Patent US4617499A successfully refreshed from Google Patents.
US4617499A
Expired / Lapsed
US
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Brushless motor
Assignee: Sony Corp
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Filing: 1985-11-21
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Granted: 1986-10-14
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Expires: 2005-11-21
Abstract
Abstract A brushless motor comprises a magnet having a plurality of pole faces, a plurality of conductors mounted adjacent to the pole faces, and a plurality of phase coils connected together at a neutral point. The magnet is included in the motor rotor and the phase coils are included in the motor stator. A high-frequency signal source supplies a high-frequency signal to the neutral point, whereby changes in eddy current loss and thus the position of the rotor with respect to the stator are detected.
Inventors
- 👤 Masami Yuasa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:35
CPC Classifications
H; H02; H02K; H02K1/00; H02K1/06; H02K1/22; H02P; H02P6/00; H02P6/14; H02P6/16; H02P6/18; H02P6/185; H02K29/00; H02K29/06; H02K29/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
96 words
A brushless motor comprising: a magnet having a plurality of pole faces; a plurality of conductors mounted adjacent to said pole faces; a plurality of phase coils connected together at a neutral point, one of said magnet and said phase coils being included in a movable motor element and the other being included in a stationary motor element; and a high-frequency signal source for supplying a high-frequency signal to said neutral point, whereby changes in eddy current loss and thus the position of said movable motor element with respect to said stationary motor element are detected.
Claim 2
Dependent Claim
96 words
A brushless motor comprising: a magnet having a plurality of pole faces; a plurality of conductors mounted adjacent to said pole faces; a plurality of phase coils connected together at a neutral point, one of said magnet and said phase coils being included in a movable motor element and the other being included in a stationary motor element; and a high-frequency signal source for supplying a high-frequency signal to said neutral point, whereby changes in eddy current loss and thus the position of said movable motor element with respect to said stationary motor element are detected.
Claim 3
Dependent Claim
23 words
A brushless motor according to claim 1; wherein said movable motor element is a rotor and said stationary motor element is a stator.
Claim 4
Dependent Claim
86 words
A brushless motor according to claim 1; further comprising: means for detecting currents respectively flowing through said phase coils; filtering means for extracting high-frequency components from the detected currents; amplitude means for generating amplitude signals representative of the amplitudes of the high-frequency components from said filtering means; rectangular wave signal means for converting said amplitude signals to rectangular wave signals; and switch means for forming switching signals in accordance with said rectangular wave signals, said switching signals controlling the drive currents to said respective phase coils.
Claim 5
Dependent Claim
79 words
A brushless motor according to claim 3; wherein said amplitude means comprises maximum value holding means for generating signals respectively representative of the maximum amplitudes of said high-frequency components and minimum value holding means for generating signals respectively representative of the minimum amplitudes of said high-frequency components, said signals representative of maximum amplitudes and said signals representative of minimum amplitudes respectively being subtracted and compared to produce compared output signals supplied as inputs to said rectangular wave signal means.
Claim 6
Dependent Claim
53 words
A brushless motor according to claim 4; wherein said rectangular wave signal means comprises latch means for generating a pulse D u , a pulse D v and a pulse D w , said pulses D u , D v , D w having phase relationships of 120° with respect to one another.
Claim 7
Dependent Claim
133 words
A brushless motor according to claim 5; wherein said switching signals comprise a signal U H that is high when D u is low and D v is high and low otherwise; a signal V H that is high when D v is low and D w is high and low otherwise; a signal W H that is high when D w is low and D u is high and low otherwise; a signal U L that is high when D u is high and D v is low and low otherwise; a signal V L that is high when D v is high and D w is low and low otherwise; and a signal W L that is high when D w is high and D u is low and low otherwise.
Claim 8
Dependent Claim
49 words
A brushless motor according to claim 6; further comprising six NPN transistors respectively having bases responsive to said signals U H , U L , V H , V L , W H , W L and connected in pairs for supplying drive current to said respective phase coils.
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) | 1989-10-13 | 1990-04-14 | 1990-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-13 | 1994-04-14 | 1994-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-13 | 1998-04-14 | 1998-10-14 | $7700.00 | Window Closed / Lapsed |