JP2017133537A - Brake for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake for a vehicle capable of more quickly towing a towing member at an initial period in start of towing the towing member, and towing the towing member with force to achieve required braking torque.SOLUTION: A brake for a vehicle includes a transmission mechanism constituted to change a reduction gear ratio, for example, by changing at least one of an outer diameter of a first rotating member at a first contact position and an outer diameter of a second rotating member at a second contact position, a towing member towing a brake member to brake a wheel, a motion converting mechanism for converting rotation of the second rotating member into straight motion in a towing direction of the towing member, and a position variable mechanism for changing an axial position of at least one of the first rotating member, the second rotating member and an endless belt so that the reduction gear ratio of the transmission mechanism is increased in accordance with increase of tensile force, by the tensile force from the towing member.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a vehicle brake.

  2. Description of the Related Art Conventionally, there is known a vehicle brake that has a motion conversion mechanism that converts the rotation of a motor into a linear motion of a cable and obtains a braking state by rotating the motor, pulling the cable, and moving a brake shoe (for example, patents). Reference 1). There is also known a vehicle brake having a speed reduction mechanism that decelerates the rotation of a motor and transmits it to a motion conversion mechanism.

Special table 2014-504711 gazette

  In such a vehicular brake, it is desirable to pull the cable quickly in order to eliminate the slack of the cable at the beginning when the cable starts to be pulled. However, if the reduction ratio of the speed reduction mechanism is set to be small in order to pull the cable quickly, a motor having a small output torque may have insufficient force for pulling the cable and the required braking torque may not be obtained.

  Accordingly, one of the problems of the present invention is that, for example, at the beginning of pulling the traction member, the traction member can be pulled more quickly, and the traction member is pulled with a force capable of obtaining a required braking torque. It is possible to obtain a vehicle brake.

  The vehicle brake of the present invention is wound around, for example, a motor, a first rotating member rotated by the motor, a second rotating member, the first rotating member, and the second rotating member. An endless belt that transmits rotation from the first rotating member to the second rotating member, and at least one of the first rotating member and the second rotating member is in contact with the endless belt. And at least one of the first rotating member, the second rotating member, and the endless belt moves in the axial direction, whereby the first rotating member, the endless belt, At least one of the outer diameter of the first rotating member at the first contact position and the outer diameter of the second rotating member at the second contact position between the second rotating member and the endless belt changes. And the reduction ratio is A speed change mechanism, a traction member that pulls the braking member to brake the wheel, and a motion conversion mechanism that converts the rotation of the second rotation member into a linear motion in the traction direction of the traction member And at least one of the first rotating member, the second rotating member, and the endless belt such that the reduction ratio in the transmission mechanism increases as the tensile force increases due to the tensile force from the pulling member. A position variable mechanism that changes the position in the axial direction.

  The vehicle brake has a speed change mechanism in which the reduction ratio increases as the pulling force of the traction member increases. The pulling force of the pulling member is small at the beginning of pulling and then increases. Therefore, in the vehicle brake described above, the speed reduction ratio of the speed change mechanism is small at the beginning of the pulling and then becomes large. Therefore, for example, the vehicle brake can pull the traction member more quickly at the beginning of the pulling of the traction member, and then the traction member with a force capable of obtaining a required braking torque by increasing the reduction ratio thereafter. Can be towed.

  In the vehicle brake, for example, the second rotating member is configured such that the axial position is changed by the tensile force.

  The vehicle brake can be configured more simply than, for example, when the position variable mechanism changes the axial position of the first rotating member or the traction member by the pulling force of the traction member.

  In the vehicle brake, for example, the position variable mechanism includes an elastic member that is elastically deformed by receiving the tensile force, and includes the first rotating member, the second rotating member, and the endless belt. At least one of the positions in the axial direction changes depending on the amount of deformation of the elastic member.

  In the vehicle brake, for example, the position of the first rotation member, the second rotation member, or the endless belt in the position variable mechanism in the axial direction, and the reduction ratio can be more easily adjusted by adjusting the elastic member. .

  In the vehicle brake, for example, the elastic member expands and contracts in the axial direction.

  The vehicle brake can be configured more simply than, for example, a case where an elastic member that elastically deforms in a direction different from the axial direction is included.

FIG. 1 is an exemplary and schematic rear view of a vehicle brake according to an embodiment from the rear of the vehicle. FIG. 2 is an exemplary schematic side view of the vehicle brake according to the embodiment from the outside in the vehicle width direction. FIG. 3 is an exemplary schematic side view of the operation of the braking member of the embodiment, and is a diagram in a non-braking state. FIG. 4 is an exemplary schematic side view of the operation of the braking member of the embodiment, and is a diagram in a braking state. FIG. 5 is an exemplary schematic cross-sectional view of the drive mechanism of the embodiment, and is a view in a non-braking state. FIG. 6 is an exemplary schematic cross-sectional view of the drive mechanism of the embodiment and is a diagram in a braking state. FIG. 7 is an exemplary and schematic graph showing the correlation between the traction amount and tension of the traction member of the vehicle brake according to the embodiment. FIG. 8 is an exemplary and schematic front view in a line of sight from the axial direction of the speed change mechanism of the embodiment.

  Hereinafter, exemplary embodiments of the present invention are disclosed. The configuration of the embodiment shown below, and the operation and result (effect) brought about by the configuration are examples. The present invention can be realized by configurations other than those disclosed in the following embodiments. According to the present invention, it is possible to obtain at least one of various effects (including derivative effects) obtained by the configuration.

  1 to 4, for the sake of convenience, the front in the vehicle front-rear direction is indicated by an arrow X, the outer side in the vehicle width direction (axle direction) is indicated by an arrow Y, and the upper side in the vehicle vertical direction is indicated by an arrow Z. .

  In the following, a case where the brake device 2 which is an example of a vehicle brake is applied to the left rear wheel (non-drive wheel) will be exemplified, but the present invention can be similarly applied to other wheels. It is.

<Brake device configuration>
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 configured as a drum brake. That is, as shown in FIG. 2, the brake device 2 includes arc-shaped brake shoes 3 on both the front and rear sides. A cylindrical drum 4 (see FIGS. 3 and 4) is provided around the brake device 2. The drum 4 rotates integrally with the wheel 1 around the 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 4. Thereby, the drum 4 and the wheel 1 are braked by the friction between the brake shoe 3 and the drum 4. The brake shoe 3 is an example of a braking member.

  The brake device 2 includes a wheel cylinder 51 (see FIG. 2) that operates by hydraulic pressure and a motor 120 (see FIG. 5) that operates by energization as actuators that move the brake shoe 3. Each of the wheel cylinder 51 and the motor 120 can move the two brake shoes 3. The wheel cylinder 51 is used for braking during traveling, for example, and the motor 120 is used for braking during parking, for example. That is, the brake device 2 is an example of an electric parking brake. The motor 120 may also be used for braking during traveling.

  As shown in FIGS. 1 and 2, the brake device 2 includes a disk-shaped back plate 6. The back plate 6 is provided in a posture intersecting with the vehicle width direction. That is, the back plate 6 extends substantially along a direction intersecting the vehicle width direction, specifically, substantially along a direction (XZ plane) orthogonal to the vehicle width direction. As shown in FIG. 1, the components of the brake device 2 are provided on both the outer side and the inner side of the back plate 6 in the vehicle width direction. The back plate 6 supports each component of the brake device 2 directly or indirectly. That is, the back plate 6 is an example of a support member. The back plate 6 is connected to a connection member (not shown) with the vehicle body. The connection member is, for example, a part of the suspension (for example, an arm, a link, an attachment member, etc.). The opening 6b provided in the back plate 6 shown in FIG. 2 is used for coupling with the connection member. The brake device 2 can also be used for drive wheels. When the brake device 2 is used for driving wheels, an axle shaft (not shown) passes through an opening 6c provided in the back plate 6 shown in FIG. The back plate 6 is made of, for example, a metal material.

