Technique for sub-micron radial alignment of electric motor component and air flow management to extend motor lifespan

Abstract

To provide a technique for sub-micron radial alignment of a motor component.SOLUTION: A rotor bore alignment device 124 is provided with a shaft. The shaft has extendable members 126-1, 126-2, and 126-3. The extendable members selectively transition from a retracted position to an extended position. The retracted position radially extends the extendable members from the shaft to a first distance, and the extended position radially extends the extendable members from the shaft to a second distance. The second distance is larger than the first distance. The shaft is configured to slidably couple into a bore to a predefined position. The predefined position aligns the extendable members with a first motor component such that transitioning of the extendable members to the extended position causes radial alignment of the first motor component with a second motor component.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 62 / 944,068, filed December 5, 2019, which is hereby incorporated by reference in its entirety.

[0002] This specification generally relates to electric motors, and more specifically to techniques for sub - micron radial alignment of motor components and a diffuser device for use in an electric motor that deflects an air stream to create one or more air jets for cooling core motor components such as windings and rotor assemblies.

Background Art

[0003] Electric motors are used in a wide range of consumer and industrial applications. A wide variety of electric motors are available, and electric motors tend to be classified into one of two broad motor types: brushed motors and brushless motors.

[0004] For example, a brushed DC motor has a permanent magnet on the outside of its structure and a rotating armature on the inside. The non - moving permanent magnet on the outside is called the stator. The rotating armature that contains electromagnets is called the rotor. In a brushed DC motor, when current flows through the armature, the rotor rotates 180 degrees. To sustain rotation, the poles of the electromagnet need to be reversed. As the rotor rotates, the brushes contact the stator, reversing the magnetic field and enabling the rotor to rotate a full 360 degrees.

[0005] On the other hand, a brushless DC motor does not include brushes and uses DC current. A brushless DC motor is essentially inside - out, eliminating the need for brushes to reverse the electromagnetic field. In a brushless DC motor, for example, permanent magnets are on the rotor and electromagnets are on the stator. Then, the circuit can charge the electromagnets in the stator to rotate the rotor a full 360 degrees.

[0006] In any case, the radial alignment of the rotor within the electric motor significantly affects the performance and reliability of the motor. For example, angular and / or radial misalignment of the rotor shaft significantly affects the nominal power / torque of the motor, introduces acoustic noise (e.g., via vibration), and can ultimately lead to early component failure, e.g., based on uneven loading along the associated rotor shaft.

[0007] The drawings included herein are for the purpose of illustrating various embodiments of the articles, methods, and equipment of the teachings herein and are not intended to limit the scope of what is taught in any way.

Brief Description of the Drawings

[0008]

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[0009] As described above, the radial alignment of the rotor shaft within an electric motor significantly affects the performance and reliability of the motor. Electric motors, such as brushless DC (BLDC) motors, can be formed from a plurality of parts / segments sandwiched together within a stack arrangement. For example, some electric motors include a housing portion that couples with a stator assembly disposed therebetween. The housing portion and the stator assembly can each include an opening / through-hole that aligns to collectively provide a rotor bore. However, when the various components of the motor are coupled together, various amounts of deviation are introduced. This deviation is ultimately combined such that the resulting bore has a deviation of up to 150 microns or more from end to end as each component introduces additional misalignment. Ideally, the resulting bore has a deviation of 0 microns from end to end (e.g., is perfectly concentric), but such 0 micron deviation is practically difficult to achieve. This is due to inherent manufacturing deviations in the components of the motor and a manufacturing process that simply cannot identify and compensate for such deviations. The minute deviations introduced by each successive motor component can ultimately combine to result in a substantial radial misalignment of the rotor shaft.

[0010] Such end-to-end deviations along the rotor bore proportionally introduce uneven loading of the rotor shaft and, for example, due to wear and heat generated in the rotor assembly, not only significantly reduce the operating life of the motor but also tend to introduce acoustic noise due to vibration.

[0011] Accordingly, the present disclosure generally aims at techniques for the radial alignment of motor components relative to each other to achieve an electric motor having a rotor bore with sub-micron end-to-end deviations, such as less than 50 microns, and preferably less than 10 microns. More specifically, a rotor bore alignment tool is disclosed herein that can be inserted between a plurality of motor components and, more specifically, between the openings / through-holes defined by each of the motor components, such as the housing section and the stator assembly. The rotor bore alignment tool includes an expandable member that can be selectively shifted to an extended position to radially align each of the motor components before fixedly connecting each of the motor components within a so-called "stack" that forms the motor. When the motor components are fixedly connected together, for example via an adhesive and / or screws, the resulting motor includes a rotor shaft that extends end-to-end with a sub-micron deviation, for example preferably less than 10 microns, more preferably 5 microns or less.

[0012] In one embodiment, the electric motor includes a first housing portion that defines a first rotor receptacle for receiving and coupling to a first end of the rotor assembly. The electric motor further includes a second housing portion that defines a second rotor receptacle for receiving and coupling to a second end of the rotor assembly, and the first housing portion and the second housing portion are configured to be coupled together and to collectively provide a rotor bore for receiving the rotor assembly. The rotor assembly is disposed within the rotor bore, and the rotor assembly includes a shaft and a first bearing and a second bearing concentrically coupled along the shaft. The first bearing can be disposed within the first rotor receptacle of the first housing portion, and the second bearing can be disposed within the second rotor receptacle of the second housing portion. The shaft and the associated first and second bearings are preferably radially aligned with each other based on the rotor bore collectively provided by the first housing portion and the second housing portion having an end-to-end offset deviation of less than 10 microns, more preferably 5 microns or less.

[0013] Referring to the figures, FIGS. 1-4 illustrate a motor 100 consistent with one embodiment of the present disclosure. The motor 100 is preferably configured as an electric motor, more preferably as a brushless DC (BLDC) motor. Note that the present disclosure illustrates and describes various aspects and features with specific reference to a BLDC motor. However, the present disclosure is not limited in this regard, and the present disclosure is equally applicable with minor modifications to other electric motor types, such as brushed motors, for example.

[0014] The motor 100 includes a housing, which is shown collectively as 102 and individually as first, second, and third housing portions 102-1, 102-2, 102-3, respectively (see FIG. 3). Thus, the housing 102 may also be referred to herein as a multi-component or multi-part housing. The housing 102 may be formed from, for example, plastic, metal, or any other suitably rigid material. Each portion of the housing 102 preferably includes a thermoplastic material having a relatively high heat resistance and tensile strength. For example, the housing 102 is preferably formed from acrylonitrile butadiene styrene (ABS).

[0015] Referring specifically to FIG. 3, each of the housing portions 102-1 to 102-3 is configured to be radially aligned with each other along the longitudinal axis 150 such that when they are joined together during manufacture, their respective openings / through-holes are generally aligned. As will be further discussed below, each of the housing portions 102-1 to 102-3 can include relatively large manufacturing tolerances to allow for a relatively coarse adjustment prior to subsequent radial alignment (e.g., via an extendable mandrel consistent with the present disclosure) and attachment / fixing steps.

