JP2001027266A - Duo to leading type drum brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrate a parking brake mechanism into a duo two leading type small-diameter brake while simplifying structure and reducing cost. SOLUTION: A link mechanism is composed of a pivot lever 40 pivotally supported in a rotatable manner to an intermediate part of one brake shoe 10, and a pair of struts 60, 70 disposed almost parallel between the other brake shoe 11 and one side and the other side of the pivot lever 40. A parking brake actuator 50 for expanding a pair of brake shoes 10, 11 in cooperation with the link mechanism is disposed on the path of the link mechanism. A service brake actuator is equipped with a shoe clearance automatic adjusting device, and one of the struts 60, 70 is provided with a parking stroke automatic adjusting device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duo-to-leading drum brake device (hereinafter referred to as "drum brake device") having a built-in parking brake mechanism, and more particularly to a drum brake suitable for a rear brake of a medium-sized commercial vehicle class. Related to the device.

[0002]

2. Description of the Related Art Regardless of the rotation direction of a brake drum,
A parking brake actuating mechanism in which a pair of brake shoes act as a leading shoe to operate the brakes
It is disclosed in Japanese Patent Application Publication No. 1-14371. (FIG. 13) This mechanism is one diagonal end 1 of each of the brake shoes 1 and 2.
a and 2b are provided at one end 3a and 4 of the first lever 3 and the second lever 4, respectively.
a, and between the intermediate portion 3b of the first lever 3 and one end 2a of the other brake shoe 2, and between the intermediate portion 4b of the second lever 4 and the other end 1 of the one brake shoe 1.
b, an upper strut 5 and a lower strut 6 are interposed respectively, an intermediate portion 7b of the operation lever 7 is pivotally connected to the other end 3c of the first lever 3, and the other end of the second lever 4 is connected by the connecting means 8. 4c is connected to one end 7a of the operation lever 7 on the first lever 3 pivot point 9 side, and the other end 7c of the operation lever 7 is formed.
Is pulled in the direction of the second lever 4 to operate the parking brake.

[0003]

The above-mentioned brake mechanism has the following problems. <A> In addition to the upper and lower struts 5, 6 and the operating lever 7, additional parts such as the first and second levers 3, 4 and the connecting means 8 are required, so that the number of components is large and the structure is complicated. Costly. <B> Since the components of the parking brake mechanism are located in the center of the brake, it can be designed as a large-diameter brake for heavy commercial vehicles. It is difficult to secure a space for disposing the parking brake mechanism in the section. <C> Since the parking brake mechanism is not provided with an automatic parking stroke adjusting function, the stroke of the parking brake increases as the lining wears. Further, if an automatic parking stroke adjusting mechanism is provided on one of the upper and lower struts 5, 6, design is extremely difficult due to space restrictions. <D> Connecting means 8 on the operation path of the parking brake
Exists, and there are three levers (first and second levers 3 and 4 and operation lever 7) pivotally connected by pins (no symbol), so that the assembling and disassembling properties are extremely poor.

The present invention has been made in view of the above points, and has as its object the duo-to-leading type drum brake device with a parking brake mechanism, which simplifies the structure and reduces the cost. Is to provide. Still another object of the present invention is to provide a duo-to-leading type drum brake device which is provided with an automatic parking stroke adjusting function to improve operation feeling.

[0005]

The invention according to claim 1 is
A duo-to-leading drum comprising a pair of brake shoes disposed opposite to each other, and a pair of service brake actuators disposed opposite each other between adjacent ends of the two brake shoes. In the brake device, a pivot lever is pivotally attached to an intermediate portion of one of the brake shoes so as to be rotatable, and a pair of struts are disposed substantially in parallel between one and the other of the pivot lever and the other brake shoe. A parking brake actuator for expanding a pair of brake shoes in cooperation with the link mechanism by operating a parking brake is disposed on a path of a link mechanism including the pivot lever and the pair of struts, and a service brake is provided. The brake drums and each brake shoe extend in response to the The pair of service brake actuators is provided with an automatic shoe gap adjusting device that automatically adjusts the gap between the brake shoes, and at least one of the pair of struts extends in response to excessive opening of both brake shoes. And a parking brake automatic adjusting device for automatically adjusting the stroke amount of the parking brake actuator.