  The wheel cylinder 51 and the brake shoe 3 shown in FIG. 2 are arranged on the outer side of the back plate 6 in the vehicle width direction. The brake shoe 3 is movably supported on the back plate 6. In the present embodiment, as shown in FIG. 3, for example, the lower end 3a of the brake shoe 3 is supported by the back plate 6 so as to be rotatable around the rotation center C1. The rotation center C1 is substantially parallel to the rotation center C of the wheel 1. The wheel cylinder 51 is supported on the upper end portion of the back plate 6. The wheel cylinder 51 has two movable parts (pistons) (not shown) that can project in the vehicle front-rear direction (left-right direction in FIG. 2). The wheel cylinder 51 causes the two movable parts to protrude in response to the pressurization. The two projecting movable parts push the upper end 3b of the brake shoe 3, respectively. Due to the protrusion of the two movable parts, the two brake shoes 3 rotate around the rotation center C1 and move so that the upper end parts 3b are separated from each other in the vehicle front-rear direction. As a result, the two brake shoes 3 move outward in the radial direction of the rotation center C of the wheel 1. A belt-like lining 31 along the cylindrical surface is provided on the outer periphery of each brake shoe 3. Therefore, the lining 31 and the inner peripheral surface 4a (see FIG. 4) of the drum 4 come into contact with each other by the movement of the two brake shoes 3 to the radially outer side of the rotation center C. Due to the friction between the lining 31 and the inner peripheral surface 4a, the drum 4 and thus the wheel 1 are braked. As shown in FIG. 2, the brake device 2 includes a return member 32. When the operation of pushing the brake shoe 3 by the wheel cylinder 51 is released, the return member 32 moves from the position where the two brake shoes 3 come into contact with the inner peripheral surface 4a of the drum 4 (braking position Pb, see FIG. 4). The drum 4 is moved to a position (non-braking position Pn, initial position, see FIG. 3) that does not contact the inner peripheral surface 4a of the drum 4. The return member 32 is an elastic member such as a coil spring, for example, and gives each brake shoe 3 a force in a direction approaching the other brake shoe 3, that is, a force in a direction away from the inner peripheral surface 4 a of the drum 4. .

<Configuration and operation of moving mechanism>
Further, the brake device 2 includes a moving mechanism 8 (see FIGS. 3 and 4) that moves the two brake shoes 3 from the non-braking position Pn to the braking position Pb. The moving mechanism 8 is provided outside the back plate 6 in the vehicle width direction. As shown in FIGS. 2 to 4, the moving mechanism 8 includes a lever 81 (not shown in FIG. 2), a cable 82, and a strut 83. The lever 81 is one of the two, for example, between the brake shoe 3L on the left side of FIG. 2 and the back plate 6, so as to overlap the brake shoe 3L and the back plate 6 in the axial direction of the center of rotation C of the wheel 1. Is provided. The lever 81 is supported by the brake shoe 3L so as to be rotatable around the rotation center C2. The rotation center C2 is located on the side of the brake shoe 3L away from the rotation center C1, that is, on the upper end in FIG. 3, and is substantially parallel to the rotation center C and the rotation center C1. The cable 82 moves the lower end portion 81a on the side farther from the rotation center C2 of the lever 81, for example, in a direction approaching the brake shoe 3R on the right side in FIG. The cable 82 moves substantially along the back plate 6. The strut 83 is interposed between the lever 81 and the brake shoe 3R different from the brake shoe 3L on which the lever 81 is supported, and stretches 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 C2 and the connection position P2 between the cable 82 and the lever 81. The cable 82 is an example of an operation member that moves the brake shoe 3 and an example of a pulling member.

  In such a moving mechanism 8, when the cable 82 is pulled and moved to the right side in FIGS. 3 and 4, the lever 81 moves in a direction approaching the brake shoe 3 </ b> R as shown in FIG. 4 (arrow a). The lever 81 pushes the brake shoe 3R through the strut 83 (arrow b). As a result, the brake shoe 3R rotates around the rotation center C1 from the non-braking position Pn (FIG. 3) (arrow c) and moves to a position in contact with the inner peripheral surface 4a of the drum 4 (braking position Pb, FIG. 4). . In this state, the connection position P2 between the cable 82 and the lever 81 corresponds to the power point, the rotation center C2 corresponds to the fulcrum, and the connection position P1 between the lever 81 and the strut 83 corresponds to the action point. Further, when the brake shoe 3R is in contact with the inner peripheral surface 4a and the lever 81 moves to the right side in FIGS. 3 and 4, that is, the strut 83 pushes the brake shoe 3R (arrow a), the strut 83 is stretched. Accordingly, the brake shoe 3L rotates counterclockwise in FIGS. 3 and 4 (arrow d) with the connection position P1 with the strut 83 as a fulcrum. As a result, the brake shoe 3L rotates around the rotation center C1 from the non-braking position Pn (FIG. 3) and moves to a position (braking position Pb, FIG. 4) in contact with the inner peripheral surface 4a of the drum 4. In this manner, the brake shoes 3L and 3R are moved from the non-braking position Pn to the braking position Pb by the operation of the moving mechanism 8. In the state after the brake shoe 3R contacts the inner peripheral surface 4a of the drum 4, the connection position P1 between the lever 81 and the strut 83 serves as a fulcrum. The amount of movement of the brake shoes 3L, 3R is very small, for example, 1 mm or less.

