US3930186A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protective device for brushless DC motor
Assignee: Sony Corp
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Filing: 1974-06-26
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Granted: 1975-12-30
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Expires: 1994-06-26
Abstract
Abstract A protective device for a brushless DC motor is disclosed in which a high frequency signal is applied through a transformer to a coil for detecting the rotary position of the rotor of the motor. In this case, the magnetic core of the transformer is made of thermo-sensitive or temperature-sensitive ferrite and the rotation of the motor is stopped when an abnormal heat is generated by detecting the abnormal heat with the magnetic core.
Inventors
- 👤 Tetsuo Sekiya
- 👤 Atsushi Hienuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:09
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/085; H02H7/0852; H01; H01F; H01F27/00; H01F27/24; H01F27/255; H02H7/0833; H02K; H02K11/00; H02K11/20; H02K11/25; H02K29/00; H02K29/06; H02K29/12
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
159 words
A brushless electrical motor including, a permanent magnet rotor, a stator rotatably supporting said rotor and a plurality of angularly spaced field windings mounted in said stator, position sensing means mounted on said rotor, a plurality of detecting coils mounted to sense the angular position of said sensing means, a plurality of electronic switches respectively connected in series with said plurality of field windings and having control electrodes respectively connected to said plurality of detecting coils, first voltage supply terminals connected across said plurality of field windings and electronic switches, an oscillator, a transformer having a temperature sensitive magnetic core with its primary winding connected to the output of said oscillator and its secondary connected across each of said detecting coils such that power is sequentially applied to said field windings as said rotor rotates at temperatures below a predetermined temperature but power is disconnected from said field windings by said electronic switches and transformer above said predetermined temperature.
Claim 2
Dependent Claim
159 words
A brushless electrical motor including, a permanent magnet rotor, a stator rotatably supporting said rotor and a plurality of angularly spaced field windings mounted in said stator, position sensing means mounted on said rotor, a plurality of detecting coils mounted to sense the angular position of said sensing means, a plurality of electronic switches respectively connected in series with said plurality of field windings and having control electrodes respectively connected to said plurality of detecting coils, first voltage supply terminals connected across said plurality of field windings and electronic switches, an oscillator, a transformer having a temperature sensitive magnetic core with its primary winding connected to the output of said oscillator and its secondary connected across each of said detecting coils such that power is sequentially applied to said field windings as said rotor rotates at temperatures below a predetermined temperature but power is disconnected from said field windings by said electronic switches and transformer above said predetermined temperature.
Claim 3
Dependent Claim
14 words
A brushless electrical motor according to claim 1 wherein said electronic switches comprise transistors.
Claim 4
Dependent Claim
28 words
A brushless electrical motor according to claim 2 including a plurality of diodes respectively connected between said plurality of detecting coils and said control electrodes of said transistors.
Claim 5
Dependent Claim
30 words
A brushless electrical motor according to claim 2 wherein said magnetic core of said transformer is made of material which has an abrupt change in permeability at said predetermined temperature.
Claim 6
Dependent Claim
16 words
A brushless electrical motor according to claim 4 wherein said magnetic core is made of fervite.
Claim 7
Dependent Claim
16 words
A brushless electrical motor according to claim 4 wherein said predetermined temperature is about 70* centigrade.
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) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |