Abstract: Rotodynamic pumps having an inner drive permanent magnet coupling disposed inside an impeller are provided. The impeller has a casing having a pumping region generally in a pumping plane that is perpendicular to the rotational axis of the impeller and aligned with a permanent magnet coupling that includes outer magnets that are connected to the impeller and at least partially aligned with the pumping region of the impeller, and inner magnets that are connected to an inner magnet ring and are axially aligned with the outer magnets. A canister is sealed to the casing and separates the outer magnets from the inner magnets.

Abstract: One aspect of the invention provides a centrifugal compressor unit (1) comprising a first motor (3), at least one compressor (2) comprising a drive shaft (9) driven by the rotor (12) of the first motor (3) and a set of impellers (5, 6, 7, 8) mounted on the drive shaft (9). The first motor (3) and the compressor (2) are mounted in a gas-tight common housing (26) operated by the compressor unit (1). The rotor (12) of the first motor (3) and the drive shaft (9) are connected by a flexible coupling (24) placed in the housing (26). The compressor unit includes a second motor (4) that is placed in the housing and of which the rotor (13) is connected to the drive shaft (9) by a second flexible coupling (25).

Abstract: An axial flow pump for a blood circulating pump for the circulation of blood, the rotor the rotor being constructed and arranged to impel blood in a downstream direction upon rotation of the rotor about its axis in a forward circumferential direction. The rotor is provided with hydrodynamic thrust bearing surfaces, each such thrust bearing surface being constructed and arranged to apply a hydrodynamic force to the rotor with a component of the force in the downstream direction upon rotation of the rotor in the forward circumferential direction.

Abstract: A wet rotor pump with an axial flux motor that includes a stator, a containment shell, and a rotor. The stator and the containment shell are arranged in a dry zone while the rotor on an impeller is arranged in a wet zone. The wet rotor pump further has an inlet line for a fluid to be pumped by the impeller, and a bearing for the impeller. Said bearing is arranged at one end of the inlet line and supports the impeller in such a way that the impeller has an axial degree of freedom. The inlet line extends through the stator, the containment shell, and the bearing in the axial direction.

Abstract: Provided is a waterproof fluid pump including: a motor that is accommodated in a first case and comprises a stator and a rotor, to thus generate a rotating torque; an impeller that is accommodated in a pump housing that is mounted in the first case and that receives the rotating torque of the motor to thus pump fluid; a support shaft to which the rotor and the impeller are rotatably supported and that is fixed to the first case; a first magnet that is fixed to the rotor and is rotated with the rotor; and a second magnet that is fixed to the impeller and is disposed facing the first magnet and that has opposite polarity to that of the first magnet. Thus, fluid may be fundamentally prevented from being introduced into the inside of the motor.

Abstract: A device for pumping blood, includes a housing having a distal end adapted to be coupled to a catheter, a proximal end having an outlet, and a tubular body extending between the distal and proximal ends along an axis. A rotor is rotatably disposed within the housing. A first magnetic bearing is operative to levitate the rotor along the axis within the housing. A second magnetic bearing controls a rotational frequency of the rotor. A third magnetic bearing controls a radial position of the rotor.

Abstract: The present invention relates to a novel bearing arrangement for a centrifugal pump. The bearing arrangement comprises a thrust bearing (50) arranged closer to the end (42?) of the shaft (42) carrying the rotor (44), the thrust bearing (50) being selectable between a four-point contact ball bearing for heavy-duty applications and a single row contact ball bearing for light-duty applications.

Abstract: Vibration of a rotor positioned within a stator of an electric motor of an electric submersible pump assembly is attenuated in a first embodiment by adjusting the length of the rotor to position rotor bearings supporting the rotor within the stator at locations of low amplitude vibration. In a second embodiment, hydraulic pressure is applied to a fluid chamber supporting a thrust bearing that supports the rotor. When hydraulic fluid pressure is applied, the thrust bearing and the rotor move axially. Thus, moving the rotor bearings away from areas of high amplitude vibration of the rotor. In a third embodiment, a sliding mass affixed to the motor is moved in response to vibration of the motor. Movement of the sliding mass changes the vibration profile of the motor.

Abstract: A thrust module and a seal module for use in an electric submersible pump assembly is provided. The thrust module provides increased lubrication and heat dissipation while increasing sealing redundancies within the module. The thrust module includes a thrust bearing that absorbs thrust from the primary pump. A circulation pump assembly is coupled to the thrust bearing to circulate fluid through the thrust bearing and dissipate heat generated in the thrust bearing through a plurality of fins formed on an exterior surface of the circulation pump assembly. The seal module has labyrinth discs positioned within the seal module that inhibit fluid flow through the seal module. The seal module also includes check valves that release fluid from and allow fluid into the seal module at predetermined pressures. The sealing assembly is interposed between the thrust bearing and a primary pump of the electric submersible pump.

Abstract: A supercharger includes a centrifugal compressor having an impeller, a rotational shaft coupled to the impeller, a motor having a stator and a rotor housed in a casing, and a journal air bearing supporting the rotational shaft. The journal air bearing includes a hollow cylindrical member having an inner space therein and a heat transfer member fitted in the inner space. The heat transfer member is made of a material which is less rigid and has a greater coefficient of thermal conductivity than the hollow cylindrical member. The impeller radiates heat transferred through the heat transfer member into ambient air.

Abstract: A blower fan includes a shaft including an outer circumferential surface, a rotor magnet arranged to rotate about a rotation axis together with the shaft, a stator arranged radially outwards of the rotor magnet in an opposing relationship with the rotor magnet, a substantially cylindrical holder unit arranged to rotatably support the shaft through a bearing, and an impeller arranged to rotate together with the shaft. The bearing includes a pair of axially spaced-apart bearing units. The rotor magnet and the stator are arranged between the bearing units. The bearing units and the stator are held on an inner circumferential surface of the holder unit.

Abstract: A pump assembly with a rotatable rotor shaft (10), wherein the rotor shaft (10) includes at least one axial bearing (36, 40) and a radial bearing (30, 32), which are integrated into a common bearing assembly (16).

Abstract: Various “contactless” bearing mechanisms including hydrodynamic and magnetic bearings are provided for a rotary pump as alternatives to mechanical contact bearings. In one embodiment, a pump apparatus includes a pump housing defining a pumping chamber. The housing has a spindle extending into the pumping chamber. A spindle magnet assembly includes first and second magnets disposed within the spindle. The first and second magnets are arranged proximate each other with their respective magnetic vectors opposing each other. The lack of mechanical contact bearings enables longer life pump operation and less damage to working fluids such as blood.

Abstract: A sealless-type centrifugal pump includes a casing that forms a pump chamber having a liquid inflow port and an outflow port, an impeller disposed in the pump chamber and rotatably supported by a pivot bearing, and a magnetic coupling device including a driven permanent magnet built into the impeller and a driving magnet that rotationally drives the driven permanent magnet through a partition. The impeller supported in the direction of the rotation axis with respect to the casing is driven by the magnetic coupling device, and pressure is applied to liquid introduced from the direction of the rotation axis through the inflow port to send the liquid through the outflow port in a radial direction. The magnetic coupling device is disposed on a line inclined from an impeller rotating surface to the inflow port side toward the center of the rotation axis.

Abstract: A compressor (22) has a housing assembly (50) with a suction port (24) and a discharge port (26). An impeller (54) is supported by a shaft (70) which is mounted for rotation to be driven in at least a first condition so as to draw fluid in through the suction port (24) and discharge the fluid from the discharge port (26). A magnetic bearing system (66, 67, 68) supports the shaft (70). A controller (84) is coupled to an axial position sensor (80) and is configured to control impeller position.

Abstract: A predetermined timing is a timing at which the sampling timing is in a vicinity of a maximum peak position of the carrier wave signal and a timing at which the sampling timing is in a vicinity of a minimum peak position. The demodulation arithmetic section outputs, as the demodulation calculated result, a value d3 calculated with d3=(d1?d2)/2 when a data value of the digital signal sampled in the vicinity of the maximum peak position is denoted by d1 and a data value of the digital signal sampled in the vicinity of the minimum peak position is denoted by d2.

Abstract: A magnetic bearing device comprises a controller configured to obtain magnetic levitation information of the rotor shaft by AD sampling of current detection signals from the plurality of current sensors and a sum signal obtained by adding the pair of current detection signals relating to the pair of electromagnets, and perform PWM control of the excitation amplifiers based on the magnetic levitation information. The controller performs PWM control so that a length of one of an on-duty period and an off-duty period of the PWM carrier signal is always longer than a predetermined time period based on an attenuation characteristic of a spike noise produced in the electromagnetic current, and performs the AD sampling after the predetermined time period passes from starting timing of one of the on-duty period and the off-duty period.

Abstract: An electric pump unit includes: a unit housing; a bearing unit provided within the unit housing; a rotary portion; and a motor stator fixed to the unit housing. The rotary portion includes: a pump driving motor shaft supported by the bearing unit such that an axial position of a center of gravity of the rotary portion falls within an axial range of the bearing unit, and a motor rotor. The motor rotor includes: a disc portion which extends radially outwards from an axial end portion of the motor shaft; and a cylindrical portion which extends from an outer circumferential portion of the disc portion towards the other axial end side and surrounds an outer circumference of the bearing unit.

Abstract: A sealless-type centrifugal pump includes a casing that forms a pump chamber having a liquid inflow port and an outflow port, an impeller disposed in the pump chamber and rotatably supported by a pivot bearing, and a magnetic coupling device including a driven permanent magnet built into the impeller and a driving magnet that rotationally drives the driven permanent magnet through a partition. The impeller supported in the direction of the rotation axis with respect to the casing is driven by the magnetic coupling device, and pressure is applied to liquid introduced from the direction of the rotation axis through the inflow port to send the liquid through the outflow port in a radial direction. The magnetic coupling device is disposed on a line inclined from an impeller rotating surface to the inflow port side toward the center of the rotation axis.

Abstract: A waterproof and salt spray-resistant fan motor structure includes a base, a stator assembly, a case, and at least one circuit board. The base has a bearing cup vertically projected from one side thereof. The stator assembly is externally fitted around the bearing cup, and includes a plurality of silicon steel plates having windings mounted thereon. The case is arranged between the base and the stator assembly and internally defines a closed space, and the circuit board is located in the closed space. With these arrangements, the case protects the circuit board against corrosion by water and salt spray, enabling a fan to have largely extended service life.

Abstract: Disclosed herein is a switched reluctance motor assembly, including: a rotating shaft forming a rotating center of a motor; a rotor part rotatably coupled on the rotating shaft; a front part mounted over the rotor part to support a first bearing part of the rotating shaft; a diffuser part having a plurality of integrated guide vanes mounted at an outer side thereof while being coupled with the axial upper portion of the front part; and an impeller part coupled with the axial upper portion of the diffuser and coupled with the rotating shaft. According to the preferred embodiments of the present invention, it is possible to reduce the noise generated at the time of driving the motor by manufacturing the guide vanes mounted in the diffuser of the switched reluctance motor so as to be vertically integrated.

Abstract: A bearing/stator set retainer structure includes a base seat, a stator set and a retainer member. The base seat has a bearing cup having an internal bearing hole in which a bearing is disposed. The stator set is assembled on the base seat and has an abutment section on one side distal from the base seat. The retainer member has at least one latch section for fixedly assembling the retainer member on the bearing cup. The retainer member further has at least one protrusion section in abutment with the abutment section and at least one inner flange section in abutment with the bearing. Accordingly, the retainer member can be easily disassembled from and reassembled with the bearing cup to facilitate reworking. Also, the retainer member is able to fix the bearing and the stator set at the same time to simplify the assembling process and prolong lifetime of the fan.

Abstract: A bearing cooling structure includes a metal base seat and a plastic bearing cup. The metal base seat has a raised section and an extension section. The plastic bearing cup encloses the raised section and has an inner circumference defining a bearing hole. The extension section horizontally extends from the raised section toward a center of the plastic bearing cup. The extension section has a free end and an upper surface positioned in the bearing hole. A bearing is received in the bearing hole and disposed on the extension section. A bottom face of the bearing is in contact with the upper surface of the extension section. Accordingly, the heat of the bearing can be transferred (conducted) through the extension section to the metal base seat to be dissipated. A fan with the bearing cooling structure is also disclosed.

Abstract: A pump unit includes a motor, a pump, a shaft spanning the motor and the pump, and at least a first magnetic bearing supporting the shaft. A hydrocarbon production system includes an underwater well and a pump unit exposed to an underwater environment. The pump unit is operable to pump a production fluid from the well and includes a motor, a pump, a shaft spanning the motor and the pump, and at least a first magnetic bearing supporting the shaft.

Abstract: Cooling apparatuses, electronic device assemblies, and cooling assemblies having a magnetic shape memory member are disclosed. In one embodiment, a cooling apparatus includes a first compliant member, a magnetic shape memory member, a magnetic field generating device, a second compliant member and a fan member. A first end of the magnetic shape memory member is coupled to the first compliant member. The magnetic field generating device is positioned proximate the magnetic shape memory member, and generates a magnetic field toward the magnetic shape memory member to cause the magnetic shape memory member to expand along a linear translation axis. Expansion of the magnetic shape memory member causes an actuated portion of the second compliant member to translate about an axis. The fan member is coupled to the actuated portion of the compliant member such that translation of the actuated portion translates the fan member.

Abstract: A fluid vapor distillation apparatus. The apparatus includes a source fluid input, and an evaporator condenser apparatus. The evaporator condenser apparatus includes a substantially cylindrical housing and a plurality of tubes in the housing. The source fluid input is fluidly connected to the evaporator condenser and the evaporator condenser transforms source fluid into steam and transforms compressed steam into product fluid. Also included in the fluid vapor distillation apparatus is a heat exchanger fluidly connected to the source fluid input and a product fluid output. The heat exchanger includes an outer tube and at least one inner tube. Also included in the fluid vapor distillation apparatus is a regenerative blower fluidly connected to the evaporator condenser. The regenerative blower compresses steam, and the compressed steam flows to the evaporative condenser where compressed steam is transformed into product fluid.

Abstract: An electric pump comprises a stator, a rotor, and an endshield. The interface plate is fixed to the stator and is configured to couple the electric motor to a pump. The pump volute is formed as an integral portion of the endshield, thereby minimizing the axial length of the electric pump. A drainage passageway is provided on the endshield to harmlessly drain away any fluid that seeps past the pump's seals. In one embodiment of the invention, the drainage passageway is a groove that faces the stator and is configured to facilitate the evaporation of and leak fluid by channeling the fluid near the stator, which warms the fluid and thereby increases the fluid's evaporation rate.

Abstract: An electric motor driven fan device has a base member with walls forming an enclosure, an electrically powered motor located within the enclosure and having an output shaft coupled via a bearing mounted in an upper wall of the base member to one end of a flexible drive shaft rotatably enclosed in a bendable sheath secured to the base member. The other end of the flexible drive shaft is coupled via a second bearing to a driven shaft secured to a multi-bladed fan. The other end of the bendable sheath is secured to the outer race of the second bearing. The predominant mass of the device is at the bottom, which reduces the footprint of the lower portion. The bendable sheath enables the attitude of the fan to be manually adjusted.

Abstract: An electrical submersible pump assembly has a motor module coupled to a centrifugal pump module by a seal section module. A shaft assembly extends through each of the modules for causing the motor module to rotate the pump module. At least one of the modules has a sleeve extending around the shaft that is of a harder material than the shaft. A torque transmitting ring is deformed between an inner diameter of the sleeve and an exterior portion of the shaft. The inner diameter of the sleeve is a continuous cylindrical surface free of any torque transmitting shoulders. Friction created by the torque transmitting ring transmits the entire rotational force from the shaft to the sleeve.

Abstract: Provided is a fluid pump including: a motor unit that comprises a stator, a rotor, and a rotational shaft on which the rotor is fixed, to thus generate a rotating torque; a pump unit that is placed separately from the motor unit on one side of the motor unit, and that comprises an impeller for pumping fluid: a first power transmission unit that is fixed to the rotor and is rotated with the rotor, and that comprises a first magnet; and a second power transmission unit that is fixed to the impeller and that comprises a second magnet that is disposed facing the first magnet and has opposite polarities to those of the first magnet. Accordingly, fluid can he fundamentally prevented from being introduced into the inside of the motor unit.

Abstract: Various “contactless” bearing mechanisms including hydrodynamic and magnetic bearings are provided for a rotary pump as alternatives to mechanical contact bearings. In one embodiment, a pump apparatus includes a pump housing defining a pumping chamber. The housing has a spindle extending into the pumping chamber. A spindle magnet assembly includes first and second magnets disposed within the spindle. The first and second magnets are arranged proximate each other with their respective magnetic vectors opposing each other. The lack of mechanical contact bearings enables longer life pump operation and less damage to working fluids such as blood.

Abstract: A submersible pumping system for use downhole, wherein the system includes a pump, a pump motor, a seal section, a shaft coupling the pump motor to the pump, and bearing assemblies for radially retaining the shaft in place that are offset with respect to an axis of the shaft. The offset bearing assemblies produce side loads in the shaft that reduce shaft vibration during use. The bearing assemblies can be a combination of symmetric and asymmetric assemblies set in an alternating pattern along the length of the shaft.

