JPH0637635U - Drum brake gap adjustment stop device - Google Patents

Abstract

(57) [Abstract] [Purpose] To easily attach and detach the temperature sensitive member and to control the blind movement of the temperature sensitive member. [Structure] Mounting holes 25 and 85 are formed in the shoe web 22 of one of the brake shoes 20 and a base end portion 81 of the temperature sensitive member 80, respectively, and a clip 90 is inserted into both of the mounting holes 25 and 85 to adjust the temperature. The base end portion 81 of the sensitive member 80 is elastically attached to the shoe web 22.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drum brake including a shoe clearance automatic adjusting device, and more particularly to a drum brake clearance adjusting stopping device that stops shoe clearance adjustment when the brake temperature rises.

[0002]

[Prior art]

 A device of this type is disclosed in Japanese Patent Publication No. 2-11768. Generally, a drum brake is equipped with an automatic shoe clearance adjusting device. In the automatic shoe clearance adjustment device, a protrusion at one end of a bell crank lever pivotally supported on a strut engages a hole formed in one shoe web with play in the operating direction of the brake shoe, When the expansion amount of the brake shoes exceeds the above play due to wear of the brake shoes, the bell crank lever rotates to expand the diameter of the pair of brake shoes and automatically reduce the gap amount. . The automatic shoe clearance adjuster functions in the same way when the brake drum thermally expands due to frictional heat in addition to when the brake shoe wears, so the clearance amount between the brake shoe and the brake shoe decreases when the brake drum cools and contracts. There is a disadvantage that it becomes extremely small. In order to eliminate this inconvenience, a gap adjustment stop device was proposed, in which the base end of a plate-shaped temperature-sensitive member that starts to deform at a constant temperature is fixed to the shoe web with a rivet, and the free end of the temperature-sensitive member is fixed. The detection part formed by bending it into a shape engages with the hole inserted in the bell crank lever, and the detection part of the temperature sensitive member slips out from the hole of the shoe web as the brake temperature rises. It is a device that transforms in a direction that substantially increases the play.

[0003]

[Problems to be solved by the present invention]

 The gap adjustment stop device described above has the following points to be improved.

<B> The temperature sensitive member must be previously attached to the individual brake shoe with rivets. Therefore, the temperature-sensitive member may be deformed due to handling or stacking during transportation of the brake shoe to which the temperature-sensitive member is attached.

<B> When the brake shoe is replaced due to wear of the lining or the like, the temperature-sensitive member must be replaced as a unit.

<C> To fix the temperature-sensitive member to the shoe web, rivet insertion holes are formed in both the shoe web and the temperature-sensitive member, and then rivets are inserted into these holes. Although the caulking is done by caulking, the caulking work of the rivet is complicated, and the caulking equipment for exclusive use is necessary.

<D> Since the shoe web and the temperature-sensitive member and the rivet are fitted by the round holes, the temperature-sensitive member freely rotates with respect to the shoe web, and the detection portion of the temperature-sensitive member comes out of the hole of the web. Or, you may get on the web and lose its original functionality.

[0008]

[Purpose of the present invention]

 The present invention has been made in view of the above points, and an object thereof is to provide a gap adjusting and stopping device for a drum brake, which can easily attach / detach the temperature sensitive member and can regulate the blind movement of the temperature sensitive member. To provide.

[0009]

[Means for solving problems]

 That is, in the present invention, a strut is disposed between a pair of opposed brake shoes, a bell crank lever is rotatably supported at one end of the strut, and one end projection of the crank lever is drilled in one shoe web. When the brake shoe engages with the provided hole with play, and the expansion amount of the brake shoe exceeds the above-mentioned play, the bell crank lever rotates to automatically adjust the gap between the brake shoes and The base end of the temperature sensitive member is attached to the shoe web, and the detection part formed by bending the free end of the temperature sensitive member is engaged with the hole formed in one of the shoe webs described above to increase the brake temperature. In the device for adjusting the gap adjustment of the drum brake, in which the detection portion of the temperature sensitive member is deformed in the direction in which the detection portion of the temperature sensitive member comes out of the hole of the shoe web and substantially increases the play, Stopping the gap adjustment of the drum brake, characterized in that mounting holes are formed in the base end portion of the degree sensitive member, and clips are inserted into both the mounting holes to elastically attach the base end portion of the temperature sensitive member. It is a device.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. <a> Drum brake FIGS. 1 and 2 show an example of a drum brake equipped with an automatic shoe clearance adjusting device and a clearance adjusting stopping device. Reference numeral 10 is a back plate fixed to the vehicle body side, and a pair of left and right brake shoes 20, 30 are disposed inside the back plate. In the brake shoes 20 and 30, shoe webs 22 and 32 are joined to the inner peripheral sides of arc-shaped rims 21 and 31, and friction materials 23 and 33 are fixed to the outer peripheral surfaces of the rims 21 and 31, respectively. A wheel cylinder 40 that expands and retracts the brake shoes 20 and 30 and an anchor 41 that serves as a fulcrum when the brake shoes 20 and 30 are expanded and contracted are disposed on the upper and lower portions inside the back plate 10. A pair of upper and lower return springs 50 and 51, which constantly bias in the radial direction, are stretched between the brake shoes 20 and 30. One end of the brake lever 60 that penetrates the back plate 1 is pivotally attached to the right end portion of the strut 70 via a pin 61, and the locking arm 62 of the lever 60 is formed in the shoe web 32 of the brake shoe 30 on the right side of the drawing. The brake lever 60 is engaged with the through hole 34, and the other end of the brake lever 60 is connected to a traction cable (not shown).

