JPH0796973B2 - Refrigerating apparatus with economizer and operation control method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating device in which an economizer is arranged in a refrigerant circuit and an operation control method thereof, and more particularly to a device for controlling a discharge gas temperature of a compressor. Regarding

(Prior Art) Conventionally, for example, "Refrigeration and Air Conditioning Handbook, 4th Edition, Basic Edition" (May 30, 1981, published by the Japan Refrigeration Association)
As disclosed on page 382, there are known refrigeration systems with economizers that increase refrigeration capacity while controlling compressor and condenser capacities. This refrigeration system with an economizer has a refrigerant circuit in which a compressor, a condenser, a liquid receiver, a main pressure reducing valve, an evaporator and a droplet separator are sequentially connected by piping, and a liquid refrigerant from the liquid receiver is reduced in pressure by a pressure reducing valve. It has a bypass passage that bypasses the intermediate pressure of the compressor after it is decompressed and gasified by the intermediate cooler (economizer), and the refrigerant refrigerant in the intermediate cooler supercools the liquid refrigerant in the main refrigerant circuit. It is something that is done.

Further, in addition to this, in the above-mentioned document, after decompressing the liquid refrigerant with a liquid pipe, the gas refrigerant and the liquid refrigerant are separated by a receiver, and the gas refrigerant is bypassed to a location at an intermediate pressure of the compressor, and the low temperature There is also disclosed one provided with an economizer receiver in which only the liquid refrigerant is evaporated by the evaporator. And
With such an economizer cycle, the enthalpy change of the refrigeration cycle is increased more than when the economizer is not used, and the refrigeration effect can be increased.

(Problems to be solved by the invention) By the way, in the refrigerating apparatus having the economizer cycle, when an automatic expansion valve whose opening is controlled by a temperature-sensing cylinder arranged in the discharge pipe is used as the decompression mechanism of the bypass passage, The discharge gas temperature of the machine can be controlled.
That is, when the discharge gas temperature is high, the opening degree of the expansion valve is increased to reduce the degree of superheat to suppress the rise in the discharge gas temperature, while when the discharge gas temperature is low, the opening degree of the expansion valve is reduced to prevent overheating. By increasing the degree, it is possible to suppress a decrease in discharge gas temperature. However, in that case, for example, when the compressor with an unloader is loaded up, the discharge gas pressure immediately rises, but since the rise in the discharge gas temperature is not immediately detected by the temperature sensing cylinder, the temperature is temporarily low. High pressure occurs,
The automatic expansion valve operates in the direction of squeezing when it judges that the degree of superheat has become small, and as a result, the discharge gas temperature rises excessively, which may cause deterioration of the lubricating oil and impair the reliability of the compressor. .

The present invention has been made in view of such a point, and an object thereof is to stop the function of the economizer at the time of load-up of the compressor and to inject the refrigerant into the compressor, thereby discharging the compressor. It is intended to cool the gas temperature in advance and thus improve its reliability.

(Means for Solving the Problem) In order to achieve the above object, the solution means of the invention according to claim (1) is an economizer in which a part of the refrigerant in the main refrigerant circuit is at an intermediate pressure of the compressor. When bypassing the compressor, the refrigerant is allowed to bypass the economizer for a predetermined time before the compressor is loaded up, and the excessive effect of the refrigerant injection effect is prevented in advance. I am trying to do it.

Specifically, in the present invention, as shown in FIG. 1, a compressor (1), a condenser (2), a main depressurization mechanism (3) and an evaporator whose operating capacity can be adjusted by an unloader mechanism (1a). A main refrigerant circuit (10) in which (8) is sequentially connected by a pipe (9), 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). Main decompression mechanism (3)
And a first bypass passage (17) for bypassing the evaporator (8) and discharging to a location having an intermediate pressure of the compressor (1), and a discharge side gas pipe (9b) of the compressor (1). The opening is adjusted by the temperature sensing tube (19a), and the first bypass path (1
Based on the first pressure reducing mechanism (19) consisting of an automatic expansion valve for reducing the pressure of the refrigerant flowing through (7) and the refrigerant pressure reducing effect of the first pressure reducing mechanism (19), the evaporator (8) to the main pressure reducing mechanism (3 ) Is assumed to be a refrigerating apparatus provided with an economizer that supercools the liquid refrigerant flowing in the above) to increase the refrigerating capacity.