Abstract: The provision of the components requiring cooling on top of the cooling mechanism enables the cooling efficiency to be increased. Furthermore, a case of a control device is attached to the cooling mechanism whereon the components requiring cooling are disposed. The cooling mechanism fulfills the role of the contact surface of the case of the control device with the turbomolecular pump main unit, where the case does not have a case panel on the contact surface with the turbomolecular pump main unit. The cooling mechanism fulfills the role of one surface of the case for the control device, where the cooling mechanism is structured integrally with the control device. Additionally, the turbomolecular pump main unit, the cooling mechanism, and the control device are structured integrally by the turbomolecular pump main unit and the cooling mechanism being in contact.

Abstract: A motor includes a shaft, a bearing for supporting the shaft rotatably, a rotor including a rotor frame to be mounted to the shaft along an axial direction of the shaft, a stator confronting an outer wall of the rotor via a space, and a washer disposed between the bearing and the rotor frame. On top of that, a step section forming a recess is provided to the rotor frame at a place where the washer confronts the rotor frame.

Abstract: The present invention discloses structure improvement of a canned motor pump, and more particular to a canned motor pump which is a plastic pump or a pump with plastic lining to transfer chemical liquids, wherein a support structure of a rotor system is improved to provide a high-rigidity cantilever stationary shaft to satisfy all kinds of requirements.

Abstract: An electric pump has a stator, a rotor, a pump volute, and an endshield. The pump volute and the endshield are formed together as a single monolithic part, thereby minimizing the axial length of the electric pump. A drainage passageway is provided on the endshield to harmlessly drain away any fluid that seeps past the pump's seals. In one embodiment of the invention, the drainage passageway is a groove that faces the stator and is configured to facilitate the evaporation of and leak fluid by channeling the fluid near the stator, which warms the fluid and thereby increases the fluid's evaporation rate.

Abstract: Various “contactless” bearing mechanisms including hydrodynamic and magnetic bearings are provided for a rotary pump as alternatives to mechanical contact bearings. In one embodiment, a pump apparatus includes a pump housing defining a pumping chamber. The housing has a spindle extending into the pumping chamber. A spindle magnet assembly includes first and second magnets disposed within the spindle. The first and second magnets are arranged proximate each other with their respective magnetic vectors opposing each other. The lack of mechanical contact bearings enables longer life pump operation and less damage to working fluids such as blood.

Abstract: A fluid energy machine, in particular a compressor, is provided. The fluid energy machine includes a common rotor, which is mounted using magnetic bearings, for the flow machine and the drive. In addition to the magnetic bearings, auxiliary bearings are provided, wherein a friction bearing is provided on the bottom part of the vertically oriented rotor and a roller bearing, which provides both radial and also axial mounting, and is implemented as a ball bearing, is provided on the upper end.

Abstract: A fluid flow machine includes a housing with a connecting piece for a working fluid on an intake side, and a pressure side. At least one impeller is mounted on a shaft, which is held in the housing by radial and axial bearings, and a cooling arrangement is provided for at least one bearing. A revolving part of the axial bearing is designed as a cooling fluid transportation device, wherein a suction connection leads to the intake side of the impeller.

Abstract: A compressor bearing cooling inlet plate has a mount plate, and a boss extending forwardly from the mount plate. The boss includes a plurality of grooves extending axially into the boss to define flow passages for cooling air from an outer peripheral surface of the cooling inlet plate to an inner bore. The grooves extend for a width between side walls, at angles that are not directly radially inwardly toward a center axis of the cooling plate. There is a plurality of widths across the plurality of grooves. A compressor bearing assembly, a motor driven compressor for use in a nitrogen generation system, and a method of installing a compressor bearing cooling inlet plate are all also disclosed and claimed.

Abstract: The invention is directed to a multi-disk centrifugal pump suitable for pumping fluids, including biocompatible fluids, such as blood. The design of the pump components is optimized to reduce or eliminate the probability of clotting and hemolysis when pumping blood, and to be energy efficient and resistant to physical shock for portable applications.

Abstract: A rotary blood pump includes a casing defining a pumping chamber. The pumping chamber has a blood inlet and a tangential blood outlet. One or more motor stators are provided outside of the pumping chamber. A rotatable impeller is within the pumping chamber and is adapted to cause blood entering the pumping chamber to move to the blood outlet. The impeller has one or more magnetic regions. The impeller is radially constrained in rotation by magnetic coupling to one or more motor stators and is axially constrained in rotation by one or more hydrodynamic thrust bearing surfaces on the impeller.

Abstract: A pump and a method for operating a pump is proposed for mounting an impeller, which is inexpensive, free from contact and wear and thus extremely permanent. For this the invention uses a combination of permanent magnetic bearings and flow-mechanical bearings. The mounting is thus based on purely passive elements without using actively controlled and/or regulated elements.

Abstract: In a motor, a bearing housing is made of a thermoplastic resin material. A bottom portion of the bearing housing includes a first large diameter portion, a small diameter portion, and a second large diameter portion. The first large diameter portion of the bearing housing is arranged on an upper surface of the base. An outer circumferential surface of the small diameter portion of the bearing housing is arranged radially opposite a side peripheral surface of a base hole. The second large diameter portion is arranged to be in direct contact with a lower surface of the base through caulking.

Abstract: A vertically mountable shaft and bearing assembly includes a thermally insulated housing that protects the shaft, bearing(s), and lubricant from overheating due to a surrounding process fluid that is above 65° C. This allows a bearing to be located near the shaft's distal end, thereby reducing shaft and bearing size requirements. The housing also serves as a reservoir for bearing lubricant that can be cooled by a lubricant cooling system normally used for processes at much lower temperatures. The lubricant can be circulated by an impeller that is actuated by the shaft or driven separately. The thermal insulation, can include vacuum, air, and/or a thermally insulating material. Additional rolling element and/or journal bearings can be included. Lubricant within the shaft housing can be pressurized, for example by pressurized gas or by filling the lubricant above the surrounding process fluid level. The shaft can operate a process fluid pump impeller.

Abstract: The present invention provides a vacuum pump capable of suppressing the structure from becoming complicated and improving the damping effect. The vacuum pump includes: a holding mechanism for clamping an outer race of the ball bearing in an axial direction and holding the outer race so that the outer race moves along a radial direction; and an elastic member disposed at an outer circumferential side of the outer race. The elastic member is disposed in contact with or close to the outer circumferential side of the outer race. Oil or grease is injected into a gap between the elastic member and the outer race. Through holding the outer race against the elastic member, the elastic member is deformed to suppress vibration. Furthermore, through injecting oil or grease into the gap, the damping effect can be further improved.

Abstract: A cooling fan (1) includes a fan housing (10), a stator (20), a rotor (30) and a bearing assembly (40). A tube (111) extends upwardly from a central portion of the fan housing. The stator is mounted around the tube. The bearing assembly includes a ball bearing (333) and a sleeve bearing (335) received in two ends of the tube, respectively. The rotor has a shaft (336) extending into and rotatably supported by the bearing assembly. An elastic element (332) is arranged on the ball bearing to provide a pressing force on the ball bearing toward the sleeve bearing. An oil retaining element (339) is arranged around a bottom end of the shaft and spaced from the shaft. The oil retaining element is attached to the sleeve bearing to provide oil for the sleeve bearing.

Abstract: A motor-compressor includes a compressor, an electric motor directly connected to the compressor, magnetic bearings and one gas support located adjacent to a magnetic bearing to seal and support an end of the compressor's rotor. The compressor and the electric motor are integrated in a single unit, being housed in a single box or casing.

Abstract: A blood pump apparatus comprises a housing, a centrifugal pump section including an impeller and rotating inside the housing to feed a fluid by a centrifugal force, an impeller rotational torque generation section for attracting thereto said impeller and rotating said impeller; and a plurality of grooves for hydrodynamic bearing provided on an inner surface of said housing at a side of said impeller rotational torque generation section, each of the grooves for hydrodynamic bearing having a first side and a second side both extending from a periphery of said portion in which a groove for hydrodynamic bearing is formed toward a central side thereof and opposed to each other, a third side connecting one end of said first side and one end of said second side to each other, and a fourth side connecting said other end of said first side and said other end of said second side to each other; said first side and said second side are formed as a circular arc respectively in such a way that centers of said circular arcs

Abstract: An impeller 22 includes a rotating shaft 7 supported rotatably by an upper bearing 9 and a lower bearing 20 at upper and lower ends, a plurality of vanes 6, an arm 18 coupling an inner circumferential side of the vanes to the rotating shaft, an annular coupling portion 8 coupled to an outer circumferential side of each vane, and a driven magnet portion 12 placed in a lower portion of the annular coupling portion. A drive magnet portion 16 provided at a rotor 13 and a driven magnet portion 12 are opposed to each other with a bottom wall of the housing interposed therebetween, and rotation of the rotor is transmitted to the impeller through magnetic coupling. A blockade member 23 is placed below the vanes and blocks a space in a region spreading between the rotating shaft and the annular coupling portion while leaving an opening 14 at least around the rotating shaft.