Motor slot liner with enhanced varnish control

Abstract

The present disclosure provides a motor slot liner with enhanced varnish control. An electric machine includes a stator core having an outer circumferential surface, an inner circumferential surface, and longitudinal slots recessed in the inner circumferential surface. Each of the slots has first and second radial walls, an outer circumferential wall extending between the radial walls, an inlet portion having opposing first and second angled walls extending divergently away from the inner circumferential surface, a first shoulder connects the first radial wall to the first angled wall and a second shoulder connects the second radial wall to the second angled wall. A winding is disposed in the slot. A slot liner is also disposed in the slot such that the winding is disposed in an interior of the slot liner. At least one of the slot liners has a first wing and a second wing angled toward each other from opposing sidewalls of the slot liner, where the first wing and the second wing cooperate to define an inner varnish barrier, and the first wing, the second wing, and a corresponding one of the slots cooperate to define an outer varnish barrier.

Description

Technical Field

[0001] The present disclosure relates to electric machines and more particularly to electric machines including slot liners having varnish control features. Background Art

[0002] Vehicles such as all-electric vehicles and hybrid electric vehicles contain a traction battery assembly to serve as an energy source for the vehicle. The traction battery may include components and systems that help manage vehicle performance and operation. The traction battery may also include high voltage components and an air or liquid thermal management system for controlling the battery temperature. The traction battery is electrically connected to an electric motor that provides torque to the drive wheels. An electric motor typically includes a stator and a rotor that cooperate to convert electrical energy into mechanical motion and vice versa. Summary of the invention

[0003] According to one embodiment, an electric machine includes a stator core having an outer circumferential surface, an inner circumferential surface, and longitudinal slots recessed into the inner circumferential surface. Each of the slots has a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, an entrance portion having opposite first angled walls and second angled walls extending divergently away from the inner circumferential surface, a first shoulder connecting the first radial wall to the first angled wall, and a second shoulder connecting the second radial wall to the second angled wall. Windings are disposed in the slots. Slot liners are also disposed in the slots so that the windings are disposed in the interior of the slot liners. At least one of the slot liners has a first wing and a second wing angled toward each other from opposite side walls of the slot liner, wherein the first wing and the second wing cooperate to define an inner varnish barrier, and the first wing, the second wing, and a corresponding one of the slots cooperate to define an outer varnish barrier.

[0004] According to one embodiment, an electric machine includes a stator core having an outer circumferential surface, an inner circumferential surface, and longitudinal slots recessed into the inner circumferential surface. Each of the slots has a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, an inlet portion having opposite first angled walls and second angled walls extending divergently away from the inner circumferential surface, a first shoulder connecting the first radial wall to the first angled wall, and a second shoulder connecting the second radial wall to the second angled wall. Slot liners are disposed in the slots. At least one of the slot liners includes a pair of opposite side walls spaced apart in the circumferential direction of the core, an outer end wall extending between the side walls and cooperating with the side walls to define an interior, a first wing extending from one of the side walls at an angle toward the inner circumferential surface and terminating at an edge engaging with the second angled wall, and a second wing extending from the other of the side walls at an angle toward the inner circumferential surface and terminating at an edge engaging with a surface of the first wing to close the interior. A winding is disposed in the interior of the slot liner.

[0005] According to another embodiment, an electric machine includes a stator core having an outer circumferential surface, an inner circumferential surface, and longitudinal slots recessed into the inner circumferential surface, each of the slots including a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, and an entrance portion. Windings are disposed in the slots. Slot liners are disposed in the slots so that the windings are disposed in the interior of the slot liners. At least one of the slot liners has a pair of opposing side walls, a first wing extending from one of the side walls at an angle toward the inner circumferential surface and terminating at an edge engaging with a side of the slot, and a second wing extending from the other of the side walls at an angle toward the inner circumferential surface and terminating at an edge engaging with a surface of the first wing to close the interior. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram of the motor.

[0007] Figure 2 is a cross-sectional end view of the stator of an electric motor.

[0008] Figure 3 is a detailed view of the stator after varnishing, showing one of the slots, the slot liner, and a plurality of conductors received in the slot liner.

[0009] Figure 4 is a detail view of a stator according to another embodiment.

[0010] Figure 5is a detailed view of a stator according to yet another embodiment. DETAILED DESCRIPTION

[0011] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take on various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show the details of specific components. Therefore, the specific structural details and functional details disclosed herein are not to be interpreted as limiting, but only as a representative basis for teaching those skilled in the art to adopt the present invention in various ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, for specific applications or implementations, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired.