According to a second aspect of the present invention, in the first aspect, an automatic shoe clearance adjusting device and a parking stroke are provided so that each adjacent end of both brake shoes is supported by an anchor of a service brake actuator when the brake is not operated. A duo-to-leading type drum brake device, wherein an adjustment convergence value of an automatic adjustment device is set.

According to a third aspect of the present invention, in the first or second aspect, the automatic shoe gap adjusting device includes a screw coupling mechanism including a bolt member and a nut member, and is incorporated in the cylinder of the service brake actuator. Characterized in that it is a duo-to-leading type drum brake device.

According to a fourth aspect of the present invention, in the third aspect, the screw connection mechanism including the bolt member and the nut member is a reversible screw connection, and the automatic shoe gap adjusting operation is an exponential incremental type. ,
It is a duo-to-leading type drum brake device.

According to a fifth aspect of the present invention, in the first or second aspect, the automatic shoe gap adjusting device includes a ratchet mechanism including a lever member and a gear member, and the lever member is provided on the cylinder body of the service brake actuator. A duo-to-leading type drum brake device characterized by being provided with an exterior.

According to a sixth aspect of the present invention, in the duo-to-leading type drum brake device according to the fifth aspect, the automatic shoe gap adjusting operation of the automatic shoe gap adjusting apparatus is a linear incremental type. is there.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the automatic parking stroke adjusting device includes a screw connection mechanism including a bolt member and a nut member, and the automatic parking stroke adjusting operation is linear. A duo-to-leading type drum brake device characterized by being an incremental type.

According to an eighth aspect of the present invention, the automatic parking stroke adjusting device according to any one of the first to sixth aspects comprises a tooth formed on a bell crank lever and an element engaging with the tooth. A duo-to-leading type drum brake device characterized in that the automatic adjustment operation is a one-shot type.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the parking brake actuator is of a forward pull type.
It is a duo-to-leading type drum brake device.

According to a tenth aspect of the present invention, there is provided a duo-to-leading type drum brake device according to any one of the first to eighth aspects, wherein the parking brake actuator is of a cross-pull type. .

According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, one of the pivot lever and the intermediate portion of the shoe web of the brake shoe is provided with a projection integrally formed by pressing. The duo-to-leading type drum brake device, wherein the projection is rotatably supported by a hole formed in one of the other members.

According to a twelfth aspect of the present invention, in the eleventh aspect, the projection is formed into a hollow shape by burring by a press, and a pin for holding a brake shoe is loosely inserted through the hollow. This is a duo-to-leading type drum brake device.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

<A> Overall Structure of Drum Brake FIG. 1 is a plan view of the drum brake device. Symbol 10,
11 is a pair of brake shoes, each of which has a shoe web 10
a, 11a and the rims 10b, 11b are formed in a T-shaped cross section.
c and 11c are fixed. Each brake shoe 10,
Numerals 11 are disposed on the back plate 20 so as to face each other, and are held on the back plate 20 by shoe holding mechanisms each including a known leaf spring 12 and pins 13.

A pair of service brake actuators 30, 31 having an anchor mechanism are provided opposite to each other between adjacent ends of the pair of brake shoes 10, 11.

Each service brake actuator 3
0 and 31 have two pistons 32 and 33 respectively. Each of the brake shoes 10, 11 has its adjacent end engaged with the piston 32, 33 of each of the service brake actuators 30, 31, respectively.
Return springs 14, 14 stretched between 0, 11
Is urged in the diameter reducing direction by the spring force.

An intermediate portion of a pivot lever 40 superimposed on the shoe web 10a of the left brake shoe 10 is pivotally connected to the center thereof, and an operation lever 50 is pinned on the upper portion of the shoe web 11a of the right brake shoe 11. It is pivotally mounted by 51.

The upper part of the pivot lever 40 and the operation lever 5
The first and second struts 60 and 70 are disposed substantially in parallel between the middle part of the brake lever 0 and between the lower part of the pivot lever 40 and the brake shoe 11 on the right side. The present invention facilitates the incorporation of the parking brake mechanism by forming a link mechanism by combining the pivot lever 40 with the pair of struts 60, 70. Hereinafter, each part will be described in detail.

