JP4571034B2 - Drum brake - Google Patents

Description

  The present invention relates to a drum brake, and more particularly to a technique for holding a brake shoe.

  In general, in a drum brake, for example, as in the drum brake shown in FIG. 3 of Patent Document 1, a shoe hold down device in which a shoe web of a brake shoe and a backing plate are always urged in the approaching direction, and the brake shoe. Using a ledge (not shown) protruding from the backing plate for determining the position of the shoe web, the shoe web is held relative to the backing plate in a plane direction. However, in such a drum brake, a shoe hold-down device for holding the brake shoe in an expandable manner is used, but such a shoe hold-down device has a large number of parts and is troublesome to assemble. Therefore, the device cannot be manufactured at a low cost, and the backing plate has a ledge necessary for positioning the brake shoe, because the backing plate cannot be made thin due to a large stress applied to the backing plate. In addition, there is a problem in that it is difficult to reduce the size of the drum brake because the shape of the backing plate is limited.

On the other hand, a brake shoe holding device as shown in FIGS. 9 and 10 is conceivable. The brake shoe holding device includes a brake shoe holding member 115 having two pairs of guide protrusions 115a protruding to the outer peripheral side in order to sandwich the shoe webs of the first brake shoe 113 and the second brake shoe 114 in the plate thickness direction. It is fixed to the backing plate 112 and is guided in a direction parallel to the surface of the backing plate 112 by sandwiching the shoe webs of the first brake shoe 113 and the second brake shoe 114 using the guide projection 115a. The first brake shoe 113 and the second brake shoe 114 are accurately positioned in a direction perpendicular to the backing plate 112 and are held so as to be relatively movable in a direction parallel to the surface of the backing plate 112.
JP 2003-56610 A

  However, in the above-described drum brake, since the brake shoe holding member 115 includes the two pairs of guide protrusions 115a that sandwich the shoe web of the brake shoe in the plate thickness direction, the shape of the brake shoe holding member 115 becomes complicated, and the brake In the shoe holding member 115, high processing accuracy is required for the guide protrusion 115 a for positioning the first brake shoe 113 and the second brake shoe 114, so that it is difficult to form the brake shoe holding member 115, and the brake shoe holding device That is, there is a problem that the manufacturing cost of the drum brake equipped with the same increases.

  The present invention has been made against the background of the above circumstances, and its object is to easily manufacture a brake shoe holding member for holding a brake shoe and to provide a drum brake at low cost. It is in.

That is, the gist of the invention according to claim 1 is that the backing plate, the pair of first brake shoes and the second brake shoes disposed on the backing plate, the pair of first brake shoes and the first brake shoe, 2 A drum brake including a brake shoe holding member fixed to a backing plate having a holding projection protruding to the outer peripheral side in order to hold the brake shoe in an expandable manner. The shoe web portion and the shoe rim portion of the first brake shoe and the second brake shoe are integrally formed, and (b) the shoe web portion is formed with an engagement hole that opens to the inner peripheral side. c) holding projection of the brake shoe holder is inserted into the engaging hole, (d) the shoe web portion, the brake shoe holder Having the characteristics nipping the holding projection portion at a predetermined elastic force.

According to the first aspect of the present invention, the backing plate, the pair of first brake shoes and the second brake shoes disposed on the backing plate, and the pair of first brake shoes and second brake shoes are expanded. A drum brake including a holding member protruding to the outer peripheral side for holding the opening in an open manner and including a brake shoe holding member fixed to the backing plate, wherein the pair of first brake shoe and second brake The shoe web portion and the shoe rim portion of the shoe are integrally formed, and the shoe web portion is formed with an engagement hole that opens to the inner peripheral side, and the holding projection of the brake shoe holding member is Since the first brake shoe and the second brake shoe are inserted into the engagement hole, The shoe web portion is provided with an engagement hole for holding the brake shoe holding member, and the brake shoe holding member is provided with a holding projection to be fitted into the engagement hole. As a result, the shape becomes simple and the drum brake can be constructed at low cost. Further, since the shoe web portion clamps the holding projection of the brake shoe holding member with a predetermined elastic force, the shoe web portion has a backlash between the engagement hole of the shoe web portion and the holding projection of the brake shoe holding member. Suppression is suppressed.

