JP2007120682A - Drum brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drum brake having a pair of mutually compatible brake shoes capable of being mounted at two positions on a backing plate even in the case that a sectional form of the brake shoe is not line-symmetric with a shoe web as a reference. <P>SOLUTION: As the drum brake has a form capable of being mounted at either of the two positions of the backing plate when taking a posture at which a side surface contacts with the backing plate, the drum brake is provided with the pair of mutually compatible brake shoes 16, 18 capable of being mounted at the two positions on the backing plate even in the case that the sectional form of each brake shoe 16, 18 is not line-symmetric for the shoe web 28 as a reference. Thus, parts of the pair of brake shoes 16, 18 are commonly used, the number of kinds of parts are decreased, the management of the parts becomes easy and the number of parts and cost are decreased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drum brake in which a pair of arc-shaped brake shoes is provided on a backing plate so as to be expandable.

  There is known a drum brake in which a pair of arc-shaped brake shoes is provided on a backing plate so as to be able to expand. In such a drum brake, for example, a backing plate, a pair of arc-shaped brake shoes provided on the backing plate, and a shoe hold-down device that presses the pair of brake shoes against the backing plate so as to be expanded. A brake actuator that presses the end portions of the pair of brake shoes against the inner peripheral surface of the rotating drum, and a shoe that is spanned between the pair of brake shoes and that is a gap between the outer peripheral surface of the brake shoe and the rotating drum A drum brake of the type having a gap adjusting device for adjusting the gap is known. For example, a leading trailing drum brake, a toe leading drum brake, and a duo servo brake are examples thereof, and the drum brake described in Patent Document 1 is one type.

By the way, in such a type of drum brake, one end is engaged or connected to a brake actuator and the other is engaged or connected to an anchor or a link at both ends of one brake shoe. Although it is formed in a shape, the pair of brake shoes has a symmetrical shape with respect to the center line of the backing braid between the pair of brake shoes. Therefore, parts management becomes easy and parts and costs are reduced.
JP-A-7-127678

  However, when a pair of brake shoes are bent from a single steel plate by plastic working such as press forming or roll forming, and the shoe web is integrally formed so as to be continuous from the side edge in the width direction of the shoe rim, Even if the shape is symmetrical with respect to the center line of the plate, the cross-sectional shape of the brake shoe does not become symmetrical with respect to the shoe web, and the backing plate side of the brake shoe does not have the same shape. Since it cannot be mounted at two positions on the plate, the compatibility between the pair of brake shoes is lost, so that there are inconveniences that the number of types of parts increases, and parts management and cost increase.

  The present invention has been made against the background of the above circumstances. The object of the present invention is to provide a 2 on the backing plate even when the cross-sectional shape of the brake shoe is not a line-symmetrical shape with respect to the shoe web. It is an object of the present invention to provide a drum brake having a pair of mutually compatible brake shoes that can be mounted at any position.

  In order to achieve such an object, the invention according to claim 1 is a drum brake provided with a pair of brake shoes provided in two positions on the backing plate so as to be expandable, wherein the pair of drum shoes is , And having a shape that can be attached to either one or the other of the two positions of the backing plate in a posture in which one side surface is in contact with the backing plate.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, both end portions of the brake shoe have the same shape.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the brake shoe includes a belt-like shoe rim bent in an arc shape and a shoe web fixed to the inner peripheral side of the shoe rim. The shoe rim has an asymmetric cross-sectional shape with respect to the center line in the width direction of the shoe rim.

  The invention according to claim 4 is characterized in that, in the invention according to claim 3, the shoe rim and the shoe web are formed integrally by being bent from a single steel plate.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein one of the pair of end portions of the pair of brake shoes in contact with each other on the backing plate. And the other set is connected to each other and mounted in a floating state with respect to the backing plate.

  According to the drum brake of the first aspect of the present invention, the pair of brake shoes respectively provided on the backing plate so as to be expandable are arranged in one of the two positions of the backing plate so that one side surface thereof is in contact with the backing plate. Since the brake shoe has a shape that can be attached to either one of the other, even if the cross-sectional shape of the brake shoe is not line-symmetrical with respect to the shoe web, it can be attached to any of the two positions on the backing plate. A drum brake having a pair of brake shoes having compatibility with each other. The pair of brake shoes provided in the drum brake can be interchanged with each other, thereby reducing the number of types of parts, facilitating parts management, and reducing parts and costs.

  Further, according to the drum brake of the invention according to claim 2, since both end portions of the brake shoe have the same shape as each other, they have a shape that can be mounted even in a posture in which both end portions are reversed. Therefore, even when the cross-sectional shape of the brake shoe is not line-symmetrical with respect to the shoe web, the drum having a pair of mutually compatible brake shoes that can be mounted at any two positions on the backing plate The brake is obtained.