<B> Pivot Structure of Pivot Lever As shown in FIG. 2, a hollow projection 41 integrally formed by press at an intermediate portion of the pivot lever 40 is formed in the shoe web 10a of the left brake shoe 10. The tip of the pin 13 which is rotatably supported by the hole 10d and is loosely fitted into the projection 41 from the back plate 20 side is hooked on the leaf spring 12 mounted on the pivot lever 40, and the brake is applied. The shoe 10 is held on the back plate 20 and the pivot lever 40 is moved to the shoe web 1 of the brake shoe 10.
0a.

The pivotal structure of the left brake shoe 10 and the pivot lever 40 is such that a hollow projection is formed on the shoe web 10.
On the a side, a hole may be provided on the pivot lever 40 side,
Instead of the pivot structure of the protrusion and the hole, a separate flanged sleeve (not shown) may be used for pivotal support. Further, a shoe hold mechanism composed of the leaf spring 12 and the pin 13 is provided at another location, and the hollow projection 41 is formed as a bottomed projection or pivotally supported using a known separate pin. It may be.

<C> Service brake actuators The service brake actuators 30 and 31 have basically the same structure, and one of them will be described with reference to FIG.

The cylinder hole 30 of the cylinder body 30a
A pair of pistons 32 and 33 are slidably housed in b and 30c, and by supplying and discharging fluid to and from a fluid chamber 30d between the pistons 32 and 33, a flow path is formed so that both pistons 32 and 33 move forward and backward. Is formed. One piston 32 is composed of a main body 32a and a head 32b, and both are fitted so as to be relatively rotatable by an external force.

The service brake actuator 30 includes a piston 32 and a partition wall 30e behind the cylinder hole 30b.
Adjustment shaft 34 and drive ring 3 incorporated between
5, an automatic shoe gap adjusting device for performing an exponential incremental type adjusting operation constituted by a spring 36 and the like is incorporated. The adjusting operation will be described later.

As described above, the automatic shoe gap adjusting device has an adjusting shaft 34 which is a bolt member as a main component.
The adjusting shaft 34 has a rear end supported by the partition 30e and has an anchoring mechanism for the piston 32.
On the other hand, the rear end of the piston 33 is supported by the partition 30e to constitute an anchor mechanism.

<D> First Strut As shown in FIGS. 1 and 4, the first strut 60 has a one-shot type automatic parking stroke adjusting function, and includes a plate 61, a bell crank lever 62 and two springs 63. , 64 and pins 65.

Notch groove 61 formed on the right side of plate 61
The right shoe web 11a and an operation lever 50 to be described later are accommodated in the bottom of the notch groove 61a.
It is in contact with 0.

In the middle of the plate 61, small teeth 61
b is engraved. The bell crank lever 62 has an intermediate portion rotatably supported on the left side of the plate 61 by a pin 65 with a pin 65.
Is movable along the plate surface in the longitudinal direction of the plate 61 in the left long hole of the plate 61 together with the pin 65.
The small teeth 62b engraved on the outer periphery of one fan-shaped arm 62a of the bell crank lever 62
With the tiny teeth 61b.

A cam arm 62c having a cam surface is loosely fitted in a rectangular hole 42 formed in the upper part (one side) of the pivot lever 40 in FIG.

The anti-rattle spring 63 is stretched between the right shoe web 11a and the plate 61, and the spring 64 is stretched between the plate 61 and the pin 65.

In FIG. 1, the anti-rattle spring 6
3 applies a counterclockwise urging force to the operation lever 50 via the first strut 60 with the pin 51 serving as a pivot portion with the shoe web 11a as a fulcrum.
And the vibration of each member of the first strut 60 is also helped. The mounting load of the two springs 63 and 64 is set larger for the anti-rattle spring 63.

<E> Second Strut As shown in FIGS. 1 and 5, a second strut 70 is suspended between the lower part of the pivot lever 40 in FIG. 1 and the lower part of the right brake shoe 11 in FIG. 1. Have been. The second strut 70 has a notch groove 7 formed on the left side thereof.
0a, the left shoe web 10a and the pivot lever 40
And the bottom of the notch groove 70 a is in contact with the pivot lever 40. The bottom of the cutout groove 70b formed on the right side of the second strut 70 has the right shoe web 1
1a.

A spring 71 stretched between the pivot lever 40 and the right shoe web 11a is used to
By biasing 0, 70 toward the shoe web 11a, it also helps prevent vibration of the pivot lever 40 and each member of the second strut 70.

<F> Parking Brake Actuator The operation lever 50 serving as the parking brake actuator is located on the path of the link mechanism composed of the pivot lever 40 and the pair of struts 60, 70 (the right side of the first strut 60 in FIG. 1). One). In this example, a case where a so-called forward pull type operation lever 50 is arranged between the first strut 60 and the right brake shoe 11 will be described.

That is, in FIG. 1, the operating lever 50 is rotatably supported by the right brake shoe 11 with a pin 51, and the stopper 52 formed on a part of the operating lever 50 is connected to the right shoe web. The return position of the lever 50 is regulated by abutting on the inner end face of the lever 11a. By pulling a control cable (not shown) connected to the free end of the operation lever 50 to the left in the drawing, the first strut 6
The pair of brake shoes 10 and 11 expands in cooperation with the link mechanism of the pivot lever 40 and the second strut 70.

[0039]

Next, the operation of the drum brake device will be described.

<A> Service brake operation In FIG.
Pressure is applied to 0, 31 and return springs 14, 14
When the upper and lower ends of both brake shoes 10, 11 are expanded against the force, the linings 10c, 11c frictionally engage with a brake drum (not shown). Now, when the brake drum is rotating in the clockwise direction, the adjusting shaft 3 on both pistons 32, 32 having a built-in automatic shoe gap adjusting mechanism is provided.
4 and 34 function as anchors, and when the brake drum is rotating counterclockwise, the other two pistons 3
3, 33 function as anchors. At this time, the two brake shoes 10 and 11 have self-servo characteristics regardless of the rotation direction of the brake drum.
Acts as a leading brake.

<B> Parking Brake Operation When the free end of the operating lever 50 shown in FIG. 1 is pulled leftward in the drawing, the operating lever 50 rotates the first strut 60 to the left while rotating clockwise about the pin 51 as a fulcrum. Move. The acting force on the first strut 60 is transmitted to the upper part of the pivot lever 40, and the pivot lever 40 is moved to the shoe web 10a.
Is rotated in the counterclockwise direction with the hollow projection 41 serving as a pivot portion as a fulcrum.

The lower portion of the pivot lever 40 acts on the lower portion of the right brake shoe 11 via the second strut 70. At the same time, the operating lever 50 is
Brake shoe 1 with pin 51 as a fulcrum via pin 51
1 to give an action force to the upper part.

Accordingly, the left brake shoe 10 is moved leftward by the action force from the pivot 10d with the pivot lever 40 to frictionally engage with the brake drum, and the right brake shoe 11 is It moves to the right by the action force from 51 and frictionally engages with the brake drum. The subsequent operation of both brake shoes 10 and 11 is the same as the operation of the service brake, and a description thereof will be omitted.

<C> Automatic shoe clearance adjusting operation The automatic shoe clearance adjusting mechanism is described in detail in Japanese Patent Application Laid-Open No. 7-208518 filed earlier by the present applicant. Next, only one brake shoe 10 will be briefly described.

Now, the lining 10 of the brake shoe 10
When the service brake is operated while the brake drum (not shown) is rotating in the counterclockwise direction, the piston 32 and the adjustment shaft 34 irreversibly screwed to the piston 32 are worn.
The drive ring 35 is reversibly screw-connected to the adjustment shaft 34 with a gap in the axial direction.
When the gap exceeds the gap, the idle rotation occurs due to the urging force of the spring 36. Here, the “irreversible screw connection” means the piston 3
When a thrust in the axial direction acts on one member of the adjusting shaft 34 and the adjusting shaft 34, it means a "screw connection" that normally does not cause relative rotation of the two members. In addition, “reversible screw connection” means “screw connection” in which when an axial thrust acts on one member of the adjustment shaft 34 and the drive ring 35, the other member is rotated, and the reverse relationship is also established. I do.

When the brake is released, the piston 32, the adjusting shaft 34, etc., retreat. At this time, when the clearance exceeds the gap of the reversible screw coupling portion, the drive ring 35 is clutch-engaged with the partition 30e to prevent rotation, and thereafter, the adjusting shaft 34 rotates and the rear end is clutch-engaged with the partition 30e. Retreat until. The rotation of the adjustment shaft 34 causes the main body 32a of the piston 32 to screw out, and the gap between the brake drum and the brake shoe 10 is automatically adjusted.

