JP6332934B2 - Automatic brake clearance adjustment device for drum brakes - Google Patents

Description

  The present invention relates to an automatic shoe gap adjusting device for a drum brake, and more particularly to a technique for improving the assembling performance when the shoe gap automatic adjusting device is assembled to a drum brake.

  The drum brake shoe gap automatic adjusting device includes: (a) a first strut member that engages with one end portion of a pair of expandable brake shoes, and an engagement with the other end portion of the pair of brake shoes. The second strut member, and the second strut member is slidably fitted in the axial direction between the first strut member and the second strut member, and rotated around the axis to thereby move the first strut member. An adjusting member with an adjusting wheel that extends a distance between the one strut member and the second strut member, and defines a standby position of the pair of brake shoes during non-braking; (b) the second A base end portion pivotally attached to the strut member, and a distal end portion extending from the base end portion toward the adjustment wheel and having a distal end portion that is an outer peripheral tooth of the adjustment wheel And an engaging lever that rotates the base wheel in one direction by the engaging portion and rotates the adjusting wheel in one direction according to the amount of expansion of the pair of brake shoes during braking. Some have For example, the shoe gap automatic adjusting device shown in Patent Document 1 is that.

  In the shoe gap automatic adjusting device as disclosed in Patent Document 1, the adjusting member with the adjusting wheel protrudes from the adjusting wheel toward the first strut member, and is screwed with the first strut member. A fitting shaft portion that protrudes from the wheel toward the second strut member and is fitted into the second strut member so as to be slidable in the axial direction is provided. In addition, a stopper that prevents the adjustment lever from excessively rotating by a biasing force of a torsion spring provided on the adjustment lever is provided between the distal end portion and the base end portion of the engagement portion of the adjustment lever. Preferably provided.

JP 2002-98180 A

  By the way, in the shoe gap automatic adjusting device as described above, the fitting shaft portion of the adjusting member is fitted into the second strut member so as to be slidable in the axial direction. When assembled to the drum brake, the fitting shaft portion of the adjusting member may fall off from the strut, and there is a problem that the assembling property of the shoe gap automatic adjusting device is relatively poor. Further, for example, it is conceivable that the adjusting lever is provided with a drop-off preventing portion for preventing the fitting shaft portion of the adjusting member from dropping from the strut. However, in addition to the stopper, the drop-off preventing portion is provided on the adjustment lever. There is a problem in that the shape of the adjusting lever cannot be simplified by providing it.

  The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a drum brake shoe that simplifies the shape of the adjust lever and improves the assembly of the automatic shoe clearance adjusting device. The object is to provide an automatic gap adjustment device.

In order to achieve this object, the gist of the present invention is that a first strut member that engages with one end portion of a pair of expandable brake shoes, and a second end portion of the pair of brake shoes. A second strut member to be engaged, and the second strut member between the first strut member and the second strut member are fitted to the second strut member so as to be slidable in the axial direction, and rotated around the axial center. and a regulating member with the adjusting wheel to extend the distance between the first strut member and a second strut member, and struts defining the standby position of the pair of brake shoes during the non-braking, the second strut A base end portion rotatably attached to the member, and the base end portion extending from the base end portion toward the adjustment wheel, and the tip end portion thereof An engagement portion that engages with the teeth, and the base end portion is rotated according to the amount of expansion of the pair of brake shoes during braking, and the adjustment wheel is rotated in one direction by the engagement portion. A shoe brake automatic adjustment device for a drum brake having an adjustment lever , wherein before the shoe gap automatic adjustment device is assembled to the drum brake, the engagement lever of the adjustment lever has a distal end thereof connected to the adjustment wheel. A bending portion that is bent so as to be positioned on the first strut member side is provided , and a screw that urges the adjustment lever to rotate the adjustment lever around the rotation center of the base end portion. A spring is provided, and the engaging portion of the adjust lever is connected to the other shoe of the pair of brake shoes from the engaging portion of the adjust lever. A contact portion is provided that extends toward the inner peripheral end surface of the web and contacts the inner peripheral end surface, and constantly urges the second strut member toward one side of the pair of brake shoes by the torsion spring. It has been.

