JP2007278331A - Shoe hold-down device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shoe hold-down device whose height from a shoe web is lowered. <P>SOLUTION: Shoe hold-down springs 52a, 54a have wire rods spirally rolled so that their center lines are not overlapped with each other in the energizing direction, so that heights H of the shoe hold-down springs 52a, 54a from the shoe webs 28, 30 can be lowered in the energizing direction when energizing brake shoes 18, 20 to the side of a backing plate 16. Thus, a space between each of the shoe hold-down devices 52, 54 and a rotary drum 12 is increased, resulting in a higher degree of freedom in designing a drum brake 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a shoe hold down device for a drum brake, and more particularly to a technique for expanding the degree of freedom in designing a drum brake.

Generally, a shoe hold down device used for a drum brake is a shoe hold that urges a pair of brake shoes toward a backing plate so as to be able to expand on the backing plate, as shown in Patent Document 1, for example. A down spring is provided, and the pair of brake shoes are held relative to the backing plate so as to be movable relative to the backing plate using the urging force of the shoe hold down spring.
JP-A-9-14311

  By the way, the shoe hold down device as described above is disposed between the rotating drum disposed so as to cover one surface of the backing plate and the shoe web of the brake shoe. It must be designed so that the hold-down device and the rotating drum do not contact each other, that is, a space is provided between the shoe hold-down device and the rotating drum. Since the conventional shoe hold down spring is constituted by a wire wound in a cylindrical shape, the shoe hold down spring is wound in a cylindrical shape multiple times in the direction in which the brake shoe is urged against the backing plate. Since only compression is possible until the wire rods are in contact with each other, the height from the shoe web cannot be made sufficiently low, and the degree of freedom in designing the drum brake is not widened.

  The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a shoe hold-down device capable of reducing the height from the shoe web.

  In order to achieve this object, the gist of the invention according to claim 1 is that a shoe hold down spring that urges a pair of brake shoes toward the backing plate so as to be expandable on the backing plate. A shoe hold-down device that uses the shoe hold-down spring to hold the pair of brake shoes so that they can move relative to the backing plate in a plane direction. The wire is wound in a spiral shape so that the center lines of the wire do not overlap in the direction.

  The gist of the invention according to claim 2 is that, in the invention according to claim 1, the shoe hold down spring is constituted by one end portion of the wire, and from the winding center portion to the backing plate side. It is characterized by having integrally a latching portion that extends and latches on the backing plate or a member fixed to the backing plate.

  Further, the gist of the invention according to claim 3 is that, in the invention according to claim 1, one end portion that is hooked on the backing plate or a member fixed to the backing plate, and the side opposite to the backing plate. And a shoe hold down pin provided with the other end portion hooked on the winding center portion of the shoe hold down spring.

  Further, the gist of the invention according to claim 4 is that, in the invention according to any one of claims 1 to 3, the shoe hold down spring is characterized in that the wires do not overlap in the urging direction. There is to do.

  According to the shoe hold down device of the first aspect of the present invention, the shoe hold down spring has the wire wound in a spiral shape so that the center lines of the wire do not overlap in the biasing direction. The shoe hold down spring can reduce the height from the shoe web in the urging direction of the brake shoe, so that the space between the shoe hold down device and the rotating drum can be increased. The degree of freedom can be expanded.

  According to the shoe hold-down device of the invention according to claim 2, the shoe hold-down spring is constituted by one end portion of the wire, and extends from the winding center portion to the backing plate side so that the backing plate or Since it has integrally the latching | locking part latched on the member fixed to the backing plate, the number of parts of a shoe holddown apparatus can be reduced and the parts management in a production site can be made easy.

  According to the shoe hold-down device of the invention according to claim 3, the shoe hold located on one side of the backing plate or the member fixed to the backing plate and the opposite side of the backing plate. Since it has a shoe hold down pin provided with the other end part latched by the winding center part of a down spring, it is possible to apply the shoe hold down spring of this application to a conventionally used shoe hold down device. Therefore, the shoe hold down device of the present application can be manufactured at low cost.

  According to the shoe hold-down device of the invention according to claim 4, the shoe hold-down spring is configured such that the wire wound in the spiral shape does not overlap in the urging direction. Since the height from the shoe web can be suitably reduced in a compressed state in which the brake shoe is urged toward the backing plate, the space between the shoe holddown device and the rotating drum can be increased, and the design of the drum brake can be The degree of freedom can be expanded.

