GB2182809A

GB2182809A - Stator having a spiral yoke

Info

Publication number: GB2182809A
Application number: GB08526806A
Authority: GB
Inventors: Karsten Laing; John Laing
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-11-02
Filing date: 1985-10-31
Publication date: 1987-05-20
Anticipated expiration: 2005-10-31
Also published as: GB2182809B; GB8526806D0

Abstract

An induction motor having discrete poles which are distributed over the circumference and made up of sheet metal lamination formed as teeth (25) whose magnetic flux is conducted through a sheet metal spiral (28) which is brought into magnetically highly conductive contact with the teeth (25) over a rotational plane. <IMAGE>

Description

SPECIFICATION Stator having a spiral yoke The invention refers to electric motors, especially those forming one unit with centrifugal pumps, in which the stator yoke is made as a spiral of magnetic laminations.

Electric motors built up from stator laminations shaped with polar symmetry are not suitable for electric motors in which the airgap runs along the surface of a sphere or of a cone. But electric motors having spherical airgaps are increasingly gaining in importance.

The invention is aimed in particular at motors of that kind.

The stator yoke of electric motors is the member which determines the diameter of an electric motor. The stator yoke must exhibit approximately the same cross-sectional area in a radial plane as the rotor of the motor. Since the stator yoke runs outside the windings, the diameter and therefore the consumption of material for leading back the magnetic flux, particularly in the case of two-pole motors, is very large.

Hitherto for spherical motors stators having teeth running in parallel with the axis have been used, which lead to an unconventional winding technique and exhibit great axial length and thereby high stray losses.

The invention avoids both the very high consumption of material by the stator yoke and also the great structural length of motors having teeth parallel with the axis.

In accordance with the invention teeth formed from sections of lamination are arranged round the airgap, between which windings are arranged, which are constructed after the same style as with conventional induction motors. But the windings of the stators in accordance with the invention may also be produced according to the same method as in the case of the rotors of d.c. motors by conventional armature winding machines. The teeth exhibit an edge lying in a plane of rotation and the spiral of laminations fits against this edge and takes over the magnetic return path.

The invention also refers to centrifugal pumps which form one unit with the motors in accordance with the invention.

The invention is to be explained with respect to a Figure.

Figure 1-shows in section a motor-centrifugal pump unit in accordance with the invention; and Figure 2-shows a section along the line of section l-l with the omission of the wall of the casing and the winding.

The rotor 1 forms with the impeller 2 one unit arranged to be able to rotate, which is supported by the bearing cap 3 upon the ball 4 which is arranged stationary. The entry of the flow medium is effected through the perforated cone 6 which ends in a flange 5 having fixing holes 7. A stationary tube 8 forms together with the cylindrical region 9 of the cone 6 the seating 10 for a sealing ring. The dividing wall 11 of spherical formation in the gap 12 for the magnetic flux is connected to the tube 8 by welding. This dividing wall continues into an annular region 13 and ends in the flange 14. Between the rotor 1 and the blade cover 15 a stationary wall 16 is inserted, which forms a gap with a spherical region 17 of the rotor 1 and the plane annular region 18 of which is held in its position by the vane ring 19.The flow medium leaving the vane ring is slipped through the pump casing 20 having the blading 21 for absorbing the angular momentum, to the outlet region 22.

As also illustrated in Fig. 2, the stator of the motor consists of stator teeth 25 which are arranged with uniform distribution over the circumference of the dividing wall 11 and which are formed from sections of lamination lying side by side in the circumferential direction. These teeth are widened at the end next the rotor 1 so that they overlap the whole axial length 26 of the iron region of the rotor 1. in the axial region 27 pointing outwards the edges of these teeth lie in an axial annular region. Against this annular region fits a stator yoke having a spiral 28 wound from magnetic lamination, the annular surface 29 of which is advantageously ground plane.

The motor casing consists of the potshaped part 30 in which after introduction of the winding 31 the flange 32 is fixed by screwing.

In the flange 32 ears 33 are cast, distributed round the circumference for screwholes.

The pump casing 20 is fastened to the motor casing 30/32 by the screws 34.

The wheel disc 35 of the impeller 2 is made with a thick wall of such a weight that the excess weight of the rotor 1 referred to the centre 36 of the ball is compensated. By this means the rotor-impeller unit 1, 2 may be driven in space in any position of the rotor axis 37. The stabilization of the rotor 1 is effected through the magnetic forces. If the motor is switched off this stabilizing force vanishes. A bearing 39 consisting preferably of plastics but which may also be made as a ball bearing, restricts the amplitude of the angle of wobble.

The gap 41 between the supporting bearing 39 and the rotor 2 is so dimensioned that in the gaps 42, 43, 44, 45 and 46 no contact can take place.

