JPH01244247A - Refrigerating plant - Google Patents

Abstract

PURPOSE:To improve the environmental comport by reducing the rate of drop in the air conditioning capacity, etc. by using both the cooling effect by bypassing the liquid cooling medium to the compressor and reducing the compressor capacity when the compressor tends to overheat. CONSTITUTION:When the compressor 1 tends to overheat, the response compressor capacity to match the load on the side of the usage side heat exchangers 20, 27 is changed to a lower compressor capacity, and, at the same time, part of the liquid cooling medium flowing in the liquid pipe 14 is bypassed to the suction side of the compressor 1. That is, a small quantity of liquid cooling medium is fed to the compressor 1 to be evaporated therein, and the heat of evaporation provides a cooling effect on the compressor 1. As a relatively higher cooling effect can be obtained without causing a drop in the compressor capacity by selecting a small quantity of the bypass flow which is not liable to cause a liquid compression, the drop in the compressor capacity can be reduced by an equivalent amount of afore-said cooling effect. Therefore, the rate of drop in the air conditioning capacity, etc. can be reduced, and so the environmental comfort can be improved than before.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigeration system having a compressor with variable compression capacity and an overload prevention function.

(Prior Art) As a conventional example of the above-mentioned refrigeration apparatus, there can be mentioned, for example, an air conditioner described in Japanese Patent Application Laid-open No. 159052/1983. In this equipment, a compressor with a variable rotation speed using an inverter is installed, and the temperature of the refrigerant discharged from this compressor is detected, and when the detected temperature exceeds a reference temperature, the difference between the detected temperature and the reference temperature is detected. In response to this, a predetermined reduction frequency is input to the Hokki inverter to lower the rotational speed of the compressor, thereby lowering the temperature of the discharged refrigerant. The refrigerant flowing through the compressor also has the effect of cooling the motor coil etc. disposed within the compressor, so the temperature of the refrigerant discharged from the compressor must be controlled to be below the allowable upper limit temperature. By,
The operation is continued at vE while preventing overheating of the motor coil.

(Problem to be solved by the invention) By the way, when the compressor tends to overheat as described above, the frequency corresponding to the air conditioning load on the indoor heat exchanger side is lowered, and the compression of the compressor is reduced. When changing to an operation that lowers the capacity, the air conditioning capacity decreases, for example, in heating operation, the temperature blown out from the indoor unit decreases, and the comfort of the air conditioner deteriorates significantly. There is.

This invention has been made in view of the above, and an object of the invention is to provide a refrigeration system that can prevent overheating of a compressor and improve air conditioning comfort.

(Means for Solving the Problems) Therefore, as shown in FIG. 1, the refrigeration system according to the first aspect of the present invention includes a compressor 1 having variable compression capacity, a heat source side heat exchanger 11, and a user side heat exchanger 11. An on-off valve 42 is interposed between the liquid pipe I4, which connects the exchanger 20.27 so that refrigerant can be circulated, and the suction side of the compressor 1, which connects the heat exchangers 11, 20, and 27 with each other. By connecting the injection pipe 40 and opening the on-off valve 42, the liquid pipe 14 is opened.
A part of the liquid refrigerant flowing through the injection pipe 40
load response control means 62 configured to bypass the compressor 1 to the suction side through the compressor 1, and to operate the compressor 1 with a response compression capacity according to the load of the utilization side heat exchanger 20.27; A regulated operation control means 65 for operating the compressor 1 at a compression capacity lower than the response compression capacity, and a temperature detection means 43 for detecting the temperature of the gas refrigerant discharged from the compressor 1 are provided, and the detected temperature Discharge temperature monitoring and control means 64 is provided for reducing the detected temperature by opening the on-off valve 42 and switching to operation by the regulated operation control means 65 when the temperature exceeds the first reference temperature. .