[0012] refer to Figure 1 The electric machine 20 can be used in a vehicle such as an all-electric vehicle or a hybrid electric vehicle. The electric machine 20 may be referred to as an electric motor, a traction motor, a generator, etc. The electric machine 20 may be a permanent magnet motor, an induction motor, etc. In the illustrated embodiment, the electric machine 20 is a three-phase alternating current (AC) motor. The electric machine 20 can be used as a motor to propel the vehicle and as a generator, such as during regenerative braking.

[0013] The motor 20 may be powered by a traction battery of the vehicle. The traction battery may provide a high voltage direct current (DC) output from one or more battery cell arrays (sometimes referred to as battery cell stacks) within the traction battery. The battery cell array may include one or more battery cells that convert stored chemical energy into electrical energy. The battery cell may include a housing, a positive electrode (cathode), and a negative electrode (anode). The electrolyte allows ions to move between the anode and cathode during discharge and then back during recharge. The terminals allow current to flow out of the battery cell for use by the vehicle.

[0014] The traction battery may be electrically connected to one or more power electronics modules. The power electronics modules may be electrically connected to the motor 20 and may provide the ability to transfer electrical energy bidirectionally between the traction battery and the motor 20. For example, a typical traction battery may provide a DC voltage, while the motor 20 may require a three-phase (AC) voltage. The power electronics modules may include an inverter that converts the DC voltage into a three-phase AC voltage as required by the motor 20. In regenerative mode, the power electronics modules may convert the three-phase AC voltage from the motor 20 acting as a generator into the DC voltage required by the traction battery.

[0015] Directional terms used herein are made with reference to the views and orientations shown in the exemplary drawings. A central axis is shown in one or more of 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 that faces away from the central axis or is on the outside of another "inner" surface. Terms such as "radial", "diameter", "circumference", etc. are also relative to the central axis. The terms "front", "rear", "upper" and "lower" represent directions referenced in the drawings. Unless otherwise expressly stated or otherwise stated by upper and lower, the terms "connected", "attached", etc. refer to directly or indirectly connected, attached, etc.

[0016] refer to Figure 1 and Figure 2 , the motor 20 includes a housing 21 that surrounds a stator 22 and a rotor 24. The stator 22 is fixed to the housing 21 and includes a cylindrical core 32 having an inner circumferential surface or inner diameter (ID) defining a hole 30, an outer circumferential surface or outer diameter (OD) 29, and a winding 40. The core 32 may be formed by a plurality of stacked laminations. The rotor 24 is supported to rotate about an axis 27 within the hole 30. The rotor 24 may include windings or permanent magnets that interact with the windings of the stator 22 to produce rotation of the rotor 24 when the motor 20 is energized. The rotor 24 may be supported on a drive shaft 26 that extends through the housing 21 and is concentric with the central axis 27. The drive shaft 26 is configured to be coupled to a drive train of a vehicle.

[0017] The stator core 32 defines slots 34 that are arranged circumferentially around the core 32 and extend outwardly from the inner diameter 28. The slots 34 may be equally spaced around the circumference and extend axially from a first end 36 to a second end 38 of the core 32. In the illustrated embodiment, the core 32 defines forty-eight slots and has eight poles, but in other embodiments, the core 32 may include more or fewer slots and / or poles. For example, the core 32 may define seventy-two slots and have twelve poles.

[0018] Slot liners 35 are received in the slots 34, with one liner 35 in each slot. The liners 35 provide electrical insulation between the stator core 32 and the windings 40. As will be described in more detail below, the liners 35 also include features for controlling varnish flow.

[0019] The winding 40 can be a hairpin type (as shown), distributed or centralized. In an exemplary embodiment, the winding 40 includes a plurality of interconnected hairpins 42. Hairpin windings are an emerging technology for improving the efficiency of electric motors used in vehicles and other applications. The hairpin winding 40 improves efficiency by providing a larger amount of stator conductors to reduce the resistance of the winding 40 without encroaching on the space reserved for electrical steel and magnetic flux paths. The hairpins are generally U-shaped, each of which is bent to include a pair of legs joined by a crown. The hairpins 42 are installed in the stator core 32 by inserting the legs through corresponding slots in the slots 34. All hairpins can be installed from the same end (e.g., end 36) of the stator core 32, so that all crowns are located on one end (e.g., end 36) of the stator, and the ends of the legs are located on the other end (e.g., end 38). Once installed, the legs of the hairpins 42 are bent to form a twisted portion connected to the twisted portions of other hairpins. The ends of the corresponding twisted portions are connected by a connection portion such as a welded portion. Hairpins are typically made of a strip conductor with a rectangular cross-section, but hairpins can have circular or other cross-sectional shapes.

[0020] The winding 40 may include three phases. Each phase includes one or more paths. For example, each phase may include two parallel paths. The paths are formed by a plurality of interconnected hairpins 42 that form a continuous circuit once connected. Each of the paths includes a first end that starts at a terminal and a second end that ends at a neutral connection (e.g., a neutral bar).

[0021] refer to Figure 2 and Figure 3 , for example, each of the slots 34 may include legs 43 of six hairpins 42 disposed within the interior 48 of the liner 35. Each of the slots 34 may include a first radial wall 50 and a second radial wall 52, an outer circumferential wall 54 extending between the radial walls, and an inlet portion 56. The inlet portion 56 opens into the air gap (the space between the stator and the rotor) at the inner diameter 28. The inlet bag portion 56 may have opposing first radial walls 60 and second radial walls 62 extending divergently away from the inner circumferential surface (ID) 28, a first shoulder 64 connecting the first radial wall 50 to the first angled wall 60, and a second shoulder 66 connecting the second radial wall 52 to the second angled wall 62. The angled walls terminate at the ID 28 with a gap or opening 68 defined therebetween. The above-mentioned walls, shoulders, etc. may extend continuously along the entire length of the stator core 32.

[0022] The slot liner 35 may include a pair of opposing side walls 80, 82 spaced apart in the circumferential direction of the core 32. An outer end wall 84 extends between the side walls 80, 82 and cooperates with the side walls to define the interior 48. A first wing 86 extends from the side wall 80 at an angle toward the inner circumferential surface 28 and terminates at an edge 90 that engages the second angled wall 62. A second wing 88 extends from the side wall 82 at an angle toward the inner circumferential surface 28 and terminates at an edge 92 that engages a surface 94 of the first wing 86 to close the interior 48. The above-mentioned walls and wings may be an internally formed part of the liner 35. The liner 35 may have a constant cross-sectional shape along its entire length, wherein the above-mentioned walls and wings extend longitudinally between the opposite ends of the liner 35.

[0023] The stator is varnished after assembly is complete to increase structural rigidity, enhance thermal conduction and provide electrical insulation. The varnish can be applied by a dripping machine with a dripping nozzle. The nozzle can be placed near the end winding and the varnish is applied at the conductor / liner interface and the liner / slot interface to achieve the desired varnish filling in the slot. In order to enhance the retention of the varnish in the slot liner interior 48 and in the gap between the slot and the liner and to prevent the flow of varnish from entering the air gap, a varnish barrier (dam) is provided.

[0024] For example, the wings 86 and 88 cooperate with each other and the stator core to define a varnish barrier configured to inhibit the flow of varnish. Figure 3 In the example of FIG. 1 , the first wing 86 and the second wing 88 cooperate to define an inner varnish barrier 100, and the first wing, the second wing and the slot cooperate to define an outer varnish barrier 102. The inner varnish barrier 100 traps the varnish within the interior 48 of the slot liner 35, while the outer varnish barrier 102 traps the varnish within the slot 34 and mitigates the flow of the varnish into the air gap. The shoulders 64, 66 also engage with the liner 35 and / or the wing 86, 88 to inhibit the flow of varnish from the empty space between the slot 34 and the liner 35 toward the air gap.

[0025] The first wing 86 defines a first angle with the side wall 80, and the second wing defines a second angle with the side wall 82. The second angle can be greater than the first angle, so that the first wing 86 engages the stator core 32, and the second wing 88 engages the first wing 86. However, in other embodiments, this can be reversed. The first wing 86 can also be wider than the second wing 88.

[0026] Figure 3 The embodiment of is but one example of a slot liner cooperating with a slot to define a varnish barrier. Figure 4 and Figure 5 Alternative embodiments of slot liners are described. In these figures, common components will retain their reference numerals and may not be discussed again for the sake of brevity.

[0027] Figure 4 Another liner 110 is shown having a first wing 112 and a second wing 114. The first wing extends from the side wall 116 to a tip 118 that engages the angled wall 62 of the slot 34. Similar to Figure 4 , the second wing 114 extends from the side wall 120 of the liner and has a tip 122 that engages the surface of the first wing 112. In this embodiment, the angle of the wing is increased to increase the size of the inner barrier 124. The first wing 112 is still wider than the second wing, but the angle of the second wing 114 relative to the wall 120 is greater than the angle between the wing 112 and the wall 116 to provide a larger inner barrier 124. Figure 3 In comparison, the size of outer barrier 126 is reduced.

[0028] Figure 5 Another liner 130 is shown having an even larger inner barrier 132. In this embodiment, a first wing 134 extends from the sidewall 135 and at a first angle, thereby forming a first section 136, and then extends circumferentially to form a second section 138. The second section 138 is the entrance or opening 68 of the slot 34. The first section 136 may contact the slot 34 at the shoulder 64 and near the entrance 68. The second section 138 includes an end portion that engages the angled sidewall 62. A second wing 140 extends from the sidewall 142 and at a first angle similar to the first wing 140 of FIG. 1 . Figure 4 The edge 144 of the wing panel 140 engages with the second section 138 (eg, surface 146 ) to close the interior 150 of the slot liner 130 .

[0029] The varnish barrier described above inhibits the flow of varnish to undesirable areas while retaining the varnish in desired areas. This results in more uniform varnish coverage within the slots and slot liners while reducing or eliminating varnish flow within the air gap between the stator and rotor.

[0030] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms covered by the claims. The words used in the specification are descriptive words rather than restrictive words, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As previously described, the features of various embodiments can be combined to form other embodiments of the present invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being superior to other embodiments or prior art implementations in terms of one or more desired characteristics, it will be appreciated by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve the desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, strength, durability, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. For this reason, embodiments described as less desirable than other embodiments or prior art implementations in terms of one or more characteristics are within the scope of the present disclosure and may be desirable for specific applications.

[0031] According to the present invention, there is provided an electric motor, the electric motor having: a stator core, the stator core having an outer circumferential surface, an inner circumferential surface and longitudinal slots recessed into the inner circumferential surface, each of the slots comprising a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, an entrance portion having opposite first angled walls and second angled walls extending divergently away from the inner circumferential surface, a first shoulder connecting the first radial wall to the first angled wall and a second shoulder connecting the second radial wall to the second angled wall; a winding, the winding being arranged in the slot; and a slot liner, the slot liner being arranged in the slot so that the winding is arranged in the interior of the slot liner, at least one of the slot liners having a first wing plate and a second wing plate angled toward each other from opposite side walls of the slot liner, wherein the first wing plate and the second wing plate cooperate to define an inner varnish barrier, and the first wing plate, the second wing plate and a corresponding one of the slots cooperate to define an outer varnish barrier.

[0032] According to one embodiment, the first wing is wider than the second wing.

[0033] According to one embodiment, the first wing defines a first angle with a first sidewall of the opposing sidewalls, and the second wing defines a second angle with a second sidewall of the opposing sidewalls, wherein the second angle is greater than the first angle.

[0034] According to one embodiment, the first wing is wider than the second wing.

[0035] According to one embodiment, the first wing has an edge in contact with a surface of the slot.

[0036] According to one embodiment, the second wing has an edge in contact with a surface of the first wing.

[0037] According to one embodiment, the winding comprises a plurality of interconnected hairpins.

[0038] According to the present invention, there is provided an electric machine, the electric machine having: a stator core, the stator core having an outer circumferential surface, an inner circumferential surface and longitudinal slots recessed in the inner circumferential surface, each of the slots comprising a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, an inlet portion having opposite first angled walls and second angled walls extending divergently away from the inner circumferential surface, a first shoulder connecting the first radial wall to the first angled wall and a second shoulder connecting the second radial wall to the second angled wall; a slot liner, the slot liner being arranged at In the narrow slot, at least one of the narrow slot liners includes: a pair of opposite side walls spaced apart in the circumferential direction of the core, an outer end wall extending between the side walls and cooperating with the side walls to define an interior, a first wing plate extending from one of the side walls at a certain angle toward the inner circumferential surface and terminating at an edge engaged with the second angled wall, and a second wing plate extending from the other of the side walls at a certain angle toward the inner circumferential surface and terminating at an edge engaged with the surface of the first wing plate to close the interior; and a winding, which is arranged in the interior of the narrow slot liner.

[0039] According to one embodiment, the first wing panel, the second wing panel, and the second angled wall cooperate to define an exterior clear coat barrier.

[0040] According to one embodiment, the first wing panel and the second wing panel cooperate to define an interior varnish barrier within the interior.

[0041] According to one embodiment, a surface of the first wing is arranged against the first shoulder to inhibit the varnish from flowing.

[0042] According to one embodiment, a surface of the second wing is disposed against the second shoulder to inhibit varnish flow.

[0043] According to one embodiment, the first wing is wider than the second wing.

[0044] According to one embodiment, the first wing panel includes a portion engaged with the first angled wall.

[0045] According to one embodiment, the first wing comprises a further portion engaging with the first shoulder.

[0046] According to one embodiment, the invention also features a rotor supported for rotation within the stator core.

[0047] According to the present invention, a motor is provided, which comprises: a stator core, the stator core having an outer circumferential surface, an inner circumferential surface and longitudinal slots recessed in the inner circumferential surface, each of the slots comprising a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, and an entrance portion; a winding, the winding being arranged in the slot; and a slot liner, the slot liner being arranged in the slot so that the winding is arranged in the interior of the slot liner, at least one of the slot liners comprising: a pair of opposite side walls, a first wing plate extending from one of the side walls at a certain angle toward the inner circumferential surface and terminating at an edge engaging with the side of the slot, and a second wing plate extending from the other of the side walls at a certain angle toward the inner circumferential surface and terminating at a surface engaging with the first wing plate to close the interior.

[0048] According to one embodiment, the first wing panel, the second wing panel, and the third wall of the second slot cooperate to define an outer varnish barrier.

[0049] According to one embodiment, the first wing panel and the second wing panel cooperate to define an interior varnish barrier within the interior.

[0050] According to one embodiment, the first wing is wider than the second wing.

Claims

1. A motor, comprising: a stator core having an outer circumferential surface, an inner circumferential surface, and longitudinal slots recessed into the inner circumferential surface, each of the slots including a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, an entrance portion having opposing first and second angled walls extending divergently away from the inner circumferential surface, a first shoulder connecting the first radial wall to the first angled wall, and a second shoulder connecting the second radial wall to the second angled wall; a winding disposed in the slot; as well as A slot liner is disposed in the slot so that the winding is disposed in an interior of the slot liner, at least one of the slot liners having a first wing and a second wing angled toward each other from opposite side walls of the slot liner, wherein the first wing and the second wing cooperate to define an inner varnish barrier, and the first wing, the second wing, and a corresponding one of the slots cooperate to define an outer varnish barrier. 2 . The electric machine of claim 1 , wherein the first wing plate is wider than the second wing plate. 3 . The motor of claim 1 , wherein the first wing plate defines a first angle with a first sidewall of the opposing sidewalls, and the second wing plate defines a second angle with a second sidewall of the opposing sidewalls, wherein the second angle is greater than the first angle. The electric machine of claim 3 , wherein the first wing plate is wider than the second wing plate. 5 . The motor of claim 1 , wherein the first wing plate has an edge in contact with a surface of the slot. 6 . The motor of claim 5 , wherein the second wing plate has an edge in contact with a surface of the first wing plate.

7. The electric machine of claim 1 wherein said winding comprises a plurality of interconnected hairpins.

8. A motor, comprising: a stator core having an outer circumferential surface, an inner circumferential surface, and longitudinal slots recessed into the inner circumferential surface, each of the slots including a first radial wall and a second radial wall, an outer circumferential wall extending between the radial walls, an entrance portion having opposing first and second angled walls extending divergently away from the inner circumferential surface, a first shoulder connecting the first radial wall to the first angled wall, and a second shoulder connecting the second radial wall to the second angled wall; a slot liner disposed in the slot, at least one of the slot liners comprising: a pair of opposing side walls, the pair of opposing side walls being spaced apart in a circumferential direction of the core, an outer end wall extending between the side walls and cooperating with the side walls to define an interior, a first wing extending from one of the side walls at an angle toward the inner peripheral surface and terminating at an edge that joins the second angled wall, and a second wing panel extending from the other of the side walls at an angle toward the inner peripheral surface and terminating at an edge engaging a surface of the first wing panel to close the interior; as well as A winding is disposed in the interior of the slot liner.

9. The electric machine of claim 8, wherein the first wing panel, the second wing panel, and the second angled wall cooperate to define an exterior varnish barrier.

10. The electric machine of claim 8, wherein the first wing panel and the second wing panel cooperate to define a varnish barrier within the interior.

11. The motor of claim 8, wherein a surface of the first wing plate is disposed against the first shoulder to inhibit varnish flow.

12. The motor of claim 11, wherein a surface of the second wing is disposed against the second shoulder to inhibit the varnish from flowing.

13. The electric machine of claim 8, wherein the first wing is wider than the second wing.

14. The electric machine of claim 8, wherein the first wing includes a portion that engages the first angled wall, and the first wing includes another portion that engages the first shoulder.

15. The electric machine of claim 8, further comprising: A rotor is supported for rotation within the stator core.

Images