WO2019131153A1 - Brake device - Google Patents

Abstract

An electric actuator of this brake device is mounted to a backing plate in a state where a motion conversion mechanism projects from a surface opposed to a braking member in the backing plate, and a rotary member is driven to rotate via a ring gear which is provided to the outer periphery of the rotary member and which rotates in conjunction with an output shaft.

Description

Brake device

The present invention relates to a brake device.

Conventionally, a motion conversion mechanism including a rotating member that rotates in conjunction with an output shaft of a motor and a linear moving member that linearly moves according to the rotation of the rotating member is provided, and the cable is pulled by the linear moving member. The brake device which moves a brake shoe and is braked by is known (for example, patent document 1 and patent document 2). In patent document 1, the linear_motion | direct_drive member with an external thread is linearly moved according to rotation of the rotation member with an internal thread. In patent document 2, the member which transmits rotation of the output shaft of a motor is connected to the axial end surface of the side far from the brake shoe of a rotation member.

Japanese Patent Application Publication No. 2014-504711 German DE 10 2007 0029 07 A1

In a brake device in which a linear moving member having an external thread linearly moves in response to the rotation of a rotating member having an internal thread as in Patent Document 1, the diameter of a bearing for supporting the rotating member tends to be large. There was a case that the device became large.

Further, in a brake device such as Patent Document 2 in which the output shaft of the motor or a member that rotates in conjunction with the output shaft is connected to the axial end face of the rotating member of the motion conversion mechanism, the brake device is axial. There was a case to enlarge.

Therefore, one of the problems of the present invention is to obtain a brake device having a novel configuration with less inconvenience, such as smaller size.

The brake device according to the present invention includes, for example, a braking member that brakes the drum rotor by being pressed by a drum rotor that rotates integrally with a wheel, a backing plate that supports the braking member, and the backing plate. An electric actuator for operating the braking member, wherein the electric actuator has a motor having a rotating output shaft and an external thread, and is interlocked with the output shaft to rotate around the axial center of the external thread A motion conversion mechanism including a rotating member rotating in a rotating direction, and a linear moving member having a female screw meshing with the male screw and linearly moving with the rotation of the rotating member, and a force for operating the braking member from the linear moving member And the electric actuator is configured to move the motion conversion mechanism to the backing plate. The rotary member is attached to the backing plate in a state of projecting from the surface opposite to the braking member, and the rotary member is rotationally driven through a ring gear provided on the outer periphery of the rotary member and rotating in conjunction with the output shaft Be done.

According to such a configuration, for example, a bearing for supporting the rotating member in comparison with a mode in which a linear moving member having an external thread linearly moves according to the rotation of the rotating member having an internal thread as disclosed in Patent Document 1 The smaller diameter of the electric actuator makes it possible to miniaturize the electric actuator in the radial direction, and the smaller diameter of the bearing lowers the sliding speed of the bearing at the same rotational speed, which results in wear resistance. There is an advantage that the durability such as the resistance can be easily improved. Moreover, according to the above configuration, for example, the output shaft of the motor as disclosed in Patent Document 2 or a member that rotates in conjunction with the output shaft is compared with the aspect in which the axial end face of the rotating member of the motion conversion mechanism is connected. Thus, the entire length of the electric actuator is likely to be shorter. Therefore, according to the above configuration, for example, in the brake device attached to the backing plate in a state where the electric actuator protrudes from the surface of the backing plate opposite to the braking member, the miniaturization of the electric actuator as described above The advantage is obtained that it is easy to secure the space, and that the durability can be improved.

FIG. 1 is an exemplary and schematic rear view from the rear of the vehicle of the brake device of the embodiment. FIG. 2 is an exemplary and schematic side view of the brake device of the embodiment from the outer side in the vehicle width direction. FIG. 3 is an exemplary and schematic side view of the operation of the braking member by the moving mechanism of the brake device of the embodiment, which is a diagram in a non-braking state. FIG. 4 is an exemplary and schematic side view of the operation of the braking member by the moving mechanism of the brake device of the embodiment, in a braking state. FIG. 5 is an exemplary and schematic cross-sectional view of the electric actuator of the embodiment in a non-braking state. FIG. 6 is an exemplary schematic cross-sectional view of a portion of the electric actuator of the embodiment in which the actuating member is in the braking position. FIG. 7 is an exemplary schematic cross-sectional view of a part of the electric actuator of the embodiment, showing a state when the actuating member reaches the release position from the braking position. FIG. 8 is an exemplary schematic cross-sectional view of a portion of the electric actuator of the embodiment in which the actuating member has reached the release position and the rotation of the motor has been stopped. FIG. 9 is an exemplary and schematic perspective view of the movement restricting member included in the electric actuator of the embodiment. FIG. 10 is an exemplary and schematic perspective view of the linear motion member included in the electric actuator of the embodiment. FIG. 11 is an exemplary and schematic perspective view of a part of the motion conversion mechanism included in the electric actuator of the embodiment. FIG. 12 is an exemplary schematic cross-sectional view of a part of the electric actuator according to the first modification, which is a diagram in a non-braking state. FIG. 13 is an exemplary schematic cross-sectional view of a part of the electric actuator according to the second modification, which is a diagram in a non-braking state. FIG. 14 is an exemplary and schematic perspective view of the movement restricting member included in the electric actuator of the third modification.

In the following, exemplary embodiments of the present invention are disclosed. The configurations of the embodiments and modifications shown below, and the operations and results (effects) provided by the configurations are examples. The present invention can also be realized by configurations other than those disclosed in the following embodiments and modifications. Further, according to the present invention, it is possible to obtain at least one of various effects (including derivative effects) obtained by the configuration.