According to the shoe brake automatic adjusting device for a drum brake of the present invention, before the shoe gap automatic adjusting device is assembled to the drum brake, the bent portion of the adjusting lever is located on the first strut member side of the adjusting wheel. Since it is positioned, there is no need to provide a stopper for preventing the adjustment lever from rotating excessively as in the conventional shoe gap automatic adjusting device, and the shape of the adjustment lever is simplified. be able to. Further, when the fitting shaft portion of the adjusting member is about to fall off from the strut, the adjusting shaft is bent by the bending portion of the adjusting lever positioned on the first strut member side of the adjusting wheel. Since the drop off from the strut is prevented, the assembling property when the shoe gap automatic adjusting device is assembled to the drum brake is improved.
The adjustment lever includes a torsion spring that urges the adjustment lever to rotate about the rotation center of the base end portion, and the adjustment lever includes an adjustment spring at the engagement portion. A contact portion that extends from the engagement portion of the lever toward the inner peripheral side end surface of the other shoe web of the pair of brake shoes and that contacts the inner peripheral side end surface is provided. The second strut member is always urged to one side of the pair of brake shoes.

Here, preferably, before Symbol second strut members, the bending portion of the adjusting lever pin for receiving the adjusting lever so as to be is positioned in the first strut member side of the adjusting wheel is formed . For this reason, before the shoe gap automatic adjusting device is attached to the drum brake, the adjusting lever is received by a pin formed on the second strut member, so that the bent portion of the adjusting lever can be The first strut member is reliably positioned on the side.

It is a front view which shows the drum brake provided with the shoe gap automatic adjustment apparatus of one Example of this invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, illustrating a configuration of the shoe gap automatic adjusting device in FIG. 1. It is a figure which shows the state at the time of the brakes of the shoe gap automatic adjustment apparatus of FIG. It is a figure which shows the state before the shoe clearance gap automatic adjustment apparatus of FIG. 2 is assembled | attached to a drum brake. It is the figure seen from the arrow A direction of the shoe gap automatic adjustment apparatus of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified for easy understanding, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 shows a leading / trailing four-wheel vehicle drum brake (hereinafter referred to as a drum brake) 12 which is a drum brake with a shoe gap automatic adjusting device 10 according to an embodiment of the present invention. It is a front view which removes and shows. The brake drum 14 is represented by two concentric circles indicated by a one-dot chain line in FIG. 1, and the circle on the center side of the two circles indicates the inner peripheral surface 16 of the brake drum 14.

  As shown in FIG. 1, the drum brake 12 has a substantially disk shape, and is, for example, a backing integrally fixed to a vehicle body side member such as an axle tube, an axle housing, and a suspension device (not shown), that is, a non-rotating member. A plate 18 is provided.

  As shown in FIG. 1, the drum brake 12 has a pair of arc-shaped brake shoes 20 and 22 disposed substantially symmetrically so as to be able to approach and separate from each other with the convex side facing outward on the outer periphery of the backing plate 18. The wheel cylinder 24 provided in a fixed position on the backing plate 18 between one end of the pair of brake shoes 20 and 22, that is, the upper end of FIG. 1, and one end of the pair of brake shoes 20 and 22 approach each other. A pair of brakes that are stretched between one end portions of the pair of brake shoes 20 and 22 so that they are always energized in the direction in which the pair of brake shoes 20 and 22 are not braked. Automatic shoe gap adjusting device for automatically adjusting the shoe gap between the shoes 20 and 22 and the brake drum 14, that is, the shoe gap. 0, an anchor 28 provided in a fixed position between the other ends of the pair of brake shoes 20 and 22, that is, the lower ends of FIG. A spring 30 is provided to always contact the lower end portion with the anchor 28.

  Each of the pair of brake shoes 20 and 22 is formed into a flat plate shape substantially parallel to the flat flat plate portion 18a of the backing plate 18 and is punched into a shape curved in an arc shape in the front view shown in FIG. Shoe webs 32 and 34, strip plate-like shoe rims 36 and 38 integrally fixed so as to have a substantially T-shaped cross section along an outer peripheral side edge forming an arc shape thereof, and the shoe rim 36 And linings 40 and 42 made of a friction material integrally fixed to the outer peripheral surfaces of the plates 38 with an adhesive or the like.

  The pair of brake shoes 20 and 22 are pressed toward the backing plate 18 by shoe hold-down devices 44 and 46 disposed on the shoe web 32 and the shoe web 34, respectively. It is held relative to each other. As shown in FIG. 1, one end of the brake shoe 20 is connected to a base end 48 a of a longitudinal flat parking brake lever 48 by a pin 50 so as to be relatively rotatable.

  As shown in FIGS. 1 to 3, the shoe gap automatic adjusting device 10 is spanned between one end portions of a pair of brake shoes 20 and 22, and the pair of brake shoes 20 and the brake brake 20 when the drum brake 12 is not braked. A strut 52 for preventing the approach of 22 and defining the standby position thereof, and an adjustment lever 54 provided in the strut 52 are provided.

