Slot liner cooling for electric machines

Abstract

A stator for an electric motor includes an annular body and a plurality of radially inner slots. The stator defines a cooling fluid domain having a fluid inlet and a cooling fluid sleeve located at a radially outer portion of the stator. The cooling fluid domain also includes a plurality of cooling fluid connectors. Each cooling fluid connector extends from the cooling fluid sleeve to a corresponding radially inner slot such that each of the plurality of radially inner slots receives cooling fluid.

Description

Technical Field

[0001] Electric motors are typically cooled using fluids directed to various parts of the motor. As the power demands of motors continue to increase over time, improving cooling remains a key focus. Therefore, innovations that improve the cooling of internal motor components will be welcomed. Background Technology

[0002] An embodiment of a stator for an electric motor is disclosed, the stator comprising an annular body and a plurality of radially inward slots. The stator defines a cooling fluid domain having a cooling fluid sleeve and a fluid inlet located at a radially outward portion of the stator. The cooling fluid domain also includes a plurality of cooling fluid connectors. Each cooling fluid connector extends from the cooling fluid sleeve to a corresponding radially inward slot, such that each of the plurality of radially inward slots receives cooling fluid.

[0003] An embodiment of an electric motor is also disclosed, comprising a stator having an annular body and a rotor located radially inward of the stator. The stator includes an annular body and a plurality of radially inward slots. The stator defines a cooling fluid domain having a cooling fluid sleeve and a fluid inlet located at a radially outward portion of the stator. The cooling fluid domain also includes a plurality of cooling fluid connectors. Each cooling fluid connector extends from the cooling fluid sleeve to a corresponding radially inward slot, such that each of the plurality of radially inward slots receives cooling fluid.

[0004] An embodiment of a method for cooling stator conductors in an electric motor is also disclosed. The method includes providing cooling fluid to a fluid domain at a cooling fluid inlet on the radially outer side. The cooling fluid domain defines a cooling fluid sleeve at a portion of the radially outer side of the stator. The fluid domain also defines a plurality of fluid connectors, each extending from the cooling fluid sleeve to a corresponding radially inner groove. A portion of the cooling fluid domain defined within each radially inner groove is separated. Attached Figure Description

[0005] The following description should not be considered as limiting in any way. Referring to the accompanying drawings, the same parts are designated with the same reference numerals: Figure 1 This is based on a quarter-end view of an example motor; Figure 2 yes Figure 1 A quarter-wavelength isometric view of the fluid domain of the motor; Figure 3A An example is shown. Figure 2 Metering characteristics of the fluid domain; Figure 3B An example is shown. Figure 2 The flow-limiting characteristics of the fluid domain; Figure 3C An example is shown. Figure 2 The flow-limiting characteristics of the fluid domain; Figure 4 It shows Figure 1 The stator winding slots are isolated from the rest of the motor; Figure 5 An example is shown for... Figure 4 Slot liners in the stator winding slots; Figure 6 It shows Figure 5 The slot liner includes conductor windings according to an example; Figure 7 It shows Figure 6 The fluid domain of the liner; Figure 8 An example is shown for... Figure 4 Replacement slot liners for stator winding slots; Figure 9A A partial view of the groove liner, including a set of rectangular support pins, is shown in isometric view. Figure 9B A partial side view of the groove liner including a set of rectangular support pins is shown; Figure 10A A partial view of the groove liner, including a set of circular support fins, is shown in isometric view. Figure 10B A partial view of the groove liner, including a set of circular support fins, is shown in a side view taken along the circumference. Figure 11A A partial view of the groove liner, including a set of airfoil-shaped support fins, is shown in isometric view. Figure 11B A partial view of the groove liner, including a set of airfoil-shaped profiles supporting the fins, is shown in a side view taken along the circumference. Figure 12A A partial view of the groove liner, including a set of serrated support fins, is shown in isometric view. Figure 12B A partial view of the groove liner, including a set of serrated support fins, is shown in a side view taken along the circumference. Figure 13 An isometric view of the groove liner including the recessed channels of the serrated flow path is shown; and Figure 14 An alternative fluid domain with the radially outer cooling jacket omitted is shown; Figure 15 It shows Figure 1An axial end view of a single replacement slot structure for the motor; and Figure 16 It shows Figure 15 An isometric view of a single alternative slot structure. Detailed Implementation

[0006] Referring to the accompanying drawings, one or more embodiments of the disclosed apparatus and methods are described in detail by way of example and not limitation.

[0007] Referring to the operation of a general-purpose electric motor, when the motor is running, each component of the motor (e.g., rotor laminations, stator laminations, magnets, conductors, etc.) generates electromagnetic losses. These losses act as heat on the components, causing the motor temperature to rise. Existing motors provide cooling by using cooling jackets, fluid jets on the winding turns, and / or fluid cooling via internal cooling paths in the rotor.

[0008] When a motor operates at its highest performance, the greatest losses typically occur in the conductors within the stator, causing a corresponding increase in temperature at the stator conductors. If the temperature exceeds a certain high level (e.g., 180°C to 200°C), it will shorten the conductor insulation life, thereby reducing the effective life of the motor.

[0009] Figure 1 A partial end view of the motor is shown. This partial end view is a quarter view of the stator portion 100 of a 72-slot motor. The stator portion 100 includes 18 slots 110 located at a radially inward edge 102 of the stator portion 100. Each slot 110 includes a slot liner 112 and a set of conductors 114. The gap between the slot liner 112 and the conductors 114 forms a fluid domain through which cooling fluid passes. The fluid cooling flow and fluid domain characteristics described herein can also be used in other machine designs, including motors with different numbers and / or arrangements of slots.

[0010] During operation, the conductors 114 within the stator section 100 generate heat. In some existing systems, heat is dissipated through cooling paths (or cooling jackets) defined by the outer surface of the stator. However, since most of the heat generated by the conductors is located at the inner edge 102 of the stator section 100, cooling achieved by applying cooling fluid to the outer surface or only to the channels 104 located at the radial outer edge 106 can be improved by allowing the cooling fluid to flow directly through each channel 110.

[0011] Even within the system (where cooling fluid typically flows to tank 110), the thermal resistance between the heating and cooling sources of the existing system, generated by the tank liner 112, still hinders cooling. To overcome this thermal resistance, each tank is separated by a parallel thickness, thereby providing two main cooling paths and thus improving the cooling capacity of the stator 100.

[0012] Figure 1 The structure shown provides cooling in direct contact with conductor 114, thereby improving cooling efficiency. In addition to separating the cooling path, the construction of the slot liner 116 provides a combination of functions including voltage isolation, fluid flow path control, and holding conductor 114 in the correct position within the slot 110.

[0013] Continue to refer to Figure 1 , Figure 2 An isometric negative space view of the fluid within the stator section 100 is provided. This fluid negative space view is also known as the fluid domain 200.

[0014] The fluid domain 200 includes an inlet 202 at which cooling fluid is received and enters the stator section 100. The inlet 202 is connected to an outer peripheral cooling fluid section 204. The outer peripheral cooling fluid section 204 defines a channel 104. Each slot 110 is connected to the channel 104 via a corresponding cooling fluid connector 210.

[0015] exist Figure 14 In an alternative embodiment shown, the fluid domain 1400 within the stator section 100 omits the outer peripheral cooling fluid section 204. Figure 2 The outer peripheral cooling fluid section is replaced with a shorter axial cooling fluid distribution channel 1402. (Similar to...) Figure 2 In one embodiment, the fluid domain 1400 includes an inlet 202 connected to a cooling fluid distribution channel 1402, which provides cooling fluid to each cooling fluid connector 210. Figure 14 Alternative embodiments can be used in motors that do not require cooling around the stator, thus allowing the motor to be shorter in the axial direction.

[0016] Continue to refer to Figure 1 and Figure 2 , Figures 3A-3C End views of various configurations of the cooling fluid connector 210 are shown. Any given stator section 100 can utilize one, two, or all of the variations of the cooling fluid connector 210 within a single component, and these variations are not mutually exclusive.

[0017] Each fluid connector 210 receives cooling fluid from its radially outer end 302 and delivers the cooling fluid to the flow-limiting section 304. In the first example ( Figure 3A The flow-limiting section 304 is an inclined portion of the outer wall that defines the fluid connector 210 and throttles the flow path 306 through the fluid connector 210. In the second example ( Figure 3B The flow-limiting section 304 is a circular portion of the outer wall that defines the fluid connector 210, which functions largely similar to... Figure 3A Cooling fluid flow restriction section 304. In the third example ( Figure 3CThe flow-limiting section 304 is a flat wall section that is perpendicular or approximately perpendicular to the flow path 306.

