JP2009298215A - Webbing take-up device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a webbing take-up device capable of enhancing the durability of an overload mechanism. <P>SOLUTION: In the webbing take-up device, a spiral spring 192 is provided on the inner side of a large diameter gear 184 constituting an overload mechanism 186. The spiral spring 192 is held by the large diameter gear 184 by pressing an outer circumferential part thereof against an inner circumferential part of the large diameter gear 184 by the elastic force, and an inner side end in the spiral direction is locked to a small diameter gear 190. When the large diameter gear 184 is rotated in one direction (the direction of an arrow C) around the axis and the rotational force in the other direction (the direction of an arrow D) around the axis is applied to the small diameter gear 190, the spiral spring 192 is seamed to permit the relative rotation of the small diameter gear 190 with respect to the large diameter gear 184. Thus, the relative rotation of the small diameter gear 190 to the large diameter gear 184 can be permitted without sliding the spiral spring 192 and the large diameter gear 184. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a webbing take-up device that winds and stores a webbing for restraining a vehicle occupant around a take-up shaft, and more particularly to a webbing take-up device that can rotate a take-up shaft by a driving force of a motor.

Conventionally, a webbing take-up device having a configuration in which an overload mechanism is interposed between a take-up shaft and a motor is known (see, for example, Patent Document 1). In this webbing take-up device, a large-diameter side gear that is rotated by the driving force of the motor, a small-diameter side gear that is arranged inside the large-diameter side gear and rotates in conjunction with the spool, and an outer periphery of the small-diameter side gear And a plurality of limit springs assembled to the portion, and these limit springs are elastically deformed to allow relative rotation between the large-diameter side gear and the small-diameter side gear.
WO2006-123750

  However, in the webbing take-up device configured as described above, when relative rotation between the large-diameter side gear and the small-diameter side gear is allowed (when the overload mechanism is activated), a plurality of limit springs are provided on the inner wall of the large-diameter side gear. Therefore, there is a problem that the durability is lowered due to wear of the structural members accompanying the sliding.

  An object of the present invention is to obtain a webbing take-up device capable of improving the durability of an overload mechanism in consideration of the above facts.

  A webbing take-up device according to a first aspect of the invention is a take-up device that winds a webbing for restraining a vehicle occupant by being rotated in the take-up direction, and is rotated in the draw-out direction by being pulled out. A shaft, a motor, and an overload mechanism interposed between the winding shaft and the motor, and the overload mechanism is rotated to one side around the axis line by transmitting the driving force of the motor. And a large-diameter rotating body having an inner peripheral portion concentric with its own rotation axis, and provided coaxially and relatively rotatably with respect to the large-diameter rotating body, and the winding shaft in the winding direction. A small-diameter rotating body that is rotated around one axis in conjunction with the rotation and rotated to the other around the axis in conjunction with rotation in the pull-out direction of the winding shaft, and is formed in a spiral shape by a spring material, The outer peripheral part is elastically The large-diameter rotating body is held by the large-diameter rotating body by being pressed against the inner peripheral portion of the radial-rotating body, and the large-diameter of the small-diameter rotating body is locked by winding the inner end in the spiral direction to the small-diameter rotating body. And a spiral spring that allows relative rotation around the axis of the rotating body to the other.

  In the webbing take-up device according to claim 1, when the large-diameter rotating body of the overload mechanism is rotated around the axis by the motor, the rotational force of the large-diameter rotating body is applied to the small-diameter rotating body via the spiral spring. The small-diameter rotating body is transmitted to one side around the axis. As a result, the winding shaft is rotated in the winding direction so that the webbing is wound around the winding shaft, and the occupant restraint by the webbing is improved.

  In addition, for example, when the winding shaft is rotated in the pulling-out direction by the pulling force acting on the webbing in the middle of the winding (that is, in a state where the large-diameter rotating body is rotated around the axis by the motor), The small diameter rotating body is rotated relative to the other around the axis with respect to the large diameter rotating body while tightening the spiral spring. Thereby, the component on the motor side of the large-diameter rotating body can be separated from the rotation of the winding shaft, and the pulling force can be absorbed by the spiral spring as elastic energy.

  Moreover, since the relative rotation of the small-diameter rotating body with respect to the large-diameter rotating body is allowed by tightening the spiral spring, the outer peripheral portion of the spiral spring is the inner peripheral portion of the large-diameter rotating body in order to allow the relative rotation. It can suppress sliding with respect to. Accordingly, it is possible to suppress the wear of the large-diameter rotating body or the like due to such sliding, so that the durability of the overload mechanism can be improved.

  A webbing take-up device according to a second aspect of the present invention is the webbing take-up device according to the first aspect, wherein the webbing take-up device is connected to the take-up shaft, rotates integrally with the take-up shaft, and exceeds a predetermined value. A torsion shaft that twists and deforms when a torsional load is applied; and a lock mechanism that restricts rotation of the torsion shaft in the pull-out direction at a predetermined opportunity. When the output acts, the torsion shaft is torsionally deformed to allow the winding shaft to rotate in the pull-out direction, and the spiral spring releases the holding of the large-diameter rotating body when the rotation is permitted. The outer peripheral portion slides with the inner peripheral portion of the large-diameter rotating body.

  In the webbing take-up device according to claim 2, when the lock mechanism restricts the rotation of the torsion shaft in the pull-out direction at a predetermined opportunity (for example, when the vehicle is suddenly decelerated), the take-up shaft connected to the torsion shaft. Is restricted from rotating in the pull-out direction. In this state, for example, if a pulling force exceeding a predetermined value acts on the webbing due to the inertial force acting on the occupant, the torsion shaft is torsionally deformed, allowing the take-up shaft to rotate in the pull-out direction, and occupant inertial energy. Is absorbed. When the rotation is allowed, the spiral spring is released from the large diameter rotating body, and the outer peripheral portion of the spiral spring slides with the inner peripheral portion of the large diameter rotating body. Thereby, relative rotation of the small-diameter rotating body with respect to the large-diameter rotating body is allowed, and the spool can be rotated in the pull-out direction independently of the motor.

