JP2011085179A - Drum brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drum brake having a reduced number of parts, and a reduced manufacturing cost. <P>SOLUTION: The other end of shoe webs 32, 34 is held between a pair of holding plates 70, 72 of an anchor device 28, and the other end of the shoe webs 32, 34 is constantly pressed against a parallel guiding surface 72a of the holding plate 72 by the pressing part 70a of the holding plate 70, so that the other end of the shoe webs 32, 34, that is, the shoe webs 32, 34 are brought in surface contact with the parallel guiding surface 72a, and held in a parallel state relative to a backing plate 16, then brake shoes 18, 20 can be movably held in the direction parallel to the backing plate 16. Therefore, The brake shoes 18, 20 can be held so as to be expandable in the radial direction by the anchor device 28 without using a shoe hold down device. The number of parts of the drum brake 10 is reduced compared with a conventional drum brake using the shoe hold down device, so that manufacturing the drum brake 10 can be achieved at low cost. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a drum brake, and more particularly to a technique for reducing the manufacturing cost of the drum brake.

  For example, as shown in Patent Documents 1 and 2, the drum brake includes (a) a backing plate, (b) a belt-like shoe rim bent in an arc shape, and an intermediate portion in the width direction of the inner peripheral surface of the shoe rim. An arc-shaped brake shoe provided on the backing plate in a movable manner with a flat shoe web projecting a predetermined amount toward the inner peripheral side of the backing plate, and (c) the brake shoe An expansion mechanism that is disposed near the one end and moves one end of the brake shoe to the outer peripheral side of the backing plate; and (d) a direction in which the one end of the brake shoe approaches the expansion mechanism. A first spring that is biased and one end of the brake shoe is latched to the expansion mechanism by the biasing force; and (e) fixed at a position close to the other end of the brake shoe. Is an anchor device the other end of the brake shoe into contact thereof, is intended to include a (f) a second spring the other end of the brake shoe is biased in a direction approaching to the anchor apparatus.

  In general, a drum brake is a shoe hold down spring in which a wire made of a spring material is wound a plurality of times in a coil shape, as in a drum brake shown in Patent Document 2, for example, and an abbreviation placed on the shoe hold down spring. A disk-shaped cup member, a longitudinal latching hole provided penetrating through the center of the cup member, a circular mounting hole penetrating through a predetermined position of the backing plate, A through hole provided at a predetermined position in the middle portion of the shoe web, a large diameter base portion as one end portion is attached to the periphery of the attachment hole, and a flat head as the other end portion is the shoe hold down spring. Shoe hold down device comprising a substantially cylindrical shoe hold down pin that passes through the center hole of the cup member and through the retaining hole of the cup member Provided, is intended to movably hold the brake shoe by using an elastic restoring force of the pre-stressed the shoe-hold-down spring always presses the brake shoe to said backing plate.

Japanese Patent Laid-Open No. 11-280802 JP 09-229101 A

  However, in the drum brake as described above, the shoe hold down device is used to hold the brake shoe movably. However, the provision of such a shoe hold down device reduces the number of parts of the drum brake. There was a problem that drum brakes could not be manufactured at a low cost.

  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 having a small number of parts and a low manufacturing cost.

  To achieve this object, the gist of the invention according to claim 1 is that (a) a backing plate, (b) a belt-like shoe rim bent in an arc shape, and a width of an inner peripheral surface of the shoe rim. An arc-shaped brake shoe provided on the backing plate so as to be movable, and a flat shoe web projecting from the intermediate portion of the direction toward the inner peripheral side of the backing plate by a predetermined amount, and (c ) An expansion mechanism disposed near the one end of the brake shoe and moving the one end of the brake shoe to the outer peripheral side of the backing plate; and (d) one end of the brake shoe is the expansion mechanism. A first spring that is urged in a direction approaching to the brake shoe and one end of the brake shoe is latched to the expansion mechanism by the urging force; and (e) a first spring that is close to the other end of the brake shoe. (F) a second spring that is biased in a direction in which the other end of the brake shoe approaches the anchor device. (G) The anchor device is configured such that a part of the outer peripheral surface of the other end of the shoe web is brought into contact with the anchor device by the urging force of the second spring, and the other end of the brake shoe is An anchor block that is received and a pair of holding plates that are disposed so as to sandwich the anchor block and that hold the other end of the shoe web, respectively, are integrally provided, and (h) the pair One of the holding plates is provided with a parallel guide surface parallel to the backing plate, and (i) the other holding plate of the pair of holding plates has the other end of the shoe web. Part In the serial pressing portion that presses constantly against the parallel guide face is provided.