And a second bypass passage (21) for causing the liquid refrigerant in the first bypass passage (17) to bypass the economizer and the first depressurization mechanism (19) and to flow to a location at an intermediate pressure of the compressor (1), A second pressure reducing mechanism (22) for reducing the pressure of the refrigerant flowing through the second bypass passage (21), and a path for bypassing a part of the liquid refrigerant in the refrigerant circuit (10) to a location at an intermediate pressure of the compressor (1). And a switching means (23) for selectively switching between the economizer side of the first bypass path (17) and the second bypass path (21) side.

Further, a detecting means (26) for detecting that a command signal for increasing the capacity is output to the compressor (1), and an output of the detecting means (26) to receive a capacity increasing command to the compressor (1). When a signal is output, a part of the refrigerant in the main refrigerant circuit (10) is circulated to the second bypass passage (21) side a predetermined time before the capacity of the compressor (1) is increased, and the compressor (1 ), The control means (27) for controlling the switching means (23) so that a part of the refrigerant in the main refrigerant circuit (10) is circulated to the economizer side of the first bypass passage (17). It is characterized by having and.

In the invention according to claim (2), as shown in FIG. 4, the first bypass passage (17) is connected to the main refrigerant circuit (10) 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 is an inner pipe (12) forming a part of the main refrigerant circuit (10), and the inner pipe (12). An annular space (14) is formed around the first annular passage (14), and the annular space (14) has a double pipe structure with an outer pipe (13) forming a part of the first bypass passage (17), and The intercooler (11) is configured to exchange heat between the refrigerant decompressed by the decompression mechanism (19) and the liquid refrigerant in the inner pipe (12).

In the invention according to claim (4), as an operation control method of the refrigerating apparatus with the economizer, when a command signal for increasing the capacity is output to the compressor (1), the refrigerating apparatus having the above configuration is output. , A predetermined time before the capacity of the compressor (1) is increased, a part of the liquid refrigerant is circulated in the main refrigerant circuit (10) by bypassing the economizer to an intermediate pressure position of the compressor (1), and then, , The capacity of the compressor (1) is increased.

(Operation) With the above configuration, in the invention according to claim (1), when a command signal for increasing the capacity is output to the compressor (1) at the time of load-up of the compressor (1), this may occur. The switching means (23) is controlled by the control means (27) which is detected by the detection means (26) and receives the output of this detection means (26),
First, a part of the refrigerant from the condenser (2) of the main refrigerant circuit (10) to the main pressure reducing mechanism (3) is circulated to the second bypass passage (21) side. Next, when a predetermined time has elapsed, the capacity of the compressor (1) is adjusted to be increased, and then a part of the refrigerant in the main refrigerant circuit (10) is circulated to the economizer side of the first bypass passage (17). . Therefore, when the compressor (1) is loaded up, even if the opening of the automatic expansion valve is temporarily reduced due to the detection delay of the temperature sensing cylinder (19a) of the first pressure reducing mechanism (19), the compressor (1 ), The mixed refrigerant of liquid and gas that does not pass through the economizer is discharged for a certain period of time to the place where the intermediate pressure of the compressor (1) is reached, and the injection gas temperature is caused by the injection effect. Is prevented from rising excessively.

In the invention according to claim (2), 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 that the subcooled liquid refrigerant always flows through the first bypass passage (17). The liquid coolant for injection is secured by the coolant. This eliminates the need for a liquid reservoir such as a receiver, thereby simplifying the circuit configuration and downsizing the refrigeration system.

In the invention according to claim (3), the economizer is composed of an intercooler (11) including an inner pipe (12) and an outer pipe (13), and an annular space () between both pipes (12) and (13) ( The refrigerant decompressed by the first decompression mechanism (19) flows through 14) and the liquid refrigerant in the inner pipe (12) is supercooled by this refrigerant, so that the effect as an economizer can be excellently exhibited.

In the invention according to claim (4), when the command signal for increasing the capacity is output to the compressor (1) during load-up of the compressor (1), first, the refrigerant in the main refrigerant circuit (10) is discharged. A part of it bypasses the economizer and is distributed to the compressor (1).
Next, when a predetermined time elapses, the capacity of the compressor (1) is increased and adjusted. Therefore, like the invention according to claim (1), even if the opening degree of the automatic expansion valve (19) is temporarily reduced due to the detection delay of the temperature sensing cylinder (19a),
The liquid / gas mixed refrigerant that does not pass through the economizer is discharged to a location having an intermediate pressure of the compressor (1) to prevent the discharge gas temperature from excessively rising.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows the overall structure of a refrigerating apparatus (A) for a cold water economizer according to an embodiment of the present invention. (1) is a compressor of turbo type, screw type, scroll type, etc., and (1a) is suction vane control. The operating capacity of the compressor (1)
It is an unloader mechanism that adjusts to 5 steps of 100%, 75%, 50%, 25% and 0%. (2) is a condenser, and (3) is an external pressure equalizing type automatic expansion valve for an evaporator as a main pressure reducing mechanism. (4) is a water cooler for cooling water,
This water cooler (4) is provided with a closed shell (7) having a water inlet (5) at the bottom and a water outlet (6) at the top, and a heat-exchangeable arrangement in the shell (7). It is composed of an evaporator (8) including a heat transfer tube provided. The compressor (1), the condenser (2), the expansion valve (3) and the evaporator (8) (heat transfer tube) are sequentially arranged by a pipe (9) including a liquid pipe (9a) and a gas pipe (9b). It is connected so that the refrigerant can circulate, and the cold heat taken by the condenser (2) is evaporated (8).
The main refrigerant circuit (10) is configured so as to cool the water in the water cooler (4) by moving the main refrigerant circuit (10). (3a) is a temperature-sensing cylinder provided in the outlet side gas pipe (9b) of the evaporator (8), and controls the opening of the automatic expansion valve (3).

An intermediate cooler (11) as an economizer for increasing the refrigerating capacity is provided in the liquid pipe (9a) of the main refrigerant circuit (10).
Is provided. This intercooler (11) has an inner tube (1
2) and a double tube consisting of an outer tube (13) arranged concentrically with a closed annular space (14) around the inner tube (12) inside the main refrigerant circuit (10) Is part of the. Further, the end of the annular space (14) between the inner pipe (12) and the outer pipe (13) on the side of the condenser (2) is between the intercooler (11) and the condenser (2). Through the pipe (15) to the liquid pipe (9a) of
The end on the side of the expansion valve (3) is connected to the intermediate pressure part of the compressor (1) via a pipe (16),
Due to the annular spaces (14) of the two pipes (15) and (16) or the intercooler (11), part of the refrigerant flowing from the condenser (2) to the automatic expansion valve (3) is expanded to the expansion valve (3) and A first bypass passage (17) is configured so that the evaporator (8) is bypassed and discharged to a location having an intermediate pressure of the compressor (1).

A cooler automatic expansion valve (19) as a first pressure reducing mechanism for reducing the pressure of the refrigerant flowing through the first bypass passage (17) is provided in the middle of the pipe (15). (19a) is a compressor (1)
The opening of the expansion valve (19) is controlled by a temperature sensitive tube provided in the gas pipe (9b) on the discharge side. Then, the liquid refrigerant flowing through the liquid pipe (9a) of the main refrigerant circuit (10) is cooled by the intercooler (11) to be in a supercooled state, and a part of the supercooled liquid refrigerant is piped (15). ) And reduce the pressure by the automatic expansion valve (19), and after the pressure-reduced refrigerant is heat-exchanged with the liquid refrigerant in the inner pipe (12) in the annular space (14) of the intercooler (11), The compressor (1) is designed to discharge to a portion having an intermediate pressure.

