JP4890487B2 - Seat belt retractor - Google Patents

Description

  The present invention relates to a seat belt retractor, and more particularly to a seat belt retractor with a pretensioner and a force limiter mechanism.

  In recent years, seat belt retractors have a pretensioner that effectively winds up the belt in the event of a collision and effectively restrains the occupant's body, and the belt is extended while absorbing energy when a load exceeding the set value is applied to the occupant. And a force limiter mechanism that reduces the burden on the chest of the patient (for example, see Patent Document 1).

The seat belt retractor described in Patent Document 1 is provided with a force limiter mechanism that absorbs energy by twisting a torsion bar (torsion bar) and plastically deforms and feeds the belt by a predetermined amount. The pretensioner (belt pre-tensioning device) is connected to the spindle (belt drum) via a torsion bar (torsion bar), and the pulling load by the pretensioner is transmitted to the spindle via the torsion bar. Pull in instantly. With this configuration, the spindle is rotated in the pull-out direction for operating the force limiter mechanism after the pretensioner is driven without being affected by the operation of the pretensioner.
Japanese Patent No. 2519386

  Incidentally, in the seat belt retractor that transmits the force of the pretensioner through the torsion bar as described in Patent Document 1 described above, the energy absorption load of the force limiter mechanism is determined by the torsional strength of the torsion bar. Will be. However, since there is no provision for restricting torsional rotation of the torsion bar, there is a risk that the torsion bar may be twisted off when the seat belt is pulled out beyond a predetermined length, and there is nothing to stop the seat belt. There was a problem.

  The present invention has been made in view of the above circumstances. The purpose of the present invention is to transmit the force of the pretensioner to the spindle via the torsion bar so that the belt can be pulled in instantaneously and when the seat belt is pulled out. An object of the present invention is to provide a seatbelt retractor capable of preventing torsion of a torsion bar by restricting torsion of the torsion bar.

The object of the present invention is achieved by the following configurations.
(1) a spindle around which the belt is wound;
A pretensioner that acts on the spindle to retract the belt;
A torsion bar disposed in a force transmission path between the spindle and the pretensioner;
A torque tube provided outside the torsion bar;
A switching device that switches between a state in which the torque tube rotates integrally with the spindle and a state in which the torque tube can rotate relatively;
A twist control mechanism for controlling the torsional rotation speed of the torsion bar;
With
The torsion bar is coupled to a tread head to which force from the pretensioner is input at one end thereof, and is coupled to the spindle at the other end.
The torsion restriction mechanism includes a plurality of deformable members provided along the longitudinal direction on the outer peripheral surface of the torsion bar, and a guide arm that rotates integrally with the tread head and protrudes along the axial direction of the torsion bar. A guide bush that has a guide ring that moves in the axial direction of the torsion bar along the guide arm while handling the deformable member with relative rotation of the torque tube with respect to the tread head;
The seatbelt retractor characterized in that in a state where the torque tube rotates integrally with the spindle, the rotation of the torsion bar is regulated via the torque tube by the guide ring coming into contact with the stopper portion of the torque tube. .
(2) On the outer peripheral surface of the torque tube, a male screw portion is formed, and a slit in which the deformable member is accommodated is provided along the axial direction.
An internal thread portion is formed on the inner peripheral surface of the guide ring so as to be screwed into the male screw portion of the torque tube. The guide ring is screwed into the torque tube and handles the deformable member at a predetermined rotational speed. The retractor for a seat belt according to (1), wherein the retractor is movable only.

  According to the seatbelt retractor of the present invention, the pretensioner constitutes a force transmission path that is coupled to the spindle via the torsion bar, and when the seatbelt is pulled out after the pretensioner is actuated, The torque tube rotates. Since the rotation of the guide ring screwed to the outside of the torque tube is restricted by the guide arm of the guide bush provided integrally with the tread head, the guide ring moves in the axial direction of the torque tube, Stop by hitting the stopper of the torque tube. At this time, since it moves while handling the deformable member, it is possible to absorb rotational energy, to prevent the torsion bar from being twisted off, and to prevent the seat belt from being pulled out abnormally. .

