Electrical machine with low-profile retention assembly for retaining a stator core

Abstract

An electric machine (30) is disclosed having a low-profile retention assembly (46) that retains a stator core (32). A first housing (36) houses the stator core (32). The first housing (36) has a circumferentially extending, contoured axial end face (56) with axially inwardly projecting recessed portions (58) alternating with non-recessed portions (60). A portion of the stator core (32) extends axially outward from the recessed portions (58). A core retention spring (62) is circumferentially disposed on the axial end face (56) of the first housing (36). The core retention spring (62) directly contacts the portion of the stator core (32) that extends axially outward from the recessed portions (58) of the first housing (36) and the contoured housing (36). The core retaining spring (62) compresses a portion of the stator core (32) extending axially outward from the first housing (36) and applies one or more of an axial load and a radial load to the stator core (32).

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to electric machines, and more particularly to a low profile retention assembly that provides one or more of axial and radial load retention for a stator core of an electric machine. [Background technology]

[0002] As electric machines such as generators and motors become more prevalent in transportation applications (e.g., vehicles and aerospace), both miniaturization and weight reduction of components in these machines have become key design requirements. However, the design requirements for miniaturization and weight reduction must take into account that these electric machines may be subjected to various temperature and / or environmental shock loads during machine operation, processing, and manufacturing. To handle the transient conditions resulting from various temperature and / or environmental shock loads, the stator core of the electric machine must sustain axial and radial forces therein to ensure proper operational function.

[0003] One approach that has been utilized to compensate for temperature differentials and / or environmental shock loads involves placing a 360° spring in a slot within the housing containing the stator core. The spring then presses directly against the stator core, maintaining an axial force on the core that can withstand the shock load. However, in electric machines where compactness and light weight are primary design considerations, the housing typically does not have the axial and radial space to accommodate a spring capable of maintaining an axial force on the stator core. In particular, these electric machines have very strict axial and radial space constraints, and therefore do not have sufficient mechanical or electrical clearance to accommodate a spring within the housing that can press directly against the stator core and maintain axial and / or radial compression to handle transient conditions that may arise from varying temperature and environmental shock loads.

[0004] Another consideration for electric machines, which also impacts temperature and environmental shock loads, is that they are now commonly manufactured with new resin materials. For example, higher power density electric machines are required to meet overall system power and efficiency targets, necessitating high-temperature insulation materials and the use of new resin formulations. Many of these new resin materials require very high-temperature curing, sometimes significantly exceeding their maximum operating temperatures. As a result, electric machine components, particularly the core, must be able to accommodate transient thermal expansion differences both during processing and operation. This is especially true for press-fit and shrink-fit component interfaces between electric machine components, such as the stator core and housing. If the interface between the stator core and housing cannot accommodate the transient thermal expansion differences that occur during processing and operation, the stator core may become loose from the housing, affecting the performance of the electric machine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 0403467 Summary of the Invention

[0006] The following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the various embodiments described herein. This summary is not an extensive overview of the various embodiments. It is not intended solely to identify key features or essential features of the claimed subject matter as set forth in the claims, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description presented later.

[0007] The embodiments described herein provide a solution to address challenges associated with smaller, lighter electric machines that lack axial and radial space for placing springs within the housing that contains the stator core to withstand the various temperature and / or environmental shock loads that may occur during operation, processing, and manufacturing of the machine. The solution provided by the embodiments involves using a low-profile retention assembly for small, lighter electric machines with a stator core within a housing that has tight radial and axial space constraints to provide one or more of axial and radial load retention for the core during operation, processing, and manufacturing of the machine.

[0008] In one embodiment, instead of using the axial and radial space within the housing to accommodate the stator core, the axial surface of the housing can be used to accommodate the spring. In this way, the spring can press or compress the core end rings that hold the stator core within the housing. The spring presses or compresses the core end rings, applying a force (axial load) to the stator core. This force allows the stator core to remain in axial compression.

[0009] In another embodiment, the springs can directly press or compress the stator core itself, applying an axial load directly to the core, eliminating the need for a core end ring. For example, the stator core located on the axial surface of the housing can be provided with features that correspond to the shape and characteristics of the core end ring at that location, eliminating the need for a core end ring. In this manner, the springs can be used to directly press or compress features on the stator core that correspond to the shape of the core end ring occupying the space shown in the previous embodiment. The springs press or compress these features, thereby applying an axial load to the stator core.

[0010] In yet another embodiment, a low-profile retention assembly can be provided to apply one or more radial and axial loads to the stator core. For example, the stator core and a core end ring located on the axial surface of the housing can be configured to have an inclined surface (e.g., a tapered surface) therebetween. Depending on the inclined surface, a spring can be applied to that surface to generate a resultant force vector on the surface that can be resolved as a radial load, an axial load, or both. This transfers the load to the stator core, maintaining the stator core in a corresponding compressed state.

[0011] To utilize the housing's axial surface for spring placement to facilitate axial compression of the stator core, certain embodiments can provide an axial surface geometry that allows the core end ring to protrude into the narrow axial and radial spaces near the housing, without completely sinking or nesting within the housing. In one embodiment, the housing's axial surface geometry can include a contour with alternating recessed and non-recessed portions that protrude axially inward from the housing's axial end face. This contour can extend circumferentially along the end or edge of the axial surface. In one embodiment, the contour with alternating recessed and non-recessed portions that protrude axially inward from the housing's axial end face can allow a portion of the core end ring to extend axially outward from the housing's axial end face. This allows a spring attached to the housing's axial surface to press against the core end ring during an impact load. When the spring presses against the core end ring, force (axial load) is transferred to the stator core such that the primary load path for the force to the core is through the core end ring. In this way, the force transmitted to the stator core can maintain the core in axial compression, which can be either constant or varying, even when the stator core tends to translate, deflect, or separate relative to the housing during an impact load.

[0012] In one embodiment, the housing profile can include a scalloped profile having a plurality of spaced-apart scalloped surfaces formed on the axial end surface of the housing. In addition to the scalloped profile, in certain embodiments, the axial surface of the housing can include a core retention spring mechanism extending axially and radially, whereby a spring is secured to the housing at the axial surface for interaction with the core end ring. In one embodiment, the core retention spring mechanism can be arranged between the scalloped surfaces to form an alternating pattern of scalloped surfaces and core retention spring mechanisms. This allows the spring to be secured to the axial surface of the housing and engage with the core end ring during an impact load. This allows the core end ring to apply an axial load to the stator core and maintain the stator core in axial compression during an impact load.

[0013] The core retention spring mechanism can include various retention mechanisms. For example, in one embodiment, the core retention spring mechanism can include an axially extending through hole that is complementary to receive the spring retention fitting, and a radially extending slot opposite the through hole. This allows the through hole, spring retention fitting, and radially extending slot to each secure a portion of the spring to the axial end face of the housing.

[0014] In another embodiment, the core retention spring mechanism can include a pair of opposing radially extending slots and an axially extending lip mechanism disposed between the slots. In this manner, each slot accommodates a portion of the spring, with another portion of the spring nestled beneath the lip mechanism. In this arrangement, the slots prevent axial and circumferential movement of the spring, and the lip mechanism prevents radial movement of the spring.

[0015] In yet another embodiment, the core retention spring mechanism can include a first axially extending through-hole and a second axially extending through-hole opposite the first through-hole. Both the first through-hole and the second through-hole are complementary to each other to accommodate a spring retaining hardware. In this manner, the first through-hole, the second through-hole, and the corresponding spring retaining hardware can secure a portion of the spring to the axial end face of the housing and prevent axial and circumferential movement.

