Patent US3719875A successfully refreshed from Google Patents.
US3719875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brushless d.c. motor using magneto resistor sensing means
Assignee: Litton Marine Systems Inc
•
Filing: 1972-01-26
•
Granted: 1973-03-06
•
Expires: 1992-01-26
Abstract
Abstract A brushless d.c. motor having a diametrically magnetized permanent magnet rotor and a plurality of stator windings disposed around the inner periphery of the motor frame, employs magneto resistors placed intermediate adjacent windings to trigger commutating switches that control energization of the individual stator windings. All stator windings are wound to attract the same selected magnetic pole of the rotor. The rise in resistance of a magneto resistor when subjected to flux from the selected magnetic pole is used to close the switch controlling the following stator winding in the desired sequence. The switch also produces a disabling signal that triggers a silicon controlled rectifier in the preceding switch so as to open this switch. The magneto resistor controlling the disabled switch is disposed diametrically opposite the energized stator winding so that when the flux from the non-selected rotor pole intercepts this resistor, the associated switch remains clamped in the open condition.
Inventors
- 👤 E Holland
- 👤 R Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:18
CPC Classifications
H; H02; H02K; H02K29/00; H02K29/06; H02K29/08
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
206 words
A brushless d.c. motor of the type in which a permanent magnet rotor rotates in response to a rotating magnetic field established by individual stator windings disposed around the inner periphery of the motor frame and wound so as to attract a selected magnetic pole of said rotor, said motor comprising individual switching means for energizing a corresponding stator winding in response to a trigger signal, individual magneto resistors coupled to apply trigger signals to a corresponding switching means, each of said magneto resistors being disposed around the inner periphery of said motor frame in a position ahead of the associated stator winding so that a magneto resistor provides a trigger signal when the selected magnetic pole of the rotor approaches the associated stator winding, means in each of said switching means for producing a disable signal when the switching means is closed, means in each of said switching means for clamping the switch in the open condition in response to a disable signal from an adjacent switching means, said magneto resistors being further disposed so that the resistor is exposed to a maximum intensity of flux from the non-selected magnetic pole of the rotor while the associated switching means is clamped in the open condition.
Claim 2
Dependent Claim
206 words
A brushless d.c. motor of the type in which a permanent magnet rotor rotates in response to a rotating magnetic field established by individual stator windings disposed around the inner periphery of the motor frame and wound so as to attract a selected magnetic pole of said rotor, said motor comprising individual switching means for energizing a corresponding stator winding in response to a trigger signal, individual magneto resistors coupled to apply trigger signals to a corresponding switching means, each of said magneto resistors being disposed around the inner periphery of said motor frame in a position ahead of the associated stator winding so that a magneto resistor provides a trigger signal when the selected magnetic pole of the rotor approaches the associated stator winding, means in each of said switching means for producing a disable signal when the switching means is closed, means in each of said switching means for clamping the switch in the open condition in response to a disable signal from an adjacent switching means, said magneto resistors being further disposed so that the resistor is exposed to a maximum intensity of flux from the non-selected magnetic pole of the rotor while the associated switching means is clamped in the open condition.
Claim 3
Dependent Claim
206 words
A brushless d.c. motor of the type in which a permanent magnet rotor rotates in response to a rotating magnetic field established by individual stator windings disposed around the inner periphery of the motor frame and wound so as to attract a selected magnetic pole of said rotor, said motor comprising individual switching means for energizing a corresponding stator winding in response to a trigger signal, individual magneto resistors coupled to apply trigger signals to a corresponding switching means, each of said magneto resistors being disposed around the inner periphery of said motor frame in a position ahead of the associated stator winding so that a magneto resistor provides a trigger signal when the selected magnetic pole of the rotor approaches the associated stator winding, means in each of said switching means for producing a disable signal when the switching means is closed, means in each of said switching means for clamping the switch in the open condition in response to a disable signal from an adjacent switching means, said magneto resistors being further disposed so that the resistor is exposed to a maximum intensity of flux from the non-selected magnetic pole of the rotor while the associated switching means is clamped in the open condition.
Claim 4
Dependent Claim
206 words
A brushless d.c. motor of the type in which a permanent magnet rotor rotates in response to a rotating magnetic field established by individual stator windings disposed around the inner periphery of the motor frame and wound so as to attract a selected magnetic pole of said rotor, said motor comprising individual switching means for energizing a corresponding stator winding in response to a trigger signal, individual magneto resistors coupled to apply trigger signals to a corresponding switching means, each of said magneto resistors being disposed around the inner periphery of said motor frame in a position ahead of the associated stator winding so that a magneto resistor provides a trigger signal when the selected magnetic pole of the rotor approaches the associated stator winding, means in each of said switching means for producing a disable signal when the switching means is closed, means in each of said switching means for clamping the switch in the open condition in response to a disable signal from an adjacent switching means, said magneto resistors being further disposed so that the resistor is exposed to a maximum intensity of flux from the non-selected magnetic pole of the rotor while the associated switching means is clamped in the open condition.
Claim 5
Dependent Claim
87 words
The brushless d.c. rotor of claim 1 in which three stator windings are disposed at equal intervals around the motor frame and a magneto resistor is positioned midway between each pair of adjacent stator windings, each magneto resistor being coupled to provide trigger signals to the associated switching means controlling the next adjacent stator winding in the direction of rotor rotation, said associated switching means further being coupled to receive disable signals from the switching means controlling the stator winding positioned diametrically opposite the same magneto resistor.
Claim 6
Dependent Claim
113 words
The brushless d.c. motor of claim 2 wherein each switching means includes amplifying means for supplying energizing current to the associated stator winding, voltage dividing means for driving said amplifying means and a disabling circuit, said voltage dividing means including a calibrating resistor and means for connecting the associated magneto resistor in series with said calibrating resistor so that the trigger signals from the associated magneto resistor appear at the junction of the calibrating resistor and the magneto resistor, said calibrating resistor being adjusted so that the amplifying means is driven into conduction when the selected magnetic pole of the rotor reaches a specified angular displacement with respect to the associated magneto resistor.
Claim 7
Dependent Claim
15 words
The brushless d.c. motor of claim 3 wherein the specified angular displacement in about 60*.
Claim 8
Dependent Claim
38 words
The brushless d.c. motor of claim 4 in which the disabling circuit includes a controlled rectifier circuit connected across said voltage dividing means so as to short out the associated magneto resistor when the controlled rectifier is conducting.
Claim 9
Dependent Claim
60 words
The brushless d.c. motor of claim 5 in which the controlled rectifier circuit includes a series resistor, a transistor, and a controlled rectifier in series relationship, said controlled rectifier being effectively shunted across the magneto resistor through said transistor, said controlled rectifier being connected to respond to disable signals from the succeeding switching means in the direction of rotor rotation.
Claim 10
Dependent Claim
117 words
The brushless d.c. motor of claim 6 wherein said transistor has a base electrode connected to the junction of said calibrating resistor and the associated magneto resistor, a collector electrode connected through said series resistor to the opposite end of said calibrating resistor, and an emitter electrode connected to the anode of said controlled rectifier, said controlled rectifier further having a cathode connected to the opposite end of said magneto resistor whereby the conduction characteristics of said controlled rectifier are dependent upon said calibrating resistor and the voltage at said junction, said calibrating resistor being selected so that the controlled rectifier is maintained in its conducting state until the voltage at said junction nears its maximum value.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-05 | 1976-09-04 | 1977-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-05 | 1980-09-04 | 1981-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-05 | 1984-09-04 | 1985-03-06 | $7700.00 | Window Closed / Lapsed |