Tongue and seat belt device using the same

1. A tongue that is slidably supported by a seat belt, separates the seat belt into a shoulder belt and a lap belt, and has an engagement portion engageable with a buckle, the tongue has

a seat belt insertion hole that is provided so as to be elongated in a direction perpendicular to or substantially perpendicular to the engagement portion and allows the seat belt to be inserted therethrough; and

a seat belt slide portion that forms part of the seat belt insertion hole and has a seat belt slide surface against which the seat belt slides,

wherein the seat belt slide portion has a specified number of recess portions provided in the seat belt slide surface, and a specified number of projections are separately provided in the recess portions,

wherein the seat belt slide surface at least has a shoulder belt-side seat belt slide surface that is disposed on a shoulder belt side and extends continuously between both ends of the seat belt insertion hole in a longitudinal direction of the seat belt insertion hole, and

wherein, relative to a position where the distance between the shoulder belt-side seat belt slide surface and an edge of the engagement portion forming a boundary of the insertion hole in a direction perpendicular to or substantially perpendicular to the longitudinal direction of the seat belt insertion hole is a minimum distance, the shoulder belt-side seat belt slide surface extends from the shoulder belt side to a lap belt side, and part of the shoulder belt-side seat belt slide surface is positioned on the lap belt side relative to the position where the distance is the minimum.

2. The tongue according to claim 1 , wherein a cross section, which is perpendicular to or substantially perpendicular to the longitudinal direction of the seat belt insertion hole, of an outer circumferential surface of each of the recess portions has an arc shape.

3. The tongue according to claim 1 , wherein the seat belt slide surface has a lap belt-side seat belt slide surface that is disposed on the lap belt side and extends in the longitudinal direction of the seat belt insertion hole.

4. The tongue according to claim 1 , wherein, the seat belt slide surface has a first and second-end seat belt slide surfaces that is disposed at both end portions in the longitudinal direction of the seat belt insertion hole and extend in the direction perpendicular to or substantially perpendicular to the longitudinal direction of the seat belt insertion hole.

5. The tongue according to claim 4 ,

wherein a plurality of the recess portions are provided, and

wherein, the seat belt slide surface has an intermediate seat belt slide surface that is disposed between the plurality of recess portions and extends in the direction perpendicular to or substantially perpendicular to the longitudinal direction of the seat belt insertion hole.

6. The tongue according to claim 1 , wherein, the projections do not project further to an outside than the seat belt slide surface from the recess portions.

7. The tongue according to claim 6 , wherein each of the projections has a substantially spherically shaped tip end.

8. A seat belt device at least comprising:

a seat belt;

a seat belt retractor that retracts the seat belt;

a tongue slidably supported by the seat belt; and

a buckle, into which the tongue is inserted and with which the tongue is engaged,

wherein the seat belt is worn by an occupant when the tongue is inserted into and engaged with the buckle, and

wherein the tongue is according to claim 1 .

9. A tongue that is slidably supported by a seat belt, separates the seat belt into a shoulder belt and a lap belt, and has an engagement portion engageable with a buckle, the tongue has a seat belt insertion hole that is provided so as to be elongated in a direction perpendicular to or substantially perpendicular to the engagement portion and allows the seat belt to be inserted therethrough; and

a seat belt slide portion that forms part of the seat belt insertion hole and has a seat belt slide surface against which the seat belt slides,

wherein the seat belt slide portion has a specified number of recess portions provided in the seat belt slide surface, and a specified number of projections are separately provided in the recess portions,

wherein the seat belt slide surface at least has a shoulder belt-side seat belt slide surface that is disposed on a shoulder belt side and extends in a longitudinal direction of the seat belt insertion hole, and

wherein, relative to a position where the distance between the shoulder belt-side seat belt slide surface and an edge of the engagement portion forming a boundary of the insertion hole in a direction perpendicular to or substantially perpendicular to the longitudinal direction of the seat belt insertion hole is a minimum distance, the shoulder belt-side seat belt slide surface extends from the shoulder belt side to a lap belt side, and part of the shoulder belt-side seat belt slide surface is positioned on the lap belt side relative to the position where the distance is the minimum,

wherein, the seat belt slide surface has a first and second-end seat belt slide surfaces that is disposed at both end portions in the longitudinal direction of the seat belt insertion hole and extend in the direction perpendicular to or substantially perpendicular to the longitudinal direction of the seat belt insertion hole,

wherein a plurality of the recess portions are provided, and

wherein, the seat belt slide surface has an intermediate seat belt slide surface that is disposed between the plurality of recess portions and extends in the direction perpendicular to or substantially perpendicular to the longitudinal direction of the seat belt insertion hole.