JPH09273572A - Drum braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum braking device which exhibits the same braking effect as a two leading shoes type with the use of one shoe tensioner actuated by service braking, and facilitates the incorporation thereinto of a parking braking device and an automatic shoe-slack adjuster. SOLUTION: A link 10 is pivotally supported by an anchor pin 2, and is engaged at its halfway with one brake shoe 4. A shoe-slack adjuster 14 is interposed between the other adjacent ends of the link 10 and the other brake shoe 5. The braking force is transmitted between the brake shoes 4 and 5 through the link 10 and the shoe-slack adjuster 14.

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 capable of obtaining a stable braking force equivalent to that of a touring type (2L type) while having only one shoe expanding device operated by a service brake.

[0002]

2. Description of the Related Art One of the brake types having a shoe extender operated by a service brake is a leading trailing type (LT type) and a duo servo type (DS).
Form) is commonly used. However, the LT type provides a stable braking effect, but has a low braking effect, and is not suitable for trucks in particular. In addition, the DS type drum brake, when the friction coefficient of the lining becomes high,
There is concern about the stability of the braking performance because the braking effectiveness increases rapidly and early locking is apt to occur, and braking imbalance between the left and right wheels easily occurs. As a drum brake device having relatively excellent braking performance and stability, there are two leading type (2L type) and dual two leading type (D2L) equipped with two shoe expanding devices (for example, wheel cylinders) at symmetrical positions of the axle. Form) is known.

[0003]

The touring type and dual touring type drum brake devices have the following problems.

<A> It is difficult to incorporate a parking brake device due to layout restrictions and complicated structure. Therefore, a separate transmission brake device is provided to deal with the problem, but the vehicle becomes heavy and the cost becomes high.

<B> It is difficult to design the shoe clearance automatic adjusting mechanism for automatically adjusting the clearance between the brake drum and the brake shoe in one form because it has two shoe expanding devices.

<C> Since two shoe expanding devices are provided, the piping is troublesome and the cost is high.

<D> A drum brake device that performs a braking action equivalent to that of the touring type is disclosed in Japanese Utility Model Publication No. 50-38.
No. 704 is disclosed. 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 improvements. (A) Attaching the automatic shoe clearance adjusting device to the shoe expanding device increases the cost, 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 attached, it is difficult to incorporate the parking brake device. (B) A spring is stretched around the arm member to maintain the neutral state of the crank mechanism during non-braking. When adjusting the shoe clearance, the fulcrum of the crank mechanism supported by the back plate becomes one point, and the spring force acting on the crank mechanism is likely to be unbalanced. When the balance of the spring force is lost, the spring force acts on the crank mechanism in a biased manner, causing the brake shoe to slide during traveling. (C) The reliability of durability is low because the number of constituent parts of the crank mechanism is large and the number of rotating parts and the number of supporting points for braking force are large. (D) It is very difficult to design a layout in which the crank mechanism is arranged in a narrow space.

The present invention has been made to solve the above problems, and an object thereof is to present a duoservo type equipped with one first shoe expanding device for operating both brake shoes by a service brake. The purpose of the present invention is to provide a drum brake device capable of obtaining a braking action equivalent to that of a touring type. Still another object of the present invention is to provide a drum brake device that can easily incorporate a second shoe expansion device device that operates both brake shoes by a parking brake and a shoe gap automatic adjustment device. Another object of the present invention is to provide a drum brake device having excellent durability.

[0009]

The invention according to claim 1 is
In a drum brake device, an anchor pin is provided between one adjacent ends of opposing brake shoes, and a first shoe expansion device that operates both brake shoes by a service brake is provided near the anchor pin. One of the links superposed on the shoe web of the brake shoe is rotatably supported on the anchor pin, and the link and the other brake shoe are operatively engaged with the one shoe web in the middle of the link. Is a drum brake device characterized in that the other adjacent ends of are connected so that braking torques can be transmitted to each other.

According to a second aspect of the present invention, an anchor pin is provided between one adjacent ends of the opposing brake shoes, and both brake shoes are operated by a service brake in the vicinity of the anchor pin. In the drum brake device in which is arranged, one of the links superposed on the shoe web of one of the brake shoes is rotatably supported by the anchor pin, and the pin is provided in the middle of the link and the superposed portion of the one shoe web. Insert and engage,
A shoe gap adjusting device is provided between the other adjacent ends of the link and the other brake shoe, and a braking force is transmitted between the brake shoes via the link and the shoe gap adjusting device. It is a drum brake device.

According to a third aspect of the present invention, in the drum brake device according to the first or second aspect, a second shoe for operating both brake shoes by a parking brake is provided between one adjacent ends of the both brake shoes. A drum brake device, characterized by being equipped with an expansion device.

The invention according to claim 4 is the drum brake device according to claim 3, wherein the second shoe expansion device is a forward pull type.

The invention according to claim 5 is the drum brake device according to claim 3, wherein the second shoe expansion device is a cross-pull type.

According to a sixth aspect of the present invention, in the drum brake device according to any one of the first to fifth aspects, a shoe gap automatic system that senses a gap between the brake drum and both brake shoes and automatically adjusts the shoe gap. A drum brake device characterized by having an adjusting device.

According to a seventh aspect of the present invention, in the drum brake device according to the sixth aspect, one of the adjusting levers is rotatably supported by the shoe web of the other brake shoe so that the middle of the adjusting lever is rotatably supported. Is urged toward the anchor pin via the lever stopper, and the other side of the adjust lever is operatively engaged with the shoe gap adjusting device, and the gap between the brake drum and both brake shoes is detected and automatically adjusted. Is a drum brake device.

According to an eighth aspect of the present invention, in the drum brake device according to the seventh aspect, when an excessive thrust force acts on the shoe gap adjusting device, the spring means can extend so as to extend between the anchor pin and the adjusting lever. The drum brake device is characterized by being stretched between them.

According to a ninth aspect of the present invention, in the drum brake device according to the sixth aspect, the shoe web of the other brake shoe is rotatably supported in the middle of the adjust lever, and one of the adjust levers and the anchor pin are provided. An adjust link mounted between the adjust levers, the pole lever being rotatably hooked on the other of the adjust levers, and the other of the pole levers being operatively engaged with the shoe gap adjusting device, and the adjust link. The drum brake device is characterized in that spring means for applying tension to the pole lever is attached to the pole lever, and the gap between the brake drum and both brake shoes is sensed and automatically adjusted.

According to a tenth aspect of the present invention, in the drum brake device according to the ninth aspect, when an excessive thrust force acts on the shoe gap adjusting device, the spring means can be contracted to reduce the pole lever and the other brake. The drum brake device is characterized in that it is contracted between the shoe and the shoe.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 of the present invention will be described below with reference to FIGS.

<B> Back Plate FIG. 1 shows a plan view of the drum brake device, FIG. 2 shows a central longitudinal sectional view thereof, and FIG. 3 shows an exploded view thereof. A central hole 1a into which the axle is fitted is formed in the center of the back plate 1, and is fixed to the vehicle body by a plurality of bolt holes 1b.
An anchor pin 2 is fixedly attached to the upper portion of the back plate 1 in the drawing, and a stiffener 3 stacked on the back plate 1 is attached.
Strengthens the strength around the anchor pin 2.

<B> Brake shoes A pair of brake shoes 4, 5 are mounted on the back plate 1. Brake shoes 4, 5 are shoe rims 4
a, 5a and shoe webs 4b, 5b are joined to each other in a T-shaped cross section, and linings 4c are provided on the outer circumferences of the shoe rims 4a, 5a.
It is configured by fixing 5c. Between the brake shoes 4, 5 and the anchor pin 2, the shoe return spring 6,
6 is stretched, and the brake shoes 4, 5 have one end 4d, 5
B is urged toward the anchor pin 2. The brake shoes 4, 5 are elastically held on the back plate 1 by shoe hold devices 7, 7. In this example, the shoe hold device 7 is provided at one place of each of the brake shoes 4 and 5, but it may be provided at two places, and the elastic body 8 of the shoe hold device 7 shown in FIG. It goes without saying that a leaf spring may be used instead.

<C> First Shoe Expansion Device A first shoe expansion device 9 is fixed to the back plate 1 near the anchor pin 2 by bolts or the like. The shoe expansion device 9 includes a pair of push rods 9a, 9 on the axis.
In the well-known hydraulic or pneumatic wheel cylinder equipped with a, the push rods 9a, 9a are advanced by the service brake. Each push rod 9a, 9
a has a notch groove for engagement at the end, and the brake shoe 4,
5 is engaged with the shoe webs 4b, 5b on one side 4d, 5d.

<D> Link In the present invention, one brake shoe 4 is not directly brought into contact with the shoe gap adjusting device 14, but is brought into contact with the shoe gap adjusting device 14 via the link 10. That is, the plate-shaped link 10 is superposed on the shoe web 4b of one of the brake shoes 4. The link 10 is rotatably supported by fitting a hole 10a formed in one side of the link 10 into the anchor pin 2 (FIG. 7). As shown in FIGS. 5 and 6, in the middle of the link 10, a pin 11 is attached to one brake shoe 4 so as to penetrate therethrough. Pin 1
Hole 10c of link 10 and shoe web 4b for inserting 1
The holes 4e are formed at corresponding positions. The engagement relationship between the pin 11 and the hole 4e is the brake shoe 4 or 5
It suffices that the braking force generated in 1 can be transmitted to the other party, and thus the planar shape of the hole 4e is not limited to the shape shown in FIG. The pin 11 is fastened to the tip of the pin 11 via a flat washer 12 by a snap ring 13 to prevent the pin 11 from coming off. Pin 1 instead of snap ring 13
You may crimp the front-end | tip part of 1 with a press. In the case of caulking, the disengagement strength doubles.

<E> Automatic shoe clearance adjusting device The shoe clearance automatic adjusting device 40 for automatically adjusting the clearance between the brake drum and the linings 4c, 5c will be described. As shown in FIG. 1, a shoe gap adjusting device 14 is interposed between the other end 10b of the link 10 and the other end 5f of the other brake shoe 5. Shoe gap adjusting device 14
Is a device for adjusting the clearance between the brake drum and the linings 4c, 5c, and is composed of a bolt member 15, a nut member 16 and a socket member 17 integrally provided with an adjusting toothed wheel 15a as shown in FIG. The notch groove 16a formed in 16 engages with the link 10, and the socket member 17
The notch grooves 17a formed in the above are engaged with the shoe webs 5b of the other brake shoe 5, respectively.

The total length of the shoe gap adjusting device 14 can be automatically adjusted by rotating the adjusting lever 41 meshing with the adjusting toothed wheel 15a. The adjusting lever 41 has a tubular flange 41a (see FIG. 4) integrally formed by burring in the middle part thereof, and the flange 41a is rotatably supported in the hole 5e of the shoe web 5b to provide a shoe hold. Shoe web 5b with device 7
Holds elastically on top. Also, adjust lever 4
One notch 42a of the lever stopper 42 is engaged with a standing piece 41c which is formed by bending the shoe web 5b on one side 41b in a direction away from the shoe web 5b.
The other 41d is operatively engaged with the adjusting toothed wheel 15a. As shown in an enlarged view in FIG. 9, in the substantially rigid lever stopper 42, one notch 42a is engaged with the upright piece 41c of the adjusting lever 41 and the other notch 42b is rotatable with respect to the anchor pin 2. In addition, it is movable in the longitudinal direction and is tiltably engaged with the contact point with the anchor pin 2 as a fulcrum. In the adjust spring 43, the lever stopper 42 is fitted and inserted in the coil 43a in the middle portion thereof, and the hooks 43b and 43c at both ends are respectively attached to the anchor pin 2 and the rising piece 41 of the adjust lever 41.
The adjusting lever 41 and the lever stopper 42 are held in place by being stretched between the adjusting lever 41 and the lever c.
Instead of the tension coil type adjustment spring 43,
A compression coil type spring may be compressed between the one 41b of the adjust lever 41 and the shoe rim 5a of the other brake shoe 5.

In FIG. 1, a spring 19 is stretched between the other ends 4f, 5f of the brake shoes 4, 5. The spring 19 functions not only to prevent the shoe gap adjusting device 14 from falling off and to prevent the bolt member 15 from rotating, but also to maintain the engagement between the one brake shoe 4 and the link 10. The spring 19 may be made small, and another spring may be provided between the one brake shoe 4 and the link 10 and between the link 10 and the other brake shoe 5, respectively. Reference numeral 20 denotes a guide plate that restricts one end 4d, 5d of the brake shoes 4, 5 adjacent to each other and one of the links 10 and is attached to the anchor pin 2.

<F> Second Shoe Expansion Device As shown in FIG. 1, the second shoe expansion device 30 has a brake lever 31 and a strut 32 as basic components. The brake lever 31 is superposed on the shoe web 5b of the other brake shoe 5, the base of which is rotatably pivoted on the brake shoe 5 by a pin 33 and the other free end 3
Cable end 36 of control cable 35 on 1b
Is locked. A C-shaped retainer 34 fixed to the tip of the pin 33 prevents the pin 33 from coming off.
The protrusion 31a formed on the outer circumference of the brake lever 31 comes into contact with the inner surface of the shoe rim 5a, thereby restricting the return position of the brake lever 31 when the brake is inoperative.
The plate-shaped strut 32 has notches at both ends, and the shoe web 4b of one brake shoe 4 and the brake lever 31 are provided.
Is engaged and bridged over. Reference numeral 37 is an anti-rattle spring that suppresses vibration of the struts 32. Although the second shoe expansion device 30 is arranged on the brake center side with respect to the first shoe expansion device 9, it should be arranged between the anchor pin 2 and the first shoe expansion device 9. Is also possible.

[0028]

[Operation]

<a> Operation of service brake Next, the operation of the service brake will be described. FIG.
When a pressing force is applied to the first shoe expanding device 9, the push rods 9a, 9a push the first adjacent ends 4d, 5d of the brake shoes 4, 5 against the force of the shoe return springs 6, 6, respectively. One brake shoe 4 expands around a pin 11 as a fulcrum, and its lining 4c frictionally engages with a brake drum (not shown). The other brake shoe 5 expands around the contact point with the socket member 17 as a fulcrum, and its lining 5c frictionally engages with the brake drum for braking.

Next, the braking action when the vehicle moves forward and backward will be described. When the brake drum is rotating in the forward direction indicated by the symbol A, one brake shoe 4 performs a braking action as a leading shoe having a self-servo, and this acting force causes the leverage (L) of the link 10 shown in FIG. ₂ / L ₁ ) and the reduced force is transmitted to the other brake shoe 5 via the shoe gap adjusting device 14. The other brake shoe 5 is supported by the anchor pin 2 and performs a braking action as a leading shoe having a self-servo, but since the braking action force of one brake shoe 4 is not directly transmitted, the entire braking force is a leading trailing type. It can be kept higher than the (LT type) drum brake device and lower than the duo servo type (DS type) drum brake device. By appropriately selecting the lever ratio (L ₂ / L ₁ ) of the link 10 described above, it is possible to obtain a braking force equivalent to that of a touring type (2L type) drum brake device.

On the other hand, when the brake drum is rotating in the reverse direction indicated by the symbol B, the other brake shoe 5 is a leading shoe having self-servoing with the contact point with the socket member 17 of the shoe gap adjusting device 14 as a fulcrum. The link 1 is provided with a braking action and through the shoe gap adjusting device 14.
0 is transmitted. This transmission force has a lever ratio (L
₁ / L ₂ ) acting on one of the brake shoes 4, the brake shoe 4 being supported by the anchor pin 2 and acting as a leading shoe having a self-servo.
In other words, a high braking force equivalent to that of a duo-servo type (DS type) drum brake device can be obtained during reverse travel. In particular, when using a two-leading type (2L type) drum brake device for the front brake, only the braking force as a trailing shoe that does not have a self-servo is obtained when the vehicle is in reverse, so the braking force of the rear brake is The higher the better,
The drum brake device having the above-described configuration is optimal for this.

<B> Operation of Parking Brake The operation of the second shoe expansion device 30 will be described with reference to FIG. Now, when the control cable 35 is pulled, the brake lever 31 rotates clockwise around the pin 33 as a fulcrum to move the strut 32 to the left, and this acting force resists the spring force of the shoe return spring 6 and one of the brake shoes. 4 spreads around the pin 11 as a fulcrum and frictionally engages with the brake drum. When the control cable 35 is continuously pulled, the pin 33 is made with the contact point with the strut 32 as a fulcrum.
A clockwise rotating force is applied to. When this rotational force resists the spring force of the shoe return spring 6, the other brake shoe 5 expands around the contact point with the socket member 17 of the shoe gap adjusting device 14 as a fulcrum and frictionally engages with the brake drum.

<C> Automatic shoe clearance adjustment operation Next, the operation of the shoe clearance automatic adjustment will be described with reference to FIGS. 1 and 9. As described above, when a pressing force is applied to the first shoe expansion device 9, the brake shoes 4 and 5 are expanded and the respective linings 4c and 5c are frictionally engaged with the brake drum. At this time, if the brake drum is rotating in the direction of arrow A, the brake shoe 5
One side 5d collides with the anchor pin 2 to generate a braking force, but at the same time, the adjusting lever 41, the lever stopper 42, etc. rotate almost integrally with the brake shoe 5, so that the adjustment lever 41 and the other side 41d are adjusted. Tooth wheel 1
The relative position to 5a is almost unchanged, and the shoe gap adjusting device 14 is not adjusted by extension.

Next, when the brake drum is rotating in the direction of arrow B, the brake shoe 5, the adjusting lever 41, etc. rotate substantially integrally until one of the brake shoes 4d hits the anchor pin 2. To do. At this time, since the substantial connecting length of the lever stopper 42 does not change, the adjusting lever 41 moves the adjusting spring 4
By the action force of 3, the lever 41 rotates counterclockwise with the flange 41a as a fulcrum while engaging with the lever stopper 42. Now, when the amount of movement of the other 41d of the adjusting lever 41 exceeds the inter-tooth pitch of the corresponding adjusting toothed wheel 15a, the next new tooth is engaged when the brake is released. As shown in the enlarged view of FIG. 8, the new teeth are rotated at the time of the next brake operation, and the bolt member 15 is screwed out from the nut member 16 by an amount corresponding to the rotation, whereby the shoe gap adjusting device 14 is extended and the brake drum and the lining 4c. The gap with 5c is automatically closed.

Further, when the frictional force of the other brake shoe 5 is transmitted to the shoe gap adjusting device 14, the link 10 and the one brake shoe 4, and the thrust force of the shoe gap adjusting device 14 is increased, the screw portion The surface pressure increases and the torque for rotating the adjusting toothed wheel 15a increases rapidly. At this time, the adjusting spring 43
Is extended and the lever stopper 42 is freed, so that the automatic adjustment component is not damaged. The automatic shoe clearance adjusting device 40 is inexpensive because it is composed of a press part and a tension coil spring, and the layout is easy because it is arranged on the other brake shoe 5.

