JP2014163441A - Drum brake for vehicle and brake shoe engaging part structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum brake for a vehicle and a brake shoe engaging part structure which are capable of reducing the number of components and the assembly man-hour, and capable of temporarily retaining and positioning a web in assembly.SOLUTION: A bulge part 3e is formed in a portion of a backing plate 3 opposing to the other end 8b of a web 8. In a web opposing part 3f of the bulge part 3e, an engaging part 3g is swingably engaged with the other end 8b of the web 8 is formed.

Description

  The present invention relates to a brake shoe engaging portion structure for a vehicle drum brake in which a braking force is generated by pressing a brake shoe disposed on a backing plate against an inner peripheral surface of a brake drum.

  As this type of drum brake, for example, in Patent Document 1, one end side of a pair of left and right brake shoes is connected by a wheel cylinder, and the other end side is engaged with an anchor block. Has been disclosed that is fixed to a backing plate by two rivets in a state of being sandwiched between a pair of holding plates together with the other end of the web.

JP2011-85179A

  By the way, in the said patent document 1, since it is a structure which pinches | interposes and hold | maintains the other end part of a web with an anchor block, a pair of holding | maintenance board, and a rivet, since there are many number of parts and the assembly man-hour increases, it becomes high cost. At the same time, there is a problem that productivity is low.

  Further, the conventional structure has a problem that positioning and provisional holding at the time of assembling the web cannot be performed because the other end portion forming the curved surface of the web is brought into contact with the flat surface of the anchor block.

  The present invention has been made in view of the above-described conventional situation, and can reduce the number of parts and the number of assembling steps, and can be positioned and temporarily held when assembling a web. It is an issue to provide.

The present invention includes a brake drum that rotates together with a wheel, a backing plate fixed to a vehicle body member that supports the wheel, and an arcuate shape that is disposed on the backing plate and faces an inner peripheral surface of the brake drum. And a pair of brake shoes having a flat web integrally formed along the inner side surface of the rim, and each brake shoe is opened at one end of the web to expand the brake. A brake shoe engagement portion structure of a vehicle drum brake configured to generate a braking force by being pressed against an inner peripheral surface of the drum,
A bulging portion is formed in a portion of the bucking plate facing the other end portion of the web, and the other end portion of the web is swingably engaged with the web facing portion of the bulging portion. An engaging portion is formed.

  According to the brake shoe engaging portion structure according to the present invention, the bulging portion is formed at a portion of the backing plate facing the other end portion of the web, and the other end portion of the web is formed at the web facing portion of the bulging portion. Since the engaging portion to be engaged is formed, it is only necessary to form the bulging portion and the engaging portion on the backing plate, so that the web is held by a conventional anchor block, a pair of holding plates and rivets. The number of parts can be greatly reduced, and the number of assembly steps can be reduced accordingly. This can reduce costs and improve productivity.

  Further, since the other end portion of the web is engaged with the engaging portion of the bulging portion, the other end portion of the web can be temporarily held in a state where the other end portion is positioned on the engaging portion of the backing plate. Assembling property can be improved.

  In the present invention, since the web is swingably engaged with the engaging portion, the web is allowed to play moderately in the direction connecting one end and the other end thereof, and the brake shoe is braked during braking. Can be brought into sliding contact with the brake drum uniformly, and a stable braking force can be obtained.

1 is an axial front view of a vehicle drum brake according to a first embodiment of the present invention. It is sectional drawing (II-II sectional view taken on the line of FIG. 1) of the brake shoe engagement part of the drum brake. It is a principal part front view of the said brake shoe engagement part. It is a figure which shows the modification of the brake shoe engaging part of the said Example. It is a figure of the brake shoe engaging part by Example 2 of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 3 are views for explaining a brake shoe engaging portion structure of a vehicle drum brake according to a first embodiment of the present invention.

  In the figure, reference numeral 1 denotes a leading trailing drum brake disposed on, for example, a rear wheel (not shown) of an automobile.

  The drum brake 1 is fixed to a brake drum 2 fixed to rotate together with the rear wheel, and an unillustrated axle housing (vehicle body member) that supports the rear wheel, and the brake drum 2 is coaxially arranged. A backing plate 3 and a pair of left and right brake shoes 4, 4 disposed in the backing plate 3 so as to be able to expand and contract are provided.

  The backing plate 3 is of a generally bowl shape having an outer peripheral wall portion 3a formed so as to surround the outer peripheral portion of the brake drum 2 and a bottom wall portion 3c formed with an axle shaft insertion hole 3b in the center portion. The bolt is fastened to the axle housing by a plurality of bolt mounting holes 3d formed in the outer peripheral portion of the axle shaft insertion hole 3b of the bottom wall portion 3c.

  The left and right brake shoes 4 have the same structure and are formed symmetrically, and have an arc-shaped rim 7 that is curved so as to face the inner peripheral surface 2a of the brake drum 2, and the rim 7 A flat web 8 integrally formed along the inner side of the rim 7 and a lining 9 attached and fixed to the outer side of the rim 7.

  A wheel cylinder 12 is disposed and fixed between upper end portions (one end portions) 8 a of the web 8 of the left and right brake shoes 4. In the wheel cylinder 12, a pair of pistons (not shown) with which the left and right upper end portions 8a abut is housed, and each wheel cylinder 12 is supplied with hydraulic pressure generated by a brake operation. The piston urges the upper end 8a outward. As a result, the left and right brake shoes 4 are expanded to press the lining 9 against the inner peripheral surface 2a of the brake drum 2, thereby generating a braking force for braking the rear wheels.

