WEBBING TAKE-UP DEVICE
FIG2 is an enlarged perspective view illustrating a locking mechanism of a webbing take-up device of an exemplary embodiment
As illustrated in FIG2, the rotatable locking section 20 is formed from a metal material. The rotatable locking section 20 is formed in a substantially half-moon shape as viewed along the axial direction. A circular support hole 20A is formed penetrating a central portion, including the center of gravity, of the rotatable locking section 20 in the axial direction. The rotatable locking section 20 is fixed to one axial direction side end portion of the spool 14 at a portion at the radial direction outer side of the rotation axis (center of rotation) of the spool 14 through a support pin 28 inserted through the support hole 20A. Two main engaging teeth 20B that engage with the fixed locking section 22, described later, are formed to an outer peripheral portion of one circumferential direction side (pull-out direction side) end portion of the rotatable locking section 20. The main engaging tooth 20B on the side closer to the support pin 28 is formed with a sub engaging tooth 20C on the other axial direction side (the opposite side to the arrow Z). A portion on one circumferential direction side of the sub engaging tooth 20C projects toward the one circumferential direction side with respect to the main engaging tooth 20B on the side closer to the support pin 28. In the present exemplary embodiment, the thickness (axial direction dimension) of the main engaging teeth 20B is set thicker than the thickness (axial direction dimension) of the sub engaging tooth 20C. Moreover, the rectangular block shaped permanent magnet 24 is fixed to an inner peripheral portion of an end portion on the one circumferential direction side (pull-out direction side) of the rotatable locking section 20. The rotatable locking section has a divided structure configured of the first rotatable locking section 52 and the second rotatable locking section 54, thereby enabling the respective weights of the first rotatable locking section 52 and the second rotatable locking section 54 to be reduced in comparison to the rotatable locking section 20 (see FIG2) described above. This thereby enables the kinetic energy of the first rotatable locking section 52 and the second rotatable locking section 54 as the spool 14 is rotated to be reduced. This thereby enables the impact when the second rotatable locking section 54 engages with the second fixed locking section 32 to be lessened, and also enables the impact when the first rotatable locking section 52 engages with the first fixed locking section 30 to be lessened.
enlarged perspective view
24
permanent magnet
28
support pin
14
spool
30
first fixed locking section
22
fixed locking section
18
locking mechanism locking mechanisms
20
rotatable locking section
16
frame
32
['1. A webbing take-up device (10) comprising: a spool (14) that takes up a webbing (12) worn by an occupant and that is rotated in a pull-out direction by the webbing being pulled out; a rotatable locking section (20) that is provided so as to be rotatable as a unit together with the spool and so as to be displaceable in a rotation-radial direction of the spool; a fixed locking section (22) that is provided at an outer side of the rotatable locking section in the rotation-radial direction of the spool, and that the rotatable locking section engages with resulting in pull-out direction rotation of the spool being locked; a restricting section (24, 26) that restricts displacement of the rotatable locking section toward the fixed locking section; and a displacement section (24, 26) that is actuated in a vehicle emergency so as to displace the rotatable locking section toward the fixed locking section against the restriction of displacement of the rotatable locking section by the restricting section, a restricting force of the rotatable locking section by the restricting section being set such that the rotatable locking section is displaced toward the fixed locking section by an inertial force that spins the rotatable locking section about its own center of rotation when the displacement section is deactivated and the spool has been rotated in the pull-out direction with an angular acceleration greater than a predetermined angular acceleration.', '2. The webbing take-up device of claim 1, wherein: the restricting section and the displacement section include: a permanent magnet (24) fixed to the rotatable locking section, and an electromagnet (26) formed from a magnetic material and including a core (24) disposed opposite the permanent magnet and a coil (36) disposed around the core; displacement of the rotatable locking section toward the fixed locking section is restricted by a magnetic force of the permanent magnet attracting the core; and the rotatable locking section is displaced toward the fixed locking section by a current being passed through the coil in one direction such that a magnetic force of repulsion from the permanent magnet is generated in the core.', '8. The webbing take-up device of claim 7, wherein: the fixed locking section includes a first fixed locking section (30) and a second fixed locking section (32) adjacent to each other in a rotation axis direction of the spool; the terminal portion is provided at the first fixed locking section; and the leading end portion is provided at the second fixed locking section.']