Seat belt retractor

1. A seat belt retractor comprising:

a spool for retracting a seat belt, wherein the spool has one side in an axial direction of the spool and another side in the axial direction of the spool;

a torsion bar disposed inside the spool, wherein the torsion bar has one side in an axial direction of the torsion bar and another side in the axial direction of the torsion bar, wherein the one side of the torsion bar is connected to the one side of the spool, and configured to be capable of absorbing energy of movement of an occupant while being deformed under torsion by a relative displacement of the one side of the torsion bar and the another side of the torsion bar;

a pre-tensioner positioned at the another side of the spool and configured to generate a rotating drive force for rotating the spool in a retracting direction of the seat belt in a condition of rapid deceleration of a motor vehicle;

a locking device capable of locking the another side of the torsion bar such that a rotation of the spool in a withdrawal direction of the seat belt is suppressed at both an operating time of the pre-tensioner when the pre-tensioner is activated and a non-operating time of the pre-tensioner when the pre-tensioner is not activated; and

a locking member disposed at the another side of the spool and connected to the another side of the torsion bar,

wherein the locking device comprises a locking gear disposed at the one side of the spool, a joint pin, and a pawl rotatably provided in the locking member, and

wherein the locking device is configured to lock the another side of the torsion bar by locking the locking member on a frame with the pawl at the non-operating time of the pre-tensioner by rotating the pawl in a locking direction using the locking gear via the joint pin.

2. The seat belt retractor according to claim 1 , wherein the joint pin is configured to be ruptured when a deformation under torsion is generated in the torsion bar.

3. The seat belt retractor according to claim 2 , further comprising an urging device for urging the pawl in an unlocking direction where a locking operation for the locking member is not performed when the joint pin is ruptured, and wherein the pawl is configured to move in the locking direction such that the locking member is locked by a centrifugal force against an urging force of the urging device when the seat belt is withdrawn at or greater than a predetermined speed.

4. The seat belt retractor according to claim 1 , further comprising a deceleration detecting device for detecting deceleration of the motor vehicle, wherein the locking device is configured to lock the another side of the torsion bar when the deceleration detecting device detects a predetermined or greater deceleration.

5. The seat belt retractor according to claim 4 , wherein the deceleration detecting device is provided at the one side of the spool.

6. A seat belt apparatus comprising:

a seat belt retractor comprising:

a spool, wherein the spool has one side in an axial direction of the spool and another side in the axial direction of the spool,

a torsion bar disposed inside the spool, wherein the torsion bar has one side in an axial direction of the torsion bar and another side in the axial direction of the torsion bar, wherein the one side of the torsion bar is connected to the one side of the spool, and configured to be capable of absorbing energy of movement of an occupant while being deformed under torsion by a relative displacement of the one side of the torsion bar and the another side in the axial direction of the torsion bar,

a pre-tensioner positioned at the another side of the spool and configured to generate a rotating drive force for rotating the spool in a retracting direction of a seat belt in a condition of rapid deceleration of a motor vehicle,

a locking device capable of locking the another side of the torsion bar such that a rotation of the spool in a withdrawal direction of the seat belt is suppressed at both an operating time of the pre-tensioner when the pre-tensioner is activated and a non-operating time of the pre-tensioner when the pre-tensioner is not activated, and

a locking member disposed at the another side of the spool and connected to the another side of the torsion bar;

the seat belt configured to be retracted by the seat belt retractor in a manner so as to be capable of being withdrawn, and restraining the occupant;

a tongue provided on the seat belt; and

a buckle device configured to be latched with the tongue,

wherein the locking device comprises a locking gear disposed at the one side of the spool, a joint pin, and a pawl rotatably provided in the locking member,

wherein the locking device is configured to lock the another side of the torsion bar by locking the locking member on a frame with the pawl at the non-operating time of the pre-tensioner by rotating the pawl in a locking direction using the locking gear via the joint pin.