JP4393896B2 - Drum brake device - Google Patents

Description

  The present invention relates to a drum brake device having an adjuster drive mechanism that adjusts the position of a brake shoe in accordance with wear of the brake shoe, and there is no occurrence of an adjustment failure, and the components of the adjuster drive mechanism are used in a hub or the like. The present invention relates to an improvement for securing a good layout without interference.

  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.

Of these, a duo-servo drum brake device generally includes a pair of brake shoes, a primary shoe and a secondary shoe, disposed in a cylindrical drum so as to face each other.
In the primary shoe, the forward rotation direction inlet side of the drum is used as an input portion, and the forward rotation direction outlet side of the drum is connected to the front side of the secondary shoe via an adjuster unit, for example. On the other hand, the outlet side of the secondary shoe is brought into contact with an anchor portion provided on the backing plate, and the anchor reaction force acting on the primary shoe and the secondary shoe is received by this anchor portion.

  As a result, when the primary shoe and the secondary shoe are expanded and pressed against the inner peripheral surface of the drum, the anchor reaction force acting on the primary shoe is input to the inlet side of the secondary shoe so as to press the secondary shoe against the inner peripheral surface of the drum. Therefore, both the primary shoe and the secondary shoe operate as leading shoes, and a braking force with a very high gain can be obtained.

  The duo-servo type drum brake device described above can not only obtain extremely high braking force compared to the leading trailing type and two-leading type drum brake devices, but also can be easily miniaturized and can also incorporate a parking brake. It has many advantages such as being easy.

FIGS. 4 and 5 illustrate a duo-servo type drum brake device in which a position of each brake shoe is adjusted by operating an adjuster unit according to wear of a pair of brake shoes, and the brake shoe and the drum. The prior art example of the adjuster drive mechanism which maintains the clearance gap between inner peripheral surfaces to an appropriate value is shown.
In the drum brake device shown in FIGS. 4 and 5, the adjuster unit 73 disposed between the opposing ends of the pair of brake shoes 71 and 72 extends when the adjuster gear 74 is rotated, The space between the opposing ends of the pair of brake shoes 71 and 72 is widened.

Further, the ends of the pair of brake shoes 71 and 72 on the adjuster unit 73 side are urged by the urging force of the shoe return springs 75 and 76 so as to maintain a state where they are in contact with both ends of the adjuster unit 73. . Further, the other opposing ends of the pair of brake shoes 71 and 72 are urged in a direction to contact the anchor pin 77 by a dedicated shoe return spring.
However, the adjuster driving mechanisms 81 and 91 shown in FIGS. 4 and 5 are different in the timing for rotationally driving the adjuster gear 74.

The adjuster drive mechanism 81 shown in FIG. 4 is configured to include an adjuster lever 82 having a pawl portion 82 a that is rotatably supported by the secondary shoe 72 and engages the adjuster gear 74, and an adjuster cable 83. is there.
The adjuster cable 83 has one end 83 a connected to an anchor pin 77 between the other opposing ends of the pair of brake shoes 71 and 72, and the other end 83 b via a cable guide 84 attached on the secondary shoe 72. The adjuster lever 82 is connected to the adjuster lever 82. The adjuster lever 82 is rotated clockwise in the drawing in accordance with the amount of movement of the secondary shoe 72 when the secondary shoe 72 is expanded, and the adjuster gear 74 is rotationally driven.
That is, the adjuster driving mechanism 81 causes the claw portion 82a to move from the outside in the radial direction to the inside by the turning operation of the adjuster lever 82 accompanying the movement of the secondary shoe 72 to the drum side during braking. A so-called positive-type drive mechanism that rotates is configured (see, for example, Patent Document 1).

On the other hand, the adjuster drive mechanism 91 shown in FIG. 5 is rotatably supported at a position near the adjuster unit 73 of the secondary shoe 72 and has an adjuster lever 92 having a claw portion 92a that engages with the adjuster gear 74. A guide plate 93 rotatably supported by an intermediate portion on the secondary shoe 72, and a first end connected to the anchor pin 77 side and the other end connected to a first engaging portion 93a on the guide plate 93. And a second adjuster rod 95 having one end connected to the second engaging portion 93b on the guide plate 93 and the other end connected to the adjuster lever 92. The adjuster gear 74 is rotated by the counterclockwise rotation of the adjuster lever 92 interlocked with the return movement of the secondary shoe 72 in the drawing. To drive.
That is, the adjuster drive mechanism 91 is a so-called negative type in which the claw portion 92a rotationally drives the adjuster gear 74 by the turning operation of the adjuster lever 92 in conjunction with the return operation of the secondary shoe 72 when the brake is released. The drive mechanism is comprised (for example, refer patent document 2).

Japanese Patent Publication No. 44-15207 Japanese Patent Publication No. 35-4015

  Incidentally, in general, in the case of the positive type adjuster driving mechanism 81 that operates the adjuster unit 73 at the time of braking, as shown in the drawing, in order to prevent over-adjustment due to deformation of the drum at the time of braking, etc. An over-adjustment prevention mechanism 86 that relaxes the tension caused by the cable 83 is provided between the adjuster cable 83 and the adjuster lever 82. However, if the over-adjustment prevention mechanism 86 is provided, excessive adjustment can be prevented. On the other hand, when a certain axial force acts on the adjuster unit 73 during the expansion of the pair of brake shoes, the over-adjustment prevention mechanism 86 As a result, the rotation of the adjuster lever 82 may be hindered, resulting in an adjustment failure.

  On the other hand, in the case of the negative type adjuster drive mechanism 91 that operates the adjuster unit 73 when the brake is released, it is not necessary to provide the over-adjustment prevention mechanism 86, so that the occurrence of an adjustment failure can be prevented. Further, the hook return portion 76a of one end of the shoe return spring 76 for keeping the end portions of the pair of brake shoes 71, 72 in contact with both ends of the adjuster unit 73 is hooked on the adjuster lever 92, and the shoe return spring 76 is moved. Because of the structure that is also used for the return operation of the adjuster lever 92, and the structure in which the claw portion 92a is within the radial direction of the adjuster unit 73, the hook portion 76a on one end side of the shoe return spring 76 is a drum. It ’s too close to the center, As return spring 76 does not interfere with the hub, a number of regulations caused on the shape and the movable range and the like of the adjuster lever 92. As a result, there arises a problem that the layout performance of these components deteriorates.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to secure a good layout property in which there is no possibility of an adjustment failure and the shoe return spring does not interfere with the hub or the like due to the rotation of the adjuster lever. It is to provide a drum brake device that can.

The above object can be achieved by a drum bouquet apparatus having the following configuration.
(1) adjuster unit which also serves as a link between one end of the pair of brake shoes are disposed, wherein the adjuster lever to rotate in a direction back in conjunction with the return movement the brake shoes upon release of the brake by the hydraulic actuator an adjuster gear of the adjuster unit a duo-servo type drum brake device having an adjuster drive mechanism for rotating operation, the adjuster lever is on one of the pair of brake shoes which are freely mounted rotating, the adjuster lever together obtain Bei lever return spring consisting return compression coil spring for urging in a direction, and further comprising a pawl position regulating spring for regulating the claw portion of the adjuster lever to a proper height for engaging the adjuster gear To do.

(2) In the above (1), the adjuster lever is rotatably supported by the brake shoe, and a claw that extends from the rotation support to one side and engages the adjuster gear at the tip. And a second arm extending from the rotation support portion to the other side, and the lever return spring is interposed between the brake shoe and the second arm. and octopus may be characterized is.

(3) In the above (1) or (2), the claw position regulating spring is a torsion coil spring in which a coil portion is fitted to an outer periphery of a lever pin on a brake shoe, and the claw portion of the adjuster lever is moved to the adjuster. The height may be regulated to an appropriate height for engaging with the gear, and the adjuster lever may be biased in the return direction .

  The adjuster drive mechanism equipped in the drum brake device described above is a positive type because it is a negative type that rotates the gear in the return direction of the lever interlocked with the return operation of the brake shoe when the brake is released. In this case, the over-adjustment prevention mechanism equipped is not necessary. Therefore, the occurrence of an adjustment failure due to the early operation of the over-adjustment prevention mechanism does not occur.

  In addition, the spring that biases the lever in the return direction is not used as a shoe return spring, but is equipped with a dedicated spring, so that one end of a pair of brake shoes abuts the adjuster unit. The shoe return spring can be placed vertically along the adjuster unit as in the case of the conventional positive type, so that the hook portion on the brake shoe side of the shoe return spring does not move greatly toward the drum center side. . Accordingly, it is possible to secure a good layout property that does not cause the shoe return spring to interfere with the hub during braking.

  In the adjuster lever of the drum brake device described in (2), the claw portion of the first arm is the point of action, the rotation support portion supported by the brake shoe is the fulcrum, and the contact portion of the spring on the second arm is Since it functions as a power point and drives the gear, even if a small compression coil spring is used as the spring, the gear can be driven firmly.

Also, in the case of a negative type adjuster drive mechanism, if the amount of rotation of the adjuster lever during braking exceeds the specified amount, the lever claw will get over the gear teeth, and the gear will rotate when the lever returns when the brake is released. Therefore, a claw position restricting means for restricting the claw portion of the lever to an appropriate height for engaging with the gear is required.
Therefore, as in the drum brake device described in (3), if the claw position restricting means is provided with a rotational force applying portion that urges the lever in the return direction, the claw position restricting means itself returns the lever. A function as a spring urging in the direction is provided, and a dedicated lever return spring can be reduced in size.

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 of this embodiment is a so-called duo-servo type drum brake device, and is a pair of brakes of a primary shoe 3 and a secondary shoe 4 that are arranged opposite to each other in a substantially cylindrical space in a drum (not shown). An adjuster unit 6 which functions as a link for inputting the output of the primary shoe 3 to the secondary shoe 4 disposed between the opposed ends of the pair of brake shoes 3 and 4 facing each other. And an operation force generating means 7 that is disposed on the other opposed end side of the pair of brake shoes 3 and 4 and generates a shoe operation force that presses the brake shoes 3 and 4 against the drum.
Further, the drum brake device 100 includes a shoe drive mechanism 8 that transmits the operating force generated by the operating force generating means 7 to the brake shoes 3, 4, a backing plate 9 that supports these components, and an adjuster lever described later. The adjuster drive mechanism 10 that drives the adjuster unit 6 via the two and the other opposing ends of the pair of brake shoes 3, 4 are erected on the backing plate 9 to generate the anchor reaction force from the brake shoes 3, 4. An anchor pin 11 is provided.
A drum (not shown) is concentric with the backing plate 9 and rotates in the direction of arrow R in FIG.

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.
The end portions of the brake shoes 3 and 4 on the side of the operating force generating means 7 are connected to spring locking portions 52 and 53 on a support plate 51 to be described later via shoe return springs 15 and 16, respectively. The ends of the shoes are biased in a direction toward each other (that is, a direction away from the drum).

  The support plate 51 is pivotally supported by the anchor pin 11 and is connected to the backing plate 9 through the anchor pin 11. The spring locking portions 52 and 53 are hook-like portions that lock the end hook portions 15a and 16a of the shoe return springs 15 and 16, and are formed by cutting and raising by pressing.

  Further, the ends of the brake shoes 3 and 4 on the side of the adjuster unit 6 are urged by the urging force of the shoe return spring 13 so that the state in contact with the end of the adjuster unit 6 is maintained. .

  In the case of the present embodiment, the operating force generating means 7 is a hydraulic actuator and outputs a shoe operating force to the cam plate 34 of the shoe drive mechanism 8 by a piston rod (not shown) that advances by hydraulic pressure, and the cam plate 34 associated therewith. The brake shoes 3 and 4 are expanded by a pivoting operation around the anchor pin 11.