As can be understood from the adjusting operation described above,
A shoe having a so-called exponential incremental type adjusting action as shown in the diagram of FIG. 6, in which the adjustment amount is large when the gap between the brake drum and the brake shoe 10 is large, and the adjustment amount is small when the gap is small. Since it operates as an automatic gap adjustment device, it is a type that is effective in preventing overadjustment even under severe use conditions.
In addition, since the automatic adjustment mechanism is built in the fluid chamber 30d, it is particularly suitable for a dump truck or a mixer truck often used in a bad environment.

<D> Automatic Parking Stroke Adjustment Operation The operation will be described with reference to FIGS. Now, brake shoes 10,
When the service brake is actuated when the linings 10c, 11c of the motor 11 are worn, the first strut 60 and the second strut 70 move rightward integrally with the brake shoe 11 and the operating lever 50 by the biasing force of the springs 63 and 71, and pivot. The lever 40 rotates counterclockwise in FIG. 1 around a hollow projection 41 as a pivot portion.

Accordingly, the bell crank lever 62 moves rightward integrally with the plate 61, and the upper part of the pivot lever 40 moves leftward by an amount obtained by adding the amount of rotation and the movement equivalent of the brake shoe 10, and as a result, the bell crank lever The lever 62 is rotated clockwise in FIG. 4 using the pin 65 as a fulcrum, and the meshing state of the notched teeth 61b of the plate 61 and the notched teeth 62b of the bell crank lever 62 meshing therewith is displaced, so that the entire length of the first strut 60 is changed. Is automatically extended, and the stroke of the operation lever 50 is always kept constant.

As can be understood from the adjusting operation described above,
Regardless of the size of the gap between the brake drum and the brake shoes 10, 11, a predetermined shoe gap value can be obtained by a single service brake operation, and it operates as a so-called one-shot type shown in the diagram of FIG. Is easy.
In addition, since the first strut 60 and the second strut 70 can be formed of plate-like members, the space at the center of the brake can be designed to be large, and the brake can be easily applied to a small brake.

It should be noted that the brake shoes 10, 11 when the brake is not operated are fixedly supported by the piston 33 as an anchor mechanism and the adjustment shaft 34 provided in the service brake actuators 30, 31, respectively. Setting an adjustment convergence value of the automatic shoe gap adjusting device and the automatic parking stroke adjusting device. As a result, the brake shoe 1 on a rough road
Dragging and biting of 0 and 11 can be reliably prevented.

[0052]

Second Embodiment Another embodiment will be described below. In the description, the same parts as those in the first embodiment are given the same reference numerals and the detailed description thereof will be omitted.

In the first embodiment described above, the case where the automatic parking stroke adjusting device is provided to the first strut 60 may be incorporated in the second strut 70 as shown in FIGS.

This embodiment shows a case in which an automatic parking stroke adjusting device for performing a linear incremental type (see the diagram shown in FIG. 6) automatic parking stroke adjusting operation is applied to the second strut 70. According to this example, the amount of one adjustment can be set small, so that the linings 10c, 1
The fluctuation of the stroke of the operation lever 50 due to the wear of 1c is suppressed to be small, and the operation feeling of the driver is improved. The second strut 70 includes an adjustment bolt 72, an adjustment nut 73, and an adjustment sleeve 74. Adjustment teeth 72a are integrally formed in the intermediate portion of the adjustment bolt 72, and a left male screw shaft portion 72b is formed.
Are screwed into the adjustment nut 73, and the right shaft portion 72c is rotatably fitted in the adjustment sleeve 74.

The outer ends of the adjusting nut 73 and the adjusting sleeve 74 have a plate-like shape.
3a and 74a are formed. The lower part of the pivot lever 40 in FIG. 7 abuts the bottom of the left cutout groove 73a of the adjust nut 73, and the left shoe web 10a is accommodated therein. The bottom of the right cutout groove 74a of the adjust sleeve 74 is engaged with the inner end surface of the right shoe web 11a with a slight gap.

