JPS62185528A - Rotary electric machine - Google Patents

Abstract

PURPOSE:To effectively prevent gas generated from an insulator of a stator winding side from invading into the case of an opposite side equipment by separating a rotor side from a stator side through gas shielding case. CONSTITUTION:A bottomed cylindrical gas shielding case 15 made of a nonmagnetic material hermetically sealed with the wall of an opposite side case 1 at a hole end by surrounding a rotary shaft 9 by a rotor 13 is interposed between a rotor 13 and a stator 14. The rotor 13 side and the stator 14 side are separated through the case 15 to prevent the gas generated from an organic insulator of the stator 14 side from invading into the case 1 of the opposite side equipment through the rotor 13 side.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to the configuration of a rotating electrical machine intended for use as a drive motor of a reverse Stirling cycle refrigerator, for example.

[Prior art and its problems]

In refrigerators that obtain extremely low temperatures, such as the above-mentioned reverse Stirling cycle refrigerator, helium gas is often used as a refrigerant. Moreover, since the molecules of this heliu gas are extremely small, gas leakage is likely to occur even if there is a slight gap, so sufficient consideration must be taken when handling it. Another problem with the cryogenic refrigerators mentioned above is that if a different type of gas mixes with the refrigerant gas during operation, the mixed gas will solidify in the low-temperature section during the refrigeration cycle, causing, for example, clogging of the regenerator, etc. This causes a decrease in the heat exchange capacity and, ultimately, the cooling capacity of the refrigerator, so sufficient attention must be paid to this aspect. By the way, an electric motor is generally used to drive the refrigerator, but due to the properties of helium gas as a refrigerant, it is difficult to install an electric motor with a general structure outside the crankcase of the refrigerator, which is filled with refrigerant gas. If a crankcase such as a compressor is connected to the output shaft of an electric motor that penetrates the wall of the crankcase and is inserted into the crankcase, fine particles such as the case shaft seal of the motor shaft and the motor bearing may be connected as is. There is a risk that refrigerant gas may leak out of the case through the gap, and for this reason, a conventional method has been adopted in which the entire electric motor is housed inside the crankcase of the refrigerator to prevent refrigerant gas from leaking out of the system. On the other hand, organic materials such as resin and varnish are generally used as insulators for the windings of rotating electric machines, especially the armature windings on the stator side, where the winding arrangement structure is complicated. As is well known, gas is released due to the heat generated when rotating electric machines operate. For this reason, in the configuration where the entire motor is housed inside the refrigerator case as described above, if the amount of gas generated from the winding insulation is large, this generated gas will mix with the refrigerant gas, causing the refrigeration problem as described above. This may lead to a decrease in the cooling capacity of the machine.
Ku . Therefore, as one of the countermeasures for the above problem, we have adopted a baking method in which the motor winding insulation is exposed to high temperature for a long time before the motor is assembled into the refrigerator, and the insulator releases emissions during operation after installation. Conventionally, methods for suppressing the amount of gas generated have been known. Although this baking method can reduce the amount of gas generated from the organic insulator, it also dries up the insulator, and if exposed to high temperatures for a long time, the insulation will deteriorate. Therefore, the baking time of the insulator is determined by the balance between the allowable amount of gas generated by the other device and the insulation characteristics required of the rotating electrical machine.
Determining this baking time requires a lot of experimentation with various insulating materials, and the baking time can be several hundred hours even for a small electric motor, requiring a great deal of time and money. This is a major bottleneck in terms of manufacturing process and cost reduction. Another countermeasure is to insert a filter, etc., into the refrigerant circuit of the refrigerator to adsorb gas generated from the insulation of the motor, and to replace this filter periodically. However, this is not necessarily a good idea as it requires multiple steps such as the need to break the refrigerant gas atmosphere each time the filter is replaced. Moreover, when the electric motor is housed and installed in the case of the other device as in each of the above-mentioned systems, the electric motor cannot be easily taken out to the outside, which poses a problem in maintainability. The problem of gas generation from organic insulators mentioned above can occur not only in refrigerator drive motors, but also in generators driven by Stirling engines, and also in equipment that uses electric motors to drive equipment installed in vacuum chambers. However, the gas released from the winding insulation of rotating electric machines causes a decrease in the degree of vacuum within the vacuum chamber. In this way, in rotating electric machines such as motors or generators that are installed and operated in the case of the other device whose interior is in a special gas atmosphere such as refrigerant gas or vacuum, the gas emitted from the winding insulation may reach the other device. The solution to this problem has become a major problem because of the obstacles it poses, and in order to solve this problem, there is a strong desire for the emergence of improvement measures to replace the conventional measures mentioned above.

