JPH1047396A - Drum brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum brake device obtaining stable brake force of a degree similar to that of dual two leading type (D2L type) though by a single shoe spread device operated by a service brake. SOLUTION: Anchors 9, 9 are arranged between one adjacent ends 4a of opposed brake shoes 2, 2, a shoe space adjusting device 10 is arranged between the other adjacent ends 4b, and a first shoe spread device 13 operated by a service brake is arranged near the anchors 9, 9. One link 11a of links 11, 11 pivotally rotatably supported to an intermediate part of the brake shoes 2, 2 is operatively engaged with the first shoe spread device 13, while the other link 11b is engaged with the shoe space adjusting device 10. In this constitution, operating force of the first shoe spread device 13 transmitted to the links 11, 11 is respectively transmitted to the brake shoe 2, 2 through the pivotal support part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake device having a self-servo function.

[0002]

2. Description of the Related Art Conventionally, as a drum brake device having relatively excellent braking performance and stability, there are two reading type (2L type) including two shoe expansion devices (for example, wheel cylinders) at symmetrical positions of an axle. A dual-to-reading type (D2L type) is known.

The conventional 2L-type and D2L-type drum brake devices have the following problems. <B> It is difficult to incorporate a parking brake device due to restrictions on layout and complicated structure. Therefore, a separate transmission brake device is provided to cope with this, but the weight of the vehicle is increased and the cost is increased. <B> The automatic shoe gap adjusting mechanism for automatically adjusting the gap between the brake drum and the brake shoe is difficult to design in one form because it has two shoe extending devices. <C> Since two shoe expansion devices are provided, the piping is complicated and the cost is high. Further, a drum brake device in which a single shoe expanding device performs a braking action equivalent to that of the two-leading type is disclosed in Japanese Utility Model Publication No. Sho 50-38704. In this device, a shoe expanding device is disposed between one adjacent end of the opposed brake shoes, and a crank mechanism that functions in cooperation with a back plate is disposed between the other adjacent ends. This type of drum brake device has the following points to be improved. (A) When the automatic shoe gap adjusting device is attached to the shoe expanding device, the cost increases, and the shoe expanding device side of the brake shoe is separated as the lining wears, and the braking force of the brake shoe is supported by the device. Since the anchor is provided, it is difficult to incorporate the parking brake device. (B) In order to keep the crank mechanism in a neutral state during non-braking, a spring is stretched on the lever member. When adjusting the shoe clearance, the crank mechanism is no longer supported at two points on the back plate, and the spring force acting on the crank mechanism tends to be unbalanced. When the balance of the spring force is lost, the spring force acts on the crank mechanism in a biased manner, so that the brake shoe is dragged. (C) The number of components of the crank mechanism is large, and the number of rotating parts and the number of supporting points of the braking force are large, so that the cost increases. (D) It is very difficult to design a layout in which the crank mechanism is disposed in a small space.

[0004]

[Problems to be solved by the invention]

<A> The present invention is to provide a drum brake device capable of obtaining a stable braking force of a dual two-leading type (D2L type) while using only one shoe expansion device operated by a service brake. <B> The present invention is to provide a drum brake device having excellent durability. <C> The present invention is to provide a drum brake device that can easily incorporate two types of shoe expansion devices and an automatic shoe clearance adjustment device.

[0005]

According to the first aspect of the present invention, opposed brake shoes are movably mounted on a back plate, and anchors are provided between one adjacent ends of the respective brake shoes. In addition, a shoe gap adjusting device is disposed between the other adjacent ends, a first shoe expanding device that is operated by a service brake is disposed near the anchor, and a rotatable pivot is provided at an intermediate portion of each brake shoe. One of the linked links is operatively engaged with the first shoe extension device, and the other is engaged with the shoe gap adjusting device, and the operating force of the first shoe extension device transmitted to the link is transmitted through the pivot. A drum brake device characterized in that the drum brake device is configured to transmit to the respective brake shoes. The invention according to claim 2 is the drum brake device according to claim 1, wherein when the brake drum rotates in one direction, one brake shoe is supported by a shoe gap adjusting device, and the other brake shoe is anchored. A drum brake device characterized in that it is configured to be supported. The invention according to claim 3 is the invention according to claim 1 or 2.
3. The drum brake device according to claim 1, wherein a contact portion between the one adjacent end of the brake shoe and the anchor is unevenly engaged with substantially the same radius of curvature. The invention according to claim 4 is the invention according to claim 1.
The drum brake device according to any one of claims 1 to 3, further comprising a second shoe expansion device operated by a parking brake such that one end of the link is openable. It is. According to a fifth aspect of the present invention, there is provided the drum brake device according to any one of the first to fourth aspects, further comprising an automatic shoe gap adjusting device that automatically detects and adjusts the amount of expansion of the brake shoe. A drum brake device characterized by the following. The invention according to claim 6 is the drum brake device according to any one of claims 1 to 5, wherein a projection is integrally formed on one of the brake shoe and an intermediate portion of the link,
A drum brake device, wherein the projection is rotatably supported by a hole formed in the other side. The invention according to claim 7 is the drum brake device according to claim 6, wherein the projection is hollow, and a shoe hold pin is loosely fitted through the hollow projection. is there.

[0006]

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a front view of a drum brake device in which a pair of left and right brake shoes 2 and 2 are movably mounted on a back plate 1. An anchor 9 is provided above the back plate 1. A wheel cylinder 13 with 9 is disposed, and a shoe gap adjusting device 10 is disposed below the wheel cylinder 13. The drum brake device also includes a pair of links 11, 11 for transmitting the operating force of the wheel cylinder 13 to both brake shoes 2, 2.
Is provided. The drum brake device according to the present invention has substantially the same structure on the left and right in the drawing, except for a forward pull type parking brake which is a second shoe expansion device described later. The description will be omitted, and the description of the arrangement structure in the right half will be omitted. Although the terms “left and right” and “up and down” are used for convenience of description, it is needless to say that the direction of the drum brake device is not limited to the illustrated direction. Hereinafter, details of each unit will be described.

<B> Brake Shoe The brake shoe 2 is configured by joining a shoe rim 3 and a shoe web 4 in a T-shaped cross section, and fixing a lining 5 to the outer periphery of the shoe rim 3. One side surface of the shoe rim 3 is elastically held on the back plate 1 by a shoe holding mechanism 8 including a known U-shaped leaf spring 6 and a shoe holding pin 7. Brake shoe 2
One 4a contacts the anchor 9 and the other 4a
b is engaged with the sleeve 16 of the shoe gap adjusting device 10. The contact portion between the one side 4a of the brake shoe 2 and the anchor 9 is unevenly engaged with substantially the same radius of curvature, and the radius of curvature of the anchor 9 is desirably set slightly larger. When the concave and convex shapes of the brake shoe 2 and the anchor 9 are reversed, the radius of curvature of the brake shoe 2 is set slightly larger.

<C> Link A link 11 is provided on the back surface of the shoe web 4 of the brake shoe 2.
And one of the links 11 is operatively engaged with a piston 13a of a wheel cylinder 13 as a first shoe expansion device, and the other 11b is engaged with a sleeve 16 of a shoe clearance adjustment device 10. I have. Link 11
Is rotatably supported by a flanged sleeve 12 penetrated with the shoe web 4. The flanged sleeve 12 is held by the shoe hold mechanism 8 as shown in FIG.

<D> Shoe Gap Adjustment Apparatus The shoe gap adjustment apparatus 10 adjusts the gap between the brake drum (not shown) and the lining 5, and is screwed to the body 14 fixed to the back plate 1 and the body 14. A pair of left and right adjusting bolts 15 and 15 and sleeves 16 and 16 rotatably fitted to the ends of the adjusting bolts 15 and 15 are provided.
The automatic gap adjusting mechanism is constituted by adding the stopper pins 7, 17 and the stopper pins 18, 18 and the adjusting spring 19.
The shoe gap adjusting device 10 includes the left and right adjustment bolts 1.
5,15 threads are formed in opposite threads.

