US3633084A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brushless dc motor having automatic braking
Assignee: Unisys Corp
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Filing: 1970-06-24
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Granted: 1972-01-04
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Expires: 1990-06-24
Abstract
Abstract A single-sensor, two-winding brushless DC motor includes a main power supply from which the stator windings are energized and an auxiliary power supply through which a commutating circuit is energized. A position-sensing circuit provides a command signal only while the rotor is within a given 180* sector. The commutating means completes a circuit through a first stator winding in response to a command signal; a circuit through a second stator winding in the absence of a command signal. Dynamic braking is achieved by turning off the main power supply while keeping the auxiliary power supply on. Under these conditions, the commutating means completes a circuit through the second stator winding so that the kinetic energy of the rotor may be dissipated and the motor stopped smoothly and rapidly.
Inventors
- 👤 Rodney G Rakes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:33
CPC Classifications
H; H02; H02P; H02P3/00; H02P3/06; H02P3/18; H02P3/24; H02K; H02K29/00; H02K29/06; H02K29/10
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
208 words
A single-sensor brushless DC motor comprising a cylindrical housing, first and second stator windings arranged to establish magnetic fields in opposite directions along a diameter of the housing, a permanently magnetized rotor rotatable within said housing, a main power supply for energizing said stator windings, sensing means energized by said main power supply for providing a command signal when and only when the rotor is aligned with a given semicircular sector, commutating means including first transistor switching means for connecting said first stator winding in a closed circuit across said main power supply in response to a command signal and second transistor switching means for connecting said second stator winding in a closed circuit across said main power supply in the absence of a command signal, individual diodes connected across each of said transistor switching means and oriented to pass current in a direction opposite to that permitted by the associated switching means, an auxiliary power supply for energizing said commutating means, and means for interrupting the flow of power from said main power supply without disturbing the flow of power from said auxiliary power supply, so that current flow may be induced in said stator windings by the motion of said rotor after the motor is deenergized.
Claim 2
Dependent Claim
208 words
A single-sensor brushless DC motor comprising a cylindrical housing, first and second stator windings arranged to establish magnetic fields in opposite directions along a diameter of the housing, a permanently magnetized rotor rotatable within said housing, a main power supply for energizing said stator windings, sensing means energized by said main power supply for providing a command signal when and only when the rotor is aligned with a given semicircular sector, commutating means including first transistor switching means for connecting said first stator winding in a closed circuit across said main power supply in response to a command signal and second transistor switching means for connecting said second stator winding in a closed circuit across said main power supply in the absence of a command signal, individual diodes connected across each of said transistor switching means and oriented to pass current in a direction opposite to that permitted by the associated switching means, an auxiliary power supply for energizing said commutating means, and means for interrupting the flow of power from said main power supply without disturbing the flow of power from said auxiliary power supply, so that current flow may be induced in said stator windings by the motion of said rotor after the motor is deenergized.
Claim 3
Dependent Claim
29 words
The motor of claim 1 wherein said sensing means includes a photosensor and means to illuminate said photosensor only when the rotor is aligned within said given semiconductor sector.
Claim 4
Dependent Claim
21 words
The motor of claim 2 wherein said sensing means produces a command signal only when the photosensor is energized and illuminated.
Claim 5
Dependent Claim
45 words
The motor of claim 3 wherein said commutating means further includes bistable means for closing one of said switches when the bistable means is in a first stable state and the other of said switches when the bistable means is in a second bistable state.
Claim 6
Dependent Claim
96 words
The motor of claim 4 wherein said bistable means includes first and second inverting means and each of said switching means includes a transistor, said first inverting means being coupled to receive a command signal from said sensing means, said second inverting means being coupled to receive an output signal from said first inverting means, one of said transistors being connected to be driven into conduction by a high-level signal from said first inverting means, the other of said transistors being connected to be driven into conduction by a high-level signal from said second inverting means.
Claim 7
Dependent Claim
44 words
The motor of claim 5 wherein said first stator winding is connected in series with one of said transistors across said main power supply and said second stator winding is connected in series with the other of said transistors across said main power supply.
Claim 8
Dependent Claim
39 words
The motor of claim 6 wHerein both of said stator windings and one side of said photosensor are all connected to the same side of said main power supply, said photosensor being further coupled to said first inverting means.
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) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |