IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0402620
(2003-03-28)
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발명자
/ 주소 |
- Naidu, Malakondaiah
- Heremans, Joseph Pierre
- Nehl, Thomas Wolfgang
- Smith, John R.
- Fuller, Brian K
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출원인 / 주소 |
- Delphi Technologies, Inc.
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인용정보 |
피인용 횟수 :
9 인용 특허 :
83 |
초록
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A torque sensing apparatus for picking up a magnetic field of a magnetostrictive material disposed on a shaft, the torque sensing apparatus having: a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to the first
A torque sensing apparatus for picking up a magnetic field of a magnetostrictive material disposed on a shaft, the torque sensing apparatus having: a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to the first integrating ring at one end and the second integrating ring at the other end; an excitation coil; and a feedback coil; wherein the first integrating ring and the second integrating ring are configured to be positioned to pick up flux signals along the entire periphery of the ends of the magnetostrictive material.
대표청구항
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1. A torque sensing apparatus for picking up a magnetic field of a magnetostrictive material disposed on a shaft, comprising:a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to said first integrating ring at on
1. A torque sensing apparatus for picking up a magnetic field of a magnetostrictive material disposed on a shaft, comprising:a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to said first integrating ring at one end and said second integrating ring at the other end; an excitation coil; and a feedback coil wound about said excitation coil. 2. The torque sensing apparatus as in claim 1, wherein said first integrating ring, said second integrating ring, said first fluxgate return strip and said second fluxgate return strip are constructed out of a high-permeable material.3. The torque sensing apparatus as in claim 1, wherein said first integrating ring and said second integrating ring are configured to pick up magnetic flux along the periphery of the magnetostrictive material.4. The torque sensing apparatus as in claim 3, wherein said excitation coil comprises a first coil and a second coil, said first coil being wound about said first fluxgate return strip and said second coil being wound about said second fluxgate return strip and said first and said second coil are connected in series.5. The torque sensing apparatus as in claim 4, wherein said first integrating ring, said second integrating ring, said first fluxgate return strip and said second fluxgate return strip are constructed out of a high-permeable material and are disposed on a cylindrical member being configured to allow said shaft to be rotatably received therein.6. The torque sensing apparatus as in claim 3, wherein said excitation coil comprises a first coil and a second coil, said first coil being wound about said first fluxgate return strip and said second coil being wound about said second fluxgate return strip and said first and said second coil are connected in series to provide a measurement flux and said first integrating ring, said second integrating ring, said first fluxgate return strip and said second fluxgate return strip provide a low reluctance closed loop flux path.7. The torque sensing apparatus as in claim 6, wherein said first integrating ring and said second integrating ring are configured to be positioned to pick up flux signals along the entire periphery of the ends of the magnetostrictive material.8. The torque sensing apparatus as in claim 1, wherein said first integrating ring, said second integrating ring, said first fluxgate return strip and said second fluxgate return strip are constructed out of a high-permeable material and said first integrating ring and said second integrating ring are configured to pick up magnetic flux along the periphery of the magnetostrictive material and the torque sensing apparatus further comprises a pickup coil.9. The torque sensing apparatus as in claim 8, wherein the application of a torque to the shaft will provide an induced voltage in the pickup coil, the induced voltage contains a 2nd harmonic component which is extracted by a means of a lock-in amplifier and rectified and fed, as current, to the feedback coil via a voltage to current converter to nullify the 2nd harmonic component, wherein the 2nd harmonic voltage is proportional to the torque to the shaft.10. A torque sensing apparatus adapted for use with a magnetostrictive material disposed on a shaft, comprising:a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to said first integrating ring at one end and said second integrating ring at the other end to create a closed loop reluctance path; an excitation coil; a feedback coil; wherein said first fluxgate return strip and said second fluxgate return strip of the closed loop reluctance path are maintained just below a magnetic saturation point when only an excitation current flows through said excitation coil and the fluxgate return strips are magnetically saturated in one direction then in the other direction when an applied torque is encountered by the shaft, the magnetic saturation causes a DC offset in an excitation waveform of the excitation coil and the DC offset is used to provide a proportional current to the feedback coil to nullify the magnetic saturation of the fluxgates. 11. The torque sensing apparatus as in claim 1, further comprising a detection circuit for determining the torque applied to the shaft, said detection circuit comprises:a voltage source for applying a voltage to said excitation coil at a first frequency; a frequency doubler for doubling said first frequency to a second frequency; a lock-in amplifier for receiving signals related to the second harmonic voltage waveform on said feedback coil and a reference signal from said frequency doubler, said lock-in amplifier producing an output signal relating to the voltage sensed across said feedback coil; and a voltage to current converter configured to receive said output signal and convert it to a current wherein the current in the feedback loop is driven to balance the flux that is applied to said first fluxgate return strip and said second fluxgate return strip. 12. The torque sensing apparatus as in claim 1, further comprising a detection circuit for measuring the second harmonic current waveform on said excitation coil, said detection circuit comprises:a voltage source for applying a voltage to said excitation coil and at a first frequency; a frequency doubler for doubling said first frequency to a second frequency; a lock-in amplifier for receiving signals related to the second harmonic current waveform on said excitation coil and a reference signal from said frequency doubler, said lock-in amplifier producing an output signal relating to the second harmonic current in the excitation coil and said lock-in amplifier provides a signal corresponding to the second harmonic current in said excitation coil, said signal being inputted into said feedback coil in the form of an applied current; wherein the applied current in the feedback coil is driven to balance the flux that is applied to said first fluxgate return strip and said second fluxgate return strip. 13. The torque sensing apparatus as in claim 12, wherein said excitation coil comprises a first coil and a second coil, said first coil being wound about said first fluxgate return strip and said second coil being wound about said second fluxgate return strip and said first and said second coil are connected in series to provide a measurement flux and said first integrating ring, said second integrating ring, said first fluxgate return strip and said second fluxgate return strip provide a low reluctance closed loop flux path.14. A method for determining the applied torque to a shaft, comprising:integrating a first end of a magnetostrictive material disposed on the shaft with a first integrating ring; integrating a second end of said magnetostrictive material disposed on the shaft with a second integrating ring; providing a measurement flux in a first flux gate winding and a second flux gate winding, each being disposed about said magnetostrictive material; providing a low reluctance closed loop flux path from said first flux gate winding to said second flux gate winding by connecting a first flux gate return strip to said first integrating ring at one end and said second integrating ring at the other end and by connecting a second flux gate return strip to said first integrating ring at one end and said second integrating ring at the other end; and measuring an applied torque to the shaft by using a null detection scheme on said a low reluctance closed loop flux path. 15. A torque sensing apparatus for picking up a magnetic field of a magnetostrictive material disposed on a shaft, comprising:a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to said first integrating ring at one end and said second integrating ring at the other end; a means for providing a magnetic flux wherein said first fluxgate return strip and said second fluxgate return strip are maintained just below a point of magnetic saturation; and a means for determining an applied torque to the shaft. 16. The torque sensing apparatus as in claim 15, wherein the applied torque causes said first fluxgate return strip and said second fluxgate return strip to become magnetically saturated.17. The torque sensing apparatus as in claim 16, further comprising means for maintaining said first fluxgate return strip and said second fluxgate just below a point of magnetic saturation after a torque has been applied and sensed by said means for determining the applied torque to the shaft.18. The torque sensing apparatus as in claim 15, further comprising means for maintaining said first fluxgate return strip and said second fluxgate just below a point of magnetic saturation after a torque has been applied and sensed by said means for determining the applied torque to the shaft.19. The torque sensing apparatus as in claim 7, wherein said first fluxgate return strip and said second fluxgate return strip are maintained just below a point of magnetic saturation when there is no torque applied to the shaft.20. The torque sensing apparatus as in claim 3, wherein an applied torque to the shaft causes said first fluxgate return strip and said second fluxgate to become magnetically saturated.21. The torque sensing apparatus as in claim 19, wherein an applied torque to the shaft causes either said first fluxgate return strip or said second fluxgate to become magnetically saturated early in one direction and then in the other direction an excitation frequency of the excitation coil is sweeping the fluxgate in both directions.22. A torque sensing apparatus adapted for use with a magnetostrictive material disposed on a shaft, comprising:a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to said first integrating ring at one end and said second integrating ring at the other end to create a closed loop reluctance path; an excitation coil; a feedback coil; wherein said first fluxgate return strip and said second fluxgate return strip of the closed loop reluctance path are maintained just below a magnetic saturation point when only an excitation current flows through said excitation coil and the fluxgate return strips are magnetically saturated in one direction then in the other direction when an applied torque is encountered by the shaft, the magnetic saturation causes a DC offset in an excitation waveform of the excitation coil and the DC offset is used to provide a proportional current to the feedback coil to nullify the magnetic saturation of the fluxgates; wherein the excitation coil is used to provide an excitation flux and receive the torque flux through the first integrating ring, the second integrating ring, the first fluxgate return strip and the second fluxgate return strip. 23. The torque sensing apparatus as in claim 22, further comprising a torque detection circuit comprising: an oscillator; a differential amplifier; a second order filter, a voltage controlled current source, and an output amplifier.24. A torque sensing apparatus adapted for use with a magnetostrictive material disposed on a shaft, comprising:a first integrating ring; a second integrating ring; a first fluxgate return strip and a second fluxgate return strip each being connected to said first integrating ring at one end and said second integrating ring at the other end to create a closed loop reluctance path; a coil; wherein said first fluxgate return strip and said second fluxgate return strip of the closed loop reluctance path are maintained just below a magnetic saturation point when only an excitation current flows through said coil and the fluxgate return strips are magnetically saturated in one direction then in the other direction when an applied torque is encountered by the shaft, the magnetic saturation causes a DC offset in an excitation waveform of the coil and the DC offset is used to provide a proportional current to the coil to nullify the magnetic saturation of the fluxgates; wherein the coil is used to provide an excitation flux and receive the torque flux through the first integrating ring, the second integrating ring, the first fluxgate return strip and the second fluxgate return strip. 25. The torque sensing apparatus as in claim 24, further comprising a torque detection circuit comprising: an oscillator; a differential amplifier; a second order filter, a voltage controlled current source, and an output amplifier.
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