[0016] Springs that can be used in the low-profile retention assemblies of various embodiments can include core retention springs. In one embodiment, the core retention spring can include a wave spring. For example, the core retention spring can include a 360° wave spring. The 360° wave spring can be positioned against a contoured shape (e.g., a scalloped contour) on the axial face of the housing, with a portion of the spring secured to any of the aforementioned core retention springs that can be used with the housing.

[0017] In another embodiment, the core retention spring can include a plurality of spaced-apart segmented wave springs arranged circumferentially around the axial end face of the housing. Using a plurality of spaced-apart segmented wave springs arranged circumferentially around the axial end face of the housing can be beneficial for fitting into tight radial and axial spaces and can also provide weight savings compared to a 360° wave spring. Each segmented wave spring can have a first tab leg, a second tab leg, and an active portion between the first and second tab legs. The first and second tab legs of each segmented wave spring can be secured to a shaped profile (e.g., a scalloped profile) at the axial end face of the housing by any of the aforementioned core retention spring mechanisms that can be utilized with the housing. For example, the segmented wave spring can include a through hole in one or more tab legs to mate with a core retention spring mechanism that secures the spring to the axial end face of the housing using a complementary through hole and spring retention hardware. In another embodiment, the tab legs can be inserted into a core retention spring mechanism that includes a radially extending slot. Regardless of the particular core retention spring mechanism utilized, in certain embodiments, the active portion of each segmented wave spring can be in direct contact with the core end ring having tab legs secured to a scalloped profile.

[0018] In addition to weight savings, the use of circumferentially arranged segmented wave springs reduces the amount of outer radial and axial material associated with using 360° wave springs. Nevertheless, the circumferentially arranged segmented wave springs still achieve the goal of mounting the springs to the axial surface of the housing, allowing the segmented wave springs to interact with the core end rings during impact loads. In this way, the segmented wave springs in certain embodiments allow the core end rings to apply an axial load to the stator core, maintaining the stator core in axial compression during impact loads.

[0019] In either spring embodiment, both the 360° wave spring and the multiple segmented wave springs enhance the low-profile aspect of the retention assembly described herein. That is, in certain embodiments, both springs can be applied to a contoured (e.g., scalloped) profile on the axial end face of the housing, allowing a portion of the spring(s) to interact with the core end rings in the event of a shock load and apply an axial load that maintains the stator core in axial compression. Furthermore, both spring embodiments can perform this function in very tight axial and radial spaces. In this way, the wave springs, and any spring hardware that may be utilized to secure the springs to the housing, are not near the active electrical components of the stator windings (i.e., coils), which could cause electrical problems. Furthermore, the location of the springs in these embodiments allows for significantly more axial deflection of the springs, which is beneficial for accommodating the wide range of differential electromechanical component interface movements and accretion that can occur during operation, processing, and manufacturing of the electric machine. Additionally, the spring not only maintains an acceptable spring force upon initial installation, but also maintains an acceptable force during higher temperature operation when thermal mismatch between the housing, core end rings, and stator core may occur.

[0020] The low-profile retention assembly of various embodiments can further include an outer housing containing a housing including a shaped profile (e.g., a scalloped profile) and a core retention spring mechanism disposed on its axial end surface. In one embodiment, this outer housing can extend over an inner housing including a shaped spring mechanism and a core retention spring mechanism, as well as a spring (i.e., a 360° spring or a segmented spring) disposed on its axial end surface. In this manner, the outer housing captures the spring underneath and prevents outward radial movement of the spring. The use of the outer housing in conjunction with the shaped profile and core retention spring mechanism on the axial end surface of the inner housing ensures that the low-profile retention assembly of various embodiments prevents any freedom of movement of the spring in the circumferential, radial, and axial directions.

[0021] According to one embodiment of the present invention, a retention assembly is provided for retaining a stator core within a stator of an electric machine. The retention assembly includes a first housing that accommodates a stator core, the first housing having an axial end face with a circumferentially extending molded contour, the first housing having recessed portions protruding axially inward from the axial end face of the housing alternating with non-recessed portions, wherein a portion of the stator core extends axially outward from the molded contour at the axial end face of the first housing beyond the recessed portions; and a core retention spring circumferentially disposed on the axial end face of the first housing, the core retention spring being in direct contact with the portion of the stator core extending axially outward from the molded contour of the first housing and with the molded contour of the first housing, wherein the core retention spring compresses the portion of the stator core extending axially outward from the molded contour of the first housing, maintaining the stator core in axial and / or radial compression, and applying one or more of an axial load and a radial load to the stator core.

[0022] According to another embodiment, a retention assembly for retaining a stator core in a stator of an electric machine is provided, the retention assembly including: a core end ring circumferentially disposed on an axial end of the stator core; an inner housing containing the stator core and the core end ring, the inner housing having an axial end face with a circumferentially extending scalloped contour, wherein a portion of the core end ring extends axially outward from the scalloped contour at the axial end face of the inner housing; and a core retention spring including a plurality of segmented core retention springs circumferentially disposed on the axial end face of the inner housing, each segmented core retention spring included in the axial end face of the inner housing to retain the core. and core retention springs that prevent circumferential and radial movement of the retention springs, wherein each segmented core retention spring directly contacts a portion of the core end ring that extends axially outward from the scallop-shaped contour of the inner housing, and wherein each segmented core retention spring presses against the core end ring and applies one or more of an axial load and a radial load to the stator core, wherein the axial load and / or radial load applied to the stator core by all of the plurality of segmented core retention springs via the core end ring maintains the stator core in an axially compressed state and / or a radially compressed state.

[0023] According to a third embodiment, an electric machine is provided, the electric machine comprising: a stator core having a plurality of axially oriented slots extending radially from a central axis of the stator core, with a plurality of stator winding coils disposed in the slots; an inner housing containing the stator core, the inner housing having an axial end face with a circumferentially extending scalloped profile, wherein a portion of the stator core extends axially outward from the scalloped profile at the axial end face of the inner housing; and a core retention spring circumferentially disposed on the axial end face of the inner housing, the core retention spring being retained by the scalloped profile of the inner housing and the scalloped ring of the inner housing. a core retention spring in direct contact with a portion of the stator core extending axially outward from the scalloped contour of the inner housing, where the core retention spring presses against the portion of the stator core extending axially outward from the scalloped contour of the inner housing, the core retention spring applying one or more of an axial load and a radial load to the stator core that maintains the stator core in axial and / or radial compression; and an outer housing that houses the inner housing, the outer housing extending over the inner housing and the core retention spring, where the outer housing captures the core retention spring underneath and prevents outward radial movement of the core retention spring.

[0024] The invention will be better understood from a reading of the following description of non-limiting embodiments, taken in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0025] [Figure 1] 1 shows a cross-sectional view of a portion of a stator of an electric machine according to the prior art; [Figure 2] 2 shows a schematic elevation view of a stator end according to one embodiment of the present invention; [Figure 3] 3 shows a schematic perspective view of a portion of a core end ring shown in FIG. 2 that can hold a stator core within a housing of a stator according to an embodiment of the present invention. [Figure 4]1 shows a schematic perspective view of a core retention spring that may be part of a retention assembly that retains a stator core in an electric machine according to an embodiment of the present invention. [Figure 5] 3 shows a schematic perspective view of a portion of the stator end shown in FIG. 2 according to one embodiment of the present invention. [Figures 6A-6B] 3 shows a schematic diagram of a perspective cross-sectional view detailing a portion of the axial end face of the inner housing of the stator shown in FIG. 2, which may form part of a retention assembly that holds a stator core of an electric machine according to an embodiment of the present invention. [Figure 7] A schematic top view of a core retention spring secured to a core retention spring mechanism positioned on the axial end face of an inner housing, which may form part of a retention assembly that holds a stator core in an electric machine according to one embodiment of the present invention, is shown. [Figure 8] 2 shows a schematic perspective view of a portion of an axial end face of an inner housing with further details of a retention assembly that holds a stator core of an electric machine according to an embodiment of the present invention; [Figure 9] 1 shows a schematic perspective cross-sectional view of a portion of a stator having an outer housing that may form part of a retention assembly that retains a stator core of an electric machine according to an embodiment of the present invention. [Figure 10] 1 shows a schematic perspective view of a portion of an axial end face of an inner housing having a 360° spring positioned on a scalloped contour of the end face that contacts the core ring, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] Illustrative embodiments of the invention are described more fully below with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0027] The present disclosure relates generally to electric machines, such as generators and motors, and more specifically to a low-profile retention assembly that provides one or more of axial and radial load retention for a stator core in electric machines useful in applications where it is desirable to make the machine small and lightweight. Transportation applications, which may include automotive, aerospace, and other modes of transportation, are non-limiting examples in which small and lightweight electric machines may be deployed. In these applications, there is typically insufficient radial and axial space within the housing of the electric machine that includes the stator core to accommodate stator core retention devices, such as springs, that can facilitate axial and radial forces on the stator core to withstand transient conditions caused by various temperatures and / or environmental shock loads. The low-profile stator core retention assemblies of various embodiments require less axial and radial space and are therefore suitable for compact and lightweight electric machines, particularly machines having a stator core in a housing with tight axial and radial space constraints. As used herein, an electric machine with tight axial and radial space constraints means an electric machine with compressed axial and radial shrouds that are limited in height and width to accommodate stator core retention devices (e.g., springs) and meet minimum electrical clearance requirements between the stator core copper coil windings and the retention devices to prevent electrical insulation reliability issues.

[0028] While various embodiments are described with respect to small, lightweight electric machines having tight axial and radial space constraints, these embodiments may also have utility with other electric machines, such as larger electric machines that do not have tight axial and radial space constraints but still require retention of the stator core to compensate for transient conditions that may affect proper operation of the electric machine.

[0029] Throughout the following description, reference is made to a set of axes that are based on a cylindrical coordinate system and refer to an axial direction A, a radial direction R, and a circumferential direction C that extends around a longitudinal axis that coincides with the axial direction A. For example, the axial direction A extends along the longitudinal axis of the stator (e.g., the central axis of the stator), the radial direction R extends laterally (e.g., perpendicularly) away from the longitudinal axis, and the circumferential direction C extends around the longitudinal axis.

[0030] Referring now to the drawings, FIG. 1 illustrates a cross-sectional view of a portion of a stator 10 of a prior art electric machine 12. This cross-sectional view of the stator 10 of the electric machine 12 of FIG. 1 shows a stator core 14, which may include a lamination stack (e.g., magnetic steel sheets) containing stator windings and coils 16 enclosed in an inner housing 18. Springs 20 are disposed in slots 22 formed in the inner housing 18. A core end ring 24 is disposed within the slots 22 to retain the stator core 14 and springs 20 within the inner housing 18. An outer housing 26 surrounds the inner housing 18 to maintain retention of the stator core 14, springs 20, and core end ring 24 within the inner housing. This allows the inner housing 18, springs 20, core end ring 24, and outer housing 26 to act in concert to maintain axial and radial loads on the stator core 14 to retain the core during operation, processing, and manufacturing of the electric machine 12. This allows the stator core 14 to withstand the various temperature and / or environmental shock loads that may occur in these cases.

[0031] In the electric machine 12 shown in FIG. 1 , the stator 10 does not have the tight axial and radial space constraints that prevent the use of springs 20 and core end rings 24 within slots 22 formed in the inner housing 18. As a result, springs 20 can be used to press directly against the stator core 14 and maintain an axial force on the core so that it can withstand shock loads. As noted above, electric machines with key design requirements of compactness and light weight typically do not have the axial and radial space within the inner housing to accommodate springs capable of maintaining an axial force on the stator core. In particular, because these electric machines have such tight axial and radial space constraints, there is not enough mechanical or electrical clearance within the inner housing to accommodate springs that can press directly against the stator core and maintain it in axial compression to handle transient conditions that may occur during machine operation, processing, and manufacturing.

[0032] FIG. 2 shows a schematic elevation view of an end of a stator 28 of an electric machine 30, such as a generator or motor, having tight radial and axial space constraints for implementing springs within an inner housing. Similar to the stator core 14 of the stator 10 of the electric machine 12 shown in FIG. 1, the stator 28 of the electric machine 30 shown in FIG. 2 includes a lamination stack stator core 32 containing stator windings and coils 34 (collectively, “stator winding coils 34”) surrounded by an inner housing 36 (e.g., a cooling jacket). In one embodiment, the stator core 32 may include multiple axial slots 38 extending radially from a central axis of the stator core (a longitudinal axis extending through the center of the stator), with multiple stator winding coils 34 positioned within the slots. After the stator winding coils 34 are positioned within the slots 38, multiple stator core wedges 40 are positioned within dovetails (not shown) formed in the stator 28. Stator core wedges 40 hold the stator winding coils 34 within the slots 38 and prevent radial movement, preventing the coils from exiting the slots. Phase ring connections or bus bars 42 interconnect the leads 44 from the various stator winding coils 34. Acting as electrical conductors, the phase ring connections or bus bars 42 connect the leads 44 of the stator winding coils 34 to the desired electrical circuit with the phase.

[0033] The electric machine 30 may further include a retention assembly 46 for retaining the stator core 32 within the tight radial and axial space constraints associated with the machine shown in FIG. 2 . In one embodiment, the retention assembly 46 may include a core end ring 48 circumferentially disposed at the axial end of the stator core 32 to retain the core within the inner housing 36 and provide insulating material used for electrical clearance. In addition to retaining the stator core 32 within the inner housing 36, the core end ring 48 may function as part of the retention assembly 46 that may apply one or more axial and / or radial loads to the stator core 32 that may maintain the stator core in axial and / or radial compression to withstand various temperature and / or environmental shock loads that may occur during operation, processing, and manufacturing of the electric machine 30.

[0034] Further details of the core end ring 48 are shown in Figure 3. As shown in Figure 3, the core end ring 48, which may comprise a non-metallic material such as plastic, may include a plurality of coil shape-retaining features 50 configured to extend correspondingly between the plurality of slots 38 at the axial end of the stator core 32. Figure 3 also shows that the core end ring 48 may include ledge features 54 that protrude outward from the plurality of coil shape-retaining features 50. When the core end ring 48 is circumferentially positioned at the axial end of the stator core 32, the ledge features 54 protrude axially outward from the axial end face of the inner housing 36, as shown in Figure 2.

[0035] Referring back to FIG. 2 , another portion of the retention assembly 46 may include an axial end face 56 of the inner housing 36. In one embodiment, the axial end face 56 of the inner housing 36 includes a circumferentially extending molded profile having recessed portions 58 that project axially inward from the axial end face of the housing, alternating with non-recessed portions 60. For example, the molded profile of the alternating recessed and non-recessed portions 58 and 60 may include a scalloped profile having a plurality of spaced-apart scalloped (i.e., curved or semicircular) surfaces formed on the axial end face 56 of the inner housing 36. With a molded profile (e.g., a scalloped profile) on the axial end face 56 of the inner housing 36, a portion of the core end ring 48 may extend axially outward from the molded profile at the axial end face beyond the recessed portions. In particular, a portion of the ledge feature 54 ( FIG. 3 ) of the core end ring 48 may extend axially outward beyond the recessed portions (e.g., scalloped surfaces) 58.

