Stator with in-slot forming and cooling

Abstract

The present disclosure provides "Stator with In-Slot Forming and Cooling". An electric machine includes a stator having a plurality of slots, each slot including a main body, a step, and a narrower coolant guide channel. Windings are positioned within the slot main body and not within the channel, and an electrically insulating coating such as varnish or epoxy is applied to the slot main body and step to provide electrical insulation while maintaining cooling efficiency. The slots are unlined and can accommodate hairpin windings or nested hairpin windings. To facilitate stator assembly, a forming tool is used to seal the channel during application of the insulating material, so the channel remains open for coolant flow. After curing, the forming tool is removed, allowing insertion of the windings.

Description

Technical Field

[0001] This disclosure relates to electric motors. Background Technology

[0002] An electric motor may include a stator and a rotor that cooperate to convert electrical energy into mechanical energy, or vice versa. The conversion of electrical energy into mechanical energy can generate heat. Summary of the Invention

[0003] An electric motor includes a stator having multiple slots, each slot having a body, a narrower coolant guide channel, and an intermediate step. Windings are positioned within the slot body rather than within the channel, and an electrically insulating coating, such as a varnish or epoxy resin, is applied to the slot body and the step, thereby forming an insulating barrier between the windings and the stator. The slots are unlined, and the windings can be hairpin windings or nested hairpin windings. The stator may incorporate axial or annular coolant passages, wherein the passages provide fluid communication for cooling.

[0004] The stator assembly station includes a forming tool designed to be placed within the body and steps of a stator slot, thereby sealing the channel while forming a surrounding gap. A distributor injects electrical insulation into the gap, where the forming tool prevents the insulation from entering the channel. The assembly station may also include a sleeve to seal the slot from the stator bore. Once the insulation has cured, the forming tool is removed, leaving a gap in the slot for inserting the magnetic winding.

[0005] A stator for an electric motor includes stacked laminations forming a stator core with multiple slots, each slot characterized by a body, a narrower step, and even narrower channels. Windings are positioned within the slot body, while an electrical insulating material, such as varnish or epoxy resin, is applied within the body and step to partially enclose the windings, thereby separating them from the channels and slot walls. The slots are unlined, and the stator core may include annular coolant passages in fluid communication with the channels. Attached Figure Description

[0006] Figure 1 This is a perspective view of the stator.

[0007] Figure 2 It is intercepted along line AA. Figure 1 A top perspective view of the cross-section of the stator.

[0008] Figure 3A It is cut along line BB. Figure 1 A top perspective view of the cross-section of the stator.

[0009] Figure 3B It is intercepted along lines CC and DD. Figure 3AA detailed view of the cross-section of the stator, with the forming tool in place.

[0010] Figure 3C It is intercepted along lines CC and DD. Figure 3A A detailed view of the cross-section of the stator, with the forming tool removed and the windings in place. Detailed Implementation

[0011] Detailed embodiments are disclosed herein. These embodiments are merely examples and may be implemented in various alternative forms. The accompanying drawings are not necessarily drawn to scale. Some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art.

[0012] The directional terminology used herein is made with reference to the views and orientations shown in the accompanying drawings. The central axis is shown in the drawings and described below. Terms such as “outer” and “inner” are relative to the central axis. For example, an “outer” surface means a surface away from the central axis or outside another “inner” surface. Terms such as “radial,” “diameter,” and “circumference” are also relative to the central axis. The terms “front,” “back,” “up,” and “down” indicate directions referenced in the drawings. Unless otherwise explicitly stated or explained above or below, the terms “connection,” “attachment,” etc., refer to direct or indirect connection, attachment, etc.

[0013] The cooling mechanisms described herein influence stator performance by enabling coolant flow within stator slots for in-slot cooling. This allows direct contact between the coolant and the magnetic wires. In-slot cooling facilitates direct axial cooling of the motor windings, thereby improving cooling efficiency and supporting continuous motor operation. Additionally, axial cooling enables bidirectional coolant flow within the stator. These cooling mechanisms may include three components: unit 1, which axially delivers coolant from the stator surface toward its center; unit 2, which radially distributes coolant around the stator circumference; and / or unit 3, which delivers coolant to each slot of the stator via dedicated ports. The coolant flow changes from axial to circumferential distribution in unit 2, and from circumferential to both radial and axial distribution in unit 3. At specific stator laminations, there is overlap between the second and third cooling units, which may occur across adjacent lamination groups.

[0014] When material spillage occurs during the manufacturing of the stator laminations, the cooling efficiency within the slots is affected. This spillage may necessitate additional cleaning steps to remove any spilled material remaining in the slots or seeping into the cooling channels. If not completely removed, it can cause blockage of the coolant flow, thus hindering cooling of the motor's primary heat sources by preventing coolant from flowing to the magnetic wires and stator. Reducing thermal resistance in the magnetic wires further impacts stator efficiency, allowing the motor to continuously maintain peak performance and operate at higher levels for longer periods. This is achieved without the need for additional heaters, thereby maximizing overall efficiency. Higher power density enables shorter stator stack lengths. The system is also scalable, requiring only minor adjustments for implementation on different stators.

[0015] The stator lamination slot design includes stepped features for accommodating the in-slot forming tool and provides a protective stator inner diameter (ID) seal. The lamination features allow for mechanical blocking between the in-slot forming tool and the in-slot cooling passages, preventing forming material from overflowing into these passages. This also prevents forming material from entering the oil passages and stator slot openings, as these areas are critical for in-slot cooling and protecting the stator ID.

[0016] Mechanical obstruction is a result of the forming tool, which is configured to fit within the stator lamination slot and adjacent to a stepped feature to prevent forming material from entering the cooling passage within the slot. Simultaneously, a protective seal positioned on the stator ID prevents forming material from escaping the slot. Furthermore, after the forming tool is removed, forming material remains on the edge of the stepped feature. This remaining forming material can be used to protect the magnetic wires positioned in the slot from direct contact with the steel core, while still maintaining open cooling passages for in-slot cooling.

[0017] Figure 1 An exemplary stator, identified as stator 10, is shown. Stator 10 includes a core 12, windings 14, and high-voltage terminals (not shown). The core 12 consists of a plurality of stacked laminations 20, the total number of which depends on the size requirements of the stator 10. For example, the core 12 may contain as few as 10 laminations or as many as 5,000 laminations. However, other quantities (including fewer than 10, more than 5,000, or any number in between) are also possible and contemplated in this disclosure.

[0018] Each lamination 20 in the stack has a top side and a bottom side. The stacking of laminations 20 can be arranged such that the top or bottom side of one lamination 20 contacts the corresponding top or bottom side of an adjacent lamination 20 to form a stack. Each lamination 20 has an inner diameter and an outer diameter. When the laminations 20 are stacked, the inner diameter of each lamination collectively forms the inner diameter of the stator 10. The inner diameter of the stator 10 defines a stator aperture or cylindrical gap 28 extending through the length of the stator 10 between the first and last laminations 20 in the stack. The outer diameter of each lamination 20 in the stack collectively forms the outer diameter of the stator 10. The outer diameter of the stator 10 defines a cylindrical surface 32 between the first and last laminations 20 in the stack. The stator 10 has a central axis 26, wherein the plurality of laminations 20 are arranged to be aligned and coaxial with the central axis 26, such that the cylindrical gap 28 and the cylindrical surface 32 are concentric with the central axis 26. The stator 10 also includes axial surfaces 30A and 30B. The top surface of the first lamination 20 in the stack defines axial surface 30A, and the bottom surface of the last lamination 20 in the stack defines axial surface 30B. The normal vectors of the two axial surfaces 30A and 30B may be parallel to the central axis 26.

[0019] Each lamination 20 in the stack includes a plurality of teeth 22 extending radially inward toward the inner diameter of the lamination 20. Adjacent teeth 22 of each lamination 20 cooperate to define a radially extending slot between the teeth 22. When the laminations 20 are stacked and oriented such that the teeth 22 of adjacent laminations 20 are aligned, the slots combine to form a plurality of slots 24 that extend axially through the stator 10 between axial surfaces 30A, 30B.

[0020] Winding 14 (also referred to as a coil, wire, or conductor) is wound around core 12 and disposed within axial slot 24. Winding 14 may be insulated with an electrically insulating insulator instead of using a liner, as will be discussed in more detail below. Therefore, slot 24 and insert winding 14 are considered unlined due to the absence of a liner. Once inserted into an electrically insulating insulator, winding 14 may also be embedded in an additional coating or varnish of the electrically insulating insulator. The electrically insulating insulator and / or varnish help stabilize the winding within slot 24. Additionally, the electrically insulating insulator electrically isolates winding 14 from the rest of stator 10. A portion of winding 14 generally extends axially along and through slot 24, while at axial faces 30A, 30B, a portion of winding 14 bends to form end winding 16. End winding 16 extends beyond axial faces 30A, 30B. Winding 14 may be supported by axial slot 24. Although winding 14 is depicted as a hairpin winding, other configurations are possible, such as, but not limited to, random windings, shaped coil windings, overlapping windings, wave windings, distributed windings, fractional slot windings, strip windings, single-layer windings, double-layer windings, and so on.

[0021] The stator 10 includes a cooling fluid delivery sub-stack 34. The cooling fluid delivery sub-stack 34 may include a cooling fluid inlet port 36, an axial channel 38, and a cooling fluid outlet port 40. The cooling fluid delivery sub-stack 34 is configured to axially deliver cooling fluid from an axial face 24 toward the center of the stator 10 via the axial channel 38 extending through some of the laminations 20 in the stack. The cooling fluid inlet port 36 is an orifice on the axial face 24. The axial channel 38 extends axially from the cooling fluid inlet port 36 toward the center of the stator 10 in a direction substantially parallel to the central axis 26. The axial channel 38 terminates at the cooling fluid outlet port 40. The cooling fluid outlet port 40 may be located at the center of the stack. The center of the stack may be defined as an intermediate lamination in the stack. However, the cooling fluid outlet port 40 may be located at a location other than the center of the stack.

[0022] The axial channel 38 is formed by adjacent stacks 20 that cooperate to form the axial channel 38. For example, a portion of the axial channel 38 may be a circular cutout in a single stack of individual stacks 20. When adjacent stacks 20 having this circular cutout are stacked and aligned, they cooperate to form the axial channel 38. The cutout may refer to a hole, opening, aperture, hole, or any other suitable shape that extends through the top and bottom surfaces of the stack 20 and extends between the top and bottom surfaces.

[0023] The cooling fluid outlet port 40 is a channel extending radially inward through the stator 10. The cooling fluid outlet port 40 may be defined by one or more laminations 20. Because the cooling fluid outlet port 40 traverses radially rather than axially, a lamination adjacent to the lamination defining the cooling fluid outlet port 40 is required to seal the outlet port 40. In some embodiments, the cooling fluid outlet port 40 may be defined by a radially extending cut that extends radially through a portion of an adjacent lamination 20 in the stack. In other embodiments, for example, the cooling fluid outlet port 40 is defined by a single lamination 20 in the stack, wherein an adjacent lamination 20 seals the port 40. In this embodiment, the cooling fluid outlet port 40 may be formed at different locations within the stack. The cuts defining the cooling fluid outlet port 40 and a portion of the axial channel 38 may be integral with each other and cooperate to form a single structure that facilitates fluid flow without separate joints or connections. During operation, cooling fluid enters the cooling fluid delivery stack 34 via the cooling fluid inlet port 36, flows axially through the stator 10 along the axial channel 38, and then flows radially inward through the cooling fluid outlet port 40.

[0024] Figure 2 Provided along Figure 1The figure shows a cross-sectional view of the stator 10 taken by line AA, and illustrates an embodiment of the lamination 220 with an annular channel 244. As shown, the lamination 220 is characterized by a plurality of teeth 222 extending radially inward toward the inner circumference 248 of the lamination 220. The space between adjacent teeth 222 defines a slot 224. Here, the slot 224 is shown without a cooling channel, which is... Figures 3A to 3C As shown in the figure. Laminates 220 and 320 ( Figure 3A These can be used interchangeably and may include the same features, but are not explicitly shown herein. When multiple laminations 220 are stacked and oriented such that the teeth 222 of adjacent laminations 220 are aligned, the respective slots 224 combine to form a continuous axial slot extending axially through the stator 10. When multiple laminations 220 are stacked, the inner circumference 248 and outer circumference 250 of each lamination 220 are aligned to form a central void or hole 28 and outer circumference 50 of the stator 10.

[0025] The annular channel 244 is a circular channel partially embedded in the surface of the lamination 220. In this context, embedding means that the channel 244 extends partially through the thickness of the lamination, rather than being completely enclosed within or through the thickness of the lamination. The depth of the annular channel 244 can vary based on cooling requirements. For example, a shallower depth may be sufficient to meet lower coolant flow rate requirements, while a deeper channel can increase coolant volume and flow rate to improve cooling efficiency. The lamination 220 may also include cutouts 242. When multiple laminations with cutouts 242 are stacked, the cutouts 242 in adjacent laminations cooperate to form a cooling fluid outlet port 240.

[0026] Figures 3A to 3C Provided along Figure 1 Another cross-sectional view of the stator 10 taken from line BB is shown, and an embodiment of the lamination 320 with stepped slots 354 is also shown. Figure 3B and Figure 3C It shows along Figure 3AThe figure shows a cross-sectional view of the lamination 320 taken by lines CC and DD, and details of the stepped slot 354 are shown. As shown, the lamination 320 is characterized by a plurality of teeth 322 extending radially inward toward the inner circumference 348 of the lamination 320. The space between adjacent teeth 322 defines the stepped slot 354. As previously described, when the plurality of laminations 320 are stacked and aligned, the individual slots 324 combine to form a continuous axial slot (not shown) extending axially through the stator 10. The stepped slot 354 includes an opening 356 extending through the inner diameter 348 and into the axial clearance or bore 28 of the stator 10. The stepped slot 354 also includes a coolant or oil passage, also referred to as a channel 358, extending radially outward from the stepped slot 354 toward the outer diameter 350. The channel 358 is in fluid communication with an annular channel 244 to receive a coolant supply, as previously discussed. Additionally, a shoulder or step 360 is positioned between the stepped slot main cavity or body 362 and the channel 358. The step 360 is configured as a joining forming tool 370, such as... Figure 3B As shown.

[0027] The body 362 has a body width, the step 360 has a step width, and the channel 358 includes a channel width. The step width is narrower than the body width, and the channel width is narrower than the step width. This width variation allows the forming tool 370 to be placed within the body 362 and engage at least a portion of the channel 358 to seal the channel 358 without completely covering the step 360, allowing the electrical insulating insulator 366 to fill the gap 368 between the forming tool 370 and the stepped slot surface.

[0028] During the electrical insulation filling process, a forming tool 370 is inserted into the stepped slot main cavity or body 362 and positioned to abut or engage a portion of the step 360 and seal the passageway to the channel 358. Once the forming tool 370 is in place, an insulating space or gap 368 is formed between the forming tool 370 and the stepped slot surface, as described above. Additionally, an inner diameter seal 364 is positioned along the inner diameter 348 and configured to seal the slot opening 356 during the electrical insulation filling process. The inner diameter seal 364 may be a sleeve in the insertion hole 28 to cover all slots of the stacked stator. Once the slot opening seal 356 and the forming tool 370 are in place, an electrical insulation 366 is added or injected into the gap 368 using a dispenser 380. Distributor 380 is configured to inject electrically insulating material 366 into stator body 362 to flow around forming tool 370, providing a barrier between metal stator laminations 320 and stator windings 14 after insertion. The electrically insulating material 366 flows around forming tool 370 and fills gaps 368, coating and adhering to the walls and steps 360 of body 362, but does not enter channels 358.

[0029] Once the electrical insulating insulator 366 has cured or hardened, the forming tool 370 and the inner diameter seal 364 are removed, leaving a winding cavity or gap 372 within the stepped slot body 362, such that the winding cavity 372 is surrounded by the hardened electrical insulating insulator 366 and is now configured to receive the stator winding 14. Figure 3C The diagram illustrates the positioning of the winding 14 extending through the stepped slot 354. The illustration shows an electrically insulating insulator 366 extending from the surface of the step 360 and surrounding the gap 368 to isolate the winding 14 from the wall or surface of the lamination 320. This procedure eliminates the need to position the liner within the slot 354 before inserting the winding 14, while still providing insulating properties, resulting in a liner-free stator.

[0030] Electrical insulation 366 can be a varnish. However, other materials can be used, including epoxy resins, silicone compounds, polyurethane resins, polyester resins, impregnating gels, thermoplastic insulating materials, ceramic insulators, fluoropolymer coatings, mica-based insulating materials, etc. These materials offer various benefits, such as thermal management, mechanical protection, and electrical insulation, to meet different application requirements and environmental conditions. Furthermore, electrical insulation 366 can be applied more than once to provide thorough coating and electrical insulation for the parts discussed herein. More specifically, the electrical insulation can be applied multiple times during the molding process.

[0031] Although exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms. Rather, the language used in this specification is descriptive rather than limiting, and it should be understood that various changes can be made without departing from the spirit and scope of the concepts conceived. Furthermore, features of various embodiments can be combined to form other embodiments.

[0032] According to the present invention, an electric motor is provided, the electric motor having: a stator defining a plurality of slots, each slot having a body; a channel narrower than the body, the channel being configured to guide coolant through it; and a step between the body and the channel, the step being narrower than the body and wider than the channel; a winding wound within the body but not within the channel; and an electrically insulating insulator coated on the surfaces of the body and the step but not on the channel to define an electrically insulating barrier between the winding and the slot, such that a portion of the electrically insulating insulator separates the winding from the channel.

[0033] According to one embodiment, the electrical insulating insulator surrounds the winding.

[0034] According to one embodiment, the slot is an unlined slot.

[0035] According to one embodiment, the winding is a hairpin winding.

[0036] According to one embodiment, the hairpin winding is a nested hairpin winding.

[0037] According to one embodiment, the electrical insulating insulator is a varnish.

[0038] According to one embodiment, the electrical insulating insulator is epoxy resin.

[0039] According to one embodiment, the stator further defines an axially extending coolant passage, and the passage is in fluid communication with the axially extending coolant passage.

[0040] According to one embodiment, the stator further defines an annular coolant passage, and the passage is in fluid communication with the annular coolant passage.

[0041] According to the present invention, a stator assembly station is provided, the stator assembly station comprising: a forming tool configured to be disposed within a body and a step of a slot defined by a stator to seal a channel of the slot from the body and the step and to form a gap between the surfaces of the body and the step and the forming tool, such that the gap surrounds the forming tool; and a distributor configured to inject an electrically insulating material into the gap, such that the forming tool prevents the electrically insulating material from entering the channel.

[0042] According to one embodiment, the invention is further characterized by a sleeve configured to be disposed within a hole in the stator to seal the slot from the hole.

[0043] According to one embodiment, the forming tool is configured to be removed from the slot after the electrical insulating insulator has cured, in order to define a gap for inserting a plurality of magnetic windings through it.

[0044] According to the present invention, a stator for an electric motor is provided, the stator having: a plurality of laminations stacked to form a stator core, the stator core defining a plurality of slots, each slot having a body, a step narrower than the body, and a channel narrower than the step; a plurality of windings wound within the body; and an electrically insulating insulator disposed within the body and the step to partially surround the windings and space the windings from the channel and the walls of the body.

[0045] According to one embodiment, the stator core defines an annular coolant passage in fluid communication with the channel.

[0046] According to one embodiment, the slot is an unlined slot.

[0047] According to one embodiment, the electrical insulating insulator is a varnish or epoxy resin.

Claims

1. An electric motor, comprising: The stator defines a plurality of slots, each slot having a body; A channel narrower than the main body, the channel being configured to guide coolant through it; And a step between the body and the channel, the step being narrower than the body and wider than the channel; A winding, which is wound inside the body but not inside the channel; as well as An electrically insulating insulator is coated on the surfaces of the body and the steps but not on the channel to define an electrically insulating barrier between the winding and the slot, such that a portion of the electrically insulating insulator separates the winding from the channel.

2. The motor according to claim 1, wherein the electrical insulating insulator surrounds the winding.

3. The motor according to claim 1, wherein the slot is an unlined slot.

4. The motor according to claim 1, wherein the winding is a hairpin winding.

5. The motor according to claim 4, wherein the hairpin winding is a nested hairpin winding.

6. The motor according to claim 1, wherein the electrical insulation insulator is varnish.

7. The motor according to claim 1, wherein the electrical insulator is epoxy resin.

8. The motor of claim 1, wherein the stator further defines an axially extending coolant passage, and the passage is in fluid communication with the axially extending coolant passage.

9. The motor of claim 1, wherein the stator further defines an annular coolant passage, and the passage is in fluid communication with the annular coolant passage.

10. A stator assembly station, comprising: A forming tool is configured to be disposed within a body and a step of a slot defined by a stator, such that the channel of the slot is sealed from the body and the step and a gap is formed between the surfaces of the body and the step and the forming tool, such that the gap surrounds the forming tool. as well as A distributor configured to inject an electrically insulating insulator into the gap, such that the forming tool prevents the electrically insulating insulator from entering the channel.

11. The stator assembly station of claim 10, further comprising a sleeve configured to be disposed within a hole in the stator to seal the slot from the hole.

12. The stator assembly station of claim 10, wherein the forming tool is configured to be removed from the slot after the electrical insulation has been cured, to define a gap for inserting a plurality of magnetic windings therethrough.

13. A stator for an electric motor, comprising: Multiple laminations are stacked to form a stator core, the stator core defining multiple slots, each slot having a body, a step narrower than the body, and a channel narrower than the step; Multiple windings are wound inside the body; as well as An electrical insulating insulator is disposed within the body and the step to partially surround the winding and space the winding from the walls of the channel and the body.

14. The stator of claim 13, wherein the stator core defines an annular coolant passage in fluid communication with the channel.

15. The stator of claim 13, wherein the slot is an unlined slot.

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