The adjuster unit 6 originally adjusts the distance between the ends of the brake shoes 3 and 4 in accordance with the progress of wear of the linings 3c and 4c of the brake shoes 3 and 4.
As shown in FIG. 2, the adjuster unit 6 includes an adjuster gear 6a, a screw portion 6b projecting from the central axis of the adjuster gear 6a, a shaft portion 6c, and a sleeve 6d screwed to the screw portion 6b. And a socket 6e in which the shaft portion 6c is rotatably accommodated.
The sleeve 6d and the socket 6e are equipped with grooves 6f sandwiching the webs 3a and 4a of the brake shoes 3 and 4 at the tip, and are prevented from rotating by engaging the grooves 6f with the webs 3a and 4a. The
When the adjuster gear 6a in FIG. 2 is rotated in the direction of arrow A in FIG. 2, the sleeve 6d is screwed on the threaded portion 6b to extend.

The adjuster drive mechanism 10 is rotatably supported by the secondary shoe 4 by the lever pin 21 and has an adjuster lever 24 having a claw portion 23 that engages with the adjuster gear 6 a, and this adjuster lever 24 is used to move the secondary shoe 4. It is the structure provided with the adjuster cable 26 for making it interlock | cooperate and rotate.
Adjuster cable 26 has one end 26a is connected to the anchor pin 11, via the cable guide 27 the other end 26b is mounted on the secondary shoe 4, Ru Tei is coupled to the adjuster lever 24.

With this configuration, the adjuster lever 24 rotates in the clockwise direction in FIG. 1 in conjunction with the movement of the secondary shoe 4 when the secondary shoe 4 is expanded, and the claw portion 23 is in the direction indicated by the arrow B in FIGS. 1 and 3. When the movement amount at that time exceeds a predetermined amount, the tooth moves over one of the teeth of the adjuster gear 6a and engages with the next tooth. When the brake is released, the adjuster lever 24 rotates counterclockwise in FIG. 1 according to the return operation of the secondary shoe 4, and the claw portion 23 returns in the direction of arrow C in FIG. 2 is rotated in the direction of arrow A to extend the adjuster unit 6.
That is, the adjuster driving mechanism 10 is configured such that the claw portion 23 moves from the inner side to the outer side in the radial direction by the turning operation of the adjuster lever 24 in the return direction interlocked with the return operation of the secondary shoe 4 when the brake is released. It constitutes a so-called negative type drive mechanism that rotationally drives the gear 6a.

  In the case of the present embodiment, the adjuster lever 24 includes a rotation support portion 24a that is rotatably supported by the secondary shoe 4 by the lever pin 21, and one end extending from the rotation support portion 24a to the adjuster gear 6a at the tip. The structure has a first arm 24b having a claw portion 23 to be engaged and a second arm 24c extending from the rotation support portion 24a to the other side.

Further, on the secondary shoe 4, a lever return spring 28, which is a dedicated spring for urging the adjuster lever 24 in the return direction, is provided.
The lever return spring 28 is a compression coil spring interposed between the rim 4b of the secondary shoe 4 and the tip of the second arm 24c.

Further, a claw position regulating spring (claw position regulating means) that regulates the position of the claw portion 23 of the adjuster lever 24 so that the claw portion 23 moves at an appropriate height for engaging the adjuster gear 6a during the return operation of the adjuster lever 24. ) 29 is equipped.
As shown in FIG. 1, the claw position regulating spring 29 is a torsion coil spring in which a coil portion 29 a is fitted to the outer periphery of the lever pin 21, and a rotational force applying portion that biases the adjuster lever 24 in the return direction. Function as.

  The adjuster drive mechanism 10 provided in the drum brake device 100 described above is engaged with the adjuster gear 6a by the turning operation of the adjuster lever 24 in the return direction in conjunction with the return operation of the secondary shoe 4 when the brake is released. Since the claw portion 23 of the adjuster lever 24 moves from the inner side to the outer side in the radial direction and the adjuster gear 6a is rotationally driven, the over-adjustment prevention mechanism equipped in the case of the positive type becomes unnecessary. Therefore, the occurrence of an adjustment failure due to the early operation of the over-adjustment prevention mechanism does not occur.