When manually adjusting the total length of the shoe clearance adjusting device 14, the plug fitted in the working hole of the back plate 1 is removed, and then the outside of the brake is pressed with a tool such as a minus driver. When the adjusting toothed wheel 15a is rotated in a desired direction, the bolt member 15 is screwed into and out of the nut member 16, and the entire length of the adjusting device 14 can be manually adjusted.

[0036]

Second Embodiment FIGS. 10 and 11 show another drum brake device to which a second cross-pull type shoe expanding device 130 is applied. In the description of this embodiment and thereafter,
The same parts as those in the first embodiment described above are 100
The number at the place of is added and the detailed description is omitted. Further, for simplification of the drawing, FIG. 10 is described with contents including Embodiment 3 described below.

<A> Configuration 101 is a back plate, 102 is an anchor pin, 10
3 is a stiffener, and 104 and 105 are opposing brake shoes. 106 and 106 are shoe return springs, 107 and 107 are shoe hold devices, 109 is a first shoe expansion device, 110 is a link, 111 is a pin,
114 is a shoe gap adjusting device, and 119 is a spring. It is also possible to make the spring 119 small and attach another spring between the one brake shoe 104 and the link 110 and between the link 110 and the other brake shoe 105, respectively.

An intermediate portion of the substantially L-shaped brake lever 131 inside the brake is provided with a pin 133 on a strut 132 which will be described later.
Is rotatably supported, and one finger portion 131e is operatively engaged with the other brake shoe 105, and the other free end portion 131b freely penetrates through the hole 101c of the back plate 101. . Flat surface 13 formed on the free end side
1c regulates the return position when the brake is not operated.
131f is a hole for connecting a control cable (not shown). The strut 132, one of which is pivotally supported by the brake lever 131, has a notch 13 formed in the other.
2e is operatively engaged with one brake shoe 104, and one side surface 132f is in sliding contact with the stiffener 103. In the present embodiment, the second shoe expansion device 13
Although 0 is arranged on the brake center side with respect to the first shoe expanding device 109, it is also possible to arrange 0 between the anchor pin 102 and the first shoe expanding device 109.

<B> Brake Operation Since the service brake operation is the same as in the first embodiment described above, its explanation is omitted.

The operation of the parking brake will be described. When a control cable (not shown) is pulled in the direction of the arrow Y, the other brake shoe 1 of the finger portion 131e is pulled.
The strut 132 is moved left about the contact point with 05 as a fulcrum,
Due to this acting force, one brake shoe 104 frictionally engages with the brake drum. Next, the finger portion 131e moves right about the pin 133 as a fulcrum to move the other brake shoe 105
Frictionally engages the brake drum.

[0041]

Third Embodiment Another drum brake device to which another shoe gap automatic adjusting device 140 is applied will be described with reference to FIGS. 10 and 12.

<B> Configuration The shoe clearance automatic adjusting device 140 is provided with the adjusting lever 1
41, a pole lever 144, an adjusting link 142, and an adjusting spring 143. The middle portion of the adjust lever 141 is the other brake shoe 10
5 is rotatably supported on one side thereof, and a plurality of semicircular grooves 141e formed on one side 141b thereof are fitted at appropriate positions on links 14 to be described later.
2 is hooked, and a pole lever 144 described later is hooked on the stepped surface 141f of the bent portion that is bent toward the back plate 101 side of the other 141d. In the adjust link 142 made of a relatively thick spring wire, one U-shaped hook 142 a of the adjust link 142 has a groove 1 of the adjust lever 141.
41e and the other U-shaped hook 142
b is hooked in the groove of the anchor pin 102. The adjusting link 142 is rotatable and tiltable around the hanging point as a fulcrum. The adjusting lever 141 is inserted into the hole 144a formed in the middle of the pole lever 144.
The bent portion is inserted and is rotatably engaged in the clockwise direction in FIG. 10 with the contact point with the stepped surface 141f as a fulcrum. Further, one side 144b of the pole lever 144 is operatively engaged with the adjusting toothed wheel 115a of the shoe gap adjusting device 114, and both sides of the notch 144d provided in the other side 144c straddle the stepped portion of the adjusting lever 141. It is in sliding contact with the plate surface. The adjusting spring 143 is contracted between the other brake shoe 105 and the pole lever 144, and the bottom of the notch 144d of the adjusting lever 14 in FIG.
The bias lever 1 is urged to press the side end surface of the stepped portion 1 and the adjustment lever 141 is inserted through the pole lever 144.
Always gives a clockwise bias.