  As described above, in this webbing take-up device, when the torsion shaft is torsionally deformed (in an emergency), the outer peripheral portion of the spiral spring slides with the inner peripheral portion of the large-diameter rotating body. Sometimes, the pulling force (overload) of the webbing can be absorbed by the tightening of the spiral spring. Therefore, it is possible to suppress a decrease in durability of the overload mechanism due to sliding between the outer peripheral portion of the spiral spring and the inner peripheral portion of the large-diameter rotating body.

  The webbing take-up device according to a third aspect of the present invention is the webbing take-up device according to the first or second aspect, wherein the spiral spring has an inner side in the spiral direction outside the central portion in the spiral direction. In comparison, the spring constant is set low.

  In the webbing take-up device according to claim 3, since the spiral spring is favorably held by the large-diameter rotating body by the outer portion in the spiral direction having a high spring constant, the spiral spring slides unnecessarily with respect to the large-diameter rotating body. It can suppress moving. In addition, the spiral spring can allow relative rotation of the small-diameter rotating body with respect to the large-diameter rotating body by easily winding and tightening the inner portion in the spiral direction with a low spring constant, and can ensure energy absorption.

  As described above, in the webbing take-up device according to the present invention, the durability of the overload mechanism can be improved.

  FIG. 1 is a schematic exploded perspective view showing the overall configuration of a webbing take-up device 10 according to an embodiment of the present invention. FIG. 2 is a schematic exploded perspective view showing a partial configuration of the webbing take-up device 10.

  The webbing take-up device 10 according to this embodiment includes a frame 12 having a U-shaped cross section. The frame 12 includes a flat plate-like back wall 12C, and the back wall 12C is fixed to the vehicle body, for example, in the vicinity of the lower end portion of the center pillar of the vehicle by a fastening means (not shown) such as a bolt. A winding device 10 is attached to the vehicle body. One side wall 12A and the other side wall 12B extend in parallel with each other from both ends in the width direction of the back plate 12C. A connecting piece 14 is bridged between the upper end of one side wall 12A and the upper end of the other side wall 12B, and this connecting piece 14 is fixed to the vehicle body. The connecting piece 14 is formed with an insertion hole 16 through which a webbing 20 described later is inserted. A circular through hole 13 is formed in one side wall 12A of the frame 12, and a substantially circular through hole 15 is formed in the other side wall 12B.

  A cylindrical spool 18 as a take-up shaft is rotatably supported between one side wall 12A and the other side wall 12B of the frame 12. A base end portion of a long belt-like occupant restraining webbing 20 is locked to the spool 18 by a columnar shaft 22, and the spool 18 is rotated around its axis (see arrow A in FIG. 1, hereinafter this). When the direction is referred to as “winding direction”), the webbing 20 is wound around the outer peripheral portion of the spool 18 from the base end side. On the other hand, when the webbing 20 is pulled from the tip side, the webbing 20 is pulled out while the spool 18 rotates around the axis to the other side (see arrow B in FIG. 1) (hereinafter, the spool 18 when the webbing 20 is pulled out). The direction of rotation is referred to as the “drawing direction”).

  A torsion shaft 24 (energy absorbing member) that constitutes a force limiter mechanism is disposed at the axial center of the spool 18. The torsion shaft 24 is made of a metal material such as iron, and is provided with a torsional deformable portion 23 that can be torsionally deformed by applying a torsional load of a predetermined value or more, and the other end of the torsionally deformable portion 23 (in FIG. 2). And a support shaft 25 provided coaxially and integrally on the left end). The support shaft portion 25 penetrates the through hole 15 of the other side wall 12B in a non-contact state and protrudes to the outside (other side) of the frame 12.

  In addition, a screw portion provided in the adapter 26 is screwed into one end portion (the right end portion in FIG. 2) of the torsion deforming portion 23, and the end portion of the torsion deforming portion 23 and the spool are screwed by the adapter 26. One end of 18 is integrally connected. As a result, the torsion shaft 24 rotates integrally with the spool 18. The adapter 26 penetrates the through hole 13 of the one side wall 12A in a non-contact state and protrudes to the outside (one side) of the frame 12.

  A lock gear 28 constituting a force limiter mechanism is provided on the other side of the spool 18 (left side in FIG. 2). The lock gear 28 is disposed in the through hole 15 of the other side wall 12 </ b> B and is locked to the other end portion of the torsional deformation portion 23. The lock gear 28 rotates integrally with the torsion shaft 24 and the spool 18 except when the torsional deformation portion 23 is torsionally deformed. Ratchet teeth 30 are formed on the outer periphery of the lock gear 28. Further, a circular knurled hole 32 is formed at the center of the lock gear 28. The knurled hole 32 is opened to the other side, and the entire inner peripheral surface of the knurled hole 32 is knurled to form a knurled surface 34.

  A lock member 46 is bridged between one side wall 12A and the other side wall 12B of the frame 12, and a lock plate 48 is provided at the other end (the left end in FIG. 2) of the lock member 46. ing. The lock plate 48 is rotatably supported at one end below the gear case 52 described below, and the lock plate 48 is disposed obliquely below the lock gear 28. A lock tooth 50 is formed at the other end of the lock plate 48, and the lock plate 48 meshes with the position where the lock tooth 50 is separated from the ratchet tooth 30 of the lock gear 28 and the lock tooth 50 meshes with the ratchet tooth 30 of the lock gear 28. It is possible to rotate between these positions.

  Here, in a state where the lock teeth 50 of the lock plate 48 are engaged with the ratchet teeth 30 of the lock gear 28, the lock gear 28, the torsion shaft 24, and the spool 18 are prevented from rotating in the pull-out direction. Moreover, in this locked state, the load acting on the spool 18 from the webbing 20 is transmitted to the frame 12 via the torsion shaft 24, the lock gear 28, and the lock plate 48 (lock member 46). In other words, the load acting on the spool 18 is supported by the frame 12 in the locked state. The lock plate 48 is usually disposed at a position where the lock teeth 50 are separated from the ratchet teeth 30 of the lock gear 28.

