WO2018155654A1

WO2018155654A1 - Drum brake device

Info

Publication number: WO2018155654A1
Application number: PCT/JP2018/006818
Authority: WO
Inventors: 利史前原; 吉川　和宏
Original assignee: 曙ブレーキ工業株式会社
Priority date: 2017-02-23
Filing date: 2018-02-23
Publication date: 2018-08-30
Also published as: JP2018135988A

Abstract

This drum brake device (100) is provided with: first and second brake shoes (17, 19); a link lever (42) rotatably supported by a first web (23) of the first brake shoe (17); first and second struts (39, 67) arranged parallelly between both the pivoting ends of the link lever (42) and the opposite ends of a second web (25) of the second brake shoe (19); and a lever (49) having a rotating base (51) rotatably supported at one end of the first strut (39). The rotating base (51) is disposed near the second brake shoe (19), and a lever input section (53) is disposed near the first brake shoe (17).

Description

Drum brake device

The present invention relates to a drum brake device.

A drum brake device having a parking brake mechanism (dual-to-leading parking brake mechanism) in which a pair of brake shoes act as a leading shoe and operate regardless of the rotation direction of the brake drum is known (see Patent Document 1).

This type of dual-to-leading parking brake mechanism shown in FIG. 10 is a dual-to-leading drum brake in which a pair of service brake actuators 530 are provided opposite to each other between adjacent ends of a pair of

brake shoes

510 and 511. Built in the device 501. A pivot lever (link lever) 540 is pivotally attached to an intermediate portion of the shoe web 510a of one brake shoe 510 so as to be pivotable. The pivot lever 540 is parallel to one and the other brake shoes 511. A first strut 560 and a second strut (not shown) are disposed in the front. A cross-pull type parking brake that expands the pair of

brake shoes

510 and 511 in cooperation with the link mechanism by the operation of the parking brake on the path of the link mechanism constituted by the pivot lever 540 and the pair of struts. The actuator is provided.

In the parking brake actuator, as shown in FIG. 11, the groove bottom of the notch groove 560 c formed at the left end of the first strut 560 is in contact with the upper portion of the pivot lever 540.
An operating lever (lever) 550 having a substantially L-shape is pivotally supported by a pin 551 at the right end of the first strut 560 so that the finger-like portion 553 of the operating lever 550 is located on the right shoe web 511a. It is in contact with the inner end face of.

The other arm 554 of the operation lever 550 passes through the hole 521 of the back plate (backing plate) 520 and projects out of the brake. The return position of the operation lever 550 is restricted by a part of the other arm 554 coming into contact with the back plate 520.
The pair of

brake shoes

510 and 511 can be expanded by pulling the other arm 554 in the direction A substantially perpendicular to the back plate 520 via a control cable (not shown) connected to the cable connection hole 555. It has become. Such a cross-pull type parking brake actuator can greatly change the shape of the back plate because the drive mechanism (motor gear unit) for electrifying the parking brake mechanism can be installed in a direction substantially orthogonal to the axle. In addition, the parking brake can be electrified.

According to such a dual two-leading parking brake mechanism, the brake device is not limited to a large dual two-leading drum brake device, and even a small dual two-leading drum brake device can easily be equipped with a parking brake mechanism. Can be designed to

Japanese Unexamined Patent Publication No. 2001-27266

However, in the conventional dual two-reading parking brake mechanism, the operation lever 550 penetrates the back plate 520 and protrudes out of the brake. Therefore, the operation lever 550 is set to be small in order to prevent interference with the brake mounting portion (hub) of the vehicle. Further, in order to suppress the variation in lever ratio, the lever ratio is set to be lower than the forward pull type (small lever ratio). As a result, in the cross-pull type parking brake actuator, the lever pulling force is increased compared to the forward pull type, and the reaction force input to the back plate 520 is increased. For this reason, there is a problem that the back plate 520 needs to have high strength and a large drive mechanism (motor gear unit) is required when the parking brake mechanism is electrified.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a drum brake device that can increase the lever ratio of a lever that expands a pair of brake shoes and can reduce the force for rotating the lever. There is.

The above object of the present invention is achieved by the following configuration.
(1) A pair of brake shoes that are arranged to expand on a surface parallel to the backing plate so as to face the inner peripheral surface of the brake drum, and are rotatably supported by an intermediate portion of the web of one of the brake shoes. Link lever,
A first strut and a second strut disposed in parallel between one swing end and the other swing end of the link lever and both ends of the web of the other brake shoe;
The rotating base portion rotatably supported by one end portion of the first strut on the other brake shoe side is rotated, so that the pressing portion presses one end of the web in the other brake shoe and the pair of pairs A lever for expanding the brake shoe,
A drum brake device in which the rotation base is disposed in the vicinity of the other brake shoe, and a lever input portion extending from the rotation base is disposed in the vicinity of the one brake shoe.

According to the drum brake device having the above-described configuration (1), the rotation base portion of the lever rotatably supported on the one end portion of the first strut is disposed in the vicinity of the other brake shoe, and the lever input portion is in the vicinity of the one brake shoe. Placed in. Therefore, the lever itself can be lengthened, and the distance from the rotation base to the lever input portion can be increased, so that the lever ratio can be increased.

(2) The drum brake device according to (1) above,
A drum brake device in which the lever input portion is disposed between the web and the backing plate on the one brake shoe side.

According to the drum brake device having the configuration (2), since the lever input portion is disposed between the web and the backing plate on one brake shoe side, the lever interferes with the inner edge of the web. Is avoided. Therefore, the lever from which the interference with the inner edge portion is avoided can move outward in the radial direction from the wheel rotation axis side. Accordingly, the drive position of the drive member connected to the lever input portion of the lever can also be moved radially outward from the rotation axis side of the wheel, so that the drive member can be easily laid out. As a result, a drive mechanism such as a motor gear unit connected to the drive member can also move radially outward from the wheel rotation axis side, and interference with other members is less likely to occur. Further, the lever itself can be further lengthened, and the distance from the rotation base portion to the lever input portion can be further increased, so that the lever ratio can be further increased.

(3) The drum brake device according to (1) or (2) above,
The drum brake device, wherein the second strut includes an automatic length adjusting mechanism for automatically adjusting a stroke amount of the lever.

According to the drum brake device having the configuration of (3) above, when the lining wears and the standby positions of the pair of brake shoes at the time of non-braking are separated, the length of the second strut is automatically adjusted by the length automatic adjustment mechanism. Stretched. As a result, the stroke of the lever is maintained substantially constant, so that the stroke does not change even if the lining wears, and the operation feeling of the parking brake is improved.

(4) The drum brake device according to any one of (1) to (3) above,
A drum brake device in which the lever input unit is driven by a motor gear unit.

According to the drum brake device configured as described in (4) above, the lever input unit can be driven by the motor gear unit to rotate the lever, and the parking brake can be electrified.

(5) The drum brake device according to any one of (1) to (4) above,
The lever and the first strut arranged side by side are a drum brake device in which the rotating base and the other end of the first strut are arranged on the same plane perpendicular to the brake center axis.

According to the drum brake device having the configuration of (5) above, the lever rotation base and the other end of the first strut are disposed so as to be on the same plane perpendicular to the brake center axis. On the same plane perpendicular to the central axis of the brake, the contact portion between the pressing portion of the first brake strut and the web of the other brake shoe, and the contact portion of the other end portion of the first strut and one swinging end of the link lever. Are arranged opposite to each other. Therefore, when the lever rotates to expand the pair of brake shoes, the expanding force of the lever acts on the pair of brake shoes on the same straight line, thereby enabling stable parking operation.

According to the drum brake device according to the present invention, the lever ratio of the lever for expanding the pair of brake shoes can be increased, and the force for rotating the lever can be reduced.

