JP7124581B2 - seat belt retractor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a seatbelt retractor with a pretensioner for use in vehicles such as automobiles, and more particularly to a seatbelt retractor in which a torsion bar is incorporated in a spool.

As a seat belt retractor with a pretensioner, a seat in which a torsion bar is inserted into an inner hole of a spool, one end of the torsion bar can be fixed to the spool, and the other end of the torsion bar can be locked to the frame of the seat belt retractor. A belt retractor is known (Patent Documents 1 and 2). In an emergency such as a vehicle collision, the spool is rotationally driven by the pretensioner to wind up the webbing. Thereafter, a force in the webbing unwinding direction is applied to the spool to twist the torsion bar, gradually rotate the spool, and gradually pull out the webbing. As a result, part of the kinetic energy applied to the occupant's body is absorbed by the twisting of the torsion bar, and the impact is mitigated.

Japanese Patent Laid-Open No. 2002-201003 describes limiting the amount of twisting of a torsion bar by moving a stopper screwed onto the torsion bar.

JP-A-11-222100 JP 2017-154525 A

In the seat belt retractor with a pretensioner disclosed in Patent Document 1, the torsion bar is twisted when the pretensioner is actuated, causing the position of the stopper to shift, which may limit the amount of twisting of the torsion bar.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a seat belt retractor with a pretensioner that secures the twist amount of the torsion bar during EA operation.

The seat belt retractor of the present invention comprises a frame supporting a spool and a locking base, a tubular spool having a first inner hole for winding webbing, a second inner hole coaxially adjacent to the spool, and a second inner hole. and is inserted through the locking base connected to the spool by a torsion bar, the first inner hole of the spool and the second inner hole of the locking base, one end side is non-rotatably connected to the spool, and the locking The torsion bar is non-rotatably connected to the base at the other end, and the pretensioner rotates the locking base in the webbing take-up direction. A seat belt retractor in which the torsion bar is torsionally deformed when a force is applied, wherein a male screw is provided on the outer peripheral surface of the locking base, and the male screw is connected to the female screw on the inner peripheral surface of the stop gear and the positioning gear. are screwed together, and in the state before the vehicle collision, the stop gear and the positioning gear are separated by a predetermined distance, and when the locking base and the spool are rotated by the pretensioner drive, , the stop gear and the positioning gear rotate integrally with the locking base, the spool rotates by EA operation, and when the locking base stops rotating, the stop gear rotates along the locking base. It spirals toward the positioning gear.

In one aspect of the present invention, a sliding resistance agent is present in a sliding portion between the male screw of the locking base and the positioning gear.
In one aspect of the present invention, the locking base includes a flange portion, a tubular shaft portion having the second inner hole and protruding from the central portion of the flange portion, and a projecting end of the shaft portion. and a receiving portion provided on the shaft portion for receiving force from the pretensioner, and the stop gear and the positioning gear are attached to the male screw. The female threads on the inner peripheral surface are screwed together.

In one aspect of the present invention, the stop gear is positioned on the distal end side of the shaft portion of the male screw on the outer peripheral surface of the shaft portion in a state before a vehicle collision, and the positioning gear is positioned on the tip side of the shaft portion. The stop gear is located closer to the proximal end of the shaft than the stop gear, and when the spool rotates while the torsion bar is twisted by the EA operation and the locking base stops rotating, the stop gear engages the shaft. It spirals toward the positioning gear and comes into contact with the positioning gear.

In one aspect of the present invention, the stop gear is configured to always rotate integrally with the spool, and the positioning gear is disengaged from the spool in the event of a heavy collision that causes a deceleration equal to or greater than a predetermined value. and at other times the positioning gear is associated with the spool and is configured to rotate integrally therewith.

In one aspect of the present invention, a locking portion extending in the axial direction is provided on the inner peripheral surface of the first inner hole of the spool, and the stop gear is engaged with the locking portion. It has an engaging portion. In one aspect of this mode, the locking portion is groove-shaped, and the engaging portion is a projection projecting from the outer peripheral surface of the stop gear.

In one aspect of the present invention, the positioning gear has a sliding resistance on the threaded portion side, and is provided with a spring elastically deformable in a radial direction on its outer peripheral surface. When the centrifugal force acting on is smaller than a predetermined value, the engaging portion is engaged, and when the centrifugal force becomes greater than the predetermined value, the spring is elastically deformed in the radial direction, and then, When the centrifugal force becomes smaller than a predetermined value, the restoring force of the spring approaches the outer peripheral surface of the positioning gear, the spring disengages from the engaging portion, and the connection between the positioning gear and the spool is released. be.

