WO2011099603A1

WO2011099603A1 - Canned electric rotating machine

Info

Publication number: WO2011099603A1
Application number: PCT/JP2011/053060
Authority: WO
Inventors: Kazutaka Yoshida; Tadashi Kataoka; Kozo Matake; Masaaki Imafuku
Original assignee: Ebara Corporation
Priority date: 2010-02-09
Filing date: 2011-02-08
Publication date: 2011-08-18
Also published as: JP2011166944A

Abstract

A canned electric rotating machine is used in an electric motor for driving a seal-less pump (non-seal pump) having a rotor chamber (15) filled with a high-pressure pump working liquid. The canned electric rotating machine includes a cylindrical frame (11), a stator (17) having a stator core (17a) and a stator winding (17b) and housed in the cylindrical frame, a can (21) configured to enclose the stator (17), and a rotor (20) rotatably provided in a space surrounded by the can (21). The can (21) is composed of a single layer of fiber-reinforced plastics comprising one resin of polyether ether ketone (PEEK), polyimide (PI), polyester amide imide, polyhydantoin, isocyanurate denatured polyester imide, polyamide-imide, polyester and epoxide, which is reinforced with carbon fiber or glass fiber or aramid fiber.

Description

DESCRIPTION

Title of Invention

CANNED ELECTRIC ROTATING MACHINE

Technical Field

[ 0001 ] The present invention relatestoa canned electric rotating machine in which a stator is enclosed by a can, and more particularly to a canned electric rotating machine suitable for use in an electric motor for driving a seal-less pump (non-seal pump) having a rotor chamber filled with a high-pressure pump working liquid.

Background Art

[0002] Conventionally, in a high-voltage canned electric motor, whose stator comprising a stator core and a stator winding is enclosed by a can, for driving a seal-less pump (non-seal pump) , particularly in a large-scale canned induction motor, having several thousands of output power (KW) and four to six poles in the number of poles, whose rotor chamber is filled with . a pump working liquid having a high-pressure of one to two kg/mm², it is required that eddy-current loss caused by magnetic flux passing through the can is reduced, the motor can withstand high internal pressure and the motor has high airtightness (gastightness) .

[0003] In this canned induction motor, it is desirable that the can made of insulting material such as resin material is used to reduce can loss (eddy-current loss) . Further, as a structure for withstanding a high-pressure pump working liquid which fills the rotor chamber, it may be conceivable that fiber-reinforced plastic (FRP) is used for a can constituent material . Furthermore, since the rotor chamber is filled with a high-pressure pump working liquid, when the rotor is rotated at high speed, the pump^' working liquid flows over the surface of the can at the same circumferential velocity as the rotor, thus causing erosion of the surface of the can made of FRP due to fluid friction and abrasion of the can. As the abrasion of the can progresses, airtightness of the can may deteriorate. Therefore, in the case where FRP is used for the can, it is necessary to take countermeasure against erosion.

[0004] Further, the pump working liquid flows in the rotor chamber at high circumferential velocity, thus causing fluid friction loss in a gap between the can and the rotor. This fluid friction loss becomes a large amount of loss depending on the length of the gap along the can and the rotor. Therefore, in a general cooling method such as a cooling method utilizing forced-fluid circulation in the rotor chamber, it is necessary to reduce the fluid friction loss because of limitations in cooling efficiency.

[0005] Further, in order to shorten a gap length, there is a structure for making a can thin. However, a pressure of a pump working liquid is applied to the can, and the can itself is pressed against the inner diameter side of the stator. At this time, when a space, a step or a gap such as a slot opening exists at an inner diameter side of the stator, the can may be deformed at the slot opening due to shortage of rigidity caused by thin can structure, or the can may be deformed so as to get into the step or the gap, or the can may be bent at the edge of the slot opening to get wrinkles, thus causing breakage or crack. As a result, airtightness and liquidtightness of the can may be damaged.

In the case where the above high-voltage induction motor is used for driving a cooling pump having a seal-less structure in a nuclear reactor, because the pump working liquid becomes high temperature, the high-voltage induction motor requires heat resistance and radiation resistance.

[0006] As a canned motor which employs FRP for a can, there have been a permanent magnet synchronous electric motor having heat resistance and pressure resistance disclosed in Japanese Laid-open Patent Publication 05-153749 and a canned motor having an improved gastightness disclosed in Japanese Laid-open Patent Publication 2001-231213.

Summary of Invention

Technical Problem

[0007] However, in Japanese Laid-open Patent Publication 05-153749 and Japanese Laid-open Patent Publication 2001-231213, no consideration is given to reduction of fluid friction loss, pressure resistance and heat resistance against a high-pressure and high-temperature pump working liquid which fills a rotor chamber, erosion resistance of the can made of FRP against high-speed flow of the pump working liquid, and radiation resistance. That is, reduction of fluid friction loss , pressure resistance, heat resistance, erosion resistance, and radiation resistance are insufficient in the conventional motor.

Further, in Japanese Laid-open utility model Publication 62-91548, a trapezoidal space between a can and a wedge for fixing wire rings is filled with hard resin. However, this structure is insufficient in pressure resistance and heat resistance.

[0008] The present invention has been made in view of the above circumstances . It is therefore an obj ect of the present invention to provide a canned electric rotating machine which can ensure reduction of fluid friction loss, excellent pressure resistance, excellent heat resistance, excellent erosion resistance and excellent radiation resistance, and can reduce eddy-current loss caused by a can to zero or a minimum.

Another object of the present invention is to provide a canned electric rotating machine which has slot wedges and a configuration of slot openings for inserting the slot wedges for improving pressure resistance of a can and cooling performance of a stator. Solution to Problem

[0009] In order to achieve the above object, according to a first aspect of the present invention, there is provided a canned electric rotating machine comprising: a cylindrical frame; a stator housed in the cylindrical frame, the stator comprising a stator core and a stator winding provided on the stator core; a can configured to enclose the stator; and a rotor rotatably provided in a space surroundedby the can; wherein the can comprises a single layer of fiber-reinforced plastics comprising one resin of polyether ether ketone (PEEK) , polyimide ( PI ), polyester amide imide, polyhydantoin, isocyanurate denatured polyester imide, polyamide-imide, polyester and epoxide, which is reinforced with carbon fiber or glass fiber or aramid fiber.

[0010] According to a second aspect of the present invention, there is provided a canned electric rotating machine comprising: a cylindrical frame; a stator housed in the cylindrical frame, the stator comprising a stator core and a stator winding provided on the stator core; a can configured to enclose the stator; and a rotor rotatably provided in a space surrounded by the can; wherein the can comprises a single layer of fiber-reinforced plastics comprising one resin of polyether ether ketone (PEEK) and polyimide (PI) resin, which is reinforced with carbon fiber or glass fiber or aramid fiber.

[0011] In a preferred aspect of the present invention, the polyimide (PI) resin is thermosetting polyimide (PI) resin, and the fiber-reinforced plastics is voidless fiber-reinforced plastics formed by vacuum exhaust and heat curing under pressure during a forming process.

[0012] According to a third aspect of the present invention, there is provided a canned electric rotating machine comprising: a cylindrical frame; a stator housed in the cylindrical frame, the stator comprising a stator core and a stator winding provided on the stator core; a can configured to enclose the stator; and a rotor rotatably provided in a space surrounded by the can; wherein the can comprises a first layer of fiber-reinforced plastics or plastics, and a second layer of a deposited metal layer or a deposited ceramic layer or a thin metal plate provided on an inner surface of the first layer.

[0013] In a preferred aspect of the present invention, the first layer comprises a fiber-reinforcedplastics comprising polyether ether ketone (PEEK) resin or polyimide resin, which is reinforced with carbon fiber or glass fiber or aramid fiber.

[0014] In a preferred aspect of the present invention, the second layer comprises a deposited metal layer formed by depositing 13Cr stainless steel or high-nickel alloy on the inner surface ofthefirstlayerora deposited ceramic layer formedby depositing Si0₂ on the inner surface of the first layer.

[0015] In a preferred aspect of the present invention, cylindrical metal rings are connected to both end surfaces of the first layer, and the second layer of the deposited metal layer or the deposited ceramic layer or the thin metal plate is provided on inner circumferential surfaces of the cylindrical metal rings and the first layer.

[0016] In a preferred aspect of the present invention, the can is held in close contact with an inner circumferential surface of the stator core, and is held by inner circumferential surfaces of frame side plates provided on both end portions of the cylindrical frame and inner circumferential surfaces of reinforcing ring members comprising cylindrical fiber-reinforced plastics provided between the frame side plates and the stator core.

[0017] In a preferred aspect of the present invention, the fiber-reinforced plastics of the reinforcing ring member comprises a fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin which is reinforced with carbon fiber or glass fiber or aramid fiber.

[0018] In a preferred aspect of the present invention, an 0 ring is provided between the can and the frame side plate and/or between the can and the reinforcing ring member.

[0019] In a preferred aspect of the present invention, an inner circumferential surface of the stator core for holding the can is cylindrical, and openings of slots formed in the stator core are formed in the inner circumferential surface of the stator core, the openings are plugged with slot wedges, the slot wedges comprise fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin which is reinforced with carbon fiber or glass fiber or aramid fiber, and surfaces of the slot wedges for holding the can comprise circular arc surfaces so as to continue from the cylindrical inner surface of the stator core without any difference in level.

[0020] In a preferred aspect of the present invention, a cooling means is provided to cool a stator chamber enclosed by the can by circulating cooling medium into the stator chamber from a compressor.

[0021] In a preferred aspect of the present invention, a pressure vessel for detecting pressure balance is provided to draw a pressure of the cooling medium in the stator chamber and a pressure of a fluid in a rotor chamber surrounded by the can into the pressure vessel, and a pressure balancing means is provided to balance the pressure of the cooling medium in the stator chamber and the pressure of the fluid in the rotor chamber by adjusting a pressure of the cooling medium supplied to the stator chamber from the compressor.

[0022] According to a fourth aspect of the present invention, there is provided a canned electric rotating machine comprising: a cylindrical frame; a stator housed in the cylindrical frame, the stator comprising a stator core and a stator winding provided on the stator core; a can configured to enclose the stator; and a rotor rotatably provided in a space surrounded by the can; wherein the can comprises a thin metal plate; and wherein the can is held in close contact with an inner circumferential surface of the stator core, and is held by inner circumferential surfaces of frame side plates provided on both end portions of the cylindrical frame and inner circumferential surfaces of reinforcing ring members comprising cylindrical fiber-reinforced plastics provided between the frame side plates and the stator core.

[0023] In a preferred aspect of the present invention, the fiber-reinforced plastics of the reinforcing ring member comprises fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin which is reinforced with carbon fiber or glass fiber or aramid fiber.

[0024] According to a fifth aspect of the present invention, there is provided a canned electric rotating machine comprising: a cylindrical frame; a stator housed in the cylindrical frame, the stator comprising a stator core and a stator winding provided on the stator core; a can configured to enclose the stator; and a rotor rotatably provided in a space surrounded by the can; wherein openings of slots formed in the stator core are plugged with slot wedges which are held in close contact with an outer circumferential surface of the can; and the slot wedges have a cutaway portion at a side opposite to an inner circumferential surface of the stator core.

[0025] In a preferred aspect of the present invention, the cutaway portion of the slot wedge is arch-shaped.

In a preferred aspect of the present invention, the slot wedge comprises machineable ceramics.

In a preferred aspect of the present invention, the slot wedge comprises a fiber-reinforced plastics.

In a preferred aspect of the present invention, a magnetic wedge is disposed between the outer circumferential surface of the can and the slot wedge.

Advantageous Effects of Invention

[0026] According to an aspect of the present invention, a can of a canned electric rotating machine comprises a single layer of fiber-reinforced plastics comprising polyether ether ketone

(PEEK) resin or polyimide (PI) resin reinforced with carbon fiber or glass fiber or aramid fiber. Therefore, the canned electric rotating machine can ensure reduction of fluid friction loss, excellent pressure resistance, excellent heat resistance and excellent radiation resistance, and can reduce eddy-current loss caused by a can to zero or a minimum.

[0027] Further, according to another aspect of the present invention, a can of a canned electric rotating machine comprises a first layer of fiber-reinforced plastics or plastics, and a second layer of a deposited metal layer or a deposited ceramic layer or a thin metal plate provided on an inner surface of the first layer. The first layer comprises fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin reinforced with carbon fiber or glass fiber or aramid fiber. Therefore, the canned electric rotating machine can ensure reduction of fluid friction loss, excellent pressure resistance, excellent heat resistance, excellent erosion resistance and excellent radiation resistance, and can reduce eddy-current loss caused by a can to zero or a minimum.

[0028] Furthermore, according to a preferred aspect of the present invention, a pressure balancing device for balancing cooling medium pressure in a stator chamber and fluid pressure in a rotor chamber is provided. Therefore, pressures inside and outside the can can be balanced, and hence there is no steady stress in a circumferential direction applied to the canby fluidpressure in the rotor chamber expect for transient state. Thus, the can is prevented from being broken, and airtightness of the can, liquidtightness of the can and mechanical life of the can can be increased remarkably. Heat generated in the stator chamber can be cooled efficiently, and deterioration of an insulating structure caused by corona discharge can be prevented.

[0029] According to another aspect of the present invention, a canned electric rotating machine comprises a cylindrical frame ; a stator housed in the cylindrical frame, the stator comprising a stator core and a stator winding provided on the stator core; a can configured to enclose the stator; and a rotor rotatably provided in a space surrounded by the can; wherein openings of slots formed in the stator core are plugged with slot wedges which are held in close contact with an outer circumferential surface of the can, there is no difference in level on the opening portion of the slot existing at the inner diameter side of the stator or no gap between the outer circumferential surface of the can and the slot wedges, and deformation of the can caused by a pressure of the pump working liquid can be prevented.

[0030] According to another preferred aspect of the present invention, the slot wedge has a cutaway portion at a side opposite to the contacting side which is held in close contact with the outer circumferential surface of the can, and the cutaway portion has substantially semicircular or triangular shape whose center line passes through a vertex of the cutaway portion and the center of the slot wedge. Therefore, weight of the slot wedge can be reduced without lowering strength of the slot wedge so much. Further, since the cutaway portion of the slot wedge extends to the laminating direction of the stator core plates, the cutaway portion serves as cooling air passage.

[0031] According to another preferred aspect of the present invention, the slot wedge comprises machineable ceramics, and thus iron loss and eddy-current loss are not generated due to nonmagnetic property and high insulating resistance even when the slot wedge is used in rotating magnetic field, and the slot wedge has high strength having little deformation against external force. Therefore, deformation of the can caused by a pressure of the pump working liquid can be prevented, and the can can be stably supported.

[0032] According to another preferred aspect of the present invention, the slot wedge comprises a fiber-reinforced plastics, and thus iron loss and eddy-current loss are not generated due to nonmagnetic property and high insulating resistance even when the slot wedge is used in rotating magnetic field, and the slot wedge has high strength having little deformation against external force. Therefore, deformation of the can caused by a pressure of the pump working liquid can be prevented, and the can can be stably supported by a lightweight structure.

[0033] According to another preferred aspect of the present invention, a magnetic wedge is disposed between the outer circumferential surface of the can and the slot wedge, and thus Carter's coefficient can be small in a gap in a motor having large width of opening of slot. Thus, effective gap length can be small and exciting current can be reduced.

Brief Description of Drawings

[0034]

[FIG. 1] FIG. 1 is a schematic vertical cross-sectional view showing a pump motor comprising a seal-less pump (non-seal pump) and a canned induction motor for driving the pump as an example of a canned electric rotating machine according to the present invention .

[FIG. 2] FIG. 2 is a fragmentary cross-sectional view showing part of a frame side plate, part of a reinforcing ring portion, part of a can, part of a stator and part of a frame body at the impeller-side of the pump motor according to an embodiment of the present invention. [FIG. 3] FIG. 3 is a fragmentary cross-sectional view showing part of a frame side plate, part of a reinforcing ring portion, part of a can, part of a stator and part of a frame body at the impeller-side of the pump motor according to another embodiment of the present invention.

[FIG. 4] FIG. 4 is a fragmentary cross-sectional view showing part of a frame side plate, part of a reinforcing ring portion, part of a can, part of a stator and part of a frame body at the impeller-side of the pump motor according to another embodiment of the present invention.

[FIG. 5] FIG. 5 is a fragmentary cross-sectional view showing part of a frame side plate, part of a reinforcing ring portion, part of a can, part of a stator and part of a frame body at the impeller-side of the pump motor according to another embodiment of the present invention.

[FIG. 6] FIG. 6 is a fragmentary cross-sectional view showing part of a frame side plate, part of a reinforcing ring portion, part of a can, part of a stator and part of a frame body at the impeller-side of the pump motor according to another embodiment of the present invention.

[FIG. 7] FIG. 7 is a fragmentary cross-sectional view showing part of a frame side plate, part of a reinforcing ring portion, part of a can, part of a stator and part of a frame body at the impeller-side of the pump motor according to another embodiment of the present invention.

[FIG. 8] FIG. 8 is a transverse cross-sectional view showing part of a stator core of a motor unit in the pump motor according to an embodiment of the present invention.

[FIG. 9A] FIG. 9A is a cross-sectional view showing a slot portion of a stator core of a motor unit in the pump motor according to another embodiment of the present invention.

[FIG. 9B] FIG. 9B is a cross-sectional view showing a slot portion of a stator core of a motor unit in the pump motor according to another embodiment of the present invention.

[FIG. 9C] FIG. 9C is a cross-sectional view showing a slot portion of a stator core of a motor unit in the pump motor according to another embodiment of the present invention.

[FIG. 10] FIG. 10 is a schematic view showing a cooling system and a pressure balancing system in the pump motor according to an embodiment of the present invention.

[FIG. 11A] FIG. 11A is a transverse cross-sectional view showing part of a stator core of a motor unit in the pump motor according to another embodiment.

[FIG. 11B] FIG. 11B is a schematic cross-sectional view showing a slot wedge in a modified embodiment.

Description of Embodiments

[0035] A canned electric rotating machine according to embodiments of the present invention will be described below with reference to FIGS .1 through 11. Like or corresponding parts are denoted by like or corresponding numerals throughout drawings and will not be described below repetitively. In the embodiments of the present invention, an induction motor will be described as an example of an electric rotating machine, but the electric rotating machine is not limited to the induction motor.

FIG. 1 is a schematic vertical cross-sectional view showing a pump motor comprising a seal-less pump (non-seal pump) and a canned induction motor for driving the pump as an example of a canned electric rotating machine according to the present invention. As shown in FIG. 1, the pump motor comprises a pump unit P and a motor unit M. The pump unit P comprising a seal-less pump (non-seal pump) has a pump casing 1 having a suction port 2 and a discharge port 3, and an impeller 5 housed in the pump casing 1 and fixed to an end of a main shaft 6. The pump casing 1 is mounted on an impeller-side bracket 7. The main shaft 6 is rotatably supported by bearings 16, 16 disposed at an upper part and a lower part of the pump motor.

[0036] The motor unit M comprising an induction motor has a motor frame 10, a motor stator 17 housed in a cylindrical frame body

11 of the motor frame 10 and fixed to the frame body 11, and a motor rotor 20 disposed inside the motor stator 17 and fixed to the central part of the main shaft 6. Both ends of the frame body 11 are mounted on a frame side plate 12 disposed at an impeller-side and a frame side plate 13 ^■ disposed at a counter-impeller-side, respectively. The frame side plate 12 is fixed to the impeller-side bracket 7 of the pump unit P. The frame side plate 12 is integrally provided with a reinforcing ring portion (reinforcing ring member) 18, and an end of the reinforcing ring portion 18 extends to the vicinity of an impeller-side end of a stator core 17a of the motor stator 17. The frame side plate 13 is integrally provided with a reinforcing ring portion (reinforcing ring member) 19, and an end of the reinforcing ring portion 19 extends to the vicinity of a counter-impeller-side end of the stator core 17a of the motor stator 17.

[0037] A cylindrical can 21 comprises a single layer of fiber-reinforced plastics, or two layers comprising a first layer of fiber-reinforced plastics or plastics and a second layer of a thin metal plate or a deposited ceramic layer or a deposited metal layer provided on an inner surface of the first layer (described later in detail) . An outer circumferential surface of the can 21 is held in close contact with inner surfaces of the stator core 17a of the motor stator 17, the reinforcing ring portion 18, the reinforcing ring portion 19, the frame side plate

12 and the frame side plate 13. An 0 ring 22 is interposed at the impeller-side between the frame side plate 12 and the can

21, and an 0 ring 23 is interposed at the counter-impeller-side between the reinforcing ring portion 19 and the can 21. Therefore, a stator chamber 14 in which the motor stator 17 is disposed is kept in a sealed state. A space enclosed by the cylindrical can 21 constitutes a rotor chamber 15 in which the motor rotor 20 is disposed.

[0038] In the pump motor having the above structure, three-phase power having a certain frequency and a certain voltage is supplied from an inverter (not shown) of a power-supply unit to a stator winding 17b of the motor unit M, thereby generating rotating-magnetic field and rotating the motor rotor 20. Thus, the impeller 5 fixed to the main shaft 6 is rotated, and a pump working liquid sucked through the suction port 2 of the pump casing 1 is pressurized and discharged through the discharge port 3. At this time, since the pump unit P comprises a seal-less pump (non-seal pump) , the rotor chamber 15 is filled with the pump working liquid, and the pump working liquid in the rotor chamber 15 is stirredby themotor rotor 20. Thus, the pump working liquid having the same circumferential velocity as the motor rotor 20 flows over the inner circumferential surface of the can 21, and a pressure of the pump working liquid is applied to the inner circumferential surface of the can 21.

