JPH03105156A - Freezer with economizer and its operation controlling method - Google Patents

Abstract

PURPOSE:To prevent a temperature of discharged gas over-rizing and improve a reliability of a compressor by a method wherein a refrigerant is bypassed in an expansion valve and an economizer for a specified period of time before executing a load-up operation when the compressor is operated to increase its load. CONSTITUTION:When a compressor 1 is operated to increase its load, an instruction signal for increasing a capacity if outputted to the compressor 1, thereby it is detected by a sensing means 26, and a changing-over means 23 is controlled by a controlling means 27, a part of refrigerant flowing from a condensor 2 in a main refrigerant circuit 10 is flowed to a second bypassing passage 21. After a predetermined time elapses, an increasing amount of the compressor 1 is adjusted and a part of the refrigerant in the main refrigerant circuit 10 is flowed to the economizer in the first bypassing passage 17. Due to this fact, when the compressor 1 is increased in its load, even if a degree of opening of an automatic expansion valve is temporarily decreased due to a delay in detection of a thermo-sensitive cylinder 19a of a first pressure reducing mechanism 19, the refrigerant as wall as liquid not passing through the economizer for a specified period of time before the load increasing operation of the compressor 1 is executed is discharged to a location where an intermediate pressure of the compressor 1 is attained and then a temperature of the discharged gas in prevented rapidly rizing.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a refrigeration system in which an economizer is disposed in a refrigerant circuit and a method for controlling its operation, particularly for controlling the temperature of gas discharged from a compressor. Regarding.

(Prior Art) Conventionally, for example, "Refrigerating Air Theory Handbook, 4th Edition, Basic Edition" (May 30, 1980, published by Japan Refrigeration Association)
As disclosed on page 382 of , a refrigeration system equipped with an economizer that increases the refrigerating capacity while controlling the capacity of the compressor and condenser is known. This refrigeration equipment with economizer consists of a compressor, condenser, liquid receiver, main pressure reducing valve,
It is equipped with a refrigerant circuit in which the evaporator and droplet separator are sequentially connected by piping. The liquid refrigerant from the liquid receiver is depressurized by a pressure reducing valve, gasified by an intercooler (economizer), and then bypassed to the intermediate pressure point of the compressor. The heat of evaporation supercools the liquid refrigerant in the main refrigerant circuit.

In addition, the above-mentioned document describes that after reducing the pressure of the liquid refrigerant in a liquid pipe, the receiver separates the gas refrigerant and the liquid refrigerant, and the gas refrigerant is bypassed to the intermediate pressure point of the compressor, and the low-temperature A device equipped with an economizer receiver that evaporates only liquid refrigerant using an evaporator has also been disclosed. and,
With such an economizer cycle, the enthalpy change of the refrigeration cycle is increased compared to when no economizer is used, and the refrigeration effect can be increased.

(Problem to be Solved by the Invention) By the way, in the above-mentioned refrigeration system having an economizer cycle, if an automatic expansion valve whose opening degree is controlled by a temperature-sensitive tube arranged in the discharge pipe is used as the pressure reduction mechanism in the bypass path, the compression The temperature of the discharge gas of the machine can be controlled.

In other words, when the discharge gas temperature is high, the opening of the expansion valve is increased to reduce the degree of superheating, thereby suppressing the rise in the temperature of the discharged gas, while when the temperature of the discharge gas is low, the opening of the expansion valve is decreased to prevent overheating. By increasing the temperature, it is possible to suppress a decrease in the temperature of the discharged gas. but,
In that case, for example, when a compressor with an unloader is loaded, the discharge gas pressure will rise immediately, but the rise in the discharge gas temperature will not be immediately detected by the thermosensor, so the temperature will be low but the pressure will temporarily rise. When a high temperature condition occurs, the automatic expansion valve determines that the degree of superheat has decreased and operates in the direction of throttling.As a result, the discharge gas temperature rises excessively, causing deterioration of the lubricating oil and reducing the reliability of the compressor. There was a risk of loss.