  According to the drum brake of the invention of claim 3, the brake shoe includes a belt-like shoe rim bent in an arc shape and a shoe web fixed to the inner peripheral side of the shoe rim, and the width of the shoe rim Since it has an asymmetrical cross-sectional shape with respect to the center line of the direction, even if such a cross-sectional shape does not become a line-symmetrical shape with respect to the shoe web, it can be in any of two positions on the backing plate. A drum brake including a pair of mutually compatible brake shoes that can be mounted is obtained.

  According to the drum brake of the invention according to claim 4, since the shoe rim and the shoe web are formed integrally by being bent from one steel plate, the shoe rim and the shoe web are There is an advantage that a process such as welding for fixing each other becomes unnecessary, and the manufacturing process is simplified.

  Further, according to the drum brake of the invention according to claim 5, on the backing plate, one set of the pair of end portions of the pair of brake shoes that are close to each other is paired with the expansion device. The other set is connected to each other and attached to the backing plate in a floating state. That is, it is configured as a duo servo type drum brake.

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

  FIG. 1 shows a hat-type disc 13 and a caliper of a duo-servo type drum-in disc brake 12 having a parking brake drum brake (hereinafter referred to as a drum brake) 10 according to an embodiment of the present invention. It is a front view. The hat-type disc 13 includes a disc-shaped outer peripheral portion and a bottomed cylindrical central portion, the disc-shaped outer peripheral portion functions as a friction plate for a disc brake, and the bottomed cylindrical central portion functions as a brake drum. Is configured to do. A circle indicated by a two-dot chain line in FIG. 1 indicates the outer peripheral surface of the bottomed cylindrical central portion.

  The drum brake 10 has a substantially disk shape and includes a backing plate 14 that is integrally fixed to a vehicle body side member (non-rotating member) such as an axle tube, an axle housing, and a suspension device (not shown). . A disk cover 15 is secured to the outer periphery of the backing plate 14 to protect the disk-shaped outer periphery of the hat type disk.

  The drum brake 10 is configured in a substantially bilaterally symmetric manner, and is a pair of arc-shaped brakes disposed substantially symmetrically so as to be able to approach and separate from each other in a posture in which the convex side is outward on the left and right outer peripheral portions of the backing plate 14. The gap adjustment device 20 interposed between the shoes 16, 18 and one end portion of the pair of brake shoes 16, 18 or the lower end portion in FIG. An intermediate portion for pinching the adjusting device 20 is a coiled spring 22, a widening device 24 provided in a fixed position between the other ends of the pair of brake shoes 16 and 18, that is, the upper ends of FIG. An intermediate portion for constantly urging the upper end portions in a direction approaching each other and bringing them into contact with the expanding device 24 includes a coiled spring 26.

  The gap adjusting device 20 and the spring 22 are connected to each other so that the pair of brake shoes 16 and 18 are relatively close to each other between the lower end portions of one pair of the two pairs of paired end portions. Therefore, it functions as a connecting device provided with a gap adjusting device. One end portions of the pair of brake shoes 16 and 18 connected to each other are in a state of being freely movable with respect to the backing plate 14.

  Each of the brake shoes 16, 18 has a flat plate shape substantially parallel to the plate surface of the backing plate 14, and the shoe webs 28, 28 are curved in an arc shape in the front view shown in FIG. Arc-shaped shoe rims 30, 30 integrally formed along the outer peripheral side edge forming the shape, and a friction material integrally fixed to the outer peripheral surface of the shoe rims 30, 30 with a thermosetting resin adhesive or the like The linings 32 and 32 which consist of are comprised, respectively. These brake shoes 16 and 18 can be moved relative to the backing plate 14 in the surface direction by being pressed toward the backing plate 14 by shoe hold-down devices 34 and 34 disposed on the shoe webs 28 and 28, respectively. Is held in. The backing plate 14, the shoe webs 28 and 28, and the shoe rims 30 and 30 are stamped parts that are punched from a steel plate or subjected to predetermined bending.

