JPH0738763U - Duo servo type drum brake - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the manufacturing cost by simplifying the structure of the anchor pin, and further to reduce the manufacturing cost of the duo servo type drum brake. [Structure] The anchor pin 30 has a substantially columnar shape as a whole, and has a serration portion 38 having an outer peripheral surface having a sawtooth cross-section perpendicular to the axis, and a torque receiving portion having a diameter smaller than that of the serration portion 38. And 42. The caliper support blanket 44 fixed to the back side of the backing plate 10 is provided with a through hole 46 to form a protrusion 48 protruding toward the shoe web 22 side, and a recess 50 formed by the protrusion 48. A reinforcing plate 52 that completely covers is fixed. The reinforcing plate 52 is provided with a through hole 54 whose axis coincides with that of the through hole 46. The anchor pin 30 is fixed to the through holes 46 and 54 by being press-fitted from the reinforcing plate 52 side with the torque receiving portion 42 side being the tip.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a duo-servo type drum brake, and more particularly to an improvement of an anchor portion that receives one end portion of a pair of brake shoes.

[0002]

[Prior art]

 A pair of shoe rims curved in an arc shape and shoe webs projecting from the inner peripheral surface of the shoe rim and arranged substantially parallel to the back plate, and provided so as to be capable of expanding relative to each other on the back plate. , A duo-servo type drum brake is known, which includes a pair of brake shoes and an anchor portion that receives one end of the shoe web of the pair of brake shoes.

[0003]

[Problems to be solved by the device]

 Conventionally, the above-mentioned anchor portion has a substantially columnar shape at an axially intermediate portion as shown in FIG. 4 which is a cross section of the anchor portion of a disc brake including the above-mentioned duoservo type drum brake as a parking brake mechanism. An anchor pin 76 having a wide portion 74 expanded in one diameter direction is inserted into the backing plate 10, the caliper support blanket 44, and the reinforcing plate 52 from the backing plate 10 side, and is a columnar shape protruding toward the reinforcing plate 52 side. The portion 78 is fixed by hot or cold caulking to prevent the portion from falling off, and the wide portion 74 is fixed by a rivet 80 to reinforce. The anchor pin 76 receives a force in a direction perpendicular to the axial center from only one shoe web 22 when the pair of brake shoes is controlled to expand. In such a case, unless the wide portion 74 is provided and fixed, the strength to withstand the braking force received from the brake shoe cannot be obtained. Therefore, the wide portion 74 is provided and fixed by the rivet 80, and the fixing position is preferably separated from the axis of the anchor pin 76 as much as possible in order to obtain strength in the falling direction. Therefore, there is a problem that the shape of the anchor pin 76 becomes complicated and the manufacturing cost becomes high, and the manufacturing cost of the duo servo type drum brake also becomes high.

The present invention has been made in view of the above circumstances, and its purpose is to reduce the manufacturing cost by simplifying the structure of the anchor pin, and further, to extend the duo servo type drum brake. To reduce the manufacturing cost of.

[0005]

[Means for Solving the Problems]

 In order to achieve such an object, the gist of the present invention is to provide a shoe rim curved in an arc shape and a shoe web projecting from the inner peripheral surface of the shoe rim and arranged substantially parallel to the back plate. And a pair of brake shoes provided on the back plate of the pair of brake shoes so as to be capable of expanding, and an anchor portion for receiving one end of the shoe web of the pair of brake shoes facing each other. In the brake, the anchor portion includes (a) a columnar portion with which one end of the shoe web abuts on the outer peripheral surface, and a serration portion having an outer peripheral surface having a sawtooth cross section perpendicular to the axis. And (b) a first through hole having a diameter slightly smaller than the diameter of the anchor pin, and a part of the back plate so that the periphery of the first through hole protrudes to the shoe web side. A bent formed Part, and (c) a second through hole having a diameter substantially similar to that of the first through hole, and the first through hole and the second through hole are aligned in the axial center, and the back plate is A reinforcing plate fixed to the surface opposite to the shoe web, and (d) the anchor pin so that the first and second through holes are both located in the serration portion, and the cylindrical portion side. It is formed by press-fitting into the first and second through holes from the side of the reinforcing plate with the tip as a tip.

