US4039946A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tachometer
Assignee: National Aeronautics and Space Administration
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Filing: 1976-03-18
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Granted: 1977-08-02
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Expires: 1996-03-18
Abstract
Abstract A tachometer in which sine and cosine signals responsive to the angular position of a shaft as it rotates are each multiplied by like, sine or cosine, functions of a carrier signal, the products summed, and the resulting frequency signal converted to fixed height, fixed width pulses of a like frequency. These pulses are then integrated, and the resulting DC output is an indication of shaft speed.
Inventors
- 👤 Frank J. Nola
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:53
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
240 words
a tachometer for measuring shaft speed comprising: transducer means responsive to the angular position of a shaft as rotated through an angle from a reference position for providing a signal representative of the sine of the angle, SIN w s t, and a signal representative of the cosine of this angle, COS w s t; signal generating means for providing a signal proportional to the sine of the angle of a carrier frequency, SINw c t, and a signal proportional to the cosine of the angle of said carrier frequency, COS w c t; first multiplication means responsive to said transducer means and said signal generating means for providing as a product SIN w s t SIN w c t, and second multiplication means responsive to said transducer means and said signal generating means for providing a product COS w s t COS w c t; summing means responsive to the outputs of said first and second multiplication means for providing as an output a signal proportional to COS(w c -w s )t and, alternately, COS(w c +w s )t; pulse means responsive to the output of said summing means for providing as an output fixed-height, fixed width pulses of the frequency of the output of said summing means; integration means responsive to the output of said pulse means for providing a DC output proportional to shaft speed; and indication means responsive to said integration means for indicating shaft speed.
Claim 2
Dependent Claim
240 words
a tachometer for measuring shaft speed comprising: transducer means responsive to the angular position of a shaft as rotated through an angle from a reference position for providing a signal representative of the sine of the angle, SIN w s t, and a signal representative of the cosine of this angle, COS w s t; signal generating means for providing a signal proportional to the sine of the angle of a carrier frequency, SINw c t, and a signal proportional to the cosine of the angle of said carrier frequency, COS w c t; first multiplication means responsive to said transducer means and said signal generating means for providing as a product SIN w s t SIN w c t, and second multiplication means responsive to said transducer means and said signal generating means for providing a product COS w s t COS w c t; summing means responsive to the outputs of said first and second multiplication means for providing as an output a signal proportional to COS(w c -w s )t and, alternately, COS(w c +w s )t; pulse means responsive to the output of said summing means for providing as an output fixed-height, fixed width pulses of the frequency of the output of said summing means; integration means responsive to the output of said pulse means for providing a DC output proportional to shaft speed; and indication means responsive to said integration means for indicating shaft speed.
Claim 3
Dependent Claim
87 words
A tachometer as set forth in claim 1 wherein said indication means comprises: a source of bias equal to the output of said integration means for a condition of zero speed of a shaft; and difference means responsive to the output of said integration means and said source of bigs for providing as an output a zero output when shaft speed is zero and a signal of a sign indicative of the direction of shaft rotation and of a magnitude representative of the speed of the shaft.
Claim 4
Dependent Claim
131 words
A tachometer as set forth in claim 2 and including: a permanent magnet coupled to a shaft to be monitored in speed; first and second Hall effect devices, each having an electrical input and electrical output, and said Hall effect devices being positioned about the periphery of said magnet at an angular spacing of 90 degrees; a SIN w c t output of said signal generating means connected to said input of said first Hall effect device, and a COS w c t output of said signal generating means connected to said input of said second Hall effect defice; and said outputs of Hall effect devices being connected additively in series to provide said COS(w c -w s )t and, alternatively, said COS(w c +w s )t to said pusle means.
Claim 5
Dependent Claim
37 words
A tachometer as set forth in claim 3 wherein said pulse means comprises a zero crossing detector, a differentiator, and a one-shot multivibrator, connected serially in this order between said Hall effect devices and said integration means.
Claim 6
Dependent Claim
25 words
A tachometer as set forth in claim 2 wherein said carrier frequency is at least five times the highest frequency output of said tranducer means.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-01 | 1981-01-31 | 1981-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-01 | 1985-01-31 | 1985-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-01 | 1989-01-31 | 1989-08-02 | $7700.00 | Window Closed / Lapsed |