  Moreover, since the spring for biasing the adjuster lever 24 in the return direction is not used as the shoe return spring 13 but is equipped with a dedicated lever return spring 28, one end of the pair of brake shoes 3 and 4 is provided. The shoe return spring 13 for abutting the adjuster unit 6 with the adjuster unit 6 can be arranged vertically along the adjuster unit 6 as in the case of the conventional positive type. The portion 13a is not greatly moved toward the drum center side. Therefore, it is possible to ensure a good layout property that prevents the shoe return spring 13 from interfering with the hub during braking.

  In the adjuster lever 24 of the present embodiment, the claw portion 23 of the first arm 24b is the operating point, the rotation support portion 24a supported by the secondary shoe 4 is the fulcrum, and the lever return spring 28 on the second arm 24c is contacted. Since the contact portion functions as a power point to drive the adjuster gear 6a, the adjuster gear 6a can be firmly returned even if a small compression coil spring is used as the lever return spring 28.

In the case of a negative type adjuster drive mechanism, the claw 23 of the adjuster lever 24 moves over the teeth of the adjuster gear 6a during braking and rotates the adjuster gear 6a when the brake is released. A claw position restricting means for restricting the portion 23 to an appropriate height for engaging the adjuster gear 6a is required.
Therefore, as in the present embodiment, a torsion coil spring claw position regulating spring 29 is employed as the claw position regulating means, and the coil portion 29a functions as a rotational force imparting portion that urges the adjuster lever 24 in the return direction. Then, the claw position regulating spring 29 itself has a function as a lever return spring for returning the adjuster lever 24, and the dedicated lever return spring 28 can be downsized.

1 is a front view of an embodiment of a drum brake device according to the present invention. It is sectional drawing which shows the structure of the adjuster unit used for the drum brake apparatus shown in FIG. It is explanatory drawing of the relationship between the operation direction of an adjuster lever and an adjuster gear in the drum brake apparatus shown in FIG. It is a front view of a drum brake device having a conventional positive type adjuster drive mechanism. It is a front view of a drum brake device having a conventional negative type adjuster drive mechanism.

Explanation of symbols

3 Primary shoe (brake shoe)
4 Secondary shoe (brake shoe)
6 Adjuster unit 7 Operating force generating means 8 Shoe drive mechanism 9 Backing plate 10 Adjuster drive mechanism 11 Anchor pin 13, 15, 16 Shoe return spring 21 Lever pin 24 Adjuster lever 24a Rotation support 24b First arm 24c Second arm 26 Adjuster cable 28 Lever return spring (compression coil spring)
29 Claw position regulating spring 29a Coil part 100 Drum brake device

Claims (3)

An adjuster unit also serving as a link is disposed between one end portions of the pair of brake shoes, and the adjuster unit is rotated by an adjuster lever that rotates in the return direction in conjunction with the return operation of the brake shoe when the brake is released by the hydraulic actuator . A duo-servo drum brake device having an adjuster drive mechanism for rotating an adjuster gear,
On one of said pair of brake shoes adjuster lever is pivotally mounted, together with obtain Bei lever return spring consisting of a compression coil spring for urging the adjuster lever returns in the direction, the claw portion of the adjuster lever A drum brake device comprising a claw position restricting spring for restricting the height to an appropriate height for engaging the adjuster gear . Said adjuster lever, a rotation support portion that is rotatably supported on the brake shoe, the first arm having a claw portion engaged with said adjuster gear to the tip extending on one of the rotating support, the A structure having a second arm extending from the rotation support portion to the other side,
The lever return spring, drum brake device according to claim 1, interposed by wherein the kite in between said brake shoe second arm. The claw position regulating spring is a torsion coil spring in which a coil portion is fitted to the outer periphery of the lever pin on the brake shoe, and regulates the claw portion of the adjuster lever to an appropriate height to be engaged with the adjuster gear. The drum brake device according to claim 1, wherein the adjuster lever is urged in a return direction .

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