  Furthermore, since the shoe web portion and the shoe rim portion of the pair of first brake shoe and second brake shoe are integrally formed and are not joined using welding, thermal stress is not generated in the shoe rim portion, Deformation does not occur. Therefore, the process of removing the deformation of the bonding surface of the shoe rim portion in order to bond the lining to the shoe rim portion after welding is eliminated, and the drum brake can be configured at low cost.

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

  FIG. 1 is a front view of a parking brake duo-servo type drum brake (hereinafter referred to as drum brake) 10 according to an embodiment of the present invention, with a brake drum 11 removed. The outer peripheral surface is indicated by a one-dot chain line. The drum brake 10 has a substantially disc shape, and includes, for example, a backing plate 12 that is integrally fixed to a non-rotating member such as an axle tube, an axle housing, and a suspension device (not shown), and an outer peripheral portion of the backing plate 12. A pair of first brake shoes 13 and second brake shoes 14 that are arranged symmetrically so as to be close to and away from each other with the arcuate convex side facing outward, and the first brake shoes 13 and the second brake shoes. 14 and the brake shoe holding member 15 fixedly contacted to the inner peripheral portion of the backing plate 12, and between the one end portions of the pair of first brake shoes 13 and second brake shoes 14, the backing plate 12 is firmly contacted. Expansion device for moving the first brake shoe 13 and the second brake shoe 14 toward and away from each other 6 and a gap adjusting device 17 that adjusts the shoe gap by being extended along with the rotation of the adjusting wheel 17a interposed between the other ends of the pair of first brake shoes 13 and second brake shoes 14, An intermediate portion for generating an urging force for constantly energizing the other end portions in a direction approaching each other and pinching the gap adjusting device 17 is provided with a spring 18 wound in a coil shape.

  As shown in FIG. 2, the expansion device 16 includes a cam shaft portion 19 a that abuts between one end portions of the first brake shoe 13 and the second brake shoe 14 and penetrates the backing plate 12 and the cam shaft portion. A T-shaped cam member 19 provided with a cam portion 19b extending along the radial direction of the backing plate 12 at one end portion of 19a, a holding member 20 for holding the cam shaft portion 19a rotatably about its axis, The pair of pins 21 and 22 that integrally fix the holding member 20 and the brake shoe holding member 15 to the backing plate 12, one end of the pair of pins 21 and 22, and the pair of first brake shoes 13. And a pair of intermediate portions wound around the second brake shoe 14 and coiled in an intermediate portion for urging the second brake shoe 14 in a direction in which both ends are brought into contact with the cam member 19. Between the return springs 23 and 24, a lever 26 attached to the other end of the cam shaft portion 19a by the lever pin 25 so as not to be relatively rotatable, and a latch member 27 fixedly connected to the lever 26 and the backing plate 12. A return spring 28 is provided which is hooked and has an intermediate portion wound in a coil shape.

  The first brake shoe 13 and the second brake shoe 14 have a flat plate shape substantially parallel to the plate surface of the backing plate 12, and the shoe web portions 13b and 14b are curved in an arc shape in the front view shown in FIG. And arc-shaped shoe rim portions 13a and 14a having a substantially T-shaped cross section along the outer peripheral side edge forming the arc shape. The outer peripheral surfaces of the shoe rim portions 13a and 14a are provided with linings 29 and 30 which are friction materials fixed integrally with an adhesive or the like.

  The shoe web portions 13b and 14b and the shoe rim portions 13a and 14a are not formed by joining the shoe rim and the shoe web, which are punched from different steel plates and subjected to predetermined bending, using resistance welding or fillet welding. These are integrally formed by bending from a single steel plate by roll forming and press forming. For this reason, the shoe web portions 13b and 14b are formed by stacking a pair of plate members in the thickness direction as shown in FIG. 3, and the inner portions are partially separated in the circumferential direction. An engagement hole 31 that opens to the circumferential side is formed.

  The brake shoe holding member 15 is a high-strength part press-formed from a steel plate thicker than the backing plate 12, and is a vehicle body side member (non-rotating) such as a suspension device not shown in the center of the backing plate 12. The holding projection 15a protruding to the outer peripheral side to hold the first brake shoe 13 and the second brake shoe 14 is symmetrically fixed to the member) with the backing plate 12 by bolts. Two pairs are provided.

  Since the holding projection 15a provided in the brake shoe holding member 15 is slidably fitted in the engagement hole 31 provided in the shoe web portions 13b and 14b, the first brake shoe 13 and the second brake shoe 13 are provided. The brake shoe 14 is guided and held so as to be capable of relative movement, that is, diameter expansion and contraction, in a direction parallel to the surface of the backing plate 12.

  As shown in FIG. 4, the holding projection 15a of the brake shoe holding member 15 is inserted into the engagement hole 31 of the shoe web portion 13b and the shoe web portion 13b of the first brake shoe 13 is in the parking brake braking state. The width dimension of the engagement hole 31 of the shoe web portion 13b is set to be slightly larger than the thickness of the holding projection 15a so that the relative movement can be smoothly performed at the time of release. The dimensional relationship between the width of the engagement hole 31 of the shoe web portion 14b of the second brake shoe 14 and the thickness of the holding projection 15a is the same as described above.

  Further, as shown in FIGS. 1 and 2, the return springs 23 and 24 are stretched between one end of the pins 21 and 22 and the shoe web portions 13b and 14b, and therefore the shoe web portions 13b and 14b. Since a biasing force is generated from the position where the pin 21 and 22 are latched to the position where the pins 21 and 22 are latched, the biasing force has a slight component in the vertical direction with respect to the surface of the backing plate 12. The brake shoe 13 and the second brake shoe 14 tend to tilt. For this reason, the holding projection 15a of the brake shoe holding member 15 and the engagement hole 31 of the shoe web portions 13b and 14b are always in contact with each other so that there is no rattling between them and noise is generated even when the vehicle travels. Absent.

  In the drum brake 10 of the present embodiment configured as described above, the parking brake is operated via a brake cable (not shown) attached to the end of the lever 26 opposite to the cam member 19 side. When the force is applied, the lever 26 is rotated against the urging force of the return spring 28, and the cam member 19 is rotated about its axis. Therefore, one end portions of the pair of first brake shoes 13 and second brake shoes 14 contacting both surfaces of the cam portion 19b in FIG. 1 are separated against the urging force of the return springs 23 and 24, and the pair of first brake shoes The brake shoe 13 and the second brake shoe 14 are pressed against the inner peripheral surface of the brake drum 11 to generate a braking force. When the operation force of the parking brake is released, the lever 26 is returned to the original position in accordance with the urging force with the return spring 28, and the first brake shoe 13 and the second brake shoe are in accordance with the urging force of the pair of return springs 23 and 24. 14 is returned to the original position shown in FIG. The braking torque generated in the first brake shoe 13 and the second brake shoe 14 of the drum brake 10 of the present embodiment is received by the pins 21 and 22 from either the first brake shoe 13 or the second brake shoe 14. .

  Here, in the drum brake 10 of the present embodiment, the shoe web portions 13b and 14b and the shoe rim portions 13a and 14a of the pair of the first brake shoe 13 and the second brake shoe 14 are integrally formed, The shoe web portions 13b and 14b are formed with an engagement hole 31 that opens to the inner peripheral side, and the holding projection 15a of the brake shoe holding member 15 is inserted into the engagement hole 31, The pair of first brake shoes 13 and second brake shoes 14 can be held so as to be relatively movable in the surface direction with respect to the backing plate 12, and the shoe web portions 13 b and 14 b hold the brake shoe holding member 15. The engagement projection 31 is provided, and the brake shoe holding member 15 is fitted into the engagement hole 31. a is the shape is simplified by provided, the drum brake 10 can be constructed at low cost.

  Further, the shoe web portions 13b and 14b and the shoe rim portions 13a and 14a of the pair of the first brake shoe 13 and the second brake shoe 14 are integrally formed and are not joined using welding. No thermal stress is generated in 13a and 14a, and no deformation occurs. Therefore, there is no step of removing deformation of the bonding surfaces of the shoe rim portions 13a and 14a in order to bond the linings 29 and 30 to the shoe rim portions 13a and 14a after welding, and the drum brake 10 can be configured at low cost.

