A vehicle seat includes a base frame supported on a base, a seat cushion provided on the base frame, and a seat back, wherein the seat back is structured so that a plurality of seat back pieces are arranged in the up-and-down direction with a predetermined space; and the base frame or a lowermost seat back piece is attached with an attachment member that stands so as to be elastically deformed and be able to be twisted around an axis, and the plurality of seat back pieces are attached to the attachment member, respectively.
1. A vehicle seat comprising a base frame supported on a base, a seat cushion provided on the base frame, and a seat back, wherein:
the seat back is structured so that a plurality of seat back pieces are arranged in the up-and-down direction with a predetermined space;
the base frame or a lowermost seat back piece is attached with an attachment member that stands so as to be elastically deformed and be able to be twisted around an axis, and the plurality of seat back pieces are attached to the attachment member, respectively; and
a sleeve member is externally inserted into the attachment member and a lower end section of the sleeve member is fixed to the base frame or the lowermost seat back piece.
2. The vehicle seat as claimed in claim 1 , wherein the attachment member is a torsion bar.
3. The vehicle seat as claimed in claim 1 , wherein center parts in the width direction of the plurality of seat back pieces are attached to the attachment member, respectively.
4. The, vehicle seat as claimed in claim 1 , wherein:
the seat back pieces are linked to the attachment member by linking members; and
the sleeve member includes opening sections to which the linking members are inserted and which restrict twist of the seat back piece by an abutment of end sections of the opening sections with the linking members when the seat back piece and the attachment member are twisted around an axis by a predetermined amount.
5. The vehicle seat as claimed in claim 1 , wherein:
the sleeve member is attached with a pair of long backing plates in an axial direction of the sleeve member so that the backing plates protrude to an outer side in a diameter direction of the sleeve member; and
a back face of the seat back piece is attached with restriction members that restrict twist of the seat back piece by abutting with the backing plate when the seat back piece and the attachment member are twisted around an axis with a predetermined amount, and the restriction members are arranged to have a predetermined space to the backing plate.
6. The vehicle seat as claimed in claim 5 , wherein a distance between the backing plate and the restriction members increases toward a top seat back piece.
7. The vehicle seat as claimed in claim 1 , wherein an upper end section of the attachment member is attached with a headrest.