In one aspect of the present invention, the spring has a main plate portion extending in a direction along the axis of the positioning gear, and one end side of the main plate portion is held by the positioning gear. The other end side is elastically deformable in the radial direction of the positioning gear by centrifugal force.

In one aspect of the present invention, a folded portion having a shape folded back so as to overlap with the main plate portion is provided on the other end side of the main plate portion of the spring. A folded portion rises from the main plate portion toward the outer peripheral surface of the positioning gear, and the tip of the folded portion is engaged with the outer peripheral surface of the positioning gear to maintain the standing state.

In one aspect of the present invention, when a centrifugal force of a predetermined value or more acts on the spring, the main plate portion is elastically deformed radially from the positioning gear, thereby locking the folded portion and the outer peripheral surface of the positioning gear. When released, the folded portion returns to its original shape along the main plate portion, and thereafter, when the centrifugal force acting on the spring becomes smaller than the predetermined value, the main plate portion follows the outer peripheral surface of the positioning gear. shape, and the spring disengages from the locking portion.

In one aspect of the present invention, a weight portion is provided on the other end side of the main plate portion.

In the seat belt retractor of the present invention, the spool, the torsion bar, the locking base, the stop gear, and the positioning gear rotate together in a state before an emergency such as a vehicle collision (hereinafter referred to as a vehicle collision) to rotate the webbing. is pulled out and wound up.

In the event of a vehicle collision, the pretensioner is activated, the locking base, torsion bar, and spool rotate in the webbing winding direction to eliminate slack in the webbing. As the slack in the webbing is removed, the tension in the webbing increases, but the pretensioner applies more force to the torsion bar in the winding direction, causing the torsion bar to twist slightly further in the winding direction. Since the stop gear and the positioning gear are engaged with the spool and both rotate and spiral relative to the locking base, the separation distance between the stop gear and the positioning gear does not change.

After that, when the pull-out force applied to the webbing from the occupant's body exceeds the wind-up force applied from the pretensioner, the locking base is kept in a non-rotating state by the holding pressure action of the pretensioner, and the spool pulls the torsion bar. It rotates while twisting, the webbing is pulled out, and the EA (energy absorption) of the occupant is performed. When the spool stops rotating in this way, the connection between the spool and the positioning gear is released.

After that, as the spool rotates, the stop gear rotates and spirals together with the spool, but the positioning gear does not rotate and remains stationary. The spool stops when the stop gear that has spiraled comes into contact with the positioning gear.

1 is an exploded perspective view from the front side of a seat belt retractor according to an embodiment; FIG. It is an exploded perspective view from the back side of a seat belt retractor concerning an embodiment. 1 is a front view of a seat belt retractor according to an embodiment; FIG. It is a left view of the seat belt retractor which concerns on embodiment. It is a right view of the seat belt retractor which concerns on embodiment. FIG. 4 is an exploded perspective view of the spool and locking plate when the spool is viewed from the left side; FIG. 4 is an exploded perspective view of the spool and locking plate when the spool is viewed from the right side; FIG. 4 is a front view of the spool and locking plate with the paddle removed; FIG. 9 is a cross-sectional view in the axial direction of FIG. 8; FIG. 10 is an enlarged view of the X portion of FIG. 9; FIG. 4 is a cross-sectional view for explaining the action of a spring provided on the positioning gear; It is a sectional view of a seat belt retractor concerning an embodiment. FIG. 4 is a cross-sectional view for explaining the action of a spring provided on the positioning gear; It is a sectional view of a seat belt retractor concerning an embodiment.

Embodiments will be described with reference to the drawings.

The seat belt retractor 1 includes a frame 10, a spool 20 rotatably held by the frame 10, a return spring unit (spring spring unit) 30 for biasing the spool 20 in a webbing winding direction, , a locking base 40 connected to the spool 20 by the torsion bar 70, a lock activation unit 50 for activating the lock of the spool 20, a pretensioner 60, the spool 20 and the locking base 40 so as to connect A torsion bar 70 and the like inserted in the spool 20 and the locking base 40 are provided.

