Abstract: A rotary electric machine includes: a stator, a rotor and rotor fans contained in a closed type frame. The cooling gas is circulated in the frame by the rotor fans and warmed as a result of heat exchange with the stator and the rotor is cooled by a gas cooler. A heat pump is adapted to use cooling water or ambient air as high temperature heat source and liquid coolant as low temperature heat source. A liquid coolant circulation system for supplying liquid coolant to the heat exchange section of the gas cooler is provided. The liquid coolant is cooled by the heat pump and is supplied to the heat exchange section of the gas cooler by means of the coolant circulation system.

Abstract: An electric motor including a motor portion, a cooling portion and a plurality of heat pipes is provided. The motor portion includes a stator and a rotor that when energized with electric current causes the rotor to rotate. The motor portion comprises a motor frame that encloses the rotor and stator from exterior elements. The cooling portion is adjacent the motor portion and exterior of the motor portion. In various embodiments it defines a fluid chamber containing a quantity of fluid that is prevented from contacting interior of the motor portion. The plurality of heat pipes within the motor portion extend from the motor portion to the cooling portion such that the fluid contacts the heat pipe within the cooling portion in order to remove heat from the heat pipe.

Abstract: A redundant cooling device, for an electrical submarine drive motor, includes a first cooling circuit and a second cooling circuit, by which thermal energy may be removed from the electric submarine drive motor. A high degree of operational security and redundancy may be provided, whereby the coolant in the first cooling circuit and the second cooling circuit flow counter-currently through a stator cooling circuit in the region of the electrical submarine drive motor.

Abstract: The present invention relates to a cooling system and method for the concentrated motor stator windings of an electric motor. The cooling system and method provides coolant directly onto the motor stator windings and between each adjacent stator winding. The motor housing assists in distributing coolant between each stator winding of the electric motor assembly. Moreover, an insulated sheet and/or tube is insertable between the concentrated motor stator windings. Each is configurable to direct coolant directly on to the stator windings.

Abstract: A spray cooled motor system with a motor housing with an interior and an exterior, a stator mounted within the interior of the motor housing, a rotor mounted within the interior of the motor housing, a coil winding mounted within the interior of the motor housing, a plurality of atomizers configured to spray a coolant on at least one of the stator and the rotor, a coolant pump in fluid communication with the plurality of atomizers; and an output shaft extending through an output shaft aperture from the interior to the exterior of the motor housing.

Abstract: A transmission includes a housing, an electric motor having a stator within the housing, and a member including a generally cylindrical portion that circumscribes at least part of the stator. The member cooperates with the housing to form an annular coolant flowpath therebetween, and the member includes a plurality of holes to provide radial inflow of coolant from the flowpath to the stator to provide significantly improved motor cooling compared to the prior art.

Abstract: A water-cooled stator bar clip for electrical generators and a method for applying a corrosion-resistant protective coating, preferably Sc, Ti, Cr, Zr, Nb, Mo, Hf, Ta, W, Ni, and Al, and their alloys or oxides to existing stator bar end fittings in order to significantly reduce the possibility of leaks through the brazed connections of the copper stator bar end connections. The coatings can be applied locally using various known physical vapor deposition (“PVD”), chemical vapor deposition (“CVD”) or other direct coating techniques known in the art. For example, the coatings can be applied using ion plasma deposition, sputtering or wire arc techniques (all PVD processes) or by using electroplating, high velocity oxygen free (“HVOF”) deposition, DC arc or electroless plating. Preferably, the coatings are applied either to new stator bar clips or to existing clips in the field.

Abstract: A method for monitoring a fan comprises measuring power usage of the fan, determining a derivative of the measured fan power usage, tracking the derivative over time, and predicting impending fan failure based on the tracked fan power usage derivative.

Abstract: A cooling jacket for an electric motor and a motor unit with a cooling jacket mounted on an electric motor having simple structure and capable of being manufactured with reduced number of processes. A cooling pipe made of copper and the like is bent, and held by plate members and lid members, and resin having high heat-conductivity is filled in between to form a series of segments of the cooling jacket. Adjacent ones of the segments are connected with each other by connecting members to form the cooling jacket. The plate members are formed to conform with a shape of the electric motor. The series of segments are mounted on an outer surface of the electric motor and gaps between the adjacent segments are adjusted to bring the plate members into close contact with the outer surface of the electric motor.