FIG. 4 is an enlarged view of the left half of the shoe gap adjusting device 10. The adjusting bolt 15 has an adjusting tooth wheel 15a integrally formed at an intermediate portion, and a screw portion 15b is formed on the body 14. The shaft 15c at the other end is rotatably fitted in a blind hole of the sleeve 16 with the female screw 14a. The cutout groove 16a of the sleeve 16 is engaged with the other 4b of the shoe web 4, the other 11b of the link 11, and the adjust lever 17. Adjust lever 17
The arm 17 a is rotatably supported by a stopper pin 18 fixed to the shoe web 4, and the intermediate portion thereof is brought into contact with the cutout groove 16 a of the sleeve 16 by the biasing force of the adjusting spring 19, while Arm 17b
Are engaged with the adjustment gear wheel 15a. Since the shoe gap adjusting device 10 is composed of a pressed component and a tension coil spring, the cost is low, and since it is disposed on the brake shoe 2, its layout is easy.

<E> Shoe return spring A first shoe return spring 20 is provided between the brake shoes 2 and 2 near the wheel cylinder 13 in FIG.
A second shoe return spring 21 is stretched between the brake shoes 2 and 2 close to the shoe gap adjusting device 10. The spring force of the first and second shoe return springs 20 and 21 is, for example, the second shoe return spring 20 and the second shoe return spring 21 so that a moment difference is generated between the brake shoes 2 and 2.
The spring force of the shoe return spring 21 is set smaller than that of the first shoe return spring 20.

<F> Set Moment Difference Acting on Shoe The setting of the moment difference acting on the brake shoe 2 will be described with reference to FIG. Regarding this moment difference, the left and right brake shoes 2, 2 are set to be the same. The mounting load of the first shoe return spring 20 is F1,
The mounting load of the second shoe return spring 21 is F
2. The distance from the pivot point (the sleeve 12 with the flange) of the brake shoe 2 to the link 11 to the first shoe return spring 20 is L1, and the link 1 of the brake shoe 2
Assuming that the distance from the pivot point (sleeve 12 with flange) to the second shoe return spring 21 is L2, the moment acting on each brake shoe 2, 2 is F
It is set so that the relationship of 1 × L1> F2 × L2 is satisfied.

<G> Parking Brake A forward pull type parking brake, which is a second shoe expansion device, will be described with reference to FIG. The brake lever 22 is disposed along the back side of the link 11 on the right side of the drawing, and its base end 22a is rotatably supported by a pin 23. An intermediate portion 22b near the base end 22a is joined to the link 11 by the right end of the strut 24. Is engaged. Brake lever 2
The brake lever 22 can be swung by a pulling operation of a control cable (not shown) hooked on a U-shaped groove bent at the second free end 22c.

<H> Strut The strut 24 is plate-shaped and has cutouts at both ends, and is bridged between the link 11 on the left side in the drawing and the link 11 and the brake lever 22 on the right side in the drawing. Also struts 24
An anti-rattle spring 25 is attached to one of the struts 24 in order to suppress the vibration of the strut 24.

By adopting such a configuration, the first shoe expansion device operated by the service brake, the second shoe expansion device operated by the parking brake,
An automatic shoe gap adjusting device and the like can be easily incorporated.

[0017]

[Action]

<A> Operation at the time of service brake When the brake pedal is depressed, the pistons 13a, 13a of the wheel cylinder 13 press the links 11, 11, and the pair of left and right brake shoes 2, 2 is expanded by the following operation.
Note that the expanding operation of the left and right brake shoes 2, 2 is the same, and therefore the following description will focus on the expanding operation of the brake shoe 2 on the left side of the drawing.

When the piston 13a of the wheel cylinder 13 presses one of the links 11a, the link 11 opens at the contact point with the shoe gap adjusting device 10 of the other side 11b as a fulcrum and brakes through the sleeve 12 with the flange. The shoe 2 is pressed.

