WO1998044325A9

WO1998044325A9 - Self-contained liquid cooled and lubricated electrical rotary machine

Info

Publication number: WO1998044325A9
Application number: PCT/US1998/006616
Authority: WO
Inventors: Kreso Mikulic
Original assignee: Reuland Electric Company; Kreso Mikulic
Priority date: 1997-04-02
Filing date: 1998-04-02
Publication date: 1999-04-22
Also published as: KR20010005922A; JP2001519905A; WO1998044325A1; AU7101098A; EP0972177A1

Abstract

An electric rotary machine has a self-contained fluid cooled and lubricated structure in a drum drive. In one embodiment, the present invention is embodied in a drum type dynamometer, and more particularly, a chassis dynamometer for testing vehicles. Lubricating coolant is contained in a closed rotatable drum of the dynamometer. Agitators in the form of baffles are provided on the shaft, which facilitate coverage of the coolant on the internal components of the dynamometer. The present invention can be embodied as a drum type electric motor as well. The output drive of the motor is a rotating drum about a fixed shaft. Like the structure of the dynamometer, lubricating coolant is contained in the closed drum. Agitators in the form of baffles are provided on the shaft, which facilitate coverage of the coolant on the internal components of the motor. In both embodiments, the coolant carries heat from the internal components to the drum, which in turn, dissipates the heat to the ambient air.

Description

SELF-CONTAINED LIQUID COOLED AND LUBRICATED ELECTRICAL ROTARY MACHINE

1. Field of the Invention The present invention relates generally to electrical rotary machines, and particularly to electric motors and dynamometers, and more particularly to lubrication and cooling of dynamometers and electric motors.

2. Description of Related Art

An example of an application of a dynamometer is vehicle testing. Vehicular chassis dynamometers are stationary test stands which have been used for testing performances of vehicles (e.g., automobiles) by simulating their running resistance, road conditions, vehicular load conditions, etc. Various performances of a vehicle, such as horse power of the vehicle engine, drive force, torque, fuel consumption, acceleration, fuel emission, etc., may be determined using a chassis dynamometer. Typically, a chassis dynamometer includes a number of rollers on which the drive wheels of the vehicle under test rest in rolling contact. As the vehicle runs, its wheels spin the rollers. At least one of the rollers includes a structure which provides a load to the drive wheels. By varying the load, the vehicle would experience a series of simulated conditions which test its designed performance. Examples of prior art chassis dynamometers may be referenced to U.S. Patent No. 4,077,255 to Murakami, U.S. Patent No. 4,635,472 to Scourtes, U.S. Patent No. 5,337,600 to Kaneko, and U.S. Patent No. 4,077,255 to Fujimori. These prior art devices are all directed to drum type drive systems, in which the roller forms a rotor and the shaft forms a stator. The varying load condition is accomplished by varying the applied power to the stator to vary the eddy current effect between the rotor and stator. By providing a load to the wheels of the vehicle under test, in effect the chassis dynamometer absorbs and dissipates the energy transmitted by the drive wheels of the vehicle. Accordingly, chassis dynamometers must be designed to efficiently dissipate the energy absorbed. Inevitably, some of the energy absorbed in a test is transformed into heat, which if allowed to build up in the chassis dynamometer system, would cause significant problems to its structural and electrical components. For example, Murakami, Kaneko and Scourtes disclose the implementation of air cooling in its chassis dynamometer.

However, inherently, air cooling is not efficient, and it requires a rather complex structure to channel the air through the internal components of the dynamometer. Typically, a pumping and circulation system is required for effective air cooling. Further, since chassis dynamometers operate under the heavy load of test vehicles, the bearings of the dynamometers must be adequately lubricated to reduce the heat generated at the bearings, and improve the durability of the components. However, prior art air cooling structures do not provide a lubrication function with respect to the bearings. A system having separate cooling and lubrication means further increases the complexity of the overall structure of the chassis dynamometer. SUMMARY OF THE INVENTION

The present invention overcomes the drawbacks present in the cooling and lubrication means in the prior art systems. The present invention is directed to a self-contained fluid cooled and lubricated electric rotary machine which has a drum type drive .

In one embodiment, the present invention is embodied in a drum type dynamometer, and more particularly a chassis dynamometer for testing vehicles. Lubricating coolant is contained in a closed rotatable drum of the dynamometer.

Agitators in the form of baffles are provided on the shaft, which facilitate coverage of the coolant on the internal components of the dynamometer. Heat from the components is carried by the coolant to the drum, which in turn dissipates the heat from the coolant to the ambient air.

The present invention can be embodied as a drum type electric motor as well . The output drive of the motor is a drum rotatably supported on a fixed shaft . As in the structure of the dynamometer, lubricating coolant is contained in the closed drum. Agitators in the form of baffles are provided on the shaft, which facilitate coverage of the coolant on the internal components of the motor. Heat from the component is carried by the coolant to the drum, which in turn, dissipates the heat from the coolant to the ambient air.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic view of a vehicle test stand which implements the chassis dynamometer of the present invention. Fig. 2 is a schematic longitudinal sectional view along the axis of the chassis dynamometer in accordance with one embodiment of the present invention.

Fig. 3 is a sectional view taken along line 3-3 in Fig. 2. Fig. 4 is a side view taken along line 4-4 in Fig. 3.

Fig. 5 is a schematic longitudinal sectional view of an electric motor in accordance with another embodiment of the present invention.

Fig. 6 is a schematic view of a roller conveying system which implements the electric motor of Fig. 5.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present description is of the best presently contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims .

The present invention is illustrated by reference to a chassis dynamometer for testing the performance of a car.

However, it is to be understood that the dynamometer of the present inventive design may be implemented for conducting testing of other types of vehicles and machines.

Fig. 1 schematically and generally illustrates a test stand 10 which implements the chassis dynamometer of the present invention. While the specific dynamometer components of the test stand 10 is novel, the general configuration of the test stand 10 is similar to those well known in the art. The test stand 10 generally includes a front set 12 and a rear set 14 of rollers 15, 16, 17, 18 with their axis below a ground plane 20. A portion of the circumferential surface of each roller protrudes above an opening in the ground plane 20. Each set 12, 14 includes two rollers (15, 16 and 17, 18 respectively) having their axes parallel and spaced apart to define a space 21, 22 for receiving a wheel 24 of the car 26. To accommodate cars with single axle drive (e.g., front or rear wheel drive) and dual-axle drive (e.g., four-wheel drive), one of the rollers 16, 18 in each set 12, 14 embodies a dynamometer 30 of the present invention (which will be described below in greater detail in reference to Figs. 2 to 4) and an idler roller 15, 17. During testing of the car, the wheels 24 of the car 26 are supported on the rollers 15, 16, 17, 18 in such a manner that each drive wheel is received in the space 21, 22 defined between the idler roller 15, 17 and the dynamometer roller 16, 18. As the car engine turns the wheels 24, they in turn rotate the rollers 15, 16, 17, 18 that are in rolling contact with the wheels. The dynamometer 16, 18 rollers feed data to a controller 28 which interprets the data to determine the performance parameters of the car. As will be described below, the controller 28 also controls the operation of the dynamometer rollers 16, 18 and other components of the chassis dynamometer system. These control functions are known in the art. A blower 29 may be provided below the ground plane 20 to improve ambient air circulation thereby facilitating external cooling of the rollers 16, 18.

It is noted that the width of each of the dynamometer rollers 16, 18 may be sized to accommodate only one wheel 24 of the car. Alternatively, as illustrated in Fig. 2, the width of the dynamometer rollers 16, 18 may be sized to support both wheels 24 on the same axle of a small car. Such design variations do not depart from the scope and spirit of the present invention.

Referring now to Figs. 2 to 4 , the structure of the dynamometer 30 in accordance with one embodiment of the present invention is schematically illustrated. This structure may be adapted for use in the chassis dynamometer system shown in Fig. 1. It is noted that in order to avoid obscuring the present invention, details in the structure that are not required for the understanding of the inventive concept have been omitted from the figures. These details are within the knowledge of one skilled in the art or can be determined without undue experimentation.

In the illustrated embodiment, the dynamometer 30 has a generally cylindrical drum 32 (forming the rollers 16, 18) which is supported by bearings 34 for rotation about a hollow shaft 36 located along the axis of the drum 32. The drum 32 has a sealed structure with respect to the coolant 38 contained therein (the cooling feature will be described in greater detail below) . Encoders 40 may be provided to monitor the rotational speed of the shaft 36. Coupled to the inside surface of the drum 32 is a rotor 42 made of a magnetic or magnetic inductive material such as a ferromagnetic alloy or a permanent magnet. The rotor 42 may also be configured with an electromagnet, such as an armature excited by an external electric power source via a slip ring coupling on the shaft (not shown in the embodiment of Fig. 2) . The rotor 42 extends around the entire inner circumference of the drum.

Along the shaft 36 is a stator 44 having an armature 46 in opposing relationship to the rotor across an air gap 48. The windings of armature 46 are connected to an external AC power source 55 by a lead 52 which runs through a seal 53 and the shaft 36. The controller 28 controls the power applied to the armature 46. The rotor 42 and/or stator 44 may be segmented (not shown in the figures) to define several magnetic poles. The resultant overall configuration of the armature stator 44 and rotor is similar to a three-phase AC inductive generator. The specific configuration of the stator 44 and rotor 42 combination by itself does not form a part of the present invention. Any conventional configuration may be adapted for purpose of the present invention. The shaft 36 is supported on bearings 50. Coupled to one end of the shaft 36 is one or more known load 52 cells which measure the force or torque on the shaft 36 as the shaft rotates at the bearings 50. The shaft 36 is limited in its rotation by the load cell structure. As between the shaft 36 and the drum 32, the shaft is essentially fixedly supported and the drum is rotatably supported.

In accordance with the present invention, cooling of the internal components of the dynamometer 30 (including the stator 44, armature 46, rotor 42 and bearings 34, etc.) is provided by a lubricating cooling liquid 38 contained in sealed chamber 43 of drum 32. The coolant 38 may be an oil lubricant, such as the SHELL Tellus Oil 32. The drum 32 is a self-contained structure with respect to the coolant 38. The bearings 34 have external seals 35 to prevent oil seepage. To prevent the coolant 38 from getting into a solid body rotation mode as the drum 32 rotates, stationary agitators, e.g., in the form of baffles 54, are provided along the shaft 36 to agitate the coolant 38. In the illustrated embodiment, four baffles 54 are provided around the shaft 36 and at two axial locations along the shaft on each side of the stator 44. It is preferred that at least one baffle extends upwardly from the shaft to ensure that the coolant that has moved to the top part of the drum interior is agitated to fall back onto the internal components of the dynamometer. More baffles may be provided at each axial location and at more axial locations without departing from the scope and spirit of the present invention. It is noted that some amount of heat is generated as a result of the physical agitation of the coolant 38 by the baffles 54. Accordingly, the number of baffles employed should be chosen such that maximum effective overall cooling and lubrication of the dynamometer is accomplished with minimum heating effect of the baffles. Referring to Fig. 4, the baffles 54 are angled with respect to the shaft so as to deflect coolant 38 to the internal components of the dynamometer, such as the stator 44. The specific shape and angle of the baffles 54 may be determine without undue experimentation, depending in part on the size and shape of the drum 32, the amount of coolant 38 contained in the drum, and the extent of agitation for the desired cooling effect. Without the baffles 54, the coolant 38, by viscous coupling to the drum wall, will rotate in synchronization with the drum 32 in a solid body rotation mode, which would not be effective in cooling the internal components of the dynamometer 30. Under static condition (the drum 32 being stationary) , the drum may be filled with coolant 38 to a level 37 such that when the drum rotates, coolant 38 redistributes to a level 39 under centrifugal forces about the drum circumference, the coolant does not continuously submerge the air gap 48 between the rotor 42 and the stator 44. Otherwise, there would be undesirable viscous shearing of the coolant 38 at the air gap 48. The operation of the dynamometer 30 may now be described. When the drum 32 is driven to rotate by the wheel 25 or wheels of the test vehicle, the rotor 42 rotates relative to the stator 44, thereby magnetically inducing a current through the armature windings 46. While inherently there is a reaction force on the rotor 42 tending to oppose its rotation, for the purpose of testing a vehicle, power from the external AC power source 50 is supplied to the armature to create an additional counter-rotation force on the rotor 42. This creates a load on the drum 32 and hence the wheel 24 of the test vehicle 26, which may be varied by the controller 28 to simulate the driving conditions of the test vehicle. As drum 32 rotates, the coolant 38 contained therein redistributes under centrifugal force about the drum circumferential surface, to form an annular band of coolant (dotted line 39) of a nominal thickness less than the distance from the air gap 48 to the circumferential drum surface. This band of coolant is broken up or agitated by the baffles 54 to deflect the coolant and/or cause the coolant to splash momentarily onto the internal components of the dynamometer 30, including the rotor 42, stator 44, shaft 36 and bearings 34. In the process, the bearings 34 are lubricated. At the same time, the coolant 38 absorbs the heat from the internal components generated as a result of the work of the rotor 42 against the applied load provided by the external power to the stator 44. The coolant 38 is then spun off the components by centrifugal force. Heat from the coolant 38 is dissipated through its contact with the circumferential walls of the drum 32. The large external surface of the drum dissipates heat by radiation and conduction from the drum to the ambient air that swirls around the rotating drum. A cooling cycle is thus formed by means of the coolant 38. The blower 29 facilitates ambient air circulation and cooling of the drum. The baffles 54 act like vortex generators to create a sufficient turbulence in the coolant 38 to splash it against all the internal components of the dynamometer 30. As can be clearly appreciated, with the inventive self-contained cooling design, there is no need for a coolant pump and coolant piping. This simplifies the overall system configuration, and improves manufacturability, durability and reliability of the dynamometer. While it is not shown in the illustrations, conceivably, one could combine air and oil cooling of the internal components of the dynamometer by providing air conduits into the interior of the drum.

The selection of the exact dimensions and geometry of the drum 32 depends on the particular application. For example, a long drum may be configured to test all the wheels on an axle of the test vehicle together, or separate shorter drums may be configured to test the wheels independently. Further, other means of providing the counter-load on the drum may be utilized, such as by applying friction to the rotating structure.

A dynamometer is one example of an electrical rotary machine. An electric motor is another example. While different design criteria and objectives are taken into consideration when designing the two types of rotary machines in view of the different natures of their applications, these machines do share some similar structures and attributes. For example, both types of machines include an electric armature component and a magnetic field component that are configured in a manner to allow for relative movement between these components (e.g., relative rotation between the armature and the field component) . As such, in accordance with the present invention, the inventive configuration of the dynamometer 30 described above may be adapted advantageously to configure an electric motor of the type which turns a drum (as opposed to a shaft) to provide the output drive .

Referring to Fig. 5, the electric motor 60 is illustrated in accordance with an embodiment of the present invention. The structure of the motor 60 is conceptually similar to the dynamometer 30 in many respects, as can be appreciated by comparing Fig. 5 to Fig. 2. The electric motor 60 is a three-phase AC motor. It comprises a drum 62 supported for rotation on bearings 64. The shaft 66 is supported fixedly. Like the dynamometer 30, a rotor 72 is provided along the inside wall of the drum 62, and the shaft 66 is provided with a stator 74 which includes an armature 76. Leads 82 from the windings of the armature 76 extend through the hollow shaft 66 to an external AC power source 80 which is controllable by a controller 84. The motor 60 has a self-contained cooling feature including coolant 68 in a sealed structure, similar to the dynamometer 30. Other details of the electric motor 60 may be similar to corresponding parts in the dynamometer 30. A blower 69 may be provided to facilitate ambient air circulation and cooling of the motor drum. In operation, when the armature windings 66 are excited by the external power source 80, the rotor 72 is magnetically induced to rotate about the stator 74, thereby rotating the drum 62 . As the drum 62 rotates, the baffles 84 cause the coolant 68 to splash onto the internal components, thus providing cooling and lubricating functions, similar to the dynamometer 30. It is to be understood that for the electric motor design, one of the design considerations is to obtain an efficient drive output for the same power input. Accordingly, the rotating drum 62 should be designed to have as low an inertial as possible. This is contrasted to a chassis dynamometer 30 which by its nature is designed essentially to be an energy inefficient machine. The specific design differences would depend on the specific applications of the respective machines.

The drum type electric motor 60 is particularly useful for applications in which an external load is driven by contact with the drum surface 62, such as in conveyor belt systems, and roller conveyor systems used for conveying logs, for example .

Referring to Fig. 6, a roller conveying system 90 is schematically illustrated. A series of rollers 92 including at least one drive roller 94 are aligned along a track 96. The load, for example in this case a log 100, rides on the rollers 92 and 94. The drive roller 94 implements an electric motor 102 of the type disclosed in connection with Fig. 5. A controller 104 controls the AC power 106 applied to the motor 102 and the operation of the motor. A blower 103 may be provided to facilitate ambient air circulation and cooling of the rollers below the track 96. In operation, the drive roller 94 moves the log 100 forward by frictional contact as the drive roller 94 is controlled to rotate. The log 100 moves to the next drive roller 94 which continues to move the log 100 along the track 96. While the invention has been described with respect to the illustrated embodiments in accordance therewith, it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.

Claims

1. A dynamometer characterized by: a shaft 36; a hollow structure 32 supported for rotation about the shaft, said structure defining a sealed interior space 43 containing a liquid cooling medium 38; a stator 44 coupled to the shaft within the interior space ; and a rotor 42 coupled to the hollow structure within the interior space in a spaced apart relationship to the stator, whereby when the hollow structure rotates about the shaft, the cooling medium contained therein cools the stator.

2. A dynamometer as in claim 1, further characterized by agitating means 54 coupled to the shaft for agitating the cooling medium as the hollow structure rotates.

3. A dynamometer as in claim 2, further characterized by the agitating means is structured and configured to deflect the liquid cooling medium towards the stator.

4. A dynamometer as in claim 3, wherein the agitating means is further characterized by at least one baffle 54 extending away from the shaft .

5. A dynamometer as in claim 4, wherein the agitating means is further characterized by a plurality of baffles extending away from a plurality of axial locations of the shaft.

6. A dynamometer as in claim 4, wherein the baffle extends upwardly from the shaft .

7. A dynamometer as in claim 1, wherein the stator is structured and configured to receive electrical power from an external power source 55.

8. A dynamometer as in claim 7, wherein the stator comprises armature windings and the rotor comprises a magnetic or magnetic inductive material.

9. A dynamometer as in claim 1, is further characterized by sensing means 50 for determining rotational effect of the rotor on the shaft.

10. A dynamometer as in claim 9, wherein the sensing means is further characterized by a load cell 50 coupled to the shaft .

11.. A dynamometer as in claim 1, wherein the hollow structure is structured and configured generally in the shape of a cylindrical drum, adapted to be driven to rotate by an external structure .

12. A dynamometer as in claim 1, wherein the cooling medium is an oil based liquid.

13. A test stand for testing performance of a vehicle, characterized by: at least one roller configured for rolling coupling to a drive wheel 24 of the vehicle, said roller including a dynamometer which comprises: a shaft 36; a hollow structure 32 supported for rotation about the shaft, said structure defining a sealed interior space 43 containing a liquid cooling medium 38; a stator 44 coupled to the shaft within the interior space; and a rotor 42 coupled to the hollow structure inside the interior space in a spaced apart relationship to the stator, whereby when the hollow structure rotates about the shaft, the cooling medium contained therein cools the stator; and a controller 28 for controlling the operation of the dynamometer.

14. A test stand as in claim 13, wherein the dynamometer is further characterized by agitating means 54 coupled to the shaft for agitating the cooling medium as the hollow structure rotates .

15. A test stand as in claim 14, wherein the agitating means is structured and configured to deflect the liquid cooling medium towards the stator.

16. A test stand as in claim 15, wherein the agitating means is further characterized by at least one baffle extending away from the shaft .

17. A test stand as in claim 16, wherein the agitating means comprises a plurality of baffles extending away from a plurality of axial locations of the shaft.

18. A test stand as in claim 16, wherein the baffle extends upwardly from the shaft .

19. A test stand as in claim 13, wherein the stator is structured and configured to receive electrical power from an external power source 55.

20. A test stand as in claim 19, wherein the stator comprises armature windings 46 and the rotor comprises a magnetic or magnetic inductive material.

21. A test stand as in claim 13, is further characterized by sensing means 50 for determining rotational effect of the rotor on the shaft .

22. A test stand as in claim 21, wherein the sensing means comprises a load cell 50 coupled to the shaft.

23. A test stand as in claim 13, wherein the hollow structure is structured and configured generally in the shape of a cylindrical drum, adapted to be driven to rotate by an external structure .

24. A test stand as in claim 13, wherein the liquid cooling medium is an oil based liquid.

25. An electric motor, characterized by: a shaft 36; a hollow structure 32 supported for rotation about the shaft, said structure defining a sealed interior space 43 containing a liquid cooling medium 38; a stator 44 coupled to the shaft within the interior space, said stator configured and structured to receive electrical power from an external source 55; and a rotor 42 coupled to the hollow structure within the interior space in a spaced apart relationship to the stator, whereby when the hollow structure rotates about the shaft, the cooling medium contained therein cools the stator.

26. An electric motor as in claim 25, further characterized by agitating means 54 coupled to the shaft for agitating the cooling medium as the hollow structure rotates.

27. An electric motor as in claim 26, wherein the agitating means is further characterized by at least one baffle extending away from the shaft.

28. An electric motor as in claim 27, wherein the agitating means is structured and configured to deflect the liquid cooling medium towards the stator.

29. An electric motor as in claim 28, wherein the agitating means comprises a plurality of baffles extending away from a plurality of axial locations of the shaft.

30. An electric motor as in claim 27, wherein the baffle extends upwardly from the shaft .

31. An electric motor as in claim 25, wherein the stator is structured and configured to receive electrical power from an external power source 55.

32. An electric motor as in claim 31, wherein the stator is characterized by armature windings 46 and the rotor comprises a magnetic or magnetic inductive material.

33. An electric motor as in claim 25, further characterized by sensing means 50 for determining rotational effect of the rotor on the shaft .

34. An electric motor as in claim 33, wherein the sensing means comprises a load cell 50 coupled to the shaft.

35. An electric motor as in claim 25, wherein the hollow structure is structured and configured generally in the shape of a cylindrical drum, adapted to be driven to rotate by an external structure.

36. An electric motor as in claim 25, wherein the cooling medium is an oil based liquid.

37. A roller drive system for moving a load characterized by: at least one drive roller 94 adapted for imparting linear movement to the load 100 by rolling coupling to the load, said drive roller including an electric motor which comprises : a shaft66; a hollow structure 62 supported for rotation about the shaft, said structure defining a sealed interior space 75 containing a liquid cooling medium 68; a stator 74 coupled to the shaft within the interior space, said stator configured and structured to receive electrical power from an external source 80; and a rotor 72 coupled to the hollow structure within the interior space in a spaced apart relationship to the stator, whereby when the hollow structure rotates about the shaft, the cooling medium contained therein cools the stator; and a controller 84 for controlling the operation of the electric motor.

38. A roller system as in claim 37, wherein the electric motor is further characterized by agitating means 84 coupled to the shaft for agitating the cooling medium as the hollow structure rotates.

39. A roller system as in claim 38, wherein the agitating means is structured and configured to deflect the liquid cooling medium towards the stator.

40. A roller system as in claim 39, wherein the agitating means is further characterized by at least one baffle extending away from the shaft .

41. A roller system as in claim 40, wherein the agitating means is further characterized by a plurality of baffles extending away from a plurality of axial locations of the shaft .

42. A roller system as in claim 40, wherein the baffle extends upwardly from the shaft .

43. A roller system as in claim 37, wherein the stator is structured and configured to receive electrical power from an external power source 80.

44. A roller system as in claim 43, wherein the stator comprises armature windings 76 and the rotor comprises a magnetic or magnetic inductive material.

45. A roller system as in claim 37, further characterized by sensing means for determining rotational effect of the rotor on the shaft .

46. A roller system as in claim 45, wherein the sensing means comprises a load cell coupled to the shaft.

47. A roller system as in claim 37, wherein the hollow structure is structured and configured generally in the shape of a cylindrical drum, adapted to be driven to rotate by an external structure .

48. A roller system as in claim 37, wherein the cooling medium is an oil based liquid.

49. A rotating electrical apparatus characterized by: a sealed chamber 32; a stator 44 within said sealed chamber, said stator having mounting ends extending outside said sealed chamber; a rotor 42 mounted for rotation relative to said stator within said sealed chamber, said rotor secured to said sealed chamber; a cooling medium 38 within said sealed chamber.

50. A rotating electrical apparatus as in claim 49 further characterized by: means 54 operative during rotation for agitating and distributing said cooling medium within said sealed

51. A rotating electrical apparatus as in claim 49, further characterized by an air gap 48 separating said rotor and said stator.

52. A rotating electrical apparatus as in claim 49, wherein the volume 37 of said cooling medium impinges on a first area of said air gap during nonoperation, and said cooling medium centrifugally distributes into a generally cylindrical volume 39 within said sealed chamber during operation.

53. A rotating electrical apparatus as in claim 49, wherein the cooling medium is an oil based liquid.