JPH02193546A - Cooling of canned motor - Google Patents

Abstract

PURPOSE:To prevent the deformation of a can and effect efficient cooling by a method wherein cooling liquid is circulated through a space provided between the outer periphery of a stator, enclosed by the can, and the inner periphery of a motor frame while the vapor pressure of the cooling liquid is regulated. CONSTITUTION:A stator cooling gap 10 is formed between a can 6, enclosing the stator core 3 of a canned motor 1, and a motor frame 4. Cooling liquid, entering through an inflow tube 11, is circulated through a stator chamber 8, a gap between a stator 7 and the can 6 and a cooling passage 10 and is returned into a cooler 14 through a discharging tube 12. A heat radiating tube 15 is cooled by a fan 17 in the cooler 14 while a pressure regulating mechanism 16 is provided to regulate the vapor pressure of the cooling liquid. According to this method, the deformation of the can 6 is prevented and efficient cooling may be effected.

Description

[Detailed Description of the Invention] The present invention relates to a method for cooling a canned motor.
It is possible to increase the capacity of the canned motor by effectively cooling the can and wire parts, where heat is generated at a high density, within the sealed structure.

Conventionally, canned motors have a rotor chamber of a drive motor and a driven body in order to completely avoid leakage of compressed, pumped, or liquid fluid from a shaft sealing device of a driven body such as a compressor or pump. At the same time, a thin metal cylindrical can is attached to the inner periphery of the stator of the motor, completely sealing it against the outside air.

Canned motors are used when dealing with special fluids such as conductive, corrosive, and toxic.

Here, if the canned motor has a small capacity, the amount of heat generated due to loss in the stator and rotor parts is small, so there may be no particular need for cooling, or it is easy to use the target fluid. As the capacity increases, the temperature of the target fluid increases when the target fluid is cooled by flowing through the rotor chamber, increasing the load on the cold part of the driven body and reducing the overall efficiency including the motor. It also results in a significant reduction, making its cooling function difficult. On the other hand, a method has been developed in which the outer periphery of the frame is heated with cold water or the like in order to avoid such a drop in efficiency. Therefore, there is little hope of a sufficient cooling effect.

The present invention has been made with the above points in mind, and includes a method in which a coolant unrelated to the target fluid of the driven body is brought into contact with and circulated on the back surface of the can, the stator coil, and the outer periphery and side surfaces of the stator core. As a method of suppressing pressure deformation of the can due to the cold section liquid pressure, select a liquid whose evaporation temperature is around room temperature, or suppress the deformation pressure to below the allowable deformation pressure of the can using a pressure regulating mechanism. This is how it was done.

The above will be explained with reference to the drawings.

FIG. 1 shows a canned motor compressor in which a canned motor according to the present cooling method is combined with a compressor, in which (a) is a side sectional view and (b) is a Y--Y sectional view thereof.

In the figure, 1 is a canned motor that drives the compressor 2, 3 is a stator core fitted with the frame rib 13 of the motor frame 4 as a guide, and 5 is a stator wire wound around the national stator core 3. A ring 6 is a thin metal cylindrical can attached to the inner periphery of the stator core 3, and forms a boundary between the rotor chamber 8, which is transmitted by the rotor 7, and the outside air, forming a sealed structure. The cans 6 on both sides of the stator core cannot withstand the rotor chamber pressure with their thickness alone, so their outer periphery is reinforced with reinforcing tubes 9.
reinforced with.

An inlet pipe 11 and a discharge pipe 12 for cold liquid are attached to the motor frame 4. A stator cold section gap 10 is formed between the outer periphery of the stator core 3 and the motor frame 4 by the frame ribs 13, and thus serves as a flow path for the cold section liquid.

Figure 2 shows the cooling fluid circulation system, and the canned motor 1
The upper discharge pipe 12 is connected to the upper part of the heat radiation pipe 15 of the cooler 14, and the inflow pipe 11 is connected to the lower part thereof. In addition, the pressure regulating mechanism 16 is used to suppress pressure when the cold part liquid expands or evaporates in the circulation system and high pressure is generated due to gasification.
will be provided. The pressure regulating mechanism 16 may be a mechanical one such as a pressure regulating bag made of an elastic material or a variable volume structure using a piston type with a rigid structure, or a special one may be one that evaporates at around room temperature. A refrigerant such as Freon 112, which is difficult to absorb and has a low saturated vapor pressure, may also be used. Alternatively, the structure may be open to the outside air through a hole.

Canned motor cans have a thickness of about 1 m/m or less to withstand the internal pressure in the rotor chamber, so the inner periphery of the stator core and the outer periphery of the can are surrounded by a reinforcing tube. Although the strength is not affected, it is easily crushed by external pressure, and the above-mentioned deterrent method is taken.

Due to the structure of the canned motor as described above, the cold liquid is filled between the inside of the frame and the can, and circulates around the outer periphery of the can, the stator coil, the outer periphery of the stator core, and its sides. Heat exchange takes place in direct contact with the refrigerant liquid.

In particular, the heat generated by the can tends to cause a temperature rise because the heat capacity of the can itself is small due to its structure, but the cooling effect of the cold part liquid is direct and therefore large. The heat generated by the rotor is transferred to the can and the stator core via the evaporated gas of the target fluid accumulated in the rotor chamber, and is cooled by the aforementioned cold section liquid.

The specific gravity of the cold part liquid decreases due to the heat generated by the motor, rises from the discharge pipe 12, flows from above the heat radiation pipe 15 of the cooler 14, is air-cooled by the air blower 1117, and enters the intake port 11 from below the heat radiation pipe 15. It flows through the water and circulates.

In this case, the cold liquid is circulated through a heat pipe, and a circulation pump is not particularly required, but if the pump is used to perform forced circulation, the cooling effect will be even better.

Since the present invention is constructed as described above, cooling of the canned motor is extremely high because the stator core, its wires, cans, etc. are cooled by directly circulating the cooling liquid.
Canned motor by suppressing external pressure using cold liquid
It becomes easy to increase the capacity of

[Brief explanation of the drawings] Part 1 (A) is a side cross-sectional view of the canned motor pressurizer, (B) is its Y-Y cross-sectional view, and Figure 2 is the cold section liquid circulation system section. It is. l: Canned motor 2: Compressor, 3: Stator core, 4
: Motor frame, 5: Stator coil, 6: Can, 7
: Rotor, 8: Rotor chamber, 9: Reinforcement cylinder, 10: Stator cooling gap, 11: Inflow pipe, 12: Discharge pipe, 13: Frame rib, 14: Cooler, 15: Heat dissipation pipe, 16: pressure regulating mechanism,
17: Cooling fan.

Claims (1)

[Claims] (1) In a canned motor in which a thin metal cylindrical can is attached to the inner circumference of the stator, a gap is provided between the outer circumference of the stator and the inner circumference of the frame, and cooling is carried out in the space between the inner circumference of the frame and the outer circumference of the can. 1. A method for cooling a canned motor, characterized in that cooling is performed by filling and circulating a liquid and suppressing pressure deformation of the can due to the pressure of the cooling liquid.