[0016] Subsequently, the first housing portion 102-1 includes a base having a plurality of fitting protrusions from which the fitting protrusions extend along the longitudinal axis 150. The fitting protrusions are configured to interlock with corresponding fitting sections of the second housing portion 102-2. Therefore, the first housing portion and the second housing portion may be configured to be connected together via the fitting protrusions, which may also be referred to herein as an interlocking fitting portion or simply an interlocking portion.

[0017] The mating protrusion preferably includes an offset alignment tolerance of at least 50 microns or more, more preferably 100 - 150 microns. The offset alignment tolerance allows for a radial displacement of the first and second housing parts 102-1, 102-2 relative to each other, as will be discussed in more detail below.

[0018] In addition, the mating protrusion is also preferably configured to maintain the angular alignment of the first and second housing parts 102-1, 102-2. This angular alignment can be maintained by supplying a compressive force (or clamping force) along the longitudinal axis 150 that displaces the first and second housing parts 102-1, 102-2 towards each other and clamps them together via an extendable mandrel / member during manufacturing, as will be discussed further below.

[0019] Subsequently, the first housing part 102-1 further defines a first rotary receptacle 104-1, and the second housing part 102-2 further defines a second rotary receptacle 104-2, at least partially based on the respective openings / through-holes described above. The first and second housing parts 102-1, 102-2 further define a stator cavity 105 (which may also be simply referred to as a cavity herein) for receiving a stator assembly (e.g., stator assembly 111) and aligning it with an associated rotor assembly (e.g., rotor assembly 106).

[0020] More specifically, each of the stator components of the stator assembly 111 is radially aligned along the longitudinal axis 150 and is configured to be connected together in a sandwiched / stacked configuration. As shown in FIG. 3, the stator components of the stator assembly 111 include a first winding liner 110-1, followed by a stator stack 112 and a second winding liner 110-2. The stator stack 112 can comprise a plurality of laminations. For example, the stator stack 112 can comprise a plurality of iron laminations radially aligned with each other.

[0021] The first and second winding liners 110-1, 110-2 are configured to receive and hold the winding 108 at a predefined position with respect to the stator stack 112 within the stator cavity 105 such that the winding 108 is arranged around the rotor assembly 106 within the housing 102. The winding 108 can include, for example, copper or other suitable materials. Thus, the stator components are connected together and collectively provide a radially aligned stator assembly disposed within the stator cavity 105.

[0022] As shown in FIG. 3, the rotor assembly is collectively shown at 106 and individually shown at 106-1 to 106-4. The rotor assembly 106 includes a shaft 106-4 and a plurality of components concentrically coupled to the shaft 106-4. Specifically, the rotor assembly 106 includes a first bearing 106-1, a second bearing 106-2, and a magnet 106-3, each coaxially and concentrically coupled to the shaft 106-4.

[0023] The first bearing 106-1 is disposed at the first end of the shaft 106-4 and is at least partially inserted into the first rotor receptacle 104-1. For this purpose, the first bearing 106-1 may be sized to a diameter substantially the same as the diameter of the first rotor receptacle to ensure a "perfect fit" without axial play / slant.

[0024] The second bearing 106-2 is disposed adjacent to the second end of the shaft 106-4. The second bearing 106-2 is at least partially inserted into the second rotor receptacle 104-2. The second bearing 106-2 is also sized to connect into the second rotor receptacle 104-2 without axial play.

[0025] The magnet 106-3 is preferably fixedly connected at an intermediate point of the shaft 106-4 via, for example, an adhesive or other attachment approach such that rotation of the shaft 106-4 causes rotation of the magnet 106-3.

[0026] As further shown, following the second winding liner 110-2 are a diffuser 114, a fan (or impeller) 116, a hub 118, and a third housing portion 102-3. The third housing portion 102-2 may also be referred to as a shroud in some cases.

[0027] Referring to FIG. 4 and additionally to FIG. 3, a cross-sectional view of the motor 100 shows the components of the motor 100 after they are radially aligned and fixedly connected together. As shown, the shaft bore (also simply referred to as the bore herein) is collectively formed by the openings / through-holes of the components of the motor 100 that are aligned along the longitudinal axis 150, and the bore has a maximum nominal offset deviation from end to end.

[0028] The end-to-end offset deviation in the context of the motor bore generally refers herein to the maximum amount of radial deviation between each radially / concentrically aligned hole / openings. For example, a 50 micron radial deviation / displacement between the openings / through-holes of the first housing portion 102-1 and the second housing portion 102-2 introduces an end-to-end offset deviation of at least 50 microns, assuming, for example, that other motor components do not have a larger misalignment amount.

[0029] The exemplary bore of FIG. 4 preferably has an end-to-end offset deviation of 10 to 50 microns, 10 microns ± 5 microns, and more preferably 5 microns or less. It is recognized that for the aspects and features of the present disclosure, the smaller the end-to-end offset deviation with respect to the bore, the longer the potential operating life of the motor 100. Stated another way, the closer the bore of the motor 100 is to an opening / bore with essentially zero deviation, e.g., a perfectly concentric bore, the longer the theoretical life of the motor 100, based on the shaft 106-4 of the rotor assembly 106 having a uniform load along its length. Similarly, it is desirable to dispose the shaft 106-4 concentrically within the bore of the motor, e.g., without angular misalignment. This alignment is also commonly referred to as the perpendicular alignment of the shaft 106-4 with respect to the motor housing 102.

[0030] In any case, one aspect of the present disclosure is to achieve a submicron end-to-end offset deviation with respect to the bore of the motor 100 to extend the maximum motor life and reduce or otherwise mitigate the wear of motor components and motor acoustics caused by rotor shaft misalignment.

[0031] FIGS. 5 and 6 demonstrate one exemplary approach for achieving the aforementioned submicron offset deviation with respect to the bore of an electric motor. As shown, before inserting the rotor assembly 106 into the bore of the motor 100, the extendable mandrel 124 is positioned / positioned in a retracted position such that the extendable mandrel 124 is inserted therein. The extendable mandrel 124 may also be referred to herein as a rotor bore alignment device. The extendable mandrel 124 may be formed having an elongated shaft with a substantially uniform diameter along its entire length and an overall length greater than the length of the associated rotor bore. The diameter of the shaft of the extendable mandrel 124 preferably remains within ±10 microns along its entire length, and more preferably is 5 microns or less.

[0032] As shown, the extensible mandrel 124 includes a plurality of extensible members, namely, first, second, and third extensible members (126-1, 126-2, 126-3 respectively). The extensible mandrel 124 may include more or fewer extensible mandrels depending on the desired configuration. Preferably, the extensible mandrel 124 includes at least one extensible mandrel.

[0033] Each extensible member is disposed at a predetermined position along the shaft of the extensible mandrel 124. As shown, each of the first, second, and third extensible members 126-1, 126-2, 126-3 is disposed at a different location along the shaft of the extensible mandrel 124. The location of each extensible member is preferably predefined to align with the component(s) of the motor 100, and more preferably predefined to align with at least the first housing portion 102-1, the second housing portion 102-2, and the stator assembly 111.

[0034] For example, and as also shown in FIG. 5, the extensible mandrel 124 is preferably configured to be inserted into the bore of the motor 100 and to prevent further insertion by the flange 128 of the extensible mandrel 124 that engages the outer surface of the motor 100. Thus, as will be discussed in more detail below, each of the first, second, and third extensible members 126-1, 126-2, 126-3 may be disposed at a predetermined location along the extensible mandrel 124 at a location that aligns each extensible member with the target component of the motor 100 when the extensible mandrel 124 is disposed within the bore of the motor 100.

[0035] The extendable mandrel 124 further includes an actuating member (or arrangement) 130 and a sleeve 132. The sleeve 132 includes a slidable section that moves in a linear manner along the longitudinal axis of the extendable mandrel 124. The sleeve 132 preferably defines angled surfaces that form V-shaped grooves 134. Each V-shaped groove preferably extends radially about the shaft of the extendable mandrel 124. Each extendable member 126-1 to 126-3 is disposed within an associated V-shaped groove. Next, the sleeve 132 is slidably moved to increase the width of each V-shaped groove, allowing the extendable members to transition to a retracted position such that the extendable members 126-1 to 126-3 extend radially from the shaft to a first distance D1, as shown in FIG. 5. The first distance D1 may be configured to allow slidable insertion of the extendable mandrel 124 into the bore of the motor 100.

[0036] On the other hand, the sleeve 132 may then slidably reduce the width of each V-shaped groove, for example, via linear movement along the shaft of the extendable mandrel 124, and as a result, "pinch" and displace the extendable member to transition to an extended position / positioning. The displacement of the extendable member causes an overall increase in diameter of the extendable member and extends radially outward from the shaft of the extendable mandrel 124 to a second distance D2. The first distance D1 is preferably from 0 to 100 microns, more preferably less than 10 microns. In a preferred embodiment, the overall diameter of the extendable mandrel 124 with the extendable member in the retracted positioning is then preferably about 9.25 mm. The second distance D2 is preferably from 500 to 800 microns, more preferably 500 ± 100 microns. In a preferred embodiment, the overall diameter of the extendable mandrel 124 with the extendable member in the extended positioning is then preferably about 9.7 to 10.0 mm. In this preferred embodiment, the outer diameter of the extendable mandrel 124 increases / decreases in a uniform manner along the entire length of the extendable mandrel 124, whereby when the extendable member transitions from the retracted positioning to the extended positioning, it extends from the shaft of the extendable mandrel 124 at a distance within ±5 microns of each other, and vice versa.

[0037] Each of the extendable members 126-1 to 126-3 preferably includes a material having an elasticity that allows for the aforementioned increase in the overall diameter. Thus, upon extension, each of the extendable members 126-1 to 126-3 is enabled to extend to a second distance D2 that is displaced as a result by the associated V-groove. Similarly, the elasticity of the material of the extendable members 126-1 to 126-3 preferably enables the extendable members to return to their original state and reduce the overall diameter to a first distance D1, for example, based on the increase and width of the V-groove. Some such exemplary materials having suitable elasticity and rigidity include, for example, nitrile butadiene rubber (NBR), carboxylated nitrile butadiene rubber (XNBR), and / or fluoroelastomers (e.g., VITON (trademark)). It should be noted that other approaches for expanding the overall diameter of the extendable mandrel 124 are within the scope of the present disclosure, and the provided examples are not intended to be limiting.

[0038] Subsequently, the actuation of the extendable members 126-1 to 126-3 can occur based on the rotation of the actuating member 130. As shown in FIG. 5, the actuating member 130 is a threaded screw / shaft that causes a linear displacement / movement of the sleeve 132 in response to its rotation. Thus, the actuating member 130 and the sleeve 132 may also be pneumatic and hydraulic, as well as a rack and pinion arrangement, which is configured to convert the rotational movement of the actuating member 130 into a linear movement of the sleeve 132.

[0039] Therefore, when the extendable mandrel 124 is inserted into the bore of the motor 100, the extendable mandrel 124 reaches a predefined position (or alignment position) based on, for example, the flange 128 that is seated against the sidewall of the first housing portion 102-1. At the predefined position, it is preferable that the first extendable member 126-1 is aligned with the first housing portion 102-1, the second extendable member 126-2 is aligned with the stator assembly 111, and the third extendable member 126-3 is aligned with the second housing portion 102-2.

[0040] Next, the first, second, and third extendable members 126-1 to 126-3 may be shifted to an extended position based on, for example, a hydraulic component (not shown) that is fixedly connected to the actuating member 130 and causes its rotation. In response thereto, the sleeve 132 then slidably engages the extendable members, for example, by reducing the width of each corresponding V-groove, and slidably displaces the extendable members.

[0041] In response thereto, the first, second, and third extendable members 126-1 to 126-3 increase in diameter and radially extend to the second distance D2. Each of the first, second, and third extendable members 126-1 to 126-3 preferably extends in a synchronized manner at substantially the same rate and distance based on the actuating member 130. In any case, when the first, second, and third extendable members 126-1 to 126-3 shift to the extended position, a force is then applied substantially transverse to the shaft of the extendable mandrel 124 and, more importantly, to the bore of the motor 100. In response thereto, each of the first housing portion 102-1, the stator assembly 111, and the second housing portion 102-2 is radially displaced by the substantially transverse force transmitted by the aligned first, second, and third extendable members 126-1, 126-2, 126-3 shifting to the extended position.

[0042] In particular, the aforementioned radial displacement is at least partially achieved by an offset alignment tolerance 120 (see FIGS. 4 and 5) collectively provided by the first and second housing parts 102-1, 102-2. Specifically, the interlocking sections that enable the first and second housing parts 102-1, 102-2 to be connected together can be manufactured to allow a pre-defined amount of radial displacement of about 50 to 100 microns, for example, to provide the offset alignment tolerance 120. Therefore, when the extendable mandrel 124 transitions to an extended position, the offset alignment tolerance 120 allows the first and second housing parts 102-1, 102-2 to be displaced along a direction extending substantially transversely to the bore of the motor 100. The result of such displacement is the radial alignment of the first and second housing parts 102-1, 102-2, and this alignment achieves a sub-micron radial alignment of the bore collectively formed therebetween (see, for example, FIG. 6).

[0043] In particular, the extendable member of the extendable mandrel 124 can also introduce a compressive / tightening force that displaces the first and second housing parts 102-1, 102-2 towards each other, thereby ensuring that the interlocking parts of the first and second housing parts 102-1, 102-2 are directly connected to each other, for example, without a gap formed therebetween, achieving an angular alignment of the bore of the motor 100.

[0044] After the first and second housing parts 102-1, 102-2 have been aligned in the aforementioned sub-micron radial alignment by the extendable mandrel 124, the first and second housing parts 102-1, 102-2 may be fixedly connected to each other via an adhesive and / or a locking device. For example, the adhesive may be disposed on the surface forming the interface between the first housing part 102-1 and the second housing part 102-2. As another method, or in addition to the adhesive, bolts (e.g., metal bolts / rods) or screws may be inserted through the first and second housing parts 102-1, 102-2. In the scenario of using screws, the screws may optionally include a self-tapping head for penetrating the housing part.