Further, in the refrigeration apparatus according to the second claim, in the apparatus according to the first claim, the opening/closing valve 42 is opened when the temperature detected by the temperature detecting means 43 exceeds the first reference temperature, and When the second reference temperature, which is higher than the first reference temperature, is exceeded, the operation is switched to the regulated operation control means 65, and when the detected temperature drops to the return temperature, the on-off valve 42 is closed and the load response is controlled. Control means 62
The discharge temperature monitoring control means 64 performs control to return to operation according to the above.

Further, in the refrigeration system according to the third claim, in the apparatus according to the second claim, when the temperature detected by the temperature detecting means 43 exceeds the second reference temperature, the compression capacity of the compressor 1 is adjusted at that time. The regulated operation control means 65 performs control to gradually reduce the compression capacity at a predetermined reduction speed.

(Function) In the refrigeration system according to the first aspect, when the compressor l tends to overheat, the user side heat exchanger 20.
In addition to switching from the response compression capacity according to the load on the 27 side to a lower compression capacity, an operation of bypassing a part of the liquid refrigerant flowing through the liquid pipe 14 to the suction side of the compressor 1 is also used. That is, by sucking a small amount of liquid refrigerant into the compressor 1 and evaporating it inside the compressor 1, the heat of evaporation at that time provides a cooling effect to the compressor 1.

Therefore, by setting a small bypass flow rate that does not cause liquid compression, a relatively large cooling effect can be obtained with almost no reduction in compression capacity, and the amount of reduction in compression capacity is due to this cooling effect. Since it is possible to reduce the
It becomes possible to improve comfort more than before.

In addition, in the refrigeration system according to the second aspect, when the compressor l tends to overheat, a cooling operation is first performed by bypassing the liquid refrigerant, and then when this operation alone causes a further temperature rise, Since the compression capacity will be reduced, for example, if the compressor 1 has a tendency to overheat with a small abnormal calorific value, it is possible to eliminate the tendency to overheat only by the cooling operation by bypassing the liquid refrigerant. As a result, comfort can be further improved by reducing the frequency of compression capacity reduction operations accompanied by a decrease in air conditioning capacity, etc.

Furthermore, in the refrigeration system according to the third aspect, by having a configuration in which the compression capacity reduction operation is gradually reduced, the air conditioning capacity etc. do not drop suddenly, and for example, the said gradual reduction operation is performed while monitoring the discharge temperature. By doing this and stopping the gradual reduction operation described above when the discharge temperature reaches the return temperature, the air conditioning capacity etc. will not decrease excessively.
This also makes it possible to improve comfort.

(Example) Next, a specific example of the refrigeration apparatus of the present invention will be described in detail with reference to the drawings.

First, FIG. 2 shows a refrigerant circuit diagram of a refrigeration apparatus according to an embodiment of the present invention configured as a heat pump system having a hot water heating function as well as an air conditioning function for four rooms.

In the figure, X is an outdoor unit, and this outdoor unit X includes four indoor units A-D and a hot water supply unit Y.
are connected by refrigerant piping.

The outdoor unit X has a compressor 1, and a discharge pipe 2 and a suction pipe 3 of the compressor 1 are each connected to a four-way switching valve 4. The compressor l has an inverter 5 for controlling its rotational speed, that is, its compression capacity, and a first solenoid valve 6 is provided in the discharge pipe 2.
However, an accumulator 7 is interposed in each of the suction pipes 3. A first gas pipe 8 and a second gas pipe 9 are connected to the four-way switching valve 4.
is connected to an outdoor heat exchanger (heat source side heat exchanger) 11 equipped with an outdoor fan 10, and the second gas pipe 9 is connected to
A first gas shutoff valve 13 is connected to the header 12 and interposed therebetween. A liquid pipe 14 is further connected to the outdoor heat exchanger 11, and this liquid pipe 14 includes:
Dryer filter 15 sequentially from the outdoor heat exchanger 11 side
, the first electric expansion valve 16 , the liquid receiver 17 , and the first liquid closing valve 18
is interposed. Between the tip of the liquid pipe 14 and the header 12, a plurality of (four in the figure) branch refrigerant pipes 19...19 are connected in parallel to each other, and these branch refrigerant pipes 19...19 Indoor heat exchangers 20, . . . 20 (only one unit is shown) and second electric expansion valves 21, . Note that each of the indoor units A to D is illustrated for only one indoor unit A, but each indoor heat exchanger 20 and indoor fan 22 are
It is composed of.

On the other hand, a hot water supply gas pipe 25 is connected to the discharge pipe 2 of the compressor 1, and a hot water supply liquid pipe 26 is connected to the liquid receiver 17 interposed in the liquid pipe 14. 25 and the hot water supply liquid pipe 26, each of the above-mentioned indoor heat exchangers 2
Hot water unit I used as a user-side heat exchanger together with 0
-Y hot water supply heat exchanger 27 is connected. The hot water supply heat exchanger 27 is disposed on the bottom side of the hot water storage tank 28, and is configured to heat the hot water in the hot water storage tank 28 by the heat of condensation of the refrigerant condensed in the hot water supply heat exchanger 27. ing. Note that a second electromagnetic valve 29 and a second gas shutoff valve 30 are sequentially provided in the hot water supply gas pipe 25.
Further, a second liquid closing valve 31 is interposed in the hot water supply liquid pipe 26, and a capillary tube 32 and a check valve 33, a capillary tube 34 and a third electromagnetic valve 35 are also provided.
A series-parallel circuit consisting of is interposed. During hot water heating operation, which will be described later, the check valve 33 side becomes a refrigerant flow path,
On the other hand, when performing a defrost operation to remove frost adhering to the outdoor heat exchanger 11 by utilizing the hot water in the hot water storage tank 28, the third solenoid valve 35 is opened and the refrigerant is introduced through the capillary tube 34. We are planning to distribute it.

Further, in the above device, the liquid receiver 17 provided in the liquid pipe 14 and the suction pipe 3 of the compressor 1 are connected by two bypass pipes. One of them is a superheat degree detection piping 39 in which a capillary tube 38 is interposed, which detects the temperature of the refrigerant that has evaporated while flowing through the capillary tube 38 as a saturation temperature corresponding to the evaporation pressure, and combines this detected temperature with the suction gas The degree of superheating is determined by the difference in temperature.

The other pipe is an injection pipe 40 provided to prevent the compressor 1 from overheating.
0 is provided with a capillary tube 41 and an electromagnetic on-off valve 42 for injection control (hereinafter referred to as a bypass valve). Further, a discharge temperature sensor (temperature detection means) 43 consisting of a thermistor for detecting the temperature of discharge gas is attached to the discharge pipe 2 of the compressor 1.
By controlling the opening and closing of the bypass valve 42 based on the temperature detected in step 3, a bypass flow is controlled in which a part of the liquid refrigerant from the liquid pipe 14 is directly returned to the suction side of the compressor l through the injection pipe 40. The details will be explained later.

In the above device, as will be described later, indoor air conditioning operation is performed by circulating refrigerant between the outdoor heat exchanger 11 and the indoor heat exchanger 20, and at this time, the hot water supply heat exchanger 27 is operated with no refrigerant flowing. When the outdoor heat exchanger 11 and the hot water supply heat exchanger 27 are in a hibernation state, and during a hot water heating operation using the hot water supply heat exchanger 27, the indoor heat exchanger 20 and the indoor heat exchanger 2
During simultaneous cooling and hot water/heating operation using the hot water supply heat exchanger 27 and the hot water supply heat exchanger 27, the outdoor heat exchangers 11 are each put into a dormant state. Each is provided with piping that communicates with the suction side of the compressor 1 when the compressor is at rest. That is, the first gas pipe 8, the second gas pipe 9, and the hot water supply gas pipe 25 are connected to the liquid accumulation prevention pipe 4 in which the solenoid valves 44, 46, and 48 are interposed, respectively.
5.47.49 is connected to the suction pipe 3 of the compressor 1.

