EP0140461A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Simple brushless dc fan motor with reversing field
Assignee: Comair Rotron Inc
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Filing: 1984-02-10
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Granted: —
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Expires: 2004-02-10
Abstract
Abstract A simplified fan and brushless DC motor (10) employs an annular permanent magnet (14) magnetized in segments about its circumference. Each segment is oppositely radially magnetized with respect to its adjacent segments. Fan blades (17) are located within the annular magnet (14). A coil comprising two electrically independent and bifilar wound windings (L1 and L2), connected to be oppositely energized, and an electromagnet structure defining two pole pieces (48 and 49) reside outside the permanent magnet annulus. A Hall effect device (H1), alternately energizes the separate coil windings (L1 and L2) in response to passage of the segments of the rotor magnet (14) to alternately produce opposite magnetic fields in the pole pieces (48 and 49). Thus commutated, the double coil arrangement affects rotation of the rotor (11) and the fan blades (17).
Inventors
- 👤 Fred A. Brown
- 👤 Alan F. Grouse
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 12:35
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/14; F; F04; F04D; F04D25/00; F04D25/02; F04D25/06; F04D25/0606; F04D25/066; H02K; H02K7/00; H02K7/14
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
106 words
A DC motor comprising: a rotor with an annular permanent magnet defining magnetic segments oppositely polarized in the radial outward direction, wherein said segments are arranged circumferentially about the magnet; a stator having an electromagnet structure outside said annular magnet, said structure including coil means for establishing magnetic fields of opposite polarities to attract the oppositely polarized segments of the annular magnet towards the coil; and position detecting means for detecting the position of the rotor relative to the stator and for commutating electrical current to the coil means to repeatedly produce said opposite polarity fields and attract said segments in dependence on said relative positioning.
Claim 2
Dependent Claim
106 words
A DC motor comprising: a rotor with an annular permanent magnet defining magnetic segments oppositely polarized in the radial outward direction, wherein said segments are arranged circumferentially about the magnet; a stator having an electromagnet structure outside said annular magnet, said structure including coil means for establishing magnetic fields of opposite polarities to attract the oppositely polarized segments of the annular magnet towards the coil; and position detecting means for detecting the position of the rotor relative to the stator and for commutating electrical current to the coil means to repeatedly produce said opposite polarity fields and attract said segments in dependence on said relative positioning.
Claim 3
Dependent Claim
23 words
The motor according to claim 1, wherein the electromagnet structure defines at least one pole piece adjacent the exterior of the annular magnet.
Claim 4
Dependent Claim
61 words
The motor according to claim 1, further including commutation circuit means connected to said position detecting means and to said coil means for reversing the field polarity at the approach of each oppositely polarized magnet segment to the position detecting means, whereby said coil means is energized to produce the alternating field throughout substantially all of the 360 of rotor movement.
Claim 5
Dependent Claim
43 words
The motor according to claim 1, wherein the electromagnet structure includes a flux path having a pair of arm in magnetic flux conducting relation with the coil means and extending to two pole pieces spaced apart along the circumference of the annular magnet.
Claim 6
Dependent Claim
35 words
The motor according to claim 4, wherein the pole pieces are spaced apart by such a distance as to each attract a separate magnetized segment of the annular magnet when the coil means is energized.
Claim 7
Dependent Claim
36 words
The motor according to claim 5, wherein adjacent segments of the annular magnet are oppositely polarized, and wherein the pole pieces are located to attract the adjacent, oppositely polarized segments when the coil means is energized.
Claim 8
Dependent Claim
55 words
The motor according to claim 1, wherein the coil means comprises two electrically independent coil windings which produce magnetic fields of opposite polarities when energized, the detecting means comprises means for commutating elelctrical current to a different coil winding to produce said opposite polarity fields and attract said segments in dependence on said relative positioning.
Claim 9
Dependent Claim
145 words
The motor according to claim 7, wherein the means for can- mutating current includes at least a first transistor means connected in current conducting relation to a first of said windings, and at least a second transistor means in current conducting relation to the second of said windings, resistance means for establishing biases to the first and second transistor means and said positon detecting means canprising a Hall device responsive to a magnetic field of the magnetic segments of one polarity for providing bias from the resistance means to the first transistor means to cause conduction therein while depriving the second transistor means of bias to prevent conduction therein, and responsive to the absence of said field for providing bias fran the resistance means to the second transistor means to cause conduction therein while depriving the first transistor means of bias to prevent conduction thereof.
Claim 10
Dependent Claim
130 words
The motor according to claim 8, wherein each transistor means connected in series with its associated winding across motor input voltage connections, the resistance means carprises resistors in series and connected with at least one of the motor input voltage connections, and connected with terminals of the transistors to bias the first or second transistor means into conduction upon establishment of appropriate bias voltage across the resistors, and the Hall device comprises a Hall switch connected between a junction of the resistors and one of the motor input voltage connections, said Hall switch being connected with the resistors to bypass at least one resistor in the presence of said field of magnetic segments of one polarity and to thereby alter the bias provided by the resistors to the transistor means.
Claim 11
Dependent Claim
73 words
A motor according to claim 9, wherein the first transistor means is a PNP transistor connected between a high side of the motor input connections and the first winding, and the second transistor means is an NPN Darlington transistor pair connected between a low side of the motor input connections and the second winding, both of said transistor means having their bases connected to the resistance means for control by the Hall switch.
Claim 12
Dependent Claim
113 words
A motor according to claim 9, wherein the first transistor means is a power transistor means requiring a relatively high drive to cause conduction therein and the second transistor means is a high gain transistor means requiring a relative low drive to cause conduction therein, said ressistors in series providing the relatively low drive to the second transistor means when the Hall switch is open and the Hall switch being connected to place a relatively large voltage drop across at least a portion of the resistors in series when closed, thereby to substantially short the bias to the high gain transistor means and supply the relatively high bias to the power transistor means.
Claim 13
Dependent Claim
19 words
The motor according to claim 1, wherein the coil means comprises two electrically independent and concentrically wound coil windings.
Claim 14
Dependent Claim
36 words
The motor according to claim 12, wherein the electromagnetic structure defines at least one pole piece and wherein the two coil windings are wound on a core in electromagnetic flux conducting relationship to the pole piece.
Claim 15
Dependent Claim
40 words
The motor according to claim 1, wherein the stator includes a housing defining a compartment at one location on the periphery of the path of rotation of the annular magnet, and wherein said coil means is located in said compartment.
Claim 16
Dependent Claim
88 words
The motor according to claim 14, wherein said coil has two windings, wherein said compartment houses the position detecting means for detecting and camutating, and wherein the position detecting and commutating means includes a Hall effect device located proximate the annular magnet, and switching circuit means for energizing one coil winding when magnetized segments of a first polarity are adjacent the Hall effect device, and for energizing the other coil winding when magnetized segments having a second polarity opposite said first polarity are adjacent the Hall effect device.
Claim 17
Dependent Claim
14 words
The motor according to claim 14, wherein the stator housing encircles the annular magnet.
Claim 18
Dependent Claim
18 words
A fan having a motor according to claim 1, the fan having blades located within the annular magnet.
Claim 19
Dependent Claim
80 words
A fan according to claim 17, wherein the fan blades extend from proximate the inside surface of the annular magnet to a central hub, said stator having a central member supporting, for rotation, the hub, the blades, and the rotor members, including the annular magnet, the stator further including struts extending outwardly fran the central stator member to a housing encircling the fan blades, said housing supporting the coil proximate the annular rotor magnet and adjacent the outer surface thereon.
Claim 20
Dependent Claim
104 words
A fan and motor combination including a central rotatable hub, fan blades radiating outwardly fran the hub, an annular perm- nent magnet having segments polarized oppositely in the radial outward direction, said permanent magnet encircling the blades of the fan and secured to the blades, a housing encircling the annular permanent magnet, a stator coil having two windings and an electromagnet structure defining pole pieces supported by the housing outside the annular magnet, and commutation means responsive to the position of the permanent magnet to repeatedly and alternately energize the coil windings to apply to a rotary force to segments of the annular magnet.
Claim 21
Dependent Claim
104 words
A fan and motor combination including a central rotatable hub, fan blades radiating outwardly fran the hub, an annular perm- nent magnet having segments polarized oppositely in the radial outward direction, said permanent magnet encircling the blades of the fan and secured to the blades, a housing encircling the annular permanent magnet, a stator coil having two windings and an electromagnet structure defining pole pieces supported by the housing outside the annular magnet, and commutation means responsive to the position of the permanent magnet to repeatedly and alternately energize the coil windings to apply to a rotary force to segments of the annular magnet.
References Cited (Backward Citations)
FR2478896A1
Cited
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