CN116914958A - Integrated stator cooling jacket system - Google Patents

Abstract

The application relates to an electric machine comprising a housing and a stator mounted in the housing. The stator is formed from a plurality of stator laminations arranged in a first lamination stack and a second lamination stack that is circumferentially offset from the first lamination stack. The first lamination stack and the second lamination stack form a coolant flow path that extends circumferentially around and axially through the stator. Each of the plurality of stator laminations of the first lamination stack and the second lamination stack includes a body having an inner surface section and an outer surface section. A plurality of cooling passage defining members are integral with and extend radially outwardly from the outer surface section. The plurality of cooling passage defining members form a coolant flow path extending circumferentially in the first plurality of passages and extending axially through the stator in the second plurality of passages.

Description

Integrated stator cooling jacket system

Cross Reference to Related Applications

The present application is a continuation-in-part application of U.S. non-provisional application Ser. No.16/739,264, filed 1/10/2020, which claims the benefit of earlier filing date of U.S. provisional application Ser. No.62/793,215, filed 1/16/2019, the entire disclosure of which is incorporated herein by reference.

Technical Field

Exemplary embodiments relate to the field of electric motors, and more particularly, to electric motors with integrated stator cooling systems.

Background

During operation, the electric motor generates heat. Typically, the rotating components of the electric motor may support a fan member that directs airflow through the internal motor components. The airflow may be helpful for smaller systems (e.g., alternators) and systems installed in open areas. In high output systems, especially those installed in enclosed areas, such as motor vehicle cabins, the airflow is not always sufficient.

Electric motors used as prime movers in motor vehicles typically include a liquid coolant system. The electric motor includes a stator and a rotor formed from a plurality of stator laminations. The liquid cooling system may include an inlet to receive the coolant and an outlet to direct the coolant to the heat exchange system. The coolant may flow in a jacket arranged radially outside the stator of the electric motor. Specifically, coolant may flow down through smaller openings in the housing onto the end turns of the stator windings. The coolant moves over the end turns and turns to the outlet. Transferring heat from the end turns to the coolant reduces a portion of the overall thermal characteristics of the electric motor. However, the end turns have a relatively small surface area relative to the overall size of the stator, thereby limiting cooling efficiency.

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 defined at an inner surface of the housing. Heat may flow from the stator through the housing into the coolant passing through the cooling jacket. Indirect contact between the coolant and the surface to be cooled limits the heat transfer capacity. 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 total area of the stator laminations. Accordingly, the industry will accept electric motor cooling systems that transfer heat directly from the larger surface area of the stator into the coolant to increase cooling efficiency.

Disclosure of Invention

An electric machine includes a housing having an outer surface, an inner surface, a coolant inlet and a coolant outlet, and a stator mounted in the housing. The stator includes a stator core formed from a plurality of stator laminations arranged in a first lamination stack and a second lamination stack that is circumferentially offset from the first lamination stack. The first lamination stack and the second lamination stack form a coolant flow path that extends circumferentially around and axially through the stator. Each of the plurality of stator laminations of the first lamination stack and the second lamination stack includes a body having an inner surface section including a plurality of stator teeth and a plurality of cooling channels defining a member integrally formed with and extending radially outwardly from the outer surface section. The plurality of cooling passage defining members form a coolant flow path extending circumferentially in the first plurality of passages and extending axially through the stator in the second plurality of passages.

The present application also discloses a stator comprising a stator core formed of a plurality of laminations arranged in a first lamination stack and a second lamination stack, the second lamination stack being circumferentially offset from the first lamination stack. The first lamination stack and the second lamination stack form a coolant flow path that extends circumferentially around and axially through the stator. Each of the plurality of laminations of the first lamination stack and the second lamination stack 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 passage defining members are integrally formed with and extend radially outwardly from the outer surface section. The plurality of cooling passage defining members form a coolant flow path extending circumferentially in the first plurality of passages and extending axially through the stator in the second plurality of passages.

