WO2023223492A1

WO2023223492A1 - Drum brake device

Info

Publication number: WO2023223492A1
Application number: PCT/JP2022/020805
Authority: WO
Inventors: 建華唐; 尚輝秋山
Original assignee: 株式会社Tbk
Priority date: 2022-05-19
Filing date: 2022-05-19
Publication date: 2023-11-23

Abstract

A drum brake device (B) according to the present invention is configured such that, when a movement responsive rotation force, which is generated by meshing of external helical teeth (72Ba) and internal helical teeth (11A) in response to movement of a sleeve (72) and transmitted from the sleeve (72) to a drive ring (11), is larger than a first rotation resistance force given to the drive ring (11) and smaller than a second rotation resistance force acting on a screwed portion of the sleeve (72) with a screw (73), the drive ring (11) rotates and moves the sleeve (72) without rotating the sleeve (72), and, when the movement responsive rotation force is smaller than the first rotation resistance force and larger than the second rotation resistance force, the sleeve (72) moves while rotating with respect to the screw (73) through the meshing portion.

Description

drum brake device

The present invention relates to a drum brake device.

A drum brake device is installed on a vehicle and includes a cylindrical brake drum that is rotatably attached to an axle, and a cylindrical brake drum that is swingably held by an anchor bracket and arranged along the inner peripheral surface of the brake drum. It has a pair of brake shoes, and by pressing the lining provided on the brake shoes facing the brake drum against the inner peripheral surface of the brake drum, the brake drum (provided on the axle) utilizes the friction generated between the two. This brakes the rotation of the wheels.

In such a drum brake device, an expander is attached to the tip of the brake shoe that extends outward in response to brake operation, and the expansion action of the expander moves the brake shoe so that the brake shoe is attached to the brake drum. There is one that is configured to be pressed against the inner circumferential surface (for example, see Patent Document 1). The expander of this drum brake device includes a sleeve member and a pressing member provided in a housing. The sleeve member is configured to be movable in the moving direction of the brake shoe and rotatable in only one direction around a rotation axis extending in the moving direction, and moves in the moving direction in response to a driving force from the drive mechanism. It looks like this. The pressing member is screwed onto the sleeve member and moves integrally with the sleeve member in the above-mentioned movement direction, thereby moving the brake shoe and pressing it against the brake drum.

Brake shoes (brake shoe linings) wear out due to friction with the brake drum, but when this wear increases the gap between the brake shoes and the brake drum (hereinafter also referred to as shoe clearance), it can cause deterioration in brake effectiveness. Become. Therefore, the drum brake device is equipped with a gap adjustment mechanism that automatically adjusts the gap between the brake shoe and the brake drum to always maintain a constant value by reducing the shoe clearance according to the wear of the brake shoe. When the brake action is released and the pressing member moves toward the housing, the gap adjustment mechanism rotates the sleeve member independently relative to the pressing member (rotating in the above-mentioned one direction) and screws the sleeve member into the sleeve member. By projecting the pressing member outward (increasing the amount of movement of the pressing member in the direction of the rotational axis relative to the sleeve member), the brake shoe is moved toward the brake drum and the shoe clearance is reduced. ing.

Patent No. 6382340

In a drum brake device, when the brake shoes are pressed against the inner peripheral surface of the brake drum, the brake shoes and the brake drum may undergo large elastic deformations. When such elastic deformation occurs, in conventional drum brake devices, the gap is adjusted even when the pressing member moves toward the housing during the process of the brake shoe and brake drum being elastically restored after the brake action is released. There are cases. As a result, excessive clearance adjustment may occur, causing brake drag in which the brake shoes are in contact with the inner circumferential surface of the brake drum even after the brake action is released, which may cause the brake drum to generate heat while the vehicle is running. There is a possibility that harmful effects may occur.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a drum brake device that can appropriately adjust the gap while preventing the brake from dragging.

In order to solve the above problems, a drum brake device according to the present invention includes a cylindrical brake drum that is provided on a rotating member and is rotatable together with the rotating member, and a cylindrical brake drum that is movably provided on a fixed member and that is rotatable with the rotating member. A brake shoe disposed to face an inner circumferential surface, an expander that moves the brake shoe in response to a brake operation and brings it into contact with the inner circumferential surface of the brake drum, and a driving force is applied to the expander. and a drive mechanism, the expander is attached to the fixed member so as to be movable in the movement direction and rotatable about a rotation axis extending in the movement direction, and the expander receives a driving force from the drive mechanism. a sleeve member that is received and moved in the movement direction; and a pressing member that is screwed and attached to the sleeve member by a screw centered on the rotation axis, and whose tip presses and moves the brake shoe. External helical teeth are formed on the outer periphery of the sleeve member, internal helical teeth that mesh with the external helical teeth are formed on the inner periphery, and the internal helical teeth are in contact with the external helical teeth. It has a drive ring member attached to the outer periphery of the sleeve member in mesh with the helical teeth, and the drive ring member is pressed against the fixed member in the direction of the rotation axis to apply a first rotational resistance force to the drive ring member. The sleeve member is moved in response to the driving force from the drive mechanism, and the brake shoe is brought into contact with the inner circumferential surface of the brake drum by the pressing member to apply the brake. , when the driving force from the drive mechanism is released to release the brake action, the above-mentioned helical teeth generated by the meshing of the external helical teeth and the internal helical teeth according to the movement of the sleeve member. A rotational force corresponding to movement transmitted from the sleeve member to the drive ring member is larger than the first rotational resistance force applied to the drive ring member, and a second rotational force acting on the threaded portion of the sleeve member and the pressing member is larger than the first rotational resistance force applied to the drive ring member. When the rotational resistance force is smaller than the first rotational resistance force, the drive ring member rotates to move the sleeve member in the moving direction without rotating, and the rotational force corresponding to the movement is smaller than the first rotational resistance force, and the drive ring member rotates to move the sleeve member in the movement direction without rotating. When the rotational resistance force is larger than the second rotational resistance force, the sleeve member is configured to rotate and move in the moving direction with respect to the pressing member via the meshing portion.