[0036] The retention assembly 46 may further include a core retention spring 62 circumferentially disposed on the axial end face 56 of the inner housing 36. The core retention spring 62 may be in direct contact with the molded contours of the core end ring 48 and the inner housing 36. Essentially, the ledge feature 54 of the core end ring 48 is in spring-loaded connection with the core retention spring 62. This allows the core retention spring 62 to compress the core end ring 48 and impart or apply a force, such as an axial load, to the stator core 32 to maintain the core in an axial compression state, which may be a constant compression state or a varying or varied compression state. This allows the stator core 32 to withstand various temperature and / or environmental shock loads that may occur during operation, processing, and manufacturing of the electric machine 30.

[0037] In one embodiment, the core retention spring 62 can be implemented in the retention assembly 46 as a segmented core retention spring comprising a plurality of segmented core retention springs. For example, the segmented core retention spring 62 can comprise segmented wave springs disposed around a contoured (e.g., scalloped) profile of the axial end face 56 of the inner housing 36. In one embodiment, each of the segmented wave springs can be disposed in a selected recessed portion 58 (e.g., scalloped surface) on the axial end face 56 of the inner housing 36 to facilitate a spring-loaded connection with the core retention spring 62. In one embodiment, a segmented wave spring can be disposed in every other recessed portion 58. Those skilled in the art will appreciate that this implementation of a segmented wave spring represents only one possible arrangement and is not meant to be limiting. For example, a segmented wave spring can be disposed in every recessed portion 58 of the axial end face 56 of the inner housing 36.

[0038] 4 shows a schematic perspective view of one of the segmented core retention springs 62 according to one embodiment, which may include a wave spring. As shown in FIG. 4, each segmented core retention spring 62 may include a first tab leg 64, a second tab leg 66, and an active portion 68 between the first and second tab legs. The first tab leg 64 and the second tab leg 66 of each segmented core retention spring 62 may be secured to a portion of the molded profile (i.e., one of the recessed portions 58 of the axial end face 56 of the inner housing 36), and the active portion 68 of the segmented core retention spring may be in direct contact with the core end ring 48, facilitating a spring-loaded connection.

[0039] In one embodiment, as shown in FIG. 4 , each segmented core retention spring 62 may include a through-hole 70 in one or more of the first tab leg 64 and the second tab leg 66. The through-holes 70 may be complementary to accommodate a spring retainer to secure one of the first tab leg 64 and the second tab leg 66 to the axial end face 56 of the inner housing 36. It should be understood that the segmented core retention spring 62 shown in FIG. 4 represents only one of the segmented wave springs that may be positioned about the axial end face 56 of the inner housing 36. For example, the segmented wave spring may have two through-holes 70 positioned in both the first tab leg 64 and the second tab leg 66. In this configuration, each through-hole 70 is complementary to accommodate a spring retainer to secure the first tab leg 64 and the second tab leg 66 to the axial end face 56. In another embodiment, the segmented wave spring may not have a through hole located in either the first tab leg 64 or the second tab leg 66. In this configuration, the first tab leg 64 and the second tab leg 66 may be located and secured to a core retention spring mechanism located on the axial end face 56 of the inner housing 36.

[0040] To clearly illustrate the retention assembly 46 and its components relevant to the various embodiments depicted herein, other components that may form part of the electric machine 30 are not shown in Figures 2 and 5-10. For example, the electric machine 30 may include a rotor and rotor shaft mounted within a stator 28. The rotor may be wound with a field winding that generates a constant magnetic field that can interact with the stator winding coils 34, which may be supplied from a system with a three-phase AC voltage.

[0041] Further details of the retention assembly 46 that retains the stator core 32 within the electric machine 30, including the core end ring 48, the axial end face 56 of the inner housing 36, and the core retention spring 62, according to one embodiment, are described in connection with FIGS. 5-10. Referring now to FIGS. 5 and 8, these figures illustrate further details of aspects of the retention assembly 46 related to the geometry at the axial end face 56 of the inner housing 36, which allows the core end ring 48 to protrude and seat in this narrow axial and radial space near this face of the housing, preventing it from being completely submerged or nested within the housing. For example, FIGS. 5 and 8 illustrate portions of the core end ring 48 (i.e., portions of the ledge features 54 (FIG. 3)) that extend axially outward from the contoured contour of the axial end face 56 of the inner housing 36. In particular, these portions of the core end ring 48 extend axially outward from the recessed portion 58 of the axial end face 56 of the inner housing 36. By extending these portions of the core end ring 48 axially outward from the recessed portions 58, the segmented core retention springs 62 located in selected recessed portions 58 on the axial end face 56 of the inner housing 36 can be positioned in and directly contact these portions of the core end ring 48 to facilitate a spring-loaded connection between the two components. This allows the segmented core retention springs 62 to compress the selected axially extending portions of the core end ring 48 during impact loads. Compressing the core end ring 48 with the segmented core retention springs 62 imparts a force (axial load) to the stator core 32 such that the primary load path for the force to the core is through the core end ring. As a result, the force imparted to the stator core 32 can maintain the core in axial compression in the event of an impact load that would tend to cause the stator core to translate, deflect, or separate relative to the housing.

[0042] 5 and 8, as well as 6A, 6B, 7, and 9, show further details of a core retention spring mechanism that may be disposed on the axial end surface 56 of the inner housing 36 to secure the core retention spring 62. In one embodiment, the core retention spring mechanism of the retention assembly may be machined into a molded contour on the axial end surface 56 of the inner housing 36. For example, the molded contour on the axial end surface 56 may form an alternating pattern of recessed portions having the core retention spring mechanism (e.g., a scalloped surface) and recessed portions without the core retention spring mechanism.

[0043] 5, 6A, and 6B, the core retention spring mechanism disposed in the molded contour of the axial end face 56 of the inner housing 36 can include an axially extending through-hole 72 (e.g., a threaded hole) complementary to receive a spring retention fitting 74 therein, and a radially extending spring retention slot or channel 76 formed in the axial end face opposite the through-hole. The through-hole 72 and spring retention fitting 74 can secure a portion of the core retention spring 62 to the axial end face 56 of the inner housing 36, and the radially extending spring retention slot 76 can receive another portion of the core retention spring therein and secure that portion to the axial end face of the first housing.

[0044] The spring retention fitting 74 may include any of several well-known fasteners capable of facilitating a mechanical connection between two components. For example, the spring retention fitting 74 may include screws, bolts, pins, inserts, rivets, etc. In addition to these fastener examples, other techniques may be used to secure the core retention spring 62 to the axial end face 56 of the inner housing 36. A non-exhaustive list of these other techniques includes bonding (e.g., adhesives) and welding (e.g., tack welding).

[0045] In another embodiment, as shown in FIGS. 7, 8, and 10, the core retention spring mechanism disposed in the contoured portion of the axial end face 56 of the inner housing 36 may include a pair of opposing radially extending spring retention slots 76 and an axially extending lip or ledge mechanism 78 disposed between the slots. In this configuration, each spring retention slot 76 is configured to receive a portion of the core retention spring 62 therein, thereby preventing axial and circumferential movement of the respective core retention spring. A portion of the active portion of the core retention spring 62 is received beneath and contacts the axially extending lip mechanism 78. In this manner, the axially extending lip mechanism 78 radially captures the underlying portion of the active portion of the core retention spring 62. Therefore, the spring retention slots 76 and the axially extending lip mechanism 78 function to prevent circumferential, radial, and axial movement of the segmented core retention spring 62.

