Patent Description:
Conventionally, a refrigeration apparatus having a refrigerant circuit where plural utilization units including utilization-side heat exchangers are connected in parallel to a heat source unit including a compressor has been known. For example, in the air conditioning system disclosed in patent document <NUM> (<CIT>), a refrigerant circuit where plural indoor units are connected in parallel to an outdoor unit including a compressor is configured. Patent document <NUM> (<CIT>) relates to an air-conditioning apparatus securing the connection flexibility between the outdoor unit and the indoor unit and, at the same time, preventing an inflammable refrigerant flowing into an indoor unit that is not sufficiently fireproof.

In this kind of refrigeration apparatus, there is the potential for refrigerant leakage caused by pipe damage or the like, in each of the utilization units. In a refrigeration apparatus having plural utilization units, the quantity of refrigerant contained in the refrigerant circuit is large compared to a refrigeration apparatus having a single utilization unit, so in a case where refrigerant leakage has occurred, cases are also assumed where the concentration of leaking refrigerant becomes greater in the spaces where those utilization units are installed. In such a case as this, when the leaking refrigerant is, for example, a mildly flammable refrigerant such as R32, a flammable refrigerant such as propane, or a toxic refrigerant such as ammonia, security is not ensured.

It is a problem of the present invention to improve the security of a refrigeration apparatus including plural utilization units.

A refrigeration apparatus pertaining to a first aspect of the present invention is defined in claim <NUM> and, among other technical features, has a refrigerant circuit, a plurality of inlet valves, and a control unit. The refrigerant circuit is configured and arranged to include a heat source unit and a plurality of utilization units. The heat source unit has a compressor. Each of the utilization units has a utilization-side heat exchanger. The plurality of utilization units are disposed in parallel to each other. The inlet valves are configured and arranged to cut off a flow of supplied refrigerant in a closed state. The control unit is configured and arranged to transition to a predetermined control mode in accordance with the situation. The control unit is configured and arranged to control the operation of the compressor and each of the inlet valves in accordance with the control mode. Each of the inlet valves is disposed on a refrigerant inlet side of any of the utilization-side heat exchangers. The control unit is electrically connected to refrigerant leakage sensors. The refrigerant leakage sensor are configured and arranged to detect refrigerant leakage inside each of the utilization units. The control unit is configured and arranged to transition to a refrigerant leakage control mode in a case where the refrigerant leakage sensors have detected refrigerant leakage in any of the utilization units. The control unit is configured and arranged to, in the refrigerant leakage control mode, control to the closed state the inlet valve disposed on the inlet side of the utilization-side heat exchanger of the utilization unit in which the refrigerant leakage has been detected and cause the compressor to operate at a predetermined rotational speed.

In the refrigeration apparatus pertaining to the first aspect of the present invention, in a case where the refrigerant leakage sensors have detected refrigerant leakage in any of the utilization units, the control unit transitions to the refrigerant leakage control mode, controls to the closed state the inlet valve disposed on the inlet side of the utilization-side heat exchanger of the utilization unit in which the refrigerant leakage has been detected, and causes the compressor to operate at the predetermined rotational speed. Due to this, the supply of the refrigerant to the utilization unit in which the refrigerant leakage is occurring is stopped. As a result, even in a case where refrigerant leakage has occurred in any of the utilization units, an increase in the quantity of leaking refrigerant is restrained.

Furthermore, the compressor is operated in a state in which the inlet valve disposed on the inlet side of the utilization-side heat exchanger of the utilization unit in which the refrigerant leakage has been detected is closed, so the refrigerant remaining inside the utilization unit in which the refrigerant leakage is occurring is recovered to the heat source unit, so that an increase in the quantity of leaking refrigerant is restrained.

Thus, increasing the concentration of leaking refrigerant is restrained from becoming greater in the space where the utilization unit in which the refrigerant leakage is occurring is installed. Consequently, the security of the refrigeration apparatus including the plural utilization units in the refrigerant circuit is improved.

It will be noted that the "inlet valves" may be disposed inside the utilization units or may be disposed outside the utilization units.

Furthermore, the refrigerant used in the "refrigerant circuit" is not particularly limited, and, for example, a mildly flammable refrigerant such as R32, or a flammable refrigerant such as propane, or a toxic refrigerant such as ammonia is assumed.

Furthermore, "cause the compressor to operate at a predetermined rotational speed" includes not only causing the compressor to operate at a fixed rotational speed determined beforehand but also causing the compressor to rotate at a rotational speed selected from among a predetermined range of rotational speeds defined beforehand (appropriately selecting a rotational speed according to the situation and causing the compressor to operate at that rotational speed).

A refrigeration apparatus pertaining to a second aspect of the present invention is the refrigeration apparatus pertaining to the first aspect, wherein in the refrigerant leakage control mode, the control unit is configured and arranged to control, to a predetermined opening degree for a refrigerant recovery operation, the inlet valve disposed on the inlet side of the utilization-side heat exchanger of the utilization unit in which the refrigerant leakage has not been detected.

Due to this, the refrigerant inside each of the utilization units including the utilization unit in which the refrigerant leakage is occurring is recovered to the heat source unit. As a result, a situation where the refrigerant flows into the utilization unit in which the refrigerant leakage is occurring from the other utilization unit so that the quantity of leaking refrigerant increases is restrained. Thus, the security of the refrigeration apparatus including the plural utilization units in the refrigerant circuit is further improved.

A refrigeration apparatus pertaining to a third aspect of the present invention is the refrigeration apparatus pertaining to the first aspect or the second aspect, further has a plurality of outlet valves. The outlet valves are configured and arranged to cut off, on refrigerant outlet sides of the utilization-side heat exchangers, a flow of the refrigerant from the outlet sides to the inlet sides. Each of the outlet valves is disposed on the outlet side of any of the utilization-side heat exchangers. The control unit is configured and arranged to, when it is assumed that recovery of the refrigerant from each of the utilization-side heat exchangers to the heat source unit has been completed in the refrigerant leakage control mode, cause a fallback operation of the compressor to be performed. The control unit is configured and arranged to control, in the fallback operation, to a predetermined opening degree for the fallback operation, the inlet valve disposed on the inlet side of the utilization-side heat exchanger of the utilization unit in which the refrigerant leakage has not been detected.

Due to this, the compressor is fallback-operated even in a case where refrigerant leakage has occurred in any of the utilization units. As a result, the refrigeration cycle is performed in the utilization unit in which the refrigerant leakage is not occurring. Thus, deterioration of products requiring temperature management or a reduction in comfort is restrained in the space where the utilization unit in which the refrigerant leakage is not occurring is installed.

A refrigeration apparatus pertaining to a fourth aspect of the present invention is the refrigeration apparatus pertaining to any of the first aspect to the third aspect, further has an information output unit. The information output unit is configured and arranged to be controlled by the control unit. The information output unit is configured and arranged to output information. The control unit is configured and arranged to, in the refrigerant leakage control mode, cause the information output unit to output predetermined notification information.

Due to this, in a case where refrigerant leakage has occurred in the utilization units, the predetermined notification information (e.g., information identifying the fact that refrigerant leakage has occurred and the utilization unit in which the refrigerant leakage is occurring) is output. As a result, in a case where refrigerant leakage has occurred in any of the utilization units, the manager can easily recognize this state of affairs and is urged to take action. Thus, security with respect to refrigerant leakage is further improved.

In the refrigeration apparatus pertaining to the first aspect of the present invention, the supply of the refrigerant to the utilization unit in which the refrigerant leakage is occurring is stopped. As a result, even in a case where refrigerant leakage has occurred in any of the utilization units, an increase in the quantity of leaking refrigerant is restrained. Furthermore, the refrigerant remaining inside the utilization unit in which the refrigerant leakage is occurring is recovered to the heat source unit, so that an increase in the quantity of leaking refrigerant is restrained. Thus, increasing the concentration of leaking refrigerant is restrained from becoming greater in the space where the utilization unit in which the refrigerant leakage is occurring is installed. Consequently, the security of the refrigeration apparatus including the plural utilization units in the refrigerant circuit is improved.

In the refrigeration apparatus pertaining to the second aspect of the present invention, a situation where the refrigerant flows into the utilization unit in which the refrigerant leakage is occurring from the other utilization unit so that the quantity of leaking refrigerant increases is restrained. Thus, the security of the refrigeration apparatus including the plural utilization units in the refrigerant circuit is further improved.

