Patent US4405885A successfully refreshed from Google Patents.
US4405885A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brushless dc motor
Assignee: Panasonic Holdings Corp
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Filing: 1981-07-20
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Granted: 1983-09-20
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Expires: 2001-07-20
Abstract
Abstract A three-phase brushless dc motor using two position detecting elements to obtain the signal necessary for sequentially energizing the motor and capable of obtaining one reference pulse signal for every rotation of the motor, the reference pulse signal being used for phase detection of the motor. More particularly, the present invention allows the two position detecting elements to be disposed radially in the same direction and on the same plate so as to reduce mounting errors between the two position detecting elements, thereby improving the performance of the resulting brushless dc motor and reducing its manufacturing costs.
Inventors
- 👤 Hiroshi Okamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:29
CPC Classifications
H; H02; H02K; H02K29/00; H02K29/06; H02K29/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
327 words
A brushless dc motor comprising a rotor including a permanent magnet of 2n-poles (n: an integer), a stator including three-phase stator windings, a position signal generator for generating a position signal corresponding to a rotating position of said rotor, and a current divider for controlling a period of time for energizing said three-phase stator windings according to said position signal, wherein said position signal generator comprises a position detecting rotary member, a first position detecting element, a second position detecting element, and a position detecting means, said position detecting rotary member being provided with a first position detecting track which is ring-like in shape and which has two states, A and B, which are different in physical properties and which are coded sequentially at an angular ratio of approximately 1 to 2 corresponding to the number of the polarities of said permanent magnet and being provided with a second position detecting track which is ring-like in shape and which has two states which are different in physical properties and which are coded sequentially at a different angular position from said first position detecting track, and rotating integrally with said rotor, said first position detecting element detecting said coded physical state of said first position detecting track corresponding to a rotating position of said position detecting rotary member, said second position detecting element detecting said coded physical state of said second position detecting track, said position detecting means providing a coding ratio of said two coded physical states of said second position detecting track and mounting said second position detecting element, so that within a zone where said first position detecting element detects the physical state A, said physical state detected by said second position detecting element changes an odd number of times and at a substantially central angle of an angular width in which said first position detecting element detects said physical state B, and said physical state detected by said first position detecting element changes once.
Claim 2
Dependent Claim
327 words
A brushless dc motor comprising a rotor including a permanent magnet of 2n-poles (n: an integer), a stator including three-phase stator windings, a position signal generator for generating a position signal corresponding to a rotating position of said rotor, and a current divider for controlling a period of time for energizing said three-phase stator windings according to said position signal, wherein said position signal generator comprises a position detecting rotary member, a first position detecting element, a second position detecting element, and a position detecting means, said position detecting rotary member being provided with a first position detecting track which is ring-like in shape and which has two states, A and B, which are different in physical properties and which are coded sequentially at an angular ratio of approximately 1 to 2 corresponding to the number of the polarities of said permanent magnet and being provided with a second position detecting track which is ring-like in shape and which has two states which are different in physical properties and which are coded sequentially at a different angular position from said first position detecting track, and rotating integrally with said rotor, said first position detecting element detecting said coded physical state of said first position detecting track corresponding to a rotating position of said position detecting rotary member, said second position detecting element detecting said coded physical state of said second position detecting track, said position detecting means providing a coding ratio of said two coded physical states of said second position detecting track and mounting said second position detecting element, so that within a zone where said first position detecting element detects the physical state A, said physical state detected by said second position detecting element changes an odd number of times and at a substantially central angle of an angular width in which said first position detecting element detects said physical state B, and said physical state detected by said first position detecting element changes once.
Claim 3
Dependent Claim
146 words
A brushless dc motor according to claim 1, wherein said position signal generator comprises a position detecting means which is arranged so that the physical state detected by said second position detecting element changes three times in one zone of n zones where said first position detecting element detects said physical state A during every rotation of said rotor and the physical state detected by said second position detecting element change once in the other n-1 zones; and a PG signal generating means which is fed outputs from said first position detecting element and said second position detecting element, and which outputs a PG pulse signal representing a period of time from the second change to the third change of said physical state detected by said second position detecting element within the period of time when said first position detecting element detects the physical state A.
Claim 4
Dependent Claim
137 words
A brushless dc motor according to claims 1 or 2, wherein said first and second position detecting tracks are positioned on the same plane or cylindrical surface and include permanent magnets coded by N and S poles, said first and second position detecting elements comprising magnetic sensitive elements utilizing the Hall effect, said current divider comprising a first differential circuit for differentially-outputting an output current from a current supply according to an output of said first position detecting element and a second differential circuit for differentially-outputting one output current from said first differential circuit according to an output of said second position detecting element, wherein said three-phase stator windings each are energized according to the output current of said first differential circuit and the differential output current of said second differential circuit, thereby generating a rotating force.
Claim 5
Dependent Claim
31 words
A brushless dc motor according to claim 3, wherein said first and second position detecting elements are provided on the same carrier plate and disposed radially thereof in the same direction.
Claim 6
Dependent Claim
23 words
A brushless dc motor according to claim 4, wherein said position detecting rotary member is integral with said permanent magnet constituting said rotor.
Claim 7
Dependent Claim
23 words
A brushless dc motor according to claim 3, wherein said position detecting rotary member is integral with said permanent magnet constituting said rotor.
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) | 1986-09-19 | 1987-03-21 | 1987-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-19 | 1991-03-21 | 1991-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-19 | 1995-03-21 | 1995-09-20 | $7700.00 | Window Closed / Lapsed |