  A gist of the invention according to claim 2 is that, in the invention according to claim 1, (j) the brake shoes are a pair of brake shoes disposed on the backing plate so as to be expandable. (K) The anchor device is fixed between the other ends of the pair of brake shoes, and (l) the pair of holding plates is formed at both ends of the pair of brake shoes. The shoe web is held with the other end of the shoe web interposed therebetween.

  The gist of the invention according to claim 3 is that, in the invention according to claim 1 or 2, (m) the holding plate on the side opposite to the backing plate side in the pair of holding plates has the first The second spring is provided with a first extension portion extended to the second spring side so as to prevent movement in a direction away from the backing plate.

  A gist of the invention according to claim 4 is that, in the invention according to claim 3, (n) in the pair of holding plates, the holding plate on the backing plate side is provided between the first extension portion. And a second extension for holding the second spring.

  Further, the gist of the invention according to claim 5 is that, in the invention according to any one of claims 1 to 4, (o) the backing plate is formed on the shoe web side from the flat plate surface of the backing plate. (P) the anchor device is fixed on the height portion and holds the brake shoe, and (q) the thickness of the backing plate. The height distance between the flat plate surface and the high portion in the direction is set to have a gap between the flat plate surface of the backing plate and the brake shoe.

  According to the drum brake of the first aspect of the present invention, (g) the anchor device is brought into contact with a part of the outer peripheral surface of the other end portion of the shoe web by the urging force of the second spring. An anchor block for receiving the other end portion of the shoe and a pair of holding plates that are disposed so as to sandwich the anchor block and hold the other end portion of the shoe web are integrally provided. (H) One holding plate of the pair of holding plates is provided with a parallel guide surface parallel to the backing plate, and (i) the other holding plate of the pair of holding plates includes: A pressing portion that constantly presses the other end portion of the shoe web toward the parallel guide surface is provided. For this reason, the other end of the shoe web is sandwiched between the pair of holding plates of the anchor device, and the other end of the shoe web is moved by the pressing portion of the other holding plate of the pair of holding plates. When the parallel guide surface of one of the pair of holding plates is always pressed against the parallel guide surface, the other end of the shoe web, that is, the shoe web is in surface contact with the parallel guide surface and parallel to the backing plate. The brake shoe is held so as to be movable in a direction parallel to the backing plate. Accordingly, in the drum brake of the present invention, the brake shoe is movably held by the anchor device without using a shoe hold-down device, and the number of parts of the drum brake is larger than that of a conventional drum brake using the shoe hold-down device. And drum brakes are manufactured at a lower cost.

  According to the drum brake of the invention according to claim 2, (j) the brake shoe is a pair of brake shoes disposed on the backing plate so as to be expandable, and (k) the anchor device is It is fixed between the other ends of the pair of brake shoes, and (l) the pair of holding plates is sandwiched between the other ends of the shoe webs of the pair of brake shoes at both ends. Therefore, the pair of brake shoes used in the leading trailing type drum brake is held by the anchor device so as to be able to expand in a state preferably parallel to the backing plate.

  According to the drum brake of the invention according to claim 3, (m) in the pair of holding plates, the holding plate opposite to the backing plate side is moved in a direction in which the second spring is separated from the backing plate. Since the first extension portion extended toward the second spring side is provided so as to prevent the brake shoe from coming out of the anchor device, the second spring comes into contact with the first extension portion. Since the movement of the second spring is blocked, the other end of the brake shoe is prevented from coming off from the anchor device.

  According to the drum brake of the invention according to claim 4, (n) in the pair of holding plates, the holding plate on the backing plate side holds the second spring between the first extension portion. Since the extension portion is provided, when the shoe web is parallel to the backing plate, the intermediate portion of the shoe web is about to float from the backing plate or approaches the backing plate. The second spring is brought into contact with at least one of the first extension and the second extension and is elastically deformed, so that the parallel state of the shoe web is maintained by the elastic return force of the second spring.

  According to the drum brake of the invention according to claim 5, (o) the backing plate is provided with a height portion bent so as to protrude from the flat plate surface of the backing plate to the shoe web side, and (p The anchor device is fixed on the high part and holds the brake shoe, and (q) the height distance between the flat plate surface and the high part in the thickness direction of the backing plate is In addition, since the gap is set between the flat plate surface of the backing plate and the brake shoe, when the brake shoe is held by the anchor device, the brake shoe and the flat plate surface of the backing plate are The brake shoe and the backing plate used in a drum brake having a conventional shoe hold-down device because they do not contact There the manufacturing cost of the grease omitted and the drum brake that is applied to the contacts in contact becomes more expensive.

It is a front view showing a leading trailing drum brake to which the present invention is applied. It is sectional drawing explaining the structure of the wheel cylinder shown in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is the enlarged view to which the anchor apparatus shown in FIG. 1 was expanded. FIG. 5 is a VV sectional view of FIG. 4. It is a figure explaining the state by which the other end part of a shoe web is inserted between a pair of holding plates of an anchor device. It is the VII-VII sectional view taken on the line 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, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 shows a leading / trailing type vehicle drum brake (hereinafter referred to as a drum brake) 10 which is a drum brake with an automatic shoe clearance adjusting device having a parking lock function according to an embodiment of the present invention. It is a front view which removes and shows the drum 12. FIG. Further, 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 two circles indicates the inner peripheral surface 14 of the brake drum 12.

  The drum brake 10 has a substantially disc shape, and includes a backing plate 16 that is 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. .

  The drum brake 10 includes a pair of arc-shaped brake shoes 18 and 20 disposed substantially symmetrically so as to be able to approach and separate from each other in a posture in which the convex side is on the outer side of the backing plate 16, and the pair of brake shoes 18 and 20. A wheel cylinder (expansion mechanism) 22 provided at a fixed position on the backing plate 16 between one end of the brake shoes 18 and 20, that is, the upper end of FIG. 1, and one end of the pair of brake shoes 18 and 20 approach each other. A coiled return spring (first spring) 24 stretched between one end portions of the coiled return spring 24 and the inside of the coiled return spring 24 so that the wheel cylinder 22 is always urged in this direction. A pair of brake shoes 18 in a non-braking state spanned between one end portions of the pair of brake shoes 18 and 20 so as to be inserted. 1 and a brake drum 12, that is, a shoe gap automatic adjusting device 26 that automatically adjusts the shoe gap, and the other end of the pair of brake shoes 18, 20, that is, a lower end of FIG. The anchor device 28 and a spring (second spring) 30 that is stretched between the other end portions of the pair of brake shoes 18 and 20 so as to always contact the other end portion with the anchor device 28 are provided.

  Each of the pair of brake shoes 18, 20 has a flat plate shape substantially parallel to the flat plate surface 16a of the backing plate 16, and the shoe webs 32, 34 curved in an arc shape in the front view shown in FIG. Adhered to the belt-like shoe rims 36 and 38 integrally fixed so that the cross-section is substantially T-shaped along the outer peripheral side edge forming the arc shape, and to the outer peripheral surfaces of the shoe rims 36 and 38 And linings 40 and 42 made of a friction material fixed integrally with an agent or the like. A base end 44 a of a flat parking brake lever 44 is connected to one end of the brake shoe 18 by a pin 46 so as to be relatively rotatable. The backing plate 16, the shoe webs 32 and 34, and the shoe rims 36 and 38 are all pressed parts that are punched from a steel plate and subjected to predetermined bending.