  In the drum brake 10 of the above-described embodiment, the shoe web portions 13b, 14b and the shoe rim portions 13a, 14a of the first brake shoe 13 and the second brake shoe 14 are bent from a single steel plate by roller forming. As a result of the bending, a pair of plate members are stacked in the thickness direction, and the pair of plate members are locally separated. Therefore, the brake is produced by separately molding the shoe web and the shoe rim and welding each other. Compared to manufacturing the shoe, the labor for manufacturing the first brake shoe and the second brake shoe is reduced, and the drum brake 10 can be configured at low cost.

  In the drum brake 10 of the embodiment, at least one end is hung on the pair of first brake shoes 13 and second brake shoes 14 in order to reduce the diameter of the pair of first brake shoes 13 and second brake shoes 14. The return springs 23 and 24 are stopped, and the return springs 23 and 24 are arranged on the first brake shoe 13 and the second brake shoe 14 at a position offset by a predetermined dimension from the center in the thickness direction of the shoe web portions 13b and 14b. Since it is latched, the surfaces of the shoe web portions 13b and 14b are inclined with respect to the surface of the backing plate 12, and the brake shoe holding member 15 comes into contact with the engagement holes 31 of the shoe web portions 13b and 14b. Shoe holding member 15 and shoe web 1 Rattling between the engaging hole 31 b and 14b are suppressed.

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

  For example, the drum brake 10 of the above-described embodiment is configured to have a duo-servo type drum brake. However, other types such as a leading trailing type and a two-leading type drum brake may be used. There is no problem. In order to expand the first brake shoe 13 and the second brake shoe 14, a wheel cylinder may be provided in place of the cam member 19.

  Further, two return springs 23 and 24 of the drum brake 10 of the above-described embodiment are stretched between the shoe web portion 13b and the pin 21 and between the shoe web portion 14b and the pin 22, as shown in FIGS. As shown, only one return spring 32 may be stretched between the first brake shoe 13 and the second brake shoe 14.

  In the drum brake 10 of the above-described embodiment, the engagement holes 31 formed in the shoe web portions 13b and 14b may be formed long in the circumferential direction as shown in FIGS.

  Further, the shoe web portions 13b and 14b of the drum brake 10 of the above-described embodiment are merely provided with the engagement holes 31 into which the holding projections 15a of the brake shoe holding member 15 are inserted. As shown in FIG. 4, spring portions 13c and 14c for clamping the holding projection 15a of the brake shoe holding member 15 with a predetermined elastic force may be provided. Further, in this case, since the spring portions 13c and 14c sandwich the holding projection 15a of the brake shoe holding member 15, rattling between the engagement hole 31 and the brake shoe holding member 15 is suppressed, and the return springs 23 and 24 are There is no need to hook the first brake shoe 13 and the second brake shoe 14 at a position offset by a predetermined dimension from the center in the thickness direction of the shoe web portions 13b and 14b.

  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.

It is a figure which shows the drum brake provided with the brake shoe holding | maintenance apparatus which is one Example of this invention. FIG. 2 is a sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. It is a figure which shows the drum brake provided with the brake shoe holding | maintenance apparatus which is another Example of this invention. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. FIG. 3 is a cross-sectional view taken along the line III-III of an example in which the engagement hole of the shoe web portion in FIG. It is VIII-VIII sectional view taken on the line in FIG. It is a figure which shows the drum brake provided with the brake shoe holding | maintenance apparatus which is a prior art example. FIG. 10 is a sectional view taken along line XX in FIG. 9.

Explanation of symbols

10: drum brake 12: backing plate 13: first brake shoe 13a: shoe rim portion 13b: shoe web portion 13c: spring portion 14: second brake shoe 14a: shoe rim portion 14b: shoe web portion 14c: spring portion 15: brake shoe Holding member 15a: Holding projection 23: Return spring 24: Return spring 31: Engagement hole

Claims (1)

A backing plate, a pair of first brake shoes and a second brake shoe disposed on the backing plate, and an outer peripheral side for holding the pair of first brake shoes and the second brake shoes in an expandable manner A drum brake including a brake shoe holding member fixed to the backing plate and having a protruding protrusion.
The shoe web portion and the shoe rim portion of the pair of first brake shoes and second brake shoes are formed integrally.
The shoe web portion is formed with an engagement hole that opens to the inner peripheral side,
The holding projection of the brake shoe holding member is inserted into the engagement hole ,
The brake shoe holding device for a drum brake, wherein the shoe web portion clamps a holding protrusion of the brake shoe holding member with a predetermined elastic force .

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