JP3936690B2 - Drum brake device - Google Patents

Description

  The present invention relates to a drum brake device having an automatic gap adjustment device that adjusts the position of a brake shoe according to wear, and in particular, it can facilitate assembly work to a vehicle and at the same time, a drum after being assembled to a vehicle. The present invention relates to an improvement for easily adjusting a gap between a brake shoe and a brake shoe.

  Conventionally, various types of drum brake devices have been used to brake the running of the vehicle, but these drum brake devices are arranged according to the arrangement of brake shoes pressed against the inner peripheral surface of a substantially cylindrical drum. It is classified as a reading trailing type, a two reading type, or a duo servo type.

  In the case of a drum brake device mounted on an automobile, the gap between the pair of brake shoes arranged opposite to the drum inner space when the brakes are not braked is usually in each brake shoe, regardless of which type is used. In order not to increase due to wear, an automatic gap adjusting device for automatically adjusting the position of each brake shoe according to the wear of each brake shoe is incorporated.

  Conventional automatic gap adjusting devices are of a micro-adjuster type in which the amount of brake shoe feed that can be adjusted during one braking operation is limited to a very small amount (for example, see Patent Document 1 or Patent Document 2). It can be broadly classified into a one-shot adjuster type that adjusts the gap between the shoe and the drum at a stretch to the reference value (for example, see Patent Document 3 or Patent Document 4).

Japanese Examined Patent Publication No. 56-34733 Japanese Patent Publication No. 63-33567 Japanese Patent Publication No.43-21822 Japanese Patent Publication No. 51-12882

However, a drum brake device equipped with a conventional micro adjuster type automatic gap adjusting device has a large initial gap between the drum and the brake shoe in order to facilitate the assembly work to the vehicle. After assembly, adjusting the clearance between the drum and the brake shoe to an appropriate clearance requires repeated braking operations many times, and it takes time to adjust the clearance between the drum and the brake shoe after assembly. There was a problem.
Further, in order to solve this problem, if the initial gap between the drum and the brake shoe is set small when assembling to the vehicle, there arises a problem that the assembling work to the vehicle becomes difficult.

On the other hand, in the case of a drum brake device equipped with a conventional one-shot adjuster type automatic gap adjustment device, even if the initial clearance between the drum and the brake shoe is set large when assembled to the vehicle, To adjust the gap between the drum and the brake shoe to an appropriate gap, it is only necessary to repeat the braking operation once or a few times. Therefore, the assembly to the vehicle can be improved, and at the same time, the adjustment of the gap between the assembled drum and the brake shoe can be simplified.
However, in the case of the conventional one-shot adjuster type automatic gap adjusting device, for example, when the drum is deformed by an excessive braking force and the range of motion of the brake shoe temporarily increases due to the deformation of the drum, Since the position of the brake shoe is adjusted all at once, including the range of motion, over-adjustment occurs where the gap between the drum and the brake shoe to be secured during non-braking is less than or equal to the appropriate gap, and the brake shoe is dragged. There was a risk of inviting.

  The present invention has been made in view of the above circumstances, and its purpose is to facilitate the assembly work to the vehicle, and at the same time, to easily adjust the gap between the drum and the brake shoe after the assembly to the vehicle, Another object of the present invention is to provide a drum brake device that can prevent the occurrence of over-adjustment that causes dragging of the brake shoe.

The above object is achieved by the following configuration.
(1) A drum brake device including an automatic gap adjusting device that automatically adjusts the position of a pair of brake shoes arranged in opposition to a space in the drum according to wear,
The automatic gap adjustment device is integrally supported by a strut receiving plate having a cam surface that is rotatably supported by one brake shoe pressed by a wheel cylinder and has a cam surface that gradually increases in distance from the rotation center. The formed adjuster gear, the strut whose one end is in contact with the cam surface and the other end is in contact with the other brake shoe, and the adjuster gear so that the cam surface is maintained in contact with the strut. And an adjuster spring that rotates the strut support plate in a predetermined rotation direction, and a ratchet pawl that is rotatably supported by the one brake shoe between the wheel cylinder and the adjuster gear and meshes with the adjuster gear And an adjuster regulating lever having
The drum, wherein the adjuster regulating lever is provided with a rotation control unit that receives a pressing force of the wheel cylinder during a braking operation and restricts the rotation of the adjuster gear by the urging of the adjuster spring. Brake device.

(2) In the above (1), the adjuster gear and the strut support plate are opposed to each other with a web of one brake shoe interposed therebetween, and are integrally connected via a connecting portion that passes outside the web. A drum brake device characterized by that.

