Salient pole machine with rotor having rotor rim with pole-rim interface and fixation points

Abstract

A salient pole machine a rotor having a rotor rim. A plurality of salient poles having a pole winding and extending in the radial direction are attached to the rotor rim, with the rotor rim having an outermost radial surface between the pole-rim interfaces. A plurality of axial rib-like rim extensions project radially from the outermost radial surface of the rotor rim with a predetermined circumferential distance between neighboring rim extensions. A plurality of axial pole grooves in the salient pole match and receive the rim extensions. Fixing elements fix the rim extensions in the pole grooves and are inserted axially into facing interface holes defined in facing sidewalls of the pole grooves and the rib-like rim extensions. The fixing elements are radially inward of the pole windings and are accessible for axial sliding removal from the facing interface holes.

Claims

1. A salient pole machine comprising: a rotor rotatable about a machine axis, the rotor further comprising a rotor rim at a circumference thereof; a plurality of salient poles, each salient pole comprising a pole winding and extending in a radial direction and attached to the rotor rim at a pole-rim interface; the rotor rim comprising an outermost radial surface extending in the circumferential direction between the pole-rim interfaces; each of the pole-rim interfaces comprising: a plurality of axial rib-like rim extensions projecting radially from the outermost radial surface of the rotor rim with a predetermined circumferential distance (d) between neighboring rim extensions; a plurality of axial pole grooves provided in the salient pole matching and receiving the rim extensions; a plurality of axially extending fixing elements that fix the rim extensions in the pole grooves, the fixing elements inserted axially into facing interface holes defined in facing sidewalls of the pole grooves and the rib-like rim extensions; and the fixing elements radially inward of the pole windings and accessible for axial sliding removal from the facing interface holes, wherein the salient poles with pole windings are subsequently removable from the rotor.

2. The salient pole machine according to claim 1, wherein the fixing elements are arranged radially outward of the outermost radial surface of the rotor rim.

3. The salient pole machine according to claim 1, wherein the fixing elements extend in the axial direction of the rotor.

4. The salient pole machine according to claim 3, wherein the fixing elements comprise axial fixation pins.

5. The salient pole machine according to claim 4, wherein the axial fixation pins comprise shear pins having a circular cross section.

6. The salient pole machine according to claim 4, wherein the axial fixation pins comprise expansion pins.

7. The salient pole machine according to claim 4, wherein the axial fixation pins comprise split pins.

8. A method for removing salient poles with winding configured thereon from a rotor that is rotatable within a stator of a salient pole machine, wherein the salient poles are attached to a rotor rim at a pole-rim interface, each of the pole-rim interfaces including: a plurality of axial rib-like rim extensions projecting radially from the radial surface of the rotor rim; a plurality of axial pole grooves provided in the salient pole matching and receiving the rim extensions; a plurality of axially extending fixing elements that fix the rim extensions in the pole grooves, the fixing elements inserted axially into facing interface holes defined in facing sidewalls of the pole grooves and the rib-like rim extensions; wherein the method comprises: removing the fixing elements in an axial direction from the pole-rim interfaces; and sliding the salient poles with attached windings in an axial direction relative to the rotor to remove the salient poles from the rotor without removing the rotor from the stator.

9. The method according to claim 8, comprising moving the salient poles in a radial direction away from the rotor rim prior to sliding the salient poles in the axial direction relative to the rotor.

10. The method according to claim 8, wherein the rotor rim has an outermost radial surface extending in the circumferential direction between the pole-rim interfaces.

11. The method according to claim 8, wherein the fixing elements are radially inward of the pole windings and thereby accessible for axial sliding removal from the facing interface holes for removal of the removal of the salient poles with pole windings from the rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is now to be explained more closely by means of different embodiments and with reference to the attached drawings.

(2) FIG. 1 shows a detailed perspective view of a salient pole machine rotor with salient poles attached by means of pole claws according to prior art;

(3) FIG. 2 shows in a sectional axial view a pole attachment according to an embodiment of the invention; and

(4) FIG. 3 shows an enlarged view of the attachment region of FIG. 2.

DETAILED DESCRIPTION OF DIFFERENT EMBODIMENTS OF THE INVENTION

(5) In the prior art poles on salient pole machines are either fixed to the rotor rim using pole body extensions named “Pole Claws”, which are elements projecting from the pole body inwards the machine, fitting on rotor rim slots, or they are fixed through bolts, going radially through the rotor rim and part of the pole.

(6) According to the present invention the pole to rim connection (pole-rim interface) is optimized through a minimum height connection system, placed on pole side area, using shear pins in between.

(7) According to this idea, there are no pole claws extending inwards or fixing bolts. The rotor rim projects itself outwards, into the pole body and fixation is done with shear pins in between. Since pole fitting can be done radially, such solution can also help to minimize clearance between pole and rim, which helps strongly to minimize the reluctance through the magnetic path.

