Counterweighted rotor

Abstract

An electric motor is adapted for driving an eccentric-motion device that employs eccentric motion about a device axis. The motor includes a stator unit and a rotor unit operatively coupled to the stator unit. The rotor unit has a rotor shaft rotatable about a rotor axis relative to the stator unit. The shaft is connectable to the eccentric-motion device so as to drive the eccentric motion thereof. The rotor unit includes a counterweight assembly that is rotatably connectable to the shaft and configured to rotate in unison therewith about the rotor axis. The counterweight assembly has a mass and a center of mass that is offset from the rotor axis at an offset distance in a radial direction that intersects the rotor axis perpendicularly, wherein at least the mass of the counterweight assembly is selected to counterbalance the eccentric-motion device.

Description

COUNTERWEIGHTED ROTORCROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 649,409, titled ELECTRIC MOTORS, AND RELATED SYSTEMS AND METHODS, filed May 19, 2024, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates to electric motors, and more particularly to integration of electric motors with eccentric-motion devices.BACKGROUND

[0003] Electric motors (e.g., brushless DC motors) are integrated with various devices to drive components thereof, including but not limited to eccentric-motion devices that employ eccentric movement about an axis. Air compressors and scroll pumps are examples of such eccentric-motion devices, though there are many others, such as crankshafts in piston engines and eccentric shafts in Wankel engines, for example. Eccentric-motion devices typically employ counterweights to counterbalance the eccentric motion to optimize performance and prolong the device lifespan.SUMMARY

[0004] According to an embodiment of the present disclosure, an electric motor is adapted for driving an eccentric-motion device that employs eccentric motion about a device axis. The motor includes a stator unit, and a rotor unit operatively coupled to the stator unit. The rotor unit has a rotor shaft rotatable about a rotor axis relative to the stator unit. The shaft is connectable to the eccentric-motion device so as to drive the eccentric motion thereof. The rotor unit includes a counterweight assembly that is rotatably connectable to the shaft and configured to rotate in unison therewith about the rotor axis. The counterweight assembly has a mass and a center of mass that is offset from the rotor axis at an offset distance in a radial direction that intersects the rotor axis perpendicularly, wherein at least the mass of the counterweight assembly is selected to counterbalance the eccentric-motion device.

[0005] According to another embodiment of the present disclosure, a motor-balanced, eccentric-motion device includes at least one eccentric member and an electric motoroperatively coupled to the at least one eccentric member. The at least one eccentric member is configured to move eccentrically about a device axis. The electric motor has a rotor unit electromagnetically driven by a stator unit. The rotor unit includes a rotor shaft that is rotatable about a rotor axis relative to the stator unit. The rotor shaft is coupled to the at least one eccentric member, such that rotation of the rotor shaft about the shaft axis moves the at least one eccentric member eccentrically about the device axis. The rotor unit includes a counterweight mount disposed on the rotor shaft, and also includes a weight disposed on the counterweight mount, such that the counterweight mount and the weight define a joint mass and a joint center of gravity that are configured to counterbalance the at least one eccentric member.

[0006] According to an additional embodiment of the present disclosure, a method of counterbalancing an eccentric-motion device includes attaching a weight to a mounting formation carried on a rotor shaft of an electric motor. The rotor shaft is configured to operatively couple to an eccentric member of the device and rotationally drive the eccentric member configured eccentrically about an axis of the device. The step of attaching the weight to the mounting formation substantially counterbalances the eccentric-motion device.

[0007] According to yet another embodiment of the present disclosure, an eccentric-motion fluidic device has an integrated electric motor and includes at least one eccentric member configured to move eccentrically about a device axis in contact with a second member. The device includes a cooling chamber adjacent to one or more of the at least one eccentric member and the second member. The cooling chamber is defined by one or more members of the eccentric-motion fluidic device. The one or more members also define an opening into the cooling chamber. The device includes a motor housing that at least partially houses the electric motor and also includes electronic circuitry for controlling operation of the electric motor. The electronic circuitry is in contact with at least one exterior surface of the motor housing. At least some of the electronic circuitry extends outwardly from the at least one exterior surface. The device includes an air duct member defining a fluidic channel that extends from an intake end of the air duct member to an outlet end of the air duct member. The outlet end is configured to discharge air through the opening and into the cooling chamber. The fluidic channel intersects the at least some of the electronic circuitry that extends outwardly from the at least one exterior surface. The device includes an air inductor configured to drive air along the fluidic channel and into the cooling chamber.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing summary, as well as the following detailed description of illustrativeembodiments of the present application, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the features of the present application, there is shown in the drawings illustrative embodiments. It should be understood, however, that the application is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0009] FIG. 1A is a perspective view of a motor-balanced system that includes a motor integrated with an eccentric-motion device, according to an embodiment of the present disclosure;

[0010] FIG. 1B is a partially exploded perspective view of the motor-balanced system illustrated in FIG. 1A, particularly showing the motor separated from the eccentric-motion device;

[0011] FIGS. 1 C-1 D are a partially exploded perspective views of a rotor unit of the motor and an exemplary eccentric motion assembly of the device, according to an embodiment of the present disclosure;

[0012] FIG. 2A is an exploded perspective view of the rotor unit illustrated in FIGS. 1C-1 D;

[0013] FIG. 2B is a perspective view of the rotor unit illustrated in FIGS. 1C-1 D;

[0014] FIGS. 3A-3B are exploded perspective views of a counterweight assembly of the rotor unit illustrated in FIGS. 2A and 2B;

[0015] FIG. 4 is a perspective view of a counterweight kit for use with the rotor unit;

[0016] FIG. 5A is a perspective sectional view of the motor-balanced system illustrated inFIG. 1A, showing an air control system for cooling features of the system; and

[0017] FIG. 5B is a perspective view of the motor-balanced system illustrated in FIG. 5A, with respective structures of the air control system removed for visualization purposes.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0018] The present disclosure can be understood more readily by reference to the following detailed description taken in connection with the accompanying figures and examples, which form a part of this disclosure. It is to be understood that this disclosure is not limited to the specific devices, methods, applications, conditions or parameters described and / or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the scope of the present disclosure. Also, as used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numericalvalue includes at least that particular value, unless the context clearly dictates otherwise.

[0019] The term “plurality”, as used herein, means more than one. When a range of values is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. All ranges are inclusive and combinable.

[0020] The terms “approximately”, “about”, and “substantially”, as used herein with respect to dimensions, angles, ratios, and other geometries, takes into account manufacturing tolerances. Further, the terms “approximately”, “about”, and “substantially” can include 10% greater than or less than the stated dimension, ratio, or angle. Further, the terms “approximately”, “about”, and “substantially” can equally apply to the specific value stated. It should be understood that, although terms involving numerical prepositions (e.g., “first,” “second,” “third,” etc.) are used herein with reference to various features, such features should not be limited by these terms. These terms are instead used to distinguish one feature from another. For example, a “first” element could be termed a “second” element in another context, and, similarly, a “second” element could be termed a “first” element in another context, without departing from the scope of the embodiments disclosed herein.

[0021] The use of “couple”, “coupled”, or similar phrases should not be construed as being limited to a certain number of components or a particular order of components unless the context clearly dictates otherwise.

[0022] Electric motors typically have a stator and a rotor. In various aspects, the rotor can be utilized to provide a counterbalance to eccentric motion. For example, the embodiments disclosed herein pertain to electric motors (such as brushless DC motors) integrated with eccentric-motion devices. In one aspect, an electric motor is configured to provide counterbalancing to the eccentrically movable component(s) of an eccentric-motion device 2. In such embodiments, the electric motor comprises a counterweight assembly that is attenuated to counterbalance the eccentric motion in the device 2. In another aspect, the electric motor is adapted with an air control system for directing air along respective features of the motor, such as electrical components, for cooling purposes, and for subsequently channeling the air into a cooling chamber of an eccentric-motion device.

[0023] In various aspects, the center of mass of the rotor can be selectively and purposefully offset from its axis of rotation to complement the offset and eccentric motion of an eccentric-motion device. For example, the offset of the center of mass of the rotor can be customized and tuned to the counterweight of the eccentric-motion device. The rotor canincorporate a counterweight assembly, for example, which can supplement or aid the rotor to collectively offset or counter the eccentricity of the eccentric-motion device.

[0024] Referring to FIGS. 1A-1C, an exemplary motor-balanced system 100 includes an eccentric-motion device 2 and an electric motor 4 configured to drive eccentric motion of the eccentric-motion device 2. The electric motor 4 is also particularly adapted to counterbalance the eccentric load of the eccentric-motion device 2. The electric motor 4 includes a counterweight assembly 6 (see, e.g., FIG. 2) to facilitate balancing of the eccentric load, as described in more detail below. The system 100 also preferably includes a cooling assembly 7, which will also be described in more detail below. As used herein, the term “eccentric motion” means a cyclical motion that occurs about a reference axis by which a center of mass of the moving part(s) is cyclically offset from the reference axis along a radial direction R that extends perpendicularly from the reference axis. Eccentric motion, as referred to herein, can apply to pure rotational motion about the reference axis (such as by a flywheel, camshaft, eccentric shaft, and the like), translational motion about the reference axis (such as by a disc in an eccentric disc pump, a scroll plate in an air compressor, and the like), and a combination of rotational and translational motion about the reference axis (such as by an eccentric sheave).

[0025] In the illustrated embodiments herein, the eccentric-motion device 2 is an air compressor, particularly a scroll-pump compressor having a scroll plate assembly 8 (FIG. 1C) that translates cyclically about a device axis X1 relative to a complementary stationary scroll plate. In these embodiments, the device axis X1 is the reference axis about which the eccentric motion is defined, and the eccentric motion is performed by the scroll plate assembly 8. It should be appreciated, however, that the disclosed system 100 can be adapted for use with various other types of eccentric-motion devices 2, such as vibratory finishers, oil pumps, electric shavers, paint shakers, crankshafts in piston engines, and eccentric shafts in Wankel engines by way of non-limiting examples.

[0026] As shown in FIG. 1 B, the motor 4 and the eccentric-motion device 2 are generally spaced from each other along a first or “axial” direction X, which in the illustrated embodiment is parallel with the device axis X1 and is thus also perpendicular to the radial direction R. For purposes of discussing the relative positions of components in the system 100, a distal direction D is oriented along the longitudinal direction L and extends from the motor 4 toward the scroll plate assembly 8, and a proximal direction P is opposite the distal direction D. It should be appreciated that the proximal and distal directions P, D are each mono-directional components of the axial direction X, which is bi-directional. It should be appreciated that, as used herein: the terms “axial”, “axially”, and derivatives thereof refer to the axial direction X; the terms “distal”,“distally”, and derivatives thereof refer to the distal direction D; the terms “proximal”, “proximally”, and derivatives thereof refer to the proximal direction P; and the term “radially” and derivatives thereof refer to the radial direction R.

[0027] The motor 4 of the illustrated embodiments herein is a brushless DC motor having a stator unit 10 (see FIG. 5A) and a rotor unit 12 operatively coupled to the stator unit 10. It should be appreciated, however, that the motor-balanced system 100 can employ other types of motors, such as universal motors, induction motors, switched reluctance motors, and brush DC motors, by way of non-limiting examples. As shown in FIG. 1C, the rotor unit 12 is rotated about a rotor axis X2 via electromagnetic interaction with the stator unit 10. In the illustrated examples herein, the rotor axis X2 is substantially coaxial with the device axis X1. In other embodiments, however, the motor-balance system 100 can be adapted to employ a rotor axis X2 that is spatially offset from the device axis X1. The rotor unit 12 includes a rotor shaft 14 that rotates about the rotor axis X2 and is configured to be connected to the eccentric-motion device 2 so as to drive the eccentric motion, particularly to drive the scroll plate assembly 8 about the device axis X1 .

[0028] Referring now to FIG. 1D, the coupling between the rotor shaft 14 and the scroll plate assembly 8 is shown. To drive the scroll plate assembly 8 in cyclical, translational movement about the device axis X1 (i.e., eccentric translation), a distal portion of the rotor shaft 14 has a coupling formation that couples with a complementary coupling structure of the scroll plate assembly 8. As shown, the coupling formation of the rotor shaft 14 can include a distal pin member 16, which can also be referred to as a “rotor transmission pin” 16. The complementary coupling structure of the scroll plate assembly 8 can include a sleeve transmission member 18 (or “transmission sleeve” 18) extending proximally from a rear plate surface 20 of the scroll plate assembly 8. For illustrative purposes, the rotor transmission pin 16 is shown engaged with the sleeve transmission member 18, while the remainder of the rotor unit 12 is shown exploded proximally therefrom. The rotor transmission pin 16 has an exterior pin surface 16a that is configured to rotatably contact an interior sleeve surface 18a of the transmission sleeve 18 in a manner that drives the eccentric translation of the scroll plate assembly 8. In particular in the illustrated embodiment, the rotor transmission pin 16 is positioned eccentrically about the rotor axis X2 while the interior sleeve surface 18a is concentric with the device axis X1 . In this manner, rolling contact between the exterior pin surface 16a and the interior sleeve surface 18a drives eccentric translation of the scroll plate assembly 8.

[0029] Referring now to FIGS. 2A-2B, the rotor unit 12 of the illustrated embodiment will be described in further detail. The rotor unit 12 includes a magnet assembly 22 having a pluralityof magnets 22a positioned around the rotor axis X2. A hub sleeve 24 is positioned concentrically within the magnet assembly 22 and defines an interior channel 24a that houses a rotor drive base or “shaft cap” 26. The shaft cap 26 defines a central bore 26a that is concentric with the rotor axis X2 and is configured to receive a stem 14a of the rotor shaft 14. The rotor shaft 14 includes an extension portion 14b that defines a shaft bore 14c having a central bore axis X3 that is radially offset from the rotor axis X2 and parallel with the rotor axis X2. The rotor transmission pin 16 has a pin stem 16b that is received within the shaft bore 14c, thereby positioning the rotor transmission pin 16 eccentrically with respect to the rotor axis X2.

[0030] As mentioned above, the rotor unit 12 is configured to counterbalance the eccentric load of the eccentric-motion device 2 (e.g., the eccentric load of the scroll plate assembly 8). The components of the rotor unit 12 described herein are particularly designed to provide a collective mass and center of gravity to counterbalance the eccentric load. Additionally, the rotor unit 12 includes the counterweight assembly 6 mentioned above, which is configured to allow for adjusting the collective mass (and the center of mass) of the rotor unit 12 to fine-tune the counterbalancing. The counterweight assembly 6, also shown in FIGS. 3A-3B, is rotatably connectable to the rotor shaft 14 and is configured to rotate in unison therewith about the rotor axis X2. The counterweight assembly 6 includes a base member 28 and at least one weight 30 mountable to the base member 28. The base member 28 and the at least one weight 30 have respective geometries that allow the at least one weight to be interchangeable with any of a plurality of weights having different masses. This interchangeable configuration of weights 30 allows for simplified adjustment of the collective mass of the rotor unit 12. The base member 28 has a first portion 28a configured for rotatably coupling with the rotor shaft 14. In particular, the first portion 28a defines a bore 28c that receives the pin stem 16b. The pin stem 16b extends through the bore 28c of the base member 28, such that the first portion 28a of the base member 28 is axially clasped between a proximal shoulder surface 16c of the rotor transmission pin 16 and a distal end surface 14d of the rotor shaft 14. The base member 28 is preferably configured to be rotationally fixed with the rotor shaft 14 (i.e., such that the base member 28 does not rotate relative to the rotor shaft 14. In the illustrated embodiment, the first portion 28a on a proximal side of the base member 28 defines a geometry that provides a keyed connection with the rotor shaft 14. For example, the first portion 28a can define a proximal rim 28f and a recessed surface 28g that is spaced distally from the rim 28f and has a complimentary geometry with the distal end surface 14d of the rotor shaft 14, such that the distal end surface 14d extends within the recess in keyed fashion.

[0031] The base member 28 includes a second portion 28b, also referred to herein as amounting formation 28b, that extends radially outward from the first portion 28a and is configured for the weight 30 to be mounted thereto. The base member 28 preferably defines a profile, as viewed in a reference plane orthogonal to the rotor axis X2, that is symmetrical about a radial axis R1 that intersects the rotor axis X2. In this manner, the base member 28 defines a center of mass that is located on the radial axis R1. The mounting formation 28b defines a mounting surface 28d, which can be substantially planar, as shown. The mounting surface 28d also preferably defines a profile that is symmetrical about the radial axis R1 . For example, the mounting surface 28d can have a semicircular profile that is symmetrical with respect to the radial axis R1 . The mounting formation 28b also defines one or more coupling structures for affixing the weight 30 to the mounting surface 28d. The one or more coupling structures can include two (2) or more mounting bores 29 extending from the mounting surface 28d toward an opposed second surface 28e of the mounting formation. As shown, the mounting bores 29 can consist of two (2) mounting bores 29 symmetrically located on opposite sides of the radial axis R1 . The mounting bores 29 are spaced from each other at a mounting bore spacing distance S1.

[0032] The weight 30 has a first surface 30a and an opposed second surface 30b that faces the mounting surface 28d and is preferably configured to mate therewith. The weight 30 defines a profile in the orthogonal reference plane that is preferably symmetrical with respect to a respective radial axis R2 that intersects the rotor axis X2. For example, the profile of the weight 30 can be arcuate, such as an arc segment having a radial thickness T 1 and extending along an angular arc-length A1 of about 180-degrees. The weight 30 defines one or more coupling structures for affixing the weight 30 to the mounting surface 28d. The one or more coupling structures can include two (2) or more weight bores 31 extending from the first surface 30a to the second surface 30b of the weight 30. As shown, the weight bores 31 can consist of two (2) bores 31 symmetrically located on opposite sides of the radial axis R2. The weight bores 31 are spaced from each other at a weight bore spacing distance S2 that is preferably equivalent to the mounting bore spacing distance S1 . The counterweight assembly 6 comprises two or more fasteners 32, such as bolts, configured to extend through the respective weight bores 31 and mounting bores 29 for affixing the weight 30 to the mounting surface 28d. The fasteners can be flat-head bolts 32 that extend proximally through the bores 31, 29 and are secured by respective nuts that rotationally abut the second surface 28e of the base member 28. It should be appreciated that other fastener types can be employed for affixing the weight 30 to the mounting formation 28b of the base member 28.

[0033] The counterweight assembly 6 has a mass, which in the illustrated embodiment is asum of the masses of the base member 28, the weight 30, and the fasteners / nuts. The counterweight assembly 6 also defines a center of mass CM, which is offset from the rotor axis X2 at an offset distance in the radial direction R. The center of mass CM is also located at a particular position in the axial direction X. In the illustrated embodiment, the center of mass CM is located on a reference plane RP coextensive with the radial axes R1 , R2 of the base member 28 and the weight 30, as shown in FIG. 3A. As mentioned above, the collective mass and the collective center of the mass of the rotor unit 12 can be adjusted by changing out the weight 30 with a different weight having a different mass and a different center of mass. It should be appreciated that interchanging one weight 30 with another weight 30 having a different mass and a different center of mass can also provide minor changes to the collective center of mass of the rotor unit 12.

[0034] The counterweight assembly 6 disclosed herein is configured for precisely counterbalancing the eccentric-motion device 2. The counterbalancing can be performed by selective application of the at least one weight 30 in the counterweight assembly 6. For example, the system 100 can include a counterweight kit 130, as shown in FIG. 4, that comprises a plurality of weights 30 having different, incremental masses that can be selectively employed for coupling with the base member 28 to counterbalance the eccentric-motion device 2. Preferably, the plurality of weights 30 are configured so as to specify a different collective center of mass CM of the rotor unit 12 based on the weight 30 selected. A technician can employ the counterweight kit 130 to select the weight 30 for attaching to the base member 28 to precisely counterbalance the specific eccentric-motion device 2 integrated with the electric motor 2. The specified collective center of mass of the rotor unit 12 can be selected to oppose or counteract the offset center of mass of the eccentric-motion device 2. The weights 30 can be comprised of metal, such as steel, lead, tungsten, and combinations thereof, for example.

[0035] FIGS. 2A-3B depict interchangeable weights 30 for a counterweight assembly 6 to provide a selective counterbalance for the eccentric-motion device 2 integrated with the electric motor 4. The counterweight assembly 6 and the weight 30 thereof can be replaceable or non- destructively removeable from the rotor shaft 14. In other aspects of the present disclosure, the counterweight assembly and / or a portion thereof can be integrally formed or permanently affixed to the rotor unit 12 and / or the rotor shaft 14 thereof. For example, one or more portions of the rotor shaft 14 can be removed, such as by machining (e.g. milling) to provide an integral counterbalance and adjust the center of mass of the rotor unit 12. As another example, one or more portions can be added to the rotor unit 12 and / or the rotor shaft 14 thereof, such as by adding metallic tape (e.g. lead tape) and / or by welding an asymmetrical weight to the rotor unit12 and / or the rotor shaft 14. In instances in which material is attached and / or removed from the rotor assembly 12 and / or the rotor shaft 14, the rotor assembly 12 and / or the rotor shaft 14 can be axially asymmetric relative to the rotor axis X2, which can correspond to the center of mass of the rotor shaft 14 being shifted axially away from the rotor axis X2 by an offset distance.

[0036] An example method for counterbalancing an eccentric-motion device 2 can include attaching a weight 30 to the mounting formation 28b of the base member 28. Prior to the attaching step, the weight can be selected from a plurality of weights each having a different mass. After the weight 30 is attached to the base member 28, the rotor unit 12 can be tested to observe whether it can be expected to counterbalance the eccentric-motion device 2. One example manner in which the rotor unit 12 can be tested is to couple the motor 4 with a test device that emulates the eccentric mass that will be turned by the motor 4. Such a test device includes a purposefully out-of-balance arbor and / or a bob weight. During testing, the motor 4 is run to drive the device and the technician observes the extent of vibrations produced by the motor 4 and test device. If the motor 4 performs satisfactorily in the test phase, the motor 4 can be coupled to the eccentric-motion device 2 and run to observe whether the device 2 is satisfactorily counterbalanced. To couple the motor 4 to the device 2 of the illustrated embodiments, the rotor shaft 14 can be operatively coupled to the scroll plate assembly 8, such as by placing the rotor transmission pin 16 into position within the sleeve transmission member 18 of the scroll plate assembly 8, as discussed above with reference to FIG. 1 D.

[0037] It should be appreciated that the motor 4 can be determined to have satisfactorily counterbalanced the device 2 when a level of vibrations observed in the device 2, when driven by the motor 4, falls below a threshold level of vibrations. The vibrations can be measured with instrumentation, such as accelerometers and the like. For testing purposes, a technician can also make macroscopic observations of the vibrations, including via sound and tactile observations. In various aspects, a technician can select a weight 30 to oppose and counterbalance at least a portion of the eccentricity of the eccentric-motion device to reduce vibrational acceleration to less than about 7.1 m / s2. In various aspects, the vibrational acceleration can be reduced to less than 10 m / s2, less than 8 m / s2, less than 5 m / s2, and / or less than 3 m / s2along one or more axes.

[0038] It should also be appreciated that selecting the weight 30 can be an iterative processes whereby, after attaching the weight 30 to the base member 28 and subsequently coupling the motor 4 to the eccentric-motion device 2 (or the test device), unsatisfactory results can lead to uncoupling the motor 4 and interchanging the weight 30 with a different weight 30, and the motor 4 can be re-tested. This process can be repeated until a weight 30 is employedthat produces satisfactory counterbalancing. Optionally, the method can include removing at least one designated counterweight from the eccentric-motion device 2 before operatively coupling the rotor shaft 14 to the device 2. In this manner, the motor 4 disclosed herein can be employed to replace the designated counterweights of the eccentric-motion device 2 and thereby reduce the total number of components in the system 100. Thus, the motor 4 can be employed to provide the entirety of counterbalancing for the eccentric member, such that the device 2 can be devoid of an additional dedicated counterweight for the eccentric member.

[0039] The cooling assembly 7 will now be described with reference to FIGS. 5A and 5B. The eccentric-motion device 2 defines a cooling chamber 50, which for a scroll compressor is located between the stationary scroll plate 52 and a distal wall 54 of the device 2. Many eccentric-motion devices, including the device 2 shown in the illustrated embodiments, employ a fan member 56, such as a “squirrel cage” fan, within the cooling chamber 50 in a manner such that driving the scroll plate assembly 8 also drives the fan member for cooling the scroll plates. However, operating the fan member 56 in this manner also loads the compressor. The cooling assembly 7 disclosed herein advantageously draws ambient air into a duct member 58 that defines a fluidic channel 66 and thereby directs the air over specific components of the motor that benefit from cooling, such as certain electrical components or circuitry in contact with an exterior surface of a housing 62 of the motor. One example of such electrical components includes leaded components of a circuit board 60. Furthermore, the cooling assembly 7 can further be configured to discharge the directed air into the cooling chamber 50 through an opening 55 defined by a housing 57 of the device 2.

[0040] As shown, the duct member 58 can be particularly configured to direct air over electrical components of the motor that are positioned on or in close proximity to a circuit board 60. These particular electrical components can be those that control operation of the motor 4. For example, the duct member 58 can define an intake end 64 adjacent to the circuit board 60. An air inductor 75, such as an electric fan, is disposed in the fluidic channel 66. An air filter 77 is also preferably disposed in the fluidic channel 68, preferably upstream of the electronic circuitry. As shown, the air filter 77 can be mounted at the intake end 64. The duct 58 can also define a first portion 58a that extends alongside the circuit board 60 so as to define a portion of the fluidic channel 66 that can house components of the circuitry. In the illustrated embodiment, the first duct portion 58a encompasses a bank of capacitors 68, e.g., electrolytic capacitors 68, that power the motor 4.

[0041] The first duct portion 58a is preferably constructed of a thermally conductive material to facilitate heat sinking behavior for the electronic circuitry. By way of a non-limiting example,the first duct portion 58a can be constructed of a 2-inch by 2-inch square tube of aluminum. Other thermally conductive materials, and tube sizes and configurations, are also within the scope of the present disclosure. In the illustrated embodiment, the first duct portion 58a has four opposed sidewalls 71 , 72, 73, 74 so as to define a rectangular fluidic channel 68 that is substantially enclosed. In this embodiment, the sidewall facing the circuit board 60 has a plurality of holes 78 formed therein, through which the capacitors extend into the fluidic channel 66. The capacitors / holes are preferably sealed at their interfaces so as to enhance the cooling aspect of the cooling assembly 7. In other embodiments, the first duct portion 58a need not be enclosed, but can instead have one or more open sides or openings extending along the fluidic channel 66. For example, the first duct portion 58a can have three sidewalls and an open side. In yet other embodiments, the first duct portion 58a can consist of a pair of opposed sidewalls.

[0042] As shown, the thermally conductive nature of the first duct portion material can be employed to heat sink electronic components that remain outside the fluidic channel 66. For example, a series of transistors, such as IGBTs, or MOSFETs, 70, can extend from the circuit board 60 and be in contact with a sidewall of the first duct portion 58a, which thereby performs heat sinking behavior for the IGBTs, or MOSFETs, 70. Additionally, input circuitry, such as 3- phase input 76, can extend from the circuit board 60 in contact with or close proximity to the first duct portion 58a. It should be appreciated that additional circuity components can be disposed alongside or adjacent to the first duct member 58a.

[0043] The cooling assembly 7 provides numerous benefits to a driven device, including the eccentric-motion device 2 described herein. One such benefit is that it directs filtered air into the cooling chamber 50. This is particularly helpful when the device 2 is used in dirty environments, such as is often the case when the device 2 is an air compressor, such as those used on buses, transportation devices, and / or other vehicles. Another benefit is that, because the cooling assembly 7 uses the air inductor 75 to direct air through the fluidic channel 68 and into the cooling chamber 7, the device 2 need not run the eccentric member (i.e. , to operate the fan member 56) in order to receive air in the cooling chamber 50.

[0044] Although the disclosure has been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments described in the specification. In particular, one or more of the features from the foregoing embodiments can be employed in other embodiments herein. As one of ordinary skill in the art will readily appreciate that processes, machines, manufacturing, composition of matter, means, methods, or steps,presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. An electric motor for driving an eccentric-motion device that employs eccentric motion about a device axis, the electric motor comprising: a stator unit; and a rotor unit operatively coupled to the stator unit, the rotor unit comprising: a rotor shaft rotatable about a rotor axis relative to the stator unit, wherein the rotor shaft is configured to be connected to the eccentric-motion device so as to drive the eccentric motion; and a counterweight assembly rotatably connectable to the rotor shaft and configured to rotate in unison with the rotor shaft about the rotor axis, the counterweight assembly having a mass value and a center of mass, wherein the center of mass is offset from the rotor axis at an offset distance in a radial direction that intersects the rotor axis and is perpendicular to the rotor axis, wherein at least the mass value of the counterweight assembly is selected to counterbalance the eccentric-motion device.

2. The electric motor of claim 1 , wherein the counterweight assembly comprises: a base member rotatably connectable to the rotor shaft, the base member defining a mounting formation that is offset from the rotor axis in the radial direction; and at least one weight connectable to the mounting formation, wherein the at least one weight and the base member collectively define the mass and the center of gravity.

3. The electric motor of claim 2, wherein the at least one weight is interchangeable with a plurality of weights having different respective mass values, such that the mass value of the counterweight assembly is adjustable by interchangeably connecting a respective one of the weights to the mounting formation.

4. The electric motor of claim 3, wherein the at least one weight and the plurality of weights are provided together in a kit.

5. The electric motor of claim 2, wherein the mounting formation defines a mounting surface that is substantially planar and has a substantially semicircular profile in a reference plane orthogonal to the rotor axis.

6. The electric motor of claim 5, wherein the substantially semicircular profile of the mounting surface is symmetrical with respect to a radial axis that intersects the rotor axis perpendicularly.

7. The electric motor of claim 6, wherein: the mounting formation defines two or more mounting bores extending from the mounting surface toward an opposed second surface of the mounting formation, the two or more mounting bores having a mounting bore spacing therebetween; the at least one weight defines two or more weight bores extending from a first surface of the weight to an opposed second surface of the weight, the two or more weight bores have a weight bore spacing therebetween that is substantially equivalent with the mounting bore spacing; and the counterweight assembly comprises two or more fasteners configured to extend through the two or more weight bores and the two or more mounting bores for coupling the at least one weight to the mounting formation.

8. A motor-balanced, eccentric-motion device, comprising: at least one eccentric member configured to move eccentrically about a device axis; an electric motor operatively coupled to the at least one eccentric member, the electric motor comprising a rotor unit electromagnetically driven by a stator unit, the rotor unit comprising: a rotor shaft rotatable about a rotor axis relative to the stator unit, wherein the rotor shaft is coupled to the at least one eccentric member, such that rotation of the rotor shaft about the rotor axis moves the at least one eccentric member eccentrically about the device axis; a counterweight mount disposed on the rotor shaft; and a weight disposed on the counterweight mount, such that the counterweight mount and the weight define a joint mass and a joint center of gravity that are configured to counterbalance the at least one eccentric member.

9. The motor-balanced, eccentric-motion device of claim 8, wherein the weight is interchangeable with a plurality of weights each having a different mass, such that the joint mass is adjustable by interchangeably connecting a different one of the plurality of weights to the counterweight mount.

10. The motor-balanced, eccentric-motion device of claim 9, wherein the motor-balanced, eccentric-motion device is devoid of an additional dedicated counterweight for the at least one eccentric member.11 . The motor-balanced, eccentric-motion device of claim 9, wherein the counterweight mount defines a mounting surface that is substantially planar, and each weight of the plurality of weights has a planar surface configured to mate with the mounting surface.

12. The motor-balanced, eccentric-motion device of claim 8, wherein the eccentric-motion device comprises an air compressor, and the at least one eccentric member comprises a scroll plate operatively coupled to the rotor shaft.

13. The motor-balanced, eccentric-motion device of Claim 8, further comprising: a cooling chamber adjacent to one or more of the at least one eccentric member; a motor housing that at least partially houses the electric motor; electronic circuitry for controlling operation of the electric motor, wherein the electronic circuitry is in contact with at least one exterior surface of the motor housing, and at least some of the electronic circuitry extends outwardly from the at least one exterior surface; an air duct member defining a fluidic channel extending from an intake end of the air duct member to an outlet end of the air duct member, wherein the outlet end is configured to discharge air through an opening and into the cooling chamber, and the fluidic channel intersects the at least some of the electronic circuitry that extends outwardly from the at least one exterior surface; and an air inductor configured to drive air along the fluidic channel and into the cooling chamber.

14. The motor-balanced, eccentric-motion device of Claim 13, wherein the air duct member defines opposed duct sidewalls that enclose the fluidic channel along at least two sides of the channel, wherein the air duct member defines a third duct sidewall that extends between the opposed duct sidewalls such that the fluidic channel is enclosed along at least three sides of the channel, wherein the air duct member defines a fourth duct sidewall opposite the third duct sidewall, wherein the fourth duct sidewall is adjacent to the at least one exterior surface, and wherein the at least one exterior surface is defined by a circuit board, the fourth duct sidewalldefines a plurality of holes, and the electric motor comprises a plurality of capacitors that extend outwardly from the circuit board and through the holes, respectively, and into the fluidic channel.

15. A method of counterbalancing an eccentric-motion device, the method comprising: attaching a weight to a mounting formation carried on a rotor shaft of an electric motor, wherein the rotor shaft is configured to operatively couple to an eccentric member of the device and rotationally drive the eccentric member configured eccentrically about an axis of the device, wherein attaching the weight to the mounting formation substantially counterbalances the eccentric-motion device.

16. The method of claim 15, further comprising, prior to the attaching step, selecting the weight from a plurality of weights each having a different mass.

17. The method of claim 15, further comprising operatively coupling the rotor shaft to the eccentric member after attaching the weight to the mounting formation.

18. The method of claim 15, further comprising removing at least one device counterweight from the eccentric-motion device before the attaching step.

19. The method of claim 15, further comprising detaching a first weight from the mounting formation prior to attaching the weight.

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