Torque detecting device

• US 4,991,447 A
• Filed: 11/02/1989
• Issued: 02/12/1991
• Est. Priority Date: 11/04/1988
• Status: Expired due to Term

• Current Assignee: Daido Tokushuko Kabushiki Kaisha, Nissan Motor Co., Ltd.
• Original Assignee: Daido Tokushuko Kabushiki Kaisha, Nissan Motor Co., Ltd.
• Inventors: Yahagi, Shinichiro, Aoki, Hiroyuki, Saito, Takanobu
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/430,406
• Time in Patent Office: 467 Days
• Field of Search: 73/862.36, 73/DIG. 2
• US Class Current: 73/862.334
• CPC Class Codes: G01D 3/028 mitigating undesired influences, e.g. temperature, pressure
• CPC Class Codes: G01D 5/2208 by influencing the self-induction of the coils
• CPC Class Codes: G01R 33/18 Measuring magnetostrictive properties
• CPC Class Codes: Y10S 73/02 Magnetostrictive

Abstract

A torque detecting device has a measuring shaft, an excitation device and a detector for detecting a magnetostriction passing through said measuring shaft. The device is able to measure the torque with accuracy even if a temperature gradient is produced in the axial direction of the measuring shaft by making the measuring shaft from a material having specified electromagnetic characteristics at least in a part in which said magnetostrictive force is detected.

Claims

1. A torque detecting device having a measuring shaft, excitation means for forming a magnetic circuit wherein said measuring shaft is a part of said magnetic circuit, and detection means for detecting a magnetostriction passing through said measuring shaft, wherein said measuring shaft has following electromagnetic characteristics at least in a part in which said magnetostriction is detected:

Electric resistivity ρ

_RT of not less than 30 μ

Ω

-cm at room temperature;

temperature coefficient α

ρ

of electric resistivity ρ

of not more than 0.25×

10^-2 /°

C. at temperature of -50°

to 150°

C.; and

temperature coefficient α

_L of inductance L of not more than 0.07×

10^-2 /°

C. at temperature of -50°

to 150°

C.

2. A torque detecting device as set forth in claim 1, wherein a concave part and a convex part making a predetermined angle with the axial direction of said measuring shaft are formed with predetermined spacing on said measuring shaft.

3. A torque detecting device as set forth in claim 1, wherein said excitation means is an excitation coil forming a magnetic circuit wherein said measuring shaft is a part of said magnetic circuit and said detection means is a detection coil for detecting a magnetostriction passing through said measuring shaft.

4. A torque detecting device as set forth in claim 3, wherein said excitation coil and said detection coil are formed from a common coil with a common yoke.

5. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made, at least in a part in which the magnetostriction is detected, from a material comprising, by weight percentage of, not more than 1.5% of C., not more than 4.0% of Si, not more than 3.0% of Mn, and one or both of not more than 5.0% of Ni and not more than 5.0% of Cr, with the remainder being Fe and impurities.

6. A torque detecting device as set forth in claim 5, wherein said measuring shaft is carburized and the amount of C in the carburized layer is more than 0.1% but not more than 1.5%.

7. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made, at least in a part in which the magnetostriction is detected, from a material comprising, by weight percentage of, not more than 0.1% of C, not more than 3.0% of Mn, not more than 10% of Si and Al in total, in the range of 30 to 90% of Ni, and not more than 10% of Cu, Cr, Mo, Ti, W, V, Nb, Ta and Zr in total, with the remainder being substantially Fe.

8. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made, at least in a part in which the magnetostriction is detected, from a material comprising, by weight percentage of, not more than 0.1% of C, not more than 3.0% of Mn, in the range of 4 to 18% of Si and Al in total and not more than 10% of Co, Cu, Ni, Cr, Mo, W, V, Nb, Ta, Ti and Zr in total, with the remainder being substantially Fe.

9. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made, at least in a part in which the magnetostriction is detected, from a material comprising, by weight percentage of, not more than 0.1% of C, not more than 3.0% of Mn, not more than 10% of Si and Al in total, in the range of 5 to 35% of Cr and not more than 10% of Co, Cu, Ni, Mo, W, V, Nb, Ta, Ti and Zr, with the remainder being substantially Fe.

10. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made from a Fe--Co based high permeability material at least in a part in which the magnetostriction is detected.

11. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made from a Co based high permeability material at least in a part in which the magnetostriction is detected.

12. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made, at least in a part in which the magnetostriction is detected, from a material comprising, by weight percentage of, not more than 1.5% of C, not more than 4.0% of Si, not more than 3.0% of Nn, one or both of not more than 5.0% of Ni and not more than 5.0% of Cr, and at least one selected from not more than 1.0% of Cu, not more than 1.0% of Mo, not more than 0.05% of B, not more than 0.5% of W, not more than 0.5% of V, not more than 0.5% of Ti, not more than 0.5% of Nb, not more than 0.5% of Ta, not more than 0.5% of Zr, not more than 0.5% of Hf and not more than 0.1% of N, with the remainder being Fe and impurities.

13. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made, at least in a part in which the magnetostriction is detected, from a material comprising, by weight percentage of, not more than 1.5% of C, not more than 4.0% of Si, not more than 3.0% of Mn, one or both of not more than 5.0% of Ni and not more than 5.0% of Cr, one or both of not more than 3.0% of Al and not more than 5.0% of Co, and at least one selected from not more than 1.0% of Cu, and not more than 1.0% of Mo, not more than 0.05% of B, not more than 0.5% of W, not more than 0.5% of V, not more than 0.5% of Ti, not more than 0.5% of Nb, not more than 0.5% of Ta, not more than 0.5% of Zr, not more than 0.5% of Hf and not more than 0.1% of N, with the remainder being Fe and impurities.

14. A torque detecting device as set forth in claim 1, wherein said measuring shaft is made, at least in a part in which the magnetostriction is detected, from a material comprising, by weight percentage of, not more than 1.5% of C, not more than 4.0% of Si, not more than 3.0% of Mn, and one or both of not more than 5.0% of Ni and not more than 5.0% of Cr, at least one selected from not more than 1.0% of Cu, not more than 1.0% of Mo, not more than 0.05% of B, not more than 0.5% of W, not more than 0.5% of V, not more than 0.5% of Ti, not more than 0.5% of Nb, not more than 0.5% of Ta, not more than 0.5% of Zr, not more than 0.5% of Hf and not more than 0.1% of N, and at least one selected from not more than 0.5% of Pb, not more than 0.5% of Bi, not more than 0.5% of S, not more than 0.3% of P, not more than 0.5% of Te, not more than 0.5% of Se, and not more than 0.05% of Ca, with the remainder being Fe and impurities.