Patent Description:
In Patent Literature <NUM>, various measures are taken to increase a refrigerant recovery speed during a refrigerant recovery operation for recovering a refrigerant in an air conditioner. Specifically, an indoor fan and an outdoor fan are driven in a state where all valves of a refrigerant circuit are fully opened, and a temperature of a compressor is increased by energizing a crankcase heater or heating a motor. Patent Literature <NUM> discloses a refrigerant recovery system including a refrigerant recovery apparatus and a refrigerant recovery container that are connected to a target apparatus, such as an air conditioner, to recover a refrigerant from the target apparatus to the refrigerant recovery container. The target apparatus includes a liquid-side service port and a gas-side service port both of which are connected to a gauge manifold which in turn is connected to the refrigerant recovery apparatus.

There are two timings for recovering a refrigerant of an air conditioner, that is, at a time of disposal of the air conditioner and at a time of service for adding or moving an indoor unit. However, in Patent Literature <NUM>, the refrigerant recovery operation is performed by the same control method at any of the two timings.

An object of the present invention is to provide a refrigerant recovery control device and a refrigerant recovery control system capable of performing a refrigerant recovery operation according to a timing of recovering a refrigerant.

The refrigerant recovery control device according to the invention can selectively use the first control mode and the second control mode in which the flow rate of the refrigerant in the refrigerant circuit is different during the refrigerant recovery operation for recovering the refrigerant in the refrigerant circuit in the refrigeration apparatus, and thus can perform the refrigerant recovery operation in accordance with a timing of recovering the refrigerant.

(<NUM>) A rotational speed of a compressor that compresses and discharges the refrigerant in the refrigerant circuit in the first control mode is preferably higher than a rotational speed of the compressor in the second control mode.

In this case, in the first control mode, since the rotational speed of the compressor is higher than in the second control mode, the flow rate of the refrigerant in the refrigerant circuit can be easily made larger than in the second control mode.

(<NUM>) An opening degree of a valve (<NUM>) that is adjustable of the flow rate of the refrigerant in the refrigerant circuit (<NUM>) in the first control mode is preferably larger than an opening degree of the valve (<NUM>) in the second control mode.

In this case, in the first control mode, since the opening degree of the valve is larger than in the second control mode, the flow rate of the refrigerant in the refrigerant circuit can be easily made larger than in the second control mode.

(<NUM>) The first control mode is preferably used in a case where the refrigeration apparatus is discarded, and the second control mode is preferably used in a case where the refrigeration apparatus is continuously used after the refrigerant is recovered.

When the refrigerant is recovered at a time of discarding the refrigeration apparatus, there is no problem even if some damage is given to the refrigeration apparatus. Thus, in the first control mode, the flow rate of the refrigerant in the refrigerant circuit can be made larger than in the second control mode. As a result, refrigerant recovery time can be reduced. In a case where the refrigeration apparatus is continuously used after the refrigerant is recovered, the flow rate of the refrigerant in the refrigerant circuit can be made smaller in the second control mode during the refrigerant recovery than in the first control mode. As a result, the damage to the refrigeration apparatus can be suppressed.

(<NUM>) In the first control mode, a pressure of the refrigerant sucked into the compressor is preferably close to a predetermined protection lower limit value, or a pressure of the refrigerant discharged from the compressor is preferably close to a predetermined protection upper limit value.

In this case, when the refrigerant is recovered in the first control mode, the pressure of the refrigerant sucked into the compressor becomes a value close to the protection lower limit value, or the pressure of the refrigerant discharged from the compressor becomes a value close to the protection upper limit value. Thus, the flow rate of the refrigerant in the refrigerant circuit can be increased as much as possible. As a result, the refrigerant recovery time can be reduced as much as possible.

(<NUM>) The compressor preferably includes a drooping lower limit value that is a lower limit value of a first pressure of the refrigerant sucked into the compressor and a drooping upper limit value that is an upper limit value of a second pressure of the refrigerant discharged from the compressor during a normal operation of the refrigeration apparatus, and a protection lower limit value that is an allowable lower limit value of the first pressure and a protection upper limit value that is an allowable upper limit value of the second pressure against damage to the compressor, in the first control mode, preferably, the first pressure becomes a value close to the protection lower limit value, or the second pressure becomes a value close to the protection upper limit value, and in the second control mode, preferably, the first pressure is higher than or equal to the drooping lower limit value, and the second pressure is lower than or equal to the drooping upper limit value.

When the refrigerant is recovered in the second control mode, the pressure of the refrigerant sucked into the compressor becomes higher than or equal to the drooping lower limit value, and the pressure of the refrigerant discharged from the compressor becomes lower than or equal to the drooping upper limit value. Therefore, the refrigerant can be recovered while suppressing damage to the compressor.

(<NUM>) A refrigerant recovery control system of the present disclosure includes a refrigeration apparatus that performs a refrigerant recovery operation for recovering a refrigerant in a refrigerant circuit, and a control unit having a first control mode and a second control mode different from each other as control modes of the refrigerant recovery operation, in which the refrigerant in the refrigerant circuit in the first control mode has a flow rate that is larger than a flow rate of the refrigerant in the refrigerant circuit in the second control mode.

The refrigerant recovery control system configured as described above can selectively use the first control mode and the second control mode in which the flow rate of the refrigerant in the refrigerant circuit is different during the refrigerant recovery operation for recovering the refrigerant in the refrigerant circuit in the refrigeration apparatus, and thus can perform the refrigerant recovery operation in accordance with a timing of recovering the refrigerant.

<FIG> is a schematic configuration diagram of an air conditioner according to the embodiment. An air conditioner <NUM> as a refrigeration apparatus is an apparatus that cools and heats the inside of a room in a large building by a vapor compression refrigeration cycle. The air conditioner <NUM> includes an outdoor unit <NUM>, a plurality of (here, four) indoor units <NUM> connected in parallel to each other, a liquid-refrigerant connection pipe <NUM>, and a gas-refrigerant connection pipe <NUM>. The air conditioner <NUM> may include an intermediate unit that switches a flow of a refrigerant between the outdoor unit <NUM> and the plurality of indoor units <NUM>. In this case, the intermediate unit may be installed outside the building, or may be installed in a machine chamber or the like of the building.

The outdoor unit <NUM> and the indoor units <NUM> are connected via the liquid-refrigerant connection pipe <NUM> and the gas-refrigerant connection pipe <NUM>. This configures a vapor compression refrigerant circuit <NUM> of the air conditioner <NUM>. The refrigerant circuit <NUM> is filled with a refrigerant such as R32, CO<NUM>, or HFO.

The outdoor unit <NUM> is installed outside of the building and constitutes part of the refrigerant circuit <NUM>. The outdoor unit <NUM> includes a compressor <NUM>, an outdoor heat exchanger <NUM>, a four-way switching valve <NUM>, an outdoor fan <NUM>, an outdoor expansion valve <NUM>, an accumulator <NUM>, a liquid-side shutoff valve <NUM>, and a gas-side shutoff valve <NUM>. The devices <NUM> to <NUM> and the valves <NUM> and <NUM> are connected by refrigerant pipes <NUM> to <NUM>.

The compressor <NUM> can change the number of operating rotations of a built-in motor (not shown) (a rotational speed of the compressor <NUM>) by inverter control of the motor. The outdoor heat exchanger <NUM> is, for example, a cross fin tube type heat exchanger, and is used for exchanging heat with the refrigerant by using air as a heat source.

The outdoor fan <NUM> includes a motor (not shown) whose number of operating rotations is adjustable by inverter control. The outdoor fan <NUM> is configured to take in outdoor air into the outdoor unit <NUM>, exchange heat between the taken-in air and the outdoor heat exchanger <NUM>, and then blow the air out of the outdoor unit <NUM>.

The four-way switching valve <NUM> reverses a flow of the refrigerant in the refrigerant circuit <NUM>, and supplies the refrigerant discharged from the compressor <NUM> by switching between the outdoor heat exchanger <NUM> and the indoor heat exchanger <NUM> (described later). The accumulator <NUM> temporarily stores the refrigerant sucked into the compressor <NUM>. The liquid-side shutoff valve <NUM> and the gas-side shutoff valve <NUM> are electric valves whose opening degrees are manually adjustable. The operations of the compressor <NUM>, the four-way switching valve <NUM>, the outdoor fan <NUM>, the outdoor expansion valve <NUM>, the liquid-side shutoff valve <NUM>, and the gas-side shutoff valve <NUM> are controlled by an outdoor control unit <NUM> (described later).

