Methods of manufacturing a stator for an electric motor

Abstract

A method of manufacturing a stator for an electric motor includes forming a stator lamination wherein each stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, and wherein each stator lamination has a first free end and a second free end opposite the first free end. A plurality of the stator laminations are stacked to achieve a predetermined stator thickness and adhered together to define a stack of stator laminations having a thickness. The stack of stator laminations are rolled to achieve a circular shape, and the first free ends of the stator laminations are attached to the second free ends of the stator laminations, wherein as the stack of stator laminations is rolled, the thickness of the stack of stator laminations is not increased.

Description

Attorney Docket No. 64787-WO-PCTTITLEMETHODS OF MANUFACTURING A STATOR FOR AN EEECTRIC MOTORBACKGROUND OF THE INVENTION

[0001] This invention relates in general to methods of manufacturing a stator for an electric motor. In particular, this invention relates to improved methods of manufacturing such a stator from a plurality of stator laminations having hinge features that reduce or eliminate an increase in thickness that occurs during a bending or rolling process, wherein the increase in thickness is a result of axial deformation of the stator laminations in the region of the hinges.

[0002] Methods of constructing a round stator from a plurality of straight or linear sets of stator laminations is known. Various stator lamination hinge mechanisms are also known. In addition to what is shown in the prior art, such hinge mechanisms could be part of an end turn insulator. The challenge with this style of hinge is that they are either not very strong, and / or require a pin or similar device in the hinge joint.

[0003] It is desirable to automate the manufacture of a stator for use in an electric motor. One common way to do this is to start with a flat stator, install electrical insulation, wind the poles, and then roll a stack of linear stator laminations into a circular shape. During the rolling process, a thin hinge feature in the laminations allows segments of the stator laminations to form the circular shape.

[0004] The hinge feature often undergoes substantial plastic deformation during the rolling process. This deformation, plastic or elastic, causes some localized areas of the hinge to become thicker and other localized areas of the hinge to become thinner. When the localized portion becomes thicker, it causes the lamination stack to deform or spread apart in the axial direction. This may cause the height, or thickness, of the stack of stator laminations to increase, which may cause installation challenges for electrical insulation or electrical wires. For example, the axial deformation may cause fractures in theAttorney Docket No. 64787-WO-PCT electrical insulation on the stator laminations and undesirable extra tension in the electrical wires. While this localized thickness increase is small, it becomes significant when several hundred laminations are stacked together.

[0005] Thus, it would be desirable to provide an improved method of manufacturing a stator that includes an improved structure for a stator lamination that has stronger hinges, eliminates the need for additional pins or hinge joints, and eliminates the localized thickness increase in an assembled stator.SUMMARY OF THE INVENTION

[0006] This invention relates in general to improved methods of manufacturing a stator for an electric motor from a plurality of stator laminations that have hinge features configured to reduce or eliminate thickness changes during the bending or rolling process, wherein the increase in thickness is a result of axial deformation of the stator laminations in the region of the hinges. As a result, variations in the overall height, or thickness, of the stacked plurality of stator laminations is reduced or eliminated.

[0007] In one embodiment, a method of manufacturing a stator for an electric motor includes forming a stator lamination wherein each stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, and wherein each stator lamination has a first free end and a second free end opposite the first free end. A plurality of the stator laminations are stacked to achieve a predetermined stator thickness and adhered together to define a stack of stator laminations having a thickness. The stack of stator laminations are rolled to achieve a circular shape, and the first free ends of the stator laminations are attached to the second free ends of the stator laminations, wherein as the stack of stator laminations is rolled, the thickness of the stack of stator laminations is not increased.

[0008] In another embodiment, the method of manufacturing a stator for an electric motor includes forming a first stator lamination, wherein each first stator laminationAttorney Docket No. 64787-WO-PCT includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, wherein each first stator lamination has a first free end and a second free end opposite the first free end, and wherein an enlarged clearance area is formed radially inboard of the hinge. A second stator lamination is formed, wherein each second stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, and wherein each second stator lamination has a first free end and a second free end opposite the first free end. The first stator lamination is adhered to the second stator lamination to define a pair of stator laminations, and the pairs of stator laminations are stacked to achieve a predetermined stator thickness. The plurality of pairs of stator laminations are adhered together to define a stack of stator laminations, and rolled to achieve a circular shape. The first free ends of the stator laminations are attached to the second free ends of the stator laminations, wherein as the stack of stator laminations is rolled, the thickness of the stack of stator laminations is not increased.

