JP7048880B2 - Refrigeration and air conditioning equipment - Google Patents

Description

The present invention relates to a refrigerating air conditioner.

If the refrigerating air conditioner continues to operate with air mixed in the refrigerant circuit for some reason, the temperature inside the compressor may rise abnormally and the compressor may be damaged. Air contamination in the refrigerant circuit is likely to occur during pump down operation when the low pressure side pressure becomes atmospheric pressure or less. For this reason, the conventional refrigerating and air-conditioning device specifically pumps when an operating state in which there is a suspicion of air contamination during pump-down operation is detected, such as the air conditioner described in Patent Document 1. Measures have been taken to forcibly stop the operation of the compressor when the end of the down operation is abnormally prolonged.

Japanese Unexamined Patent Publication No. 2016-90223

However, since the conventional air conditioner described in Patent Document 1 is a method of determining air contamination from a change in operating state in pump-down operation, it is possible to detect air contamination in normal air conditioning operation. Not only could it not be possible, but it could also be falsely detected.

An object of the present invention has been made in view of the problems in the prior art, and an object of the present invention is to provide a refrigerating and air-conditioning apparatus capable of directly detecting the mixing of air into a refrigerant circuit.

The refrigerating and air-conditioning apparatus according to the first aspect includes a refrigerant circuit having a compressor, an outdoor heat exchanger, a decompression mechanism, a liquid side closing valve, an indoor heat exchanger, and a gas side closing valve, and a suction side circuit of the compressor. An air sensor attached to the compressor for detecting the mixing of air in the refrigerant circuit, and the compressor so as to stop the operation of the compressor when the air sensor detects the mixing of air in the refrigerant circuit. It is equipped with a safe operation control unit that controls the operation of the compressor.

As used herein, the term "refrigerating and air-conditioning operation" refers to air conditioning operation that adjusts the temperature and humidity of the air in living rooms such as general households and office buildings and workplaces in factories, and cooling operation that cools the inside of refrigerators. It refers to an operation that applies a refrigeration cycle, such as a freezing operation that freezes the inside of a freezer and a cooling operation that cools the lubricating oil of a machine tool. Further, the "refrigerating and air-conditioning device" refers to a device that performs a refrigerating and air-conditioning operation as exemplified here.

Further, in the present specification, the "air sensor" may be any one that can detect the mixing of air into the refrigerant circuit, and by detecting oxygen gas, carbon dioxide gas, nitrogen gas, etc., which are components of air, It may be one that detects the inclusion of air. Further, the air sensor is preferably one that can detect the concentration of air contained in the refrigerant in the refrigerant circuit.

According to the refrigerating and air-conditioning apparatus of the first aspect, it is possible to directly detect air contamination in the refrigerant circuit and stop the operation of the compressor regardless of whether it is a normal refrigerating or air-conditioning operation or a pump-down operation. can. Further, since the air sensor is attached to the suction side circuit of the compressor, air contamination can be detected sensitively.

According to the refrigerating and air-conditioning apparatus according to the second aspect, the refrigerant circuit is provided with a four-way switching valve, and is formed so that the refrigerant flow direction can be reversibly switched by switching the four-way switching valve. It is attached to the suction pipe connecting the accumulator attached to the suction side of the compressor and the four-way switching valve.

In general, since the accumulator is a device attached to the compressor, it is often mounted close to the compressor, and there is often little extra space around the pipe connecting the compressor and the accumulator. Therefore, it is difficult to secure a space for mounting the air sensor around the pipe connecting the compressor and the accumulator. On the other hand, the four-way switching valve is not as strongly associated with the compressor as the accumulator, and there is often a margin between the accumulator and the four-way switching valve to secure the mounting space for the air sensor. Is easy.

According to the refrigerating and air-conditioning apparatus according to the third aspect, the pump down operation is performed by controlling the compressor and the pressure reducing mechanism in a state where the liquid side closing valve is closed and the gas side closing valve is opened. The pump-down operation control unit is further provided, and the safe operation control unit has the air sensor mixed with air in both the normal refrigerating and air-conditioning operation and the pump-down operation based on the control of the pump-down operation control unit. Is configured to stop the operation of the compressor when the above is detected.

According to this refrigerating and air-conditioning device, the operation of the compressor is controlled so as to stop the operation of the compressor when the air sensor detects the presence of air in both the normal refrigerating and air-conditioning operation and the pump-down operation. Therefore, damage to the compressor can be suppressed.

According to the refrigerating and air-conditioning apparatus according to the fourth aspect, the safe operation control unit is configured to immediately stop the operation of the compressor when the air sensor detects the inclusion of air.
According to this refrigerating and air-conditioning device, the operation of the compressor is stopped immediately when the air sensor detects the presence of air, so that damage to the compressor can be further suppressed.

According to the refrigerating and air-conditioning apparatus according to the fifth aspect, the refrigerating and air-conditioning apparatus according to the first to third aspects further includes a pressure sensor for detecting the low pressure side pressure, and the safe operation control unit is the pressure sensor. It is configured to stop the operation of the compressor when it is detected that the pressure on the low pressure side is equal to or lower than the atmospheric pressure and the air mixing is detected by the air sensor.

Air mixing into the refrigerant circuit cannot occur unless a portion below atmospheric pressure is generated in the refrigerant circuit. Therefore, if the low pressure side pressure is added to the atmospheric pressure or less as a condition for detecting air contamination and stopping the compressor as in this refrigeration and air conditioning device, the erroneous detection of air contamination by the air sensor will be further improved. It can be further suppressed.

According to the refrigerating and air-conditioning apparatus according to the sixth aspect, the compressor and the pressure reducing mechanism are controlled to perform a pump-down operation in a state where the liquid side closing valve is closed and the gas side closing valve is opened. Accumulation of the amount of air mixed in the refrigerant circuit from the pump down operation control unit to be performed and the air concentration in the refrigerant circuit measured by the air sensor and the number of revolutions of the compressor in the case of the pump down operation. Further provided with an air mixing amount calculation unit for calculating a value, the safe operation control unit stops the operation of the compressor in the case of normal refrigerating and air-conditioning operation when the air sensor detects air mixing. In the case of the pump down operation, the operation of the compressor is stopped when the air mixing amount calculation unit calculates a mixed air amount equal to or higher than a preset threshold value.

According to this refrigerating and air-conditioning apparatus, the operation of the compressor is stopped when the air sensor detects the inclusion of air during normal refrigerating and air-conditioning operation. Further, in the pump down operation, the operation of the compressor is stopped only when the cumulative amount of air mixed in exceeds a preset threshold value. Therefore, it is possible to suppress unnecessary system down due to erroneous detection.

According to the refrigerating and air-conditioning apparatus according to the seventh aspect, in the refrigerating and air-conditioning apparatus according to the first and second aspects, the refrigerating and air-conditioning apparatus further includes a pressure sensor for detecting the low pressure side pressure, and the safe operation control. The unit is configured to stop the operation of the compressor in normal operation when the pressure sensor detects that the pressure is below atmospheric pressure and the air sensor detects air contamination, and the pump down. In operation, the compressor is configured to stop operation when the air-conditioned air mixing amount calculation unit calculates a mixed air amount equal to or higher than a preset threshold value.

According to this refrigerating and air-conditioning device, the operation of the compressor is stopped when the pressure sensor detects that the pressure is below the atmospheric pressure and the air sensor detects the inclusion of air during normal operation. In addition, during pump down operation, the compressor operation is stopped only when the cumulative amount of air mixed in exceeds a preset threshold value. Therefore, unnecessary system down due to erroneous detection is suppressed. Can be done.

According to this refrigerating and air-conditioning apparatus, it is possible to directly detect the mixing of air into the refrigerant circuit and stop the operation of the compressor regardless of whether it is a normal operation or a pump-down operation.

The refrigerant circuit diagram of the refrigerating and air-conditioning apparatus which concerns on Embodiment 1. FIG. A block diagram showing peripheral devices connected to the control device of the refrigeration and air conditioning system. Correlation diagram between the amount of air mixed in and the possibility of compressor damage. Flow chart of air mixture detection operation in the refrigeration and air conditioner. The block diagram which shows the peripheral device connected to the control device of the refrigerating and air-conditioning apparatus which concerns on Embodiment 2. Flow chart of air mixture detection operation in the refrigeration and air conditioner. The flowchart of the air mixture detection operation in the refrigerating and air-conditioning apparatus which concerns on the modification of Embodiment 1. The flowchart of the air mixture detection operation in the refrigerating and air-conditioning apparatus which concerns on the modification of Embodiment 2.

Hereinafter, the refrigerating and air-conditioning apparatus according to the embodiment of the present invention will be described. It should be noted that the present invention is not limited to the examples described below, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. To.

(Embodiment 1)
In the air conditioner as the refrigerating and air-conditioning device according to the first embodiment, as shown in FIG. 1, the indoor unit 1 installed indoors and the outdoor unit 2 installed outdoors are connected to the liquid side connecting pipe L1. It is configured by being connected to the gas side connecting pipe L2. This air conditioner is a pair type air conditioner in which the indoor unit 1 and the outdoor unit 2 are connected one-to-one. The indoor unit 1 is equipped with an indoor heat exchanger 11, an indoor fan 12, an electric expansion valve 13 as an example of a pressure reducing mechanism, and the like. Further, the outdoor unit 2 is equipped with a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, a liquid side closing valve 24, a gas side closing valve 25, an accumulator 26, an outdoor fan 27 and the like. The liquid side closing valve 24 and the gas side closing valve 25 are manual on-off valves. Further, an air sensor 28 and a pressure sensor 29 are provided in the suction pipe connecting the accumulator 26 and the four-way switching valve 22.

Then, in this air conditioner, the refrigerant circuit is reversibly switched by switching the four-way switching valve 22, and the cooling operation is performed by the cooling cycle, and the heating operation is performed by the heating cycle. That is, during the cooling operation, as shown by the solid line arrow in FIG. 1, the compressor 21, the four-way switching valve 22, the outdoor heat exchanger 23, the liquid side closing valve 24, the liquid side connecting pipe L1, the electric expansion valve 13, A refrigerant circuit forming a cooling cycle in which the refrigerant is circulated in the order of the indoor heat exchanger 11, the gas side connecting pipe L2, the gas side closing valve 25, the four-way switching valve 22, the accumulator 26, and the compressor 21 is formed. Further, during the heating operation, as shown by the broken arrow in FIG. 1, the compressor 21, the four-way switching valve 22, the gas side connecting pipe L2, the indoor heat exchanger 11, the electric expansion valve 13, the liquid side connecting pipe L1, A refrigerant circuit forming a heating cycle in which the refrigerant is circulated in the order of the outdoor heat exchanger 23, the four-way switching valve 22, the accumulator 26, and the compressor 21 is formed.

In this air conditioner, in the cooling cycle, the outdoor heat exchanger 23 acts as a condenser and the indoor heat exchanger 11 acts as an evaporator, so that the indoor air circulated by the indoor fan 12 is cooled and dehumidified. , The room is cooled. Further, in this air conditioner, in the heating cycle, the outdoor heat exchanger 23 acts as an evaporator and the indoor heat exchanger 11 acts as a condenser, so that the indoor air circulated by the indoor fan 12 is heated. And the room is heated.

The air sensor 28 and the pressure sensor 29 are provided in the suction pipe connecting the accumulator 26 and the four-way switching valve 22 in the refrigerant circuit having the above configuration. The air sensor 28 detects oxygen, which is a component of air, that is, an oxygen sensor, which detects the mixing of air by detecting oxygen in the intake gas. The pressure sensor 29 detects the refrigerant pressure of the suction pipe, that is, the low pressure side pressure.

Further, the air conditioner is equipped with a control device 30 for controlling various operations as shown in FIG. The control device 30 is actually formed by a control unit mounted on the indoor unit 1 and a control unit mounted on the outdoor unit 2, but since it operates as a functional unit, it is one here. Express and explain as an element.

As shown in FIG. 2, a compressor 21, a four-way switching valve 22, an electric expansion valve 13, an outdoor fan 27, an indoor fan 12, a liquid side closing valve 24, and a gas side closing valve 25 are connected to the control device 30. ing. More specifically, the drive unit of these devices is connected to the control device 30. Further, the control device 30 includes an outdoor heat exchanger temperature sensor 41 and an outside air temperature sensor 42, an indoor heat exchanger temperature sensor 43, an indoor temperature sensor 44, an operation / stop button 45, and the above-mentioned air sensor 28 and pressure sensor. 29 is connected. Further, the remote controller 35 is wirelessly connected to the control device 30.

In the above, the outdoor heat exchanger temperature sensor 41 is installed in the outdoor heat exchanger 23 and detects the temperature of the outdoor heat exchanger 23. The outside air temperature sensor 42 is installed inside the outdoor unit 2 and detects the temperature of the outside air. The indoor heat exchanger temperature sensor 43 is installed in the indoor heat exchanger 11 and detects the temperature of the indoor heat exchanger 11. The indoor temperature sensor 44 is installed in the indoor unit 1 and detects the indoor air temperature. The start / stop button 45 is a switch for starting and stopping the pump down operation.

The remote control 35 functions as an operation operation unit for the air conditioner, and includes an operation switch for turning on / off the operation of the air conditioner, an operation mode selection unit, a setting unit for setting the set temperature of the room air, and normal heating. It is provided with an air volume setting unit for setting the air volume of the indoor fan 12 during operation, a display unit for displaying the indoor temperature and the air volume of the indoor fan 12, and the like. The remote controller 35 is configured to wirelessly transmit the selected or set driving operation information to the control device 30.

The control device 30 includes a microcomputer, an input / output circuit, and the like, and includes a normal operation control unit 31, a pump-down operation control unit 32, and a safe operation control unit 33.
The normal operation control unit 31 detects a command from the remote control 35, an outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor 41, an outside air temperature detected by the outside air temperature sensor 42, and an indoor heat exchanger temperature sensor 43. Based on the indoor heat exchanger temperature, the indoor temperature detected by the indoor temperature sensor 44, and the like, arithmetic processing, judgment processing, and the like are performed to control the normal operation of the air conditioner. The command from the remote controller 35 includes an operation start command, a room temperature setting command, and the like.

The pump-down operation control unit 32 controls the electric expansion valve 13 and the compressor 21 to perform the pump-down operation when receiving a command for the pump-down operation issued from the operation / stop button 45.

That is, in the above-mentioned refrigerant circuit, when a refrigerant leaks in the indoor unit 1, or when the air conditioner is relocated or repaired, the pump down operation is performed. When performing the pump-down operation, the operation / stop button 45 (see FIG. 2) provided on the indoor unit 1 or the outdoor unit 2 is pressed and held to the pump-down operation control unit 32 of the control device 30. The start of forced operation is ordered. On the other hand, the worker closes the liquid side closing valve 24 while opening the gas side closing valve 25. Then, the electric expansion valve 13 is fully opened by the pump down operation control unit 32, the four-way switching valve 22 is switched to the cooling cycle side, and then the compressor 21 is driven at a predetermined frequency (for example, 50 Hz). A pump-down operation is performed in which the refrigerant on the indoor unit 1 side is recovered on the outdoor unit 2 side.

By performing the pump-down operation in this way, the pump-down is substantially completed when the temperature difference between the indoor temperature and the temperature of the indoor heat exchanger 11 continues to be below the predetermined temperature difference for a predetermined time or longer. It is judged that it is doing. When the pump down is substantially completed, the refrigerant in the indoor heat exchanger 11 becomes diluted, and heat exchange is substantially not performed. As a result, the temperature difference between the indoor temperature and the temperature of the indoor heat exchanger 11 becomes less than the predetermined temperature difference. When such a state occurs, the operator is notified by a command from the pump down operation control unit 32 that the pump down is substantially completed by lighting the end lamp (not shown) or the like, and the compressor 21 is notified. Is operated at a predetermined frequency. Therefore, the operator closes the gas side closing valve 25 and stops the compressor 21 by operating the start / stop button 45. As a result, the pump down operation is completed.

The safe operation control unit 33 operates the compressor 21 so as to avoid damage to the compressor 21 by receiving at least the low pressure side pressure detected by the pressure sensor 29 and the presence or absence of air contamination by the air sensor 28. Control.

If the operation of the compressor 21 is continued with air mixed in the refrigerant circuit, the temperature inside the compressor 21 rises. As shown in FIG. 3 the relationship between the amount of oxygen in the refrigerant circuit and the possibility of damage to the compressor, the greater the amount of oxygen in the refrigerant circuit, the greater the risk of damage to the compressor. Therefore, in this air conditioner, the safe operation control unit 33 operates at the same time as the start of operation, and the operation of detecting air contamination in the refrigerant circuit and the operation of coping with the detection of air contamination are performed.

Next, as the operation of the air conditioner according to the present embodiment, the operation of detecting air contamination in the refrigerant circuit by the safe operation control unit 33 and the response operation at the time of detecting air contamination will be described in detail with reference to FIG.

As shown in FIG. 4, at the same time as the refrigerating and air-conditioning operation is started, the low pressure side pressure in the suction pipe of the compressor 21 is monitored by the pressure sensor 29, and it is detected whether or not the low pressure side pressure is below the atmospheric pressure (step S11). ). The lowest refrigerant pressure in the refrigerant circuit is the low pressure side pressure in the suction pipe of the compressor 21. Therefore, the possibility of air mixing into the refrigerant circuit usually occurs after the low pressure side pressure becomes atmospheric pressure or lower.

Then, when the pressure on the low pressure side becomes equal to or lower than the atmospheric pressure (YES in step S11), the process proceeds to the next step S12. If the low pressure side pressure is equal to or higher than the atmospheric pressure, there is no possibility of air entering the refrigerant circuit, so the check whether the low pressure side pressure is equal to or lower than the atmospheric pressure is repeated as it is.

In the next step S12, in view of the possibility of air mixing in the refrigerant circuit, the air sensor 28 checks whether or not air mixing is detected in the suction side circuit of the compressor 21. In this embodiment, the detection of air contamination by the air sensor 28 is performed by determining whether or not oxygen is contained in the intake gas refrigerant. Then, when the air sensor 28 detects that air is mixed into the refrigerant circuit (YES in step S12), the operation of the compressor 21 is immediately stopped, the normal operation is forcibly terminated, and the safe operation control is performed. The control by the unit 33 is terminated.

The operation of detecting air contamination in the refrigerant circuit and the operation of coping with the detection of air contamination by the safe operation control unit 33 described above are started at the same time as the start of the refrigerating and air-conditioning operation. Then, it is performed in parallel with the control of the refrigerating and air-conditioning operation by the normal operation control unit 31. It should be noted that even when the pump-down operation controlled by the pump-down operation control unit 32 is started during the normal operation, it is configured to operate in parallel. Therefore, if air is detected by the air sensor 28 in this pump-down operation (YES in step S12), the operation of the compressor 21 is immediately stopped (step S13), and the normal operation is forcibly terminated. This completes the control by the safe operation control unit 33.

(Effect of Embodiment 1)
Since the air conditioner as the refrigerating and air-conditioning apparatus according to the first embodiment is configured as described above, the following effects can be obtained.

(1) According to this air conditioner, air contamination in the refrigerant circuit is detected when the low pressure side pressure of the compressor 21 is atmospheric pressure or less regardless of whether it is a normal refrigerating / air-conditioning operation or a pump-down operation. In that case, the operation of the compressor 21 is stopped, so that damage to the compressor 21 can be suppressed.

(2) Further, since the air sensor 28 is attached to the suction side circuit of the compressor 21, air contamination can be sensitively detected.
(3) Since the air sensor 28 is mounted around the pipe connecting the compressor 21 and the accumulator 26, it is easy to secure a mounting space for the air sensor 28.

(4) As a condition for detecting air contamination and stopping the compressor 21, in addition to detecting air contamination by the air sensor 28, the pressure sensor 29 adds that the low pressure side pressure is at least atmospheric pressure. Therefore, the possibility of erroneous detection is reduced as compared with the case where the detection of air contamination is performed only by the air sensor 28.

(Embodiment 2)
Next, the air conditioner as the refrigerating and air-conditioning apparatus according to the second embodiment will be described with reference to FIGS. 5 and 6.

The air conditioner according to the second embodiment has a detection operation for detecting air contamination in the refrigerant circuit and a countermeasure operation for detecting air contamination in the normal operation and the pump down operation. Is different. Compared with the case of the first embodiment, it is the same in the normal operation, but different in the pump down operation. This is because, during the pump down operation, the operation is performed until the low pressure side pressure becomes equal to or lower than the atmospheric pressure, so it is almost meaningless to add only the detection of the low pressure side pressure by the pressure sensor 29 as a condition. Therefore, in order to further increase the certainty, this air conditioner is designed to eliminate erroneous detection by confirming that the cumulative amount of air mixed in the refrigerant circuit exceeds a certain value.

As the configuration according to the second embodiment, the differences from the first embodiment will be described.
As shown in FIG. 5, the major difference is that the control device 30 is provided with the air mixing amount calculation unit 34. The air mixing amount calculation unit 34 calculates the amount of the refrigerant sucked into the compressor 21 in consideration of the changes in the rotation speed of the compressor 21 and the pressure on the low pressure side, and further, in the gas refrigerant sucked into the compressor 21. The air concentration calculated from the oxygen concentration is grasped including the change, and the cumulative amount of air mixed in the outdoor unit 2 is calculated based on this information. Therefore, in order to enable calculation in the air mixing amount calculation unit 34, information on the rotation speed of the compressor 21 and the low pressure side pressure of the refrigerant circuit is output from the pump down operation control unit 32 to the air mixing amount calculation unit 34. .. Further, in order to detect the oxygen concentration in the inhalation gas, an oxygen sensor as the air sensor 28 that can detect the oxygen concentration in the inhalation gas is used, and the oxygen concentration detected by the air sensor 28 is used for safe operation. It is output to the air mixing amount calculation unit 34 via the control unit 33.

Next, as the operation according to the second embodiment configured as described above, the operation of detecting air contamination in the refrigerant circuit and the operation of dealing with the detection of air contamination will be described in detail with reference to FIG.
As shown in FIG. 6, as in the case of the first embodiment, the low pressure side pressure in the suction pipe of the compressor 21 is monitored by the pressure sensor 29 at the same time as the start of the refrigerating and air conditioning operation, and the low pressure side pressure becomes lower than the atmospheric pressure. It is detected whether or not it has become (step S21).

Then, when the low pressure side pressure becomes equal to or lower than the atmospheric pressure (YES in step S21), the process proceeds to the next step S22. When the low pressure side pressure is equal to or higher than the atmospheric pressure (NO in step S21), the check whether the low pressure side pressure is equal to or lower than the atmospheric pressure is repeated.

In the next step S22, the air sensor 28 checks whether or not air contamination is detected in the suction side circuit of the compressor 21. In this embodiment, the detection of air contamination by the air sensor 28 determines whether or not oxygen is contained in the intake gas refrigerant, and also measures the oxygen concentration in the intake gas. If air contamination is not detected by the air sensor 28, the process returns to step S21, but if air contamination is detected (YES in step S22), the process proceeds to step S23 and the current operation is pumped down. It is judged whether it is driving or normal driving.

If it is determined in step S23 that the operation is normal, the compressor 21 is immediately stopped as in the case of the first embodiment (step S26). Therefore, when air contamination is detected in normal operation, it is substantially the same as that of the first embodiment. However, when it was determined in step S23 that the pump down operation was in progress, air was not mixed during the normal operation, but the pump down operation was started and the low pressure side pressure of the compressor 21 became lower than the atmospheric pressure. The pump down operation has progressed to a certain extent. In addition, air intrusion occurred after this state was reached. Here, considering that there is a possibility of erroneous detection in the case of only the air sensor 28, the rotation speed of the compressor 21, the low pressure side pressure of the compressor 21, and the oxygen concentration in the intake gas detected by the air sensor 28. , And the cumulative amount of air mixed in is calculated from the passage of time (step S24). Then, when the cumulative mixing amount exceeds a preset threshold value (YES in step S25), the operation of the compressor 21 is stopped (step S26). When the cumulative amount of air mixed does not exceed the preset threshold value, it is determined that there is no air mixed in an amount sufficient to damage the compressor 21, and the operation of the compressor 21 is continued as it is (step). If NO in S25).

(Effect of Embodiment 2)
Since the air conditioner as the refrigerating and air-conditioning apparatus according to the second embodiment is configured as described above, it can exert the following effects as well as the above-mentioned effects (2) and (3). can.

(5) If the low-pressure side pressure drops during normal operation and the air sensor 28 detects that air is mixed into the refrigerant circuit, the operation of the compressor 21 is immediately stopped, so that the compressor 21 is damaged. Can be suppressed. Further, the possibility of erroneous detection is reduced as compared with the case where the detection of air contamination is performed only by the air sensor 28.

(6) During the pump down operation, the pressure on the low pressure side drops, and when the air sensor 28 detects that air is mixed in the refrigerant circuit, the cumulative amount of air mixed in the refrigerant circuit is preset. When the specified threshold value is exceeded, it is considered that air has been mixed into the refrigerant circuit, and the operation of the compressor 21 is stopped, so that the risk of erroneous detection is reduced.

(Modification example)
The description of each of the above embodiments is an example of possible embodiments of the refrigerating and air-conditioning apparatus according to the present invention, and is not limited to the embodiments. It should be noted that a form in which at least two modifications that do not contradict each other may be combined may be used.

-In the first embodiment, it is possible to omit that the low pressure side pressure becomes atmospheric pressure or less as a condition for detecting air contamination in the refrigerant circuit. In this case, the detection operation of air contamination and the coping operation at the time of detecting air contamination omit the detection of the low pressure side pressure in step S11 in the procedure in the first embodiment shown in FIG. Just follow the steps. That is, as shown in FIG. 7, when the air sensor 28 detects the mixing of air into the refrigerant circuit (YES in step S12), the operation of the compressor 21 is immediately stopped (step S13), which is normal. The operation may be forcibly terminated. In this case, the attachment of the pressure sensor 29 itself may be omitted.

-In addition, in the second embodiment, it is possible to omit that the low pressure side pressure becomes atmospheric pressure or less as a condition for detecting air contamination in the refrigerant circuit. In this case, the air contamination detection operation and the coping operation at the time of air contamination detection omit the detection of the low pressure side pressure in step S21 in the procedure in the second embodiment shown in FIG. Just follow the steps. That is, as shown in FIG. 8, when the air sensor 28 detects the mixing of air into the refrigerant circuit (YES in step S22), it is determined whether the operation is pump-down operation or normal operation (step S23). ). If it is determined in step S23 that the operation is normal, the compressor 21 is immediately stopped (step S26). On the other hand, when it is determined in step S23 that the pump is down, the compressor 21 is operated when the cumulative amount of air mixed in the refrigerant circuit exceeds a preset threshold value (YES in step S25). Is stopped (step S26). In this case, the attachment of the pressure sensor 29 itself may be omitted.

-In the above embodiment, the oxygen sensor is used as the air sensor 28, but carbon dioxide or nitrogen gas, which is an air component, may be detected.
-In the first embodiment, the mounting position of the air sensor 28 is referred to as a low-pressure pipe connecting the four-way switching valve 22 and the accumulator 26, but if space allows, the accumulator 26 and the compressor 21 are used. It may be used as a suction pipe for connecting. This way, since the air mixing is detected at a position closer to the suction port of the compressor 21, it is possible to more accurately detect the air mixing in the refrigerant circuit.

-In the above embodiment, a separate type air conditioner is listed as a refrigerating device, but an integrated air conditioner, a cooling device for cooling the inside of a refrigerator, a freezing device for refrigerating the inside of a freezer, and lubricating oil for a machine tool are used. It may be a device that performs other types of refrigeration cycle application operation such as a cooling device for cooling.

L1 Liquid side communication pipe L2 Gas side communication pipe 1 Indoor unit 2 Outdoor unit 11 Indoor heat exchanger 12 Indoor fan 13 (as a decompression mechanism) Electric expansion valve 21 Compressor 22 Four-way switching valve 23 Outdoor heat exchanger 24 Liquid side Closing valve 25 Gas side closing valve 26 Accumulator 27 Outdoor fan 28 Air sensor 29 Pressure sensor 30 Control device 31 Normal operation control unit 32 Pump down operation control unit 33 Safe operation control unit 34 Air mixing amount calculation unit 35 Remote control 41 Outdoor heat exchanger Temperature sensor 42 Outside air temperature sensor 43 Indoor heat exchanger Temperature sensor 44 Indoor temperature sensor 45 Start / stop switch

Claims (7)

A refrigerant circuit having a compressor (21), an outdoor heat exchanger (23), a decompression mechanism, a liquid side closing valve (24), an indoor heat exchanger (11), and a gas side closing valve (25).
An air sensor (28) attached to the suction side circuit of the compressor (21) to detect the mixing of air into the refrigerant circuit, and
A safe operation control unit that controls the operation of the compressor (21) so as to stop the operation of the compressor (21) when the air sensor (28) detects the mixing of air into the refrigerant circuit. With (33) and the liquid side closing valve (24) closed and the gas side closing valve (25) open, the compressor (21) and the pressure reducing mechanism are controlled to perform a pump down operation. From the pump-down operation control unit (32) that performs the operation, and the air concentration in the refrigerant circuit measured by the air sensor (28) and the number of revolutions of the compressor (21) in the case of the pump-down operation. It is equipped with an air mixing amount calculation unit (34) that calculates the cumulative value of the mixed air amount in the refrigerant circuit .
The air sensor (28) detects air contamination based on the detection of air components in the refrigerant circuit, and detects air contamination .
The safe operation control unit (33) is configured to stop the operation of the compressor (21) in the case of normal refrigerating and air-conditioning operation when the air sensor (28) detects air contamination. In the case of the pump down operation, the operation of the compressor (21) is stopped when the air-conditioned air mixing amount calculation unit (34) calculates a mixed air amount equal to or higher than a preset threshold value.
Refrigeration and air conditioning equipment. The refrigerating and air-conditioning apparatus according to claim 1 further includes a pressure sensor (29) for detecting a low pressure side pressure.
The safe operation control unit (33) detects that the pressure sensor (29) is below atmospheric pressure, and when the air sensor (28) detects air contamination, the compressor is used in normal operation. The compressor (21) is configured to stop the operation of (21), and in the pump down operation, when the air mixing amount calculation unit (34) calculates the amount of mixed air equal to or higher than a preset threshold value. A refrigerating air conditioner that is configured to shut down. The refrigerant circuit has a four-way switching valve (22), and is formed so that the refrigerant flow direction can be reversibly switched by switching the four-way switching valve (22).
Claim 1 or claim that the air sensor (28) is attached to a suction pipe connecting an accumulator (26) attached to the suction side of the compressor (21) and the four-way switching valve (22). Item 2. The refrigerating and air-conditioning apparatus according to item 2. In the case of normal refrigeration and air conditioning operation, the safe operation control unit (33) is configured to immediately stop the operation of the compressor (21) when the air sensor (28) detects air contamination. The refrigerating and air-conditioning apparatus according to any one of claims 1 to 3. A refrigerant circuit having a compressor (21), an outdoor heat exchanger (23), a decompression mechanism, a liquid side closing valve (24), an indoor heat exchanger (11), and a gas side closing valve (25).
An air sensor (28) attached to the suction side circuit of the compressor (21) to detect the mixing of air into the refrigerant circuit, and
A safe operation control unit that controls the operation of the compressor (21) so as to stop the operation of the compressor (21) when the air sensor (28) detects the mixing of air into the refrigerant circuit. A refrigerating air conditioner provided with (33).
A pump-down operation in which the compressor (21) and the decompression mechanism are controlled to perform a pump-down operation while the liquid-side closing valve (24) is closed and the gas-side closing valve (25) is opened. In the case of the control unit (32) and the pump down operation, the air concentration in the refrigerant circuit measured by the air sensor (28) and the rotation speed of the compressor (21) are transferred into the refrigerant circuit. Further equipped with an air mixing amount calculation unit (34) for calculating the cumulative value of the mixed air amount,
The safe operation control unit (33) is configured to stop the operation of the compressor (21) in the case of normal refrigerating and air-conditioning operation when the air sensor (28) detects air contamination. In the case of the pump down operation, the refrigerating unit (34) is configured to stop the operation of the compressor (21) when the air-conditioned air amount calculation unit (34) calculates a mixed air amount equal to or higher than a preset threshold value. Air conditioner. The refrigerating and air-conditioning apparatus according to claim 5 further includes a pressure sensor (29) for detecting a low pressure side pressure.
The safe operation control unit (33) detects that the pressure sensor (29) is below atmospheric pressure, and when the air sensor (28) detects air contamination, the compressor is used in normal operation. The compressor (21) is configured to stop the operation of (21), and in the pump down operation, when the air mixing amount calculation unit (34) calculates the amount of mixed air equal to or higher than a preset threshold value. A refrigerating air conditioner that is configured to shut down. The refrigerant circuit has a four-way switching valve (22), and is formed so that the refrigerant flow direction can be reversibly switched by switching the four-way switching valve (22).
The air sensor (28) is attached to a suction pipe connecting the accumulator (26) attached to the suction side of the compressor (21) and the four-way switching valve (22).
The refrigerating and air-conditioning apparatus according to claim 5 or 6 .

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