Abstract: An electric motor assembly including a stator having a stator core and windings around the stator core is disclosed. The stator core has opposing ends and an outer surface extending between the opposing ends. The electric motor assembly also includes a housing having an inner surface enclosing at least a portion of the stator, and at least one fluid passage between the outer surface of the stator core and the inner surface of the housing. The fluid passage permits a coolant in the fluid passage to contact one or more portions of the outer surface of the stator core to remove heat from the stator core during operation of the electric motor assembly. Additional motor assemblies including stator and/or rotor cooling features are disclosed.

Abstract: A rotor for a reluctance motor includes a laminated core having a number of rotor sheet metal blanks. Each rotor sheet metal blank includes flux barriers cast with a non-ferromagnetic casting compound and at least one soft-magnetic rotor sheet which delimits the flux barriers. Flux barriers of adjacent rotor sheet metal blanks are arranged offset relative to one another so that the flux barriers of one of the adjacent rotor sheet metal blanks are delimited in an axial direction at least partially by the rotor sheets of the other one of the adjacent rotor sheet metal blanks, with the casting compound of the flux barriers adhering in an adhesion zone to the rotor sheets.

Abstract: A rotor related to the present invention is for a rotary electric machine. The rotor includes a rotor core and magnets. The rotor core has a plurality of core refrigerant passages. The core refrigerant passage each includes an inlet passage, a magnet cooling passage and an outlet passage. The inlet passage is configured such that a liquid refrigerant flows into the inlet passage from a shaft refrigerant passage. The magnet cooling passage is configured such that the liquid refrigerant flows into the magnet cooling passage from the inlet passage. The magnet cooling passage extends in an axial direction. The outlet passage is configured to flow the liquid refrigerant from the magnet cooling passage to a gap. An axial position of the outlet passage in the rotor core is at one place at a central position in the axial direction.

Abstract: A water-cooling device includes a main body having a pump chamber and a heat exchange chamber, which are partitioned from each other by a water room partitioning board. The water room partitioning board has a communication section for communicating the pump chamber with the heat exchange chamber. A pump unit is disposed in the pump chamber. A heat transfer unit is disposed in the heat exchange chamber. A cooling fluid is filled up in the pump chamber and the heat exchange chamber. The water-cooling device has greatly enhanced heat dissipation performance. Moreover, the water-cooling device is free from the problem of overheating of the stator assembly in operation.

Abstract: An electric motor/generator includes a rotor with magnets mounted on the surface of the rotor, the magnets facing the stator over a gap. The magnets have a very high flux density but a limited ability to withstand high stator currents at high temperatures, preferably magnets made of the N48H material. By providing rotor magnet cooling means that reduces the temperature of the magnets by a cooling fluid, use of magnets with lower maximum working temperature and higher flux density is permitted and thereby higher flux can be obtained from the magnets.

Abstract: A method and apparatus for determining a characteristic of an injector are set forth. In one example, a compressed gas is applied to the inlet chamber of the injector while the spoolvalve is closed until the pressure of the compressed gas in the inlet chamber reaches a predetermined pressure. A change in pressure of the compressed gas in the inlet chamber is measured over time while the spool valve is closed. The pressure change measurement corresponds to the characteristic of the injector that is to be determined.

Abstract: A water-cooling module includes a main body. The main body has a receiving space and a water room partitioning board. The receiving space is partitioned by the water room partitioning board into a pump chamber and a heat exchange chamber. The pump chamber and the heat exchange chamber communicate with each other through at least one communication section. A pump unit is disposed in the pump chamber. A heat transfer unit is disposed in the heat exchange chamber. A cooling fluid is filled up in the main body to circulate within the pump chamber and the heat exchange chamber. The pump unit is entirely immersed in the cooling fluid so that the operation efficiency of the pump unit is enhanced and the main body is thinned. Moreover, the problem of overheating of the pump unit in operation is solved.

Abstract: A rotating electrical machine is configured such that, in a rotor coil, ventilation passages are formed in two lines arranged in a width direction of the rotor coil, and formed in the same shape at a plurality of positions spaced from each other in a longitudinal direction, 0.3?W1/W2?0.7 . . . (Expression 1) is satisfied, where (W1) is a width dimension of the ventilation passage in the longitudinal direction and (W2) is a width dimension from one end of the ventilation passage to one end of another ventilation passage adjacent thereto, and 0.025?W4/W3?0.08 . . . (Expression 2) is satisfied, where (W3) is a width dimension of the rotor coil and (W4) is a width dimension of the ventilation passage.

