Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-05-21
2001-07-31
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S180000, C310S184000, C310S185000
Reexamination Certificate
active
06268675
ABSTRACT:
The invention relates to a magnetically journalled electrical drive in accordance with the preamble of the independent patent claim.
BACKGROUND OF THE INVENTION
Magnetic journalling technology opens up fields of application of machine and apparatus construction with extremely high requirements on the speed of rotation region, the lifetime, the purity and the sealing tightness of the drive system—thus substantially fields of application which can not or can only with difficulty be realised using conventional journalling techniques. Various embodiments, such as for example high speed milling and grinding spindles, turbocompressors, vacuum pumps, or pumps for chemical or medical products of high purity are already being equipped with magnetic bearings.
A conventional magnetically journalled electrical machine (
FIG. 1
) requires, in addition to a machine unit
1
, two radial magnetic bearings
2
and
3
respectively, an axial magnetic bearing
4
, two mechanical interception bearings
5
and
6
respectively and a total of thirteen power controllers
7
,
8
,
9
and
10
for the excitation of the motoric and magnetic bearing loops.
There are proposals (
FIG. 2
) in the literature for integrating machine and radial magnetic bearings in a magnetic stator unit. Two separate winding systems
11
and
12
for the torque and suspension force winding are inserted into multiply layered into grooves in a stator. Both winding systems are three-looped and differ by one in the number of pole pairs. The coils are distributed over a plurality of grooves. The example of
FIG. 2
shows:
a four-pole machine winding
11
(outside): first loop
13
, second loop
14
, third loop
15
a two-pole suspension winding
12
(inside): first loop
16
, second loop
17
, third loop
18
.
The arrows (without reference symbols) from the rotor in the direction towards the stator or from the stator in the direction towards the rotor stand for the direction of the magnetisation of the four magnetic rotor segments (e.g. radial or diametral magnetisation).
In applications which require no rigid-axis rotor guidance, such as for example in ventilators, fans, pumps or mixers, the axial magnetic bearing and the second radial magnetic bearing can be omitted from the integrated machine-magnetic-bearing embodiment. A prerequisite for this is a disc-shaped embodiment of the rotor with a length dimension (
FIG. 3
) which is small with respect to the rotor diameter. Thus a passive stabilization of the rotor position in the axial direction and the tilt directions can be achieved via the magnetic traction
41
between the stator
39
and the rotor
40
.
In many cases however the complicated and expensive system construction and therewith the higher manufacturing costs stand in the way of the technical use of magnetic journalling. The object of the invention consists therefore in the simplification of the mechanical construction of the machine and magnetic bearing unit taking into consideration the electronic excitation which is suitable for this.
SUMMARY OF THE INVENTION
A magnetically journalled electrical drive comprises a magnetically journalled electrical machine with windings which are inserted in the stator or rotor for the production of torque and the suspension for it. An analog or digital electronic circuitry is used for control, regulation, monitoring, and excitation of the magnetically journalled machine. The magnetically journalled machine is equipped in the stator with windings which are utilized via a corresponding excitation through the electronic circuitry, both for the production of the suspension force for the rotor and for the production of torque. The rotor is of a type generating its own magnetic flux.
Of particular advantage in the solution of the object in accordance with the invention is the considerably simplified stator or rotor construction respectively and the winding construction of the magnetically journalled machine with respect to previously known solutions as well as the saving of power controllers.
REFERENCES:
patent: 5036235 (1991-07-01), Kleckner
patent: 5053662 (1991-10-01), Richter
patent: 5237229 (1993-08-01), Ohishi
patent: 5424595 (1995-06-01), Preston
patent: 0768750A1 (1997-04-01), None
Lam Thanh
Ramirez Nestor
Sulzer Electronics AG
Townsend and Townsend / and Crew LLP
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