In the refrigeration apparatus pertaining to the third aspect of the present invention, the refrigeration cycle is performed in the utilization unit in which the refrigerant leakage is not occurring. Thus, deterioration of products requiring temperature management or a reduction in comfort is restrained in the space where the utilization unit in which the refrigerant leakage is not occurring is installed.

In the refrigeration apparatus pertaining to the fourth aspect of the present invention, the predetermined notification information is output in a case where refrigerant leakage has occurred in the utilization units. As a result, in a case where refrigerant leakage has occurred in any of the utilization units, the manager can easily recognize this state of affairs and is urged to take action. Thus, security with respect to refrigerant leakage is further improved.

A refrigeration apparatus <NUM> pertaining to an embodiment of the present invention will be described below with reference to the drawings. It will be noted that the following embodiment is a specific example of the present invention, is not intended to limit the technical scope of the present invention, and can be appropriately changed to the extent that it does not depart from the scope of the present which is solely defined by the appended claims.

<FIG> is an overall configuration diagram of the refrigeration apparatus <NUM> pertaining to the embodiment of the present invention. The refrigeration apparatus <NUM> is a system that performs, by means of a vapor compression refrigeration cycle, refrigeration of utilization-side spaces such as interior spaces of refrigerated storage rooms or showcases in a store. The refrigeration apparatus <NUM> mainly has a heat source unit <NUM>, plural (here, three) utilization units <NUM> (30a, 30b, 30c), a liquid refrigerant communication pipe L1 and a gas refrigerant communication pipe G1 that interconnect the heat source unit <NUM> and the utilization units <NUM>, refrigerant leakage sensors <NUM> (40a, 40b, 40c) that detect refrigerant leakage inside each of the utilization units <NUM>, plural remote controllers <NUM> (50a, 50b, 50c) serving as input devices and as display devices, and a controller <NUM> that controls the operation of the refrigeration apparatus <NUM>.

In the refrigeration apparatus <NUM>, a refrigerant circuit RC is configured as a result of the one heat source unit <NUM> and the plural (here, three) utilization units <NUM> being interconnected via the liquid refrigerant communication pipe L1 and the gas refrigerant communication pipe G1. In the refrigeration apparatus <NUM>, a refrigeration cycle is performed wherein refrigerant contained inside the refrigerant circuit RC is compressed, cooled or condensed, reduced in pressure, heated or evaporated, and thereafter again compressed. In the present embodiment, the refrigerant circuit RC is charged with R32 as the refrigerant for performing the vapor compression refrigeration cycle.

The heat source unit <NUM> is connected to the utilization units <NUM> via the liquid refrigerant communication pipe L1 and the gas refrigerant communication pipe G1, and configures part of the refrigerant circuit RC. The heat source unit <NUM> mainly has a compressor <NUM>, a heat source-side heat exchanger <NUM>, a receiver <NUM>, a sub-cooler <NUM>, a heat source-side expansion valve <NUM> (expansion mechanism), an injection valve <NUM>, a liquid-side shut-off valve <NUM>, and a gas-side shut-off valve <NUM>.

The heat source unit <NUM> has a first heat source-side gas refrigerant pipe P1 that interconnects the discharge side of the compressor <NUM> and the gas-side end of the heat source-side heat exchanger <NUM>, a heat source-side liquid refrigerant pipe P2 that interconnects the liquid-side end of the heat source-side heat exchanger <NUM> and the liquid refrigerant communication pipe L1, and a second heat source-side gas refrigerant pipe P3 that interconnects the suction side of the compressor <NUM> and the gas refrigerant communication pipe G1.

The heat source unit <NUM> has an injection pipe P4 that diverts some of the refrigerant flowing through the heat source-side liquid refrigerant pipe P2 and returns the diverted refrigerant to the compressor <NUM>. The injection pipe P4 branches from the section of the heat source-side liquid refrigerant pipe P2 located on the downstream side of the sub-cooler <NUM>, passes through the sub-cooler <NUM>, and is then connected to the middle of the compression stroke of the compressor <NUM>.