In addition, the branch from the liquid pipe (9a) and the intercooler (11)
The one end of the pipe (20) is connected to the pipe (15) that constitutes the first bypass passage (17) between the pipe (20) and the intermediate cooler (11) and the compressor (1). Plumbing to and from (16)
It is connected to the (first bypass passage (17)), and the liquid refrigerant in the first bypass passage (17) is compressed by this pipe (20) by bypassing the intercooler (11) and the expansion valve (19). A second bypass passage (21) is provided to circulate the intermediate pressure in the machine (1). Further, in the middle of the pipe (20), a second refrigerant for depressurizing the refrigerant flowing through the second bypass passage (21) is provided.
A capillary tube (22) as a pressure reducing mechanism is arranged.

Furthermore, a path for bypassing a part of the refrigerant in the liquid pipe (9a) of the main refrigerant circuit (10) to a location having an intermediate pressure of the compressor (1) is an intercooler (11) of the first bypass path (17). ) Side and the second bypass path (21) side is provided with a switching mechanism (23) for selectively switching. This switching mechanism (23) has a second
The first solenoid valve (SV ₁ ) arranged in the pipe (15) between the connection to the bypass passage (21) and the expansion valve (19), and the pipe (2
0) and a second solenoid valve (SV ₂ ), the first solenoid valve (SV ₁ ) is switched to the fully open state at the same time when the compressor (1) is started. Then, by controlling the opening and closing of the second solenoid valve (SV ₂ ) with respect to the fully opened first solenoid valve (SV ₁ ), the selection of the first or second bypass passages (17), (21) is switched, When the second solenoid valve (SV ₂ ) is closed, a path for bypassing a part of the refrigerant in the main refrigerant circuit (10) to a location at an intermediate pressure of the compressor (1) is formed in the middle of the first bypass path (17). On the other hand, when the second solenoid valve (SV ₂ ) is opened, the same bypass path is used as the second bypass path (21).
Try to be on the side.

The solenoid valves (SV ₁ ) and (SV ₂ ) of the unloader mechanism (1a) and the switching mechanism (23) of the compressor (1) are configured to be operated and controlled by the control device (24). A measurement signal of a water temperature sensor (25) for detecting the water temperature in the water cooler (4) is input to the control device (24). The control means in the control device (24) will be described with reference to the flowchart of FIG. 3. During operation of the compressor (1) operating at, for example, 50% capacity, first, in step S ₁ , the water cooler (4) It is determined whether or not the water temperature inside is higher than the target temperature and a load-up command signal for operating the compressor (1) at a capacity of 75% has been output. If this determination is NO, the same step S ₁ is repeated. . On the other hand, if the decision is made to YES, the process proceeds to step S _2, after opening the second solenoid valve (SV _2), whether the first set time t ₁ (e.g. 10 seconds) has elapsed in step S ₃ determines The same step S until the judgment becomes YES.
Repeat ₃ . When the set time t ₁ elapses, the determination is Y
When it comes to ES, the unloader mechanism (1a) in step S ₄
The compressor (1) is stepped up by one step to bring the operating capacity to 75%. After that, the process proceeds to step S _5, and it is determined whether or not the second set time t ₂ (for example, 1 minute longer than the time when the detection state of the temperature sensing tube (19) is reversed) has elapsed, and the determination is made. Repeat step S ₅ until YES. And
If the determination is YES after the elapse of the predetermined time t ₂ , step S
After completely closing the second solenoid valve SV ₂ ) in ₆ , the procedure returns to the first step S ₁ .