  Hereinafter, a retractor for a seat belt according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the seat belt retractor 10 of the present embodiment is rotatably supported by a retractor frame 11, a spindle assembly 12 that winds up a seat belt (not shown), and the spindle assembly 12 as a seat. A winding spring device 17 that urges the belt in the winding direction, an acceleration sensor 13 that detects the acceleration in the horizontal direction of the vehicle, and a lock that locks the pull-out operation of the seat belt in accordance with the acceleration detected by the acceleration sensor 13 A mechanism 14, a pretensioner 15 that acts on the spindle assembly 12 to retract the seat belt in the event of a vehicle collision, and a force limiter mechanism 16 that feeds out the seat belt while absorbing energy when a load greater than a set value is applied to the seat belt; .

  The winding spring device 17 is arranged on one end side in the axial direction of the spindle assembly 12 and is attached to the retractor frame 11. On the other hand, the acceleration sensor 13, the lock mechanism 14, and the pretensioner 15 are disposed on the other axial end side of the spindle assembly 12 and are accommodated in a drive cover 18 and a system cover 19 attached to the retractor frame 11.

  The acceleration sensor 13 includes a spherical sensor weight 21 and a sensor case 22 that houses the sensor weight 21, and a sensor lever 22 a is rotatably attached to the sensor case 22.

  The lock mechanism 14 can employ various known configurations. In the case of the present embodiment, the lock mechanism 14 is rotatably supported between the bearing plate 31 and the system cover 19, and can be engaged with the internal teeth 31 a of the bearing plate 31 in conjunction with the inertia body 34. The lever 32, the steering wheel 33 engaged with the WS lever 32, the inertia body 34 disposed in the steering wheel 33, the spring 35 provided between the steering wheel 33 and the inertia body 34, and the steering disk 36 And a ratchet wheel 37 attached integrally with the steering wheel 33.

  When the horizontal acceleration is greater than a predetermined value due to a vehicle collision or the like, the sensor weight 21 of the acceleration sensor 13 moves and the sensor lever 22a rotates upward. Subsequently, the sensor lever 22 a rotates upward and engages with the steering wheel 33. When the seat belt is pulled out from the retractor 10 while the rotation of the steering wheel 33 in the pull-out direction is blocked, the steering wheel 33 is delayed in rotation with respect to the spindle 12 and is attached to the steering wheel 33 so as to be rotatable. Further, a lock piece 67 described later is engaged with a pre-tension ring 42 described later in a state in which the lock piece 67 is moved radially outward to be unable to rotate, and the seat belt pulling operation by the spindle 12 is locked.

  The pretensioner 15 includes a large-diameter ring 41, a pre-tension ring 42, a small-diameter ring 43, a locking lever 44, a sync ring 45, a distance plate 46, a ball guide plate 47, and a lever member between the retractor frame 11 and the drive cover 18. 48 and a ball stop 49, and a drive device 51 around the pretension ring 42.

  The drive device 51 includes a tube housing 52 attached to the retractor frame 11, a gas generator 53 provided in the tube housing 52, a spring 54, a piston 55, and a ball 56 as a mass body. One end of the tube housing 52 is closed by a cap 57. The balls 56 are pushed out through the piston 55 due to the gas pressure increase due to the ignition of the gas generator 53, and these balls 56 enter the groove portion of the pretension ring 42 to rotate the pretension ring 42. Note that the spring 54 prevents the generation of abnormal noise due to the rattling of the normal ball 56.

  The pretension ring 42 is rotatably supported between the retractor frame 11 and the drive cover 18 by a large diameter ring 41 and a small diameter ring 43. On the outer peripheral side of the pretension ring 42, there are a groove portion 42 a in which the ball 56 of the driving device 51 is accommodated, and a claw portion 45 a that can mesh with the locking lever 44 and that is formed inwardly around the synchro ring 45. Lockable external teeth 42b are formed. Further, an inner tooth 42 c that can mesh with the lock piece 67 is formed on the inner peripheral side of the pretension ring 42. Further, a window hole 42d (see FIG. 2) for inserting and guiding the lever member 48 is formed on the side surface of the pretension ring 42.