<B> Automatic shoe clearance adjusting operation The operation of the shoe clearance adjusting apparatus 140 will be described with reference to FIG. When a pressing force is applied to the first shoe expansion device 109 while the brake drum (not shown) is rotating in the direction of arrow B, the intermediate portion of the adjusting lever 141 moves following the other brake shoe 105. At this time, since the link 142 is substantially rigid, the adjust lever 141 rotates counterclockwise about the pivotal support portion in the middle thereof as a fulcrum, and the pole lever 144 engaged with the lever 141 is also integrated. Rotate. As a result, the adjusting toothed wheel 115a of the shoe gap adjusting device 114 is rotated to perform a shoe gap adjusting action. Then, when the thrust force of the shoe gap adjusting device 114 increases, the adjusting spring 143 bends, and the pole lever 144 can rotate clockwise around the hole 144a as a fulcrum. Absent.

[0044]

Fourth Embodiment of the Invention The present invention is based on the first embodiment described above.
However, the combination of the second shoe expanding devices 30 and 130 and the shoe gap automatic adjusting devices 40 and 140 may be changed, or a new shoe gap automatic adjusting device may be provided. In addition, the second shoe expanding devices 30 and 130 and the shoe gap automatic adjusting devices 40 and 14
0 is not indispensable, and many modifications are possible, such as mounting as needed.

[0045]

According to the present invention, the following effects can be obtained. (A) Since there is only one shoe expansion device that is operated by the service brake, a stable braking force equivalent to a touring type can be obtained with a simple link mechanism, and the piping of the brake pipe is simple. (B) Since a simple link mechanism is simply attached to the duo servo type drum brake as a base, the parking brake device can be easily incorporated. (C) Not only the parking brake device but also the shoe gap automatic adjustment device can be easily incorporated. (D) The adjustment of the clearance between the brake drum and the brake shoe is basically the same as that of the conventionally known duo-servo type, so there is no problem in its adjustability, and one brake shoe is too clogged, causing dragging. There is no risk of erroneous adjustment. (E) Since the number of link mechanism parts is small, the number of assembly steps can be significantly reduced. As a result, the number of rotating parts is small, so that reliability is high over a long period of time. (F) Since the links need only be superposed on the shoe web and attached, the layout is extremely simple and can be applied at a low cost. (G) Since the second shoe expanding device can be applied to the forward pull type or the cross pull type, it is versatile.

[Brief description of drawings]

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

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

FIG. 3 is an exploded view of the drum brake device

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 is a cross-sectional view of VV in FIG.

6 is a sectional view of VI-VI in FIG.

FIG. 7 is an explanatory diagram of the leverage of the link.

FIG. 8 is an enlarged view of the shoe gap adjusting device in FIG.

9 is a partially enlarged view of the shoe clearance automatic adjusting device in FIG.

FIG. 10 is a plan view of a drum brake device according to another embodiment.

11 is a sectional view of XI-XI in FIG.

12 is a sectional view taken along line XII-XII in FIG.