  The front end 44b of the parking brake lever 44 is pulled so that the front end 44b of the parking brake lever 44 rotates in the direction of arrow F shown in FIG. A parking brake cable 48 is provided.

  As shown in FIG. 2, the wheel cylinder 22 is slidable in opposite directions into a cylinder body 50 fixed to the backing plate 16 and a cylinder bore 50 a provided so as to penetrate the cylinder body 50. A pair of substantially cylindrical pistons 52, 54 fitted into the outer periphery, seal members 56, 58 fitted in outer circumferential grooves 52a, 54a provided on the outer circumference of the pair of pistons 52, 54, and a pair of pistons The coil spring 60 is interposed between the pistons 52 and 54 and urges the pair of pistons 52 and 54 in a direction to separate them, and the pressure chamber 62 sealed by the pair of pistons 52 and 54 in the cylinder bore 50a. Yes. In addition, synthetic rubber cylinder covers 64 and 66 are installed between the opening of the cylinder bore 50a and the pistons 52 and 54 to prevent foreign substances from entering.

  As shown in FIGS. 2 and 3, a pair of side surfaces 52 b, 54 b facing one end of the shoe webs 32, 34 and a return are provided at the ends of the substantially cylindrical pistons 52, 54 on the shoe webs 32, 34 side. A longitudinal guide groove having a bottom surface 52c, 54c against which a part of the outer peripheral surface of one end portion of the shoe webs 32, 34 abuts by an urging force of the spring 24 and into which one end portion of the shoe webs 32, 34 is fitted. 52d and 54d are disposed, and when one end portion of the shoe webs 32 and 34 is fitted into the guide grooves 52d and 54d, the thickness direction of the shoe webs 32 and 34 at one end portion of the shoe webs 32 and 34 is determined. The movement in the width direction of the shoe webs 32 and 34 is restrained by the pair of side surfaces 52b and 54b of the guide grooves 52d and 54d and the cylinder covers 64 and 66. That. That is, when one end portion of the shoe webs 32, 34 is fitted into the guide grooves 52d, 54d by the urging force of the return spring 24, one end portion of the pair of brake shoes 18, 20 is hooked on the wheel cylinder 22 and the pair The brake shoes 18 and 20 are prevented from coming off from the wheel cylinder 22 at one end thereof.

  As shown in FIGS. 4 and 5, the anchor device 28 has the other end portion of the brake shoes 18, 20 in contact with a part of the outer peripheral surface at the other end portion of the shoe webs 32, 34 by the biasing force of the spring 30. And a pair of substantially rectangular holding plates 70 that are disposed so as to sandwich the anchor block 68 and hold the other ends of the shoe webs 32 and 34, respectively. 72 and the anchor block 68 and the pair of holding plates 70, 72 are integrally provided with a pair of substantially cylindrical rivets 74 penetrating in the thickness direction, and one end portions of the pair of rivets 74 are caulked. To the backing plate 16.

  As shown in FIGS. 4 and 5, in the anchor device 28, the width dimension A in the longitudinal direction of the pair of holding plates 70, 72 is larger than the width dimension B in the longitudinal direction of the anchor block 68. Both ends of the plates 70 and 72 are arranged so as to protrude from both ends of the anchor block 68 to the outer peripheral side of the backing plate 16, and between the pair of holding plates 70 and 72 at both ends of the pair of holding plates 70 and 72. The other ends of the shoe webs 32 and 34 are inserted.

  As shown in FIGS. 5 and 6, parallel guide surfaces 72 a substantially parallel to the flat plate surface 16 a of the backing plate 16 are provided at both ends of the holding plate 72 on the backing plate 16 side of the pair of holding plates 70 and 72. Each end of the pair of holding plates 70 and 72 opposite to the backing plate 16 side of the pair of holding plates 70 and 72 is arranged such that a part of the both ends approach the both ends of the holding plate 72. Each of the bent pressing portions 70a is provided.

  As shown in FIG. 6, since the dimension C between the pressing portion 70a and the parallel guide surface 72a is set to be smaller than the thickness D of the shoe webs 32, 34, the other end portions of the shoe webs 32, 34 are used. Is inserted between the pressing portion 70a and the parallel guide surface 72a, the other ends of the shoe webs 32 and 34 are brought into contact with the parallel guide surface 72a of the holding plate 72 by the elastic return force of the pressing portion 70a of the holding plate 70. The other end portions of the shoe webs 32 and 34 and the parallel guide surface 72a of the holding plate 72 are brought into surface contact with each other, and the shoe webs 32 and 34 are held in a substantially parallel state with respect to the flat plate surface 16a of the backing plate 16. Is done. 6 indicates a state in which the other end portion of the shoe web 32 is inserted between the pressing portion 70a and the parallel guide surface 72a and the pressing portion 70a is elastically deformed.

  That is, the holding plate 70 is made of a material having a relatively low elastic modulus, for example, spring steel, and the holding plate 72 is made of a material having a relatively high elastic modulus, for example, a rope material larger than the elastic modulus of the holding plate 70. Therefore, when the other end portions of the shoe webs 32 and 34 are inserted between the pressing portion 70a and the parallel guide surface 72a, the pressing portion 70a of the holding plate 70 having a relatively low elastic modulus as shown in FIG. 6 is preferable. However, since the parallel guide surface 72a of the holding plate 72 having a relatively large elastic modulus is hardly elastically deformed, the shoe webs 32 and 34 are pressed against the flat plate surface 16a of the backing plate 16 by the elastic portion 70a. By this, it is held in a substantially parallel state.

  Further, in the wheel cylinder 22, a pair of side surfaces 52 b and 54 b of the guide grooves 52 d and 54 d into which one end portions of the brake shoes 32 and 34 are fitted with respect to the flat plate surface 16 a of the backing plate 16, that is, the parallel guide surface 72 a of the holding plate 72. Therefore, when the other end portions of the shoe webs 32 and 34 are inserted between the pressing portion 70 a and the parallel guide surface 72 a, the shoe webs 32 and 34 are substantially the same as the flat plate surface 16 a of the backing plate 16. Hold in parallel.

  As shown in FIG. 6, the anchor device 28 receives the other end portions of the shoe webs 32 and 34 urged in the direction of arrow E by the urging force of the spring 30, that is, the direction approaching the anchor device 28, by the anchor block 68. A shoe web that is always urged in the direction of arrow G by the urging force of the pressing portion 70a of the holding plate 70, with a part of the outer peripheral surface at the other end of the shoe webs 32, 34 in contact with the anchor block 68. The other end portions of the shoe webs 32 and 34 are received by the parallel guide surface 72a of the holding plate 72 and the other end portions of the shoe webs 32 and 34 are always brought into contact with the parallel guide surface 72a, whereby the shoe webs 32 and 34, that is, the brakes. The shoes 18 and 20 can move on the backing plate 16 in a direction substantially parallel to the flat plate surface 16a of the backing plate 16. It is held in.

  As shown in FIG. 5, the backing plate 16 is integrally provided with a high portion 16 b that is bent in a substantially trapezoidal shape so as to protrude from the flat plate surface 16 a of the backing plate 16 toward the shoe webs 32 and 34. The anchor device 28 is fixed to the high portion 16b and holds the pair of brake shoes 18 and 20. Further, as shown in FIG. 5, the height of the high portion 16b of the backing plate 16, that is, the height distance H between the flat plate surface 16a and the high portion 16b in the thickness direction of the backing plate 16, is A holding plate 72 on the backing plate 16 side of the pair of holding plates 70, 72 in the thickness direction of the backing plate 16 when the other end portion is inserted between the pressing portion 70a of the anchor device 28 and the parallel guide surface 72a; It is set longer than the distance I between the arcuate side edges 36a, 38a on the backing plate 16 side of the shoe rims 36, 38. Therefore, when the pair of brake shoes 18, 20 are held on the anchor device 28, a gap J is formed between the arc-shaped side edges 36 a, 38 a on the backing plate 16 side of the shoe rims 36, 38 and the flat plate surface 16 a of the backing plate 16. The pair of brake shoes 18 and 20 are held by the anchor device 28 in a state of being separated from the flat plate surface 16 a of the backing plate 16.

  Further, as shown in FIG. 5, when the brake shoes 18 and 20 are held by the anchor device 28, the brake shoes 18 and 20 and the backing plate 16 do not come into contact with each other. 38 is not provided with a ledge portion bent so that a part of the arc-shaped side edges 36a, 38a on the backing plate 16 side protrudes to the inner peripheral side of the backing plate 16, and the backing plate 16 has its backing The curved part bent so that a part of flat plate surface 16a of the plate 16 may protrude to the ledge part side is not provided. In a conventional drum brake using a shoe hold-down device, the ledge portion of the shoe rims 36a, 38a and the curved portion of the backing plate 16 are brought into contact with each other by the shoe hold-down device, and the pair of brake shoes 18, 20 are expanded. It was held open.

  As shown in FIGS. 4 and 7, the intermediate portion of the holding plate 70 is extended from the intermediate portion toward the spring 30 so as to prevent the spring 30 from moving away from the backing plate 16, that is, in the direction of the arrow K. The first extension portion 70b is provided, and the intermediate portion of the holding plate 72 is provided between the spring 30 and the parking brake cable 48 from the intermediate portion so that the spring 30 is held between the first extension portion 70b. A second extension 72b is provided.

  In the drum brake 10 configured as described above, when the front end 44b of the parking brake lever 44 is rotated in the direction of arrow F via the parking brake cable 48 by operating a parking lever (not shown), the brake shoe 20 Is pushed by the shoe clearance automatic adjusting device 26 and moved to the outer peripheral side, and the brake shoe 18 is pushed by the pin 46 and moved to the outer peripheral side, so that the pair of brake shoes 18 and 20 are expanded and braking force is applied. Can be generated. Further, when a brake pedal (not shown) is operated, the drum brake 10 increases the pressure of the hydraulic fluid in the pressure chamber 62 of the wheel cylinder 22 so that the pair of pistons 52 and 54 protrude from the cylinder body 50 to both sides. The one end part of a pair of brake shoes 18 and 20 is expanded, and a braking force is generated. When the operation of the brake pedal is released, the pair of pistons 52 and 54 are returned to their original positions by the urging force of the return spring 24, and the pair of brake shoes 18 and 20 are connected to the inner peripheral surface 14 of the brake drum 12. The braking force is released by being separated from.

  According to the drum brake 10 of the present embodiment, a part of the outer peripheral surface at the other end of the shoe webs 32, 34 is brought into contact with the anchor device 28 by the urging force of the spring 30, and the brake shoes 18, 20 and the like. An anchor block 68 that receives the end portion and a pair of holding plates 70 and 72 that are disposed so as to sandwich the anchor block 68 and hold the other end portions of the shoe webs 32 and 34 are integrally formed. One of the pair of holding plates 70, 72 is provided with a parallel guide surface 72a substantially parallel to the flat plate surface 16a of the backing plate 16, and the pair of holding plates 70, 72 The other holding plate 70 out of 72 is provided with a pressing portion 70a that constantly presses the other end portion of the shoe webs 32, 34 toward the parallel guide surface 72a. Therefore, the other end portions of the shoe webs 32 and 34 are sandwiched between the pair of holding plates 70 and 72 of the anchor device 28, and the shoe is pressed by the pressing portion 70 a of the other holding plate 70 of the pair of holding plates 70 and 72. When the other end portion of the webs 32 and 34 is constantly pressed against the parallel guide surface 70a of one holding plate 70 of the pair of holding plates 70 and 72, the other end portion of the shoe webs 32 and 34, that is, the shoe web 32. , 34 are in surface contact with the parallel guide surface 72a and are held in a state substantially parallel to the flat plate surface 16a of the backing plate 16, so that the brake shoes 18, 20 are held movably in a direction parallel to the backing plate 16. The Therefore, in the drum brake 10 of the present embodiment, the brake shoes 18 and 20 are held by the anchor device 28 so that they can be expanded without using the shoe hold-down device, and compared with the conventional drum brake using the shoe hold-down device. The number of parts of the drum brake 10 is reduced, and the drum brake 10 is manufactured at a lower cost.

  Further, according to the drum brake 10 of the present embodiment, the anchor device 28 is fixed between the other ends of the pair of brake shoes 18 and 20 disposed on the backing plate 16 so as to be able to expand. In this case, the pair of holding plates 70 and 72 hold the other end portions of the shoe webs 32 and 34 of the pair of brake shoes 18 and 20 at both ends thereof. The pair of brake shoes 18 and 20 used in the drum brake 10 are held by the anchor device 28 so as to be able to expand in a state substantially parallel to the flat plate surface 16a of the backing plate 16.

  Further, according to the drum brake 10 of the present embodiment, the spring 30 extends from the backing plate 16 to the middle portion in the longitudinal direction of the holding plate 70 opposite to the backing plate 16 side of the pair of holding plates 70 and 72. Since the first extension portion 70b protruding from the spring 30 so as to prevent the movement in the direction of separation, that is, the direction of the arrow K is integrally provided, the brake shoes 18, 20, that is, the shoe webs 32, 34 are anchored. If the spring 30 is detached from the device 28, the spring 30 stretched between the other ends of the shoe webs 32 and 34 comes into contact with the first extension 70b and the movement of the spring 30 in the arrow K direction is prevented. The shoe webs 32 and 34 are prevented from coming off the anchor device 28.

  Further, according to the drum brake 10 of the present embodiment, the spring 30 is interposed between the pair of holding plates 70 and 72 in the longitudinal direction of the holding plate 72 on the backing plate 16 side and the first extension portion 70b. So that the shoe webs 32, 34 are flat plates of the backing plate 16. The second extension 72 b is provided integrally between the spring 30 and the parking brake cable 48. The spring 30 will move in the direction of the arrow K or the arrow L as the intermediate part of the shoe webs 32, 34 tries to float up or approach the backing plate 16 from a state substantially parallel to the surface 16a. Then, the spring 30 stretched between the other end portions of the pair of brake shoes 18 and 20 is formed by the first extension portion 70b and the second extension portion. Since 2b of the contact in at least one and elastically deformed substantially parallel with respect to the flat plate surface 16a of the backing plate 16 of the shoe web 32, 34 i.e. the brake shoes 18 and 20 by the elastic restoring force of the spring 30 is held.

  Further, according to the drum brake 10 of the present embodiment, the second extension portion 72b of the holding plate 72 extends between the spring 30 and the parking brake cable 48, so that the parking brake cable 48 and the spring Thus, the parking brake cable 48 and the spring 30 are prevented from contacting each other.

  Further, according to the drum brake 10 of the present embodiment, the backing plate 16 is provided with the high portion 16b that is bent so as to protrude from the flat plate surface 16a of the backing plate 16a toward the shoe webs 32 and 34, The anchor device 28 is fixed on the high portion 16b and holds the brake shoes 18 and 20, and the height distance between the flat plate surface 16a and the high portion 16b in the thickness direction of the backing plate 16 is provided. H is set so as to have a gap J between the flat plate surface 16a of the backing plate 16 and the arc-shaped side edges 36a, 38a of the shoe rims 36, 38 on the backing plate 16 side. When 18 and 20 are held, the shoe rims 36 and 38 and the flat plate surface 16a of the backing plate 16 are in contact with each other. Therefore, as compared with the conventional shoe hold-down device, it is necessary to eliminate the grease applied to the contact point at which the brake shoes 18 and 20 and the backing plate 16 are in contact with each other, and to provide a ledge portion and a curved portion to be brought into sliding contact with the ledge portion. Therefore, the shapes of the backing plate 16 and the shoe rims 36 and 38 are simplified, and the manufacturing cost of the drum brake 10 is further reduced.

