BACKGROUND

[0001] Integrated motor-drives are combinations of an electric motor and a drive unit that are integrated together and provided as a standalone unit. The electric motor may be an alternating current (AC) or direct current (DC) motor that converts an electrical power input to a motive force or torque typically transmitted through a rotating shaft. The drive unit can include electronics and electric circuitry to modify the electrical power input to produce a particular desired output of the motive force. For example, the drive unit may be capable of adjusting the electric current or the frequency of the electrical power input to change the torque or rotation speed of the motive force output. Motor-drives may be used in applications like fans, pumps, and the like to vary their operation to match the present requirements.

[0002] As stated, in an integrated motor-drive the electric motor and the drive unit are assembled together in an integrated combination. An advantage of integrated motor-drives is that they provide a compact arrangement of an electric motor and the components for adjustably controlling the motor and which can be sized to meet standardized settings and configurations such as, for example, the National Electrical Manufactures Association (“NEMA”) frame size designations. Another advantage of integrated motor-drives is that the integrated combination typically requires fewer external connections and cabling than if the components and their functionality were separated and distributed.

[0003] Electric motors generate heat during operation due to, for example, electrical resistance in conductors and windings, eddy currents induced by electromagnetic interaction of components, bearing friction and the like. Drive units also generate heat due to the operation of the electronic components such as transistors included in the drive units. To remove the thermal energy generated by the electric motor and the drive unit, the integrated motor-drive may include or be associated with a fan to direct cooling air with respect to the motor drive and transfer the thermal energy away by convection. The present disclosure is directed to a cooling arrangement and method for an integrate motor-drive configured to provided improved thermal management. BRIEF SUMMARY

[0004] The disclosure describes an integrated motor-drive including an electric motor, a drive unit, and a fan unit mounted together with the fan unit disposed between the electric motor and the drive unit. Airflow is drawn from the ambient environment into a drive chamber of the drive unit that accommodates a substrate with electrical components. An airflow aperture disposed in the substrate establishes fluid communication between the drive chamber and a fan chamber of the fan unit accommodating an impeller. A plurality of airflow outlets formed in a fan cover of the fan unit direct airflow from the fan chamber forwardly and externally over a motor enclosure of the electric motor.

[0005] A possible advantage of the disclosure is that airflow is directed though the drive unit thermally cooling the electrical components and the substrate therein. Another possible advantage is that the drive unit is separated and located away from the electric motor by the fan unit, impeding the heat transfer path from the electric motor. These and other possible advantages and features will be apparent from the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure l is a partial cutaway perspective view of an integrated motor-drive including an electric motor with a TEFC motor enclosure and a drive unit mounted to the rearward end of the electric motor with a fan unit disposed between the electric motor and the drive unit.

[0007] Figure 2 is a partial cutaway perspective view of another example of the motordrive including an electric motor and a drive unit mounted to the rearward end of the electric motor with an external fan disposed between the electric motor and the drive unit and representing an alternative airflow through the drive unit.

[0008] Figure 3 is an embodiment of a substrate of the drive unit mounted to a frustoconical heat sink with an airflow aperture disposed there through in accordance with an aspect of the disclosure.

DETAILED DESCRIPTION

[0009] Now referring to the drawings, wherein whenever possible like reference numbers refer to like elements, there is illustrated in FIG. 1 an integrated motor-drive 100 which includes an electric motor 102 with a drive unit 104 mounted thereto. As is known, the electric motor 102 can convert electrical energy to mechanical rotating power or torque that may be transmitted through a rotating motor shaft 106 to be harnessed for other work. The electrical motor 102 can be of any suitable construction and may utilize any suitable electromechanical operating principles such as, for example, an alternating current motor operating on single or polyphase power. Aspects of the disclosure are applicable to other types of electrical motors such as direct current stepper motors or servomotors. The drive unit 104 can modify the electrical power received by the electric motor 102 to achieve the desired output in terms of motor speed or torque. The electric motor 102 and the drive unit 104 are combined as an integrated package to reduce the overall footprint or volume of the motordrive 100 and to reduce power cabling and signal cabling between the electrical motor and its controls.

[0010] The electric motor 102 includes a motor enclosure 108, or a hollow housing to accommodate the internal motor components, that extends between forward end 110 and a rear end 112 that defines the axial length of the electric motor. The rod-like motor shaft 106 extends from the forward end 110 and defines a rotational axis 114 of the electric motor 102. In the illustrated example, to promote cooling by convective heat transfer, the motor enclosure 108 can include a plurality of external fins 116 that extend parallel to the rotational axis 114 and generally between the forward and rearward ends 110, 112 thereby increasing the external surface area of the motor enclosure. In the illustrated example, the motor enclosure 108 can be a totally enclosed metal casting, although as described below, the disclosure is applicable to any other suitable construction.

[0011] The motor enclosure 108 can be designed in accordance with various industry recognized standards for motor enclosures such as the Nation Electrical Manufacturers Association (NEMA) enclosure standards or the International Electrotechnical Commission (TEC) standards. These standards may define the type of enclosure for the electric motor 102 including the types of protection against ingress of dust or water, the type of cooling or heat removal such as air convection or fan cooled, and its suitability for different operating environments and hazards. For example, the electric motor 102 may be designed as an opened drip proof (ODP) motor that may include vents to the ambient environment or totally enclosed fan cooled (TEFC) motor that is enclosed to the environment to prevent dirt or water from entering and is cooled by an external fan. The standards may also relate to frame size or frame configuration of the motor enclosure 108 that can specify the configuration and dimensions for various mounting structures such mounting feet 118 at the base of the motor enclosure 108. The frame size may also specify the position and extension of the motor shaft 106 with respect to the mounting feet 118. Standardization of these aspects facilitates compatibility of the electrical motors 102 in different industrial settings.

[0012] The motor enclosure 108 accommodates the internal components of the electric motor 102. For example, to cause the motor shaft 106 of the electric motor 102 to rotate, a stator 120 and an electromagnetically interacting rotor 122 are accommodated in the enclosed space defined by the hollow motor enclosure 108. The stator 120 can be a stationary annular structure that is fixedly mounted to the motor enclosure 108 and concentric about the motor axis 114. In an AC induction motor, the stator 120 may be made of a plurality of windings or coils which are conductive and which can receive electricity from an external source. The rotor 122 can be formed on and radially disposed about the motor shaft 106 such that, in operation, the rotor assembly rotates with motor shaft. The rotor 122 can be made of a corresponding set of electromagnetically reactive coils, bars, or laminations. When alternating current is supplied to the coils of the stator 120, it generates a rotating magnetic field that induces a current to flow in the conductors of the rotor 122. The flow of current in the rotor 122 produces a secondary magnetic field that interacts with the rotating magnetic field or flux from the stator 120 causing the rotor to follow the primary field and generate rotary motion and torque. The elongated motor shaft 106 may be supported at the forward end 110 and rearward end 112 of the motor enclosure 108 by bearings 126 and can thus rotate with the rotor 122 under the electromagnetic interaction with the stator 120. However, other examples of an electric motor 102 may use different principles of operation.

[0013] To adjust operation of the electrical motor 102, the drive unit 104 can vary the electrical power received from the external source in accordance with the desired performance of the motor-drive 100. For example, the drive unit 104 can vary the current applied to the electric motor 102 which is proportional to the motor torque. To change the motor speed, the drive unit 104 can vary the electrical frequency of the A-C power source to speed up or slow down the electric motor 102. To vary the electrical power applied to the electric motor 102, the drive unit 104 can include a planar substrate 130 such as a printed circuit board to which are mounted various electrical components 132 such as transformers, capacitors, transistors and the like. The electrical components 132 can be electrically connected together through the substrate and can combine and cooperatively interact as an electrical circuit to control and regulate the electrical power from an external source and that is applied to the electric motor 102. To protect the electrical components 132, the substrate 130 and the components thereon can be disposed within a drive cowling 134 that defines an enclose space or drive chamber 136 for accommodating the substrate 130. The planar substrate 130 can be disposed in the drive chamber 136 such that it is normal to the rotational axis 114 of the electric motor 102, although other orientations are contemplated. The drive cowling 134 can be made from formed sheet metal, molded plastic, or the like and can include or operate with mounting features 138, for example, threaded fasteners, that enable the drive unit 104 to mount to the motor enclosure 108 of the electric motor 102. The drive unit 104 can be axially mounted to the rearward end 112 of the motor enclosure 108 and can be generally aligned with the rotational axis 114 of the electrical motor 102.

[0014] During operation, the electric motor 102 will generate thermal energy or heat due to the electromagnetic interaction between the stator 130 and rotor and possibly due to friction from the bearings 126. The drive unit 104 may also generate heat due to the electrical interaction of the electrical components 132. To remove heat and thermally cool the motordrive 100 by convective heat transfer, the motor-drive 100 can include a fan unit 140 that is operatively associated with the electric motor 102. The fan unit 140 can include an impeller 142 that is coupled or mounted to a portion of the elongated motor shaft 106 that extends through the rearward end 112 of the motor enclosure 108. The impeller 142 can be fixedly mounted to the motor shaft 106 by a central hub and can have a plurality of radially extending vanes or blades 146. The blades 146 can be angled or shaped so that when the motor shaft 106 rotates, the impeller 142 creates or imparts an airflow that may be in the axial direction generally parallel to the rotational axis 114 of the electrical motor 102. To prevent unintentional contact with the impeller 142 when rotating, the fan unit 140 can included a fan cover 148 that surrounds and encloses the impeller 142. For accommodating the fan unit 140, the fan cover 148 defines an enclosed space or fan chamber 149 similar to the drive chamber 136 defined by the drive cowling 134. The fan chamber 149 and the drive chamber 136 are physically separated by the substrate 130.

[0015] In the illustrated example, the fan unit 140 can be axially disposed between the electrical motor 102 and the drive unit 104 of the motor-drive 100. Hence, the fan unit 140 occupies the axial intermediate position of the primary components of the motor drive 100. The fan cover 148 can be disposed between the rearward end 112 of the motor enclosure 108 and the drive cowling 134. The fan cover 148 may have an external structure and dimensional shape similar to the drive cowling 134 and may be formed as an integral or joined structure of the drive cowling, although, in other designs of the drive unit 104, the drive cowling 134 and fan cover 148 can be formed or assembled differently.

[0016] Locating the fan unit 140 intermediately between the electric motor 102 and the drive unit 104 separates the electric motor and drive unit and impedes the thermal path between the two components. In other words, the fan unit 140, which may be the thermally coolest operating component of the drive unit 100, establishes a thermal barrier between the electric motor 102 and the drive unit 104 that are typically the thermally hotter operating components.

[0017] To enable the fan unit 140 to draw airflow from the ambient surroundings, the drive unit 104 can be configured to provide an airflow path to the impeller 142. For example, the drive cowling 134 can include a planar faceplate 150 that is normal to the rotational axis 114 of the electric motor 102 and which is located axially rearward of the substrate 130. The planar faceplate 150 can define a grate 152 with a plurality of vents 154 that are disposed through the planar faceplate and provide airflow communication between the drive chamber 136 and the external environment. The grate 152 can be circular in form and can aligned with the rotational axis 114 and the vents 154 can extend radially concentrically about the rotational axis 114. To connect the planar faceplate 150 to the rearward end 112 of the motor enclosure 108, the drive cowling 134 can include a peripheral cowling wall 156 which is disposed around or extends about the motor axis 114 and that defines in part the exterior shape of the motor drive 100.

[0018] To enable airflow to proceed from the drive chamber 136 to the fan chamber 149, which are separated by the substrate 130, the substrate can have disposed therein an airflow aperture 158. The airflow aperture 158 can be circular in shape, similar to the grate 152 and with a similar diameter. The airflow aperture 158 can also be axially aligned with and concentric to the rotational axis 114. The electrical components 132 of the drive unit 104 can mounted to the substrate 130 in a radially concentric pattern around the airflow aperture 158. The axially aligned grate 152 and airflow aperture 158 thus provide an airflow path from the ambient environment through the planar faceplate 150 into the drive chamber 136 and axially forward to the fan chamber 149 with the impeller 142 located therein. While the illustrated airflow aperture 158 in the substrate 130 is circular, other shapes and dimensions are contemplated by the disclosure.

[0019] As the airflow passes from the drive chamber 136 through the airflow aperture 158 axially forward into the fan chamber 149 where it is drawn by the impeller 142, that passing airflow can remove, by thermal convection, the heat generated by the electrical components on the substrate 130. To enable the airflow to continue in the axially forward direction from the fan chamber 149 onto the electric motor 100, the fan cover 148 may include a plurality of airflow outlets 160. The airflow outlets 160 may be disposed through the portion of the fan cover 148 that is axially proximate to rearward end 112 of the electric motor 100. Moreover, the airflow outlets 160 can be located at a radially outward distance with respect to the rotational axis 114 such that the airflow outlets 160 align with the external fins 116 of the motor enclosure 108. The airflow directed axially in to the fan chamber 149 by the impeller 142 can flow outwardly from the fan chamber 149 through the airflow outlets 160 and between the external fins 116 over the external surface of the motor enclosure 108 to remove the heat generated by the electromagnetic interaction between the stator 120 and the rotor 122 as well as the other sources of thermal heat associated with the electric motor 102.

[0020] The foregoing configuration provides an motor-drive 100 that includes TEFC motor in a compact configuration with the electric motor 102 and the drive unit 104 separated by the fan unit 140 to impede heat transfer between the components. The forgoing configuration also enable both external fan cooling of the TEFC electric motor 102 and internal cooling of the drive unit 104 by an airflow directed through the drive chamber 136. In a possible variation, the airflow outlets 160 disposed in the fan cover 148 can be configured to direct a portion of the airflow axially rearward and externally back over the peripheral cowling wall 156 of the drive cowling 134. The rearward directed airflow can further remove thermal energy from and cool the drive unit 104.

[0021] Referring to FIG. 2, there is illustrated another example of a motor drive 200 comprised of an electric motor 202 and a drive unit 204 mounted together as an integrated unit. The drive unit 204 is capable of modifying the electrical power received by the electric motor 202 from an external power source to achieve the desired output of the electric motor 202 in terms of torque or speed.

[0022] The electric motor 202 includes a rod-like rotating motor shaft 206 disposed within and extending through an elongated motor enclosure 208 having a forward end 210 and a rearward end 212 and which functions to accommodate the internal components like the stator and rotor. The motor shaft 206 defines the rotational axis 214 of the electric motor 202. In contrast to the example of FIG. 1, the motor enclosure 208 is cylindrical and has a smooth exterior in that it lacks external fins. The motor enclosure 208 may be designed in accordance with any recognized motor enclosure standards such as NEMA or IEC regarding construction, protection against environmental factors, and frame size. The motor enclosure 208 can be made from a suitable thermally convective material such as sheet metal.

[0023] The drive unit 204 can be axially mounted to the rearward end 212 of the electric motor 202. The drive unit 204 can include a planar substrate 230 populated with the electrical components 232 that interact as a circuit to control and regulate power to the electric motor 202. To protect the electrical components 232, the substrate 230 can be disposed in a protective drive cowling 234 that defines an enclosed space or drive chamber 236. The drive chamber 136 may be total enclosed by the drive cowling 234 to isolate the substrate 230 from the environment as illustrated. The drive cowling 234 may be of similar material and shape as the motor enclosure 208 and may function to mount the drive unit 204 to the electric motor 202.

[0024] To remove heat generated by the electric motor 202 and the drive unit 204 and thermally cool the motor-drive 200, a fan unit 240 can be included that is operatively associated with the electric motor. The fan unit 240 may include an impeller 242 having a plurality of blades that may be angled to impart movement to airflow. The impeller 242 can be accommodated in a fan chamber 249 defined by a fan cover 248. The fan unit 240 can be axially disposed between the rearward end 212 of the electric motor 202 and the drive unit 204.

[0025] To enable airflow from the ambient external environment to access the fan unit 204 disposed intermediately between the electric motor 202 and the drive unit 204, the drive cowling 234 may include an planar faceplate 250 with a grate 252 that is oriented normal to the rotational axis 214 of the electric motor 202 and at the axial rearward end of the drive unit 204. To join the planar faceplate to the rearward end 212 of the electric motor 202, the drive cowling 234 can include a peripheral cowling wall 256 disposed around the rotational axis 214 of the motor-drive 200.

[0026] To direct airflow entering the drive unit 204 from the ambient environment to the fan chamber 249, the drive cowling 234 includes a central airflow tube 257 that extends through the drive chamber 236. The airflow tube 257 establishes direct fluid communication between the grate 252 and the fan chamber 249 to deliver airflow to the impeller 242 and can be cylindrical and concentrically disposed about the rotational axis 214. The airflow tube 257 may align with the rotational axis 214 and is centrally disposed within the enclosed drive chamber 236 such that the enclosed space of the drive chamber forms a torus To pass through the substrate 230 accommodated in the drive chamber 236, the substrate has an airflow aperture 238 disposed there through. The airflow aperture 238 can be circular and of the same diameter as the airflow tube 257 so that the inner rim of the airflow aperture makes edge contact with the airflow tube, thereby supporting the planer substrate 130within the drive chamber 236.

[0027] Because the drive chamber 236 and the substrate 230 and the electrical components 232 thereon are not directly exposed to airflow, the drive cowling 234 may function as a heatsink. For example, the edge contact between the airflow aperture 258 and the airflow tube 257 may allow thermal energy to pass from the substrate 230 through the airflow tube to the airflow that is directed therein to the fan chamber 249. Fins can extend from the inner wall of the airflow tube 257 to provide additional heat transfer from the drive unit to the airflow passing through the airflow tube. In addition, the outer diameter of the planar substrate 230 can make edge contact with the inner surface of the peripheral cowling wall 256 to similarly transfer thermal energy from the substrate 230 to the ambient environment.

[0028] To enable the airflow directed therein to exit the fan chamber 249, the fan cover 248 can include one or more airflow outlets 258. The airflow outlets 258 can be arranged to direct the airflow axially forward and adjacently over the motor enclosure 208 to remove thermal energy from the electric motor 202 and provide thermal cooling. To provide additional cooling to the drive unit 204, the airflow outlets 258 can also be configured to direct a portion of the airflow axially rearward and externally back over the peripheral cowling wall 256 of the drive cowling 234 and remove heat via thermal convection. In the present example, thermal energy conducted by the substrate 230 can flow both radially inwards towards the airflow tube 257 and radially outwardly through the peripheral cowling wall 256.

[0029] Referring to FIG. 3, there is illustrated an example of a substrate-heatsink 300 that can be used in a motor-drive of the foregoing types having an electric motor and a rearwardly mounted drive unit with a fan unit disposed between them. In contrast to a planar substrate, the substrate-heatsink 300 is frustoconical in shape in that it has a larger diameter circular base 302 and a smaller diameter circular apex 304. A conical surface 306 tapers between the circular base 302 and the circular apex 304. The electrical components of the drive unit can be surface mounted to the conical surface 306 and electrical traces over the conical surface can complete establish electrical communication between the components to complete circuits.

[0030] The substrate-heatsink 300 may be generally solid. Because of its intended location, i.e. axially between the drive chamber and the fan chamber of the motor-drive, an airflow aperture 310 can be disposed between the circular base 302 and the circular apex 304. The airflow aperture 310 can establish fluid communication between the drive chamber and fan chamber delineating an airflow path between them. The illustrated airflow aperture 310 is circular in shape but may have any other suitable shape. A possible advantage of the frustoconical shaped substrate-heatsink 300 is that it provides a larger surface area via the conical surface 306 on which to mount the electrical components, which in turn provides for greater heat transfer of thermal energy between the drive unit and the airflow therein. In addition to a frustoconical shape, the substrate-heat sink may have other suitable shapes to drain heat from the electrical components mounted thereon.

[0031] The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.