The following embodiments and modifications include similar components. Therefore, in the following, the same reference numeral is given to the same component, and the overlapping description may be omitted. Further, in the present specification, ordinal numbers are given for the sake of convenience in order to distinguish parts, parts, etc., and do not indicate priority or order.

Further, in each figure, the direction in which the end 150a (one end) of the cable 150 is away from the braking member in the axial direction of the third rotation center Ax3 is indicated by the arrow D1, and in the axial direction of the third rotation center Ax3 The direction in which the end 150a approaches the braking member is indicated by the arrow D2. In the following, unless otherwise stated, the axial direction of the third rotation center Ax3 is simply referred to as the axial direction, the radial direction of the third rotation center Ax3 is simply referred to as the radial direction, and the circumferential direction of the third rotation center Ax3 Is simply referred to as the circumferential direction.

[Embodiment]
[Configuration of brake device]
FIG. 1 is a rear view from behind the vehicle of the brake device 2 for a vehicle. FIG. 2 is a side view of the brake device 2 from the outer side in the vehicle width direction. FIG. 3 is a side view showing the operation of the brake shoe 3 (the braking member) by the moving mechanism 8 of the brake device 2 and is a view in a non-braking state. FIG. 4 is a side view showing the operation of the brake shoe 3 by the moving mechanism 8 of the brake device 2 and is a view in a braking state.

As shown in FIG. 1, the brake device 2 is accommodated inside the peripheral wall 1 a of the cylindrical wheel 1. The brake device 2 is a so-called drum brake. As shown in FIG. 2, the brake device 2 includes two brake shoes 3 spaced apart in the front-rear direction. The two brake shoes 3 extend in an arc along the inner peripheral surface 4a of the cylindrical drum rotor 4 as shown in FIGS. The drum rotor 4 rotates integrally with the wheel 1 about a rotation center C along the vehicle width direction (Y direction). The brake device 2 moves the two brake shoes 3 so as to contact the inner peripheral surface 4 a of the cylindrical drum rotor 4. As a result, the drum rotor 4 and hence the wheel 1 are braked by the friction between the brake shoe 3 and the drum rotor 4. The brake shoe 3 is an example of a braking member.

The brake device 2 includes, as an actuator for moving the brake shoe 3, a wheel cylinder 51 (see FIG. 2) operated by oil pressure and a motor 120 operated by energization. The wheel cylinder 51 and the motor 120 can move two brake shoes 3 respectively. The wheel cylinder 51 is used, for example, for braking while traveling, and the motor 120 is used, for example, for braking when parking. That is, the brake device 2 is an example of an electric parking brake. Motor 120 may be used for braking while traveling.

The brake device 2 is provided with a disk-like backing plate 6 as shown in FIGS. The backing plate 6 is provided in a posture crossing the rotation center C. That is, the backing plate 6 extends substantially along the direction intersecting the rotation center C, specifically, along the direction orthogonal to the rotation center C. As shown in FIG. 1, the components of the brake device 2 are provided on both the outside and the inside of the backing plate 6 in the vehicle width direction. The backing plate 6 supports each component of the brake device 2 directly or indirectly. That is, the backing plate 6 is an example of a support member. The backing plate 6 is also connected to a connecting member (not shown) with the vehicle body. The connection member is, for example, a part of the suspension (for example, an arm, a link, a mounting member, etc.). The opening 6b provided in the backing plate 6 shown in FIG. 2 is used for coupling with the connection member. In addition, the brake device 2 can be used for any of a driving wheel and a non-driving wheel. When the brake device 2 is used as a drive wheel, an axle (not shown) passes through the opening 6c provided in the backing plate 6 shown in FIG.

[Actuation of brake shoe by wheel cylinder]
The wheel cylinder 51, the brake shoe 3 and the like shown in FIG. 2 are disposed outward of the backing plate 6 in the vehicle width direction. The brake shoe 3 is movably supported by the backing plate 6. Specifically, as shown in FIG. 3, the lower end portion 3a of the brake shoe 3 is supported by the backing plate 6 (see FIG. 2) so as to be rotatable about the rotation center C11. The rotation center C11 is substantially parallel to the rotation center C of the wheel 1. Further, as shown in FIG. 2, the wheel cylinder 51 is supported by the upper end portion of the backing plate 6. The wheel cylinder 51 has two unshown movable parts (pistons) which can protrude in the vehicle longitudinal direction (left and right direction in FIG. 2). The wheel cylinder 51 causes the two movable parts to project in response to the pressure application. The two projecting movable parts respectively push the upper end 3 b of the brake shoe 3. The two brake shoes 3 rotate about the rotation center C11 (see FIGS. 3 and 4) by the projection of the two movable parts, and move so that the upper end portions 3b are separated from each other in the vehicle longitudinal direction. Thereby, the two brake shoes 3 move radially outward of the rotation center C of the wheel 1. A band-like lining 31 along the cylindrical surface is provided on the outer peripheral portion of each brake shoe 3. Accordingly, the radial outward movement of the rotation center C of the two brake shoes 3 brings the lining 31 into contact with the inner circumferential surface 4 a of the drum rotor 4 as shown in FIG. 4. The friction between the lining 31 and the inner circumferential surface 4a brakes the drum rotor 4 and hence the wheel 1 (see FIG. 1). Further, as shown in FIG. 2, the brake device 2 is provided with a return member 32. The return member 32 is a position where the two brake shoes 3 are in contact with the inner peripheral surface 4a of the drum rotor 4 when the operation of pushing the brake shoes 3 by the wheel cylinder 51 is released (braking position Psb, see FIG. 4) To the position (non-braking position Psn, initial position, see FIG. 3) not in contact with the inner peripheral surface 4a of the drum rotor 4. The return member 32 is, for example, an elastic member such as a coil spring, and forces each brake shoe 3 in a direction to approach the other brake shoe 3, that is, a force in a direction away from the inner circumferential surface 4 a of the drum rotor 4 give.