  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 present embodiment is a leading trailing drum brake 10 in which the anchor device 28 is fixed between the other ends of the pair of brake shoes, but one of the pair of brake shoes is used. Even if the anchor device is disposed at the other end of the brake shoe and the anchor device is disposed at one end of the other brake shoe of the pair of brake shoes, the present invention may be applied to a two-leading type drum brake. good.

  Further, in the anchor device 28 according to the present embodiment, the holding plate 70 on the opposite side of the backing plate 16 side of the pair of holding plates 70 and 72 is provided with a pressing portion 70 a and the pair of holding plates 70 and 72. Although the parallel guide surface 72a is provided on the holding plate 72 on the backing plate 16 side, the anchor device 28 of the present invention guides parallel to the holding plate 70 on the opposite side of the backing plate 16 side of the pair of holding plates 70 and 72. The pressing portion 70a may be provided on the holding plate 72 on the backing plate 16 side of the pair of holding plates 70, 72 provided with the surface 72a.

  Further, in the drum brake 10 of the present embodiment, the wheel cylinder 22 is used as the expansion mechanism, but any type may be used as long as the brake shoes 18 and 20 are expanded.

  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: drum brake 16: backing plate 18, 20: pair of brake shoes 22: wheel cylinder (expansion mechanism)
24: Return spring (first spring)
28: Anchor device 30: Spring (second spring)
32, 34: Shoe web 36, 38: Shoe rim 68: Anchor block 70, 72: A pair of holding plates 70a: Press part 70b: First extension part 72a: Parallel guide surface 72b: Second extension part

Claims (5)

A backing plate, a belt-like shoe rim bent in an arc shape, and a flat shoe web projecting a predetermined amount from an intermediate portion in the width direction of the inner peripheral surface of the shoe rim toward the inner peripheral side of the backing plate And an arcuate brake shoe movably disposed on the backing plate, and one end of the brake shoe disposed on the outer peripheral side of the backing plate. An expanding mechanism to be moved, and a first spring in which one end portion of the brake shoe is urged in a direction approaching the expanding mechanism and the one end portion of the brake shoe is latched to the expanding mechanism by the urging force An anchor device fixed at a position close to the other end of the brake shoe and in contact with the other end of the brake shoe, and the other end of the brake shoe A drum brake including a second spring which is biased in a direction approaching the over device,
The anchor device includes an anchor block in which a part of an outer peripheral surface of the other end portion of the shoe web is brought into contact with the urging force of the second spring and the other end portion of the brake shoe is received, and the anchor block includes A pair of holding plates that are arranged so as to be sandwiched and hold the other end portions of the shoe webs in a state of being sandwiched respectively are integrally provided,
One holding plate of the pair of holding plates is provided with a parallel guide surface parallel to the backing plate,
The drum brake, wherein the other holding plate of the pair of holding plates is provided with a pressing portion that constantly presses the other end portion of the shoe web toward the parallel guide surface. The brake shoes are a pair of brake shoes disposed on the backing plate so as to be expandable,
The anchor device is disposed between the other ends of the pair of brake shoes,
The drum brake according to claim 1, wherein the pair of holding plates hold the other end portions of the shoe webs of the pair of brake shoes at both ends thereof.   The holding plate opposite to the backing plate side of the pair of holding plates has a first extension extended to the second spring side so as to prevent the second spring from moving in a direction away from the backing plate. 3. The drum brake according to claim 1, further comprising an extension portion.   The holding plate on the backing plate side of the pair of holding plates is provided with a second extension for holding the second spring between the first extension and the holding plate. Drum brake. The backing plate is provided with a high portion bent so as to protrude from the flat plate surface of the backing plate to the shoe web side,
The anchor device is fixed on the height portion and holds the brake shoe,
A height distance between the flat plate surface and the height portion in the thickness direction of the backing plate is set so as to have a gap between the flat plate surface of the backing plate and the brake shoe. The drum brake according to any one of claims 1 to 4.

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