Abstract: A cooling system for an electric motor includes a cooling duct formed between a cooling jacket and a separate component surface. The separate component surface may define at least a portion of a wall of the cooling duct. The cooling duct may be configured to direct a cooling liquid along at least a portion of the separate component surface and draw heat from the electric motor. An inlet port may be in fluid communication with the cooling duct. The inlet port may be configured to receive the cooling liquid and to introduce the cooling liquid to the cooling duct. An outlet port may be in fluid communication with the cooling duct.

Abstract: In the stator of a electric rotary machine in which heat conductive insulation resin is filled at the end portions of a stator coil, the material of a stator core, the stator coil, the heat conductive insulation resin and a frame is selected such that a linear thermal expansion coefficient ?1 of the stator core, a linear thermal expansion coefficient ?2 of the stator coil, a linear thermal expansion coefficient ?3 of the heat conductive insulation resin being filled and a linear thermal expansion coefficient ?4 of the frame satisfy a relation that ?1<?2 <?4 ??3. A cooling medium path is integrally formed within the frame made from aluminum through die casting molding.

Abstract: The present invention is drawn to a method and apparatus for cooling a hybrid transmission electric motor. More precisely, an annular chamber is formed between a housing for the electric motor and a transmission housing. Coolant is disposed in the annular chamber and is applied to the electric motor through a plurality of coolant apertures in the motor housing to cool the motor.

Abstract: A cooling device for an internal stator of an electric machine. The stator includes a substantially cylindrical cavity having a substantially cylindrical internal surface. The cooling device includes a body defining an external substantially cylindrical contact surface. The cooling device further includes a biasing element connected to the body. The biasing element is so configured and sized as to bias the contact surface of the body against the internal surface of the rotor when the cooling device is positioned inside the cavity.

Abstract: An electric motor, transformer or inductor having a lamination cooling system including a stack of laminations, each defining a plurality of apertures at least partially coincident with apertures of adjacent laminations. The apertures define a plurality of cooling-fluid passageways through the lamination stack, and gaps between the adjacent laminations are sealed to prevent a liquid cooling fluid in the passageways from escaping between the laminations. The gaps are sealed by injecting a heat-cured sealant into the passageways, expelling excess sealant, and heat-curing the lamination stack. The apertures of each lamination can be coincident with the same-sized apertures of adjacent laminations to form straight passageways, or they can vary in size, shape and/or position to form non-axial passageways, angled passageways, bidirectional passageways, and manifold sections of passageways that connect a plurality of different passageway sections.

Abstract: A rotating electric machine having a plurality of ventilating passages formed between a stator frame and a stator iron core and coolers which cool a coolant being provided in the plurality of the ventilating passages. A ventilating circuit in which at least a portion of the coolant which is cooled by one of the coolers is further cooled by another of the coolers, and is allowed to flow to a central portion in an axial direction of the stator iron core in a direction from an outer peripheral side to an inner peripheral side of the stator iron core at least via one ventilating passage of the plurality of ventilating passage which communicates with the central portion in the axial direction of the stator iron core.

Abstract: Methods and related systems providing removal of heat from electric motors via fluid baths.

Abstract: A multi-shaft, multi-layer motor has a stator coaxially disposed between inner and outer rotors which are driven independently by a compound current. For cooling stator coils, first through last branch coolant passages are arranged around the axis. The upstream ends of the first through last branch passages are arranged in sequence circumferentially along a distributing circumferential passage in a direction away from a common introduction port for introducing the coolant into the distributing circumferential passage, and the downstream ends of the first through last branch passages are distributed in sequence circumferentially along a collecting circumferential passage in a direction toward a common discharge port for discharging the coolant from the collecting circumferential passage.

Abstract: A multi-shaft, multi-layer motor includes an inner rotor, an outer rotor surrounding the inner rotor, and a stator disposed coaxially between the inner and outer rotors. The motor further includes an outer member surrounding the outer rotor and defining a first wet chamber between the outer rotor and the outer member; an inner member defining a second wet chamber surrounded by the inner rotor; and an intermediate member defining a dry chamber communicating with an outer air gap between the stator and the outer rotor, and an inner air gap between the stator and the inner rotor.

Abstract: A rotor with wedges and a method of retaining wedges in a rotor are disclosed. The rotor includes a shaft, first and second poles extending radially from the shaft, and first and second coils of windings respectively wrapped around the first and second poles. Each coil includes a respective outer face including two end portions and two side portions, and a respective inward-facing edge including two end sections and two side sections. The rotor further includes a first outer wedge positioned between neighboring side portions of the first and second coils, and a first inner wedge positioned between neighboring side sections of the first and second coils. The first inner wedge is coupled to the first outer wedge so that the first outer wedge is at least partly retained from moving radially outward away from the shaft.

Abstract: A generator gas shield includes an annular ring body having an outer radially extending flange terminating at a first free end of a first diameter; a curved inlet portion; a substantially axial portion surrounding a center opening, and a curved outlet portion terminating at a second free end of a second diameter smaller than the first diameter.

Abstract: A rotating electric machine exhibits a substantially level axial temperature rise distribution by supplying a coolant which is sufficiently cooled to a central portion of an iron core which is most distant from each of the axial ends of the iron core. A plurality of ventilating passages, which continuously extend in the peripheral direction, are provided in the axial direction between a stator frame and a stator iron core, and coolers are provided in the ventilating passages. A coolant boosted by a booster is cooled by the coolers and is allowed to flow to a central portion of the stator iron core in the direction from the outer peripheral side to the inner peripheral side of the stator iron core via ventilating passages which communicate with the central portion of the stator iron core.

Abstract: Electric machine (10) which can be operated as a motor or generator, with a rotor (26a, 26b) rotatably mounted in a housing (12), a rotor shaft (24) which extends beyond the housing (12) and a plurality of electromagnet components (28) which are statically disposed in the housing at uniform angular spacings and spaced from the axis of rotation of the rotor, each with a coil core (32) bearing a coil winding (30) consisting of one or more conductors. The pole faces of the end faces of the coil cores (32) are aligned with pole faces of permanent magnets (27) which are retained non-rotatably in or on the rotor and each have a polarity which is successively reversed in the peripheral direction.

Abstract: A coolant inlet and a coolant outlet are opened on an inner surface enclosing an inner space of a rotation object. The coolant inlet and the coolant outlet are located on a rotation axis and face each other. A main-stream which flows straightly along the rotation axis from the coolant inlet to the coolant outlet is generated in a central space of the inner space. Therefore, a resistance about the coolant stream is small. In addition, a sub-stream which circulates in a radial direction is generated in a peripheral space around the central space. By generating a contact between the main-stream and the sub-stream, it is possible to obtain high performance of cooling.

Abstract: A liquid-cooled vehicle generator-motor includes a frame having a liquid passage, a stator core fixedly fitted to the inner periphery of the frame, a multi-phase stator winding accommodated in the plurality of slots of the stator core, and a rotor disposed inside the stator core. The stator winding includes a plurality of insulated U-shaped conductor segments each of which has a pair of legs. Each leg is inserted in a slot from one end of the stator core and paired to another at a portion extending from the other end of the stator.

Abstract: A generator gas shield includes an annular ring body having an outer radially extending flange terminating at a first free end of a first diameter; a curved inlet portion; a substantially axial portion surrounding a center opening, and a curved outlet portion terminating at a second free end of a second diameter smaller than the first diameter.

Abstract: A method of maintaining a desired level of sub-transient reactance in a superconducting machine includes specifying a desired level of sub-transient reactance. A stator assembly is produced that includes at least one stator coil assembly having a first predefined length. A rotor assembly is produced that is configured to rotate within the stator assembly. An asynchronous field filtering shield, having a second predefined length that is less than the first predefined length, is positioned between the stator assembly and the rotor assembly. The desired level of sub-transient reactance is achieved by adjusting either the first predefined length or the second predefined length.

Abstract: In a linear motor coil assembly (12), and a method for manufacturing the same, a plurality of coils (14) are arranged in a line in a direction of movement and have respective coil axes perpendicular to the direction of movement of the motor. A flat cooling tube (20) is arranged to meander inside the plurality of coils. The cooling tube has a cross section elongated in a direction parallel to the coil axes, and a plurality of clearance holes (25) through which coolant flows are formed inside the cooling tube. The cooling tube has interleaved folds at least equal in number to the number of coils. The coils being fitted into these folds. At the time of manufacture of the coil assembly, the coils are wound around cores that are divided for each coil, and the cores are inserted into the folds of the cooling tube.

Abstract: A system and method is disclosed for the construction of a frameless cartridge motor. In accordance with one embodiment of the present invention a frameless cartridge motor is provided such that the motor's rotor is aligned with the motor's stator, a feedback device is calibrated and attached to the motor via a flexible member, and fasteners fix the rotor to motor's housing.

Abstract: A cooling arrangement for an electrical machine—for example, a permanent-field synchronous machine of a vehicle. The electrical machine is connected to the engine block of the vehicle. In order to ensure cost-effective cooling of the electrical machine, the electrical machine includes a support element, and the engine block includes a cooling element. At least a region of the electrical machine is connected via the support element to the cooling element of the engine block such that the heat generated during operation of the electrical machine dissipates thermally into the engine block.

Abstract: A motorized wheel hub assembly includes a sealed motor section having first and second coaxial shafts extending from the motor section, the second shaft being a rotary shaft and a gear reduction section adjacent to the motor section, the gear reduction section including a pinion at the end of the rotary shaft, a plurality of planet gears rotatably mounted to the housing in meshing engagement with the pinion and a third shaft connected to the motor housing, all of the shafts being separate but coaxial. A hub having an interior surface closely surrounds the motor and gear reduction sections and is rotatably coupled to the first and third shafts. A ring gear formed in the interior surface of the hub is in meshing engagement with the planet gears so that when the second shaft rotates at a selected speed, the hub rotates relative to the first and third shafts at a lesser speed. Preferably, the hub is at least partially filled with oil to conduct heat from the motor section to the outside.

Abstract: A passively cooled electromechanical actuator is disclosed. The passively cooled electromechanical actuator includes a rotor having an output shaft rotatably received within a stator. A pair of inner supports connect the stator to a pair of mounting platforms. The mounting platforms are attached to the inner surfaces of an aircraft wing and are in thermal communication therewith. A pair of closed, capillary tube thermosyphons containing a working fluid are in thermal communication with the stator, the inner supports and the mounting platforms. During operation, the thermosyphons receive heat from the stator and transport it to the mounting platforms whereupon it is convected or radiated to the atmosphere from the aircraft wings. The inner supports have a phase change material received within for providing temporary thermal energy storage during transient conditions.

Abstract: A rotating machine having a core and being equipped with coolers for cooling a cooling medium which is circulated inside the machine by the rotation of a fan installed near the rotating axis. The coolers are installed in a ventilation passage for the cooling medium and comprise a primary cooler installed in a primary ventilation passage extending from the exhaust side of a fan installed near the rotating axis to the suction side of said fan via the core, and a secondary cooler installed in a secondary passage that is branched from the primary ventilation passage.

Abstract: A permanent magnet electrical rotating machine wherein the slots of stator core 2A of stator 1A are rectangular enclosed slots 4A in which triangular projecting gaps 3a are formed on the inner periphery side of this stator core 2A. The stator core 2A is cooled by passing gas through the projecting gaps 3a. The magnet flux that reaches stator core 2A from permanent magnets 6 by passing through retaining ring 8 and air gap 9 is caused to pass the inner periphery sides of the projecting gaps a of the stator core 2A. By this means, oscillation of magnetic flux density in the peripheral direction is prevented, eddy currents in the retaining ring 8 which accompany this oscillation are reduced and temperature rise prevented.

Abstract: A rotating machine equipped with coolers for cooling a cooling medium which is circulated inside the machine by the rotation of a fan installed on the rotating axis. The coolers includes two or more coolers installed in a ventilation passage for the cooling medium. At least part of the cooling medium cooled by one cooler is further cooled by another cooler.

Abstract: A rotating machine having a stator core and being equipped with coolers for cooling a cooling medium which is circulated inside the machine by the rotation of a fan installed near the rotating axis. The coolers are installed in a ventilation passage for the cooling medium and comprise a primary cooler installed in a primary ventilation passage extending from the exhaust side of a fan installed near the rotating axis to the suction side of the fan via the stator core, and a secondary cooler installed in a secondary ventilation passage extending from the exhaust side of the fan in the primary ventilation passage to the inside of the inner surface of the stator core via the stator core.

Abstract: An apparatus (10) and method for applying air to cool an electrical power generator (15) is provided. The apparatus (10) preferably includes a housing (12), a power generator (15) positioned in the housing (12), and a heat transfer device (20) positioned within the housing (12) and adjacent and in fluid communication with air contacting the power generator (15) for receiving relatively hot air from the electrical power generator (15), transferringly cooling the relatively hot air with relatively cooler air received from outside the housing (12) without allowing the relatively hot air to contact and mix with the relatively cooler air, and supplying cooled air from within the housing (12) to the power generator (15).

Abstract: A stator structure enables a claw pole motor to be reduced in diameter and to highly increase its performance.

Abstract: In order to assure efficient cooling and a temperature balance between the stator and the rotor, an asynchronous electric motor is provided containing a closed cooling liquid circuit which passes successively into the stator (1) and into the shaft (3) of the rotor, over the entire length of the stator and the rotor. A pump (15) is incorporated in the rotor shaft. The liquid is injected into the pump by a stationary axial tube (16) and comes out again between the shaft and this tube. The pump includes a centrifugal pumping member (20) fixed to the bottom of the bore of the shaft, and longitudinal-blades (21) fixed to the shaft facing an external helicoid rib (17) of the injection tube. The liquid is cooled by the ambient air along the periphery of the stator.

Abstract: An outboard motor comprises an engine contained within an engine compartment formed within a power head of the motor. The engine includes a generator having a stator and a rotor. The stator is cooled by a cooling component to reduce the operating temperature of the stator. The cooling component generally comprises a heat transfer plate or cooling jacket that is positioned adjacent to at least a portion of the stator to usher heat build-up away from the stator portion of the generator. The cooling jacket may be in fluid communication with other cooling jackets or may be a discrete system that is separate and distinct from other cooling systems of the motor.

Abstract: An in-line generator fits between the engine and transmission of a conventional motor vehicle. The in-line generator comprises an externally cooled housing having a first end that is mounted to the engine in place of the transmission. The transmission is secured to the housing second end in the same manner as the transmission would normally be secured to the engine. One end of a rotor is fastened to the engine crankshaft. A coupling is attached to the rotor second end and to the transmission input shaft. When the engine is operated, the rotor rotates to cooperate with a stator in the housing to produce electric power. The rotor also transmits torque to the transmission to propel the motor vehicle. The coupling includes a flex plate that accommodates thermal expansion of the rotor and other generator parts. The in-line generator can be removed from the vehicle and the transmission resecured to the engine as in a normal vehicle should the in-line generator require repair.

Abstract: In a motor having a cylindrical stator fixed to a motor housing and inner and outer rotors concentrically arranged to the stator, a cooling structure of the motor includes cooling jackets formed in the stator. Coolant inlet and outlet ports are provided at an axial end of the rotor which end is opposite to an output end portion of the outer rotor. The coolant inlet and outlet ports are connected to the cooling jackets to supply and discharge coolant to and from the cooling jackets. A coolant return portion is provided at the other axial end of the rotor and connects each pair of the cooling jackets.

Abstract: A motorized wheel hub assembly includes a sealed motor section having first and second coaxial shafts extending from the motor section, the second shaft being a rotary shaft and a gear reduction section adjacent to the motor section, the gear reduction section including a pinion at the end of the rotary shaft, a plurality of planet gears rotatably mounted to the housing in meshing engagement with the pinion and a third shaft connected to the motor housing, all of the shafts being separate but coaxial. A hub having an interior surface closely surrounds the motor and gear reduction sections and is rotatably coupled to the first and third shafts. A ring gear formed in the interior surface of the hub is in meshing engagement with the planet gears so that when the second shaft rotates at a selected speed, the hub rotates relative to the first and third shafts at a lesser speed. Preferably, the hub is partially filled with oil to conduct heat from the motor section to the outside.

Abstract: A motor cooling and sound absorbing system includes a housing (10) forming a chamber (13) around a motor (11). The shaft (12) of the motor (11) carries a fan (40) positioned in a chamber (38) formed by a recess (36) cut in a foam block (35). The fan (40) draws air into the chamber (13) through inlet apertures (33) in the housing (10) and this air is directed past the motor (11) to cool it. The air exits the fan (40) generally radially against an angled surface (37) of the recess (36) of the foam block (35). The air is then received in a diffuser passageway (41) defined by the angled surface (37) and an angled surface (42) of a choke plate (19) positioned above the foam block (35). The diffuser passageway (41) reduces the velocity of the air to assist the foam block (35) in absorbing the noise generated thereby, while at the same time reducing the pressure at the exit of the fan (40) to increase the cooling air flow past the motor (11).

Abstract: A conduit for providing air flow from an air conditioning housing to a motor for driving a climate control system air blower is disclosed. The blower is located in the air conditioning housing. The air conditioning motor includes a motor housing inlet port for admitting the air flow to the interior of the motor. The conduit comprises a generally cylindrical hose member having a motor housing end and a blower housing end. The blower housing end of the conduit extends through the blower housing wall and into the blower housing and defines a generally cylindrical wall. The generally cylindrical wall includes an angled portion and a stop wall portion opposite the angled portion which cooperate to guide air through the conduit to the motor.

Abstract: A fanless salient pole DEM is provided with annular shrouds fitted to the stator ends in close juxtaposition to the rotor to isolate the rotor from atmospheric pressure during operation of the DEM.

Abstract: In a gas-cooled electrical machine, the conductor bars (3, 4) in the winding overhang are cooled directly by a flow element of the cooling gas flow which is passed through cooling channels (8) located within the eyes (5a, 5b) of the bar ends. To this end, the bar levels of the winding bars, which are designed as a two-level bar, are spaced apart from one another in the eye region, and thus form a radial cooling channel (8). These radial cooling channels (8) are coupled to the discharge eyes (5b) by pipe connections (10) which are connected electrically, and in terms of the flow, to round connections (20). The cooling channels (9) in the round connections (20) are connected by means of insulating tubes (31) or insulating hoses to an induction area (32) of the machine fan, which is separated from the winding overhang area (30) by a bulkhead wall (33). The invention allows the bar ends and the round connections (20) connected to them in the winding overhang to be cooled optimally, since the cooling is direct.

Abstract: A cooling loop structure of high speed spindle comprises three groups of cooling areas where the first group being the front bearing cooling area, the second group being the motor cooling area and the third group being the rear bearing cooling area. Cooling fluid from the cooling machine outlet, flows through the rear end of spindle into the front bearing cooling area, then flows into the motor cooling area, finally, after flowing into the rear bearing cooling area, it flows back into the inlet of cooling machine, thereby, forms a temperature-controlled cooling loop. The cooling loop needs only a setup of cooling fluid inlet and outlet at the rear end of spindle which can avoid being using too many exposed cooling pipes that result in space occupation and being inconvenient in the installation of spindle.

Abstract: Hydrogen coolers are provided with a cooler frame; cooling tubes positioned within the cooler frame; a tube bundle: an inlet chamber adjacent to an inlet end of the tube bundle; a reverse chamber adjacent to the reverse end of the tube bundle; and a support bracket adapted to be mounted on a frame of an electric generator. The support bracket defines an opening sized to receive inlet and outlet connections to the inlet chamber. The support bracket includes a shoulder for supporting the inlet chamber. This invention also encompasses the method of assembling these coolers in an electric generator.

Abstract: A stator for a dynamoelectric machine includes a stator frame including a main frame and axial ribs cylindrically arranged in the main frame to extend parallel with an axis of rotation of a rotor such that a space is defined. The main frame includes a bottom wall, side walls standing from both radial ends of the bottom wall respectively, and connecting walls standing from both axial ends of the bottom wall and interconnecting both ends of the side walls, respectively. Each axial rib has opposite ends connected to the respective connecting walls and an intermediate portion between the ends. The intermediate portion of each axial rib is spaced away from the side walls. A stator core is formed of a stack of laminations of steel sheets and fitted in the space defined by the axial ribs to be held in position.

Abstract: A reluctance motor/generator apparatus capable of operation at high rates of revolu-tion and high energy densities with reduced cooling-related windage losses and without incurring thermal damage to motor/generator elements. The apparatus includes an electrical winding-free reluctance rotor having a plurality of windage controlling and heat dissipating divider or barrier elements (which are also referred-to as thermal elements in the descriptions) disposed at opposite ends and periodically along its axial length to definite a plurality of rotor cooling chamber areas. The divider or barrier elements are provided with cooling fluid limiting apertures selected in size to optimize a relationship between rotor cooling effectiveness and windage energy losses. The machine stator is provided with cooling fluid release apertures of predetermined position and size relationship with the rotor cooling chamber areas. Use of the disclosed apparatus in the aircraft dynamoelectric machine environment is also disclosed.