Pre-loading magnets in the rotor core

Abstract

A rotor core for an automotive electric motor includes a core body, the core body including a plurality of laminates, each laminate including a plurality of apertures formed therein, the apertures in each laminate being axially aligned to define a plurality of magnets extending axially through the core body, the plurality of magnets being stacked axially along the length of the core body in each of a plurality of magnetic slots, each of the plurality of magnetic slots including a cavity extending axially along the length of the core body and a wedge inserted into the cavity, the wedge being adapted to apply a lateral force to the plurality of magnets in at least one magnetic slot to secure the plurality of magnets in the at least one magnetic slot.

Description

Technical Field

[0001] The present disclosure relates to a permanent magnet rotor core for an automotive electric motor. More particularly, the present disclosure relates to preloading magnets into the rotor core to secure the magnets in place. Background Art

[0002] Lightweight, high-power-density electric motors, such as starters and generators, have been used in automobiles for many years. The demand for lighter units has led to the design of higher-speed motors and generators to maximize the unit's power-to-weight ratio. Recent advances in permanent magnet materials, such as ferrites and rare-earth compounds, are allowing designers to further increase the power density of rotating electric machines.

[0003] The use of permanent magnet materials in high-speed rotating electrical equipment presents numerous challenges in terms of material support and definition of magnetic energy paths, which have hindered the application of these materials in ultra-high-speed motors. In known motor rotors, multiple permanent magnets are embedded in magnetic slots formed within the laminated sheets of the rotor core. The shape and position of the slots within the laminated sheets define multiple pole pieces to form a series of magnetic poles. These poles force the magnetic flux to travel through multiple paths within the motor. The paths that connect the stator windings and produce useful torque are called main flux paths. Other paths that are not connected to the stator winding circuit do not produce torque and are generally referred to as leakage flux paths.

[0004] A key design consideration for permanent magnet motors using permanent magnets is minimizing leakage flux paths. The movement of the permanent magnets within the magnet slots causes changes in the flux paths, resulting in leakage flux. The magnetic flux field follows a flux path that can be strengthened or weakened. Increasing or strengthening the flux field allows the motor to temporarily increase torque production. Weakening the flux field counteracts the motor's existing magnetic field. A weakened magnetic field limits torque production.

[0005] Known permanent magnet rotor designs that have been proposed require combining magnetic and non-magnetic materials in a high-speed rotor configuration. This type of bonding is difficult to achieve during rotor manufacturing. Other designs use trapezoidal magnets that are pressed axially against each other, allowing the permanent magnets to be firmly wedged in place. Manufacturing permanent magnets with such complex shapes is expensive, and dimensional tolerances on the permanent magnets can result in the magnets not fitting completely within the core or not completely filling the length of the core.

[0006] Another limitation of current rotor designs is the maximum speed at which the rotor can rotate before the laminate structure within the core deforms under centrifugal forces. Modern electric motors require high-speed motors, where the rotor rotates at very high speeds. The magnetic slots formed within the laminate define webs between adjacent slots. At high rotational speeds, the centrifugal forces generated by the spinning rotor bias the mass of the magnets placed within the slots outward. These centrifugal forces exert stress on the webs between the slots, ultimately causing the laminate to deform at these webs.

[0007] Therefore, while current permanent magnet electric machines achieve their intended purpose, a need exists for a new and improved rotor core for use in electric machines that uses wedges to provide lateral force against the magnets within the slots, thereby pre-loading the magnets within the slots and securing them in place, while also inducing compressive stresses in the webs between the slots, thereby increasing the maximum speed at which the rotor can rotate before mechanical failure occurs. Summary of the Invention

[0008] According to several aspects of the present disclosure, a rotor core for an automotive electric motor includes a core stack comprising a plurality of lamination plates, each lamination plate including a plurality of apertures formed therein, the apertures in each lamination plate being axially aligned to define a plurality of magnetic slots extending axially through the core, a plurality of magnets being stacked axially in each of the plurality of magnetic slots along the length of the core, at least one of the plurality of magnetic slots including a cavity extending axially along the length of the core and a wedge inserted into the cavity, the wedge being adapted to apply a lateral force to the plurality of magnets in the at least one magnetic slot to secure the plurality of magnets in the at least one magnetic slot.

[0009] According to another aspect, the cavity within at least one magnetic slot includes a projection defining a lateral support surface for a wedge, the wedge being positioned between the projection and the plurality of magnets within the at least one magnetic slot.

[0010] According to another aspect, the wedge is made of a non-magnetic material.

[0011] According to another aspect, the cavity includes a concave block opposite to the convex block, the concave block extending toward the web of the rotor core.

[0012] According to another aspect, the wedge includes a first corner block and a second corner block, each of the first corner block and the second corner block including an inclined surface, the inclined surface of the first corner block contacting the inclined surface of the second corner block, wherein when the first corner block and the second corner block are axially pushed into each other, the sliding of the first corner block and the second corner block relative to each other on the inclined surfaces forces the first corner block and the second corner block to expand laterally against the protrusion and the plurality of magnets.

[0013] According to another aspect, the wedge block includes a first step block and a second step block, each of the first step block and the second step block including a plurality of inclined surfaces, the inclined surfaces of the first step block contacting corresponding inclined surfaces of the second step block, wherein when the first step block and the second step block are axially pushed into each other, sliding of the first step block and the second step block relative to each other on the inclined surfaces forces the first step block and the second step block to expand laterally against the protrusion and the plurality of magnets.

[0014] According to another aspect, the wedge includes a tube of deformable material, the tube press-fitted into a cavity between the support surface of the projection and the plurality of magnets, the tube urging laterally outward against the support surface of the projection and the plurality of magnets.

[0015] According to another aspect, the rotor core further includes a first support insert positioned within the cavity adjacent the lug and extending along the length of the core.

[0016] According to another aspect, the wedge includes a plurality of deformable members positioned within a cavity between the first support insert and the plurality of magnets, the plurality of deformable members being axially compressed within the cavity and urged laterally outward against the first support insert and the plurality of magnets.

[0017] According to another aspect, the deformable insert has one of a cylindrical shape and a spherical shape.

[0018] According to another aspect, the wedge includes a strip of corrugated material positioned within the cavity between the first support insert and the plurality of magnets, the strip of corrugated material being axially compressed within the cavity and urged laterally outward against the first support insert and the plurality of magnets.

[0019] According to another aspect, the wedge includes a strip of corrugated material press-fitted within a cavity between the first support insert and the plurality of magnets, the strip of corrugated material urging laterally outward against the first support insert and the plurality of magnets.

[0020] According to another aspect, the wedge includes a strip formed therein having a deformable feature, the strip having a thickness greater than a distance between the first support insert and the plurality of magnets such that the strip is urged laterally outward against the first support insert and the plurality of magnets.

[0021] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0023] Figure 1 is a perspective view of a rotor core according to an exemplary embodiment of the present disclosure;

[0024] FIG2 is a top view of magnetic slots within a laminate of a prior art rotor core;

[0025] Figure 3A yes Figure 1 An enlarged view of the rotor core, such as Figure 1 Surrounded and marked as " Figure 3A ” The area indicated by

[0026] Figure 3B yes Figure 3A An enlarged view of Figure 3A Surrounded and marked as " Figure 3B ” The area indicated by

[0027] Figure 4A It is along Figure 3B A cross-sectional view taken along the center line 4A-4A illustrates an exemplary embodiment of the present disclosure, wherein the wedge block includes a first corner block and a second corner block;

[0028] Figure 4B is a cross-sectional view illustrating another exemplary embodiment of the present disclosure, wherein the wedge block includes a first stepped block and a second stepped block;

[0029] Figure 5 is a cross-sectional view illustrating another exemplary embodiment of the present disclosure, wherein the wedge comprises a tube of flexible material;

[0030] Figure 6A is a cross-sectional view illustrating another exemplary embodiment of the present disclosure, wherein the wedge includes a plurality of deformable cylindrical members;

[0031] Figure 6B is a schematic diagram of a deformable cylindrical member loosely placed in the cavity of a magnetic slot;

[0032] Figure 6C is a schematic diagram of a deformable cylindrical member being axially compressed in the cavity of a magnetic slot;

[0033] Figure 7A is a schematic diagram of a deformable spherical member loosely placed in the cavity of a magnetic slot;

[0034] Figure 7B is a schematic diagram of a deformable spherical member being axially compressed in the cavity of a magnetic slot;

[0035] Figure 8A is a schematic diagram of a wedge comprising a corrugated strip loosely placed within a cavity of a magnetic slot;

[0036] Figure 8B It is a schematic diagram of the corrugated strips being axially compressed in the cavity of the magnetic slot;

[0037] Figure 9A is a perspective view of a wedge including a strip having a deformable feature; and

[0038] Figure 9B yes Figure 9A Schematic diagram of the center wedge, where the strip is press-fit into the cavity of the magnetic slot. DETAILED DESCRIPTION

[0039] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0040] See Figure 1 A rotor core 10 for an automotive electric motor includes a core 12 comprising a plurality of identical laminates 14. The rotor core 12 is from an electric motor within an automobile, such as, but not limited to, a starter, a generator, a starter / generator, or other electric motor. Each laminate 14 is made of a ferrous material, such as, but not limited to, steel or non-oriented electrical steel. The laminates 14 are positioned adjacent to each other along a central axis 16 to define the core 12. The core 12 has an inner diameter 18 and an outer diameter 20.

[0041] Each laminate 14 includes a plurality of apertures 22 formed therein. The laminates 14 are aligned relative to one another along the central axis 16 such that the apertures 22 of each laminate 14 are axially aligned with corresponding apertures 22 of adjacent laminates 14 to define a plurality of magnetic slots 24. The magnetic slots 24 extend axially through the core 12 parallel to the central axis 16. The magnetic slots 24 are adapted to support a plurality of permanent magnets 26 stacked axially within each of the plurality of magnetic slots 24 along a length 28 of the core 12.

[0042] exist Figure 1 In the exemplary embodiment shown, the core 12 includes eight symmetrical groups of magnetic slots 24 evenly spaced about the core 12. Each group of magnetic slots 24 includes four magnetic slots 24 oriented in a V-shape. The magnetic slots 24 in each group further define an outer flux guide 30, a middle flux guide 32, and an inner flux guide 34. The outer flux guide 30, the middle flux guide 32, and the inner flux guide 34 provide a magnetic flux path for flux current during operation of the rotor core 10.

[0043] 2 , in a prior art design, the magnetic slot 24′ includes an opening 36′ to increase the magnetic resistance path and encourage electrical flux to pass through the outer flux guide 30′, the middle flux guide 32′, and the inner flux guide 34′. In this prior art design, the magnetic slot 24′ includes features 38′ adapted to support the permanent magnet 26′ within the magnetic slot 24′. These features 38′ are adapted to prevent movement and misalignment of the permanent magnet 26′ within the magnetic slot 24′ as much as possible. However, there must be sufficient clearance between the features 38′ and the permanent magnet 26′ to allow the permanent magnet 26′ to be inserted into the magnetic slot 24′, thereby causing some potential movement of the permanent magnet 26′.

[0044] Referring again to FIG. 2 , the position and shape of the magnetic slots 24 ′ define webs 27 ′. The webs 27 ′ are located within the V-shape of each set of magnetic slots 24 ′ and interconnect adjacent outer flux guides 30 ′, center flux guides 32 ′, and inner flux guides 34 ′. These webs are the structurally weakest portion of the core 12 . When the rotor core 10 rotates at high speeds, centrifugal forces act on the permanent magnets 26 ′, pushing them radially outward and stressing the webs 27 ′. At sufficiently high rotational speeds, the centrifugal forces can become high enough to cause deformation and mechanical failure within the core 12 .

[0045] See Figure 3A and Figure 3B In the rotor core 10 of the present disclosure, each magnetic slot 24 includes an opening 36 to increase the magnetic resistance path and encourage electrical flux to pass through the outer flux guide 30, the middle flux guide 32, and the inner flux guide 34. The magnetic slots 24 also include features 38 suitable for supporting the permanent magnets 26 within the magnetic slots 24. In addition, at least one magnetic slot 24 in the plurality of magnetic slots 24 includes a cavity 40 extending axially along the length 28 of the core 12. The cavity 40 within at least one magnetic slot 24 includes a protrusion 42 defining a lateral support surface 44.