The frame 10 is provided on a front wall 11, a left side wall 12 extending forward from the left side of the front wall 11, a right side wall 13 extending forward from the right side, and side walls 12 and 13, respectively. It has spool insertion holes 15, 16 and the like. Saw teeth 16 a are provided on the inner peripheral surface of the spool insertion hole 16 .

The return spring unit 30 has a spiral spring housed in a case 31 , and one end of the spiral spring is connected to the projecting shaft 20 t on the left end side of the spool 20 .

The lock activation unit 50 has a lock assembly 52 with which a pendulum 51 (FIG. 2) held on the first right side wall 13 of the frame engages with its outer peripheral surface. When the rotational angular acceleration of the lock assembly 52 exceeds a predetermined value or when the pendulum 51 engages with the outer peripheral surface of the lock assembly 52, the lock assembly 52 causes the pawl 43 (FIG. 2) to protrude from the outer peripheral surface of the locking base 40. to engage the serrations 16a.

A cover 55 covers the lock assembly 52 and the pendulum 51 .

This lock activation unit 50 is of a known construction.

The pretensioner 60 winds up the spool 20 in the webbing winding-up direction with a large torque in the event of a vehicle collision, and removes slack in the webbing. The pretensioner 60 includes a gas generator 61 that generates gas at the time of a vehicle collision, a duct 62, and a power transmission member made of synthetic resin or the like filled in the duct 62, and the like. The gas pressure from the gas generator 61 feeds the power transmission member in the circumferential direction to the outer periphery of the paddle wheel 80, which will be described later, and the spool 20 rotates in the webbing take-up direction. This configuration can be, for example, that described in Patent Document 2.

Next, the structures of the spool 20 and locking base 40 will be described in detail.

6 to 10, the spool 20 has a tubular portion 21 around which the webbing is wound, a left flange 22 on the left end side of the tubular portion 21, and a right flange 23 on the right end side.

An outer peripheral surface 22 e of the left flange 22 of the spool 20 faces the inner peripheral surface of the spool insertion hole 15 . An outward flange portion 22f that protrudes in the radial direction is provided around the outer peripheral edge of the left flange 22 on the cylinder portion 21 side. The collar portion 22f is slidably in contact with the inner surface of the side wall 12 along the peripheral portion of the spool insertion hole 15. As shown in FIG.

The tubular portion 21 of the spool 20 is provided with a first inner hole 29 extending from the right end to the left end. A serration portion 29a (FIG. 9) is provided at the innermost portion of the inner hole 29, that is, on the left end side, and a gear-shaped portion 71 of a torsion bar 70 (not shown in FIG. 9) engages with the serration portion 29a. there is

As clearly shown in FIG. 9 , the first inner hole 29 of the spool 20 has a large diameter in the range from the inlet side of the first inner hole 29 to the step surface 108 . A groove 110 is provided on the inner peripheral surface of this large diameter portion as a locking portion extending in a direction parallel to the axis of the spool 20 . A convex portion 82b as an engaging portion on the outer peripheral surface of the stop gear 82 is engaged with the groove 110 so as to be slidable in the direction parallel to the axis.

A locking base 40 is arranged adjacent to the right side of the spool 20 . The locking base 40 has a flange portion 41, a cylindrical shaft portion 42 connected to the central portion of the flange portion 41, a pawl 43 provided on the flange portion 41, and the like. The tip side of the shaft portion 42 is coaxially inserted into the inner hole 29 of the spool 20 .

A serration portion 42a (FIG. 9) is provided on the inner peripheral surface of the tip side of the inner hole (second inner hole) of the shaft portion 42. It engages with the portion 42a.

A hexagonal portion 42b as a non-circular portion is provided on the outer periphery of the shaft portion 42 of the locking base 40 on the base end side (flange 41 side). A male screw 42c is provided on the outer peripheral surface of the shaft portion 42 other than the hexagonal portion 42b.

As shown in FIG. 6, a hexagonal inner hole 80a of a paddle wheel 80 (not shown in FIG. 7) is engaged with the hexagonal portion 42b, and the paddle wheel 80 is attached to the shaft portion 42 so as not to rotate in the circumferential direction. .

A power transmission member made of synthetic resin or the like is supplied from the duct 62 of the pretensioner 60 to the outer circumference of the paddle wheel 80 to rotate the paddle wheel 80 and the locking base 40 .