[0046] The core retention spring mechanism shown in the figures is illustrative of only some possibilities and is not meant to be limiting to various embodiments. In one embodiment, the core retention spring mechanism can include two through holes 72 instead of just one. For example, a first axially extending through hole 72 can be formed in the axial end face 56 of the inner housing 36 at a location within the recessed portion 58, and a second axially extending through hole 72 can be formed at the opposite end of the recessed portion. In this configuration, both the first through hole 72 and the second through hole 72 are complementary to receive a spring retaining clip 74 therein. In this manner, the first through hole 72 and the second through hole 72 and the corresponding spring retaining clip can secure a portion of the core retention spring 62 to the axial end face 56 of the inner housing 36, preventing axial and circumferential movement of the segmented core retention spring 62.

[0047] While FIGS. 2, 5, 6A, 6B, 7, 8, and 9 illustrate that the core retention spring 62 can include a segmented core spring, such as a wave spring, as discussed above and shown in FIG. 10, the core retention spring can include a 360° spring, such as a 360° wave spring. As shown in FIG. 10, the 360° wave spring can be disposed on a molded contour of the axial end face 56 of the inner housing 36. For example, the 360° wave spring can be disposed along the entire molded contour of the axial end face 56, including the recessed portion 58 (e.g., a scalloped surface) and the non-recessed portion 60. In one embodiment, as shown in FIG. 10, the 360° wave spring can be secured to the axial end face 56 of the inner housing 36 using any of the spring retention fixtures 74 described above. For example, the spring retention fixture 74 can be secured to the non-recessed portion 60 on the molded contour of the axial end face 56.

[0048] While FIG. 10 illustrates the use of spring retention fittings 74 to secure the 360° wave spring to the axial end face 56 of the inner housing 36, it should be understood that other core retention spring mechanisms can be used to secure the 360° wave spring. For example, the 360° wave spring can be secured within radially extending spring retention slots 76 located along the axial end face 56 of the inner housing 36 in the manner described above. These other core retention spring mechanisms can also include axially extending lip mechanisms 78 that provide positive radial outward retention of the spring, which complements the axial and circumferential retention of the spring provided by the spring retention slots 76. It should be understood that the 360° wave spring can be secured to the axial end face 56 of the inner housing 36 using any of the other techniques described above, including, but not limited to, bonding and welding.

[0049] By utilizing an outer housing that houses the inner housing 36, including the molded contour and core retention spring mechanism, the retention assembly 46 can further add positive radial outward retention of the core retention spring 62. For example, FIG. 9 shows an outer housing 80 that extends over the inner housing 36 and the segmented core retention spring 62. In this manner, the outer housing 80 can capture or contain the core retention spring 62 beneath it, preventing outward radial movement of the spring. In particular, by covering the radially extending spring retention slots 76, the outer housing 80 can contain the segmented core retention spring 62 and prevent outward radial movement of the spring, further supplementing the radial movement prevention that can be provided by the use of the axially extending lip mechanism 78 (FIGS. 7 and 8).

[0050] The retention assemblies shown in Figures 2, 5, 6A, 6B, 7, 8, 9, and 10 are not meant to be limiting, as other approaches can be implemented to provide axial and / or radial load retention for an electric machine stator core. For example, in one embodiment, a low-profile retention assembly can be implemented without the use of a core end ring 48. In this embodiment, the stator core 32 at the axial end face 56 of the housing 36 can be shaped to exhibit features corresponding to the shape and characteristics of the core end ring at this location. For example, using Figure 9 as a reference, the axial face of the stator core 32 can be formed to take on the shape of the core end ring at this location, i.e., in addition to the portion of the axial end face of the stator core shown in this figure to obviate the use of a core end ring 48. In this manner, the core retention springs 62 can be used to directly press or compress against features on the stator core that are shaped to correspond to the features on the core end ring. Pressing or compressing the core retention springs 62 against these features can impart an axial load to the stator core.

[0051] In another embodiment, a low-profile retention assembly can be provided to apply one or more radial and axial loads to the stator core. For example, the stator core 32 and the core end ring 48 at the axial end face 56 of the housing 36 can be configured with an inclined surface (e.g., a tapered surface) formed between these components. Depending on the inclined surface, applying the core retention spring 62 to that surface can generate a resultant force vector on the surface that can be resolved into a radial load, an axial load, or both. As a result, these loads can be applied to the stator core 32 to maintain the stator core 32 in a corresponding loaded compression state.

[0052] From the description of the embodiments presented herein, it is clear that the present disclosure presents an effective solution to the challenges associated with compact, lightweight electric machines that lack axial and radial space for placing springs, such as 360° springs, within the inner housing containing the stator core to withstand shock loads that may occur during machine operation, processing, and manufacturing. The solution provided by the retention assemblies of various embodiments involves utilizing the axial surface of the inner housing to accommodate the springs. In this manner, the springs can press or compress against portions of the core end ring or stator core that extend radially from the axial surface. The springs pressing or compressing these portions of the core end ring or stator core impart a force (axial load and / or radial load) to the stator core. This force can maintain the stator core in axial and / or radial compression.

[0053] Use of the retention assemblies described herein provides several advantages. For example, low-profile retention assemblies facilitate the manufacturing and production of electric machines with compactness and light weight as key design requirements. Furthermore, the retention assemblies of various embodiments allow significantly more axial spring deflection, which is beneficial for accommodating a wide range of differential electric machine component interface movement and growth that may occur during operation, processing, and manufacturing of the electric machine. Furthermore, the retention assembly springs not only maintain an acceptable spring force upon initial installation, but also during high-temperature operation when thermal mismatch between the housing, core end rings, and stator core may occur.

[0054] The foregoing description of illustrative embodiments of the present subject disclosure, including those described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples have been described herein for illustrative purposes, various modifications are possible that are contemplated within the scope of such embodiments and examples, as those skilled in the art will recognize. For example, parts, components, steps, and aspects from different embodiments may be combined or suitable for use in other embodiments even if not described in the present disclosure or illustrated in the figures. Thus, because certain changes can be made to the above-described invention without departing from the spirit and scope of the invention embodied herein, it is intended that all of the subject matter of the foregoing description, as shown in the accompanying drawings, should be interpreted solely as examples illustrating the inventive concepts herein, and not as limiting the invention.

[0055] In this regard, while the disclosed subject matter has been described with reference to various embodiments and corresponding drawings, it should be understood that, where applicable, other similar embodiments can be used, or modifications and additions can be made to the described embodiments, to perform the same, similar, alternative, or substitute function of the disclosed subject matter without departing from the disclosed subject matter. Accordingly, the disclosed subject matter should not be limited to any single embodiment described herein, but rather should be construed broadly in accordance with the following appended claims. For example, reference to "one embodiment" of the present invention is not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the described features.

[0056] In the appended claims, the terms "including" and "in which" are used as the plain English equivalents of the respective terms "comprising" and "wherein." Furthermore, in the following claims, the terms "first," "second," "third," "upper," "lower," "bottom," "top," and the like are used merely as guides and are not intended to impose numerical or positional requirements on their objects. The terms "substantially," "generally," and "about" indicate conditions within reasonably achievable manufacturing and assembly tolerances relative to ideal desired conditions suitable for achieving the functional purpose of a component or assembly. Furthermore, the limitations of the following claims are not written in, and are not intended to be construed as, means-plus-function, unless such claim limitations expressly use the phrase "means for" followed by a description of a function lacking further structure.