[0039] FIG. 2 is a fragmentary cross-sectional view showing part of the frame side plate 12, part of the reinforcing ring portion 18, part of the can 21, part of the stator 17 and part of the frame body 11 at the impeller-side of the pump motor. As shown in FIG.2, the can 21 comprises a single layer of fiber-reinforced plastics (FRP) . In this example, as a material of the -can 21, polyether ether ketone (PEEK) resin or polyimide (PI) resin having high heat resistance and high mechanical strength is used. Further, FRP which is reinforced with reinforcement fiber having high strength such as long-fibered glass or long-fibered aramid and has high mechanical strength is used. In this manner, the can 21 is composed of FRP comprising PEEK resin or PI resin reinforced with long fiber of carbon, glass or aramid, and part of the can 21 which is not reinforced with the stator core 17a of the motor stator 17 (i.e. part of the stator chamber 14 in which the stator winding 17b and wire connection portion (not shown) are disposed) is reinforced with the reinforcing ring portion 18 which comprises FRP comprising PEEK or PI reinforced with carbon fiber and is disposed so as to contact the outer circumferential surface of the can 21 and imparts mechanical strength to the can 21. As FRP resins, in addition to polyether ether ketone (PEEK) and polyimide (PI), polyester amide imide, polyhydantoin, isocyanurate denatured polyester imide, polyamide-imide, polyester and epoxide may be used . These resins have resistance to high-temperature and radiation resistance in common, and thus are suitable for application requiring resistance to high-temperature and radiation resistance. Among these resins, particularly, PEEK and PI have a high application performance in a nuclear power plant and are particularly suitable for use in the nuclear power plant.

[0040] In the case where thermosetting PI resin which can easily form dense structure having few void by vacuum exhaust and heat curing under pressure during a resin forming process is used for a resin for forming a FRP layer of the can 21, a can having high airtightness and liquidtightness can be constructed. The can 21 comprising a single layer of FRP reinforced with fiber composed of aramid resin has tensile strength in a circumferential direction which is one to three times that of metal material such as stainless steel. The reinforcing ring portion 18 and the frame side plate 12 are integrally formed by stainless steel or the like, and thus structural strength can be imparted to part of the can which is not reinforced with the stator core 17a of the motor stator 17, and the area of the can to which internal pressure is. applied can be expanded. The reinforcing ring portion 18 and the frame side plate 12 may be formed by carbon FRP reinforced with carbon fiber and having tensile strength which is 5 to 10 times that of stainless steel, thereby further increasing structural strength.

[0041] In the case where FRP comprising PEEK resin or PI resin having high structural strength and reinforced with long-fibered carbon is used for the can 21, a reinforcing structure such as the reinforcing ring portion 18 for reinforcing strength of the can 21 can be omitted because the can 21 has sufficient strength. In particular, in the case where thermosetting PI resin which can easily form dense structure having few void by vacuum exhaust and heat curing under pressure during a resin forming process is used for a resin for forming a FRP layer of the can 21, the can 21 having high airtightness and liquidtightness can be constructed.

[0042] In this case, since FRP contains conductive carbon fiber in the resin layer, can loss (eddy-current loss) is generated. However, since volume resistivity of FRP containing carbon fiber is about 100 times that of stainless steel, it is apparent from the following equation (1) that if the can has a certain thickness , the can loss can be greatly reduced to 1/100 of stainless steel.

[0043] Wc=15.5-Dil³-Lg-fBg²-Ns²-10^"16-Ks/ p (1)

where c is can loss (W) , Dil is an inner diameter of stator core (cm) , Lg is a length of stator core (cm) , t is a thickness of can (cm) , Bg is maximum magnetic flux density (T) in air gap, Ns is synchronous speed (r/sec), p is resistivity of can material (□^•cm), Ks is loss reduction coefficient determined by ratio of the length of stator core (Lg) and pole pitch ( τ ) , t is pole pitch (πϋϋ/Ρ) (cm), and P is pole number of motor..

The equation (1) is a calculation equation for calculating can loss recommended by AIEE (American Institute of Electrical Engineers) .

[0044] FIG. 3 is a fragmentary cross-sectional view showing part of the frame side plate 12, part of the reinforcing ring portion 18, part of the can 21, part of the stator 17 and part of the frame body 11 at the impeller-side of the pump motor. As shown in FIG. 3, the can 21 has a two-layer structure comprising a first layer 21a and a second layer 21b. The first layer 21a is composed of FRP comprising PEEK resin or PI resin having high structural strength and reinforced with long fiber of carbon, or FRP comprising PEEK resin or PI resin reinforced with long fiber of glass or aramid, as with the can 21 having a single layer shown in FIG. 2. As FRP resins, in addition to polyether ether ketone (PEEK) and polyimide (PI) , polyester amide imide, polyhydantoin, isocyanurate denatured polyester imide, polyamide-imide, polyester and epoxidemay be used. These resins have resistance to high-temperature and radiation resistance in common, and thus are suitable for application requiring resistance to high-temperature and radiation resistance. Among these resins, particularly, PEEK and PI have a high application performance in a nuclear power plant and are particularly suitable for use in the nuclear power plant.

[0045] Further, the second layer 21b comprises a metal film formed by depositing a metal material (stainless steel, high-nickel alloy, titanium nitride) on the inner surface of the first layer 21a by PVD (physical vapor deposition) , or a thin metal plate held in close contact with the inner surface of the first layer 21a. In this manner, by providing the. metal film deposited on the inner surface of the first layer 21a by PVD or the thin metal plate held in close contact with the inner surface of the first layer 21a, higher airtightness of the can can be ensured, and wear (erosion) of the inner surface of the can 21 caused by a flow of a pump working liquid over the inner surface of the can 21 can be prevented. In order to ensure airtightness of the can and to prevent erosion of the can from occurring, a deposited ceramic layer formed by depositing Si0₂ on the inner surface of the first layer 21a may be effective.

[0046] As described above, by providing the second layer 21b comprising the metal film deposited by PVD on the inner surface of the first layer 21a composed of FRP or the second layer 21b comprising the thin metal plate held in close contact with the inner surface of the first layer 21a composed of FRP, can loss (eddy-current loss) is generated in the second layer 21b . However, if the metal film formed by PVD has a thickness of several μπ\ to several tens μπι and the thin metal plate has a thickness of 0.05mm to 0.1mm, then the can loss of the metal film becomes 1/100 to 1/4 of that of a general metal can having a thickness of 0.2mm to 0.5mm and the can loss of the thin metal plate becomes 1/10 to 1/2 of that of the above general metal can. This reduction of the can loss can be verified by the equation (1) .

[0047] Although the metal film formed by PVD and the thin metal plate have a very small thickness and low structural strength, because the first layer 21a is composed of FRP comprising PEEK resin or PI resin having high structural strength and reinforced with long fiber of carbon, or FRP comprising PEEK resin or PI resin reinforced with long fiber of glass or aramid, the metal film formed by PVD or the thin metal plate constituting the second layer 21b can be stably retained.

[0048] As described above, since the first layer 21a comprises FRP comprising PEEK resin or PI resin reinforced with long fiber of carbon, glass or aramid, the eddy-current loss of the first layer 21a can be reduced to zero or a minimum. Part of the can 21 which is not reinforced with the stator core 17a of the motor stator 17 (i.e. part of the stator chamber 14 in which the stator winding 17b and wire connection portion (not shown) are disposed) is reinforced with the reinforcing ring portion 18 which comprises FRP comprising PEEK or PI reinforced with carbon fiber and is disposed so as to contact the outer circumferential surface of the can 21 and imparts mechanical strength to the can 21.

[0049] In the case where thermosetting PI resin is used for a resin for forming the first layer 21a of the can 21, and dense structure having few void is formed by vacuum exhaust and heat curing under pressure during a resin forming process, the first layer 21a having high airtightness and liquidtightness can be constructed. The first layer 21 composed of FRP reinforced with fiber comprising aramid resin has tensile strength in a circumferential direction which is one to three times that of metal material such as stainless steel. If structural strength of the can 21 is insufficient under conditions of high pressure of the pump working liquid in the can 21, carbon FRP whose tensile strength is 5 to 10 times that of stainless steel is used for the reinforcing ring portion 18. Thus, structural strength can be imparted to part of the can which is not reinforced with the stator core 17a of the motor stator 17 and the area of the can to which internal pressure is applied can be expanded.

[0050] FIG. 4 is a fragmentary cross-sectional view showing part of the frame side plate 12, part of the reinforcing ring portion 18, part of the can 21, part of the stator 17 and part of the frame body 11 at the impeller-side of the pump motor. As shown in FIG. 4, a metal can 21c composed of a cylindrical thin metal plate having a thickness of 0.1mm is used. The thin metal plate can 21c is fixed such that the outer circumferential surface of the thin metal plate can 21c is held in close contact with the inner circumferential surface of the stator core 17a and the inner circumferential surface of the reinforcing ring portion 18. As shown in FIG. 8, openings of slots 30 are formed in the inner circumferential surface of the stator core 17a, and the openings of the slots 30 are plugged with slot wedges 31 composed of FRP comprising PEEK resin.or PI resin reinforced with short fiber of carbon, aramid or glass . Thus, the inner circumferential surface A of the stator core 17a is formed into a smooth circular shape without any difference in level by the plugged slot wedges 31.

[0051] The outer circumferential surface of the thin metal plate can 21c is held in close contact with the inner circumferential surface A of the stator core 17a having no difference in level. Stress applied to the thin metal plate can 21c by internal pressure is received by the inner circumferential surface A of the stator core 17a, thereby retaining the thin metal plate can 21c. Part of the outer circumferential surface of the thin metal plate can 21c which is not held in close contact with the inner circumferential surface A of the stator core 17a (i.e. part of the stator chamber 14 in which terminal ends of the stator winding 17b and wire connection portion are disposed) is held in close contact with the inner circumferential surface of the cylindrical reinforcing ring portion 18 and is thus retained. The reinforcing ring portion 18 comprises FRP comprising PEEK or PI reinforced with carbon fiber, and the inner surface of the reinforcing ring portion 18 is circular so as to continue from the inner surface of the stator core 17a without any difference in level. The thin metal plate can 21c is held by the inner circumferential surface of the stator core 17a and the inner circumferential surface of the reinforcing ring portion 18.

[0052] By adopting the above structure, the can loss of the can 21 can be reduced to 1/5 to 1/2 of that of a general can having a thickness of 0.2 to 0.5mm. Further, the can 21 has excellent airtightness, excellent liquidtightness and excellent abrasion resistance as with the metal can.

[0053] By using carbon FRP for a material of the reinforcing ring portion 18, the tensile strength of the carbon FRP is 5 to 10 times that of a general metal material, and thus the thickness of the reinforcing ring portion 18 can be 1/10 to 1/5 of that of the reinforcing ring portion 18 made of metal.

[0054] By placing the reinforcing ring portions 18 , 19 (see FIG.1) composed of the above carbon FRP having a reduced thickness at both ends of the stator core 17a, areas of the reinforcing ring portions 18, 19 in a radial direction of the stator core 17a can be very small, and displacement of positions of the stator windings 17b, 17b inserted into the slots 30 of the motor stator 17 toward the outer circumferential side of the stator core 17a can be small. Therefore, the stator core 17a can be prevented from being large-scaled. As the moving distance of the insert position of the stator windings 17b, 17b toward the outer circumferential side of the stator core 17a is larger, the shape of the slot 30 is forced to be an elongated shape in a radial direction, and a space in which the stator windings 17b, 17b exist increases . Therefore, flux leakage increases and maximum torque of the motor unit M decreases, and thus a bulk of the motor unit M for achieving the required torque increases. By making the reinforcing ring portion 18 thin, the bulk of the motor unit M which is liable to be large-sized due to insertion of the reinforcing ring portion 18 can be prevented from being large-scaled.

[0055] After the stator windings 17b, 17b are housed in the slots 30 of the stator core 17a, insulating spacers 32 for fixing the stator windings 17b, 17b into the slots 30 are inserted into grooves 37 formed in the slots 30, thereby plugging the openings of the slots 30. . The inner circumferential surface of the slot wedge 31 is formed into the shape having no difference in level with the inner circumferential surface A of the stator core 17a. When the can 21 disposed at the inner diameter side of the motor stator 17 is pressed against the inner circumferential surface of the motor stator 17 due to internal pressure of the rotor chamber 15 or thermal deformation or other stresses, the slot wedges 31 serve as a structural body for preventing damage of the can 21 caused by the edge of the opening of the slot 30 and for supporting a force which causes the can 21 to be deformed toward an outer diameter direction.

[0056] The slot wedge 31 has a side of circular arc so as to continue from the inner circumferential surface A of the stator core 17a without any difference in level, and has a projection 31a having a rectangular cross-section as shown in FIG. 8 or a projection 31a having a triangular shape or a semicircular shape as shown in FIGS. 9A, 9B and 9C at both ends of the circular arc. The projection 31a is fitted into a groove formed in the inner surface of the slot 30 to receive a force applied from the can 21. Although the slot wedges 31 have a substantially rectangular shape, as shown in FIG. 9C, the side opposite to the inner circumferential surface A of the stator core 17a is formed into an arch shape to reduce an amount of resin and weight of the resin without lowering of the strength. As shown in FIGS. 8 and 9, insulating spacers 32 are provided in each of the slots 30. Further, the slot wedges 31 are not limited to the structure shown in FIGS. 8 and 9, and are applicable to other structure such as structure shown in FIGS. 2 and 3.

[0057] FIGS. 11A and 11B are views showing a slot wedge according to another embodiment. In this embodiment, the slot wedge 31 has a side opposite to the inner circumferential surface A of the stator core 17a which is formed into an arch shape as with the embodiment shown in FIG. 9C. The slot wedge 31 has a wedge insert portion 36 which projects from the slot toward the stator core 17a and has a substantially trapezoidal shape in cross-section. Further, the insulating spacer 32 has a width longer than that of the slot. 30, and projects into the stator core. In a large-scale motor or a high-voltage motor, there is a design specification in which insertion width of stator windings is substantially equal to width of opening of the slot 30. Further, in the case of inserting the slot wedge 31, the slot 30 is required to be such a shape as to be deeper to the outer diameter side of the motor stator 17, compared to a design specification having no slot wedge. Therefore, Carter's coefficient for calculating gap dimension for use in calculating magnetic circuit on the basis of mechanical gap dimension tends to be larger. Further, since the width of opening becomes large and the width between the openings (i.e. the width of teeth of stator) becomes small, pulsation of distribution of magnetic flux in the gap portion becomes large, and an effect of spatial harmonic becomes large. Therefore, a magnetic wedge 38 is disposed between the inner circumferential surface A of the slot wedge 31 and the outer circumferential surface of the can 21 to improve magnetic path near the gap. Thus, the Carter's coefficient can be small, the gap dimension used for calculating magnetic circuit can be small, and exciting current can be reduced. Further, magnetic flux is passed through the magnetic wedge 38 to prevent magnetic flux from concentrating on the teeth portion of the stator, thereby reducing spatial harmonic flux. As a result, loss (loss in rotor surface, iron loss of teeth of rotor) caused by pulsation in teeth portion of stator can be reduced. Further, as shown in FIG. 11B, the magnetic wedge 38 may be embedded in advance in the slot wedge 31. As shown in FIG. 11A, an upper spacer 33, an intermediate spacer 34 and a lower spacer 35 should be inserted properly, if the stator windings 17b, 17b are not fixed sufficiently only by the insulating spacer 32.

[0058] FIG. 5 is a fragmentary cross-sectional view showing part of the frame side plate 12, part of the reinforcing ring portion 18, part of the can 21, part of the stator 17 and part of the frame body 11 at the impeller-side of the pump motor. In FIG. 5, the first layer 21a of the can 21 is composed of FRP comprising PEEK resin or PI resin having high structural strength and reinforced with long fiber of carbon, or FRP comprising PEEK resin or PI resin reinforced with long fiber of glass or aramid, as with the first layer shown in FIG. 3. A cylindrical metal ring 24 is fixed by adhesive to the end surface of the first layer 21a in a longitudinal direction of the first layer 21a. The metal ring 24 has an inner circumferential surface and an outer circumferential surface which continue from the inner circumferential surface and the outer circumferential surface of the first layer 21a without any difference in level.

[0059] The second layer 21b comprises a metal film formed by depositing a metal material on the metal ring 24 and the first layer 21a which are integrally bonded, or a thin metal plate held in close contact with the metal ring 24 and the first layer 21a which are integrally bonded. Also in the case of the can 21 which comprises a metal ring 24 and a first layer 21a integrally bonded, and a deposited metal layer or a thin metal plate provided on the metal ring 24 and the first layer 21a, the can structure having high airtightness and liquidtightness can be provided. An 0 ring 22 is interposed between the outer circumferential surface of the metal ring 24 and the inner circumferential surface of the frame side plate 12 at the impeller-side, and thus the pump working fluid is prevented from entering the stator chamber 14. Further, since the outer circumferential surface of the bonded portion of the first layer 21a and the metal ring 24 is covered with the second layer 21b comprising a deposited metal layer or a thin metal plate, airtightness and liquidtightness can be maintained. As a measure for preventing airtightness and liquidtightness from being lowered due to crack or the like of the second layer 21b comprising a deposited metal layer or a thin metal plate, an 0 ring 22 is interpose between the outer circumferential surface of the reinforcing ring portion 18 and the inner circumferential surface of the can 21 to prevent the pump working liquid from entering the stator chamber 14.

[0060] The first layer 21a may be formed as a FRP can comprising a cylindrical fiber bundle formed by winding reinforcement fiber transversely and thermosetting resin impregnated into the cylindrical fiber bundle by vacuum exhaust and heat curing. The metal ring 24 may be bonded to the first layer 21a by the thermosetting resin as adhesive at the forming process of the first layer, thereby integrating the metal ring 24 and the first layer 21a. [0061] Further, if it is necessary to detect a lowering of airtightness and liquidtightness of the second layer 21b caused by crack or the like, as shown by dotted lines of FIG.5, a pressure detecting hole 33 which opens on the surface of the can 21 between the two 0 rings 22, 22 is provided, and the pressure detecting hole 33 is connected to a pressure detector 34. The pump working liquid leaked from the rotor chamber 15 reaches the pressure detecting hole 33, and a pressure of the pressure detecting hole 33 increases. By detecting pressure increase by the pressure detector 34 located outside the motor, leakage of the pump working liquid can be detected. Outputs of the pressure detector 34 are transmitted to a control panel of the pump motor, and an alarm indicating generation of crack in the deposited metal layer or the thin metal plate is issued.

[0062] FIG. 6 is a fragmentary cross-sectional view showing part of the frame side plate 12, part of the reinforcing ring portion 18, part of the can 21, part of the stator 17 and part of the frame body 11 at the impeller-side of the pump motor. In FIG. 6, the first layer 21a of the can 21 is composed of FRP comprising PEEK resin or PI resin having high structural strength and reinforced with long fiber of carbon, or FRP comprising PEEK resin or PI resin reinforced with long fiber of glass or aramid, as with the embodiments shown in FIGS. 3 and 5. A second layer 21b comprising a deposited metal layer is formed on the inner circumferential surface of the first layer 21a, an end surface of the first layer 21a in the longitudinal direction of the first layer 21a, and an outer circumferential surface located near the end surface. An 0 ring 22 is interposed between the second layer 21b of the can 21 and the inner circumferential surface of the frame side plate 12 at the impeller-side, and an 0 ring 22 is interposed between the inner circumferential surface of the reinforcing ring portion 18 and the inner surface of the can 21 having no second layer 21b (inner surface of the first layer 21a), thereby forming double seal.

[0063] FIG. 7 is a fragmentary cross-sectional view showing part of the frame side plate 12, part of the reinforcing ring portion 18, part of the can 21, part of the stator 17 and part of the frame body 11 at the impeller-side of the pump motor. In this embodiment, the reinforcing ring portion 18 comprises a cylindrical member separated from the frame side plate 12 at the impeller-side. A projecting portion 18a is provided on the end surface of the reinforcing ring portion 18 in the longitudinal direction of the reinforcing ring portion 18, and the projecting portion 18a is fitted into a groove 12a formed in the inner side surface of the frame side plate 12. Thus, the reinforcing ring portion 18 is fixed to the frame side plate 12. The first layer 21a of the can 21 is composed of FRP comprising PEEK resin or PI resin having high structural strength and reinforced with long fiber of carbon, or FRP comprising PEEK resin or PI resin reinforced with long fiber of glass or aramid, as with the embodiments shown in FIGS. 3, 5 and 6. A second layer 21b comprising a deposited metal layer or a deposited ceramic layer or a thin metal plate is formed on the outer circumferential surface of the first layer 21a.

[0064] By using carbon FRP as a material for constructing the reinforcing ring portion 18 separated from the frame side plate 12, since the tensile strength of carbon FRP is 5 to 10 times that of a general metal material, the thickness of the reinforcing ring portion 18 can be 1/10 to 1/5 of that of the reinforcing ring portion 18 made of metal.

[0065] By placing the reinforcing ring portions 18, 19 composed of the above carbon FRP having a reduced thickness at both ends of the stator core 17a, areas of the reinforcing ring portions 18, 19 in a radial direction of the stator core 17a can be very small, and displacement of positions of the stator windings 17b, 17b inserted into the slots 30 of the motor stator 17 toward the outer circumferential side of the stator core 17a can be small. Thus, the stator core 17a can be prevented from being large-scaled.

[0066] FIGS. 2 through 7 show part of the frame side plate 12, part of the reinforcing ring portion 18, part of the can 21, part of the motor stator 17 and part of the frame body 11 at the impeller-side of the pump motor. However, the frame side plate 13, the reinforcing ring portion 19, the can 21, the motor stator 17, and the frame body 11 at the counter-impeller-side have the same structure as those in FIGS. 2 through 7, and thus illustration and explanation thereof are omitted.

[0067] In the embodiments shown in FIGS. 2 through 7, the end portion of the can 21 at the impeller-side is a free end in an axial direction of the can 21 to absorb expansion and contraction of the can 21 in the longitudinal direction of the can 21 caused by heat. However, absorption of expansion and contraction of the can 21 in the longitudinal direction of the can 21 caused by heat is not limited to this measure . For example, metal bellows may be provided on both ends of the can 21 in the longitudinal direction of the can 21 so as to be in close contact with the can 21, and expansion and contraction of the can 21 are absorbed by expansion and contraction of the metal bellows. Other expansion and contraction mechanism may be provided.

[0068] Further, in the embodiments shown in FIG. 3 and FIGS. 5 through 7, FRP is used for the second layer 21a. Because the reinforcing ring portions 18 and 19 are provided, if a pressure of the pump working liquid is not so high, then the second layer 21a may be formed only by resin (plastic) which is not reinforced with fiber. As resins of this case, in addition to polyether ether ketone (PEEK) and polyimide (PI), polyester amide imide, polyhydantoin, isocyanurate denatured polyester imide, polyamide-imide, polyester and epoxide may be used as with the embodiments shown in FIG. 3 and FIGS. 5 through 7. [0069] In the above seal-less pump and the canned induction motor for driving the pump, it is necessary to cool heat generation in the stator chamber 14 caused by copper loss of the stator, iron loss of the stator and can loss. FIG. 10 is a schematic view showing a cooling system. Any of air, nitrogen gas, helium gas and hydrogen gas is circulated through the stator chamber 14 from the outside by a compression pump 25 as a forced-cooling gas , and the cooling gas is passed through cooling grooves provided in the stator core 17a or the outer circumferential portion of the stator core 17a and pierced in an axial direction of the stator core 17a, thereby cooling the heat loss. The heat loss of the can 21 is cooled through the stator core 17a by the above cooling gas. The cooling gas is cooled by a heat exchanger 26 located outside the pump motor. In this embodiment, the cooling gas is used as a cooling medium, but the cooling medium is not limited to gas and a cooling liquid may be used.

[0070] The heat loss in the stator chamber 14 is cooled by the above cooling system. A pressure vessel 27 is provided to detect pressure balance between pressure of the cooling gas in the stator chamber 14 and fluid pressure of the pump working liquid in the rotor chamber 15. The pressure of the cooling gas in the stator chamber 14 and the fluid pressure in the rotor chamber 15 are drawn into the pressure vessel 27. A mechanism for regulating a gas pressure in the stator chamber 14 by using a compressor 28 is provided on the pressure vessel 27. By performing pressure control using the compressor 28 so as to balance the gas pressure in the stator chamber 14 and the fluid pressure in the rotor chamber 15 in the pressure vessel 27 (so as to locate a sluice valve 27a at a balanced point ) , it is possible to maintain pressure balance in the stator chamber 14, i.e. inside and outside the can 21. While the heat loss generated in the stator chamber 14 is cooled by gas, pressures inside and outside the can 21 are balanced using the above mechanism, thereby achieving the following effects (a) to (c) .

[0071] (a) Because pressures inside and outside the can 21 are balanced, there is no steady stress in a circumferential direction of the can 21 caused by fluid pressure in the rotor chamber 15 except for transient state. Therefore, the can 21 is prevented from being damaged, and the can 21 has excellent airtightness and excellent liquidtightness and mechanical life of the can 21 can be remarkably increased.

[0072] (b) Since the pressure balance inside and outside the can 21 can be maintained, the pressure in the stator chamber 14 increases, and thus cooling efficiency of the cooling gas can be increased. The cooling gas is passed through the cooling grooves (not shown) provided in the stator 17 to cool various losses (copper loss, iron loss, can loss) generated in the stator chamber. 14, thereby achieving direct cooling having high efficiency. Thus, the motor unit M can be prevented from being large-scaled.

[0073] (c) Since the pressure in the stator chamber 14 becomes high, corona discharge starting voltage of high-voltage winding can be increased. Thus, corona discharge can be suppressed and deterioration of insulating component caused by corona discharge can be reduced.

[ 0074 ] FRP components such as the first layer 21a or the reinforcing ring portions 18, 19 of the can 21 cause thermal expansion by an influence of heat loss of the thin metal can. Since linear expansion coefficient of resin is generally larger than that of metal material, a buffer layer may be damaged due to a friction caused by difference of linear expansion in an axial direction of FRP between the thin metal can and FRP of the buffer layer and between a metal reinforcing structural member and FRP of the buffer layer, or the thin metal can may be damaged or broken due to mechanical stress generated in the thin metal can. Therefore, reinforcement fiber used for FRP of the buffer layer is incorporated in the resin by the following method, and the linear expansion coefficient of the FRP in the axial direction can be equivalent to or close to the thin metal can and the metal reinforcing structural portion. Thus, difference of thermal expansion is eliminated and damage is avoidable.

[0075] The linear expansion coefficient of FRP is determined by dominant factors including linear expansion coefficient of reinforcement fiber and orientation of fiber. For example, in the FRP in which carbon fiber is disposed in a single direction, the linear expansion coefficient of the FRP in a fiber direction is approximately 5*10^~6(1/°C, 0-100°C) , and the linear expansion coefficient of the FRP in a direction perpendicular to the fiber is approximately 40 ^χ 10^~6 ( 1/°C, 0-100°C) . That is, the linear expansion coefficient differs greatly depending on the direction of the fiber. Therefore, by setting the direction of the fiber properly, the linear expansion coefficient of FRP can be brought close to the linear expansion coefficient of the thin metal film or the metal reinforcing structural member, i.e. 11*10^"6 to 19xlO-⁶(l/°C, 0-100°C) .

[0076] In the case where reinforcement fiber is wound transversely to the cylindrical FRP structural member, the reinforcement fiber is wound in a spiral fashion at a roving angle having a certain angle Θ to the axial direction, and by adjusting this angle Θ, the linear expansion coefficient required for the cylindrical FRP structural member in the axial direction can be adjusted. The linear expansion coefficient in the axial direction is generally determined by the following equation (2).

K_ta=AXcos Θ +BXsin Θ (2)

where K_ta is linear expansion coefficient in an axial direction, A is linear expansion coefficient (1/°C) in a fiber direction of FRP, B is linear expansion coefficient (1/°C) in a direction perpendicular to the fiber of FRP, and Θ is angle of winding direction of fiber to the axial direction. [0077] Further, by adjusting density of the reinforcement fiber or size of the reinforcement fiber, the linear expansion coefficient of the cylindrical FRP structural member can be adjusted.

