JPH10132406A - Refrigerating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a smooth retrial control by a method wherein the operation is stopped once when a high pressure on the delivery side of a compressor excessively rises in the heating operation to perform a reverse cycle operation by switching a main refrigerant circuit to a cooling cycle and then, the heating operation is restarted with the switching thereof over to a heating cycle. SOLUTION: When the state of a refrigerant detected by a state detection means SS reaches a predetermined set position, a stop processing means 41 stops the operation of compressors 1a and 1b. In order words, when a high pressure detected by a high pressure sensor rises excessively and when the temperature of a delivery pipe detected by a delivery pipe sensor rises excessively, the stop processing means 41 stops the compressors 1a and 1b once until a specified time passes. In the heating operation, upon the ending of the stop processing by the stop processing means 41, a four-path changeover valve is changed over to switch a main refrigerant circuit 18 once to a cooling cycle and a reverse cycle operation 42 is performed. Then, the normal heating operation is restarted for retrial by switching the circuit over to the heating cycle again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a refrigeration apparatus,
In particular, it relates to retry control measures.

[0002]

2. Description of the Related Art Conventionally, an air conditioner as a refrigerating apparatus has a compressor, a four-way switching valve, an outdoor heat exchanger, an outdoor expansion valve, as disclosed in JP-A-6-11207. Some include a main refrigerant circuit in which an indoor expansion valve and an indoor heat exchanger are sequentially connected. The main refrigerant circuit is provided with a high-pressure sensor for detecting a high-pressure pressure (condensing pressure) of the refrigerant discharged from the compressor and a discharge-pipe temperature sensor for detecting the discharge pipe temperature of the discharged refrigerant.

In the above air conditioner, when the high pressure detected by the high pressure sensor becomes equal to or higher than a predetermined value, retry control is performed to temporarily stop the operation of the compressor, wait for a predetermined time, and restart the operation. Also, when the discharge pipe temperature rises abnormally, retry control is performed to temporarily stop the operation of the compressor, wait a predetermined time and restart the operation.

[0004]

However, in the above-described air conditioner, the retry control is only executed in the heating cycle during the heating operation, so that the high pressure does not decrease or the discharge pipe temperature does not decrease. There was a problem of restarting as is.

In other words, during the heating operation, if the high pressure is excessively increased due to a delay in control of the capacity of the compressor, etc., the refrigerant pipe in the discharge line from the four-way switching valve to the indoor heat exchanger is at a high temperature. At the time of restart, the high pressure is easily increased. In particular, in a main refrigerant circuit having no equalizing line for equalizing the discharge side and the suction side of the compressor, the compressor is restarted in a state where the refrigerant pressure in the discharge line is relatively high. As a result, the high pressure increases again at the time of retry, and finally, the abnormal processing of the high pressure abnormality is executed.

[0006] The cause of the excessive rise in the discharge pipe temperature is that the control of the electric expansion valve cannot keep up with a sudden change in the amount of refrigerant circulation, or that the difference between the suction pressure and the discharge pressure of the compressor is large. (When the compression ratio is high) and when the amount of refrigerant is small (in the case of running out of gas).

[0007] In any of these cases, it is considered that the suction pressure of the compressor is very low. In particular, during the heating operation, the high pressure is maintained at a certain pressure (14 kg /
In the main refrigerant circuit, which is maintained at cm ² ) and does not include the pressure equalizing line, the compression ratio tends to increase when restarting. As a result, at the time of retry, the discharge pipe temperature rises again, and finally the discharge pipe temperature becomes abnormal, and the abnormal processing is executed.

As described above, in the main refrigerant circuit having no pressure equalizing line, there is a problem that the retry control of the high pressure and the discharge pipe temperature is not smoothly performed, and a comfortable air conditioning operation cannot be performed. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to enable smooth retry control due to an excessive rise in high pressure or the like.