  A gear case 52 is provided outside the other side wall 12 </ b> B of the frame 12, and the gear case 52 covers the other side of the lock gear 28. A circular hole 54 is formed at the center of the gear case 52, and the circular hole 54 exposes the knurled hole 32 of the lock gear 28. The circular hole 54 is formed to have a sufficiently larger diameter than the support shaft portion 25 of the torsion shaft 24, and the support shaft portion 25 passes through the circular hole 54 coaxially.

  A pretensioner mechanism 56 is provided outside the other side wall 12B of the frame 12 (on the side opposite to the spool 18). The pretensioner mechanism 56 has a pinion 58 disposed on the other side of the gear case 52. The pinion 58 is made of a metal material such as iron, and has a gear portion 60 having outer teeth formed on the outer peripheral portion.

  A cylindrical cam portion 62 is provided coaxially and integrally on one side of the gear portion 60, and irregularities are alternately formed on the outer periphery of the cam portion 62. The cam portion 62 is inserted into the knurled hole 32 through the circular hole 54 of the gear case 52 and is not in contact with the knurled surface 34, so that the lock gear 28 can rotate independently of the pinion 58. The cam portion 62 corresponds to a clutch plate 64 described later.

  Further, on the other side of the gear portion 60, a cylindrical rotation support shaft portion 61 is provided coaxially and integrally. The rotation shaft 61 passes through a circular hole 81 formed in a cover plate 80 described later and is locked by a snap ring 83, and the pinion 58 is rotatably supported by the cover plate 80.

  Further, a circular hole portion 63 penetrating along the axial direction is formed in the axial center portion of the pinion 58 (the gear portion 60, the cam portion 62, and the rotation support portion 61). The part 25 penetrates coaxially.

  On the other hand, the pretensioner mechanism 56 has a clutch plate 64, and the clutch plate 64 is disposed between the gear case 52 and the pinion 58. A plurality of engagement claws 66 are formed on the center side of the clutch plate 64, and each engagement claw 66 protrudes from the clutch plate 64 to one side. Each meshing claw 66 is fitted in each concave portion of the cam portion 62 described above, whereby the clutch plate 64 is attached to the pinion 58. Each engaging claw 66 is inserted into the knurled hole 32 together with the cam portion 62 via the circular hole 54 of the gear case 52 and is not in contact with the knurled surface 34, so that the lock gear 28 rotates independently of the clutch plate 64. It is possible.

  Further, the pretensioner mechanism 56 includes an operation source 67. The operating source 67 has a substantially L-shaped cylindrical cylinder 68, and the cylinder 68 is fixed to the outside of the other side wall 12 </ b> B of the frame 12 below the pinion 58. A gas generator 70 is provided at a lower end of the cylinder 68 and a bottomed cylindrical generator cap 72 is fixed. The gas generator 70 is attached to the cylinder 68 with the generator cap 72 covered. The lower end is closed.

  The operating source 67 has a piston 74, and the piston 74 is inserted into the cylinder 68 from the upper end. An O-ring 76 is provided at the lower end of the piston 74, and the O-ring 76 seals between the lower end of the piston 74 and the cylinder 68. Further, a rack 78 is formed at a portion other than the lower end of the piston 74.

  Furthermore, the pretensioner mechanism 56 has a cover plate 80 having a substantially triangular prism container shape, and the cover plate 80 is fixed to the outside of the other side wall 12B. As described above, the pinion 64 is rotatably supported in the circular hole 81 of the cover plate 80, and the support shaft part 25 penetrating the hole 63 of the pinion 58 protrudes to the other side of the cover plate 80. . One side surface and the lower surface of the cover plate 80 are opened. The cover plate 80 accommodates the pinion 58, the clutch plate 64, and the upper portion of the piston 74 therein, and the gear case 52 between the other side wall 12B. Is holding.

  On the other side of the pretensioner mechanism 56, a lock mechanism 82 is provided. The lock mechanism 82 has a box-shaped housing 84 opened on one side. The housing 84 is made of a resin material, and is attached to the opposite side of the other side wall 12B from the spool 18. A circular bearing hole 85 is formed in the bottom wall of the housing 84, and the other end portion of the support shaft portion 25 (the other end portion of the torsion shaft 24) that penetrates the hole portion 63 of the pinion 58 in a non-contact state. The bearing hole 85 is rotatably supported.

  On the other hand, the other side of the housing 84 is covered with a box-shaped sensor cover 86 opened on one side, and the sensor cover 86 is fixed to the housing 84 and the other side wall 12B of the frame 12.

  An acceleration sensor 88 is held at the lower portion of the housing 84, and the acceleration sensor 88 is disposed in a gap between the housing 84 and the sensor cover 86. The acceleration sensor 88 has a placement unit 90. A concave portion having a substantially inverted conical shape is formed on the upper surface of the mounting portion 90, and a sphere 92 is placed in the concave portion of the mounting portion 90. A movable claw 94 is rotatably supported above the sphere 92, and the movable claw 94 is placed on the sphere 92.

  A V gear 96 is provided in the gap between the housing 84 and the sensor cover 86, and the V gear 96 is integrally connected to the other end portion of the support shaft portion 25 so as to be integrated with the torsion shaft 24. Rotate to. Ratchet teeth 98 are formed on the outer periphery of the V gear 96.

  A W pawl 100 is rotatably supported by the V gear 96, and a W mass 102 is fixed to the W pawl 100. A sensor spring 104 is stretched between the V gear 96 and the W pawl 100, and the sensor spring 104 urges the V gear 96 in the winding direction with respect to the W pawl 100.

  In the gap between the housing 84 and the sensor cover 86, a substantially disk-shaped gear sensor 106 is provided on the other side of the V gear 96, and the gear sensor 106 can rotate to the other end of the support shaft portion 25. It is supported by. A coil spring 108 is spanned between the gear sensor 106 and the inner surface of the sensor cover 86, and the coil spring 108 biases the gear sensor 106 in the winding direction.

  An engaging claw 110 is rotatably supported on the lower side of the gear sensor 106, and the engaging claw 110 has a rotation center axis parallel to the axial direction of the torsion shaft 24 and the V gear 96. The ratchet teeth 98 can be engaged with each other. Further, a pressing piece 112 is formed on the lower side of the gear sensor 106 on the other side.

  On the other hand, as shown in FIG. 1, a clutch housing 114 is attached to the outside (one side) of one side wall 12 </ b> A of the frame 12. The clutch housing 114 is formed in a box shape that opens toward the side (one side) opposite to the one side wall 12 </ b> A, and the opening is closed by a cover 116. A circular through hole 118 is formed in the side wall portion 114 </ b> A of the clutch housing 114, and the adapter 26 described above passes through the through hole 118 coaxially.

  The adapter 26 includes a hexagonal column-shaped main body portion 26A, and a cylindrical support shaft portion 26B is provided coaxially and integrally on one side (the opposite side of the spool 18) of the main body portion 26A. The support shaft portion 26B passes through a through hole 116A formed in the cover 116 and protrudes to the outside (one side) of the clutch housing 114.

  On one side of the clutch housing 114, a resin spring cover 120 is provided. The spring cover 120 is formed in a substantially bottomed cylindrical shape with the other side (the cover 116 side) opened, and is attached to the one side wall 12 </ b> A via the clutch housing 114. A support shaft portion 26B of the adapter 26 is inserted inside the spring cover 120, and the support shaft portion 26B is rotatably supported by a bearing portion (not shown) provided on the spring cover 120.

  A spiral spring (not shown) is housed inside the spring cover 120. In this spiral spring, the outer end in the spiral direction is locked to the spring cover 120, and the inner end in the spiral direction is locked to the support shaft portion 26 </ b> B, and the spool 18 is connected via the adapter 26 and the torsion shaft 24. Energized in the winding direction.

  On the other hand, the clutch 122 is accommodated in the clutch housing 114 described above. The clutch 122 includes a gear wheel 124. The gear wheel 124 is formed in a bottomed cylindrical shape having a short axial dimension with one side (the cover 116 side) opened. The opening of the gear wheel 124 is closed by a disc-shaped cover 125. In addition, external teeth are formed on the outer periphery of the gear wheel 124. The external teeth correspond to a gear 200 described later.

  As shown in FIG. 3, a substantially cylindrical ratchet 126 is coaxially arranged with respect to the gear wheel 124 inside the gear wheel 124. The ratchet 126 is rotatably supported at one end in the axial direction in a circular hole formed in the gear wheel 124, and is rotatably supported in a circular hole formed in the cover 125 at the other end in the axial direction. Yes. As a result, the ratchet 126 can rotate relative to the gear wheel 124 and the cover 125.

  A fitting hole 127 having a hexagonal cross section is formed in the axial center portion of the ratchet 126. In the fitting hole 127, the main body portion 26A (see FIG. 1) of the adapter 26 is fitted. As a result, the ratchet 126 and the spool 18 are coupled so as not to be relatively rotatable, and the gear wheel 124 and the cover 125 are supported by the adapter 26 via the ratchet 126. A plurality of ratchet teeth 128 are formed at regular intervals on the outer periphery of the ratchet 126.

  Further, a pair of cylindrical bosses 129 are formed on the gear wheel 124 outside the ratchet 126 in the radial direction. These bosses 129 are arranged on opposite sides of each other via a ratchet 126, and a pawl 130 is attached to each boss 129.

  Each pawl 130 includes a main body 132. The main body 132 is formed in a ring shape, and the pawl 130 is rotatably supported around the boss 129 by fitting the boss 129 inside the main body 132. A connecting piece 134 is provided on a part of the outer periphery of the main body 132.

  Each connecting piece 134 extends to the winding direction side of the spool 18 (the arrow A direction side in FIG. 3) with respect to the main body 132 in a state where the main body 132 is pivotally supported by the boss 129. Further, each connecting piece 134 is rotated by a predetermined angle around the boss 129 in the winding direction, whereby the tip 134A is engaged with the ratchet teeth 128 of the ratchet 126 described above. In this meshing state, the rotational force in the winding direction of the gear wheel 124 is transmitted to the ratchet 126 via the pawl 130, and the ratchet 126 is rotated integrally with the gear wheel 124 in the winding direction. . The tip 134A of each connecting piece 134 is inclined with a portion facing the surface of the ratchet teeth 128 on the winding direction side, and is inclined in the winding direction of the ratchet 126 with respect to the gear wheel 124 even in the meshing state. Is allowed to rotate relative to each other.

  A release piece 136 extends from the outer peripheral portion of each main body 132. The release piece 136 is generally formed on the opposite side of the connecting piece 134 with the main body 132 interposed therebetween, and a portion of the gear wheel 124 facing outward in the radial direction is an inclined slope. By rotating the release piece 136 in the pull-out direction, the connecting piece 134 is rotated in a direction away from the outer peripheral portion of the ratchet 126.

  Further, the clutch 122 includes a rotating plate 140. The rotating plate 140 is rotatably supported with respect to the ratchet 126. A pair of blocks 146 are formed on the rotating plate 140. These blocks 146 are arranged on opposite sides of each other via the ratchet 126. A spring accommodating portion 148 is formed on the outer peripheral portion of one of the pair of blocks 146, and the compression coil spring 150 is accommodated in the spring accommodating portion 148.

  The end portion of the compression coil spring 150 on the winding direction side is in contact with the wall portion 148 </ b> A of the spring accommodating portion 148. The end portion of the compression coil spring 150 on the pulling direction side is in contact with a contact wall 152 that extends from the inner peripheral portion of the peripheral wall 96 of the gear wheel 124 and enters the spring accommodating portion 148.

  Since the rotating plate 140 is rotatably supported with respect to the ratchet 126, the rotating plate 140 is basically rotatable relative to not only the ratchet 126 but also the gear wheel 124. However, as described above, the end portion on the winding direction side of the compression coil spring 150 is in contact with the wall portion 148A of the spring accommodating portion 148, and the end portion on the drawing direction side is in contact with the contact wall 152 of the gear wheel 124. . For this reason, when the gear wheel 124 attempts to rotate relative to the rotating plate 140 in the winding direction, the abutment wall 152 presses the rotating plate 140 in the winding direction via the compression coil spring 150 to cause the rotating plate 140 to move. The gear wheel 124 is rotated following the rotation.

  As a result, relative rotation in the winding direction of the gear wheel 124 with respect to the rotating plate 140 is limited unless a rotating force with a magnitude that can resist the biasing force of the compression coil spring 150 acts on the rotating plate 140.

  A pressing piece 154 is provided on the inner peripheral portion of each block 146. These pressing pieces 154 are arranged on the winding direction side of the pawl 130, and are directed to the block 146 along the peripheral wall 156 formed in the block 146 so as to be coaxially curved with respect to the circular hole 144 (that is, , Relative to the rotating plate 140).

  A compression coil spring 158 as an urging member is provided on the opposite side of the pressing piece 154 from the pawl 130. The compression coil spring 158 is arranged in a curved state along the peripheral wall 156. One end of the compression coil spring 158 is engaged with and connected to the end of the pressing piece 154 opposite to the pawl 130. On the other hand, the other end of the compression coil spring 158 is in contact with the contact wall 160 formed on the rotating plate 140 on the side opposite to the pressing piece 154.

  A slope 164 is formed at the outer end in the width direction of the connecting piece 134 of each pawl 130 corresponding to each pressing piece 154. The inclined surface 164 is inclined outward in the radial direction of the gear wheel 124 with respect to the winding direction. When the tip 134A is not in contact with the outer peripheral portion of the ratchet 126, the inclined surface 164 extends along the circumferential direction of the gear wheel 124 and the rotating plate 140. It faces the pressing piece 154.

  The pressing piece 154 is formed so that the gear wheel 124 contacts the inclined surface 164 when the gear wheel 124 rotates relative to the rotating plate 140 in the winding direction by a predetermined amount. When the relative rotation in the winding direction with respect to 140 is attempted, the inclined surface 164 is pressed in the pulling direction by the pressing piece 154, and the pawl 130 rotates around the boss 129 in the winding direction by this pressing force.

  In addition, a pressing portion 166 is formed at the end of each block 146 in the winding direction along the circumferential direction of the rotating plate 140, and a release piece is located closer to the axial center of the rotating plate 140 than the pressing portion 166. A housing portion 168 is formed. The pressing portion 166 is formed corresponding to the release piece 136 of the pawl 130 along the circumferential direction of the rotating plate 140.

  The release piece 136 is gradually curved toward the axial center side of the gear wheel 124 from the connecting portion (base end portion) to the main body 132 toward the distal end side, and the widthwise outer surface thereof is similarly curved. Therefore, when the gear wheel 124 rotates relative to the rotating plate 140 by a predetermined amount in the pull-out direction, the pressing portion 166 contacts the outer side surface of the release piece 136 in the width direction. When the wheel 124 rotates relative to the pull-out direction, the pressing portion 166 presses the distal end portion of the release piece 136 in the winding direction.

  The tip of the release piece 136 is an inclined slope. For this reason, when the pressing portion 166 presses the tip of the release piece 136, the pawl 130 is rotated around the boss 129 in the pull-out direction and guided to the release piece housing portion 168.

  The clutch 122 having the above-described configuration includes a brake mechanism (not shown) that restricts the rotation of the rotating plate 140 by a frictional force. When the gear wheel 124 rotates in the winding direction, the clutch 122 rotates between the gear wheel 124 and the rotating plate 140. Rotation occurs.

  When the gear wheel 124 rotates relative to the rotating plate 140 by a predetermined amount or more in the winding direction, the pressing piece 154 provided on the block 146 of the rotating plate 140 contacts the connecting piece 134 of the pawl 130. In this state, when the gear wheel 124 further attempts to rotate relative to the rotating plate 140 in the winding direction, the pressing piece 154 presses the slope 164 of the connecting piece 134 in the pulling direction.

  The pressing force applied to the inclined surface 164 acts in the pull-out direction and inward in the radial direction of the rotating plate 140 and the gear wheel 124, and this radially inward action causes the pawl 130 to wind around the boss 124. Rotate. By rotating the pawl 130 around the boss 124 in the winding direction, the corner portion of the tip 134A is brought into contact with the outer peripheral portion of the ratchet 126, and in this state, until it comes into contact with the adjacent ratchet teeth 128 on the winding direction side. It rotates in the winding direction around the center of the gear wheel 124 together with the gear wheel 124.

  Next, in this state, the tip 134A comes into contact with the ratchet teeth 128, and further, when the gear wheel 124 rotates in the winding direction, the tip 134A of the pawl 130 presses the ratchet teeth 128 in the winding direction, thereby ratchet 126, and eventually the spool. 18 is rotated in the winding direction.

  On the other hand, a reduction gear train 170 is accommodated inside the clutch housing 114 described above. The reduction gear train 170 includes a spur gear 172. The gear 172 is housed inside the clutch housing 114 in a state where the axial direction is along the axial direction of the spool 18.

  The gear 172 is fixed to the output shaft 176 of the motor 174 to which the clutch housing 114 is attached. A spur gear 178 having a larger diameter than that of the gear 172 is provided on the side of the rotational radius direction of the gear 172. A support shaft 180 is formed in the clutch housing 114 corresponding to the gear 178. The support shaft 180 has an axial direction along the axial direction of the spool 18, and the gear 178 is rotatably supported by the support shaft 180 while meshing with the gear 172.

  A spur gear 182 having a smaller diameter than the gear 178 is formed coaxially and integrally with the gear 178 on the axial direction side of the gear 178. A large-diameter gear 184 (large-diameter rotating body) having a diameter larger than that of the gear 182 is provided on the side of the rotational radius direction of the gear 182. The large diameter gear 184 constitutes an overload mechanism 186 (torque limiter mechanism).

  As shown in FIG. 4, the large-diameter gear 184 includes a main body portion 184A formed in a bottomed cylindrical shape having a bottom wall on one side, and the main body portion 184A has an opening on the other side as a clutch housing. It arrange | positions in the state which opposes 114 A side wall part 114A. A cylindrical bearing portion 184B is provided inside the main body portion 184A. The bearing portion 184B protrudes from the bottom wall of the main body portion 184A toward the other side (opening side) of the main body portion 184A, and is provided coaxially and integrally with the main body portion 184A. A support shaft 188 provided in the clutch housing 114 is inserted inside the bearing portion 184B. The support shaft 188 has an axial direction along the axial direction of the spool 18, and the large-diameter gear 184 has a spur tooth externally formed on the outer peripheral portion of the main body 184 </ b> A meshed with the gear 182. Is supported rotatably.

  On the other side of the large-diameter gear 184, a small-diameter gear 190 (small-diameter rotating body) having a smaller diameter than the large-diameter gear 184 is disposed. The small diameter gear 190 is formed in a cylindrical shape, and a bearing portion 184B of the large diameter gear 184 is rotatably fitted therein. Thereby, the small diameter gear 190 is supported coaxially and relatively rotatable with respect to the large diameter gear 184.

  The small-diameter gear 190 has a cylindrical portion 190A disposed inside the main body portion 184A, and a gear portion 190B provided coaxially and integrally on the other side of the cylindrical portion 190A. The gear portion 190B protrudes to the outside (other side) of the main body portion 184A, and spur teeth are formed on the outer peripheral portion of the gear portion 190B.

  An annular gap is formed between the outer peripheral part of the cylindrical part 190A and the inner peripheral part of the main body part 184A, and a spiral spring 192 formed in a spiral shape by a leaf spring is provided in this gap. Yes. The spiral spring 192 has an outer diameter dimension in a natural state larger than an inner diameter dimension of the main body portion 184A, and is assembled to the inner side of the main body portion 184A in a state of being tightened so that the outer diameter dimension is reduced. It has been. For this reason, the spiral spring 192 presses the outer peripheral portion against the inner peripheral portion of the main body portion 184A by an elastic force, and is held by the main body portion 184A by the frictional force generated between the main body portion 184A.

  Further, a locking portion 194 that protrudes inward in the radial direction is formed at the inner end of the spiral spring 192 in the spiral direction. The locking portion 194 is inserted into a locking groove 196 formed in the cylindrical portion 190A of the small diameter gear 190. Thereby, the spiral direction inner end of the spiral spring 192 is connected to the small-diameter gear 190 so as not to be relatively rotatable.

  In the overload mechanism 186 configured as described above, when the large-diameter gear 184 rotates around one axis (in the direction of arrow C in FIG. 4), the rotational force of the large-diameter gear 184 is transmitted to the small-diameter gear 190 via the spiral spring 192. The small-diameter gear 190 follows the large-diameter gear 184 and rotates around one axis (in the direction of arrow C in FIG. 4) (see FIG. 5). 5 to 7, for convenience of explanation, the illustration of the gear portion 190B of the small-diameter gear 190 is omitted, and the provision of hatching to the cylindrical portion 190A and the bearing portion 184B is omitted.

  In addition, when a rotational force directed toward the other side (in the direction of arrow D in FIG. 4) that exceeds the elastic force of the spiral spring 192 acts on the small diameter gear 190, the spiral spring 192 is wound and tightened, whereby the small diameter gear with respect to the large diameter gear 184 is obtained. A relative rotation around the axis of 190 to the other is allowed (see FIG. 6). In this case, the spiral spring 192 is restricted from rotating relative to the large-diameter gear 184 by a static friction force acting between its outer peripheral portion and the inner peripheral portion of the main body portion 184A. When the force becomes excessive, the outer peripheral portion of the spiral spring 192 slides with the inner peripheral portion of the main body portion 184A, and the spiral spring 192 rotates relative to the large diameter gear 184 together with the small diameter gear 190. (See FIG. 7).

  On the other hand, the clutch housing 114 is formed with a support shaft 198 whose axial direction is along the axial direction of the spool 18. The support shaft 198 supports a spur gear 200 having a larger diameter than the small-diameter gear 190. The shaft 198 is rotatably supported. The gear 200 is meshed with the gear portion 190B of the small diameter gear 190. Further, a spur gear (not shown) is coaxially and integrally formed on the other side of the gear 200, and this gear meshes with the gear wheel 124 of the clutch 122 described above. As a result, the rotation of the output shaft 176 of the motor 174 is transmitted to the gear wheel 124 via the reduction gear train 170.

  When the motor 174 rotates the output shaft 176 in the forward direction, the large-diameter gears 184 and 190 of the overload mechanism 186 are rotated around one axis (in the direction of arrow C in FIG. 4), and the gear wheel 124 is wound in the winding direction (see FIG. 1 (in the direction of arrow A). Further, when the motor 174 reversely rotates the output shaft 176, the large-diameter gears 184 and 190 of the overload mechanism 186 are rotated around the axis in the other direction (the direction of arrow D in FIG. 4), and the gear wheel 124 is pulled out (in FIG. 1). It is rotated in the direction of arrow A).

  Next, the operation of this embodiment will be described.

  In the webbing retractor 10 having the above configuration, for example, based on the detection result of a front monitoring means (not shown) such as a radar distance measuring device or an infrared distance measuring device, the front of the vehicle on which the webbing retractor 10 is mounted. When a control means (not shown) such as an ECU determines that the distance to an obstacle such as another vehicle that is running or stopped is less than a certain value, the control means drives the motor 174 to rotate forward. When the output shaft 176 rotates normally by the normal driving force of the motor 48, the normal rotation of the output shaft 176 is transmitted to the large-diameter gear 184 of the overload mechanism 186 via the gears 172, 178, 182 of the reduction gear train 170. The large-diameter gear 184 is rotated around one axis (in the direction of arrow C in FIG. 5). The rotation of the large-diameter gear 184 in one direction around the axis is transmitted to the small-diameter gear 190 via the spiral spring 192, and the small-diameter gear 190 is rotated around the axis in one direction (arrow C direction in FIG. 5). The rotation of 190 is transmitted to the gear wheel 124 of the clutch 122 via the gear 200 and a gear (not shown), and the gear wheel 124 is rotated in the winding direction.