  FIG. 1 shows a leading / trailing type vehicle drum brake (hereinafter referred to as a drum brake) 10 which is a drum brake with a shoe clearance automatic adjustment mechanism having a parking lock function according to an embodiment of the present invention. It is a front view which removes and shows the drum (rotary drum) 12. FIG. The brake drum 12 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 drum brake 10 of the two circles indicates the inner peripheral surface 14 of the brake drum 12. Yes. The drum brake 10 has a substantially disc shape, and includes, for example, a backing plate 16 that is integrally fixed to a non-rotating member such as an axle tube, an axle housing, and a suspension device (not shown), and left and right sides of the backing plate 16. A pair of brake shoes 18, 20 disposed substantially symmetrically so as to be able to approach and separate from each other with an arcuate convex side outward on the outer periphery, and between one end of the pair of brake shoes 18, 20, that is, FIG. An anchor 22 provided between the lower end portions of the pair of brake shoes 18, a spring 24 that is stretched between the lower end portions of the pair of brake shoes 18, 20 so that the lower end portions are always in contact with the anchor 22, and a pair of brake shoes 18 and 20, that is, a wheel cylinder 26 disposed between the upper end portions in FIG. 1.

  Each of the brake shoes 18, 20 has a flat plate shape substantially parallel to the plate surface of the backing plate 16, and the shoe webs 28, 30 curved in an arc shape in the front view shown in FIG. Arc-shaped shoe rims 32 and 34 that are integrally fixed so as to form a substantially T-shaped cross section as shown in FIG. 2 along the outer peripheral side edge that forms the shape, and the outer peripheral surfaces of these shoe rims 32 and 34 And linings 36 and 38 each made of a friction material fixed integrally with an adhesive or the like.

  A return spring 40 is stretched between the upper ends of the brake shoes 18, 20, that is, between the ends on the wheel cylinder 26 side, and a longitudinal plate-like strut 42 is bridged. The brake shoes 18 and 20 are respectively formed with support protrusions 18a and 20a protruding along the strut 42 in order to support the strut 42.

  As shown in FIG. 2, the strut 42 has notches 44 and 46 at both ends, and the shoe web 28 of the brake shoe 18 is fitted into the notch 44 on the brake shoe 18 side. The shoe web 30 of the brake shoe 20 is fitted in the notch 46 on the side. In addition, a hooking protrusion 48 is provided at a middle portion in the longitudinal direction of the strut 42 so as to protrude away from the backing plate 16. The strut 42 is stretched between the hooking protrusion 48 and the brake shoe 18. The strut return spring 50 is constantly urged toward the brake shoe 18 side.

  The brake shoes 18 and 20 are pressed toward the backing plate 16 by shoe hold-down devices 52 and 54 disposed in the vicinity of the center in the longitudinal direction of the shoe webs 28 and 30, respectively. The shoe hold-down devices 52 and 54 have shoe hold-down springs 52a, which are configured by winding a circular wire made of a spring material into a spiral shape and a conical shape a plurality of times as shown in FIGS. 54a. The shoe hold down springs 52a and 54a are constituted by one end of the wire, and back through a through hole 56 formed through the shoe webs 28 and 30 from the winding center portion along the winding center line. Shaft portions 52b and 54b extending to the plate 16 side, and hooking portions 52c and 54c bent so that the tips of the shaft portions 52b and 54b are hooked on the hooking member 58 fixed on the backing plate 16. Have one. That is, the shoe hold down springs 52a and 54a, the shaft portions 52b and 54b, and the latching portions 52c and 54c are integrally bent by a single wire.

  When the shoe hold-down devices 52 and 54 are mounted by hooking the hook portions 52c and 54c of the shoe hold-down springs 52a and 54a on the hook member 58, the shoe webs 28 and 30 are compressed in the thickness direction. Therefore, the urging force generated in the direction of the backing plate 16 by the elastic restoring force generated by the compression is transmitted to the latching member 58, that is, the backing plate 16 through the shaft portions 52b and 54b and the latching portions 52c and 54c. Accordingly, the shoe webs 28 and 30 are always urged toward the backing plate 16 side. Therefore, the shoe hold-down devices 52 and 54 hold the brake shoes 18 and 20 so that they can be moved relative to the backing plate 16 in the plane direction, that is, can be expanded.

  FIG. 5 is an enlarged cross-sectional view taken along the line VV of FIG. 1, and the shoe hold down springs 52a and 54a are arranged so that the center lines of the wire rods are in the direction of the urging force, that is, the direction from the shoe webs 28 and 30 to the backing plate 16. It has a spiral shape that does not overlap, that is, the wires do not overlap. For this reason, the shoe hold-down springs 52a, 54a, that is, the shoe hold-down, are not brought into contact with each other when the shoe hold-down springs 52a, 54a are compressed in the winding center line direction in order to generate the urging force. The height H in the direction opposite to the backing plate 16 from the shoe webs 28, 30 of the devices 52, 54, that is, the direction from the shoe webs 28, 30 to the brake drum 12 can be suitably reduced. Further, since the shoe hold down springs 52a and 54a are not in contact with each other in the compressed state, the compression rate of the shoe hold down springs 52a and 54a (the height of the shoe hold down springs 52a and 54a before compression / Since the height of the shoe hold down springs 52a and 54a after compression) × 100 (%) can be increased, a high urging force can be generated.

  A base end portion of a flat parking brake lever 60 is rotatably connected to the upper end portion of the brake shoe 18 by a pin 62. An intermediate portion of the parking brake lever 60 and close to the pin 62 is fitted into the notch 44 of the strut 42 together with the shoe web 28. The tip of the parking brake lever 60 is connected to a well-known parking brake cable (not shown), and the tip of the parking brake lever 60 is centered on the backing plate 16 via the parking brake cable by operating a parking lever (not shown). When the brake shoe 20 is turned to the side, the brake shoe 20 is pushed by the strut 42 and moved to the outer circumferential side, and the brake shoe 18 is pushed by the pin 62 and moved to the outer circumferential side, so that the pair of brake shoes 18 and 20 Is expanded so that a braking force is generated.

  A flat plate-like adjusting lever 64 is disposed at the upper end of the brake shoe 20 so as to be rotatable about the axis of a pin 66 that is substantially perpendicular to the plate surface of the shoe web 30. This adjustment lever 64 is provided with engagement teeth 64a on an arcuate outer peripheral edge located on the opposite side to the rotational axis, and an opening of the notch 46 of the strut 42 is provided on the outer peripheral edge. An engaging protrusion 68 that protrudes inwardly from the portion is engaged. As a result, the adjustment lever 64 is rotated as the strut 42 moves away from the brake shoe 20. An adjustment latch 70 having a latching tooth 70a meshing with the engagement tooth 64a at a predetermined position on the outer peripheral edge is rotatably provided by a pin 72 at an intermediate portion in the longitudinal direction of the brake shoe 20 and is engaged. A spring spring-like latch spring 74 is provided to bias the adjustment latch 70 so that the teeth 64a and the latching teeth 70a are always meshed with each other. As a result, the adjustment lever 64 is prevented from moving away from the strut 42, that is, the rotating direction toward the outer peripheral side of the backing plate 16, and is moved to the strut 42 by one or more strokes of the engagement teeth 64 a or the latching teeth 70 a. When it is rotated in the approaching direction, that is, toward the inner peripheral side of the backing plate 16, the engaging tooth 64a gets over one tooth of the latching tooth 70a, and the rotation for one tooth is allowed. . That is, the engaging teeth 64a and the latching teeth 70a are each formed in a sawtooth shape, for example.

  When the upper ends of the brake shoes 18 and 20 are expanded in a direction away from each other by the piston of the wheel cylinder 26 being pushed out by the operation of a brake pedal (not shown), the strut 42 together with the brake shoes 18 Since it moves to the outer peripheral side, the adjustment lever 64 that engages with the engaging projection 68 is rotated around the brake shoe 18 side. When the amount of rotation of the engaging teeth 64a of the adjusting lever 64, that is, the amount of movement is within one tooth, the rotation position of the adjusting lever 64 does not change every time the brake is operated. The adjustment lever 64 is rotated about the side of the brake shoe 18 by one tooth after getting over the stop teeth 70a. As a result, when the expansion amount exceeds a predetermined value due to wear of the brake shoes 18 and 20, the adjustment lever 64 is rotated around the brake shoe 18 side by one tooth, and the expansion amount, that is, the brake shoes 18 and 20 is increased. And a gap, that is, a gap between the inner peripheral surface 14 of the brake drum 12 (not shown) is automatically adjusted.

  Here, according to the shoe hold-down devices 52 and 54 of the present embodiment, the shoe hold-down springs 52a and 54a are wound in a spiral shape so that the center lines of the wire do not overlap in the urging direction. Therefore, the shoe hold-down springs 52a and 54a reduce the height H from the shoe webs 28 and 30 in the biasing direction when the brake shoes 18 and 20 are biased toward the backing plate 16 side. Therefore, the space between the shoe hold-down devices 52 and 54 and the rotary drum 12 can be increased, and the degree of freedom in designing the drum brake 10 can be expanded.

  In the shoe hold-down devices 52 and 54 of the present embodiment, the shoe hold-down springs 52a and 54a are constituted by one end of the wire, and extend from the winding center to the backing plate 16 side so as to have the backing plate 16 Or since it has integrally the latching | locking parts 52c and 54c latched on the latching member 58 fixed to the backing plate 16, the number of parts of the shoe holddown apparatus 52 and 54 can be reduced, and parts management in a production site can be performed easily. can do.

  Further, in the shoe hold down devices 52, 54 of the present embodiment, the shoe hold down springs 52a, 54a do not overlap with each other in the urging direction because the spirally wound wire rods do not overlap each other. Since the height H from the shoe webs 28, 30 can be suitably reduced in a compressed state in which the brake shoes 18, 20 are biased toward the backing plate 16, the shoe hold-down devices 52, 54 and the rotary drum 12 can be reduced. And the degree of freedom in designing the drum brake 10 can be expanded.

  Next, another embodiment of the present invention will be described. In the following embodiments, portions common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

  6 corresponds to the VV cross-sectional view of FIG. 1, that is, FIG. 5 when a shoe hold-down device 80 different from the above-described embodiment is used.

  The shoe hold-down device 80 is disposed near the longitudinal center of the shoe web 28, and a shoe hold-down spring 82 in which a cylindrical wire is wound a plurality of times in the same spiral shape as in the above embodiment, One end portion 86a hooked to a hooking member 84 fixed to the backing plate 16 and the winding center portion of the shoe hold down spring 82 located on the opposite side of the backing plate 16 from the one end portion 86a through the through hole 56. And a shoe hold down pin 86 having the other end 86b to be hooked. One end 86a and the other end 86b of the shoe hold down pin 86 are formed by, for example, heading a cylindrical rod-shaped member. The latch member 84 includes a latch hole 84a that penetrates in substantially the same shape as the one end portion 86a. The one end portion 86a passes through the latch hole 84a, and the shoe hold down pin 86 is pivoted in this state. When it is rotated around the center by a predetermined angle, for example, 90 degrees, the one end portion 86a cannot be taken out from the hooking member 84, that is, the one end portion 86a is hooked on the hooking member 84. The shoe hold down device 80 transmits the urging force generated by the shoe hold down spring 82 being compressed from the shoe web 28 toward the backing plate 16 to the latch member 84, that is, the backing plate 16 through the shoe hold down pin 86. Accordingly, the shoe web 28 is constantly urged toward the backing plate 16 side. Therefore, the shoe hold-down device 80 holds the shoe web 28, that is, the brake shoe 28 so as to be movable relative to the backing plate 16 in the surface direction.

  The shoe hold down spring 82 has a spiral shape in which the center lines of the wire do not overlap with each other in the direction of the urging force, that is, the direction from the shoe web 28 to the backing plate 16 as shown in FIG. It has become. Therefore, the wire rods do not come into contact with each other when the shoe hold down spring 82 is compressed in order to generate the urging force, so that the shoe hold down spring 82, that is, the shoe web 28 of the shoe hold down device 80 is opposed to the backing plate 16. The height H in the direction, that is, the direction from the shoe web 28 to the brake drum 12 can be suitably reduced. Further, since the shoe hold down spring 82 is not in contact with each other in the compressed state, the compression rate of the shoe hold down spring 82 (height before compression of the shoe hold down spring 82 / compression of the shoe hold down spring 82) Since the subsequent height) × 100 (%) can be increased, a high urging force can be generated.

  Here, the shoe hold-down device 80 of the present embodiment includes a backing plate 16 or one end portion 86 a that is hooked on the latch member 84 that is fixed to the backing plate 16, and a shoe hold that is located on the opposite side of the backing plate 16. Since the shoe hold down pin 86 having the other end 86b hooked to the winding center portion of the down spring 82 is included, the shoe hold down spring 82 of the present application is used in a shoe hold down device conventionally used. Therefore, the shoe hold down device 80 of the present application can be manufactured at low cost.

  FIG. 7 corresponds to the VV cross-sectional view of FIG. 1, that is, FIG. 5 when a shoe hold-down device 88 different from the above-described embodiment is used.

  The shoe hold-down device 88 of FIG. 7 is disposed near the center of the shoe web 28 in the longitudinal direction, similar to the shoe hold-down device 52 shown in FIGS. A shoe hold down spring 88a configured by being wound a plurality of times in a conical shape. That is, the shoe hold down spring 88a integrally includes a shaft portion 88b similar to the shaft portion 52b and the latching portion 52c and the latching portion 88c, and the shoe hold down spring 88a, the shaft portion 88b, and the latching portion 88c. Is integrally bent by a single wire, except that the length of the shaft portion 88b in the thickness direction of the shoe web 28 is shorter than the length of the shaft portion 52b.

  The shoe hold-down spring 88a of the present embodiment has the same effect as that of the above-described embodiment, and the length of the shaft portion 88b is shorter than the length of the shaft portion 52b. The height H of the 88 shoe webs 28 in the direction of the brake drum 12 can be made lower than the height H of the shoe hold-down device 52 after compression. Therefore, the shoe hold-down device 88 can further increase the space with the brake drum 12, and can further increase the degree of freedom in designing the drum brake.

  As mentioned above, although the 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 a leading / trailing drum brake, but various modes are possible as long as the drum brake uses a shoe hold-down device such as a two-leading type or a duo servo type. It is. Therefore, instead of the wheel cylinder 26, a drum brake of a type provided with another operating device such as a cam lever may be used, or a drum of a type not provided with the parking brake lever 60 or the adjusting lever 64 described above. It may be a brake.

  In the above-described embodiment, the latching portions 52c and 54c are latched on the latching member 58, but there is no problem even if it is latched directly on the backing plate 16. In the other embodiments described above, the one end portion 86a is hooked on the hooking member 84. However, the hooking member 16 may be hooked directly on the one end 86a.

  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 front view showing a leading trailing drum brake to which the present invention is applied. It is a figure which shows the strut of the drum brake of the Example of FIG. 1 from the wheel cylinder side. FIG. 3 is a sectional view taken along line III-III in FIG. 1. It is a perspective view of the shoe hold down apparatus of FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. 1. It is a figure which shows the shoe hold down apparatus of another Example, and respond | corresponds to the VV sectional view of FIG. It is a figure which shows the shoe hold down apparatus of another Example, and respond | corresponds to the VV sectional view of FIG.

Explanation of symbols

16: Backing plates 18, 20: Brake shoes 52, 54, 80, 88: Shoe hold down devices 52a, 54a, 82, 88a: Shoe hold down springs 52c, 54c, 88c: Latch portions 58, 84: Latch members (Element)
86: Shoe hold down pin 86a: One end 86b: The other end

Claims (4)

A pair of brake shoes having a shoe hold down spring that urges toward the backing plate so as to be able to be expanded on the backing plate, and the pair of brake shoes are mounted on the backing plate using the shoe hold down spring; In the shoe hold-down device that holds the plate so that it can be moved relative to the surface in the plane direction,
The shoe hold-down spring is a shoe hold-down device in which the wire is wound in a spiral shape so that the center lines of the wire do not overlap in the urging direction. The shoe hold down spring is constituted by one end portion of the wire rod, and extends integrally from the winding center portion to the backing plate side and latches on the backing plate or a member fixed to the backing plate. The shoe holddown device according to claim 1, wherein One end portion hooked to the backing plate or a member fixed to the backing plate, and the other end portion hooked to the winding center portion of the shoe hold down spring located on the opposite side of the backing plate. The shoe hold-down device according to claim 1, further comprising a shoe hold-down pin. The shoe hold-down device according to any one of claims 1 to 3, wherein the shoe hold-down springs do not overlap the wires in the urging direction.

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