[0009] In an additional embodiment the method of manufacturing a stator for an electric motor includes forming a first stator lamination, wherein each first stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, wherein each first stator lamination has a first free end and a second free end opposite the first free end, and wherein an enlarged clearance area is formed radially inboard of the hinge. A second stator lamination is formed, wherein each second stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, and wherein adjacent T-shaped segments are connected at joints defined by a hinge. The first stator lamination is adhered to the second stator lamination to define a pair of stator laminations, and the pairs of stator laminations are stacked to achieve a predetermined stator thickness. The plurality of pairs of stator laminations are adhered together to define a stack of stator laminations, and rolled to achieve a circular shape. TheAttorney Docket No. 64787-WO-PCT first free ends of the stator laminations are attached to the second free ends of the stator laminations, wherein as the stack of stator laminations is rolled, the thickness of the stack of stator laminations is not increased.

[0010] Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in view of the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a perspective view of a portion of a conventional stator lamination used to manufacture a stator of an electric motor.

[0012] Fig. 2 is an enlarged perspective view of a hinge of the conventional stator lamination illustrated in Fig. 1.

[0013] Fig. 3 is a further enlarged side elevational view of the hinge of the first conventional stator lamination illustrated in Figs. 1 and 2.

[0014] Fig. 4A is a perspective view of a portion of a stator formed from a plurality of stator laminations manufactured in accordance with a first method of this invention.

[0015] Fig. 4B is a perspective view of a portion of a stator similar to the stator illustrated in Fig. 4A, but formed from a stack of conventional stator laminations.

[0016] Fig. 5 is a top plan view of a portion of a first embodiment of a stator lamination manufactured in accordance with the first method of this invention, shown prior to bending.

[0017] Fig. 6 is a top plan view of the portion of the stator lamination shown in Fig. 5 shown after an initial amount of bending has occurred.

[0018] Fig. 7 is a top plan view of the portion of the stator lamination shown in Fig. 6 shown after a further amount of bending has occurred.

[0019] Fig. 8 is a perspective view of a portion of a second embodiment of a stator lamination manufactured in accordance with the second method of this invention.Attorney Docket No. 64787-WO-PCT

[0020] Fig. 9 is an enlarged perspective view of the hinge of the stator lamination illustrated in Fig. 8.

[0021] Fig. 10 is a further enlarged perspective view of the hinge of the stator lamination illustrated in Figs. 8 and 9.

[0022] Fig. 11 is a perspective view of a portion of a third embodiment of a stator lamination manufactured in accordance with the second method of this invention.

[0023] Fig. 12 is an enlarged perspective view of a hinge of the stator lamination illustrated in Fig. 11.

[0024] Fig. 13 is a further enlarged perspective view, partially in cross-section, of a portion of the hinge of the stator lamination illustrated in Fig. 12.

[0025] Fig. 14 is a top plan view of a portion of an upper stator lamination manufactured in accordance with a fourth method of this invention, shown prior to bending.

[0026] Fig. 15 is a top plan view of a portion of a lower stator lamination manufactured in accordance with the fourth method of this invention, also shown prior to bending.

[0027] Fig. 16 is a partially exploded perspective view of the upper stator lamination and the lower stator lamination illustrated in Figs. 14 and 15 aligned with one another prior to assembly.

[0028] Fig. 17 is a top plan view of the upper stator lamination and the lower stator lamination illustrated in Figs. 16 after assembly and defining a pair of stator laminations.

[0029] Fig. 18 is a perspective view of the pair of stator laminations illustrated in Fig. 17.

[0030] Fig. 19 is a perspective view of a portion of a stacked stator lamination comprising a plurality of stator lamination pairs and shown after assembly.

[0031] Fig. 20 is a first alternate perspective view of the stacked stator lamination illustrated in Fig. 19.Attorney Docket No. 64787-WO-PCT

[0032] Fig. 21 is a second alternate perspective view of the stacked stator lamination illustrated in Fig. 19.

[0033] Fig. 22 is a perspective view of the stacked stator lamination illustrated in Figs. 19 through 21 shown after bending.

[0034] Fig. 23 is a partially exploded perspective view of a portion of a fifth embodiment of a stator lamination manufactured in accordance with the fourth method of this invention.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] It is known and desirable to automate the manufacture of a stator, such as the circular stator 81 shown in Fig. 22, in an electric motor (not shown), such as an electric motor having one or more winding cooling liners. One common way to do this is to begin with a flat stator lamination, install electrical insulation, wind the poles, and then roll a stack of stator laminations into a circular shape. During the rolling process, a thin hinge feature in the laminations allows the segments of the laminations to bend and form the circular shape.

[0036] Referring now to the drawings, there is illustrated in Figs. 1 through 3 a portion of a conventional stator lamination 10 used to manufacture a stator 16, a portion of which is shown in Fig. 4B, of an electric motor (not shown). The stator lamination 10 includes a plurality of linearly extending, generally T-shaped teeth or segments 12 defining slots 13 therebetween. Adjacent T-shaped segments 12 are connected at joints defined by a hinge 14. Each segment 12 may include one or more alignment hole 17 formed therethrough.

[0037] Typically, a plurality of the conventional stator laminations 10 are stacked, such as in the manner shown in Fig. 20, and adhered together. When adhered together, the slots 13 of each stator lamination 10 of the stacked stator laminations 10 combine to define channels 15, shown in Fig. 4B. The stack of conventional stator laminations 10 is then rolled to form the stator 16 having a final circular shape a portion of which is shown in Fig. 4B, and shown without the windings for clarity.Attorney Docket No. 64787-WO-PCT

[0038] When the conventional stacked stator laminations 10 are rolled, the hinges 14 undergo substantial plastic deformation. This deformation causes a localized portion of each hinge 14 to become thicker, such as shown as Ti in Fig. 3, and a portion to become thinner, such as shown at T2. When the localized portion Ti becomes thicker, it causes the conventional stacked stator laminations 10 to undesirably spread apart axially, as shown by the arrows Ai and A2. While this localized thickness increase is relatively small, it becomes significant when several hundred stator laminations 10 are stacked on top of each other.

[0039] The overall thickness increase Ti in the axial direction, Ai and / or A2, may be between about 0.02 mm and 0.08 mm. Although this thickness increase is small enough to be considered negligible in just one stator lamination 10, a typical stator stack includes hundreds of stator laminations 10. With such a large number of stator laminations 10, the increase in the overall thickness of the stator stack becomes significant and undesirable.

[0040] For example, each conventional stator lamination 10 may have a thickness of about 0.5 mm. The stator 16, formed from a stack of conventional stator laminations 10, may be formed with 102 stator laminations 10 to achieve a stack thickness of 51 mm. If the thickness increase Ti near each hinge 14 is a total of between about 0.02 mm and 0.08 mm for each stator lamination 10, then the stator 16 formed from the stator laminations 10 would have an undesirable increase in the stack thickness of between about 2.04 mm and 8.16 mm. It would be preferable however, if the stack of stator laminations 10 were not axially distorted or deformed during the roll forming process. The axial deformation may cause fractures in the electrical insulation on the stator laminations 10 and extra tension in the electrical wires.

[0041] One method that has been shown to eliminate the localized thickness increase in an assembled stator, such as the stator 81 shown in Fig. 22, is a stretch hinge method. A portion of a first embodiment of a stator lamination 20 used to manufacture a stator in accordance with the stretch hinge method is shown in Figs. 5 through 7. The stator lamination 20 includes a plurality of linearly extending, generally T-shaped teeth orAttorney Docket No. 64787-WO-PCT segments 22 defining slots 23 therebetween. Each segment 22 may include one or more alignment hole 17 formed therethrough. An outer peripheral edge of each segment 22 (the upper edge when viewing Figs. 5 through 7) may have a notch 21 formed therein configured to have structural members, including but not limited to copper cooling pipes (not shown) positioned therein.

[0042] Adjacent T-shaped segments 22 are connected at joints defined by a hinge 24. The geometry of the hinge 24 is selected and sized to allow for some initial plastic deformation during the start of the rolling process. The hinge 24 may have any desired width Wi. It will be understood that the width Wi may be determined by the thickness of a stack of stator laminations of a stator to be formed therewith, and by a diameter of the stator to be formed.

[0043] In a first method of manufacturing a stator, also known as the stretch hinge method, a plurality of the stator laminations 20 are formed, such as from electrical steel, including but not limited to silicon steel. The steel stator laminations 20 are laminated or coated with an insulating material to prevent eddy currents. Examples of such insulating materials include, but are not limited to a or phosphate coating, an epoxy resin-based enamel and a chromate or a silicate coating.

[0044] Each stator lamination 20 may have any desired number of T-shaped segments 22, such as 24 T-shaped segments 22, and has a first free end 22A and a second free end (not shown) opposite the first free end 22A. The first method of manufacturing, as shown in Figs. 5 through 7, includes stacking a plurality of the stator laminations 20 to achieve a desired stator thickness, using cleats or interlocks (not shown) to hold the stacked stator laminations 20 together, and adhering the stacked stator laminations 20 together using any conventional means, including but not limited to adhesives, mechanical fastening means, such as staking, and welding. When adhered together, the slots 23 of each stator lamination 20 of the stacked stator laminations 20 combine to define channels (not shown), similar to the channels 83 shown in Figs. 4A and 22. The stack of stator laminations 20 is then rolled to achieve the desired final circular shape, such as shown inAttorney Docket No. 64787-WO-PCTFig. 22, and shown without the windings for clarity. The first free end 22A is then attached to the second free end (not shown), such as by welding.

