Patent US4517480A successfully refreshed from Google Patents.
US4517480A
Expired / Lapsed
US
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Tachogenerator for speed control of electric motors
Assignee: Papst Licensing GmbH and Co KG
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Filing: 1983-03-25
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Granted: 1985-05-14
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Expires: 2003-03-25
Abstract
Abstract A motor has been proposed in German Offenlegungsschrift DE-OS No. 2 730 142. The windings of the tacho winding are disposed here next to the stator winding in the flat air gap of the main magnet, and the current changes in the statorwinding induce therefor in the tachowinding voltages interfering with a precise working control. On the other hand would a disposition of the tacho generator at a different position of the motor increase its axial length considerably, especially when a magnetic shielding between the motor and the tachogenerator is provided. Therefor, it is a purpose of the present invention to provide a motor of the kind initially cited, which with compact construction and especially short length in direction of its rotation axis provides a low interference tacho signal remaining the same or improving with increasing age of the motor, for example in order to improve in any case, but at least to keep the same the ganging flutter of a speed controlled direct drive motor for a record player.
Inventors
- 👤 Rolf Muller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 07:04
CPC Classifications
H; H02; H02K; H02K21/00; H02K21/12; H02K21/24; H02K29/00; H02K29/14
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
175 words
A tachogenerator for speed control of electrical motors having an axial bearing for compensating the axial forces acting on the rotor comprising a flat multipole permanent magnet solidly connected to the rotor of the motor and having a number p of pairs of magnetic poles on its surface uniformly arranged on a circle of diameter d for the pole centers, a circular wave winding solidly connected to the stator and separated from the permanent magnet by a flat air gap of a width g and having a number p of angular substantially repeat units of the wave winding wherein p is equal to from about 0.5 to 1.5 times the ratio of the diameter d divided by the width g, with d and g being measured in the same units; and a corresponding return winding corresponding to the wave winding and disposed running in opposite angular direction to the wave winding for compensating the effect of the wave winding on a magnetic field component in axial direction running through the circle of the wave winding.
Claim 2
Dependent Claim
175 words
A tachogenerator for speed control of electrical motors having an axial bearing for compensating the axial forces acting on the rotor comprising a flat multipole permanent magnet solidly connected to the rotor of the motor and having a number p of pairs of magnetic poles on its surface uniformly arranged on a circle of diameter d for the pole centers, a circular wave winding solidly connected to the stator and separated from the permanent magnet by a flat air gap of a width g and having a number p of angular substantially repeat units of the wave winding wherein p is equal to from about 0.5 to 1.5 times the ratio of the diameter d divided by the width g, with d and g being measured in the same units; and a corresponding return winding corresponding to the wave winding and disposed running in opposite angular direction to the wave winding for compensating the effect of the wave winding on a magnetic field component in axial direction running through the circle of the wave winding.
Claim 3
Dependent Claim
38 words
The tachogenerator according to claim 1 wherein p is equal to from about 0.8 to 1 times the ratio of the diameter d divided by the width g, with d and g being measured in the same units.
Claim 4
Dependent Claim
16 words
The tachogenerator according to claim 1 wherein the diameter d is at least about 10 mm.
Claim 5
Dependent Claim
16 words
The tachogenerator according to claim 1 wherein the diameter d is at most about 100 mm.
Claim 6
Dependent Claim
18 words
The tachogenerator according to claim 1 wherein the diameter d is from about 30 mm to 50 mm.
Claim 7
Dependent Claim
20 words
The tachogenerator according to claim 1 wherein the width g of the air gap is at least about 0.2 mm.
Claim 8
Dependent Claim
20 words
The tachogenerator according to claim 1 wherein the width g of the air gap is at most about 2 mm.
Claim 9
Dependent Claim
20 words
The tachogenerator according to claim 1 wherein the width of the air gap is from about 0.5 to 1 mm.
Claim 10
Dependent Claim
37 words
The tachogenerator according to claim 1 wherein the number p of pole pairs is equal to from about 1 to 2 times the number of pole pairs corresponding to the maximum induced voltage at the frequency desired.
Claim 11
Dependent Claim
14 words
The tachogenerator according to claim 1 wherein the wave winding is a meander winding.
Claim 12
Dependent Claim
23 words
The tachogenerator according to claim 2 wherein the meander winding is provided by a conductor disposed on a plastic disc by photolithographic techniques.
Claim 13
Dependent Claim
29 words
The tachogenerator according to claim 1 further comprising a soft magnetic material disposed on the side of the wave winding opposite to the side facting the multipole permanent magnet.
Claim 14
Dependent Claim
15 words
The tachogenerator according to claim 12 wherein the soft magnetic material provides a magnetic shield.
Claim 15
Dependent Claim
19 words
The tachogenerator according to claim 1 wherein the wave winding is attached to a support tube of the rotor.
Claim 16
Dependent Claim
23 words
The tachogenerator according to claim 1 wherein the multipole permanent magnet is attached to a soft magnetic backing solidly connected to the rotor.
Claim 17
Dependent Claim
16 words
The tachogenerator according to claim 1 wherein the multipole permanent magnet is a so-called rubber magnet.
Claim 18
Dependent Claim
20 words
The tachogenerator according to claim 16 wherein the so called rubber magnet is adhesively attached to a soft magnetic material.
Claim 19
Dependent Claim
17 words
The tachogenerator according to claim 1 wherein the electric motor is a two strand brushless d.c. motor.
Claim 20
Dependent Claim
55 words
The tachogenerator according to claim 18 wherein the rotor comprises successively a north pole magnet zone of 120° electrical, a south pole magnet zone of 120° electrical and a remaining zone of 120° electrical having a magnetization generating in a magnetically active section of the stator winding at a relative motion substantially a zero voltage.
Claim 21
Dependent Claim
26 words
The tachogenerator according to claim 1 further comprising a motor magnetic ring of the rotor forming in its interior a hollow space for disposing the tachogenerator.
Claim 22
Dependent Claim
21 words
The tachogenerator according to claim 1 wherein the flat multipole permanent magnet comprises a magnetic plate formed from a rubber magnet.
Claim 23
Dependent Claim
35 words
The tachogenerator according to claim 21 further comprising a magnetic short circuit plate attached to the magnetic ring of the rotor and wherein the magnet plate is adhesively attached to the magnetic short circuit plate.
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) | 1988-05-13 | 1988-11-12 | 1989-05-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-13 | 1992-11-12 | 1993-05-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-13 | 1996-11-12 | 1997-05-14 | $7700.00 | Window Closed / Lapsed |