[Explanation of symbols]

 1, 101 ... back plate, 2, 102 ... anchor pin, 4, 5, 104, 105 ... brake shoe, 4d, 5d ... one adjacent end of brake shoe, 4f, 5f ... other side of brake shoe, 6 ………… Shoe return spring, 7 …… Shoe hold device, 9,109 …… First shoe expansion device, 10,110 …… Link, 11,111 …… Pin, 14,114 …… Shoe clearance adjustment Device, 15 ... Bolt member, 15a, 115a ... Adjusting toothed wheel, 16 ... Nut member, 17 ... Socket member, 19,119 ... Spring, 30,130 ... Second shoe expansion device, 31, 131 ... Brake lever, 31b, 131b ... Free end of brake lever, 32, 132 ... Strut, 33, 133 ... Pin, 40, 1 0 …… Shoe clearance automatic adjusting device, 41,141 …… Adjust lever, 41a …… Adjust lever flange, 42 …… Lever stopper, 43,143 …… Adjust spring, 142 …… Adjust link, 144 …… Pole lever .

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[Submission date] May 22, 1996

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FIG.

Claims (10)

[Claims] 1. A drum brake in which an anchor pin is provided between one adjacent ends of opposing brake shoes, and a first shoe expanding device for operating both brake shoes by a service brake is provided in the vicinity of the anchor pin. In the device, one of links linked to a shoe web of one brake shoe is rotatably supported by an anchor pin, and an intermediate part of the link is operatively engaged with the one shoe web. A drum brake device, characterized in that the braking torque is mutually transmitted between the other adjacent ends of the other brake shoe. 2. A drum brake in which an anchor pin is disposed between one adjacent ends of opposing brake shoes, and a first shoe expanding device for operating both brake shoes by a service brake is disposed in the vicinity of the anchor pin. In the device, one of the links superposed on the shoe web of one brake shoe is rotatably supported by the anchor pin, and the pin is inserted through the overlapping portion of the one of the shoe webs and the midway of the link. , A shoe gap adjusting device is provided between the other adjacent ends of the link and the other brake shoe, and a braking force is transmitted between the brake shoes via the link and the shoe gap adjusting device. And the drum brake device. 3. The drum brake device according to claim 1 or 2, further comprising a second shoe expanding device for operating both brake shoes by a parking brake between adjacent ends of the both brake shoes. A drum brake device characterized by the above. 4. The drum brake device according to claim 3, wherein the second shoe expansion device is a forward pull type. 5. The drum brake device according to claim 3, wherein the second shoe expansion device is a cross-pull type. 6. The drum brake device according to any one of claims 1 to 5, further comprising a shoe gap automatic adjusting device for sensing and automatically adjusting a gap between the brake drum and both brake shoes. A drum brake device characterized by the above. 7. The drum brake device according to claim 6, wherein the shoe web of the other brake shoe is rotatably supported in the middle of the adjusting lever, and one of the adjusting levers is urged by a spring means via a lever stopper. It is characterized in that it urges toward the anchor pin and operatively engages the other of the adjusting levers with the shoe gap adjusting device to detect the gap between the brake drum and both brake shoes and adjust automatically. , Drum brake device. 8. The drum brake device according to claim 7, wherein when an excessive thrust force acts on the shoe gap adjusting device, the spring means is stretchably extended between the anchor pin and the adjusting lever. The drum brake device is characterized in that 9. The drum brake device according to claim 6, wherein the shoe web of the other brake shoe is rotatably supported midway of the adjust lever, and an adjust link is provided between one of the adjust levers and the anchor pin. It is mounted, and the pole lever is rotatably hooked to the other of the adjusting levers, and the other of the pole levers is operatively engaged with the shoe gap adjusting device, and a tension is applied to the adjusting link. A drum brake device characterized in that spring means is attached to a pole lever and the gap between the brake drum and both brake shoes is detected and automatically adjusted. 10. The drum brake device according to claim 9, wherein when an excessive thrust force acts on the shoe gap adjusting device, the spring means is contractible between the pole lever and the other brake shoe. A drum brake device, which is characterized by being installed.