Drawings

The following description should not be taken as limiting in any way. Referring to the drawings, like elements are numbered alike:

FIG. 1 depicts an electric motor including a stator formed from a plurality of stator laminations in accordance with an aspect of an exemplary embodiment;

FIG. 2 depicts stator laminations of the stator of FIG. 1;

FIG. 3 depicts radial misalignment of stator laminations arranged in a first lamination stack with stator laminations of a second lamination stack in accordance with an aspect of an exemplary embodiment;

FIG. 4 depicts a coolant flow path formed by a plurality of stator lamination stacks defining the stator of FIG. 1;

FIG. 5 depicts a partially exploded view of the stator of FIG. 1 showing a first end ring and a second end ring mounted to a stator lamination in accordance with a non-limiting example;

FIG. 6 depicts a first end ring and a second end ring mounted to stator laminations in accordance with a non-limiting example;

FIG. 7 is a plan view of an inner surface of a second end ring illustrating directing coolant to coolant injection slots on stator end turns according to a non-limiting example;

FIG. 8 is a partial cross-sectional view of a stator core depicting coolant flow from coolant injection slots onto stator end turns according to a non-limiting example; and

fig. 9 is a cross-sectional view of the electric motor of fig. 1 according to a non-limiting example.

Detailed Description

A detailed description of one or more embodiments of the disclosed apparatus and method is provided herein by way of example and not limitation with reference to the accompanying drawings.

Referring first to FIG. 1, an electric motor according to a non-limiting example is indicated generally 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 coolant outlet 24 may vary. The electric motor 10 includes a stator 26 disposed in the housing 14. The stator 26 includes a stator core 28 having a first axial end 29 and a second axial end 30 opposite the first axial end 29. The stator core 28 is coupled to the inner surface 18 of the housing 14. The stator 26 includes a first end turn 32 and a second end turn 34. In a non-limiting example, the coolant inlet 22 and the coolant outlet 25 are radially aligned and disposed axially inward from each axial end 29, 30 of the stator 26.

According to a non-limiting example, the stator 26 is formed from a plurality of stator laminations 37 having an outer diameter 38, which will be described in more complete detail herein. Stator laminations 37 are arranged in a plurality of lamination packs including a first lamination pack 39 and a second lamination pack 41. The number of lamination packs may vary. The second lamination stack is circumferentially offset with respect to the first lamination stack 39. In one embodiment, second lamination stack 41 may be circumferentially offset from first lamination stack 39 by approximately 30 °.

In a non-limiting example, first lamination stack 39 is formed from a first plurality of laminations 42 that are spaced apart from one another by a respective one of a first plurality of channels 44. Similarly, the second lamination stack 41 is formed from a plurality of laminations, such as those spaced from one another by a respective one of a second plurality of channels 48, indicated at 46. The first plurality of channels 44 and the second plurality of channels 48 form part of a coolant flow path (not separately labeled) that extends circumferentially around the plurality of laminations 37.

In a non-limiting example, the plurality of laminations 37 are formed by stacking and interleaving a first plurality of laminations 42 of the first lamination stack 39 with corresponding laminations in a second plurality of laminations 46 forming the second lamination stack 41. In a non-limiting example, each of the second plurality of laminations 46 is circumferentially staggered from a corresponding lamination of the first plurality of laminations 42 forming the first lamination stack 39. The circumferential offset creates a first plurality of channels 44 and a second plurality of channels 48. Each of the first plurality of passages 44 is axially and circumferentially offset relative to a corresponding passage of each of the second plurality of passages 48. In a non-limiting example, the inner surface 18 of the housing 14 defines the outer boundaries of the first plurality of channels 46 and the second plurality of channels 48 and thus forms the surface of the coolant flow path 50. One of a first plurality of stator laminations 42 that may form a portion of first lamination stack 39 will now be described with reference to fig. 2. Stator laminations 42 include a body 54 having an inner surface section 56 and an outer surface section 58. The inner surface section 56 supports a plurality of radially inwardly projecting stator teeth 60. According to an exemplary embodiment, the outer surface section 58 supports a plurality of cooling passage defining members, one of which is indicated at 64. In this regard, it should be appreciated that each of the second plurality of laminations 46 includes a second plurality of cooling passage defining members, such as shown at 66 in FIG. 3. Further, it should be appreciated that the first plurality of laminations 42 and the second plurality of laminations 46 can be similarly formed.