Female threads 82a and 86a on the inner peripheral surfaces of the stop gear 82 and the positioning gear 86 are screwed into the male thread 42c. The stop gear 82 and the positioning gear 86 can be screwed along the male screw 42c. The outer peripheral surface of the stop gear 82 is provided with the convex portion 82b as described above.

A ring-shaped spring holder 88 is fitted around the positioning gear 86, and a leaf spring 90 is attached to the spring holder 88. As shown in FIG. As shown in FIG. 7, small projections 86b provided on the outer circumference of the positioning gear 86 are engaged with slits 88a of the spring holder 88, so that the spring holder 88 is held against the positioning gear 86 so as not to rotate in the circumferential direction.

The spring 90 has a long plate-like main plate portion 93 and folded pieces 91 and 92 that are folded in parallel with the main plate portion 93 from one end side and the other end side of the main plate portion 93 . The main plate portion 93 is a leaf spring extending in the direction along the axis of the positioning gear 86 . A weight portion (weight) 94 (FIGS. 10 to 12) is provided in the vicinity of the folded portion 92 on the main plate portion 93 .

A folded portion 91 is inserted into and held by the spring mounting portion 88b of the spring holder 88 . The folded portion 92 on the other end side of the spring 90 is elastically rotated by approximately 90°, and the tip thereof contacts the convex portion 86 c on the outer peripheral surface of the positioning gear 86 .

As shown in FIG. 10, when the folded portion 92 is brought into contact with the convex portion 86c and erected, the other end of the main plate portion 93 is elastically deformed so as to separate from the outer peripheral surface of the positioning gear 86. . The elastic restoring force of the main plate portion 93 presses the folded portion 92 against the convex portion 86c, and the folded portion 92 is held in the radial direction of the positioning gear 86. As shown in FIG.

As shown in FIG. 10 , in the upright state of the folded portion 92 , the vicinity of the folded portion 92 of the main plate portion 93 enters the groove 110 of the inner hole of the spool 20 . Therefore, in the state of FIG. 10, the positioning gear 86 rotates integrally with the spool 20. As shown in FIG.

In the seat belt retractor described above, the stop gear 82 is normally screwed into the male screw 42c of the locking base 40 in the vicinity of the distal end (left side) thereof. Normally, the spring 90 is in the state shown in FIG. 10, and the engagement between the spring 90 and the groove 110 allows the positioning gear 86 and the spool 20 to rotate together as described above. Also, the stop gear 82 always rotates integrally with the spool 20 due to the engagement between the projection 82b and the groove 110 .

In the normal state before the vehicle collision, the stop gear 82 is positioned on the left end side of the male screw 42c. Also, in this normal state, the stop gear 82 and the positioning gear 86 are separated by a predetermined distance. When the spool 20 rotates as the webbing is pulled out and wound up, the spool 20, the torsion bar 70, the locking base 40, the stop gear 82 and the positioning gear 86 all rotate together. does not change the distance between

A sliding resistance agent is applied to the screw sliding portion between the positioning gear 86 and the locking base 42 so that the positioning gear does not move due to the inertial force when the webbing is pulled and wound normally.

In this normal state, the rotational speed of the spool 20 when the webbing is pulled out and wound up is low, and the centrifugal force applied to the weight portion 94 of the spring 90 when the spool 20 or the like rotates is small. Therefore, the spring 90 is maintained in the state shown in FIG. 10 by the elastic restoring force of the main plate portion 93 .

When the vehicle collides, the pendulum 51 engages the outer peripheral surface of the lock assembly 52 and the lock activation unit 50 causes the pawl 43 to protrude from the outer peripheral surface of the locking base 40 . A protruding pawl 43 engages the sawtooth 16 a of the right side wall 13 .

The pretensioner 60 does not operate during a light collision in which the vehicle deceleration at the time of collision is small. Rotation of the spool 20 is prevented by the engagement between the bowl 43 and the sawtooth 16a, and the occupant is restrained by the webbing. Further, during this light collision, as described above, the spool 20 does not rotate. Since the pretensioner 60 does not operate, the locking base 40 does not rotate either. As a result, the stop gear 82 and the positioning gear 86 do not rotate either, and the stop gear 82 and the positioning gear 86 are stopped at their original positions.
There is a case where the torsion bar 70 is twisted and the spool 20 rotates due to a light collision. In this case, stop gear 82 and positioning gear 86 rotate together with spool 20, so the distance between them does not change.