[0057] The foregoing includes examples of systems and methods that illustrate the disclosed subject matter. It is, of course, not possible to describe every possible combination of elements or techniques. Those skilled in the art will recognize that many more combinations and permutations of the claimed subject matter are possible. Furthermore, to the extent that terms such as "includes," "has," and "possesses" are used in the Detailed Description, claims, appendices, and drawings, such terms are intended to be inclusive in the same manner as the term "comprising" is interpreted when used as a transitional term in a claim. That is, unless expressly stated to the contrary, an embodiment that "comprising," "including," or "having" an element or elements having a particular characteristic may include additional such elements that do not have that characteristic. Furthermore, the articles "a" and "an" as used in this specification and the accompanying drawings should generally be construed to mean "one or more" unless otherwise specified or unless it is clear from the context that the singular form is intended.

[0058] This specification uses examples to disclose some embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the embodiments of the invention, including making and using any devices or systems, and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ insubstantial way from the literal language of the claims.

[0059] Further aspects of the invention are provided by the subject matter of the following clauses.

[0060] 1. A retention assembly for retaining a stator core in a stator of an electric machine, the retention assembly comprising: a first housing that receives the stator core, the first housing having an axial end face with a circumferentially extending molded contour, the first housing having recessed portions projecting axially inward from the axial end face of the housing alternating with non-recessed portions, wherein a portion of the stator core extends axially outward from the molded contour in the axial end face of the first housing beyond the recessed portions; and a core retention spring circumferentially disposed on the axial end face of the first housing, the core retention spring being in direct contact with the portion of the stator core extending axially outward from the molded contour of the first housing and with the molded contour of the first housing, wherein the core retention spring compresses the portion of the stator core extending axially outward from the molded contour of the first housing to maintain the stator core in axial and / or radial compression, the core retention spring applying one or more of an axial load and a radial load to the stator core.

[0061] 10. The retention assembly of claim 1, wherein the molded profile of the first housing comprises a plurality of spaced apart scalloped surfaces formed on an axial end face of the first housing, the scalloped profile having a plurality of core retention spring mechanisms extending axially and radially, the plurality of core retention spring mechanisms being disposed on selected scalloped surfaces, wherein the scalloped profiles form an alternating pattern of scalloped surfaces having core retention spring mechanisms and scalloped surfaces not having core retention spring mechanisms.

[0062] 10. The retention assembly of claim 1, wherein the plurality of core retention spring mechanisms include axially extending through holes and radially extending spring retention slots opposite the through holes that are complementary to receive spring retention fittings therein, the through holes and spring retention fittings securing a portion of the core retention spring to the axial end face of the first housing, and the radially extending spring retention slots receiving another portion of the core retention spring therein and securing that portion to the axial end face of the first housing.

[0063] 10. The retention assembly of any preceding clause, wherein the plurality of core retention spring mechanisms comprise a pair of opposing radially extending spring retention slots and an axially extending lip mechanism disposed between the slots, wherein each spring retention slot is configured to receive therein a portion of the core retention spring that prevents axial and circumferential movement of the portion of the core retention spring, and wherein the axially extending lip mechanism is configured to radially capture therebelow an additional portion of the core retention spring that prevents radial movement of the core retention spring.

[0064] A retention assembly as described in any of the preceding clauses, wherein the plurality of core retention spring mechanisms include a first axially extending through hole and a second axially extending through hole opposite the first through hole, both the first through hole and the second through hole being complementary to each other to accommodate a spring retention fitting therein, and the first through hole and the second through hole and the corresponding spring retention fitting are configured to secure a portion of the core retention spring to the axial end face of the first housing to prevent axial and circumferential movement of the portion of the core retention spring.

[0065] 10. The retention assembly of claim 1, wherein the core retention spring is a segmented core retention spring comprising a plurality of segmented core retention springs, each segmented core retention spring having a first tab leg, a second tab leg, and an active portion between the first tab leg and the second tab leg, wherein the first tab leg and the second tab leg of each segmented core retention spring are secured to a molded profile on the axial end face of the first housing, and wherein the active portion of the segmented core retention spring is in direct contact with a portion of the stator core extending axially outward from the molded profile of the first housing, and wherein each segmented core retention spring is spaced from an adjacent segmented core retention spring on the molded profile at the axial end face of the first housing.

[0066] 10. The retention assembly of any preceding clause, wherein each segmented core retention spring includes a through hole in one or more of the first tab leg and the second tab leg, the through holes being complementary to accommodate a spring retention fitting therein, securing one of the first tab leg and the second tab leg to an axial end face of the first housing.

[0067] The retention assembly of any preceding clause, further comprising a second housing that receives the first housing, the second housing extending over the first housing and the core retention spring, the second housing capturing the core retention spring thereunder and preventing outward radial movement of the core retention spring.

[0068] A retention assembly for retaining a stator core within a stator of an electric machine, comprising: a core end ring circumferentially disposed on an axial end of the stator core; an inner housing containing the stator core and the core end ring, the inner housing having an axial end face with a circumferentially extending scalloped contour, a portion of the core end ring extending axially outward from the scalloped contour at the axial end face of the inner housing; and a core retention spring including a plurality of segmented core retention springs circumferentially disposed on the axial end face of the inner housing, each segmented core retention spring being included in the axial end face of the inner housing. and a core retention spring configured to prevent circumferential and radial movement of the core retention springs, wherein each segmented core retention spring directly contacts a portion of the core end ring that extends axially outward from the scallop-shaped contour of the inner housing, and wherein each segmented core retention spring compresses the core end ring and applies one or more of an axial load and a radial load to the stator core, wherein the axial and / or radial load applied to the stator core by all of the plurality of segmented core retention springs via the core end ring maintains the stator core in an axial and / or radial compressed state.

[0069] 10. The retention assembly of claim 1, wherein the circumferentially extending scalloped contour comprises a plurality of spaced apart scalloped surfaces formed on the axial end face of the inner housing and a plurality of axially and radially extending core retention spring mechanisms, the plurality of core retention spring mechanisms being disposed on selected scalloped surfaces, wherein the scalloped contour forms an alternating pattern of scalloped surfaces having core retention spring mechanisms and scalloped surfaces not having core retention spring mechanisms.

[0070] 10. The retention assembly of claim 9, wherein the plurality of core retention spring mechanisms include axially extending through holes and radially extending spring retention slots opposite the through holes that are complementary to receive spring retention fittings therein, the through holes and spring retention fittings securing a portion of one of the segmented core retention springs to the axial end face of the inner housing, and the radially extending spring retention slots receiving another portion of the segmented core retention spring therein and securing that portion of the segmented core retention spring to the axial end face of the inner housing.

[0071] 10. The retention assembly of claim 1, wherein the plurality of core retention spring mechanisms comprise a pair of opposing radially extending spring retention slots and an axially extending lip mechanism disposed between the spring retention slots, wherein each spring retention slot is configured to receive a portion of one of the segmented core retention springs therein preventing axial and circumferential movement of the segmented core retention spring, and wherein the axially extending lip mechanism is configured to radially capture the segmented core retention spring therebelow preventing radial movement of the segmented core retention spring.

[0072] A retention assembly as described in any of the preceding clauses, wherein the plurality of core retention spring mechanisms include a first axially extending through hole and a second axially extending through hole opposite the first through hole, both the first through hole and the second through hole being complementary to each other to accommodate a spring retention fitting therein, and the first through hole and the second through hole and the corresponding spring retention fitting are configured to secure a portion of one of the segmented core retention springs to an axial end face of the inner housing to prevent axial and circumferential movement of the portion of the core retention spring.