The cavities 47 remaining between the windings 31 are filled with a hardening resin by which the hydrostatic forces emanating from the pump casing 48 are absorbed, and by which at the same time the transfer of heat to the delivery flow is favoured.

Claims

1. An induction motor, in particular a motor-centrifugal pump unit having a stator the airgap of which runs along a spherical or conical surface and the winding of which is arranged between teeth which take over the conduction of the magnetic flux between the rotor and a stator yoke, characterized in that the teeth (25) exhibit, lying in a plane of rotation, regions (27) against which fits a stator yoke (28) which is built up from strips of magnetic laminations running along spiral lines.

2. An induction motor characterized in that the teeth (25) consist of a plurality of stacked sections of laminations, the central section of lamination of a stack in each case running along a radial plane.

3. An induction motor-centrifugal pump unit having an airgap running along a spherical surface, characterized in that the rotor (1) exhibits a bore into which reaches a stationary member (6) carrying a ball (4) and the centre (36) of the convex sliding partner (4) coincides with the centre of the spherical surface which bounds the airgap (12), and further the rotor (1) forms with an impeller (2) one rotating unit which is supported on the ball (4) via a bearing cap (3).

4. An induction motor having a spherical airgap as in Claim 1 and when the occasion arises 3, characterized in that the back of the bearing cap (3) is made spherical in the region (50) and that a spindle (51) connected to a stationary component (52) forms with the spherical region (50) a gap of such width that operationally the components (3 and 51) bounding the gap do not touch.

5. An induction motor-centrifugal pump unit as in Claim 1, characterized in that a tube (8) separating the suction side (5) from the pressure side forms with the inside of the bore in the rotor (1) a gap which runs in the plane of rotation (37) associated with the centre (36) of the ball.

6. An induction motor-centrifugal pump unit as in Claim 1, having an airgap running along a spherical surface, characterized in that the impeller (2) exhibits a wall thickness (35) exceeding that required by the strength, so that the centre of gravity of the mass of the rotating rn,:or-impeller unit (1, 2) coincides with the centre (36) of the ball.

7. An induction motor-centrifugal pump unit as in Claim 1, characterized in that the teeth (25) at their ends next the rotor (1) exhibit widening to form pole shoes over an axial distance predetermined by the length (26) of magnetic iron of the rotor (1).

8. An induction motor-centrifugal pump unit as in Claim 7, characterized in that the widenings to form pole shoes, which project beyond the axial tooth width exhibit crosssections which are in the ratio of the crosssections of the amounts of the axial extent (26) of the rotor (1), which are overlapped by the regions of widening.

9. An induction motor-centrifugal pump unit as in Claim 1, characterized in that between the rotor (1) and the impeller (2) runs a gap (42, 43) into which a stationary wall (16) projects.

10. An induction motor-centrifugal pump unit as in Claim 1, characterized in that its casing consists of a pump casing shell (20), a stator casing (30) made in the shape of a bell, and a flange (32) which is connectedly firmly to the stator casing (30).

11. An induction motor-centrifugal pump unit having a spherical airgap as in Claim 1, characterized in that the greatest diameter of the rotor (1) lies in the plane of rotation (37) containing the centre (36) of the ball and that the dividing wall (11) separating the pump chamber from the stator runs along a sphere and after reaching the greatest diameter tapers in again until the inner diameter of the dividing wall (11) coincides with the maximum diameter of the rotor.

CLAIMS Amendments to the claims have been filed, and have the following effect:- New or textually amended claims have filed as follows:

12. A pump unit comprising a centrifugal pump which has an impeller and which is integral with an induction motor whose stator is outside the pump chamber and whose rotor is inside the pump chamber and integral with the impeller, a dividing wall being provided between the stator and the rotor, the dividing wall extending along a spherical or conical surface and having a larger internal diameter at the end facing the impeller than at the opposite end, the stator having windings through which magnetically conductive teeth which are distributed over the circumference project and which define the conductive path for the magnetic flux between the rotor and a magnetic yoke, characterized in that the windings (31) define a toroid disposed around the dividing wall (11), that the teeth (25) project through the toroid of the windings (31), that at their inwardly directed boundary the teeth (25) extend over the axial length of the magnetic air gap (12), that these teeth (25) extend substantially radially outwardly, that at their side facing away from the impeller (2,35) the lami nae forming the teeth (25) have a precisely radially extending edge, that a spirally wound metal strip (28) touches all the radially extending edges of the laminae, and that the spirally wound strip (28) surrounds the part of the toroid of the windings (31) which faces away from the impeller.

13. A pump unit according to Claim 12 and constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying diagrammatic drawing.

14. An induction motor for a pump unit according to Claim 12, the motor being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying diagrammatic drawing.