Abstract: According to one embodiment, an electric motor includes a stator, a rotor, bearings and a rotor shaft, in a frame, supporting surfaces on the rotor, and a plurality of threaded holes in the frame, which are configured to receive bolts for pressing the support surfaces from outside.

Abstract: A totally enclosed fan cooled (TEFC) induction motor or other type of induction motor auxiliary cooling system has a buffet thermal shroud that is oriented in opposed spaced relationship over existing motor housing cooling fins. An airflow channel is defined between the motor cooling fins and the shroud, for direction and passage of a cooling airflow. Tabs are oriented in the airflow channel between opposed cooling fins where they are in thermal and fluid communication with the cooling air flow. In some embodiments the tabs are shroud fingers that project inwardly from the shroud. The tabs or shroud fingers create turbulence in the cooling air flow that increases convective heat transfer efficiency and contact time between the cooling air and motor cooling fins. Tabs or shroud fingers also absorb heat from the cooling air flow. Shroud fingers also transfer that absorbed heat conductively to the shroud.

Abstract: A cooling fan is provided at an axial end portion of a rotor. The cooling fan generates a cooling air when rotated integrally with the rotor. On a stator core arranged at a position on a radially outer side of the rotor, a plurality of stator coils are arrayed in a circumferential direction of the stator core. Each stator coil includes a coil end that protrudes from an axial end surface of the stator core. A front housing covering the cooling fan includes: an exhaust port for passing the cooling air therethrough, at least part of the exhaust port being located at a position on a radially outer side of the coil end; and a recess portion opposed to the coil end in an axial direction.

Abstract: Described herein is a technology for an electric motor system that reduces stress in motor shaft bearings. Furthermore, the electric motor system that provides an adequate heat ventilation is described herein.

Abstract: An electric motor apparatus having an improved cooling system comprising a first compartment housing an electric motor mounted on a rotating shaft, a second compartment housing an electric circuit adapted to connect said electric motor to a power supply source, and a cooling system adapted to dissipate the heat generated by said electric motor apparatus. The cooling system comprises a fan mounted on said rotating shaft in a position adjacent to said second compartment and on the opposite side with respect to said first compartment and at least one finned heat exchanger adapted to dissipate the heat generated by said electric circuit inside said second compartment.

Abstract: A cooling system for bushings of an electric generator, which includes a casing housing a stator and a rotor connected to a rotor shaft activating at least a fan defining at least a high pressure zone and a low pressure zone. The generator has a plurality of phases electrically connected to hollow phase rings that are electrically connected to bushings supported by the casing and having cooling circuits to let a cooling medium pass through them to cool them. The outlets of the bushing cooling circuits are housed in the high pressure zone and are connected to inlets of the hollow phase rings. A method for cooling the bushings of an electric generator is also provided.

Abstract: A motor rotor system including: an axis of rotation, a rotor iron core mounted on the axis of rotation, a permanent magnet, a magnetic ring bracket, and a magnetic ring. The permanent magnet, the magnetic ring bracket, and the magnetic ring are mounted on the rotor iron core. The magnetic ring is sheathed on the magnetic ring bracket. The magnetic ring bracket is located at one end of the rotor iron core and connected with an end face of the rotor iron core. The motor rotor system has excellent batch-to-batch consistency, simple structure, and convenient installation. It is suitable for large batch production and can be controlled using sine-wave driving control methods with a position sensor.

Abstract: A rotor arrangement for an electric machine comprises a rotor shaft and a rotor segment coupled to the rotor shaft. The rotor segment includes a main body and a collar integral with the main body. The collar includes an outer peripheral groove adjacent to the main body portion of the rotor segment. The rotor arrangement further includes a cooling fan that has a center opening defined by an inner perimeter. The center opening of the fan is configured to slidably engage the collar and is adjustable between an insertion diameter and a locking diameter. When the center opening is at the locking diameter, at least a portion of the inner perimeter of the fan extends into the outer peripheral groove in the collar such that the fan is retained on the rotor segment.

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: According to the invention, an air compressor includes: one pair of air tanks arranged parallel to each other by being separated from each other in a constant interval, for storing thereinto compressed air; a compressing unit that compresses air sucked from an external space so as to supply the compressed air to the air tanks; and a motor coupled to the compressing unit so as to drive the compressing unit, while the motor and the compressing unit are arranged above the one pair of air tanks; wherein: a cooling fan that generates cooling wind is provided on one end of a rotation shaft of the motor; and a control circuit unit that drives the motor is arranged above the one pair of air tanks and at a position which is overlapped with an axial direction projection area of the cooling fan.

Abstract: A fan having an air guide and a flywheel is provided, the flywheel being attached to a shaft, for cooling an electric motor. The electric motor has a rotor which can be attached to the shaft. The air guide is arranged in an interchangeable manner at a position between the flywheel and the rotor with respect to the axial direction, and has an air guide opening with an inner cross section for the purpose of forming a blowing channel. An air flow generated by the flywheel can be guided through the blowing channel in the axial direction. The inner cross section is smaller than an outer cross section of the rotor.

Abstract: According to one embodiment, an electric motor includes a stator, a rotor, bearings and a rotor shaft, in a frame, supporting surfaces on the rotor, and a plurality of threaded holes in the frame, which are configured to receive bolts for pressing the support surfaces from outside.

Abstract: A blower for supplying and exiting the air to and from a treating chamber of a clothes dryer.

Abstract: A method and an arrangement for cooling an electric machine, including an electric machine and at least one blower connected to an axle of the electric machine for blowing a cooling agent into the electric machine or for sucking it from the electric machine, wherein the at least one blower is a side channel blower.

Abstract: A slinger shield structure is provided and includes a first annular disc, having a body, opposing faces defining an aperture extending through the body and through-holes extending through the body, which are arrayed around the aperture, a second annular disc having a body and opposing faces defining an aperture extending through the body, a hub for connection with the first and second annular discs at the respective apertures and radial vanes suspended between the first and second annular discs at a distance from the hub to define radial channels between adjacent radial vanes and drainage channels between the radial vanes and the hub.

Abstract: A high-pressure cleaning device has a housing which surrounds a motor pump unit which comprises a liquid-cooled electric motor and a pump. The pump has a suction inlet and a pressure outlet. Liquid, which is subsequently subjected to pressure by the pump, can be supplied to the electric motor for the purpose of cooling it. The electric motor is configured as a fan-less asynchronous motor and the motor pump unit is mounted via vibration-damping buffer elements.

Abstract: A motor having a first portion configured to turn in a forward direction, a second portion coaxially mirrors the first portion; and a central fan between the first and second portions, and forcing air through the portions. A thermoelectric cooler element, thermally coupled to the portion is configured to cool the motor. A motor controller is electrically coupled to the first and second portions, and operates a portion in response to a condition sensed by the motor controller. The condition sensed by the motor controller is a motor torque, a motor speed, a motor casing temperature, or a zoned motor casing temperature. A method includes detecting a motor operational command; selecting a motor operational state using motor portion responsive to the motor command; sensing a heating state of a motor portion; and providing a cooling state to the motor portion responsive to the heating state.

Abstract: A motor with an air-cooling structure having high cooling efficiency and capable of avoiding an increase in the size of the motor. A stator of the motor has an air flow channel being formed in the stator near outer circumferences of the slots. Air conveyed from a fan motor collides with an inner surface of an end at a spindle side of the stator, while cooling the slots through the air flow channel. The flowing direction of air which collides with the housing is inverted by a redirecting part, and the air is returned to the fan motor side while cooling the outside of the stator.

Abstract: A battery powered tool includes a housing containing a motor assembly. A fan positioned in the housing is rotated by the motor assembly. The fan has a circular ring/body and further has multiple fan blades directly connected to the circular ring body. The circular ring/body defines a concave shaped surface having the fan blades directly connected to the concave shaped surface. A housing cover includes: first and second extending walls; a slot created between the first and second extending walls; and multiple air intake vents all positioned in a lower housing zone separated from an upper housing zone by the slot. An electronics module is positioned in the housing proximate to the housing cover lower housing zone such that air entering the intake vents passes only through the lower housing zone and past the electronics module to cool the electronics module before entering the fan.

Abstract: A vehicle drive system configured with a dynamo within a case. The case is disposed on at least one axial side of the dynamo, and includes a wall portion overlapping the dynamo, which has a section that overlaps with the dynamo as viewed from the axial direction. The wall portion overlapping the dynamo includes a supply flow passage through which lubricating-cooling fluid flows, and which is formed with a first supply portion that supplies lubricating-cooling fluid to a rotor support bearing for the dynamo electric. The first supply portion includes a throttle portion whose flow passage cross-sectional area is small when compared to an upstream-side flow passage cross-sectional area in the flow direction of lubricating-cooling fluid. The supply flow passage includes a second supply portion that is a portion supplying lubricating-cooling fluid to the dynamo and higher than the first supply portion.

Abstract: An improved generator for using waterpower, wave-power or wind-power, comprising; a set of magnet plates and coil plates for mounting on a rotating shaft in parallel, the magnets installed on the magnet plates and the generating coils installed on the coil plates with constant-intervals in radial direction, a plurality of blades obliquely installed on circumference of the magnet plates and coil plates with mutually opposite direction, an inner annular cylinder and outer annular cylinder mounted on the coil plates to form annular container for inserting the magnets. A plurality of induction coils installed on the inner annular cylinder, a plurality of electromotive coils installed on the outer annular cylinder for proximately contact with ends of the magnets. The magnet plates and coil plates rotate in mutually opposite direction to enhance the quality of generation and repulsive force.

Abstract: A paper shredder motor cooling assembly having a paper shredder motor coupled to a fan shaft, an enclosure surrounding the paper shredder motor and having selected input and selected output vents to control airflow to the paper shredder motor, a fan coupled to the fan shaft, communicating with the selected input vents or the selected output vents; when the paper shredder motor is operating, the rotor shaft turns the fan to generate a differential air pressure between the selected input vents and the selected output vents, removing heat from the motor. A duty cycle of greater than 15 minutes is obtained. The fan can be coupled to the motor by speed increasing gearing, attached to the cutter blade assembly, such that the fan turns faster than the motor. The fan also can be attached to the motor shaft. An input fan and an output fan can be used.

Abstract: An object of the present invention is to provide an electrical rotating machine capable of securing safety against collision. Included are a rotor having a field winding and cooling fans, and a stator having a stator winding, arranged so as to surround the rotor. A bracket 1 is fixed to a load side end of the stator, and a heat sink is disposed inside the bracket. On the anti-load side of the heat sink, a field circuit unit and power circuit units for controlling the field winding and the stator winding, respectively, are mounted, whereas on the load side thereof, cooling fins are disposed. The anti-load side and lateral side of the field circuit unit and the power circuit units are surrounded by the bracket. Accordingly, a whole of the field circuit unit and the power circuit units is surrounded by the bracket and the heat sink.

Abstract: An electric drive motor for a work apparatus includes a stator having two stator poles which are at a distance from one another in the circumferential direction and have respective field windings. The motor has a rotor which rotates between the stator poles and the rotor shaft of the rotor drives a fan wheel. The cooling-air flow generated by the fan wheel enters the stator, flows therethrough and is discharged therefrom. For effective cooling, a pole intermediate space is provided between the stator poles; and, for the cooling-air flow, this space is filled by a non-magnetic guide body to provide a cooling duct delimited by the guide body and the field windings. The guide body is fastened to a support at one stator end and is inserted axially into the stator at the other end thereof.

Abstract: A totally enclosed fan cooled (TEFC) induction motor or other type of induction motor auxiliary cooling system has a buffet thermal shroud that is oriented in opposed spaced relationship over existing motor housing cooling fins. An airflow channel is defined between the motor cooling fins and the shroud, for direction and passage of a cooling airflow. Tabs are oriented in the airflow channel between opposed cooling fins where they are in thermal and fluid communication with the cooling air flow. In some embodiments the tabs are shroud fingers that project inwardly from the shroud. The tabs or shroud fingers create turbulence in the cooling air flow that increases convective heat transfer efficiency and contact time between the cooling air and motor cooling fins. Tabs or shroud fingers also absorb heat from the cooling air flow. Shroud fingers also transfer that absorbed heat conductively to the shroud.

Abstract: The present invention relates to an apparatus for generating power by a direct current supply brush that rotates with a field pole generator, the apparatus comprising: a field pole generator which has a plurality of iron cores having a coil or wire wound around; a winding wire used for power generation, the winding wire being formed in such a manner as to wind around the field pole generator; a commutator which is disposed at one end of the field pole generator and has a plurality of commutator segments arranged in a circular shape; a rotating body which has a direct current supply brush adhered to the outer surface of the commutator; a motor for rotating the rotating body; a slip ring secured to a shaft of the motor; and a direct current supply unit for supplying direct current power to the slip ring.

Abstract: An air-cooled generator may be provided with a centrifugal blower configured for rotation on a shaft of the generator. The centrifugal blower may have an axially oriented outlet. An impeller of the blower may have blades with trailing edges oriented at an angle between 80° to about 90° relative to an axis of the shaft of the generator.

Abstract: An electric motor has a stator and a rotor rotatably mounted in the stator. The rotor has a shaft and a fan mounted on the shaft. A air guide structure with an axial extension portion is arranged at one end of the stator adjacent the fan. The gap between the axial extension portion and the fan in the axial and/or radial direction of the motor is narrow in order to reduce air swirl generated by air flowing from the outlet of the fan to the inlet of the fan through the gap. Preferably, the width of the gap is larger than 0.05 mm and smaller than 2.0 mm. The cooling efficiency of the fan is increased and the performance of the motor is improved.

Abstract: An electric, permanent magnet motor (10) is described, where the motor comprises a motor housing (12) with a stator (14) and an internal rotating rotor (16) connected to a central shaft (24), as the rotor (16) is equipped externally with magnets (30) and the stator (14) is internally equipped with coils (32) and that during operation of the motor, the torque is transferred to the central shaft (24) for operation of external equipment.

Abstract: An electric motor including a housing; an output shaft stuck out from an end face of the housing; an air purge device having an inner circumferential surface and a mounting surface, the inner circumferential surface surrounding an outer circumferential surface of the output shaft, the mounting surface is mounted on the end face of the housing, the air purge device being configured to supply air to a clearance between the inner circumferential surface and the outer circumferential surface of the output shaft; and a fastening part fastening the air purge device to the end face of the housing in a detachable manner. The housing and the air purge device respectively having fitting parts at which the housing and the air purge device are fitted to each other when mounting the air purge device to the end face of the housing.

Abstract: According to one embodiment, an electric motor includes a stator, a rotor, bearings and a rotor shaft, in a frame, supporting surfaces on the rotor, and a plurality of threaded holes in the frame, which are configured to receive bolts for pressing the support surfaces from outside.

Abstract: An electric rotating machine including a rotor rotating relative to a stator, the rotor rotating a first fan placed at a first end of the stator, and a second fan placed at a second end of the stator opposite to the first end, the first and second fans being configured to generate an air flow from the first fan to the second fan through the rotor and the stator, the first fan comprising an external ring connecting the radial ends of blades together.

Abstract: A motor vehicle drive unit and an automotive vehicle comprising such a motor vehicle drive unit are provided. An electric motor has a rotor and a main stator rotatably mounted to a support structure. A first transmission provides an output to a first wheel axle shaft from the rotor. A second transmission provides an output to a second wheel axle shaft from the main stator. An auxiliary stator at least partially surrounds the main stator and is held stationary relative to the main rotatably mounted stator. A control unit is provided for controlling the auxiliary stator to add or subtract power to the main rotatably mounted stator.

Abstract: An electrical machine includes a stator, a rotor magnetically interacting with the stator, a shaft supported on the stator for rotation in a first direction of rotation and in a second direction of rotation which is opposite to the first direction of rotation, wherein the rotor is arranged on the shaft, a first axial fan mounted on the shaft on a side of the rotor for co-rotation with the shaft in the first direction of rotation and having freewheeling capability on the shaft in the second direction of rotation, and a second axial fan mounted on the shaft on the same side of the rotor as the first axial shaft for co-rotation with the shaft in the second direction of rotation and having freewheeling capability on the shaft in the first direction of rotation.

Abstract: Embodiments of the invention provide an electric machine module and a method for cooling an electric machine. The electric machine module includes the electric machine including a stator with stator end turns, a through bolt, and a housing with at least two removably-coupled frame members. Each of the at least two removably-coupled frame members include an inner wall, an outer wall, a coolant cavity defined between the inner wall and the outer wall, and a bolt channel. The coolant cavity can be positioned substantially around at least one of the stator end turns radially. The bolt channel can be positioned through a portion of each of the at least two removably-coupled frame members and can be located radially inward from an outer substantially circular periphery of the housing.

Abstract: A high speed electric motor for use in a variety of applications. The electric motor an electric motor including a motor housing or stator, a rotor having a commutator and brushes for contacting the commutator at a predefined area known as the contact area. Additionally, the motor includes a forced air cooling assembly. The forced air cooling assembly includes a centrifugal fan for creating air flow, a manifold for accelerating the air flow. The manifold having exit ports and the exit ports being positioned directly over the contact area for directing the accelerated air flow at the contact area and the motor housing having at least one opening aligned with the contact area and at least a second opening defining an exit vent. Additionally, a method of cooling the motor in accordance with the invention is also disclosed.

Abstract: To include a stator, a rotor that is arranged within the stator, a frame that encloses the stator and the rotor, a pair of bearings that respectively support a driving side and a driven side of a rotary shaft, and a fan that is mounted on the rotary shaft. A plurality of blades that extend in a radial direction of the rotor and are provided to stand at a substantially equal interval in a rotation direction of the rotor are formed in the fan. A cross section of each of the blades in a direction perpendicular to the rotor has an elliptical shape extending in the radial direction, and the cross section widens toward a side of the fan.

Abstract: The totally-enclosed fan-cooled motor includes the stator; the rotor; the drive side bracket; the counter drive side bracket; a pair of the bearings; the external fan that sends cooling air to the stator; the internal fan; the heat radiator that is arranged on an outer side of the drive side bracket and is mounted on the rotation shaft; the cover that contains a joint, which connects the rotation shaft extending to an outer side of the drive side bracket of the motor and a reduction gear, and is provided in parallel with the joint; and the ventilation path that is arranged between the drive side bracket and an end of the cover, and includes the outlet causes the cooling air induced by rotation of the heat radiator to flow to the heat radiator and discharges the cooling air outside the motor.

Abstract: A motor assembly includes a structural unit for mounting a motor, for mounting and enclosing electronic circuitry, and for providing a corridor for air to flow and cool the motor and/or the electronic circuitry. The motor assembly includes a substantially water-resistant motor that rotationally drives a fan for cooling the motor and/or rotationally drives a propeller for providing propulsion to watercraft. The electronic circuitry of the motor assembly receives and transmits instructions to a command post by way of electronic signals and distributes power to the motor. The structural unit seals the circuitry from the surrounding environment.

Abstract: A power tool has a casing and a motor assembly installed in the casing. The motor assembly comprises a motor and a heat dissipation device. The motor comprises a housing and magnets or windings disposed at an inner surface of the housing. The heat dissipation device is arranged at an outer surface of the housing and a window is formed in the casing to expose the heat dissipation device. Preferably, the heat dissipation device comprises an annular heat absorbing section fitted to a radially outer surface of the motor housing and a plurality of fins extending from the heat absorbing section and into the window.

Abstract: An electric motor is disclosed that includes a first electric motor frame; a second electric motor frame positioned outside the first electric motor frame; a first ventilation path between the first frame and the second frame; and a first ventilation path fan installed within the first ventilation path. The first ventilation path fan can be integral with a shaft of the electric motor. The first ventilation path can be at least partially defined by the first and second electric motor frame. The electric motor of Claim 1 further comprising a control apparatus attached outside of the second frame. The electric motor can also include a second ventilation path between the control apparatus and the second frame wherein the second ventilation path is in communication with the first ventilation path. The electric motor can also include a second ventilation path fan located in the second ventilation path.

Abstract: In an axial fan including a motor, a substrate that connects the ends of a plurality of coils is disposed at a position axially under the bottom portion of a case with an axial gap therebetween. A spacer is interposed between the substrate and the bottom portion, and the substrate is fixed to the spacer. A plurality of through holes provided in the bottom portion are disposed in axial alignment with a plurality of through holes provided in the spacer. An air flow produced by rotation of an impeller at least partially passes through the interior of the case to be discharged to the outside of the case through the through holes in the bottom portion and in the spacer so that heat generated inside the motor can be efficiently transferred to the outside of the case.