At this time, since the moment difference between the first and second shoe return springs 20 and 21 is acting on the brake shoe 2, one of the brake shoes 4
The other side 4b is expanded with the contact point with the anchor 9 on the a side as a fulcrum, and the lining 5 frictionally engages with a rotating brake drum (not shown) to brake this. As is clear from the above, the acting force acting on the brake shoe 2 is:
As shown in FIG. 5, the ratio of the distance L3 from the pivot point of the link 11 pivotally supported by the flanged sleeve 12 to the action point on the one 11a side of the link 11 and the distance L4 from the bearing point, that is, the leverage of the link 11 It can be easily changed by the ratio (L3 + L4) / L4.

In FIG. 1, when the brake drum (not shown) is rotating in the direction of arrow A, the other shoe 4b of the brake shoe 2 on the left side of the drawing is connected to the shoe gap adjusting device 10.
The brake shoe 2 on the right side of the drawing also functions as a leading shoe having a self-servo property, with one of the brake shoes 4a being supported by the anchor 9. In this manner, the pair of left and right brake shoes 2 and 2 perform a two-leading braking action.

When the brake drum is rotating in the direction of arrow B, the other 4 of the brake shoe 2 on the right side of the drawing is used.
b is supported by the shoe gap adjusting device 10 and acts as a leading shoe having a self-servo characteristic. One of the brake wheels 2a on the left side of the drawing is supported by the anchor 9 and acts as a leading shoe having a self-servo characteristic. Brake shoes 2 and 2 perform a two-leading braking action in the same manner as described above. As described above, the dual wheel-reading type (which operates as a leading shoe having self-servo characteristics in both forward and backward movements of the vehicle while having only one wheel cylinder 13 as the first shoe expansion device operated by the service brake). D2L type)
A stable braking force can be obtained.

<B> Automatic Adjustment of Gap The intermediate portions of the adjustment levers 17, 17 in FIG. 1 are pressed against the sleeve 16 by the biasing force of the adjustment spring 19. As described above, each stop pin 1 together with the left and right brake shoes 2 and 2 is operated by the operation of the service brake.
8, 18 move together. Therefore, the adjustment lever 17 on the left side in the drawing rotates counterclockwise about the stopper pin 18 and the adjustment lever 17 on the right side in the drawing.
Rotates clockwise.

In FIG. 4, when the lining 5 wears out and the amount of rotation of the other arm 17b of the adjusting lever 17 exceeds the pitch between the teeth of the adjusting gear wheel 15a, the adjusting bolt 15 is screwed out of the body 14. Rotated,
It is automatically adjusted so that the gap between the brake drum (not shown) and the lining 5 is always kept constant.

In FIG. 1, the wheel cylinder 1
3 is pressurized, the pistons 13a, 13a
The force for pressing one of 11a, 11a increases, and the thrust force applied to shoe gap adjusting device 10 increases. When the thrust force of the shoe gap adjusting device 10 increases, the surface pressure of the thread portion of the adjusting bolt 15 increases, and the torque for rotating the adjusting tooth wheels 15a, 15a increases sharply. Since the extension of 19 causes the stopper pins 18, 18 and one of the arms 17a, 17a of the adjusting levers 17, 17 to be in a free state, the components constituting the automatic gap adjusting mechanism are not damaged.

<C> Actuation of parking brake For example, when a hand brake lever in the vehicle compartment is operated,
The control cable (not shown) is indexed, and the brake lever 22 is rotated clockwise about the pivot point of the base end 22a with the pin 23, and presses the link 11 on the left side of the drawing via the strut 24. I do.

The link 11 rotates counterclockwise around a contact point with the shoe gap adjusting device 10 on the other side 11b as a fulcrum,
The brake shoe 2 on the left side of the drawing is pressed through the sleeve 12 with the flange. At that time, the first brake shoe 2
And the second shoe return springs 20 and 21 act on each other, the brake shoe 2 on the left side of the drawing rotates clockwise around the contact point with the anchor 9 and the lining 5 of the brake shoe 2 on the brake drum. Frictionally engage.