[Configuration of moving mechanism and operation of brake shoe by moving mechanism]
The brake device 2 further includes a moving mechanism 8 shown in FIGS. The moving mechanism 8 moves the two brake shoes 3 from the non-braking position Psn (FIG. 3) to the braking position Psb (FIG. 4) based on the operation of the electric actuator 100 (see FIG. 5) including the motor 120. The moving mechanism 8 is provided outward of the backing plate 6 in the vehicle width direction. The moving mechanism 8 has a lever 81, a cable 150, and a strut 83. The lever 81 is disposed between the brake shoe 3L and the backing plate 6 between the brake shoe 3L and the backing plate 6 between the brake shoe 3L on the left side in FIG. It is provided to overlap in the axial direction. Further, the lever 81 is rotatably supported by the brake shoe 3L around the rotation center C12. The rotation center C12 is located at an end of the brake shoe 3L on the side (upper side in FIGS. 3 and 4) away from the rotation center C11, and is substantially parallel to the rotation center C11. The cable 150 moves the lower end 81a of the lever 81 far from the rotation center C12 in the direction approaching the brake shoe 3R on the other side, for example, in FIGS. The cable 150 moves substantially along the backing plate 6. The strut 83 is interposed between the lever 81 and the brake shoe 3R other than the brake shoe 3L on which the lever 81 is supported, and is stretched between the lever 81 and the other brake shoe 3R. The connection position P1 between the lever 81 and the strut 83 is set between the rotation center C12 and the connection position P2 between the end 150b (the other end) of the cable 150 and the lever 81. The cable 150 is an example of an operating member that moves the brake shoe 3.

In the moving mechanism 8 as described above, when the lever 81 moves in the direction approaching the brake shoe 3R by pulling the cable 150 and moving to the right in FIG. 4 (arrow a), the lever 81 moves through the strut 83. Press the brake shoe 3R (arrow b). As a result, the brake shoe 3R rotates from the non-braking position Psn (FIG. 3) to the rotation center C11 (arrow c in FIG. 4) and contacts the inner peripheral surface 4a of the drum rotor 4 at the braking position Psb (FIG. 4) Move to In this state, the connection position P2 between the cable 150 and the lever 81 corresponds to the power point, the rotation center C12 corresponds to the fulcrum, and the connection position P1 between the lever 81 and the strut 83 corresponds to the action point. Furthermore, with the brake shoe 3R in contact with the inner circumferential surface 4a, when the lever 81 moves to the right in FIG. 4, that is, when the strut 83 moves in the direction to push the brake shoe 3R (arrow b) Thus, the lever 81 rotates in the direction opposite to the moving direction of the lever 81, that is, in the counterclockwise direction in FIG. Thus, the brake shoe 3L rotates from the non-braking position Psn (FIG. 3) around the rotation center C11 and moves to the braking position Psb (FIG. 4) in contact with the inner circumferential surface 4a of the drum rotor 4. Thus, the brake shoes 3L and 3R both move from the non-braking position Psn (FIG. 3) to the braking position Psb (FIG. 4) by the operation of the moving mechanism 8. In the state after the brake shoe 3R contacts the inner circumferential surface 4a of the drum rotor 4, the connection position P1 of the lever 81 and the strut 83 is a fulcrum. The amount of movement of the brake shoes 3L and 3R is very small, for example, 1 mm or less.

[Electric actuator]
As shown in FIG. 1, the electric actuator 100 is fixed to the backing plate 6 in a state in which the electric actuator 100 protrudes from the inner surface 6 a in the vehicle width direction of the backing plate 6 to the opposite side to the brake shoe 3.

FIG. 5 is a cross-sectional view of the electric actuator 100 in a non-braking state. The electric actuator 100 pulls the brake shoe 3 (braking member) via the cable 150 to move the brake shoe 3 from the non-braking position to the braking position. The cable 150 passes through a through hole 6 d provided in the backing plate 6. The cable 150 is an example of the actuating member.

As shown in FIG. 5, the electric actuator 100 includes a housing 110, a motor 120, a reduction mechanism 130, a motion conversion mechanism 140, a cable 150, and a control device 200.

The housing 110 supports the motor 120, the reduction mechanism 130, and the motion conversion mechanism 140. The housing 110 includes a body 112 (base), a lower case 113, an inner cover 114, and an upper case 115. These are integrated, for example, by unillustrated connectors such as screws, insert molding, or the like. In the housing 110, a storage chamber R surrounded by the wall portion 111 of the housing 110 is provided. The motor 120, the reduction gear mechanism 130, and the motion conversion mechanism 140 are accommodated in the accommodation chamber R and covered by the wall 111. The housing 110 may be referred to as a base, a support member, a casing or the like. In addition, the structure of the housing 110 is not limited to what was illustrated here.

The body 112 can be made of, for example, a metal material such as an aluminum alloy. In this case, the body 112 can be manufactured by die casting, for example. The lower case 113, the inner cover 114, and the upper case 115 can be made of, for example, a synthetic resin material.

The motor 120 is an example of an actuator, and includes a case 121 and a housing part housed in the case 121. The housing part includes, for example, a stator, a rotor, a coil, a magnet (not shown), etc. in addition to the output shaft 122. The output shaft 122 projects from the case 121 in a direction D2 (rightward in FIG. 5) along the first rotation center Ax1 of the motor 120. The motor 120 is controlled by a control device such as an electronic control unit (ECU), for example, and rotates the output shaft 122.

