Integrated stator cooling jacket system

Abstract

An electric machine includes a stator formed by a plurality of stator laminations arranged in a first lamination group and a second lamination group, the second lamination group being circumferentially offset from the first lamination group. The first lamination group and the second lamination group form a tortuous flow path extending axially through the stator. Each of the plurality of stator laminations of the first lamination group includes a body having an inner surface section and an outer surface section. The inner surface section includes a plurality of stator teeth. A plurality of cooling channel defining members are integrally formed with the outer surface section and extend radially outward from the outer surface section. Each of the plurality of cooling channel defining members is spaced apart from other cooling channel defining members of the plurality of cooling channel defining members by a corresponding gap.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of the earlier filing date of U.S. Provisional Application Serial No. 62 / 793,215, filed on January 16, 2019, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] Exemplary embodiments relate to the field of electric motors, and more particularly, to electric motors with integrated stator cooling systems. Background Art

[0004] During operation, electric motors generate heat. Often, the rotating components of the electric motor may support a fan member that directs air flow through the internal motor components. The flow of air may be helpful in smaller systems, such as alternators, and systems mounted in open areas, such as generators. In high output systems, the flow of air is not always adequate, particularly those mounted in enclosed areas, such as a motor vehicle engine compartment.

[0005] An electric motor used as a prime mover in a motor vehicle typically includes a liquid coolant system. The electric motor includes a stator and a rotor formed by a plurality of stator laminations. The liquid cooling system may include an inlet for receiving the coolant and an outlet for directing the coolant to a heat exchange system. The coolant may flow in a jacket disposed radially outside of the stator of the electric motor. Specifically, the coolant may flow down to the end turns of the stator windings through a small opening in the housing. The coolant flows through the end turns and flows to the outlet. Transferring heat from the end turns to the coolant reduces a portion of the overall thermal signature of the electric motor. However, the end turns have a relatively small surface area relative to the overall size of the stator, thereby limiting the cooling efficiency.

[0006] Other systems rely on direct contact between the outer surface of the stator and the inner surface of the motor housing. In some cases, a cooling jacket may be confined at the inner surface of the housing. Heat may flow from the stator through the housing into the coolant passing through the cooling jacket. The indirect contact between the coolant and the surface to be cooled limits the heat transfer capability. In other systems, heat may be transferred from the outer surface of the stator to the coolant flowing through the housing. The outer surface of the stator has a relatively small surface area when considered relative to the overall area of ​​the stator laminations. Therefore, the industry will accept an electric motor cooling system that transfers heat directly from the larger surface area of ​​the stator to the coolant to increase cooling efficiency. Summary of the invention

[0007] The present disclosure discloses an electric machine, which includes a housing having an outer surface, an inner surface, a coolant inlet and a coolant outlet. A stator is mounted in the housing. The stator is formed by a plurality of stator laminations arranged into a first lamination group and a second lamination group, the second lamination group being circumferentially offset from the first lamination group. The first lamination group and the second lamination group form a tortuous flow path extending axially through the stator. Each of the plurality of stator laminations of the first lamination group includes a body having an inner surface section and an outer surface section. The inner surface section includes a plurality of stator teeth. A plurality of cooling channel defining members are integrally formed with the outer surface section and extend radially outward from the outer surface section. Each of the plurality of cooling channel defining members is spaced apart from other cooling channel defining members of the plurality of cooling channel defining members by a corresponding gap.

[0008] A stator lamination is also disclosed, comprising a body having an inner surface section and an outer surface section, the inner surface section comprising a plurality of stator teeth. A plurality of cooling channel defining members are integrally formed with the outer surface section and extend radially outward from the outer surface section. Each of the plurality of cooling channel defining members is spaced apart from other cooling channel defining members of the plurality of cooling channel defining members by a corresponding gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following description should not be considered limiting in any way. Referring to the accompanying drawings, like elements are numbered alike:

[0010] Figure 1 An electric motor including a stator formed from a plurality of stator laminations is depicted according to one aspect of the exemplary embodiment;

[0011] Figure 2 Depicted Figure 1 stator laminations of a stator;

[0012] Figure 3 depicts stator laminations in a first lamination stack arranged radially offset from stator laminations in a second lamination stack according to one aspect of the exemplary embodiment;

[0013] Figure 4 Depicts a serpentine coolant passage formed by a plurality of stator lamination stacks defining Figure 1 stator; and

[0014] Figure 5 A stator formed from stator laminations coupled by stator end rings is depicted according to one aspect of the exemplary embodiment. DETAILED DESCRIPTION

[0015] With reference to the accompanying drawings, a detailed description of one or more embodiments of the disclosed apparatus and methods is given herein, by way of example and not limitation.

[0016] First reference Figure 1 , an electric motor according to an exemplary embodiment is generally indicated at 10. The electric motor 10 includes a housing 14 having an outer surface 16 and an inner surface 18. The housing 14 also includes a coolant inlet 22 and a coolant outlet 24. The specific location and orientation of the coolant inlet 22 and the coolant outlet 24 can vary. The electric motor 10 includes a stator 30 disposed in the housing 14. The stator 30 is coupled to an end wall (not separately labeled) of the housing 14. The stator 30 includes a first end turn 32 and a second end turn 34.

[0017] The stator 30 is formed of a plurality of stator laminations 37, which will be described more fully herein. The stator laminations 37 are arranged into a plurality of lamination groups, including a first lamination group 39 and a second lamination group 41. The number of lamination groups can vary. The second lamination group is radially offset relative to the first lamination group 39. In one embodiment, the second lamination group 41 can be radially offset from the first lamination group 39 by approximately 30°.

[0018] Now refer to Figure 2 The stator lamination 48 is depicted. The stator lamination 48 may form part of the first lamination set 39. The stator lamination 48 includes a body 54 having an inner surface segment 56 and an outer surface segment 58. The inner surface segment 56 supports a plurality of radially inwardly projecting stator teeth 60. According to an exemplary embodiment, the outer surface segment 58 supports a plurality of cooling channel defining members, one of which is indicated at 64.

[0019] In one embodiment, each cooling channel defining member 64 is radially offset by approximately 30° from an adjacent cooling channel defining member 64. It should be appreciated that the number of cooling channel defining members may vary with the offset between adjacent cooling channel defining members. Furthermore, the offset may be different than the offset between adjacent lamination stacks, or may be substantially the same as the offset between adjacent lamination stacks.

[0020] According to an exemplary embodiment, each cooling passage defining member 64 includes a first circumferentially extending portion 68 and a second circumferentially extending portion 70. The first circumferentially extending portion 68 is spaced apart from the second circumferentially extending portion 70 by a gap 71. The first circumferentially extending portion is also spaced apart from the outer surface segment 58 to establish a first cooling passage portion 72, and the second circumferentially extending portion 70 is spaced apart from the outer surface segment 58 to establish a second cooling passage portion 73. A third cooling passage portion 80 extends between adjacent first circumferentially extending portions 68 and second circumferentially extending portions 70.

[0021] Each stator lamination 48 includes an opening 83 formed in each of the plurality of cooling channel defining members 64 and a partial opening 85 formed in the third cooling channel portion 80. The first lamination set 39 and the second lamination set 41 may be offset relative to each other, and as shown in FIG. Figure 3In one embodiment, each circumferentially extending portion 68, 70 may include a groove (also not separately labeled) on an outer surface portion (not separately labeled). The groove forms a coupling element receiving area that can help couple the stator 30 to the inner surface 18 of the housing 14.

[0022] In one embodiment, several stator laminations, such as six (6) stator laminations, may be coupled to form a first lamination stack 39. Similarly, several stator laminations, such as six (6) stator laminations, may be coupled to form a second lamination stack 41. Additional lamination stacks may be formed and coupled together, each stack offset relative to another stack to form the stator 30, such as Figure 4 as shown in .

[0023] The first end ring 87 and the second end ring 88 can be installed and the laminations can be connected by a plurality of mechanical fasteners, one of which is shown at 91 and extends through the corresponding opening 83 and a portion of the opening 85, such as Figure 5 In this manner, the first cooling channel portion 72, the second cooling channel portion 73, and the third cooling channel portion 80 may be joined to form a serpentine cooling channel (not individually labeled) extending axially through the stator 30. A cooling fluid may pass through the cooling channel between the exterior surface segment 58 and the interior surface 18 of the housing 14.

[0024] At this point, it should be understood that the exemplary embodiments describe a stator that includes radially outwardly extending protrusions, each of which includes circumferentially extending portions that establish a tortuous or serpentine cooling channel. With this arrangement, additional surface area of ​​the stator laminations is exposed to the cooling fluid, thereby enhancing the heat dissipation capability. The heat dissipation capability can be increased by up to 50% or more compared to existing systems. In addition, the increased stator lamination surface area provides increased stator flux carrying capacity, which can increase performance by up to 5%. Therefore, the present invention not only provides additional cooling, but also increases the overall operating efficiency of the electric motor.

[0025] The term "about" is intended to include the degree of error associated with the measurement of a particular quantity based on the equipment available at the time the application was filed. For example, "about" may include a range of ±8% or 5%, or 2% of a given value.

[0026] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when used in this specification, the terms "comprise" and / or "comprising" indicate the presence of stated features, wholes, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements and / or groups thereof.

[0027] Although the present invention has been described with reference to one or more exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made without departing from the scope of the present invention, and equivalents may be substituted for its elements. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present invention without departing from the basic scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed as the best mode for carrying out the present invention, but the present invention will include all embodiments falling within the scope of the claims.

Claims

1. An electric machine comprising: a housing having an outer surface, an inner surface, a coolant inlet, and a coolant outlet; as well as a stator mounted in the housing, the stator being formed of a plurality of stator laminations arranged in a first lamination group and a second lamination group, the second lamination group being circumferentially offset from the first lamination group, the first lamination group and the second lamination group forming a tortuous flow path extending axially through the stator, each of the plurality of stator laminations in the first lamination group comprising: a body having an inner surface segment and an outer surface segment, the inner surface segment including a plurality of stator teeth; and a plurality of cooling channel defining members integrally formed with the outer surface segment and extending radially outward from the outer surface segment, each of the plurality of cooling channel defining members being spaced apart from other of the plurality of cooling channel defining members by a corresponding gap, wherein the plurality of cooling channel defining members of the first lamination stack and the plurality of cooling channel defining members of the second lamination stack form a first cooling channel portion, a second cooling channel portion, and a third cooling channel portion, the third cooling channel portion extending circumferentially between the first cooling channel portion and the second cooling channel portion.

2. The electric machine according to claim 1, wherein: Each of the plurality of cooling channel defining components includes a first circumferentially extending portion and a second circumferentially extending portion spaced apart from the outer surface segment, wherein the first circumferentially extending portion and the second circumferentially extending portion are located on opposite sides of the cooling channel defining component, and the first circumferentially extending portion of the first lamination stack overlaps the second circumferentially extending portion of the second lamination stack to form at least one coolant passage.

3. The electric machine according to claim 2, wherein: The first circumferentially extending portion extends in a first direction and the second circumferentially extending portion extends in a second direction, wherein the first direction is a counterclockwise direction and the second direction is a clockwise direction, and the first circumferentially extending portion is spaced apart from the second circumferentially extending portion.

4. The electric machine according to claim 2, wherein: The first cooling channel portion is defined between the exterior surface segment and the first circumferentially extending portion, the second cooling channel portion is defined between the second circumferentially extending portion, and the third cooling channel portion is defined between the first cooling channel portion and the second cooling channel portion.

5. The electric machine according to claim 4, further comprising: A partial opening is defined in the third cooling channel portion.

6. The electric machine of claim 5, further comprising: An opening is formed in each of the plurality of cooling-passage-defining members, the opening being positioned to align with a portion of the opening in the second lamination stack.

7. The electric machine of claim 2, further comprising: A first groove is formed in an outer circumferential edge of the first circumferentially extending portion and a second groove is formed in an outer circumferential edge of the second circumferentially extending portion.

8. The electric machine according to claim 1, wherein: Each cooling channel defining member is spaced 30° apart from an adjacent cooling channel defining member.

9. A stator lamination comprising: a body having an inner surface segment and an outer surface segment, the inner surface segment including a plurality of stator teeth; as well as A plurality of cooling channel defining members are integrally formed with the outer surface segment and extend radially outward from the outer surface segment, each of the plurality of cooling channel defining members being spaced apart from other cooling channel defining members of the plurality of cooling channel defining members by a corresponding gap, wherein the plurality of cooling channel defining members arranged in a first lamination group in the stator laminations and the plurality of cooling channel defining members arranged in a second lamination group in the stator laminations form a first cooling channel portion (72), a second cooling channel portion (73) and a third cooling channel portion (80), the second lamination group being circumferentially offset from the first lamination group, and the third cooling channel portion extending circumferentially between the first cooling channel portion and the second cooling channel portion.

10. The stator lamination according to claim 9, wherein: Each of the plurality of cooling passage defining members includes a first circumferentially extending portion and a second circumferentially extending portion spaced apart from the outer surface segment, wherein the first circumferentially extending portion and the second circumferentially extending portion are located on opposite sides of the cooling passage defining member.

11. The stator lamination according to claim 10, wherein: The first circumferentially extending portion extends in a first direction and the second circumferentially extending portion extends in a second direction, the first circumferentially extending portion being spaced apart from the second circumferentially extending portion, wherein the first direction is a counterclockwise direction and the second direction is a clockwise direction.

12. The stator lamination according to claim 10, wherein: The first cooling channel portion is defined between the exterior surface segment and the first circumferentially extending portion, the second cooling channel portion is defined between the second circumferentially extending portion, and the third cooling channel portion is defined between the first cooling channel portion and the second cooling channel portion.

13. The stator lamination according to claim 12, further comprising: A partial opening is defined in the third cooling channel portion.

14. The stator lamination according to claim 13, further comprising: An opening is formed in each of the plurality of cooling-passage-defining members, the opening being positioned to align with a portion of an opening in another stator lamination stack.

15. The stator lamination of claim 10, further comprising: A first groove is formed in an outer circumferential edge of the first circumferentially extending portion and a second groove is formed in an outer circumferential edge of the second circumferentially extending portion.

16. The stator lamination according to claim 9, wherein: Each cooling channel defining member is spaced 30° apart from an adjacent cooling channel defining member.

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