A motor in which a stator is formed from a stator motorlet and a compression spacer to improve heat transfer efficiency

Abstract

An electric motor is provided having a stator and a rotor rotatably mounted within the stator. The stator includes a plurality of motlets, each having an iron metal core segment and an electrically conductive winding on the core segment. The plurality of motlets are arranged in a circular configuration, and a plurality of wedges are provided, one of the wedges positioned at each interface between the electrically conductive windings of adjacent ones of the motlets, to press the electrically conductive windings of adjacent ones of the motlets against the respective iron metal core segment. This provides a configuration with minimal or no air gap between the electrically conductive windings and electrical insulation on the core segment or each of the core segments.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority to U.S. Non - Provisional Application No. 17 / 412,411, filed on August 26, 2021, the entire disclosure of which is incorporated herein by reference.

[0002] Field of the Invention The present disclosure relates to an e - motor (electric motor) used in an electric vehicle or a hybrid electric vehicle, and more specifically, to a stator formed from motrets made of core segments having conductive windings that form the stator of the e - motor.

Background Art

[0003] Material conductivity thermally affects the amount of material required to create the magnetic field necessary within an e - motor to produce mechanical power. In automotive applications, it is necessary to optimize performance to increase the driving range. Therefore, reducing the thermal resistance of the packaging laminate of the e - motor can help increase the power density and may enable weight reduction or performance improvement.

[0004] During winding of the stator core segments of a concentrated - wound e - motor stator assembled from pre - wound core segments (motrets), it has been found that the current tensioning method may leave a small void between the copper of the core segment and the plastic bobbin overmold. This void is a problem for e - motor performance based on heat transfer between materials within the assembled stator.

Summary of the Invention

Means for Solving the Problems

[0005] In one aspect, the present disclosure aims to provide an interference fit between the stator coil and the stator core segment / bobbin on which the coil is wound, by reducing or eliminating this void to include a minimal void or no void, in order to improve heat transfer efficiency.

[0006] According to the present disclosure, an electric motor is provided having a stator and a rotor rotatably mounted within the stator. The stator includes a plurality of motrets each having a ferromagnetic core segment and a conductive winding on the core segment. The plurality of motrets are arranged in a circular configuration, and a plurality of wedges are provided, with one of the wedges positioned at each interface between the conductive windings of adjacent motrets among the motrets, pressing the conductive windings of adjacent motrets among the motrets toward respective ferromagnetic core segments of the ferromagnetic core segments. Thereby, a configuration is provided that includes a minimum gap or no gap between the conductive winding and the electrical insulator on each of the core segment or core segments.

[0007] In one embodiment, each of the wedges has a fixed taper portion.

[0008] In another embodiment, the wedge includes two winding contact surfaces extending between a radially outer end and a radially inner end, the radially outer end being wider than the radially inner end, and the winding contact surfaces having a convex shape. Thereby, in a region where the convex shape extends or curves outward, the force applied to the conductive winding by the wedge becomes larger.

[0009] In another embodiment, the wedge includes two winding contact surfaces extending between a radially outer end and a radially inner end, the radially outer end being wider than the radially inner end, and the winding contact surfaces having an outer shape configured to apply a greater circumferential compressive force to adjacent conductive windings among the conductive windings within a region between the radially outer end and the radially inner end. In this configuration, the outer shape can be adjusted according to a specific application or motret configuration.

[0010] In one aspect, the wedge is formed of a polymer material.

[0011] In another aspect, the wedge is formed of a thermally conductive material. This thermally conductive material can be a polymeric thermally conductive material.

[0012] In another aspect, an insulating potting material is injected to surround the conductive winding, and preferably the insulating potting material is also thermally conductive.

[0013] In another aspect, a method of assembling a stator of an e - motor is provided, the method comprising: (a) winding a conductive winding around a ferrous metal core segment to form a motoret; and (b) arranging a plurality of motorets in a circular configuration, wherein a wedge is positioned at each interface between adjacent motorets' conductive windings among the motorets; and (c) compressing the motorets together such that the wedge presses the conductive windings of adjacent motorets among the motorets towards respective ferrous metal segments of the ferrous metal core segment to form a stator.

[0014] The method can further include that the ferrous metal core is overmolded with an electrical insulator formed of a polymeric material. Alternatively, other types of insulators such as paper insulators may be used.

[0015] The method can also include injecting a potting material around the conductive winding and the wedge.

[0016] The shape and structure of the wedge can also be selected from the various configurations disclosed herein to minimize or eliminate the air gap between the conductive winding and the core segment in order to improve the heat transfer efficiency and the overall efficiency of the e - motor.

[0017] It should be noted that various of the above - mentioned features can be used alone or in combination with each other.

[0018] The foregoing summary and the following detailed description will be better understood when read in conjunction with the accompanying drawings that illustrate preferred embodiments of the present disclosure.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0020] In the following description, certain terms are used for convenience only and are not limiting. The terms "inwardly" and "outwardly" refer to the direction toward and away from the component referenced in the drawings. A reference to a list of items cited as "at least one of a or b" (where a and b represent the listed items) means either single one of the items a or b, or a combination of both of them a and b. This applies equally to lists of three or more items, including individual items of the list or combinations thereof. The terms "about" and "approximately" include ±10% of the indicated value unless otherwise stated. The terms include the words specifically described above, derivatives thereof, and words of similar meaning. In the context of minimizing a gap, this means that the gap is 0.030 inches or less.

[0021] Referring to FIG. 1, an electric motor (e - motor) 10 according to the present disclosure is schematically shown. The e - motor 10 includes a stator 20 and a rotor 40 rotatably mounted within the stator 20, with a shaft 42 extending from the rotor 40. The stator 20 is surrounded by a housing or casing 21. End covers, although not shown, can be attached in the same manner as other attachment components and electronic components.

[0022] Referring to FIGS. 2 and 8, the stator 20 includes a plurality of motrets 22, each including a ferromagnetic core segment 24 and a conductive winding 26 on the core segment 24. A single motret is shown in FIG. 2 with the conductive winding 26 wound around the core segment 24. As shown in detail in FIG. 8, each of the ferromagnetic core segments 24 is preferably coated or covered with an electrical insulator 28 (also referred to as a bobbin) in the region of the conductive winding 26, and the conductive winding 26 is wound on the electrical insulator 28. The insulator is preferably made of a thermally conductive material, and examples of the thermally conductive material include nylon PA46 containing a glass-filled mixture, electrical insulating paper, or a thermally conductive polymer such as a PET film. The conductive winding 26 is preferably made of a coated copper wire. However, other conductive materials can also be used.

[0023] As shown in FIGS. 6 and 7, a plurality of motrets 22 are arranged in a circular configuration, and a plurality of wedges 30 are provided, with one of the wedges 30 positioned at each interface between the conductive windings of adjacent motrets among the motrets 22, pressing the conductive windings 26 of the adjacent motrets among the motrets 22 toward the respective ferromagnetic core segments of the ferromagnetic core segments 24.

[0024] As shown in FIGS. 3A and 3B, the wedge 30 may have a fixed taper portion. A first alternative form of the wedge 30A is shown in FIGS. 4A and 4B. The wedge 30A includes two winding contact surfaces 32, 33 extending between a radially outer end 34 and a radially inner end 35 of the wedge 30A. The radially outer end 34 is wider than the radially inner end 35, and the winding contact surfaces 32, 33 each have a convex shape 36. This makes it possible to target and apply more force to the middle region of the conductive winding 26. Alternatively, as shown in FIGS. 5A and 5B, the wedge 30B may include an outer shape 37 configured to apply a greater circumferential force to adjacent conductive windings among the conductive windings 26 in the region between the radially outer end 34 and the radially inner end 35. This outer shape 37 can be a simple rectangular outer shape or a more complex stepped outer shape depending on where additional force needs to be applied to the conductive winding to reduce or eliminate the gap between the conductive winding 26 and the electrical insulator 28 on each stator core segment 24 or the conductive winding 26 within the target area shown by the dashed line in FIG. 8. Wedges 30, 30A, 30B of the same or different types can be used within a single stator 20. Reducing or eliminating the gap provides better thermal efficiency in transferring heat from the conductive winding 26 during operation, improving the overall performance and efficiency of the e - motor 10.

[0025] Wedges 30, 30A, 30B are preferably formed of a polymer material such as a glass - filled nylon mixture, or a ceramic material, or other thermally conductive materials. Wedges 30, 30A, 30B are also preferably formed of a thermally conductive material.

[0026] As shown in detail in FIG. 8, the potting material 38 is preferably both thermally conductive and electrically insulating and surrounds the conductive winding 26. The potting material 38 can be injected after the motorlet 22 and the wedges 30, 30A, 30B are assembled, and the assembly process will be described in more detail below.

[0027] Referring now to FIG. 6, a method of assembling the stator 20 of the e - motor 10 is described. After forming the motoret 22 by winding the conductive winding 26 around the ferrous metal core segment 24, a plurality of motorets 22 are arranged in a circular configuration, and wedges 30, 30A, 30B are positioned at each interface between the conductive windings 26 of adjacent motorets of the motoret 22. As schematically shown in FIG. 6, this configuration is provided within a clamp assembly 50 (represented as a clamping ring), and after positioning the motoret 22 and the wedges 30, 30A, 30B in place, they are compressed together by the clamping ring 50 such that the wedges 30, 30A, 30B press the conductive windings 26 of adjacent motorets of the motoret 22 against the respective ferrous metal core segments of the ferrous metal core segment 24 or the electrical insulator 28 on the conductive winding 26 to form the stator 20. The clamping ring 50 may be a permanent part of the final assembly, or the compressed configuration can be transferred, as shown in FIG. 7, into a housing or casing 21 that maintains the compressed motoret 22 and wedges 30, 30A, 30B in place, and the conductive winding 26 is pressed against the ferrous metal core segment 24 or the insulator 28 on the conductive winding 26 to reduce or eliminate any air gaps.

[0028] The electrical insulator 28 is preferably formed of a polymeric material and overmolded onto the ferrous metal core segment 24.

[0029] Furthermore, after assembly, in order to provide more efficient heat transfer and to reduce any movement of components due to vibration, potting material 38 can be injected around the conductive winding 26 and the wedges 30, 30A, 30B.

[0030] Thus, while the presently preferred embodiments have been described in detail, many physical changes can be made without changing the concepts and principles embodied in the present invention, some of which are only illustrated in the detailed description of the present invention, and which will be apparent to those skilled in the art. Also, numerous embodiments incorporating only some of the preferred embodiments are possible, and it should be understood that the concepts and principles embodied in the present invention are not changed with respect to these portions. Accordingly, the present embodiments and optional configurations should be considered illustrative and / or exemplary in all respects and not limiting, and the scope of the present invention is indicated by the appended claims rather than the foregoing description, and accordingly, all alternative embodiments and modifications to the present embodiments that fall within the meaning and scope of the equivalents of the claims should be included within the scope of the claims.

Explanation of Reference Numerals

[0031] 10 Electric motor 20 Stator 21 Casing or housing 22 Motorette 24 Ferromagnetic core segment 26 Conductive winding 28 Electrical insulator 30, 30A, 30B Wedge 32 Winding contact surface 33 Winding contact surface 34 Radial outer end 35 Radial inner end 36 Convex shape 37 Outer shape 38 Potting 40 Rotor 42 Shaft 50 Clamping ring

Claims

1. An electric motor comprising: a stator; a rotor rotatably mounted within the stator, wherein the stator comprises: a plurality of motrets, each comprising a ferrous metal core segment and a conductive winding on the ferrous metal core segment; a plurality of motrets arranged in a circular configuration; a plurality of wedges, one of the wedges being positioned at each interface between the conductive windings of adjacent ones of the motrets, the wedges pressing the conductive windings of the adjacent motrets towards respective ones of the ferrous metal core segments; and the plurality of wedges each comprise a radially outer end, a radially inner end that is narrower than the radially outer end, and two winding contact surfaces extending between the radially outer end and the radially inner end, the winding contact surfaces having a convex shape extending in the radial direction so as to apply a circumferential compressive force to adjacent ones of the conductive windings in a region between the radially outer end and the radially inner end.

2. The electric motor according to claim 1, further comprising an electrical insulator on each of the ferrous metal core segments, the conductive winding being wound on the electrical insulator.

3. The electric motor according to claim 1, wherein each of the wedges has a tapered portion.

4. The electric motor according to claim 1, wherein the wedges are formed of a polymer material or a ceramic material.

5. The electric motor according to claim 1, further comprising a potting material surrounding the conductive winding.

6. A method of assembling a stator of an e - motor, the method comprising: wrapping a conductive winding around a ferrous metal core segment to form a motret; arranging a plurality of motrets in a circular configuration such that a wedge is positioned at each interface between the conductive windings of adjacent motrets; compressing the motrets together such that the wedge presses the conductive windings of the adjacent motrets towards respective ones of the ferrous metal core segments to form the stator. and The plurality of wedges each include a radially outer end, a radially inner end that is narrower in width than the radially outer end, and two winding contact side surfaces that extend between the radially outer end and the radially inner end, and the winding contact side surfaces have a convex shape that extends in the radial direction so as to apply a circumferential compression force to adjacent ones of the conductive windings among the conductive windings in a region between the radially outer end and the radially inner end, a method.

7. The method according to claim 6, further comprising providing an electrical insulator on the ferrous metal core segment before winding the conductive winding.

8. The method according to claim 6, wherein the ferrous metal core segment is overmolded with an electrical insulator formed of a polymer material.

9. The method according to claim 6, further comprising injecting a potting material around the conductive winding and the wedge.

10. The method according to claim 6, wherein each of the wedges has a tapered portion.

11. The method according to claim 6, wherein the wedges are formed of a polymer material or a ceramic material.

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