<Drive mechanism>
The driving mechanism 100 shown in FIGS. 1, 2, 5 and 6 moves the two brake shoes 3 from the non-braking position Pn to the braking position Pb via the moving mechanism 8 (see FIGS. 3 and 4). As shown in FIGS. 1 and 2, the drive mechanism 100 is located on the inner side in the vehicle width direction of the back plate 6 and is fixed to the back plate 6. The cable 82 shown in FIGS. 2 to 4 passes through an opening (not shown) provided in the back plate 6.

  As shown in FIG. 5, the drive mechanism 100 includes a housing 110, a motor 120, a speed change mechanism 130, a motion conversion mechanism 140, and a position variable mechanism 150.

  The housing 110 supports the motor 120, the speed change mechanism 130, the motion conversion mechanism 140, and the position variable mechanism 150. The housing 110 can be configured to include a plurality of members. In this case, the plurality of members can be combined and integrated by a coupling tool (not shown) such as a screw. A housing chamber R surrounded by a wall 111 is provided in the housing 110. The motor 120, the speed change mechanism 130, the motion conversion mechanism 140, and the position variable mechanism 150 are accommodated in the accommodation chamber R and covered with the wall portion 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 motor 120 is an example of an actuator, and includes a case 121 and a housing component housed in the case 121. The housing components include, for example, a stator, a rotor, a coil, and a magnet (not shown) in addition to the shaft 122. The shaft 122 protrudes from the case 121 in a direction D1 along the first rotation center Ax1 of the motor 120. The direction D1 is rightward in FIG. The motor 120 is driven by driving power based on the control signal, and rotates the shaft 122. The shaft 122 can also be referred to as an output shaft.

  The speed change mechanism 130 includes a first pulley 131, a second pulley 132, and an endless belt 133. In transmission mechanism 130, rotation of first pulley 131 by motor 120 is transmitted to second pulley 132 via endless belt 133. The speed change mechanism 130 can be referred to as a speed reduction mechanism or a rotation transmission mechanism. The pulley can be called a roller or a sheave.

  The first pulley 131 is supported by the shaft 122 of the motor 120 and rotates integrally with the shaft 122. The first pulley 131 can be referred to as a drive pulley. The first pulley 131 is an example of a first rotating member.

  The second pulley 132 is supported by the housing 110 so as to be rotatable around a second rotation center Ax2 parallel to the first rotation center Ax1. The second pulley 132 can be referred to as a driven pulley. The second pulley 132 is an example of a second rotating member.

  The endless belt 133 is configured in an endless shape (annular or ring shape) and is wound around the first pulley 131 and the second pulley 132. That is, the first pulley 131 and the second pulley 132 are inscribed in the endless belt 133. The endless belt 133 rolls with the rotation of the first pulley 131 and rotates the second pulley 132. The endless belt 133 may be, for example, a rubber belt or a steel belt, or may be an assembly of a belt and a plurality of elements arranged in a column supported by the belt. The endless belt 133 has elasticity.

  As shown in FIG. 5, the outer peripheral surface 131a of the first pulley 131 and the outer peripheral surface 132a of the second pulley 132 are conical. The outer peripheral surface 131a is inclined with respect to the first rotation center Ax1, and the outer diameter of the outer peripheral surface 131a is smaller toward the direction D1. The outer peripheral surface 132a is inclined with respect to the second rotation center Ax2, and the outer diameter of the outer peripheral surface 132a is smaller toward the direction D1. The angle between the generatrix of the outer peripheral surface 131a of the first pulley 131 and the first rotation center Ax1, and the angle between the generatrix of the outer peripheral surface 132a of the second pulley 132 and the second rotation center Ax2 are substantially the same. It is. The outer peripheral surfaces 131a and 132a are an example of a peripheral surface. The outer peripheral surfaces 131a and 132a may be referred to as contact surfaces, contact surfaces, and friction surfaces.

