JPH11132581A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerator comprising a multistage compressor being driven through a motor, a condenser for condensing gas refrigerant delivered from the multistage compressor, an intermediate cooler for cooling the condensed liquid refrigerant by reducing the pressure, and an evaporator for evaporating the liquid refrigerant flowing out from the intermediate cooler in which the motor can be cooled effectively without lowering the efficiency thereof. SOLUTION: The casing 34 of a motor 2 is partitioned into a stator chamber 41 for containing a stator 3 and a rotor chamber 42 for containing a rotor 4. Supercooled refrigerant extracted from an evaporator 5 and boosted by a liquid refrigerant pump 44 is fed to the stator chamber 41 in order to cool the stator 3. It is then returned back to a refrigerant circuit in the downstream of an intermediate cooler 7 feeding gas refrigerant to the rotor chamber 42 in order to cool the rotor 4. The gas refrigerant is returned back to the intermediate suction port 23 or the first stage suction port 22 of a multistage compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a refrigerator.

[0002]

2. Description of the Related Art An example of a conventional refrigerator is shown in FIG. When the refrigerator is operated, the discharge port of the multi-stage turbo compressor 1
The high-pressure gas refrigerant discharged from 21 enters the condenser 6 via the discharge pipe 10, where it is condensed and liquefied by radiating heat to a cooling medium such as cooling water flowing through the heat transfer pipe 18.

The liquid refrigerant is extracted from the liquid reservoir 14 and enters the intercooler 7, where the liquid refrigerant is partially evaporated by being throttled to the intermediate pressure by the high-pressure side throttle mechanism 24. After separating the droplets in
The air is sucked into the multi-stage turbo compressor 1 through the intermediate suction port 23 through the intermediate suction valve 8 interposed therebetween, and is compressed by the second-stage impeller 28.

The remaining liquid refrigerant not evaporated in the intercooler 7 is cooled by the latent heat of evaporation, and then cooled by the low-pressure side throttle mechanism 25.
As a result, the flow rate is adjusted and the adiabatic expansion is performed, thereby forming a low-pressure gas-liquid two-phase.

This refrigerant enters the evaporator 5 where the heat transfer tubes 16
By absorbing heat from a medium to be cooled such as brine or cold water flowing through the inside, it evaporates and evaporates to become a low-pressure gas refrigerant, and passes through the suction pipe 9 to the multi-stage turbo compressor 1 at its first-stage suction port 22.
And is compressed by the first-stage impeller 27 and the second-stage impeller 28 via the inlet vane 15.

The impellers 27 and 28 of the multi-stage turbo compressor 1 are fixed to a rotating shaft 29 and housed in a sealed housing 30. The rotating shaft 29 is operatively connected to a rotating shaft 33 of the electric motor 2 via gears 31 and 32, and the rotor 4 and the stator 3 of the electric motor 2 are housed in a casing 34.

[0007] The liquid refrigerant extracted from the liquid reservoir 14 of the condenser 6 is supplied to the outer periphery of the stator 3 of the electric motor 2 through the supply pipe 12 to cool the outer peripheral surface. Next, a part of the liquid refrigerant flows into an air gap formed between the inner peripheral surface of the stator 3 and the outer peripheral surface of the rotor 4 through a passage extending from the outer peripheral surface of the stator 3 to the inner peripheral surface. Is evaporated and vaporized in the process of cooling, and then sucked into the evaporator 5 through the return pipe 13.

FIG. 5 is a Mollier diagram of the refrigeration cycle. The refrigerant gas is changed from A to B by being compressed by the first stage impeller 27 of the multi-stage turbocompressor 1, and is sucked into the second stage impeller 28 in the state of C to be compressed by being compressed by the second stage impeller 28. State.

The gas refrigerant is cooled by the condenser 6 to be in the state of E, and then condensed to form F.
Saturated liquid refrigerant. This saturated liquid refrigerant is throttled by the high-pressure side throttle mechanism 24 of the intercooler 7 to
State. Then, a part thereof evaporates to a state of H, and then is reduced in pressure by the intermediate suction valve 8 to a state of I, and is sucked into the second stage impeller 28 in a state of C.

[0010] The remaining liquid refrigerant is cooled to be in the state of J, and is throttled by the low-pressure side throttle mechanism 25 to be in the state of K. The refrigerant evaporates in the evaporator 5 to be in the state of L in the multistage turbo compressor 1, and is decompressed by the inlet vane 15 to the state of A.

The liquid refrigerant extracted from the liquid reservoir 14 of the condenser 6 is cooled to the electric motor 2 to enter the state of M through a system shown by a broken line and is sucked into the evaporator 5. Note that N is a saturated liquid line, and O is a saturated vapor line.

[0012]

In the above-described conventional refrigerator, the liquid refrigerant evaporates in an air gap formed between the inner peripheral surface of the stator 3 and the outer peripheral surface of the rotor 4, and the gas-liquid two-phase is cooled. Therefore, the rotational resistance of the rotor 4 increases and the motor 2
However, there is a problem that the efficiency of the refrigerator is deteriorated because the mechanical loss increases and a large amount of liquid refrigerant is required.

Further, the pressure of the liquid refrigerant supplied to the electric motor 2 depends on the temperature of the cooling medium flowing through the heat transfer tube 18 of the condenser 6 and the temperature of the medium to be cooled flowing through the heat transfer tube 16 of the evaporator 5. , The amount of refrigerant required for cooling the electric motor 2 may not be secured.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a first aspect of the present invention is to provide a multi-stage compressor driven by an electric motor and a multi-stage compressor. A condenser for condensing and liquefying the gas refrigerant discharged from the compressor, an intercooler for cooling by reducing the liquid refrigerant condensed in the condenser, and an evaporator for evaporating the liquid refrigerant flowing out of the intercooler. And the casing of the electric motor is partitioned into a stator chamber containing a stator and a rotor chamber containing a rotor, and the supercooled liquid refrigerant extracted from the evaporator and heated by a liquid refrigerant pump is supplied to the stator chamber. After cooling the stator to supply the refrigerant to the refrigerant circuit downstream of the intercooler, the gas refrigerant evaporated by the intercooler is supplied to the rotor chamber to cool the rotor. After, in refrigerator and returning the intermediate inlet or first stage suction port of the multistage compressor.

Another feature is that a means is provided for switching the gas refrigerant flowing out of the rotor chamber into the intermediate suction port or the first-stage suction port of the multistage compressor.

Still another feature is that a pressure control valve for controlling the pressure of the gas refrigerant flowing out of the rotor chamber is provided.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIG. The interior of a casing 34 of the electric motor 2 includes a stator chamber 41 for housing the stator 3 and a rotor chamber 42 for housing the rotor 4.
And is divided into.

A liquid reservoir 43 is formed below the evaporator 5.
The liquid refrigerant extracted from the liquid reservoir 43 is energized by the liquid refrigerant pump 44 and flows into the head tank 45 to be in the state of W on the Mollier diagram shown in FIG.

Next, the liquid refrigerant is supplied into the stator chamber 41 in the state of X, and is cooled to the stator 3 to be in the state of Y in FIG. 2 and enters the refrigerant circuit on the downstream side of the intercooler 7. Here, the refrigerant merges with the refrigerant flowing out of the intercooler 7 and enters the evaporator 5.

On the other hand, the gas refrigerant evaporated in the intercooler 7 enters the rotor chamber 42 in the state of P via the eliminator 26,
Here, by cooling the rotor 4, the state becomes Q. This gas refrigerant passes through the pressure control valve 46 and the on-off
Is sucked into the intermediate suction port 23 of the multi-stage turbo compressor 1 in the state described above.

At this time, the pressure of the gas refrigerant is controlled by the pressure control valve 47 to stably secure a flow rate of the gas refrigerant sufficient to cool the rotor 4.

When the pressure of the intercooler 7 exceeds a predetermined value due to a change in the operating conditions of the refrigerator or the temperature of the electric motor 2 exceeds a predetermined value, the on-off valve 47 is closed and the on-off valve 48 is simultaneously opened. open. Then, the gas refrigerant flowing out of the rotor chamber 42 enters the suction pipe 9 via the pressure control valve 46 and the opening / closing valve 48, where it merges with the gas refrigerant flowing out of the evaporator 5 and sends the first gas to the multi-stage turbo compressor 1. It is sucked through the step inlet 22.

At this time, the pressure of the gas refrigerant is controlled by the pressure control valve 47 to maintain the pressure of the intercooler 7 at a predetermined value or less and the temperature of the electric motor 2 at a predetermined value or less, and at the same time, use an unnecessarily large amount of gas refrigerant. From flowing through the rotor chamber 42.

FIG. 3 is a Mollier diagram in the case where the gas refrigerant is returned to the first stage suction port 22. The gas refrigerant changes from the state of S to the state of T by cooling the rotor 4, and then the pressure control valve. By being squeezed at 47, the state becomes U. The other configuration and operation are the same as those of the conventional one shown in FIGS.

The liquid refrigerant having the lowest temperature in the system is extracted from the evaporator 5 and is boosted by a liquid refrigerant pump 44 to be a supercooled liquid refrigerant. , The stator 3 can be effectively cooled, and therefore, the amount of liquid refrigerant for cooling the stator 3 and the amount of gas refrigerant for cooling the rotor 4 are minimized. be able to.

The rotor 4 is cooled by a minimum amount of gas refrigerant supplied to the rotor chamber 42, and a gas-liquid two-phase refrigerant flows through an air gap formed between the stator 3 and the rotor 4. Does not flow, the rotational resistance of the rotor 4 can be reduced, and therefore, the mechanical efficiency of the electric motor 2 and thus the efficiency of the refrigerator can be improved.

When the operating conditions of the refrigerator change, the gas refrigerant flowing out of the rotor chamber 42 is supplied to the first stage inlet 22 of the compressor 1.
In this case, the amount of gas refrigerant sufficient to cool the rotor 4 can be obtained. At this time, if the pressure of the gas refrigerant flowing out of the rotor chamber 42 is controlled by the pressure control valve 46, it is possible to prevent an unnecessarily large amount of gas refrigerant from flowing through the rotor chamber 42.

[0028]

According to the present invention, the interior of the motor casing is divided into a stator chamber for accommodating the stator and a rotor chamber for accommodating the rotor, and the supercooled liquid refrigerant extracted from the evaporator and pressurized by the liquid refrigerant pump is supplied to the stator. Since the stator is supplied to the chamber to cool the stator, the stator can be effectively cooled.Therefore, the amount of liquid refrigerant required to cool the stator and the amount of gas refrigerant required to cool the rotor are reduced. Can be minimized.

Since the rotor is cooled by supplying the gas refrigerant evaporated in the intercooler to the rotor chamber, the rotational resistance of the rotor is reduced, and therefore, the mechanical efficiency of the electric motor and the efficiency of the refrigerator can be improved. .

By providing a means for switching the gas refrigerant flowing out of the rotor chamber into the intermediate suction port or the first-stage suction port of the multi-stage compressor and allowing it to flow in, the rotor can be cooled regardless of the operation state of the refrigerator. Enough gas refrigerant can be supplied to the rotor chamber.

Furthermore, if the pressure of the gas refrigerant flowing out of the rotor chamber is controlled by the pressure control valve, the amount of gas refrigerant required for cooling the rotor can be stably secured.

[Brief description of the drawings]

FIG. 1 is a system diagram of a refrigerator showing an embodiment of the present invention.

FIG. 2 is a Mollier diagram when the gas refrigerant of the embodiment is returned to an intermediate suction port.

FIG. 3 is a Mollier chart when returning the gas refrigerant of the embodiment to the first stage suction port.

FIG. 4 is a system diagram of a conventional refrigerator.

FIG. 5 is a Mollier diagram of a conventional refrigerator.

[Explanation of symbols]

 2 Motor 33 Rotary shaft 34 Casing 3 Stator 4 Rotor 41 Stator chamber 42 Rotor chamber 1 Multistage turbo compressor 21 Discharge port 22 First stage suction port 23 Intermediate suction port 27, 28 Impeller 29 Rotating shaft 30 Housing 15 Inlet vane 31, 32 Gear 6 Condenser 18 Heat transfer tube 14 Liquid reservoir 7 Intercooler 24 High-pressure side throttle mechanism 25 Low-pressure side throttle mechanism 26 Eliminator 5 Evaporator 16 Heat transfer tube 43 Liquid reservoir 9 Suction pipe 10 Discharge pipe 44 Liquid refrigerant pump 45 Head tank 46 Pressure control valve 47, 48 On-off valve

Claims (3)

[Claims] 1. A multi-stage compressor driven by an electric motor;
A condenser for condensing and liquefying the gas refrigerant discharged from the multistage compressor, an intercooler for cooling the liquid refrigerant condensed by the condenser by reducing the pressure, and evaporating the liquid refrigerant flowing out of the intercooler. An evaporator is provided, and the inside of the casing of the electric motor is partitioned into a stator chamber containing a stator and a rotor chamber containing a rotor, and the supercooled liquid refrigerant extracted from the evaporator and heated by a liquid refrigerant pump is supplied with the evaporator. After supplying to the stator chamber and cooling the stator,
After returning to the refrigerant circuit on the downstream side of the intercooler and supplying the gas refrigerant evaporated in the intercooler to the rotor chamber to cool the rotor, the intermediate suction port or the first-stage suction of the multi-stage compressor is provided. A refrigerator characterized by being returned to the mouth. 2. The refrigerator according to claim 1, further comprising means for switching the gas refrigerant flowing out of the rotor chamber to an intermediate suction port or a first-stage suction port of the multi-stage compressor to flow the refrigerant. 3. The refrigerator according to claim 1, further comprising a pressure control valve for controlling a pressure of the gas refrigerant flowing out of the rotor chamber.