Back frame for seat, particularly for power vehicle seat

A back frame for a seat, particularly a power vehicle seat, comprising

• a transverse member;
• and
• two side members each having one end connected with said transverse member in a connecting point and another end provided with a connecting ear for connecting with a hinge of a seat pad frame, each of said side members having a U-shaped cross section with a web, and front and rear legs connected with said web and located at opposite sides of a center plane extending between said legs, said web of each of said side members narrowing from said connecting ear to said connecting point of the respective side member, said rear leg of each of said side members also narrowing from said connecting ear to said connecting point of the respective side member and being longer than said front leg so that the cross section of each of said side members is asymmetrical relative to the center plane of said cross section and the asymmetry reduces from the other end to said one end, at least one leg of at least one side member having a part which extends transverse to said center axis of said cross section of said at least one side member so that in the event of an accident and resulting high loading of said transverse member said side members are turnably deflected without breaking in the region of said one end.