Rotating electric machine part fixing device

Abstract

The present disclosure relates to a rotating electrical machine component fixture, and in particular, to a fixture for forming a component of a rotating electrical machine, comprising: a body defining a cavity, having a closed end, configured to receive a stack of metal plates forming a rotor or stator; an end cap assembly removably coupled to the open end of the cavity, having at least one spring applying a force in an axial direction toward the closed end of the body; and an induction heating system having an induction loop that receives current from a power source and heats the metal plate.

Description

Technical Field

[0001] The present application relates to rotating electrical machines and, more particularly, to the manufacture of components included in electrical machines. Background Art

[0002] A rotating electrical machine (sometimes referred to as an electric motor) typically includes a stator having stator windings that receive an electric current and a rotor that is angularly displaced relative to the stator in response to the electric current. The stator and rotor can be formed in a variety of different ways. For example, the stator and / or rotor can be an assembly of multiple thin steel plates stacked along an axis and bonded together to form an integral structure. However, the assembly of the plates can involve several challenges. Alignment of the plates and bonding the plates together can involve long periods of time. It would be useful to improve the speed and accuracy with which the stator / rotor assembly is formed. Summary of the invention

[0003] In one embodiment, a fixture for forming a component of a rotating electrical machine includes: a body defining a cavity having a closed end configured to receive a stack of metal plates forming a rotor or stator; an end cap assembly removably coupled to an open end of the cavity having at least one spring applying a force in an axial direction toward the closed end of the body; and an induction heating system having an induction loop that receives current from a power source and heats the metal plates.

[0004] In another embodiment, a fixture for forming a component of a rotating electric machine includes: a body defining a cavity configured to receive a stack of metal plates forming a rotor or stator; a closed end coupled to one end of the cavity; an end cap assembly removably coupled to an opposite end of the cavity, having a plurality of springs carried by an adjustable stud, the plurality of springs applying a force in an axial direction toward the closed end of the body; and an induction heating system having an induction loop that receives current from a power source and heats the metal plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a perspective view illustrating an embodiment of a rotating electric machine component fixing device;

[0006] Figure 2 is a cross-sectional view illustrating an embodiment of a rotating electric machine component fixing device; and

[0007] Figure 3 is an exploded view illustrating a portion of an embodiment of a rotating electric machine component securing device. DETAILED DESCRIPTION

[0008] A rotating electrical machine fixture comprises a cavity for releasably receiving a plurality of thin plates, an induction heating system and an axial force, which together form a rotor or stator assembly from the plates. A rotating electrical machine or motor typically comprises a rotor and / or a stator, which is formed by a stack of thin metal plates having holes and / or outer boundaries that together define the shape of the rotor / stator. The plates may include an electrically insulating adhesive layer applied to the surface. In the past, stacks of axially extending plates including an adhesive layer were placed in a convection oven, heated for a long time to activate the adhesive, and ultimately removed from the oven as an integral structure. However, the curing time of the plates in the convection oven may be several hours, which hinders the large-scale production of rotating electrical machine components.

[0009] After assembling the stack of metal sheets on the mandrel, the rotating electric machine fixture can receive the stack of plates in a cavity closed at one end. The end cap assembly can be releasably attached to the other end of the fixture to enclose the stack of metal sheets in the cavity during the curing process. The end cap assembly can include one or more biasing elements (springs) that compress the stack of plates between the closed end of the fixture and the end cap assembly when the assembly is fixed to one end of the fixture. The springs can be adjusted individually to adjust the magnitude and position of the force applied axially to the stack of plates. The induction heating system can be included by the wall of the fixture radially outward from the stack of plates. The system can include at least one induction coil positioned adjacent to or within the wall of the fixture. The control system can adjust the alternating current (AC) applied to the induction coil to induce eddy currents in the metal sheets of the stack. Unlike the convection furnace method that relies on slowly conducting heat inward via the atmosphere around the surface of the stack, the induction coil heats the stack of metal sheets from within the rotor / stator itself, thereby improving the uniformity and speed of the rotor / stator curing. The stack of plates can be cured in minutes rather than hours. Once cured into an integral component of the rotating electrical machine, the end cap assembly can be disengaged from the fixture in a manner that releases the applied axial pressure and the rotor / stator can be removed from the open end of the fixture.

[0010] The embodiment of the rotating electrical machine fixing device 10 is Figure 1 The fixture 10 includes an interior cavity 12, a closed end 14, and an end cap assembly 16 that selectively encloses a stack 18 of thin metal sheets that ultimately form a rotor or stator within the interior cavity 12. The end cap assembly 16 includes one or more springs 20 that adjustably apply a force to a radial surface 22 of the stack 18 toward the closed end 14.