In the event of a vehicle collision with a vehicle deceleration exceeding a predetermined value, the gas generator 61 of the pretensioner 60 is activated to apply a strong torque in the webbing winding-up direction to the locking base 40 through the paddle wheel 80, causing locking. The base 40, the torsion bar 70 and the spool 20 are integrally rotated in the webbing winding direction. As a result, the webbing is wound around the spool 20 and the slack in the webbing is removed.

In this state, the locking base 40 rotates in the webbing winding direction without being restrained by the sawteeth 16a. Further, the spool 20 and the locking base 40 rotate integrally in the same direction at the same rotational speed, and the stop gear 82 and the positioning gear 86 also rotate integrally with the locking base 40 in the same direction at the same rotational speed. Gear 82 and positioning gear 86 are each in their original positions on locking base 40 .

Since the rotation speed of the locking base 40 and the spool 20 is high when the pretensioner 60 is actuated, the spring 90 is elastically deformed in the direction in which the folded piece 92 is separated from the positioning gear 86 by centrifugal force as shown in FIG. . 11, the spring 90 is engaged with the groove 110 of the spool 20, so the positioning gear 86 is linked to the spool 20. As shown in FIG. Therefore, as described above, the positioning gear 86 rotates together with the stop gear 82 together with the spool 20 and the locking base 40 . In addition, in the state of FIG. 11, the folded piece 92 is restored to a shape along the main plate portion 93 .

As noted above, webbing tension increases as slack in the webbing is removed. On the other hand, a force is applied from the pretensioner 60 to the torsion bar 70 in the webbing winding-up direction, thereby gradually twisting the torsion bar 70 during the webbing winding-up. By twisting the torsion bar 70, the locking base 40 rotates relative to the spool 20, and the positioning gear 86 and the stop gear 82 are slightly translated to the right in FIG. 12 as shown in FIG.

When the winding of the webbing progresses and the slack in the webbing is removed, the spool 20 is temporarily stopped, and the winding of the webbing by the spool 20 is stopped. When the spool 20 stops in this way, the centrifugal force applied to the spring 90 disappears. It becomes the state which overlapped with the outer peripheral surface. As a result, the spring 90 is disengaged from the groove 110 and the connection between the spool 20 and the positioning gear 86 is released.

After that, the spool 20 begins to rotate in the webbing pull-out direction while twisting the torsion bar 70 due to the webbing pull-out direction force applied to the spool 20 (EA operation). The locking base 40 , which is connected to the spool 20 via the torsion bar 70 , is prevented from rotating in the webbing pull-out direction due to the holding pressure action of the pretensioner 60 . As a result, the spool 20 rotates while twisting the torsion bar 70, and the webbing is pulled out. The torsional deformation of the torsion bar 70 absorbs the operating energy of the forward movement of the passenger.

When the spool 20 rotates in the webbing pull-out direction with the locking base 40 stopped in this manner, the stop gear 82 rotates integrally with the spool 20 and spirals toward the positioning gear 86 . The positioning gear 86 is disengaged from the spool 20 with the spring 90 in the state shown in FIG. Therefore, even if the spool 20 rotates EA, the positioning gear 86 does not rotate and is stopped. As a result, the distance between the stop gear 82 and the positioning gear 86 gradually decreases.

When the stop gear 82 rotates a predetermined number of times, the stop gear 82 comes into contact with the positioning gear 86 as shown in FIG. 14, and further screwing is disabled. As a result, the spool 20 is prevented from rotating by the locking base 40 via the stop gear 82 and the positioning gear 86 . By stopping the rotation of the spool 20 in this manner, further webbing withdrawal is stopped.

The above-described embodiment is an example of the present invention, and the present invention may be made into aspects other than those described above.

1 Seatbelt Retractor 10 Frame 16a Sawtooth 20 Spool 22 Left Flange 23 Right Flange 29 Inner Hole 30 Return Spring Unit 40 Locking Base 41 Flange Part 42 Shaft Part 42c Male Thread 43 Pawl 50 Lock Starting Unit 52 Lock Assy 60 Pretensioner 70 Torsion Bar 80 paddle wheel 82 stop gear 86 positioning gear 90 spring 91, 92 folded piece 93 main plate portion 110 groove