In the drum brake device according to the above (1), when the brake operation is performed and the wheel cylinder presses one end of one brake shoe and the brake shoes start to expand, the brake shoe moves to the inner peripheral surface of the drum. Until the end of the strut, the adjuster gear and the strut support plate are rotated by the urging force of the adjuster spring so that one end of the strut constituting the automatic clearance adjustment device does not move away from the strut support plate. The separation distance between the pair of brake shoes held in this way is extended.
The adjustment of the separation distance between the pair of brake shoes via the struts is performed at once in conjunction with the movement until the brake shoes come into contact with the inner peripheral surface of the drum, so the conventional one-shot adjuster type automatic gap As in the case of a drum brake device equipped with an adjusting device, the gap between the drum and the brake shoe after assembly even if the initial clearance between the drum and the brake shoe is set large when assembled to the vehicle. Can be achieved by executing only one braking operation. Therefore, by setting a large initial gap when assembling to the vehicle, it is possible to improve the ease of assembling to the vehicle and to adjust the gap between the drum and the brake shoe after assembling to the vehicle. Can be simple.

After the brake shoe comes into contact with the inner peripheral surface of the drum, a braking force is generated by the sliding contact between the brake shoe and the drum, and at that time, the brake shoe contacting the drum is placed on the piston of the wheel cylinder. Therefore, the operating force transmitted from the wheel cylinder to the brake shoe increases in accordance with the generated braking force.
When the operating force transmitted from the wheel cylinder to the brake shoe increases, the adjuster regulating lever that receives the operating force on the rotation control unit is gradually pressed strongly against the adjuster gear by the rotational force in the direction that regulates the rotation of the adjuster gear. When the generated braking force reaches the specified magnification, the turning force of the adjuster regulating lever, which has been increasing until then, balances with the turning force of the adjuster gear by the adjuster spring, and the rotation of the adjuster gear and the strut support plate Stop movement.
Therefore, after that, even if the braking force further increases and, for example, a situation occurs in which the drum is deformed by an excessive braking force, an adjusting operation in which the brake shoe follows the deformation of the drum does not occur. Therefore, it is possible to prevent the occurrence of over-adjustment that causes dragging of the brake shoe.

In the drum brake device described in (2) above, the integrated structure of the adjuster gear and the strut receiving plate is a metal plate in which an adjuster gear is formed at one end of the connecting portion and a strut receiving plate is formed at the other end of the connecting portion. Can be easily manufactured by bending at the connecting portion, can be mass-produced at low cost by press molding, and is effective in reducing the manufacturing cost.
Since the adjuster gear and the strut support plate are opposed to each other with the web of the brake shoe interposed therebetween, the adjuster gear and the strut support plate can be arranged using a small empty space on both sides of the web. Compactness can be achieved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a drum brake device according to the invention will be described in detail with reference to the drawings.
FIG. 1 is a front view of an embodiment of a drum brake device according to the present invention.
The drum brake device 100 according to the embodiment includes a pair of brake shoes 3 and 4 including a leading shoe 3 and a trailing shoe 4 that are disposed opposite to each other in a space in a substantially cylindrical drum (not shown), and a pair of these shoes. A wheel cylinder 6 disposed on one opposite end side of each of the brake shoes 3 and 4 to generate a shoe operating force that presses the brake shoes 3 and 4 against the drum, and the other of the pair of brake shoes 3 and 4 A gap between the anchor member 7 disposed on the opposite end side, the backing plate 9 that supports these constituent members, and the drum when the pair of brake shoes 3 and 4 are not braked is each brake shoe 3 and 4. An automatic gap adjusting device 10 that automatically adjusts the position of each brake shoe 3 and 4 in accordance with wear, and a pair of brake shoes when parking. 3 and 4 was expanded and a parking lever 11 to generate a braking force.
A drum (not shown) is concentric with the backing plate 9 and rotates in the direction of arrow R in FIG. 1 when the vehicle moves forward.

The above brake shoes 3 and 4 are attached to the backing plate 9 by a shoe support shaft 14 so as to be movable toward the inner periphery of the drum.
As shown in FIG. 3, the end portions of the brake shoes 3 and 4 on the wheel cylinder 6 side are in directions in which the end portions of the respective shoes approach each other by the shoe-to-shoe spring 15 (that is, in the direction away from the drum). The end of each shoe is kept in contact with the piston of the wheel cylinder 6 by being biased.
The end portion of the anchor member 7 side of the brake shoes 3 and 4, the direction in which the end portions of the respective shoe by the anchor scan pulling 16 approach each other (i.e., a direction away from the drum) is biased, respectively The ends of the shoes are kept in contact with the anchor member 7.