  Further, as shown in FIG. 5, the endless belt 133 has an inner peripheral surface 133a, an outer peripheral surface 133b, and an end surface 133c. The inner peripheral surface 133a contacts the outer peripheral surface 131a of the first pulley 131 at the first contact position Pc1, and contacts the outer peripheral surface 132a of the second pulley 132 at the second contact position Pc2. The inner peripheral surface 133a is inclined with respect to the first rotation center Ax1 and the second rotation center Ax2. The inner diameter of the inner circumferential surface 133a is smaller toward the direction D1 in a free state where the endless belt 133 is detached from the transmission mechanism 130 and held in an annular shape. In the free state, the angle between the bus line of the inner peripheral surface 133a and the center line is the angle between the bus bar of the outer peripheral surface 131a of the first pulley 131 and the first rotation center Ax1, and the angle of the second pulley 132. The angle between the generatrix of the outer peripheral surface 132a and the second rotation center Ax2 is substantially the same. The bus bar of the outer peripheral surface 133b is parallel to the first rotation center Ax1 and the second rotation center Ax2 in a state where the endless belt 133 is incorporated in the transmission mechanism 130. The end surface 133c is along a plane substantially orthogonal to the first rotation center Ax1 and the second rotation center Ax2 in a state where the endless belt 133 is incorporated in the transmission mechanism 130. The cross section orthogonal to the circumferential direction of the endless belt 133 is trapezoidal.

  The first pulley 131 has a guide portion 131b. The guide portion 131b protrudes radially outward from two axial end portions of the outer peripheral surface 131a, and is annular and plate-shaped. The two guide portions 131b are arranged at a distance slightly larger than the width of the endless belt 133 in the axial direction. The endless belt 133 is located between the two guide portions 131b. The guide part 131b restricts the endless belt 133 from moving (displaced) in the axial direction along the outer peripheral surface 131a of the first pulley 131.

  The housing 110 has a guide portion 112. The guide part 112 has a planar guide surface 112a orthogonal to the axial direction. The guide surface 112a faces the end surface 133c of the endless belt 133, and can support the endless belt 133 so as to be slidable. The two guide portions 112 are arranged at a distance slightly larger than the width of the endless belt 133 in the axial direction. The endless belt 133 is located between the two guide portions 112. The guide portion 112 restricts the endless belt 133 from moving (displaced) in the axial direction. The guide part 112 may be a part of the wall part 111 as the outer wall of the housing 110, or may be provided separately from the outer wall.

  The motion conversion mechanism 140 includes a rotating member 141, a linear motion member 142, and an elastic member 143.

  The rotating member 141 rotates around the second rotation center Ax2. The rotating member 141 has a second pulley 132. Therefore, the structures of the speed change mechanism 130 and the motion conversion mechanism 140 can be further simplified as compared with the case where the rotating member 141 and the second pulley 132 are separate members. The second pulley 132 is located in the intermediate portion of the rotating member 141 in the axial direction. The rotating member 141 is supported by the housing 110 so as to be rotatable about the second rotation center Ax2, and is supported so as to be movable along the axial direction of the second rotation center Ax2. Portions on both axial sides of the rotating member 141 with the second pulley 132 interposed therebetween are supported by the housing 110 via bearings 114, respectively. The bearing 114 is, for example, a metal bush.

  The rotation member 141 is provided with a through-hole 141a having a substantially circular cross section that penetrates along the second rotation center Ax2. A female screw is provided in the through hole 141a. That is, the through hole 141a can be referred to as a female screw portion or a female screw hole.

  The linear motion member 142 extends along the second rotational center Ax2 and penetrates the rotational member 141. The linear motion member 142 includes a rod-like portion 142a and a connecting portion 142b.

  The rod-like portion 142a is inserted into the through hole 141a of the rotating member 141. The rod-like portion 142a has a substantially circular cross section. The rod-like portion 142a is provided with a male screw that meshes with a female screw provided in the through hole 141a of the rotating member 141. That is, the rod-like portion 142a can be referred to as a male screw portion.

  The connecting portion 142 b is connected to the end portion 82 a of the cable 82 by the connecting member 144. The connecting member 144 passes through the end portion 82 a and the connecting portion 142 b of the cable 82. The connecting member 144 is a pin, for example.

  Of the connecting portion 142b and the rod-like portion 142a, the end portion on the connecting portion 142b side is accommodated in a cylindrical portion 113 provided in the housing 110. The cylindrical portion 113 extends along the second rotation center Ax2. A groove 113 a is provided on the inner surface of the cylindrical portion 113. The groove 113a extends with a substantially constant width and depth along the second rotation center Ax2. The groove 113a is provided at two locations across the second rotation center Ax2. The end of the connecting member 144 in the longitudinal direction is inserted into the groove 113a. The circumferential width of the second rotation center Ax2 of the groove 113a is set to be slightly larger than the width of the end of the connecting member 144 in the longitudinal direction. Therefore, the connection member 144 and the circumferential surface of the groove 113a contact each other, so that the rotation of the connection member 144 and thus the linear motion member 142 around the second rotation center Ax2 is limited. In addition, the structure which couple | bonds the linear motion member 142 and the cable 82 is not limited to the example of FIG.