[0011] The fixture 10 may include a body 24 extending between the closed end 14 and the end cap assembly 16. The body 24 may be generally tubular in shape, with a cylindrical cavity 12. The body 24 may be formed of metal and have a thickness sized to enclose an induction heating system 28. In this embodiment, the induction heating system 28 may be enclosed within a wall 30 of the body 24. However, it should be understood that in other embodiments, the induction heating system may be positioned adjacent to the outer surface of the body 24. The body 24 may include a threaded receptacle 32 that may receive a threaded fastener 34 (such as a bolt) that couples the closed end 14 and the end cap assembly 16 to the fixture 10. In this embodiment, the closed end 14 may be an element that is separate from the body 24 and coupled to the body 24 via the threaded fastener 32. However, other embodiments in which the closed end is integral with the body are also possible. The closed end 14 may include a groove 36 formed in the outer surface. The groove 36 may cooperate with a base 38 that orients the fixture 10 vertically. The closed end 14 may include a hole 40 for receiving one end of a mandrel 42 that holds and positions the stack of plates 18 when the stack of plates 18 is in the cavity 12. The closed end 14 may be formed of an inductive and electrically conductive material such that the induction heating system 28 heats the closed end 14. In one embodiment, the closed end 14 is formed of a ferrous material such as steel.

[0012] The end cap assembly 16 is releasably coupled to an end of the body 24 remote from the closed end 14. The assembly 16 includes a back plate 46, a pressure plate 48, and a plurality of springs 20 located between the plates 46, 48. Each spring 20 may be carried by an adjustable stud 52 that changes the amount of force applied by the pressure plate 48 on the stack 18 of metal plates that will become the rotor or stator. The stud 52 passes through a hole 54 in the back plate 46 and the center of the spring 20 to engage a threaded hole 56 in the pressure plate 48. Tightening or loosening the stud 52 relative to the pressure plate 48 may change the length of the stud 52 and the distance between the back plate 46 and the pressure plate 48. Increasing / decreasing the distance between the plates 46, 48 may also increase or decrease the amount of force applied by the end cap assembly 16 on the stack 18 of plates. Each spring 20 may be adjusted individually and independently of the other springs 20. This may help manage the formation of various features of the stack 18, such as stator slots or the back iron of the stator. The spring 20 may be implemented as a coil spring, but other elastic elements or force generating elements are possible. The term "spring" as used in the claims is intended to be interpreted broadly so that it includes elements other than springs and may be used interchangeably with the term "force generating element." A central hole 40 may be included in the end cap assembly 16 to receive the other end of a mandrel 42 that holds the stack of metal sheets 18, thereby positioning the stack within the cavity 28.

[0013] In this embodiment, the end cap assembly 16 includes a pivot 60 that enables the assembly 16 to be pivotally moved to open and close the cavity 12, thereby facilitating the introduction and removal of the stack of plates 18. When open, the end cap assembly 16 rotates about the pivot 60 to open the cavity 12 at one end, and when closed, the end cap assembly 16 rotates about the pivot 60 to close the cavity 12. In the closed position, the end cap assembly 16 can be coupled to the body 24 using a threaded fastener 62 received by a threaded receptacle 64 in the body 24. When the end cap assembly 16 is in the closed position, the pressure plate 48 of the end cap assembly 16 can abut the stack of metal plates 18 and apply a defined amount of axial pressure on the stack of metal plates 18. The stack of metal plates 18 can be compressed between the pressure plate 48 and the closed end 14. The end cap assembly 16 can be formed of an inductive and conductive material so that the induction heating system 28 heats the assembly 16. In one embodiment, the closed end 14 is formed of a ferrous material such as magnetic steel. Generally speaking, the top and bottom of the fixture directly abut the stack of metal plates 18 and may contain magnetic steel. However, other parts of the fixture are generally not magnetic and therefore will not be heated in response to the flow of current through the induction coil.

[0014] The stack 18 may include a plurality of metal plates 66 arranged axially on the mandrel 42 so that the surfaces of the plates abut against each other. Each plate may include an adhesive coating 68 on each side. The plates 66 may be stacked in unison so that the adhesive coatings 68 abut against each other. The insulating coating 68 may be electrically insulating and optionally thermally insulating. The adhesive coating 68 may be implemented as any of a variety of heat-activated adhesives. In one embodiment, the adhesive coating 68 may be an epoxy resin pre-impregnated with a heat-activated resin that hardens above a specific temperature. The mandrel 42 may be a cylindrical rod that can be radially moved or tapered so that it can releasably hold the metal plates 66 using the inner diameter of the stack as a contact point. The metal plates 66 may be stamped from a ferrous material such as steel and have an outer diameter 72 and an inner diameter 74. A hole may be formed between the outer diameter and the inner diameter so that when the plates 66 are stacked axially, adjacent holes may form cooling channels that enable fluid to flow through the rotor / stator. The shape of the outer or inner diameter of the plate 66 can be controlled to form features of the rotor or stator, such as stator slots or voids that can receive rotor magnets. In one embodiment, a stack of 500 metal plates, each plate having a thickness of 1.0 millimeter (mm), can be stacked axially on the mandrel so that the adhesive and insulating coatings abut and prevent the plates from moving relative to the mandrel. One end of the mandrel 42 can be received by the hole 40 in the closed end 14, the other end of the mandrel 42 can be received by the central hole 40 in the end cap assembly 16, and the end cap assembly 16 can be coupled to the body 24.

[0015] The induction heating system 28 may include an induction coil 76 that receives AC current from a power source such as an electrical grid (not shown). The induction coil 76 may include one or more wires surrounding a cavity that are electrically connected to the electrical grid. The cross-sectional size and number of turns of the wire are variable and may be selected based on a variety of factors. A control system (not shown) including one or more switches may selectively allow current to flow through the induction coil 76 to generate a magnetic field and induce eddy currents in each metal plate 66 of the stack 18. The current may be single-phase or three-phase AC. The flow of current through the induction coil 76 may heat each metal plate 66 within the stack by induced eddy currents. In addition to the heating plates 66, the induction heating system 28 may also induce heat in the closed end 14 and the end cap assembly 16, thereby applying heat to the radial surface of the rotor or stator. In one embodiment, the amount of time from the initial current flowing through the induction coil until the rotor or stator solidifies is less than five minutes, and the fixture reaches a temperature somewhere between 220°C and 260°C.

[0016] It should be understood that the foregoing is a description of one or more embodiments of the present invention. The present invention is not limited to the specific embodiments disclosed herein, but is limited only by the appended claims. In addition, the statements contained in the foregoing description relate to specific embodiments and should not be interpreted as limitations on the scope of the present invention or the term definitions used in the claims, unless a term or phrase is clearly defined above. Various other embodiments and various changes and modifications to the disclosed embodiments will become apparent to those skilled in the art. All of these other embodiments, changes and modifications are intended to fall within the scope of the appended claims.

[0017] As used in this specification and claims, the terms "for example," "for example," and "such as," and the verbs "include," "have," "comprise," and their other forms, when used in conjunction with a list of one or more components or other items, should be interpreted as open-ended, meaning that the list should not be considered to exclude other additional components or items. Other terms should be interpreted using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.

Claims

1. A fixture for forming a component of a rotating electrical machine, comprising: a body defining a cavity having a closed end configured to receive a stack of metal plates forming a rotor or a stator; an end cap assembly removably coupled to the open end of the cavity having at least one spring applying a force in an axial direction toward the closed end of the body; as well as An induction heating system has an induction loop that receives current from a power source and heats the metal plate.

2. The fixture of claim 1 wherein the stack of metal sheets is carried by a mandrel engaged with the closed end. 3 . The fastening device of claim 1 , wherein the stack of metal sheets comprises metal sheets having an adhesive coating on each side of the metal sheets. 4 . The fixture of claim 1 , wherein the stack of metal plates includes a hole between an inner diameter of the metal plates and an outer diameter of the metal plates.

5. The fixture of claim 1, wherein the stack of metal sheets includes an adhesive coating comprising an epoxy resin.

6. The fixture of claim 1, further comprising one or more adjustable studs that control the amount of force applied by the spring.

7. The fixture of claim 1, further comprising a groove formed in an outer surface of the fixture, the groove configured to engage a base that vertically holds the fixture.

8. The fixture of claim 1, further comprising a pivot connecting the end cap assembly to the body.

9. A fixture for forming a component of a rotating electrical machine, comprising: a body defining a cavity configured to receive a stack of metal plates forming a rotor or a stator; a closed end coupled to one end of the cavity; an end cap assembly removably coupled to an opposite end of the cavity having a plurality of springs carried by an adjustable stud, the plurality of springs applying a force in an axial direction toward the closed end of the body; as well as An induction heating system has an induction loop that receives current from a power source and heats the metal plate.

10. The fixture of claim 9, wherein the stack of metal sheets is carried by a mandrel engaged with the closed end.

11. The fastening device of claim 9, wherein the stack of metal sheets comprises metal sheets having an adhesive coating on each side of the metal sheets.

12. The fixture of claim 9, wherein the stack of metal plates includes a hole between an inner diameter of the metal plates and an outer diameter of the metal plates.

13. The fixture of claim 9, wherein the stack of metal sheets includes an adhesive coating comprising an epoxy resin.

14. The fixture of claim 9, further comprising a groove formed in an outer surface of the fixture, the groove configured to engage a base that vertically holds the fixture.

15. The fixture of claim 9, further comprising a pivot connecting the end cap assembly to the body.

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