  An upper spring member 13 that constantly urges the left and right brake shoes 4 in the contracting direction is installed between the upper portions of the left and right brake shoes 4. Further, a lower spring member 14 that constantly urges the left and right brake shoes 4 in the engaging direction is mounted between the lower portions.

  A shoe clearance adjustment member 15 is installed between the upper portions of the left and right brake shoes 4 to automatically adjust the clearance s between the brake shoe 4 and the inner peripheral surface 2a of the brake drum 2. That is, the shoe clearance adjustment member 15 is configured to automatically correct the increase in the clearance s between the brake drum 2 and the lining 9 that is caused by wear of the lining 9 due to a long-time brake operation.

  A convex bulging portion 3e is formed at a portion of the backing plate 3 that faces the lower end portion (other end portion) 8b of the web 8.

  The bulging portion 3e is formed by drawing at the time of forming the backing plate 3, and is formed to face the lower end portions 8b of the left and right webs 8.

  The left and right facing portions 3f and 3f of the bulging portion 3e that are opposed to the lower end portion 8b are formed with engaging holes (engaging portions) 3g and 3g that are engaged with the lower end portion 8b of the web 8. Has been.

  A stepped insertion portion 8c is formed at the lower end portion 8b of the left and right webs 8, and the insertion portion 8c is inserted into the engagement hole 3g.

  R-shaped shoulder portions 8e and 8e 'are formed at the boundary between the lower end portion 8b and the insertion portion 8c of the left and right webs 8, and the shoulder portions 8e and 8e' are formed in the engagement portions. It is in contact with the opening edge 3g 'of the joint hole 3g so as to be able to roll and slide. As a result, the web 8 can swing left and right around the direction 8e and can slide up and down.

  According to the present embodiment, the bulging portion 3e is formed in the portion corresponding to the lower end portion 8b of the left and right webs 8 of the bucking plate 3 so as to face the lower end portion 8b. Since the engagement holes 3g with which the insertion portions 8c of the web 8 are engaged are formed in the left and right facing portions 3f, the web 8 is shaken only by forming the bulging portions 3e and the engagement holes 3g in the backing plate 3. Since it can be supported movably and slidably, the number of parts can be greatly reduced as compared with the case where the web is held by a conventional anchor block, a pair of holding plates and rivets, and the number of assembling steps can be reduced accordingly. This can reduce costs and improve productivity.

  In this embodiment, the insertion portions 8c of the left and right webs 8 are inserted into the engagement holes 3g of the bulging portion 3e, and the R-shaped shoulder portion 8e is brought into contact with the opening edge 3g 'of the engagement hole 3g. Since it is a structure, the web 8 can be temporarily held in a positioned state, and the assembling property of the brake shoe 4 can be improved.

  Further, the insertion portions 8c of the left and right webs 8 are inserted into the engagement holes 3g, and the shoulder portions 8e are slidably contacted with the opening edge portions 3g 'so that a slight amount is provided between the insertion portions 8c and the engagement holes 3g. Since the gap a is provided, moderate play is allowed in the direction connecting the upper end 8a and the lower end 8b of the web 8, and the brake shoe 4 is brought into sliding contact with the brake drum 2 evenly during braking. And a stable braking force can be obtained.

  Further, since the vertical behavior of each brake shoe 4 is not hindered, the brake shoe 4 is brought into sliding contact with the inner peripheral surface 2a of the brake drum 2 evenly, so that uneven wear of the lining 9 can be prevented.

  In the above embodiment, the shoulder 8e of the web 8 has an R shape. However, in the present invention, as shown in FIGS. 4A and 4B, the shoulders 8e and 8e 'are tapered. It may be formed. Even in this case, the brake shoe 4 can be slidably contacted with the brake drum 2 during braking, and a stable braking force can be obtained.

  FIGS. 5A and 5B are views for explaining a brake shoe engagement portion structure according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIGS. 2 and 3 denote the same or corresponding parts.

  In this embodiment, a groove-shaped engagement recess (engagement portion) 3h is formed in the facing portion 3f of the bulging portion 3e of the backing plate 3, and the lower end portion 8b of the web 8 is engaged with the engagement recess 3h. This is the case.

  The lower end portion 8b of the web 8 is formed with a pointed portion 8d that becomes thinner toward the tip, and the tip curved surface 8d 'of the pointed portion 8d can swing left and right on the bottom wall surface 3h' of the engaging recess 3h. Abuts slidably up and down.

  Also in the present embodiment, the same effect as in the first embodiment can be obtained, in which the brake shoe 4 can be uniformly slidably contacted with the brake drum 2 during braking, and uneven wear of the lining 9 can be prevented.

DESCRIPTION OF SYMBOLS 1 Drum brake 2 Brake drum 3 Backing plate 3e Expansion part 3f Opposing part 3g Engagement hole (engagement part)
3h Engaging recess (engaging part)
4 Brake shoe 7 Rim 8 Web 8a Upper end (one end)
8b Lower end (other end)
9 Lining 12 Wheel cylinder

Claims (1)

A brake drum that rotates with the wheels,
A backing plate fixed to a vehicle body member that supports the wheel;
A pair of brakes having a rim disposed in the backing plate and formed in an arc shape so as to face the inner peripheral surface of the brake drum, and a flat web integrally formed along the inner surface of the rim With shoes,
A brake shoe engagement portion structure of a vehicle drum brake, wherein each brake shoe generates a braking force by expanding one end of the web and pressing the brake shoe against an inner peripheral surface of the brake drum,
A bulging portion is formed in a portion of the bucking plate facing the other end of the web,
A brake shoe engaging portion of a drum brake for a vehicle, wherein an engaging portion is formed at the web facing portion of the bulging portion so that the other end portion of the web is swingably engaged. Construction.

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