  In such a configuration, the rotation of the shaft 122 of the motor 120 is transmitted to the rotating member 141 via the speed change mechanism 130, and when the rotating member 141 rotates, the female screw provided in the through hole 141 a of the rotating member 141 moves linearly. Due to the engagement of the member 142 with the male screw and the limitation of the rotation of the linear motion member 142 by the housing 110 in the groove 113a, the linear motion member 142 is in the non-braking position Pn (FIG. 5) along the axial direction of the second rotation center Ax2. ) And the braking position Pb (FIG. 6). Of the cylindrical portion 113 of the housing 110, the portion provided with the groove 113 a is an example of a rotation limiting portion that limits the rotation of the connecting member 144, and thus the linear motion member 142 around the second rotation center Ax <b> 2. It is also an example of the guide part which guides 144, and by extension, the linear motion member 142 along the axial direction of 2nd rotation center Ax2.

  In the motion conversion mechanism 140, when the linear motion member 142 moves from the non-braking position Pn (FIG. 5) to the braking position Pb (FIG. 6) with the rotation of the rotational member 141, the rotational member 141 passes through the linear motion member 142. The cable 82 is pulled in the direction opposite to the direction D1, that is, leftward in FIGS. At this time, the rotating member 141 receives a reaction force from the linear motion member 142 in the direction D1. The reaction force is a tensile force that acts on the rotating member 141 from the cable 82 via the linear motion member 142.

  The elastic member 143 is configured to be elastically deformed by a tensile force acting on the rotating member 141 from the cable 82 via the linear motion member 142. In the present embodiment, for example, the elastic member 143 is positioned between the surface 141b of the rotating member 141 and the surface 111a of the wall portion 111 of the housing 110, and the second rotation center Ax2 is the central axis, and the second The coil spring elastically expands and contracts along the rotation center Ax2. When receiving the force in the direction D1 from the rotating member 141, the elastic member 143 is elastically contracted along the second rotation center Ax2. The elastic member 143 is accommodated in a recess 141c provided on the rotating member 141 and opened in the direction D1. The elastic member 143 is disposed so as to wind the linear motion member 142 at intervals. A bearing 145 is interposed between the elastic member 143 and the rotating member 141. The bearing 145 is, for example, a thrust washer. The bearing 145 may be interposed between the elastic member 143 and the surface 111a of the housing 110, or may be a needle bearing.

  Here, in a situation where the linear motion member 142 is located at the non-braking position Pn, no tension is applied to the cable 82 and the cable 82 is loose. Therefore, in a state where the linear motion member 142 is located at or near the non-braking position Pn, that is, at the beginning of the pulling of the linear motion member 142 and the cable 82 due to the rotation of the rotary member 141, the linear motion member 142 The reaction force acting on the rotating member 141, and hence the force acting on the elastic member 143 from the rotating member 141, is relatively small and close to 0 (zero). When the rotating member 141 further rotates and the linearly moving member 142 moves from the non-braking position Pn in the direction opposite to the direction D1, loosening of the cable 82 is eliminated and tension is generated in the cable 82.

  FIG. 7 is a graph showing an example of the correlation between the pulling amount of the cable 82 and the tension of the cable 82. When the brake shoe 3 is pressed against the drum 4 by pulling the cable 82, the brake shoe 3 and the drum 4 are elastically deformed, and the amount of elastic deformation increases as the pressing amount increases. That is, as shown in FIG. 7, the tension of the cable 82 increases as the pulling amount of the cable 82 increases. Therefore, as the linear motion member 142 moves from the non-braking position Pn to the braking position Pb, the tensile force that acts on the linear motion member 142 from the cable 82, the reaction force that acts on the rotational member 141 from the linear motion member 142, and thus the rotational member. The force acting on the elastic member 143 from 141 increases. Therefore, as shown in FIGS. 5 and 6, the elastic member 143 moves to the second rotation center Ax2 as the linear movement member 142 moves in the direction opposite to the direction D1 from the non-braking position Pn to the braking position Pb. Compressed along.