In the refrigeration system having the above configuration, refrigerant circulation control during heating and air conditioning operation will be described next. This driving is the 1st i! The solenoid valve 6 is opened, the second solenoid valve 39 is closed, and the refrigerant discharged from the compressor 1 is condensed in each indoor heat exchanger 20 via the four-way switching valve 4 and the second gas pipe 9, and then the liquid is It is evaporated in the outdoor heat exchanger 11 via the pipe 14, and then the first gas pipe 8,
This is done by returning the flow from the four-way switching valve 4 to the compressor 1.

In this case, the degree of superheating of the evaporative refrigerant is controlled by the first electric expansion valve 16.
The second electric expansion valves 21...21 control the amount of refrigerant distributed to each indoor heat exchanger 20...20.

On the other hand, cooling operation is performed by switching the four-way switching valve 4 from the above to circulate the refrigerant discharged from the compressor 1 from the outdoor heat exchanger 11 to each indoor heat exchanger 20. At this time, the first electric expansion valve 16 is fully opened, and each second electric expansion valve 2
1...21 controls the degree of superheating of the refrigerant.

Next, in the hot water heating operation, the first solenoid valve 6 is closed, and the second solenoid valve 3 is closed.
9 is opened and the compressor 1 is operated. Then, the refrigerant passes through the hot water supply gas pipe 25 and condenses in the hot water supply heat exchanger 27, then passes through the hot water supply liquid pipe 26 and the liquid pipe 14, and evaporates in the outdoor heat exchanger 11. The flow returns to the compressor [1] through the first gas pipe 8 and the four-way switching valve 4. In this case, each of the second electric expansion valves 21 . . . 21 is fully closed, and the first electric expansion valve 16 controls the degree of superheating of the evaporative refrigerant.

For simultaneous operation of heating and hot water supply, both the first and second solenoid valves 6.29 are opened, the refrigerant is condensed in both the indoor heat exchanger 20 and the hot water supply heat exchanger 27, and outdoor heat exchange is performed. Vessel 11
This can be done by circulating a refrigerant that is evaporated at a temperature.

In addition, in the above, simultaneous operation of cooling and hot water heating, that is, operation of heating hot water in the hot water storage tank 28 using exhaust heat from the air conditioner, is performed by closing the first solenoid valve 6, opening the second solenoid valve 29, and opening the first solenoid valve 29. This is done with the expansion valve 16 fully closed. Then, the refrigerant passes through the hot water supply gas pipe 25, condenses in the hot water supply heat exchanger 27, passes through the hot water supply liquid pipe 26, the liquid receiver 17, and the liquid pipe 14, and then enters each indoor heat exchanger 20...20. After that, it is returned to the compressor 1 via the second gas pipe 9 and the four-way switching valve 4. In this case, the degree of superheating of the evaporative refrigerant is controlled in each of the second electric expansion valves 21...21.

Next, operation control in each of the above-mentioned operation modes will be explained based on the control system flowchart shown in FIG. As shown in the figure, in the above device, an outdoor control device 51 is installed in the outdoor unit Each of the indoor control devices W52 includes a heating/cooling switch (not shown), an operation switch 54, a temperature setting switch 55 for setting the desired air conditioning temperature, and a temperature setting switch 55 for detecting the room temperature. A room temperature sensor 56 is connected thereto. Each indoor control device 52 outputs an operation request signal to the outdoor control device 51 when the operation switch 54 is ON and the temperature detected by the room temperature sensor 56 has not reached the set temperature. At the same time, a temperature difference signal between the set temperature and the detected temperature is output. Similarly, an operation switch 57, a hot water temperature setting switch 58, and a hot water temperature sensor 59 that detects the temperature of hot water in the hot water storage tank 28 are connected to the hot water supply control device 53.
is ON and the detected hot water temperature has not reached the set hot water temperature, an operation request signal and a temperature difference signal between the set hot water temperature and the detected hot water temperature are output from the hot water supply control device 53 to the outdoor control device 51. be done.

On the other hand, the outdoor control device 51 specifies the operation mode to be operated in response to the operation request signals from among the operation modes described above, and switches the respective valves to set the refrigerant circulation path in that operation. It has a valve control unit (not shown) that performs control, and also has a valve control unit (not shown) that operates the compressor l at a compression capacity corresponding to load fluctuations in the user-side heat exchanger during operation, that is, at an inverter frequency. As shown, a load capacity grasping section 61, a frequency control section (load response control means) 62, and a storage section 63 are provided. In the load capacity grasping section 61,
The total value of the rated load capacities of the units with the above-mentioned operation request among the indoor units A to D and the hot water supply unit Y is determined. On the other hand, initial setting frequencies corresponding to various combinations of total load capacity and temperature difference are stored in advance in the storage section 63 as a data table. Therefore, the initial setting frequency according to the total load capacity determined by the load capacity grasping section 61 and the temperature difference signal at that time is determined by the frequency control section 61.
2, and this frequency signal is read out from the storage unit 63 at
is output to the compressor 1 via the compressor 1, and the operation of the compressor 1 is started. After the rotation speed of the compressor 1 reaches the rotation speed corresponding to the initial setting frequency, the frequency control section 62 performs
For example, the frequency according to load changes by PID control,
That is, a load response frequency is sequentially generated, and the compressor 1 continues to operate at this frequency (hereinafter, such control will be referred to as load response control).

The outdoor control device 51 is further provided with a regulation signal generation section (regulation signal generation means) 65. When the discharge temperature monitoring control section 64 outputs the switching signal from the load response control to the regulation operation, the regulation signal generation section 65 detects the inverter drive frequency generated by the frequency control section 62 at that time. As a starting point, it has a function of generating a control frequency that decreases the frequency at a rate of, for example, 4 Hz per minute, and by outputting this gradually decreasing control frequency via the discharge temperature monitoring control section 64. , the compression capacity of compressor 1 is gradually decreasing (
(Hereinafter, such control will be referred to as droop control).

Incidentally, the discharge pipe 2 is further provided with an overload relay (not shown) that operates at the allowable upper limit temperature of the discharge gas refrigerant temperature, for example, 120°C, so that the discharge gas temperature from the compressor 1 reaches the above-mentioned allowable upper limit. When the temperature reaches that temperature, the compressor 1 is forcibly stopped by the overload relay (2).

Then, when the compressor 1 tends to overheat while the load response control continues, the discharge temperature monitoring control section 64 attempts to lower the temperature of the compressor 1 before the discharge gas temperature reaches the allowable upper limit temperature. , has a control function to prevent the operation from being forced to stop due to this. Next, such control will be explained based on the control flowchart of FIG. 4.

In the same figure, step S1 is the discharge temperature sensor 43.
The detected temperature Tot at the first reference temperature TI (for example, 10
8° C.), and while the temperature is lower than the first reference temperature T1, the compressor 1 is driven at the load response control σ described above in step S2. Then, by repeating steps S1 and 32, the operation based on the load response control is continued while comparing the detected temperature Tot with the first reference temperature TI.

When the above-mentioned Tot becomes T1 or more, the above-mentioned step S
1, the process moves to step S3, and a valve opening signal for the bypass valve 42 is output. As a result, a part of the liquid refrigerant flowing through the liquid pipe 14 explained based on FIG.
This means that the accumulator 7 is directly bypassed. As a result, the refrigerant in which the bypass liquid refrigerant is mixed into the suction gas refrigerant is sucked into the compressor 1, and the liquid component explodes in the compressor 1.
The cooling effect of the circulating refrigerant on the air becomes large. This is intended to lower the temperature of the compressor 1, which has tended to overheat, to a normal operating temperature range. By utilizing the evaporation effect of this liquid refrigerant, a relatively large cooling effect can be obtained even if the amount of bypass liquid refrigerant is small. However, as in the above configuration where the liquid refrigerant is sucked into the compressor 1 via the accumulation rake 7, when an excessive amount of liquid refrigerant is supplied to the compressor 1, liquid compression occurs, so it is necessary to keep it to a small amount. Therefore, the cooling effect is limited to some extent. In the above, the capillary tube 41 is interposed in the injection pipe 40, and the amount of bypass liquid refrigerant is adjusted to the minimum necessary amount. In this way, when bypassing a small amount of liquid refrigerant, the compression capacity of the compressor 1,
It is also possible to lower the temperature of the compressor 1 without substantially impairing the air conditioning or hot water heating capacity of the user heat exchanger.

After starting the cooling operation using the bypass liquid refrigerant by the process of step S3 in FIG. 4 as described above, step S4
, S5, and S6 are repeated. That is, in step S5, the load response control is continued, and in step S4, the second reference temperature T2, which is set higher than the first reference temperature TI (for example, 110°
C) and the detected temperature Td, and in step S6, the return temperature Tr (for example, 93°C) and the detected temperature Td are compared.
Compare d. During this time, if the discharge gas temperature gradually decreases due to the cooling effect of the bypass liquid refrigerant, when the detected temperature Tot reaches the return temperature Tr in the step S6, steps S6 to S7 are performed.
, outputs a valve closing signal for the bypass valve 42, and
The liquid refrigerant bypass operation described above is stopped, and the process returns to step S1 to proceed to the repeating process of S1 and S2 during normal operation.

On the other hand, if the temperature of the discharged gas cannot be lowered even by the cooling effect of the bypass liquid refrigerant, the process moves from step S4 to step S8 when the detected temperature Tot reaches T2, and in this step While outputting the drooping control signal, the process proceeds to an iterative process in which it is determined in step S9 whether or not the detected temperature Tot has decreased to the return temperature Tr. Therefore, during this period, along with the cooling effect of the bypass liquid refrigerant, the rotational frequency of the compressor 1 is gradually decreased at a rate of, for example, 4 Hz per minute. The temperature is lowered by gradually decreasing the detected temperature T.
When ot drops to the return temperature Tr, step S7
In step S1, the liquid refrigerant bypass operation is stopped, and then the process proceeds to steps S1 and S2 during normal operation using load response control.

As described above, in the above embodiment, when the compressor 1 tends to overheat, the cooling effect by bypassing the liquid refrigerant to the compressor is combined with the reduction in compression capacity. The structure is designed to lower the temperature of the compressor 1. Therefore, the rate of decrease in compression capacity can be reduced by the cooling effect of the liquid refrigerant, so that, for example, the degree of decrease in air conditioning capacity is also reduced, making it possible to improve comfort compared to the past.

In addition, when the compressor 1 starts to overheat, a cooling operation is first performed by bypassing the liquid refrigerant, and then, if this operation alone causes a further temperature rise, the compression capacity is reduced, for example. In the case of a tendency to overheat with a small abnormal calorific value in unit 1, it is possible to eliminate the tendency to overheat simply by cooling the liquid refrigerant by bypass, and as a result, the compression capacity decreases with a decrease in the air conditioning capacity, etc. Comfort can be further improved by reducing the frequency of reduction operations.

Furthermore, by configuring the compression capacity reduction operation to be gradually reduced, the air conditioning capacity etc. will not drop suddenly, and the above-mentioned gradual reduction operation will be performed while monitoring the discharge temperature, and when the discharge temperature reaches the return temperature, the above-mentioned By stopping the gradual reduction operation and returning to load response control, the air conditioning capacity, etc. will not be excessively reduced, and this also makes it possible to improve comfort.

