JPH1070858A - Rotating electric machine with hollow rotor - Google Patents

Abstract

(57) [Summary] (Modified) PROBLEM TO BE SOLVED: To provide a runner, impeller, impeller, etc. for fluid transfer.
Newly-structured rotary electric motor with a hollow rotor having functions
Provide a machine. SOLUTION: A stator winding (12) is wound around the periphery.
Between a cylindrical rotor (10) and the stator winding (12)
Cylindrical electromagnetic action generator (2)
And a hollow rotor (20) provided with 2).
The trochanter (20) is rotatable inside the cylindrical stator (10).
A rotating electric machine with a hollow rotor fitted in Noh
It is solved. Inside this hollow rotor (20)
Forms blades, wings, screws, etc. for fluid transfer, for example
can do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating electric machine having a novel structure, such as a motor or a generator, and more particularly to a rotating electric machine having a hollow rotor. Used here,
The term "hollow" in a hollow rotor means that the electromagnetically acting part is not included in the rotor, and elements that perform other functions, such as blades and wings that act on a fluid Alternatively, the existence of a structure for relatively moving the target object is not denied.

[0002]

2. Description of the Related Art An ordinary electric motor that converts electric energy into mechanical energy and extracts power from the motor extracts mechanical power from a rotating shaft. The mechanical power taken from the rotating shaft is added to the load and performs the intended work.

[0003] Normal loads transmit power by direct connection via various couplings, connection via gear transmission means, or connection via belts or chains via pulleys or sprockets.

[0004] Therefore, the hollow rotor motor cannot take out the mechanical power and is not suitable for the above-mentioned applications. In addition, ordinary generators that convert mechanical energy into electric energy add kinetic energy, which is rotational power from hydraulic power, steam power, wind power, internal combustion power, and other sources, convert energy inside the generator, and output electric energy. Is what you do. Therefore, even a generator without a rotating shaft cannot input external power, so that it does not fit in conventional equipment as in the case of a motor.

[0005] However, there are many applications in which the existence of such a rotating shaft or the center of a solid rotor is an obstacle. For example, blowers, fans, windmills or pumps for fluid transfer,
In a device such as a water turbine, the presence of a rotating shaft forcibly changes the flow direction of a fluid to be transferred by a blade or a runner, which is a major cause of an increase in loss. The same applies to a rotating body or the like of a movable part that performs positioning while rotating on a screw.

Even in a so-called axial flow type pump or blower having a rotary impeller or a propeller, in order to avoid an increase in fluid resistance due to the presence of an electric motor, a forced change in the flow path direction is performed, It is indispensable to consider that the main body of the rotating electric machine with the impeller is surrounded by a streamlined cover and disposed directly in the flow path.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a rotating electric machine having a hollow rotor to which functions such as a runner and an impeller for transferring fluid can be added. The task is to provide.

[0008]

An object of the present invention is to provide a cylindrical stator 10 having a stator winding 12 wound therearound as shown in FIGS. 1 (A) and 1 (B). , The stator winding 12
And a hollow rotor 20 having a cylindrical electromagnetic action generating portion 22 for generating an electromagnetic action between the hollow rotor 2 and the hollow rotor 2.
0 is solved by a rotating electric machine having a hollow rotor rotatably disposed inside the cylindrical stator 10.

In the above construction, the cylindrical stator 10
It is desirable to provide a bearing at at least one position between the inner surface of the hollow rotor 20 and the outer surface of the hollow rotor 20.

Such a bearing may be a contact type bearing for reducing mechanical friction, for example, a ball bearing, a roller bearing, a needle bearing, a plastic bearing, etc., and a non-contact type utilizing a magnetic repulsion force. Magnetic bearing.

The hollow rotor in the present invention means that the rotor of the rotating electric machine is hollow.
A configuration required for other functions can be added directly or detachably to the inside thereof. For example, a predetermined number of blades, wings, and projections corresponding to a fluid can be provided inside the above-described hollow rotor. These blades, wings, projections, and the like can be liquid-compatible structures or gas-compatible structures, respectively.