The outdoor unit <NUM> further includes a discharge pressure sensor <NUM>, a discharge temperature sensor <NUM>, a suction pressure sensor <NUM>, and a suction temperature sensor <NUM>.

The discharge pressure sensor <NUM> detects a pressure of the refrigerant discharged from the compressor <NUM>. The discharge temperature sensor <NUM> detects a temperature of the refrigerant discharged from the compressor <NUM>. The suction pressure sensor <NUM> detects a pressure of the refrigerant sucked into the compressor <NUM>. The suction temperature sensor <NUM> detects a temperature of the refrigerant sucked into the compressor <NUM>.

Signals detected by the sensors <NUM> to <NUM> are input to the outdoor control unit <NUM> (see <FIG>). The operations of the compressor <NUM>, the outdoor fan <NUM>, and the outdoor expansion valve <NUM> are controlled by the outdoor control unit <NUM> in accordance with output of the sensors <NUM> to <NUM>.

The indoor units <NUM> are installed inside of the building and constitute part of the refrigerant circuit <NUM>. Each of the indoor units <NUM> includes an indoor expansion valve <NUM>, an indoor heat exchanger <NUM>, and an indoor fan <NUM>.

As the indoor expansion valve <NUM>, an electric expansion valve capable of adjusting a refrigerant pressure and a flow rate of the refrigerant is used. The indoor heat exchanger <NUM> is, for example, a cross fin tube type heat exchanger, and is used for exchanging heat with indoor air.

The indoor fan <NUM> includes a motor (not shown) whose number of operating rotations is adjustable by inverter control. The indoor fan <NUM> is configured to take indoor air into the indoor unit <NUM>, exchange heat between the taken-in air and the indoor heat exchanger <NUM>, and then blow the air into the room. The opening degree of the indoor expansion valve <NUM> and the driving of the indoor fan <NUM> are controlled by an indoor control unit <NUM> (described later) (see <FIG>).

The liquid-refrigerant connection pipe <NUM> has one end that is connected to the liquid-side shutoff valve <NUM> of the outdoor unit <NUM> and the other end that is connected to a liquid side of the indoor expansion valves <NUM> of the indoor units <NUM>. The gas-refrigerant connection pipe <NUM> has one end that is connected to the gas-side shutoff valve <NUM> of the outdoor unit <NUM> and the other end that is connected to a gas side of the indoor heat exchangers <NUM> of the indoor units <NUM>.

<FIG> is a block diagram illustrating an example of internal configurations of the outdoor unit <NUM> and the indoor unit <NUM>.

The indoor unit <NUM> includes the indoor control unit <NUM> and a communication unit <NUM>. The communication unit <NUM> includes a communication interface, and transmits and receives various information to and from the outdoor control unit <NUM>. The indoor control unit <NUM> is a microcomputer including a CPU, a memory, and the like. The indoor control unit <NUM> controls the indoor expansion valve <NUM> and the indoor fan <NUM> on the basis of a command from the outdoor control unit <NUM>.

The outdoor unit <NUM> includes the outdoor control unit <NUM>, a communication unit <NUM>, and an input unit <NUM>.

The communication unit <NUM> includes a communication interface, and transmits and receives various information to and from the communication unit <NUM> of the indoor unit <NUM>. The input unit <NUM> includes, for example, a dip switch or the like provided on a substrate, and performs an operation on the outdoor unit <NUM>, setting of a control mode of a refrigerant recovery operation (described later), and the like.

The outdoor control unit <NUM> is a microcomputer including a CPU, a memory, and the like. The outdoor control unit <NUM> controls the operation of the air conditioner <NUM> as a whole by controlling various components of the outdoor unit <NUM> and the indoor unit <NUM> on the basis of detection signals and the like of the sensors as described above. The outdoor control unit <NUM> performs cooling operation control for controlling a cooling operation, heating operation control for controlling a heating operation, and refrigerant recovery operation control for controlling the refrigerant recovery operation. In the present embodiment, the outdoor control unit <NUM>, the communication unit <NUM>, and the input unit <NUM> constitute a refrigerant recovery control device that controls the refrigerant recovery operation of the air conditioner <NUM>.

In the cooling operation control, the outdoor heat exchanger <NUM> acts as an evaporator, and the indoor heat exchanger <NUM> acts as a condenser. Specifically, the outdoor control unit <NUM> switches the four-way switching valve <NUM> to an outdoor heat radiation state (a state indicated by a solid line in <FIG>), and opens the liquid-side shutoff valve <NUM> and the gas-side shutoff valve <NUM>. The outdoor control unit <NUM> then drives the compressor <NUM> and the outdoor fan <NUM>, and outputs a command to drive the indoor fan <NUM> to the indoor control unit <NUM>.

A high-pressure refrigerant discharged from the compressor <NUM> flows out of the outdoor unit <NUM> through the four-way switching valve <NUM>, the outdoor heat exchanger <NUM>, the outdoor expansion valve <NUM>, and the liquid-side shutoff valve <NUM>. The refrigerant flowing out of the outdoor unit <NUM> is branched and sent to the plurality of indoor units <NUM> through the liquid-refrigerant connection pipe <NUM>. Then, the refrigerant merges and is sent to the outdoor unit <NUM> through the indoor expansion valve <NUM>, the indoor heat exchanger <NUM>, and the gas-refrigerant connection pipe <NUM> of each indoor unit <NUM>. Thereafter, the refrigerant is sucked into the compressor <NUM> through the gas-side shutoff valve <NUM>, the four-way switching valve <NUM>, and the accumulator <NUM>.

In the heating operation control, the outdoor heat exchanger <NUM> acts as a condenser, and the indoor heat exchanger <NUM> acts as an evaporator. Specifically, the outdoor control unit <NUM> switches the four-way switching valve <NUM> to an outdoor heat evaporation state (a state indicated by a broken line in <FIG>), and opens the liquid-side shutoff valve <NUM> and the gas-side shutoff valve <NUM>. The outdoor control unit <NUM> then drives the compressor <NUM> and the outdoor fan <NUM>, and outputs a command to drive the indoor fan <NUM> to the indoor control unit <NUM>.

A high-pressure refrigerant discharged from the compressor <NUM> flows out of the outdoor unit <NUM> through the four-way switching valve <NUM> and the gas-side shutoff valve <NUM>. The refrigerant flowing out of the outdoor unit <NUM> is branched and sent to the plurality of indoor units <NUM> through the gas-refrigerant connection pipe <NUM>. Then, the refrigerant merges and is sent to the outdoor unit <NUM> through the indoor heat exchanger <NUM>, the indoor expansion valve <NUM>, and the liquid-refrigerant connection pipe <NUM> of each indoor unit <NUM>. Thereafter, the refrigerant is sucked into the compressor <NUM> through the liquid-side shutoff valve <NUM>, the outdoor expansion valve <NUM>, the outdoor heat exchanger <NUM>, the four-way switching valve <NUM>, and the accumulator <NUM>.

The refrigerant recovery operation is performed when the refrigerant in the refrigerant circuit <NUM> is recovered to the outdoor unit <NUM>. At this time, the outdoor heat exchanger <NUM> and the accumulator <NUM> of the outdoor unit <NUM> function as a recovery unit that recovers the refrigerant in the refrigerant circuit <NUM>. Hereinafter, the outdoor heat exchanger <NUM> and the accumulator <NUM> are also referred to as recovery units <NUM> and <NUM>.

In the refrigerant recovery operation control, the outdoor control unit <NUM> switches the four-way switching valve <NUM> to the outdoor heat radiation state as in the cooling operation. The outdoor control unit <NUM> closes the liquid-side shutoff valve <NUM> and opens the gas-side shutoff valve <NUM>, the outdoor expansion valve <NUM>, and the indoor expansion valve <NUM>. The outdoor control unit <NUM> then drives the compressor <NUM> and the outdoor fan <NUM>, and outputs a command to drive the indoor fan <NUM> to the indoor control unit <NUM>.