  The automatic gap adjusting device 10 of the present embodiment will be described with reference to FIG. 2 as well. A pin erected on the web 3a on one end side of one brake shoe 3 pressed from the wheel cylinder 6 during braking operation. 21 and a cam surface 25a that is rotatably supported by the web 3a via the pin 21 and has a cam surface 25a that gradually increases the distance from the center of rotation, as clearly shown in FIGS. An adjuster gear 23 integrally formed with the strut receiving plate 25, a strut 27 having one end abutting against the cam surface 25a and the other end abutting against the web 4a of the other brake shoe 4, and the wheel cylinder 6 When the pair of brake shoes 3 and 4 are expanded by the pressure applied by the lever, the cam surface 25a is always adjusted so as to maintain the state in contact with one end of the strut 27. An adjuster spring 29 for rotating the gear 23 and the strut support plate 25 in a predetermined rotational direction (clockwise), and a pin erected on the web 3a of one brake shoe 3 between the wheel cylinder 6 and the adjuster gear 23 31 and an adjuster regulating lever 33 that is rotatably supported on the web 3a via the pin 31.

The adjuster gear 23 has ratchet teeth 23 a in an arc portion centered on the pin 21, and an arm portion 23 b with which one end of an adjuster spring 29 is engaged.
As shown in FIG. 4, when the cam surface 25a formed on the strut receiving plate 25 rotates clockwise about the pin 21 (in the direction of arrow F in the figure), the distance l to the pin 21 according to the rotation. (See FIG. 7) is a smooth curved surface that gradually increases.

  As shown in FIGS. 4 and 5, the adjuster gear 23 and the strut receiving plate 25 face each other with the web 3 a of one brake shoe 3 interposed therebetween, and are integrally connected via a connecting portion 24 that passes through the outside of the web 3 a. It is manufactured by press forming a metal plate.

  The adjuster spring 29 is a torsion coil spring fitted to the pin 21 and biases the adjuster gear 23 in the direction of arrow F in FIG. The adjuster spring 29 and the adjuster gear 23 are prevented from coming off by a clip 41 engaged with the pin 21.

The other end portion of the strut 27 is pulled toward the other brake shoe 4 by the tension coil spring 45 and is kept in contact with the other brake shoe 4.
Therefore, when the brake shoes 3 and 4 are expanded, the strut 27 moves following the other brake shoe 4, and if one end of the strut 27 tries to disengage from the cam surface 25a of the strut receiving plate 25 by the movement, In order to maintain the contact state between the cam surface 25a and one end of the strut 27, the adjuster spring 29 rotates the adjuster gear 23 and the strut receiving plate 25 in the direction of arrow F in FIG.

As shown in FIGS. 4 and 6, the adjuster regulating lever 33 includes a ratchet pawl 33 a that meshes with the adjuster gear 23 to prevent reverse rotation of the adjuster gear 23, and a rotation control that receives the pressing force of the wheel cylinder 6 during braking operation. It has the part 33b and the bending part 33c which performs rough positioning by contact | abutting to the side surface of the web 3a at the time of the assembly | attachment to the web 3a.
As shown in FIG. 4, the rotation control unit 33 b receives the operation force W of the wheel cylinder 6 at a position eccentric from the pin 31 toward the adjuster gear 23 by a distance s. When the operating force W acts on the rotation control unit 33 b from the wheel cylinder 6, the adjuster regulating lever 33 rotates clockwise around the pin 31 in FIG. 4. The turning force of the adjuster restricting lever 33 becomes turning force in a direction that restricts the rotation of the adjuster gear 23 due to the urging of the adjuster spring 29.

  In the drum brake device 100 described above, when the brake operation is performed and the wheel cylinder 6 presses one end of the one brake shoe 3 and the brake shoes 3 and 4 start to expand each other, the brake shoes 3 and 4 are moved to the drum. As shown in FIG. 7, the urging force of the adjuster spring 29 prevents the one end of the strut 27 constituting the automatic gap adjusting device 10 from separating from the strut receiving plate 25 until it comes into contact with the inner peripheral surface. The adjuster gear 23 and the strut receiving plate 25 rotate, and the distance between the pair of brake shoes 3 and 4 held via the strut 27 is extended.

  The adjustment of the separation distance between the pair of brake shoes 3 and 4 via the struts 27 is performed at once in conjunction with the movement operation until the brake shoes 3 and 4 come into contact with the inner peripheral surface of the drum. As in the case of a drum brake device equipped with a one-shot adjuster type automatic gap adjustment device, even if the initial clearance between the drum and the brake shoe is set large when assembled to the vehicle, In order to adjust the clearance between the brake shoe and the appropriate clearance, only one braking operation is required. Therefore, by setting a large initial clearance when assembled to the vehicle, it is possible to improve the ease of assembling to the vehicle and to easily adjust the clearance between the drum and the brake shoe after being assembled to the vehicle. Can be.

After the brake shoes 3 and 4 come into contact with the inner peripheral surface of the drum, a braking force is generated by sliding contact between the brake shoes 3 and 4 and the drum. Since the drag force from the brake shoe that contacts the drum acts, the operating force transmitted from the wheel cylinder 6 to the brake shoe 3 increases in accordance with the generated braking force.
When the operating force W transmitted from the wheel cylinder 6 to the brake shoe 3 increases, the adjuster regulating lever 33 that receives the operating force W on the rotation control unit 33b is adjusted in a direction that regulates the rotation of the adjuster gear 23. When the generated braking force reaches a predetermined magnification, the rotational force of the adjuster regulating lever 33, which has been increasing until then, balances with the rotational force of the adjuster gear 23 by the adjuster spring 29, and the adjuster The gear 23 and the strut receiving plate 25 are prevented from rotating.
Therefore, after that, even if the brake force further increases and the drum is deformed by the excessive brake force, an adjusting operation in which the brake shoe follows the deformation of the drum does not occur. Therefore, it is possible to prevent the occurrence of over-adjustment that causes dragging of the brake shoe.

In the drum brake device 100 described above, the integrated structure of the adjuster gear 23 and the strut receiving plate 25 forms the adjuster gear 23 at one end of the connecting portion 24 and the strut receiving plate 25 at the other end of the connecting portion 24. The bent metal plate can be easily manufactured by bending at the connecting portion 24, and can be mass-produced at low cost by press molding, which is effective in reducing the manufacturing cost.
Since the adjuster gear 23 and the strut receiving plate 25 are opposed to each other with the web 3a of the brake shoe 3 sandwiched therebetween, the adjuster gear 23 and the strut receiving plate 25 are connected to each other by using small empty spaces on both sides of the web 3a. The brake device can be made compact.

  In addition, the arrangement | positioning form of the brake shoe in the drum brake device equipped with the automatic clearance gap adjustment apparatus which concerns on this invention is not restricted to the said embodiment. The automatic gap adjusting device according to the present invention can be mounted on any type of drum brake device such as a leading trailing type, a two leading type, or a duo servo type.

1 is a front view of an embodiment of a drum brake device according to the present invention. It is explanatory drawing of the coupling | bonding relationship of a pair of brake shoe and automatic clearance gap adjustment apparatus shown in FIG. FIG. 3 is a view as seen from an arrow A in FIG. 2. FIG. 2 is an enlarged view showing a positional relationship between an adjuster gear and a strut receiving plate shown in FIG. 1 and an adjuster regulating lever. FIG. 5 is a side view showing an integrated structure of the adjuster gear and the strut support plate shown in FIG. 4. It is a side view of the adjuster control lever shown in FIG. FIG. 5 is an enlarged view of a state in which the gap adjustment of the automatic gap adjustment device shown in FIG. 4 has advanced.

Explanation of symbols

3, 4 Brake shoes 3a, 4a Web 6 Wheel cylinder 9 Backing plate 10 Automatic gap adjusting device 23 Adjuster gear 24 Connecting part 25 Strut receiving plate 25a Cam surface 27 Strut 29 Adjuster spring 33 Adjuster regulating lever 33a Ratchet claw 33b Rotation control part 100 drum brake device

Claims (2)

A drum brake device including an automatic gap adjustment device that automatically adjusts the position of a pair of brake shoes arranged in the drum inner space according to wear,
The automatic gap adjustment device is integrally supported by a strut receiving plate having a cam surface that is rotatably supported by one brake shoe pressed by a wheel cylinder and has a cam surface that gradually increases in distance from the rotation center. The formed adjuster gear, the strut whose one end is in contact with the cam surface and the other end is in contact with the other brake shoe, and the adjuster gear so that the cam surface is maintained in contact with the strut. And an adjuster spring that rotates the strut support plate in a predetermined rotation direction, and a ratchet pawl that is rotatably supported by the one brake shoe between the wheel cylinder and the adjuster gear and meshes with the adjuster gear And an adjuster regulating lever having
The drum, wherein the adjuster regulating lever is provided with a rotation control unit that receives a pressing force of the wheel cylinder during a braking operation and restricts the rotation of the adjuster gear by the urging of the adjuster spring. Brake device. The adjuster gear and the strut support plate are opposed to each other with a web of one brake shoe interposed therebetween, and are integrally connected via a connecting portion that passes through the outside of the web. The drum brake device according to 1.

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