Abstract: A rotor assembly includes a housing and a hub. The housing has an open end and an opposed closed end, and is formed with a raised portion in the central location of the closed end. The hub is mounted on the closed end of the housing and covers the housing except for the raised portion to construct a thin motor.

Abstract: A fuel booster operable to compress a combustible fuel, the fuel booster comprising a compressor housing a compress rotor, and a seal assembly coupled to the compressor housing. The seal assembly and the compressor housing cooperate to at least partially define a hermetically sealed compressor chamber. A motor housing is coupled to the seal assembly. The motor housing and seal assembly cooperate to at least partially define a motor chamber that is sealed from the compressor chamber to prevent fluid flow therebetween. The fuel booster also includes a motor having a motor rotor and a motor stator. The motor rotor and the compressor rotor are contained within the compressor chamber. The motor rotor includes a cylindrical surface. The motor stator substantially surrounds the cylindrical surface and is contained within the motor chamber.

Abstract: A variable-capacity water pump includes a housing having an impeller mounted on a rotatable shaft. The impeller includes a plurality of vanes pivotally coupled between upper and lower shroud and operatively coupled to a pitch plate. As the pump speed increases in response to increasing engine speed, the pitch plate controls the rotation of the impeller vanes about a fixed rivet from a maximum pitch position, toward a minimum pitch position, thereby lowering pump output according to engine cooling requirements.

Abstract: A vortex blower is composed of a motor providing a rotating power and including a pivot, a first rear housing mounted in proximity of the pivot and including two through holes at a lower side thereof for communicating respectively with an entrance airway and an exit airway, an impeller mounted inside the first rear housing and on the pivot and rotating along with the shaft, a second rear housing including a through hole at the center thereof and covers on the first rear housing to enable the pivot to run through the through hole and to enable the impeller to be encased inside the first and second rear housings, and a heat-dissipating device mounted outside the second rear housing and is driven by the pivot to work and to generate rapid flowing air outside the first and second rear housings.

Abstract: A circulating lubrication system for a centrifugal pump, or other rotating equipment utilizing an oil sump, is disclosed. The lubrication system includes an external reservoir located distant from the main lubrication chamber, so that lubricating fluid from the main misting chamber is forced out of the main chamber, cooled and cleaned (i.e. filtered) in the external reservoir, and thereafter fed back into the main lubricating chamber. In such a manner, the lubrication system maintains substantially clean, cool, and moisture free lubricating fluid in the main misting chamber and reduces the required downtime of the device. Thus, the life span of the device is lengthened while at the same time production is increased.

Abstract: A fluid pump includes a pump head having an inlet for receiving fluid at a first pressure and an outlet for outputting fluid at a second pressure greater than the first pressure. Pressurized fluid is directed through a first passage to the outlet without the pressurized fluid leaving the pump head prior to reaching the outlet. A second passage directs pressurized fluid to a fluid circulation path which is at least partially external to the pump head with the fluid circulation path terminating adjacent the outlet. Pressurized fluid passing through the first and second passages is directed to the outlet without being re-pressurized by the pump head. The first and second passages are in opposed relation to one another to provide balancing of thrust produced by the flow of pressurized fluid through the passages. An electric motor drives the pump head. The fluid circulation path may include portions of the electric motor.

Abstract: A vacuum pump is capable of preventing reaction products produced by a process gas from being precipitated in the pump, of holding various pump components in an allowable temperature range, and hence of operating in a wide operation range, and which has increased durability. The vacuum pump has a pump casing having an intake port and an exhaust port, an exhaust assembly disposed in the pump casing and having a rotor and a stator, and a heating unit for heating a stator side component of the exhaust assembly positioned near the exhaust port. The heating unit is disposed in a space inside the pump casing where is evacuated during operation, and held in contact with at least a portion of the stator side component of the exhaust assembly positioned near the exhaust port.

Abstract: A fan with improved self-cooling capability having a frame, a stator, a magnetic ring, an iron case, and a rotor blade impeller. The frame has a base for containing the stator, and the stator is provided with at least a coil. The magnetic ring is magnetically coupled to the stator, and the iron case is coupled to the magnetic ring while being provided with at least a first heat dissipation hole. The rotor blade impeller is formed on the iron case, in which at least a second heat dissipation hole aligned to the first heat dissipation hole is formed on a hub of the rotor blade impeller, and the first heat dissipation hole and the second heat dissipation hole are not formed to directly align to a position of the coil.

Abstract: A fan (10) is disclosed having a downrod (11), a motor (12), a motor housing (13) substantially encasing the motor (12), and blades (14) mounted to the motor housing (13). Each blade (14) has an air intake scoop (16 adjacent to and extending from the motor housing (13). The interior space (17) created by the intake scoop (16) is in fluid communication with an opening (18) extending through the motor housing (13). Rotational movement of the air intake scoops (16) create airstreams which are directed to the electric motor for ventilation purposes.

Abstract: In a flat-type blower unit disposed in a narrow space between a bottom portion of a front seat and a vehicle floor in a vertical direction, a motor-attachment bracket part for attaching a fan motor is integrally formed with a drive circuit cover part for covering a motor drive circuit to construct a motor attachment bracket having heat-generating components which generate heat when being operated. The motor attachment bracket is disposed to protrude radial outside from the fan motor, so that a dimension of the motor attachment bracket in the vertical direction can be reduced.

Abstract: An air pump is provided with a motor body having an air slot to allow air to flow from the air slot to air inlets positioned in a front sealing cap of the motor body. The air inlets are aligned with air holes in a closed housing. A shaft of the motor body extends into the closed housing which houses a piston. The shaft of the motor body is connected to gearing mechanisms in the closed housing to provide reciprocating motion of the piston. The piston includes an air inlet and a valve. The reciprocating movement of the piston causes air to travel through the piston into a cylinder above the piston. The design of the pump affords a cooling function to both the motor body and cylinder while reducing the noise of the pump.

Abstract: A device for the local cooling or heating of an object by means of a fluid is disclosed. The device comprises a circulation pump for the fluid. A thermal contact element for making thermal contact with the object is integrated in the circulation pump.

Abstract: The invention relates to an electrically driven flow compressor comprising a drive (2, 3)—and a flow compressor and a converter (5) for electrical supply and control of the drive unit (2, 3).According to the invention, the converter (5) and the drive unit (2, 3) form an integral arrangement. Said inventive flow compressor has a reduced size, excellent electromagnetic performance and reduced production costs compared to flow drives with an external frequency converter.

Abstract: Disclosed is a canned pump comprising a housing, a rotor contained in the housing, a circuit substrate supported on the housing, semi-conductor means for power control attached to the circuit substrate, an end cover attached to the housing to cover the circuit substrate, and a heat sink having heat radiating means for cooling the semi-conductor means for power control.

Abstract: A pump including an electric motor mounted in a motor casing, and a rotatable pumping member, the pumping member when rotated by the motor pumping a first fluid, there being a first fluid flow path for the first fluid from a high pressure side of the pumping member, into the motor casing to cool the motor, and to a low pressure side of the pumping member, the pump further including a heat exchanger located between a wall of the motor casing and a heat load, the heat exchanger including a second fluid flow path for a second fluid so that in use, heat is exchanged between the first and second fluids.

Abstract: A rotordynamic system includes a vertically arranged motor, rotordynamic device and controller. The rotordynamic device is a centrifugal pump or compressor operated by the motor to drive a fluid from the input to the output. A liquid cooling system operates to maintain the controller and motor at a desired operating temperature. Due to the liquid cooling system, the controller operates the motor at effectively any practical speed. The liquid cooling system is in heat exchange relationship with an oil system contained within the motor to distribute thermal energy therebetween to further increase thermal control of each.

Abstract: The radial turbo-blower comprises a stator (35) that is housed in a stator housing (10) and a rotor (13) that rotates within a pump housing (11). The rotor (13) comprises a cavity (23) with a bearing arrangement (26) that is received by a protruding bearing pin (25). A pump chamber (12) is separated from a stator chamber (22) by a thin partition wall (21). Thereby, an atmospheric pressure is maintained in the stator chamber (22). The blower consists of few components and has a short structural length. It is substantially maintenance-free and the rotor area is protected from being contaminated by oil.

Abstract: The invention relates to an electric fan, in particular, for motor vehicles, comprising an electric drive motor, a fan wheel coupled with the drive motor, and an electronic control unit for controlling the motor. In order to make the electric fan structurally more simple and more cost-effective to assemble, it is proposed that the drive motor and the control unit be arranged in a common housing, and that the housing have air vents for passage of a flow of cooling air generatable by the fan wheel, and a heat sink of the control unit be arranged at at least one air vent.

Abstract: This invention provides a small, high efficiency, oil free motor driven compressor/blower suitable for providing pressurized, contamination-free gas and or air to transportation, industrial and aerospace fuel cell systems or other contaminant-intolerant applications. The motor driven compressor/blower rotor assembly is supported by foil air bearings and rotates at high speed by using a high frequency drive. The impeller is a centrifugal type design. The MDC can be easily integrated into the air management system of a fuel cell.

Abstract: A cascade thermoelectric cooler designed to cool to cryogenic temperatures of 30 to 120 K integrates high performance\high-ZT BixSb2−xTe3 and Bi2Te3−xSe3-based super-lattice-structure thin-film thermoelectric devices with a bulk-material based thermoelectric cooler including plural cascaded cold stages with each successive cascaded cold stage able to cool to a progressively lower temperature. Each cold stage in the bulk-material thermoelectric cooler includes a heat source plate, a heat sink plate, a p-type thermoelectric, and a n-type thermoelectric. Moreover, the thin-film thermoelectric cooler can have multiple stages in which each stage contains a heat source plate, a heat sink plate, a p-type super-latticed thermoelectric element, and a n type super-latticed thermoelectric element.

Abstract: A centrifugal pump for pumping low temperature fluid includes a motor portion driving an impeller of a pump portion. The motor portion and impeller are coaxial. A pot, sealed to the pump portion, receives the low temperature fluid. The low temperature fluid contacts only the pump portion in the pot, thereby reducing the overall heat capacity of the centrifugal pump to reduce start time. A heat insulating jacket is in tight contact with the motor portion. A vent pipe extends from the pot, through the pump portion and within the heat insulating jacket, to a rear of the motor portion to increase safety and provide double-insulation to the vent pipe. The heat insulating jacket reduces the size and surface area of the centrifugal pump to resist heat flow and increase safety.

Abstract: A device for cooling and lubricating a subsea device (1) which includes an electric rotary machine (4) and a fluid-rotation machine (6-8) drive-connected (5) thereto, which electric rotary machine (4) has a lubrication/cooling circuit includes a cooler (11) exposed towards the surrounding seawater, and where the fluid-rotation machine (6-8) has a fluid pressure at the end facing towards the electric rotary machine (4). The lubrication/cooling circuit (12, 11, 14) is pressure-impacted by the fluid pressure at one point (19, 20) in the lubrication/cooling circuit outside the fluid-rotation machine (6-8).

Abstract: A heater 29 is mounted on the outer peripheral surface of a base 6 to heat the base 6. By heating the base 6, the interior of a gas discharge path for process gas is kept at a high temperature, and hence the precipitation of solid product in the pump is restrained. Also, a pump inside substrate 25 in which various types of information on a vacuum pump are stored is arranged on the inside of a back cover 26. A water cooled tube 30 is installed on the back cover 26 on which the pump inside substrate 25 is arranged, whereby the back cover 26 is cooled forcedly. Further, a heat insulating material 27 with low heat conductivity is arranged in a connecting portion 27a and a contacting portion 27b between the back cover 26 and the base 6. By constructing the vacuum pump in this manner, the pump inside substrate 25 can be cooled efficiently while the gas discharge path for process gas in the vacuum pump is kept at a higher temperature than before.

Abstract: A heater 29 is mounted on the outer peripheral surface of a base 6 to heat the base 6. A heat shutoff wall 24b is provided on a motor housing 24 to prevent the radiation heat of the base 6 heated by the heater 29 from transferring to a pump inside substrate 25. A gap portion 27 is formed by providing a gap between the motor housing 24 and the base 6 to prevent the heat of the base 6 heated by the heater 29 from transferring to the motor housing 24. Also, a water cooled tube 28 is installed under the motor housing fixing portion 24c and cooling water is circulated in the tube to efficiently cool the pump inside substrate 25. By constructing a vacuum pump in this manner, the accumulation of solid product of process gas in the vacuum pump is restrained, and thus the pump inside substrate can be cooled efficiently.

Abstract: An impeller pump with thermostatically adjustable guide vanes is suitable for use as an automotive coolant pump. The pump is driven by a constant speed electric motor, and flow variation is controlled by varying the orientation of the vanes. Orientation of the vanes is effected by a wax-type thermostat, which senses coolant temperature: flow is increased when the coolant is hot, and decreased as the coolant cools. The variable guide vanes are mounted for pivoting about radial axes, and are located just upstream from the pump impeller.

Abstract: A rotordynamic system includes a vertically arranged motor, rotordynamic device and controller. The rotordynamic device is a centrifugal pump or compressor operated by the motor to drive a fluid from the input to the output. A liquid cooling system operates to maintain the controller and motor at a desired operating temperature. Due to the liquid cooling system, the controller operates the motor at effectively any practical speed. The liquid cooling system is in heat exchange relationship with an oil system contained within the motor to distribute thermal energy therebetween to further increase thermal control of each.

Abstract: A vacuum pump comprises a pump case having an interior space, a rotor disposed in the interior space of the pump case, and a thread stator disposed in the interior space of the pump case and opposite to an outer peripheral surface of the rotor. At least one heater is arranged in the thread stator for heating the interior space of the pump case. An output device outputs a parameter constituting a factor for determining a temperature of the rotor. A memory stores a database containing information corresponding to a relationship between the parameter output by the output device and a preselected temperature of the heater. A controller inputs the parameter output by the output device and selects from the database stored in the memory the preselected temperature of the heater in accordance with the input parameter.

Abstract: A propeller-type fan including a pressure housing for improving air flow past a motor which powers the fan.

Abstract: A bypass discharge motor assembly with improved noise reduction includes a motor assembly having a rotatable shaft. A working air fan assembly and a cooling fan are rotated by the shaft. A cooling fan housing is coupled to the motor assembly and partially encloses the cooling fan. The cooling fan housing has at least one radial air entry part for radially receiving cooling air drawn into the housing by the cooling fan.

Abstract: A fan having a supercharging structure includes a casing having an air passage hole with an air inlet at a first end thereof and an air outlet at a second end thereof. A base is mounted to the air outlet end of the casing. A supporting plate is mounted in the air passage hole of the casing or an air outlet in the base for engaging with a stator bobbin that pivotally holds a fan wheel to be driven. Plural supercharging plates are mounted between the supporting plate and the base.

Abstract: A fluid pump, in particular for the coolant and heating system of a motor vehicle, has a stator (21) of claw pole construction and a rotor (6), separated from the stator (21) by a pipe (11), which is immersed in the coolant and forms a vane wheel. The rotor (6) is disposed radially inside the stator (21).

Abstract: An impeller pump with thermostatically adjustable guide vanes is suitable for use as an automotive coolant pump. The pump is driven by a constant speed electric motor, and flow variation is controlled by varying the orientation of the vanes. Orientation of the vanes is effected by a wax-type thermostat, which senses coolant temperature: flow is increased when the coolant is hot, and decreased as the coolant cools. The variable guide vanes are mounted for pivoting about radial axes, and are located just upstream from the pump impeller.

Abstract: A multi-stage centrifugal compressor multi-stage centrifugal compressor with an integral high-speed motor for compressing air has a variable speed permanent magnet motor having electronically commutated stator coils surrounding a rotor carrying permanent magnets, wherein there is a gap between the coils and the rotor. The rotor has a magnetic steel rotor shaft rotatably supported at each end by pressurized oil lubricated hydrodynamic bearings. The stator coils have a plurality of stator wires extending longitudinally along the stator and continuing around the ends of the stator to define end turns. The compressor also has a plurality of compressor impellers mounted to turn with the rotor shaft and cooler for cooling the bearings, rotor and stator coils comprising a pump for introducing cooled oil into the bearings, said bearing configured so that oil exiting from the bearings splashes over the supported ends of the shaft and splashes over the end turns of the stator coils.

Abstract: In an exemplary embodiment, a motor assembly includes a shaft and a compound fan assembly that provides axial and centrifugal air flow. The fan assembly includes a body including an outer surface, a cavity defined by the body outer surface, a plurality of first blades extending radially outwardly from the body outer surface, and a plurality of second blades disposed within the cavity. The shaft is concentric with the body and the second blades are rotatably coupled to the shaft.

Abstract: An air ventilation structure for D.C. brushless air fans provides a selected number of side apertures on the side wall of the air fan casing and slot openings at the front end of the air fan rotor. Through the side apertures and slot openings, high temperature generated during the air fan operation will be carried away and air ventilation in the air fan will increase thereby increase the air fan durability.

Abstract: The mobile part of a fan includes at least one rotor of an electric motor and fan blades integral with the rotor. A rotating fixed part includes at least one stator of the electric motor. The fan additionally includes at least part of the electric motor that includes the stator arranged in an enclosed chamber. The motor-operated fan includes structure for guiding a first fluid passing through at least one of the mobile part and fixed part of the motor-operated fan between a fist zone with a first pressure of the first fluid outside the enclosed chamber on a first side of the blades of the motor-operated fan in an axial direction, and a second zone with a second pressure on a second side of the blades of the motor-operated fin outside the enclosed chamber, the second pressure being less than the first pressure.

Abstract: A motor-fan assembly for a floor care appliance having an improved working air fan for increased performance and noise reduction, a working air fan housing cover having a plurality of spiral shaped grooves, and a motor cooling air fan housing cover with slot shaped vent openings for increased cooling performance. The working air fan has a larger number of blades as compared to conventional fans wherein the blades are of two different lengths arranged in an alternating pattern circumferentially on an annular shaped disc. The blades are spaced closer together to prevent the passage of debris between adjacent blades and also to reduce flow noise. The passage between the edges of the fan blades and the working air fan cover has been widened and made uniform to aid in the passage of debris over the top of the working air fan.

Abstract: A high-efficiency motor/pump system (20) for jetted baths/spas includes a pump assembly (22) removably secured to a motor assembly (24). The motor assembly (24) includes a motor (26) having a conventional laminated stator (30), a front housing (32) at the forward end of the motor (26), a rear housing (34) at the back end of the motor (26), and a ventilation plate (36) at the end of the rear housing (34). An armature-mounted internal fan (104) draws ambient air through openings in a ventilation plate (36) and forces the air through annular channels (80) in the rear housing (34) to effect cooling of the motor (26). The motor (26) is of the permanent split-capacitor type to eliminate the centrifugal switch commonly used in capacitor-start induction motors to thereby improve reliability. Additionally, telescoping structures on the forward end of the motor assembly and the rearward end of the pump assembly facilitate self-aligning assembly of the components.

Abstract: A through-flow blower assembly includes a housing that carries a motor assembly. The motor assembly has a stator, and a rotor that rotates a shaft when energized. The rotor has openings therethrough. A fan shell has an axial opening and is coupled to the housing. At least one rotating fan is carried by the shaft. The rotating fan draws working air through said axial opening and exhausts the working air through an exhaust port of the housing. The rotating fan has a diameter larger than the rotor. A cooling fan is attached to the rotor and includes a fan disc and a fan ring. The fan disc is connected to the fan ring by a plurality of blades, said fan ring having an eye that is directly adjacent the rotor openings. The cooling fan has a diameter no larger than said rotor. As the rotor rotates, the cooling fan draws a portion of the working air over the motor assembly for cooling purposes. Stationary fans may be carried by the fan shell if more than one rotating fan is provided.

Abstract: A composite heat dissipation fan, including an impeller having first blades, and the first blades having a periphery combined with second blades for creating a side directed wind supply. The impeller is provided with a magnet ring which is energized with the stator coils of the base plate, so that the impeller is induced to rotate about the rotation shaft of the base plate. The first blades draw the ambient cold air through the wind inlet opening, and the wind outlet opening of the base plate drains the wind outward. The second blades uses part of the cold air to drain wind sideward, thereby providing a multi-directional wind draining effect so as to increase the heat dissipation efficiency.

Abstract: A centrifugal compressor assembly includes two centrifugal compressor stages, a diffuser duct, a plurality of collection chambers, inlet and outlet tubing, and a built-in electrical motor between the stages. The centrifugal compressor assembly is used in a refrigerating system. The electrical motor includes a rotor positioned with the compressor stage rotors on one shaft mounted on gasodynamic bearings, with the stator fixed inside the motor housing, forming a cooling skirt. The cooling skirt for the stator is formed by lengthwise slots on the surface of the stator in contact with the housing, with the ends of the slots being connected to annular grooves on the internal surface of the motor housing. Each of the annular grooves is connected to coolant feed and discharge ducts.

Abstract: The invention concerns a turbo molecular pump which can release the heat generated in a impeller without cooling a base section. A casing-side cylinder is extended downwardly. A water-cooling pipe is contacted with a casing bottom surface in a spring manner within a space defined by the casing-side cylinder, the casing bottom surface and a bottom cover.

Abstract: A compressor system having a first compartment for housing relatively quietly operating equipment, and a second compartment for housing relatively noisy operating equipment. The second compartment is substantially closed off from the surrounding atmosphere to reduce the amount of noise that can be heard outside the compressor system on account of the noisy equipment operating within the compressor system housing. The second compartment includes a small air inlet opening and a small air outlet opening to allow enough air to flow through the second compartment to cool the equipment housed therein. The small openings reduce the amount of air-born noise which is released to the outside environment.

Abstract: A centrifugal pump for pumping low temperature fluid includes a motor portion driving an impeller of a pump portion. The motor portion and impeller are coaxial. A pot, sealed to the pump portion, receives the low temperature fluid. The low temperature fluid contacts only the pump portion in the pot, thereby reducing the overall heat capacity of the centrifugal pump to reduce start time. A heat insulating jacket is in tight contact with the motor portion. A vent pipe extends from the pot, through the pump portion and within the heat insulating jacket, to a rear of the motor portion to increase safety and provide double-insulation to the vent pipe. The heat insulating jacket reduces the size and surface area of the centrifugal pump to resist heat flow and increase safety.

Abstract: In a turbo-molecular pump, a rotor is supported by a magnetic bearing (3) in a non-contact mode. A pump control section (2) has a magnetic bearing control device (8) with a digital signal operating processor or DSP (7) which is programmable by a software or which can execute a programmed software. The digital signal operating processor (7) performs the control of a heating system, namely, a heater, as well as the control of the magnetic bearing (3).

Abstract: Water circulation apparatus for use in a spa or the like utilises a turbine or axial flow pump for pumping the water from a water inlet to the jets or other exhaust openings within the spa and under the water surface. Cooling air from ambient surroundings is used to cool a motor providing power to the pump. The motor and pump are located within a component compartment and exhaust openings exhaust the cooling air passing through the motor where it may be used for heating towels. The component compartment may be sealed thereby to allow heated air to escape only from the exhaust openings.

Abstract: A two-stage, permanent-magnet, integral disk-motor centrifugal pump, has a housing having first and second suction ports and first and second discharge ports, the first discharge port being connected to the second suction port. A first impeller is rotatably disposed on a shaft between the first suction port and the first discharge port and a second impeller is placed back-to-back with the first impeller and rotatably disposed on a shaft between the second suction port and the second discharge port, each of the first and second impellers having a back shroud with an array of permanent magnets fixed thereto. A first stator and a second stator are interposed between and adjacent to the first and second impellers, respectively, the rotational speed of the impellers being controlled by invertors acting upon the stators. Provisions are also included for extracting motor heat from the pump.

Abstract: A turbo molecular pump comprises an electric component section having a motor, a base section supporting the electric component section, a shaft rotationally driven by the motor, and an impeller connected to the shaft for rotation therewith. A casing houses the electric component section, and a heat insulating material is disposed between the casing and the base section.

Abstract: The present invention relates to a composite heat dissipation fan, including an impeller having first blades, and the first blades having a periphery combined with second blades for creating a side directed wind supply. The impeller is provided with a magnet ring which is energized with the stator coils of the base plate, so that the impeller is induced to rotate about the rotation shaft of the base plate. The first blades draw the ambient cold air through the wind inlet opening, and the wind outlet opening of the base plate drains the wind outward. The second blades uses part of the cold air to drain wind sideward, thereby providing a multi-directional wind draining effect so as to increase the heat dissipation efficiency.

Abstract: A through-flow blower assembly includes a housing that carries a motor assembly. The motor assembly has a stator, and a rotor that rotates a shaft when energized. The rotor has openings therethrough. A fan shell has an axial opening and is coupled to the housing. At least one rotating fan is carried by the shaft The rotating fan draws working air through said axial opening and exhausts the working air through an exhaust port of the housing. The rotating fan has a diameter larger than the rotor. A cooling fan is attached to the rotor and includes a fan disc and a fan ring. The fan disc is connected to the fan ring by a plurality of blades, said fan ring having an eye that is directly adjacent the rotor openings. The cooling fan has a diameter no larger than said rotor. As the rotor rotates, the cooling fan draws a portion of the working air over the motor assembly for cooling purposes. Stationary fans may be carried by the fan shell if more than one rotating fan is provided.