The adjustment lever 75 is rotatably supported on the right shoe web 11a by a pin 76. The adjustment spring 77 is stretched between the adjustment lever 75 and the right shoe web 11a, and in FIG. 7, applies a counterclockwise urging force to the adjustment lever 75 with the pin 76 as a fulcrum. Lever 75
One arm 75a is in contact with the end face of the adjusting sleeve 74, and the other arm 75b is engaged with the adjusting teeth 72a.

The urging force is such that the second strut 70 is moved to the left, the pivot lever 40 is moved clockwise in FIG. 7 around the hollow projection 41 as a pivot, and the first strut 60 is moved to the right. 50 is transmitted counterclockwise in FIG. 7 with the pin 51 serving as a pivot portion as a fulcrum,
It also has a vibration preventing function of the link mechanism constituted by these.

Now, the linings 10c, 11c of both brake shoes 10, 11 are worn, and the amount of expansion of both brake shoes 10, 11 during service braking is increased.
The other arm 7 having the pin 76 of the adjustment lever 75 as a fulcrum
When the rotation amount of 5b exceeds one adjustment tooth 72a, the adjustment bolt 72 is rotated to extend the entire length of the second strut 70 by one tooth, thereby keeping the stroke of the operation lever 50 constant.

[0059]

Third Embodiment FIG. 9 shows another example in which an automatic shoe gap adjusting device for performing a linear incremental type automatic shoe gap adjusting operation disclosed in, for example, Japanese Patent Application Laid-Open No. 8-31702 is applied to a service brake actuator 80. Is shown.

The automatic shoe gap adjusting device includes an adjusting nut 84 having an adjusting tooth wheel 83 rotatably inserted into a piston 82 in a cylinder body 81 and fixed to an outer end thereof.
The shoe web 10a is screwed onto the adjustment nut 84 and
Adjustment bolt 85 having a notch groove for receiving the same, and an adjustment claw 87 rotatably supported by a support shaft 86 outside the cylinder body 81 with a support shaft 86 and engaging with an adjustment tooth wheel 83. 88, a connecting member 89 for transmitting the advance of the piston 82 to the adjusting lever 88, a connecting member 89 and the adjusting lever 88.
An adjusting spring 90 is provided between the adjusting lever 88 and the adjusting claw 87 of the adjusting lever 88 and the teeth of the adjusting tooth wheel 83 constitute a ratchet mechanism that allows rotation in only one direction. In the present embodiment, the flange mechanism of the piston 82 is in contact with the left end surface of the cylinder body 81 to constitute an anchor mechanism.

In the above-described configuration, when the lining 10 c is worn out during the service brake operation and the gap between the lining 10 c and the brake drum has reached a predetermined value, the connecting member 89 integral with the piston 82 advances, and the tension of the adjusting spring 90 causes A clockwise urging force about the support shaft 86 is applied to the adjustment lever 88, so that the adjustment claw 87 rotates one tooth of the adjustment tooth wheel 83. Thereby, the adjusting bolt 85 is screwed out from the adjusting nut 84 to automatically adjust the shoe gap.

The case where the shoe gap is automatically adjusted when the piston 82 advances has been described above.
The same automatic adjustment may be performed at the time of retreat.

[0063]

Fourth Embodiment FIGS. 10 to 12 show another application example in which a cross-pull type is adopted as a parking brake actuator.

The plate 6 corresponding to the first strut 60
The groove bottom of the notch groove 61c formed at the left end of 1 is in contact with the upper part of the pivot lever 40 in FIG.

As shown in FIG. 11, an operation lever 50 having a substantially L-shape is rotatably supported on the right end of a plate 61 by a pin 51, and a finger 53 of the operation lever 50 is connected to a right shoe. It is in contact with the inner end surface of the web 11a.

The other arm 54 of the operation lever 50 penetrates the hole 21 of the back plate 20 and projects outside the brake. The return position of the operation lever 50 is regulated by a part of the other arm 54 abutting on the back plate 20.

Then, the other arm 54 is connected via a control cable (not shown) connected to the cable connection hole 55.
The pair of brake shoes 10 and 11 can be opened by pulling in the direction A substantially perpendicular to the back plate 20. That is, the finger 5 of the operation lever 50
At 3, the right brake shoe 11 is pushed outward, and the plate 61 is moved leftward via the pin 51 by the reaction force. The subsequent operation is described in the second embodiment.
The description is omitted because it is the same as the above.

