Patent ID: 12218569

DETAILED DESCRIPTION

FIG.1shows a cross-sectional view of a set of lamination sheets1,2for forming a lamination stack of a corresponding stator segment according to the conventional art discussed in the introductory portion of this document. The lamination sheets1,2have an arc-like shape and can be combined with further lamination sheets to form a lamination stack. As shown, the left lamination sheet1is shorter than the right lamination sheet. This size difference allows stacking of the sheets like bricks in a wall, i.e., such that the sheets overlap each other. In other words, the next layer of sheets to be stacked on top of the sheets1,2shown inFIG.1would be arranged with the longer sheet to the left and the shorter sheet to the right. The resulting stator segment can then be combined with further segments to form an annular stator structure. Each lamination sheet1,2comprises a plurality of teeth3extending from yoke4. To form an electric machine, such as a wind turbine generator, windings are arranged between the teeth such that electrical currents are induced therein when a magnetic rotor (not shown) is moved relative to the stator. Furthermore, connection structures5extend from the side of the yoke4that is opposite from the teeth3, i.e., the lower side of yoke4in the drawing. Each connection structure5comprises a recess or hollow portion6formed to engage with a fastening member (not shown, discussed further below) in order to secure the resulting lamination stack of lamination sheets1,2to a support structure (not shown, discussed further below) of a corresponding stator segment. As can be seen, the connection structures5extend away from the yoke4and thus adds to the radial width of the lamination sheets1,2. As mentioned in the introduction, forming of the connection structures5by stamping the lamination sheets1,2results in a considerable amount of scrap material and thus also adds to the production costs. The connection structures5are evenly distributed along arc-shaped yokes4.

FIG.2shows a cross-sectional view of a set of lamination sheets21,22for forming a lamination stack of a stator segment according to an embodiment of the present invention. While the overall structure is similar to that shown inFIG.1, the lamination sheets21,22differ in that the recesses26of the connection structures25extend partially within the yokes24. Accordingly, the connection structures25does not extend as far out from the yokes24as in the structure shown inFIG.1. Thus, the radial size of the lamination sheets21,22(and thereby the radial size of the resulting lamination stack) as well as the resulting amount of scrap material is comparatively reduced. Furthermore, in the embodiment shown inFIG.2, each connection structure25is positioned directly behind (i.e., opposite to) one of the teeth23, as indicated by lines27. Thereby, the reduced amount of yoke material caused by the recesses26does not significantly influence the magnetic and electric properties of the yoke24.

FIG.3shows a close-up view of a part ofFIG.2and clearly shows that about one-third of the recess36extends within the yoke34, i.e., above the dashed line37.

FIG.4shows a cross-sectional view of a stator segment41according to an embodiment of the present invention. The stator segment41comprises a support structure42on which a lamination stack with yoke43and teeth44is fastened by fastening members45. Windings46are arranged between the teeth44.

FIG.5shows a close-up view of a part ofFIG.4. Here, it can be seen how a rod-shaped fastening member45is arranged within a recess and partially extends within the yoke43as indicated by the dashed line48. The recess and the fastening member45forms a dovetail connection and the rod45is secured to the support structure42by bolts47.

FIG.6shows a perspective view of a support structure60in accordance with an embodiment of the present invention. As shown, the support structure comprises an arc-shaped frame having several connection structures61and62for engaging respectively with a fastening member (seeFIG.8) and corresponding connection structures of neighboring stator segments. The elongate connection structures61each comprises a number of holes allowing bolt connections with a rod-shaped fastening member45as shown inFIG.5and discussed above.

FIG.7shows a perspective view of a lamination stack70in accordance with an embodiment of the present invention. The lamination stack70comprises a plurality of packets71arranged with a small gap between them. Each packet71comprises laminated iron material with a cross-sectional shape corresponding to the shapes shown e.g., inFIG.2and discussed above. Similar to the structures shown inFIGS.2to5, the lamination stack70comprises connection structures72for securing the lamination stack70to a support structure using a fastening member as discussed above.

FIG.8shows a perspective view of a rod-shaped fastening member80in accordance with an embodiment of the present invention. The fastening member80comprises holes81for receiving bolt as shown e.g., inFIG.5and discussed above in order to secure a lamination stack to a support structure. The fastening member has an end82and comprises a cross-sectional shape (in this embodiment a half-moon shape) that fits into a corresponding recess (e.g.,26or36) to form a dovetail joint.

FIG.9shows a perspective view of a stator segment90in accordance with an embodiment of the present invention. More specifically, the stator segment comprises a support structure60as shown inFIG.6, a lamination stack70as shown inFIG.7, and a fastening member80as shown inFIG.8.

Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.