Core for dynamoelectric machines

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Drawing sheet — no readable text.

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United States Patent Office 3,221,195 Patented Nov. 30, 1965

FIG. 6 is a front view of an alternate set of lamina 3,221,195 tions with the secondary and tertiary laminations super

CORE FOR DYNAMOELECTRIC MACHINES

Jack H. Hoffmann, West Allis, Wis., assignor to Allis imposed on a primary lamination. Chalmers Manufacturing Company, a corporation of Referring more specifically to the drawings by char Milwaukee, Wis. - acters of reference this invention is illustrated in a Filed Nov. 24, 1961, Ser. No. 154,641 stator core 10 for a large turbo-generator. The core 10 5 Claims. (C. 310-179) is made up of a series of stacked lamination rings 11a, 11b, 11c that are clamped together in the usual manner.

This invention relates generally to dynamoelectric ma Each ring 11 is made up of a set of independent sections chines. More specifically this invention relates to cores 10 which are arranged to form an annular ring. of large turbo-generators. In the primary lamination rings each section or in In the cores of large turbo-generators, which are made dividual lamination 15 is somewhat trapezoidal in shape up of numerous iron laminations, there is usually a and has a series of slots 16 formed in its radially inner build-up of material in some parts of the core causing an portion and grooves 17 in its outer portion for receiving unequal overall length of the core. This build-up of ma 5 dovetailed projections from the yoke. The inner slots terial is due to uneven coatings of varnish on the lamina are aligned with the slots of other laminations in the core tions and more particularly to burrs and other irregulari and form a receptacle for the electrical windings of the ties in the laminations caused by the shearing action in machine which are positioned in the slots 16 after the forming winding slots in the laminations. When these core has been formed. The grooves 17 in the outer por cores are completely assembled they are seasoned by 20 tions are used for aligning the laminations and mounting heating and compressing them. This removes a large them in the outer casing or yoke 21 of the generator. portion of the irregularities in the individual lamina The core 10 of this invention is made up of principally tions but the remaining irregularities frequently cause the the primary laminations 15 described above but has in core to have a significant differential length between its terspersed throughout the core some sets of secondary inner and outer portions. 25 laminations 25 having a shorter radial length. These lam In actual practice there has been as much as 34 inch inations 25 are illustrated in FIG. 3 and have a radial length differential between the inner and outer portions length which is less than the distance between the outer of the core having an overall length of less than 90 edge of the primary lamination 15 and the bottom of the inches. This difference in length makes it an extremely slots 16 at the radial inner portion of the lamination. difficult job to securely clamp the laminations firmly to 30 The reason for this particular length is that the maximum gether. Because the laminations are not firmly clamped amount of lamination build-up is in the area of the together they tend to vibrate during operation creating teeth 23 forming the slots 16 where during the shearing an excessive amount of noise. These vibrations of the operation in forming these laminations there is formed laminations further loosen the core thereby increasing a large number of burrs and other irregularities in the the amplitude of vibration of the individual laminations laminations which are not compressed into the plane of which results in greater noise and disturbance. This the laminations during assembly. The secondary lamina chain reaction continues and often results in the core tions 25 when judiciously interspersed throughout the producing an unacceptable noise volume. length of the core, balance out the build-up due to the This invention overcomes the problems cited above lamination irregularities at the inner portion of the core by forming the core member from laminations having 40 and provide a finished core having a substantially uniform different radial lengths. By inserting shorter laminations overall length.

intermittently between the regular laminations, the over In some cores, especially the longer ones, it may be all length of the core can be made uniform. This makes desirable to intersperse in the core periodically a third the clamping of the core much easier and provides a group of laminations 30 having an even shorter radial firmer more compact core. This in turn reduces the 45 length than the secondary laminations. These shorter amount of vibration in the individual laminations thereby tertiary laminations 30 (shown in FIG. 4) provide an reducing the noise made by the generator during opera even more compact and uniform core when used in con tion. Furthermore, by having a more compact, firmly junction with the other two sets of laminations 15, 25. clamped core initially, it is much less likely that the core This is because the length of the core tends to decrease will loosen excessively during operation. 50 gradually from the top of the slots 16 to the outer edge Therefore, it is the object of this invention to provide of the core with the shortest portion of the core at the a new and improved core for dynamoelectric machines. extreme outer diameter. Hence, by inserting some sec Another object of this invention is to provide a new ondary laminations for adding length in the area from and improved core for dynamoelectric machines having the slots outward and using a few shorter tertiary lam a more uniform overall length. inations in the outer portion of the core only, the over Another object of this invention is to provide a new all length of the core is more uniform throughout. This and improved core for dynamoelectric machines that can provides a more compact core having fewer voids which be more easily and firmly clamped. in turn reduces the amount of vibration in the lamina Other objects and advantages of this invention will be tions. Furthermore, if only secondary laminations are apparent from the following description when read in 60 used to supplement the primary lamination, in some connection with the accompanying drawings, in which: cases the inner and outer lengths of the core would be FIG. 1 is a pictorial view with sections removed of a equal but the length at the middle of the core would be stator core having the laminations of this invention; greater. This of course could create some of the prob FIG. 2 is a front view of a primary lamination of this lems this invention is trying to solve. More than three invention; 65 different sizes of laminations can be used but in most FIG. 3 is a front view of a secondary lamination of this cases the additional benefits to be gained by so doing invention; would not be worth the added expense and effort. FIG. 4 is a front view of a tertiary lamination of this It is obvious that this overall length differential could invention; occur in cores made up of annular laminations 34 such FIG. 5 is a front view of a set of laminations of FIG. 70 as shown in FIG. 6. In such a core the secondary lam 2 arranged to form an annular lamination member for inations 36 are annular in shape rather than trapezoidal a dynamoelectric machine; and but again would have a radial length less than the dis

