Seat belt retractor

1. A seatbelt retractor, comprising:

a retractor frame;

a spindle rotatably supported by the retractor frame and capable of winding up a seatbelt therearound;

a torsion bar provided in the spindle and having a first end coupled to the spindle and a plurality of shaft parts having different torsional torque characteristics;

an emergency locking mechanism capable of locking rotation of the spindle by locking a second end of the torsion bar;

a torque tube coupled to the torsion bar between the plurality of shaft parts and provided in the spindle; and

a switching mechanism implementing switching between a first state in which the torque tube rotates together with the spindle and a second state in which the torque tube rotates relatively to the spindle,

the switching mechanism further comprising:

a locking mechanism locking the torque tube with respect to the spindle so that the torque tube rotates together with the spindle;

a switching member capable of rotating to unlock the locking mechanism;

a housing storing the switching member, a driving member adapted to activate the switching member, and a gas generator that generates gas for pushing out the driving member upon activation of the switching mechanism,

the housing of the switching mechanism having a protrusion that protrudes in an incoming direction of the switching member at an abutment part, the switching member hitting the abutment part when the switching member is rotated by the driving member.

2. The seatbelt retractor according to claim 1 , further comprising the protrusion deforms when the switching member hits the protrusion.

3. The seatbelt retractor according to claim 1 , wherein the locking mechanism comprises:

a locking member attached on a spindle side in a through hole provided radially through the spindle and rotatable between a locking position associated with the first state in which the torque tube is locked with respect to the spindle so that the torque tube rotates together with the spindle and an unlocking position associated with the second state in which the torque tube is unlocked from the spindle so that the torque tube rotates relatively to the spindle, and

a restriction ring radially abutting against the locking member to restrict the locking member in the locking position,

the switching member is a switch ring having an operated part that is movable axially from a first position in which the restriction ring abuts against the locking member, to a second position apart from the locking member and that is allowed to protrude radially and hit the protrusion at the abutment part, and

the protrusion extends axially to protrude in the incoming direction of the switching member.

4. The seatbelt retractor according to claim 3 , wherein the housing of the switching mechanism comprises a plurality of ramp surfaces inclined in a moving direction of the switch ring at a sliding surface on which the switch ring slides, and

the switch ring moves axially by sliding along the plurality of ramp surfaces while rotating in a circumferential direction by activation of the driving member.

5. The seatbelt retractor according to claim 3 , further comprising the protrusion is formed into a substantially triangular shape and collapses and deforms as the operating part of the switch ring when moving axially hits the protrusion wherein the switch ring is restricted from shifting in the axial direction.

6. The seatbelt retractor according to claim 1 , further comprising the switching member after hitting the abutment part when the switching member is rotated by the driving member is restricted from further movement in the circumferential direction.

7. The seatbelt retractor according to claim 1 , further comprising the protrusion is formed integrally with the housing.