Abstract: An airflow control arrangement for a direct-drive wind-turbine with a generator comprising a rotor and a stator, which airflow control arrangement comprises an outflow fan arranged to draw an exit airflow through an exit duct, which exit duct extends from an interior cavity of the stator to the exterior of the wind turbine. The invention further describes a direct-drive wind turbine comprising such an airflow control arrangement. The invention further describes a method of controlling an airflow in a direct-drive wind-turbine with a generator comprising a rotor and a stator is provided.

Abstract: A rotating electric machine (1) having a stator (4) in a housing (2) and a rotor (10) supported by a shaft (6). The housing (2) circumferential wall (12) and first and second axially opposing end walls (14, 16) support bearing flanges with bearings (18) for the shaft (6). Two cooling fan impellers (20, 22) are connected to the shaft (6). An inner cooling fan impeller (20) positioned inside the housing (2) generates an inner cooling air circuit (A) inside the housing (2). An outer cooling fan impeller (22) provided outside the housing (2), generates an outer cooling air flow (B). The first end wall (14) is formed with a thermal conductivity of at least a specified value and has an outer cooling rib geometry (28) on its outer side facing the outer cooling fan impeller (22), and an inner cooling rib geometry (30) on its opposing inner side.

Abstract: An electromagnetic actuator including: a core comprising a material having a high magnetic permeability relative to air; an array of coils sequentially arranged on the core, each coil of the array of coils being wound around the longitudinal axis of the core; and a magnet assembly movably mounted along the array of coils, the magnet assembly having a coil side facing the array of coils and an opposite side facing away from the array of coils and including an array of permanent magnets sequentially arranged along the array of coils in a direction parallel to the longitudinal axis, wherein the magnetic moments of the plurality of magnets are selected and arranged to augment the magnetic field produced on the coil side of the magnet assembly and to reduce the magnetic field produced on the opposite side of the magnet assembly.

Abstract: The rotor for an electric machine comprises a shaft, a spider on the shaft, a laminated drum on the spider. The spider has a plurality of apart elements defining ducts between each other. The laminated drum has a plurality of cooling channels connected to the ducts. The rotor also has throttle elements associated to at least one duct and/or cooling channel.

Abstract: A rotary electric machine according to the present invention includes a stator including a stator core and stator coils, a rotor provided rotatably with a gap to the stator, a housing that stores the stator and the rotor, a fan that circulates air inside the housing through the gap in the housing, a heat exchanger that cools the air circulated by the fan, and an air guiding plate including an air guiding route formed therein for guiding the air cooled by the heat exchanger such that the cooled air flows into the gap without coming into contact with the stator coils.

Abstract: An electric motor cooling system is provided in which at least one heat pipe is captured within at least one hollow region within the motor's rotor shaft. An end of the heat pipe that extends out and away from the end of the rotor shaft is coupled to a heat exchanger, for example a heat sink in which the fins of the heat sink are shaped as fan blades. During motor operation, as the rotor heats up thermal energy is absorbed by the heat pipe within the rotor shaft and transferred to the heat sink for efficient removal.

Abstract: A superconducting electrical machine includes a rotor with a rotor outer housing surrounding a winding support having a superconducting winding. The rotor has on a torque-transmitting side a first, rigid connection device between the winding support and the rotor outer housing and on the opposite side a second connection device which compensates for axial expansion of the winding support. The second connection device has an axially extending connection element which is on one end connected rigidly to the winding support and which has on the opposite free end an axially moving, radially force-fitting connection to a centering holding element of the rotor outer housing. The holding element includes a bushing through the rotor outer housing, through which the free end of the connection element of the second connection device passes. The superconducting winding is cooled and thermally insulated.

Abstract: A cooling system for an electric machine is provided. The cooling system includes an airflow restriction feature configured to provide airflow to a radial air channel of the electric machine.

Abstract: A centrifugal heat dissipation device and a motor using same are disclosed. The centrifugal heat dissipation device includes a main body having a shaft hole, a heat-absorption zone and a heat-transfer zone. The heat-transfer zone has a radially outer side connected to the heat-absorption zone and a radially inner side connected to the shaft hole. The shaft hole axially extends through the main body for receiving a shaft of a motor therein. A centrifugal force generated by the rotating shaft and accordingly, the heat dissipation device enables enhanced vapor-liquid circulation of a working fluid in the heat dissipation device, so that heat generated by the operating motor is absorbed by the centrifugal heat dissipation device and transferred to the shaft for guiding out of the motor, allowing the motor to have largely upgraded heat dissipation performance.

Abstract: A rotor for an electric motor includes a metal core, a plurality of electrical conductors arranged on the metal core, and a metallic corrosion protection layer enveloping the metal core and the plurality of conductors. The corrosion protection layer is laid as a solid body around the metal core and the conductors and fastened at least to the metal core. The corrosion protection layer is at least a part of a hot-pressing containment for isostatic pressing of the conductors in the metal core.

Abstract: A rotating electrical machine includes a rotor which has a rotor core formed by stacking magnetic plates having an annular plate shape in an axial direction, a permanent magnet is inserted into a magnet insertion hole formed in the rotor core, and a rotor shaft is inserted into a shaft insertion hole surrounded by an inner peripheral surface of the rotor core; and a stator. A radial communication passage is formed by a communication penetration hole group that is formed by sequentially communicating a plurality of the penetration holes from a shaft insertion hole to a magnetic resistance hole in the radial direction. The plurality of the penetration holes are divided into at least two specific magnetic plates and formed such that the radial positions of the penetration holes are different from each other and the penetration holes partially overlap each other when viewed in the axial direction.

Abstract: Vent spacers and induction motor rotor core assemblies for induction motors are disclosed. The induction motor rotor assembly includes at least two rotor packages, each having axial sidewalls, a radial periphery, and axial vents, and a vent spacer positioned between opposing axial sidewalls of the at least two rotor packages. The vent spacer has a hub and a plurality of radially-extending fins coupled to the hub, the fins extending approximately to a radial periphery and extending axially between the opposed axial sidewalls to form a plurality of radial cooling channels extending between the sidewalls. Induction motors and methods of operating the induction motors are disclosed, as are other aspects.

Abstract: An electric motor includes a stator operable to produce a magnetic field and defining an opening, and a rotor at least partially disposed within the opening. The rotor includes a shaft extending along a rotational axis, a plurality of first core portions each including a plurality of laminations stacked contiguously on the shaft, and a second core portion coupled between each of the first core portions. The first core portions and the second core portion cooperating to define a rotor magnetic core. A plurality of windings is coupled to the rotor magnetic core, and an air flow path is partially defined by the first core portions, the second core portion, and the shaft. The air flow path includes an axial portion that passes through the shaft axially along the rotational axis and a radial portion that extends radially outward through the second core portion.

Abstract: The present invention relates to an open rotary electric machine having a rotor mounted to rotate relative to at least one stator and co-operating with the stator to define at least one airgap, the rotor being suitable for rotating at least one fan having at least two channels, said fan including a first channel generating a first cooling air stream passing through the stator, and a second channel generating a second cooling air stream passing through the rotor, the fan including a solid web separating the first and second air streams.

Abstract: An electric machine includes a stator, a rotor interacting magnetically with the stator, a housing surrounding the stator and rotor, and a hollow shaft provided for arrangement of the rotor and mounted on the housing. A radial fan is mounted rotationally fixed on the hollow shaft on the ventilation side. A section of a fan blade of the radial fan extends axially away from the housing to a greater extent than the hollow shaft. A guide element with radially extending plate is arranged in the hollow shaft, wherein the plate is arranged axially further away from the housing than the end side of the hollow shaft on the ventilation side. An inner coolant flow can thus be delivered from the section of the fan blade out of the hollow shaft through a passage between the end side of the hollow shaft on the ventilation side and the plate radially outwards.

Abstract: A liquid-cooled, radial air gap electric motor includes a stator, a rotor, a rotor shaft, two end bells, a housing, a coolant manifold system, and a coolant sump. The rotor includes a plurality of axially directed slots located near its periphery. The coolant manifold system directs a first portion of liquid coolant to flow past some portion of the stator and a second portion of liquid coolant to flow through the rotor slots. Some or all of the liquid coolant is received by the coolant sump from which the coolant may be recirculated.

Abstract: An electric motor assembly including a stator having a stator core and windings around the stator core is disclosed. The stator core has opposing ends and an outer surface extending between the opposing ends. The electric motor assembly also includes a housing having an inner surface enclosing at least a portion of the stator, and at least one fluid passage between the outer surface of the stator core and the inner surface of the housing. The fluid passage permits a coolant in the fluid passage to contact one or more portions of the outer surface of the stator core to remove heat from the stator core during operation of the electric motor assembly. Additional motor assemblies including stator and/or rotor cooling features are disclosed.

Abstract: An electrical machine rotor includes a flux-conducting portion and a flux-inhibiting portion. The flux-conducting portion is conducive to conveying an electromagnetic flux and has a plurality of salient rotor poles and a portion of back material. The flux-inhibiting portion is less conducive to conveying an electromagnetic flux than the flux-conducting portion and is disposed entirely outside the boundaries of the rotor poles.

Abstract: A motor includes: a shaft to which a rotor is attached and having an internal cooling medium passage in an inside of the shaft, a cooling medium passing through the internal cooling medium passage; a housing including the shaft disposed therein and configured to rotatably support the shaft; and a cooling medium reservoir provided in the housing and provided on an upstream side of an inlet of the internal cooling medium passage in a flowing direction of the cooling medium, the cooling medium reservoir being configured to store the cooling medium and then flow the cooling medium to the internal cooling medium passage.

Abstract: On an inner circumference side of a stator fixed in an inner housing, a rotor is arranged. The rotor rotates through a bearing with respect to a center shaft that is a stationary shaft fixed to outer housings. Oil introduced into a rotor oil inlet path in the center shaft flows through a communication path and a clearance on an outer circumference of the center shaft into an oil path in the rotor. The oil flowing through the oil path cools a permanent magnet, lubricates the bearing, and is discharged from a rotor oil discharge port to the outside of the inner housing. The oil in the clearance is sealed with a thread seal, i.e., an inner thread formed in an inner face of an end ring and is prevented from flowing toward the bearing.

Abstract: A motor driven assembly includes a motor having a motor inlet and a motor outlet, a shaft, and a rotor spaced radially outwards from the shaft. A cooling flow passage is located between the shaft and the rotor. The cooling flow passage fluidly connects the motor inlet and the motor outlet. A compressor is in fluid communication with the motor outlet. The compressor includes a compressor outlet that is in fluid communication with the motor inlet.

Abstract: An electric motor coupled to a driven device of a vehicle. The electric motor includes a rotor and a shaft coupled to the rotor. The rotor has at least one radially oriented cavity and at least one fluid channel. The fluid channel extends in a generally axial direction. The fluid channel is fluidly connected to the at least one radially oriented cavity. The shaft has a fluid passageway therein. The at least one radially oriented cavity has a fluid connection to the fluid passageway of the shaft. The at least one radially oriented cavity leads to a radial exit from the rotor for a flow of fluid therefrom.

Abstract: A fan includes an air movement implement including a blade and a motor that drives the air movement implement. The motor includes a rotor that includes an internal diameter heat exchanger and a heat pipe having a first end and a second end, the first end in thermal contact with the internal diameter heat exchanger and the second end in thermal contact with the blade.

Abstract: A rotor for a turbo generator is provided. The rotor includes a cylindrical rotor shaft that expands in the center to form a rotor body, grooves introduced into the cylindrical surface of the rotor body, an excitation winding accommodated in the grooves, a feeding duct through which a cooling gas flows, and cooling ducts which penetrate the excitation winding substantially in the radial direction and connect the feeding duct to respective outlets in the cylindrical surface of the rotor body A distribution duct extending in the longitudinal direction of the shaft is arranged in the area of the central longitudinal axis. The feeding ducts are connected to the distribution duct via junction ducts. An admission duct for feeding the cooling gas is provided for each distribution duct.

Abstract: In an electric motor 11, a rotary shaft 12 has an outer circumferential surface 21 with a diameter that decreases from a larger diameter section 17 having a first diameter toward a smaller diameter section 18 having a second diameter smaller than the first diameter. A sleeve 13 is mounted by interference fit with an inner circumferential surface 22 with a diameter that decrease from a front end adjoining the larger diameter section 17 toward a rear end adjoining the smaller diameter section 18, to the outer circumferential surface 21 of the rotary shaft 12. With such a construction, the sleeve 13 is fitted with the substantially entire surface of the inner circumferential surface 22 to the outer circumferential surface 21 of the rotary shaft 12.

Abstract: A superconducting rotating machine having a cooler for a rotator is provided. The superconducting rotating machine includes a rotator wound with a superconducting coil, a stator enclosing the rotator and separated therefrom by a predetermined gap, the cooler having a cold head directly attached to the rotator and at least one compressor connected with the cold head, and a flexible coupling disposed between the cold head and the compressor and enabling a cryogenic refrigerant to flow therein. The cold head is directly connected to the rotator, and the cold head and the compressor are driven using the flexible coupling, so that it is possible to prevent vibration of the compressor and enhance cooling efficiency by thermally separating the cryogenic cold head from the compressor.

Abstract: An electrical machine has passages in the rotor. The passages have an inlet port and an exit port disposed at different locations. The passages remove heat from the electrical machine during operation. Another embodiment is an electrical machine rotor. The rotor has passages that remove heat from an electrical machine during operation. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for electrical machines and the cooling of electrical machine rotors and/or stators.

Abstract: A generator motor cooling structure for cooling a generator motor, which includes a housing storing an input/output shaft to which a rotor is attached and a stator disposed at an outer periphery portion of the rotor, by a cooling medium, includes: a protrusion portion that protrudes toward the rotor from a surface at a side of the housing of an end side member disposed at one end portion of the housing in a direction of a central rotation axis of the input/output shaft, wherein the protrusion portion is provided on an inner side of a coil of the stator in a radial direction, on an outer side of a bearing attached to the input/output shaft in the radial direction, in at least a partial region on a periphery of the central rotation axis.

Abstract: A cooling structure of a generator motor includes: a rotor holder; a rotor core; a first blade; and a second blade, wherein the second blade includes a recessed coolant holding portion, provided on an outer circumference of the second blade on an opposite side to the rotor core and opening inward in the radial direction, for collecting a coolant, and a drain hole radially penetrating an outer circumference of the coolant holding portion for draining the coolant collected in the coolant holding portion.

Abstract: A centrifugal heat dissipation device and a motor using same are disclosed. The centrifugal heat dissipation device includes a main body having a shaft hole, a heat-absorption zone and a heat-transfer zone. The heat-transfer zone has a radially outer side connected to the heat-absorption zone and a radially inner side connected to the shaft hole. The shaft hole axially extends through the main body for receiving a shaft of a motor therein. A centrifugal force generated by the rotating shaft and accordingly, the heat dissipation device enables enhanced vapor-liquid circulation of a working fluid in the heat dissipation device, so that heat generated by the operating motor is absorbed by the centrifugal heat dissipation device and transferred to the shaft for guiding out of the motor, allowing the motor to have largely upgraded heat dissipation performance.

Abstract: The electrical connection of a sealed electrical machine is provided and includes a casing containing lead conductors each connected to a bushing via an electrical connector. The casing has at least an inlet and an outlet for a cooling fluid. The electrical connector includes at least a permeable element defining a chamber such that during operation the cooling fluid, passing through the chamber and the permeable element, cools the permeable element. A method is also provided for cooling an electrical connection.

Abstract: An electric machine includes a casing have a first end plate and a second end plate, the first end plate having an air inlet and the second end plate having an air outlet; an outer rotor positioned inside the casing; a stator positioned inside the outer rotor; a hub positioned inside the stator; a fan positioned within the casing, the fan drawing air from the air inlet and exhausting air out the air outlet.

Abstract: The coolant supplying and collecting apparatus is inserted along an inner diameter of a rotary shaft of a motor. The apparatus includes a first body section having a hole section formed at one side thereof, and a second body section inserted into and fixed to the first body section. The apparatus is configured to provide a moving path of a fluid along an inner diameter thereof. A channel section is formed between an inner circumferential surface of the first body section and an outer circumferential surface of the second body section and extends in a longitudinal direction to provide a moving path of the fluid in the hole section direction.

Abstract: An electric motor includes: a shaft having an internal cooling medium passageway; a cooling medium supply portion provided inside a housing at a side of one end of the shaft and supplying a cooling medium to the internal cooling medium passageway; a rotation angle detection sensor attached at the side of the one end of the shaft and detecting a rotation angle of the shaft; a push member including a penetration hole through which the cooling medium supplied from the cooling medium supply portion passes and interposed between the cooling medium supply portion and the one end of the shaft to guide the cooling medium to the internal cooling medium passageway and pressing the rotation angle detection sensor from the side of the one end of the shaft; and a connector holding a terminal connected to a signal cable from the rotation angle detection sensor and attached to the housing.

Abstract: An induction motor includes a stator having a winding to be inserted to a plurality of stator slots formed along an inner circumferential edge of a stator iron core; and a rotor placed inside of the stator via a gap, the rotor includes a plurality of double squirrel-cage rotor slots formed along an outer circumferential edge of the rotor iron core and filled with conductive material and at least three air hole parts provided around a rotating shaft hole of the rotor iron core to which the rotating shaft is fitted and having an opening which is open to the rotating shaft hole; and an inner diameter part of the end ring which short circuits both edges of the conductive material filled to the double squirrel-cage rotor slot is placed to be adjacent to the air hole part in at least the end ring of one side.

Abstract: A motor driven assembly comprises a motor shaft, a rotor, a passage, and a corrugated fin heat transfer structure. The motor shaft is mounted for rotation about a rotational axis. The rotor is located radially about the shaft. The passage extends through the rotor alongside the motor shaft. The corrugated fin heat transfer structure is disposed within the passage radially aligned with the rotor.

Abstract: A wedge cooling apparatus and method for cooling a rotating machine, such as a generator, disperses a spray of cooling fluid into the wedges of the generator via a pipe that runs along the length of each of the wedges. The pipe may include a plurality of spray delivery devices to spray cooling fluid from the pipe to the inside of the wedges. The spray cooling method results in a high heat transfer coefficient of about 2000-3000 W/m2C as opposed to conventional conduction cooling, which has a heat transfer coefficient of about 200-300 W/m2C. The apparatus and method of the present invention efficiently removes heat from high powered, high current density designed generators.

Abstract: In one possible implementation, a motor is provided including a rotor and a stator. Front cooling fins are thermally coupled to a front of the stator, and rear cooling fins are thermally coupled to a rear portion of the stator. The winding is between the front and rear cooling fins.

Abstract: A shaft cooler (1) for a tool motor spindle (2), which has a rotating shaft (3), a static lance (4), and at least one coolant loop (7), which comprises a coolant inlet (5) and a coolant outlet (6), said shaft cooler being implemented such that the flow of the coolant from the static lance (4) into the rotating shaft (3) is performed via a flow path that includes radially-extending cooling holes (31) to cause the coolant to flow from a radially inside location to a radially outside location.

Abstract: A synchronous reluctance machine includes a rotor having a plurality of rotor disks with longitudinal flux barriers. When the rotor disks are stacked together to form a rotor core, the flux barriers define channels extending in an axial direction of the rotor core. Air is forced to flow through these channels in order to improve a temperature distribution within the machine.

Abstract: In a rotating electrical machine configured with a rotor and stator, a lubricant supply portion is configured to supply a lubricant from within. A communication passage is provided in either the rotor support member or the sensor rotor, and is configured so as to provide a passage from a first space, which extends radially outward from the axial first direction side of the sensor rotor and is formed between the support wall and the rotor support member, with a second space, which is formed between the sensor rotor and the rotor support member. The case of the machine has a support wall extending at least in a radial direction to an axial first direction side, which is one side in an axial direction of the rotating electrical machine, and after lubricating the bearing, the lubricant is discharged from the second space to the first space through the communication passage.

Abstract: Embodiments of the invention provide an electric machine module including a housing defining a machine cavity. In some embodiments, an electric machine can be positioned within the machine cavity and include a rotor hub coupled to rotor laminations. The rotor hub can include first and second axial ends and the rotor laminations can include a recess. In some embodiments, the recesses can be aligned to define a portion of a plurality of coolant channels that can be in fluid communication with the machine cavity. In some embodiments, the rotor hub can include first and second rotor hub inlets in fluid communication with at least a portion of the coolant channels. The first and the second rotor hub inlets can be adjacent to the axial ends of the rotor hub. In some embodiments, the coolant channels are in fluid communication with the rotor hub inlets are not the same coolant channels.