The compressor <NUM> is a device that compresses refrigerant at a low pressure in the refrigeration cycle to a high pressure. Here, as the compressor <NUM>, a compressor with a closed structure in which a rotary, scroll or the like positive-displacement compression element (not shown in the drawings) is driven to rotate by a compressor motor M11 is used. Furthermore, the operating frequency of the compressor motor M11 can be controlled by an inverter, whereby the capacity of the compressor <NUM> can be controlled.

The heat source-side heat exchanger <NUM> is a heat exchanger that functions as a radiator or condenser of refrigerant at a high pressure in the refrigeration cycle. Here, the heat source unit <NUM> has a heat source-side fan <NUM> for sucking outside air (heat source-side air) into the heat source unit <NUM>, causing the air to exchange heat with the refrigerant in the heat source-side heat exchanger <NUM>, and thereafter discharge the air to the outside. The heat source-side fan <NUM> is a fan for supplying to the heat source-side heat exchanger <NUM> the heat source-side air serving as a cooling source for the refrigerant flowing through the heat source-side heat exchanger <NUM>. The heat source-side fan <NUM> is driven to rotate by a heat source-side fan motor M19.

The receiver <NUM> is a vessel that temporarily stores the refrigerant condensed in the heat source-side heat exchanger <NUM>, and is disposed in the heat source-side liquid refrigerant pipe P2.

The sub-cooler <NUM> is a heat exchanger that further cools the refrigerant temporarily stored in the receiver <NUM>, and is disposed in the heat source-side liquid refrigerant pipe P2 (more specifically, in the section thereof on the downstream side of the receiver <NUM>).

The heat source-side expansion valve <NUM> is an electrically powered expansion valve whose opening degree can be controlled, and is disposed in the heat source-side liquid refrigerant pipe P2 (more specifically, in the section thereof on the downstream side of the sub-cooler <NUM>).

The injection valve <NUM> is disposed in the injection pipe P4 (more specifically, in the section thereof that leads to the inlet of the sub-cooler <NUM>). The injection valve <NUM> is an electrically powered expansion valve whose opening degree can be controlled. The injection valve <NUM> reduces, in accordance with its opening degree, the pressure of the refrigerant flowing through the injection pipe P4 before allowing the refrigerant to flow into the sub-cooler <NUM>.

The liquid-side shut-off valve <NUM> is a manual valve disposed in the section of the heat source-side liquid refrigerant pipe P2 connected to the liquid refrigerant communication pipe L1.

The gas-side shut-off valve <NUM> is a manual valve disposed in the section of the second heat source-side gas refrigerant pipe P3 connected to the gas refrigerant communication pipe G1.

Various types of sensors are disposed in the heat source unit <NUM>. Specifically, a suction pressure sensor <NUM> which detects a suction pressure LP that is the pressure of the refrigerant on the suction side of the compressor <NUM>, and a discharge pressure sensor <NUM> which detects a discharge pressure HP that is the pressure of the refrigerant on the discharge side of the compressor <NUM>, are disposed in the vicinity of the compressor <NUM> of the heat source unit <NUM>. Furthermore, a receiver outlet temperature sensor <NUM>, which detects the receiver outlet temperature that is the temperature of the refrigerant at the outlet of the receiver <NUM>, is disposed in the section of the heat source-side liquid refrigerant pipe P2 between the outlet of the receiver <NUM> and the inlet of the sub-cooler <NUM>. Moreover, a heat source-side air temperature sensor <NUM>, which detects the temperature of the heat source-side air sucked into the heat source unit <NUM>, is disposed in the vicinity of the heat source-side heat exchanger <NUM> or the heat source-side fan <NUM>.

The heat source unit <NUM> has a heat-source-unit control unit <NUM> that controls the operation of each part configuring the heat source unit <NUM>. The heat-source-unit control unit <NUM> has a microcomputer including a CPU and a memory or the like. The heat source control unit <NUM> is connected via a communication line cb1 to utilization-unit control units <NUM> of each of the utilization units <NUM>, and sends controls signals and so forth to, and receives control signals and so forth from, the utilization-unit control units <NUM>.

The utilization units <NUM> are connected to the heat source unit <NUM> via the liquid refrigerant communication pipe L1 and the gas refrigerant communication pipe G1, and configure part of the refrigerant circuit RC. In the present embodiment, three utilization units <NUM> (30a, 30b, and 30c) are connected to one heat source unit <NUM>. The utilization units <NUM> are disposed in parallel to each other.

