insufficient, such a case may occur. In some cases, even if rust prevention measures were taken, it was not possible to reliably prevent rust on the rusted part of the rotating part of the bell crank.

Further, in the above-mentioned drum brake, the parking brake operating force is transmitted to the brake shoe through many parts such as the parking cable, the bell crank, the connecting member, the parking lever, and the strut, so that the transmission efficiency of the parking brake operating force is improved. There was a problem that it was hard to get enough.

On the other hand, the applicant of the present application filed in Japanese Patent Application No. 63-1146
As described in No. 35, there is a backing plate and one of the backing plates, which has a first contact portion which is located between one end portions of a pair of brake shoes and is brought into contact with one end portion of the brake shoes. Between the brake shoes of
A moving member that is guided in a direction perpendicular to a straight line that connects the center of the backing plate and the center of the anchor pin that is located between the ends of the pair of brake shoes, and those brakes that are positioned between the ends of the pair of brake shoes. A second contact portion that is brought into contact with the other end portion of the shoe, and a second portion thereof.
The abutting portion projects from the end on the backing plate side to the side opposite to the moving member side and is positioned between the backing plate and the other brake shoe to connect the parking cable to the projecting end and the projecting end. It is considered that the above problem can be suitably solved if the drum brake is configured to include a bell crank having a longitudinal portion operatively connected to the moving member on the side opposite to the side.

However, even in this case, there is still a problem to be solved. That is, the first abutting portion of the moving member and the second abutting portion of the bell crank are usually arranged between the one ends of the pair of brake shoes with a slight play when not braking. Therefore, there is a possibility that the moving member and the bell crank may vibrate when the vehicle is traveling to generate an abnormal noise.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a drum brake including a parking brake mechanism including a moving member and a bell crank as described above. It is to provide a technique for suppressing abnormal noise caused by vibration of a bell crank.

Means for Solving the Problems In order to achieve the above object, the present invention has an arc shape,
A pair of brake shoes arranged so as to be capable of expanding relative to each other on the backing plate, and a pair of brake shoes which are positioned between opposite one ends of the pair of brake shoes and are brought into contact with one end of both brake shoes. A moving member having one contact portion and being guided between the backing plate and one brake shoe thereof in a direction perpendicular to a straight line connecting the center of the backing plate and the center between one end portions of the pair of brake shoes; A second contact portion positioned between one end portions of the pair of brake shoes and brought into contact with the other end portions of both brake shoes, and a moving member from the end portion of the second contact portion on the backing plate side And the parking cable is connected to the protruding end side so as to project toward the opposite side and to be located between the backing plate and the other brake shoe. And a bell crank having a longitudinal shaped portion which is operatively connected to the moving member in the opposite side of the protruding end portion side, the parking cable by the based on rotating the bell crank in one direction a second
A drum brake of the type in which the other brake shoe is pushed to the outer peripheral side by the abutting portion and the one brake shoe is pushed to the outer peripheral side by the first abutting portion of the moving member. Bias provided between the brake shoe and / or between the bell crank and the one brake shoe to constantly bias the moving member and the bell crank toward the other brake shoe and / or one brake shoe side. It is characterized by including means.

According to the drum brake having such a configuration, the biasing force of the biasing means provided between the moving member and the other brake shoe and / or between the bell crank and the one brake shoe is provided. Accordingly, since the moving member and the bell crank are constantly urged toward the other brake shoe and / or the one brake shoe side, rattling of the moving member and the bell crank during non-braking can be suppressed, As a result, it is possible to prevent the moving member and the bell crank from vibrating and making an abnormal noise when the vehicle is traveling.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 and 2, a pair of brake shoes 12 and 14 are supported on one side 11 of the backing plate 10 by shoe hold down devices 16 and 18 so as to be capable of expanding. These brake shoes 12, 14 are fixed to the arc-shaped and plate-shaped shoe rims 20, 22, shoe webs 24, 26 projecting from the inner peripheral surfaces of the shoe rims 20, 22, and the outer peripheral surfaces of the shoe rims 20, 22. The linings 28 and 30 are provided respectively. Brake shoes 12,14 (Shoe web 2
4, 26) are opposed to each other and are stretched between the notches 35, 35 formed on the outer peripheral sides of the shoe webs 24, 26 and the anchor pin 34 fixed on the one surface 11 of the backing plate 10. Or, according to the biasing force of the turn springs 31 and 33,
The shoe webs 24, 26 are respectively brought into contact with the side surfaces of the anchor pins 34, and the other ends of the shoe webs 24, 26 are urged in a direction toward each other by a spring (not shown) so that the axial length thereof is variable. The two ends of the adjuster 32 are engaged with each other. In FIG. 2, 37 is a shoe lifting prevention plate.

The portion on the one surface 11 of the backing plate 10 and located on the one end side of the brake shoes 12, 14 has a first
As shown in FIGS. 3 to 3, a pedestal having an arc shape and a plate shape.
36 is fixed by a bolt or the like not shown. That is, in the pedestal 36, while the anchor pin 34 is inserted through the intermediate portion in the longitudinal direction thereof, the bolts are provided with through holes 38, 38 provided at both ends of the pedestal 36, the backing plate 10, and a non-rotating member (not shown). It is fixed to the one surface 11 of the backing plate 10 by inserting the fixing portions and tightening the nuts on the tip end side of the bolts. A pair of brackets 40, 40 facing each other at a predetermined interval are provided in a protruding manner at a portion of the pedestal 36 located on the brake shoe 14 side, and between the brackets 40, 40, the pedestal 36 to the shoe web 26 side. A pin 42 is attached at a position separated by a predetermined distance.

On the pedestal 36, as shown in FIGS. 1 to 3, a bell crank 44 having an L-shape as a whole is provided. The bell crank 44 is formed by integrally laminating two plate members by welding or the like, and is between the one ends of the brake shoes 12 and 14 and slightly on the inner peripheral side of the anchor pin 34. In position, a relatively short contact portion 43 which is brought into contact with the inner peripheral side end surface of the shoe web 24 of the brake shoe 12, and a direction opposite to the brake shoe 14 side from the end portion of the contact portion 43 on the backing plate 10 side. It has a longitudinal portion 45 which projects to the back and is located between the backing plate 10 and the shoe web 24 of the brake shoe 12. Therefore, in the present embodiment, the brake shoe 12 corresponds to the other brake shoe and the contact portion 43 corresponds to the second contact portion. A bifurcated portion 46 is formed on the protruding end side of the elongated portion 45, and the bifurcated portion 46 is provided on the backing plate 10 from the end face 48 side of the backing plate 10.
The parking cable 50 that is inserted into the one surface 11 side through the 10 is connected via a connection fitting 52 that is caulked and fixed to one end of the parking cable 50 and a compression coil spring 53 that is arranged on the outer peripheral side of the parking cable 50. ing. Further, the bell crank 44 is adapted to be brought into contact with the pedestal 36 at an intermediate portion thereof.

Between the bell crank 44 and the brake shoe 14, as shown in FIGS. 1 to 3, a moving member 54 having a substantially inverted T shape.
Is provided. The moving member 54 is composed of two plate members integrally bonded by welding or the like,
An abutting portion 55 which is abutted with the inner peripheral side end surface of the shoe web 26 of the brake shoe 14 at a position between the one ends of the brake shoes 12 and 14 and slightly on the inner peripheral side of the anchor pin 34, and An elongated shape extending from the end of the contact portion 55 on the backing plate 10 side to both the bell crank 44 side and the side opposite to the bell crank 44 side and located between the backing plate 10 and the shoe web 26 of the brake shoe 14. Department
And 57. Therefore, in this embodiment, the brake shoe 14 corresponds to one brake shoe, and the contact portion 55 corresponds to the first contact portion.
A forked portion 56 is provided at the end of the elongated portion 57 on the side of the bell crank 44.
Is formed, and the moving member 54 has its forked part 56 sandwiching the middle part of the bell crank 44,
It is rotatably attached to the middle portion of 44 by a pin 58. Further, the end of the moving member 54 on the side opposite to the bell crank 44 side is inserted between the pin 42 and the pedestal 36, whereby the center O of the backing plate 10 and the center of the anchor pin 34 (brake). The moving member 54 is guided in a direction perpendicular to a straight line connecting the shoe 12 and the center of the one end of the shoes 12 and 14), that is, the horizontal direction in FIGS.

