Center shaft torque sensor for electric power-assisted bicycle

The utility model discloses a center shaft torque sensor for an electric power-assisted bicycle. The center shaft torque sensor comprises a signal amplification circuit board and device, and an outputbody, a force measuring body, a rotating space ring, a pressure applying body, a pressure sensor and a force bearing body which are sequentially arranged on a center shaft in a sleeving manner, the force measuring body is slidably connected to the middle shaft through a spline; the axial component f directly acts on the pressure sensor which is fixed with the outer sleeve into a whole and is in anon-rotating state; an electric signal in proportional relation with the pedal force value is detected on the pressure sensor and is directly output; the pressure sensor part is only subjected to bypass component force of a pedal driving chain main loop; only about 1/10 of the pressure change of the pedal driving force is borne; the structure of the center shaft torque sensor is simplified, signal acquisition is more real