Patent Application
20070145836
The present invention is generally directed to motors having heat-sensitive electronic components mounted adjacent to heat-producing portions of the motor, and more particularly to motors having cooled winding leads for preventing damage to the components.
In some motors, it is necessary to mount heat-sensitive electronics inside or very close to the motor housing. Such heat-sensitive electronics can be damaged by heat produced inside the motor. Prior art insulation and cooling configurations, and even liquid cooling of the motor is inadequate for some motor applications. Accordingly, a better way of protecting the electronics from the heat of the windings is needed.
In one aspect, a motor comprises a stator including windings and leads extending from the windings. A rotor is in magnetic coupling relation with the stator and electronic components are electrically connected to the leads. An actively cooled shield separates the electronic components from the rotor and stator. The winding leads are thermally connected with the shield for transferring heat from the winding leads through the shield so that heat transferred from the winding leads to the electronic components is reduced.
In another aspect, a motor comprises a housing, and the stator and rotor are mounted within the housing. The shield includes holes receiving the winding leads, and a thermally conductive filler is disposed between the winding leads and the shield for transferring heat from the leads through the shield.
In yet another aspect, the motor additionally comprises potting material encasing at least a portion of the windings and a cooling system within the housing for cooling the motor. The shield includes tubes receiving the winding leads. The coolant of the cooling system is in direct contact with the shield so that a temperature of the shield is reduced by the cooling system. The potting material extends up through the tubes and around the winding leads.
Various refinements exist of the features noted in relation to the above-mentioned aspects of the present invention. Further features may also be incorporated in the above-mentioned aspects of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments of the present invention may be incorporated into any of the above-described aspects of the present invention, alone or in any combination.
Referring to
As best shown in
The motor 11 has a drive end (DE) and a non-drive end (NDE). The non-drive end of the motor 11 includes an endshield 25 (more generally, a shield) having a plurality (e.g. 6) of holes 27 (see
In this embodiment, winding leads 29 extend from the windings 21 through the holes 27 in the shield 25 and are electrically, mechanically and thermally connected to a busbar 31. Heat tends to be conducted through the winding leads 29. Electronic components 33 (e.g., capacitors and power components) are disposed on the other side of the endshield 25 from the rotor 17 and stator 15. The heat conducted by the winding leads 29 can damage the electronic components 33.
In this embodiment, the motor 11 includes a cooling system for cooling the motor. The system includes coolant ports 37 fluidly connected to a “cooling jacket” or coolant channels 39 in the motor 11. The coolant flows through a channel 39A in the endshield 25 and through the cooling jacket 39 in the motor housing 13. Thus, the endshield 25 and the cooling jacket 39 are fluidly connected. The direct coolant contact with the endshield 25 helps to cool the shield and thereby protect the electronic components 33 from heat damage. More generally, the cooling system 35 helps to maintain the electronic components 33 below a maximum acceptable temperature. In one embodiment, the maximum acceptable temperature is about 135° C. A variety of coolants may be suitable, including for example liquid coolant, gas refrigerants, or even high velocity air.
To further reduce damaging heat transferred from the heat-producing portions (e.g., the windings 21 and winding leads 29) through the endshield 25, a thermal connection between the winding leads and the shield is provided. Because the endshield 25 is actively cooled, e.g., in this embodiment, the endshield is thermally connected to the coolant, the winding leads 29 are cooled more effectively. Thus, less heat is conducted to the electronic components 33.
In this embodiment and as best shown in
In one embodiment, the endshield 25 is cast aluminum, and the potting material 23 is cast epoxy, though other materials and methods of manufacture are contemplated within the scope of the invention. As one exemplary method of forming the potting material 23, the windings 21 are placed around the teeth of the stator 15, and the stator is placed in a mold. The liquid potting material 23 is poured into the mold and allowed to set. It is formed to create the final shape of the potted assembly, including the posts.
As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. For example, the motor can have a variety of different rotor/stator constructions and a variety of different housings or even no housing separate from the stator. The motor need not include a cooling system, or even be actively cooled within the scope of this invention.
When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