The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is a front view of a drum brake device according to a first embodiment of the present invention. FIG. 2 is a bottom view of the drum brake device shown in FIG. FIG. 3 is a perspective view of the drum brake device shown in FIG. 4A is a perspective view of the brake shoe, the link lever, the first and second struts, and the lever shown in FIG. 3 as viewed from the bottom side of the front, and FIG. 4B is the perspective view of FIG. It is the perspective view which looked at a) from the upper surface side of the back. 5A is a perspective view of the link lever, the first and second struts, and the lever shown in FIG. 4A viewed from the bottom side of the front, and FIG. 5B is the perspective view of FIG. It is the perspective view which looked at (a) from the upper surface side of the back. FIGS. 6A and 6B are a front view and a bottom view of the link lever, the first and second struts, and the lever shown in FIG. FIG. 7 is an exploded perspective view of the link lever, first and second struts, and lever shown in FIG. FIG. 8 is a front view of a drum brake device according to the second embodiment of the present invention. 9 is a cross-sectional view taken along the line IX-IX in FIG. FIG. 10 is a front view in which a part of a conventional drum brake device is omitted. 11 is a cross-sectional view taken along the line XI-XI in FIG.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
As shown in FIGS. 1 to 3, the drum brake device 100 according to the first embodiment of the present invention is integrally fixed to the vehicle body in a posture in which the backing plate 11 is substantially perpendicular to the wheel rotation axis 13. Is done. The backing plate 11 is formed with a predetermined strength by raising an outer peripheral edge of a circular substrate made of a thick metal plate as a peripheral wall. As shown in FIG. 2, a motor gear unit 15 for electrifying the parking brake is provided on the surface of the backing plate 11 on the vehicle side. A pair of first brake shoes 17 and second brake shoes 19 each having an arc shape are disposed on the backing plate 11 along the outer peripheral edge on the vehicle front-rear direction side (left-right direction side in FIG. 1).

As shown in FIGS. 4A and 4B, the first brake shoe 17 and the second brake shoe 19 disposed on the backing plate 11 are arranged on the inner peripheral side of the back plate 21 and the first web 23 and the second brake shoe 19, respectively. The second web 25 is fixed, and the lining 27 is fixed to the outer peripheral side of the back plate 21. The first web 23 and the second web 25 are opposed to each other across a diameter of a virtual circle (not shown) centered on the wheel rotation axis 13 perpendicular to the backing plate 11, and are arcuate on a plane parallel to the backing plate 11. Is formed. In the present specification, an extension line of the above-described diameter sandwiched between the first web 23 and the second web 25 is referred to as a brake center shaft 29 (see FIG. 1).

The first brake shoe 17 and the second brake shoe 19 are held on the backing plate 11 by the shoe hold-down device 31 so as to be spreadable. The first brake shoe 17 and the second brake shoe 19 are disposed so as to be able to expand on a plane parallel to the backing plate 11 so as to face the inner peripheral surface of the brake drum 30 with the brake center shaft 29 interposed therebetween.

As shown in FIGS. 1 and 3, a pair of

wheel cylinders

43 and 44 are attached to the backing plate 11 so as to face each other between the adjacent ends of the first brake shoe 17 and the second brake shoe 19. . Each

wheel cylinder

43, 44 incorporates a first piston 55 and a second piston, respectively. The first brake shoes 17 and the second brake shoes 19 have their adjacent ends engaged with the first piston 55 and the second piston of the

wheel cylinders

43 and 44, respectively. The return springs 37 and 41 provided are biased in the direction of diameter reduction by the spring force.

The pair of

wheel cylinders

43 and 44 push the two end portions away from each other by the first piston 55 and the second piston, respectively, to expand the first brake shoe 17 and the second brake shoe 19. The

wheel cylinders

43 and 44 expand the first brake shoe 17 and the second brake shoe 19 by the first piston 55 and the second piston that advance from both ends during service braking by depressing the foot brake pedal. The first brake shoe 17 and the second brake shoe 19 that have spread are frictionally engaged with the inner peripheral surface of the brake drum 30 to brake it.

Each

wheel cylinder

43, 44 is provided with a known shoe gap automatic adjustment mechanism 60. When the movement amount of the first brake shoe 17 and the second brake shoe 19 during braking is increased due to wear of the lining 27, the shoe gap automatic adjustment mechanism 60 is adjusted from an adjustment nut that is rotatably inserted into the second piston. 52 is screwed out to automatically adjust the shoe gap.