In the drum brake device according to the present invention, a clutch ring member is fixed to the fixed member and has an abutment receiving surface that faces one end surface of the drive ring member in the direction of the rotating shaft and is brought into contact with the one end surface; a biasing member that is provided on the fixed member and applies a biasing force to the drive ring member to press the one end surface against the abutment receiving surface; A continuous clutch ring-side uneven portion is formed, and a drive ring-side uneven portion is formed on the one end surface, the drive ring side uneven portion is capable of contacting and engaging with the clutch ring-side uneven portion and is continuous in the circumferential direction of the rotating shaft. With the biasing force being applied, the drive ring member rotates while moving the contact position of the drive ring side unevenness with respect to the clutch ring side unevenness in the circumferential direction of the rotating shaft, and At this time, it is preferable that the first rotational resistance force is applied to the drive ring member through a contact portion between the clutch ring-side uneven portion and the drive ring-side uneven portion.

Further, in the drum brake device according to the present invention, the clutch ring-side uneven portion and the drive ring-side uneven portion are arranged in a circumferential direction of the rotating shaft and have a triangular cross-sectional shape along the circumferential direction. It is preferable that it is constituted by triangular teeth.

Furthermore, in the drum brake device according to the present invention, it is preferable that each of the triangular teeth has a pair of sloped surfaces, and the pair of sloped surfaces are configured such that their respective slopes are different from each other.

Further, in the drum brake device according to the present invention, the expander includes a transmission member that is provided on the fixed member so as to be movable in the movement direction and that transmits the driving force from the drive mechanism to the sleeve member, It is preferable that the sleeve member is attached to the transmission member so as to be rotatable in one direction and the other direction about the rotation axis.

Further, in the drum brake device according to the present invention, the sleeve member has a sleeve base and a sleeve sub-portion formed separately from the sleeve and fixed to the sleeve base, and the sleeve sub-portion is fixed to the sleeve base. Preferably, the external helical teeth are formed on the outer periphery.

Further, in the drum brake device according to the present invention, by manually adjusting the rotational position of the sleeve member in one direction and the other direction around the rotation axis, the pressing member can be extended in the direction of the rotation axis relative to the sleeve member. Preferably, the amount can be adjusted to increase or decrease.

According to the drum brake device according to the present invention, as the sleeve member moves, the rotational force corresponding to the movement transmitted from the sleeve member to the drive ring member generated by the meshing of the external helical teeth and the internal helical teeth is transmitted to the drive ring member. When the drive ring member is larger than the first rotational resistance force applied to the ring member and smaller than the second rotational resistance force acting on the threaded portion between the sleeve member and the pressing member, the drive ring member rotates to rotate the sleeve member. Move in the direction of movement without moving. At this time, the amount of delivery of the pressing member relative to the sleeve member does not increase or decrease. Therefore, when the second rotational resistance force acting on the threaded portion of the sleeve member and the pressing member increases, such as during the process of elastic restoration of the brake shoes and the brake drum, the brake shoes and the brake drum Since the sleeve member and the pressing member can be moved integrally in the moving direction without adjusting the gap, it is possible to prevent the brake from dragging. Further, when the rotational force corresponding to the movement is smaller than the first rotational resistance force and larger than the second rotational resistance force, the sleeve member rotates and moves in the movement direction with respect to the pressing member via the engagement portion. At this time, the amount of delivery of the pressing member relative to the sleeve member increases, thereby making it possible to appropriately adjust the gap between the brake shoe and the brake drum.

It is a front view showing a drum brake device concerning this embodiment. FIG. 2 is a sectional view taken along arrow II-II in FIG. 1, and shows the drum brake device when it is not in operation. FIG. 2 is a sectional view taken along arrow II-II in FIG. 1, and shows the drum brake device when it is in operation. It is a partial sectional view showing the structure of the drive clutch mechanism provided in the expander of the drum brake device. FIG. 3 is a perspective view showing a sleeve in the expander. FIG. 3 is a perspective view showing a drive ring in the expander. FIG. 3 is a perspective view showing a clutch ring in the expander. It is a side view which shows the structure of the connection part of the screw and brake shoe in the said expander.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of a drum brake device according to an embodiment of the present invention will be described using FIGS. 1 to 8.

