Patent US3831071A successfully refreshed from Google Patents.
US3831071A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brushless direct current motor & control therefor
Assignee: Suwa Seikosha KK
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Filing: 1972-08-14
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Granted: 1974-08-20
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Expires: 1992-08-14
Abstract
Abstract A brushless direct current motor is formed with a rotor having a magnetic construction in which the direction of magnetic flux is parallel to the rotary axis of the motor. At least one magnetic sensitive element is disposed in the magnetic flux of the rotor for detecting the state of said flux. A base plate is provided on which driving coils are disposed, the current controlled by a signal from said magnetic sensitive element is supplied to said driving coils to drive said rotor.
Inventors
- 👤 Y Mitsui
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:47
CPC Classifications
H; H02; H02K; H02K29/00; H02K29/06; H02K29/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
205 words
A brushless direct current motor which controls driving current by detecting the state of magnetic flux comprising a rotor having a pair of spaced yokes, each of said yokes having a plurality of permanent magnets mounted thereon arranged circumferentially about the rotary axis of said rotor, the permanent magnets on each yoke being polarized in a direction parallel to said rotary axis and so that each adjacent pair of permanent magnets on each yoke are of opposite polarity, said yokes being arranged in spaced relation along said rotary axis with their respective permanent magnets in spaced facing relation to define a gap through which magnetic flux flows in a direction parallel to the rotary axis of said motor; at least one magnetic sensitive element positioned in said gap in the path of said magnetic flux for detecting the state of said magnetic flux; a base plate; a plurality of driving coils mounted on said base plate in said gap in said magnetic circuit means; and driving circuit means coupling said magnetic sensitive element and said driving coils for applying driving current to saiD driving coils in response to the signal produced by said magnetic sensitive element in response to the state of said magnetic flux.
Claim 2
Dependent Claim
205 words
A brushless direct current motor which controls driving current by detecting the state of magnetic flux comprising a rotor having a pair of spaced yokes, each of said yokes having a plurality of permanent magnets mounted thereon arranged circumferentially about the rotary axis of said rotor, the permanent magnets on each yoke being polarized in a direction parallel to said rotary axis and so that each adjacent pair of permanent magnets on each yoke are of opposite polarity, said yokes being arranged in spaced relation along said rotary axis with their respective permanent magnets in spaced facing relation to define a gap through which magnetic flux flows in a direction parallel to the rotary axis of said motor; at least one magnetic sensitive element positioned in said gap in the path of said magnetic flux for detecting the state of said magnetic flux; a base plate; a plurality of driving coils mounted on said base plate in said gap in said magnetic circuit means; and driving circuit means coupling said magnetic sensitive element and said driving coils for applying driving current to saiD driving coils in response to the signal produced by said magnetic sensitive element in response to the state of said magnetic flux.
Claim 3
Dependent Claim
34 words
A brushless direct current motor as recited in claim 1, wherein each of said permanent magnets on each of said yokes are essentially pie-shaped, the adjacent edges thereof being substantially contiguous or closely spaced.
Claim 4
Dependent Claim
32 words
A brushless direct current motor as recited in claim 1, wherein said magnetic sensitive element is a hall element positioned in the path of magnetic flux of all of said permanent magnets.
Claim 5
Dependent Claim
38 words
A brushless direct current motor as recited in claim 3, wherein said coil means are essentially flat coils aligned in a plane passing through said gap and occupying a predetermined sector positioned circumferentially relatively to said rotary axis.
Claim 6
Dependent Claim
32 words
A brushless direct current motor as recited in claim 4, wherein each of said driving coils occupies a pi /3 section, each of said yokes carrying at least six pie-shaped permanent magnets.
Claim 7
Dependent Claim
66 words
A brushless direct current motor as recited in claim 5, including four of said driving coils spaced concentrically about said rotary axis, and including at least two of said hall elements, said driving circuit means coupling said hall elements and driving coils so that each of said driving coils is actuated by driving current at least three times during each period of rotation of said rotor.
Claim 8
Dependent Claim
27 words
A brushless direct current motor as recited in claim 6, wherein said hall elements are each angularly spaced from the driving coils driven thereby by pi /2.
Claim 9
Dependent Claim
24 words
A brushless direct current motor as recited in claim 5, including at least three of said driving coils and at least two hall elements.
Claim 10
Dependent Claim
26 words
A brushless direct current motor as recited in claim 5, including at least one of said hall elements and at least two of said driving coils.
Claim 11
Dependent Claim
96 words
A brushless direct current motor as recited in claim 1, wherein alternating permanent magnets on each of said yokes are dimensioned to project in a radial direction beyond the other of said permanent magnets, the permanent magnets of increased radial dimension on each of said yokes being in facing relation to the permanent magnets of increased radial dimension on the other of said yokes, said magnetic sensitive elements being magnetic resistant elements positioned in the locus of said permanent magnets of increased radial dimension but not in the locus of the other of said permanent magnets.
Claim 12
Dependent Claim
48 words
A brushless direct current motor as recited in claim 1, wherein said magnetic sensitive elements, driving coils and magnetic driving circuit are oriented so that a driving current pulse is applied to each of said driving coils more than twice during each period of rotation of 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) | 1977-08-19 | 1978-02-18 | 1978-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-19 | 1982-02-18 | 1982-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-19 | 1986-02-18 | 1986-08-20 | $7700.00 | Window Closed / Lapsed |