Patent ID: 8660743
Filing Date: 2014-02-25
Classification: B62D,G01L

Abstract:
1. A torque detection device comprising; a resolver unit including a first resolver and a second resolver, the first resolver having a first excitation coil supplied with an excitation AC signal, a first sin phase detection coil which outputs a voltage signal having an amplitude corresponding to the sin value of a rotational angle of a shaft at a first axial position thereof, and a first cos phase detection coil which outputs a voltage signal having an amplitude corresponding to the cos value of the rotational angle of the shaft at the first axial position thereof, the second resolver having a second excitation coil supplied with an excitation AC signal, a second sin phase detection coil which outputs a voltage signal having an amplitude corresponding to the sin value of a rotational angle of the shaft at a second axial position thereof, and a second cos phase detection coil which outputs a voltage signal having an amplitude corresponding to the cos value of the rotational angle of the shaft at the second axial position thereof; and torque computation section which supplies the excitation AC signals to an excitation AC signal input section of the first excitation coil and an excitation AC signal input section of the second excitation coil via individual excitation lines, inputs the voltage signals from a signal output section of the first sin phase detection coil, a signal output section of the first cos phase detection coil, a signal output section of the second sin phase detection coil, and a signal output section of the second cos phase detection coil via individual detection lines, calculates a first rotational angle of the shaft at the first axial position and a second rotational angle of the shaft at the second axial position on the basis of the voltage signals, and calculates a torque acting around the axis of the shaft on the basis of the calculated first and second rotational angles, wherein the resolver unit includes a first inter-coil resistor element which electrically connects the signal output section of one of the first sin phase detection coil and the first cos phase detection coil of the first resolver and the signal output section of one of the second sin phase detection coil and the second cos phase detection coil of the second resolver, and a second inter-coil resistor element which electrically connects the signal output section of the other of the first sin phase detection coil and the first cos phase detection coil of the first resolver and the signal output section of the other of the second sin phase detection coil and the second cos phase detection coil of the second resolver; and the torque computation section includes: a coil drive circuit which supplies a sin wave signal for excitation to one of the first excitation coil and the second excitation coil and supplies a cos wave signal for excitation to the other of the first excitation coil and the second excitation coil, the cos wave signal for excitation having a frequency identical with that of the sin wave signal for excitation and having a phase delay of 90° in relation to the sin wave signal for excitation, and separation means which separates excitation sin wave signal components corresponding to the sin wave signal for excitation, and excitation cos wave signal components corresponding to the cos wave signal for excitation, from composite signals which are input via the detection lines and including the voltage signals output from the first resolver and the second resolver in a mixed manner.