  A protrusion 44 a (see FIG. 2) is formed on the side surface of the locking lever 44, and this protrusion is guided to the cam hole 45 b of the synchro ring 45. The locking lever 44 is engaged with and disengaged from the external teeth 42b by the rotation of the synchro ring 45 by the rotation of the pretension ring 42, and stops the rotation of the pretension ring 42 in the belt drawing direction by meshing with the external teeth 42b.

  1, 5, 6, and 8, the spindle assembly 12 includes a spindle 61 around which the seat belt is wound, a tread head 62 that closes an opening at one end thereof, and a spindle that is disposed in the spindle 61. A torque pipe 63, a torsion bar 65, a torque tube 64 provided around the torsion bar 65, and a lock piece guided to the outer peripheral surface of the tread head 62. 67, a locking element 68 that is rotatably mounted in a pair of through holes 61a formed in the spindle 61, an end piece 69 and a spindle ring 70 that are mounted on the periphery from the other end of the spindle 61. Prepare. In FIG. 1, reference numeral 71 is a drum ring, and 72 is an omega spring.

  Further, a switch housing 81 and a switch piston 82 are disposed between the retractor frame 11 and the cover case 17, and a path switching gas generator 83 is attached to the switch housing 81. In this embodiment, the locking element 68, end piece 69, spindle ring 70, switch housing 81, switch piston 82, and path switching gas generator 83 are provided in the force transmission path between the spindle 61 and the pretensioner 15. The switching device 20 is configured to switch the torque tube 64 that is rotating relative to the spindle 61.

  One end 65a of the torsion bar 65 is formed in a Torx (registered trademark) shape having a large diameter, and the other end 65b is formed in a Torx shape having a small diameter. The torsion bar 65 is designed to have a thickness and hardness so as to have a torsional torque larger than the torque generated by the operation of the pretensioner 15. In addition, the torsion bar 65 is provided with a twist restricting mechanism 90 that restricts the torsional rotation speed of the torsion bar 65 when the seat belt is pulled out.

  A torx-shaped hole 62 a is formed on the inner peripheral surface of the tread head 62, and one end 65 a of the torsion bar 65 is fitted therein. The other end 65 b of the torsion bar 65 is fitted and fixed to a Torx-shaped recess 61 b formed on the inner peripheral surface on the other end of the spindle 61. As a result, the torsion bar 65 is disposed in the force transmission path between the spindle 61 and the pretensioner 15.

  The torque pipe 63 has a plurality of convex portions 63a and 63b on the outer peripheral surfaces of both ends, and the convex portion 63a on one end side is formed in a concave portion 64b formed on the inner peripheral surface of the other end portion of the torque tube 64 and on the other end side. The convex portion 63b is disposed around the torsion bar 65 in a state where the convex portion 63b is fitted and fixed to a concave portion 61c formed on the inner peripheral surface on the other end side of the spindle 61.

  The locking element 68 is mounted in a through hole 61 a formed in the spindle 61 and rotates so as to advance and retreat in a connecting recess 64 c formed in an end portion of the torque tube 64. In a state where the locking element 68 is pressed against the inner peripheral surface of the spindle ring 70, as shown in FIG. 7 (a), the locking element 68 advances into the connecting recess 64c of the torque tube 64, and the rotation is suppressed. Thereby, the torque tube 64 is coupled to the spindle 61 via the pair of locking elements 68, and the spindle 61 and the torque tube 64 rotate integrally. The end piece 69 is made of resin, and the spindle ring 70 is positioned and fixed with respect to the spindle 61.