As shown in FIG. 1, the drum brake device B includes a drum unit 3 including a brake drum 31 provided on an axle 1 and rotatable together with the axle 1, and an anchor bracket 2 fixed to the vehicle body so as to be swingable. A brake shoe unit 4 includes a pair of

brake shoes

40, 40 arranged along the inner circumferential surface of the brake drum 31, and a brake shoe unit 4 that swings the

brake shoes

40, 40 in response to a brake operation. It is mainly composed of an expander unit 5 that is pressed against the inner circumferential surface of the expander unit 5.

The anchor bracket 2 has a circular opening 2a in the center, and is connected to an axle housing (not shown) of the vehicle body through a bolt (not shown) inserted into a bolt hole 2b provided around the opening 2a. Fixed. Further, at the lower part of the anchor bracket 2, there is a support arm part 2c that is divided into two in the thickness direction (direction perpendicular to the plane of the paper in FIG. 1), and the support arm part 2c has a front side in the thickness direction and a rear side in the thickness direction. Circular

pin insertion ports

2d, 2d are arranged side by side on the left and right when viewed from the front, respectively.

The drum unit 3 has a wheel rim (not shown) attached to a wheel hub (not shown) rotatably attached via a bearing to an axle 1 protruding outward from an opening 2a of an anchor bracket 2. , brake drum 31 are combined. Note that a wheel is attached to the wheel rim, and the brake drum 31 and the wheel rotate together through the wheel hub.

The brake shoe unit 4 is configured with two brake shoes 40 arranged on the left and right sides when viewed from the front with the anchor bracket 2 in between. The brake shoe 40 includes a web portion 41 extending in an arc shape, a rim portion 42 attached to the outer peripheral end of the web portion 41, and a lining 43 fixed to the rim portion 42 with rivets or the like. The brake shoe 40 is disposed along the inner circumferential surface of the brake drum 31, and has a lining 43 facing the inner circumferential surface of the brake drum 31.

The brake shoe 40 has a base end pivotally fixed to the anchor bracket 2 via an anchor pin 44 inserted into a pin insertion hole 2d of the support arm 2c, and swings from left to right in FIG. It is possible to swing in the direction. A return spring 45 is provided between the tip ends of the pair of

brake shoes

40, 40 to connect them to each other. When the brakes are not operated (when the brakes are not activated), the

brake shoes

40, 40 are in a position where they are swung inward by the biasing force of the return spring 45 (i.e., a position away from the brake drum 31). ) is held.

Further, an expander unit 5 fixed to the anchor bracket 2 is arranged between the tips of the

brake shoes

40, 40. As will be described in detail later, the expander unit 5 attaches the end portions of the

brake shoes

40, 40 to the return spring 45 by the expansion operation of the

expanders

70, 70 when the brake is operated (when the brake is activated). Push outward against the force. The

brake shoes

40, 40 swing outward around the anchor pins 44, 44, respectively, and the

linings

43, 43 are pressed against the inner peripheral surface of the opposing brake drum 31, and due to the frictional force between the two, the brake drum 31 rotation is braked. Thereby, a predetermined braking effect can be obtained on the wheels that rotate integrally with the brake drum 31.

As shown in FIGS. 2 and 3, the expander unit 5 includes a housing 50 having a wedge accommodating portion 51 in the center and a pair of

cylinder portions

52, 52 communicating with the wedge accommodating portion 51 from both sides. , a wedge unit 60 as a drive mechanism which has a wedge 61 that is removably attached to the wedge accommodating part 51, and a wedge unit 60 that is provided in the

cylinder parts

52 and 52 and is tensioned in the direction of the axis X (hereinafter also referred to as "axial direction"). The

expanders

70, 70 are configured to be expandable. A boot 55 that prevents dust from entering the cylinder part 52 is attached to the open end of the cylinder part 52 in the housing 50 via a snap ring 56 (see FIG. 4). Note that the housing 50 is fixed to the anchor bracket 2 and constitutes a fixing member together with the anchor bracket 2.

The expander unit 5 is configured symmetrically, and for convenience of explanation, the inner side of the housing 50 in the axial direction ( The wedge accommodating portion 51 side) will be referred to as "one end side," and the outer side of the housing 50 in the axial direction (brake shoe 40 side) will be referred to as the "other end side." Note that FIG. 2 shows the state of the expander unit 5 when the brake is not applied, and FIG. 3 shows the state of the expander unit 5 when the brake is applied.

