JP7565481B2 - Air conditioners - Google Patents

Description

The present invention relates to a technology for preventing leakage of working refrigerant in air conditioners that use refrigeration and heat pump cycles for air conditioning.

In recent years, in addition to placing importance on the operating efficiency of air conditioners from the perspective of preventing global warming, there has been an accelerating movement to regulate the use of refrigerants with high global warming potential.

Refrigerants with low global warming potential include naturally occurring carbon dioxide, hydrocarbons such as propane and butane, and artificially synthesized fluorocarbons such as hydrofluoroolefins (HFOs), which have double bonds in their molecular structure and decompose in a short time in the atmosphere. HFOs such as 2,3,3,3-tetrafluoro-1-propene (R1234yf) and 1,3,3,3-tetrafluoro-1-propene (R1234ze) are attracting attention and some are already in practical use.

However, carbon dioxide has high operating pressures, making it difficult to operate efficiently when used in air conditioners, and it is difficult to say that it has excellent properties as a refrigerant.

In addition, R1234yf and R1234ze have high boiling points and large pressure losses, making them inefficient to use in separate air conditioners such as room air conditioners, and they are also slightly flammable, which is problematic when used in multi-air conditioners for buildings that use large amounts of refrigerant.

On the other hand, while hydrocarbons, especially propane, have excellent properties as refrigerants for air conditioners, they are highly flammable and therefore pose a risk of fire or explosion if the refrigerant leaks, so they cannot be easily used.

There have been many inventions to date that aim to improve the safety of separate-type air conditioners, such as room air conditioners and packaged air conditioners, that use flammable refrigerants.

One of these technologies is to collect flammable refrigerant in the outdoor unit to prevent it from leaking indoors. Preventing refrigerant leakage is a very important issue in terms of environmental impact, even with the currently used fluorocarbon gases, and refrigerant leakage from air conditioners must be avoided, regardless of whether the refrigerant is flammable or non-flammable.

The separated type air conditioner described in Patent Document 1 aims to prevent refrigerant consisting of flammable gas stored in the refrigerant circuit in the outdoor unit from leaking into the refrigerant circuit in the indoor unit when the air conditioner is stopped. To this end, actuators with built-in valves that operate based on differential pressure are provided on the refrigerant inlet and outlet sides of the indoor unit, and an on-off valve is installed in each of the pressure guiding pipes that lead the compressor discharge gas to each actuator.

Upon receiving a stop command, the on-off valve of the pressure piping connected to the actuator on the refrigerant inlet side of the indoor unit is closed to perform refrigerant recovery operation, and after the refrigerant in the indoor unit's refrigerant circuit is stored in the outdoor unit's refrigerant circuit, the on-off valve of the pressure piping connected to the actuator on the refrigerant outlet side of the indoor unit is closed to stop the compressor.

Figure 3 shows a first embodiment of the air conditioner described in Patent Document 1, in which an indoor unit 14 attached to a room 11 and an outdoor unit 10 are connected to form a refrigerant circuit. In the outdoor unit 10, the refrigerant is compressed by the compressor 1 to become a high-temperature, high-pressure gas refrigerant, which dissipates heat in the outdoor heat exchanger 2 and condenses to become a high-pressure liquid refrigerant. The pressure is reduced by the throttle 3 to become a two-phase gas-liquid refrigerant, which absorbs heat and evaporates in the indoor heat exchanger 4 of the indoor unit 14, and returns to the compressor 1 again.

An actuator 21 is provided on the inlet side of the indoor unit 14, and an actuator 22 is provided on the outlet side. The refrigerant discharged from the compressor 1 is supplied to the actuator 21 from the pressure guiding pipe 12 via the solenoid valve 15, and to the actuator 22 from the pressure guiding pipe 13 via the solenoid valve 16, so that the actuators 21 and 22 are in the open state.

When solenoid valve 15 or solenoid valve 16 is closed by command from controller 19, the supply of refrigerant discharged from compressor 1 stops, actuator 21 or actuator 22 is closed, and refrigerant does not flow in the refrigerant circuit of indoor unit 14.

When air conditioning is in operation, the controller 19 opens the solenoid valves 15 and 16, which opens the actuators 21 and 22, allowing the room 11 to be air-conditioned.

When stopping the air conditioning, the controller 19 first closes the solenoid valve 15 and closes the actuator 21 to start the refrigerant recovery operation. As the refrigerant recovery progresses and the suction side pressure of the compressor 1 drops, the pressure sensor 7 operates, and in response, the controller 19 closes the solenoid valve 16, closes the actuator 21, stops the compressor 1, and ends the refrigerant recovery operation.

In addition, a gas leak detection sensor 8 is installed in the room 11. When a gas leak detection signal is input to the controller 19 during air conditioning operation, the controller 19 outputs a stop command to perform refrigerant recovery operation, and a gas leak alarm is output at the same time that the compressor 1 stops.

In Patent Document 2, in order to reduce the cost of the equipment when performing a similar refrigerant recovery, the indoor unit's liquid side (cooling inlet side) and gas side (cooling outlet side) are shut off using an electromagnetic expansion valve for the liquid side and a shutoff valve for the gas side. The refrigerant recovery operation method is as follows: after the electromagnetic expansion valve is shut off, the compressor is operated for a specified time, the compressor is stopped, and the shutoff valve is shut off.

Japanese Unexamined Patent Publication No. 8-166171 JP 2000-97527 A

The conventional air conditioners described in Patent Documents 1 and 2 use a flammable refrigerant, and in order to avoid the risk of indoor fire or explosion, a refrigerant recovery operation is performed to remove the refrigerant from the indoor refrigerant circuit when operation is stopped or a refrigerant leak is detected.

The end of refrigerant recovery is determined when a drop in refrigerant pressure on the compressor suction side is detected in the case of Patent Document 1, and when a predetermined time has elapsed since the start of refrigerant recovery operation in the case of Patent Document 2.

However, when determining when refrigerant recovery is complete, depending on the operating conditions, there is a possibility that flammable refrigerant in the indoor refrigerant circuit may not be sufficiently removed, or that the pressure of the refrigerant on the suction side of the compressor may become negative, introducing air into the refrigerant circuit.

As a result, there is a risk that residual refrigerant may leak and ignite, or that the compressor may compress a mixture of flammable refrigerant or refrigeration oil and air, causing the outdoor unit to explode.

Therefore, the present invention aims to solve these problems and prevent refrigerant leakage by providing an air conditioner that performs a refrigerant recovery operation when the operation is stopped or when a refrigerant leak occurs, and provides a device that performs the refrigerant recovery operation appropriately and is safe and reliable.

In order to solve the above-mentioned problems, the air conditioner of the present invention is an air conditioner that constitutes a refrigeration or heat pump cycle with a compressor that compresses and sends out a working refrigerant, an outdoor unit having an outdoor heat exchanger that exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger that exchanges heat between the working refrigerant and indoor air sent by an indoor blower, and has a first refrigerant blocking means that blocks a first refrigerant path connecting the outdoor unit and the indoor unit, and a second refrigerant blocking means that blocks a second refrigerant path connecting the outdoor unit and the indoor unit. The system includes a second refrigerant shutoff means, a state detection means for acquiring information for estimating the state of the working refrigerant in the indoor unit, and a control means for controlling the operation of the device, including the operation of the first refrigerant shutoff means and the second refrigerant shutoff means. The state detection means includes at least two of a refrigerant temperature detection means, a refrigerant pressure detection means, an air temperature detection means, and a compressor power detection means. The control means determines the timing to close the second refrigerant shutoff means based on the output of the state detection means when recovering the working refrigerant to the outdoor unit during operation stoppage or working refrigerant leakage.

This allows the timing of closing the second refrigerant shutoff means to be appropriately determined, and the indoor unit can be stopped with an appropriate amount of working refrigerant remaining in the refrigerant circuit.

The air conditioner of the present invention can appropriately determine the timing to close the second refrigerant shutoff means and can shut down with an appropriate amount of working refrigerant remaining in the indoor unit's refrigerant circuit, so that even if a leak of working refrigerant occurs on the indoor unit side, the amount of leakage is kept to a minimum, air is drawn into the refrigerant circuit to prevent the compressor from exploding, and the piping connecting the indoor unit and outdoor unit is prevented from being deformed by even a slight external force, providing an air conditioner that is safe, reliable, and has a low environmental impact.

FIG. 1 is a configuration diagram of an air conditioner according to a first embodiment of the present invention. Flow diagram of refrigerant recovery from an air conditioner according to the first embodiment of the present invention. Diagram of a conventional air conditioner

The first invention is an air conditioner that forms a refrigeration or heat pump cycle with a compressor that compresses and sends out a working refrigerant, an outdoor unit having an outdoor heat exchanger that exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger that exchanges heat between the working refrigerant and indoor air sent by an indoor blower, and is equipped with a first refrigerant shutoff means that shuts off a first refrigerant path connecting the outdoor unit and the indoor unit, a second refrigerant shutoff means that shuts off a second refrigerant path connecting the outdoor unit and the indoor unit, a state detection means that acquires information for estimating the state of the working refrigerant in the indoor unit, and a control means that controls the operation of the device, including the operation of the first refrigerant shutoff means and the second refrigerant shutoff means, and the state detection means includes at least two or more of a refrigerant temperature detection means, a refrigerant pressure detection means, an air temperature detection means, and a compressor power detection means, and the control means determines the timing to close the second refrigerant shutoff means based on the output of the state detection means when recovering the working refrigerant to the outdoor unit during operation stoppage or working refrigerant leakage.

This allows the timing of closing the second refrigerant shutoff means to be appropriately determined, allowing an appropriate amount of working refrigerant to remain in the indoor unit's refrigerant circuit before shutting down.

As a result, even if a leak of working refrigerant occurs in the indoor unit, the amount of leakage is kept to a minimum, air is drawn into the refrigerant circuit, preventing the compressor from exploding, and preventing the pipes connecting the indoor and outdoor units from being deformed by even the slightest external force, providing a safe and reliable air conditioner.

The second invention is the first invention in which the refrigerant temperature detection means and the refrigerant pressure detection means are used as the state detection means, and the refrigerant temperature detection means and the refrigerant pressure detection means are both disposed on the indoor side of the refrigerant circuit that is cut off by the first refrigerant cut-off means and the second refrigerant cut-off means.

This allows the state of the working refrigerant in the indoor unit to be accurately estimated.

This allows for accurate determination of the amount of working refrigerant to remain in the indoor unit's refrigerant circuit.

The third invention is the first and second inventions, in which the control means controls the rotation speed of the compressor in response to the output of the refrigerant pressure detection means.

This allows the recovery speed of the working refrigerant to be slowed down near the end of the refrigerant recovery operation, improving the accuracy of determining when to shut off.

This improves the reproducibility of the amount of working refrigerant remaining in the indoor unit's refrigerant circuit.

The fourth invention is the first, second, and third inventions, in which the working refrigerant is a flammable refrigerant.

This will help minimize the destruction of the ozone layer and the impact on global warming.

This makes it possible to provide an air conditioner that is safe and has a low environmental impact.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a configuration diagram of an air conditioner according to a first embodiment of the present invention.

As shown in FIG. 1, the air conditioner in the first embodiment is a device that performs cooling or heating by circulating a working refrigerant through a ring-shaped connection between an outdoor unit 101 and an indoor unit 107 connected by piping.

Figure 2 is a flow chart showing an outline of the control when an air conditioner in embodiment 1 of the present invention performs refrigerant recovery.

The outdoor unit 101 is equipped with a compressor 102 that compresses the working refrigerant, a four-way valve 103 that switches the flow of the working refrigerant discharged from the compressor 102, an outdoor heat exchanger 104 that exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower 105, and an expansion valve 106 that reduces the pressure of the high-pressure working refrigerant and expands it. Incidentally, the compressor 102 is an inverter-driven compressor, and its operating speed can be changed depending on the situation.

The indoor unit 107 is equipped with an indoor heat exchanger 108 that exchanges heat between the indoor air sent by the indoor blower 109 and the working refrigerant, and performs cooling and heating to keep the room comfortable.

There are no particular limitations on the working refrigerant that can be used, and any working refrigerant that can be used to create a refrigeration or heat pump using a compressor by utilizing the heat absorption and release that accompanies a phase change can be used.

The indoor unit 107 is connected to the outdoor unit 101 via a liquid side connection port 110 and a gas side connection port 111, forming a basic refrigerant circuit. In addition, to provide comfortable air conditioning and smooth operation, a room temperature sensor 116, an indoor refrigerant temperature sensor 117, an outside air temperature sensor 118, a compressor power sensor 119, and a control device 120 as a control means are provided.

The control device 120 receives the outputs of all the sensors and outputs operation commands to all the operating elements. In FIG. 1, the sensor outputs 123 and operation commands 124 are shown by arrows, and individual correspondence is omitted. The control means can control, for example, the liquid side shutoff valve 112, the gas side shutoff valve 113, and the compressor 102.

The air conditioner in FIG. 1 has a state detection means, and the state detection means may be any detection means for estimating the state of the working refrigerant in the indoor unit, such as a refrigerant temperature detection means, a refrigerant pressure detection means, an air temperature detection means, and a compressor power detection means, and preferably, at least two or more of these are installed. The refrigerant temperature detection means is a means for detecting the temperature of the working refrigerant flowing through the refrigerant circuit, and in FIG. 1, this corresponds to the refrigerant temperature sensor 114 and the indoor refrigerant temperature sensor 117. The refrigerant pressure detection means is a means for detecting the pressure of the working refrigerant in the refrigerant circuit, and in FIG. 1, this corresponds to the pressure sensor 115. The air temperature detection means is a means for detecting the ambient temperature of the outdoor unit 101 and the indoor unit 107, and in FIG. 1, this corresponds to the outdoor air temperature sensor 118 and the room temperature sensor 116. The compressor power detection means is a means for detecting the power consumption of the compressor 102, and in FIG. 1, this corresponds to the compressor power sensor 119.

Furthermore, the air conditioner of FIG. 1 appropriately performs refrigerant recovery operation when operation is stopped, for example, when operation is terminated or when working refrigerant leaks, in order to minimize leakage of the working refrigerant and improve safety and reduce the environmental load. For this purpose, a refrigerant shutoff means is provided, and a liquid side shutoff valve 112 is arranged as a first refrigerant shutoff means between the expansion valve 106 and the liquid side connection port 110, which is the first refrigerant path, and a refrigerant temperature sensor 114 is arranged between the liquid side shutoff valve 112 and the liquid side connection port 110. In addition, a gas side shutoff valve 113 is arranged as a second refrigerant shutoff means between the gas side connection port 111 and the four-way valve 103, which is the second refrigerant path, and a pressure sensor 115 is arranged between the gas side connection port 111 and the gas side shutoff valve 113, and a refrigerant sensor 125 is arranged in the indoor unit 107.

In FIG. 1, the four-way valve 103 is in a cooling operation, defrosting operation, or refrigerant recovery operation state, and the working refrigerant discharged from the compressor 102 flows from the four-way valve 103 to the outdoor heat exchanger 104, and then to the expansion valve 106, the liquid-side shutoff valve 112, the liquid-side connection port 110, and the indoor heat exchanger 108, forming a refrigeration cycle.

During heating operation, the working refrigerant discharged from the compressor 102 flows from the four-way valve 103 through the gas side shutoff valve 113 and the gas side connection port 111 to the indoor heat exchanger 108, and then through the liquid side connection port 110, the liquid side shutoff valve 112, and the outdoor heat exchanger 104, forming a heat pump cycle.

In order to use the compressor 102 to recover the working refrigerant to the outdoor unit 101, it is necessary to configure and operate a refrigeration cycle.

As shown in FIG. 2, when a refrigerant recovery operation is instructed by the control device 120, the rotation speed of the compressor 102 is set to a predetermined value and the refrigerant recovery operation is performed. During heating operation, the operation is stopped once, and then the setting of the four-way valve 103 is set to the same as during cooling operation to start the refrigerant recovery operation. During cooling operation, defrosting operation, or other operation in a refrigeration cycle in which the refrigerant flows from the compressor 102 through the outdoor heat exchanger 104 to the indoor heat exchanger 108 in that order, the refrigerant recovery operation is continued continuously without being stopped.

When the liquid-side shutoff valve 112 is closed after a certain time has elapsed since the transition to refrigerant recovery operation, the supply of working refrigerant to the refrigerant circuit of the indoor unit 107 stops and the compressor 102 continues to operate, so that the working refrigerant in the refrigerant circuit of the indoor unit 107 is sucked in and recovered into the refrigerant circuit of the outdoor unit 101, most of which is condensed and stored in the outdoor heat exchanger 104.

As the refrigerant recovery operation progresses, the output of the pressure sensor 115 decreases, and the outputs of the refrigerant temperature sensor 114 and the indoor refrigerant temperature sensor 117 also decrease, but when the liquid refrigerant in the detection section runs out, they begin to increase, and slowly rise up to the ambient temperature as an upper limit.

The change in output of the refrigerant temperature sensor 114 and the indoor refrigerant temperature sensor 117 progresses faster for the indoor refrigerant temperature sensor 117, reaching its minimum value first and then beginning to rise. The refrigerant temperature sensor 114 is the furthest from the intake port of the compressor 102, and its output change reaches its minimum value last.

The output of the pressure sensor 115 alone can detect a drop in pressure, but the amount of liquid refrigerant remaining in the refrigerant circuit of the indoor unit 107 is not necessarily the same depending on the installation condition, room temperature, etc.

It is difficult to judge based on just one sensor output from the refrigerant temperature sensor 114 or the indoor refrigerant temperature sensor 117, and even if it is judged based on the output value of the indoor refrigerant temperature sensor 117, it is difficult to judge how much liquid refrigerant remains between the liquid side connection pipe 121 and the liquid side shutoff valve 112, depending on the installation state of the liquid side connection pipe 121 and the operating conditions. If it is judged based only on the output of the refrigerant temperature sensor 114, there is a high possibility that the refrigerant circuit of the indoor unit 107 will become negative pressure if the minimum output value is not confirmed.

If a large amount of liquid refrigerant remains, there is a risk of it catching fire if it leaks. Conversely, if negative pressure is created inside the refrigerant circuit, air may get mixed in, causing a diesel explosion inside the compressor 102, oxygen and moisture may have a negative effect on the reliability of the device, and there is a risk that the liquid side connection pipe 121 or gas side connection pipe 122, which are now under negative pressure, may easily become deformed if external force is applied to them due to some kind of work.

Therefore, by determining the timing to end refrigerant recovery based on a comprehensive assessment of multiple sensor outputs rather than determining the timing based on the output of a single sensor, the amount of refrigerant remaining in the refrigerant circuit of the indoor unit 107 can be accurately controlled.

In addition, in the first embodiment, the compressor 102 is provided with a compressor power sensor 119, and as the refrigerant recovery operation progresses, the output of the compressor power sensor 119 decreases even if the rotation speed of the compressor 102 is constant. Although the compressor power sensor 119 is less accurate, it is often installed for protection and control of the compressor 102, and can be constructed at low cost.

In addition, even if the pressure sensor 115 is used, if a malfunction occurs in the pressure sensor 115, the compressor power sensor 119 can take over, providing high reliability.

Here we will explain sensor combinations and examples of refrigerant recovery operations.

First, a basic combination would be a pressure sensor 115 as a refrigerant pressure detection means and a refrigerant temperature sensor 114 or an indoor refrigerant temperature sensor 117 as a refrigerant temperature detection means.

After the refrigerant recovery operation starts, the output of the pressure sensor 115 gradually decreases. At this time, the refrigerant recovery operation is basically terminated by reducing the liquid refrigerant in the refrigerant circuit in the indoor unit 107 as much as possible before the output of the pressure sensor 115 becomes negative pressure.

As the refrigerant recovery operation progresses, the output of the pressure sensor 115 decreases, and the output of the refrigerant temperature sensor 114 or the indoor refrigerant temperature sensor 117 also decreases. Before the output of the pressure sensor 115 becomes negative pressure, when the output of the refrigerant temperature sensor 114 or the indoor refrigerant temperature sensor 117 starts to rise and the output of the pressure sensor 115 reaches a predetermined value, the refrigerant recovery is terminated, the gas side shutoff valve 113 is closed, and the compressor 102, the outdoor blower 105, and the indoor blower 109 are stopped.

From the viewpoint of performing refrigerant recovery with high accuracy, the refrigerant temperature sensor 114 is superior to the indoor refrigerant temperature sensor 117, but the indoor refrigerant temperature sensor 117 can be substituted with a pipe temperature sensor that is generally installed for the purpose of controlling the air conditioner, and in many cases, this can prevent an increase in costs.

In addition, if the compressor power sensor 119 is used as the compressor power detection means instead of the pressure sensor 115, the detection accuracy of the refrigerant pressure will decrease, but in compressors that use DC brushless motors, the current value is used for control, and detection is possible without incurring special costs, so increases in costs can be suppressed.

Immediately after the start of the refrigerant recovery operation, when the refrigerant recovery to the outdoor unit 101 has not yet progressed and the pressure of the refrigerant sucked into the compressor 102 is high, the power of the compressor 102 is also high. However, as the refrigerant recovery progresses and the pressure of the refrigerant sucked into the compressor 102 decreases, the power of the compressor also decreases. Therefore, it is possible to replace the output of the pressure sensor 115 with the output of the compressor power sensor 119, and the progress of the refrigerant recovery can be estimated in a similar manner.

In addition, it is possible to perform appropriate refrigerant recovery operation by using the pressure sensor 115 or the compressor power sensor 119, the room temperature sensor 116 and the outside air temperature sensor 118 as air temperature detection means, and the refrigerant temperature sensor 114 or the indoor refrigerant temperature sensor 117.

By using the outputs of the room temperature sensor 116 and the outside air temperature sensor 118, in combination with the rotation speed of the compressor 102, the temperature of the working refrigerant in the outdoor room can be estimated, and the power consumption of the compressor 102 can be estimated.

When the air conditioner is operating normally, the output value of the compressor power sensor 119 roughly matches the estimated power consumption, but if the refrigerant circulation stops or heat exchange with the indoor or outdoor air is hindered, a large discrepancy will occur.

When refrigerant is being recovered, the circulation of the refrigerant stops at the liquid side shutoff valve 112, so as refrigerant recovery progresses, the output value of the compressor power sensor 119 decreases and becomes smaller than the estimated value.

By comparing this estimated power consumption of the compressor 102 with the output value of the compressor power sensor 119, the progress of refrigerant recovery can be estimated more accurately.

Here, if the shape of the mounting parts of the indoor refrigerant temperature sensor 117 and the refrigerant temperature sensor 114 is, for example, shaped so that it falls vertically and then rises vertically again, making it easier for liquid refrigerant to accumulate, the completion of evaporation of the liquid refrigerant can be detected more accurately.

In addition, for the purpose of recovering refrigerant accurately, the refrigerant temperature sensor 114 and the pressure sensor 115 are preferably arranged on the indoor unit 107 side of the refrigerant circuit that is cut off by the liquid side shutoff valve 112 as the first refrigerant shutoff means and the gas side shutoff valve 113 as the second refrigerant shutoff means. The refrigerant temperature sensor 114 is installed where the liquid refrigerant remains until the end, that is, between the liquid side connection port 110 and the liquid side shutoff valve 112, so that the moment when the last liquid refrigerant evaporates can be captured. The pressure sensor 115 can be installed on the refrigerant circuit side of the indoor unit 107, between the gas side connection port 111 and the gas side shutoff valve 113, which is closest to the suction port of the compressor 102, to detect the minimum pressure.

In other words, refrigerant recovery can be performed most accurately by placing the refrigerant temperature sensor 114 and pressure sensor 115 in the positions shown in Figure 1.

In addition, when considering the rotation speed of the compressor 102 during refrigerant recovery, if the rotation speed is high, it is possible to complete the refrigerant recovery operation in a short time, but even if the timing of the refrigerant recovery end command is slightly off from the appropriate end timing, the remaining amount of working refrigerant in the refrigerant circuit on the indoor unit 107 side will vary greatly.

On the other hand, if the rotation speed is low, the working refrigerant is recovered slowly, so the timing of the refrigerant recovery end command is less likely to deviate from the appropriate end timing, making it easier to maintain an appropriate amount of working refrigerant remaining in the refrigerant circuit on the indoor unit 107 side, but this is undesirable as it takes a long time to recover the refrigerant.

Therefore, an appropriate rotation speed that is neither high nor low may be set. Preferably, the compressor 102 is driven at a high rotation speed when the refrigerant recovery operation starts, and as the refrigerant recovery progresses and the operation nears its end, the rotation speed is reduced. This makes it easy to keep the remaining amount of working refrigerant in the refrigerant circuit on the indoor unit 107 side appropriate while minimizing the time required for the refrigerant recovery operation.

The air conditioner shown in embodiment 1 in Figure 1 is capable of minimizing leakage of the working refrigerant and preventing air intake, improving safety and reducing the environmental impact, regardless of the working refrigerant used. However, when using flammable refrigerants such as R32, R1234yf, R1234ze, or hydrocarbons such as propane or butane, it is highly effective in preventing ignition and other hazards.

Among these, propane not only has a small impact on global warming, but also has excellent performance as a refrigerant, making the present invention extremely significant in that it can reduce the risk of fire.

As described above, the air conditioner of the present invention prevents refrigerant leakage in an air conditioner that uses refrigeration and a heat pump cycle for air conditioning, and the technology is not limited to air conditioners, but can also be widely applied and effective in water heaters, showcases, freezers, etc.

REFERENCE SIGNS LIST 101 Outdoor unit 102 Compressor 103 Four-way valve 104 Outdoor heat exchanger 105 Outdoor blower 106 Expansion valve 107 Indoor unit 108 Indoor heat exchanger 109 Indoor blower 110 Liquid side connection port 111 Gas side connection port 112 Liquid side shutoff valve 113 Gas side shutoff valve 114 Refrigerant temperature sensor 115 Pressure sensor 116 Room temperature sensor 117 Indoor refrigerant temperature sensor 118 Outdoor air temperature sensor 119 Compressor power sensor 120 Control device 121 Liquid side connection pipe 122 Gas side connection pipe 123 Sensor output 124 Operation command

Claims (3)

an outdoor unit having a compressor that compresses and delivers a working refrigerant, and an outdoor heat exchanger that exchanges heat between outdoor air sent by an outdoor blower and the working refrigerant;
an indoor unit having an indoor heat exchanger that exchanges heat between indoor air sent by an indoor blower and the working refrigerant;
An air conditioner that constitutes a refrigeration or heat pump cycle,
a first refrigerant blocking means for blocking a first refrigerant path connecting the outdoor unit and the indoor unit;
a second refrigerant blocking means for blocking a second refrigerant path connecting the outdoor unit and the indoor unit;
A state detection means for acquiring information for estimating a state of the working refrigerant of the indoor unit;
A control means for controlling the operation of the device including the operation of the first refrigerant shutoff means and the second refrigerant shutoff means,
The state detection means includes at least two of a refrigerant temperature detection means, a refrigerant pressure detection means, an air temperature detection means, and a compressor power detection means,
the refrigerant temperature detection means and the refrigerant pressure detection means are disposed on the indoor side of the refrigerant circuit cut off by the first refrigerant cutoff means and the second refrigerant cutoff means,
the control means, when recovering the working refrigerant to the outdoor unit upon operation shutdown or leakage of the working refrigerant, determines the timing to close the second refrigerant cutoff means based on an output of the refrigerant pressure detection means or the compressor power detection means of the status detection means and an output of the refrigerant temperature detection means or the air temperature detection means of the status detection means ;
the control means, when determining the timing to close the second refrigerant cutoff means based on the output of the refrigerant pressure detection means of the state detection means and the output of the refrigerant temperature detection means of the state detection means, determines the timing to close the second refrigerant cutoff means based on the output of the refrigerant temperature detection means turning to an increase before the output of the refrigerant pressure detection means becomes negative pressure;
The air conditioner characterized in that, when determining when to close the second refrigerant shutoff means based on the output of the compressor power detection means of the status detection means and the output of the refrigerant temperature detection means or the air temperature detection means of the status detection means, the control means estimates the indoor and outdoor refrigerant temperatures based on the output of the refrigerant temperature detection means or the air temperature detection means, estimates the power consumption of the compressor based on the estimated indoor and outdoor refrigerant temperatures, and determines the time to close the second refrigerant shutoff means by comparing the estimated power consumption of the compressor with an output value of the compressor power detection means . The air conditioner according to claim 1, characterized in that the control means controls the rotation speed of the compressor according to the output of the refrigerant pressure detection means. An air conditioner according to claim 1 or 2, characterized in that the working refrigerant is a flammable refrigerant.