[0045] After the first and second housing parts 102-1, 102-2 have been fixedly connected to each other, the extendable mandrel 124 may be shifted back to a retracted position, for example, based on the rotation of the actuating member 130. The extendable mandrel 124 may then be withdrawn from the bore of the motor 100.

[0046] As shown in FIG. 7, the shaft 106-4 of the rotor assembly 106 can include a plurality of step (or shoulder) features including at least first and second step features 134-1, 134-2. The first step feature 134-1 enables the end of the shaft 106-4 to be inserted into the opening / through-hole of the impeller 116 and "bottom out" against the first step 134-1. Therefore, the first step feature 134-1 can operate as a mechanical stop that enables the fan to achieve a perpendicular alignment with the aforementioned shaft 106-4.

[0047] The second step feature portion 134-2 includes a protrusion configured to engage a corresponding groove within the motor 100 and to prevent further insertion into the bore of the motor 100. For example, as shown in FIGS. 8 and 9, the rotor assembly 106 is inserted into the bore of the motor 100. Next, the second step feature portion 134-2 engages the groove 136 of the second housing portion 102-2, which functions as a mechanical stop to prevent further insertion of the rotor assembly 106. Therefore, the second step feature portion 134-2 of the rotor assembly 106 and the groove 136 of the second housing portion 102-2 ensure that the rotor assembly 106 is inserted into a predefined position within the bore of the motor 100, preferably simply by bottoming out. Therefore, the vertical alignment of the rotor assembly 106 and insertion into a predefined location within the bore of the motor 100 can be achieved by the mechanical stops provided by the first and second step features 134-1, 134-2 of the rotor assembly 106.

[0048] As shown in FIG. 10B, the preload of the bearing may be achieved via a spring-type bearing sleeve that is consistent with the present disclosure. As shown, the bore of the motor 100, more specifically the first bearing receptacle 104-1, is at least partially provided by the bearing sleeve 138. The bearing sleeve 138 includes a diameter that receives at least a portion of the first bearing 106-1 of the rotor assembly 106.

[0049] Next, a locking cap 140, as clearly shown by FIG. 10A, is coupled to the bearing sleeve 138 in a radially and axially aligned position, for example, based on the threaded portion of the locking cap 140 and the corresponding threaded slots of the bearing sleeve 138. The locking cap 140 provides an annular disk that extends substantially transverse to the bore of the rotor assembly 106 and the motor 100. As shown, a spring device 142, such as a wave washer, is disposed between the sidewall of the first housing portion 102-1 and the surface that defines the annular disk of the locking cap 140. Further shown, the first housing portion 102-1, more specifically, its sidewall, defines a confinement recess for receiving and holding the spring device 142 in alignment with the locking cap 140.

[0050] Next, the spring device 142 provides a spring biasing force along an axis that extends substantially parallel to the longitudinal axis of the rotor assembly 106 and the bore of the motor 100 and in a direction substantially away from the motor 100. Therefore, this spring biasing force "pulls (or pulls away)" the bearing sleeve 138 in order to introduce a preload to the first bearing 106-1.

[0051] The bearing sleeve 138 can include a material having a coefficient of thermal expansion that is less than the coefficient of thermal expansion of the material forming the first housing portion 102-1. Therefore, based on the heat generated, for example, during operation of the motor 100, the expansion of the first housing portion 102-1 can occur in a direction substantially parallel to the bore of the motor 100 without causing misalignment of the first bearing 106-1. Instead, the bearing sleeve 138 maintains pressure / force on the first bearing 106-1, which can generally be understood as a force that "pulls" the rotor assembly 106 towards the locking cap 140. However, the rotor assembly 106 remains radially aligned and is fixed within the bore of the motor 100, for example, based on a second step feature 134-2 that engages a groove 136 of the second housing portion 102-2.

[0052] Figures 11-13 show an embodiment of the diffuser 114 of FIG. 3 alone. As shown, the diffuser 114 includes a cylindrical body 144 that defines an opening / aperture 146 that allows the shaft of the rotor assembly 106 to extend therethrough along the longitudinal axis 150 (see FIGS. 1 and 3). The diffuser 114 further includes a band 148 (or rim) that is concentric with and surrounds the cylindrical body 144. The band 148 includes side walls that extend substantially parallel to the longitudinal axis 150. The band 148 is disposed adjacent to the first end 152-1 of the cylindrical body 144.

[0053] The diffuser 114 further defines a plurality of fins 154 that extend radially from the cylindrical body 144. The plurality of fins 154 may also be referred to herein as curved exhaust fins or exhaust fins. Such fins do not necessarily include the curved profile as shown in FIGS. 11-13 and may include other shapes and profiles depending on the desired configuration.

[0054] Each fin of the plurality of fins 154 is adjacent to the band 148 based on a first portion that extends from the first end 152-1 of the cylindrical body 144 along a direction that is substantially transverse to the longitudinal axis 150, and a second portion 156 extends from the band 148 and tapers to a position adjacent to the second end 152-2 of the cylindrical body 144. Thus, the band 148 only partially encompasses / surrounds the curved exhaust fins, whereby each tapered section of the exhaust fins (e.g., generally indicated at 156) is exposed to air and forms a blade-like (or wing) structure for exhaust.

[0055] As shown in FIG. 13, the plurality of fins 154 further define a plurality of air deflection channels generally indicated at 158. As shown in FIG. 13, the diffuser 114 defines at least three of such air deflection channels 158. The air deflection channels 158 are configured to generate an air jet that extends substantially transverse to the longitudinal axis 150, whereby the generated air jet induces cooling across the windings 108 and / or the rotor assembly 106 within the motor 100 (see FIGS. 1 and 4). This advantageously introduces cooling for the core components within the motor 100, can extend the operating life, can limit thermal expansion, and can enable the motor 100 to maintain nominal power over a longer period compared to an uncooled motor configuration.

[0056] FIGS. 14-15 show the third housing portion 102-3 of FIG. 3 alone. The third housing portion 102-3 may also be referred to as a shroud. As shown, one end of the third housing portion 102-3 defines an opening 199 for receiving air within the housing 102 (FIG. 10B).

[0057] FIGS. 16-18 collectively show a diffuser 214 of another exemplary embodiment suitable for use in the motor 100 of FIGS. 1-4 and / or the motor 100' of FIG. 23A. The diffuser 214 can be configured in a manner similar to that of the diffuser 114 discussed above for generating an air jet within the motor, and its description is not repeated for the sake of brevity.

[0058] However, also as shown in FIGS. 16-18, the diffuser 214 does not include an outer rim / band 148 (see FIG. 11). The present disclosure has revealed that omitting the rim / band 148 around the diffuser improves the aerodynamic performance of the diffuser 214 by reducing the formation of airflows, such as vortices, across the main flow along the surface of the associated fins, and the possibility of undesirable air recirculation within the housing of the motor, as will be discussed in more detail below.

[0059] As shown, the diffuser 214 includes a cylindrical body 244 that defines an opening / aperture 246 that allows the shaft of the rotor assembly 106 to extend therethrough along the longitudinal axis 150 (see FIG. 3). The cylindrical body 244 may also be referred to herein as the diffuser body or simply the body.

[0060] The diffuser 214 further defines a plurality of fins 254 that extend radially from the cylindrical body 244, such that the plurality of fins 254 extend substantially transversely to the rotor assembly 106 when extending through the opening 246. The plurality of fins 254 can be evenly distributed around the diameter of the cylindrical body 244 and preferably include a uniform distance between each fin. The fins 254 may also be referred to herein as curved exhaust fins or simply curved fins.

[0061] The plurality of fins 254 are preferably formed with the cylindrical body 244 as a single monolithic piece of material. For example, the cylindrical body 244 and the fins 254 may be formed from a single piece of composite material and / or thermosetting plastic. However, the present disclosure is not necessarily limited in this regard, and the cylindrical body 244 and the fins 254 may also be formed as separate parts that include the same or different materials.

[0062] As shown in FIGS. 16 and 17, each fin of the plurality of fins 254 includes a curved profile and preferably extends radially from the cylindrical body 244 for an overall length L1. The overall length L1 is preferably a distance of 4 - 6 mm, more preferably at least 5 mm. In one exemplary configuration, the overall length L1 is a length that is 10% - 50% of the radius R1 of the cylindrical body 244.

[0063] Each fin of the plurality of fins 254 includes upper and lower surfaces 270-1, 270-2 that extend from a first end 272-1 to a second end 272-2. The upper and lower surfaces 270-1, 270-2 are disposed opposite to each other and extend at a predetermined angle (θ) with respect to the upper surface 252 that defines the first end of the cylindrical body 244 (see FIG. 17). The predetermined angle (θ) is preferably an angle of 25 to 50 degrees, more preferably 30 to 35 degrees.

[0064] Each fin of the plurality of fins 254 preferably extends from a first end 272-1 to a second end 272-1 up to the overall height H2. The overall height H2 is preferably 13 to 16 mm. In one exemplary configuration, the overall height H2 is equal to or greater than the overall height H1 of the cylindrical body 244. Preferably, the overall height H1 is 9 to 10 mm.

[0065] As shown in FIG. 17, each fin of the plurality of fins 254 preferably includes a first end 272-1 having a distal surface substantially in the same plane as the upper surface 252 that defines the first end of the cylindrical body 244. Each fin of the plurality of fins 254 preferably further includes a second end 272-2 that extends beyond the bottom surface 257 that defines the second end of the cylindrical body 244.

[0066] The width W1 (FIG. 16) from the first end 272-1 to the second end 272-2 of each fin of the plurality of fins 254 preferably varies to provide a taper at one or both ends. The width W1 of each fin of the plurality of fins 254 can be, for example, 1 to 2 mm in length. The width W1 along the overall length of each fin of the plurality of fins 254 is more preferably up to 10 to 25% (0.1 to 0.25) of the overall length L1 that each fin extends from the cylindrical body 244. Therefore, the ratio of the width W1 of each fin to the length L1 can be 0.2:1.0 to 0.25:1.0, although other ratios are also within the scope of the present disclosure. Accordingly, each fin of the plurality of fins 254 can provide a blade-like structure for displacing air and diffusing air into the motor during operation.

[0067] As described above, the diffuser 214 shown in FIGS. 16-18 includes a rimless configuration that does not include the rim / band 148 (see FIG. 11). Accordingly, each fin of the plurality of fins 254 can include a portion distal to the cylindrical body 244 that is not connected to an adjacent rim structure. Stated another way, each fin of the plurality of fins 254 is connected to the cylindrical body 244 along a region of each fin proximate to the cylindrical body 244, whereby the distal end of each fin, which is distal to the cylindrical body 244, is preferably fully / wholly (e.g., to air) exposed. As shown in FIG. 17, this can include a distal end provided by the surface 259, which extends substantially transversely to and adjacent the first and second surfaces 270-1, 270-2 and is (fully) exposed to air.

[0068] Accordingly, air may then flow along the first and / or second surfaces 270-1, 270-2 in a first direction extending from the first end 272-1 to the second end 272-2 of each fin, and also in a second direction that is transverse to the first direction, for example allowing air to flow radially outward away from the cylindrical body 244 without being obstructed / impeded by the surface defining the rim 148 (see FIG. 11). This can advantageously improve aerodynamic performance by minimizing or otherwise reducing vortex formation that can reduce the overall amount of air recirculating / stagnating within the motor housing.

[0069] FIGS. 19-20 show an exemplary third housing portion 102-3' that is consistent with aspects of the present disclosure. The third housing portion 102-3' can be utilized as the third housing portion 102-3 / 2302-3 with the motor 100 of FIG. 1 and / or the motor 100' of FIG. 23A. The third housing portion 102-3' may also be referred to herein as a shroud in some cases.

[0070] The third housing part 102-3' preferably includes a dome-shaped profile that defines an inner cavity 1904. The third housing part 102-3' can include other shapes / profiles, and the embodiments shown in FIGS. 19-20 are not intended to be limiting.

[0071] The third housing part 102-3' further defines an opening 1906 at an end that communicates with the inner cavity 1904. Note that the opening 1906 can provide an opening 199 when connected to the motor (see FIG. 10B). The third housing part 102-3' preferably further provides a plurality of shoulder / step features, respectively shown as first, second, and third step features 1902-1, 1902-2, 1902-3. The specific number of step features shown in FIGS. 19-20 is not intended to be limiting, and more or fewer step features may be utilized depending on the desired configuration.

[0072] As will be discussed in more detail below, one or more such step features can be utilized as mechanical stops that allow the insertion of one or more sealing devices (also referred to herein as seal devices) to prevent air from entering and leaving the motor 100 through the gaps formed between the third housing part 102-3, the rotor assembly 106, and the fan / impeller 116.

[0073] FIG. 22A shows a cross-sectional view of an exemplary third housing part 2202-3 that includes a cavity 2204 defined by an inner sidewall 2256. The cavity 2204 may at least partially define an impeller windage chamber when the third housing part 2202-3 is connected to the motor. The exemplary third housing part 2202-3 may be utilized, for example, within the motors 100 and / or 100' of FIGS. 1 and 23A.

[0074] As further shown, the inner sidewall 2256 defines a plurality of riblets / projections 2258 that extend into the cavity 2204. Each of the riblet / projections of the plurality of riblets 2258 extends substantially parallel to each other and preferably forms a helical pattern along the entire inner diameter of the cavity 2204.

[0075] When the third housing portion 2102-3 is connected to the motor, the plurality of riblets 2258 are preferably angled to guide air along a direction that extends substantially parallel to the longitudinal axis of the motor, such as the longitudinal axis 150 of the motor 100 (see FIG. 4). Therefore, the plurality of riblets 2258 can also define at least a portion of the impeller compression chamber within the motor 100. The plurality of riblets 2258 can be formed from the same material (such as ABS plastic) as the third housing portion 2202-3, or from a different material (such as polyphenylene sulfide (PPS) or steel).

[0076] As further shown in FIG. 22A and the partial exploded view of FIG. 22B, the third housing portion 2202-3 can include a first seal insert 2262. Although the first seal insert 2262 is preferably formed from a deformable material such as a foam material, other materials (such as rubber) for the first seal insert 2262 are also within the scope of the present disclosure. For example, the first seal insert 2262 may include polytetrafluoroethylene, rubber, and / or nylon.

[0077] The first seal insert 2262 preferably includes a plurality of annular rings / projections 2280 that extend radially from the body. The projections 2280 may also be referred to herein as O-rings in some cases. The plurality of annular rings 2280 are preferably configured to extend into corresponding grooves 2278 defined by the third housing portion 2202-3 as shown in FIG. 22A. An example of such a groove is more clearly shown as groove 2178 in the cross-sectional view of FIG. 21.

[0078] Alternatively, the first seal insert 2262 may be implemented as a ring that does not necessarily include the annular ring / protrusion 2280. For example, as also shown in FIG. 22C, the first seal insert 2262' can include a substantially smooth outer surface. The first seal insert 2262' may be utilized, for example, when the third housing portion 2202-3 does not include the groove 2278.

[0079] In any case, the first seal insert 2262' may advantageously provide an axial seal 2244, for example, at the distal end / lip of the third housing portion 2202-3 (see FIG. 22A) adjacent to the surface defining the opening 2206, and / or may provide a radial seal based on the annular protrusion 2280 (see FIG. 22B).

[0080] Referring to FIGS. 23A-23B, another exemplary motor 100' is shown in accordance with aspects of the present disclosure. The motor 100' may be configured substantially the same as that of the motor 100, the teachings of which are equally applicable and will not be repeated for the sake of brevity. In particular, the motor 100' can also include sub-micron radial alignment for an associated rotor assembly that utilizes, for example, the extendable mandrel 124 as described above.

[0081] However, as also shown, the motor 100' includes a housing shown collectively as 2302 and individually as first, second, and third housing portions 2302-1, 2302-2, 2302-3, respectively, which include one or more pressure regulating valves 2390.

[0082] The one or more pressure regulating valves 2390 are preferably disposed along the third housing portion 2302-3 and more preferably disposed at a location on the third housing portion 2302-3 proximate to the impeller windage / compression chamber 2392 (see FIG. 23C).

[0083] Each pressure regulating valve of the one or more pressure regulating valves 2390 can include a nozzle that extends away from the third housing portion 2302-3. Each nozzle preferably extends radially from the third housing portion 2303-3 as shown in FIGS. 23A-23C. Although each nozzle can include a profiled return to enable a friction fit with an associated hose / tube as shown, other nozzle profiles are also within the scope of the present disclosure.

[0084] FIG. 23C shows a cross-sectional view of the motor 100' taken along line C-C of FIG. 23B according to one embodiment of the present disclosure.

[0085] As shown, each valve of the one or more pressure regulating valves 2390 includes a first end that extends from the third housing portion 2303-3 and defines an inlet. The inlet is in fluid communication with the valve actuator 2391. The valve actuator 2391 selectively fluidly couples the passage 2394 with the inlet, for example, based on the air pressure in the passage 2394 dropping below a predetermined threshold. The predetermined threshold may be selected to maintain the pressure in the impeller windage chamber 2392 at a target pressure. For example, the target pressure may be approximately atmospheric pressure ± 10 PSI, and thus the valve actuator 2391 may be configured to open based on the air pressure in the passage 2394 dropping below, for example, a first predetermined pressure value of -15 PSI.

[0086] In particular, the passage 2394 disposed at the distal end of the motor 100' (e.g., adjacent to the opening 2399) enables a pressure differential to be introduced along the shoulder 2398 of the impeller 2316 with respect to the impeller windage chamber 2392. Thus, the valve actuator 2391 may be configured to induce a pressure differential along the shoulder 2398 such that the air pressure proximal thereto is greater than the air pressure within the impeller windage chamber 2392. One such exemplary difference includes the air pressure proximate the shoulder 2398 of the impeller 2316 and is at least 0.1-0.2% higher than the air pressure within the impeller windage chamber 2392.

[0087] The first seal insert 2262 preferably provides an airtight seal having a surface that defines, for example, the impeller 2316, and prevents air communication from outside the motor 100' from entering into the shoulder 2398 of the impeller 2316. Thus, air is then substantially prevented from recirculating along the shoulder 2398 of the impeller 2316 and may instead be directed towards the components of the motor 100' within the housing 2302 (see FIG. 23A).

[0088] As further shown in FIG. 23C, the diffuser 2314 can include a rimless configuration as described above with respect to FIGS. 16 and 17. This may further increase the airflow through the motor 100' and may also minimize or otherwise reduce air recirculation. Thus, the motor 100' may then achieve a higher overall efficiency based on the increased airflow by removing the heat generated in the stator assembly within the motor 100'.

[0089] According to one aspect, a method of aligning sections of an electric motor during manufacture is disclosed. The method includes coupling a stator assembly between a first housing portion and a second housing portion to collectively provide a rotor bore extending therethrough, and inserting an extensible mandrel into the rotor bore, the extensible mandrel having a retracted position and an extended position, the retracted position providing the extensible mandrel with an outer diameter that is substantially equal to or less than the diameter for the rotor bore to enable insertion into the rotor bore; displacing the extensible mandrel to the extended position to radially displace the first housing portion, the second housing portion, and the stator assembly relative to one another, whereby the rotor bore extending therethrough has an end-to-end axial offset deviation of less than 50 microns, more preferably less than 10 microns; and subsequent to displacing the extensible mandrel to the extended position within the rotor bore, fixing the first and second housing portions to one another, whereby the rotor bore maintains the end-to-end axial offset deviation after the extensible mandrel is removed from the rotor bore.

[0090] The method can further include inserting the extensible mandrel into the rotor bore and further includes inserting the extensible mandrel into a predefined position within the rotor bore. Inserting the extensible mandrel into a predefined position can further include abutting a flange of the extensible mandrel against an outer sidewall of the first housing portion or the second housing portion.

[0091] In the method, inserting the extensible mandrel into a predefined position can further include aligning the extensible member of the extensible mandrel with each of the first housing portion, the stator assembly, and the second housing portion. In the method, transitioning the extensible mandrel to an extended position preferably causes axial displacement of the first housing portion, the stator assembly, and the second housing portion based on the aligned plurality of extensible members. In the present method, fixing the first and second housing portions to each other can further include disposing an adhesive on the interface between the first housing portion and the second housing portion. In the method, fixing the first and second housing portions to each other can further include inserting a screw therebetween.

[0092] According to another aspect of the present disclosure, an electric motor is disclosed. The electric motor includes a first housing portion defining a first rotor receptacle for receiving and coupling to a first end of a rotor assembly, and a second housing portion defining a second rotor receptacle for receiving and coupling to a second end of the rotor assembly, the first housing portion and the second housing portion being configured to couple together and collectively provide a rotor bore for receiving the rotor assembly, and a rotor assembly disposed within the rotor bore, the rotor assembly comprising a shaft and first and second bearings concentrically coupled along the shaft, the first bearing being disposed within the rotor receptacle of the first housing portion and the second bearing being disposed within the rotor receptacle of the second housing portion.

[0093] The electric motor can further include a sleeve disposed within a first rotary receptacle, the sleeve defining an opening for receiving at least a portion of a first bearing, a locking cap radially aligned and connected with the sleeve, the locking cap providing an annular disk extending substantially transversely to the rotor assembly, and a spring disposed between the first housing portion and the annular disk, the spring being substantially parallel to the rotor assembly and providing a spring force in a direction away from the first housing portion, the spring force preloading the first bearing.

[0094] In the electric motor, the first housing portion can include a first material having a first coefficient of thermal expansion, and the sleeve can include a second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being smaller than the first coefficient of thermal expansion. In the electric motor, the second housing portion can include a groove adjacent to the rotor bore, the groove engaging a step feature of the rotor assembly to prevent further insertion of the rotor assembly. In the electric motor, the spring can include a spring washer, and preferably the spring washer is disposed within a confinement recess defined by an outer sidewall of the first housing portion.

[0095] According to one aspect of the present disclosure, an electric motor is disclosed. The electric motor includes a first housing portion defining a first rotor receptacle for receiving and coupling to a first end of a rotor assembly, and a second housing portion defining a second rotor receptacle for receiving and coupling to a second end of the rotor assembly, the first housing portion and the second housing portion being configured to couple together and collectively provide a rotor bore for receiving the rotor assembly, and a rotor assembly disposed within the rotor bore, the rotor assembly comprising a shaft and at least a first bearing concentrically coupled along the shaft, the first bearing being disposed within the first rotor receptacle of the first housing portion or within the second rotor receptacle of the second housing portion, the shaft and the first bearing being radially aligned with each other based on the rotor bore collectively provided by the first and second housing portions having an end-to-end offset deviation of less than 10 microns.

[0096] According to another aspect of the present disclosure, a rotor bore alignment device for radial alignment of a bore collectively provided by a plurality of housing parts of an electric motor is disclosed. The rotor bore alignment device comprises a shaft having at least one extendable member disposed at a predefined location along the shaft, and selectively transitioning from a retracted positioning of the at least one extendable member to an extended positioning, the retracted positioning radially extending the at least one extendable member from the shaft by a first distance D1, and the extended positioning radially extending the at least one extendable member from the shaft by a second distance D2, the second distance D2 being greater than the first distance D1, and the shaft being configured to be slidably coupled into a predefined position within the bore, the predefined position being for aligning the at least one extendable member with at least a first motor component, whereby transitioning of the at least one extendable member to the extended positioning causes radial alignment of a first motor component and a second motor component of the electric motor.

[0097] According to one aspect of the present disclosure, a diffuser for use with an electric motor is disclosed. The diffuser comprises a cylindrical body defining an opening through which a shaft of a rotor assembly is enabled to extend, and a plurality of curved exhaust fins extending radially from the cylindrical body.

[0098] The principles of the present disclosure are described herein, but it should be understood by those skilled in the art that this description is provided by way of example only and is not intended to limit the scope of the present disclosure. Other embodiments are contemplated within the scope of the present disclosure in addition to the exemplary embodiments shown and described herein. It will be understood by those skilled in the art that the electric motor may embody any one or more of the features included herein, and that the features may be used in any particular combination or sub-combination. Modifications and substitutions by those skilled in the art are considered to be within the scope of the present disclosure, which should not be limited except as by the claims. [Aspect 1] An electric motor, a first housing portion defining a first rotor receptacle for receiving and coupling to a first end of a rotor assembly; a second housing portion defining a second rotor receptacle for receiving and coupling to a second end of the rotor assembly, the first and second housing portions being configured to couple together and collectively provide a rotor bore for receiving the rotor assembly; a rotor assembly disposed within the rotor bore, the rotor assembly comprising a shaft and at least a first bearing concentrically coupled along the shaft, the first bearing being disposed within the first rotor receptacle of the first housing portion or within the second rotor receptacle of the second housing portion, and the shaft and the first bearing being radially aligned with each other based on the rotor bore collectively provided by the first and second housing portions having an end-to-end offset deviation of less than 10 microns. [Aspect 2] Each of the first and second housing portions is coupled to each other based on first and second interlocking portions, the first and second interlocking portions having an offset alignment tolerance of at least 50 microns, whereby the first and second housing portions are slidably coupled together and enable a radial displacement of at least 50 microns relative to each other, the electric motor according to Aspect 1. [Aspect 3] The rotor bore is based on the first and second housing portions coupled together and radially displaced by the offset alignment tolerance of the first and second interlocking portions, and includes an end-to-end offset deviation of less than 10 microns, the electric motor according to Aspect 2. [Aspect 4] The electric motor according to aspect 1, wherein the first and second housing parts are connected to each other using an adhesive. [Aspect 5] The electric motor according to aspect 1, wherein the first and second housing parts are connected to each other based on a locking device. [Aspect 6] The electric motor according to aspect 5, wherein the locking device comprises a self-tapping screw. [Aspect 7] The electric motor according to aspect 5, wherein the locking device comprises a metal bolt. [Aspect 8] The electric motor according to aspect 1, further comprising a stator assembly disposed between the first housing part and the second housing part and defining at least a part of the rotor bore. [Aspect 9] The electric motor according to aspect 1, further comprising a third housing part configured to be connected to the second housing part, the third housing part defining an opening for communicating air into the electric motor. [Aspect 10] The electric motor according to aspect 9, wherein the third housing part includes at least one pressure regulating valve in fluid communication with an impeller windage chamber at least partially defined by the third housing part. [Aspect 11] The electric motor according to aspect 10, further comprising a first sealing device disposed adjacent to the opening to form an airtight seal with a surface of an impeller disposed within the impeller windage chamber. [Aspect 12] The electric motor according to aspect 11, wherein the first sealing device includes at least one annular protrusion, and the third housing part defines at least one groove for receiving the at least one annular protrusion to form the airtight seal. [Aspect 13] The electric motor according to aspect 11, wherein the first sealing device is formed from a material including foam, polytetrafluoroethylene, rubber, and / or nylon. [Aspect 14] A rotor bore alignment device for the radial alignment of a bore collectively provided by a plurality of housing parts of an electric motor, comprising a shaft having at least one extendable member disposed at a predefined location along the shaft, the at least one extendable member being selectively movable from a retracted position to an extended position, the retracted position radially extending the at least one extendable member from the shaft by a first distance D1, and the extended position radially extending the at least one extendable member from the shaft by a second distance D2, the second distance D2 being greater than the first distance D1, the shaft being configured to be slidably coupled into the bore at a predefined position, the predefined position aligning the at least one extendable member with at least a first motor component of the electric motor, whereby the transition of the at least one extendable member to the extended position causes a radial alignment of the first motor component and a second motor component of the electric motor. A rotor bore alignment device. [Aspect 15] The at least one extendable member is a plurality of extendable members, and the bore is collectively defined by at least first and second housing parts of the plurality of housing parts and a stator assembly disposed therebetween, and the predefined position is configured to align and engage a first, a second, and a third extendable member of the plurality of extendable members with the first housing part, the stator assembly, and the second housing part, respectively, whereby the transition of the plurality of extendable members to the extended position causes a radial alignment of the bore collectively provided by the first housing part, the stator assembly, and the second housing part. The rotor bore alignment device according to Aspect 14. [Aspect 16] The rotor bore alignment device according to aspect 15, wherein the bore has an end-to-end offset deviation of less than 10 microns. [Aspect 17] The rotor bore alignment device according to aspect 14, further comprising a flange disposed at an end of the shaft, the flange extending substantially transversely to the longitudinal axis of the shaft, and the flange being configured to engage a side wall of the first or second housing portion and to prevent further insertion of the shaft into the bore, the flange being configured to engage the side wall when the shaft is slidably inserted into the predefined position within the bore. [Aspect 18] The rotor bore alignment device according to aspect 14, wherein the at least one extendable member comprises an annular ring, the annular ring being configured to extend radially outward from the shaft so as to increase the diameter and in response to the at least one extendable member transitioning to the extended positioning. [Aspect 19] The rotor bore alignment device according to aspect 14, wherein the rotor bore alignment device is configured to introduce a clamping force, the clamping force extending substantially parallel to the bore and displacing the plurality of housing portions towards each other and preventing angular and axial shifts of the plurality of housing portions relative to each other. [Aspect 20] The rotor bore alignment device according to aspect 14, further comprising a sleeve disposed on the shaft and slidably engaging and disengaging the at least one extendable member, the sleeve defining at least one V-groove so as to selectively displace the at least one extendable member based on linear movement of the sleeve. [Aspect 21] The rotor bore alignment device according to aspect 20, further comprising a bolt threaded into a cavity of the shaft, the threaded bolt rotating and displacing the sleeve. [Aspect 22] The rotor bore alignment device according to aspect 20, wherein the sleeve is configured to displace the at least one extendable member away from the shaft and to shift the extendable member to an extended position. [Aspect 23] The rotor bore alignment device according to aspect 20, wherein the sleeve is configured to be separated from the at least one extendable member and to enable the at least one extendable member to shift to the retracted position. [Aspect 24] The rotor bore alignment device according to aspect 14, wherein the at least one extendable member includes a material having elasticity that enables the at least one extendable member to increase in diameter and extend to the second distance D2 when shifted to the extended position, and to retract back to the first distance D1 when shifted to and returning from the retracted position. [Aspect 25] The rotor bore alignment device according to aspect 14, wherein the at least one extendable member includes nitrile butadiene rubber (NBR), carboxylated nitrile butadiene rubber (XNBR), and / or fluoroelastomer. [Aspect 26] A diffuser for use with an electric motor, comprising: a cylindrical body defining an opening through which a shaft of a rotor assembly can extend; a plurality of curved exhaust fins extending radially from the cylindrical body. [Aspect 27] The diffuser according to aspect 26, further comprising a rim connected to the cylindrical body by the plurality of curved exhaust fins. [Aspect 28] The diffuser according to aspect 27, wherein each of the plurality of curved exhaust fins includes a distal end on the opposite side of the cylindrical body that connects the rim to the cylindrical body. [Aspect 29] The diffuser according to aspect 26, wherein each of the plurality of curved exhaust fins includes a distal end on the opposite side of the cylindrical body that is exposed to air. [Aspect 30] The diffuser according to aspect 26, wherein each of the plurality of curved exhaust fins includes a distal end on the opposite side of the cylindrical body that is completely exposed to air.

Claims

1. 1. A rotor bore alignment apparatus for radial alignment of bores collectively provided by a plurality of housing portions of an electric motor, comprising: a shaft having at least one extendable member disposed at a predefined location along the shaft, the at least one extendable member selectively transitioning from a retracted position to an extended position, the retracted position radially extending the at least one extendable member a first distance D1 from the shaft, and the extended position radially extending the at least one extendable member a second distance D2 from the shaft, the second distance D2 being greater than the first distance D1; the shaft is configured to be slidably coupled into the bore to a predefined position, the predefined position aligning the at least one extendable member with at least a first motor component of the electric motor, whereby transition of the at least one extendable member to the extended position causes radial alignment of the first motor component with a second motor component of the electric motor.

2. 2. The rotor bore alignment device of claim 1, wherein the at least one extendable member is a plurality of extendable members, and the bore is collectively defined by at least a first and a second of the plurality of housing portions and a stator assembly disposed therebetween, and the predefined position is configured to align and engage a first, second and third of the plurality of extendable members with the first housing portion, the stator assembly and the second housing portion, respectively, whereby transition of the plurality of extendable members to the extended position causes radial alignment of the bore collectively provided by the first housing portion, the stator assembly and the second housing portion.

3. 3. The rotor bore alignment system of claim 2, wherein said bore has an end-to-end offset deviation of less than 10 microns.

4. 2. The rotor bore alignment device of claim 1, further comprising a flange disposed on an end of the shaft, the flange extending substantially transverse to a longitudinal axis of the shaft, and the flange configured to engage a sidewall of the first or second housing portion and to prevent further insertion of the shaft into the bore, the flange configured to engage the sidewall when the shaft is slidably inserted into the bore to the predefined position.

5. 2. The rotor bore alignment device of claim 1, wherein the at least one extendable member comprises an annular ring configured to increase in diameter and extend radially outward from the shaft in response to the at least one extendable member transitioning to the extended position.

6. 2. The rotor bore alignment device of claim 1, wherein the rotor bore alignment device is configured to introduce a clamping force that extends substantially parallel to the bore and displaces the housing portions toward one another and prevents angular and axial shift of the housing portions relative to one another.

7. 2. The rotor bore alignment device of claim 1, further comprising a sleeve disposed on said shaft for slidably engaging and disengaging said at least one extendable member, said sleeve defining at least one V-groove for selectively displacing said at least one extendable member based on linear movement of said sleeve.

8. 8. The rotor bore alignment device of claim 7, further comprising a bolt threaded within a cavity of said shaft, said threaded bolt rotating and displacing said sleeve.

9. The rotor bore alignment device of claim 7 , wherein the sleeve is configured to displace the at least one extendable member away from the shaft and to transition the extendable member to an extended position.

10. The rotor bore alignment device of claim 7 , wherein the sleeve is configured to be pulled away from the at least one extendable member to allow the at least one extendable member to transition to the retracted position.

11. 2. The rotor bore alignment device of claim 1, wherein the at least one extendable member comprises a resilient material that allows the at least one extendable member to increase in diameter to extend to the second distance D2 when transitioned to the extended position and to retract back to the first distance D1 when transitioned back to the retracted position.

12. The rotor bore alignment device of claim 1 , wherein the at least one extendable member comprises nitrile butadiene rubber (NBR), carboxylated nitrile butadiene rubber (XNBR), and / or a fluoroelastomer.

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