The wedge unit 60 applies driving force to the expander 70, and is mainly composed of a wedge 61 and a wedge spring 62. The wedge 61 is formed into a shaft shape and is attached to the housing 50 so that it can be inserted into and removed from the housing 50 in the direction of the axis Y orthogonal to the axial direction (hereinafter also referred to as the "axis orthogonal direction") by the operation of a diaphragm of a chamber (not shown). ing. When the brake is not activated (when the brake is released), the wedge 61 is pulled out to the outside of the wedge accommodating portion 51 by the biasing force of the wedge spring 62, as shown in FIG. Ru. On the other hand, when the brake is activated, the wedge 61 moves in the direction perpendicular to the axis (downward in FIG. 3) within the wedge housing part 51 against the urging force of the wedge spring 62, as shown in FIG. 51. The insertion end 61a, which is the end of the wedge 61 that is inserted into the wedge accommodating portion 51, is formed in a wedge shape that points toward the tip, and has inclined

surfaces

61b, 61b on both sides in the axial direction. . Further, the wedge 61 is provided with a roller holder 61d that supports a pair of

rollers

61c, 61c. The pair of

rollers

61c, 61c are provided rotatably relative to the roller holder 61d and movable in directions toward and away from each other (axial direction). Further, the roller holder 61d is provided so as to be able to reciprocate along the direction orthogonal to the axis, and is always urged toward the outside of the housing 50 (upward in FIG. 2) together with the wedge 61 by the wedge spring 62. . This roller holder 61d cooperates with the wedge 61 to convert the linear motion of the wedge 61 in the direction orthogonal to the axis into the linear motion of the expander 70 in the axial direction.

The expander 70 includes a tappet 71 that is fitted into the cylinder portion 52 and is arranged to be slidable in the axial direction, a sleeve 72 that is disposed on one end side of the tappet 71 in the axial direction, and a sleeve 72 that is disposed in the axial direction. The housing 51 is configured to include a screw 73 as a pressing member which is screwed into the housing 51 and extends outward from the side of the housing 51.

The tappet 71 functions as a transmission member that transmits the driving force from the wedge unit 60 to the sleeve 72, and has a main body portion 71a formed at one end in the axial direction with an outer diameter slightly smaller than the inner diameter of the cylinder portion 52. and a cylindrical portion 71b having a smaller outer diameter than the main body portion 71a on the other end side in the axial direction. The sleeve 72 has a cylindrical portion at one end in the axial direction having an outer diameter equal to that of the main body 71a of the tappet 71, and this cylindrical portion covers the cylindrical portion 71b of the tappet 71 so that the axial It is attached to the tappet 71 so as to be rotatable about X.

The tappet 71 is formed into a stepped cylindrical shape from a main body part 71a and a cylindrical part 71b having different outer diameters, and the main body part 71a has an inclined surface 71c that is substantially parallel to the inclined surface 61b of the wedge 61. . Furthermore, an O-ring 74 is attached to the outer periphery of the cylindrical portion 71b of the tappet 71 to ensure sealing between the tappet 71 and the sleeve 72. The tappet 71 is fitted into the innermost part of the cylinder part 52 that communicates with the wedge housing part 51, and has an inclined surface 71c in contact with the circumferential surface of the roller 61c. The driving force from the wedge unit 60 causes the cylinder portion 52 to slide in the axial direction.

The sleeve 72 is composed of a sleeve main portion 72A and a sleeve sub portion 72B. The sleeve main portion 72A has a base portion 72Aa and an intermediate portion 72Ab that have different outer diameters. The base portion 72Aa has an outer diameter equal to the outer diameter of the main body portion 71a of the tappet 71, and the intermediate portion 72Ab has an outer diameter smaller than the outer diameter of the base portion 72Aa. Further, the sleeve main portion 72A has a tool engaging portion 72Ac formed in an octagonal column shape on the other end side in the axial direction. A through hole 72Ad (see FIG. 5) extending along the axial direction is formed in the sleeve main portion 72A, and a female threaded portion 72Ae into which the screw 73 is screwed is formed on the inner peripheral surface of the through hole 72Ad. has been done.

The sleeve sub-portion 72B is formed into a cylindrical shape. The outer diameter of the sleeve sub-portion 72B is formed to be equal to the outer diameter of the base portion 72Aa of the sleeve main portion 72A, and the inner diameter of the sleeve sub-portion 72B is formed to be equal to the outer diameter of the intermediate portion 72Ab of the sleeve main portion 72A. The sleeve sub-portion 72B is press-fitted into the intermediate portion 72Ab of the sleeve main portion 72A, and is integrated with the sleeve main portion 72A. A plurality of concave external helical teeth 72Ba (see FIG. 5) are formed on the outer peripheral surface of the sleeve sub-portion 72B. Note that the sleeve 72 may be formed by integrally forming the sleeve main portion 72A and the sleeve sub-portion 72B as one member. As in this embodiment, the sleeve main portion 72A and the sleeve sub-portion 72B are formed separately, the external helical teeth 72Ba are formed on the sleeve sub-portion 72B, and then the sleeve sub-portion 72B is press-fitted into the sleeve main portion 72A. This structure has the advantage that it becomes easy to form the external helical teeth 72Ba. Further, it is also possible to form the sleeve main portion 72A and the sleeve sub-portion 72B from different materials. The sleeve 72 is inserted into the cylinder portion 52 of the housing 50 so that the axis X becomes the rotation axis, and rotates in one direction around the rotation axis (for example, counterclockwise when viewed from one end in the axial direction) and in the other direction around the rotation axis. (For example, clockwise when viewed from one end in the axial direction).

The screw 73 is formed into a rod shape extending in the axial direction and has a male threaded portion 73a on the outer peripheral surface, and the male threaded portion 73a is screwed into the female threaded portion 72Ae of the sleeve 72 and extends outward from the side of the housing 50. It is set up to do so. A brake shoe connecting portion 73b having a pair of connecting

surfaces

73c, 73c facing each other with the axis X in between is formed at the other end of the screw 73 in the axial direction. As shown in FIG. 8, the brake shoe 40 is connected to the brake shoe connecting portion 73b via a connecting member 80 fixed to the tip of the brake shoe 40. The connecting member 80 has a connecting portion 81 that protrudes toward the brake shoe connecting portion 73b, and is connected to the brake shoe connecting portion 73b by fitting the connecting portion 81 between the pair of connecting

surfaces

73c, 73c. It has become. When the brake shoe connecting portion 73b is connected to the brake shoe 40 via the connecting member 80, the screw 73 is in a state in which rotation about the axis X is restricted (non-rotatable state).

The expander unit 5 (expander 70) having such a configuration automatically closes the gap (shoe clearance) between the lining 43 and the brake drum 31 to a predetermined gap when the lining 43 of the brake shoe 40 wears out. Equipped with a gap adjustment function to adjust the distance. This gap adjustment function is realized by having the drive clutch mechanism 10 in addition to the tappet 71, sleeve 72, and screw 73. Note that the gap adjustment is performed by rotating the sleeve 72 screwed onto the screw 73 in the other direction (clockwise as described above) around the rotation axis, thereby adjusting the amount by which the screw 73 extends toward the other end in the axial direction relative to the sleeve 72. It is done by increasing. As shown in FIG. 5, the drive clutch mechanism 10 mainly includes a drive ring 11, a clutch ring 12, and a wave spring 13.

The drive ring 11 is formed in an annular shape, and a plurality of convex internal helical teeth 11A are formed on its inner peripheral surface. Furthermore, a drive ring-side uneven portion 11B that continues in the circumferential direction of the axis X is formed on the end surface of the drive ring 11 on one end side in the axial direction. The drive ring side uneven portion 11B is constituted by a plurality of triangular teeth 11Ba having the same shape and arranged in the circumferential direction of the axis X. Each triangular tooth 11Ba has a triangular cross-sectional shape along the circumferential direction of the axis X, and has a pair of inclined surfaces 11Bb and 11Bc. The pair of inclined surfaces 11Bb and 11Bc are configured such that their respective slopes (inclination angles with respect to a plane perpendicular to the axis steep slope). The drive ring 11 having such a configuration is arranged in the housing 50 with each internal helical tooth 11A meshing with each external helical tooth 72Ba of the sleeve 72 (sleeve sub-portion 72B). The drive ring 11 is rotated around the axis X in one direction (for example, counterclockwise when viewed from one end in the axial direction) and in the other direction around the rotation axis (for example, clockwise when viewed from one end in the axial direction). It is possible to rotate.

The clutch ring 12 is formed in an annular shape like the drive ring 11. A clutch ring-side uneven portion 12A that continues in the circumferential direction of the axis X is formed on the end surface of the other end of the clutch ring 12 in the axial direction. The clutch ring side uneven portion 12A is constituted by a plurality of triangular teeth 12Aa having the same shape and arranged in the circumferential direction of the axis X. Each triangular tooth 12Aa has a triangular cross-sectional shape along the circumferential direction of the axis X, and has a pair of inclined surfaces 12Ab and 12Ac. The pair of inclined surfaces 12Ab and 12Ac are configured such that their respective slopes (inclination angles with respect to the plane perpendicular to the axis X) are different from each other (in this example, the inclined surface 12Ab is larger than the inclined surface 12Ac. steep slope). Note that the clutch ring side uneven portion 12A has the same shape as the drive ring side uneven portion 11B when the drive ring 11 is reversed about an axis perpendicular to the X-axis. Therefore, when the clutch ring-side uneven portion 12A and the drive ring-side uneven portion 11B are butted against each other, they can be perfectly engaged with each other. The clutch ring 12 having such a configuration is fixed in the housing 50 with the clutch ring side uneven portion 12A facing and abutting against the drive ring side uneven portion 11B.

The wave spring 13 is a biasing member that applies a biasing force (referred to as a drive ring biasing force) to the drive ring 11 that presses the drive ring side uneven portion 11B against the clutch ring side uneven portion 12A. The wave spring 13 is held in the housing 50 by a boot 55 attached to the open end of the cylinder portion 52 via a snap ring 56.