  As shown in FIGS. 2 and 3, the strut 52 has a first engagement portion 56 a that engages with one end portion of the shoe web 32 of the brake shoe 20 and the base end portion 48 a of the parking brake lever 48. A first strut member 56, a longitudinal second strut member 58 having a second engaging portion 58 a that engages with one end of the shoe web 34 of the brake shoe 22, and the first strut member 56 and the second strut member 58. And an adjustment member 60 that extends the distance between the first strut member 56 and the second strut member 58 by being rotated around the axis C1.

  As shown in FIGS. 2 and 3, the adjustment member 60 has a substantially disc-shaped adjustment wheel 60 a with outer peripheral teeth formed, and a substantially columnar shape from the center of the adjustment wheel 60 a toward the first strut member 56. And a screw shaft portion 60b formed with a male screw threadedly engaged with a female screw formed on the first strut member 56, and a substantially cylindrical shape protruding from the center portion of the adjustment wheel 60a toward the second strut member 58 side. The second strut member 58 is integrally provided with a fitting shaft portion 60c slidably fitted in the direction of the axis C1 and around the axis C1. The adjustment wheel 60a is formed to have a diameter larger than the diameters of the screw shaft portion 60b and the fitting shaft portion 60c and the diameters of the first strut member 56 and the second strut member 58.

  Therefore, when the adjustment wheel 60a is rotated in the predetermined direction, for example, if the screw shaft portion 60b of the adjustment member 60 is a right-hand screw by the adjustment lever 54, the strut 52 is rotated in the counterclockwise direction. The first strut member 56 is moved away from the second strut member 58 by the action of the male screw formed on the inner strut 56b of the first strut member 56 and the female screw formed on the inner peripheral portion of the female screw hole 56b of the first strut member 56. Thus, the distance between the first engaging portion 56a of the first strut member 56 and the second engaging portion 58a of the second strut member 58, that is, the distance in the longitudinal direction of the strut 52 is extended.

  As shown in FIGS. 2 and 3, one end portion of the shoe web 32 of the brake shoe 20 and the base end portion 48 a of the parking brake lever 48 are fitted into the first engaging portion 56 a of the first strut member 56. A first notch 56c is formed in the second strut member 58 so that one end of the shoe web 34 of the brake shoe 22 is fitted into the second engaging portion 58a. A second notch 58c is formed. For this reason, the strut 52 causes the one end portion of the shoe web 32 of the brake shoe 20 and the base end portion 48 a of the parking brake lever 48 to be in the first engaging portion 56 a of the first strut member 56 by the urging force of the return spring 26. The one end of the shoe web 34 of the brake shoe 22 is brought into contact with the first contact surface 56d formed by the first notch 56c, and the second notch 58c in the second engaging portion 58a of the second strut member 58 is brought into contact with the first notch 56c. By contacting the formed second contact surface 58d, the standby positions of the pair of brake shoes 20 and 22 when the drum brake 10 is not braked are defined.

  As shown in FIGS. 1 to 3, the adjustment lever 54 is provided with a base end portion 54a rotatably attached by a substantially cylindrical pin 62 provided on the second strut member 58, and a base end portion 54a thereof. Is extended to the adjustment wheel 60a side, and the tip part engages with one of a plurality of outer peripheral teeth provided on the outer peripheral surface of the substantially disc-shaped adjustment wheel 60a when the drum brake 12 is braked by operating a brake pedal (not shown). A long flat plate-like engaging portion 54b, and an abutting portion 54c that extends from the engaging portion 54b toward the inner peripheral end surface 34a side at one end of the shoe web 34 of the brake shoe 22 and contacts the inner peripheral end surface 34a. Are integrated.

  As shown in FIGS. 1 and 4, the engaging portion 54b of the adjusting lever 54 is provided with a bent portion 54d that is bent so that its tip is positioned on the first strut member 56 side of the adjusting wheel 60a. . Further, as shown in FIG. 4, the bending portion 54 d has a distal end of the engaging portion 54 b at a predetermined interval with respect to the surface 60 d on the first strut member 56 side of the adjustment wheel 60 a in the longitudinal direction of the strut 52. It is bent so as to approach the axis C1 of the strut 52.