The speed reduction mechanism 130 includes a plurality of gears rotatably supported by the housing 110. The plurality of gears are, for example, a first gear 131, a second gear 132, and a third gear 133. The speed reduction mechanism 130 may be referred to as a rotation transmission mechanism.

The first gear 131 rotates integrally with the output shaft 122 of the motor 120. The first gear 131 may be referred to as a drive gear.

The second gear 132 rotates about a second rotation center Ax2 parallel to the first rotation center Ax1. The second gear 132 includes an input gear 132a and an output gear 132b. The input gear 132 a meshes with the first gear 131. The number of teeth of the input gear 132 a is larger than the number of teeth of the first gear 131. Thus, the second gear 132 is decelerated to a lower rotational speed than the first gear 131. The output gear 132b is located rearward (leftward in FIG. 5) of the direction D1 with respect to the input gear 132a. The second gear 132 may be referred to as an idler gear.

The third gear 133 rotates about a third rotation center Ax3 parallel to the first rotation center Ax1. The third gear 133 meshes with the output gear 132 b of the second gear 132. The number of teeth of the third gear 133 is larger than the number of teeth of the output gear 132b. Therefore, the third gear 133 is decelerated to a rotational speed lower than that of the second gear 132. The third gear 133 may be referred to as a driven gear. The third gear 133 is an example of a ring gear. Here, the ring gear is an annular gear and in this case is an external gear. The configuration of the speed reduction mechanism 130 is not limited to the one exemplified here. The speed reduction mechanism 130 may be, for example, a rotation transmission mechanism other than a gear mechanism, such as a rotation transmission mechanism using a belt, a pulley, or the like.

The motion conversion mechanism 140 has a rotating member 141 and a linear moving member 142. FIG. 6 is an enlarged sectional view of the motion conversion mechanism 140. As shown in FIG. The position of the cable 150 is different between FIG. 5 and FIG.

As shown in FIG. 6, the rotating member 141 has a peripheral wall 141a and a flange 141b. The shape of the peripheral wall 141a is a cylindrical shape centered on the third rotation center Ax3. A through hole 141c extending in the axial direction is provided inside the peripheral wall 141a.

The shape of the flange 141 b is annular and plate-like. The flange 141 b protrudes radially outward from the peripheral wall 141 a. A third gear 133 is provided on the outer periphery of the flange 141 b. That is, the rotating member 141 and the flange 141b may be referred to as a driven portion or a third gear.

The peripheral wall 141a has a first extending portion 141a1 extending from the flange 141b in the direction D1 and a second extending portion 141a2 extending from the flange 141b in the direction D2. The length of the first extending portion 141a1 is longer than the length of the second extending portion 141a2.

An external thread 141 d is provided on the outer periphery of the first extending portion 141 a 1. The center of the male screw 141 d is a third rotation center Ax3. The third rotation center Ax3 is an example of an axial center.

A radial bearing 161 such as a slide bush or a roller bearing is provided between the outer periphery of the second extending portion 141a2 and the inner periphery of the through hole 112a of the body 112, for example. Further, a thrust bearing 162 such as a roller bearing is provided between the end surface 141 b 1 of the flange 141 b in the direction D 2 and the end surface 112 b of the body 112 in the direction D 1. The rotating member 141 is rotatably supported by the body 112 about the third rotation center Ax3 via the radial bearing 161 and the thrust bearing 162. The rotating member 141 is rotationally driven by the second gear 132 by the engagement of the second gear 132 and the third gear 133.

The third gear 133 is made of, for example, a synthetic resin material, and the disc 141 b 2 of the peripheral wall 141 a and the flange 141 b excluding the third gear 133 may be made of, for example, a metal material such as iron or aluminum alloy. In the present embodiment, iron is used as an example. In this case, the rotating member 141 can be configured, for example, by insert molding. The rotating member 141 may be integrally formed of a metal material, including the third gear 133.

The linear moving member 142 has a side wall 142a and a flange 142b. The side wall 142 a is positioned radially outward with respect to the rotation member 141 and extends in the axial direction. The side wall 142a surrounds the third rotation center Ax3 and the rotation member 141, and the shape of the side wall 142a is cylindrical around the third rotation center Ax3. Side wall 142a may also be referred to as a circumferential wall. A through hole 142c extending in the axial direction is provided inside the side wall 142a. The rotation member 141 axially penetrates the through hole 142 c.

The shape of the flange 142 b is polygonal and plate-like. The flange 142b protrudes radially outward from the side wall 142a.

The side wall 142a has a first extension 142a1 extending from the flange 142b in the direction D1 and a second extension 142a2 extending from the flange 142b in the direction D2. The length of the first extending portion 142a1 is longer than the length of the second extending portion 142a2.

On the inner surface of the through hole 142c, a female screw 142d that meshes with the male screw 141d of the rotating member 141 is provided. The female screw 142d is provided adjacent to the end of the through hole 142c in the direction D2. The female screw 142d is provided in the section from the end of the through hole 142c in the direction D2 to the position radially aligned with the flange 142b, and is not provided at the end of the through hole 142c in the direction D1. Further, the flange 142 b is surrounded by the axially extending detent member 143.

The locking member 143 has a side wall 143a. The side wall 143a is positioned radially outward with respect to the flange 142b and extends in the axial direction. The side wall 143a surrounds the third rotation center Ax3 and the periphery of the rotating member 141, and the shape of the side wall 143a is tubular. Side wall 143a may also be referred to as a peripheral wall.

The anti-rotation member 143 is fixed to a housing 110 such as the body 112 or the upper case 115, for example. A minute gap is provided between the outer surface 142b1 of the flange 142b and the inner surface 143a1 of the side wall 143a in parallel with each other, and both the outer surface 142b1 and the inner surface 143a1 extend in the direction intersecting the circumferential direction. .