FIG. 12 shows another example in which the operating lever 50 is provided at the left end of the plate 61 shown in FIG. When the operation lever 50 is provided at the left end of the plate 61, the finger 53 of the operation lever 50 is brought into contact with the upper part of the pivot lever 40 in FIG. 10, but the finger 53 is pivoted as shown in the figure. In addition to being inserted through a rectangular hole 42 formed at the top of FIG.
A notch groove may be formed in the upper part of the groove 0 so as to abut on the groove bottom.

[0069]

[Fifth Embodiment] The present invention is not limited to the above-described embodiments. For example, the automatic adjustment of the shoe gap and the automatic adjustment of the parking stroke of the various adjustment operation types described above may be appropriately combined. Can be.

Further, the automatic parking stroke adjusting device may be of a type that performs adjustment when the parking brake is operated.

Various changes can be made such that the position of the operation lever 50 is reversed upside down of the brake and provided on the lower second strut 70 side.

[0072]

According to the present invention, the following effects can be obtained as apparent from the above-described configuration. <A> Due to the problem of securing the installation space, the duo-to-leading type drum brake device with a built-in parking brake mechanism has been limited to large-diameter brakes, and has been difficult for small-diameter brakes. According to the present invention, the parking brake actuator is disposed on the path of the link mechanism combining the pivot lever and the first and second struts, so that a brake device having a built-in parking brake mechanism can be easily designed even for a small diameter brake. can do. <B> The number of components of the parking brake mechanism is small, and the structure can be simplified. Thus, the weight and cost of the device can be reduced. <C> Since parts are not concentrated in the center of the brake, it is easy to attach a parking brake automatic stroke adjusting device, and even if the lining is worn, the stroke does not change and the operation feeling of the parking brake is improved. <D> Set the convergence adjustment values of the automatic shoe clearance adjustment device and the automatic parking stroke adjustment device so that the adjacent ends of both brake shoes are fixedly supported by the service brake actuator anchors when the brake is not operated. As a result, dragging and biting of the brake shoe during traveling can be reliably prevented. <E> The incremental type or one-shot type can be applied to the adjustment operation of the automatic shoe gap adjusting device, and the incremental type or one-shot type can also be applied to the adjusting operation of the automatic stroke adjustment device. , Parts can be shared. <F> Excellent in assemblability and disassembly of equipment.

[Brief description of the drawings]

FIG. 1 is a plan view of a duo-to-leading type drum brake device according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 1;

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

FIG. 5 is a sectional view taken along line VV of FIG. 1;

FIG. 6 is an adjustment operation diagram of each type showing the relationship between the number of braking operations and the adjustment amount.

FIG. 7 shows a duo according to a second embodiment of the present invention in which an automatic parking stroke adjusting device is incorporated in a second strut.
Top view of two-leading drum brake device

8 is a sectional view taken along line VIII-VIII of FIG. 7;

FIG. 9 is an explanatory view according to Embodiment 3 of the present invention;
Is a plan view of a service brake actuator equipped with a linear incremental type shoe gap automatic adjustment device,
(B) is a front view with a part thereof broken.

FIG. 10 is an explanatory view according to Embodiment 4 of the present invention, and is a plan view in which a part of a duo-to-leading type drum brake device employing a cross pull type as a parking brake actuator is omitted.

11 is a sectional view taken along line XI-XI in FIG.

FIG. 12 is an explanatory view of a modification of FIG. 11 in which an operation lever is provided at a left end portion of a plate.

FIG. 13 is a plan view of a conventional duo-to-leading drum brake device.