Furthermore, the drum brake device 100 according to the first embodiment is a dual two in which the pair of first brake shoes 17 and the second brake shoes 19 act as leading shoes regardless of the rotation direction of the brake drum 30. A leading parking brake mechanism (hereinafter referred to as a parking brake mechanism) 33 is provided.

4 to 7, the parking brake mechanism 33 includes a link lever 42 rotatably supported by the first web 23 of the first brake shoe (one brake shoe) 17, and an upper end portion of the link lever 42. The first oscillating end 42a and the lower end (the other oscillating end) 42b and the second brake shoe 19 (the other brake shoe) 19 are arranged in parallel between both ends of the second web 25. A first strut 39 and a second strut 67; a lever 49 having a rotation base 51 rotatably supported at one end portion (right end portion in FIG. 1) of the first strut 39 on the second brake shoe 19 side; and a motor gear unit And a drive member 45 driven by the motor 15.

In the strip-shaped link lever 42, an intermediate portion overlapped with the first web 23 of the first brake shoe 17 is rotatably supported by a support pin 46. The support pin 46 has a head, the insertion tip opposite to the head penetrates the first web 23 and the link lever 42, and a retaining ring 48 is attached to the penetration tip that penetrates the through hole 42 c of the link lever 42. Dropout is restricted (see FIG. 4B).

The upper end portion of the second web 25 in the second brake shoe 19 is accommodated in a notch groove 39c formed at one end (right end in FIG. 7) of the first strut 39. The notch groove 39b formed at the other end (the left end in FIG. 7) of the first strut 39 accommodates the upper end portion of the first web 23 and the upper end portion of the link lever 42 in the first brake shoe 17, The upper end portion 42a of the link lever 42 contacts the bottom of the notch groove 39b.

The second strut 67 constitutes an automatic length adjustment mechanism for automatically adjusting the stroke amount (rotation range) of the lever 49, and includes an adjuster socket 69, an adjuster gear 71, an adjuster nut 73, And an adjuster lever 75.
The adjuster gear 71 extends the entire length of the second strut 67 by rotation, and keeps the stroke of the lever 49 constant. One end of the adjuster gear 71 is screwed into an adjuster nut 73, the other end is fitted and inserted into an adjuster socket 69, and a toothed ring 77 is formed at an intermediate portion. The adjuster lever 75 has a claw portion 79 (see FIG. 5B) that engages with the toothed wheel 77, and the adjuster pin 72 is centered when the first brake shoe 17 and the second brake shoe 19 are expanded. Further, the claw portion 79 is configured to come into contact with the toothed ring 77 by rotating in the clockwise direction in FIG.

In the automatic length adjusting operation by the second strut 67, a part of the adjuster lever 75 that is always urged by the tension coil spring 74 in the direction in which the claw portion 79 abuts on the toothed wheel 77 is behind the second brake shoe 19. By abutting on the plate 21, rotation in the clockwise direction in FIG. 4B is regulated around the adjuster pin 72.

When the wear amount of the lining 27 increases, the first brake shoe 17 and the second brake shoe 19 move more than a specified stroke during parking brake, and the back plate 21 of the second brake shoe 19 and a part of the adjuster lever 75 are moved. Since the contact is disengaged, the claw portion 79 of the adjuster lever 75 whose rotation restriction has been released contacts one tooth of the toothed ring 77 and rotates the toothed ring 77 by one tooth. As a result, the second strut 67 extends. Since the second strut 67 has a longer overall length, the second strut 67 follows the variation of the standby positions of the first brake shoe 17 and the second brake shoe 19 during non-braking, and keeps the stroke of the lever 49 constant.

The adjuster socket 69 accommodates the lower end portion of the second web 25 in the second brake shoe 19 in a notch groove 69a formed on the side opposite to the side on which the adjuster gear 71 is inserted (right side in FIG. 7). The The lower end of the second web 25 abuts on the bottom of the notch groove 69a.
The adjuster nut 73 is formed in a notch groove 73a formed on the opposite side (left side in FIG. 7) to the side on which the adjuster gear 71 is screwed, and the lower end portion of the first web 23 in the first brake shoe 17 and the link lever. The lower end portion 42b of the link lever 42 comes into contact with the bottom of the notch groove 73a.