That is, in this embodiment, step S _{1 of the} above flow is
Thus, the detection means (26) for detecting that the command signal for increasing the operating capacity of the compressor (1) is output to the unloader mechanism (1a) of the compressor (1) is configured.

The predetermined by the step S ₂ to S _6, receiving the output of said detecting means (26), when the capacity increase command signal to the compressor (1) is output, increasing the capacity of the compressor (1) time
Before t _1, a part of the refrigerant in the main refrigerant circuit (10) is circulated to the second bypass passage (21) side to increase the capacity of the compressor (1), and then for a predetermined time t ₂ , the main refrigerant is Control means (27) for controlling the switching mechanism (23) so that a part of the refrigerant of the circuit (10) is circulated to the intercooler (11) side of the first bypass passage (17).
Is configured.

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

With the start of the compressor (1), the first solenoid valve (SV ₁ ) is opened and the second solenoid valve (SV ₂ ) is closed. At this time, the high-pressure gas refrigerant discharged from the compressor (1) of the main refrigerant circuit (10) is liquefied in the condenser (2) and then cooled in the inner pipe (12) of the intercooler (11). It becomes a supercooled state.
This liquid refrigerant is decompressed by the expansion valve (3) for the condenser,
The water in the water cooler (4) is evaporated by the evaporator (8), and the heat of evaporation cools the water in the water cooler (4). Evaporator (8)
The gas refrigerant evaporated in step 1 is favored by the compressor (1) and recompressed. Then, the refrigerating capacity of the refrigerating apparatus (A) is increased by the good cooling of the liquid refrigerant in the intermediate cooler (11).

Further, a part of the liquid refrigerant flowing from the condenser (2) to the condenser expansion valve (3) flows to the first bypass passage (17), and the refrigerant is decompressed by the cooler expansion valve (19), It passes through the annular space (14) of the intermediate cooler (11), where the liquid refrigerant in the main refrigerant circuit (10) is cooled well. The refrigerant that has passed through the intermediate cooling (11) is discharged to a location having an intermediate pressure of the compressor (1). The opening of the expansion valve (19) for the cooler is controlled by the temperature sensing tube (19a) on the discharge side of the compressor (1), and the temperature of the discharge gas of the compressor (1) is controlled to a constant temperature by this control. To be done.

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) causes the unloader mechanism ( A load-up command signal is output to 1a). And by the output of this load-up command signal,
First, the second solenoid valve (SV ₂ ) has the first set time t ₁ (10 seconds)
Open for a while. By opening the second solenoid valve (SV ₂ ), a part of the refrigerant flowing from the condenser (2) to the condenser expansion valve (3) passes through the second bypass passage (21) to the intercooler (11). It bypasses and flows to the place where it becomes an intermediate pressure of the compressor (1). When the set time t ₁ has elapsed, an actual load-up signal is output to the unloader mechanism (1a), and the operating capacity of the compressor (1) increases. After this load-up, when the second set time t ₂ (1 minute) elapses and the operating state of the compressor (1) stabilizes, the second solenoid valve (SV ₂ ) closes to its original state.

Therefore, in this embodiment, when the compressor (1) is loaded, even when the opening degree of the cooler expansion valve (19) is temporarily reduced due to the detection delay of the temperature sensing cylinder (19a),
A certain period of time before the compressor (1) is loaded up
Only for t ₁ , the mixed refrigerant of liquid and gas that does not pass through the intercooler (11) is discharged to the place where the intermediate pressure of the compressor (1) is reached, and the injection effect causes the discharge gas temperature to rise excessively. This can be prevented in advance, and the reliability of the compressor (1) can be improved.

