System and method for installing rotor sleeves

Abstract

An assembly includes a rotor assembly having a rotor stack having a rotor outer diameter and a rotor shaft extending along a rotational axis of the rotor assembly. A mandrel includes a mandrel outer diameter extending between a proximal end and a distal end, with a rotor engagement surface at the distal end of the mandrel. The mandrel outer diameter includes a first cylindrical portion adjacent the proximal end and a conical portion distal to the first cylindrical portion, with a first transition portion connecting the first cylindrical portion to the conical portion. The assembly further includes a sleeve having a sleeve inner diameter that, in an unexpanded state, is smaller than the rotor outer diameter.

Description

INTRODUCTION

[0001] The present disclosure relates to electrical machines and, more particularly, to electrical machines including rotor assemblies with press-fit sleeves.

[0002] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, include one or more electric machines and a battery system. The battery system supplies power to the one or more electric machines and receives energy from the one or more electric machines and / or a utility device. The battery system includes one or more battery cells, battery modules, and / or battery packs. A power control system is used to control the charging and / or discharging of the battery system during charging and / or driving.

[0003] Electrical machines consist of a rotor and a stator. During manufacturing of the electrical machines, a reinforcing sleeve may be installed on an outer surface of the rotor to prevent expansion of the rotor assembly during operation. SUMMARY

[0004] An assembly is disclosed herein. The assembly includes a rotor assembly having a rotor stack with a rotor outer diameter and a rotor shaft extending along a rotational axis of the rotor assembly. A mandrel has a mandrel outer diameter extending between a proximal end and a distal end, with a rotor engagement surface at the distal end of the mandrel. The mandrel outer diameter includes a first cylindrical portion adjacent the proximal end and a conical portion distal to the first cylindrical portion with a first transition portion connecting the first cylindrical portion to the conical portion. The assembly further includes a sleeve having a sleeve inner diameter that, in the unexpanded state, is smaller than the rotor outer diameter.

[0005] Another aspect of the disclosure may be that a mandrel inner diameter engages an outer diameter of a bearing reference on the rotor assembly, wherein a fastener engages the bearing reference to secure the mandrel to the rotor assembly.

[0006] Another aspect of the disclosure may be that the mandrel has a second cylindrical portion distal from the conical portion, wherein the second cylindrical portion is connected to the conical portion by a second transition portion.

[0007] Another aspect of the disclosure may be that at least one of the first transition sections or the second transition sections on the mandrel has a radius of curvature.

[0008] Another aspect of the disclosure may be that the radius of curvature is greater than the thickness of the sleeve divided by twice the maximum material elongation of a material of the sleeve.

[0009] Another aspect of the disclosure may include a polymer ring having a drive contact surface on a first axial end face and a sleeve contact surface on a second axial end face configured to engage a proximal end of the sleeve.

[0010] Another aspect of the disclosure may include a press having a sleeve drive with a body portion defining a central opening for surrounding the mandrel and a distal end having a ring engagement surface for engagement of the drive contact surface with the polymer ring and a pressure relief hole extending through and defined by the body portion.

[0011] Another aspect of the disclosure may include a mounting base having a cylindrical body defining a central opening for receiving a portion of the rotor shaft of the rotor assembly.

[0012] Another aspect of the disclosure may include a flange disposed at an outer periphery of the distal end of the mandrel, wherein a radially inner side of the flange defines a portion of a circumferential channel recessed into the distal end of the mandrel.

[0013] Another aspect of the disclosure may be that the rotor outer diameter and the mandrel outer diameter are each covered with a continuous material coating and the continuous material coating comprises a radially outer surface that lies radially outside the rotor outer diameter and the mandrel outer diameter relative to the axis of rotation.

[0014] Another aspect of the disclosure may be that the distal end of the mandrel includes at least one projection configured to fit into a corresponding alignment opening defined by a portion of the rotor assembly.