[0006]

[Effect of action and device]

 With this configuration, the first and second through holes provided in the back plate and the reinforcing plate are located separately from each other, so that the pair of brake shoes is expanded and one shoe web is opened during braking. When the anchor pin receives a force in the direction perpendicular to the axis from only the fulcrum, the anchor pin rotates about the contact part with the first through hole of the back plate (contact part with the first through hole) and the action point. The distance to the (contact portion with the second through hole) becomes extremely large, and an extremely large force is required for rotation. Therefore, the strength of the anchor pin in the falling direction can be obtained without fixing the wide part as in the past. Moreover, since the anchor pin is provided with a serration part and the anchor pin is press-fitted so that the first and second through holes are located in this serration part, a large pull-out load can be obtained only by press-fitting from the reinforcing plate side. To be Therefore, it is not necessary to provide a wide portion on the anchor pin, the shape is simplified and the manufacturing cost is reduced, and further, the manufacturing cost of the duo servo type disc brake is reduced.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing an essential part of an example of a duo-servo type drum brake to which the present invention is applied, and is used as a parking brake mechanism of a drum-in disc brake, for example. In FIG. 1, on the backing plate 10, a pair of brake shoes 12 and 14 having an arc shape as a whole are supported by shoe hold down devices 16 and 18 so as to be capable of expanding. The brake shoes 12, 14 are a strip-shaped shoe rim 20 bent in an arc shape, and a plate-shaped shoe web 22 projecting from the inner peripheral surface of the shoe rim 20 and arranged substantially parallel to the backing plate 10. And a lining 24 fixed to the outer peripheral surface of the shoe rim 20, respectively, and one end portion of the shoe web 22 of the brake shoes 12 and 14 located downward in FIG. 1 has an axial length. The variable connection adjusting device 26 is engaged with each other in accordance with the biasing force of the shoe-to-shoe spring 28 that is stretched between both ends.

The other end of the shoe web 22 is adapted to be brought into contact with an anchor pin 30 fixed on the backing plate 10, and a male screw member 32 screwed to the front end surface of the anchor pin 30 and a male screw member 32. The shoe return springs 34, 36 stretched between the brake shoes 12, 14 are constantly urged toward the anchor pin 30. The anchor pin 30 has a substantially columnar shape as a whole, and as shown in the cross-sectional view of FIG. 2, a selection portion 38 having an outer peripheral surface having a sawtooth-shaped cross section perpendicular to the axis, and the selection portion 38. It is composed of a head 40 having a diameter larger than the serration portion 38 and continuously formed on one end side thereof, and a torque receiving portion 42 having a diameter smaller than the serration portion 38 and continuously formed on the other end side thereof. . A female screw is formed at the end of the torque receiving portion 42 opposite to the serration portion 38, and the male screw member 32 is screwed therein.

A caliper support blanket 44 is fixed to the back side of the backing plate 10. The caliper support blanket 44 is provided with a through hole 46, and a part of the periphery of the through hole 46 is formed into a substantially rectangular shape as shown in a perspective view in FIG. A convex portion 48 that protrudes inward is formed, and a portion around the convex portion 48 of the backing plate 10 is largely removed. Further, on the surface of the caliper support blanket 44 opposite to the backing plate 10, there is provided a reinforcing plate 52 that completely covers the recess 50 formed by the projection 48, for example, in the peripheral portion at 2 to 4 places. It is fixed by spot welding. The reinforcing plate 52 is provided with a through hole 54 provided in the caliper support blanket 44 and a through hole 54 whose axis coincides with the through hole 46. The anchor pin 30 is fixed to the through holes 46 and 54 by press-fitting from the reinforcing plate 52 side with the torque receiving portion 42 side as the tip, and the portion protruding toward the shoe web 22 side of the serration portion 38 is It is caulked after press fitting for reinforcement. In this embodiment, the torque receiving portion 42 is a cylindrical portion, the caliper support blanket 44 is a back plate, the convex portion 48 is a mounting portion, the through hole 46 is a first through hole, and the through hole 54 is a first through hole. Each corresponds to two through holes.