When the compressor <NUM> is driven, the refrigerant retained in a refrigerant pipe <NUM>, the liquid-refrigerant connection pipe <NUM>, the indoor expansion valve <NUM>, the indoor heat exchanger <NUM>, and the gas-refrigerant connection pipe <NUM> in the refrigerant circuit <NUM> flows into the accumulator <NUM> through the gas-side shutoff valve <NUM> and the four-way switching valve <NUM>. Of the refrigerant flowing into the accumulator <NUM>, a liquid refrigerant stays in the accumulator <NUM>, and a gas refrigerant is sucked into the compressor <NUM> and flows from the compressor <NUM> into the outdoor heat exchanger <NUM> through the four-way switching valve <NUM>. The gas refrigerant flowing into the outdoor heat exchanger <NUM> flows out toward the liquid-side shutoff valve <NUM>, but since the liquid-side shutoff valve <NUM> is closed, the refrigerant accumulates in the outdoor heat exchanger <NUM>. As described above, the refrigerant in the refrigerant circuit <NUM> is recovered by the recovery units <NUM> and <NUM> of the outdoor unit <NUM>.

When the recovery of the refrigerant into the recovery units <NUM> and <NUM> is completed, the outdoor control unit <NUM> stops the driving of the compressor <NUM>, the outdoor fan <NUM>, and the indoor fan <NUM>, and closes the gas-side shutoff valve <NUM>. By closing the gas-side shutoff valve <NUM> in this manner, the refrigerant recovered by the recovery units <NUM> and <NUM> can be prevented from flowing out toward the indoor unit <NUM>.

The outdoor control unit <NUM> has a first control mode and a second control mode different from each other as control modes of the refrigerant recovery operation. The first control mode and the second control mode are selected and set by the input unit <NUM> of the outdoor unit <NUM> by a service engineer or the like. The outdoor control unit <NUM> selectively executes the first control mode and the second control mode as the refrigerant recovery operation control on the basis of an output signal from the input unit <NUM>.

The first control mode is used as a control mode of the refrigerant recovery operation, for example, when the refrigerant recovery operation is performed at a time of discarding the air conditioner <NUM>. When the air conditioner <NUM> is discarded, the air conditioner <NUM> will not be used in future. Thus, there is no problem even if some damage is given to the air conditioner <NUM> as long as the air conditioner <NUM> can be operated until the refrigerant is completely recovered. Therefore, in the first control mode, the refrigerant recovery operation is performed by increasing the flow rate of the refrigerant in the refrigerant circuit <NUM> so as to prioritize reduction of refrigerant recovery time over damage to the air conditioner <NUM>.

The second control mode is used as a control mode of the refrigerant recovery operation, for example, in a case where the air conditioner <NUM> is continuously used after the refrigerant recovery operation. As a case where the air conditioner <NUM> is continuously used after the refrigerant recovery operation, there may be a case where the air conditioner <NUM> is expanded, relocated, maintained, or updated. In these cases, since the air conditioner <NUM> is continuously used after the refrigerant is recovered, it is not preferable to damage the air conditioner <NUM>. Therefore, in the second control mode, the refrigerant recovery operation is performed by reducing the flow rate of the refrigerant in the refrigerant circuit <NUM> so as to prioritize suppression of damage to the air conditioner <NUM> over reduction of the refrigerant recovery time.

As described above, the outdoor control unit <NUM> controls the components of the outdoor unit <NUM> and the indoor unit <NUM> such that the flow rate of the refrigerant in the refrigerant circuit <NUM> in the first control mode is larger than the flow rate of the refrigerant in the refrigerant circuit <NUM> in the second control mode. In the present embodiment, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the rotational speed of the compressor <NUM> that compresses and discharges the refrigerant of the refrigerant circuit <NUM> in the first control mode is higher than the rotational speed of the compressor <NUM> in the second control mode.

For example, in the first control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that a pressure of the refrigerant sucked from the compressor <NUM> (first pressure) approaches a predetermined protection lower limit value, or a pressure of the refrigerant discharged from the compressor <NUM> (second pressure) approaches a predetermined protection upper limit value. Here, the protection lower limit value is an allowable lower limit value of the first pressure against damage to the compressor <NUM>. Here, the protection upper limit value is an allowable upper limit value of the second pressure against damage to the compressor <NUM>.

