JPH0476358A - Device in refrigerating cycle - Google Patents

Abstract

PURPOSE:To keep refrigerant from flowing in reverse from the discharge port of a low-level compressor into a gas-liquid separator and also always free the operation of a high-level compressor from liquid compression by connecting to a line connecting the discharge port of the low-level compressor and the suction port of the high-level compressor at an intermediate point of this line a bypass provided with a check valve from the gas part of a gas-liquid separator, in which the gas is in a state of medium-pressure saturation. CONSTITUTION:The refrigerant in a state of medium-pressure gas resulting from the compression by a low-level compressor 3 joins refrigerant flowing in a state of medium-pressure saturated gas through a bypass 16 and the combined flow is drawn into a high-level compressor 4 and discharged as high-temperature high-pressure refrigerant gas and sent to a condenser 5; high-pressure liquid refrigerant thereby liquefied by condensation undergoes pressure reduction to a medium pressure by a high level-side expansion valve 6; thereby turned into two phases, the refrigerant flows into a gas-liquid separator 7; the gaseous refrigerant in the gas part 7a in the gas-liquid separator 7 flows through the bypass 16 and a check valve 17 therein and is again drawn into the high-level compressor 4, whereas the medium-pressure saturated liquid in the liquid part 7b in the gas-liquid separator 7 is turned into low-pressure refrigerant in two phases by a low-level side expansion valve 8, gasefied by an evaporator 9, and again drawn into a low-level compressor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a refrigeration cycle device in which high and low two-stage compressor sections are housed in a single closed shell.

[Prior Art] Figure 3 is a refrigerant circuit diagram of a conventional refrigeration cycle device disclosed in Japanese Patent Application Laid-Open No. 2-10062.
) is the compressor, (la) is its closed shell, (3) is the internal low stage compressor section, (4) is the internal high stage compressor section, (
5) is a condenser, (6a) is a first capillary tube, (7) is a gas-liquid separator, (8a) is a second capillary tube, (9) is an evaporator, (10) is an injection path, ( 11) is an auxiliary pressure reducing device, and (12) is a liquid refrigerant introduction path.

Next, the operation will be explained. The medium-pressure medium-temperature gas refrigerant compressed by the low-stage compressor section (3) joins with the medium-pressure, saturated-temperature gas or slightly moist refrigerant that has passed through the injection path (10), and flows into the high-stage compressor section. At step (4), the gas is compressed into high-pressure, high-temperature gas and reaches the condenser (5). Most of the high-pressure liquid refrigerant condensed and liquefied here is depressurized in the first capillary tube (6a) to become a medium-pressure two-phase refrigerant and flows into the gas-liquid separator (7). Here, the intermediate pressure saturated gas separated into gas and liquid and a part of the high pressure liquid refrigerant from the condenser (5) pass through the injection path (io) together with the intermediate pressure two-phase refrigerant whose pressure has been reduced in the auxiliary pressure reducing device (11). , is sucked into the high stage compressor section (4). On the other hand, the gas-liquid separator (7)
The liquid inside is depressurized in the second capillary tube (8a), becomes a low-pressure two-phase refrigerant, is gasified in the evaporator (9), and is sucked into the low stage compressor section (3) again to form a refrigerant circuit. It turns out.

[Problem to be solved by the invention] Since the conventional refrigeration cycle device is configured as described above, the refrigerant flows backward through the injection path when the compressor is started, and the pressure rise speed at the time of startup is slow. Alternatively, when the amount of refrigerant injected from the auxiliary pressure reducing device is inappropriate, there is a problem in that the high stage compressor section causes liquid compression.

This invention was made to solve the above-mentioned problems, and it prevents the refrigerant from flowing backwards from the discharge port of the low-stage compressor section to the gas-liquid separator, and also prevents the high-stage compressor section from flowing back into the gas-liquid separator. The object is to obtain a refrigeration cycle device that does not cause liquid compression.

[Means for Solving the Problems] The refrigeration cycle device according to the present invention includes a medium-pressure saturated gas and The bypass pipe from the gas section of the gas-liquid separator is connected via a check valve.

[Function] In the refrigeration cycle device of the present invention, the intermediate pressure gas discharged from the low stage compressor section when the compressor is started does not flow back to the gas-liquid separator due to the check valve, and is transferred to the high stage compressor. Since it is sucked into the machine part, the pressure rise time at startup is shortened. Furthermore, the suction gas to the high-stage compressor section is a mixed refrigerant consisting only of the superheated gas discharged from the low-stage compressor section and the medium-pressure saturated gas in the gas-liquid separator, so no liquid compression occurs8 [Example] Below An embodiment of this invention will be described. That is, in Fig. 1, (1) is the compressor, (1a) is its closed shell, (2) is the internal electric motor, (3) is the internal low stage compressor section driven by this, and (4) is the internal low stage compressor section. Similarly, the high-stage compressor section, (5) is a condenser communicated in the upper v2 closed shell, (6) is the high-stage expansion valve connected to this, and (7) is the gas section ( 7a) a gas-liquid separator connected to
(8) is a low-stage expansion valve connected to the liquid part (7b) of this gas-liquid separator; (9) is an evaporator connected to this expansion valve;
(13) is the discharge port of the low-stage compressor section, and (14) is the suction port of the high-stage compressor section, which are communicated by a connecting pipe (15). (16) is a bypass pipe drawn out from the gas section (7a) of the gas-liquid separator (7), and a check valve (17)
It is connected to the middle of the connecting pipe (15) via the connecting pipe (15).

Next, the operation will be explained. The medium-pressure medium-temperature gas refrigerant compressed by the low-stage compressor section (3) passes through the bypass pipe (16
), it is sucked into the high-stage compressor section (4), becomes a high-temperature, high-pressure gas refrigerant, and is discharged to the condenser (5).

The high-pressure liquid refrigerant condensed and liquefied here is depressurized to intermediate pressure by the high-stage expansion valve (6), becomes a two-phase refrigerant, and flows into the gas-liquid separator (7). The gas refrigerant in the gas section (7a) in the gas-liquid separator (7) is passed through the check valve (17) by the bypass pipe (16).
is sucked into the high-stage compressor section (4) again. - The medium-pressure saturated liquid in the liquid part (7b) in the liquid separator (7) becomes a low-pressure two-phase refrigerant in the low-stage expansion valve (8), and becomes a low-pressure two-phase refrigerant in the evaporator (
In step 9), it is evaporated into gas and sucked into the low-stage compressor section (3) again, thus configuring a two-stage compression type refrigeration cycle. In addition, each point (a) (b) (c) (d) (e) (f) (
g) (h) (i) The locations are as indicated by the same reference numerals on the Mollier diagram in FIG.

In the above embodiment, a low-stage expansion valve and a high-stage expansion valve are used, but these may be capillary tubes or electronic expansion valves.

[Effects of the Invention] Since the refrigeration cycle device of the present invention is configured as described above, there is no backflow of refrigerant from the discharge port of the low stage compressor section into the gas-liquid separator, and This has the effect of providing a refrigeration cycle device in which there is no fear of liquid compression during startup, and the pressure rises quickly at startup.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit diagram showing one embodiment of the refrigeration cycle apparatus of the present invention, FIG. 2 is a Mollier diagram thereof, and FIG. 3 is a refrigerant circuit diagram of a conventional refrigeration cycle apparatus. In the figure, (1) is the compressor, (la) is the closed shell, (
2) is an electric motor, (3) is a low-stage compressor section, (4) is a high-stage compressor section, (5) is a condenser, (6) is a high-stage expansion valve, and (7) is a high-stage compressor section.
) is a gas-liquid separator, (7a) is a gas part, (7b) is a liquid part,
(13) is a discharge port, (14) is an inlet, (15) is a connecting pipe, (16) is a bypass pipe, and (17) is a check valve. Compressor port 5, condenser 6: KF? tfAlfll'yl Well 7゛Gas-Liquid OI
! Vessel 7a Kasu Gloss 7b 'Part 7 Figure

Claims (1)

[Claims] A compressor having a single electric motor, a low-stage compressor section and a high-stage compressor section driven by the motor in a closed shell, a condenser communicated with the shell, and a high-stage expansion valve. In a refrigeration cycle comprising a gas-liquid separator whose gas section is connected through a gas-liquid separator, and an evaporator that is connected to the liquid section of the separator through a low-stage expansion valve and communicates with the low-stage compressor section,
A bypass pipe from the gas section of the gas-liquid separator is connected via a check valve in the middle of the connecting pipe connecting the discharge port of the low-stage compressor section and the suction port of the high-stage compressor section. Features of refrigeration cycle equipment.