In one embodiment, each cooling passage defining member 64 is radially offset from an adjacent cooling passage defining member 64 by about 30 °. It should be appreciated that the number of cooling passage defining members 64 may vary, as may the offset between adjacent cooling passage defining members 64. Furthermore, the staggering may be different from or may be substantially the same as the staggering between adjacent lamination stacks.

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 68 is also spaced from the outer surface section 58 to form a first cooling channel portion 72, and the second circumferentially extending portion 70 is spaced from the outer surface section 58 to form a second cooling channel portion 73.

Each of the first plurality of stator laminations 42 includes an opening 83 formed in each of the plurality of cooling passage defining members 64 and a partial opening 85 formed in the third cooling passage portion 80. First lamination stack 39 and second lamination stack 41 may be staggered relative to one another and joined together as shown in fig. 3. In one embodiment, each circumferentially extending portion 68, 70 may include a recess or notch (not separately labeled) on an outer surface portion (also not separately labeled). The recess forms a coupling element receiving region that may assist in coupling the stator 26 to the inner surface 18 of the housing 14. In this regard, it should be appreciated that each of the second plurality of stator laminations 46 are similarly formed.

In one embodiment, a first plurality of stator laminations 42 (e.g., six (6) stator laminations) can be joined to form a first lamination stack 39. Similarly, a second plurality of stator laminations 46 (e.g., six (6) stator laminations) can be joined to form a second lamination stack 41 that is circumferentially staggered with respect to and coupled to the first lamination stack 39. That is, each lamination 42 may be interleaved with each lamination 46 when forming lamination stacks 39 and 41. Additional lamination packs may be formed and joined together, each lamination pack being staggered with respect to the other lamination pack to form a stator 26 such as shown in fig. 4. In this regard, it should be appreciated that the number of laminations in the lamination stack may vary. Furthermore, although channels 44 and 48 are shown as having a thickness of a single lamination, the thickness of each channel 44 and 48 may be varied by adjusting how many laminations are combined prior to interleaving.

In a non-limiting example, when first lamination stack 39 and second lamination stack 41 are combined, separate coolant paths are formed as shown in fig. 4. That is, coolant (e.g., oil) entering coolant inlet 22 (fig. 1) enters channels 44 and 48 and flows circumferentially around stator core 30. The coolant passes axially through the coolant flow path defined by the first and second cooling gallery portions 72, 73, through the first and second pluralities of passages 44, 48, and into the coolant outlet 24. Dividing the coolant flow into channels 44 and 48 via first cooling channel portion 72 and second cooling channel portion 73 reduces the pressure drop of the coolant and thereby improves stator cooling efficiency.

In a non-limiting example, a portion of the coolant entering the coolant inlet 22 flows counter-clockwise through the passage 44 until reaching the cooling passage portion 72. The coolant flows into the cooling passage portion 72 in both axial directions. A portion of the coolant may flow out of the cooling passage portion 72 and into the passage 48 counterclockwise. A second portion of the coolant flow may flow axially out of the channels 72 and onto the stator end turns 32 and/or 34. Additional coolant may enter the channels 48 and then enter the cooling channel portion 73. The second portion of the coolant may flow through the cooling channel portion 73 in the channel 73 in both axial directions. A third portion of the coolant may flow into an adjacent one of the channels 44 and/or may flow axially outward onto the stator end turns 32 and/or 34. This pattern repeats itself counterclockwise until all of the coolant is axially discharged from the cooling passage portions 72 and 73.

In the non-limiting example shown in fig. 5, the first end ring 87 and the second end ring 88 may be mounted on opposite sides of the stator core 30. The first end ring 87 and the second end ring 88 may be connected by a plurality of mechanical fasteners, one of which is indicated at 91, extending through a respective one of the openings 83 and portions 85 in the first lamination stack 39 and the second lamination stack 41, as shown in fig. 6. As will be described in detail herein, the end rings 87 and 88 cooperate with the coolant flow path defined by the first and second cooling channel portions 72 and 73 to deliver coolant to the first and second end turns 32 and 34 of the stator 26.