[0010]

[Means for Solving the Problems]

−Summary of the Invention− The present invention relates to a reversible main refrigerant circuit (18) for circulating a refrigerant between a cooling cycle and a heating cycle, when a high pressure or the like on the discharge side of the compressor (1a, 1b) excessively increases during a heating operation. Then, the operation of the compressors (1a, 1b) is temporarily stopped. Thereafter, the main refrigerant circuit (18) is temporarily switched to the cooling cycle to perform the reverse cycle operation, and then switched to the heating cycle to resume the normal heating operation.

[Solution Means] Specifically, as shown in FIG. 1, the means adopted by the invention according to claim 1 includes a compressor (1a, 1b), a heat source side heat exchanger (14) and an expansion Mechanism (EV-1, EV-2) and user-side heat exchanger (3
0) are sequentially connected, and a reversible main refrigerant circuit (18) for circulating refrigerant is provided in the cooling cycle and the heating cycle. State detection means (SS) for detecting the state of the refrigerant on the discharge side of the compressor (1a, 1b) is provided. Furthermore,
Stop processing means (41) for stopping the operation of the compressors (1a, 1b) when the refrigerant state detected by the state detection means (SS) reaches a predetermined set state is provided. In addition, when the stop processing of the stop processing means (41) is completed during the heating operation in which the main refrigerant circuit (18) is set to the heating cycle, the main refrigerant circuit (18) is temporarily switched to the cooling cycle to perform the reverse cycle operation. Thereafter, a reverse cycle operation means (42) for switching to the heating cycle and restarting the normal heating operation is provided.

According to a second aspect of the present invention, in the first aspect of the present invention, the oil return operation is performed by setting the main refrigerant circuit (18) to a cooling cycle every predetermined operation time. Oil return operation means (43) is provided. The reverse cycle operation means (42) includes a stop processing means (41)
The reverse cycle operation after the end of the stop processing is replaced with the oil return operation means (43) and is also used as the oil return operation.

According to a third aspect of the present invention, in the first aspect of the present invention, the main refrigerant circuit (18) is configured to equalize the compressor (1a, 1b), the discharge side and the suction side. It does not have a pressure line.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the state detecting means (SS) comprises:
The refrigerant pressure or the refrigerant temperature on the discharge side of the compressor (1a, 1b) is detected.

According to the present invention, first, the state detecting means (SS) detects the state of the refrigerant on the discharge side of the compressors (1a, 1b) during the air-conditioning operation. According to the fourth aspect of the present invention, the high pressure, which is the refrigerant pressure on the discharge side of the compressor (1a, 1b), or the discharge pipe temperature, which is the refrigerant temperature, is detected.

Then, during the heating operation in which the main refrigerant circuit (18) is in a heating cycle, it is determined whether or not the discharge pipe temperature has reached a predetermined value or whether or not the high pressure has reached a predetermined value. If the discharge pipe temperature is normal, the heating operation is continued, and if the discharge pipe temperature has reached a predetermined value or the high pressure has reached a predetermined value, the stop processing means (4
1) temporarily stops the compressors (1a, 1b) and executes a retry stop process. Thereafter, the stop processing means (41) causes the operation of the compressors (1a, 1b) to wait until a predetermined time elapses, and when the restart standby processing is completed, the reverse cycle operation means (42) starts the reverse cycle operation. To resume normal heating operation.

That is, in the above-described reverse cycle operation, the compressor (1a, 1b) is started by changing the state in which the main refrigerant circuit (18) is stopped in the heating cycle to the cooling cycle. At this time, the indoor fan (Fr) is stopped, and each electric expansion valve (EV-
Perform reverse cycle operation with 1, EV-2) fully open.

According to the second aspect of the invention, the reverse cycle operation of the reverse cycle operation means (42) also serves as the oil return operation of the oil return operation means (43), and the lubricating oil of the main refrigerant circuit (18) is used. Return to the compressor (1a, 1b). This oil return operation means (4
In 3), the oil return operation is performed at predetermined time intervals. However, when the reverse cycle operation means (42) executes the reverse cycle operation, the time interval is reset and the reverse cycle operation means (42) is reset. When a predetermined time interval elapses from the reverse cycle operation of the above), the oil return operation is executed.

[0019]

Therefore, according to the present invention, when the refrigerant pressure on the discharge side of the compressors (1a, 1b) rises excessively, the main refrigerant circuit (18) is switched from the heating cycle to the cooling cycle to perform the reverse cycle operation. After that, the normal heating operation is resumed, so that the discharge side refrigerant pipe at the time of starting the heating operation heated to a high temperature state is cooled by the refrigerant sucked into the compressors (1a, 1b). In addition, due to the effect of mixing the high-pressure gas refrigerant and the low-pressure gas refrigerant, the pressure of the high-pressure refrigerant at the time of starting the heating operation can be reliably reduced. Therefore, the temperature of the refrigerant on the discharge side at the time of starting the heating operation can be reliably reduced.

As a result, the refrigerant condensing pressure and the refrigerant temperature on the discharge side at the time of restarting during the heating operation can be reliably suppressed from excessively rising again, so that the heating operation can be restarted smoothly. Heating comfort can be improved.

According to the second aspect of the present invention, since the reverse cycle operation also serves as the oil return operation, the interval of the original oil return operation can be extended, so that the heating capacity is reduced. Can be suppressed.

According to the third aspect of the present invention, the pressure equalizing line for communicating the discharge side and the suction side of the compressors (1a, 1b) is not provided in the main refrigerant circuit (18). Also,
Since an excessive rise in the refrigerant pressure or the like at the time of retry can be suppressed, reliability can be improved.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIGS. 2 and 3, the air conditioner of the present embodiment is a multi-type air conditioner as a refrigerating device in which one outdoor unit (1A) is connected to a plurality of indoor units (1B). The outdoor unit (1A) and multiple indoor units (1B) are connected to the liquid side and gas side communication pipes (L
L, LG). FIG. 2 shows the refrigerant piping system of the outdoor unit (1A), whereas the indoor units (1B) have the same configuration. FIG. 3 shows the refrigerant piping system of one indoor unit (1B). Is shown.

The outdoor unit (1A) includes a compression mechanism (1A).
0), an oil separator (2a, 2b), a four-way switching valve (13),
An outdoor heat exchanger (14) as a heat source side heat exchanger, an outdoor electric expansion valve (EV-1) as an expansion mechanism, and a receiver (15);
An accumulator (16) is provided as main equipment.
These devices (10 to 16, EV-1) are connected by a refrigerant pipe (RP) and constitute an outdoor side of a main refrigerant circuit (18) through which the refrigerant flows.

The compression mechanism (10) includes a first compressor (1a)
And the second compressor (1b) are connected in parallel with each other. The first compressor (1a) controls only driving and stopping, and the second compressor (1b) uses a capillary tube (CP) and a solenoid valve (SV-1) on the discharge side and the suction side. The capacity is changed by the opening and closing operation of the solenoid valve (SV-1).

An oil recovery pipe (12a, 1b) provided with a capillary tube (CP, CP) is provided on the suction side of each of the compressors (1a, 1b).
The oil separators (2a, 2b) are connected by 2b), and the compressors (1a, 1b) are connected by oil equalizing pipes (1c).

The four-way switching valve (13) switches as shown by the solid line in the drawing during the cooling operation, and switches as shown by the broken line in the drawing during the heating operation to switch the refrigerant circulation operation. The outdoor heat exchanger (14) is provided with two outdoor fans (Fo, Fo), exchanges heat between the refrigerant and the outside air, functions as a condenser during a cooling operation, and functions as an evaporator during a heating operation. .
Further, the outdoor electric expansion valve (EV-1) adjusts the flow rate of the refrigerant during the cooling operation, and performs the pressure reducing operation of the refrigerant during the heating operation.

The main refrigerant circuit (18) is provided with an injection passage (LJ) and a bypass passage (21). The injection passage (LJ) supplies a liquid refrigerant to each of the compressors (1a, 1b) during the cooling / heating operation, and supplies the liquid refrigerant to the compressors (1a, 1a).
Cool the discharged refrigerant of 1b). One end of the injection passage (LJ) is connected between the outdoor electric expansion valve (EV-1) and the receiver (15), and the other end is branched and connected to each of the compressors (1a, 1b). Has a capillary tube (CP, CP) and a solenoid valve (SV
-2, SV-2).

The bypass passage (21) is a passage for heating overload control, and one end is connected between the oil separators (2a, 2b) and the four-way switching valve (13), and the other end is connected. , Is connected between the outdoor heat exchanger (14) and the outdoor electric expansion valve (EV-1). The bypass path (21) is composed of an auxiliary heat exchanger (22), an electromagnetic valve (SV-3), and a capillary tube (CP) connected in series in order, and includes a four-way switching valve (13) and an outdoor heat exchanger. It is connected in parallel to the vessel (14). This solenoid valve (SV
-3) is open at all times during the cooling operation, and opens when the high pressure is excessively increased during the heating operation.
A part of the discharge gas is bypassed to the auxiliary heat exchanger (2).
Condensate in 2).

The main refrigerant circuit (18) is provided with a compressor (1).
There is no pressure equalizing line that connects the discharge side and the suction side of the compression mechanism (10) when the a, 1b) is stopped.

On the other hand, the indoor unit (1B) includes an indoor heat exchanger (30), which is a use side heat exchanger serving as an evaporator during a cooling operation and a condenser during a heating operation, and a fan (Fr) thereof.
And an indoor electric expansion valve (EV-2), which is an expansion mechanism for adjusting the flow rate of the refrigerant during the heating operation and reducing the pressure of the refrigerant during the cooling operation, on the liquid pipe side of the indoor heat exchanger (30). Is provided.

Further, various sensors are arranged in this air conditioner. (Th-1) is a room temperature sensor that detects the indoor temperature, and (Th-2) and (Th-3) are indoor liquids that detect the temperature of the refrigerant in the liquid and gas pipes of the indoor heat exchanger (30), respectively. Temperature sensor and indoor gas temperature sensor, (Th-4)
Is a discharge pipe sensor that detects the discharge pipe temperature of each compressor (1a, 1b), (Th-5) is a defrost sensor that detects the frost state from the refrigerant temperature of the outdoor heat exchanger (14) during the heating operation, Th
-6) is a suction pipe sensor that detects the suction pipe temperature of the compressors (1a, 1b), and (Th-7) is an outside heat sensor that is located at the air suction port of the outdoor heat exchanger (14) and detects the outdoor air temperature. It is a temperature sensor.

[0034] (SP-H) is disposed in the discharge pipe of the compressor (1a, 1b) and detects a high-pressure side pressure of the main refrigerant circuit (18). (SP-L) is a compressor (1a). , 1b) is a low-pressure sensor that is disposed in the suction line and detects the low-pressure side pressure. (HP-S) is a high-pressure switch for protecting the compressors (1a, 1b).

The high pressure sensor (SP-H) and the discharge pipe sensor (Th-4) constitute state detection means (SS) for detecting the state of the refrigerant on the discharge side of the compressors (1a, 1b). .

Sensors such as the above-mentioned room temperature sensor (Th-1)
The control unit (40) is connected by signal lines to the control unit (40). The control unit (40) receives signals from the sensors and controls the opening and closing of each motor-operated valve (EV-1, EV-2) and the compressor (1a, 1b).
Control of the capacity.

The control unit (40) is provided with stop processing means (41) and reverse cycle operation means (42) as features of the present invention.

The stop processing means (41) stops the operation of the compressors (1a, 1b) when the state of the refrigerant detected by the state detecting means (SS) reaches a predetermined set state. That is, when the high pressure detected by the high pressure sensor (SP-H) rises excessively, the stop processing means (41) outputs the discharge pipe sensor (Th-4)
If the detected discharge pipe temperature rises excessively, the compressor (1a,
1b) is temporarily stopped until a predetermined time has elapsed.

The reverse cycle operating means (42) switches the four-way switching valve (13) to switch the main refrigerant circuit (18) when the stop processing of the stop processing means (41) is completed during the heating operation.
Is temporarily switched to the cooling cycle to perform the reverse cycle operation, and then switched to the heating cycle to resume the normal heating operation and retry.

The control unit (40) is provided with an oil return operation means (43). The oil return operation means (43) is provided for every predetermined operation time, for example, every 8 hours. When the oil return timer that counts the time is up, an oil return operation of a reverse cycle in which the main refrigerant circuit (18) is set to the cooling cycle is executed, and at this time, the indoor fan (Fr) is stopped and each electric expansion valve ( EV-1 and EV-2) are fully opened to return the lubricating oil to the compression mechanism (10).

The reverse cycle operation means (42) also serves as an oil return operation. In other words, the reverse cycle operation means (42) temporarily stops the compressors (1a, 1b) and performs retry control when the high pressure or the like excessively increases during the heating operation, but performs the reverse cycle operation of the cooling cycle for a predetermined time. For example,
The reverse cycle operation for 4 minutes is performed, and the oil return operation is also used. On the other hand, when the reverse cycle operation means (42) performs reverse cycle operation, the oil return operation means (43) resets the oil return timer, and 8 hours after the reverse cycle operation of the reverse cycle operation means (42). After the elapse, the oil return operation is performed.

-Air-conditioning operation- Next, the operation of the air conditioner will be described.

During the cooling operation, the four-way switching valve (13) is switched to the solid line side in FIG. 2 to set the main refrigerant circuit (18) to the cooling cycle. The electric expansion valve (EV-1) of the outdoor unit (1A) is fully opened, and the indoor electric expansion valve (EV-2) is the indoor heat exchanger (30)
Is controlled so as to keep the degree of superheat of the refrigerant at the outlet side of. In addition, the solenoid valve (SV-3) in the bypass passage (21) is always opened.

In this state, the refrigerant compressed by the compression mechanism (10) is condensed by the outdoor heat exchanger (14) and the auxiliary heat exchanger (22), and then passes through the liquid side communication pipe (LL) to the room. Flow to unit (1B). In each indoor unit (1B), the liquid refrigerant is depressurized by the indoor electric expansion valve (EV-2), and the indoor heat exchanger (3B)
After evaporating in 0), it returns to the outdoor unit (1A) via the gas side connection pipe (LG) and is sucked into the compression mechanism (10). This refrigerant circulation is repeated, and the liquid refrigerant exchanges heat with the indoor air in the indoor heat exchanger (30) to evaporate, thereby cooling the indoor air.

On the other hand, during the heating operation, the four-way switching valve (13)
Is switched to the broken line side in FIG. 2 to make the main refrigerant circuit (18) a heating cycle. The indoor electric expansion valve (EV-2) is fully opened,
The outdoor electric expansion valve (EV-1) is controlled to keep the degree of superheat of the refrigerant at the outlet side of the outdoor heat exchanger (14) constant.

In this state, the refrigerant compressed by the compression mechanism (10) passes through the gas side communication pipe (LG) and the indoor unit (1).
B), condenses in the indoor heat exchanger (30), and then returns to the outdoor unit (1A) via the liquid side communication pipe (LL). In the outdoor unit (1A), the liquid refrigerant is depressurized by the outdoor electric expansion valve (EV-1), evaporated in the outdoor heat exchanger (14), and then sucked into the compression mechanism (10). This refrigerant circulation is repeated, and the gas refrigerant exchanges heat with the indoor air in the indoor heat exchanger (30), condenses, and heats the indoor air.

Next, the operation of the retry control, which is a feature of the present invention, will be described with reference to the control flow of FIG.

First, in step ST1, as described above, the four-way switching valve (13) is switched to the dashed line in FIG. 2 to set the main refrigerant circuit (18) to the heating cycle and perform the heating operation. During this heating operation, in step ST2, it is determined whether or not the discharge pipe temperature detected by the discharge pipe sensor (Th-4) has reached a predetermined value A, or the high pressure detected by the high pressure sensor (SP-H) has reached a predetermined value. It is determined whether the value B has been reached. When the discharge pipe temperature does not reach the predetermined value A, or when the high pressure does not reach the predetermined value B, the discharge pipe temperature and the like are normal.
The determination in step ST2 is NO, the process returns to step ST1, and the heating operation is continued.

On the other hand, in step ST2, when the discharge pipe temperature has reached the predetermined value A or when the high pressure has reached the predetermined value B, the discharge pipe temperature has risen excessively or the high pressure has risen excessively. So the determination is YES and the step
Move to ST3.

In this step ST3, the stop processing means (41) detects an excessive rise in the discharge pipe temperature or an excessive rise in the high pressure, temporarily stops the compressors (1a, 1b), and executes a retry stop processing. I do. Thereafter, the process proceeds from step ST3 to step ST4, and the stop processing means (41) performs the operation of the compressor (1a,
The operation of 1b) is made to wait until a predetermined time has elapsed, and a process of waiting for restart is executed.

After that, when the restart processing of the stop processing means (41) is completed, the above-described steps ST4 to ST4 are executed.
The process proceeds to step 5, and the reverse cycle operation means (42) performs reverse cycle operation, returns to step ST1, and resumes the normal heating operation.

That is, in the reverse cycle operation, the four-way switching valve (13) is switched to the side indicated by the solid line in FIG. 2 from the state in which the main refrigerant circuit (18) is stopped in the heating cycle.
Start the compressors (1a, 1b) with 8) as the cooling cycle. At that time, the indoor fan (Fr) is stopped, and the electric expansion valves (EV-1, EV-2) are fully opened, and the reverse cycle operation is performed for 4 minutes.

The reverse cycle operation of the reverse cycle operation means (42) also serves as the oil return operation of the oil return operation means (43), and returns the lubricating oil of the main refrigerant circuit (18) to the compression mechanism (10). The oil return operation means (43) performs the oil return operation, for example, every eight hours. However, when the reverse cycle operation means (42) executes the reverse cycle operation, the oil return operation means (43) resets the eight hours, When eight hours have passed since the reverse cycle operation of the reverse cycle operation means (42), the oil return operation is executed.

On the other hand, by the reverse cycle operation of the reverse cycle operation means (42), the four-way switching valve (13) during the heating operation is operated.
The refrigerant pipe (RP) on the discharge side of the indoor heat exchanger (30) communicates with the suction side of the compressor (1a, 1b), and the four-way switching valve (13) during the heating operation passes through the outdoor heat exchanger (14). ) Side suction side refrigerant pipe (RP) communicates with the discharge side of the compressors (1a, 1b). For this reason, the high pressure during the heating operation and the low pressure during the heating operation are mixed, so that the high pressure during the heating operation is reduced, and the discharge side refrigerant pipe (RP) during the heating operation that has been heated to a high temperature is cooled. Is done.

-Effects of Embodiment- As described above, according to this embodiment, when the high pressure or the like is excessively increased, the main refrigerant circuit (18) is switched from the heating cycle to the cooling cycle to perform the reverse cycle operation. Later, because the normal heating operation was restarted, the discharge side refrigerant pipe (RP) at the time of starting the heating operation heated to a high temperature state,
Cooled by the refrigerant drawn into the compressors (1a, 1b),
Due to the effect of mixing the high-pressure gas refrigerant and the low-pressure gas refrigerant, the high-pressure pressure at the time of starting the heating operation can be reliably reduced. Therefore, the discharge pipe temperature at the time of starting the heating operation can be reliably reduced.

As a result, it is possible to reliably prevent the high pressure (refrigerant condensing pressure) and the discharge pipe temperature from excessively increasing again when the heating operation is restarted, so that the heating operation can be smoothly restarted. And heating comfort can be improved.

Further, since the reverse cycle operation means (42) also serves as the oil return operation, the interval of the original oil return operation can be extended, so that a decrease in the heating capacity can be suppressed. .

Further, even when the pressure equalizing line for communicating the discharge side and the suction side of the compressors (1a, 1b) is not provided in the main refrigerant circuit (18), the excess pressure such as the high pressure during the retry can be obtained. Since the rise can be suppressed, the reliability can be improved.

[0059]

Other Embodiments In the present embodiment, a multi-type air conditioner having a plurality of indoor units (1B) has been described. However, the present invention has one indoor unit (1B). The main refrigerant circuit (18) is not limited to the embodiment.

The main refrigerant circuit (18) includes a compressor (1a,
The compressor (1a, 1b) may be provided with an inverter for controlling the compressor (1a, 1b) by an inverter. The reliability can be further improved by the reverse cycle operation.

In the first aspect of the present invention, it is not necessary to combine the reverse cycle operation of the reverse cycle operation means (42) with the oil return operation, that is, the oil return operation means (43) is replaced with the reverse cycle operation means (42). The oil return operation may be executed regardless of the reverse cycle operation of 42).

The present invention also relates to two compressors (1a, 1b)
It is needless to say that the present invention is not limited to the one equipped with a compressor, and may be one equipped with one compressor, and is not limited to an air conditioner, but can be applied to various refrigeration systems. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant circuit diagram showing a main refrigerant circuit of the outdoor unit.

FIG. 3 is a refrigerant circuit diagram showing a main refrigerant circuit of the indoor unit.

FIG. 4 is a control block diagram illustrating retry control.

[Explanation of symbols]

 1A outdoor unit 1B indoor unit 10 compression mechanism 1a, ab compressor 13 four-way switching valve 14 outdoor heat exchanger (heat source side heat exchanger) 18 main refrigerant circuit RP refrigerant pipe LJ injection passage 21 bypass passage 30 indoor heat exchanger ( Use side heat exchanger) EV-1, EV-2 Electric expansion valve (expansion mechanism) SP-H High pressure sensor Th-4 Discharge pipe sensor SS State detection means 40 Control unit 41 Stop processing means 42 Reverse cycle operation means 43 Oil return Driving means

Claims (4)

[Claims] 1. A compressor (1a, 1b) and a heat source side heat exchanger (1).
4) and expansion mechanism (EV-1, EV-2) and use side heat exchanger (30)
A main refrigerant circuit (18), which is connected in order to recycle the refrigerant in a cooling cycle and a heating cycle, and a state detecting means (SS) for detecting a refrigerant state on the discharge side in the compressor (1a, 1b). When the state of the refrigerant detected by the state detection means (SS) reaches a predetermined set state, stop processing means (41) for stopping the operation of the compressor (1a, 1b); and the main refrigerant circuit (18) When the stop processing of the stop processing means (41) is completed during the heating operation in which the heating cycle is changed to the heating cycle, the main refrigerant circuit (18) is temporarily switched to the cooling cycle to perform the reverse cycle operation, and then switched to the heating cycle to perform the normal operation. A refrigerating apparatus comprising: a reverse cycle operation means (42) for restarting a heating operation. 2. The refrigeration apparatus according to claim 1, wherein the oil return operation means (43) executes the oil return operation by setting the main refrigerant circuit (18) to a cooling cycle at every predetermined operation time set in advance. The reverse cycle operation means (42) is configured such that the reverse cycle operation after the stop processing of the stop processing means (41) ends is replaced with the oil return operation means (43) and also serves as the oil return operation. A refrigeration apparatus characterized by the above-mentioned. 3. The refrigeration system according to claim 1, wherein the main refrigerant circuit (18) is not provided with a pressure equalizing line for equalizing the compressors (1a, 1b) and the discharge side and the suction side. Refrigeration equipment. 4. The refrigerating apparatus according to claim 1, wherein the state detecting means (SS) detects the refrigerant pressure or the refrigerant temperature on the discharge side of the compressor (1a, 1b).