Claims (12)

a frame supporting the spool and locking base;
a tubular spool having a first inner hole for winding the webbing;
the locking base coaxially adjacent to the spool and having a second bore and coupled to the spool by a torsion bar;
the torsion bar inserted through the first inner hole of the spool and the second inner hole of the locking base, having one end non-rotatably connected to the spool and the other end non-rotatably connected to the locking base;
a pretensioner that rotates the locking base in the webbing winding direction,
A seat belt retractor in which the torsion bar is torsionally deformed when a tensile force of a predetermined value or more is applied to the webbing in a state where the locking base is locked,
A male screw is provided on the outer peripheral surface of the locking base,
Female threads on the inner peripheral surfaces of the stop gear and the positioning gear are screwed into the male threads, respectively,
In the state before the vehicle collision, the stop gear and the positioning gear are separated by a predetermined distance,
When the locking base and the spool are rotated by the pretensioner drive, the stop gear and the positioning gear rotate integrally with the locking base,
A seat belt retractor in which the stop gear spirals along the locking base toward the positioning gear when the spool is rotated by EA operation and the locking base stops rotating. 2. A seat belt retractor according to claim 1, wherein sliding resistance is provided in a sliding portion between said male screw of said locking base and said positioning gear. The locking base includes a flange portion, a tubular shaft portion having the second inner hole and protruding from the center portion of the flange portion, and an outer peripheral surface of the shaft portion on the tip end side in the projecting direction. and a receiving portion provided on the shaft portion for receiving force from the pretensioner,
3. The seat belt retractor according to claim 1, wherein the female threads of the inner peripheral surfaces of the stop gear and the positioning gear are screwed into the male threads. The stop gear is positioned on the tip end side of the shaft portion of the male screw on the outer peripheral surface of the shaft portion in a state before the vehicle collision,
The positioning gear is positioned closer to the proximal end of the shaft than the stop gear,
The EA operation causes the spool to rotate while the torsion bar is twisted, and when the locking base stops rotating, the stop gear spirals toward the positioning gear and comes into contact with the positioning gear. The seat belt retractor according to claim 3, wherein: The stop gear is always configured to rotate integrally with the spool,
The positioning gear is configured to be disengaged from the spool in the event of a heavy collision that causes a deceleration greater than or equal to a predetermined value, and at other times the positioning gear is linked to the spool and rotates integrally with the spool. The seat belt retractor according to claim 3 or 4. A locking portion extending in the axial direction is provided on the inner peripheral surface of the first inner hole of the spool,
The seat belt retractor according to any one of claims 3 to 5, wherein the stop gear has an engaging portion engaged with the engaging portion. 7. The seat belt retractor according to claim 6, wherein the locking portion is groove-shaped, and the engaging portion is a projection projecting from the outer peripheral surface of the stop gear. The positioning gear has a radially elastically deformable spring provided on its outer peripheral surface,
The spring is engaged with the locking portion when the centrifugal force acting on the spring is smaller than a predetermined value,
When the centrifugal force exceeds a predetermined value, the spring elastically deforms in the radial direction. 8. The seat belt retractor according to claim 6 or 7, wherein the spring is disengaged from the engaging portion by approaching, and the connection between the positioning gear and the spool is released. The spring has a main plate portion extending in a direction along the axis of the positioning gear,
One end side of the main plate portion is held by the positioning gear,
9. The seat belt retractor according to claim 8, wherein the other end of the main plate portion is elastically deformable in the radial direction of the positioning gear due to centrifugal force. A folded portion having a shape folded back so as to overlap the main plate portion is provided on the other end side of the main plate portion of the spring,
Before the vehicle crashes, the folded portion stands up in the direction from the main plate toward the outer peripheral surface of the positioning gear, and the leading end of the folded portion is engaged with the outer peripheral surface of the positioning gear, resulting in an upright state. 10. The seat belt retractor of claim 9, wherein the retractor is retained. When a centrifugal force greater than or equal to a predetermined value acts on the spring, the main plate portion is elastically deformed radially from the positioning gear to release the engagement between the folded portion and the outer peripheral surface of the positioning gear, and the folded portion is released. The part returns to its original shape along the main plate part,
After that, when the centrifugal force acting on the spring becomes smaller than the predetermined value, the main plate portion assumes a shape along the outer peripheral surface of the positioning gear, and the spring disengages from the engaging portion. 11. The seat belt retractor according to 10. The seat belt retractor according to any one of claims 9 to 11, wherein a weight portion is provided on the other end side of the main plate portion.

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