  As shown in FIGS. 1 to 3, the adjustment lever 54 is always urged so that the adjustment lever 54 rotates in the direction of arrow F around the axis of the pin 62 (the rotation center of the base end portion 54a) C2. A torsion spring 64 is provided. For this reason, as shown in FIG. 2, the contact portion 54c of the adjustment lever 54 causes the second strut member 58, that is, the strut 52 to move toward the brake shoe 20 side of the pair of brake shoes 20 and 22 by the biasing force of the torsion spring 64. Always energized. Note that the biasing force of the torsion spring 64 is smaller than the biasing force of the return spring 26.

  As shown in FIG. 5, the second strut member 58 receives the contact portion 54c of the adjusting lever 54 so that the bent portion 54d of the adjusting lever 54 is positioned on the first strut member 56 side of the adjusting wheel 60a. A cylindrical receiving pin 58e is formed.

  FIGS. 4 and 5 are views showing a state before the shoe gap automatic adjusting device 10 is assembled to the drum brake 12. As shown in FIGS. 4 and 5, the adjustment lever 54 is urged by the urging force of the torsion spring 64 so as to rotate in the direction of the arrow F around the axis C <b> 2 of the pin 62. When the contact portion 54c is received by the receiving pin 58e of the second strut member 58, the bent portion 54d is positioned on the first strut member 56 side of the adjustment wheel 60a. It should be noted that the receiving pin 58e of the second strut member 58 is such that the bent portion 54d of the adjusting lever 54 has the first strut member 56 of the adjusting wheel 60a when the contact portion 54c of the adjusting lever 54 is received by the receiving pin 58e. It arrange | positions so that it may be located in the side. For this reason, for example, when assembling the shoe brake automatic adjusting device 10 with the drum brake 12, if the fitting shaft portion 60c of the adjustment member 60 attempts to fall out of the fitting hole 58b of the second strut member 58, that is, the strut 52, the adjustment is performed. Since the adjustment wheel 60a contacts the bent portion 54d of the adjustment lever 54 positioned on the first strut member 56 side of the wheel 60a, the fitting shaft portion 60c of the adjustment member 60 is prevented from falling off from the strut 52. .

  The drum brake 12 configured as described above is expanded in a direction in which one end portions of the pair of brake shoes 20 and 22 are separated from each other by the wheel cylinder 24 in accordance with a brake pedal operation (not shown). Then, in a state where the linings 40 and 42 are worn and the shoe gap is increased, the pair of brake shoes 20 and 22 are expanded from the standby position by the wheel cylinder 24, and the strut 52 is brought into contact with the contact portion 54 c of the adjustment lever 54. When the pair of brake shoes 20 and 22 are moved to the brake shoe 20 side, the distance between the second strut member 58 and the brake shoe 22, that is, the amount of expansion of the pair of brake shoes 20 and 22, as shown in FIG. Thus, the base end portion 54a of the adjusting lever 54 rotates and the engaging portion 54b engages with the outer peripheral teeth of the adjusting wheel 60a, so that the adjusting wheel 60a is in a predetermined direction, for example, the screw shaft portion 60b of the adjusting member 60 is right-handed. If there is, it is turned counterclockwise. Thereby, the strut 52 is extended and the shoe gap is adjusted.

  As described above, according to the shoe gap automatic adjusting device 10 of the drum brake 12 of this embodiment, before the shoe gap automatic adjusting device 10 is assembled to the drum brake 12, the bent portion 54d of the adjustment lever 54 is adjusted to the adjustment wheel. Since it is positioned on the first strut member 56 side of 60a, there is no need to provide a stopper for preventing the adjustment lever from rotating excessively as in the conventional automatic shoe clearance adjusting device. The shape of the lever 54 can be simplified. Further, when the fitting shaft portion 60c of the adjustment member 60 tries to drop off from the strut 52, the adjustment member 60 is fitted by the bent portion 54d of the adjustment lever 54 located on the first strut member 56 side of the adjustment wheel 60a. Since the shaft portion 60c is prevented from falling off from the strut 52, the assemblability when the shoe gap automatic adjusting device 10 is assembled to the drum brake 12 is improved.

  Further, according to the shoe gap automatic adjusting device 10 of the drum brake 12 of this embodiment, the adjustment lever 54 is attached so that the adjustment lever 54 is rotated about the rotation center of the base end portion 54a by the torsion spring 64. The second strut member 58 is formed with a receiving pin 58e for receiving the adjustment lever 54 so that the bent portion 54d of the adjustment lever 54 is positioned on the first strut member 56 side of the adjustment wheel 60a. ing. For this reason, before the shoe gap automatic adjusting device 10 is attached to the drum brake 12, the adjusting lever 54 is received by the receiving pin 58e formed on the second strut member 58, whereby the bent portion 54d of the adjusting lever 54 is obtained. Is reliably positioned on the first strut member 56 side of the adjustment wheel 60a.