[Explanation of symbols]

 10, 11 Brake shoe 10a, 11a Shoe web 10b, 11b Shoe rim 10c, 11c Lining 10d Hole 12 Leaf spring 13 Pin 14 Return spring 20 Back plate 21 Hole 30, 31 Service brake actuator 30a Cylinder body 30b Cylinder hole 30c Cylinder hole 30d Fluid chamber 30e Partition wall 32, 33 Piston 32a Main body 32b Head 34 Adjustment shaft 35 Drive ring 36 Spring 40 Pivot lever 41 Hollow projection 42 Rectangular hole 50 Operation lever 51 Pin 52 Stopper 53 Finger part 54 Other arm 55 Cable connection hole 60 First 1 strut 61 plate 61a notch groove 61b notched tooth 61c notched groove 62 bell crank lever 62a arm 62b notched tooth 62c cam arm 3 Anti-rattle spring 64 Spring 65 Pin 70 Second strut 70a, 70b Notch groove 71 Spring 72 Adjust bolt 72a Adjusting tooth 72b Male screw shaft part 72c Shaft part 73 Adjust nut 73a Notch groove 74 Adjust sleeve 74a Notch groove 75 Adjust lever 75a Arm 75b Other arm 76 Pin 77 Adjust spring 80 Service brake actuator 81 Cylinder body 82 Piston 83 Adjusting tooth wheel 84 Adjusting nut 85 Adjusting bolt 86 Support shaft 87 Adjusting claw 88 Adjusting lever 89 Connecting member 90 Adjusting spring

Claims (12)

[Claims] 1. A duo comprising a pair of brake shoes disposed opposite to each other and a pair of service brake actuators disposed opposite each other between adjacent ends of the two brake shoes. In a two-leading type drum brake device, a pivot lever is pivotally attached to an intermediate portion of one of the brake shoes so as to be rotatable, and a pair of the pivot levers is disposed substantially parallel to one and the other and the other brake shoe. A strut is provided, and a parking brake actuator for expanding a pair of brake shoes in cooperation with the link mechanism by operating a parking brake is provided on a path of a link mechanism including the pivot lever and the pair of struts. The brake drum expands in response to excessive opening of each brake shoe during service braking, An automatic shoe gap adjusting device for automatically adjusting the gap with each brake shoe is provided in the pair of service brake actuators, and at least one of the pair of struts responds to the excessive expansion of both brake shoes. And a parking brake automatic adjusting device for automatically adjusting the stroke amount of the parking brake actuator, the duo-to-leading type drum brake device. 2. The adjustment convergence of the automatic shoe gap adjusting device and the automatic parking stroke adjusting device according to claim 1, wherein when the brake is not operated, each adjacent end of both brake shoes is supported by an anchor of a service brake actuator. A duo-to-leading type drum brake device, characterized in that a value is set. 3. An automatic shoe clearance adjusting device according to claim 1, further comprising a screw coupling mechanism comprising a bolt member and a nut member, which is incorporated in a cylinder of a service brake actuator. Duo-to-leading drum brake system. 4. The duo-to-leading device according to claim 3, wherein the screw connection mechanism comprising the bolt member and the nut member is a reversible screw connection, and the automatic shoe gap adjusting operation is an exponential incremental type. Drum brake device. 5. The automatic shoe clearance adjusting device according to claim 1, further comprising a ratchet mechanism including a lever member and a gear member, wherein the lever member is externally mounted on a cylinder body of the service brake actuator. Features a duo-to-leading drum brake device. 6. The duo-to-leading type drum brake device according to claim 5, wherein the automatic shoe clearance adjusting operation of the automatic shoe clearance adjusting device is of a linear incremental type. 7. The automatic parking stroke adjusting device according to claim 1, wherein the automatic parking stroke adjusting device includes a screw coupling mechanism including a bolt member and a nut member, and the automatic parking stroke adjusting operation is a linear incremental type. Features a duo-to-leading drum brake device. 8. The automatic parking stroke adjusting device according to claim 1, further comprising a tooth formed on a bell crank lever and an element engaging with the tooth.
A duo-to-leading drum brake device wherein the parking stroke automatic adjustment operation is a one-shot type. 9. The duo-to-leading type drum brake device according to claim 1, wherein the parking brake actuator is of a forward pull type. 10. The duo-to-leading type drum brake device according to claim 1, wherein the parking brake actuator is of a cross-pull type. 11. The projection according to claim 1, wherein one of the pivot lever and the intermediate portion of the shoe web of the brake shoe is provided with a projection integrally formed by pressing. Characterized in that the drum brake device is rotatably supported by a hole formed in the other member or the other member. 12. The duo-to-two according to claim 11, wherein the projection is formed into a hollow shape by burring by a press, and a pin for holding a brake shoe is loosely inserted through the hollow. -Leading drum brake device.