TECHNICAL FIELD

The present disclosure relates to the field of automobile seats, in particular, to shoulder adjustment mechanisms for seat backrests.

BACKGROUND ART

With the development of the automobile industry and the changes in the automobile market, in order to improve user experiences, more and higher demands are put forward for functions and comfortability of the automobile.

Referring to FIG. 1, a structural schematic view of a shoulder adjustment mechanism for a seat backrest in the prior art is shown. Referring to FIG. 2, a front view of the shoulder adjustment mechanism for a seat backrest in the prior art is shown. As shown in FIG. 1 and FIG. 2, a motor 10a is adopted to drive a main movement pair 20a to move up and down and meanwhile rotate about a bolt fixing point 30A, to thereby realize adjustment of the shoulder. The mounting point and rotating point of the shoulder adjustment mechanism in the prior art are at the same point 30a, and the movement stroke for shoulder adjustment depends on the length b of the lead screw, so the movement stroke is difficult to increase. If it is expected to increase the movement stroke for shoulder adjustment, the shoulder adjustment mechanism needs to be made larger, which may lead to large occupation space, high cost and poor applicability of the shoulder adjustment mechanism.

CONTENT OF THE INVENTION

An object of the present disclosure is to overcome the shortcomings in the prior art, by providing a shoulder adjustment mechanism for a seat backrest to solve the problem that the movement stroke of the shoulder adjustment mechanism is difficult to increase in the prior art.

The aforesaid object is achieved by the following technical solution:

The present disclosure provides a shoulder adjustment mechanism for a seat backrest, comprising:

- an upper backrest frame and a lower backrest frame in an up-and-down arrangement, each of the upper backrest frame and the lower backrest frame including a first side and a second side opposing to each other in a left-right direction, a third side facing a seat, and a fourth side facing away from the seat;
- a pair of first hinges hingedly connected to the first sides and the second sides of the upper backrest frame and the lower backrest frame and close to the third sides;
- a pair of second hinges hingedly connected to the first sides and the second sides of the upper backrest frame and the lower backrest frame and close to the fourth sides, the lower backrest frame being provided with sliding grooves for allowing movement of the second hinges;
- a first base fixed to the first side of the lower backrest frame;
- a first transmission structure rotatably mounted on the first base and in driving connection with a motor, wherein a spacing exists between a rotating position of the first transmission structure and a fixed position of the first base;
- a first lead screw in transmission connection with the first transmission structure, wherein a top portion of the first lead screw is connected with one of the second hinges, and wherein the motor drives the first lead screw to move up and down through the first transmission structure, and accordingly the first lead screw brings the second hinges to move in the sliding grooves, thus realizing rotation of the upper backrest frame about the first hinges relative to the lower backrest frame.