Torque sensor

• US 6,843,142 B2
• Filed: 04/01/2004
• Issued: 01/18/2005
• Est. Priority Date: 04/02/2003
• Status: Expired due to Fees

• Current Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Inventors: Nagase, Shigeki
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): MILLER, TAKISHA S
• Application Number:
  US10/816,088
• Publication Number:
  US 20040194557A1
• Time in Patent Office: 292 Days
• Field of Search: 738/62, 738/623.26, 738/620.8, 738/623.31, 738/623.32, 738/623.33, 738/623.38, 738/621.93, 738/623.21, 738/623.25, 738/623.35, 738/623.39
• US Class Current: 73/862.326
• CPC Class Codes: B62D 6/10 characterised by means for sensing or determining torque
• CPC Class Codes: G01L 3/104 involving permanent magnets
• CPC Class Codes: G01L 3/109 involving measuring phase difference of two signals or pulse trains
• CPC Class Codes: G01L 5/221 to steering wheels, e.g. for power assisted steering

Abstract

The torque sensor outputs a sinusoidal first alternating signal the phase of which changes in accordance with change in the rotation angle of a first shaft, and a sinusoidal second alternating signal the phase of which changes in accordance with change in the rotation angle of a second shaft capable of performing relative rotation, elastically, with respect to the first shaft. A phase difference correspondence signal the waveform of which changes in accordance with change in the phase difference between the first alternating signal and the second alternating signal is output. A value corresponding to the torque transmitted by the first and second shafts is determined from the phase difference correspondence signal. This value corresponding to the transmitted torque is corrected on the basis of a value corresponding to the difference between a first distortion indicator value which changes in accordance with the waveform distortion in the first alternating signal and a second distortion indicator value which changes in accordance with the waveform distortion in the second alternating signal.

Claims

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 sinusoidal 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 sinusoidal second alternating signal the phase of which changes in accordance with change in the rotation angle of said second shaft;

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;

a determining part which determines a first distortion indicator value which changes in accordance with the waveform distortion of said first alternating signal;

a determining part which determines a second distortion indicator value which changes in accordance with the waveform distortion of said second alternating signal; and

a correcting part which corrects the value corresponding to the torque which is determined from said phase difference correspondence signal and transmitted by said first and second shafts, on the basis of a value corresponding to the difference between said first distortion indicator value and said second distortion indicator value.

2. The torque sensor according to claim 1, wherein the time period from the time at which the value of said first alternating signal becomes zero until the time at which the integral value of said first alternating signal becomes zero is determined as said first distortion indicator value, and wherein the time period from the time at which the value of said second alternating signal becomes zero until the time at which the integral value of said second alternating signal becomes zero is determined as said second distortion indicator value.