Although the above description has been made by taking as an example a multi-type heat pump system having a multi-room air conditioning function and a hot water heating function, the present invention can be applied to other refrigeration systems such as a dedicated air conditioner, for example.

(Effects of the Invention) As described above, in the refrigeration system according to the first claim of the present invention, when the compressor tends to overheat, the cooling effect is achieved by bypassing the liquid refrigerant to the compressor. By using this together with the reduction in compression capacity, the rate of reduction in compression capacity can be reduced by the cooling effect of the liquid refrigerant, so for example, the degree of reduction in air conditioning capacity, etc. is reduced, and comfort is improved. It is possible to improve this compared to the conventional method.

Further, in the refrigeration system according to the second aspect, when the compressor tends to overheat, a cooling operation is first performed by bypassing the liquid refrigerant, and then the compression capacity is reduced. In cases where the machine tends to overheat with a small abnormal calorific value, the frequency of compression capacity reduction operations accompanied by a decrease in air conditioning capacity etc. is reduced, thereby further improving comfort.

Furthermore, in the refrigeration system according to the third aspect, by having a configuration in which the compression capacity reduction operation is gradually reduced, it is possible to prevent the air conditioning capacity from dropping rapidly or dropping more than necessary. This makes it possible to improve the

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is a refrigerant circuit diagram of a refrigeration system according to an embodiment of the invention, FIG. 3 is a block diagram of an operation control system of the refrigeration system, and FIG. FIG. 3 is a control flowchart diagram performed by a discharge temperature monitoring control section in the apparatus. ■... Compressor, 11... Outdoor heat exchanger (heat source side heat exchanger), 14... Liquid pipe, 20... Indoor heat exchanger (user side heat exchanger), 27... Heat exchanger for hot water supply (user side heat exchanger), 40... Injection piping, 42...
・Bypass valve (on/off valve), 43...Discharge temperature sensor (
temperature detection means), 62... frequency control section (load response control means), 64... discharge temperature monitoring control section (discharge temperature monitoring control means), 65... regulation signal generation section (regulated operation control means) . Patent applicant: Daikin Industries, Ltd. Figure 1 Figure 4

Claims (1)

[Claims] 1. A heat source side heat exchanger (1) is installed in the compressor (1) with variable compression capacity.
1) and the user-side heat exchangers (20) (27) are connected to enable refrigerant circulation, and each of the above-mentioned heat exchangers (11) (20)
(27) and the liquid pipe (14) interconnecting the compressor (
1) is connected to the suction side of the on-off valve (42) by an injection pipe (40) provided with an on-off valve (42).
By opening the valve, a part of the liquid refrigerant flowing through the liquid pipe (14) is configured to bypass to the suction side of the compressor (1) through the injection pipe (40), and the use side heat exchanger (20) Load response control means (62) for operating the compressor (1) with a response compression capacity according to the load on the (27) side; ), and a temperature detection means (43) for detecting the temperature of the gas refrigerant discharged from the compressor (1), and the detected temperature exceeds the first reference temperature. When the on-off valve (4)
A refrigeration system characterized by being provided with a discharge temperature monitoring control means (64) which aims at lowering the detected temperature by using both the opening of the valve in 2) and the switching to operation by the regulated operation control means (65). . 2. When the temperature detected by the temperature detection means (43) exceeds the first reference temperature, the on-off valve (42) is opened, and when the temperature exceeds the second reference temperature, which is higher than the first reference temperature. Switching to operation using the regulated operation control means (65), and then, when the detected temperature drops to the recovery temperature, closing the on-off valve (42) and returning to operation using the load response control means (62). The refrigeration system according to claim 1, wherein the control is performed by the discharge temperature monitoring control means (64). 3. When the temperature detected by the temperature detection means (43) exceeds a second reference temperature, the compression capacity of the compressor (1) is controlled to gradually decrease from the compression capacity at that time at a predetermined reduction rate. The refrigeration system according to claim 2, characterized in that said regulated operation control means (65) performs the control.