[0073] 10. The retention assembly of claim 1, wherein the plurality of segmented core retention springs comprises segmented wave springs, each wave spring having a first tab leg, a second tab leg, and an active portion between the first and second tab legs, wherein the first and second tab legs of each wave spring are secured to a scalloped contour at the axial end face of the inner housing, and wherein the active portion of the wave spring is in direct contact with a portion of the core end ring that extends axially outward from the scalloped contour of the inner housing, and wherein each wave spring is spaced from an adjacent wave spring on the scalloped contour at the axial end face of the inner housing.

[0074] 10. The retention assembly of claim 1, wherein each wave spring includes a through hole in one or more of the first tab leg and the second tab leg, the through holes being complementary to receive a spring retention hardware therein and securing one of the first tab leg and the second tab leg to an axial end face of the inner housing.

[0075] 10. The retention assembly of any preceding clause, further comprising an outer housing that houses the inner housing, the outer housing extending over the inner housing and the plurality of segmented core retention springs, the outer housing capturing the plurality of segmented core retention springs therebelow and preventing outward radial movement of the segmented core retention springs.

[0076] An electric machine comprising: a stator core having a plurality of axially oriented slots extending radially from a central axis of the stator core, with a plurality of stator winding coils disposed within the slots; an inner housing containing the stator core, the inner housing having an axial end face with a circumferentially extending scalloped profile, wherein a portion of the stator core extends axially outward from the scalloped profile at the axial end face of the inner housing; and a core retention spring circumferentially disposed on the axial end face of the inner housing, the core retention spring being circumferentially oriented relative to the scalloped profile of the inner housing and the scalloped profile of the inner housing. a core retention spring in direct contact with a portion of the stator core extending axially outward from the scalloped contour of the inner housing, where the core retention spring presses against the portion of the stator core extending axially outward from the scalloped contour of the inner housing, the core retention spring applying one or more of an axial load and a radial load to the stator core that maintains the stator core in axial and / or radial compression; and an outer housing that encases the inner housing, the outer housing extending over the inner housing and the core retention spring, where the outer housing captures the core retention spring underneath and prevents outward radial movement of the core retention spring.

[0077] 10. The electric machine of claim 9, wherein the circumferentially extending scalloped profile includes a plurality of spaced apart scalloped surfaces formed on an axial end face of the inner housing and a plurality of axially and radially extending core retention spring mechanisms, the scalloped profile forming an alternating pattern of scalloped surfaces having core retention spring mechanisms and scalloped surfaces not having core retention spring mechanisms.

[0078] 10. The electric machine of any preceding clause, wherein the core retention spring mechanism comprises one or more of at least one radially extending spring retention slot and at least one axially extending through hole.

[0079] 10. The electric machine of any preceding clause, wherein the core retention spring is a segmented core retention spring comprising a plurality of segmented core retention springs, each segmented core retention spring having a first tab leg, a second tab leg, and an active portion between the first tab leg and the second tab leg, wherein the first tab leg and the second tab leg of each segmented core retention spring are secured to a scallop-shaped contour at an axial end face of the inner housing, and wherein the active portion of the segmented core retention spring is in direct contact with a portion of the stator core extending axially outward from the scallop-shaped contour of the inner housing, and wherein each segmented core retention spring is spaced from an adjacent segmented core retention spring on the scallop-shaped contour at the axial end face of the inner housing. [Explanation of symbols]

[0080] 10 Stator 12 Electrical Machinery 14 stator core 16 Stator Windings and Coils 18 Inner housing 20 spring 22 slots 24 Core end ring 26 Outer housing 28 Stator 30 Electrical Machinery 32 stator core 34 Stator winding coil 36 inner housing, first housing 38 slots 40 stator core wedge 42 Phase Ring Connection or Busbar 44 lead wire 46 Retaining Assembly 48 Core end ring 50 Coil shape preservation mechanism 54 Ledge mechanism 56 Axial end face 58 Concave part 60 Non-concave part 62 Core retaining spring 64 First Tab Leg 66 Second tab leg 68 Valid Part 70 through holes 72 First through hole, second through hole 74 Spring retaining bracket 76 Spring retaining slot, channel 78 Lip mechanism, ledge mechanism 80 outer housing, second housing

Claims

1. A retention assembly (46) for retaining a stator core (32) within a stator (28) of an electric machine (30), comprising: a first housing (36) containing the stator core (32), the first housing (36) having an axial end face (56) with a circumferentially extending contoured formed thereon, the first housing (36) having recessed portions (58) projecting axially inward from the axial end face (56) of the housing (36) alternating with non-recessed portions (60), wherein a portion of the stator core (32) extends axially outward from the contoured formed portion at the axial end face (56) of the first housing (36) beyond the recessed portions (58); a core retention spring (62) circumferentially disposed on the axial end surface (56) of the first housing (36), the core retention spring (62) being in direct contact with the portion of the stator core (32) extending axially outward from the molded profile of the first housing (36) and the molded profile of the first housing (36), wherein the core retention spring (62) compresses the portion of the stator core (32) extending axially outward from the molded profile of the first housing (36) and maintains the stator core (32) in axial and / or radial compression, applying one or more of an axial load and a radial load to the stator core (32); A retention assembly (46) comprising:

2. 2. The retention assembly of claim 1, wherein the shaped profile of the first housing comprises a plurality of spaced apart scalloped surfaces formed on the axial end face of the first housing, the scalloped profile having a plurality of axially and radially extending core retention spring mechanisms, the plurality of core retention spring mechanisms being disposed on selected scalloped surfaces, and wherein the scalloped profiles form an alternating pattern of scalloped surfaces having core retention spring mechanisms and scalloped surfaces not having core retention spring mechanisms.

3. 3. The retention assembly of claim 2, wherein the plurality of core retention spring mechanisms include axially extending through holes (70) and radially extending spring retention slots (76) opposite the through holes (70) that are complementary to receive spring retention fittings (74) therein, the through holes (70) and the spring retention fittings (74) securing a portion of the core retention spring (62) to the axial end face (56) of the first housing (36), and the radially extending spring retention slots (76) receiving another portion of the core retention spring (62) therein and securing that portion to the axial end face (56) of the first housing (36).

4. 3. The retention assembly of claim 2, wherein the plurality of core retention spring mechanisms comprise a pair of opposing radially extending spring retention slots and an axially extending lip mechanism disposed between the slots, wherein each spring retention slot is configured to receive therein a portion of the core retention spring that prevents axial and circumferential movement of the portion of the core retention spring, and wherein the axially extending lip mechanism is configured to radially capture therebelow an additional portion of the core retention spring that prevents radial movement of the core retention spring.

5. 3. The retention assembly of claim 2, wherein the plurality of core retention spring mechanisms comprise a first axially extending through hole and a second axially extending through hole opposite the first through hole, wherein both the first through hole and the second through hole are complementary to each other to receive a spring retention fitting therein, and the first through hole and the second through hole and the corresponding spring retention fitting are configured to secure a portion of the core retention spring to the axial end face of the first housing to prevent axial and circumferential movement of the portion of the core retention spring.

6. The core retention spring (62) is a segmented core retention spring (62) comprising a plurality of segmented core retention springs (62), each having a first tab leg (64), a second tab leg (66), and an active portion (68) between the first tab leg (64) and the second tab leg (66), wherein the first tab leg (64) and the second tab leg (66) of each segmented core retention spring (62) are in contact with the axial end surface (5) of the first housing (36). 6) to the molded contour, and the active portion (68) of the segmented core retention spring (62) is in direct contact with the portion of the stator core (32) extending axially outward from the molded contour of the first housing (36), wherein each segmented core retention spring (62) is spaced from an adjacent segmented core retention spring (62) on the molded contour of the axial end face (56) of the first housing (36).