Therefore, the rotation of the outer surface 142 b 1 about the third rotation center Ax 3 is limited by the inner surface 143 a 1, whereby the rotation of the linear moving member 142 is limited by the anti-rotation member 143. On the other hand, since both the outer surface 142 b 1 and the inner surface 143 a 1 extend in the axial direction, the inner surface 143 a 1 does not hinder the axial movement of the outer surface 142 b 1. That is, the rotation preventing member 143 can guide the linearly moving member 142 along the axial direction while prohibiting the rotation of the linearly moving member 142 about the third rotation center Ax3. The inner surface 143a1 is an example of a guide portion.

A plurality of protrusions 143 b protruding inward in the radial direction from the side wall 143 a are provided at the end of the rotation prevention member 143 in the direction D 1. The inner end of the protrusion 143 b is located radially outward of the side wall 142 a of the linear motion member 142. It should be noted that one annular protrusion (inward facing flange) along the circumferential direction may be provided instead of the plurality of protrusions 143b.

The cable 150 passes through the through hole 141 c of the rotating member 141 and extends in the axial direction. One axial end (right end in FIG. 6) is coupled to a movable member that operates the brake shoe 3. Further, a cable end 144 is coupled to an end 150a (left end in FIG. 6) as the other axial end. The cable end 144 has a tubular portion 144a and a flange 144b. The cable 150 and the cable end 144 are coupled by caulking the tubular portion 144a from the outside. The flange 144 b protrudes radially outward beyond the side wall 142 a of the linear moving member 142 and the inner end of the protrusion 143 b of the rotation preventing member 143.

The cable end 144 and the linear motion member 142 are not integrated but are configured to be able to be separated in the axial direction. Here, the cable 150 is pulled in a direction (direction D2) in which the braking member is in a braking state by an elastic member (biasing member) such as a spring (not shown). Thus, the cable end 144 is pressed against the linear motion member 142 in the direction D2. The electric actuator 100 is configured such that the biasing force of the elastic member always acts on the cable 150 in the movement range of the cable 150 (the use range of the brake). Further, in the braking state, the cable 150 is subjected to tension corresponding to the rigidity of the brake device. In such a configuration, force is transmitted between the linear motion member 142 and the cable 150 via the cable end 144. The cable end 144 is an example of the transmission member.

Control device 200 controls motor 120. A part of the control device 200 may be configured by hardware such as a central processing unit (CPU) or a controller that executes software, or the control device 200 may be configured entirely by hardware. . The control device 200 is an example of a control unit.

In such a configuration, when the rotation of the output shaft 122 of the motor 120 is transmitted to the rotating member 141 via the speed reduction mechanism 130 and the rotating member 141 rotates, the male screw 141 d of the rotating member 141 and the female screw 142 d of the linear moving member 142 And the rotation of the outer surface 142b1 of the linearly moving member 142 by the inner surface 143a1 of the detent member 143 limits the linearly moving member 142 in the axial direction. Thus, the cable 150 moves in the axial direction between the braking position Pb and the release position Pr in accordance with the movement of the linear movement member 142.

FIG. 6 is a cross-sectional view of the motion conversion mechanism 140 with the cable 150 in the braking position Pb, and FIG. 7 is a view of the motion conversion mechanism 140 when the cable 150 reaches the release position Pr from the braking position Pb. FIG. 8 is a cross-sectional view, and FIG. 8 is a cross-sectional view of the motion conversion mechanism 140 in a state in which the cable 150 reaches the release position Pr and the rotation of the motor 120 is stopped.

The cable 150 moves in the direction D1 by rotation of the output shaft 122 of the motor 120 controlled by the control device 200 in one direction (hereinafter, referred to as braking rotation direction), and the braking member is in the braking state. The tension increases, which increases the rotational load of the motor 120 and thus the drive current of the motor 120. Therefore, for example, when the drive current of the motor 120 exceeds the threshold value, the control device 200 detects that the cable 150 has reached the braking position Pb, and stops the supply of the drive current to the motor 120 at that time. . As a result, the rotation of the output shaft 122 is stopped, and the cable 150 is located at the braking position Pb (FIG. 6).

The cable 150 is moved from the braking position Pb (FIG. 6) to the direction D 2 by the rotation of the output shaft 122 of the motor 120 controlled by the controller 200 in the other direction (hereinafter referred to as release rotation direction). Is moved to the release position Pr in contact with the projection 143 b of the rotation stopping member 143 (FIG. 7). In this state, the braking member is separated from the rotating member (not shown, for example, a brake drum), and the electric braking state by the electric actuator 100 is released. The protrusion 143 b restricts the movement in the direction D 2 beyond the position in contact with the protrusion 143 b of the cable end 144. That is, the protrusion 143 b is an example of a positioning portion that positions the cable 150 at the release position Pr, and the rotation preventing member 143 is an example of a movement restricting member.

In the state where the cable 150 is positioned at the release position Pr, a gap g is provided between the rotating member 141 and the cable end 144 in the axial direction. The positioning of the cable 150 at the release position Pr due to the contact between the protrusion 143 b and the cable end 144 is not essential. For example, the release position Pr may be determined by contact between the lever 81 and another member, and in this case, the protrusion 143 b and the cable end 144 may not be in contact with each other.

As described above, in the present embodiment, the cable end 144 and the linear motion member 142 are not integrated, and can be axially separated. For this reason, when the output shaft 122 of the motor 120 is further rotated in the release rotational direction from the state where the cable 150 is positioned at the release position Pr, engagement of the male screw 141d and female screw 142d and rotation of the linear movement member 142 by the rotation stopping member 143. The stop causes linear member 142 to move away from cable end 144 in direction D2 (FIG. 8).