Each of the utilization units <NUM> has a utilization-side expansion valve <NUM> and a utilization-side heat exchanger <NUM> (evaporator). Furthermore, each of the utilization units <NUM> has a utilization-side liquid refrigerant pipe P5 which interconnects the liquid-side end of the utilization-side heat exchanger <NUM> and the liquid refrigerant communication pipe L1, and a utilization-side gas refrigerant pipe P6 which interconnects the gas-side end of the utilization-side heat exchanger <NUM> and the gas refrigerant communication pipe G1.

The utilization-side expansion valve <NUM> is a throttling mechanism that functions as a means (expanding means) for reducing the pressure of the high-pressure refrigerant sent from the heat source unit <NUM>. In the present embodiment, the utilization-side expansion valve <NUM> is a thermostatic expansion valve including a thermosensitive cylinder and operates (its opening degree is automatically determined) in accordance with changes in the temperature of the thermosensitive cylinder.

The utilization-side heat exchanger <NUM> is a heat exchanger that functions as an evaporator of the refrigerant at a low temperature in the refrigeration cycle to refrigerate the interior space air (utilization-side air). Here, the utilization unit <NUM> has a utilization-side fan <NUM> for sucking the utilization-side air into the utilization unit <NUM>, causing the utilization-side air to exchange heat with the refrigerant in the utilization-side heat exchanger <NUM>, and thereafter supplying the utilization-side air to the utilization-side space. The utilization-side fan <NUM> is a fan for supplying to the utilization-side heat exchanger <NUM> the utilization-side air serving as a heating source for the refrigerant flowing through the utilization-side heat exchanger <NUM>. The utilization-side fan <NUM> is driven to rotate by a utilization-side fan motor M35.

Furthermore, each of the utilization units <NUM> has an on/off valve <NUM> (inlet valve) capable of cutting off the flow of refrigerant flowing into the utilization unit <NUM>. The on/off valve <NUM> is disposed on the liquid refrigerant inlet side (the liquid refrigerant communication pipe L1 side) of the utilization unit <NUM>. Specifically, the on/off valve <NUM> is disposed on nearer to the inlet side than the utilization-side heat exchanger <NUM>. More specifically, the on/off valve <NUM> is disposed on nearer to the inlet side than the utilization-side expansion valve <NUM>. In the present embodiment, the on/off valve <NUM> is an electromagnetic valve that is switched between an open state and a closed state. Specifically, the on/off valve <NUM> is switched from the open state to the closed state as a result of being powered. When the on/off valve <NUM> is switched to the closed state, the on/off valve <NUM> cuts off the flow of refrigerant flowing into the utilization unit <NUM> (more specifically, the utilization-side heat exchanger <NUM>). The on/off valve <NUM> is controlled so as to normally be in the open state.

Furthermore, each of the utilization units <NUM> has a check valve <NUM> (outlet valve) capable of cutting off the flow of refrigerant flowing (back-flowing) into the utilization unit <NUM> from its outlet side. The check valve <NUM> is disposed on the refrigerant outlet side (the gas refrigerant communication pipe G1 side) of the utilization unit <NUM>. Specifically, the check valve <NUM> is disposed on nearer to the outlet side than the utilization-side heat exchanger <NUM>. The check valve <NUM> allows the flow of refrigerant from the utilization-side gas refrigerant pipe P6 to the gas refrigerant communication pipe G1 but cuts off the flow of refrigerant from the gas refrigerant communication pipe G1 to the utilization-side gas refrigerant pipe P6 (more specifically, nearer to the utilization-side heat exchanger <NUM> side than the check valve <NUM>).

Furthermore, each of the utilization units <NUM> has a utilization-unit control unit <NUM> that controls the operation of each part configuring the utilization unit <NUM>. The utilization-unit control unit <NUM> has a microcomputer including a CPU and a memory, or the like. The utilization-unit control unit <NUM> is connected via the communication line cb1 to the heat-source-unit control unit <NUM>, and sends control signals and so forth to, and receives control signals and so forth from, the heat-source-unit control unit <NUM>. The utilization-unit control unit <NUM> is electrically connected to the refrigerant leakage sensor <NUM>, and signals from the refrigerant leakage sensor <NUM> are output to the utilization-unit control unit <NUM>.