<B> Automatic shoe clearance adjustment device A bell crank lever 72 is pivotally attached to the left end of the plate-shaped strut 70 via a pin 71, and a projection 72a at one end of the bell crank lever 72 is shown on the left side of the drawing. Is engaged with a square hole 24 formed in the brake shoe 20. The shoe web 32 of one brake shoe 30 is fitted in the groove 73 at the right end of the strut 70, and the spring 53 stretched between the strut 70 and the shoe web 32 restrains the rattling between the members 70, 32. is doing. On the left side of the strut 70 in the drawing, there is formed a meshing portion 74 that meshes with a curved end surface 72b centered on the pin 71 of the bell crank lever 72, and a spring 54 stretched between the strut 70 and the pin 71 is formed on the end surface 72b. And the meshing portion 74 are urged in a direction to mesh with each other. The structure of the brake assembly and the operation of the automatic shoe clearance adjusting device described above are the same as those of the prior art except for the clearance adjusting and stopping device described later.

<C> Gap Adjustment Stopping Device FIG. 3 shows a state before the assembly of the gap adjustment stopping device, and FIG. 4 shows a state after the assembly. As shown in FIG. 3, the temperature-sensitive member 80, which senses an increase in the brake temperature and is deformed, is made of a material such as a plate-shaped bimetal or a shape memory alloy, and is a base fixed to the shoe web 22 of one brake shoe 20. An end portion 81, a free end portion 82 extending on the same plane as the base end portion 81, a hook portion 83 extending near the tip of the free end portion 82 on the same plane as the free end portion 82, and a hook portion. An end portion of 83 is bent at a right angle to the plate surface of the hook portion 83, and a detection portion 84 is formed. The present invention improves the mounting structure of the temperature sensitive member 80 as described below. At the base end portion 81 of the temperature sensitive member 80, a variant mounting hole 85 having substantially the same shape as the variant mounting hole 25 formed in the shoe web 22, such as an ellipse, a triangle or a polygon, is provided. The clip 80 is elastically attached to the brake shoe 20 by inserting the illustrated clip 90 into both the base end portion 81 and the modified mounting holes 85 and 25 of the shoe web 22. As shown in FIG. 4, the detection portion 84 of the temperature-sensitive member 80 is inserted into the shoe web 22 in contact with the inner surface of the square hole 24 of the shoe web 22 to detect the protrusion 72a of the bell crank lever 72 and the temperature-sensitive member 80. A play g (Fig. 4) at room temperature is set between the portion and the portion 84. As shown in the enlarged view of FIG. 5, the clip 90 includes an insertion portion 91 having a cross-section that can be inserted into the base end portion 81 of the temperature-sensitive member 80 and the both-shaped attachment holes 85 and 25 of the shoe web 22, and the insertion portion 91. A known stopper integrally formed with a resin or the like on the upper portion of the portion 91 and a head portion 92 formed larger than the insertion portion 91. The side surface of the insertion portion 91 faces the head portion 92 from the bottom portion of the insertion portion 91. A wedge-shaped locking portion 93 having an increased wall thickness is formed. The inside of the insertion portion 91 is hollow, and at least one locking portion 93 is expanded / contracted so that it can be inserted into the temperature-sensitive member 80 and the deformed mounting holes 85 and 25 of the shoe web 22 to be locked. .

[0013]

[Action]

 Next, the operation of the gap adjustment stopping device will be described.