The control device 200 measures the time (rotation time) in which the motor 120 is rotated from the state where the cable 150 is at the braking position Pb (rotation time) and the number of rotations of the output shaft 122 The operation of the motor 120 is stopped at the position of FIG. 8 separated from D2. At this time, the rotation time and the number of rotations are between the stopped linear moving member 142 and another member (for example, the second gear 132 or the flange 141 b of the rotating member 141) separated from the linear moving member 142 in the direction D2. In order to make the gap more reliable, in other words, it is set so as not to contact or interfere with other members.

9 is a perspective view of the detent member 143, FIG. 10 is a perspective view of the linear moving member 142, and FIG. 11 is a perspective view of the cable 150, the cable end 144, the detent member 143, and the linear moving member 142. FIG. 10 is a perspective view of the cable 150 in the release position Pr.

As shown in FIG. 9, the detent member 143 can be configured by pressing or bending a plate of a metallic material such as an iron-based material. The side wall 143a is formed in a hexagonal tubular shape. Each of the six inner surfaces 143a1 of the side wall 143a has a planar shape that is orthogonal to the radial direction and extends in the axial direction. The end surface 143b1 in the direction D1 of the protrusion 143b is substantially orthogonal to the axial direction.

In addition, a projection 143 b is configured by bending a projection that protrudes in the axial direction from an end in the direction D 1 of the side wall 143 a inward in the radial direction. The locking member 143 has three protrusions 143b, but may have two protrusions 143b or may have four or more protrusions 143b.

As shown in FIG. 10, the shape of the flange 142b provided on the linear moving member 142 is a hexagonal plate. The six outer surfaces 142b1 of the flange 142b are each planar and orthogonal to the radial direction and axially extending. Since the six inner surfaces 143a1 of the detent member 143 and the six outer surfaces 142b1 of the flange 142b face each other, the linearly moving member 142 moves in the axial direction while the rotation around the third rotation center Ax3 is limited. The linear motion member 142 can be configured, for example, by forging a metal material such as an aluminum alloy.

As shown in FIGS. 9 and 7, the cable end 144 flange 144b abuts on the end surfaces 143b1 of the three protrusions 143b, whereby the cable 150 is positioned at the release position Pr. The cable end 144 can be more stably supported by the three protrusions 143b.

As described above, in the present embodiment, the motion conversion mechanism 140 has the male screw 141 d, and the rotating member 141 that rotates around the third rotation center Ax3 (axial center of the male screw 141 d) in conjunction with the output shaft 122; And a linear motion member 142 which has a female screw 142d engaged with the male screw 141d, and linearly moves with the rotation of the rotation member 141. In addition, the electric actuator 100 is attached to the backing plate 6 in a state where the motion conversion mechanism 140 protrudes from the surface 6a on the opposite side to the brake shoe 3 (braking member) in the backing plate 6, and the rotating member 141 is the rotating member It is rotationally driven via a third gear 133 (ring gear) provided on the outer periphery of 141 and rotating in conjunction with the output shaft 122.

According to such a configuration, for example, the rotation member 141 is supported compared to a mode in which the linear movement member having the male screw linearly moves according to the rotation of the rotation member having the female screw as disclosed in Patent Document 1 The diameter of the radial bearing 161 and the thrust bearing 162 is likely to be small, and the support structure of the rotating member 141 can be further miniaturized, and the diameter of the radial bearing 161 and the thrust bearing 162 is smaller, so that the same rotation is achieved. Since the sliding speed of the radial bearing 161 and the thrust bearing 162 at a lower speed becomes lower, there is an advantage that durability such as wear resistance can be easily improved. Moreover, according to the above configuration, for example, the output shaft of the motor as disclosed in Patent Document 2 or a member that rotates in conjunction with the output shaft is compared with an aspect in which the axial end face of the rotating member of the motion conversion mechanism is connected. Thus, the entire length of the electric actuator 100 is easily shortened. Therefore, according to the above configuration, for example, in the brake device 2 attached to the backing plate 6 in a state where the electric actuator 100 protrudes from the surface 6 a on the opposite side to the brake shoe 3 in the backing plate 6, The miniaturization of the actuator 100 offers the advantage of being able to easily secure a vehicle-mounted space and the advantage of being able to improve the durability.

Further, in the present embodiment, the male screw 141 d and the female screw 142 d mesh with each other on the side of the third gear 133 opposite to the brake shoe 3, and the end 150 a (one end) of the cable 150 (operating member) The other end of the cable 150 is configured to operate the brake shoe 3 under the force of operating the brake shoe 3. According to such a configuration, for example, as compared with the aspect in which the male screw and the female screw engage with each other on the braking member side more than the ring gear, the connecting portion with the cable 150 in the linear moving member 142 may be further away from the braking member Since the connecting member with the cable 150 in the linear moving member 142 is provided at a position closer to the braking member, the body 112 can be shorter in the axial direction. Since the body 112 is a site that receives the tension applied from the cable 150 in the braking state, the rigidity is set relatively high. Thus, the longer the axial length of the body 112, the heavier the housing 110 and hence the electric actuator 100 are likely to be. Further, since the body 112 is a mounting site of the electric actuator 100, the center of gravity of the electric actuator 100 is separated from the mounting member (for example, backing plate) as the axial length of the body 112 is longer. The vibrational energy when it vibrates tends to be larger. In this respect, according to the above configuration, since the body 112 can be configured to be shorter, for example, the electric actuator 100 can be configured to be smaller or lighter, or vibration when the electric actuator 100 vibrates. The advantage is obtained that energy can be made smaller.