The refrigerant leakage sensors <NUM> are sensors for detecting refrigerant leakage inside the interior spaces where the utilization units <NUM> are disposed (more specifically, inside the spaces of the utilization units <NUM>). In the present embodiment, a known general-purpose sensor is used for the refrigerant leakage sensors <NUM>.

The refrigerant leakage sensors <NUM> are disposed inside casings of the corresponding utilization units <NUM>. That is, the refrigerant leakage sensors <NUM> are disposed inside each of the utilization units <NUM>, so that the refrigeration apparatus <NUM> has the same number of refrigerant leakage sensors <NUM> as utilization units <NUM>.

The refrigerant leakage sensors <NUM> are electrically connected to the utilization-unit control units <NUM> of the corresponding utilization units <NUM>. Specifically, the refrigerant leakage sensor 40a is connected to the utilization-unit control unit <NUM> of the utilization unit 30a, the refrigerant leakage sensor 40b is connected to the utilization-unit control unit <NUM> of the utilization unit 30b, and the refrigerant leakage sensor 40c is connected to the utilization-unit control unit <NUM> of the utilization unit 30c respectively. When the refrigerant leakage sensor <NUM> detects refrigerant leakage, the refrigerant leakage sensor <NUM> outputs to the utilization-unit control unit <NUM> to which it is connected an electrical signal (hereinafter called a "refrigerant leakage signal") indicating that refrigerant leakage is occurring.

The remote controllers <NUM> are input devices for users to input various types of instructions for switching the operating state of the refrigeration apparatus <NUM>. Furthermore, the remote controllers <NUM> also function as display devices for displaying the operating state of the refrigeration apparatus <NUM> and predetermined notification information. The remote controllers <NUM> are connected via communication lines cb2 to the utilization-unit control units <NUM>, and send signals to, and receive signals from, the utilization-unit control units <NUM>. Specifically, the remote controller 50a is connected to the utilization-unit control unit <NUM> of the utilization unit 30a, the remote controller 50b is connected to the utilization-unit control unit <NUM> of the utilization unit 30b, and the remote controller 50c is connected to the utilization-unit control unit <NUM> of the utilization unit 30c.

In the refrigeration apparatus <NUM>, the controller <NUM> that controls the operation of the refrigeration apparatus <NUM> is configured as a result of the heat-source-unit control unit <NUM> and the respective utilization-unit control units <NUM> being interconnected via the communication line cb <NUM>. Details of the controller <NUM> will be described in "(<NUM>) Details of Controller <NUM>" below.

The flow of the refrigerant in the refrigerant circuit RC in each operating mode will be described below. In the refrigeration apparatus <NUM>, at the time of operation, a refrigeration operation (refrigeration cycle operation) is performed wherein the refrigerant charged in the refrigerant circuit RC circulates mainly in the order of the compressor <NUM>, the heat source-side heat exchanger <NUM> (radiator), the receiver <NUM>, the sub-cooler <NUM>, the heat source-side expansion valve <NUM> (expansion mechanism), the utilization-side expansion valves <NUM>, and the utilization-side heat exchangers <NUM> (evaporators).

When the refrigeration operation is started, inside the refrigerant circuit RC the refrigerant is sucked into the compressor <NUM>, compressed, and thereafter discharged. Here, the low pressure in the refrigeration cycle is the suction pressure LP detected by the suction pressure sensor <NUM>, and the high pressure in the refrigeration cycle is the discharge pressure HP detected by the discharge pressure sensor <NUM>.

In the compressor <NUM>, capacity control according to the cooling load required by the utilization units <NUM> is performed. Specifically, a target value for the suction pressure LP is set in accordance with the cooling load required by the utilization units <NUM>, and the operating frequency of the compressor <NUM> is controlled so that the suction pressure LP reaches the target value. The gas refrigerant discharged from the compressor <NUM> travels through the first heat source-side gas refrigerant pipe P1 and flows into the gas-side end of the heat source-side heat exchanger <NUM>.

The gas refrigerant that has flowed into the gas-side end of the heat source-side heat exchanger <NUM> exchanges heat with the heat source-side air supplied by the heat source-side fan <NUM>, radiates heat, condenses, and becomes liquid refrigerant in the heat source-side heat exchanger <NUM>, and then the liquid refrigerant flows out from the liquid-side end of the heat source-side heat exchanger <NUM>.

