JP2001074325A - Two-stage compression type freezing and refrigerating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of temperature control in respective freezing and refrigerating chambers and achieve the unifying of temperature at respective parts in the chambers, the heightening of an efficiency, the reducing of an electric power consumption and the heightening of reliability. SOLUTION: A two-stage compression type freezing and refrigerating system is constituted of a two-stage compressor 20 equipped with a low-stage compressing element 23 and a high-stage compressing element 24 in a sealed vessel 21, a condenser 25, an intermediate-pressure expansion device 26, an intermediate-pressure evaporator 28, a low-pressure expansion device 29 and a low-pressure evaporator 30. The discharging side of the low-stage compressing element 23 and the suction side of the high-stage compressing element 24 are constituted so as to communicate in the sealed vessel 21 whereby the evaporating temperatures in two sets of evaporators can be controlled so as to be suitable to the temperatures in respective chambers of a freezing chamber, a refrigerating chamber or the like and the improvement of accuracy of temperature control in respective chambers as well as the unifying of temperatures at respective parts in the chambers can be achieved. Further, an intermediate pressure can be increased mainly whereby the efficiency of the two-stage compressor 20 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage compression refrigeration apparatus having a two-stage compressor having two compression elements.

[0002]

2. Description of the Related Art In the field of refrigeration equipment, a two-stage compression refrigeration system using a multi-stage compressor suitable for high compression ratio operation has been proposed as part of securing a low-temperature heat source and a high-temperature heat source. As a conventional two-stage compression refrigeration system, for example, Japanese Patent Application Laid-Open No. 5-133
No. 368 is disclosed.

Hereinafter, an example of the conventional two-stage compression refrigeration system will be described with reference to the drawings.

FIG. 11 is a piping diagram of a two-stage compression refrigeration cycle using a conventional two-stage compressor.

In FIG. 11, 1 is a two-stage compressor, 2 is a condenser, 3 is a first expansion valve, 4 is a gas-liquid separator, 5 is a second expansion valve, 6 is an evaporator, and 7 is an accumulator. Yes, these are sequentially connected by piping. Reference numeral 8 denotes an airtight container. A motor 9 is disposed in an upper space in the airtight container 8, and a two-stage compression mechanism 10 is disposed below the motor 9, and an outer peripheral portion and a bottom portion thereof are configured as an oil reservoir 11. Two-stage compression mechanism 10
Are the upper stage compression element 12 and the lower stage compression element 13
And a flat plate-shaped middle plate 14 disposed between the compression elements (12, 13). 15 is the first eccentric portion 15a and the second
It is a crankshaft having an eccentric portion 15b, which is fixed to the rotor 9a of the motor 9. Reference numerals 16 and 17 denote a first eccentric portion 15a and a second eccentric portion 15 of the crankshaft 15.
b shows a first piston and a second piston mounted on the b. The cylinder capacity of the high-stage compression element 12 is
Is set to about 45 to 65% of the cylinder capacity of the cylinder. The discharge side of the low-stage compression element 13 communicates with the suction side of the high-stage compression element 12 via a communication passage 18. Reference numeral 19 denotes a refrigerant injection passage, which communicates the communication passage 18 with the downstream side of the gas-liquid separator 4.

[0006] The operation of the two-stage compression refrigeration system configured as described above will be described below.

The crankshaft 15 is driven by the motor 3.
Rotates, the low-stage compression element 13
The refrigerant gas is sucked from the compressor, compressed, and discharged to the communication passage 18. The refrigerant gas discharged from the low-stage compression element 13 to the communication passage 18 mixes with the refrigerant gas from the refrigerant injection passage 19 and is sucked from the suction side of the high-stage compression element 12,
It is compressed again. The refrigerant gas compressed by the high-stage compression element 12 is once discharged into the closed vessel 8 and then sent to the condenser 2 via a pipe. The refrigerant gas radiates heat in the condenser 2 to be condensed into a liquid refrigerant, and then decompressed by the first expansion valve 3. Then, the gas flows into the gas-liquid separator 4 and a part thereof evaporates there. As a result, the liquid refrigerant is stored at the bottom inside the gas-liquid separator 4, and the saturated gas refrigerant that has expanded in one stage is stored at the top inside the gas-liquid separator 4. Then, only the liquid refrigerant flows out of the gas-liquid separator 4 in the direction of the second expansion valve 5, where it is depressurized, flows into the evaporator 6, and evaporates. At this time, the evaporator 6 exerts a cooling action by removing heat from the surroundings. Then, the low-temperature gaseous refrigerant leaving the evaporator 6 is supplied to the accumulator 7
Then, it is returned to the two-stage compressor 1 and is sucked into the low-stage compression element 13 again.

On the other hand, the saturated gas refrigerant in the upper part of the gas-liquid separator 4 flows into the communication passage 18 via the refrigerant injection passage 19. Therefore, since the temperature of the refrigerant gas discharged from the low-stage compression element 13 is reduced, the temperature of the refrigerant gas sucked by the high-stage compression element 12 can be reduced, and the efficiency can be improved. Further, since the temperature of the gas discharged from the high-stage compression element 12 is also reduced, overheating of the compressor can be prevented, and poor lubrication and deterioration of the lubricating oil due to a decrease in the viscosity of the lubricating oil can be prevented.

As described above, the use of the two-stage compression refrigeration cycle improves the efficiency of the refrigeration cycle and improves the reliability of the compressor as compared with the case of using the one-stage compression refrigeration cycle.

[0010]

However, in the above-described conventional configuration, when the two-stage compression refrigeration cycle is applied to an apparatus requiring two or more temperature zones, such as freezing and refrigerating, for example, a refrigerator-freezer, etc. Since the temperature in the freezer compartment having the lowest temperature is set at about −18 ° C. to −22 ° C., the evaporation temperature of the evaporator 6 needs to be about −30 ° C. lower than that. On the other hand, the higher the evaporation temperature, the higher the efficiency of the compressor. Therefore, it is necessary to design the evaporation temperature as high as possible. However, the evaporation temperature is limited to a certain value or less due to the above-described limitation of the freezing room temperature. For this reason, the internal temperature is 3 ° C
For cooling the refrigerator compartment at about -7 ° C, low-temperature cold air cooled by the evaporator 6 at about -30 ° C must be used.
In addition to the low efficiency of the cooling system due to the low evaporating temperature, the accuracy of temperature control in the refrigerator compartment deteriorates and the temperature of each part in the refrigerator becomes uneven.

SUMMARY OF THE INVENTION The present invention solves the conventional problems, and comprises two evaporators and two-stage compressors each having an evaporating temperature suitable for the temperature in each of the freezing compartment and the refrigerator compartment of a freezing and refrigeration apparatus. The accuracy of temperature control in each chamber is improved, and the temperature of each section in the chamber can be made uniform, with higher efficiency and less power consumption.
It is another object of the present invention to provide a highly reliable two-stage compression refrigeration apparatus.

Further, in the above-mentioned conventional configuration, since it is necessary to obtain a cooling action only by the evaporator 6, the amount of the refrigerant circulated from the gas-liquid separator 4 is smaller than that of the refrigerant injection passage 19 in the second expansion valve 5. More on the side. Therefore, the cylinder capacity of the high-stage compression element 12 of the two-stage compressor 1 is
3 is set to about 45 to 65% of the cylinder capacity. When the two-stage compressor 1 is applied to a refrigeration cycle having two evaporators suitable for the temperatures in the freezing compartment and the freezing compartment of the refrigeration apparatus, the cylinder capacity of the high-stage compression element 12 is low. Since it is considerably smaller than the cylinder capacity of the stage compression element 13, the refrigerating capacity of the evaporator for the refrigerating compartment becomes small, and there is a disadvantage that the refrigerating compartment and the refrigerating compartment may not be properly cooled.

Another object of the present invention is to provide a two-stage compressor and two evaporators each having an evaporating temperature suitable for the temperature in each of the freezing compartment and the refrigerating compartment of the freezing and refrigeration apparatus. By optimizing the ratio of the cylinder capacity to the cylinder capacity of the low-stage compression element, one of the freezer compartments in the freezer compartment and the refrigerating compartment in a different temperature zone, such as the freezer compartment, becomes insufficient in refrigeration capacity, Each chamber can be properly cooled without becoming excessive,
It is another object of the present invention to provide a two-stage compression refrigerating / cooling apparatus having high efficiency and low power consumption.

[0014]

SUMMARY OF THE INVENTION To achieve this object, the present invention provides a two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container; A condenser connected to the discharge side of the condenser by a pipe, an expansion device for intermediate pressure connected to the outlet side of the condenser by a pipe, and an intermediate pressure suction communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element. A pipe, an intermediate-pressure evaporator connected between the intermediate-pressure expansion device and the intermediate-pressure suction pipe, and a low-pressure expansion connected to the outlet of the condenser or the outlet of the intermediate-pressure expansion device. And a low-pressure evaporator connected by piping between the low-pressure expansion device and the suction side of the low-stage compression element of the two-stage compressor, wherein the discharge side of the low-stage compression element and the high-stage The suction side of the compression element is in the closed container It was a structure in communication.

Thus, the two evaporators of the freezing and refrigerating apparatus can be set to the evaporating temperatures suitable for the respective internal temperatures of the freezing room and the refrigerating room, respectively, and the accuracy of the temperature control in each of the internal refrigerators is improved. At the same time, the temperature of each part in the refrigerator can be made uniform. Also,
In particular, since the evaporation temperature of the intermediate-pressure evaporator can be set high, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each compartment is not cooled with cold air having a lower temperature than necessary. Furthermore, since the inside of the closed vessel is at an intermediate pressure, the pressure difference between the compression chamber of each of the low-stage compression element and the high-stage compression element and the inside of the closed vessel is small, and the pressure between each compression element and the inside of the closed vessel is small. The leakage amount of the refrigerant gas can be reduced, and the refrigeration capacity and efficiency of the two-stage compressor can be improved.

Further, the present invention provides a two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container,
A condenser pipe-connected to the discharge side of the high-stage compression element, an intermediate-pressure expansion device pipe-connected to the outlet side of the condenser,
An intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element; and an intermediate-pressure evaporator pipe-connected between the intermediate-pressure expansion device and the intermediate-pressure suction pipe. A low-pressure expansion device pipe-connected to an outlet side of the condenser or an outlet side of the intermediate-pressure expansion device, and a pipe between the low-pressure expansion device and a suction side of a low-stage compression element of the two-stage compressor. A low-pressure evaporator is connected to the low-pressure compression element, and the suction side of the low-stage compression element communicates with the closed vessel.

Thus, the two evaporators of the freezing and refrigerating apparatus can be set to the evaporating temperatures suitable for the respective internal temperatures of the freezing room and the refrigerating room, respectively, and the accuracy of the temperature control in each of the internal refrigerators is improved. At the same time, the temperature of each part in the refrigerator can be made uniform. Also,
In particular, since the evaporation temperature of the intermediate-pressure evaporator can be set high, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each compartment is not cooled with cold air having a lower temperature than necessary. Furthermore, since the pressure inside the sealed container is low, and each compression element and motor in the sealed container can be cooled by a low-temperature refrigerant gas returning from the low-pressure evaporator, overheating of each compression element can be prevented, and reliability can be prevented. And the motor efficiency can be improved by lowering the temperature of the motor.

Further, the present invention provides a two-stage compressor including a motor, a low-stage compression element and a high-stage compression element in a closed container,
A condenser pipe-connected to the discharge side of the high-stage compression element, an intermediate-pressure expansion device pipe-connected to the outlet side of the condenser,
An intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element; and an intermediate-pressure evaporator pipe-connected between the intermediate-pressure expansion device and the intermediate-pressure suction pipe. A low-pressure expansion device pipe-connected to an outlet side of the condenser or an outlet side of the intermediate-pressure expansion device, and a pipe between the low-pressure expansion device and a suction side of a low-stage compression element of the two-stage compressor. A low-pressure evaporator was connected, and the discharge side of the high-stage compression element was configured to communicate with the closed vessel.

Thus, the two evaporators of the freezing and refrigerating apparatus can be set to the evaporating temperatures suitable for the respective internal temperatures of the freezing room and the refrigerating room, respectively, and the accuracy of the temperature control in each of the internal refrigerators is improved. At the same time, the temperature of each part in the refrigerator can be made uniform. Also,
In particular, since the evaporation temperature of the intermediate-pressure evaporator can be set high, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each compartment is not cooled with cold air having a lower temperature than necessary. Further, since the pressure in the closed vessel is high, lubricating oil can be sufficiently supplied from the inside of the closed vessel to the compression chambers of the low-stage compression element and the high-stage compression element by the pressure difference. The lubricity of the moving part is improved, and the reliability can be improved.

Further, in the present invention, the ratio VH / VL of the cylinder volume VL of the low-stage compression element to the cylinder volume VH of the high-stage compression element is set in the range of 0.5 to 1.3. .

Thus, the two evaporators of the freezing and refrigerating apparatus can be set to the evaporating temperatures suitable for the respective internal temperatures of the freezing room and the refrigerating room, respectively, and the accuracy of temperature control in each of the internal refrigerators is improved. At the same time, the temperature of each part in the refrigerator can be made uniform. Also,
In particular, since the evaporation temperature of the intermediate-pressure evaporator can be set high, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each compartment is not cooled with cold air having a lower temperature than necessary. Furthermore, by making the ratio of the cylinder volume of the high-stage compression element to the cylinder volume of the low-stage compression element appropriate,
Either the freezer compartment and the refrigerator compartment of the freezer compartment in different temperature zones, such as the freezer compartment, will not have insufficient freezing capacity or excess freezing capacity. Power consumption can be reduced. Further, by setting the ratio of the cylinder volume to each of the high pressure, the low pressure, and the intermediate pressure, the maximum torque and the torque fluctuation of the motor can be reduced, and the motor efficiency can be improved and the vibration can be reduced.

Further, in the present invention, the opening of the suction pipe for the intermediate pressure into the closed vessel communicates with the suction side of the high-stage compression element through a small gap.

[0023] Thereby, the two evaporators of the freezing and refrigerating apparatus can be set to the evaporating temperatures suitable for the respective internal temperatures of the freezing room and the refrigerating room, respectively, and the accuracy of the temperature control in each of the internal refrigerators is improved. At the same time, the temperature of each part in the refrigerator can be made uniform. Also,
In particular, since the evaporation temperature of the intermediate-pressure evaporator can be set high, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each compartment is not cooled with cold air having a lower temperature than necessary. Further, the refrigerant gas returned from the intermediate-pressure evaporator into the closed vessel through the intermediate-pressure suction pipe is sucked into the suction side of the high-stage compression element through a small gap, so that each compression element and the motor The influence of the heat reception is small, and the temperature rise is suppressed to a small level. Therefore, the density of the refrigerant gas to be taken in increases, and the amount of circulating refrigerant increases, and the efficiency can be improved. Furthermore, compared with the case where the intermediate pressure suction pipe and the suction side of the high-stage compression element are directly connected, the pressure pulsation from the high-stage compression element diffuses into the closed vessel due to the slight gap, and the intermediate-pressure suction pipe It is difficult to transmit the noise, and the generation of noise can be prevented.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An invention according to claim 1 of the present invention is directed to a two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container, A condenser pipe-connected to the discharge side, an intermediate-pressure expansion device pipe-connected to the outlet side of the condenser, and an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element An intermediate-pressure evaporator pipe-connected between the intermediate-pressure expansion device and the intermediate-pressure suction pipe; and a low-pressure expansion device pipe-connected to the outlet side of the condenser or the outlet side of the intermediate-pressure expansion device. And a low-pressure evaporator piped between the low-pressure expansion device and the suction side of the low-stage compression element of the two-stage compressor, wherein the discharge side of the low-stage compression element and the high-stage compression The suction side of the element communicated with the closed container The two evaporators of the freezing and refrigeration system have low and intermediate evaporating pressures, respectively. Therefore, the evaporator temperatures should be suitable for the temperatures inside the freezer and refrigerator compartments. As a result, the accuracy of temperature control in each of the refrigerators can be improved, and the temperature of each part in the refrigerator can be made uniform. In addition, since the evaporation temperature of the evaporator for the intermediate pressure can be set higher, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each refrigerator is not cooled with unnecessarily low temperature air. I do. Further, since the discharge side of the low-stage compression element and the suction side of the high-stage compression element communicate with each other in the closed container, the inside of the closed container has an intermediate pressure, and each of the low-stage compression element and the high-stage compression element The pressure difference between the compression chamber and the closed container is small, and the amount of refrigerant gas leakage between each compression element and the closed container can be reduced,
This has the effect of improving the refrigerating capacity and efficiency of the two-stage compressor.

According to a second aspect of the present invention, there is provided a two-stage compressor including a motor, a low-stage compression element and a high-stage compression element in a closed container, and a condenser connected to a discharge side of the high-stage compression element by piping. An intermediate-pressure expansion device pipe-connected to the outlet side of the condenser, an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element,
An intermediate-pressure evaporator pipe-connected between the intermediate-pressure expansion device and the intermediate-pressure suction pipe, and a low-pressure expansion device pipe-connected to the outlet side of the condenser or the outlet side of the intermediate-pressure expansion device, A low-pressure evaporator connected by piping between the low-pressure expansion device and the suction side of the low-stage compression element of the two-stage compressor, wherein the suction side of the low-stage compression element is communicated with the closed vessel. Since the two evaporators of the freezing and refrigeration system have low and intermediate evaporating pressures, respectively, the evaporator temperatures should be suitable for the temperatures in the freezer and refrigerator compartments. As a result, the accuracy of temperature control in each of the refrigerators can be improved, and the temperature of each part in the refrigerator can be made uniform. In addition, since the evaporation temperature of the evaporator for the intermediate pressure can be set higher, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each refrigerator is not cooled with unnecessarily low temperature air. I do. Furthermore, since the suction side of the low-stage compression element communicates with the closed container, the pressure in the closed container becomes low, and the low-temperature refrigerant gas returned from the low-pressure evaporator cools each compression element and motor in the closed container. Can be prevented, overheating of each compression element can be prevented, reliability can be improved, and motor efficiency can be improved by lowering the temperature of the motor.

According to a third aspect of the present invention, there is provided a two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container, and a condenser connected to a discharge side of the high-stage compression element by piping. An intermediate-pressure expansion device pipe-connected to the outlet side of the condenser, an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element,
An intermediate-pressure evaporator pipe-connected between the intermediate-pressure expansion device and the intermediate-pressure suction pipe, and a low-pressure expansion device pipe-connected to the outlet side of the condenser or the outlet side of the intermediate-pressure expansion device, A low-pressure evaporator connected by piping between the low-pressure expansion device and a suction side of a low-stage compression element of the two-stage compressor, wherein a discharge side of the high-stage compression element is communicated with the closed vessel. Since the two evaporators of the freezing and refrigeration system have low and intermediate evaporating pressures, respectively, the evaporator temperatures should be suitable for the temperatures in the freezer and refrigerator compartments. As a result, the accuracy of temperature control in each of the refrigerators can be improved, and the temperature of each part in the refrigerator can be made uniform. In addition, since the evaporation temperature of the evaporator for the intermediate pressure can be set higher, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each refrigerator is not cooled with unnecessarily low temperature air. I do. Furthermore, since the discharge side of the high-stage compression element communicates with the inside of the closed vessel, the inside of the closed vessel becomes high pressure, and the pressure difference causes lubrication from the inside of the closed vessel to the compression chambers of the low-stage compression element and the high-stage compression element. It has an effect that the oil can be sufficiently supplied, the lubricating properties of the sliding parts such as the piston and the cylinder are improved, and the reliability can be improved.

The invention described in claim 4 is the same as the invention described in claim 1, 2 or 3,
The ratio VH / VL of the cylinder volume VL of the low-stage compression element and the cylinder volume VH of the high-stage compression element is set to be in the range of 0.5 to 1.3, and is set forth in claim 1 or claim 2. In addition to the operation of the second or third aspect of the present invention, the ratio of the cylinder volume of the high-stage compression element to the cylinder volume of the low-stage compression element is made appropriate, so that the freezing room and the refrigerating room of the refrigerating and refrigerating device can be used. There is an effect that the inside of each refrigerator can be properly cooled, and the power consumption can be reduced with high efficiency, without any one of the refrigerators in different temperature zones becoming insufficient in refrigeration capacity or excessive in refrigeration capacity. Further, by setting the ratio of the cylinder volume to each of the high pressure, the low pressure, and the intermediate pressure, the maximum torque and the torque fluctuation of the motor can be reduced, and the motor efficiency can be improved and the vibration can be reduced.

According to a fifth aspect of the present invention, the opening of the intermediate-pressure suction pipe into the closed vessel communicates with the suction side of the high-stage compression element through a small gap. In addition to the function of the invention described in Item 1, the refrigerant gas returned from the intermediate pressure evaporator into the closed vessel through the intermediate pressure suction pipe is sucked into the suction side of the high-stage compression element through a small gap. Therefore, the influence of the heat received from each compression element and the motor is small, and the temperature rise is suppressed to a small level. Therefore, the density of the refrigerant gas to be taken in increases, and the amount of circulating refrigerant increases, and the efficiency can be improved.
Furthermore, compared with the case where the intermediate pressure suction pipe and the suction side of the high-stage compression element are directly connected, the pressure pulsation from the high-stage compression element diffuses into the closed vessel due to the slight gap, and the intermediate-pressure suction pipe It has an effect that it is hard to be transmitted to noise and noise is hardly generated.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a two-stage compression refrigeration apparatus according to the present invention will be described below with reference to the drawings. The same components as those of the related art are denoted by the same reference numerals, and detailed description is omitted.

(Embodiment 1) FIG. 1 shows a refrigerant circuit diagram of a two-stage compression refrigeration apparatus according to Embodiment 1 of the present invention. FIG. 2 is a plan sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment. FIG. 3 is a longitudinal sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment. FIG. 4 is a pressure-enthalpy diagram of a refrigeration cycle in the two-stage compression refrigeration apparatus of the embodiment.

In FIG. 1, FIG. 2, FIG. 3, and FIG.
This is a two-stage compressor including a motor 22, a low-stage compression element 23, and a high-stage compression element 24 in a closed container 21. 25 is a condenser connected to the discharge side of the high-stage compression element 24 by piping.
Reference numeral 26 denotes an intermediate pressure expansion device connected to the outlet side of the condenser 25 by piping. Reference numeral 27 denotes an intermediate pressure suction pipe which communicates with the discharge side of the low-stage compression element 23 and the suction side of the high-stage compression element 24, and 28 is connected between the intermediate-pressure expansion device 26 and the intermediate-pressure suction pipe 27. It is an intermediate pressure evaporator. Reference numeral 29 denotes a low-pressure expansion device connected to the outlet side of the condenser 25 by piping, and reference numeral 30 denotes a low-pressure expansion device connected by piping between the low-pressure expansion device 29 and the suction side of the low-stage compression element 23 of the two-stage compressor 20. Evaporator. The discharge side of the low-stage compression element 23 and the suction side of the high-stage compression element 24 communicate with each other in the closed casing 21.

The low-stage compression element 23 includes a cylinder 31, a piston 32, a connecting rod 33, a suction muffler 34, a discharge muffler 35, and the like. The high-stage compression element 24 similarly has a cylinder 36, a piston 37, a connecting rod 38, and a suction muffler 39. , A discharge muffler 40 and the like. Motor 2
2 is a rotor 4 fixed to the crankshaft 41
2. It is composed of the stator 43. The crankshaft 41 has an eccentric portion 41a, and the eccentric portion 41a and the pistons 32 and 37 are connected by connecting rods 33 and 38, respectively. Reference numeral 42 denotes a low-pressure suction pipe that is fixed to the closed container 21 and communicates the suction muffler 34 and the low-pressure evaporator 30. Reference numeral 43 denotes a discharge pipe fixed to the closed container 21, one end of which is connected to the discharge muffler 4 through a discharge pipe 44.
0, and the other end is connected to the condenser 25 via a pipe. Reference numeral 45 denotes a lubricating oil, which is stored in a lower part of the closed container 21.

The operation of the hermetic compressor constructed as described above will be described below.

The motor 22 causes the crankshaft 4
When 1 rotates, the pistons 32 and 37 reciprocate in the cylinders 31 and 36 by the connecting rods 33 and 38, respectively. The low-stage compression element 23 is provided with the low-pressure evaporator 3.
After sucking the refrigerant gas into the cylinder 31 from 0 through the low-pressure suction pipe 42 and the suction muffler 34, the refrigerant gas is compressed to an intermediate pressure and discharged into the closed container 21 through the discharge muffler 35. The refrigerant gas discharged from the discharge muffler 35 is mixed with the refrigerant gas flowing into the closed vessel 21 from the intermediate pressure suction pipe 27, and is sucked into the cylinder 36 from the suction muffler 39 of the high-stage compression element 24, and compressed again. Is done. The refrigerant gas compressed by the high-stage compression element 24 is sent to the condenser 25 through the discharge muffler 40, the discharge pipe 44, and the discharge pipe 43. The refrigerant gas radiates heat in the condenser 25 to be condensed into a liquid refrigerant, and then splits into two flow paths.
One of them flows into the intermediate pressure expansion device 26 and is decompressed, and then flows into the intermediate pressure evaporator 28 and evaporates. At this time, by removing heat from the surroundings, the intermediate-pressure evaporator 28 exhibits a cooling action. Then, the refrigerant gas that has exited the intermediate-pressure evaporator 28 returns to the two-stage compressor 1 through the intermediate-pressure suction pipe 27.

The other liquid refrigerant from the condenser 25 flows into the low-pressure expansion device 29 to be decompressed, flows into the low-pressure evaporator 30, and evaporates. At this time, the low-pressure evaporator 28 exerts a cooling action by removing heat from the surroundings. And
The refrigerant gas exiting the low-pressure evaporator 30 is supplied to the low-pressure suction pipe 4.
2 and returns to the two-stage compressor 1, and again the low-stage compression element 23
Inhaled.

The lubricating oil 45 is supplied to the crankshaft 41.
After being lifted up by the centrifugal force from the lower end of the eccentric part 41a and lubricating each sliding part of the crankshaft 41, it is scattered by the centrifugal force from the upper end of the eccentric part 41a, and the pistons 32, 37
And the sliding parts of the cylinders 31 and 36 and the connecting rods 33 and 3
8 are lubricated.

In the refrigeration cycle of this embodiment, as shown in FIG. 4, the refrigerant in the intermediate-pressure evaporator 28 has an intermediate pressure, and the refrigerant in the low-pressure evaporator 30 has a low pressure. When this refrigeration cycle is applied to a refrigeration apparatus, the intermediate-pressure evaporator 28 is used for refrigeration, and the low-pressure evaporator 30 is used for refrigeration. Therefore, the temperature of the evaporator can be adjusted to the temperature in each of the freezer compartment and the refrigerator compartment. For example, the temperature of the refrigerator compartment is 3 ° C. to 7 ° C., and the temperature of the freezer compartment is −18 ° C. to −2.
When set to 2 ° C., the evaporation temperature of the intermediate pressure evaporator 28 can be set to about 0 ° C. to −10 ° C., and the evaporation temperature of the low pressure evaporator 30 can be set to about −25 ° C. to −35 ° C. Since the difference between the temperature in each storage and the evaporation temperature is small, the accuracy of temperature control in each storage is improved and the temperature of each part in the storage can be made uniform. In addition, since the evaporation temperature of the intermediate-pressure evaporator 28 can be set particularly high, the efficiency of the two-stage compressor 20 is improved, and the interior of each refrigerator is not cooled with unnecessarily low temperature cool air. Efficiency is improved.

Further, since the discharge side of the low-stage compression element 23 and the suction side of the high-stage compression element 24 communicate with each other in the closed container 20, the pressure in the closed container 20 becomes an intermediate pressure, and the low-stage compression element 23 In addition, the pressure difference between the inside of each of the cylinders 31 and 36 of the high-stage compression element 24 and the inside of the closed vessel 21 is small, and the amount of refrigerant gas leakage between each compression element and the inside of the closed vessel 21 can be reduced. The refrigeration capacity and efficiency of the two-stage compressor 20 can be improved.

As described above, the two-stage compression refrigeration apparatus of the present embodiment comprises a two-stage compressor 20 having a motor 22, a low-stage compression element 23, and a high-stage compression element 24 in a closed container 21,
Condenser 25 connected to the discharge side of high-stage compression element 24 by piping
And an intermediate-pressure expansion device 26 connected to the outlet side of the condenser 25 by piping, and an intermediate-pressure suction pipe 2 communicating with the discharge side of the low-stage compression element 23 and the suction side of the high-stage compression element 24.
7, intermediate pressure expansion device 26 and intermediate pressure suction pipe 27
, A low-pressure expansion device 29 connected to the outlet of the condenser 25 or the outlet of the intermediate-pressure expansion device 26, and a low-pressure expansion device 2.
9 and a low-pressure evaporator 30 connected by piping between the two-stage compressor 20 and the suction side of the low-stage compression element 23. The discharge side of the low-stage compression element 23 and the suction side of the high-stage compression element 24. Are communicated with the inside of the closed container 21, so that the accuracy of temperature control in each refrigerator can be improved, the temperature of each part in the refrigerator can be made uniform, and the two-stage compression refrigeration with high efficiency and low power consumption can be achieved. It can be a refrigerator.

(Embodiment 2) FIG. 5 is a refrigerant circuit diagram of a two-stage compression refrigeration apparatus according to Embodiment 2 of the present invention. FIG. 6 is a plan sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment.

Hereinafter, description will be made with reference to the drawings, but the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. 5 and 6, reference numeral 46 denotes a two-stage compressor including a low-stage compression element 47 and a high-stage compression element 48. Reference numeral 49 denotes an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element 47 and the suction side of the high-stage compression element 48. Reference numeral 50 denotes a low-pressure suction pipe fixed to the closed container 21, and communicates the low-pressure evaporator 30 with the inside of the closed container 21. Further, the suction side of the low-stage compression element 47 communicates from the suction muffler 51 into the closed container 21. Reference numeral 52 denotes a suction muffler for the high-stage compression element 48, which communicates with a suction pipe 49 for intermediate pressure. A communication pipe 53 communicates the discharge muffler 54 and the suction muffler 52.

The operation of the two-stage compression refrigerating and refrigerating apparatus configured as described above will be described below.

Embodiment 1 Except for the internal structure of the two-stage compressor 46
Therefore, the effect of the present refrigeration cycle can be obtained almost in the same manner as in the first embodiment. That is, it is possible to improve the accuracy of the temperature control in each of the refrigerators, to make the temperature of each part in the refrigerator uniform, and to further reduce power consumption with higher efficiency.

In this embodiment, since the suction side of the low-stage compression element 47 communicates with the inside of the closed vessel 21, the inside of the closed vessel 21 has a low pressure and the low-temperature refrigerant gas returning from the low-pressure evaporator 30. Can cool the low-stage compression element 47, the high-stage compression element 48, and the motor 22 in the closed container 21, so that the overheating of each compression element 47, 48 can be prevented, and the reliability is improved. Efficiency can be improved.

As described above, the two-stage compression refrigeration apparatus of the present embodiment comprises a two-stage compressor 46 having the motor 22, the low-stage compression element 47 and the high-stage compression element 48 in the closed container 21,
Condenser 28 connected by piping to the discharge side of high-stage compression element 48
An intermediate-pressure expansion device 26 connected to the outlet side of the condenser 28 via a pipe, and an intermediate-pressure suction pipe 4 communicating with the discharge side of the low-stage compression element 47 and the suction side of the high-stage compression element 48.
9, intermediate pressure expansion device 26 and intermediate pressure suction pipe 49
, A low-pressure expansion device 29 connected to the outlet of the condenser 25 or the outlet of the intermediate-pressure expansion device 26, and a low-pressure expansion device 2.
9 and a low-pressure evaporator 30 connected to the suction side of the low-stage compression element 47 of the two-stage compressor 46 by piping. The suction side of the low-stage compression element 47 communicates with the closed vessel 21. Therefore, the accuracy of the temperature control in each of the refrigerators can be improved, the temperature in each of the refrigerators can be made uniform, the power consumption can be reduced with higher efficiency, and the reliability of the two-stage compressor 46 can be further improved. And motor efficiency can be improved.

(Embodiment 3) FIG. 7 shows a refrigerant circuit diagram of a two-stage compression refrigeration apparatus according to Embodiment 3 of the present invention. FIG. 8 is a plan sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment.

Hereinafter, description will be made with reference to the drawings. However, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. 8 and 9, reference numeral 55 denotes a two-stage compressor including a low-stage compression element 56 and a high-stage compression element 57. Reference numeral 58 denotes an intermediate-pressure suction pipe that communicates with the discharge side of the low-stage compression element 56 and the suction side of the high-stage compression element 57. Reference numeral 59 denotes a suction muffler for the high-stage compression element 57, which communicates with the suction pipe 58 for intermediate pressure. Reference numeral 60 denotes a communication pipe that connects the discharge muffler 61 and the suction muffler 59. Reference numeral 62 denotes a discharge pipe fixed to the closed container 21, one end of which is connected to the inside of the closed container 21, and the other end of which is connected to the condenser 25 via a pipe. Also, the high-stage compression element 57
Is communicated from the discharge muffler 63 into the closed container 21.

The operation of the two-stage compression refrigerating / refrigerating apparatus configured as described above will be described below.

Embodiment 1 Except for the internal structure of the two-stage compressor 55,
Therefore, the effect of the present refrigeration cycle can be obtained almost in the same manner as in the first embodiment. That is, it is possible to improve the accuracy of the temperature control in each of the refrigerators, to make the temperature of each part in the refrigerator uniform, and to further reduce power consumption with higher efficiency.

In this embodiment, since the discharge side of the high-stage compression element 57 communicates with the inside of the closed vessel 21, the pressure inside the closed vessel 21 becomes high, and
It becomes higher than the pressure in 1,36. Therefore, the cylinders 31 and 36 are moved from the eccentric portion 41a of the crankshaft 41.
The lubricating oil 45 scattered on the cylinder 3
The lubrication of the sliding parts such as the pistons 32 and 37 and the cylinders 31 and 36 can be improved by flowing into the gaps between the pistons 1 and 36 and the pistons 32 and 37, and the reliability can be improved.

As described above, the two-stage compression refrigeration apparatus of the present embodiment comprises a two-stage compressor 55 having the motor 22, the low-stage compression element 56 and the high-stage compression element 57 in the closed container 21,
Condenser 25 connected to the discharge side of high-stage compression element 57 by piping
An intermediate-pressure expansion device 26 connected to the outlet side of the condenser 25 with a pipe, and an intermediate-pressure suction pipe 5 communicating with the discharge side of the low-stage compression element 56 and the suction side of the high-stage compression element 57.
8, intermediate pressure expansion device 26 and intermediate pressure suction pipe 58
, A low-pressure expansion device 29 connected to the outlet of the condenser 25 or the outlet of the intermediate-pressure expansion device 26, and a low-pressure expansion device 2.
9 and a low-pressure evaporator 30 connected to the suction side of the low-stage compression element 56 of the two-stage compressor 55, wherein the discharge side of the high-stage compression element 57 communicates with the closed vessel 21. As a result, the accuracy of the temperature control in each of the refrigerators can be improved, and the temperature of each part in the refrigerator can be made uniform, and the power consumption can be reduced with higher efficiency. Stage compression element 56 and high stage compression element 57
The lubricating oil 45 can be sufficiently supplied into the respective cylinders 31 and 36, and the pistons 32 and 37 and the cylinder 3
The lubricating properties of the sliding portions such as 1 and 36 are improved, and the reliability can be improved.

(Embodiment 4) FIG. 9 is a longitudinal sectional view of a two-stage compressor used in a two-stage compression refrigeration apparatus according to a fourth embodiment of the present invention.

Hereinafter, description will be made with reference to the drawings. However, the same components as those in the first, second, or third embodiment will be denoted by the same reference numerals, and detailed description will be omitted.
In FIG. 9, reference numeral 64 denotes a two-stage compressor including a low-stage compression element 65 and a high-stage compression element 66. Low stage compression element 65
Is a cylinder 66, a piston 67, a connecting rod 68,
The high-stage compression element 66 includes a cylinder 69, a piston 70, a suction muffler 34, a discharge muffler 35, and the like.
Connecting rod 71, suction muffler 39, discharge muffler 40
Etc. The ratio VH / VL of the cylinder volume VL of the low-stage compression element 65 to the cylinder volume VH of the high-stage compression element 66 is 0.5 to
It is set in the range of 1.3.

The operation of the two-stage compression refrigerating and refrigerating apparatus configured as described above will be described below.

The cylinder volume ratio VH / VL of the two-stage compressor 64
Except for the above, the present refrigeration cycle has substantially the same effects as those of the first, second, or third embodiment. That is, it is possible to improve the accuracy of temperature control in each of the refrigerators and to make the temperature of each part in the refrigerator uniform, to achieve higher efficiency, lower power consumption, and to increase reliability.

In the present embodiment, the ratio VH / V of the cylinder volume VL of the low-stage compression element 65 to the cylinder volume VH of the high-stage compression element 69
L is set in the range of 0.5 to 1.3, and the effect will be described below.

Generally, in a refrigerator, the ratio of the internal volume of the refrigerator to the internal volume of the freezer is about 1.5 to 4.0, which is larger in the refrigerator. , The required refrigerating capacity is smaller than this ratio. Therefore, the ratio of the required refrigerating capacity of the refrigerator to the required refrigerating capacity of the freezer is about 0.5 to 1.1.

For example, the temperature of the refrigerating compartment including the partial compartment is -5 ° C. to 7 ° C., and the temperature of the freezing compartment is -22 ° C. to -18.
When the temperature is set to ° C., the evaporation temperature of the intermediate pressure evaporator 28 is set to about −20 ° C. to 0 ° C., and the evaporation temperature of the low pressure evaporator 30 is set to about −35 ° C. to −25 ° C. When the ratio of the refrigerating capacity between the freezing compartment and the refrigerating compartment is set to 0.5 to 1.1 at these evaporation temperatures, according to the study of the inventor, the cylinder of the low-stage compression element 65 It is known from calculations and experiments that the ratio VH / VL between the volume VL and the cylinder volume VH of the high-stage compression element 69 should be set to 0.5 to 1.3.

If the value of VH / VL is too small, the amount of circulating refrigerant on the high-stage compression side decreases, the refrigerating capacity of the intermediate-pressure evaporator 28 decreases, and the temperature inside the refrigerator compartment rises. Appears. On the other hand, if the value of VH / VL is too large,
The amount of circulating refrigerant on the low-stage compression side is reduced, the refrigeration capacity of the low-pressure evaporator 30 is reduced, and adverse effects such as an increase in the temperature of the freezer compartment appear.

Therefore, by making the ratio of the cylinder capacity of the high-stage compression element 66 to the cylinder volume of the low-stage compression element 64 appropriate, it is possible to use either the freezer compartment of the freezing and refrigeration system or the refrigerator compartment of a different temperature zone. It is possible to appropriately cool the inside of each refrigerator, to reduce the power consumption with high efficiency, without causing the refrigeration capacity to be insufficient or the refrigeration capacity to be excessive.

Further, when the differential pressure between the high pressure and the intermediate pressure is larger than the differential pressure between the intermediate pressure and the low pressure during the operation of the compressor, the cylinder volume of the high-stage compression element 66 is made smaller than the cylinder volume of the low-stage compression element 64. By doing so, the difference between the torque required to compress the high-stage compression element 66 and the torque required to compress the low-stage compression element 64 is reduced, and the maximum torque and torque fluctuation of the motor 22 can be reduced. And vibration can be reduced. In this case, adjustment of each cylinder volume is performed by the piston 6
This is performed by changing the outer diameter of 7, 70. On the other hand, when the differential pressure between the high pressure and the intermediate pressure is smaller than the differential pressure between the intermediate pressure and the low pressure, the same effect can be obtained by making the cylinder volume of the high-stage compression element 66 larger than the cylinder volume of the low-stage compression element 64. Is obtained.

As described above, in the two-stage compression refrigeration apparatus of this embodiment, the ratio VH / VL of the cylinder volume VL of the low-stage compression element 65 to the cylinder volume VH of the high-stage compression element 66 is 0.5-1. 3
, And in addition to the effects of the first or second or third embodiment, either the inside of the freezer compartment of the freezing and refrigeration apparatus and the refrigerator compartment of a different temperature zone, such as the refrigerating compartment. It is possible to appropriately cool the interiors of each refrigerator, to reduce the power consumption with high efficiency, without one of the refrigeration capacity becoming insufficient or the refrigeration capacity becoming excessive. Further, by setting the cylinder volume ratio according to each of the high pressure, the low pressure, and the intermediate pressure, the maximum torque and the torque fluctuation of the motor 22 can be reduced, and the motor efficiency can be improved and the vibration can be reduced.

(Embodiment 5) FIG. 10 is a plan sectional view of a two-stage compressor used in a two-stage compression refrigeration apparatus according to a fifth embodiment of the present invention.

Hereinafter, description will be made with reference to the drawings. However, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In FIG. 10, reference numeral 72 denotes a two-stage compressor including a low-stage compression element 23 and a high-stage compression element 73. An intermediate pressure suction pipe 74 communicates with the discharge side of the low stage compression element 23 and the suction side of the high stage compression element 73. 75 is a suction muffler for the high-stage compression element 73.
The opening of the intermediate pressure suction pipe 74 into the closed container 21 communicates with the suction muffler 75 of the high-stage compression element 73 via a small gap.

The operation of the two-stage compression refrigerating and refrigerating apparatus configured as described above will be described below.

Embodiment 1 Except for the internal structure of the two-stage compressor 46,
Therefore, the effect of the present refrigeration cycle can be obtained almost in the same manner as in the first embodiment. That is, it is possible to improve the accuracy of the temperature control in each of the refrigerators, to make the temperature of each part in the refrigerator uniform, and to further reduce power consumption with higher efficiency.

In this embodiment, the opening of the intermediate pressure suction pipe 74 into the closed vessel 21 communicates with the suction muffler 75 of the high-stage compression element 73 through a small gap. The refrigerant gas that has returned from inside 28 into the closed casing 21 through the intermediate-pressure suction pipe 74 is drawn into the suction muffler 75 on the suction side of the high-stage compression element 73 through a small gap. Therefore, the influence of the heat received from the low-stage compression element 23, the high-stage compression element 73, and the motor 22 on the refrigerant gas is small, and the temperature rise is suppressed to be small. Therefore, the density of the sucked refrigerant gas increases, the refrigerant circulation amount increases, and the efficiency can be improved.

Further, as compared with the case where the suction pipe 74 for intermediate pressure and the suction side of the high-stage compression element 73 are directly connected, the pressure pulsation from the high-stage compression element 73 is It is difficult to diffuse and transmit to the suction pipe 74 for the intermediate pressure, so that generation of noise can be prevented.

As described above, in the two-stage compression refrigeration apparatus of this embodiment, the opening of the intermediate-pressure suction pipe 74 into the closed vessel 21 is provided with a small gap on the suction side of the high-stage compression element 73. Because of the communication configuration, in addition to the effect of the first embodiment, the refrigerant gas returned from the intermediate pressure evaporator 28 into the closed container 21 through the intermediate pressure suction pipe 74 is
Since the air is sucked into the suction side of the high-stage compression element 73 through a small gap, the influence of the heat received from each compression element and the motor 22 is small, and the temperature rise is suppressed to a small level. Therefore, the density of the refrigerant gas to be taken in increases, and the amount of circulating refrigerant increases, and the efficiency can be improved. Further, the pressure pulsation from the high-stage compression element is diffused into the closed vessel and is hardly transmitted to the intermediate-pressure suction pipe, so that generation of noise can be prevented.

[0070]

As described above, the first aspect of the present invention provides a two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container, A condenser pipe-connected to the discharge side, an intermediate-pressure expansion device pipe-connected to the outlet side of the condenser, and an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element An intermediate-pressure evaporator piped between the intermediate-pressure expansion device and the intermediate-pressure suction pipe, and a low-pressure expansion device piped to the outlet side of the condenser or the outlet side of the intermediate-pressure expansion device. A low-pressure evaporator connected between the low-pressure expansion device and the suction side of the low-stage compression element of the two-stage compressor, the discharge side of the low-stage compression element and the high-stage compression. The suction side of the element communicates with the closed container Therefore, the two evaporators of the freezing and refrigerating device can be set to the evaporating temperature suitable for the respective internal temperature of the freezing room and the refrigerating room, respectively, and the accuracy of the temperature control in each internal refrigerator is high. In addition, the temperature of each part in the refrigerator can be made uniform. Particularly, the efficiency of the compressor is improved because the evaporating temperature of the intermediate pressure evaporator can be set high, and the efficiency of the entire refrigeration cycle is improved because the inside of each compartment is not cooled with cold air having a lower temperature than necessary. . Furthermore, since the inside of the closed vessel is at an intermediate pressure, the pressure difference between the compression chamber of each of the low-stage compression element and the high-stage compression element and the inside of the closed vessel is small, and the pressure between each compression element and the inside of the closed vessel is small. The leakage amount of the refrigerant gas can be reduced, and the refrigeration capacity and efficiency of the two-stage compressor can be improved.

The invention according to claim 2 provides a two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container, and a pipe connection between a discharge side of the high-stage compression element and a pipe. A condenser, an intermediate-pressure expansion device connected to the outlet of the condenser by piping, an intermediate-pressure suction pipe communicating with a discharge side of the low-stage compression element and a suction side of the high-stage compression element, and an intermediate-pressure suction pipe. An intermediate-pressure evaporator pipe-connected between an expansion device and the intermediate-pressure suction pipe; a low-pressure expansion device connected to the outlet of the condenser or the outlet of the intermediate-pressure expansion device; A low-pressure evaporator connected by piping between an expansion device and the suction side of the low-stage compression element of the two-stage compressor, wherein the suction side of the low-stage compression element communicates with the closed vessel. Refrigeration equipment Since the evaporating pressures of the two evaporators become low pressure and intermediate pressure, respectively, the evaporator temperatures suitable for the respective internal temperatures of the freezing room and the refrigerating room can be respectively set, and the accuracy of the temperature control in each internal compartment can be achieved. And the temperature of each part in the refrigerator can be made uniform. In addition, since the evaporation temperature of the evaporator for the intermediate pressure can be set higher, the efficiency of the compressor is improved, and the efficiency of the entire refrigeration cycle is improved because the inside of each refrigerator is not cooled with unnecessarily low temperature air. I do. Furthermore, since the suction side of the low-stage compression element communicates with the closed container, the pressure in the closed container becomes low, and the low-temperature refrigerant gas returned from the low-pressure evaporator cools each compression element and motor in the closed container. , Cooling of each compression element can be prevented, reliability can be improved, and motor efficiency can be improved by lowering the temperature of the motor.

The third aspect of the present invention provides a two-stage compressor including a motor, a low-stage compression element and a high-stage compression element in a closed container, and a pipe connection between a discharge side of the high-stage compression element and a pipe. A condenser, an intermediate-pressure expansion device connected to the outlet of the condenser by piping, an intermediate-pressure suction pipe communicating with a discharge side of the low-stage compression element and a suction side of the high-stage compression element, and an intermediate-pressure suction pipe. An intermediate-pressure evaporator pipe-connected between an expansion device and the intermediate-pressure suction pipe; a low-pressure expansion device connected to the outlet of the condenser or the outlet of the intermediate-pressure expansion device; A low-pressure evaporator connected to a pipe between the expansion device and the suction side of the low-stage compression element of the two-stage compressor, wherein the discharge side of the high-stage compression element communicates with the closed vessel. So
Each of the two evaporators of the freezing and refrigeration apparatus can be set to an evaporating temperature suitable for each internal temperature of the freezing room and the refrigerating room,
The accuracy of temperature control in each refrigerator is improved, and the temperature of each part in the refrigerator can be made uniform. Particularly, the efficiency of the compressor is improved because the evaporating temperature of the intermediate pressure evaporator can be set high, and the efficiency of the entire refrigeration cycle is improved because the inside of each compartment is not cooled with cold air having a lower temperature than necessary. . Furthermore,
Since the pressure inside the closed vessel is high, lubricating oil can be sufficiently supplied from the inside of the closed vessel to the compression chamber of each of the low-stage compression element and the high-stage compression element due to the pressure difference. And the reliability can be improved.

The invention described in claim 4 is the first invention.
Alternatively, in addition to the invention described in claim 2 or 3, the ratio VH / VL of the cylinder volume VL of the low-stage compression element to the cylinder volume VH of the high-stage compression element is set in the range of 0.5 to 1.3. In addition, since one of the refrigerators in different temperature zones such as the freezing room and the refrigerator compartment of the freezing and refrigerating device does not have insufficient refrigeration capacity or does not have excessive freezing capacity, The inside can be properly cooled, and the power consumption can be reduced with high efficiency. Also, by setting the ratio of the cylinder volume according to each of the high pressure, the low pressure, and the intermediate pressure, the maximum torque and torque fluctuation of the motor can be reduced,
Improves motor efficiency and reduces vibration.

The invention described in claim 5 is the first invention.
In addition to the above-mentioned invention, since the opening of the suction pipe for intermediate pressure into the closed vessel communicates with the suction side of the high-stage compression element via a small gap, the evaporation for intermediate pressure is further improved. The refrigerant gas returned from the compressor through the intermediate-pressure suction pipe into the closed vessel is drawn into the suction side of the high-stage compression element through a small gap, so the influence of the heat received from each compression element and motor It is small and the temperature rise is kept small. Therefore, the density of the refrigerant gas to be taken in increases, and the amount of circulating refrigerant increases, and the efficiency can be improved. Further, the pressure pulsation from the high-stage compression element is diffused into the closed vessel and is hardly transmitted to the intermediate-pressure suction pipe, so that generation of noise can be prevented.

[Brief description of the drawings]

FIG. 1 is a first embodiment of a two-stage compression refrigeration apparatus according to the present invention.
Refrigerant circuit diagram

FIG. 2 is a plan sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment.

FIG. 3 is a longitudinal sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment.

FIG. 4 is a pressure-enthalpy diagram of a refrigeration cycle in the two-stage compression refrigeration apparatus of the embodiment.

FIG. 5 is a second embodiment of a two-stage compression refrigeration apparatus according to the present invention.
Refrigerant circuit diagram

FIG. 6 is a plan sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment.

FIG. 7 is a third embodiment of a two-stage compression refrigeration apparatus according to the present invention.
Refrigerant circuit diagram

FIG. 8 is a plan sectional view of a two-stage compressor used in the two-stage compression refrigeration apparatus of the embodiment.

FIG. 9 is a fourth embodiment of a two-stage compression refrigeration apparatus according to the present invention.
Sectional view of a two-stage compressor in Japan

FIG. 10 is a plan sectional view of a two-stage compressor in a fifth embodiment of a two-stage compression refrigeration apparatus according to the present invention.

FIG. 11 is a piping diagram of a two-stage compression refrigeration cycle using a conventional two-stage compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Two-stage compressor 21 Closed container 22 Motor 23 Low-stage compression element 24 High-stage compression element 25 Condenser 26 Intermediate pressure expansion device 27 Intermediate pressure suction pipe 28 Intermediate pressure evaporator 29 Low pressure expansion device 30 Low pressure evaporator 46 2 Stage compressor 47 Low stage compression element 48 High stage compression element 49 Intermediate pressure suction pipe 55 Two stage compressor 56 Low stage compression element 57 High stage compression element 58 Intermediate pressure suction pipe 64 Two stage compressor 65 Low stage compression element 66 High Stage compression element 72 Two stage compressor 73 High stage compression element 74 Intermediate pressure suction pipe

[Procedure amendment]

[Submission date] September 24, 1999 (1999.9.2)
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kosuke Tsuboi 4-5-2-5 Takaida Hondori, Higashi-Osaka-shi, Osaka Matsushita Refrigerator Co., Ltd. F-term (reference) 3H076 AA04 AA38 BB21 BB31 BB32 BB35 BB43 CC28 CC91 CC92 CC94 CC99

Claims (5)

[Claims] 1. A two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container, a condenser connected to a discharge side of the high-stage compression element by piping, An intermediate-pressure expansion device connected to the outlet side with a pipe, an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element, the intermediate-pressure expansion device and the intermediate-pressure suction pipe, An evaporator for intermediate pressure connected between the pipes, a low-pressure expansion device connected to the outlet side of the condenser or the inlet side of the expansion device for intermediate pressure, and the low-pressure expansion device and the two-stage compressor. A low-pressure evaporator connected to the piping between the low-stage compression element and the suction side,
A two-stage compression refrigeration apparatus in which a discharge side of the low-stage compression element and a suction side of the high-stage compression element communicate with the closed container. 2. A two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed vessel, a condenser connected to a discharge side of the high-stage compression element by piping, An intermediate-pressure expansion device connected to the outlet side with a pipe, an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element, the intermediate-pressure expansion device and the intermediate-pressure suction pipe, An evaporator for intermediate pressure connected between the pipes, a low-pressure expansion device connected to the outlet side of the condenser or the inlet side of the expansion device for intermediate pressure, and the low-pressure expansion device and the two-stage compressor. A low-pressure evaporator connected to the piping between the low-stage compression element and the suction side,
A two-stage compression refrigeration apparatus in which the suction side of the low-stage compression element communicates with the inside of the closed container. 3. A two-stage compressor having a motor, a low-stage compression element and a high-stage compression element in a closed container, a condenser connected to a discharge side of the high-stage compression element by piping, An intermediate-pressure expansion device connected to the outlet side with a pipe, an intermediate-pressure suction pipe communicating with the discharge side of the low-stage compression element and the suction side of the high-stage compression element, the intermediate-pressure expansion device and the intermediate-pressure suction pipe, An evaporator for intermediate pressure connected between the pipes, a low-pressure expansion device connected to the outlet side of the condenser or the inlet side of the expansion device for intermediate pressure, and the low-pressure expansion device and the two-stage compressor. A low-pressure evaporator connected to the piping between the low-stage compression element and the suction side,
A two-stage compression refrigeration unit in which a discharge side of the high-stage compression element communicates with the inside of the closed container. 4. The ratio VH / VL of the cylinder volume VL of the low-stage compression element and the cylinder volume VH of the high-stage compression element is set in a range of 0.5 to 1.3. Item 3
2. The two-stage compression freezing and refrigeration apparatus according to 1. 5. The two-stage compression refrigeration apparatus according to claim 1, wherein an opening of the intermediate-pressure suction pipe into the closed vessel communicates with a suction side of the high-stage compression element through a small gap.