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tance between the outer edge and the bottom slots of lamination rings and being interspersed with said primary the primary laminations 34. The specific length of the lamination rings, tertiary laminations of substantially secondary laminations may vary in some cases but should trapezodal shape having a radial length less than the be sufficient to provide a core having a substantially uni radial length of said secondary laminations, said tertiary form overall length but without having too many spaces 5 laminations being combined to form annular lamination between laminations which will allow the laminations to rings interspersed with the other said amination rings, vibrate excessively during the operation of the machine. said laminations being clamped together to form a core A tertiary set of laminations 37 may also be used in Such for a dynamoelectric machine having a substantially uni a core if desired. form overall length.

In operation, the laminations are stacked in a shell 0. 3. A core for a dynamoelectric machine comprising: or yoke with grooves 7 engaging complementary dove a plurality of substantially trapezoidal shaped lamina tail bars 40 on the yoke. The core is made up of primary tions having slots at their inner end, said laminations laminations with secondary and/or tertiary laminations being combined to form annular lamination rings, said interspersed periodically throughout the core as needed lamination rings being aligned and stacked, secondary to provide the overall uniform length. In practice the laminations of Substantially trapezoidal shape having a ratio of primary laminations to secondary and/or ter radial length less than the distance between the outer tiary laminations varies but is usually between 75 to edge and the bottom of said slots in said primary lamina and 100 to 1. The core is stacked in a vertical position tions, Said secondary laminations being combined to form and a group of secondary laminations are occasionally annular lamination rings and being interspersed with said positioned on top of a group of primary laminations to primary lamination rings, said laminations being clamped make the surface of the core at that point level. By con together to form a core for a dynamoelectric machine hav tinually repeating this process throughout the building of ing a Substantially uniform overall length. the core, the core has an equal overall length and the 4. A core for a dynamoelectric machine comprising: secondary laminations are uniformly distributed through a plurality of Substantially trapezoidal shaped amina out the core. After the core has been stacked, the lam 2 5 tions having slots at their inner end, said laminations inations are clamped together and seasoned. Then the being combined to form annular lamination rings, said core is finally clamped and prepared ready to receive lamination rings being aligned and stacked, secondary electric conductors in the slot portions 16. laminations of substantially trapezoidal shape having a Although but two embodiments of this invention have radial length less than the distance between the outer been illustrated and described, it will be apparent to 30 edge and the bottom of Said slots in said primary amina those skilled in the art that various modifications and tions, said secondary laminations being combined to form changes can be made therein without departing from annular lamination rings and being interspersed with said the spirit of the invention or the scope of the appended primary lamination rings, tertiary laminations of substan claims. tially trapezoidal shape having a radial length less than Having now particularly described and ascertained the the radial length of said secondary laminations, said ter nature of my said invention and the manner in which tiary laminations being combined to form annular lam it is to be performed, I declare that what I claim is: ination rings interspersed with the other said lamina 1. A core for a dynamoelectric machine comprising: tion rings, said laminations being clamped together to a plurality of substantially trapezoidal shaped lamina form a core for a dynamoelectric machine having a tions, said laminations being combined to form annular 40 Substantially uniform overall length. lamination rings, said lamination rings being aligned and 5. A core for a dynamoelectric machine comprising: stacked, secondary laminations of Substantially trapezoidal a plurality of primary laminations stacked to form an shape having a shorter radial length than said primary annular core, a plurality of secondary laminations having laminations, said secondary laminations being combined varying radial lengths less than the radial length of said to form annular lamination rings and being interspersed core, said secondary laminations being interspersed with with said primary lamination rings, said laminations be Said primary laminations to form a core having a sub ing clamped together to form a core for a dynamoelectric stantially uniform overall length. machine having a substantially uniform overall length.

2. A core for a dynamoelectric machine comprising: References Cited by the Examiner a plurality of substantially trapezoidal shaped lamina 50 UNITED STATES PATENTS tions having slots at their inner end, said laminations 1,538,196 5/1925 Livingston -------- 310-216 X being combined to form annular lamination rings, said 1,816,795 7/1931 Pohl -------------- 310-256 lamination rings being aligned and stacked, secondary laminations of substantially trapezoidal shape having a shorter radial length than said primary laminations, said 55 ORIS L. RADER, Primary Examiner. secondary laminations being combined to form annular DAVID X. SLINEY, Examiner.