Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-03-02
2001-10-09
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S058000, C310S059000, C310S064000, C310S089000
Reexamination Certificate
active
06300693
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to systems for cooling electric machines and, more particularly, to a cooling jacket assembly for cooling an electric motor and/or generator having high heat-dissipation requirements.
This invention has special (albeit not exclusive) application to electric machines (motors and generators) operating at high speeds, such as a brushless permanent magnet motor operating at speeds in excess of 50,000 rpm and driven by fuel-powered turbines to generate electrical power. These machines typically generate considerable heat and must be cooled by suitable means. One such means is by circulating a suitable cooling fluid through a cooling jacket in heat exchange contact with the stator of the machine. One example of such a system is described in U.S. Pat. No. 5,859,482.
Prior systems have suffered various drawbacks, including expense, difficulty in manufacture and assembly, and other disadvantages. There is a need, therefore, for a system which is economical to manufacture, easy to assemble, and capable of effective cooling.
SUMMARY OF THE INVENTION
Among the several objects of this invention may be noted the provision of an improved cooling jacket for an electric machine (e.g., motor and/or generator); the provision of such a jacket which comprises an assembly of parts which are relatively economical to manufacture and easy to assemble; the provision of such an assembly which is adapted for the efficient cooling of an electric machine having high heat dissipation requirements; and the provision of a method for making such an assembly.
In general, a cooling jacket assembly of the present invention is used for cooling the stator of an electric machine. The assembly comprises an annular cooling jacket body comprising coaxial inner and outer cylindric shells defining an annular gap therebetween. The inner shell has an outer surface and a cylindric inner surface defining a cylindric cavity for receiving the stator so that the stator is in heat transfer contact with the inner surface. Heat transfer fins in the annular space between the inner and outer shells define flow channels for the flow of coolant therethrough. A first annular end cap is connected to one end of the cooling jacket body and defines an annular conduit around the body in fluid communication with the flow channels. A second annular end cap is connected to an opposite end of the cooling jacket body and defines an annular conduit around the body in fluid communication with the flow channels. An inlet is provided on one or the other of the end caps for flow of coolant into a respective conduit, and an outlet is provided on one or the other of the end caps for flow of coolant out of a respective conduit. Barriers in the conduits direct fluid from the inlet through the flow channels to the outlet along at least one serpentine path comprising a plurality of parallel sections extending axially of the cooling jacket body and connected by the conduits. Each section of the at least one serpentine path comprises a group of two or more flow channels defined by a plurality of adjacent fins.
In another aspect of the invention, the aforementioned serpentine path for the coolant comprises at least first, second and third parallel sections extending axially of the cooling jacket body and connected by said conduits. Each section of the serpentine path comprises a group of flow channels defined by a plurality of adjacent fins. The arrangement is such that coolant is adapted to flow in a first axial direction through the flow channels of the first section, then in a second axial direction generally opposite the first through the flow channels of the second section, and then in said first axial direction through the flow channels of the third section.
In still another aspect of this invention, cooperating registration elements are provided on the body and the first and second end caps to properly orient the end caps relative to the body during assembly of the body and the end caps.
In accordance with another aspect of the present invention, at least one ramp is positioned in the aforementioned conduits and extends across the inlet end of at least one of the parallel sections of the serpentine path for effecting a more uniform distribution of fluid through the flow channels of the section.
The present invention is also directed to a method of making a cooling jacket assembly. The method comprises the steps of extruding a cooling jacket metal body comprising coaxial inner and outer cylindric shells defining a stator-receiving cavity, and fins extending between the shells defining flow channels for the flow of coolant therethrough. The method also includes the steps of casting first and second annular end caps, applying the first and second end caps to the cooling jacket body using registration elements to ensure proper orientation of the end caps relative to the body to provide conduits communicating with said flow channels, and affixing the end caps to opposite ends of the metal body in positions wherein fluid is able to flow through the jacket body in the flow channels and conduits. The method further comprises mounting the stator in said stator-receiving cavity.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.
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Electrical Apparatus Service Association, Inc.,Principles of Large AC Motors, 2000 (The motor shown in Fig. 6 is admitted to be prior art.).
Faye C. McQuiston and Jerald D. Parker,Heating, Ventilating, and Air Conditioning: Analysis and Design, before 1993, p. 619, Third Edition, John Wiley & Sons Publishers.
Frank P. Incropera and David P. DeWitt,Fundamentals of Heat and Mass Transfer, 1990, pp. 119-121, Third Edition, John Wiley & Sons Publishers.
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William C. Reynolds and Henry C. Perkins,Engineering Thermodynamics, 1977, pp. 567-568, Second Edition, McGraw Hill Book Company.
Bostwick Peter K.
Poag Andrew F.
Emerson Electric Co.
Nguyen Tran
Senniger Powers Leavitt & Roedel
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