In the second control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the first pressure does not become lower than or equal to a predetermined drooping lower limit value and the second pressure does not become higher than or equal to a predetermined drooping upper limit value. The drooping value is a value determined to protect the compressor <NUM> during a normal operation (during the cooling operation or the heating operation) of the air conditioner <NUM>, and is a value of the first pressure and a value of the second pressure that define a range in which the refrigerant recovery operation can be performed so as not to greatly damage the compressor <NUM>. The drooping lower limit value that is a lower limit value of the first pressure is a value larger than the protection lower limit value. The drooping upper limit value that is an upper limit value of the second pressure is a value smaller than the protection upper limit value.

When the first pressure of the compressor <NUM> is low or the second pressure of the compressor <NUM> is high, the refrigerant can be recovered by the recovery units <NUM> and <NUM> in a short time. However, when the first pressure of the compressor <NUM> is excessively low or the second pressure of the compressor <NUM> is excessively high, the temperature of the compressor <NUM> rises and the compressor <NUM> may be damaged. In the first control mode, the reduction of the refrigerant recovery time is prioritized over the damage to the compressor <NUM>. Therefore, in the first control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> on the basis of a detection value of the suction pressure sensor <NUM> or the discharge pressure sensor <NUM> such that the first pressure of the compressor <NUM> becomes a value close to the protection lower limit value (for example, <NUM> MPa) or the second pressure of the compressor <NUM> becomes a value close to the protection upper limit value (for example, <NUM> MPa).

On the other hand, in the second control mode, the suppression of the damage to the compressor <NUM> is prioritized over the reduction of the refrigerant recovery time. Therefore, in the second control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the first pressure of the compressor <NUM> becomes higher than or equal to the drooping lower limit value and the second pressure of the compressor <NUM> becomes lower than or equal to the drooping upper limit value.

Specifically, in the second control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> on the basis of a detection value of the suction pressure sensor <NUM> or the discharge pressure sensor <NUM> such that the first pressure of the compressor <NUM> becomes greater than or equal to a value (for example, <NUM> MPa) higher than the protection lower limit value or the second pressure of the compressor <NUM> becomes less than or equal to a value (for example, <NUM> MPa) lower than the protection upper limit value.

In the first control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the temperature of the refrigerant discharged from the compressor <NUM> (discharge-side temperature) approaches a predetermined protection upper limit temperature. Here, the protection upper limit temperature is an upper limit value of the discharge-side temperature at which the compressor <NUM> can be driven without failure.

When the discharge-side temperature of the compressor <NUM> is high, the refrigerant can be recovered by the recovery units <NUM> and <NUM> in a short time. However, when the discharge-side temperature of the compressor <NUM> is excessively high, the compressor <NUM> may be damaged. In the first control mode, the reduction of the refrigerant recovery time is prioritized over the damage to the compressor <NUM>. Therefore, in the first control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> on the basis of a detection value of the discharge temperature sensor <NUM> such that the discharge-side temperature of the compressor <NUM> becomes a value close to the protection upper limit temperature (for example, <NUM>).

On the other hand, in the second control mode, the suppression of the damage to the compressor <NUM> is prioritized over the reduction of the refrigerant recovery time. Thus, in the second control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the discharge-side temperature of the compressor <NUM> does not approach the protection upper limit temperature. Specifically, in the second control mode, the outdoor control unit <NUM> controls the operation of the compressor <NUM> on the basis of a detection value of the discharge temperature sensor <NUM> such that the discharge-side temperature of the compressor <NUM> becomes less than or equal to a value lower than the protection upper limit temperature (for example, <NUM>).

<FIG> is a flowchart illustrating a control example during the refrigerant recovery operation of the air conditioner <NUM>. Note that a specific pressure value and temperature value described below are merely examples, and it goes without saying that the specific pressure value and temperature value are different values depending on the type of the refrigerant.