<a> Attaching / detaching operation of temperature-sensitive member Until now, it was necessary to attach the temperature-sensitive member 80 to a predetermined brake shoe with a rivet or the like before assembling the brake shoes 20, 30 to the brake assembly. It was In the present invention, it is not necessary to attach the temperature sensitive member 80 to the brake shoe 20 in advance, but the temperature sensitive member 80 may be attached in the following manner after the brake shoes 20 and 30 are assembled to the brake assembly. As shown in FIG. 3, the temperature sensitive member 80 is placed on one surface of the brake shoe 20 (the surface opposite to the back plate 10 side). At this time, the detection portion 84 of the temperature sensitive member 80 is inserted into the square hole 24 of the brake shoe 20. Both the temperature-sensitive member 80 and the odd-shaped mounting holes 85 and 25 of the brake shoe 20 are aligned with each other, and the insertion portion 91 is inserted into the holes 25 and 85 until the head 92 of the clip 90 is pressed against the temperature-sensitive member 80. 93 is locked to the back side of the shoe web 22. In this manner, the base end portion 81 of the sensitive member 80 is elastically attached to the shoe web 22. When the brake shoes 20 and 30 are replaced, the locking portion 93 of the clip 90 is pinched with a tool or the like and the clip 90 is pulled out to the head 92 side, so that the temperature sensitive member 80 and the brake shoe 20 are attached. To cancel.

<B> When temperature rises When the temperature inside the drum brake reaches the set temperature of the temperature-sensitive member 80, the temperature-sensitive member 80 moves from the shoe web 22 of the brake shoe 20 around the base end 81 of FIG. When tilted in the direction of separating, the detection portion 84 of the temperature sensitive member 80 slips out of the square hole 24 of the shoe web 22 as shown by the chain double-dashed line in FIG. 4, and the protrusion of the bell crank lever 72 in the square hole 24. The amount of play of 72a increases. As a result, the amount of clearance between the brake shoes 20, 30 and the brake drum increases due to the temperature expansion of the brake drum, and even if the brake shoes 20, 30 move more than necessary, the automatic shoe clearance adjustment remains stopped. Become.

[0016]

Second Embodiment FIG. 6 shows another temperature-sensitive member 80a in which the free end portion 82 is bent along the way to form a bent portion 86. In this embodiment, there is an advantage that the sensitivity to temperature is further improved by increasing the total length of the free end portion 82 by the amount of the bent portion 86.

[0017]

Third Embodiment The clip 90 is not limited to being made of resin and may be formed of a leaf spring or a wire spring. Further, if the clip 90 is formed integrally with the temperature sensitive members 80 and 80a, the number of parts is reduced and the assembling property is improved.

[0018]

[Effect of the present invention]

 Since the present invention is as described above, the following effects can be obtained.

<A> Since the base end of the temperature sensitive member is elastically clipped from the side opposite to the back plate to the shoe web, the temperature sensitive member can be mounted after the brake assembly is assembled. Therefore, the temperature-sensitive member will not be deformed due to handling or stacking during transportation.

<B> Since the temperature sensitive member is detachably attached to the shoe web, it can be reused after the brake shoe is replaced.

<C> Since the temperature sensitive member is elastically attached to the shoe web with a clip, special equipment for the attachment is not required and the shoe web can be easily attached.

<D> Since the shoe web and the base end portion of the temperature-sensitive member and the clip are elastically fitted to each other by the irregular shape fitting, the temperature-sensitive member does not rotate with respect to the surface direction of the shoe web, and The free end of the sensitive member does not ride on the web or come off the web square hole. Therefore, the shoe clearance automatic adjusting operation and the clearance adjusting stopping operation are surely performed.

[Brief description of drawings]

FIG. 1 is a plan view of a drum brake.

FIG. 2 is a sectional view of II-II in FIG.

FIG. 3 is an assembly drawing of a temperature sensitive member.

FIG. 4 is an enlarged view of an arrow IV frame in FIG.

5 is a sectional view of VV in FIG.

FIG. 6 is an explanatory diagram of a second embodiment showing another temperature sensitive member.

Claims (3)

[Scope of utility model registration request] 1. A strut is disposed between a pair of opposing brake shoes, a bell crank lever is rotatably supported at one end of the strut, and one end projection of the crank lever is drilled in one shoe web. When the brake shoe engages with the provided hole with play, and the expansion amount of the brake shoe exceeds the play, the bell crank lever rotates to automatically adjust the clearance of the brake shoe, and The base end of the temperature sensitive member is attached to the shoe web, and the detection portion formed by bending the free end of the temperature sensitive member is engaged with the hole formed in the one shoe web to increase the brake temperature. Accordingly, in the device for adjusting the gap of the drum brake, in which the detecting portion of the temperature-sensitive member comes out of the hole of the shoe web and is deformed in a direction to substantially increase the play, the one shoe web and the temperature-sensitive portion Of bored respectively mounting hole in a proximal end portion, said both mounting holes by interpolating the clip, characterized in that the Tamagi the base end portion of the temperature responsive member, gap adjusting stop device of a drum brake. 2. The gap adjusting and stopping device for a drum brake according to claim 1, wherein each of the mounting holes at the base end portion of the shoe web and the temperature sensitive member is formed in a different shape that is substantially the same as the cross-sectional shape of the clip. . 3. The gap adjusting and stopping device for a drum brake according to claim 1, wherein the clip is integrally formed with the base end of the temperature sensitive member.