The utility model relates to a center shaft
torque sensor with a limiting function, and belongs to the field of power-assisted bicycles. The device comprises a middle shaft, a left bearing seat, a bearing, a protective sleeve, a right five-way seat, an elastic body, a needle bearing and a
strain gauge, the two ends of the protective sleeve are connected with the left bearing seat and the right five-way seat respectively, the bearing is installed between the left bearing seat and the middle shaft, the needle bearing is installed between the elastic body and the middle shaft, and the
strain gauge is installed between the elastic body and the middle shaft. The elastic body is located in the right five-way seat, the
strain gauge is pasted on the elastic body, two ends of the elastic body are respectively a fixed end and a free end, and the elastic body is structurally characterized in that the fixed end of the elastic body is fixed with the right five-way seat, the free end of the elastic body is provided with a limiting convex rib, and the limiting convex rib and the elastic body are of an integrated structure.