  When the gear wheel 124 rotates in the winding direction, the pawl 130 attached to the gear wheel 124 rotates in the winding direction together with the gear wheel 124, and the pressing piece 154 provided on the block 146 of the rotating plate 140 is the tip of the pawl 130. 134A is rotated to the ratchet 126 side. Thus, the tip 134A of the pawl 130 is engaged with the ratchet teeth 128 of the ratchet 126, and relative rotation of the gear wheel 124 with respect to the ratchet 126 in the winding direction is restricted.

  When the gear wheel 124 is further rotated in the winding direction in this state, the ratchet 126 is rotated in the winding direction together with the gear wheel 124. Since the ratchet 126 is connected to the spool 18 via the adapter 26 and the torsion shaft, when the ratchet 126 rotates in the winding direction, the spool 18 rotates in the winding direction, and the webbing 20 has its longitudinal direction proximal end side. Is wound around the spool 18. Thereby, slight slackness of the webbing 20 attached to the occupant's body, so-called “slack”, is eliminated, and the restraint of the occupant by the webbing 20 is improved.

  At this time, when the vehicle suddenly decelerates, for example, when the occupant operates the brakes of the vehicle, the sphere 92 of the acceleration sensor 88 of the lock mechanism 82 moves through the concave portion of the mounting portion 90 to the anti-acceleration direction. Ascend and push up the movable claw 94. As a result, the movable claw 94 rotates the engagement claw 110 of the gear sensor 106 and meshes with the ratchet teeth 98 of the V gear 96, whereby the gear sensor 106 is connected to the V gear 96. In this state, when the webbing 20 is pulled out by an inertial force or the like acting on the occupant, the V gear 96 and the gear sensor 106 are slightly rotated in the pulling direction via the spool 18 and the torsion shaft 24.

  Thus, the gear sensor 106 is rotated somewhat in the pull-out direction, whereby the pressing piece 112 of the gear sensor 106 rotates the lock plate 48 of the lock member 46 to the lock gear 28 side. As a result, a pulling load is applied from the occupant to the webbing 20 and a rotational force is applied to the spool 18, the torsion shaft 24 and the lock gear 28 in the pulling direction, whereby the lock teeth 50 of the lock plate 48 are ratchet teeth of the lock gear 28. 30, the lock gear 28 is prevented from rotating in the pull-out direction, and the webbing 20 is prevented from being pulled out.

  Here, since the spool 18 is somewhat rotated in the pull-out direction until the webbing 20 is prevented from being pulled out as described above, the gear wheel 124 connected to the spool 18 via the pawl 130 or the like is used. It is rotated somewhat in the drawing direction. At this time, the small-diameter gear 190 of the overload mechanism 186 is provided with a rotational force directed to the other around the axis via the gear 200 and the gear 200 (not shown) meshed with the gear wheel 124. In this case, as shown in FIG. 6, the spiral spring 192 is tightened by the rotational force, thereby allowing relative rotation of the small diameter gear 190 around the axis of the large diameter gear 184 to the other. As a result, the constituent member closer to the motor 174 than the large-diameter gear 184 can be separated from the rotation of the spool 18, and the rotational force (that is, the pulling force acting on the webbing 20) can be absorbed by the spiral spring as elastic energy. it can.

  As described above, when the spool 18 is slightly rotated in the pull-out direction, the lock teeth 50 of the lock plate 48 are engaged with the ratchet teeth 30 of the lock gear 28, and thereafter, the load acting on the spool 18 (acting on the webbing 20). Is pulled by the frame 12.

  On the other hand, when it is determined that the possibility of collision of the vehicle is high based on the detection result of the forward monitoring means, the control means described above operates the gas generator 70 of the pretensioner mechanism 56 and puts the high pressure in the cylinder 68. Of gas. As a result, the piston 74 protrudes from the cylinder 68, the rack 78 of the piston 74 is engaged with the pinion teeth 60 of the pinion 58, and the pinion 58 is rotated in the winding direction. For this reason, the pinion 58 is rotated relative to the clutch plate 64, and the meshing claws 66 of the clutch plate 64 are fitted to the convex portions of the cam portion 62 of the pinion 58, whereby each meshing of the clutch plate 64 is engaged. The claw 66 is moved radially outward of the clutch plate 64 and meshes with the knurled surface 34 of the lock gear 28 (the pinion 58 and the lock gear 28 are connected). As a result, the clutch plate 64 and the lock gear 28 are rotated in the winding direction integrally with the pinion 58, whereby the torsion shaft 24 and the spool 18 are rotated in the winding direction integrally with the lock gear 28. As a result, the webbing 20 is forcibly wound around the spool 18 and the restraining force of the occupant by the webbing 20 is further increased.

  In this state, for example, when the vehicle collides with a collision object and the inertial force of the occupant is input to the webbing 20, a large rotational force directed in the pull-out direction is applied to the spool 18. As a result, when the torsional load applied to the torsion shaft 24 exceeds a predetermined value, the torsional deformation portion 23 of the torsion shaft 24 is torsionally deformed, so that the spool 18 is rotated in the pull-out direction independently of the lock gear 28. . Thereby, the webbing 20 is allowed to be pulled out by a predetermined amount, and the inertia energy of the occupant is absorbed.

  Here, when the spool 18 is rotated in the pull-out direction as described above, the gear wheel 124 connected to the spool 18 via the pawl 130 or the like is rotated in the pull-out direction. A rotational force is applied to 190 around the axis toward the other side. When this rotational force becomes larger than the maximum static frictional force acting between the outer peripheral portion of the spiral spring 192 and the inner peripheral portion of the main body portion 184A of the large diameter gear 184, the outer peripheral portion of the spiral spring 192 has a large diameter. It slides with the inner periphery of the main body 184A of the gear 184 (see FIG. 7). As a result, relative rotation of the small-diameter gear 190 with respect to the large-diameter gear 184 is allowed, and components on the motor 174 side relative to the large-diameter gear 184 can be separated from rotation of the spool 18. This allows the spool 18 to rotate in the pull-out direction independently of the motor 174.

  As described above, in this embodiment, when the torsion shaft 24 is torsionally deformed (in an emergency), the outer periphery of the spiral spring 192 slides with the inner periphery of the main body 184A of the large-diameter gear 184. During normal use other than the above, the pulling force acting on the webbing 20 is absorbed by the tightening of the spiral spring 192. Therefore, the large-diameter gear 184 can be prevented from being worn as the spiral spring 192 and the large-diameter gear 184 slide, whereby the durability of the overload mechanism 186 can be greatly improved.

  In addition, in the present embodiment, the overload mechanism 186 is actuated depending on whether the spiral spring 192 is tightened or the outer peripheral portion of the spiral spring 192 slides with the inner peripheral portion of the main body portion 184A of the large-diameter gear 184. Therefore, in any case, it is possible to suppress the generation of operating noise and vibration. Therefore, passenger comfort can be ensured.

  In this embodiment, since the overload mechanism 186 has a simple configuration in which the spiral spring 192 is disposed between the large diameter gear 184 and the small diameter gear 190, the number of components is small and the manufacture is easy. Further, since the overload mechanism 186 can be configured to be lightweight and compact, the degree of freedom in layout when the overload mechanism 186 is incorporated in the reduction gear train 170 or the like can be improved.

  In the above-described embodiment, for example, the spiral dimension of the spiral spring 192 is smaller than the central part in the spiral direction by configuring the width dimension (or thickness dimension) of the spiral spring 192 to be narrower toward the inner side of the spiral direction. The inner side may be configured to have a lower spring constant than the outer side in the spiral direction. In this case, the spiral spring 192 is satisfactorily held by the large-diameter gear 184 by the outer portion in the spiral direction with a high spring constant, so that the spiral spring 192 can be prevented from sliding unnecessarily with respect to the large-diameter gear 184. In addition, the spiral spring 192 can allow relative rotation of the small-diameter gear 190 with respect to the large-diameter gear 184 by easily winding and tightening the inner portion in the spiral direction with a low spring constant, and can ensure energy absorption. .

  In the above embodiment, the spiral spring 192 is formed by a leaf spring. However, the present invention is not limited to this, and the spiral spring may be formed by a wire spring material.

1 is a schematic exploded perspective view showing an overall configuration of a webbing take-up device according to an embodiment of the present invention. 1 is a schematic exploded perspective view showing a partial configuration of a webbing take-up device according to an embodiment of the present invention. It is a front view which shows the structure of the principal part of the clutch which is a structural member of the webbing winding apparatus which concerns on embodiment of this invention. It is a disassembled perspective view of the overload mechanism which is a structural member of the webbing take-up device according to the embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating a configuration of a main part of the overload mechanism illustrated in FIG. 4 and illustrating a state in which a small-diameter gear is rotated by a rotational force of a large-diameter gear transmitted through a spiral spring. FIG. 5 is a cross-sectional view illustrating a configuration of a main part of the overload mechanism illustrated in FIG. 4 and illustrating a state in which relative rotation of a small-diameter gear with respect to a large-diameter gear is permitted by winding a spiral spring. FIG. 4 shows the configuration of the main part of the overload mechanism shown in FIG. 4, in which the outer peripheral part of the spiral spring slides with the inner peripheral part of the large-diameter gear so that the relative rotation of the small-diameter gear with respect to the large-diameter gear is allowed It is sectional drawing for demonstrating.

Explanation of symbols

10 Webbing take-up device 18 Spool (winding shaft)
20 Webbing 24 Torsion shaft 82 Lock mechanism 174 Motor 184 Large diameter gear (large diameter rotating body)
186 Overload mechanism 190 Small-diameter gear (small-diameter rotating body)
192 spiral spring

Claims (3)

A webbing for restraining a vehicle occupant is wound by being rotated in the winding direction, and a winding shaft that is rotated in the pulling direction when the webbing is pulled out, a motor, and the winding shaft and the motor. An overload mechanism interposed therebetween,
The overload mechanism is
A driving force of the motor is transmitted and rotated around one axis, and a large-diameter rotating body having an inner peripheral portion concentric with its own rotation axis,
Coaxially and relatively rotatable with respect to the large-diameter rotating body, and is rotated around one axis in conjunction with the rotation of the winding shaft in the winding direction, and the withdrawal of the winding shaft A small-diameter rotating body that rotates around the axis in conjunction with rotation in the direction,
It is formed in a spiral shape by a spring material, and is held by the large-diameter rotating body by pressing the outer peripheral portion against the inner peripheral portion of the large-diameter rotating body by an elastic force, and the inner end in the spiral direction becomes the small-diameter rotating body. A spiral spring that allows relative rotation to the other around the axis of the small-diameter rotating body with respect to the large-diameter rotating body by being locked and tightened;
A webbing take-up device comprising:   A torsion shaft that is coupled to the take-up shaft, rotates integrally with the take-up shaft, and twists and deforms when a torsional load greater than or equal to a predetermined value is applied thereto; A lock mechanism that restricts the rotation of the take-up shaft, and when a pulling force exceeding a predetermined value acts on the webbing in the restricted state, the torsion shaft is torsionally deformed to allow the take-up shaft to rotate in the pull-out direction. The spiral spring is released from the holding of the large-diameter rotating body when the rotation is permitted, and an outer peripheral portion slides with an inner peripheral portion of the large-diameter rotating body. The webbing take-up device described in 1.   3. The webbing take-up device according to claim 1, wherein the spiral spring has a spring constant set lower in a spiral direction inner side than in a spiral direction outer side than in a spiral direction central portion.

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