The shoe web 22 of one of the brake shoes 12 is provided with a parking brake lever 56 having a longitudinal plate shape so as to be rotatable at one end thereof, and the parking brake lever 56 has an intermediate portion in the longitudinal direction. Struts 58 are bridged between the part and the other brake shoe 14. One end of a parking cable 62 slidably accommodated in a spring 60 is connected to the other end of the parking brake lever 56, and the other end of the parking cable 62 is, for example, a foot-operated parking brake. It is connected to a parking brake pedal (not shown) of the operation force input device. In FIG. 1, 64 is a shoe floating prevention plate, 66 is a cable guide, 68 is a disc cover, 70 is a caliper, and in FIG. 2, 72 is a disc rotor.

In the duo servo type drum brake described above, when the parking cable 62 is pulled rightward in FIG. 1 by, for example, depressing the parking brake pedal, the parking brake lever 56 moves the fulcrum provided on the anchor pin 30 side. It is rotated counterclockwise as the center. As the parking brake lever 56 rotates, the strut 58 is moved to the right in the figure, and the pressing force of the strut 58 presses the one brake shoe 14 against the disc rotor 72. The above pressing force is transmitted to the other brake shoe 12 via the connection adjusting device 26, and the brake shoe 12 is also pressed by the disc rotor 72, so that the parking brake action is obtained. At this time, one end of the shoe web 22 of one brake shoe 14 is separated from the anchor pin 30 by being pressed by the strut 58, while one end of the shoe web 22 of the other brake shoe 12 is moved downward in the figure. Since the end portion on the side is pressed against the brake shoe 14 via the connection adjusting device 26, it is pressed against the anchor pin 30 by the pressing force. That is, the anchor pin 30 receives a force in the direction perpendicular to the axis only from the shoe web 22 of the brake shoe 12 while the braking is being performed, so that the anchor pin 30 needs to have sufficient tilting strength.

For this reason, conventionally, as shown in FIG. 4, an anchor pin 76 having a wide cylindrical portion 74 that is substantially cylindrical and is enlarged in a straight radial direction at an axially intermediate portion is used as a backing plate 10 and a caliper support. The blanket 44 and the reinforcing plate 52 are inserted from the backing plate 10 side, and the columnar portion 78 protruding to the reinforcing plate 52 side is fixed by hot or cold caulking to prevent falling out, and The wide portion 74 was fixed and reinforced by a pair of rivets 80. However, in such a structure, there is a problem that the shape of the anchor pin 76 becomes complicated and the manufacturing cost becomes high, and the manufacturing cost of the duo servo type drum brake also becomes high.

On the other hand, according to the present embodiment, the circumference of the through hole 46 of the caliper support blanket 44 is formed into the convex portion 48 protruding toward the shoe web 22 side, and the penetrating hole 46 is penetrated so as to cover the recess 50. Since the reinforcing plate 52 having the hole 54 is fixed to the caliper support blanket 44, the anchor pin 30 is centered on the contact portion with the through hole 46 of the caliper supported blanket 44 as compared with the conventional anchor pin 76. As a result, the distance between the fulcrum (contact portion with the through hole 46) and the action point (contact portion with the through hole 54) when rotating becomes extremely large, and an extremely large force is required for rotation. Therefore, the tilting strength of the anchor pin 30 can be sufficiently obtained without providing and fixing the wide portion 74 as in the prior art.