[0015] Disclosed herein is a method for installing a sleeve on a rotor assembly. The method includes aligning a mandrel outer diameter of a mandrel relative to a rotor outer diameter of a rotor assembly. The mandrel outer diameter includes a first cylindrical portion adjacent a proximal end, a tapered portion distal to the first cylindrical portion, and a first transition portion connecting the first cylindrical portion to the tapered portion. The method also includes pressing the sleeve with a drive on a press over the mandrel outer diameter and onto the rotor assembly, wherein the sleeve is configured to exert a compressive force on a portion of the rotor assembly surrounded by the sleeve.

[0016] Another aspect of the disclosure may include positioning a polymer ring between a proximal end of the sleeve and a distal end of the driver.

[0017] Another aspect of the disclosure may be that pressing the sleeve over the mandrel outer diameter includes expanding a radial dimension of the sleeve to align it with a radial dimension of an outer surface of the rotor assembly.

[0018] Another aspect of the disclosure may include attaching the mandrel to a bearing reference on a shaft of the rotor assembly to align a rotor outer diameter on a rotor stack with the mandrel outer diameter. A mandrel inner diameter engages an outer diameter of a bearing reference on the rotor assembly.

[0019] Another aspect of the disclosure may be that the mandrel has a second cylindrical portion distal from the conical portion and is connected to the conical portion by a second transition portion.

[0020] Another aspect of the disclosure may be that a distal end of the mandrel has a flexible flange that encloses an outer periphery of the distal end and flexes to align with a radially outer surface of the rotor assembly.

[0021] Another aspect of the disclosure may include overmolding the mandrel and rotor assembly with a polymer coating and machining the polymer layer over the mandrel and rotor assembly to provide a smooth transition for the sleeve in the radial direction between the mandrel and rotor assembly.

[0022] Another aspect of the disclosure may include applying a lubricant to the mandrel outer diameter and the rotor outer diameter and pressing the sleeve over the mandrel and rotor assembly at a speed equal to or greater than the hydrodynamic lubrication speed of the applied lubricant.

[0023] Disclosed herein is a press assembly for disposing a sleeve onto a rotor assembly. The press assembly includes a press with a drive and a mount for supporting the rotor assembly. The rotor assembly includes a rotor stack having a rotor outer diameter and a rotor shaft extending along a rotational axis of the rotor assembly. The press assembly further includes a mandrel having a mandrel outer diameter extending between a proximal end and a distal end and having a rotor engagement surface at the distal end of the mandrel. The mandrel outer diameter includes a first cylindrical portion adjacent the proximal end, a conical portion distal to the first cylindrical portion, and a first transition portion connecting the first cylindrical portion to the conical portion. The sleeve has a sleeve inner diameter that, in the unexpanded state, is smaller than the rotor outer diameter. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 illustrates an exemplary press assembly for assembling an exemplary rotor assembly. Fig. Figure 2 is an enlarged view of a mandrel mounted on the rotor assembly of Fig. 1 is aligned. Fig. Figure 3 is an enlarged view of a cut surface of the mandrel of Fig. 2 with the rotor arrangement of Fig. 1. Fig. Figure 4 is an enlarged view of a cross-sectional view of another exemplary mandrel and rotor assembly of Fig. 1. Fig. 5 illustrates yet another exemplary mandrel aligned with another exemplary rotor assembly. Fig. 6 illustrates a method of arranging a sleeve on the rotor assembly of Fig. 1 or the rotor arrangement of Fig. 5.

[0024] The present disclosure may be modified or embodied in alternative forms, representative embodiments of which are shown in the drawings and described in detail below. The present disclosure is not limited to the disclosed embodiments. Rather, the present disclosure is intended to cover alternatives falling within the scope of the disclosure as defined by the appended claims. EXACT DESCRIPTION

[0025] Those skilled in the art will recognize that terms such as "above," "below," "up," "down," "top," "bottom," "left," "right," etc., are used illustratively in the figures and do not represent limitations on the scope of the disclosure as defined by the appended claims. Furthermore, the instructions herein may be described in terms of functional and / or logical block components and / or various processing steps. It should be realized that such block components may include multiple hardware, software, and / or firmware components configured to perform the specified functions.

[0026] With reference to the figures, in which like reference numerals designate like parts, and with reference to the drawings, in which like reference numerals refer to like components, Fig. 1 is a schematic view of a press assembly 20 used to place a sleeve 50 onto a rotor assembly 40 using a mandrel 46. In the illustrated example, the press assembly 20 includes an upper frame support 22 and a lower frame support 24. The upper frame support 22 at least partially supports a press arm 26, such as a servo press, with a sleeve drive 28 attached to a distal end of the press arm 26 to move the sleeve 50 relative to the rotor assembly 40.

[0027] In the example shown, the rotor assembly 40 comprises a stack of laminations forming a rotor stack 44 having a rotor outer diameter 56, wherein a rotor shaft 42 is arranged along a rotational axis A ( Fig. 2) of the rotor assembly 40. During assembly, the rotor assembly 40 is supported by a mounting base 32 that is attached to the lower frame support 24. The mounting base 32 includes a cylindrical body having a central opening 34 for receiving a portion of the rotor assembly 40. In the illustrated example, the mounting base 32 receives a portion of a rotor shaft 42 in the central opening 34. A distal end of the mounting base 32 opposite the lower frame support 24 includes a ledge that engages an edge of the rotor stack 44 to prevent longitudinal movement of the rotor assembly 40 relative to the rotational axis A.

[0028] As in the Fig. 1 and Fig. 2, the mandrel 46 is press-fitted onto the rotor assembly 40 and may be secured with or without a fastener 54, such as a screw. In the illustrated example, the fastener 54 threadably engages a bearing datum 58 at one end of the rotor shaft 42, and an inner diameter 46D of the mandrel 46 engages an outer diameter of the bearing datum 58. A feature of this mounting arrangement is improved alignment between a rotor outer diameter 56 on the rotor stack 44 and a mandrel outer diameter 48 on the mandrel 46.

[0029] In addition, a plurality of jackscrews 60 are disposed radially outward of the fastener 54 and are threadedly engaged with the mandrel 46 along a shank of the jackscrews 60. The jackscrews 60 assist in removing the mandrel after the sleeve 50 has been installed by extending to engage a portion of the rotor assembly 40.

[0030] The mandrel outer diameter 48 on the mandrel 46 extends between a proximal end 62 of the mandrel 46 and a distal end 64 of the mandrel 46. The distal end 64 includes a rotor engagement surface that directly abuts a portion of the rotor assembly 40. As shown in Fig. 2, the mandrel outer diameter 48 includes a first cylindrical portion 48A adjacent the proximal end 62, a tapered portion 48B distal from the first cylindrical portion 48A, and a second cylindrical portion 48C adjacent the distal end 64. A first transition portion 48T connects the first cylindrical portion 48A to the tapered portion 48B, and a second transition portion 48T connects the tapered portion 48B to the second cylindrical portion 48C. An inner diameter of the sleeve 50 may have a sleeve inner diameter that is greater than or equal to a diameter of the first cylindrical portion 48A and less than a diameter of either the tapered portion 48B or the second cylindrical portion 48C. This allows the sleeve 50 to be easily placed over the proximal end 62 of the mandrel 46 during installation.

[0031] At least one of the first transition sections 48T or the second transition section 48T in the mandrel 46 has a radius of curvature connecting the first and second cylindrical sections 48A and 48C to the conical section 48B. One feature of the transition sections 48T is to prevent damage to the sleeve 50 during installation when the sleeve 50 moves over portions of the mandrel 46 with different conical shapes. In one example, the radius of curvature of the transition sections 48T is greater than or equal to a thickness of the sleeve 50 divided by twice the maximum material elongation of a material of the sleeve 50.

[0032] As in Fig. 1, a ring 52, such as a polymer ring made of nylon or Torlon, is disposed at a proximal end of the sleeve 50. The ring 52 includes a first axial face defining a drive contact surface for engagement with a distal end of the sleeve drive 28 and a second axial face defining a sleeve contact surface for engagement with a proximal end of the sleeve 50. A feature of the ring 52 is to reduce lateral loads on the sleeve 50 and to uniformly apply pressure to the sleeve 50 to reduce damage to the sleeve 50. Another feature of the ring 52 is that it expands with the sleeve 50 to apply an axial force to the sleeve 50 as the sleeve 50 expands. In particular, the sleeve 50 is designed with a substantially greater strength in the circumferential direction than in the longitudinal direction in order to exert compressive stress on the rotor stack 44 with low weight.In one example, the sleeve 50 is made of a carbon fiber material. Furthermore, the distal end of the mandrel 46 and the proximal end of the rotor assembly 40 may have a fillet or radius of curvature along their outer diameters to facilitate the transition and prevent damage to the sleeve 50 as it passes between them.

[0033] As in Fig. 1, the press arm 26 includes the sleeve drive 28 at a distal end having a body portion 29 for engaging the ring 52 and for pressing the sleeve 50 onto the rotor assembly 40. The distal end 28D of the sleeve drive 28 defines a ring engagement surface surrounding an inner chamber 31 for receiving the mandrel 46 in pressing the sleeve 50 over the mandrel 46 and onto the rotor assembly 40. A pressure relief hole 30 extends through and is defined by a portion of the body portion 29 to relieve pressure built up in the inner chamber 31.

[0034] As in the Fig. 2 and Fig. 3, a flange 66, such as a flexible flange, is disposed on an outer periphery of the distal end 64 of the mandrel 46. A radially inner side of the flange 66 defines a portion of a circumferential channel 68 recessed into the distal end 64 of the mandrel 46. A feature of the flange 66 is that it is deflectable radially inward relative to a longitudinal axis of the mandrel 46 to provide improved alignment between the mandrel 46 and the rotor assembly 40.

[0035] Due to manufacturing limitations, it can be difficult to machine and install the mandrel 46 with tolerances between the mandrel outer diameter 48 and the rotor outer diameter 56 that do not damage the sleeve 50 during installation. The sleeve 50 can be prone to failure during installation because the hoop strength of the sleeve 50 is significantly greater than the longitudinal strength of the sleeve 50. The compressive force of the sleeve 50 can cause the flange 66 to deflect or bend radially inward during installation and align with the rotor outer diameter 56. In addition, this allows the mandrel outer diameter 48 at the distal end 64 to be manufactured to a greater tolerance than the rotor diameter 56 to allow the flange 66 to accommodate diameter variations.

[0036] Fig. 4 shows another exemplary mandrel 146 adjacent to the rotor assembly 40. The mandrel 146 is similar to the mandrel 46, except that the mandrel 146 does not include the flange 66 with the adjacent channel 68. Similar or identical components between the mandrel 46 and the mandrel 146 have an added leading "1."

[0037] In the illustrated example, both a mandrel outer diameter 148 of the mandrel 146 and the rotor outer diameter 56 of the rotor assembly 40 are covered with a continuous coating or material layer 70. In one example, the material coating comprises a polymeric material. The continuous material coating 70 includes a radially outer surface that lies radially outward of the rotor outer diameter 56 and the mandrel outer diameter 48 relative to the rotational axis A. The material coating 70 provides a continuous surface upon which the sleeve 50 can slide. In one example, the material coating 70 can be machined after it has been applied to both the mandrel 146 and the rotor assembly 40. After the sleeve 50 is installed, the mandrel 146 can be separated from the rotor assembly by breaking the material coating 70.The material coating 70 can be removed from the mandrel 146 so that the mandrel 146 can be attached to another rotor assembly 40.

[0038] Fig. 5 shows another exemplary mandrel 246 and another exemplary rotor assembly 240. The mandrel 246 and rotor assembly 240 are similar to the mandrel 46 and rotor assembly 40, respectively, except for the differences described below or shown in the drawings. Similar or identical components between the mandrel 46 and rotor assembly 40, respectively, and the mandrel 246 and rotor assembly 240, respectively, have a leading "2" added.

[0039] The mandrel 246 includes a proximal end 262 and a distal end 264 in abutting contact with a rotor stack 244 in the rotor assembly 240. The rotor assembly 240 includes a rotor shaft 242. The distal end 264 of the mandrel 246 includes at least one projection 265, such as a pin with a round or oval cross-section, that engages an alignment opening 245 or recess in the rotor stack 244 in the rotor assembly 240. The interface between the at least one projection 265 and the alignment opening 245 provides improved alignment between the mandrel outer diameter 248 on the mandrel 246 and the radially outer surface 256 on the rotor stack 244 of the rotor assembly 240.

[0040] Fig. 6 shows an exemplary method 300 for disposing the sleeve 50 on the rotor assembly 40. The method 300 also applies to disposing the sleeve 50 on the rotor assembly 240, with the differences noted below. The method 300 begins at block 302 by positioning one of the rotor assemblies 40 in the mounting base 32. This allows the rotor assembly 40 to float laterally within the mounting base 32 to facilitate improved alignment during the compression of the sleeve 50, as explained below.

[0041] In block 304, the mandrel 46 is aligned with the rotor assembly 40. The mandrel 46 is aligned with the rotor assembly 40 by aligning the mandrel outer diameter relative to the rotor outer diameter. Alignment can be accomplished by aligning a central longitudinal axis of the mandrel 46 with the rotational axis A of the rotor assembly 40. This ensures that deviations between the mandrel outer diameter and the rotor outer diameter are minimized to reduce damage to the sleeve 50 during installation. In the case of the rotor assembly 240 and mandrel 246, the projection 265 on the mandrel 246 is inserted into the alignment opening 245 on the rotor assembly 240.

[0042] The mandrel 46 can be attached to the rotor assembly 40, with the fastening element 54 engaging the bearing cover 58 on the rotor assembly 40. While the Fig. 1, Fig. 2 and Fig. 5 shows two jackscrews 60, four or more jackscrews 60 may be arranged in a circle around the bearing cover 58 and used to remove the mandrel 46 from the rotor assembly 40 after the sleeve has been installed.

[0043] In another example, aligning the mandrel 46 with the rotor assembly 40 includes overmolding the mandrel 46 and the rotor assembly 40 with the material coating 70. The material coating 70 may be machined to provide a smooth transition for the sleeve 50 in the radial direction between the mandrel 46 and the rotor assembly 40.

[0044] In block 306, the sleeve 50 is disposed around a proximal end of the mandrel 46. Because the mandrel 46 has a first cylindrical portion 48A with a diameter less than or equal to the inner diameter of the sleeve 50, the sleeve 50 can be relatively easily disposed on the mandrel 46 and the ring 52 can be disposed on the sleeve 50.

[0045] In block 308, the sleeve 50 is pressed over the mandrel 46 and onto the rotor assembly 40 on the press arm 26 by the sleeve drive 28. The sleeve drive 28 engages the ring 52 to apply even pressure to the sleeve 50 during pressing, thereby reducing the possibility of damage to the sleeve 50 during installation. Because the mandrel 46 has a cylindrical section and a conical section, the sleeve 50 expands in a radial direction as it is moved over the transition section to follow the outer diameter of the conical section. As the sleeve 50 is pressed over the mandrel 46, pressurized air can build up in the inner chamber 31. The pressure can be relieved through the pressure relief hole 30 in the sleeve drive 28.

[0046] As the sleeve 50 is pressed over the mandrel 46 and onto the rotor assembly 40, lubricant may be applied to the mandrel diameter 48 and / or the rotor outer diameter 56. As shown in Fig. 1, spray nozzles 80 may be used to apply the lubricant 82 to the outer diameters 48, 56. While two spray nozzles 80 are shown in the illustrated example, additional spray nozzles 80 could be arranged in a circle around the mandrel 46 and the rotor assembly 40 to provide additional lubrication during the pressing operation. In another example, the rotor assembly 40 and / or the mandrel 46 include internal passages 84 ( Fig. 1) for distributing the lubricant along the outer diameters 48, 56.

[0047] Furthermore, the sleeve 50 is pressed over the mandrel 46 and the rotor assembly 40 at a speed sufficient to achieve a hydrodynamic lubrication velocity in the lubricant 82. In one example, the velocity is greater than 0.5 to 1 meter per second at a sleeve pressure of 30 MPa.

[0048] In block 310, the sleeve drive 28 is retracted from the mandrel 46, and the ring 52 is removed from its position around the rotor assembly 40 and the mandrel 46. The mandrel 46 can then be separated from the rotor assembly 40 in block 312, with the sleeve 50 enclosing the rotor outer diameter 56 and exerting a compressive force on the rotor assembly 40.

[0049] The terms "a" and "an" do not imply a limitation of number, but rather denote the presence of at least one of the referenced elements. The term "or" means "and / or" unless clearly indicated otherwise by context. A reference throughout the application text to "an aspect" means that a particular element (e.g., a feature, structure, step, or characterization) described in connection with the aspect is included in at least one aspect described herein and may or may not be present in further aspects. In addition, it is to be understood that the described elements in the various aspects may be combined in any suitable manner.

[0050] When an element, such as a layer, lamina, region, or substrate, is referred to as "on" another element, it may be directly adjacent to the other element or may also have intervening elements present. In contrast, when an element is referred to as "directly adjacent" to another element, no intervening elements are present.

[0051] Unless otherwise specified herein, examination standards are the most recent standard in force as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the examination standard appears.

[0052] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0053] While the above disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include embodiments that fall within its scope.

Claims

[1] Arrangement which includes: a rotor assembly having a rotor stack with a rotor outer diameter and a rotor shaft extending along an axis of rotation of the rotor assembly; a mandrel having a mandrel outer diameter extending between a proximal end and a distal end, wherein a rotor engagement surface is present at the distal end of the mandrel, the mandrel outer diameter having a first cylindrical portion adjacent to the proximal end and a conical portion distal to the first cylindrical portion, a first transition portion connecting the first cylindrical portion to the conical portion; and a sleeve with an inner diameter that is smaller than the rotor outer diameter in the unexpanded state. [2] The assembly of claim 1, wherein a mandrel inner diameter engages an outer diameter of a bearing reference on the rotor assembly and a fastener engages the bearing reference to secure the mandrel to the rotor assembly. [3] The assembly of claim 2, wherein the mandrel includes a second cylindrical portion distal to the conical portion, the second cylindrical portion being connected to the conical portion via a second transition portion. [4] Arrangement according to claim 3, wherein at least the first transition section and / or the second transition section on the mandrel have a radius of curvature. [5] The assembly of claim 4, wherein the radius of curvature is greater than the thickness of the sleeve divided by twice the maximum material elongation of a material of the sleeve. [6] The assembly of claim 1, comprising a polymer ring having a drive contact surface on a first axial end face and a sleeve contact surface on a second axial end face configured to engage a proximal end of the sleeve. [7] An assembly according to claim 6, comprising a press having a sleeve drive with a body portion defining a central opening for surrounding the mandrel and a distal end having a ring engagement surface for engagement of the drive contact surface on the polymer ring and a pressure relief hole extending through and defined by the body portion. [8] An assembly according to claim 1, comprising a mounting base having a cylindrical body defining a central opening for receiving a portion of the rotor shaft of the rotor assembly. [9] The assembly of claim 1, comprising a flange disposed on an outer periphery of the distal end of the mandrel, a radially inner side of the flange defining a portion of a circumferential channel recessed into the distal end of the mandrel. [10] The assembly of claim 1, wherein the rotor outer diameter and the mandrel outer diameter are each covered with a continuous coating of material, and the continuous coating of material has a radially outer surface that lies radially outwardly of the rotor outer diameter and the mandrel outer diameter relative to the axis of rotation.

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