[Purpose of the invention]

This invention was made in consideration of the above points, and it is possible to prevent gas generated from the insulators of the windings of the rotating electric machine, especially the stator windings, from penetrating into the case of the other device without degrading the characteristics of the rotating electric machine. This type of rotating electric machine is designed to reliably prevent the above-mentioned problems from occurring. It is an object of the present invention to provide a configuration of a rotating electrical machine that can also ease manufacturing conditions.

[Key points of the invention]

In order to achieve the above object, the present invention provides a bottomed bottom made of a non-magnetic material between a rotor and a stator, which surrounds the rotor and the rotating shaft, and whose open end is hermetically coupled to the wall surface of the mating case. By interposing a cylindrical gas shield case and isolating the rotor side and stator side by separating the gas shield case, gas generated from the insulator on the stator winding side is prevented from flowing into the other equipment. This is designed to reliably prevent entry into the case.

[Embodiments of the invention]

FIG. 1 is a block diagram of a rotating electric machine according to an embodiment of the present invention, FIG. 2 is a schematic diagram of a reverse Stirling cycle refrigerator driven by an electric motor, and FIG. 3 is a plan view of FIG. 2. The outline of the configuration of a reverse Stirling cycle refrigerator as an example of the practical application of the rotating electric machine according to the present invention will be described with reference to FIG. 2 is a compressor cylinder configured as a part of case 1, 3 is a compression piston, 4 is an expansion cylinder, 5 is an expansion piston, 6 is a regenerator, 7 is a radiator, and 8 is installed on the side wall of the crankcase 1. The output shaft 9 of the electric motor 8 is pulled into the crankcase, and the crankshaft 10.
The above-mentioned compression piston 3. A refrigerator is configured in connection with the expansion piston 5. Note that the refrigeration cycle of such a reverse Stirling cycle refrigerator is well known, and its explanation will be omitted here. Although the illustrated example shows an integrated type in which the expansion piston 5 is driven by the electric motor 8 together with the compression piston 3, there is also a separate type in which the expansion piston is a free piston. Next, the detailed structure of the electric motor 8 for driving the refrigeration S described above is shown in FIG. is a rotor bearing provided on the output shaft 9, and a gas shield case indicated by the reference numeral 15 is newly interposed between the rotor 13 and the stator 14 according to the present invention. This gas shield case 15 is a bottomed cylindrical case made of non-magnetic metal that also serves as a base for mounting the electric motor, and the rotor 13 described above. The mounting, which surrounds the outer periphery of the output shaft 9 and is formed at its open end, brings the flange portion 15a into close contact with the outer wall surface of the crank case 1 of the refrigerator, which is the other device, and is fixedly supported to the case 1 by the fastening bolts 17. ing. Note that the flange portion 1 is provided on the crankcase side.
A Q IJ song sealing member 18 is attached opposite to the flange 5a to airtightly seal the space between the flange surface and the flange surface. In addition, the bearing 16 on the right side of the figure fits into and is supported by a stepped portion 15b formed on the inner peripheral side of the gas shield case 15, and the bearing on the left side is connected to the open end of the gas shield case 15 via a bearing support 19. It is fastened and supported by bolts 20. On the other hand, the stator 14 is assembled with its stator core attached to the inner periphery of the stator casing 21, and is fitted onto the outer peripheral surface of the body of the gas shield case 15 from the right end side in the direction of arrow P. The flange portion at the left end of the upper stator casing 21 is fastened and fixed to the flange 15a of the gas shield case 15 with fastening bolts 22. According to this configuration, when the rotating electric machine 8 is installed on the outer wall surface of the crank case 1 of a counterpart device, for example, a refrigerator, the rotor side that communicates with the internal space of the case 1 faces the rotor. The stator side is