When the control cable is subsequently indexed, a clockwise acting force is generated on the brake lever 22 with the contact point with the strut 24 as a fulcrum, and this acting force is applied to the link 11 on the right side of the drawing via the pin 23. Convey. The link 11 rotates around the contact point with the shoe gap adjusting device 10 as a fulcrum, and presses the brake shoe 2 on the right side of the drawing via the sleeve 12 with the flange. At that time, the moment difference due to the first and second shoe return springs 20 and 21 also acts on the brake shoe 2 on the right side of the drawing.
The brake shoe 2 on the right side in the drawing rotates counterclockwise around the contact point with the anchor 9 and frictionally engages with the brake drum.

[0028]

[Embodiment 2] Some other embodiments according to the present invention will be described below. Functionally, the same portions as those in Embodiment 1 described above are denoted by the same reference numerals, and Description is omitted.

In the first embodiment of the invention described above, the case where one of the brake shoes 2, 2 4a, 4a is supported outside the wheel cylinder 13 with respect to the brake center, as shown in FIG. May be supported inside the wheel cylinder 13. That is, anchors 9, 9 are respectively fixed to both sides of a hole 13c provided in a cylinder body 13b inside the wheel cylinder 13 with respect to the brake center, and one of the brake shoes 2, 2 is attached to each of the anchors 9, 9. , 4a are supported.
The difference between the moments acting on the brake shoes 2 and 2 and the relationship between the lever ratios of the links 11 and 11 are the same as in the first embodiment.

Further, a cross-pull type shown in FIGS. 6 and 7 may be applied as a parking brake which is a second shoe expanding device. That is, the left end of the strut 24 is engaged with the link 11 on the left side of the drawing, and the strut 2
The right end of 4 is engaged with the link 11 on the right side of the drawing via an L-shaped brake lever 22. A base end portion 22a of a brake lever 22 disposed through the back plate 1 is pivotally supported by a right end of a strut 24 via a pin 23, and an engagement arm 22d of the brake lever 22 is connected to a link 1 on the right side in the drawing.
1 is inserted into and engaged with a rectangular hole 11c formed on one side 11a. By pulling the control cable connected to the free end 22c of the brake lever 22 outside the back plate 1, the link 11 on the right side of the drawing moves rightward with the pivot point (pin 23) with the strut 24 as the fulcrum. The brake shoe 2 pivotally supported by the link 11 on the right side of the drawing expands, and the brake shoe 2 pivotally supported by the link 11 on the left side of the drawing via the strut 24 expands. Reference numeral 26 denotes a lever stopper that regulates the return position of the brake lever 22.

[0031]

Third Embodiment FIG. 8 shows another embodiment to which another automatic shoe gap adjusting mechanism is applied. In the present embodiment, the common adjustment bolts 15, 15 having the same direction of the thread threaded on the threaded portion 15b are used,
The left and right adjustment levers 17 are arranged in opposite directions. Since the directions of the left and right adjustment levers 17, 17 are reversed, each of the adjustment levers 17, 1
Adjust spring 19,1 between body 7 and body 14
9 are individually stretched. In the present embodiment,
Not only can the adjustment bolts 15 and 15 be shared, but the processing of the female screw 14a of the body 14 can be simplified.

[0032]

Fourth Embodiment FIGS. 6 and 9 show other pivot means of the brake shoe 2 and the link 11. In the present embodiment, an intermediate portion of the shoe web 4 is burring-processed, and a cylindrical projection 12a formed integrally therewith is inserted into a hole 11d of the link 11 to rotatably pivot. Also, the intermediate portion of the link 11 may be burred to form the projection 12a integrally. The point is that a protrusion for forming a pivot portion is formed on one of the shoe web 4 or the link 11 of the brake shoe 2, and the link 11 may be rotatably supported on the brake shoe 2 via the protrusion.

[0033]

Embodiment 5 The present invention relates to Embodiment 1 described above.
The pivot engagement between one of the brake shoes 2 and the anchor 9 may be provided on the contact surface between the other side 4b of the brake shoe 2 and the sleeve 16, for example. The same effect can be obtained by suppressing the vertical movement of the brake shoe 2 due to the vibration during running. In addition, although the embodiment in which the parking brake is generally used for the rear brake has been described, various modifications are possible, such as being applicable to the front brake if the parking brake component is removed.