[0046] like Figure 3A As shown, a wedge 46 is inserted into the cavity 40. The wedge 46 is adapted to apply a lateral force to the plurality of magnets 26 within at least one magnetic slot 24 to preload and secure the plurality of magnets 26 within the at least one magnetic slot 24 and induce compressive stress in the web 27 between adjacent magnetic slots 24. The wedge 46 is positioned between the projection 42 and the plurality of magnets 26 within at least one magnetic slot 24. The projection 42 is positioned adjacent the "top" of the magnetic slot 24, where the wedge will act upon one end of the permanent magnet 26 and adjacent the corner of the permanent magnet 26 closest to the web 27. This provides a shortest path for more effectively transferring the compressive stress to the web 27. It should be understood that any number or all of the magnetic slots 24 may include a cavity 40 and a wedge 46 adapted to secure the magnets 26 therein.

[0047] In the exemplary embodiment, the wedge 46 is made of a non-magnetic material. The wedge 46 does not provide a simple leakage flux path and therefore does not interfere with the magnetic flux path through the outer flux guide 30 , the middle flux guide 32 , and the inner flux guide 34 .

[0048] See Figure 3B , wherein cavity 40 is shown without wedge 46 positioned therein. In the exemplary embodiment, the distance between support surface 44 of projection 42 and plurality of magnets 26 is specifically designed to correspond to the lateral thickness of wedge 46 to ensure that wedge 46 functions properly within cavity 40 and applies lateral force to plurality of magnets 26 to secure magnets 26 within magnetic slots 24.

[0049] The cavity includes a recess 47 opposite to the protrusion 42. The recess 47 provides a gap between the protrusion 42 and the cavity wall 49 opposite to the protrusion 42 to reduce magnetic flux leakage between the protrusion 42 and the cavity wall 49 opposite to the protrusion 42. The recess 47 extends toward the web 27 of the rotor core 12, wherein the web 27 of the rotor core 12 of the present disclosure is substantially similar to the web 27' of the prior art rotor core. Figure 3A and Figure 3BAs shown, the cavity wall 49 opposite to the protrusion 42 includes a first portion 49A that is substantially parallel to the wedge 46 and perpendicular to one end of the permanent magnet 26. The cavity wall 49 opposite to the protrusion 42 further includes a second portion 49B that is inclined upward so that the shape of the concave block 47 faces the web 47.

[0050] See Figure 4A , schematically showing the rotor core along Figure 3A A cross-sectional view along the center line 4A-4A. Figure 4A As shown, in the exemplary embodiment, the wedge block 46 includes a first corner block 50 and a second corner block 52. As shown, the first corner block 50 has a right-angled triangular shape, including an outer side 150 adjacent to and in contact with the support surface 44 of the projection 42 and parallel to the central axis 16 of the core 12, an end 250 perpendicular to the central axis 16 of the core 12, and an inclined surface 350 facing laterally inward toward the plurality of magnets 26. The second corner block 52 has a right-angled triangular shape, including an outer side 152 adjacent to and in contact with the plurality of magnets 26 and parallel to the central axis 16 of the core 12, an end 252 perpendicular to the central axis 16 of the core 12, and an inclined surface 352 facing laterally inward toward the projection 42.

[0051] The inclined surface 350 of the first corner block 50 contacts the inclined surface 352 of the second corner block 52. When the first corner block 50 and the second corner block 52 are axially pushed toward each other, as indicated by arrows 54, the sliding movement of the first corner block 50 and the second corner block 52 relative to each other on the inclined surfaces 350, 352 forces the first corner block 50 and the second corner block 52 to expand laterally outward, as indicated by arrows 56. As the first corner block 50 and the second corner block 52 move laterally outward, the outer side 150 of the first corner block 50 pushes laterally against the support surface 44 of the projection 42, while the outer side 152 of the second corner block 52 pushes laterally against the plurality of magnets 26. The outward push of the first corner block 50 and the second corner block 52 against the projection 42 and the magnets 26 applies a preload force to the plurality of magnets 26, thereby securing the plurality of magnets 26 within the magnet slots 24 and preventing any movement of the plurality of magnets 26 during operation of the rotor core 10.

[0052] See Figure 4B, shows a schematic diagram of another exemplary embodiment of a wedge block 46, wherein the wedge block 46 includes a first stepped block 60 and a second stepped block 62. The first stepped block 60 and the second stepped block 62 each include a plurality of inclined surfaces 360 and 362. As shown, the first stepped block 60 has an outer side 160 adjacent to and in contact with the support surface 44 of the projection 42 and parallel to the central axis 16 of the core 12, an end 260 perpendicular to the central axis 16 of the core 12, and three inclined surfaces 360 facing laterally inward toward the plurality of magnets 26. The second stepped block 62 has an outer side 162 adjacent to and in contact with the plurality of magnets 26 and parallel to the central axis 16 of the core 12, an end 262 perpendicular to the central axis 16 of the core 12, and three inclined surfaces 362 facing laterally inward toward the projection 42.

[0053] Each inclined surface 360 ​​of the first step block 60 contacts one of the inclined surfaces 362 of the second step block 62. It should be understood that any suitable number of inclined surfaces 360, 362 may be provided on the first step block 60 and the second step block 62, as long as the first step block 60 and the second step block 62 have the same number of inclined surfaces 360, 362. When the first step block 60 and the second step block 62 are axially pushed toward each other, as indicated by arrow 64, the sliding movement of the first step block 60 and the second step block 62 relative to each other on the inclined surfaces 360, 362 forces the first step block 60 and the second step block 62 to expand laterally outward, as indicated by arrow 66.

[0054] As the first and second stepped blocks 60, 62 move laterally outward, outer sides 160 of the first stepped blocks 60 push laterally against the support surfaces 44 of the projections 42, while outer sides 162 of the second stepped blocks 62 push laterally against the plurality of magnets 26. The outward pushing of the first and second stepped blocks 60, 62 against the projections 42 and magnets 26 applies a preload force to the plurality of magnets 26 to secure the plurality of magnets 26 within the magnet slots 24 and prevent any movement of the plurality of magnets 26 during operation of the rotor core 10.

[0055] See Figure 5In another exemplary embodiment, wedge 46 includes a tube 70 made of a deformable material. For ease of illustration, tube 70 is shown partially inserted into cavity 40 of magnet slot 24. Tube 70 has a generally hollow cylindrical shape and an outer diameter 72. Prior to insertion, outer diameter 72 is greater than the distance 48 between projection 42 and the plurality of magnets 26 within cavity 40. Tube 70 is press-fitted into cavity 40 between support surface 44 of projection 42 and the plurality of magnets 26. When tube 70 is pressed into place, as indicated by arrow 74, tube 70 slightly collapses due to the interference fit. Because tube 70 is made of a flexible material, it compresses rather than completely collapses during insertion. Once tube 70 is pressed into cavity 40, the elastic properties of tube 70 cause tube 70 to push laterally outward against support surface 44 of projection 42 and the plurality of magnets 26, as indicated by arrow 76.

[0056] See Figure 6A In another exemplary embodiment, the wedge 46 includes a plurality of deformable members 80 disposed within the cavity 40. Figure 6B , the rotor core 12 includes a first support insert 82 positioned within the cavity 40 adjacent to the tabs 42 and extending axially along the length 28 of the core 12. The first support insert 82 is a strip of material that spans across all of the laminates 14 to provide solid support. A plurality of deformable members 80 are positioned within the cavity 40 between the first support insert 82 and the plurality of magnets 26. As shown, the rotor core 12 further includes a second support insert 48 positioned within the cavity 40 adjacent to the plurality of magnets 26 and extending axially along the length 28 of the core 12.

[0057] When the plurality of deformable members 80 are axially compressed, the deformable members 80 compress in the axial direction and squeeze laterally outward to push laterally against the first support insert 82 and the second support insert 84 and pass through the first support insert 82 and the second support insert 84, the support surface 44 of the projection 42, and the plurality of magnets 26. The first support insert 82 and the second support insert 84 ensure that the plurality of deformable members 80 comprising the wedge 46 are not squeezed between the laminate sheets or between adjacent pairs of magnets in the plurality of magnets, so that all of the lateral expansion force from the deformable members 80 is transferred along the length of the core 12 to the projection 42 and the plurality of magnets 26.

[0058] See again Figure 6A and Figure 6B In another exemplary embodiment, the deformable member 80 is cylindrical and hollow. The deformable member 80 has a resting diameter 86 that is smaller than the distance between the first support insert 82 and the second support insert 84. The deformable members 80 are stacked between the first support insert 82 and the second support insert 84, with the radially outer wall 88 of the deformable member 80 facing the first support insert 82 and the second support insert 84, and the radially outer wall 88 of the deformable member 80 facing the adjacent deformable member 80.

[0059] See Figure 6C When an axial force is applied to the stack of deformable members 80, as indicated by arrow 90, the cylindrical deformable members 80 compress and squeeze axially outward, as indicated by arrow 92, to push against the first support insert 82 and the second support insert 84, thereby pushing against the support surface 44 of the projection 42 and the plurality of magnets 26. The deformable members 80 can be made of any suitable compressible material, such as rubber. The deformable members 80 can be placed individually between the first support insert 82 and the second support insert 84, or bonded together in a stack and inserted as a single piece.

[0060] See Figure 7A In another exemplary embodiment, the rotor core 10 includes a spherical deformable member 94. The spherical deformable member 94 can be hollow or solid. The spherical deformable member 94 has a resting diameter 96 that is less than the distance 88 between the first support insert 82 and the second support insert 84. The spherical deformable member 94 is stacked between the first support insert 82 and the second support insert 84. Figure 7B When an axial force is applied to the stack of spherical deformable members 94, as indicated by arrow 98, the spherical deformable members 94 are compressed and squeezed laterally outward, as indicated by arrow 100, to push against the first support plug 82 and the second support plug 84, thereby pushing against the support surface 44 of the protrusion 42 and the plurality of magnets 26.

[0061] In another exemplary embodiment, the wedge 46 includes a strip of corrugated material 102 positioned within the cavity 40 between the first support insert 82 and the second support insert 84. Figure 8A The strip of corrugated material 102 has a rest thickness 104 that is less than the distance 88 between the first support insert 82 and the second support insert 84. The strip of corrugated material 102 is placed within the cavity 40 between the first support insert 82 and the second support insert 84. Figure 8B When an axial force is applied to the corrugated material strip 102 , as shown by arrow 106 , the corrugated material strip 102 elastically and plastically deforms to compress axially and expand laterally to push against the first support insert 82 and the second support insert 84 , as shown by arrow 108 .

[0062] Alternatively, see again Figure 8A , the corrugated material strip 102 has a rest thickness that is greater than the distance 88 between the first support insert 82 and the second support insert 84. The corrugated material strip 102 is stretched axially, as indicated by arrow 110, so that the corrugated material strip 102 elastically plastically deforms and elongates axially, and is compressed laterally to a thickness that is less than the distance 88 between the first support insert 82 and the second support insert 84. When stretched in this manner, the corrugated material strip 102 is positioned within the cavity 40 between the first support insert 82 and the second support insert 84. See again Figure 8B When the axial force stretching the strip of corrugated material 102 is removed, the strip of corrugated material 102 springs back to its rest shape due to elasticity, wherein the strip of corrugated material 102 is axially compressed and laterally expanded to contact the first support insert 82 and the second support insert 84. The elastic properties of the strip of corrugated material 102 exert a force on the first support insert 82 and the second support insert 84, as indicated by arrows 108.

[0063] In yet another variation having a wedge 46 including a strip of corrugated material 102, the strip of corrugated material 102 has a rest thickness that is greater than the distance 88 between the first support insert 82 and the second support insert 84. The strip of corrugated material 102 is axially press-fitted between the first support insert 82 and the second support insert 84. When the strip of corrugated material 102 is pressed between the first support insert 82 and the second support insert 84, the strip of corrugated material 102 elastically plastically deforms to laterally compress the strip of corrugated material 102 between the first support insert 82 and the second support insert 84. Once press-fitted between the first support insert 82 and the second support insert 84, the elastic properties of the strip of corrugated material 102 exert a force on the first support insert 82 and the second support insert 84, as Figure 8B As shown by arrow 108 in FIG.