In the drum brake configured as described above, the parking brake operating force is applied to the parking cable.
When 50 is pulled downward in FIG. 1, the brake shoe 12 is pushed outward by the abutting portion 43 of the bell crank 44 by rotating the bell crank 44 counterclockwise around the pin 58 as a rotation center. The lining 28 is pressed against the inner peripheral surface of the rotary drum. Then, by the reaction force at this time, the moving member 54 is moved to the brake shoe 14 side via the pin 58. That is, due to the reaction force, a rotational force in the counterclockwise direction in FIG. 1 about the contact point between the contact portion 55 and the shoe web 26 as the center of rotation is applied to the moving member 54. The counterclockwise rotation of the moving member 54 is blocked by the contact with the pin 42, so that the moving member 54 is guided by the pin 42 and moved to the brake shoe 14 side. As a result, the brake shoe 14 is pushed out to the outer peripheral side by the contact portion 55 of the moving member 54, the lining 30 is pressed against the inner peripheral surface of the rotary drum, and the braking by the parking brake is performed.

Here, in the present embodiment, a relatively short tension coil spring 60 is further provided between the end of the bell crank 44 on the contact part 43 side and the end of the moving member 54 on the contact part 55 side. The notch 35 is stretched and formed in the end portion of the moving member 54 on the contact portion 55 side and the shoe web 24 of the brake shoe 12.
A relatively long tension coil spring 62 is stretched between and. As a result, the tension coil spring 60 constantly urges the bell crank 44 in the clockwise rotating direction in FIG. 1, and the tension coil spring 62 causes the moving member 54 and the bell crank 44 to both brake shoes.
Always urged to the 12th side. Therefore, in this embodiment, the tension coil spring 62 corresponds to the biasing means. The spring load of the tension coil spring 62 is the same as that of the moving member 54 and the bell crank 44 during non-braking.
It is determined in advance so that the abnormal noise due to the vibration can be properly suppressed.

As described above, according to the present embodiment, the bell crank 44 and the moving member 54 are provided inside the drum brake on the one surface 11 side of the backing plate 10 and are not exposed to the outside. As compared with the conventional case in which the parking brake operating force is transmitted to the brake shoe via a bell crank or the like that is movably provided, it is possible to more reliably prevent rust and the like at the rotating portion of the bell crank 44.

Further, according to the present embodiment, the parking brake operating force is generated by the parking cable 50, the bell crank 44, and the moving member.
Brake shoes 12, 14 through relatively few parts such as 54
Is transmitted to the parking cable, a bell crank provided outside the backing plate, a connecting member provided inside the backing plate, a parking lever provided on the brake shoe, and a strut bridged between the brake shoes. Compared with the conventional case in which the parking brake operating force is transmitted to the brake shoes via the above, the transmission efficiency of the parking brake operating force can be further improved.

Further, according to the present embodiment, the tension coil spring 62 is provided between the end of the moving member 54 on the contact portion 55 side and the brake shoe 12.
Is stretched, and both the moving member 54 and the bell crank 44 are constantly biased toward the brake shoe 12 side in accordance with the biasing force of the tension coil spring 62. The rattling is preferably suppressed, and it is effectively prevented that the moving member 54 and the bell crank 44 vibrate and make an abnormal noise when the vehicle is running, while the parking brake operating force is released. When the diameters of 14 are reduced, the bell crank 44 is rotated clockwise in FIG. 1 while being pushed toward the brake shoe 12 by the moving member 54 according to the urging force of the tension coil spring 62. Even after the parking cable 50 is assisted in returning and the brake shoes 12 and 14 are prevented from being reduced in diameter beyond a certain limit based on the contact with the anchor pin 34. May return the parking cable 50 to the original position obtained by further rotating the bell crank 44 by the biasing force of the tension coil spring 62.

Further, according to the present embodiment, one end of the tension coil spring 62 is hooked in the notch 35 formed in the shoe web 24 in order to hook one end of the return spring 31. There is an advantage that it is not necessary to separately provide a hook hole.

Further, according to the present embodiment, the tension coil spring 60 is stretched between the end of the moving member 54 on the contact portion 55 side and the end of the bell crank 44 on the contact portion 43 side. Since the bell crank 44 is constantly urged in the clockwise direction (the direction in which the parking cable 50 is returned) in FIG. 1 according to the urging force of the tension coil spring 60, the tension coil spring 60 and the tension coil spring 62 cause The return of the parking cable 50 can be more favorably assisted, and the parking cable 50 can be reliably returned to the original position.

