Patent Application
20140009015
Exemplary embodiments pertain to the art of electric machines and, more particularly, to an electric machine having a cooling system and method.
Electric machines produce work from electrical energy passing through a stator to induce an electro-motive force in a rotor. The electro-motive force creates a rotational force that causes the rotor to rotate or spin relative to the stator. The rotation of the rotor is used to power various external devices. Of course, electric machines can also be employed to produce electricity from an external work input. In either case, electric machines are currently producing greater torque output, are operated at higher speeds, and are being designed in smaller packages. The greater torque and higher speeds often result in harsh operating conditions such as high internal temperatures, vibration and the like on internal components of the electric machine. Accordingly, many conventional electric machines include coolant systems that are configured to lower internal temperatures to prolong an overall operational life of the internal components as well as improve electro-mechanical performance of the electric machine.
Disclosed is an electric machine including a housing having a body including an inner surface that defines an interior, a first end defining an opening exposing the interior, and a second end. A stator is fixedly mounted to the inner surface of the housing. The stator includes a first end and a second end. A rotor is supported within the interior. The rotor defines an axis of rotation. An end cover extends across the opening adjacent one of the first end and the second end of the stator. A cooling system is carried by the end cover. The cooling system includes a body having a cooling fluid plenum, a plurality of stator nozzles and a plurality of rotor nozzles. The stator nozzles are configured and disposed to direct multiple jets of a coolant toward the one of the first end and the second end of the stator and the plurality of rotor nozzles are configured and disposed to guide multiple jets of the coolant toward the rotor.
Also disclosed is a method of cooling an electric machine. The method includes delivering a cooling fluid into an end cover of the electric machine, passing the cooling fluid from the end cover into a cooling fluid plenum of a cooling system carried by the end cover, discharging a first portion of the cooling fluid through a plurality of stator nozzles toward a stator of the electric machine, and discharging another portion of the cooling fluid through a plurality of rotor nozzles toward a rotor of the electric machine.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
An electric machine in accordance with an exemplary embodiment is indicated generally at 2. Electric machine 2 includes a housing 4 having a body 6. Body 6 includes an inner surface 8 that defines an interior 10. Body 6 also includes a first end 14 that defines a first opening 15 and a second end 18 that defines a second opening 19. Electric machine 2 is shown to include a stator 24 mounted to inner surface 8. Stator 24 includes a stator core 28 provided with a plurality of stator windings 30. Windings 30 include a first or crown side 32 and a second or weld side 34. A rotor 40 is rotatably mounted within housing 4. Rotor includes a hub 42 mounted to a shaft 44. Shaft 44 is supported by bearings 45 and 46 and defines an axis of rotation 48 of rotor 40. Electric machine 2 is shown to include a first end cover 61 that extends across first opening 15 and a second end cover 64 that extends across second opening 19. First end cover 61 supports or carries a first cooling system 70 and second end cover 64 supports or carries a second cooling system 74.
Reference will now be made to
Cooling system 70 is configured to guide a cooling fluid (liquid or gas) from cooling fluid plenum 90 onto portions of stator 24 and rotor 40. The particular type of cooling fluid employed in connection with cooling system 70 may vary. Cooling system 70 includes a first plurality of stator nozzles 104, a second plurality of stator nozzles 106, and a plurality of rotor nozzles 108. First plurality of stator nozzles 104 are arranged in an annular array on third step surface 86. In accordance with one aspect of the exemplary embodiment, a portion of first plurality of stator nozzles 104 may be provided on fourth step surface 87. Second plurality of stator nozzles 106 and the plurality of rotor nozzles 108 are arranged in a generally annular array about second step surface 85.
First plurality of stator nozzles 104 guide jets of liquid coolant along axis 48 onto crown end 32 of stator 24. Second plurality of stator nozzles 106 guide jets of cooling fluid at an angle relative to axis 48 toward an inner surface (not separately labeled) of crown side 32. The plurality of rotor nozzles 108 guide jets of cooling fluid along or substantially parallel to axis 48 toward rotor 40. The jets of cooling fluid flow over stator 24 and rotor 40 to lower operating temperatures of both components. The cooling fluid collects within interior 10 and passes from housing 4 through a cooling fluid outlet 120. The cooling fluid may be passed through a heat exchanger (not shown) prior to re-introduction to housing 4, or may simply pass to a cooling fluid collection vessel (also not shown).
Reference will now be made to
Cooling system 74 is configured to guide a cooling fluid (liquid or gas) from internal cooling fluid plenum 140 onto portions of stator 24 and rotor 40. The particular type of cooling fluid employed in connection with cooling system 74 may vary. Cooling system 74 includes a first plurality of stator nozzles 154, a second plurality of stator nozzles 156, and a plurality of rotor nozzles 158. First plurality of stator nozzles 154 are arranged in a generally annular array on third step surface 136. In accordance with one aspect of the exemplary embodiment, a portion of the first plurality of stator nozzles 154 may be provided on fourth step surface 137. Second plurality of stator nozzles 156 and the plurality of rotor nozzles 158 are arranged in an annular array about second step surface 135.
First plurality of stator nozzles 154 guide jets of liquid coolant along axis 48 onto weld end 34 of stator 24. Second plurality of stator nozzles 156 guide jets of cooling fluid at an angle relative to axis 48 toward an inner surface (not separately labeled) of weld side 34. The plurality of rotor nozzles 158 guide jets of cooling fluid along or substantially parallel to axis 48 toward rotor 40. The jets of cooling fluid flow over stator 24 and rotor 40 to lower operating temperatures of both components. The cooling fluid collects within interior 10 and passes from housing 4 through a cooling fluid outlet 170. In a manner similar to that discussed above, the cooling fluid may be passed through a heat exchanger (not shown) prior to re-introduction to housing 4, or may simply pass to a cooling fluid collection vessel (also not shown). At this point it should be understood that cooling fluid outlet 120 and cooling fluid outlet 170 may lead to separate heat exchangers or may join and connect to a single heat exchanger.
At this point it should be understood that the exemplary embodiments provide a system for cooling internal components of an electric machine. The cooling systems in accordance with the exemplary embodiments include multiple nozzles that precisely deliver jets of cooling fluid onto components of the electric machine to reduce operating temperatures. The cooling systems are mounted to end covers of the electric machine and may be readily removed for service, repair or replacement. In addition, it should be understood that the electric machine need not be provided with both a plurality of stator nozzles that guide cooling fluid along an axis of the electric machine and a plurality of stator nozzles that guide cooling fluid at an angle to the axis. The particular degree of the angle may vary depending on the type and construction of the electric machine. Finally, it should be understood that the electric machine may only include a single cooling system positioned to guide cooling fluid onto one side or another of the stator. Also, it should be understood that the cooling system may include a single source or multiple sources of cooling fluid. Further, it should be understood that the cooling fluid may be a cooling liquid or, alternatively, a cooling gas.
While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.