Although such a rotating electric machine can be configured as an electric motor, it can also be a generator such as a water turbine or a wind turbine that inputs kinetic energy by a fluid.
The hollow rotor in each of these configurations has a cage-shaped rotating body in which a cage-shaped conductor made of a good conductor is surrounded by another metal or a non-metallic material having different conductivity, and has a plurality of magnetic projections arranged in parallel around the rotating body. A toothed rotor or a permanent magnet rotating body in which a required number of appropriately shaped permanent magnets are embedded in a cylindrical non-magnetic material can be used.

When a rotating electric machine having such a hollow rotor is used as an electric motor, it is possible to form a rotating portion such as a pump, a blower, a blower, a fan, etc. inside the motor rotor as it is. it can. Therefore,
It is possible to reduce the size and simplify the entire structure in which both are integrated. In such a structure, since the moving direction of the fluid is almost straight, the loss in the flow path due to the forced flow path change can be greatly reduced.

The same structure can be adopted when the rotating electric machine according to the present invention is a generator, and the same effect can be expected by using a structure in which torque is generated by fluid motion inside the rotor. it can. In the case where the rotor is configured as a generator, the rotor is usually of a permanent magnet embedded type in many cases, and can be a relatively small device. By installing the device configured as described above in a liquid fluid pipeline or a gaseous fluid pipeline, power can be easily generated. However, it is also possible to use it in the form of an induction generator as a cage rotor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings showing embodiments, but does not limit the scope of the present invention. FIG. 1A shows an example of a basic configuration of a stator 10 and a hollow rotor 20 fitted into the stator 10 in a rotary electric machine having a hollow rotor according to the present invention, and FIG. 1B shows a hollow rotor 20. FIG. 2 is a perspective view schematically showing the configuration of FIG. The following embodiment mainly describes a form of an electric motor.

FIG. 1A shows a state in which a stator winding 12 is wound around an outer surface of a cylindrical body 11 made of a suitable material such as plastic or non-magnetic metal. , Such as three-phase, six-phase, etc., a rotating magnetic field generating winding by polyphase alternating current, a moving magnetic field winding by single-phase alternating current, an alternating magnetic field winding by alternating-current conversion, and sequentially generating a traveling magnetic field by pulse. Stepping motor winding, reluctance motor winding, SR (Switched Relutanc)
e) Although it may be a motor winding or the like, it is schematically shown here as a simple cylindrical body.

By supplying a necessary current to the stator winding 12 from a power source (not shown), a rotating magnetic field, a moving magnetic field, an alternating magnetic field, and the like are generated. In addition,
The end of the tubular body 11 may have a structure according to the application, for example, a structure suitable for connection to a pipe or a structure for attaching to a casing. Also, the connection may be appropriately made via an adapter or a union coupling.

In this case, the power supply may be a polyphase AC power supply, or a variable power supply such as an inverter or the like formed by a control rectifier such as a thyristor and other elements. If such an inverter is used, the rotating magnetic field and the moving magnetic field have variable speeds, and the adjustment of the rotating speed as the electric motor can be easily performed, and the applicable range is expanded. Further, it may have the same structure as a single-phase induction motor that uses a leading or lagging current to form a moving magnetic field. further,
As described above, the pulse generator can be used as a drive source and configured as a stepping motor.

Inside the cylindrical body 11, bearings 14A and 14A are provided.
It is desirable that B be provided to support the outer surface of the hollow rotor 20 or a hollow shaft portion having a diameter slightly smaller than the diameter of the rotating body. Depending on the type of low-speed rotation device and bearing type,
It is also possible to use only one of them, or to add a bearing function to the structure of the rotor. The stator winding 1
2 can be divided into two parts, and one bearing can be provided at the center. Further, in an application such as a pump that rotates in a fluid, it can be made of a hard and low-slip resistance engineering plastic such as polytetrafluoroethylene (PTFE) or polyacetal (polyoxymethylene: POM).

FIG. 1B is a perspective view showing the basic structure of the hollow rotor 20. The vicinity of the center of the cylindrical body 21 of a suitable material, for example, a plastic or other non-metallic material or a non-magnetic metal such as an aluminum alloy,
The electromagnetic action generating section 22 is formed at a portion corresponding to the area 2.
The electromagnetic action generating section 22 can be, for example, a cage made of a good conductor. When such a cage is used, the tubular body 21 can be made of a thermoplastic or thermosetting synthetic resin or a metal having lower conductivity than the cage.

In consideration of the type of the fluid to be transferred, for example, an engineering plastic which is excellent in solvent resistance, chemical resistance, etc., and is hard and has low slip resistance, such as PTFE or POM as described above, is used. It can also be configured. By selecting such a material, the rotor cylindrical body 21 itself can be configured as a part of the bearing.

Another example of the configuration of the cylindrical electromagnetic torque generating section 22 can be formed by bar-shaped permanent magnets embedded in parallel along the axial direction. The rod-shaped permanent magnets can be disposed with the direction slightly inclined from the axial direction. Such a structure is effective for smoothing the torque in the case of the electric motor and for reliably generating the starting torque. In the case of a rotor using such a permanent magnet,
Operates as a synchronous machine, stepper motor or brushless DC machine.

In this brushless DC machine, as is well known, a direct current is applied to the stator winding from the outside, the magnetic pole position of the rotor is detected by a magnetic sensor such as a Hall element, and at each position, attraction / repulsion is performed. The current is controlled so as to generate the rotation torque. Note that a stepping motor using a pulsed current, a reluctance motor, or an SR motor can also be used.

The cylindrical electromagnetic action generating section 22 is provided with a cylindrical body 21 as much as possible in order to enhance the use efficiency of electromagnetic energy.
It is desirable to provide it near the outer surface. Although it depends on the type of the surrounding fluid on which the rotor 20 is placed, if there is no problem such as a chemical attack by the surrounding fluid, a structure in which a part of the outer surface is exposed may be employed.

It is to be noted that a cylindrical electromagnetic action generating section 22 combining both the above-described cage conductor and the rod-shaped permanent magnet may be used. By combining both structures, various characteristics such as starting characteristics, rotation speed,
A hollow rotor electric motor exhibiting torque, braking characteristics, and the like is obtained.

In this hollow rotor 20, internal bearing members 24A and 24B are provided at portions corresponding to the bearings 14A and 14B when fitted inside the stator 10. Naturally, it is provided at a corresponding part between the stator 10 and the rotor 20, and the mounting part is designed according to each use.

FIG. 2 shows that a suitable number of blades 26 are formed from the inner wall surface of the hollow rotor 20 toward the center toward the fluid. The blade 26 differs depending on the size of the inner diameter of the hollow portion of the rotor and the type of the target fluid, for example, gas or liquid. In addition, considering the specific gravity and viscosity of the fluid, the shape,
Dimensions, number, pitch, slope, curvature, etc. can be changed. In addition, the structure of the cylindrical body 21 of the hollow rotor 20 and the structure of the blade 26 to be inserted are prepared separately, for example, a ridge formed between them and a fitting structure such as a groove corresponding thereto,
It can be configured to be integrated by screwing or bonding.

With such a configuration, the standard hollow rotor 20 manufactured in advance can be adapted to various applications by combining the structure of the blades 26 having different structures and characteristics for each application. It can be configured such that it can be replaced even when it is worn or broken. In any case, the need to adjust the rotational balance of the completed hollow rotor 20 is the same as in the case of a normal rotating body. However, since the structure is supported not from the center axis but from the outside, the influence of the centrifugal force is small, so that the generation of vibration is slight.

The hollow rotor 20 is connected to the cylindrical body 11 of the stator 10.
The bearings 14A, 14B and 24A, 24B for supporting at a predetermined position should be determined in consideration of the type of the target fluid and its physical and chemical properties as described above.
Well-known bearings, for example, contact bearings such as ball bearings, roller bearings, and needle bearings made of steel, sintered metal, or other special metals can be used. When the fluid is air or another normal gas, these bearings can be appropriately selected and used.

However, care must be taken when the fluid contains a corrosive component such as a strong acid or strong alkali, or when it is a gas-liquid mixture. If such a problem exists, use a corrosion resistant material such as PTFE or PO as described above.
Materials with high resistance to chemical attack, such as M, and lubrication systems must be considered.

Further, when the target fluid is a liquid, it is necessary to particularly consider the configuration of the bearing unless the flowing liquid is a high-quality oil. Similar considerations are also required when it is not convenient to mix a lubricant into a target fluid such as a liquid for drinking or medical use.

As described above, when the use of the contact bearing becomes a problem, a magnetic bearing can be adopted. The magnetic bearing is provided with a permanent magnet magnetic pole at a desired position of the hollow rotor 20, and is provided in a non-contact manner by a repulsive force acting between the rotor side magnetic pole and the same polarity magnetic pole attached to the stator 10. Is a structure held at a predetermined position.

Although such magnetic bearings are currently expensive, they can also be used in applications that are unsuitable or unsuitable for use with the contact bearings described above.

[0034] Inexpensive contact type bearings can be used for fluids such as air which do not cause any particular trouble. For example, contact bearings may be applied to various fans and blowers.

The electric motor having a hollow rotor according to the present invention is used in a case where the transfer fluid is a gas. -It can be applied to cooling fans for electronic equipment. Further, the hollow rotor can be formed extremely short and used as a small cooling fan attached to a semiconductor integrated device.

When the fluid is a liquid, it may be used as a so-called in-line pump or a pump for suction / discharge / stirring at the connection between the tanks and the piping, which is disposed in the middle of the pipe. Can be used as an agitator. Such an in-line pump can be easily disposed at appropriate positions such as horizontal, inclined, and vertical sections of piping, and efficient liquid transfer is possible because there is no change in the fluid flow path. Becomes For example, the present invention can be applied to a use where the stagnation of contents is prevented by disposing the pipe at a low place of a pipe.

In this case, fresh water, edible oil, fuel oil, various chemicals / bloods, alcohols, juices, other drinking waters, etc. can be obtained by appropriately considering the materials of the hollow rotor and the stator-side cylindrical body. It can be advantageously used for seasonings such as soy sauce and sauces, water supply, sewage, liquid fertilizers and the like. In terms of capacity, it can handle both large and small,
In particular, it is advantageous for miniaturization. For example, as a liquid transfer pump in a vending machine, there is no risk of liquid leakage or contamination due to mixing of other objects, and safe liquid transfer is possible.

When the rotating electric machine having the hollow rotor according to the present invention is used as a generator, an induction motor using a cage rotor or a synchronous generator using a permanent magnet rotor can be used. In such an application as a generator, the shape and structure of the blades inside the hollow rotor 20 need to be adapted to the type of target fluid, high-speed fluid such as water and steam, wind, and the like. . Rotational power proportional to the product of the flow rate and flow rate of the gas or liquid is obtained, and this is converted into electric energy in the stator winding and output. The generated power is AC, but especially in induction generators.
Must be linked to another reference generator or grid.

With a generator having a hollow rotor having such a structure, it is possible to generate electric power by connecting in-line at an appropriate position in a pipeline. This electric power does not necessarily mean a large electric power, and can be applied to, for example, an application that requires a power source such as measurement, control, transmission, or lighting at an appropriate position in a long-distance pipeline. In such an application, power supply wiring, battery equipment, and the like are not required.

As a primary use of the generator, a small dam can be easily formed by forming a small dam for blocking the water flow and installing the generator. Simple power generation facilities can be constructed in mountainous areas or in areas without power. It can be applied to secure power supply in mountain huts, campsites, villas, etc. Also, tidal currents and wave forces can be used on the beach.

The rotating electric machine having a hollow rotor according to the present invention can be applied to various modes. Therefore, the shapes of the stator 10 and the hollow rotor 20 can be modified not only to be cylindrical but also to adapt to each. The inner and outer shapes of the hollow rotor 20 are, for example, a trumpet shape, a two-stage shape with different diameters, a barrel shape, and an intermediate diaphragm as shown by a solid line with respect to a cylindrical outer shape shown by a broken line as shown in the side view of FIG. An appropriate internal shape such as a shape can be adopted.

The electromagnetic action generating portion 22 and the bearing member as the internal structure can be provided in the portion surrounded by the broken line and the solid line inside and outside. Further, the shape inside the hollow portion should be selected in consideration of the contents such as simple transfer, compression or discharge of the fluid. For example, when compressing a fluid, the fluid is sucked from the large diameter side and compressed while passing through the small diameter side. The outer shape can also be appropriately changed. For example, when a part is used as an internal member of the bearing, a small-diameter portion is formed, and the shape can be formed so as to be fitted into a part of the stator-side cylindrical body.

Further, as shown in FIG. 4, it is possible to adopt a structure in which a hollow rotor 20 is mounted around a hollow rotary shaft 28 having a fluid transfer blade 27 or a blade therein. In such an offensive, the bearing 24 is placed at an appropriate position on the hollow shaft 28.
C and 24D can be provided. Such a structure can be particularly advantageous as a small-sized fluid transfer device, for example, a filter pump for breeding appreciation fish, a vending machine pump, and other fluid transfer pumps. Of course, it can also be configured as a gas transfer fan or a blower.

[0044]

According to the rotating electric machine having the hollow rotor according to the present invention, since the inside of the rotor is hollow, functions such as air and other various gases, such as air and the like, for achieving a desired object, A blade for transferring a fluid such as a liquid,
Wings and propellers can be formed directly. Therefore, the pump, fan,
It functions as a blower, water turbine, turbine, etc. for that reason,
There is no loss in power transmission unlike conventional equipment, and the occurrence of loss due to forced change of the flow path is avoided. In addition, since there is no leakage of the fluid in the rotary shaft penetrating portion or the like, safe and efficient fluid transfer can be achieved.

According to the fluid transfer device using the rotating electric machine having the hollow rotor according to the present invention, a series coupling (in-line) can be achieved by using an appropriate coupling that does not cause leakage at an appropriate position of the fluid pipe. Can be installed. Therefore, it is possible to install a plurality of devices at appropriate intervals in the fluid pipe, and cascade operation becomes possible. for that reason. It is also suitable for transferring fluids containing highly viscous fluids or substances that easily precipitate.

In such a fluid transfer pump, a special fluid, for example, a strong acid or a strong alkali, or other toxic or harmful substances can be obtained by appropriately selecting a material and a structure of the cylindrical body on the stator side and the hollow rotor. And a chemical pump suitable for the transfer of water. In addition, applications that dislike the inclusion of other substances, such as seasonings such as sauces, soy sauce, mirin,
It is also suitable for transferring edible oils, milk, alcoholic beverages, drinking water such as juice and cola, and the like. In addition, since there is no penetrating portion of the drive shaft and the like, and it has a closed structure, it can be applied to highly volatile fuels and chemicals. In various applications, it is possible to bury the whole in these liquids and use it by making the stator structure a completely closed structure.

Further, the fluid transfer device including the rotating electric machine having the hollow rotor according to the present invention can be configured for gas. It can be used as a ventilation fan or a roof fan. It can also be applied to home appliances such as futon dryers, hair dryers, air conditioners, etc., which are arranged between the suction unit and the dust collection unit to constitute a vacuum cleaner, arrange a heat source and combine it with this. .

Further, the present invention can be used as a small-sized cooling apparatus directly incorporated in small-sized electronic devices or these components. In such an application, since there is no change in the flow path of the fluid, the flow resistance is greatly reduced, the fluid can be efficiently transferred, and the apparatus can be downsized and energy saving can be achieved as a whole.

If the rotating electric machine having the hollow rotor according to the present invention is applied as a generator, a small-sized water turbine generator and other high-speed fluid generators can be formed with a very simple configuration. For example, in a fluid transfer pipe, power generation can be performed in accordance with the flow of the fluid in the pipe by in-line connection to an appropriate portion in the pipe.

The obtained power can be used as a power source for measurement, control, and remote transmission, including lighting, electric heating, and motor driving. It is also possible to use a power supply for preventing freezing and a power supply for transmitting information in a long-distance pipeline or a facility piping in a cold district plant. In this case, by making the stator side completely waterproof, it can be buried in liquid and used for operation or buried underground. For example, it can be placed on a small river or a beach, and can generate electric power using flowing water accompanying water current or wave power / tidal current.

[Brief description of the drawings]

FIG. Figures (A) and (B) show hollow rotation according to the present invention.
FIG. 3 is a perspective view showing a basic configuration of a rotating electric machine having a child.

FIG. 2 Of a rotating electric machine having a hollow rotor according to the present invention.
It is a perspective view showing the example of composition of a hollow rotor.

FIG. 3 Figures (A) to (D) show the hollow circuit according to the present invention.
It is a side view which shows the example of a shape of a trochanter.

FIG. 4 5 shows another example of the shape of the hollow rotor according to the present invention.
It is a front view.

[Explanation of symbols]  10 Hollow rotor 11 Cylindrical body  12 Stator winding  14A bearing  14B bearing  20 hollow rotor  21 cylindrical body  22 Electromagnetic action generator  24A bearing 24B bearing 26 blade 27 blade 28 hollow bearing  24C bearing 24D bearing

Claims (21)

[Claims] A cylindrical electromagnetic device for generating an electromagnetic action between a cylindrical stator (10) having a stator winding (12) wound therearound and said stator winding (12). Action generator (2
And a hollow rotor (20) provided with 2), wherein the hollow rotor (20) is rotatably fitted into the cylindrical stator (10). Rotating electric machine having a child. 2. A bearing (14A, 14B; 24A, 24B) is provided on at least one of an inner surface of the cylindrical stator (10) and an outer surface of the hollow rotor (20). A rotating electric machine having the hollow rotor according to claim 1. 3. The rotating electric machine having a hollow rotor according to claim 2, wherein the bearing is a contact type bearing for reducing mechanical friction. 4. The rotating electric machine having a hollow rotor according to claim 2, wherein said bearing is a magnetic bearing utilizing mutual repulsion of magnetism. 5. A predetermined number of fluid blades (26) are provided on an inner surface of the hollow rotor (20).
A rotating electric machine having the hollow rotor according to claim 1. 6. The rotating electric machine having a hollow rotor according to claim 5, wherein the fluid blade formed on the inner surface of the hollow rotor has a liquid-compatible structure. 7. The rotating electric machine according to claim 5, wherein the fluid blade formed on the inner surface of the hollow rotor (20) has a structure corresponding to gas. 8. The rotating electric machine having a hollow rotor according to claim 1, wherein the rotating electric machine is configured as an electric motor. 9. An electromagnetic action generating section (2) of the hollow rotor.
9. Hollow according to claim 8, characterized in that 2) is formed as a squirrel-cage rotor and is configured as an induction motor generating a rotational force by a rotating magnetic field generated by the stator winding (12). A rotating electric machine having a rotor. 10. An electromagnetic action generating section (2) of the hollow rotor.
2) The synchronous motor, wherein 2) is formed as a hollow rotor in which a permanent magnet is embedded, and is configured as a synchronous motor that generates a rotating force by a rotating magnetic field generated by the stator winding (12). A rotating electric machine having the hollow rotor according to claim 8. 11. An electromagnetic action generating part (2) of the hollow rotor.
2) is formed as a hollow rotor in which a permanent magnet is embedded, and the current of the stator winding (12) is changed according to the position of the magnetic pole of the permanent magnet embedded in the rotor, thereby producing a rotational force. The rotating electric machine having a hollow rotor according to claim 8, wherein the rotating electric machine is configured as a brushless DC motor that generates the electric current. 12. The hollow rotor according to claim 8, wherein the fluid blade formed on the inner surface of the hollow rotor is formed as a pump rotor. A rotating electric machine having 13. The blade according to claim 8, wherein the fluid blade formed on the inner surface of the hollow rotor (20) is formed as a blower blade for a vacuum cleaner. A rotating electric machine having a hollow rotor. 14. The hollow rotor according to claim 8, wherein the fluid blade formed on the inner surface of the hollow rotor is formed as a blade of a ventilation fan. A rotating electric machine having 15. The hollow body according to claim 8, wherein the fluid blade formed on the inner surface of the hollow rotor is formed as a blower blade for an electrostatic precipitator. A rotating electric machine having a rotor. 16. The hollow rotary body according to claim 8, wherein the fluid blade formed on the inner surface of the hollow rotor is formed as an air-conditioning blower blade. Rotating electric machine having a child. 17. A fluid blade formed on an inner surface of the hollow rotor (20) is formed as a blower blade for a futon dryer. A rotating electric machine having a hollow rotor. 18. The hollow rotor according to claim 8, wherein the fluid blade formed on the inner surface of the hollow rotor is formed as a blower for a hair dryer. Rotating electric machine having a child. 19. The rotating electric machine having a hollow rotor according to claim 1, wherein the rotating electric machine is configured as a generator. 20. The rotating electric machine having a hollow rotor according to claim 19, wherein the fluid blade formed on an inner surface of the hollow rotor is formed as a runner of a water turbine. 21. A rotating electric machine having a hollow rotor according to claim 1, wherein a hollow shaft (28) is provided inside the hollow rotor (20).