In the above-described embodiment, the tension coil spring 62 is formed by cutting the end of the moving member 54 on the contact portion 55 side and the notch of the brake shoe 12.
Although it is stretched between the brake shoe 12 and the brake shoe 12, it is not always necessary to stretch the gap between the brake shoe 12 and the brake shoe 12. It is possible to get the same effect as the example, or
The end of the bell crank 44 on the contact portion 43 side and the brake shoe 14
Even when it is stretched between the notch 35 and the notch 35, both the bell crank 44 and the moving member 54 are urged toward the brake shoe 14 and the bell crank 44 is urged in the clockwise direction in FIG. It is possible to obtain the same effect as that of the above-described embodiment. In this case, the moving member 54 and the brake shoe 12
The effect of the present invention is that even if tension coil springs are stretched between the bell crank 44 and the brake shoe 14 and between the bell crank 44 and the brake shoe 14, the noise caused by the vibration of the moving member 54 and the bell crank 44 can be suppressed. Is possible.

Further, in the above-described embodiment, the tension coil spring 62 is used as the biasing means, but it is also possible to use a biasing means made of an elastic material such as rubber.

Further, in the above-described embodiment, the tension coil spring 60
Is not always necessary and may be deleted. In this case, since the tension coil spring 62 is longer than the tension coil spring 60, the number of turns of the coil portion can be secured to be large and the degree of freedom in designing the spring load can be suitably secured, so that the tension coil spring 60 is not provided. However, the extension of the parking cable 50 can be sufficiently improved by the tension coil spring 62.

Further, in the above-described embodiment, the bell crank 44 is rotatably attached to the moving member 54 by the pin 58 at the intermediate portion thereof, but it is not always necessary to constitute such a structure, and for example, the intermediate portion of the bell crank may be used. The side end surface of the moving member and the side end surface of the moving member may only be brought into contact with each other in a state in which they are prevented from coming off. In short, the bell crank and the moving member need only be operatively connected to each other.

Further, in the above-described embodiment, both the bell crank 44 and the moving member 54 are formed by bonding two plate members together, but it goes without saying that they may be made of one plate member.

Further, in the above-described embodiment, the rotation of the moving member 54 in the counterclockwise direction in FIG. 1 causes the pin 42 provided between the brackets 40, 40 to rotate.
And the longitudinal portion 57 of the moving member 54 is abutted against the upper surface in FIG.
The pin 42 may be inserted through an elongated hole provided in the moving member.

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

[Brief description of drawings]

FIG. 1 is an enlarged view showing an essential part of a cross section of the drum brake of FIG. 2 taken along line I-I. FIG. 2 is a front view showing a main part of a drum brake to which the present invention is applied. FIG. 3 is an enlarged view of a main part of the drum brake of FIG. 2, showing a brake shoe and the like removed. 10: Backing plate 12: Brake shoe (other brake shoe) 14: Brake shoe (one brake shoe) 43: Contact part (second contact part) 44: Bell crank 45: Long part 50: Parking cable 54 : Moving member 55: Contact part (first contact part) 62: Tensile coil spring (biasing means)

Claims (1)

[Scope of utility model registration request] 1. A pair of brake shoes which are arcuate and are arranged on a backing plate so as to be capable of expanding each other, and the brake shoes which are positioned between one end portions of the pair of brake shoes facing each other. And a center between the backing plate and the one end of the pair of brake shoes between the backing plate and the one brake shoe. A moving member which is guided in a direction perpendicular to a straight line connecting the two, a second contact portion which is located between one end portions of the pair of brake shoes and is brought into contact with the other end portion of the brake shoes, and The second contact portion projects from the end on the backing plate side to the side opposite to the moving member side and is located between the backing plate and the other brake shoe, and is parked on the projecting end side. And a bell crank having a longitudinal portion operatively connected to the moving member on a side opposite to the projecting end side, the pivot cable being rotated in one direction by the parking cable. A drum brake of the type in which the other brake shoe is pushed outward by the second contact portion and the one brake shoe is pushed outward by the first contact portion of the moving member. Provided between the moving member and the other brake shoe and / or between the bell crank and the one brake shoe, the moving member and the bell crank being provided on the other brake shoe and / or the one The drum brake, which includes an urging means for constantly urging the brake shoe side.