In the drive clutch mechanism 10 configured in this way, a rotational resistance force (referred to as a drive ring rotational resistance force) that resists rotation of the drive ring 11 around the rotation axis is applied to the drive ring 11. This drive ring rotational resistance force can be adjusted by changing the slope of the inclined surface of each triangular tooth of the clutch ring side uneven portion 12A and the drive ring side uneven portion 11B. That is, the drive ring 11 rotates while receiving the drive ring biasing force from the wave spring 13 while moving the contact position of the drive ring side uneven portion 11B with respect to the clutch ring side uneven portion 12A in the circumferential direction of the rotating shaft. However, during this rotation, a drive ring rotational resistance force acts on the drive ring 11 via the contact portion between the clutch ring side uneven portion 12A and the drive ring side uneven portion 11B. This drive ring rotational resistance force increases as the slope of the inclined surface of each triangular tooth 12Aa of the clutch ring side uneven portion 12A and the inclined surface of each triangular tooth 11Ba of the drive ring side uneven portion 11B becomes larger. In the present embodiment, when the drive ring 11 rotates in one direction (counterclockwise as described above) around the rotation axis, the relative The sloped surface 11Bc having a gentle slope crosses over the sloped surface 12Ac having a relatively gentle slope among the pair of sloped surfaces 12Ab and 12Ac of each triangular tooth 12Aa of the clutch ring side uneven portion 12A. On the other hand, when the drive ring 11 rotates in the other direction (clockwise as described above) around the rotation axis, the relatively steep inclined surface 11Bb of each triangular tooth 11Ba of the drive ring side uneven portion 11B becomes the clutch ring side unevenness. This will overcome the relatively steep inclined surface 12Ab of each triangular tooth 12Aa of the portion 12A. Therefore, the driving The drive ring rotational resistance force (hereinafter also referred to as "drive ring clockwise rotational resistance force") that acts on the drive ring 11 when the ring rotational resistance force rotates in the other direction (clockwise as described above) around the rotation axis is larger.

Next, the operation of the drum brake B when the brake is activated and when it is not activated, and the gap adjustment by the drive clutch mechanism 10 will be explained. Below, a case where the brake drum 31 and the brake shoe 40 (lining 43) undergo relatively large elastic deformation due to brake operation will be described.

First, when the brake is operated, the wedge 61 resists the biasing force of the wedge spring 62 and is inserted into the wedge accommodating portion 51 (in the lower part of FIGS. 2 and 3) due to the operation of a diaphragm (service chamber) not shown. direction). This pressing force is converted into a pressing force in the axial direction via the

rollers

61c, 61c due to the wedge action between the

inclined surfaces

61b, 61b of the wedge 61 and the

inclined surfaces

71c, 71c of the tappet 71, and is applied to the sleeve via the tappet 71. 72. In response to this pressing force, the sleeve 72 moves together with the tappet 71 within the cylinder portion 52 from one end to the other end in the axial direction.

The sleeve 72 meshes with the drive ring 11 through the meshing portion between the external helical teeth 72Ba of the sleeve 72 and the internal helical teeth 11A of the drive ring 11. When the sleeve 72 moves toward the other end in the axial direction, a rotational force is applied from the sleeve 72 to the drive ring 11 through their meshing portions to rotate the drive ring 11 in one direction (counterclockwise) around the rotation axis. (hereinafter also referred to as "rotational force corresponding to movement during braking") acts. On the other hand, the drive ring counterclockwise rotation resistance force acts on the drive ring 11 due to the action of the drive clutch mechanism 10 . Further, the sleeve 72 is screwed onto the screw 73 via a threaded portion between a female threaded portion 72Ae of the sleeve 72 and a male threaded portion 73a of the screw 73. When the sleeve 72 moves toward the other end in the axial direction, the threaded joint between the sleeve 72 and the screw 73 has a rotational resistance force (hereinafter referred to as "braking") that resists the rotation of the sleeve 72 around the rotation axis with respect to the screw 73. At the same time, a sleeve rotation resistance force (also referred to as "sleeve rotation resistance force") acts.

In this embodiment, each triangular tooth of the clutch ring-side uneven portion 12A is arranged so that the rotational force corresponding to the movement during braking is larger than the counterclockwise rotational resistance force of the drive ring and smaller than the sleeve rotational resistance force during braking. The slope of the slope 11Bc at 11Ba and the slope of the slope 12Ac at each triangular tooth 12Aa of the clutch ring side uneven portion 12A are set. Therefore, while the drive ring 11 rotates in one direction around the rotation axis, the sleeve 72 does not rotate and moves within the cylinder portion 52 toward the other end in the axial direction.

Further, the screw 73 screwed into the sleeve 72 moves integrally with the sleeve 72 toward the other end in the axial direction. Then, due to the extension of the

screws

73, 73 in the axial direction, the pair of

brake shoes

40, 40 swing outward around the anchor pins 44, 44, and the lining 43 is pressed against the inner peripheral surface of the brake drum 31. The rotation of the brake drum 31 is braked by the friction between the two. When the lining 43 is pressed against the inner circumferential surface of the brake drum 31 and the brake drum 31 and the brake shoe 40 (lining 43) are elastically deformed, the screw 73 remains integral with the sleeve 72 even in this elastically deformed range. Move to the other end in the axial direction.

When the brake operation is released, the wedge 61 moves in the direction of removal from the wedge accommodating portion 51 (upward in FIGS. 3 and 4) due to the biasing force of the wedge spring 62. In accordance with this movement of the wedge 61, the pressing force acting on the expander 70 from the wedge 61 toward the other end in the axial direction becomes smaller. Thereby, the screw 73 and the sleeve 72 are allowed to move toward one end in the axial direction, and the brake drum 31 and the brake shoe 40 are allowed to recover elastically. When the screw 73 moves toward one end in the axial direction, the threaded portion of the screw 73 and the sleeve 72 has a rotational resistance force (hereinafter referred to as "braking") that resists the rotation of the sleeve 72 relative to the screw 73 around the rotation axis. When released, a sleeve rotation resistance force (also referred to as "sleeve rotation resistance force") acts. Furthermore, when the sleeve 72 moves toward one end in the axial direction together with the screw 73, the drive ring 11 is moved from the sleeve 72 to the drive ring 11 in the other direction around the rotation axis (clockwise as described above) via their meshing portions. A rotational force for rotation (also referred to as "rotational force for movement when brake is released") acts. On the other hand, the drive ring clockwise rotation resistance force acts on the drive ring 11 due to the action of the drive clutch mechanism 10 .

In this embodiment, in the process where the brake drum 31 and the brake shoes 40 are elastically restored, the rotational force corresponding to the movement at the time of brake release is smaller than the sleeve rotation resistance force at the time of brake release, and the drive ring counterclockwise rotation resistance force is smaller than the sleeve rotation resistance force at the time of brake release. The slope of the inclined surface 11Bb of each triangular tooth 11Ba of the clutch ring side uneven portion 12A and the slope of the inclined surface 12Ab of each triangular tooth 12Aa of the clutch ring side uneven portion 12A are set so as to be larger than the above. Therefore, while the drive ring 11 rotates in the other direction around the rotation axis, the sleeve 72 moves toward one end in the axial direction within the cylinder portion 52 without rotating.

Further, the screw 73 screwed into the sleeve 72 moves integrally with the sleeve 72 toward one end in the axial direction. At this time, since the sleeve 72 does not rotate, the amount of feed of the screw 73 relative to the sleeve 72 does not increase, and therefore no gap adjustment is performed.

As the elastic restoration of the brake drum 31 and brake shoe 40 progresses due to the movement of the screw 73 and sleeve 72 toward one end in the axial direction, the sleeve rotational resistance force at the time of brake release and the rotational force corresponding to the movement at the time of brake release are correspondingly increased. becomes smaller. In addition, even if the elastic restoration of the brake drum 31 and the brake shoes 40 is completed, the screw 73 and the sleeve 72 remain in place between the two

brake shoes

40 and 40 until they are stored in a predetermined position in the cylinder part 52. Due to the action of the return spring 45, it moves toward one end in the axial direction.

In this embodiment, when the elastic restoration of the brake drum 31 and the brake shoes 40 is completed, the rotational force corresponding to the movement at the time of brake release is greater than the sleeve rotation resistance force at the time of brake release, and is greater than the counterclockwise rotation resistance force of the drive ring. The slope of the inclined surface 11Bb of each triangular tooth 11Ba of the clutch ring side uneven portion 12A and the slope of the inclined surface 12Ab of each triangular tooth 12Aa of the clutch ring side uneven portion 12A are set such that Therefore, while the drive ring 11 does not rotate, the sleeve 72 moves toward one end in the axial direction within the cylinder portion 52 while rotating in the other direction (clockwise as described above) around the rotation axis.

Further, as the sleeve 72 rotates in the other direction (clockwise as described above) around the rotation axis, the screw 73 screwed into the sleeve 72 is moved toward the other end in the axial direction by an amount corresponding to the rotation angle of the sleeve 72. It is rolled out. This performs gap adjustment.

In this manner, in the drum brake device B equipped with the drive clutch mechanism 10, the sleeve 72 does not rotate when the screw 73 moves toward one end in the axial direction during the process of elastically restoring the brake drum 31 and the brake shoes 40. Since gap adjustment is not performed, it is possible to prevent brake drag from occurring. Further, after the elastic restoration of the brake drum 31 and the brake shoes 40 is completed, when the screw 73 moves toward one end in the axial direction, the sleeve 72 rotates to adjust the gap, so that the inner peripheral surface of the brake drum 31 The gap between the brake shoe 40 and the brake shoe 40 can be automatically adjusted appropriately.

Next, a case where the gap adjustment is performed manually will be explained. In the drum brake device B, by engaging a tool such as a spanner with the tool engaging portion 72Ac of the sleeve 72 and manually rotating the sleeve 72 around the rotation axis, the amount of delivery of the screw 73 relative to the sleeve 72 can be adjusted to increase or decrease. It looks like this. Specifically, by rotating the sleeve 72 in one direction (counterclockwise as described above) around the rotation axis, it is possible to reduce the amount of delivery of the screw 73 relative to the sleeve 72. Thereby, the gap between the inner circumferential surface of the brake drum 31 and the brake shoe 40 can be widened. Further, by rotating the sleeve 72 in the other direction (clockwise as described above) around the rotation axis, the amount of delivery of the screw 73 relative to the sleeve 72 can be increased. Thereby, the gap between the inner peripheral surface of the brake drum 31 and the brake shoe 40 can be reduced. Note that when the sleeve 72 is rotated, the drive ring 11 rotates together with the sleeve 72.

In conventional drum brake devices, the amount of payout of the screw relative to the sleeve is adjusted by manually rotating the screw. The screw is connected to the brake shoe via a clip member that restricts rotation of the screw except during manual adjustment while allowing rotation of the screw during manual adjustment. There is a risk that this clip member may be damaged by vibrations during driving, but drum brake device B does not use such a clip member as described above, so there is no such concern.