A strip-like lever 49 from which the lever input portion 53 extends from the rotation base portion 51 is juxtaposed so as to overlap the first strut 39, and one end portion of the first strut 39 on the second brake shoe 19 side (FIG. 7). The rotation base 51 is rotatably supported by a lever pin 59 at the middle and right end). The lever pin 59 has a head, the insertion tip opposite to the head penetrates the first strut 39 and the through

holes

39a, 49a of the lever 49 and the washer 62, and a retaining ring 61 is attached to the penetration tip. Dropout is regulated.

The lever 49 moves the first strut 39 to the left via the lever pin 59 on the one hand, and presses the upper end portion of the second brake shoe 19 via the pressing portion 63 on the other hand, thereby a pair of first brake shoes. An expansion mechanism 35 for expanding the 17 and the second brake shoe 19 is configured.

Further, as shown in FIG. 6A, the first strut 39 and the lever 49 are formed by bending the intermediate portion into a crank shape so that the rotation base 51 and the other end of the first strut 39 are braked. They are arranged on the same plane 91 orthogonal to the central axis 29.

As for the lever 49 of the spreading mechanism 35, the rotation base 51 is disposed in the vicinity of the second brake shoe 19, and the lever input portion 53 extending from the rotation base 51 is disposed in the vicinity of the first brake shoe 17 (see FIG. 1). ). The lever input portion 53 is disposed between the first web 23 and the backing plate 11 on the first brake shoe 17 side.

The drive member 45 is formed in a rectangular box shape having a lever insertion opening 65 as shown in FIG. The lever 49 is connected to the driving member 45 in an engaged state when the lever input portion 53 is inserted into the lever insertion opening 65 with play. In other words, the lever input portion 53 is directed toward the drive member 45 that applies an external force to the lever input portion 53 in the direction in which the pair of first brake shoes 17 and second brake shoes 19 are expanded (arrow B in FIG. (Contact point with the drive member 45 is movable). Therefore, the tip of the lever input portion 53 has an outer periphery with an arc shape (see FIG. 6B) centered on the center line in the same direction as the lever pin 59. The contact between the lever input portion 53 and the drive member 45 moves on the outer periphery of the arc shape.

That is, the drive member 45 and the lever 49 are not connected by a pin or the like, but are movable (surface contact). As a result, the fluctuation of the standby position when the first brake shoe 17 and the second brake shoe 19 that are automatically adjusted by the shoe clearance automatic adjustment mechanism 60 and the wear of the lining 27 are not changed. Can be absorbed by sliding. Therefore, it is not necessary to arrange a short cable or a clevis that connects the drive shaft of the motor gear unit 15 and the drive member 45.

Next, the operation of the drum brake device 100 according to the first embodiment will be described.
(Service brake operation)
In FIG. 1, when pressure is applied to the

wheel cylinders

43, 44 and the upper and lower ends of the first brake shoe 17 and the second brake shoe 19 are expanded against the return springs 37, 41, the lining 27 is attached to the brake drum 30. Frictionally engages the inner peripheral surface.

When the brake drum 30 rotates in the clockwise direction, the adjustment bolt 52 on the second piston side of the

wheel cylinders

43 and 44 functions as an anchor, and the brake drum 30 rotates in the counterclockwise direction. The first piston 55 functions as an anchor. At this time, the first brake shoe 17 and the second brake shoe 19 have self-servo properties regardless of the rotation direction of the brake drum 30, and thus act as a two-reading brake.

(Parking brake activated)
When the lever input portion 53 of the lever 49 shown in FIG. 6B is pulled downward in the drawing by the drive member 45 driven by the motor gear unit 15, the lever 49 is connected to the first strut 39 via the lever pin 59. Move to the left. The acting force on the first strut 39 is transmitted to the upper end portion 42a of the link lever 42, and rotates the link lever 42 counterclockwise with the support pin 46 as a fulcrum.