[0034]

According to the present invention, the following effects can be obtained. <B> A dual two-leading (D2L type) stable braking force can be obtained while using only one shoe expansion device operated by the service brake. <
B> A drum brake device with excellent durability can be obtained. <C> Two types of shoe expansion devices and an automatic shoe clearance adjustment device can be easily incorporated. <D> The braking force can be set arbitrarily by changing the leverage of the link. <E> If the wheel cylinder is positioned above the vehicle and the free end of the brake lever is positioned below, the layout will be the same as that of a known leading / trailing type drum brake. It will be easier.

[Brief description of the drawings]

FIG. 1 is a front view of a drum brake device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of an anchor portion in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an explanatory view of a shoe gap automatic adjustment mechanism.

FIG. 5 is an explanatory diagram of the leverage of the link and the link acting on the brake shoe.

FIG. 6 is a front view in which a part of a drum brake device according to a second embodiment of the present invention is omitted.

FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6;

FIG. 8 is a front view in which a part of a drum brake device according to a third embodiment of the present invention is omitted.

FIG. 9 is a sectional view of IX-IX in FIG. 6;

[Explanation of symbols]

1 ... Back plate 2, 2 ... Brake shoe 3 ... Shoe rim 4 ... Shoe web 4a ... One of the shoe webs 4b ... the other of the shoe webs 5 ... the lining 6 ... the leaf spring 7 ... the shoe hold pin 8,8 ... the shoe Hold mechanism 9, 9 ... anchor 10 ... shoe gap adjusting device 11, 11 ... link 11a ... one of the links 11b ... ... the other of the links 11c ... ··········································································································································· 13a, 13a · piston of wheel cylinder 14 · · · ... Body 14a ... Body internal thread 15 ... Adjust bolt 15a ... Adjustment bolt adjustment tooth wheel 15b ... One screw shaft of the adjustment bolt 15c ····················································································································· Sensor Arm 17b ... The other arm of the adjust lever 18 ... Stopper pin 19 ... Adjust spring 20 ... First shoe return spring 21 ... · Second shoe return spring 22 ····· Brake lever 22a ··· Base end of brake lever 22b ··· Middle part of brake lever 22c ····································································································· .... Lever stoppers

Claims (7)

[Claims] 1. A brake shoe movably mounted on a back plate, an anchor is provided between one adjacent end of each brake shoe, and a shoe gap adjusting device is provided between the other adjacent ends. A first shoe expansion device operated by a service brake is disposed in the vicinity of the anchor, and one of links rotatably pivoted to an intermediate portion of each brake shoe is operatively connected to the first shoe expansion device. And the other is engaged with the shoe gap adjusting device, and the operating force of the first shoe expanding device transmitted to the link is transmitted to the brake shoe via the pivotal support. And the drum brake device. 2. The drum brake device according to claim 1, wherein when the brake drum rotates in one direction, one brake shoe is supported by a shoe gap adjusting device, and the other brake shoe is supported by an anchor. A drum brake device characterized by comprising. 3. The drum brake device according to claim 1, wherein a contact portion between the one adjacent end of the brake shoe and the anchor has a concave and convex engagement with substantially the same radius of curvature. Yes, the drum brake device. 4. The drum brake device according to claim 1, wherein a second shoe extension device operated by a parking brake is provided so that one end adjacent to the link can be opened. A drum brake device. 5. The drum brake device according to claim 1, further comprising an automatic shoe gap adjusting device that senses an amount of expansion of the brake shoe and automatically adjusts the amount. Characterized by a drum brake device. 6. The drum brake device according to claim 1, wherein a projection is integrally formed on one of the brake shoe and an intermediate portion of the link, and the projection is formed on the other. A drum brake device characterized in that it is rotatably supported by a hole provided. 7. The drum brake device according to claim 6, wherein the protrusion is hollow, and a shoe hold pin is loosely fitted through the hollow protrusion.