Further, in the present embodiment, for example, the cable 150 passes through the through hole 142c provided in the linear motion member 142, and the end 150a (one end) opposite to the brake shoe 3 with respect to the through hole 142c is , The force acting on the brake shoe 3 from the linear moving member 142. According to such a configuration, for example, as compared with the aspect in which the actuating member is disposed so as to bypass the radial outer side of the ring gear, the cable 150 has a third rotation center Ax3 (axial center of the rotation member 141). Since it can be arranged in a linearly extended state, it is possible to suppress that the reaction force applied to the operation of the brake shoe 3 acts in the direction intersecting the third rotation center Ax3. Therefore, for example, it is possible to suppress the force of lowering the rotating member 141, which contributes to downsizing of the supporting structure of the rotating member 141 and improvement in durability. Further, for example, as compared with the aspect in which the actuating member is disposed to bypass the radially outer side of the ring gear, the electric actuator 100 can be prevented from being enlarged in the radial direction.

Further, in the present embodiment, the cable end 144 (transmission member) fixed to the cable 150 is configured to be able to be separated axially from the linear movement member 142. According to such a configuration, the linear motion member 142 can be moved independently of the cable 150. In a more specific example, the overrun of the linear moving member 142 can be allowed without moving the cable 150 and thus the brake shoe 3. Therefore, the control accuracy in the case of controlling the movement amount of the linear movement member 142 can be relaxed.

Further, in the present embodiment, the protrusion 143 b of the rotation prevention member 143 (movement restriction member) restricts the movement of the cable end 144 in the direction D2. According to such a configuration, for example, the cable end 144 can be used to restrict the movement of the cable 150 in addition to the transmission of force between the cable 150 and the linear motion member 142. Thus, for example, the rotation of the rotating member 141 can be suppressed from being transmitted to the cable end 144 by the cable end 144 coming into contact with the rotating member 141, so that, for example, the rotating member 141 and the cable end 144 slide against each other. It is possible to suppress the occurrence of inconvenience such as movement and wear.

Further, in the present embodiment, the control device 200 controls the motor 120 so that the rotation is stopped after the movement of the cable end 144 in the direction D2 (release direction) is limited by the rotation stopping member 143 (movement limiting member). Do. According to such a configuration, for example, the cable 150 is more reliably released based on the driving time and the amount of rotation (number of rotations, rotation angle) of the motor 120 required to move the cable 150 from the braking position Pb to the release position Pr. It is possible to operate or stop the motor 120 in a state where the position Pr is reached. Therefore, for example, there is an advantage that it is not necessary to provide a sensor or the like for detecting the position of the cable 150 or the linear motion member 142 when stopping the operation of the motor 120.

Further, in the present embodiment, the rotation preventing member 143 has an inner surface 143a1 (guide portion) that guides the linear moving member 142 in the axial direction while restricting the rotation of the linear moving member 142. According to such a configuration, for example, the electric actuator 100 can be realized as a simpler configuration as compared with a configuration in which the detent member 143 and the movement restricting member are separately provided.

Further, in the present embodiment, the rotating member 141 is provided with an external thread 141 d, and the linear moving member 142 is provided with an internal thread 142 d. According to such a configuration, as one example, the motion conversion mechanism 140 and thus the electric actuator 100 is realized by a relatively simple configuration by the rotating member 141 having the male screw 141 d and the linear moving member 142 having the female screw 142 d. be able to.

Further, in the present embodiment, a gap is provided in the axial direction between the rotating member 141 and the cable end 144 in the state where the cable 150 is positioned at the release position Pr. According to such a configuration, for example, transmission of the rotation of the rotation member 141 to the cable 150 via the cable end 144 is suppressed. The same effect can be obtained even in the case where a detent structure is provided between the cable end 144 and the detent member 143 to limit relative rotation in the circumferential direction by engagement of irregularities or the like.

Further, in the present embodiment, the detent member 143 may be configured by press molding or bending of a metal material. According to such a configuration, for example, the locking member 143 can be configured relatively easily or at a lower cost.

First Modification
FIG. 12 is a cross-sectional view of a part of the electric actuator 100A of the present modification. The configuration shown in FIG. 12 can be replaced with the corresponding portion of the electric actuator 100 of the above embodiment. In the motion conversion mechanism 140A of this modification, the center of the cable end 144A and thus the cable 150 is a third rotation center between the cable end 144A and the rotation stopping member 143A, and between the cable end 144A and the linear movement member 142A. A guide mechanism 145 is provided which is positioned radially to be positioned at Ax3. The guide mechanism 145 has an outer surface 144c1 of the protrusion 144c projecting in the direction D2 from the flange 144b of the cable end 144A, an inner surface 143b2 (recessed portion, opening) of the protrusion 143b of the rotation preventing member 143A, and the direction D1 side of the linear motion member 142A. And an inner surface 142c1 provided at the tip of the. The outer surface 144c1 is a conical outer surface whose diameter decreases in the direction D2, and the inner surface 143b2 and the inner surface 142c1 are conical inner surfaces in which the diameter decreases in the direction D2. The outer surface 144c1 and the inner surface 143b2 are configured to have a minute gap between the outer surface 144c1 and the inner surface 143b2 in a state where the flange 144b abuts on the end surface 143b1 of the protrusion 143b. The outer surface 144c1 and the inner surface 142c1 are configured such that a minute gap is provided between the outer surface 144c1 and the inner surface 142c1 in a state where the flange 144b abuts on the tip of the linear motion member 142A in the direction D1. According to such a configuration, for example, it is possible to suppress that the tension of the cable 150 acts on the rotation preventing member 143A or the linear moving member 142A due to the inclination or the deviation of the cable 150. In addition, a projection (outer surface) may be provided in the rotation preventing member or the linear movement member, and a recess (opening, inner surface) may be provided in the transmission member. Further, as described above, the guide mechanism 145 does not have to include both the rotation preventing member 143A and the linear movement member 142A, and may include, for example, one of the rotation prevention member 143A and the linear movement member 142A.