FIG. 4 shows the essential parts of another embodiment of the present invention. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, the first bypass passage (17 ') is provided to the main refrigerant circuit (10) so as to take out the liquid refrigerant supercooled by the intercooler (11) and the automatic expansion valve. It is connected to the liquid pipe (9a) between (3). Therefore,
In this case, the subcooled liquid refrigerant always flows through the first bypass passage (17 '), and the liquid refrigerant for injection is secured by this liquid refrigerant. For this reason, a liquid reservoir such as a receiver for storing the injection refrigerant is not necessary, and by omitting the liquid reservoir, the circuit configuration of the refrigerating apparatus (A) is simplified and the refrigerating apparatus (A) is downsized, and liquid injection is performed. Thus, the discharge gas temperature can be stably controlled, and the durability and reliability of the compressor (1) can be improved.

Further, in the main refrigerant circuit (10), since the liquid refrigerant supercooled by the intercooler (11) is used as the liquid refrigerant for injection, the cooling effect by the injection of this supercooled liquid refrigerant becomes large, Therefore, the amount of the injection liquid refrigerant can be relatively small. Therefore, the amount of refrigerant decompressed by the cooler automatic expansion valve (19) also decreases, and the expansion valve (19) can be downsized by the smaller amount of the refrigerant, thereby reducing the cost and expanding the expansion valve (19). ) Durability and reliability can be improved.

(Effects of the Invention) As described above, according to the inventions of claims (1) and (4), a part of the refrigerant from the condenser of the main refrigerant circuit to the main pressure reducing mechanism becomes the intermediate pressure of the compressor. Bypass to a location, decompress the refrigerant with an automatic expansion valve in the middle, evaporate it with an economizer, then supercool the refrigerant in the main refrigerant circuit with this economizer. At this time, the refrigerant bypasses the expansion valve and the economizer for a predetermined time before executing the load-up, so that the opening of the automatic expansion valve is temporarily stopped due to the detection delay of the temperature sensing tube that detects the discharge gas temperature. Even if it becomes extremely small, it is possible to obtain the 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 place where it becomes the intermediate pressure of the compressor. In this case, it is possible to prevent the temperature of the discharge gas from excessively rising and improve the reliability of the compressor.

According to the invention of claim (2), the bypass path is
Since it was connected to the main refrigerant circuit so as to take out the supercooled liquid refrigerant by the economizer, the supercooled liquid refrigerant can always be made to flow to the bypass passage to secure the injection liquid refrigerant, thus simplifying the circuit configuration and refrigeration equipment. Can be miniaturized.

According to the invention of claim (3), the economizer is composed of 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 decompressed by an expansion valve to Since I tried to supercool the liquid refrigerant in the pipe,
The effect as an economizer can be exhibited well.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of the present invention. FIG. 2 and the following drawings show an embodiment of the present invention, FIG. 2 is a refrigerant piping system diagram showing the overall configuration of a refrigerating apparatus, and FIG. 3 is a flow chart diagram showing a control means. FIG. 4 is a view corresponding to FIG. 2 showing another embodiment. (A), (A ') ... Refrigerator (1) ... Compressor (1a) ... Unloader mechanism (2) ... Condenser (3) ... Expansion valve (main decompression mechanism) (8) ... Evaporator (9) …… Pipe (9b) …… Gas pipe (10) …… Main refrigerant circuit (11) …… Intercooler (economizer) (12) …… Inner pipe (13) …… Outer pipe (14) ) …… Annular space (17), (17 ′) …… First bypass passage (19) …… Expansion valve (first depressurization mechanism) (19a) …… Temperature tube (21) …… Second bypass passage ( 22) …… Capillary tube (second pressure reducing mechanism) (23) …… Switching mechanism (switching means) (24) …… Control device (26) …… Detecting means (27) …… Controlling means

Claims (4)