(8) Instead of the classical prior art solution, using slots cut radially located inside the outer radius of the rotor rim, as well as, pole claws projecting radially inwards to fix the pole core on the rotor rim, the present anchoring solution is developed basically in the pole core region, projecting the pole fixation outwards from the outer radius of the rim (and consequently inwards into the pole core).

(9) Part of the anchoring system or pole-rim interface is placed below or under the shadow of the pole coil. Thus, to remove the pole, after removing the connecting pins, it is necessary to slide the pole slightly radially, using the air gap space and then slide it axially, parallel to the rim axial length.

(10) FIGS. 2 and 3 show an embodiment of the present invention.

(11) The salient pole machine 30 of FIGS. 2 and 3 comprises a rotor 20, which rotates about a machine axis (not shown). Rotor 20 has at its circumference a rotor rim 28 with a predetermined outer radius 29. A plurality of salient poles 22, each extending in radial direction and being equipped with a pole winding 23, is attached to said rotor 20 at said rotor rim 21. Each pole is anchored to said rotor rim 21 at a pole-rim interface 24, which has the character of an interdigitation.

(12) At each pole-rim interface 24 a plurality of axial rib-like rim extensions 25 project radially from the cylindrical surface 28 of rotor rim 21 with a predetermined circumferential distance d between neighboring rim extensions 25. On the other side, each salient pole 22 has a plurality of axial pole grooves 26 matching and receiving said rib-like rim extensions 25 of the pole-rim interface 24.

(13) Salient pole 22 is fixed in this interdigitated configuration by means of fixing elements or fixation pins 27, which are provided to fix said rib-like rim extensions 25 in said pole grooves 26. Fixing elements 27 are arranged outside rotor rim 21. They extend and are applied in axial direction. They are arranged in respective interface holes between said pole grooves 26 and said rib-like rim extensions 25 at the sidewalls thereof, as shown in FIGS. 2 and 3.

(14) According to this solution, as this rib-like rim extensions or ribs 25, extending from the rotor rim 21 and fitting into the pole 22 are accessible, one can remove the pins 27 and slide the pole 22 axially without removing the rotor 20 from inside the generator stator. Furthermore, as there are no ribs extending inwards into the rim 21, the rotor rim 21 is not weakened, thus using 100% of its radial strength.

(15) Thus, pole fixation on the rotor rim 21 is done through axial pins. In order to have perfect contact among the adjacent surfaces or pole and rotor rim, different possibilities may be considered as variant to the base idea. One possible method of fixation is to ream the holes axially prior to introducing the fixation pins 27.

(16) According to another solution, expansion pins may be used, which eliminate the radial clearance of the interface holes.

(17) Depending on the pole design, the proposed new anchoring system might penetrate more or less inside the pole core of salient pole 22 and have a significant area under the area of pole winding 23. In this case one additional variant is to split the fixation pin 27 in two, preferably with crocodile tapered shape interface.

(18) After sliding the salient pole 22 radially inwards over the rotor rim 21, the split pins shall be rotated and then axially driven to be locked one against each other.

(19) Another variant within the present invention is that the pole fixation can be either normal to rim interface surface (cylindrical surface 28) or with trapezoidal shape, whereby the angle will facilitate the dismantling and removal of the pole 22.

(20) The number of fixation pins 27 and their position in the pole-rim interface 24 is determined by mechanical dimensioning, i.e. the fixation pins 27 are not necessarily equally distributed along the interface surface of the poles to the rim. The same applies to the size of the pins, which does not need to be the same on each interface point.

(21) The present invention has various advantages: For machines, where the efficiency is not a key issue, the benefit can be optimized. Preliminary analysis indicates that a lighter machine may be realized with same or better performance. Furthermore, critical speed can be increased. Another plus of this solution is that less raw material is used for the poles since they do not need an extension called “pole claws”. Another advantage is to have large radius in the contact area, thus optimizing the stress concentration and, consequently, the fatigue lifetime of the pole. An advantage of the use of shear pins is that they will help to transmit load in the rotor rim, together with the rim bolts; thus the rim can be even more optimized due to this new functionality. Since in this solution there is no need to slide a pole claw through the rim, one additional advantage will be to reduce erection clearance between pole and rim, which is strongly beneficial to the magnetic circuit, because it reduces reluctance of the magnetic path. The pole can be removed axially without removing the rotor from inside the machine or generator stator. As there are no ribs extending inwards into the rim, the rotor rim is not weakened, thus using 100% of its radial strength. It is within the scope of the invention to cool the machine through different ways, e.g. with radial ventilation cooling through the rotor rim, or with axial cooling (promoted with help of blades/fan pumping air axially through the machine rotor poles and stator).

LIST OF REFERENCE NUMERALS

(22) 10, 21 rotor rim 11 plate segment 12 cooling slit 13 strip (wedge carrier) 14 wedge 15 slot 16 pole claw 17 rotor pole 18 pole winding 19 pole gap 20 rotor (salient pole machine) 22 salient pole 23 pole winding 24 pole-rim interface 25 rim extension (rib-like) 26 pole groove 27 fixation pin (axial) 28 cylindrical surface 29 outer radius (rim) 30 salient pole machine