  As shown in FIGS. 5, 6, and 9, the twist restricting mechanism 90 includes a plurality of (for example, three) deforming members 91 provided on the outer peripheral surface of the torsion bar 65 along the longitudinal direction, and a tread. A guide bush 92 having a guide arm 92a that rotates integrally with the head 62 and protrudes along the axial direction of the torque tube 64, and a guide arm 92a while handling the deformable member 91 as the torque tube 64 rotates relative to the tread head 62. And a guide ring 93 that moves in the axial direction of the torsion bar 65.

  As shown in FIG. 9, the torque tube 64 is formed in a cylindrical shape, and has a male screw portion 64d having a screw formed on the outer peripheral surface and a larger diameter than the male screw portion 64d on one end side of the male screw portion 64d. And it has the stopper part 64e in which the connection recessed part 64c is formed in an outer peripheral surface. Further, a slit 64a having a width through which the deformable member 91 can pass is cut out at a predetermined length corresponding to the number of the deformable members 91 at the end of the male screw portion 64d on the stopper portion 64e side.

  As shown in FIG. 9 (c), the deformable member 91 is formed from a metal wire, and one end 91 a is implanted on the outer peripheral surface of the torsion bar 65 and extends along the outer peripheral surface of the torsion bar 65. The other end 91b is a free end. Further, a convex portion 91c is bent on the one end 91a side of the deformable member 91, and an inclined portion 91d is provided on the other end 91b side of the convex portion 91c. As shown in FIG. 9B, when the torque tube 64 is put on the torsion bar 65, the convex portion 91c is inserted into the slit 64a.

  The height of the convex portion 91c is set so that the upper surface protrudes at least outward from the valley of the male screw portion 64d of the torque tube 64 so that the deformable member 91 is handled when the guide ring 93 moves. To do. Further, a gap 94 into which the deformable member 91 can be inserted is provided between the inner surface of the torque tube 64 and the outer surface of the torsion bar 65.

  As shown in FIGS. 10A and 10B, the guide bush 92 has a bottomed cylindrical main body 92 b provided outside the torque tube 64, and extends from the main body 92 b in the axial direction of the torque tube 64. At least one guide arm 92a (two in this embodiment) is provided so as to protrude. Further, an engaging portion 92 c that protrudes from the main body 92 b toward the tread head 62 is fixed to the tread head 62, and the guide bush 92 always rotates integrally with the tread head 62.

  As shown in FIG. 9, the guide ring 93 has a cylindrical shape, and is provided with a guide opening 93a that is fitted to the guide arm 92a of the guide bush 92 and guided by the guide arm 92a. Further, on the inner surface of the guide ring 93, a female screw portion 93 b (see FIGS. 5 and 6) that is screwed with the male screw portion 64 d of the torque tube 64 is formed except for a position facing the deformation member 91. . Therefore, when the torque tube 64 rotates relative to the guide bush 92, the guide ring 93 moves along the torque tube 64 without rotating relative to the guide bush 92.

  Next, operations of the pretensioner 15, the force limiter mechanism 16, and the torsion restriction mechanism 90 of the seat belt retractor 10 of the present embodiment will be described.

  The pretensioner 15 receives a current for operation from the vehicle side, and the ball 56 moves in the tube housing 52 due to an increase in gas pressure due to ignition of the gas generator 53 of the drive device 51. The moved ball 56 enters the groove portion 42 a of the pretension ring 42 from the tube housing 52 and rotates the pretension ring 42.

  When the pretension ring 42 rotates, the locking lever 44 engaged with the external teeth 42b is ejected outward from the state shown in FIG. At the same time, the protrusion 44a of the locking lever 44 rotates the synchro ring 45 by pulling the cam hole 45b (see FIG. 3B). Thereafter, the lock lever 44 is brought into contact with a cut-and-raised plate (not shown) provided on the retractor frame 11 to stop the rotation, and the synchro ring 45 is also connected via a cam hole 45b that guides the protrusion 44a. Stop turning.

  However, as shown in FIG. 4, the claw portion 45a formed on the synchro ring 45 is engaged with the external teeth 42b of the pretension ring 42 and the ratchet so as to allow the pretension ring 42 to rotate. 42 continues to rotate while playing the claw portion 45b with the external teeth 42b.

