Laminated rotor machining enhancement
A laminated rotor for an electric machine is disclosed. In an embodiment, the rotor comprises a plurality of stacked laminations. Each lamination includes a plurality of radially extending slots arranged about a circumference thereof, and a first chamfer on a surface of each of the slots, wherein the surface mates with a wedge. The first chamfer connects the surface and a first face of the lamination. A stud member passes longitudinally through a hole in the lamination stack, a first end flange member on a first end of the lamination stack, and a second end flange member on a second end of the lamination stack. A first fastener is affixed to a first end of each of the at least one stud member; and a second fastener affixed to a second end of each of the at least one stud member.
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The subject matter disclosed herein relates generally to a rotor structure of an electric machine such as a generator. More particularly, the invention relates to an electric machine having a laminated rotor structure including chamfers on the laminations to reduce smearing.
Generators typically include a stator and a rotor, the rotor rotating about a longitudinal axis within the stator to convert mechanical energy into electrical energy. The stator typically includes windings from which electrical power is output.
The rotor includes radially cut slots about the circumference of the rotor body, which extend lengthwise along the rotor body. These slots contain the coils which form the rotor field windings for carrying current. The rotor field windings are supported in place against centrifugal forces by using one of a number of different systems including, e.g., coil wedges which bear against the slot surfaces. The regions of the coils which extend beyond the ends of the rotor body are referred to as end windings, and are supported against centrifugal forces by retaining rings. The portion of the rotor shaft forging which is located under the rotor end windings is referred to as the spindle.
Rotors may be formed from a solid single forging of high strength iron or steel, which provide the rotor with the required bending stiffness to support the rotor both statically and to transmit torque from the rotor to a drive flange of the generator for successful operation of a large, high speed generator. These solid single-forging rotors are expensive to produce, and limited production capacity may result in long lead times for ordering and manufacture.
Laminated rotor bodies have been used in some electric machines such as generators and motors to alleviate the expense and lead time associated with solid steel rotors. These laminated rotor bodies comprise laminations placed on, or attached to, a single steel shaft, such that the shaft provides the required bending stiffness for the rotor. Laminated rotor bodies have also been used in electric machines in which the stack of laminations is held in compression by a series of rods that pass through holes in the periphery of the laminations.
After assembly of a laminated rotor, surfaces that serve as mechanical load transfer interfaces typically need machining to avoid stress concentration, and likelihood of resultant failure. Additional machining may be needed to form and/or shape mating surfaces between the rotor and wedges which hold the windings in place. Further, the assembled rotor may have excessive radial runout, which may require machining of the outer diameter of the rotor body to reduce to an acceptable level. The machining that the rotor may undergo following assembly may result in smearing, or electrical contact between laminations, across insulation layers between laminations.
BRIEF DESCRIPTION OF THE INVENTIONA first aspect of the disclosure provides a rotor comprising a lamination stack including a plurality of stacked laminations. Each lamination has a first thickness, and includes a plurality of radially extending slots arranged about a circumference of each of the plurality of laminations, and a first chamfer on a surface of each of the plurality of radially extending slots, wherein the surface mates with a wedge, and wherein the chamfer connects the surface and a first face of the lamination. At least one stud member passes longitudinally through at least one hole in the lamination stack, a first end flange member on a first end of the lamination stack, and a second end flange member on a second end of the lamination stack. A first fastener is affixed to a first end of each of the at least one stud member; and a second fastener is affixed to a second end of each of the at least one stud member. The first fastener and the second fastener provide compression to the laminated stack. A plurality of coils are positioned within the plurality of slots.
A second aspect of the disclosure provides an electric machine comprising a rotor and a stator surrounding the rotor. The rotor includes a lamination stack including a plurality of stacked laminations. Each lamination has a first thickness, and includes a plurality of radially extending slots arranged about a circumference thereof, and a first chamfer on a surface of each of the plurality of radially extending slots, wherein the surface mates with a wedge, and wherein the chamfer connects the surface and a first face of the lamination. At least one stud member passes longitudinally through at least one hole in the lamination stack, a first end flange member on a first end of the lamination stack, and a second end flange member on a second end of the lamination stack. A first fastener is affixed to a first end of each of the at least one stud member; and a second fastener is affixed to a second end of each of the at least one stud member. The first fastener and the second fastener provide compression to the laminated stack. A plurality of coils are positioned within the plurality of slots.
A third aspect of the disclosure provides a lamination for forming a rotor body comprising: a plurality of radially extending slots arranged about a circumference of the lamination; a first chamfer on a surface of each of the plurality of radially extending slots, wherein the surface mates with a rotor wedge, and wherein the chamfer connects the surface and a first face of the lamination; and at least one hole in the lamination for a stud member to pass through.