[0064] The corrugated strip 102 applies force through alternating peaks and valleys. The first and second support inserts 82 , 84 evenly distribute the laterally outward force to the projections 42 and the plurality of magnets 26 along the length 28 of the core 12 .

[0065] In another exemplary embodiment, the wedge 46 includes a strip 112 having a deformable feature 114 formed therein. Figure 9A and 9B , one example of such a strip 112 includes a sinusoidal shape defining a deformable feature 114 in the form of a plurality of alternating curved peaks and valleys. The strip 112 having the deformable feature 114 has a rest thickness 116 that is greater than the distance 88 between the first support insert 82 and the second support insert 84. The strip 112 having the deformable feature 114 is axially press-fitted between the projection 42 and the plurality of magnets 26. Alternatively, the strip 112 having the deformable feature 114 may be axially press-fitted between the first support insert 82 and the second support insert 84, as Figure 9B shown.

[0066] When the strip 112 with the deformable feature 114 is pressed between the first support insert 82 and the second support insert 84, the strip 112 with the deformable feature 114 elastically plastically deforms to laterally compress the strip 112 with the deformable feature 114 between the first support insert 82 and the second support insert 84. Once press-fitted between the first support insert 82 and the second support insert 84, the elastic properties of the deformable feature 114 exert a force on the first support insert 82 and the second support insert 84, as shown in FIG. Figure 9B 1. It should be appreciated that the deformable features 114 may include features embossed into the strip 112, such as indentations extending from one or both sides of the strip 112, wherein the indentations elastically plastically deform to compress laterally between the first support insert 82 and the second support insert 84 when press-fitted between the first support insert 82 and the second support insert 84.

[0067] The rotor core 10 of the present disclosure has several advantages. These advantages include the ability to secure the magnets 26 within the magnetic slots 24 to preload the magnets 26 and prevent the magnets 26 from moving within the magnetic slots 24 without requiring the magnets 26 to be designed with a complex trapezoidal shape. Another advantage of the rotor core of the present disclosure is that the wedges 46 cause the webs 27 of the rotor core 12 to compress, preventing the webs 27 of the rotor core 12 from deforming and failing due to the centrifugal forces to which the rotor core is subjected during high-speed rotation.

[0068] The description of the present disclosure is merely exemplary in nature, and variations that do not depart from the gist of the present disclosure are intended to fall within the scope of the present disclosure. Such variations should not be regarded as a departure from the spirit and scope of the present disclosure.

Claims

1. A rotor core for an automotive motor, comprising: a core comprising a plurality of laminates; each laminate including a plurality of apertures formed therein, the apertures of each laminate axially aligned to define a plurality of magnetic slots extending axially through the core; a plurality of magnets stacked axially along the length of the core within each of the plurality of magnetic slots; at least one magnetic slot of the plurality of magnetic slots includes a cavity extending axially along the length of the core; as well as a wedge inserted into the cavity, the wedge being adapted to apply a lateral force to the plurality of magnets in the at least one magnetic slot to secure the plurality of magnets in the at least one magnetic slot and to provide a preload force in the laminate to increase the resiliency of the rotor core to centrifugal stress; wherein the cavity within the at least one magnetic slot includes a projection, the projection defining a lateral support surface for the wedge, the wedge being positioned between the projection and the plurality of magnets within the at least one magnetic slot; The wedge block comprises a tube made of a deformable material, the tube being press-fitted into the cavity between the support surface of the protrusion and the plurality of magnets, and the tube being pushed laterally outward against the plurality of magnets.

2. The rotor core according to claim 1, wherein: The wedge is made of non-magnetic material.

3. The rotor core according to claim 2, wherein: The cavity includes a concave block located opposite to the convex block, and the concave block extends toward the web of the rotor core.

4. The rotor core according to claim 3, wherein: The tube is pushed laterally outward against the support surface of the projection and the plurality of magnets.

Images