  At the same time, when the pretension ring 42 rotates, the lever member 48 guided by the window hole 42 d rotates and the tip of the lever member 48 meshes with the ratchet wheel 37.

  Further, when the pretension ring 42 is rotated and the lever member 48 is further rotated, the ratchet wheel 37 and the steering disk 36 are rotated. In this state, no force is transmitted to the tread head 62.

  As a result, the pin 67a is supported in the cam hole 36a of the steering disk 36 (see FIG. 2), and the lock piece 67 is driven by the rotation of the steering disk 36 while being guided by the tread head 62. 42c (see FIG. 3C).

  Further, when the pretension ring 42 is pushed by the ball 56 and rotates, the lock piece 67 meshes with the inner teeth 42c of the pretension ring 42, so that the rotation of the pretension ring 42 causes the tread head 62, the torsion bar 65, A seat belt which is transmitted to the spindle 61 via the locking element 68 and fixed to the spindle 61 is wound. As a result, the pretensioner 15 is activated. At this time, the torque tube 64 rotates integrally with the spindle 61.

  The torsion bar 65 has a torsional torque larger than the torque generated by the operation of the pretensioner 15. That is, since the thickness and hardness are set so as not to be twisted (not plastically deformed) by the force of the pretensioner 15, the force of the pretensioner 15 can be reliably transmitted to the spindle 61.

  On the other hand, in the force limiter mechanism 16, after the pull-in by the pretensioner 15 is started, the gas generator 53 is operated and the switching device 20 is operated at an appropriate timing. The operation timing of the switching device 20 is appropriately set in advance from the characteristics of the vehicle and the seat belt. For example, the switching device 20 can be set to operate after a predetermined time (ms) after the pretensioner operation.

  The switching device 20 receives the path switching current and the path switching gas generator 83 ignites. The switch piston 82 is pushed in the direction of the arrow x in FIG. 5 by the gas pressure from the path switching gas generator 83, and the spindle ring 70 is also pushed by the switch piston 82 and deviated in the direction of the arrow x.

  When the spindle ring 70 moves in the direction of the arrow x, the locking element 68 is rotatable in the radial direction of the spindle 61 in the connection hole 61 a of the spindle 61. For this reason, the profile moves outward from within the connecting recess 64c of the torque tube 64 by the connecting recess 64c of the torque tube 64 formed so as to push the locking element 68 outward (see FIG. 9B). Thereby, the spindle 61 and the torque tube 64 can be relatively rotated.

  However, in this state, since the spindle 61 and the torque tube 64 are connected by the torque pipe 63, relative rotation is not performed. Since the force transmission path between the tread head 62 and the spindle 61 is not affected by the rotation of the torque tube 64, the tread head 62, the torsion bar 65, the torque pipe 63, and the spindle 61 are arranged in this order.

  On the other hand, when the movement of the ball 56 of the pretensioner 15 is completed and the rotation of the spindle 61 in the winding direction is stopped, the belt is pulled out by the forward movement of the occupant. A force (force transmission path) acting in the belt pulling direction is transmitted to the spindle 61, the torque pipe 63, the torsion bar 65, the tread head 62, and the pretensioning ring.

  When the pretension ring 42 rotates in the belt pull-out direction, the claw portion 45a of the synchro ring 45 engages with the external teeth 42b of the pretension ring 42, so that the synchro ring 45 also rotates integrally. At this time, the cam hole 45b formed in the synchronization ring 45 pushes the protrusion of the locking lever 44 to guide the locking lever 44 inward, and engages the locking lever 44 and the external teeth 42b of the pretensioning ring 42. Thereby, the rotation of the pretensioning ring 42 in the pull-out direction is stopped.

  When the seat belt is pulled out in this state, as shown in FIG. 11, the rotation of the spindle 61 is transmitted to the torque pipe 63 and the torsion bar 65 and twists the torsion bar 65, so that the belt load increases (in FIG. 11, a section). Before switching by the switching device 20, the torque tube 64 rotates integrally with the spindle 61 and the torsion bar 65, and the rotational force of the spindle 61 is transmitted to the tread head 62 side.

  That is, when the belt load reaches the torsional load of the torsion bar 65, the torsion bar 65 is twisted while being plastically deformed in the force transmission path, the spindle 61 rotates, and the seat belt is pulled out.

  Further, since the torque tube 64 rotates relative to the tread head 62 from the state shown in FIG. 10A, the torque tube 64 is screwed into the male threaded portion 64 d of the torque tube 64 and stopped by the guide bush 92. The guide ring 93 moves in the direction of arrow A (see FIG. 10B) along the guide arm 92a. At this time, since the guide ring 93 rotates while handling the deformable member 91, it absorbs rotational energy. When the torsion bar 65 rotates by a predetermined number of rotations (here, 8 rotations), the guide ring 93 comes into contact with the stopper portion 64e of the torque tube 64 and stops rotating. Thereby, the rotation of the torsion bar 65 rotating integrally with the torque tube 64 is prevented.

  On the other hand, if switching by the switching device 20 is performed before the torsion bar 65 rotates by a predetermined number of rotations (here, 8 rotations), the torque pipe 63 is twisted at the same time as the second torsion bar 65 is twisted, and torque The pipe 63 generates a load when it is torsionally deformed, and is twisted off after completing a predetermined rotation. Therefore, in the initial stage of the force limiter operation, it is possible to add the load of the torque pipe 63 in addition to the load at which the torsion bar 65 starts to be twisted, and the torque pipe 63 compensates the load at which the torsion bar 65 starts to twist. Play a role. In the torque pipe 63, the generated load and the number of rotations that can be torsionally set are set in advance.

  After the torque pipe 63 has been twisted, the torque tube 64 is separated from the spindle 61 and the torsion bar 65 and can be relatively rotated. Then, the pulling direction force acting on the spindle 61 is transmitted to the tread head 62 and the pretensioning ring 42 while absorbing energy by the torsion bar 65 (b section in FIG. 11).

  For this reason, the torque tube 64 stops rotating with respect to the tread head 62 before reaching the predetermined rotation of the torsion bar 65. After that, when the seat belt is pulled out and the spindle 61 rotates, the torsion bar 65 also rotates, and therefore rotates while pulling the deformation member 91 having one end fixed to the torsion bar 65. When the deformable member 91 is rotated by a predetermined number of rotations (for example, 4 rotations) and stopped, the rotation of the torsion bar 65 is stopped.

  The operation timing of the switching device 20 is determined by various sensors mounted on the vehicle to detect the severity of the collision, the form of the collision, the occupant's physique, the belt load, and the like, and an appropriate timing according to each collision. The switching operation may be performed with. Alternatively, the operation timing of the switching device 20 can be set in advance after a predetermined time has elapsed from the operation of the pretensioner 15.

  As described above, according to the seat belt retractor 10 of the present embodiment described above, the pretensioner 15 forms a force transmission path that couples with the spindle 61 via the torsion bar 65, and when the seat belt is pulled out after the pretensioner 15 is actuated. As the spindle 61 rotates, the torsion bar 65 and the torque tube 64 rotate. Since the guide ring 93 screwed to the outside of the torque tube 64 is restricted in rotation by the guide arm 92 a of the guide bush 92 provided integrally with the tread head 62, the guide ring 93 is connected to the torque tube 64. It stops in contact with the stopper portion 64e of the torque tube 64. At this time, since it moves while handling the deformable member 91, the rotational energy can be absorbed, and the torsion bar can be prevented from being twisted and the seat belt can be prevented from being pulled out abnormally. it can. On the other hand, after the switching device 20 switches the torque tube 64 to be rotatable relative to the spindle 61, the torsion bar 65 rotates while pulling the deformable member 91, so that it absorbs rotational energy and rotates by a predetermined number of rotations. Then, the rotation stops. Thereby, it is possible to prevent the torsion bar 65 from being twisted out even after switching, to prevent the torsion bar 65 from being twisted off, and to prevent the seat belt from being pulled out abnormally.