Abstract: A hollow actuator with a built-in reduction gear includes a motor having an output shaft, and a reduction gear having an input shaft, the output shaft and the input shaft being provided separately from one another. The actuator also includes a motor section and a brake section disposed on a non-load side of the motor section. A bearing is attached to an inner periphery of the brake section. Another bearing that is different from the bearing provided on the inner periphery of the brake section rotatably supports the output shaft of the motor section.

Abstract: Provided is a technology for enhancing the reliability of a permanent magnet rotating machine against thermal degradation of a permanent magnet. Specifically, provided is a permanent magnet rotating machine comprising a housing which houses a rotation shaft, a rotor connected to the rotation shaft and configured to rotate together with the rotation shaft, a stator, and permanent magnets fastened to the rotor or the stator; an air intake port provided at one end of the housing and an air exhaust port provided at the other end of the housing, the air intake port and the air exhaust port being configured to allow cooling air to flow through the housing; and a blower for feeding the cooling air to the air intake port; wherein the permanent magnet rotating machine is configured to be driven by magnetic force of the permanent magnets, and among the permanent magnets, a permanent magnet in the air exhaust port side has a higher coercivity than a permanent magnet in the air intake port side.

Abstract: A first inverter ventilation aperture is disposed so as to pass through a portion of a fin base that faces a bearing, a first rotor ventilation aperture is disposed so as to pass through a portion of a bottom surface portion that faces the bearing, and a first cooling airflow ventilation channel is formed in which a cooling airflow flows radially inward through radiating fins, then flows toward a first surface side of a mount portion through the first inverter ventilation aperture, flows axially through an interior portion of a stator core, and then flows out between the bottom surface portion and a base portion through the first rotor ventilation aperture, and subsequently flows radially outward between the bottom surface portion and the base portion due to rotational driving of a centrifugal fan.

Abstract: An air-cooled generator may be provided with a centrifugal blower configured for rotation on a shaft of the generator. The centrifugal blower may have an axially oriented outlet. An impeller of the blower may have blades with trailing edges oriented at an angle between 80° to about 90° relative to an axis of the shaft of the generator.

Abstract: An alternating current (AC) induction machine, such as a medium voltage induction motor, includes an auxiliary electrical connection box that is incorporated in the terminal box or within separate auxiliary electrical connection boxes that, are coupled to the machine's incoming power source. The box includes power conversion transformers or bridges that respectively convert the incoming AC power to other AC voltages or direct current (DC) useful for operating auxiliary devices proximal the machine. The connection box avoids the need to run separate power lines to induction machines necessary for operating auxiliary devices. Exemplary auxiliary devices include external auxiliary AC powered cooling fans for medium voltage AC motors. The auxiliary connection box may reconfigurable in the field and/or be pre-configured to provide one or more common auxiliary device output power sources.

Abstract: A dynamoelectric machine pressurization apparatus is disclosed. In one embodiment, the apparatus includes a dynamoelectric machine air shield including a channel configured to fluidly connect an outlet of a rotor fan with an ambient air source.

Abstract: An arrangement for cooling an electrical machine is provided. The electrical machine includes a rotor and a stator, an air-gap being between the rotor and the stator. The stator includes a plurality of stacked laminate-plates. The laminate-plates include on a first side, which is facing the air-gap, a plurality of slots containing metal-windings of a stator-coil. The laminate-plates are positioned and fixed by a structural support and by end-plates in relation to a central-part of the stator. A joint cavity is formed by the end-plates, the central-part of the stator and an internal surface of the laminate-plates. The internal surface is defined by a second side of the laminate-plates, the second side being opposite to the first side. The cavity is coupled with an air-cooling-arrangement, which is arranged and used to circulate a cooling gaseous medium from the cavity to the air-gap and the laminate-plates back into the cavity.

Abstract: A direction in which cooling air generated by a cooling fan flows to be discharged is perpendicular or nearly perpendicular to a direction in which diffusers are inclined. Thus, airflow resistance is increased by the diffusers, and the cooling air cannot be efficiently discharged from discharge ports provided circumferentially in an outer peripheral portion of a housing. Further, a stator coil cannot be sufficiently cooled.