  As mentioned above, although one Example of this invention was described based on drawing, this invention is applied also in another aspect.

  For example, in the shoe gap automatic adjusting device 10 of this embodiment, before the shoe gap automatic adjusting device 10 is assembled to the drum brake 12, the adjusting lever 54 is received by the receiving pin 58e, so that the bending of the adjusting lever 54 is performed. Although the portion 54d is positioned on the first strut member 56 side of the adjusting wheel 60a, the receiving pin 58e is not necessarily provided on the second strut member 58. For example, in a free state where no external force is applied, the adjusting lever 54 is used by using a torsion spring 64 formed so that the bent portion 54d of the adjusting lever 54 is positioned on the first strut member 56 side of the adjusting wheel 60a. The bent portion 54d may be positioned on the first strut member 56 side of the adjustment wheel 60a.

  Further, in the shoe gap automatic adjusting device 10 of the present embodiment, the bent portion 54d of the adjustment lever 54 is spaced from the surface 60d of the adjustment wheel 60a on the first strut member 56 side by a predetermined distance. Although the tip is bent so as to approach the axis C1 of the strut 52, the bent portion 54d of the adjust lever 54 may have any shape. That is, as long as the tip of the engaging portion 54b of the adjusting lever 54 is bent so as to be positioned on the first strut member 56 side of the adjusting wheel 60a, the shape of the bent portion 54d of the adjusting lever 54 is any shape. It may be.

  Further, in the shoe gap automatic adjusting apparatus 10 of the present embodiment, the base end portion 54a of the adjusting lever 54 rotates according to the amount of expansion of the pair of brake shoes 20 and 22, and the adjusting wheel 60a is moved by the engaging portion 54b. For example, the strut 52 may be extended by rotating the adjustment wheel 60a in a predetermined direction by returning the engagement portion 54b of the adjustment lever 54 when the drum brake 12 is released.

  Moreover, although the drum brake 12 of the present Example was used for the four-wheeled vehicle, it can also be applied to vehicles other than the four-wheeled vehicle, such as a two-wheeled vehicle.

  Although not illustrated one by one, the present invention can be implemented in variously modified and improved modes based on the knowledge of those skilled in the art.

10: Automatic shoe clearance adjustment device 12: Drum brake 20, 22: A pair of brake shoes 52: Strut 54: Adjust lever 54a: Base end portion 54b: Engaging portion 54d: Bending portion 56: First strut member 58: Second Strut member 58e: receiving pin (pin)
60: Adjustment member 60a: Adjustment wheel C1: Axle

Claims (2)

A first strut member that engages with one end portion of the pair of expandable brake shoes, a second strut member that engages with the other end portion of the pair of brake shoes, the first strut member, The second strut member is slidably fitted in the axial direction between the two strut members and rotated around the axial center, thereby increasing the distance between the first strut member and the second strut member. An adjustment member with an adjusting wheel that extends, and a strut that defines a standby position of the pair of brake shoes during non-braking,
A base end portion rotatably attached to the second strut member, and an engagement portion that extends from the base end portion toward the adjustment wheel and that engages with the outer peripheral teeth of the adjustment wheel. Shoe gap automatic adjustment of a drum brake having an adjusting lever that rotates the base end in accordance with the amount of expansion of the pair of brake shoes during braking and rotates the adjusting wheel in one direction by the engaging portion. A device,
Before the shoe gap automatic adjusting device is assembled to the drum brake, the engaging portion of the adjustment lever has a bent portion that is bent so that its tip is located on the first strut member side of the adjusting wheel. Provided ,
The adjustment lever includes a torsion spring that urges the adjustment lever to rotate about the rotation center of the base end portion,
The adjusting lever engaging portion extends from the adjusting lever engaging portion toward the inner peripheral side end surface of the other shoe web of the pair of brake shoes and contacts the inner peripheral side end surface. An automatic shoe gap adjusting device for a drum brake, comprising: a contact portion that constantly urges the second strut member toward one side of the pair of brake shoes by a torsion spring . The front Stories second strut member, said adjustment lever bent portion of the first drum brake of claim 1 pin for receiving the adjusting lever so as to be is positioned to the strut member side is formed of the adjusting wheel Automatic shoe clearance adjustment device.

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