  As the elastic member 143 is compressed, the rotating member 141 moves in the direction D1. Here, as described above, the rotating member 141 has the second pulley 132, and the outer diameter of the second pulley 132 is smaller toward the direction D1, and the shaft of the endless belt 133 is guided by the guide portions 112, 131b and the like. Movement in the direction, that is, the direction D1 or the direction opposite to the direction D1, is restricted. Therefore, as will be apparent from comparison between FIGS. 5 and 6, the position where the endless belt 133 is wound around the second pulley 132 as the rotating member 141 moves in the direction D <b> 1, that is, the outer peripheral surface of the second pulley 132. The outer diameter of the outer peripheral surface 132a at the second contact position Pc2 in contact with 132a gradually increases. In the speed change mechanism 130, the reduction ratio increases as the diameter of the outer peripheral surface 132a of the second pulley 132 increases. Therefore, in transmission mechanism 130, the reduction ratio of transmission mechanism 130 is relatively small at the beginning of towing of cable 82, and the reduction ratio of transmission mechanism 130 increases as the pulling of cable 82 proceeds.

  According to the above-described embodiment, the cable 82 (traction member) can be pulled more quickly at the beginning of starting to pull the cable 82, and the required braking can be performed by increasing the reduction ratio in the transmission mechanism 130 thereafter. The drive mechanism 100 capable of pulling the cable 82 with a force capable of obtaining torque is obtained. Thereby, for example, it is not necessary to provide the motor 120 having a larger torque. Therefore, for example, an effect of suppressing an increase in the size of the motor 120 and thus the size of the drive mechanism 100 or suppressing an increase in power consumption by the motor 120 can be obtained. In the present embodiment, the rotating member 141 and the elastic member 143 are examples of the position variable mechanism 150.

  In the present embodiment, the second pulley 132 (second rotating member) is configured to be movable along the second rotation center Ax2 (axial direction). Therefore, for example, the position variable mechanism 150 and the speed change mechanism 130 are configured so that the first pulley 131 or the endless belt 133 is movable and the speed is changed by the movement of the first pulley 131 or the endless belt 133. The motion conversion mechanism 140 and thus the drive mechanism 100 can be configured more simply.

  In the present embodiment, the position variable mechanism 150 includes the elastic member 143, and the axial position of the second pulley 132 (second rotating member) changes according to the deformation amount of the elastic member 143. Therefore, for example, by adjusting the elastic member 143, the position of the second pulley 132 in the position variable mechanism 150 in the axial direction, and hence the speed reduction ratio of the speed change mechanism 130 can be adjusted more easily.

  In the present embodiment, the elastic member 143 expands and contracts along the second rotation center Ax2. Therefore, for example, compared to the case where the elastic member 143 has an elastic member that elastically deforms in a direction different from the direction along the second rotation center Ax2, the position variable mechanism 150, the speed change mechanism 130, the motion conversion mechanism 140, As a result, the drive mechanism 100 can be configured more simply.

  Further, as shown in FIG. 5, in a state where the linear motion member 142 is positioned at the non-braking position Pn, the rotating member 141 applies an elastic force (compression reaction force) from the elastic member 143 in the direction opposite to the direction D1. It is pressed against the stopper 115. The stopper 115 can also be referred to as an inward flange or a hook. The stopper 115 restricts the rotation member 141 from moving in the direction opposite to the direction D1. The elastic member 143 is compressed by being sandwiched between the stopper 115 and the wall 111 in a state where the cable 82 is not pulled, that is, in a state where the linear motion member 142 is located at the non-braking position Pn, Preload (initial load, preset load) is applied. With such a configuration, the pulling of the cable 82 by the drive mechanism 100 is started, and until the rotating member 141 starts moving in the direction D1 after the tension of the cable 82 overcomes the preload, that is, the drive mechanism 100 pulls the cable 82. At the beginning of pulling, the rotating member 141 is maintained at the non-braking position Pn, and as a result, the second contact position Pc2 having a small outer diameter on the outer peripheral surface 132a of the second pulley 132 as shown in FIG. 5 is maintained. That is, according to such a configuration, at the beginning of the drive mechanism 100 starting to pull the cable 82, the speed change mechanism 130 maintains a relatively small reduction ratio (the state of FIG. 5). The cable 82 can be pulled more quickly. Further, the movement of the rotating member 141, the linear motion member 142, the cable 82, and the like in the housing 110 is suppressed, and the generation of sound and vibration due to these movements can be suppressed. As shown in FIG. 7, the preload magnitude Fp (traction amount Xp) is set to be larger than 0 and smaller than the braking tension Fb (traction amount Xb) acting in the braking state. It is set to be smaller than 1/2 of the braking tension Fb.