7. 7. The retention assembly of claim 6, wherein each segmented core retention spring includes a through hole in one or more of the first tab leg and the second tab leg, the through holes being complementary to receive a spring retention fitting therein and securing one of the first tab leg and the second tab leg to the axial end face of the first housing.

8. 2. The retention assembly (46) of claim 1, further comprising a second housing (80) that receives the first housing (36), the second housing (80) extending over the first housing (36) and the core retention spring (62), the second housing (80) capturing the core retention spring (62) therebelow and preventing outward radial movement of the core retention spring (62).

9. A retention assembly (46) for retaining a stator core (32) within a stator (28) of an electric machine (30), comprising: a core end ring (48) circumferentially disposed at an axial end of the stator core (32); an inner housing (36) containing the stator core (32) and the core end ring (48), the inner housing (36) having an axial end face (56) with a circumferentially extending scalloped contour, and a portion of the core end ring (48) extending axially outward from the scalloped contour at the axial end face (56) of the inner housing (36); a core retention spring (62) including a plurality of segmented core retention springs (62) circumferentially disposed on the axial end face (56) of the inner housing (36), each segmented core retention spring (62) being contained on the axial end face (56) of the inner housing (36) to prevent circumferential and radial movement of the core retention springs (62), wherein each segmented core retention spring (62) is secured to the core end ring (48) extending axially outward from the scalloped profile of the inner housing (36); a core retention spring (62) in direct contact with the portion of the core end ring (48), each segmented core retention spring (62) compressing the core end ring (48) and applying one or more of an axial load and a radial load to the stator core (32), wherein the axial load and / or the radial load applied to the stator core (32) by all of the segmented core retention springs (62) through the core end ring (48) maintains the stator core (32) in an axial and / or radial compression state; A retention assembly (46) comprising:

10. 10. The retention assembly of claim 9, wherein the circumferentially extending scalloped profile comprises a plurality of spaced apart scalloped surfaces formed on the axial end face of the inner housing and a plurality of axially and radially extending core retention spring mechanisms, the plurality of core retention spring mechanisms disposed on selected scalloped surfaces, wherein the scalloped profile forms an alternating pattern of scalloped surfaces having core retention spring mechanisms and scalloped surfaces not having core retention spring mechanisms.

11. 11. The retention assembly of claim 10, wherein the plurality of core retention spring mechanisms comprise axially extending through holes (72) complementary to receive spring retention fittings (74) therein and radially extending spring retention slots (76) opposite the through holes (72), the through holes (72) and the spring retention fittings (74) securing a portion of one of the segmented core retention springs (62) to the axial end face (56) of the inner housing (36), and the radially extending spring retention slots (76) receiving another portion of the segmented core retention spring (62) therein and securing that portion of the segmented core retention spring (62) to the axial end face (56) of the inner housing (36).

12. 11. The retention assembly of claim 10, wherein the plurality of core retention spring features comprise a pair of opposing radially extending spring retention slots and an axially extending lip feature disposed between the spring retention slots, wherein each spring retention slot is configured to receive a portion of one of the segmented core retention springs therein preventing axial and circumferential movement of the segmented core retention springs, and wherein the axially extending lip feature is configured to radially capture the segmented core retention springs therebelow preventing radial movement of the segmented core retention springs.

13. 11. The retention assembly of claim 10, wherein the plurality of core retention spring mechanisms comprise a first axially extending through hole and a second axially extending through hole opposite the first through hole, both the first through hole and the second through hole being complementary to each other to receive a spring retention fitting therein, and the first through hole and the second through hole and the corresponding spring retention fitting are configured to secure a portion of one of the segmented core retention springs to the axial end face of the inner housing to prevent axial and circumferential movement of the portion of the core retention spring.

14. The plurality of segmented core retention springs (62) comprise segmented wave springs (20), each having a first tab leg (64), a second tab leg (66), and an active portion (68) between the first tab leg (64) and the second tab leg (66), wherein the first tab leg (64) and the second tab leg (66) of each wave spring contact the scalar at the axial end face (56) of the inner housing (36).

10. The retention assembly (46) of claim 9, wherein the active portions (68) of the wave springs (20) are secured to a scallop-shaped profile of the inner housing (36), and the active portions (68) of the wave springs (20) are in direct contact with the portions of the core end ring (48) that extend axially outward from the scallop-shaped profile of the inner housing (36), wherein each wave spring (20) is spaced from an adjacent wave spring (20) on the scallop-shaped profile at the axial end face (56) of the inner housing (36).

15. 15. The retention assembly (46) of claim 14, wherein each wave spring (20) includes a through hole (70) in one or more of the first tab leg (64) and the second tab leg (66), the through holes (70) being complementary to receive a spring retention fitting (74) therein and securing one of the first tab leg (64) and the second tab leg (66) to the axial end face (56) of the inner housing (36).

16. 10. The retention assembly (46) of claim 9, further comprising an outer housing (80) that receives the inner housing (36), the outer housing (80) extending over the inner housing (36) and the plurality of segmented core retention springs (62), the outer housing (80) capturing the plurality of segmented core retention springs (62) therebelow and preventing outward radial movement of the segmented core retention springs (62).

17. An electric machine (30), a stator core (32) having a plurality of axially oriented slots (38) extending radially from a central axis of the stator core (32), with a plurality of stator winding coils (34) disposed within the slots (38); an inner housing (36) that houses the stator core (32), the inner housing (36) having an axial end surface (56) with a circumferentially extending scallop-shaped profile, wherein a portion of the stator core (32) extends axially outward from the scallop-shaped profile at the axial end surface (56) of the inner housing (36); a core retention spring (62) circumferentially disposed on the axial end face (56) of the inner housing (36), the core retention spring (62) being in direct contact with the scalloped contour of the inner housing (36) and the portion of the stator core (32) extending axially outward from the scalloped contour of the inner housing (36), wherein the core retention spring (62) presses against the portion of the stator core (32) extending axially outward from the scalloped contour of the inner housing (36), and the core retention spring (62) maintains the stator core (32) in axial and / or radial compression; the core retention spring (62) applying one or more of an axial load and a radial load to the stator core (32); an outer housing (80) that receives the inner housing (36), the outer housing (80) extending over the inner housing (36) and the core retention spring (62), wherein the outer housing (80) captures the core retention spring (62) underneath and prevents outward radial movement of the core retention spring (62); An electric machine (30) comprising:

18. 18. The electric machine of claim 17, wherein the circumferentially extending scalloped profile comprises a plurality of spaced apart scalloped surfaces formed on the axial end face of the inner housing and a plurality of axially and radially extending core retention spring features, the scalloped profile forming an alternating pattern of scalloped surfaces having core retention spring features and scalloped surfaces not having core retention spring features.

19. The electric machine (30) of claim 17, wherein the core retention spring mechanism comprises one or more of at least one radially extending spring retention slot (76) and at least one axially extending through-hole (72).

20. The core retention spring (62) is a segmented core retention spring (62) comprising a plurality of segmented core retention springs (62), each having a first tab leg (64), a second tab leg (66), and an active portion (68) between the first tab leg (64) and the second tab leg (66), wherein the first tab leg (64) and the second tab leg (66) of each segmented core retention spring (62) are in contact with the axial end face (56) of the inner housing (36).

18. The electric machine of claim 17, wherein the active portions of the segmented core retention springs are secured to the scalloped contour and are in direct contact with the portion of the stator core that extends axially outward from the scalloped contour of the inner housing, and wherein each segmented core retention spring is spaced apart from an adjacent segmented core retention spring on the scalloped contour at the axial end face of the inner housing.

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