The lower end portion 42b of the link lever 42 acts on the lower end portion of the second web 25 in the second brake shoe 19 via the second strut 67. At the same time, the pressing portion 63 of the lever 49 rotates counterclockwise with the lever pin 59 as a fulcrum. An action force is applied to the upper end portion of the second web 25 in the second brake shoe 19 while rotating.

Accordingly, the first brake shoe 17 is moved to the left by the acting force from the link lever 42 via the support pin 46 and is frictionally engaged with the inner peripheral surface of the brake drum 30, and the second brake shoe 19 is the second brake shoe 19. The strut 67 and the lever 49 are moved to the right by the acting force from the pressing portion 63 and frictionally engage with the inner peripheral surface of the brake drum 30. Subsequent operations of the first brake shoe 17 and the second brake shoe 19 are the same as the service brake operation, and thus description thereof is omitted.

Next, the operation of the above configuration will be described.
In the drum brake device 100 having the parking brake mechanism 33 according to the first embodiment, as shown in FIG. 1, the rotation base 51 of the lever 49 rotatably supported by one end of the first strut 39 is the first. The two brake shoes 19 are disposed in the vicinity, and the lever input portion 53 is disposed in the vicinity of the first brake shoe 17. Therefore, the lever itself can be lengthened, and the distance from the rotation base 51 to the lever input portion 53 can be increased, so that the lever ratio can be increased.
Further, since the lever input portion 53 is disposed between the first web 23 and the backing plate 11 on the first brake shoe 17 side, the lever 49 avoids interference with the inner edge of the first web 23. Is done. Therefore, the lever 49 from which the interference with the inner edge portion is avoided can move outward in the radial direction from the wheel rotation axis 13 side. Accordingly, the drive position of the drive member 45 connected to the lever input portion 53 of the lever 49 can also be moved radially outward from the wheel rotation axis 13 side, so that the drive member 45 can be easily laid out. As a result, the motor gear unit 15 connected to the drive member 45 can also move radially outward from the wheel rotation axis 13 side, and interference with other members such as a brake mounting portion (hub) of the vehicle is less likely to occur. Become. Further, the lever 49 itself can be further lengthened, and the distance from the rotation base 51 to the lever input portion 53 can be further increased, so that the lever ratio can be further increased.

Further, in the drum brake device 100 having the parking brake mechanism 33 according to the first embodiment, the standby positions of the pair of the first brake shoe 17 and the second brake shoe 19 at the time of non-braking are separated due to wear of the lining 27. Then, the length of the second strut 67 is automatically extended by the length automatic adjustment mechanism. As a result, the stroke of the lever 49 is maintained substantially constant, so that the stroke does not change even if the lining 27 is worn, and the operation feeling of the parking brake is improved.

Further, in the drum brake device 100 having the parking brake mechanism 33 according to the first embodiment, the driving member 45 is pulled by driving the motor gear unit 15, and the pulling driving member 45 applies a rotational external force to the lever input unit 53. Therefore, the parking brake can be easily electrified. Furthermore, since the lever 49 having a long lever can have a large lever ratio, the lever pulling force does not increase, and the small motor gear unit 15 can be used.

In the drum brake device 100 having the parking brake mechanism 33 according to the first embodiment, as shown in FIG. 6A, the rotation base 51 of the lever 49 and the other end of the first strut 39 Is disposed on the same plane 91 orthogonal to the brake center axis 29, the contact portion between the pressing portion 63 of the lever 49 and the second web 25 in the second brake shoe 19, and the first The contact portion between the other end portion of the strut 39 and the upper end portion 42 a of the link lever 42 is disposed opposite to each other on the same plane 91 orthogonal to the brake center axis 29. Therefore, when the lever 49 rotates to expand the pair of first brake shoes 17 and second brake shoes 19, the expanding force of the lever 49 applies to the pair of first brake shoes 17 and second brake shoes 19. Each acts on the same straight line, and a stable parking operation becomes possible.

[Second Embodiment]
As shown in FIGS. 8 and 9, the drum brake device 200 according to the second embodiment of the present invention, except for the parking brake mechanism 33, includes a backing plate 11, a motor gear unit 15, a drive member 45, a

wheel cylinder

43, 44, return springs 37, 41, and the like are configured in substantially the same manner as the drum brake device 100 according to the first embodiment. Therefore, in the following description, the parking brake mechanism 83 will be mainly described in detail, and the other components of the drum brake device 200 that are equivalent to the drum brake device 100 will be given the same reference numerals and detailed description thereof will be omitted. .

As shown in FIGS. 8 and 9, the parking brake mechanism 83 according to the second embodiment includes a link lever 42 rotatably supported by the first web 23 of the first brake shoe 17, and a link lever 42. The first strut 39 and the second strut 67 disposed in parallel between the upper end portion 42a and the lower end portion 42b and both end portions of the second web 25 in the second brake shoe 19, and the second brake shoe 19 side. A lever 85 on which the rotation base 51 is rotatably supported at one end portion (right end portion in FIG. 8) of one strut 39 and a drive member 45 driven by the motor gear unit 15 are provided.

The lever 85 moves the first strut 39 to the right in FIG. 9 via the lever pin 59 on the one hand and presses the upper end of the second web 25 via the pressing portion 63 on the other hand, thereby The brake shoe 17 and the second brake shoe 19 are expanded.
In the parking brake mechanism 83 according to the second embodiment, the rotation base 51 of the lever 85 is disposed in the vicinity of the second brake shoe 19 and extends from the rotation base 51, as in the first embodiment. The input unit 53 is disposed in the vicinity of the first brake shoe 17 (see FIG. 9).

Further, the lever input portion 53 that extends in parallel to the backing plate 11 from the rotation base 51 and is disposed in the vicinity of the first brake shoe 17 is disposed on the inner side of the first web 23 on the first brake shoe 17 side. ing. The lever insertion opening 65 of the drive member 45 is disposed on the opposite side of the backing plate 11 with respect to the first web 23.

Next, the operation of the above configuration will be described.
In the drum brake device 200 according to the second embodiment, as shown in FIG. 9, the rotation base 51 of the lever 85 that is rotatably supported at one end of the first strut 39 is located near the second brake shoe 19. The lever input portion 53 is disposed in the vicinity of the first brake shoe 17. Therefore, the lever itself can be lengthened, and the distance from the rotation base 51 to the lever input portion 53 can be increased, so that the lever ratio can be increased.
Further, the lever input portion 53 is disposed on the inner side of the first web 23 on the first brake shoe 17 side, and the lever insertion opening 65 of the drive member 45 is on the opposite side of the backing plate 11 with respect to the first web 23. Is arranged. Therefore, the lever input portion 53 can secure a sufficient clearance between the backing plate 11 and the stroke amount of the lever 85 can be increased.

Therefore, according to the

drum brake devices

100 and 200 having the

parking brake mechanisms

33 and 83 according to the above embodiments, the lever ratio of the

levers

49 and 85 for expanding the pair of first and

second brake shoes

17 and 19 is set. The force can be increased, and the force for rotating the

levers

49 and 85 can be reduced.

The present invention is not limited to the above-described embodiments, and the configurations of the embodiments may be combined with each other, or may be modified or applied by those skilled in the art based on the description of the specification and well-known techniques. The invention is intended and is within the scope of seeking protection.

For example, in the above configuration example, the case where the parking brake mechanism is electrically driven by the motor gear unit 15 has been described. However, the configuration of the present invention has the same effect as described above even when applied to a manual parking brake mechanism.
This application is based on a Japanese patent application filed on Feb. 23, 2017 (Japanese Patent Application No. 2017-032278), the contents of which are incorporated herein by reference.

