Patent ID: 7104145
Filing Date: 2006-09-12
Classification: B62D,G01L

Abstract:
1. A torque sensor comprising: a first shaft; a second shaft capable of performing relative rotation, elastically, with respect to said first shaft; a first alternating signal source which outputs a first alternating signal the phase of which changes in accordance with change in the rotation angle of said first shaft; a second alternating signal source which outputs a second alternating signal the phase of which changes in accordance with change in the rotation angle of said second shaft; and an output signal processing section which outputs a phase difference correspondence signal the waveform of which changes in accordance with change in the phase difference between said first alternating signal and said second alternating signal, wherein said first alternating signal source has a first detector and a first signal processing section; taking KE as a coefficient, ω as the angular frequency of an excitation signal, t as the time and θ as the rotation angle of the first shaft, said first detector outputs a first sinusoidal amplitude signal expressed by KE sin(ωt) sin θ and a first cosinusoidal amplitude signal expressed by KE sin(ωt) cos θ, when an excitation signal proportional to sin (ωt) is input; said first signal processing section has a first resistance and a first capacitor connected mutually in series in a circuit which connects the output terminal of said first sinusoidal amplitude signal with the output terminal of said first cosinusoidal amplitude signal, said output signal processing section being connected to between said first resistance and said first capacitor; the resistance value of said first resistance and the capacitance value of said first capacitor are set in such a manner that the cut-off frequency becomes said value of ω, when said first resistance and said first capacitor function as a low-pass filter for one of said first sinusoidal amplitude signal and said first cosinusoidal amplitude signal, while functioning as a high-pass filter for the other of said signals, said second alternating signal source has a second detector and a second signal processing section; taking KE as a coefficient, ω as the angular frequency of an excitation signal, t as the time and θ+Δθ as the rotation angle of the second shaft, said second detector outputs a second sinusoidal amplitude signal expressed by KE sin(ωt) sin(θ+Δθ) and a second cosinusoidal amplitude signal expressed by KE sin(ωt) cos(θ+Δθ), when an excitation signal proportional to sin(ωt) is input; said second signal processing section has a second resistance and a second capacitor connected mutually in series in a circuit which connects the output terminal of said second sinusoidal amplitude signal with the output terminal of said second cosinusoidal amplitude signal, said output signal processing section being connected to between said second resistance and said second capacitor; the resistance value of said second resistance and the capacitance value of said second capacitor are set in such a manner that the cut-off frequency becomes said value of ω, when said second resistance and said second capacitor function as a low-pass filter for one of said second sinusoidal amplitude signal and said second cosinusoidal amplitude signal, while functioning as a high-pass filter for the other of said signals; and a value corresponding to the torque transmitted by said first and second shafts being determined from said phase difference correspondence signal.