  For example, as shown in FIG. 2, the expansion device 24 is a floating type that can move in the surface direction with respect to the backing plate 14, and is a lever 42 that is connected to one end portion so as to be relatively rotatable by a connection pin 40. And the struts 44, and the connecting pins 40 are arranged in a posture substantially parallel to the backing plate 14. The lever 42 is composed of two metal plates, and one end connected to the connecting pin 40 is integrally overlapped so as to be in close contact with each other, and the engaging recess to be engaged with the brake shoe 16. 46 is provided, and the other end portions are separated from each other by a predetermined dimension to be provided with a cable hooking portion 48, and a hooking member 52 fixed to the tip of the parking brake cable 50 is hooked. . The strut 44 is also composed of two metal plates. A lever 42 is disposed on the inner side of the strut 44, and the other end opposite to the connecting pin 40 is bent inward so as to be in close contact with each other. An engagement recess 58 that is overlapped and engaged with the brake shoe 18 is provided. The lever 42 is provided with a leaf spring 60 bent in a predetermined shape to guide the parking brake cable 50 to the cable hooking portion 48 of the lever 42 and to be hooked once inserted into the cable hooking portion 48. The stop member 52 is prevented from being detached.

  In addition, on one surface 14a of the backing plate on which the pair of brake shoes 16 and 18 are disposed, an anchor block 64 is integrated with the backing plate 14 and a vehicle body side member such as an axle housing or a suspension device by a plurality of bolts 62. The expansion device 24 is fixed and supported in contact with the heads 62h of the bolts 62. An insertion hole 68 for inserting the parking brake cable 50 into the anchor block 64 and the backing plate 14 is provided. 70 is provided. A guide pipe 72 that accommodates the parking brake cable 50 on the inner peripheral side is inserted into and inserted into the insertion holes 68 and 70.

  In the expansion device 24 configured as described above, when the operating force from the parking brake lever in the pulling direction is transmitted via the parking brake cable 50, the connecting pin 40 is brought closer to the backing plate 14 side. The distance between the engagement recesses 46 and 58, that is, the upper ends of the brake shoes 16 and 18 are expanded, and a braking force is generated. On the other hand, when the operating force is returned, the brake shoes 16 and 18 are reduced in diameter according to the urging force of the spring 26, and the braking force is released.

  Here, each of the brake shoes 16 and 18 has, for example, the shape shown in FIG. 3, and both end portions of the arc-shaped brake shoe have the same shape. Further, when the end portions of the same shape are positioned at the upper ends of the brake shoes 16 and 18, the expansion device 24 and the spring 26 are positioned at the lower ends of the brake shoes 16 and 18. The gap adjusting device 20 and the spring 22 both have a shape that can be attached. Of the brake shoes 16 and 18, the shoe web 28 has a line symmetry with respect to a center line C in a plane parallel to the backing plate 14, that is, a vertically symmetrical shape in FIG. 3. That is, in the brake shoes 16 and 18, the brake shoes 16 and 18 are positioned on the center line C of the mounting hole 74 of the shoe hold-down device 34 provided at the center in the longitudinal direction, and are in contact with the anchor block 64. The pair of engaging protrusions 76, a pair of notches 78 engageable with the gap adjusting device 20 and the expanding device 24, and a pair of retaining holes 80 with which the spring 22 and the spring 26 are latched are provided as a brake. At both ends of the shoes 16 and 18, the shoes 16 and 18 are provided at line symmetrical positions with respect to the center line C, respectively.

6 and 7 are a front view and a cross-sectional shape of a conventional shoe web 116, respectively, corresponding to the front view of FIG. 3 and the III-III cross-sectional view of FIG. A lining formed of a shoe web 128 and a shoe rim 130 integrally fixed along an outer peripheral side edge forming an arc shape thereof, and a friction material integrally fixed to the outer peripheral surface of the shoe rim 130 with an adhesive or the like. 132, and the cross section thereof is substantially T-shaped. Here, the lining 132 is drawn with a dotted line, and the shoe web 128 and the shoe rim 130 are drawn with a solid line. The shoe rim 130 and the shoe web 128 are fixed to each other by means such as resistance welding or fillet welding.

4 to 5 show an example of the brake shoes 16 and 18 according to the present embodiment. The shoe rim 30 and the shoe web 28 are integrally formed by bending a single steel plate by a roll press or the like. FIG. 3 is a sectional view taken along line III-III in FIG. 3 of brake shoes 16 and 18 obtained by molding. When the brake shoes 16 and 18 are bent from a single steel plate in this way, the cross section of the brake shoes 16 and 18 is the conventional brake shoe shown in FIG. 4 in which the shoe web 128 and the shoe rim 130 are fixed by welding or the like. Unlike the case of having a substantially T-shaped cross section such as 116, the cross section having a symmetrical shape is not obtained when the center line D in the width direction of the shoe rim 30 is used as a reference.

  That is, when the brake shoes 16 and 18 are bent from a single steel plate, the shoe web 28 and the shoe rim 30 are connected at either end of the shoe rim, as shown in FIGS. 4 to 5, this portion is the lower end of the shoe rim 30. However, when the portion is designed to contact the ridge surface of the backing plate 14, the end of the steel plate when bent from one steel plate is used. The end of the shoe rim 30 that is not connected to the shoe web 28, that is, the upper end of the shoe rim 30 in FIGS. 4 to 5 cannot be used in contact with the ridge surface of the backing plate 14. In other words, it is impossible to use the brake shoes 16, 18 in a so-called inverted state.