[0045] As the T-shaped segments 22 are rolled together, the adjacent faces 25 of the T- shaped segments 22 of the stator laminations 20 contact each other and define an area in compression, see the circle 26, and apply tension to the hinge 24, see the circle 27. The rolling process will create a localized thickness increase in the hinge 24. This localized thickness is reduced when the hinge 24 is stretched during the final formation of the circular shape, as shown in Fig. 7. Advantageously, the first method of manufacturing, as shown in Figs. 5 through 7 creates a hinge that is in tension. However, although the stretch hinge method is effective, the amount of force needed to stretch each stator lamination 20 may result in buckling of the stator laminations 20. Such buckled stator laminations 20 may cause undesirable distortions of the stacked stator laminations 20.

[0046] A second method that has been shown to eliminate the localized thickness increase in an assembled stator is designed to create expansion space for axially expanding material near the hinge. A portion of a second embodiment of a stacked stator lamination 30 used to manufacture a stator in accordance with the method of creating expansion space is shown in Figs. 8 through 10. In Figs. 8 through 10, a representative pair 32 of stator laminations of the stacked stator lamination 30 is shown and includes a first or upper stator lamination 34 and a second or lower stator lamination 36. The upper stator lamination 34 includes a plurality of linearly extending, generally T-shaped teeth or segments 38 defining slots 39 therebetween, and has a first free end 34A and a second free end (not shown) opposite the first free end 34A.

[0047] Adjacent T-shaped segments 38 are connected at joints defined by a hinge 40. The geometry of the hinge 40 is similar to the hinge 24 described above, is relatively thin and is in tension when the stacked stator lamination 30 rolled to achieve its final circular shape. Like the hinge 24, the hinge 40 may have any desired width Wi. It will be understood that the width Wi may be determined by the thickness of a stack of statorAttorney Docket No. 64787-WO-PCT laminations of a stator to be formed therewith, and by a diameter of the stator to be formed. An enlarged clearance area 42 is formed radially inboard of the hinge 40.

[0048] The lower stator lamination 36 includes a plurality of linearly extending, generally T-shaped teeth or segments 44 defining slots 45 therebetween, and has a first free end 36A and a second free end (not shown) opposite the first free end 36A. Adjacent T-shaped segments 44 are connected at joints defined by a hinge 46. The geometry of the hinge 46 is similar to the hinge 14 described above. An enlarged opening 48 is formed radially inboard of the hinge 46. The opening 48 is smaller than the enlarged clearance area 42 and has a generally teardrop shape when the lower stator lamination 36 is rolled, as shown in Fig. 10.

[0049] A second method of manufacturing a stator is shown in Figs. 8 through 10 and is designed to create expansion space for axially expanding material near the hinge 46 of the lower stator lamination 36. As described above, a plurality of the stator laminations 34 and 36 are formed, such as from phosphate coated electrical steel. Each of the stator laminations 34 and 36 may have any desired number of T-shaped segments 38 and 44, respectively, such as 24 T-shaped segments 38 and 44. The second method of manufacturing includes adhering one of the upper stator laminations 34 to one of the lower stator laminations 36 to define the pair 32 of stator laminations of the stacked stator lamination 30. The stator laminations 34 and 36 may be adhered together using any conventional means, including but not limited to adhesives, mechanical fastening means, such as staking, and welding. When adhered together, the slots 39 and 45 of each pair 32 of stator laminations of the stacked stator laminations 30 combine to define channels (not shown), similar to the channels 83 shown in Figs. 4A and 22.

[0050] A plurality of pairs 32 of stator laminations are then stacked to achieve a desired stator thickness, and the pairs 32 are adhered together as described above. The stack of stator lamination pairs 32 is then rolled to achieve the desired final circular shape, such as shown in Fig. 22, and shown without the windings for clarity. The first free end 34A is then attached to the second free end (not shown), such as by welding.Attorney Docket No. 64787-WO-PCT

[0051] As the T-shaped segments 44 of the lower stator lamination 36 are rolled together, adjacent faces of the T- shaped segments 44 of the lower stator laminations 36 contact each other, and the hinges 46 undergo substantial plastic deformation and are mostly in compression. This deformation causes a localized portion of each hinge 46 to become thicker axially, as indicated generally at 50 in Fig. 10, and as described above in reference to the stator laminations 20. Advantageously, the axially deformed material near the hinge 46 of the lower stator lamination 36 will expand into the clearance area 42 of the upper stator lamination 34.

[0052] A portion of a third embodiment of a stacked stator lamination 60 used to manufacture a stator in accordance with the second method, or the method of creating expansion space, is shown in Figs. 11 through 13. In Figs. 11 through 13, a representative pair 62 of stator laminations of the stacked stator lamination 60 is shown and includes a first or upper stator lamination 64 and the lower stator lamination 36. The upper stator lamination 64 includes a plurality of linearly extending, generally T-shaped teeth or segments 68 defining slots 69 therebetween, and has a first free end 64A and a second free end (not shown) opposite the first free end 64A.

[0053] Adjacent T-shaped segments 68 of the upper stator lamination 64 are connected at joints defined by a hinge 70. The geometry of the hinge 70 is similar to the hinges 24 and 40 described above, is relatively thin and is in tension when the stacked stator lamination 60 is rolled to achieve its final circular shape. Like the hinges 24 and 40, the hinge 70 may have any desired width Wi. It will be understood that the width Wi may be determined by the thickness of a stack of stator laminations of a stator to be formed therewith, and by a diameter of the stator to be formed. An enlarged, circumferentially extending clearance area 72 is formed radially inboard of the hinge 70.

[0054] In Figs. 11 through 13, the second method of manufacturing a stator is shown using a stack of the stator lamination pairs 62, and is designed to create expansion space for axially expanding material near the hinge 46 of the lower stator lamination 36. As described above, a plurality of the stator laminations 64 and 36 are formed, such as fromAttorney Docket No. 64787-WO-PCT phosphate coated electrical steel. Each of the stator laminations 64 and 36 may have any desired number of T-shaped segments 68 and 44, respectively, such as 24 T-shaped segments 68 and 44. The second method of manufacturing includes adhering one of the upper stator laminations 64 to one of the lower stator laminations 36 to define a pair 62 of stator laminations of the stacked stator lamination 60. The stator laminations 64 and 36 may be adhered together using any conventional means, including but not limited to adhesives, mechanical fastening means, such as staking, and welding. When adhered together, the slots 69 and 45 of each pair 62 of stator laminations of the stacked stator laminations 60 combine to define channels (not shown), similar to the channels 83 shown in Figs. 4A and 22.

[0055] A plurality of pairs 62 of stator laminations are then stacked to achieve a desired stator thickness, and the pairs 62 are adhered together as described above. The stack of stator lamination pairs 62 is then rolled to achieve the desired final circular shape, and shown without the windings for clarity. The first free end 64A is then attached to the second free end (not shown), such as by welding.

[0056] As the T-shaped segments 44 of the lower stator lamination 36 are rolled together, adjacent faces of the T- shaped segments 44 of the lower stator laminations 36 contact each other, and the hinges 46 undergo substantial plastic deformation and are mostly in compression. This deformation causes a localized portion of each hinge 46 to become thicker axially, as shown at 50 in Fig. 13, and as described above in reference to the stator laminations 20. Advantageously, the axially deformed material near the hinge 46 of the lower stator lamination 36 will expand into the clearance area 72 of the upper stator lamination 64.

[0057] Advantageously, the second method, or the method of creating expansion space, as shown in Figs. 8 through 10 and Figs. 11 through 13, uses the pairs 32 and 62 of alternating laminations layers, wherein each layer of each pair 32 and 62 has a different configuration, including a different hinge. As described above, the hinge in a lower lamination layer will distort and expand axially. However, an upper lamination layerAttorney Docket No. 64787-WO-PCT includes an opening into which the localized thickness increase in the lower layer may expand and occupy. The hinge of each upper lamination layer 34 and 64 is thin and in tension only. Thus, there is only minimal localized thickness increase on each upper lamination layer 34 and 64. Advantageously, the pairs 32 and 62 of stator laminations may be stacked to create a lamination stack of any desired height.

[0058] A third method that may be used to eliminate the localized thickness increase in an assembled stator is a press hinge method (not shown). The press hinge method comprises pressing a lamination stack, such as the stack of conventional stator laminations 10, which has been axially deformed during the rolling process, so as to return stack of conventional stator laminations 10 to its pre-rolled height or thickness. Such pressing may be accomplished by any desired press configured to generate a force sufficient to return the assembled stator to its pre-rolled height, including, but not limited to a hydraulic cylinder. However, because the press hinge method allows for the stack of conventional stator laminations 10 to axially distort prior to pressing the height back its pre-rolling height, the risk of fracture of the insulation system is increased.

[0059] A fourth method of manufacturing a stator is shown in Figs. 14 through 22 and advantageously eliminates the undesirable axial deformation in a stack of stator laminations by using a combination of the second method, or the method of creating expansion space, and the Creating Expansion Space and the first or stretch hinge method.

[0060] A portion of a fifth embodiment of a stacked stator lamination 80 used to manufacture the stator 81 in accordance with the fourth method, or the method comprising the combination of creating expansion space and the stretch hinge method, is shown in Figs. 14 through 22. In Figs. 14 through 18, a representative pair 82 of stator laminations of the stacked stator lamination 80 is shown and includes a first or upper stator lamination 84 and a lower stator lamination 86. The upper stator lamination 84 includes a plurality of linearly extending, generally T-shaped teeth or segments 88 defining slots 89 therebetween, and has a first free end 84A and a second free end 84B, opposite the first free end 84A (see Fig. 20). Adjacent T-shaped segments 88 of the upperAttorney Docket No. 64787-WO-PCT stator lamination 84 are connected at joints defined by a hinge 90. The geometry of the hinge 90 is similar to the hinge 24 described above, is relatively thin and is in tension when the stacked stator lamination 80 is rolled to achieve its final circular shape, as shown at 81 in Fig. 22. Like the hinges 24, 40, and 70, the hinge 90 may have any desired width Wi. It will be understood that the width Wi may be determined by the thickness of a stack of stator laminations of a stator to be formed therewith, and by a diameter of the stator to be formed. An enlarged, circumferentially extending clearance area 92 is formed radially inboard of the hinge 90.

[0061] The lower stator lamination 86 includes a plurality of linearly extending, generally T-shaped teeth or segments 94 defining slots 95 therebetween, and has a first free end 86A and a second free end 86B, opposite the first free end 86A (see Fig. 20). Adjacent T-shaped segments 94 are connected at joints defined by a hinge 96. The geometry of the hinge 96 is similar to the hinge 14 described above.

[0062] In Figs. 14 through 22, the fourth method of manufacturing a stator is shown using a stack of the stator lamination pairs 82, and is designed to create expansion space for axially expanding material near the hinge 96 of the lower stator lamination 86. As described above, a plurality of the stator laminations 84 and 86 are formed, such as from phosphate coated electrical steel. Each of the stator laminations 84 and 86 may have any desired number of T-shaped segments 88 and 94, respectively, such as 24 T-shaped segments 88 and 94 as shown in Fig. 20. The fourth method of manufacturing includes adhering one of the upper stator laminations 84 to one of the lower stator laminations 86 to define a pair 82 of stator laminations of the stacked stator lamination 80. The stator laminations 84 and 86 may be adhered together using any conventional means, including but not limited to adhesives, mechanical fastening means, such as staking, and welding. When adhered together, the slots 89 and 95 of each pair 82 of stator laminations of the stacked stator laminations 80 combine to define channels 83 shown in Figs. 4A and 19 through 22.Attorney Docket No. 64787-WO-PCT

[0063] A plurality of pairs 82 of stator laminations are then stacked to achieve a desired stator thickness, and the pairs 82 are adhered together as described above. The stacked stator lamination pairs 82 are then rolled to achieve the desired final circular shape, as shown at 81 in Fig. 22. The first free ends 84A and 86A are then attached to the second free ends 84B and 86B, such as by welding.

[0064] As the T-shaped segments 94 of the lower stator lamination 86 are rolled together to form the stator 81, adjacent faces of the T-shaped segments 94 of the lower stator laminations 86 contact each other, and apply tension to the hinge 96. When a stack of stator lamination pairs 82 are rolled, the hinges 96 undergo substantial plastic deformation and are mostly in compression. This deformation causes a localized portion of each hinge 96 to become thicker axially, as described above in reference to the stator laminations 20. Advantageously, the axially deformed material near the hinge 96 of the lower stator lamination 86 will expand into the clearance area 92 of the upper stator lamination 84. Additionally, the hinge 90 is relatively thin and is in tension when the stator lamination 30 rolled to achieve its final circular shape. The stretched hinge 90 has very little axial deformation because the strain is low and the hinge 90 is being stretched through most of the rolling or bending process.

[0065] A portion of a fifth embodiment of a stacked stator lamination 100 used to manufacture a stator in accordance with the fourth method, or the method comprising the combination of creating expansion space and the stretch hinge method, is shown in Fig. 23. In Fig. 23, a representative pair 102 of stator laminations of the stacked stator lamination 100 is shown and includes a first or upper stator lamination 104 and a lower stator lamination 106. The upper stator lamination 104 includes a plurality of linearly extending, generally T-shaped teeth or segments 108 defining slots 109 therebetween, and has a first free end 104 A and a second free end (not shown) opposite the first free end 104A.

[0066] Adjacent T-shaped segments 108 of the upper stator lamination 104 are connected at joints defined by a hinge 110. The geometry of the hinge 110 is similar toAttorney Docket No. 64787-WO-PCT the hinges 24, 40, and 70 described above, is relatively thin and is in tension when the stacked stator lamination 100 is rolled to achieve its final circular shape. Like the hinges 24, 40, and 70, the hinge 110 may have any desired width Wi. It will be understood that the width Wi may be determined by the thickness of a stack of stator laminations of a stator to be formed therewith, and by a diameter of the stator to be formed. An enlarged, circumferentially extending clearance area 112 is formed radially inboard of the hinge 110.

[0067] The lower stator lamination 106 includes a plurality of linearly extending, generally T-shaped teeth or segments 114 defining slots 115 therebetween, and has a first free end 106 A and a second free end (not shown) opposite the first free end 106 A. Adjacent T-shaped segments 114 are connected at joints defined by a hinge 116. The geometry of the hinge 116 is similar to the hinge 14 described above. An enlarged, circumferentially extending opening 118 is formed radially inboard of the hinge 116. The opening 118 is smaller than the enlarged clearance area.

[0068] As described above, a plurality of the stator laminations 104 and 106 are formed, such as from phosphate coated electrical steel. Each of the stator laminations 104 and 106 may have any desired number of the T-shaped segments 108 and 114, respectively, such as 24 T-shaped segments 108 and 104. The second method of manufacturing includes adhering one of the upper stator laminations 104 to one of the lower stator laminations 106 to define the pair 102 of stator laminations of the stacked stator lamination 100. The stator laminations 104 and 106 may be adhered together using any conventional means, including but not limited to adhesives, mechanical fastening means, such as staking, and welding. When adhered together, the slots 109 and 115 of each pair 102 of stator laminations of the stacked stator laminations 100 combine to define channels (not shown), similar to the channels 83 shown in Figs. 4A and 22. Both the upper stator lamination 104 and the lower stator lamination 106 may include one or more alignment hole 107 formed therethrough. Additionally, both the upper statorAttorney Docket No. 64787-WO-PCT lamination 104 and the lower stator lamination 106 may have a notch 111, similar to the notch 21 described above, formed therein.

[0069] A plurality of pairs 102 of stator laminations are then stacked to achieve a desired stator thickness, and the pairs 102 are adhered together as described above. The stack of stator lamination pairs 102 is then rolled to achieve the desired final circular shape, and shown without the windings for clarity. The first free end 104 A is then attached to the second free end (not shown), such as by welding.

[0070] As the T-shaped segments 104 of the lower stator lamination 106 are rolled together, adjacent faces of the T- shaped segments 104 of the lower stator laminations 106 contact each other, and the hinges 116 undergo substantial plastic deformation and are mostly in compression. This deformation causes a localized portion of each hinge 116 to become thicker axially, as described above in reference to the stator laminations 20. Advantageously, the axially deformed material near the hinge 116 of the lower stator lamination 106 will expand into the clearance area 112 of the upper stator lamination 104.

[0071] Advantageously, the fourth method of manufacturing a stator described herein above allows the axially deformed regions of the hinges 96 and 116 to expand into the space provided by the clearance areas 92 and 112, respectively. The stretched hinges 90 and 110 of the upper stator laminations 84 and 104 have very little or no axial deformation since the strain is low and it is being stretched through nearly the entire bending process.

[0072] Additionally, a stator formed with any of the four methods of manufacturing a stator described herein above, such as the stator 81 shown in Fig. 4A, will be significantly thinner than a similar conventional stator, such as the stator 16 shown in Fig. 4B, when both the stators 81 and 16 are formed with the same number of stator laminations.

[0073] The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that thisAttorney Docket No. 64787-WO-PCT invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.

Claims

Attorney Docket No. 64787-WO-PCTCLAIMS1. A method of manufacturing a stator for an electric motor comprising: forming a stator lamination wherein each stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T- shaped segments are connected at joints defined by a hinge, and wherein each stator lamination has a first free end and a second free end opposite the first free end; stacking a plurality of the stator laminations to achieve a predetermined stator thickness; adhering the plurality of stator laminations together to define a stack of stator laminations having a thickness; rolling the stack of stator laminations to achieve a circular shape; and attaching the first free ends of the stator laminations to the second free ends of the stator laminations; wherein as the stack of stator laminations is rolled, the thickness of the stack of stator laminations is not increased.

2. The method according to claim 1, wherein as the stack of stator laminations is rolled, the adjacent faces of the T-segments of the stator laminations contact each other and each hinge is stretched.

3. The method according to claim 2, wherein as each hinge is stretched, its thickness reduced, and each hinge is placed in tension.

4. A method of manufacturing a stator for an electric motor comprising: forming a first stator lamination, wherein each first stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, wherein each firstAttorney Docket No. 64787-WO-PCT stator lamination has a first free end and a second free end opposite the first free end, and wherein an enlarged clearance area is formed radially inboard of the hinge; and forming a second stator lamination, wherein each second stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, and wherein each second stator lamination has a first free end and a second free end opposite the first free end; adhering the first stator lamination to the second stator lamination to define a pair of stator laminations; stacking a plurality of the pairs of stator laminations to achieve a predetermined stator thickness; adhering the plurality of pairs of stator laminations together to define a stack of stator laminations; rolling the stack of stator laminations to achieve a circular shape; and attaching the first free ends of the stator laminations to the second free ends of the stator laminations; wherein as the stack of stator laminations is rolled, the thickness of the stack of stator laminations is not increased.

5. The method according to claim 4, wherein an enlarged opening is formed radially inboard of the hinge of the second stator lamination, and wherein the enlarged opening is smaller than the enlarged clearance area of the first stator lamination.

6. The method according to claim 5, wherein the enlarged opening is teardrop shaped.

7. The method according to claim 5, wherein the enlarged opening is circumferentially extending.Attorney Docket No. 64787-WO-PCT8. The method according to claim 5, wherein as the stack of stator laminations is rolled, the adjacent faces of the T-segments of the second stator laminations contact each other, thus causing the hinges of each second stator lamination to be compressed and to deform such that portions of each hinge becomes thicker axially.

9. The method according to claim 8, wherein the thicker portions of each hinge of each second lamination expands axially into the enlarged clearance area of the first stator lamination of each pair of stator laminations.

10. The method according to claim 9, wherein the enlarged clearance area is radially extending.

11. The method according to claim 10, wherein the enlarged clearance area is teardrop shaped.

12. The method according to claim 9, wherein the enlarged clearance area is circumferentially extending.

13. A method of manufacturing a stator for an electric motor comprising: forming a first stator lamination, wherein each first stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, wherein adjacent T-shaped segments are connected at joints defined by a hinge, wherein each first stator lamination has a first free end and a second free end opposite the first free end, and wherein an enlarged clearance area is formed radially inboard of the hinge; andAttorney Docket No. 64787-WO-PCT forming a second stator lamination, wherein each second stator lamination includes a plurality of linearly extending T-shaped segments defining slots therebetween, and wherein adjacent T-shaped segments are connected at joints defined by a hinge; adhering the first stator lamination to the second stator lamination to define a pair of stator laminations; stacking a plurality of the pairs of stator laminations to achieve a predetermined stator thickness; adhering the plurality of pairs of stator laminations together to define a stack of stator laminations; rolling the stack of stator laminations to achieve a circular shape; and attaching the first free ends of the stator laminations to the second free ends of the stator laminations; wherein as the stack of stator laminations is rolled, the thickness of the stack of stator laminations is not increased.

14. The method according to claim 13, wherein the enlarged clearance area is circumferentially extending.

15. The method according to claim 13, wherein as the stack of stator laminations is rolled, the adjacent faces of the T-segments of the first stator laminations contact each other and each hinge is stretched.

16. The method according to claim 15, wherein as each hinge is stretched, its thickness reduced, and each hinge is placed in tension.

17. The method according to claim 13, wherein as the stack of stator laminations is rolled, the adjacent faces of the T-segments of the second stator laminations contact each other, thus causing portions of each second stator lamination toAttorney Docket No. 64787-WO-PCT be compressed and to deform such that the portions of each second stator lamination become thicker axially.

18. The method according to claim 17, wherein the thicker portions of each second stator lamination expands axially into the clearance area of the first stator lamination of each pair of stator laminations.

19. The method according to claim 13, wherein as the stack of stator laminations is rolled, the adjacent faces of the T-segments of the second stator laminations contact each other, thus causing the hinges of each second stator lamination to be compressed and to deform such that portions of each hinge becomes thicker axially.

20. The method according to claim 19, wherein the thicker portions of each hinge of each second lamination expands axially into the clearance area of the first stator lamination of each pair of stator laminations.

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