Vehicle seat
A seatback of a vehicle seat includes a seatback frame and a backrest attached to the seatback frame. The backrest includes a first supporting area configured to receive a load of a shoulder of the occupant, and a second supporting area configured to receive a load of a spine area of the occupant. Support stiffness in the first supporting area for a vertical load is lower than that in the second supporting area. Support stiffness in the second supporting area for a shearing load is higher than that in the first supporting area.
1. A vehicle seat, comprising:
a seatback including a seatback frame and a backrest attached to the seatback frame for supporting a back of an occupant sitting on the vehicle seat,
wherein the backrest includes
a first supporting area configured to receive a load of a shoulder of the occupant including a shoulder blade, and
a second supporting area configured to receive a load of a spine area of the occupant between the shoulders,
wherein vertical support stiffness in the first supporting area for a load perpendicular to the backrest is lower than that in the second supporting area, and
wherein shear support stiffness in the second supporting area for a load in a shearing direction is higher than that in the first supporting area.
2. The vehicle seat as claimed in claim 1 ,
wherein the first supporting area comprises a net member including strings intersecting each other, and
wherein the second supporting area comprises a sheet member.
3. The vehicle seat as claimed in claim 2 ,
wherein the net member further comprises a hub member disposed on a back face of the second supporting area corresponding to the spine area of the occupant,
wherein the intersecting strings include
a plurality of first strings drawn radially between the hub member and the frame, and
a plurality of second strings drawn to connect the first strings, and
wherein the plurality of first strings and the plurality of second strings are covered by the sheet member in the second supporting area.
4. The vehicle seat as claimed in claim 3 ,
wherein the backrest further includes
a third supporting area configured to support a lumber spine of the occupant sitting on the vehicle seat, the third supporting area arranged below the second supporting area, and
a plurality of third strings intersecting the plurality of first strings in the third supporting area.
5. The vehicle seat as claimed in claim 4 ,
wherein a material of the plurality of third strings has a lower tensile strength than that of the plurality of first strings.
6. The vehicle seat as claimed in claim 5 ,
wherein shear support stiffness in the third supporting area for a load in the shearing direction is lower than that in the second supporting area.
7. The vehicle seat as claimed in claim 1 ,
wherein a boundary between the first supporting area and the second supporting area is configured to curve along an outline of the shoulder blade.
8. The vehicle seat as claimed in claim 1 , further comprising:
a vacant area formed in the second supporting area at a location adapted to be corresponding to a neck of the occupant.
9. The vehicle seat as claimed in claim 1 ,
wherein the backrest further includes a third supporting area configured to support a lumber spine of the occupant sitting on the vehicle seat, and
wherein shear support stiffness in the third supporting area for a load in the shearing direction is lower than that in the second supporting area.
10. The vehicle seat as claimed in claim 9 ,
wherein the third supporting area comprises a net member.
11. The vehicle seat as claimed in claim 10 ,
wherein the first supporting area comprises a further net member, and
wherein the second supporting area comprises a sheet member.
12. The vehicle seat as claimed in claim 11 ,
wherein the sheet member is X-shaped.
13. The vehicle seat as claimed in claim 9 ,
wherein the second supporting area comprises a sheet member, and
wherein the third supporting area comprises a further seat member having shear support stiffness for a load in the shearing direction lower than that of the sheet member.
14. The vehicle seat as claimed in claim 9 ,
wherein the second supporting area comprises a sheet member, and
wherein the third supporting area comprises a further seat member having the same material as the sheet member.
15. The vehicle seat as claimed in claim 9 ,
wherein the vertical support stiffness in the first supporting area for a load perpendicular to the backrest is lower than that in the third supporting area.
16. The vehicle seat as claimed in claim 1 ,
wherein the first supporting area comprises a net member including strings intersecting each other,
wherein the second supporting area comprises a sheet member, and
wherein the sheet member is X-shaped.
17. The vehicle seat as claimed in claim 1 ,
wherein the first supporting area comprises a net member including strings intersecting each other, and
wherein the second supporting area comprises a sheet member, and the sheet member does not cover the intersecting strings in the first supporting area.
18. The vehicle seat as claimed in claim 1 ,
wherein the second supporting area comprises a sheet member, and
wherein a lower edge of the sheet member is curved upwardly and adapted to extend along latissimus dorsi muscle of the occupant.
19. The vehicle seat as claimed in claim 1 ,
wherein the vertical support stiffness in the first supporting area for a load perpendicular to the backrest is higher than the shear support stiffness in the first supporting area for a load in the shearing direction.
20. The vehicle seat as claimed in claim 1 ,
wherein the backrest is free of rotary joints.