[0018] Downstream of the flow-limiting section 304, the flow path 306 splits into two parallel paths 310 and 312, each supplying cooling fluid to one of the first partition 212 and the second partition 214 of the corresponding slot 110. The cooling fluid travels through the slot 110 and is ejected from each axial end of the slot 110, thereby providing further cooling to any components radially inward of the stator section 100. In one example, such components include the rotor section of an electric motor.

[0019] In some cases, the ejected cooling fluid can be recovered via a corresponding cooling fluid recovery mechanism using known methods. In other cases, depending on the needs of a given motor, the type of cooling fluid used, or any other relevant factors, the cooling fluid may be considered depleted and not recovered.

[0020] Continue to refer to Figures 1-3C , Figure 4 An end view of a single groove 110 including groove liner 410 is shown. Figure 5 The groove liner 410 of groove 110 is shown. Figure 6 The slot liner 410 is shown with the conductor winding 416 in place. Figure 7 The fluid domain 418 defined by the slot liner 410 and the conductor winding 416 is shown.

[0021] The slot liner 410 is non-conductive and includes a set of fins 412, 414 projecting inward from the slot liner 410. A conductor winding 416 is defined within the slot liner 410 and provides the electrical winding for the stator. The conductor winding 416 is held in place relative to the slot liner 410 by sub-group fins 412, each sub-group fin including one or more fins in contact with each conductor winding 416. The space between the slot liner 410, the conductor winding 416, and the fins 412, 414 defines a fluid domain 418.

[0022] In some examples, the subgroup fin 412 that holds the conductor winding 416 in place is longer than the remaining fins 414.

[0023] In some examples, the set of fins 412, 414 may include a variety of fin shapes, lengths, and cross-sections. The specific shape, length, cross-section, and similar dimensions of each fin 412, 414 can be customized to give the cooling fluid flowing around the fins 412, 414 specific flow characteristics, depending on the needs of a given motor (including the motor's operating parameters and the environment in which the motor is expected to operate).

[0024] During operation, fins 412 and 414 agitate the flow of cooling fluid, thereby improving cooling performance by disrupting the boundary layer within the fluid flow near the liner 410.

[0025] Continue to refer to Figures 1-8 , Figure 9A An isometric view including fins 900 with a rectangular outline is shown. Figure 9B An axial side view of a fin 900 with a rectangular profile is shown. As used herein, the profile of fin 900 refers to the two-dimensional cross-sectional shape of fin 900. Figure 9B In the example, the liner 902 includes two sets of fins 900 (900' and 900").

[0026] The first set of fins 900' extends outward from the slot liner 902 in a circumferential length sufficient to contact the conductor 114 inside the slot. Figure 1 The first set of fins 900' serves both as a structural support to hold the conductor 114 in the correct circumferential position in the slot and as a turbulence generator to apply turbulence to the cooling fluid flow.

[0027] The second set of fins 900” extends outward from the liner 902 in a circumferential length shorter than the circumferential length required to contact the conductor 114 inside the liner, and is used only to apply turbulence to the cooling fluid flow.

[0028] In an alternative example, fins 900 can all belong to group 900', and group 900 can be omitted.

[0029] Continue to refer to Figures 1-8 , Figure 10A A partial isometric view of a groove liner 1002 including fins 1000 with a circular profile is shown. Figure 10B A circumferential side view of a groove liner 1002 including fins 1000 with a circular profile is shown. Figure 10A In the example, all fins 1000 extend the same circumferential distance from the groove liner 1002. In an alternative example, such as Figure 9A and Figure 9B Like fin 900, fin 1000 can be extended to different lengths.

[0030] Continue to refer to Figures 1-8 , Figure 11A An isometric view of the groove liner 1102, including the fin 1160 with an airfoil profile, is shown. Figure 11B A circumferential side view of a slot liner 1102 including fins 1160 with an airfoil profile is shown. In the example of Figure 11, all fins 1160 extend from the slot liner 1102 by the same circumferential distance. In an alternative example, such as Figure 9B Like fin 900, fin 1100 can be extended to different lengths.

[0031] Continue to refer to Figures 1-8 , Figure 12AAn isometric view and a circumferential side view (12B) of a groove liner 1202 including fins 1200 with a serrated profile are shown. Figure 12A In the example, all fins 1000 extend the same circumferential distance from the groove liner 1002. In an alternative example, such as Figure 9B Like fin 900, fin 1200 can be extended to different lengths.

[0032] Continue to refer to all Figure 1-Figure 1 2, Figure 9A , Figure 10A , Figure 11A and Figure 12A Example fins 900, 1000, 1160, and 1200 can be used in combination within a single slot liner, and / or different slots within a single stator structure can include... Figure 9A , Figure 10A , Figure 11A and Figure 12A Arrangement of any combination of fins. In some alternative embodiments, one or more of the fins 900, 1000, 1160, 1200 may not extend perpendicular to the surfaces of the liner 902, 1002, 1102, 1202, but rather extend obliquely relative to the surfaces of the liner 902, 1002, 1102, 1202.

[0033] exist Figure 13 In another embodiment shown in the isometric view, Figure 13 The serrated fin structure can be inverted, causing a set of channels 1300 to be circumferentially pressed into the wall 1304 of the slot liner 1302. In such an example, the wall 1304 contacts the conductor 114 and maintains the conductor's circumferential positioning within the slot.

[0034] In some examples, for example Figure 8 In an alternative example shown, the slot liner 410 may include a separated radially inner conductor segment 802. The separated conductor segment 802 receives the radially innermost conductor winding and is not exposed to the cooling fluid flow. When sufficient cooling is provided via the remaining cooling flow, it can be used... Figure 8 Alternative examples.

[0035] Continue to refer to Figures 1-14 , Figure 15 and Figure 16 A single slot 1510 of an alternative construction of the stator 1500 is shown. As... Figure 1 In this example, slot 1510 accommodates a set of conductors 1514 forming a stator winding. Slot liner 112 is located in slot 1510 and surrounds conductors 1514. Conductors 1514 are held in place within slot liner 1510 by a set of fins 1512 extending from a wall 1501 of slot liner 1510. The set of fins 1512 presses conductors 1514 against circumferentially opposite walls 1509.

[0036] In some examples, only a portion of the subgroup of fins in the fin group 1512 extends circumferentially from the slot liner 1501 to the conductor 1514. This configuration provides that: a first subgroup of fins in the fin group 1512 holds the conductor 1514 in place; and a second subgroup of fins in the fin group 1512 does not hold the conductor 1514 in place.

[0037] The liner 1510 defines a gap 1513, which is connected to the channel 1504 via a fluid connector 1505. The channel 1504 is substantially similar to... Figure 1 The channel 104. The fluid connector 1505 includes a flow restrictor 1507, which is designed to connect with... Figure 3A , Figure 3B and Figure 3C It is constructed in the same manner as any of the flow-limiting sections in the flow-limiting section 304.

[0038] The fin outlines in this set of fins 1512 can be compared with... Figure 9A , Figure 9B , Figure 10A , Figure 10B , Figure 11A , Figure 11B , Figure 12A or Figure 12B Matches any of the contours shown, or with Figure 9A , Figure 9B , Figure 10A , Figure 10B , Figure 11A , Figure 11B , 12A or Figure 12B The provided contours are provided by any combination of the outlines shown.

[0039] In the context of describing the invention (especially in the context of the appended claims), unless otherwise stated herein or clearly contradicted by the context, the use of the terms “a” and “an” and similar designations such as “the” should be interpreted to cover both singular and plural. Furthermore, it should be noted that the terms “first,” “second,” etc., used herein do not indicate any order, quantity, or importance, but are used to distinguish one element from another. The terms “about,” “substantially,” and “generally” are intended to include the degree of error associated with a measurement of a specific quantity based on the equipment available at the time of filing. For example, “about” and / or “substantially” and / or “generally” can include a range of ±8% of a given value.

[0040] Although the invention has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from the scope of the invention. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from the basic scope of the invention. Therefore, the invention is not limited to the specific embodiments disclosed as the best mode for carrying out the invention, but rather the invention will include all embodiments falling within the scope of the claims. Moreover, exemplary embodiments of the invention have been disclosed in the drawings and description, and although specific terminology may have been used, it is used in a general and descriptive sense only, and not for limiting purposes, unless otherwise stated; therefore, the scope of the invention is not so limited.

Claims

1. A stator for an electric motor, the stator comprising: Annular body and multiple radially inner grooves; The stator defines a cooling fluid domain having a cooling fluid sleeve and a fluid inlet located at a radially outer portion of the stator. The cooling fluid domain also includes a plurality of cooling fluid connectors, each extending from the cooling fluid sleeve to a corresponding radially inner slot, such that each of the plurality of radially inner slots receives cooling fluid.

2. The stator according to claim 1, further comprising: Each of the plurality of radially inner slots includes a slot liner and a plurality of conductor windings; and A portion of the cooling fluid domain defined within each radially inner groove is separated.

3. The stator according to claim 2, wherein, Each slot liner includes a set of fins extending toward one of the plurality of conductor windings housed in the slot, the fins being configured to agitate cooling fluid flowing around the fins in the set of fins.

4. The stator according to claim 3, wherein, The subgroup of fins in each group of fins contacts at least one corresponding conductor winding and holds at least one corresponding conductor winding in place within the slot on the radially inner side.

5. The stator according to claim 3, wherein, At least a portion of each fin group includes an airfoil cross section configured to impart specific flow characteristics to the cooling fluid flowing around the fin, thereby disrupting the boundary layer of the cooling fluid flow.

6. The stator according to claim 2, wherein, Each of the plurality of fluid connectors includes a radially outward inlet, a flow-limiting section, and a separating outlet.

7. The stator according to claim 6, wherein, The flow restrictor includes a flow path contraction section, which is immediately downstream of at least one of the following: a sidewall that is inclined relative to the direction of cooling fluid flow, a sidewall that is curved relative to the direction of cooling fluid flow, and a sidewall that is substantially perpendicular to the direction of cooling fluid flow.

8. The stator according to claim 1, wherein, Each slot includes multiple conductor windings, wherein at least one of the conductor windings is isolated from the cooling fluid by the slot liner.

9. The stator according to claim 1, wherein, The cooling fluid domain includes a fluid outlet at each axial end of each slot in the radially inner groove.

10. The stator according to claim 1, further comprising: Each of the plurality of radially inner slots includes a slot liner and a plurality of conductor windings; Each of the plurality of radially inner slots includes a set of windings located within the slot liner and held in place at least partially via contact with a set of fins extending from a first radially aligned wall of the slot liner and with a second radially aligned wall of the slot liner.

11. An electric motor, comprising: The stator includes a ring-shaped main body; The rotor is located radially inside the stator; The stator includes multiple radially inward slots, each slot including a slot liner and multiple conductor windings; and The stator defines a cooling fluid domain having a cooling fluid sleeve and a fluid inlet located at a radially outer portion of the stator. The cooling fluid domain also includes a plurality of cooling fluid connectors, each extending from the cooling fluid sleeve to a corresponding radially inner groove, wherein a portion of the cooling fluid domain defined within each radially inner groove is partitioned.

12. The motor of claim 11, wherein each slot liner includes a set of fins extending toward one of the plurality of conductor windings received in the slot, the fins being configured to agitate cooling fluid flowing around the fins in the set of fins.

13. The motor according to claim 12, wherein, The subgroup of fins in each group of fins contacts at least one corresponding conductor winding and holds at least one corresponding conductor winding in place within the slot on the radially inner side.

14. The motor according to claim 12, wherein, At least a portion of each fin group includes an airfoil cross section configured to impart specific flow characteristics to the cooling fluid flowing around the fin, thereby disrupting the boundary layer of the cooling fluid flow.

15. The motor according to claim 11, wherein, Each of the plurality of fluid connectors includes a radially outward inlet, a flow-limiting section, and a separating outlet.

16. The motor according to claim 15, wherein, The flow restrictor includes a flow path contraction section, which is immediately downstream of at least one of the following: a sidewall that is inclined relative to the direction of cooling fluid flow, a sidewall that is curved relative to the direction of cooling fluid flow, and a sidewall that is substantially perpendicular to the direction of cooling fluid flow.

17. The motor according to claim 11, wherein, The slot liner includes a plurality of conductor windings, wherein at least one of the conductor windings is isolated from the cooling fluid by the slot liner.

18. The motor according to claim 11, wherein, Each of the plurality of groove liners is non-conductive.

19. The motor according to claim 1, wherein, The cooling fluid domain includes a fluid outlet at each axial end of each slot in the radially inner groove.

20. A method for cooling stator conductors in an electric motor, the method comprising: Cooling fluid is supplied to a cooling fluid domain at a cooling fluid inlet on the radially outer side, wherein the cooling fluid domain defines a cooling fluid sleeve at a portion of the stator on the radially outer side, the cooling fluid domain also defining a plurality of cooling fluid connectors, each cooling fluid connector extending from the cooling fluid sleeve to a corresponding groove on the radially inner side, and wherein a portion of the cooling fluid domain defined in each groove on the radially inner side is separated.

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