Electricity: measuring and testing – Magnetic – Displacement
Patent
1992-05-13
1993-09-28
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
Displacement
73168, 73660, 32420722, 32420724, 32420725, 324226, 415118, 417 63, G01B 714, F04B 5100, G01M 1304
Patent
active
052489400
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to apparatus for measuring the change of position of a rotor.
We will describe the invention with reference to socalled seal-less pumps and the like in which a driven inner rotor is connected to an impeller of the pump, the impeller and inner rotor being sealingly mounted within a closed system through which the fluid to be pumped flows, the inner rotor being mounted within a generally cylindrical sealed shroud which closely surrounds said inner rotor, and there being mounted a drive outer rotor surrounding the shroud which is magnetically coupled with the inner rotor so that as the drive outer rotor rotates, it drives the driven inner rotor and hence the impeller.
The magnetic coupling may comprise permanent magnets forming part of the inner and outer rotor, or there may be provided coils which cooperate by means of magnets produced by eddy currents, or the outer rotor may, in place of permanent magnets comprise electro magnets, the inner and outer rotor effectively forming an electric motor so that a separate motor is not required.
Such a drive system may be used to operate other apparatus for example mixers, fans and blowers. Furthermore, arrangements are known where the drive and driven rotors are disc-like and arranged face to face.
One of the difficulties of such an arrangement, as is well known, is that, because the inner rotor is mounted within the sealed shroud and is therefore not visible, it is not possible to check the bearings of the inner rotor without dismantling the apparatus. This has been a particular problem and requires the pump to be stripped at regular intervals.
The present invention relates to means for measuring change of position (e.g. radial and/or axial position) of a rotor in a drive system comprising a drive (usually outer) rotor, a driven (usually inner) rotor generally concentrically mounted with respect to the drive rotor, the drive and driven rotors being magnetically coupled together, said apparatus comprising conduction means stationarily mounted between said rotors, and means for measuring the emf (electro motive force) produced in said conduction means as said rotors rotate, and means for determining, from said measurement, the relative position of the two rotors and/or the position of one of the rotors.
It should be understood that if the bearings on the driven rotor wear, the relative radial positions of the two rotors will change and this will affect the magnetic flux coupling between the two rotors, whereby the emf produced by the conduction means will vary.
The conduction means is preferably mounted on a stationary housing between the driven and drive rotor.
The drive system may be a seal-less pump which includes a sealing shroud between the drive rotor and the driven rotor, said conduction means being mounted on or forming part of said sealing shroud.
Whilst the conduction means may comprise a single length of conductive wire which cuts the lines of the magnetic field between the drive and driven rotors as they rotate relative to the wire, in a preferred arrangement, two conduction means may be provided spaced at, for example, 180.degree. intervals around the axis of the housing. In a preferred arrangement one conduction means may be at the top of the housing and one at the bottom. In a yet more preferred arrangement, four conduction means may be provided spaced at substantially 90.degree. intervals around the axis of the rotors.
In place of a single length of wire, where the rotors are inner and outer coaxial rotors, the conduction means may comprise one (or more) loops (each loop comprising a sensor) including lengths extending substantially parallel to the axis ("active conductors"), and other lengths extending circumferentially around the housing ("connector wires"). The lengths extending parallel to the axis ("active conductors") may be spaced at a distance equal to the pitch distance between successive circumferentially disposed magnets attached to the inner and/or outer rotor.
The means for determining the relative positions o
REFERENCES:
patent: 3981621 (1976-09-01), Considine
Beam Palmer H.
Patience Brian M.
West David A.
HMD Seal/Less Pumps Limited
Strecker Gerard R.
LandOfFree
Apparatus for measuring changes in radial and/or axial position does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for measuring changes in radial and/or axial position , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for measuring changes in radial and/or axial position will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2193133