Further, the above slot wedge 31 has an arch shape at a side opposite to the inner circumferential surface A of the stator core 17a, and thus a space extending in a laminating direction of stator core plates can be formed between this side of the slot wedge 31 and the insulating spacer 32. Therefore, this space is used as passage for forced-cooling gas, thereby achieving direct cooling having high efficiency.

[0078] Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.

Industrial Applicability

[0079] According to the present invention, because the can of the canned electric rotating machine comprises a first layer of fiber-reinforced plastics and a second layer of a deposited metal layer or a deposited ceramic layer or a thin metal plate provided on an inner surface of the first layer, and the fiber-reinforced plastics of the first layer comprises polyether ether ketone (PEEK) resin or polyamide (PI) resin reinforced with carbon fiber or glass fiber or aramid fiber. Therefore, the canned electric rotating machine can ensure reduction of fluid friction loss, excellent pressure resistance, excellent heat resistance, excellent erosion resistance and excellent radiation resistance, and can reduce eddy-current loss caused by the can to zero or a minimum.

Claims

[Claim 1]

A canned electric rotating machine comprising:

a cylindrical frame;

a stator housed in said cylindrical frame, said stator comprising a stator core and a stator winding provided on said stator core;

a can configured to enclose said stator; and

a rotor rotatably provided in a space surrounded by said can;

wherein said can comprises a single layer of fiber-reinforcedplastics comprising one resin of polyether ether ketone (PEEK), polyimide (PI), polyester amide imide, polyhydantoin, isocyanurate denatured polyester imide, polyamide-imide, polyester and epoxide, which is reinforced with carbon fiber or glass fiber or aramid fiber.

[Claim 2]

A canned electric rotating machine comprising:

a cylindrical frame;

a can configured to enclose said stator; and

a rotor rotatably provided in a space surrounded by said can;

wherein said can comprises a single layer of fiber-reinforcedplastics comprising one resin of polyether ether ketone (PEEK) and polyimide (PI) resin, which is reinforced with carbon fiber or glass fiber or aramid fiber.

[Claim 3]

A canned electric rotating machine according to claim 2, wherein said polyimide (PI) resin is thermosetting polyimide (PI) resin, and said fiber-reinforced plastics is voidless fiber-reinforced plastics formed by vacuum exhaust and heat curing under pressure during a forming process.

[Claim 4]

A canned electric rotating machine comprising:

a cylindrical frame;

a can configured to enclose said stator; and

a rotor rotatably provided in a space surrounded by said can;

wherein said can comprises a first layer of fiber-reinforced plastics or plastics, and a second layer of a deposited metal layer or a deposited ceramic layer or a thin metal plate provided on an inner surface of said first layer.

[Claim 5]

A canned electric rotating machine according to claim 4, wherein said first layer comprises a fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin, which is reinforced with carbon fiber or glass fiber or aramid fiber .

[Claim 6]

A canned electric rotating machine according to claim 4 or 5, wherein said second layer comprises a deposited metal layer formed by depositing 13Cr stainless steel or high-nickel alloy on the inner surface of said first layer or a deposited ceramic layer formed by depositing SiC>2 on the inner surface of said first layer .

[Claim 7]

A canned electric rotating machine according to any one of claims 4 to 6, wherein cylindrical metal rings are connected to both end surfaces of said first layer, and said second layer of the deposited metal layer or the deposited ceramic layer or thethinmetalplate is provided on inner circumferential surfaces of said cylindrical metal rings and said first layer.

[Claim 8]

A canned electric rotating machine according to any one of claims 2 to 7, wherein said can is held in close contact with an inner circumferential surface of said stator core, and is held by inner circumferential surfaces of frame side plates provided on both end portions of said cylindrical frame and inner circumferential surfaces of reinforcing ring members comprising cylindrical fiber-reinforced plastics provided between said frame side plates and said stator core.

[Claim 9]

A canned electric rotating machine according to claim 8, wherein said fiber-reinforced plastics of said reinforcing ring member comprises a fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin which is reinforced with carbon fiber or glass fiber or aramid fiber.

[Claim 10]

A canned electric rotating machine according to any one of claims 2 to 9, wherein an 0 ring is provided between said can and said frame side plate and/or between said can and said reinforcing ring member.

[Claim 11]

A canned electric rotating machine according to any one of claims 2 to 10, wherein an inner circumferential surface of said stator core for holding said can is cylindrical, and openings of slots formed in said stator core are formed in said inner circumferential surface of said stator core, said openings are plugged with slot wedges, said slot wedges comprise fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin which is reinforced with carbon fiber or glass fiber or aramid fiber, and surfaces of said slot wedges for holding said can comprise circular arc surfaces so as to continue from said cylindrical inner surface of said stator core without any difference in level.

[Claim 12]

A canned electric rotating machine according to any one of claims 2 to 11, wherein a cooling means is provided to cool a stator chamber enclosed by said can by circulating cooling medium into said stator chamber from a compressor.

[Claim 13]

A canned electric rotating machine according to any one of claims 2 to 12 , wherein a pressure vessel for detecting pressure balance is provided to draw a pressure of said cooling medium in said stator chamber and a pressure of a fluid in a rotor chamber surrounded by said can into said pressure vessel, and a pressure balancing means is provided to balance said pressure of said cooling medium in said stator chamber and said pressure of said fluid in said rotor chamber by adjusting a pressure of said cooling medium supplied to said stator chamber from said compressor.

[Claim 14]

A canned electric rotating machine comprising:

a cylindrical frame;

a can configured to enclose said stator; and

a rotor rotatably provided in a space surrounded by said can;

wherein said can comprises a thin metal plate; and wherein said can is held in close contact with an inner circumferential surface of said stator core, and is held by inner ■ circumferential surfaces of frame side plates provided on both end portions of said cylindrical frame and inner circumferential surfaces of reinforcing ring members comprising cylindrical fiber-reinforcedplastics providedbetween said frame side plates and said stator core.

[Claim 15]

A canned electric rotating machine according to claim 14, wherein said fiber-reinforced plastics of said reinforcing ring member comprises fiber-reinforced plastics comprising polyether ether ketone (PEEK) resin or polyimide resin which is reinforced with carbon fiber or glass fiber or aramid fiber.

[Claim 16]

A canned electric rotating machine comprising:

a cylindrical frame;

a can configured to enclose said stator; and

a rotor rotatably provided in a space surrounded by said can;

wherein openings of slots formed in said stator core are plugged with slot wedges which are held in close contact with an outer circumferential surface of said can; and

said slot wedges have a. cutaway portion at a side opposite to an inner circumferential surface of said stator core.

[Claim 17]

A canned electric rotating machine according to claim 16 wherein said cutaway portion of said slot wedge is arch-shaped

[Claim 18]

A canned electric rotating machine according to claim 16 wherein said slot wedge comprises machineable ceramics.

[Claim 19]

A canned electric rotating machine according to claim 16 wherein said slot wedge comprises a fiber-reinforced plastics [Claim 20]

A canned electric rotating machine according to claim 16, wherein a magnetic wedge is disposed between said outer circumferential surface of said can and said slot wedge.