Vehicular seats

1. A vehicle seat comprising:

a back frame having a generally rectangular shape;

a frame member having a shape corresponding to a part of the back frame and being separate and attached to the back frame;

a sheet member attached to the frame member in a tensioned state;

a cushion pad mounted on a front surface of the frame member; and

a regulation structure provided on the frame member and the cushion pad, and the regulation structure configured to prevent the cushion pad from shifting along the front surface of the frame member, the regulation structure comprising:

at least one rib extending along the frame member and provided on the frame member; and

at least one slit extending along the cushion pad and provided in the cushion pad, wherein

the at least one rib is inserted into the at least one slit,

the at least one rib comprises a bent portion bending in a front-back direction and a seat width direction, and

the at least one rib has an S-shape in both the front-back direction and the seat width direction.

2. The vehicle seat of claim 1 , wherein the frame member is made of resin and is molded integrally with an outer peripheral edge of the sheet member.

3. The vehicle seat of claim 1 , wherein

the cushion pad comprises a left cushion pad and a right cushion pad, wherein the frame member has left and right side portions extending vertically, and wherein

the left cushion pad and the right cushion pad, respectively, extend along the left and right side portions of the frame member.

4. The vehicle seat of claim 1 , further comprising a pad cover attached on the frame member so that the pad cover covers the cushion pad.

5. The vehicle seat of claim 1 , wherein the at least one rib has a plurality of protrusion portions that are arranged in a longitudinal direction of the frame member and protrude toward the at least one slit.

6. The vehicle seat of claim 5 , wherein each of the plurality of protrusions has a tapered surface including a plurality of concentric steps that engage the at least one slit.

7. A vehicle seat comprising:

a back frame having a generally rectangular shape;

a frame member having a shape corresponding to a part of the back frame and being separate and attached to the back frame;

a sheet member attached to the frame member in a tensioned state;

a cushion pad mounted on a front surface of the frame member; and

a regulation structure provided on the frame member and the cushion pad, and the regulation structure configured to prevent the cushion pad from shifting along the front surface of the frame member, the regulation structure comprising:

at least one rib extending along the frame member and provided on the frame member; and

at least one slit extending along the cushion pad and provided in the cushion pad, wherein

the at least one rib is inserted into the at least one slit,

the at least one rib has an upper part spaced from a lower part

the upper part is angled downwardly toward a central axis of the width of the seat, and the lower part is angled upwardly toward the central axis of the width of the seat, and

the at least one slit has an upper part spaced from a lower part and the upper part and the lower part have an inclination angle corresponding to the upper part and the lower part of the at least one rib.

8. The vehicle seat of claim 7 , wherein the frame member is made of resin and is molded integrally with an outer peripheral edge of the sheet member.

9. The vehicle seat of claim 7 , wherein

the cushion pad comprises a left cushion pad and a right cushion pad, wherein the frame member has left and right side portions extending vertically, and

the left cushion pad and the right cushion pad, respectively, extend along the left and right side portions of the frame member.

10. The vehicle seat of claim 7 , further comprising a pad cover attached on the frame member so that the pad cover covers the cushion pad.

11. A vehicle seat comprising:

a back frame having a generally rectangular shape;

a frame member having a shape corresponding to a part of the back frame and being separate and attached to the back frame;

a sheet member attached to the frame member in a tensioned state;

a cushion pad mounted on a front surface of the frame member; and

a regulation structure provided on the frame member and the cushion pad, and the regulation structure configured to prevent the cushion pad from shifting along the front surface of the frame member, the regulation structure comprising:

at least one rib extending along the frame member and provided on the frame member; and

at least one slit extending along the cushion pad and provided in the cushion pad, wherein

the at least one rib is inserted into the at least one slit,

the at least one rib comprises a bent portion bending in a front-back direction and a seat width direction, and

the at least one rib has a plurality of protrusion portions that are arranged in a longitudinal direction of the frame member and protrude toward the at least one slit.

12. The vehicle seat of claim 11 , wherein the frame member is made of resin and is molded integrally with an outer peripheral edge of the sheet member.

13. The vehicle seat of claim 11 , wherein

the cushion pad comprises a left cushion pad and a right cushion pad, wherein the frame member has left and right side portions extending vertically, and

the left cushion pad and the right cushion pad, respectively, extend along the left and right side portions of the frame member.

14. The vehicle seat of claim 11 , further comprising a pad cover attached on the frame member so that the pad cover covers the cushion pad.

15. The vehicle seat of claim 11 , wherein the at least one rib has an S-shape in both a front-back direction and a seat width direction.

16. The vehicle seat of claim 11 , wherein each of the plurality of protrusions has a tapered surface including a plurality of concentric steps that engage the at least one slit.