separated from the other by the gas shield case 15. Therefore, even if gas is released from the organic insulator of the winding on the stator 14 side during operation, this generated gas can be completely prevented from entering the case 1 of the other device and mixing with the refrigerant gas. Therefore, it is sufficient to use a lubricant for the bearing on the rotor side, a lubricant that generates less gas, and an inorganic insulating material, paying careful attention to gas generation with respect to the insulator of the rotor winding. Note that cage-type induction motors and the like have a simple rotor structure and are easy to manufacture without using organic insulating materials. Moreover, the stator is located outside the system with respect to case 1, so organic insulating materials can be used freely without being restricted by the special gas atmosphere or vacuum conditions of the other device. Moreover, there is no need for the baking described above, and the machine manufactured in the same manner as a normal rotating electric machine can be used as is. Furthermore, in the illustrated embodiment, the stator 14 and the stator casing 21 are supported on the outer periphery of the body of the gas shield case 15 in a fitting manner.
5 remains fixed to the crankcase 1, the stator 14 can be removed independently without breaking the seal between the stator 14 and the case 1, making maintenance easy for inspections, repairs, etc. . Note that the gas shield case 15
are made of non-magnetic material, and have little effect on the magnetic circuit of the rotating electric machine (it does not affect the operating characteristics, but in order to keep eddy current loss low, the opposing surface of the stator and rotor is It is preferable that the wall thickness of the body part interposed in the rotor is as thin as possible. [Effects of the Invention] As described above, according to the present invention, the rotor and the rotating shaft are surrounded between the rotor and the stator. A bottomed cylindrical gas shield case made of a non-magnetic material whose open end is hermetically coupled to the wall of the other case is interposed, and the gas shield case is interposed between the rotor side and the stator side. By configuring it in isolation, even if gas is generated from the organic insulator on the stator side, this emitted gas can be completely prevented from entering the case of the other equipment through the rotor side. It is possible to easily solve the problem of contamination of insulator-generated gas, which is a major problem in various types of rotating electric machines, and to improve the reliability of three-rotation machines and to ease the design and manufacturing conditions.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of a rotating electrical machine according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a schematic configuration of a reverse Stirling cycle refrigerator, which is an application example of the rotating electrical machine, and FIG. 3 is a plan view of FIG. 2. It is a diagram. In each figure, 1: Crank case of the refrigerator as a counterpart equipment case, 8: Electric motor for driving the refrigerator, 9: Output shaft, 13: Rotor, 14: Stator, 15: Gas shield case, 15a
:Flange part, 16: Bearing, 18: Sea Figure 2 Figure 3

Claims (1)

[Claims] 1) A rotating electric machine that is installed on the outer wall of a case of a counterpart device whose internal space is in a special gas atmosphere or vacuum, and that is operated by connecting a rotating shaft inserted into the case to the counterpart device. A bottomed cylindrical gas shield case made of a non-magnetic material is provided between the rotor and the stator, surrounding the rotor and rotating shaft, and the open end of which is hermetically coupled to the wall surface of the other case. A rotating electric machine characterized in that a rotor side and a stator side are separated from each other by intervening the gas shield case. 2) In the rotating electric machine according to claim 1, the gas shield case has a rotor bearing support part on the inner circumferential side, and a case opening end part for airtight coupling to the case wall surface of a mating device. A rotating electrical machine comprising a mounting flange portion and a stator removably fitted and supported on the outer peripheral surface of a case body. 3) The rotating electrical machine according to claim 1, wherein the rotating electrical machine is a motor for driving a refrigeration device whose case is filled with a refrigerant gas such as helium.