The present invention has been made in view of the above, and its purpose is to stop the function of the economizer when loading the compressor and inject refrigerant into the compressor. The purpose of the present invention is to cool down the temperature of the discharged gas in advance, thereby improving its reliability.

(Means for Solving the Problem) In order to achieve the above object, the solving means of the invention according to claim (1) is an economizer that transfers a part of the refrigerant in the main refrigerant circuit to the intermediate pressure point of the compressor. When the refrigerant is bypassed through the economizer, the refrigerant is bypassed through the economizer for a predetermined period of time before loading the compressor, and the refrigerant injection effect prevents an excessive rise in the temperature of the discharged gas from the compressor. We are trying to prevent this from happening.

Specifically, in this invention, as shown in FIG. (
The main refrigerant circuit (
10) and a part of the liquid refrigerant flowing from the condenser (2>) of the main refrigerant circuit (10) to the main pressure reducing mechanism (3).
) and the evaporator (8) and is disposed in the first bypass path (17>) which bypasses the evaporator (8) and discharges the gas to the intermediate pressure point of the compressor (1), and the discharge side gas pipe (9b) of the compressor (1). a first pressure reducing machine side (19) consisting of an automatic expansion valve whose opening degree is adjusted by a temperature sensing tube (19a) and which reduces the pressure of the refrigerant flowing through the first bypass path (17); and the first pressure reducing mechanism (19). Based on the refrigerant pressure reduction effect caused by the refrigerant, the refrigeration system is equipped with an economizer that subcools the liquid refrigerant flowing from the evaporator (8) to the main pressure reduction mechanism (3) to increase the refrigerating capacity.

and a second bypass path (21) that allows the liquid refrigerant in the first bypass path (17) to bypass the economizer and the first pressure reducing mechanism (19) and flow to an intermediate pressure location of the compressor (1); a second pressure reducing mechanism (22) that reduces the pressure of the refrigerant flowing through the second bypass path (21);
0) selectively switches the path for bypassing a portion of the liquid refrigerant to the intermediate pressure point of the compressor (1) to the economizer side of the first bypass path (17) and the second bypass path (21) side. A switching means (23) is provided.

It also includes a detection means (26) for detecting that a command signal to increase the capacity of the compressor (1) has been output, and a detection means (26) which receives the output of the detection means (26) and commands the compressor (1) to increase the capacity. When the signal is output, a part of the refrigerant in the main refrigerant circuit (10) is transferred to the second
After causing the refrigerant to flow to the bypass path (21) side and increasing the capacity of the compressor (l), a part of the refrigerant in the main refrigerant circuit (10) is caused to flow to the economizer side of the first bypass path (17). Control means (27) for controlling the switching means (23)
It is characterized by having the following.

In the invention according to claim (2), as shown in FIG. 4, the first bypass path (17) is connected to the main refrigerant circuit (IO) so that the liquid refrigerant supercooled by the economizer can be taken out.

In the invention according to claim (3), as shown in FIGS. 2 and 4, the economizer includes an inner pipe (12) constituting a part of the main refrigerant circuit (10), is arranged with an annular space (14) around the annular space (14).
is the outer pipe (13) that constitutes a part of the first bypass path (17).
) and an intercooler (11) that exchanges heat between the refrigerant depressurized by the first pressure reducing mechanism (19) and the liquid refrigerant in the inner pipe (l2).

Further, in the invention according to claim (4), as the operation control method for the economizer-equipped refrigeration system, when a command signal to increase the capacity of the compressor (1) is output to the refrigeration system having the above configuration, , a part of the liquid refrigerant in the main refrigerant circuit (10) bypasses the economizer and flows to the intermediate pressure point of the compressor (1) a predetermined time before increasing the capacity of the compressor (1), and then , the capacity of the compressor (1) is increased.

(Function) With the above configuration, in the invention according to claim (1), when a command signal to increase the capacity of the compressor (1) is outputted to the compressor (1) during load-up of the compressor (1), it is possible to Detection means (
26), and the switching means (23) is controlled by the control means (27>) which receives the output of this detection means (26), and first, the main depressurization is controlled from the condenser (2>) of the main refrigerant circuit (10). A portion of the refrigerant reaching the mechanism (3) passes through the second bypass path (
21> side. Next, after a predetermined period of time has elapsed, the capacity of the compressor (1) is adjusted to increase, and then a portion of the refrigerant in the main refrigerant circuit (10) is transferred to the first bypass path (10).
7) is distributed to the economizer side. Therefore, even if the opening degree of the automatic expansion valve becomes temporarily small due to the detection delay of the temperature sensing cylinder (19a) of the first pressure reducing mechanism (19) during load-up of the compressor (1), the compressor (1) ) before the load-up is executed, the refrigerant mixture of liquid and gas that does not pass through the economizer is discharged to the intermediate pressure point of the compressor (1) for a certain period of time, and due to the injection effect, the refrigerant is discharged. Excessive rise in gas temperature is prevented.

In the invention according to claim '2J, the first bypass path (17
) is connected to the main refrigerant circuit (10) so as to take out the liquid refrigerant supercooled by the economizer, so the supercooled liquid refrigerant always flows through the first bypass path (17). The injection liquid refrigerant is secured by the liquid refrigerant. This eliminates the need for a liquid reservoir such as a receiver, making it possible to simplify the circuit configuration and downsize the refrigeration system.

In the invention according to claim (3), the economizer is an intercooler (11) comprising an inner pipe (12) and an outer pipe (13).
The annular space (1
4) through which the refrigerant whose pressure has been reduced by the first pressure reduction mechanism (19) flows;
Since the liquid refrigerant in the inner tube (12) is supercooled by this refrigerant, the effect as an economizer can be developed satisfactorily.

In the invention according to claim (4), when the compressor (1) is loaded up, when a command signal to increase the capacity of the compressor (1) is output, first, the refrigerant in the main refrigerant circuit (10) is A portion bypasses the economizer and is distributed to the compressor (1).Next, after a predetermined period of time has elapsed, the capacity of the compressor (1) is adjusted to increase. Similar to the invention, even if the opening degree of the automatic expansion valve (19) is temporarily reduced due to a detection delay of the temperature sensing tube (19a), the refrigerant mixed with liquid and gas that does not pass through the economizer for a certain period of time remains in the compressor. The gas is discharged to a location where the pressure is intermediate in (1), and an excessive rise in the temperature of the discharged gas is prevented.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows the overall configuration of a chilled water economizer-equipped refrigeration system (A) according to an embodiment of the present invention, in which (1) is a turbo type;
Screw type, scroll type, etc. compressor, (la) is an unloader that adjusts the operating capacity of the compressor (l) in five steps of 100%, 75%, 50%, 25% and 0% by suction vane control. It is a mechanism. (2) is a condenser, (3) is an external pressure equalizing automatic expansion valve for the evaporator next to the main pressure reducer. (4) is a water cooler for cooling water; (4) consists of a closed shell (7) with a water port (5) in the lower part and a water outlet (6) in the upper part, and a transmission disposed in the shell (7) for heat exchange. The compressor (1), the condenser (2), the expansion valve (3), and the evaporator (8) (heat transfer tubes) are sequentially connected to the liquid tube (8). 9
a) and a gas pipe (9b) so that the refrigerant can be circulated, and the cold heat taken away by the condenser (2) is transferred to the evaporator (8) and then inside the water cooler (4). A main refrigerant circuit (10) is configured to cool the water. (3a) is a temperature-sensing tube installed in the gas pipe (9b) on the outlet side of the evaporator (8). This controls the opening degree of the valve (3).

The branch pipe (9a) of the main refrigerant circuit (10) is equipped with an intercooler (
11) is provided. This intercooler (l1) is
An inner tube (l2) and a closed annular space (14) around it.
It consists of a double pipe with an outer pipe (13) arranged concentrically with a gap in between, and the inside of the inner pipe (l2) is part of the main refrigerant circuit (10). In addition, the end of the annular space (14) between the inner pipe (12) and the outer pipe (13) on the condenser (2) side is connected to the intercooler (11> and the condenser (2)). The liquid pipe between (
9a) via piping (l5), and the end on the expansion valve (3) side is connected to the intermediate pressure point of the compressor (1) through piping (l6).
These two pipes (15) are connected to each other via
．． (l6) or the annular space (14) of the intercooler (11)
), a part of the refrigerant flowing from the condenser (2) to the automatic expansion valve (3) bypasses the expansion valve (3) and the evaporator (8) and is discharged to the intermediate pressure point of the compressor (1). A first bypass path (17) is configured such that the first bypass path (17)

In the middle of the above piping (l5), there is a first bypass path (17).
An automatic expansion valve (19) for the cooler is provided as a first pressure reduction mechanism for reducing the pressure of the refrigerant flowing through the cooler. (19a) is a temperature-sensitive cylinder installed in the gas pipe (9b) on the discharge side of the compressor (1), which controls the opening degree of the expansion valve (19).

Then, the liquid refrigerant flowing through the liquid pipe (9a) of the main refrigerant circuit (10) is cooled to a supercooled state by the intercooler (11), and a part of the supercooled liquid refrigerant is transferred to the pipe (15).
) and depressurized by the automatic expansion valve (19),
This reduced pressure refrigerant is transferred to the annular space of the intercooler (11) (
14), after exchanging heat with the liquid refrigerant in the inner pipe (12),
It is designed to be discharged to a portion of the compressor (1) that has an intermediate pressure.

In addition, a branch part from the liquid pipe (9a) and an intercooler (1
1) constituting the first bypass path (17) between
One end of piping (20) is connected to l5), and this piping (
The other end of 20> is connected to the pipe (1B) (first bypass path (17)) between the intercooler (11) and the compressor (1), and this pipe (20) connects the first bypass The liquid refrigerant in the passage (17) is passed through the intercooler (11) and the expansion valve (
A second bypass path (21) is provided that bypasses the air pressure (19) and flows to the intermediate pressure point of the compressor (+).

Further, in the middle of the piping (20), a second bypass path (
A cavillary tube (22) is provided as a second pressure reduction mechanism for reducing the pressure of the refrigerant flowing through the refrigerant (21).

Furthermore, a route for bypassing a portion of the refrigerant in the liquid pipe (9a) of the main refrigerant circuit (10) to a location where the intermediate pressure of the compressor (
) side and the second bypass path (21) side is provided. This switching machine +J
I (23) is a first solenoid valve (SV 1) disposed in a pipe (15) between a connection to a second bypass path (21) and an expansion valve (19), and a pipe (20>). a second solenoid valve (SV!') disposed in the first solenoid valve (SV!');
V1) is switched to the fully open state at the same time as the compressor (1) is started. Then, this fully open first solenoid valve (SV +
), by opening and closing the second solenoid valve (SV, = ), the first or second bypass path (+7), (21
) and close the second solenoid valve (SV 2 ), the first path bypasses a part of the refrigerant in the main refrigerant circuit (10) to the intermediate pressure point of the compressor (1).
The bypass path (17) is placed on the intercooler (11) side, and when the second solenoid valve (SV!) is opened, the bypass path is placed on the second bypass path (21) side.

Both solenoid valves (SV + ), (SV
z) is configured to be operated and controlled by a control device (24). A measurement signal from a water temperature sensor (25) that detects the water temperature in the water cooler (4) is input to this control device (24).The flowchart of FIG. 3 shows the control procedure in the control device (24). To explain, during operation when the compressor (1) is operated at, for example, 50% capacity, first, in step S1, the water temperature in the water cooler (4) is higher than the target temperature and the compressor (1) is operated. It is determined whether a load-up command signal for operating at 75% capacity has been output, and if this determination is No, the same step SI is repeated.On the other hand, if the determination is YES, the process advances to step S2, and the second electromagnetic After opening the valve (SV!), the first set time 1+ (for example, 10
Step S3 is repeated until the determination becomes YES. If the determination becomes YES after the set time t1 has elapsed, the unloader mechanism (la) increases the compressor (1) by one step to bring the operating capacity to 7596 in step S4. After that, the process proceeds to step S5, where the second set time t2 (temperature-sensing cylinder (1
It is determined whether a period of time longer than the time for which the detection state in 9a) is reversed (for example, one minute) has elapsed, and the same step S5 is repeated until the determination becomes YES. Then, a predetermined time t
If the determination becomes YES after step 2, the second solenoid valve (SV 2 ) is completely turned off in step S6, and then
Return to the first step S1.

That is, in this embodiment, step S1 of the above flow
Accordingly, a detection means (2G) is configured to detect that a command signal to increase the operating capacity of the compressor (1) is output to the unloader mechanism (1a) of the compressor (1).

Further, in steps 82 to S6, the detection means (2
When a capacity increase command signal is output to the compressor (1) in response to the output from B), a portion of the refrigerant in the main refrigerant circuit (10) is the second
After flowing to the bypass path (21) side and increasing the capacity of the compressor (1), the main refrigerant circuit (IO
A control means (27) is configured to control the switching mechanism (23) so that a part of the refrigerant in the first bypass passage (17>) flows to the intercooler (11) side.

Next, the operation of the above embodiment will be explained.

When the compressor (1) starts, the first solenoid valve (SV + )
is in an open state, and the second solenoid valve (SV 2 ) is closed. At this time, the compressor (1) of the main refrigerant circuit (IO)
The high-pressure gas refrigerant discharged from the condenser <2> is liquefied, and then cooled in the inner pipe (l2) of the intercooler (l1>) to a supercooled state.This liquid refrigerant is passed through the condenser expansion valve ( 3)
After the pressure is reduced in the water cooler (4), the water is evaporated in the evaporator (8) of the water cooler (4), and the water in the water cooler (4) is cooled by this heat of evaporation. The gas refrigerant evaporated in the evaporator (8) is transferred to the compressor (1)
is sucked into and recompressed. The refrigerating capacity of the refrigeration system (A) is increased by supercooling the liquid refrigerant in the intercooler (11).

Further, a part of the liquid refrigerant flowing from the condenser (2) to the condenser expansion valve (3) flows to the first bypass path (17), and after this refrigerant is depressurized by the condenser expansion valve (19>), The refrigerant passes through the annular space (14) of the intercooler (l1), where it subcools the liquid refrigerant of the main refrigerant circuit (10). It is discharged to a location where the pressure is high.Then, the expansion valve for the cooler (1
The opening degree of 9) is the temperature sensing tube (19a) on the discharge side of the compressor (1).
This control controls the discharge gas temperature of the compressor (1) to a constant temperature.

During such operation, the water temperature in the water cooler (4) is detected by the water temperature sensor (25>), and when the water temperature is higher than the target temperature, the control device (24) sends the unloader mechanism (1) of the compressor (1). A load-up command signal is outputted to the load-up command signal la).The output of this load-up command signal first opens the second solenoid valve (Sv2> for a first set time t+ (10 seconds). This second solenoid valve (
SV! ), a part of the refrigerant flowing from the condenser (2) to the condenser expansion valve (3) bypasses the intercooler (11) through the second bypass path (21>) and flows into the compressor (1). Flows to the point where the intermediate pressure is reached.The above set time t
1, an actual load-up signal is output to the unloader mechanism (la), and the operating capacity of the compressor (1) increases. After this load-up, the second set time t2
(1 minute) and when the operating state of the compressor (1) becomes stable, the second electromagnetic valve (SV 2 ) closes to its original state.

Therefore, in this embodiment, when the compressor (1) is loaded up, even if the opening degree of the cooler expansion valve (19) is temporarily reduced due to the detection delay of the temperature sensing tube (19a), the compression Before the load-up of the compressor (1) is executed, for a certain period of time t1, the refrigerant mixture of liquid and gas that does not pass through the intercooler (11) is discharged to the intermediate pressure point of the compressor (1). In other words, the injection effect prevents an excessive rise in the temperature of the discharged gas, and the compressor (1)
reliability can be improved.

FIG. 4 shows the main part of another embodiment of the present invention. Note that the same parts as in FIG. 2 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this embodiment, the first bypass path (17') connects the intercooler (11) and an automatic expansion valve to the main refrigerant circuit (10) so as to take out the liquid refrigerant supercooled by the intercooler (11). (3). Therefore, in this case, supercooled liquid refrigerant always flows through the first bypass path (17'), and this liquid refrigerant causes injection The refrigerant for use is secured.Therefore, there is no need for a liquid reservoir such as a receiver to store the refrigerant for injection, and by omitting this liquid reservoir,
The circuit configuration of the refrigeration device (A) is simplified and the refrigeration device (A)
) while reducing the size of the compressor (1), the temperature of the discharged gas can be stably controlled by liquid injection, and the durability and reliability of the compressor (1) can be improved.

In addition, in the main refrigerant circuit (10), an intercooler (1
Since the supercooled liquid refrigerant is used as the liquid refrigerant for injection, the cooling effect due to the injection of this supercooled liquid refrigerant increases, and
The amount of liquid refrigerant for injection can be relatively small. Therefore, the amount of refrigerant depressurized by the automatic expansion valve (19) for the cooler is also reduced, and the expansion valve ({9) can be made smaller by the amount of refrigerant that is smaller, thereby reducing costs and reducing the size of the expansion valve ( 19) can improve durability and reliability.

(Effects of the Invention) As explained above, according to the inventions according to claims (1) and (4), a part of the refrigerant from the condenser of the main refrigerant circuit to the main pressure reducing mechanism is brought to the intermediate pressure of the compressor. For refrigeration equipment with an economizer, the refrigerant is depressurized by an automatic expansion valve in the middle of the bypass, then evaporated by an economizer, and the refrigerant in the main refrigerant circuit is supercooled by this economizer. By making the refrigerant bypass the expansion valve and economizer for a predetermined period of time before executing the load-up, the opening of the automatic expansion valve may temporarily change due to the detection delay of the thermosensor that detects the discharge gas temperature. Even if the refrigerant is small in size, it is possible to obtain an injection effect by discharging the mixed refrigerant of liquid and gas that does not pass through the economizer for a certain period of time to the intermediate pressure point of the compressor, thereby preventing an excessive rise in the discharge gas temperature. This can be prevented and the reliability of the compressor can be improved.

According to the invention according to claim (2), the bypass path is
Since the economizer is connected to the main refrigerant circuit so as to take out the supercooled liquid refrigerant, the supercooled liquid refrigerant can always flow through the bypass path to secure the liquid refrigerant for the injector, which simplifies the circuit configuration and It is possible to downsize the refrigeration device.

According to the invention according to claim (3), the economizer is constituted by an intercooler consisting of an inner pipe and an outer pipe, and the annular space between the two pipes is used as a refrigerant passage whose pressure is reduced by an expansion valve. Since the liquid refrigerant inside the pipe is supercooled,
The effect as an economizer can be demonstrated well.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the present invention. The drawings following FIG. 2 show embodiments of the present invention, FIG. 2 is a refrigerant piping system diagram showing the overall configuration of the refrigeration system, and FIG. 3 is a flowchart showing the control procedure. FIG. 4 is a diagram corresponding to FIG. 2 showing another embodiment. (A), (A')... Refrigeration device (1)... Compressor (LA)... Unloader mechanism <2)... Condenser (3)... Expansion valve (main pressure reducing mechanism) (8)... Evaporator (9)... Piping (9b)... Gas pipe (IO)... Main refrigerant circuit (11)... Intercooler (economizer) (l2)...
... Inner pipe (I3) ... Outer pipe (14) ... Annular space (17), (17') ... First bypass path (1
9)... Expansion valve (first pressure reducing mechanism) (19a)... Temperature sensing cylinder (21)... Second bypass path (22>... Cabillary tube (second pressure reducing mechanism) (
23)...Switching mechanism (switching means) (24)...Control device (26)...Detection means (27>...Control means 19a] ]a] Figure (↓2)...Inside Pipe (L3)... Outer pipe <14>... Annular space (upper 7), (17')... First binoculars path (engineering 9)... Expansion valve (first pressure reducing rocky structure )(23)・
...Switching mechanism (switching means) (24) ...Control device (26) ...Detection means (27) ...Control means Fig. 3 197

Claims (4)

[Claims] (1) A compressor (1) whose operating capacity can be adjusted by an unloader mechanism (1a), a condenser (2), a main pressure reducing mechanism (3), and an evaporator (8) are successively connected by piping (9). A part of the liquid refrigerant flowing from the main refrigerant circuit (10) and the condenser (2) of the main refrigerant circuit (10) to the main pressure reducing mechanism (3) bypasses the main pressure reducing mechanism (3) and the evaporator (8). The gas is opened by a first bypass path (17) that allows the gas to be discharged to an intermediate pressure point of the compressor (1), and a temperature-sensitive cylinder (19a) arranged in the discharge side gas pipe (9b) of the compressor (1). a first pressure reducing mechanism (19) comprising an automatic expansion valve that reduces the pressure of the refrigerant flowing through the first bypass path (17); In the refrigeration system, the first bypass path (17
) a second bypass path (21) that allows the liquid refrigerant to bypass the economizer and the first pressure reducing mechanism (19) and flow to an intermediate pressure point of the compressor (1); and the second bypass path (21). A second pressure reducing mechanism (22) that reduces the pressure of the flowing refrigerant and a first bypass path (17 ) economizer side and second bypass path (21)
a detection means (26) for detecting that a command signal to increase the capacity of the compressor (1) is output to the compressor (1); When the output is received and a capacity increase command signal is output to the compressor (1), a part of the refrigerant in the main refrigerant circuit (10) is transferred to the second
After causing the refrigerant to flow to the bypass path (21) side and increasing the capacity of the compressor (1), a part of the refrigerant in the main refrigerant circuit (10) is caused to flow to the economizer side of the first bypass path (17). Control means (27) for controlling the switching means (23)
A refrigeration device with an economizer, characterized by being provided with. (2) The economizer-equipped refrigerator according to claim (1), wherein the first bypass path (17) is connected to the main refrigerant circuit (10) so that the liquid refrigerant supercooled by the economizer can be taken out. Device. (3) The economizer includes an inner pipe (12) that constitutes a part of the main refrigerant circuit (10), and an annular space (14) that is arranged around the inner pipe (12). ) has a double pipe structure with the outer pipe (13) forming a part of the first bypass path (17), and the refrigerant reduced in pressure by the first pressure reducing mechanism (19) and the liquid in the inner pipe (12) The refrigerating device with an economizer according to claim 1 or 2, characterized in that the refrigerating device is an intercooler (11) that exchanges heat with a refrigerant. (4) A compressor (1) whose operating capacity can be adjusted by an unloader mechanism (1a), a condenser (2), a main pressure reducing mechanism (3), and an evaporator (8) are successively connected by piping (9). A part of the refrigerant flowing from the main refrigerant circuit (10) and the condenser (2) of the main refrigerant circuit (10) to the main pressure reduction mechanism (3) is bypassed through the main pressure reduction mechanism (3) and the evaporator (8). The opening is adjusted by a bypass passage (17) that discharges the gas to an intermediate pressure point of the compressor (1), and a temperature-sensitive cylinder (19a) arranged in the discharge side gas pipe (9b) of the compressor (1). , the above bypass path (1
an automatic expansion valve (19) that reduces the pressure of the refrigerant flowing through the evaporator (8) and an automatic expansion valve (19) that reduces the pressure of the refrigerant flowing through the evaporator (8). A method for controlling the operation of a refrigeration system equipped with an economizer that increases the refrigeration capacity by cooling the compressor (1), when a command signal to increase the capacity of the compressor (1) is output to the compressor (1). A part of the liquid refrigerant in the main refrigerant circuit (10) bypasses the economizer and the expansion valve (19) and flows to the intermediate pressure point of the compressor (1) a predetermined time before the capacity is increased, and then, A method for controlling the operation of a refrigeration system with an economizer, the method comprising increasing the capacity of a compressor (1).