Patent ID: 7270017

Claim:
A torque measuring device for a rotating body, the device comprising: (a) a rotary section having a driving side flange, a driven side flange and a hollow cylindrical portion interposed between the driving side flange and the driven side flange, the rotary section being integrally formed as one piece, and being made of an iron magnetic material; (b) a stationary section positioned for opposing an outer circumference of the driven side flange; (c) a strain gauges attached to an inner circumferential surface of the hollow cylindrical portion; (d) a rotary transformer including a primary coil disposed on an inner circumference of the stationary section, and a secondary coil disposed on an outer circumference of the driven side flange of the rotary section, wherein the primary coil and the secondary coil are arranged to face each other through a gap, wherein an electric power is transmitted from the stationary section to the rotary section by electromagnetic induction, a torque generated at a rotating body is detected at the rotary section by means of the electric power transmitted, and wherein a detection result is transmitted from the rotary section to the stationary section; (e) a capacitor connected in series at a side of the secondary coil of the rotary transformer, whereby a combination of the capacitor and a leakage inductance of the rotary transformer causes a large output voltage at the secondary side of the rotary transformer; and, (f) a rectifying and smoothing circuit connected at the secondary coil of the rotary transformer, wherein the capacitor is connected between the secondary coil and the rectifying and smoothing circuit.