Note that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the gist of the present invention.

In the above-described embodiment, the drum brake device B is configured as a leading-trailing type drum brake, but it may also be configured as a uni-servo type, duo-servo type, or two-leading type drum brake.

B Drum brake device 1 Axle (rotating member)
2 Anchor bracket 3 Drum unit 4 Brake shoe unit 5 Expander unit 10 Drive clutch mechanism 11 Drive ring 11B Drive ring side uneven part 11A Internal helical teeth 12 Clutch ring 12A Clutch ring side uneven part 13 Wave spring 31 Brake drum 40 Brake shoe 50 Housing 60 Wedge unit 70 Expander 71 Tappet 72 Sleeve 72Ba External helical teeth 72Ae Female thread part 73 Screw 73a Male thread part

Claims

a cylindrical brake drum provided on a rotating member and rotatable together with the rotating member; a brake shoe movably provided on a fixed member and disposed facing the inner circumferential surface of the brake drum; and a brake operation device. an expander that moves the brake shoe to make it come into contact with the inner peripheral surface of the brake drum in accordance with the above, and a drive mechanism that applies a driving force to the expander,
The expander is attached to the fixed member so as to be movable in the moving direction and rotatable about a rotating shaft extending in the moving direction, and moves in the moving direction in response to a driving force from the drive mechanism. and a pressing member that is screwed onto the sleeve member with a screw centered on the rotating shaft, and whose tip presses and moves the brake shoe,
External helical teeth are formed on the outer periphery of the sleeve member,
A drive ring member having internal helical teeth that mesh with the external helical teeth formed on the inner peripheral side, the internal helical teeth meshing with the external helical teeth, and is attached to the outer periphery of the sleeve member. has
configured to press the drive ring member against the fixed member in the direction of the rotation axis to apply a first rotational resistance force to the drive ring member,
The sleeve member is moved in response to the driving force from the drive mechanism, and the brake shoe is brought into contact with the inner circumferential surface of the brake drum by the pressing member to apply the brake, or the sleeve member is moved by the driving force from the drive mechanism. When releasing the brake action by releasing the
As the sleeve member moves, a rotational force corresponding to the movement is transmitted from the sleeve member to the drive ring member, which is generated by the meshing of the external helical teeth and the internal helical teeth, and is applied to the drive ring member. When the drive ring member is larger than the first rotational resistance force acting on the threaded portion of the sleeve member and the pressing member and smaller than the second rotational resistance force acting on the threaded portion of the sleeve member and the pressing member, the drive ring member rotates to rotate the sleeve member. moving in the moving direction without any movement,
When the rotational force corresponding to the movement is smaller than the first rotational resistance force and larger than the second rotational resistance force, the sleeve member rotates with respect to the pressing member via the meshing portion in the moving direction. A drum brake device configured to move.
a clutch ring member that is fixed to the fixed member and has an abutment receiving surface that faces one end surface of the drive ring member in the rotation axis direction and that the one end surface abuts;
a biasing member that is provided on the fixed member and applies a biasing force to the drive ring member to press the one end surface against the contact receiving surface;
A clutch ring-side uneven portion continuous in the circumferential direction of the rotating shaft is formed on the abutment receiving surface,
A drive ring side uneven portion is formed on the one end surface and is capable of contacting and engaging with the clutch ring side uneven portion and continuous in the circumferential direction of the rotating shaft,
With the biasing force applied, the drive ring member rotates while moving the contact position of the drive ring side unevenness with respect to the clutch ring side unevenness in the circumferential direction of the rotating shaft, and during the rotation, The first rotational resistance force is configured to act on the drive ring member through a contact portion between the clutch ring side uneven portion and the drive ring side uneven portion. The drum brake device according to claim 1.
The clutch ring-side uneven portion and the drive ring-side uneven portion are configured by a plurality of triangular teeth arranged in the circumferential direction of the rotating shaft and having a triangular cross-sectional shape along the circumferential direction. The drum brake device according to claim 2.
The drum brake device according to claim 3, wherein each of the triangular teeth has a pair of inclined surfaces, and each of the pair of inclined surfaces is configured to have a different slope.
The expander includes a transmission member that is provided on the fixed member so as to be movable in the movement direction and that transmits the driving force from the drive mechanism to the sleeve member,
The drum brake device according to any one of claims 1 to 4, wherein the sleeve member is attached to the transmission member so as to be rotatable in one direction and the other direction about the rotation axis.
The sleeve member has a sleeve base and a sleeve sub-portion formed separately from the sleeve and fixed to the sleeve base, and the external helical teeth are formed on the outer periphery of the sleeve sub-portion. The drum brake device according to any one of claims 1 to 5, characterized in that:
By manually adjusting the rotational position of the sleeve member in one direction and the other direction around the rotation axis, the amount by which the pressing member is extended in the direction of the rotation axis relative to the sleeve member can be adjusted to increase or decrease. The drum brake device according to any one of claims 1 to 6, characterized by: