US3873897A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Collector-less D-C motor
Assignee: Papst Licensing GmbH and Co KG
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Filing: 1973-05-23
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Granted: 1975-03-25
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Expires: 1993-05-23
Abstract
Abstract A permanent magnet rotor operates within the air gap of a stator magnetic circuit which has a stator winding. Current through the winding is controlled by a selectively energized semiconductor switch, which is energized over a portion of rotor rotation and in synchronism therewith. The air gap included in the magnetic circuit is non-uniform along its length, increasing to a maximum intermediate the extent of a pole, for example between 10 to 50 electrical degrees, and then decreasing to a minimum over the remainder to 180 electrical degrees over a pole. The winding is energized to cause rotation of the rotor while the permanent magnet is within a predetermined angular range, resulting in storage of magnetic energy which is released as torque upon further rotation of the rotor in another angular range. The timing of energization of the winding by a control circuit can be used to control motor speed.
Inventors
- 👤 Rolf Muller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:40
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/08; H02K; H02K29/00; H02K29/06; H02K29/08; H02P6/26; H02P2209/00; H02P2209/07
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
387 words
Brushless d-c motor having a permanent magnet rotor (11); a stator (13, 14, 15); a winding (18, 19) on the stator to generate an electromagnetic field when energized; and an air gap (26, 27, 111, 112, 116-119) separating the rotor and the stator; controlled semiconductor switching means (38, 39) controlling pulsed current flow through the winding; wherein the width of said air gap is non-uniform, in zones, so that the reluctance of the magnetic circuit which includes said stator, said air gap and said rotor varies with angular position over the circumference of the stator, said zones, in the direction of rotation of the motor being defined by: a zone of increasing width of the air gap and hence increasing reluctance of the magnetic circuit extending over a first angular range ( Alpha ) to a maximum (d2), and then a zone of decreasing width of the air gap and hence decreasing reluctance of the magnetic circuit extending over a second angular range ( Beta ) to a minimum (d1), and means (25) synchronizing pulsed energization of the semiconductor switching means and hence of the winding with the angular position of the rotor to generate, electrodynamically, an interrupted, pulsed electromagnetic torque during such pulsed energization of the winding by interaction of the magnet of the rotor with the electromagnetic field, due to energization of the winding and to store during such pulsed energization of the winding a portion of said generating torque in form of magnetic reluctance torque by interaction of the magnet of the rotor with the magnetic structure of the stator when the magnet of the rotor is in an angular range which includes at least part of said zone of increasing width of the air gap, the reluctance torque stored in magnetic form being released to the rotor, during pulse gaps, or interruptions in the generated electromagnetic field, by interaction of the magnet of the rotor with the magnetic structure of the stator when the magnet of the rotor is in an angular range which includes at least part of said zone of decreasing width of the air gap, the alternating component of the electrodynamically generated torque and the magnetic reluctance torque being in phase opposition and, together, providing a net driving torque to the rotor upon its rotation with respect to the stator.
Claim 2
Dependent Claim
387 words
Brushless d-c motor having a permanent magnet rotor (11); a stator (13, 14, 15); a winding (18, 19) on the stator to generate an electromagnetic field when energized; and an air gap (26, 27, 111, 112, 116-119) separating the rotor and the stator; controlled semiconductor switching means (38, 39) controlling pulsed current flow through the winding; wherein the width of said air gap is non-uniform, in zones, so that the reluctance of the magnetic circuit which includes said stator, said air gap and said rotor varies with angular position over the circumference of the stator, said zones, in the direction of rotation of the motor being defined by: a zone of increasing width of the air gap and hence increasing reluctance of the magnetic circuit extending over a first angular range ( Alpha ) to a maximum (d2), and then a zone of decreasing width of the air gap and hence decreasing reluctance of the magnetic circuit extending over a second angular range ( Beta ) to a minimum (d1), and means (25) synchronizing pulsed energization of the semiconductor switching means and hence of the winding with the angular position of the rotor to generate, electrodynamically, an interrupted, pulsed electromagnetic torque during such pulsed energization of the winding by interaction of the magnet of the rotor with the electromagnetic field, due to energization of the winding and to store during such pulsed energization of the winding a portion of said generating torque in form of magnetic reluctance torque by interaction of the magnet of the rotor with the magnetic structure of the stator when the magnet of the rotor is in an angular range which includes at least part of said zone of increasing width of the air gap, the reluctance torque stored in magnetic form being released to the rotor, during pulse gaps, or interruptions in the generated electromagnetic field, by interaction of the magnet of the rotor with the magnetic structure of the stator when the magnet of the rotor is in an angular range which includes at least part of said zone of decreasing width of the air gap, the alternating component of the electrodynamically generated torque and the magnetic reluctance torque being in phase opposition and, together, providing a net driving torque to the rotor upon its rotation with respect to the stator.
Claim 3
Dependent Claim
18 words
Motor according to claim 1, wherein the first angular range ( Alpha ) is approximately 10* to 100*-electrical.
Claim 4
Dependent Claim
56 words
Motor according to claim 1, wherein the air gap decreases from a maximum (d2) at the beginning of the second angular range ( Beta ) approximately monotonically to a minimum (d1), said minimum being located by a third angle ( gamma ) in advance of the centeR of the electromagnetic field when the winding is energized.
Claim 5
Dependent Claim
16 words
Motor according to claim 3, wherein said second angular range ( Beta ) is about 80*-160*-electrical.
Claim 6
Dependent Claim
18 words
Motor according to claim 3, wherein said third angular range ( gamma ) is from 0* to 30*-electrical.
Claim 7
Dependent Claim
35 words
Motor according to claim 3, wherein the air gap increases approximately monotonically in a fourth angular range ( delta ) to the maximum (d2), said fourth range including said first angular range ( Alpha ).
Claim 8
Dependent Claim
16 words
Motor according to claim 6, wherein said fourth angular range ( delta ) is about 20*-100*-electrical.
Claim 9
Dependent Claim
23 words
Motor according to claim 1, wherein the motor is a two-pole external rotor motor and the stator (13) has approximately elliptical cross section.
Claim 10
Dependent Claim
37 words
Motor according to claim 8, wherein the main axis (32) of the ellipse includes an angle ( epsilon ) having a value between about 40*-80*-electrical, with an axis (33) passing through the center of the stator poles.
Claim 11
Dependent Claim
41 words
Motor according to claim 1 (FIG. 5), wherein the motor is a two-pole internal rotor motor and the stator is formed with an internal essentially cylindrical space in which the rotor may turn, which space is approximately elliptical in cross section.
Claim 12
Dependent Claim
34 words
Motor according to claim 1 (FIG. 6), wherein the stator of the motor has a circumference facing the air gap which has portions flattened with respect to a complete circle coaxial with the motor.
Claim 13
Dependent Claim
49 words
Motor according to claim 11, wherein the motor is a four-pole motor and the stator structure has four flattened portions uniformly distributed above the circumference of the stator; the windings are located in winding slots (120-123), said slots being located at portions of the rotor between said flattened portions.
Claim 14
Dependent Claim
28 words
Motor according to claim 1, wherein the synchronization means (25) comprises a magnetic semiconductor sensing means located at an angular position corresponding to that between adjacent stator poles.
Claim 15
Dependent Claim
17 words
Motor according to claim 1, wherein the permanent magnet rotor (11) has approximately sinusoidal distribution of magnetism.
Claim 16
Dependent Claim
17 words
Motor according to claim 1, wherein the permanent magnet rotor (11) has approximately trapezoidal distribution of magnetism.
Claim 17
Dependent Claim
16 words
Motor according to claim 1, wherein the permanent magnetic rotor has approximately rectangular-shaped distribution of magnetization.
Claim 18
Dependent Claim
66 words
Motor according to claim 1, wherein the synchronizing means comprises a magnetic sensing element (25) and a speed controller circuit (FIG. 3) including the sensing element, said circuit controlling the semiconductor switching means (38, 39) to interrupt energization of the winding before the theoretical commutation instant sensed by the sensing element and to re-energize the winding after the theoretical commutation instant sensed by the sensing element.
Claim 19
Dependent Claim
37 words
Motor according to claim 17, wherein the winding is a two-part winding and the duration of energization of any part of the winding at the desired speed is less than 120*-electrical to generate a driving torque (Mel).
Claim 20
Dependent Claim
41 words
Motor according to claim 17, wherein the driving torque (Mel) generated during energization of the winding and the torque (Mrel) released or delivered by stored magnetic energy are substantially complementary, whereby the added instantaneous values provide a substantially uniform output torque.
Claim 21
Dependent Claim
65 words
Motor according to claim 1, wherein the synchronizing means comprises magnetic sensing means (25) and a control circuit comprising means (68, 69) sensing induced a-c voltages in the stator winding during operation of the motor; means (85) phase-shifting the sensed a-c voltages; and means (100, 84) deriving a control signal to energize the semiconductor switching means in dependence on a characteristic of the phase-shifted voltage.
Claim 22
Dependent Claim
23 words
Motor according to claim 20, wherein the phase-shift means (85) comprises means shifting the phase of the induced a-c voltageS by about 180*-electrical.
Claim 23
Dependent Claim
14 words
Motor according to claim 20, wherein the phase-shift means (85) comprises a multi-stage filter.
Claim 24
Dependent Claim
16 words
Motor according to claim 22, wherein the multi-stage filter comprises a plurality of series-connected R-C circuits.
Claim 25
Dependent Claim
30 words
Motor according to claim 20, further comprising voltage reference means (95) and wherein said characteristics comprise a comparison of amplitude of the phase-shifted voltage with respect to the reference means.
Claim 26
Dependent Claim
11 words
Motor according to claim 24, wherein the comparison level is adjustable.
Claim 27
Dependent Claim
20 words
Motor according to claim 20, wherein the phase-shift means comprises a multi-stage filter (85) and a control amplifier connected thereto.
Claim 28
Dependent Claim
36 words
Motor according to claim 20, further comprising a temperature sensitive element (87) included in the control circuit, said temperature sensitive element being dimensioned to compensate for temperature dependency of remanent induction of the permanent magnetic rotor.
Claim 29
Dependent Claim
19 words
Motor according to claim 20, wherein the means sensing the induced voltage comprises a multi-phase half-wave rectifier (68, 69).
Claim 30
Dependent Claim
365 words
Brushless d-c permanent magnet rotor and control circuit combination comprising a stator having at least one winding thereon to selectively energize at least two poles, in respective directions of magnetization; semiconductor control means selectively energizing the winding, alternately, in respective directions of magnetization in pulses, leaving pulse gaps between energizing pulses; a permanent magnet rotor opposed to the poles of the stator; an air gap separating the rotor and the stator poles, said air gap being characterized in that progressing in the direction of rotation of the motor, the air gap has a first zone of increasing width, so that the reluctance of the magnetic path between rotor and stator increases in said first zone, said first zone extending over a first angular range ( Alpha ) to a maximum (d2), and the air gap has a second zone of decreasing width, so that the reluctance of said magnetic path then decreases in said second zone, said second zone extending over a second angular range ( Beta ) to a minimum (d1), to store magnetic energy by interaction of the magnetism of the rotor with the magnetic structure of the stator when a pole of the rotor is in said first zone and to release the stored energy in the form of delivered torque by interaction of the permanent magnetism of the rotor with the magnetic structure of the stator when a pole of the rotor is in said second zone; magnetic sensing means sensing the angular position of a pole of the rotor with respect to the winding on the stator; a control circuit responsive to and connected to said magnetic sensing means and controlling said semiconductor control means to energize the winding in respective direction of current flow and generate a magnetic field, in alternate direction, in synchronism with the position of a pole of the rotor in said first zone, and to de-energize the winding when the pole of the rotor is in the second zone, to generate electrodynamically, an interrupted pulsed torque having an alternating component in phase opposition to the torque applied to the rotor as the magnets of the rotor interact with the respective zones of the magnetic structure.
Claim 31
Dependent Claim
365 words
Brushless d-c permanent magnet rotor and control circuit combination comprising a stator having at least one winding thereon to selectively energize at least two poles, in respective directions of magnetization; semiconductor control means selectively energizing the winding, alternately, in respective directions of magnetization in pulses, leaving pulse gaps between energizing pulses; a permanent magnet rotor opposed to the poles of the stator; an air gap separating the rotor and the stator poles, said air gap being characterized in that progressing in the direction of rotation of the motor, the air gap has a first zone of increasing width, so that the reluctance of the magnetic path between rotor and stator increases in said first zone, said first zone extending over a first angular range ( Alpha ) to a maximum (d2), and the air gap has a second zone of decreasing width, so that the reluctance of said magnetic path then decreases in said second zone, said second zone extending over a second angular range ( Beta ) to a minimum (d1), to store magnetic energy by interaction of the magnetism of the rotor with the magnetic structure of the stator when a pole of the rotor is in said first zone and to release the stored energy in the form of delivered torque by interaction of the permanent magnetism of the rotor with the magnetic structure of the stator when a pole of the rotor is in said second zone; magnetic sensing means sensing the angular position of a pole of the rotor with respect to the winding on the stator; a control circuit responsive to and connected to said magnetic sensing means and controlling said semiconductor control means to energize the winding in respective direction of current flow and generate a magnetic field, in alternate direction, in synchronism with the position of a pole of the rotor in said first zone, and to de-energize the winding when the pole of the rotor is in the second zone, to generate electrodynamically, an interrupted pulsed torque having an alternating component in phase opposition to the torque applied to the rotor as the magnets of the rotor interact with the respective zones of the magnetic structure.
Claim 32
Dependent Claim
59 words
Motor and control circuit combination as in claim 29, further comprising speed control means comprising means deriving a signal representative of motor speed; command means connected to said signal deriving means and delivering a speed command signal; and means controlling the duration of energization of said winding by said semiconductor control means in dependence on said speed command signal.
Claim 33
Dependent Claim
60 words
Motor and control circuit combination as in claim 29, wherein the air gap decreases from a maximum (d2) at the beginning of the second angular range ( Beta ) approximately monotonically to a minimum (d1), said minimum being located By a third angle ( gamma ) in advance of the center of the electromagnetic field when the winding is energized.
Claim 34
Dependent Claim
53 words
Motor and control circuit combination as in claim 31, wherein said control circuit controls said semiconductor control means to energize the winding in respective direction of current flow when a pole of the rotor has rotated beyond said third angle ( gamma ) and while said pole is still in said first zone.
Claim 35
Dependent Claim
21 words
Motor and control circuit combination as in claim 29, wherein the permanent magnet rotor (11) has approximately sinusoidal distribution of magnetism.
Claim 36
Dependent Claim
20 words
Motor and control circuit combination as in claim 29, wherein the permanent magnet rotor has approximately trapezoidal distribution of magnetism.
Claim 37
Dependent Claim
28 words
Motor as in claim 1, wherein the synchronization means (25) comprises a magnetic field sensing means located at an angular position corresponding to that between adjacent stator poles.
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) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |