Optimization of motor stator insulating paint

Abstract

An electric motor includes a stator having a stator core comprised of a ferromagnetic material and having a stator outer surface. The stator core includes a stator core body and a plurality of stator teeth extending therefrom. The plurality of stator teeth define conductor slots therebetween. The stator also includes a plurality of stator conductors disposed within the conductor slots. The stator additionally includes a slot liner disposed within each conductor slot and surrounding a corresponding stator conductor. A first gap is established between each stator conductor and a corresponding slot liner, and a second gap is established between each slot liner and an adjacent stator tooth. And a predetermined amount of insulating paint disposed within the first gap and the second gap to limit an amount of open space within the first gap and the second gap without the insulating paint and to adjust viscous damping of the motor.

Description

Technical Field

[0001] The present disclosure relates to optimizing insulation varnish application in electric motor stators. Background Art

[0002] An electric motor is a machine that converts electrical energy into mechanical energy. Electric motors can be configured as either alternating current (AC) or direct current (DC) types. The operation of an electric motor is based on the electromagnetic interaction between permanent magnets and the magnetic field generated by the machine's selectively energized coils. Electric motors are classified into two categories based on the direction of the magnetic field: axial flux motors and radial flux motors. Typically, axial flux motors include a rotor located inside a corresponding stator, while radial flux motors have a rotor located alongside the stator.

[0003] As a byproduct of the torque produced, electric motors generate heat, which can adversely affect motor performance and reliability. Therefore, cooling the electric motor can remove thermal stresses experienced by the motor poles or windings and provide longer motor life at or below peak load. Electric motor cooling can also enhance motor operation at higher speeds and facilitate reduced motor inertia and packaging. Motor cooling is typically provided by circulating oil, which can also be used to reduce friction between internal motor components. Summary of the Invention

[0004] An electric motor includes a stator having a stator core constructed of ferromagnetic material and having a stator outer surface. The stator core includes a stator core body and a plurality of stator teeth extending therefrom. The plurality of stator teeth define conductor slots therebetween. The stator also includes a plurality of stator conductors disposed within the conductor slots. The stator further includes a slot liner disposed within each conductor slot and surrounding the corresponding stator conductor. A first gap is established between each stator conductor and the corresponding slot liner, and a second gap is established between each slot liner and an adjacent stator tooth. A predetermined amount of insulating varnish is disposed within each of the first and second gaps and is configured to limit the amount of open space within the first and second gaps that is free of the insulating varnish. In this manner, the amount of insulating varnish adjusts the viscous damping and noise, vibration, and harshness (NVH) characteristics of the electric motor.

[0005] The electric motor may further include a lubrication system configured to supply oil to the stator. During operation of the electric motor, a portion of the oil may fill open spaces within the first gap and the second gap that are free of insulating paint, thereby affecting noise, vibration, and harshness (NVH) characteristics of the electric motor.

[0006] The insulating varnish may fill 80% of each of the first gap and the second gap.

[0007] The insulating varnish may be arranged away from relatively high vibration or resonance angular positions.

[0008] The insulating varnish disposed away from the relatively high vibration angle position may fill more than 90% of each of the first gap and the second gap.

[0009] The insulating varnish arranged near the relatively high vibration angle position may fill 50% of each of the first gap and the second gap.

[0010] In side view, the stator core may comprise a plurality of adjacent stator laminations arranged along the axis of rotation.The amount of insulating varnish may vary axially, ie along the axis of rotation.

[0011] In a plan view, the stator core may include a plurality of circumferentially arranged mounting bosses defining motor restraint positions. A relatively high vibration angular position may be provided between the mounting bosses, and a predetermined amount of insulating varnish may be applied within first and second gaps between the mounting bosses.

[0012] In a side view, the stator core may include a first stator end and an opposite second stator end. A mounting boss may be arranged on the first stator end, and the insulating varnish may fill more than 90% of each of the first gap and the second gap axially adjacent to the mounting boss.

[0013] The stator may include a stator inner diameter (ID) and a stator outer diameter (OD), and the amount of insulating varnish may vary in a radial direction between the stator ID and the stator OD.

[0014] Each slot liner can include a first slot liner portion and a second slot liner portion. In such an embodiment, the first slot liner portion can be configured to partially surround a corresponding stator conductor, and the second slot liner portion can be configured to partially surround the subject stator conductor and overlap the first slot liner portion.

[0015] The motor can have either radial or axial flux configuration.

[0016] A motor vehicle having the electric motor described above is also disclosed.

[0017] The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the embodiments and the best mode for carrying out the described disclosure when taken in conjunction with the accompanying drawings and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of a motor vehicle having a powertrain utilizing an electric motor-generator for propulsion.

[0019] Figure 2 According to the present disclosure Figure 1 A schematic close-up, partially cut-away perspective view of a radial flux embodiment of the electric motor-generator shown in , depicting a stator defining stator teeth and having conductors disposed within conductor slots and slot liners surrounding the conductors.

[0020] Figure 3 According to the present disclosure Figure 2 Schematic partial plan or front view of an embodiment of a stator shown in , showing representative adjacent stator teeth, a two-piece slot liner surrounding a conductor, a first gap and a second gap established via the slot liner, and a variable amount of insulating varnish disposed in the gaps.

[0021] Figure 4 According to an embodiment of the present disclosure Figure 2 A schematic plan or front view of the motor-generator shown in , illustrating the high resonance location arranged between the stator mounting bosses.

[0022] Figure 5 According to the present disclosure Figure 2 A schematic close-up cross-sectional side view of a radial flux motor-generator shown in , depicting a fluid circulation system configured to supply oil to first and second gaps between stator teeth. DETAILED DESCRIPTION

[0023] The embodiments of the present disclosure as described herein are intended to be used as examples. Other embodiments may take various and alternative forms. In addition, the drawings are generally schematic and not necessarily drawn to scale. Some features may be exaggerated or minimized to illustrate details of specific components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the present disclosure in various ways.

[0024] Certain terms may be used in the following description for reference purposes only and are therefore not intended to be limiting. For example, terms such as "upper" and "lower" refer to directions in the drawings to which reference is made. Terms such as "front," "back," "front," "rear," "left," "right," "rear," "side," "upward," "downward," "top," and "bottom" describe the orientation and / or position of parts of components or elements within a consistent but arbitrary reference frame, which becomes clear by reference to the text and related drawings describing the components or elements in question.

[0025] In addition, terms such as "first," "second," "third," etc. may be used to describe individual components. Such terminology may include the words specifically mentioned above, their derivatives, and words of similar meaning, and is used descriptively with respect to the drawings and does not represent a limitation on the scope of the present disclosure as defined by the appended claims. Furthermore, the teachings herein may be described in terms of functional and / or logical block components and / or various processing steps. It should be appreciated that such block components may include a plurality of hardware, software, and / or firmware components configured to perform the specified functions.

[0026] refer to Figure 1 , depicts a motor vehicle 10 having a powertrain 12. The motor vehicle 10 may include, but is not limited to, a commercial vehicle, an industrial vehicle, a passenger car, an airplane, a boat, a train, etc. It is also contemplated that the motor vehicle 10 may be a mobile platform, such as an airplane, an all-terrain vehicle (ATV), a boat, a personal mobility device, a robot, etc., for purposes of the present disclosure. The powertrain 12 includes a first power source 14, which is depicted as an electric motor-generator and is configured to generate a first power source torque T1 ( Figure 1 ) for propelling the motor vehicle 10 relative to the road surface via driven wheels 16. The motor-generator 14 may be configured as a radial flux motor (e.g., Figure 2 and Figure 4 ), wherein the magnetic flux is generated perpendicular to the motor's axis of rotation, and the air gap between the motor's rotor and stator is arranged concentrically with the axis of rotation. Alternatively, the motor-generator 14 can be configured as an axial flux motor (not shown, but understood by those skilled in the art), wherein the magnetic flux is generated coaxially with the motor's axis of rotation, and the air gap between the motor's rotor and stator is arranged perpendicular to the axis of rotation. For the sake of brevity, the remainder of this description will primarily focus on the radial flux configuration of the motor-generator 14.

[0027] like Figure 1As shown, the powertrain 12 may also include a second power source 20, such as an internal combustion engine configured to generate a second power source torque T2. Power sources 14 and 20 may cooperate to power the motor vehicle 10 and are operably connected to a transmission assembly 22. The transmission assembly 22 may be configured to transmit the first power source torque T1 and / or the second power source torque T2 to a final drive unit 24, which in turn may be connected to the driven wheels 16. The first power source 14 (which will be referred to as a motor-generator or motor for the remainder of this disclosure) may be mounted to (or coupled to) the second power source 20, the transmission assembly 22, the final drive unit 24, or may be a separate component mounted to the structure of the vehicle 10. As shown, the motor vehicle 10 further includes a programmable electronic controller 26, which is configured to communicate via a high-voltage bus 27 and control the powertrain 12 to generate a predetermined amount of power source torque (such as the sum of T1 and T2), along with various other vehicle systems. The motor vehicle 10 additionally includes an energy storage system 28 , such as one or more batteries, configured to generate and store electrical energy for powering the power sources 14 and 20 .

[0028] Figure 2 1 shows a general cross-section of a radial flux embodiment of the motor-generator 14. As shown, the motor-generator 14 includes a rotationally fixed stator assembly or stator 30 having a generally cylindrical stator core 32 defining a stator core body or back iron 33 and a plurality of stator teeth 34 extending therefrom. The stator core 32 is constructed of a ferromagnetic material and has a stator inner diameter (ID) defining a radially inner stator surface 32A and a stator outer diameter (OD) defining a radially outer stator surface 32B, such as a stator core 32 having a substantially cylindrical stator core 32 defining a stator core body or back iron 33. Figure 2 The stator teeth 34 define a plurality of conductor slots 36 therebetween. The stator core 32 may include or be constructed from a plurality of adjacent (eg, bonded) stator laminations 38 arranged along the axis of rotation X.

[0029] like Figure 2 As shown, the stator 30 also includes a plurality of conductors or wire windings 40 arranged within the conductor slots 36. Specifically, a plurality of conductors 40 can be arranged within each conductor slot 36. Although the stator conductors 40 are generally contained within the conductor slots 36, the end turns of the conductors generally extend beyond the limits of the cylindrical core 32 at axially opposite stator ends (first end 32-1 and second end 32-2). The motor-generator 14 also includes at least one rotor 42 disposed on a shaft defining an axis of rotation X and thereby mounted for rotation within the stator 30. Specifically, an axial flux motor-generator 14 can have two rotors 42, each disposed on one side of the stator 30, while a radial flux motor-generator 14 includes a single rotor 42 mounted within the corresponding stator 30.

[0030] The rotor(s) 42 have corresponding outer rotor surface(s) 42A. Each rotor 42 has a ferromagnetic rotor core 44. The rotor core 44 has axially opposed rotor core ends, a first end 44-1 and a second end 44-2. In the case of a radial flux electric motor-generator 14, the outer rotor surface 42A is the radially outer surface, while in a radial flux electric motor-generator, the outer rotor surface 42A is defined by either the first end 44-1 or the second end 44-2. The rotor core 44 may be constructed of a relatively soft magnetic material, such as laminated silicon steel or ferrous steel. Figure 2 As shown, in radial flux motor-generator 14 , rotor core outer surface 44A establishes an air gap 46 between rotor 42 and stator 30 , ie, between outer rotor surface 42A and outer stator surface 32A.

[0031] Continue to refer Figure 2 Each rotor 42 includes a plurality of magnetic poles 48, each of which is configured to generate magnetic flux. The stator conductors 40 are configured to establish a rotating magnetic field that exerts torque on the rotor 42 via interaction with the magnetic poles 48 of the rotor. The stator conductors 40 receive multi-phase AC from the power inverter to establish a rotating magnetic field that exerts torque on the rotor 42. Figure 3 As shown, the stator 30 further includes a plurality of slot liners 50, each slot liner being arranged within a corresponding conductor slot 36 and surrounding a corresponding stator conductor 40. Each slot liner 50 may include a first slot liner portion 50-1 and a second slot liner portion 50-2. The first slot liner portion 50-1 is configured to partially wrap around a corresponding stator conductor 40 arranged within a corresponding conductor slot 36. The second slot liner portion 50-2 is configured to also partially wrap around the same stator conductor 40 and overlap a portion of the first slot liner portion 50-1, such that the corresponding conductor is surrounded by the two slot liner portions, as shown in the stator plan view ( Figure 3 Each of the conductor slots 36 may have an enlarged section 36A to accommodate the overlapping first and second slot liner portions 50 - 1 and 50 - 2 .

[0032] As shown in the partial plan view of the stator 30 ( Figure 3As shown, a first gap 52-1 is established between each stator conductor 40 and the corresponding slot liner 50. A second gap 52-2 is established between each slot liner 50 and the adjacent stator tooth 34, extending to each side of the corresponding conductor slot 36. The respective first gaps 52-1 and second gaps 52-2 are thus completely disposed within their corresponding conductor slots 36. A predetermined or controlled amount of varnish 54 is disposed within each of the first gaps 52-1 and second gaps 52-2. To establish the necessary amount of varnish 54 within the first gaps 52-1 and second gaps 52-2, the varnish can be applied to specific conductors 40 and to specifically identified areas of the conductor slots 36 via capillary action. This varnish application can be completed after twisting and welding the stator wire windings and before curing of the stator assembly 30. The specific amount of insulating varnish 54 thus disposed is configured to limit the amount of open space 56 (i.e., devoid of insulating varnish) within the first gap 52-1 and the second gap 52-2 to adjust or tune the viscous damping of the electric motor 14, including noise, vibration, and harshness (NVH) characteristics, as described in detail below. The amount of insulating varnish 54 can vary, for example, in a radial direction between the stator ID and the stator OD.

[0033] like Figure 5 As shown, the motor-generator 14 may also include a lubrication or fluid circulation system 60 configured to supply oil 62 to the stator 30, such as via a fluid pump 64. During operation of the motor-generator 14, a portion of the oil 62 may fill the open spaces 56 within the first gap 52-1 and the second gap 52-2, thereby affecting the NVH characteristics of the motor. For example, the insulating varnish 54 may fill up to 80% of each of the first gap 52-1 and the second gap 52-2 throughout the stator 30, leaving the remaining 20% filled with the oil 62. Figure 4 In the plan view shown, a predetermined amount of insulating varnish 54 may be applied to slots 36 that are located away from relatively high vibration or resonant angular locations 66 on the stator 30. In such an embodiment, during operation of the motor 14, oil 62 will variably fill the open spaces 56 in the remaining slots (identified by numeral 36') surrounding or proximate the relatively high resonant locations 66 to dampen stator vibrations.

[0034] The insulating varnish 54 arranged away from the relatively high vibration angle position 66 may fill more than 90% and up to 100% of each of the first gap 52-1 and the second gap 52-2. On the other hand, the insulating varnish 54 arranged near the relatively high resonance angle position 66 may fill approximately 50% of each of the first gap 52-1 and the second gap 52-2. Figure 5As shown in the side view, the amount of insulating varnish 54 can vary axially between adjacent stator laminations 38 along the rotation axis X. The variation in the amount of insulating varnish 54 can be consistent between multiple stator laminations 38 or adjusted differently along the rotation axis X according to identified resonance regions of the stator 30.

[0035] like Figure 2 and Figure 4 As shown, the stator core 32 may include a plurality of mounting bosses 68. The mounting bosses 68 may be circumferentially arranged on the radially outer stator surface 32B and located in structurally advantageous positions. The mounting bosses 68 define the restrained position of the motor 14 relative to the structure of the motor vehicle 10. In such an embodiment, the relatively high vibration angle position 66 may be provided between the mounting bosses 68 (e.g., Figure 4 As shown). Therefore, a predetermined amount of insulating varnish 54 filler can then be placed in the first gap 52-1 and the second gap 52-2 between the mounting protrusions 68. Figure 5 In the illustrated stator side view, the mounting boss 68 can be disposed on or near the first stator end 32 - 1 . In such an embodiment, the insulating varnish 54 can be concentrated near the first stator end 32 - 1 and fill more than 90% of each of the first gap 52 - 1 and the second gap 52 - 2 axially proximate to the mounting boss 68 .

[0036] The detailed description and the accompanying drawings or figures support and describe the present disclosure, but the scope of the present disclosure is limited only by the claims. Although some best modes and other embodiments for carrying out the claimed disclosure have been described in detail, there are various alternative designs and embodiments for practicing the disclosure defined in the appended claims. In addition, the embodiments shown in the drawings or the features of the various embodiments mentioned in this specification are not necessarily to be understood as embodiments that are independent of each other. On the contrary, it is possible that each feature described in one of the examples of the embodiment can be combined with one or more other desired features from other embodiments, resulting in other embodiments not being described in words or with reference to the drawings. Therefore, such other embodiments fall within the framework of the scope of the appended claims.

Claims

1. An electric motor, comprising: a stator having a stator core constructed of a ferromagnetic material and having an outer stator surface; wherein: The stator core includes a stator core body and a plurality of stator teeth extending from the stator core body; and The plurality of stator teeth define conductor slots therebetween; and in: The stator further comprises: a plurality of stator conductors arranged in the conductor slots; and a slot liner disposed within each conductor slot and surrounding a corresponding stator conductor; establishing a first gap between each stator conductor and a corresponding slot liner; and establishing a second gap between each slot liner and an adjacent stator tooth; and A predetermined amount of insulating varnish is disposed within each of the first gap and the second gap and is thereby configured to limit the amount of open space without insulating varnish within the first gap and the second gap and adjust viscous damping of the motor.

2. The electric motor according to claim 1, further comprising a lubrication system configured to supply oil to the stator, wherein During operation of the electric motor, a portion of the oil fills the open spaces within the first and second gaps, thereby affecting noise, vibration, and harshness (NVH) characteristics of the electric motor.

3. The electric motor according to claim 1, wherein The insulating varnish fills 80% of each of the first gap and the second gap.

4. The electric motor according to claim 1, wherein The insulating varnish is arranged away from a position with a relatively high vibration angle.

5. The electric motor according to claim 4, wherein The insulating varnish disposed away from the relatively high vibration angle position fills more than 90% of each of the first gap and the second gap.

6. The electric motor according to claim 4, wherein The insulating varnish arranged near the relatively high vibration angle position fills 50% of each of the first gap and the second gap.

7. The electric motor according to claim 4, wherein The stator core comprises a plurality of adjacent stator laminations arranged along the rotation axis, and wherein the amount of the insulating varnish varies along the rotation axis.

8. The electric motor according to claim 4, wherein In a plan view, the stator core includes a plurality of circumferentially arranged mounting bosses that define motor restraint positions, wherein the relatively high vibration angle position is provided between the mounting bosses, and wherein a predetermined amount of insulating varnish is applied within the first gap and the second gap between the mounting bosses.

9. The electric motor according to claim 8, wherein In a side view, the stator core includes a first stator end and an opposite second stator end, and wherein the mounting boss is arranged on the first stator end, and wherein the insulating varnish fills more than 90% of each of the first gap and the second gap axially close to the mounting boss.

10. The electric motor according to claim 1, wherein The stator includes a stator inner diameter (ID) and a stator outer diameter (OD), and wherein an amount of the insulating varnish varies in a radial direction between the stator ID and the stator OD.

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