These and other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawings, where like parts are designated by like reference characters throughout the drawings, disclose embodiments of the invention.
At least one embodiment of the present invention is described below in reference to its application in connection with the operation of an electric machine. Although embodiments of the invention are illustrated relative to an electric machine in the form of a generator, it is understood that the teachings are equally applicable to other electric machines including, but not limited to, motors. Further, at least one embodiment of the present invention is described below in reference to a nominal size and including a set of nominal dimensions. However, it should be apparent to those skilled in the art that the present invention is likewise applicable to any suitable generator and/or motor. Further, it should be apparent to those skilled in the art that the present invention is likewise applicable to various scales of the nominal size and/or nominal dimensions.
As indicated above, aspects of the invention provide a laminated rotor body.
Rotor body 300 further includes a plurality of slots 140 which contain coils 130, forming the rotor field winding. As shown in
Drive coupling 340, shown in
Referring back to
In an embodiment, lamination stack 410 and first and second end flange members 420 and 425 may further be flanked by a first spacer member 430 located adjacent to the first end flange member 420, and a second spacer member 435 located adjacent to the second end flange member 425. As shown in
Referring back to
As shown in
Tightening of fasteners 445, 450 results in compression of laminated stack 410 at a pressure sufficient to provide the necessary bending stiffness to rotor body 300 and sufficient frictional capability to transmit a torque load from rotor body 300 to a drive shaft. The pressure necessary to accomplish this varies with the size of generator 200, and consequently, with the size of rotor 120. Larger machines require increased rotor stiffness, approaching that of a solid steel rotor. The pressures achieved are highly dependent on a variety of variables including but not limited to: the size of the rotor, the materials from which it is made, the extent to which fasteners 445, 450 are tightened, and so on.
As shown in
As shown in
As further shown in
Referring to
In a further embodiment, depicted in
In a further embodiment, depicted in
Also provided is a method for forming a rotor body 300 in accordance with embodiments of the invention. A rotor body 300 is assembled, including assembling a stack 410 of a plurality of laminations 415, and inserting a stud member 440 through a hole 510 in each of the plurality of laminations 415. Each of the plurality of laminations 415 includes a plurality of radially extending slots 140 arranged about a circumference of each of the plurality of laminations 415. When assembled into stack 410, laminations 415 are positioned such that slots 140 in successive laminations 415 in the stack 410 are aligned. Each of the plurality of laminations 415 may further include a first chamfer 520 on a face of each of the laminations 415, or a first chamfer 540 on both faces of each of the laminations 415. In some embodiments, first chamfer 520 may be filled with an insulating material 530, which may be an epoxy. In further embodiments, second chamfers 521, 522 may be provided at the outer diameter of each lamination 415, which may be single- or double-sided.
A number of surfaces of the assembled rotor body 300 may be machined, for a variety of purposes, including, e.g., surface 550 of lamination 415, at the interface between wedge 150 and lamination 415 (see
As used herein, the terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). The suffix “(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the metal(s) includes one or more metals). Ranges disclosed herein are inclusive and independently combinable (e.g., ranges of “up to about 25 mm, or, more specifically, about 5 mm to about 20 mm,” is inclusive of the endpoints and all intermediate values of the ranges of “about 5 mm to about 25 mm,” etc.).
While various embodiments are described herein, it will be appreciated from the specification that various combinations of elements, variations or improvements therein may be made by those skilled in the art, and are within the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims
1. A rotor comprising:
- a lamination stack including a plurality of stacked laminations, wherein each lamination includes: a first face; a second, opposing face; and a circumferential surface; a plurality of radially extending slots arranged about a circumference of each of the plurality of laminations, each slot including a radially inward-facing surface configured to mate with a wedge, and a first chamfer on the radially inward-facing surface of each of the plurality of radially extending slots, wherein the first chamfer connects the radially inward-facing surface and the first face of the lamination;
- a stud member passing longitudinally through at least one hole in the lamination stack, a first end flange member on a first end of the lamination stack, and a second end flange member on a second end of the lamination stack;
- a first fastener affixed to a first axial end of the stud member;
- a second fastener affixed to a second axial end of the stud member;
- the first fastener and the second fastener providing a compression to the laminated stack; and
- a plurality of coils positioned within the plurality of slots.
2. The rotor of claim 1, wherein the first chamfer is filled with an insulating material.
3. The rotor of claim 2, wherein the insulating material comprises an epoxy.
4. The rotor of claim 1, wherein the first chamfer further comprises a double-sided chamfer, wherein the double-sided chamfer includes an angled chamfer surface connecting the radially inward-facing surface with the first face of the lamination, and an angled chamfer surface connecting the radially inward-facing surface with the second, opposing face of the lamination.
5. The rotor of claim 1, wherein each of the plurality of laminations is coated with an insulating coating.
6. The rotor of claim 1, further comprising a second chamfer connecting the first face of the lamination with the circumferential surface of the lamination.
7. The rotor of claim 6, wherein the second chamfer further comprises a double sided chamfer, wherein the double-sided chamfer includes an angled chamfer surface that connects the circumferential surface with the first face of the lamination and an angled chamfer surface connecting the circumferential surface with the second, opposing face of the lamination.
8. An electric machine comprising:
- a rotor including:
- a lamination stack including a plurality of stacked laminations, wherein each lamination includes: a first face; a second, opposing face; and a circumferential surface; a plurality of radially extending slots arranged about a circumference thereof, each slot including a radially inward-facing surface configured to mate with a wedge, and a first chamfer on the radially inward-facing surface of each of the plurality of radially extending slots, wherein the first chamfer connects the radially inward-facing surface and the first face of the lamination;
- a stud member passing longitudinally through at least one hole in the lamination stack, a first end flange member on a first end of the lamination stack, and a second end flange member on a second end of the lamination stack;
- a first fastener affixed to a first axial end of the stud member;
- a second fastener affixed to a second axial end of the stud member;
- the first fastener and the second fastener providing a compression to the laminated stack;
- a plurality of coils positioned within the plurality of slots; and
- a stator surrounding the rotor.
9. The electric machine of claim 8, wherein the first chamfer is filled with an insulating material.
10. The electric machine of claim 9, wherein the insulating material comprises an epoxy.
11. The electric machine of claim 8, wherein the first chamfer further comprises a double-sided chamfer, wherein the double-sided chamfer includes an angled chamfer surface connecting the radially inward-facing surface with the first face of the lamination, and an angled chamfer surface connecting the radially inward-facing surface with the second, opposing face of the lamination.
12. The electric machine of claim 8, wherein each of the plurality of laminations is about 0.95 cm thick.
13. The electric machine of claim 8, wherein each of the plurality of laminations is coated with an insulating coating.
14. The electric machine of claim 8, further comprising a second chamfer connecting the first face of the lamination with the circumferential surface of the lamination.
15. The electric machine of claim 14, wherein the second chamfer further comprises a double sided chamfer, wherein the double-sided chamfer includes an angled chamfer surface that connects the circumferential surface with the first face of the lamination and an angled chamfer surface connecting the circumferential surface with the second, opposing face of the lamination.
16. A lamination for forming a rotor body comprising:
- a first face; a second, opposing face; and a circumferential surface;
- a plurality of radially extending slots arranged about a circumference of the lamination, each slot including a radially inward-facing surface configured to mate with a wedge;
- a first chamfer on the radially inward-facing surface of each of the plurality of radially extending slots, wherein the first chamfer connects the radially inward-facing surface and the first face of the lamination;
- at least one hole in the lamination for a stud member to pass through.
17. The lamination of claim 16, wherein the first chamfer further comprises a double-sided chamfer, wherein the double-sided chamfer includes an angled chamfer surface connecting the radially inward-facing surface with the first face of the lamination, and an angled chamfer surface connecting the radially inward-facing surface with the second, opposing face of the lamination.
18. The lamination of claim 16, wherein the lamination is coated with an insulating coating.
19. The lamination of claim 16, further comprising a second chamfer connecting the first face of the lamination with the circumferential surface of the lamination.
20. The lamination of claim 16, wherein the second chamfer further comprises a double sided chamfer, wherein the double-sided chamfer includes an angled chamfer surface that connects the circumferential surface with the first face of the lamination and an angled chamfer surface connecting the circumferential surface with the second, opposing face of the lamination.
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Type: Grant
Filed: Jul 6, 2011
Date of Patent: Oct 6, 2015
Patent Publication Number: 20140232234
Assignee: General Electric Company (Schenectady, NY)
Inventors: Dmitry Yurevich Semenov (Moscow), Anthony Salvatore Arrao (Clifton Park, NY), Richard Nils Dawson (Voorheesville, NY), Evgeny Victorovich Kazmin (Moscow), Timothy Gerald Schmehl (Clifton Park, NY), Yury Danilovich Vinitsky (Moscow)
Primary Examiner: Tran Nguyen
Application Number: 13/823,054
International Classification: H02K 1/26 (20060101); H02K 1/28 (20060101); H02K 1/16 (20060101); H02K 3/487 (20060101); H02K 15/02 (20060101);