In the non-limiting example shown in fig. 7, the end ring 88 includes a plurality of openings, one of which is shown at 100, that receive a respective one of a plurality of mechanical fasteners 95. The end ring 88 includes an inner surface 110 that abuts one of the plurality of laminations 37. In a non-limiting example, the inner surface 110 includes a plurality of locator elements 118 that orient the end ring 88 to the stator core 30. That is, the locator elements 118 establish a selected circumferential alignment of the end rings 88 relative to the stator core 30.

In a non-limiting example, the inner surface 110 of the end ring 88 includes a plurality of coolant injection slots 130 aligned with one of the passages 44 and 48 and/or the coolant flow path defined by the first and second cooling passage portions 72 and 73. The coolant injection slots 130 direct coolant onto the end turns 32 as shown in FIG. 8. In this manner, the coolant not only reduces the operating temperature of the stator core 30, but also reduces the stator end turn temperature. It should be appreciated that although the coolant injection slots are described as being located on the inner surface 110 of the end ring 88, additional coolant slots (not shown) are also provided on the end ring 87.

According to the non-limiting example shown in fig. 9, the coolant 100 enters the coolant inlet 22 and essentially branches into a first coolant flow portion 108 and a second coolant flow portion 110. The first coolant flow portion 108 enters the coolant flow path 50 and flows circumferentially clockwise around the stator 26 within the first and second pluralities of channels 44, 48. The second coolant flow portion 110 flows circumferentially counterclockwise around the stator 26 within the first and second pluralities of passages 44, 48.

Upon reaching channels 72 and 73, a portion of first coolant flow 108 and second coolant flow 110 flow axially through stator 26. At this point, coolant 100 exits the channels 72 and 73 at each of the first and second axial ends 28 and 30 and is sprayed onto a respective one of the first and second end turns 32 and 34. The coolant continues to flow around and through the first and second end turns 32, 34 and drips to the bottom (not separately labeled) of the housing 14. The coolant 100 gathers at the bottom of the housing 14 and is discharged through the coolant outlet 25.

In one non-limiting example, as shown in fig. 1 and 9, the coolant inlet 22 is positioned axially inward from the first axial end 28 and the second axial end 30. The coolant outlet 25 is disposed axially outwardly from the first axial end 28 and the second axial end 30. In addition, the electric motor 10 includes a rotor (not shown) having a hollow rotor shaft (also not shown) that may carry coolant that is sprayed onto the inner diameter 120 (FIG. 1) of the stator 26.

In this regard, it should be appreciated that the exemplary embodiments describe a stator that includes radially outwardly extending protrusions that each include a circumferentially extending portion that forms a serpentine or serpentine cooling channel. With this arrangement, the additional surface area of the stator laminations is exposed to the cooling fluid, thereby enhancing the heat dissipation capability. The heat dissipation capacity may be increased by as much as 50% or more compared to existing systems. Furthermore, the increased surface area of the stator laminations provides the stator with increased magnetic flux carrying capacity, which can improve performance by up to 5%. Thus, the present application not only provides additional cooling, but also increases the overall operating efficiency of the electric motor.

The term "about" is intended to include the degree of error associated with a measurement based on a particular amount of equipment available at the time of filing the application. For example, "about" may include a range of + -8%, or 5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. 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 the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the application has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the application. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the application without departing from the essential scope thereof. Therefore, it is intended that the application not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this application, but that the application will include all embodiments falling within the scope of the appended claims.

Claims (21)

1. An electric machine, comprising:

a housing having an outer surface, an inner surface, a coolant inlet, and a coolant outlet; and

a stator mounted in the housing, the stator comprising a stator core formed of a plurality of stator laminations arranged in a first lamination stack and a second lamination stack, the second lamination stack being circumferentially offset from the first lamination stack, the first lamination stack and the second lamination stack forming a coolant flow path extending circumferentially around the stator and axially through the stator, each of the plurality of stator laminations of the first lamination stack and the second lamination stack comprising:

a body having an inner surface section and an outer surface section, the inner surface section comprising a plurality of stator teeth; and

a plurality of cooling channel defining members integrally formed with and extending radially outwardly from the outer surface section, the plurality of cooling channel defining members forming a coolant flow path extending circumferentially in a first plurality of channels and axially through the stator in a second plurality of channels.

2. The electric machine of claim 1, wherein each of the plurality of stator laminations of the first lamination stack is substantially similar to each of the plurality of stator laminations forming the second lamination stack.

3. The electric machine of claim 2, wherein an inner surface of the housing forms a surface of the coolant flow path.

4. The electric machine of claim 3, wherein each of the first plurality of channels is circumferentially offset from each of the second plurality of channels by about 30 °.

5. The electric machine of claim 3, wherein the plurality of cooling passage defining members comprises: a first plurality of cooling channel defining members on each of the plurality of stator laminations defining the first lamination set and the first cooling channel portion, and a second plurality of cooling channel defining members on each of the plurality of stator laminations defining the second lamination set and the second cooling channel portion, the second plurality of cooling channel defining members being circumferentially spaced from the first cooling channel portion.

6. The electric machine of claim 5, wherein the housing includes a coolant inlet fluidly connected to the first and second cooling channel portions, the coolant inlet receiving coolant flowing into the electric machine.

7. The electric machine of claim 6, wherein a first portion of the flow of coolant through the coolant inlet flows circumferentially clockwise around the plurality of stator laminations and a second portion of the flow of coolant through the coolant inlet flows circumferentially counterclockwise around the plurality of stator laminations.

8. The electric machine of claim 6, wherein the plurality of stator laminations include a first axial end and a second axial end opposite the first axial end, the coolant inlet being located between the first axial end and the second axial end.

9. The electric machine of claim 3, further comprising: an end ring mounted to the stator core, the end ring including a coolant injection slot fluidly connected to one of the first plurality of channels and the second plurality of channels.

10. The electric machine of claim 9, wherein the stator includes end turns positioned adjacent the coolant injection slots.

11. The electric machine of claim 1, wherein the first plurality of channels includes an axial thickness corresponding to an axial thickness of at least one of the plurality of stator laminations.

12. A stator, comprising:

a stator core formed from a plurality of laminations arranged in a first lamination stack and a second lamination stack circumferentially offset from the first lamination stack, the first and second lamination stacks forming a coolant flow path extending circumferentially around and axially through the stator, each of the plurality of laminations of the first and second lamination stacks comprising:

a body having an inner surface section and an outer surface section, the inner surface section comprising a plurality of stator teeth; and

a plurality of cooling passage defining members integrally formed with and extending radially outwardly from the outer surface section, the plurality of cooling passage defining members forming a coolant flow path extending circumferentially in the first plurality of passages and axially through the stator in the second plurality of passages.

13. The stator of claim 12, wherein each of the plurality of laminations of the first lamination stack is substantially similar to each of the plurality of laminations forming the second lamination stack.

14. The stator of claim 13, wherein each of the first plurality of channels is circumferentially offset from each of the second plurality of channels by about 30 °.

15. The stator of claim 13, wherein the plurality of cooling channel defining members comprises: a first plurality of cooling passage defining members on each of a plurality of laminations defining the first lamination stack and first cooling passage portion; and a second plurality of cooling passage defining members on each of the plurality of laminations defining the second lamination stack and second cooling passage portion, the second plurality of cooling passage defining members being circumferentially spaced from the first cooling passage portion.

16. The stator of claim 15, further comprising: a coolant inlet fluidly connected to the first and second cooling channel portions, the coolant inlet receiving coolant flowing into the stator.

17. The stator of claim 16, wherein a first portion of the flow of coolant through the coolant inlet flows circumferentially clockwise around the plurality of laminations and a second portion of the flow of coolant through the coolant inlet flows circumferentially counterclockwise around the plurality of laminations.

18. The stator of claim 16, wherein the plurality of laminations include a first axial end and a second axial end opposite the first axial end, the coolant inlet being located between the first axial end and the second axial end.

19. The stator of claim 14, further comprising: an end ring mounted to the stator core, the end ring including a coolant injection slot fluidly connected to one of the first plurality of channels and the second plurality of channels.

20. The stator of claim 19, wherein the stator includes end turns positioned adjacent the coolant injection slots.

21. The stator of claim 12, wherein each of the first plurality of channels comprises an axial thickness corresponding to an axial thickness of at least one of the plurality of laminations.