  Even in such a case, the brake shoes 16 and 18 of the present embodiment have the same shape at both ends, and the shape of the shoe web 28 is symmetrical in the vertical direction. The part where the expansion device 24 and the spring 26 are attached as the upper end of the brake shoe 16 even when the brake shoe 16 is moved to the position of the other brake shoe, that is, the brake shoes 18, 16 while keeping the direction in contact with the ridge surface. The gap adjusting device 20 and the spring 22 can be attached as the lower end of the brake shoe 18, and the portion where the gap adjusting device 20 and the spring 22 are attached as the lower end of the brake shoe 16 is used as the upper end of the brake shoe 18. A spreader 24 and a spring 26 can be attached. Further, since the shape of the shoe webs 28 of the brake shoes 16 and 18 is vertically symmetrical and the drum brake 10 is substantially symmetrical, the mounting holes 74 of the shoe hold-down devices 34 of the brake shoes 16 and 18 are provided. Even when the brake shoes 16 and 18 are moved to the positions of the brake shoes 18 and 16, respectively, the positions of the shoe shoes are substantially coincident with the position of the other shoe hold-down device 34, and the shoe hold-down device 34 is attached. be able to. Therefore, the brake shoes 16 and 18 can be mounted and used by moving to the positions of the brake shoes 18 and 16 respectively while keeping the direction in contact with the ridge surface.

  Therefore, the brake shoes 16 and 18 can be made into common parts. Incidentally, in the prior art, as shown in FIGS. 6 to 7, the brake shoe 116 was not configured to be vertically symmetrical, but its cross section has a line-symmetric shape such as a substantially T-shape as shown in FIG. In addition, since the drum brake has a substantially bilaterally symmetric shape, the left and right brake shoes 116 are used as common parts by using the brake shoes 116 in an inverted state. However, when the brake shoe 116 is processed by bending a single steel plate as described above, it has been impossible to make a common part from this viewpoint.

  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 a duo-servo type drum brake. However, the drum brake 10 is a type in which a load is transmitted between one end portions of a pair of brake shoes 16 and 18 via a gap adjusting device 20. If so, various modes are possible. Moreover, although the drum brake 10 of the above-mentioned Example was provided in the center part of the drum in disc brake 12, it may be used independently.

  Further, in the drum brake 10 of the above-described embodiment, the pair of brake shoes 16 and 18 are expanded by the expansion device 24, but may be expanded by a wheel cylinder.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

It is a front view which shows the case where the duo servo type drum brake to which this invention is applied is provided in the center part of the drum in disc brake. It is an enlarged view for demonstrating the structure of the expansion apparatus with which the drum brake of the Example of FIG. 1 was equipped. It is a front view of the brake shoe provided in the drum brake of the Example of FIG. FIG. 4 is a cross-sectional view of an essential part of FIG. 3 for explaining a brake shoe provided on the drum brake of the embodiment of FIG. FIG. 4 is a cross-sectional view taken along the line III-III of FIG. 3 for illustrating a brake shoe provided on the drum brake of the embodiment of FIG. It is a front view of the brake shoe with which the conventional drum brake was equipped. It is sectional drawing of the conventional brake shoe of FIG. 6, Comprising: It is a figure corresponded in III-III principal part sectional drawing of FIG.

Explanation of symbols

10: drum brake 14: backing plate 16, 18: brake shoe 24: expansion device 28: shoe web 30: shoe rim

Claims (5)

A drum brake in which a pair of arc-shaped brake shoes are provided at two positions on the backing plate so as to be able to expand,
The drum brake, wherein the brake shoe has a shape that can be attached to either one or the other of the two positions of the backing plate in a posture in which one side surface is in contact with the backing plate. The drum brake according to claim 1, wherein both ends of the brake shoe have the same shape. The brake shoe includes a belt-like shoe rim bent in an arc shape and a shoe web fixed to the inner peripheral side of the shoe rim, and has an asymmetric cross-sectional shape with respect to the center line in the width direction of the shoe rim. The drum brake according to claim 1 or 2, characterized by comprising: 4. The drum brake according to claim 3, wherein the shoe rim and the shoe web are integrally formed by bending from a single steel plate. On the backing plate, one pair of two pairs of end portions of the pair of brake shoes that are close to each other is engaged with the spreader, and the other pair is The drum brake according to any one of claims 1 to 4, wherein the drum brake is connected to each other and is in a floating state with respect to the backing plate.

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