Here, the features of the above-described embodiment of the drum brake device according to the present invention will be briefly summarized and listed below.
[1] A pair of brake shoes (a first brake shoe 17 and a second brake shoe) disposed so as to be able to expand on a surface parallel to the backing plate (11) facing the inner peripheral surface of the brake drum (30). 19) and a link lever (42) rotatably supported at an intermediate portion of the web (first web 23) of one of the brake shoes (first brake shoe 17),
One oscillating end (upper end portion 42a) and the other oscillating end (lower end portion 42b) of the link lever (42) and the web (second web 25) of the other brake shoe (second brake shoe 19). A first strut (39) and a second strut (67) arranged in parallel between both ends;
The rotation base portion (51) rotatably supported by one end portion of the first strut (39) on the other brake shoe (second brake shoe 19) side is rotated, so that the pressing portion (63) is moved to the other side. A lever (a first brake shoe 17 and a second brake shoe 19) that expands the pair of brake shoes (first brake shoe 17 and second brake shoe 19) by pressing one end of the web (second web 25) of the brake shoe (second brake shoe 19). 49), and
The rotation base portion (51) is disposed in the vicinity of the other brake shoe (second brake shoe 19), and a lever input portion (53) extending from the rotation base portion (51) has one brake shoe (first brake). Drum brake device (100, 200) disposed in the vicinity of the shoe 17).
[2] The drum brake device according to [1] above,
A drum brake device (100) in which the lever input portion (53) is disposed between the web (first web 23) and the backing plate (11) on the one brake shoe (first brake shoe 17) side. ).
[3] The drum brake device according to [1] or [2] above,
The drum brake device (100, 200), wherein the second strut (67) has an automatic length adjusting mechanism for automatically adjusting the stroke amount of the lever (49).
[4] The drum brake device according to any one of [1] to [3],
A drum brake device (100, 200) in which the lever input portion (53) is driven by a motor gear unit (15).
[5] The drum brake device according to any one of [1] to [4] above,
The lever (49) and the first strut (39) arranged side by side are the same in which the rotation base (51) and the other end of the first strut (39) are orthogonal to the brake center axis (29). A drum brake device (100, 200) disposed on a plane (91).

According to the drum brake device of the present invention, it is possible to provide a drum brake device in which the lever ratio of the lever for expanding the pair of brake shoes can be increased and the force for rotating the lever can be reduced.

11 ... backing plate 15 ... motor gear unit 17 ... first brake shoe (one brake shoe)
19 ... Second brake shoe (the other brake shoe)
23. First web (web)
25. Second web (web)
29 ... Brake center axis 30 ... Brake drum 33 ... Parking brake mechanism (dual-two reading parking brake mechanism)
35 ... Expansion mechanism 39 ... First strut 42 ...

Link lever

43, 44 ... Wheel cylinder 45 ... Drive member 49 ... Lever 51 ... Rotating base 53 ... Lever input part 63 ... Pressing part 67 ... Second strut 100 ... Drum brake device

Claims

A pair of brake shoes disposed so as to be able to expand on a surface parallel to the backing plate facing the inner peripheral surface of the brake drum;
A link lever rotatably supported at an intermediate portion of the web in one of the brake shoes;
A first strut and a second strut disposed in parallel between one swing end and the other swing end of the link lever and both ends of the web of the other brake shoe;
The rotating base portion rotatably supported by one end portion of the first strut on the other brake shoe side is rotated, so that the pressing portion presses one end of the web in the other brake shoe and the pair of pairs A lever for expanding the brake shoe,
A drum brake device in which the rotation base is disposed in the vicinity of the other brake shoe, and a lever input portion extending from the rotation base is disposed in the vicinity of the one brake shoe.
The drum brake device according to claim 1,
A drum brake device in which the lever input portion is disposed between the web and the backing plate on the one brake shoe side.
The drum brake device according to claim 1 or 2,
The drum brake device, wherein the second strut includes an automatic length adjusting mechanism for automatically adjusting a stroke amount of the lever.
The drum brake device according to any one of claims 1 to 3,
A drum brake device in which the lever input unit is driven by a motor gear unit.
The drum brake device according to any one of claims 1 to 4,
The lever and the first strut arranged side by side are a drum brake device in which the rotating base and the other end of the first strut are arranged on the same plane perpendicular to the brake center axis.