[Claims] 1. A compressor (1) whose operating capacity can be adjusted by an unloader mechanism (1a), a condenser (2), a main decompression mechanism (3) and an evaporator (8) are sequentially connected by a pipe (9). A 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 main pressure reducing mechanism (3) and the evaporator (8). First bypass passage (17) for bypassing the gas and discharging it to an intermediate pressure location of the compressor (1), and a temperature sensing tube (19a) arranged in the discharge side gas pipe (9b) of the compressor (1) The opening is adjusted by the
The first pressure reducing mechanism (19) consisting of an automatic expansion valve for reducing the pressure of the refrigerant flowing through (7), and the pressure reducing effect of the refrigerant by the first pressure reducing mechanism (19), from the evaporator (8) to the main pressure reducing mechanism (3). In the refrigerating device provided with an economizer that supercools the liquid refrigerant flowing in the above) to increase the refrigerating capacity, the liquid refrigeration of the first bypass passage (17) is compressed by bypassing the economizer and the first pressure reducing mechanism (19). A second bypass passage (21) that circulates to a location that has an intermediate pressure of the machine (1), and a second that reduces the pressure of the refrigerant that flows through the second bypass passage (21).
The depressurization mechanism (22) and a path for bypassing a part of the liquid refrigerant of the main refrigerant circuit (10) to a location at an intermediate pressure of the compressor (1) are provided on the economizer side of the first bypass path (17) and on the second side. Switching means (23) for selectively switching to the bypass path (21) side, detection means (26) for detecting that a command signal for increasing the capacity has been output to the compressor (1), and the detection means When the capacity increase command signal is output to the compressor (1) in response to the output of the means (26), one of the refrigerant in the main refrigerant circuit (10) is supplied a predetermined time before the capacity of the compressor (1) is increased. Part to the second bypass passage (21) side, and the compressor (1)
The control means (27) for controlling the switching means (23) so that a part of the refrigerant in the main refrigerant circuit (10) is circulated to the economizer side of the first bypass passage (17) after the capacity of the main refrigerant circuit (10) is increased. A refrigeration system with an economizer characterized by being provided with. 2. A main refrigerant circuit (10) for allowing the first bypass passage (17) to take out liquid refrigerant supercooled by an economizer.
The refrigeration system with an economizer according to claim 1, characterized in that the refrigeration system is connected to. 3. The economizer is arranged with an inner pipe (12) forming a part of a main refrigerant circuit (10) and an annular space (14) around the inner pipe (12). (14) has a double pipe structure with the outer pipe (13) forming a part of the first bypass passage (17), and the refrigerant reduced in pressure by the first pressure reducing mechanism (19) and the inner pipe (12) Intercooler (11) for exchanging heat with other liquid refrigerant
The refrigeration apparatus with an economizer according to Claim (1) or (2), characterized in that 4. A compressor (1), a condenser (2), a main depressurization mechanism (3) and an evaporator (8) are sequentially connected by a pipe (9) so that the operating capacity can be adjusted by an unloader mechanism (1a). And a part of the refrigerant flowing from the condenser (2) of the main refrigerant circuit (10) to the main decompression mechanism (3) in the main decompression mechanism (3) and the evaporator (8). The bypass passage (17) for bypassing and discharging to a place where the pressure becomes the intermediate pressure of the compressor (1), and the temperature sensing cylinder (19a) arranged in the discharge side gas pipe (9b) of the compressor (1) Based on the automatic expansion valve (19) that is adjusted and reduces the pressure of the refrigerant flowing through the bypass passage (17), and the pressure reducing effect of the refrigerant by the automatic expansion valve (19),
A method for controlling the operation of a refrigerating apparatus, comprising: an economizer for supercooling a liquid refrigerant flowing from the evaporator (8) to the main pressure reducing mechanism (3) to increase refrigerating capacity, wherein the compressor (1) has a capacity When a command signal for increasing the capacity is output, a part of the liquid refrigerant in the main refrigerant circuit (10) bypasses the economizer and the expansion valve (19) a predetermined time before the capacity of the compressor (1) is increased. Then, the operation control method of the refrigerating apparatus with an economizer is characterized in that the compressor (1) is circulated to a location having an intermediate pressure and then the capacity of the compressor (1) is increased.