In addition, this invention is not limited to the thing of the said embodiment, An improvement or a deformation | transformation etc. are possible suitably.
For example, in the above-described embodiment, the guide ring 93 is capable of rotating eight times with respect to the torque tube 64 and the deformable member 91 is allowed to rotate the torsion bar 65 four times. can do.

  Further, the cross-sectional shape of the torsion bar 65 may not be circular as long as it is a shape that is not twisted by the force of the pretensioner, and may be a Torx shape over both axial ends.

It is a disassembled perspective view which shows the seatbelt retractor of 1st Embodiment of this invention. It is a perspective view which shows the pretensioner of FIG. It is the schematic which shows the operation state of a pretensioner, (a) is a state before an operation | movement, (b) is a state in which engagement with a lock lever and a pretension ring is cancelled | released at the time of an operation | movement, (c) is after an operation | movement. The state where the lock piece is engaged with the pretension ring is shown. It is a principal part enlarged view which shows the engagement state of the external tooth of a pretension ring, and the nail | claw part of a synchro ring. FIG. 2 is a cross-sectional view showing a state before the guide ring moves in the seat belt retractor of FIG. 1. FIG. 2 is a cross-sectional view showing a state after a guide ring has moved in the seat belt retractor of FIG. 1. It is sectional drawing along the VII-VII line of FIG. 5, (a) is the state before switching by a switching apparatus, (b) is the state after switching. It is a perspective view of a spindle assembly. (A) is a perspective view of a twist control mechanism, (b) is a perspective view of a torque tube, and (c) is a perspective view of a torsion bar. (A) is a perspective view of the torsion restriction mechanism showing a state before the guide ring moves, and (b) is a perspective view of the torsion restriction mechanism after the guide ring moves. It is a graph which shows a force limiter characteristic when there is no switching by a switching device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Seat belt retractor 15 Pretensioner 20 Switching device 61 Spindle 62 Tread head 64 Torque tube 64a Slit 64e Stopper part 64d Male thread part 65 Torsion bar 65a One end part 65b Other end 90 Torsion control mechanism 91 Deformation member 92 Guide bush 92a Guide arm 93 Guide ring 93b Female thread

Claims (2)

A spindle around which the belt is wound,
A pretensioner that acts on the spindle to retract the belt;
A torsion bar disposed in a force transmission path between the spindle and the pretensioner;
A torque tube provided outside the torsion bar;
A switching device that switches between a state in which the torque tube rotates integrally with the spindle and a state in which the torque tube can rotate relatively;
A twist control mechanism for controlling the torsional rotation speed of the torsion bar;
With
The torsion bar is coupled to a tread head to which force from the pretensioner is input at one end thereof, and is coupled to the spindle at the other end.
The torsion restriction mechanism includes a plurality of deformable members provided along the longitudinal direction on the outer peripheral surface of the torsion bar, and a guide arm that rotates integrally with the tread head and protrudes along the axial direction of the torsion bar. A guide bush that has a guide ring that moves in the axial direction of the torsion bar along the guide arm while handling the deformable member with relative rotation of the torque tube with respect to the tread head;
The seatbelt retractor characterized in that in a state where the torque tube rotates integrally with the spindle, the rotation of the torsion bar is regulated via the torque tube by the guide ring coming into contact with the stopper portion of the torque tube. . On the outer peripheral surface of the torque tube, a male screw portion is formed, and a slit for accommodating the deformable member is provided along the axial direction,
An internal thread portion is formed on the inner peripheral surface of the guide ring so as to be screwed into the male screw portion of the torque tube. The guide ring is screwed into the torque tube and handles the deformable member at a predetermined rotational speed. The seatbelt retractor according to claim 1, wherein the seatbelt retractor can be moved only by a predetermined distance.

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