Seat belt locking buckle and seat belt apparatus including seat belt locking buckle

1. A seat belt locking buckle directly or indirectly mounted on one of a seat belt and a vehicle body, the seat belt locking buckle securing a top end of the seat belt to the vehicle body by latching a seat belt locking tongue mounted directly or indirectly on the other of the seat belt and the vehicle body, the seat belt locking buckle comprising:

a seat belt locking tongue insertion port that allows a tongue latch member of the seat belt locking tongue to be inserted into the seat belt locking buckle;

a buckle latch member having a substantially solid cylindrical shape, the buckle latch member being disposed so as to be rotatable about an axis extending in a direction perpendicular or substantially perpendicular to a plane of the motion of the tongue latch member inserted into the seat belt locking buckle through the seat belt locking tongue insertion port at least between a non-latch position at which the tongue latch member is not latchable by the buckle latch member and a latch position at which the tongue latch member is latchable by the buckle latch member;

a latch member rotation control member that disables rotation of the buckle latch member and holds the buckle latch member at the non-latch position when the tongue latch member is not inserted into the seat belt locking buckle and that enables rotation of the buckle latch member when moved by the tongue latch member inserted into the seat belt locking buckle along a plane parallel or substantially parallel to the plane of the motion of the tongue latch member; and

a latch-member operating member that moves along a plane parallel or substantially parallel to the plane of the motion of the tongue latch member when the buckle latch member is rotatable and pushes the buckle latch member to rotate the buckle latch member from the non-latch position to the latch position.

2. The seat belt locking buckle according to claim 1 ,

wherein the latch-member operating member is separated from the buckle latch member and does not push the buckle latch member when the tongue latch member is not inserted into the seat belt locking buckle, and

wherein the latch-member operating member is in contact with the buckle latch member and pushes the buckle latch member when the latch member rotation control member is moved by the tongue latch member inserted into the seat belt locking buckle.

3. The seat belt locking buckle according to claim 1 , further comprising:

a first base and a second base,

wherein the first base and the second base are assembled together so that a space that allows the tongue latch member inserted through the seat belt locking tongue insertion port to be inserted thereinto is formed between the first base and the second base, and

wherein the buckle latch member includes a first latch guide portion and a second latch guide portion by which the assembled first base and second base are sandwiched when the tongue latch member and the buckle latch member are latched together.

4. The seat belt locking buckle according to claim 3 , wherein the latch-member operating member rotates the buckle latch member from the non-latch position to the latch position by coming into contact with the first latch guide portion and pushing the first latch guide portion.

5. The seat belt locking buckle according to claim 4 ,

wherein the latch member rotation control member does not allow the latch-member operating member to be in contact with the first latch guide portion when the tongue latch member is not inserted into the seat belt locking buckle, and

wherein the latch member rotation control member causes the latch-member operating member to be in contact with the first latch guide portion when the latch member rotation control member is moved by the tongue latch member.

6. The seat belt locking buckle according to claim 3 , further comprising:

a cover that contains at least the buckle latch member, the latch member rotation control member, the latch-member operating member, the first base, and the second base, the cover having the seat belt locking tongue insertion port formed therein; and

a latch detection unit that protrudes from the cover to the outside of the cover when the seat belt locking tongue is not latched by the seat belt locking buckle and that retracts into the cover when the seat belt locking tongue is latched by the seat belt locking buckle.

7. The seat belt locking buckle according to claim 6 , wherein the latch detection unit is disposed in the latch-member operating member.

8. The seat belt locking buckle according to claim 1 , further comprising:

an ejector that urges the tongue latch member inserted into the seat belt locking buckle in a direction in which the tongue latch member is ejected from the seat belt locking buckle,

wherein the ejector serves as the latch member rotation control member.

9. A seat belt apparatus comprising:

a seat belt capable of restraining a vehicle occupant;

a seat belt retractor that retracts the seat belt therein;

a tongue slidably supported by the seat belt;

a buckle that allows the tongue to be inserted thereinto and engaged therewith;

a seat belt locking buckle directly or indirectly mounted on one of the seat belt and a vehicle body; and

a seat belt locking tongue directly or indirectly mounted on the other of the seat belt and the vehicle body, the seat belt locking tongue being latchable by the seat belt locking buckle,

wherein the seat belt locking buckle is the seat belt locking buckle according to claim 1 .

10. The seat belt apparatus according to claim 9 , wherein the tongue latch member includes a tongue insertion regulation portion that regulates the length of a portion of the tongue latch member that is inserted into the seat belt locking buckle to a predetermined length.

11. The seat belt apparatus according to claim 10 , wherein the tongue insertion regulation portion further functions as a tongue latch member wrong insertion preventing portion that prevents the tongue latch member from being accidentally turned over and inserted.

12. The seat belt apparatus according to claim 9 , wherein the tongue latch member includes a tongue latch member wrong insertion preventing portion that prevents the tongue latch member from being accidentally turned over and inserted.

13. The seat belt apparatus according to claim 12 , wherein the seat belt locking buckle includes a tongue latch member wrong insertion prevention portion insertion permitting portion formed in the seat belt locking tongue insertion port, and the tongue latch member wrong insertion prevention portion insertion permitting portion allows the tongue latch member wrong insertion preventing portion to pass therethrough.