Second Modified Example
FIG. 13 is a cross-sectional view of a part of an electric actuator 100B of the present modification. The configuration shown in FIG. 13 can be replaced with the corresponding portion of the electric actuator 100 of the above embodiment. In this modification, the motion conversion mechanism 140B has a linear motion member 142B in which the cable end 144B is integrated. A disc spring 146 is provided between the flange 144 b of the cable end 144 B and the rotation stopping member 143 as a compression spring that generates a repulsive force in the axial direction. In this case, as the cable 150 approaches the release position Pr, the axial reaction force by the disc spring 146 increases, and the torque of the motor 120 increases accordingly. Thus, for example, when the drive current of the motor 120 exceeds the threshold value, the control device 200 detects that the cable 150 has reached the release position Pr, and stops the supply of the drive current to the motor 120 at that time. be able to.

Third Modification
FIG. 14 is a perspective view of a part of an electric actuator 100C of the present modification. The configuration shown in FIG. 14 can be replaced with the corresponding portion of the electric actuator 100 of the above embodiment. In the present modification, the protrusion 143b of the anti-rotation member 143C functions as a leaf spring (compression spring) that generates a repulsive force in the axial direction. In this case, as the cable 150 approaches the release position Pr, the protrusion 143b is elastically deformed so that the curve of the protrusion 143b becomes large, whereby the axial reaction force by the protrusion 143b increases, and the torque of the motor 120 increases. Therefore, also in the present modification, the control device 200 detects that the cable 150 has reached the release position Pr, for example, when the drive current of the motor 120 exceeds the threshold, and at that time, the control device 200 sends Supply can be stopped. The repulsive force (elastic force, biasing force) and the spring constant can be adjusted by the specifications (number, shape, size, thickness, number, etc.) of the protrusion 143b. In the example of FIG. 14, as an example, the thickness of the tip portion of the protrusion 143 b is thinner than the thickness of the root portion.

The compression spring (biasing member, elastic member) that generates a repulsive force in the axial direction with the movement of the cable 150 is not limited to a disc spring or a plate spring, and may be, for example, a coil spring or an elastomer. . In addition, the compression spring can be interposed at various places such as between the flange 142 b of the linear moving member 142 and the flange 141 b of the rotating member 141 or between the flange 142 b of the linear moving member 142 and the body 112. In addition, the various compression springs exemplified in the present specification may be provided to the electric actuator 100 in which the cable end 144 and the linear motion member 142 can be axially separated as in the above embodiment. In this case, the compression spring can suppress, for example, sticking due to biting between the male screw 141 d and the female screw 142 d.

As mentioned above, although the embodiment of the present invention was illustrated, the above-mentioned embodiment is an example and it is not intended to limit the range of the present invention. The above embodiment can be implemented in other various forms, and various omissions, replacements, combinations, and changes can be made without departing from the scope of the invention. In addition, the specifications (structure, type, direction, type, size, length, width, thickness, height, number, placement, position, material, etc.) of each configuration, shape, etc. are appropriately changed. Can be implemented.

For example, the actuating member is not limited to a tension member such as a cable, but may be a pressing member such as a rod.

Also, for example, the actuating member may not pass through the through hole of the rotating member. In this case, the actuating member may detour radially outward of the ring gear. The rotating member may not have the through hole. Further, the male screw and the female screw may mesh with each other on the braking member side more than the ring gear.

Claims (7)

A braking member that brakes the drum rotor by being pressed by a drum rotor that rotates integrally with the wheel; a backing plate that supports the braking member; and an electric actuator that is provided on the backing plate and that operates the braking member. A braking device provided with
The electric actuator is
A motor with a rotating output shaft,
A rotating member which has an external thread and rotates in conjunction with the output shaft and rotates about the axial center of the external thread; and a linear moving member which has an internal thread meshing with the external thread and linearly moves with the rotation of the rotating member. Motion conversion mechanism,
An operating member that receives a force that operates the braking member from the linear moving member;
Have
The electric actuator is attached to the backing plate in a state where the motion conversion mechanism protrudes from a surface of the backing plate opposite to the braking member.
The rotating member is rotationally driven via a ring gear provided on the outer periphery of the rotating member and rotating in conjunction with the output shaft.
Brake equipment. The male screw and the female screw mesh with each other on the side of the ring gear opposite the braking member;
The brake device according to claim 1, wherein one end of the actuating member receives a force for actuating the braking member from the linear motion member, and the other end of the actuating member operates the braking member. The rotating member is provided with a through hole along the axis.
The actuating member penetrates the through hole,
The brake device according to claim 2, wherein the one end is located on the opposite side of the through hole to the braking member. The transmission member comprises a transmission member fixed to the actuating member and configured to be separable in the axial direction of the axial center from the linear movement member and transmitting a force for actuating the braking member from the linear movement member to the actuating member. The brake device according to any one of Items 1 to 3. The brake device according to claim 4, further comprising a movement restricting member that restricts the movement of the transmission member in a release direction in which the braking by the braking member is released. A control unit that controls the motor;
When the control unit operates the motor to move the actuating member in the release direction from the braking position in the braking state, the control unit rotates after the movement of the transmission member in the release direction is restricted by the movement restricting member. The brake device according to claim 5, wherein the motor is controlled such that the motor stops. The brake device according to claim 5 or 6, wherein the movement restricting member has a guide portion which guides the linear moving member in the axial direction of the axial center while restricting the rotation of the linear moving member.

Images