First, the outdoor control unit <NUM> closes the liquid-side shutoff valve <NUM> and opens the outdoor expansion valve <NUM> and the indoor expansion valve <NUM> (step ST11). Thereafter, the outdoor control unit <NUM> drives the outdoor fan <NUM> and the indoor fan <NUM> (step ST12).

The outdoor control unit <NUM> determines whether the output signal from the input unit <NUM> is a signal indicating the first control mode (step ST13). When the output signal from the input unit <NUM> is a signal indicating the first control mode ("Yes" in step ST13), the outdoor control unit <NUM> controls the operation of the compressor <NUM> in the first control mode (step ST14).

Specifically, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the rotational speed of the compressor <NUM> becomes high. For example, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the first pressure of the compressor <NUM> becomes a value close to the protection lower limit value of <NUM> MPa or the second pressure of the compressor <NUM> becomes a value close to the protection upper limit value of <NUM> MPa. The outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the discharge-side temperature of the compressor <NUM> becomes a value close to <NUM>, which is the protection upper limit temperature.

When the output signal from the input unit <NUM> is not a signal indicating the first control mode ("No" in step ST13), the outdoor control unit <NUM> determines that the output signal from the input unit <NUM> is a signal indicating the second control mode and controls the operation of the compressor <NUM> in the second control mode (step ST15).

Specifically, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the rotational speed of the compressor <NUM> becomes lower than the rotational speed of the compressor <NUM> in the first control mode. For example, the outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the first pressure of the compressor <NUM> becomes greater than or equal to <NUM> MPa which is higher than the protection lower limit value and the second pressure of the compressor <NUM> becomes less than or equal to <NUM> MPa which is lower than the protection upper limit value. The outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the discharge-side temperature of the compressor <NUM> becomes less than or equal to <NUM> which is lower than the protection upper limit temperature.

In the air conditioner <NUM> according to the present embodiment, the outdoor control unit <NUM> can selectively use the first control mode and the second control mode in which the flow rate of the refrigerant in the refrigerant circuit <NUM> is different during the refrigerant recovery operation for recovering the refrigerant in the refrigerant circuit <NUM>, and thus can perform the refrigerant recovery operation in accordance with a timing of recovering recover the refrigerant.

The outdoor control unit <NUM> controls the operation of the compressor <NUM> such that the rotational speed of the compressor <NUM> that compresses and discharges the refrigerant of the refrigerant circuit <NUM> in the first control mode is higher than the rotational speed of the compressor <NUM> in the second control mode. As a result, in the first control mode, the flow rate of the refrigerant in the refrigerant circuit <NUM> can be easily increased as compared with the second control mode.

When the refrigerant is recovered at the time of discarding the air conditioner <NUM>, there is no problem even if some damage is given to the air conditioner <NUM>. Thus, in the first control mode, the flow rate of the refrigerant in the refrigerant circuit <NUM> can be made larger than in the second control mode. As a result, refrigerant recovery time can be reduced. In a case where the air conditioner <NUM> is continuously used after the refrigerant is recovered, the flow rate of the refrigerant in the refrigerant circuit <NUM> can be made smaller in the second control mode during the refrigerant recovery than in the first control mode. As a result, the damage to the air conditioner <NUM> can be suppressed.

In the first control mode, the outdoor control unit <NUM> controls the compressor <NUM> such that the first pressure of the compressor <NUM> becomes a value close to the protection lower limit value or the second pressure of the compressor <NUM> becomes a value close to the protection upper limit value. Thus, the flow rate of the refrigerant in the refrigerant circuit <NUM> can be increased as much as possible. As a result, the refrigerant recovery time can be reduced as much as possible.

In the second control mode, the outdoor control unit <NUM> controls the compressor <NUM> such that the first pressure of the compressor <NUM> becomes higher than or equal to the drooping lower limit value and the second pressure of the compressor <NUM> becomes lower than or equal to the drooping upper limit value. Accordingly, the refrigerant can be recovered while suppressing the damage to the compressor <NUM>.

<FIG> is a flowchart illustrating a modification of the control example during the refrigerant recovery operation of the air conditioner <NUM>. The outdoor control unit <NUM> of the present modification controls the opening degree of the indoor expansion valve <NUM> such that the opening degree of the indoor expansion valve <NUM> that is adjustable of the flow of the refrigerant in the refrigerant circuit <NUM> in the first control mode is larger than the opening degree of the indoor expansion valve <NUM> in the second control mode.

For example, the outdoor control unit <NUM> controls the opening degree of the indoor expansion valve <NUM> such that the opening degree of the indoor expansion valve <NUM> is fully opened in the first control mode. The outdoor control unit <NUM> controls the opening degree of the indoor expansion valve <NUM> such that the opening degree of the indoor expansion valve <NUM> in the second control mode is smaller than when the indoor expansion valve <NUM> is fully opened.

First, the outdoor control unit <NUM> closes the liquid-side shutoff valve <NUM> and opens the outdoor expansion valve <NUM> (step ST21). Next, the outdoor control unit <NUM> determines whether the output signal from the input unit <NUM> is a signal indicating the first control mode (step ST22). When the output signal from the input unit <NUM> is a signal indicating the first control mode ("Yes" in step ST22), the outdoor control unit <NUM> controls the opening degree of the indoor expansion valve <NUM> in the first control mode (step ST23). Specifically, the outdoor control unit <NUM> controls the opening degree of the indoor expansion valve <NUM> such that the indoor expansion valve <NUM> is fully opened.

When the output signal from the input unit <NUM> is not a signal indicating the first control mode ("No" in step ST22), the outdoor control unit <NUM> determines that the output signal from the input unit <NUM> is a signal indicating the second control mode and controls the opening degree of the indoor expansion valve <NUM> in the second control mode (step ST24). Specifically, the outdoor control unit <NUM> controls the opening degree of the indoor expansion valve <NUM> to be smaller than when the indoor expansion valve <NUM> is fully opened.

The outdoor control unit <NUM> controls the opening degree of the indoor expansion valve <NUM> in the first control mode or the second control mode, and then drives the outdoor fan <NUM>, the indoor fan <NUM>, and the compressor <NUM> (step ST25).

In the present modification, the opening degree of the indoor expansion valve <NUM> that is adjustable of the flow of the refrigerant in the refrigerant circuit <NUM> in the first control mode is larger than the opening degree of the indoor expansion valve <NUM> in the second control mode. As a result, in the first control mode, the flow rate of the refrigerant in the refrigerant circuit <NUM> can be easily increased as compared with the second control mode.

In the above embodiment, the outdoor control unit <NUM> and the like function as the refrigerant recovery control device. Alternatively, a centralized controller that controls the outdoor unit <NUM> and the indoor unit <NUM> may function as the refrigerant recovery control device, and the centralized controller may instruct the outdoor control unit <NUM> about the control mode of the refrigerant recovery operation. A remote controller communicably connected to the outdoor control unit <NUM> via a network may remotely control the refrigerant recovery operation of the air conditioner <NUM>. In this case, the air conditioner <NUM> and the control unit of the remote controller constitute a refrigerant recovery control system of the present invention.

The present invention can be applicable to a refrigeration apparatus other than the air conditioner <NUM>. Furthermore, the present invention may be applied to a chiller unit or a cascade unit.

In the above embodiment, in the first control mode, the compressor <NUM> is controlled such that the first pressure becomes a value close to the protection lower limit value or the second pressure becomes a value close to the protection upper limit value. Alternatively, the compressor <NUM> may be controlled such that the first pressure becomes a value close to the protection lower limit value and the second pressure becomes a value close to the protection upper limit value.

Claim 1:
A refrigerant recovery control device comprising
a control unit (<NUM>) having a first control mode and a second control mode different from each other as control modes of a refrigerant recovery operation for recovering a refrigerant in a refrigerant circuit (<NUM>) in a refrigeration apparatus (<NUM>) , wherein the control unit (<NUM>) closes
an outdoor expansion valve (<NUM>) and a liquid-side shutoff valve (<NUM>) of the refrigerant circuit (<NUM>), or opens the outdoor expansion valve (<NUM>) and closes the liquid-side shutoff valve (<NUM>),
wherein
the refrigerant in the refrigerant circuit (<NUM>) in the first control mode has a flow rate that is larger than a flow rate of the refrigerant in the refrigerant circuit (<NUM>) in the second control mode.