  FIG. 8 is a front view of the speed change mechanism 130 viewed from the axial direction. As shown in FIG. 8, the speed change mechanism 130 includes a tension roller 134 that increases the tension of the endless belt 133. In the tension roller 134, the endless belt 133 is elastically pressed in the direction of arrow D2 by the elastic member 135, and thereby the endless belt 133 is elastically pressed in the direction of arrow D2. The tension roller 134 can prevent the endless belt 133 from slackening and consequently the rotation from being transmitted by the endless belt 133 even when the position where the endless belt 133 is wound around the second pulley 132 changes. it can.

  As mentioned above, although embodiment of this invention was illustrated, the said embodiment is an example to the last, Comprising: It is not intending limiting the range of invention. The above embodiment can be implemented in various other forms, and various omissions, replacements, combinations, and changes can be made without departing from the spirit of the invention. In addition, the specifications (structure, type, direction, shape, size, length, width, thickness, height, number, arrangement, position, material, etc.) of each configuration, shape, etc. are appropriately changed. Can be implemented.

  For example, in the above embodiment, the brake device is configured as a leading trailing drum brake, but the present invention can also be configured as other types of brake devices. Further, the present invention can be implemented as a configuration corresponding to the other actuator of a brake device having a disc brake by one actuator and a drum brake by another actuator.

  Further, the position variable mechanism is configured to change not the second rotating member (second pulley) but the axial position of the first rotating member or the endless belt according to the tension of the traction member (cable). May be. In this case, for example, the first rotating member or the guide portion of the endless belt is supported so as to be movable in the axial direction within the housing, and the position variable mechanism operates the arm, the lever, or the like that moves the first rotating member or the guide portion. You may have a member. The position variable mechanism may change the outer diameter of the first rotating member at the first contact position, or the outer diameter of the first rotating member at the first contact position and the second contact position. Both the outer diameter of the second rotating member may be changed. In addition, the peripheral surface of the first rotating member and the second rotating member whose outer diameter does not change at the contact position by the position variable mechanism may not be conical.

  The elastic member is not limited to a coil spring, and may be, for example, a torsion spring, an elastomer, a leaf spring, or the like. Further, the specifications of the elastic member are not limited to the above embodiment.

  DESCRIPTION OF SYMBOLS 2 ... Brake device (brake for vehicles), 82 ... Cable (traction member), 120 ... Motor, 130 ... Transmission mechanism, 131 ... First pulley (first rotating member), 132 ... Second pulley (second rotation) Members), 133 ... endless belts, 131a, 132a ... outer peripheral surface (peripheral surface), 140 ... motion conversion mechanism, 141 ... rotating member (position variable mechanism), 143 ... elastic member (position variable mechanism), 150 ... position variable mechanism , Pc1 ... first contact position, Pc2 ... second contact position.

Claims (4)

A motor,
The first rotating member rotated by the motor, the second rotating member, the first rotating member and the second rotating member wound from the first rotating member to the second rotating member An endless belt that transmits rotation to the first rotation member, and at least one of the first rotation member and the second rotation member has a conical circumferential surface in contact with the endless belt, and the first rotation The first rotating member at a first contact position between the first rotating member and the endless belt when at least one of the member, the second rotating member, and the endless belt moves in the axial direction. The speed change ratio is configured such that at least one of the outer diameter of the second rotating member and the outer diameter of the second rotating member at the second contact position between the second rotating member and the endless belt changes to change the reduction ratio. Mechanism,
A traction member that pulls the braking member to brake the wheel;
A motion conversion mechanism that converts the rotation of the second rotating member into a linear motion in the pulling direction of the pulling member;
At least one of the first rotating member, the second rotating member, and the endless belt so that the reduction ratio in the speed change mechanism increases as the tensile force increases due to the tensile force from the pulling member. A variable position mechanism for changing the position of the two axial directions;
Brake for vehicles equipped with.   2. The vehicle brake according to claim 1, wherein the second rotating member is configured to change a position in the axial direction by the tensile force. 3. The position variable mechanism has an elastic member that elastically deforms in response to the tensile force,
The position in the axial direction of at least one of the first rotating member, the second rotating member, and the endless belt changes according to a deformation amount of the elastic member. The brake for vehicles as described.   The vehicle brake according to claim 3, wherein the elastic member expands and contracts in the axial direction.

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