Moreover, since the anchor pin 30 is provided with the serration portion 38 and the anchor pin 30 is press-fitted so that the through holes 46 and 54 are located in the serration portion 38, only the press-fitting from the reinforcing plate 52 side is performed. A large pull-out load can be obtained. Therefore, it is not necessary to provide the wide portion 74 on the anchor pin 30, the shape is simplified and the manufacturing cost is reduced, and further, the manufacturing cost of the duo servo type disc brake is reduced.

Further, according to the present embodiment, the recess 50 is completely covered with the reinforcing plate 52, and the serration portion 38 of the anchor pin 30 has a closed cross-section structure. When the blanket 44 has the same thickness, the anchor pin 30 does not fall even if the braking force received from the brake shoe 22 is relatively large. If it is not necessary to cause a fall to the same braking force as the conventional one, the caliper support blanket 44 can be made thinner, and the duo servo disc brake can be made lighter. Is.

FIG. 5 is a perspective view showing a caliper support blanket 82 used in another embodiment. In this caliper support blanket 82, the convex portions 84 are provided along the sides. Therefore, in the assembled state shown in FIG. 2, one side surface of the convex portions 84 is open. When the braking force received from the brake shoes 22 is relatively small, the caliper support blanket 82 having such a shape may be used.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in still another mode.

For example, in the above-described embodiment, the case where the present invention is applied to the drum-in disc brake provided with the caliper support blankets 44 and 82 has been described, but the present invention is also applicable to a normal duo-servo type drum brake. Applied. In that case, for example, instead of the caliper support blankets 44 and 82, the convex portions 48 and 84 may be provided on the backing plate 10, and the thickness of the backing plate 10 may be appropriately changed according to the required strength. .

Further, in the above-described embodiment, after the anchor pin 30 is press-fitted, the portion of the serration portion 38 projecting to the shoe web 22 side is caulked, but this caulking is not always necessary.

Although not illustrated one by one, the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a duo-servo type drum brake to which the present invention is applied, and is a diagram showing a main part.

FIG. 2 is a view showing a cross section taken along line II-II in FIG.

3 is a perspective view showing a main part of a caliper support blanket used in the duo servo type drum brake of FIG. 1. FIG.

FIG. 4 is a view showing a conventional anchor pin.

FIG. 5 is a perspective view showing a main part of a caliper support blanket used in another embodiment of the present invention, and is a view corresponding to FIG. 2;

[Explanation of sign]

 30: Anchor pin 38: Serration part 42: Torque receiving part (cylindrical part) 44: Caliper support blanket (back plate) 46: Through hole (first through hole) 48: Convex part (mounting part) 52: Reinforcing plate 54: Through hole (second through hole)

Claims (1)

[Scope of utility model registration request] 1. A shoe rim curved in an arc shape and a shoe web projecting from the inner peripheral surface of the shoe rim and arranged substantially parallel to the back plate, and can be expanded on the back plate. A duo-servo type drum brake, comprising: a pair of brake shoes provided on a pair of brake shoes; and an anchor portion that receives one end portion of a pair of shoe webs of the pair of brake shoes, the anchor portion including an outer peripheral surface of the shoe. An anchor pin having a cylindrical portion with which one end of the web abuts and a serration portion having an outer peripheral surface having a sawtooth-shaped cross section perpendicular to the axis, and a first through hole having a diameter slightly smaller than the diameter of the anchor pin. A mounting portion formed by bending a part of the back plate so that the periphery of the first through hole projects toward the shoe web side; and a mounting portion having a diameter substantially similar to that of the first through hole. With two through holes, the first consistent A reinforcing plate fixed to a surface of the back plate opposite to the shoe web in a state where axes of the hole and the second through hole are aligned with each other, the anchor pin, the first and second It is characterized in that it is formed by press-fitting into the first and second through holes from the reinforcing plate side with the cylindrical portion side as a tip so that all the through holes are located in the serration portion. Duo servo type drum brake.