The liquid refrigerant that has flowed out from the liquid-side end of the heat source-side heat exchanger <NUM> travels through the section of the heat source-side liquid refrigerant pipe P2 between the heat source-side heat exchanger <NUM> and the receiver <NUM> and flows into the inlet of the receiver <NUM>. The liquid refrigerant that has flowed into the receiver <NUM> is temporarily stored as liquid refrigerant in a saturated state in the receiver <NUM>, and thereafter flows out from the outlet of the receiver <NUM>.

The liquid refrigerant that has flowed out from the outlet of the receiver <NUM> travels through the section of the heat source-side liquid refrigerant pipe P2 between the receiver <NUM> and the sub-cooler <NUM> and flows into the inlet on the heat source-side liquid refrigerant pipe P2 side of the sub-cooler <NUM>.

The liquid refrigerant that has flowed into the sub-cooler <NUM> exchanges heat with the refrigerant flowing through the injection pipe P4, is further cooled, and becomes liquid refrigerant in a sub-cooled state in the sub-cooler <NUM>, and then the sub-cooled liquid refrigerant flows out from the outlet on the heat source-side liquid refrigerant pipe P2 side of the sub-cooler <NUM>.

The liquid refrigerant that has flowed out from the outlet on the heat source-side liquid refrigerant pipe P2 side of the sub-cooler <NUM> travels through the section of the heat source-side liquid refrigerant pipe P2 between the sub-cooler <NUM> and the heat source-side expansion valve <NUM> and flows into the heat source-side expansion valve <NUM>. At this time, some of the liquid refrigerant that has flowed out from the outlet on the heat source-side liquid refrigerant pipe P2 side of the sub-cooler <NUM> is diverted to the injection pipe P4 from the section of the heat source-side liquid refrigerant pipe P2 between the sub-cooler <NUM> and the heat source-side expansion valve <NUM>.

The refrigerant flowing through the injection pipe P4 has its pressure reduced by the injection valve <NUM> to an intermediate pressure in the refrigeration cycle. The refrigerant flowing through the injection pipe P4 after its pressure has been reduced by the injection valve <NUM> flows into the inlet on the injection pipe P4 side of the sub-cooler <NUM>. The refrigerant that has flowed into the inlet on the injection pipe P4 side of the sub-cooler <NUM> exchanges heat with the refrigerant flowing through the heat source-side liquid refrigerant pipe P2, is heated, and becomes gas refrigerant in the sub-cooler <NUM>. Then, the refrigerant heated in the sub-cooler <NUM> flows out from the outlet on the injection pipe P4 side of the sub-cooler <NUM> and is returned to the middle of the compression stroke of the compressor <NUM>.

The liquid refrigerant that has flowed into the heat source-side expansion valve <NUM> from the heat source-side liquid refrigerant pipe P2 has its pressure reduced by the heat source-side expansion valve <NUM>, thereafter travels through the liquid-side shut-off valve <NUM> and the liquid refrigerant communication pipe L1, and flows into the utilization units <NUM> that are in operation.

The refrigerant that has flowed into the utilization units <NUM> travels through the on/off valves <NUM> and part of the utilization-side liquid refrigerant pipes P5 and flows into the utilization-side expansion valves <NUM>. The refrigerant that has flowed into the utilization-side expansion valves <NUM> has its pressure reduced by the utilization-side expansion valves <NUM> to a low pressure in the refrigeration cycle, travels through the utilization-side liquid refrigerant pipes P5, and flows into the liquid-side ends of the utilization-side heat exchangers <NUM>.

The refrigerant that has flowed into the liquid-side ends of the utilization-side heat exchangers <NUM> exchanges heat with the utilization-side air supplied by the utilization-side fans <NUM>, evaporates, and becomes gas refrigerant in the utilization-side heat exchangers <NUM>, and then the gas refrigerant flows out from the gas-side ends of the utilization-side heat exchangers <NUM>.

The gas refrigerant that has flowed out from the gas-side ends of the utilization-side heat exchangers <NUM> travels through the check valves <NUM>, the utilization-side gas refrigerant pipes P6, the gas refrigerant communication pipe G1, the gas-side shut-off valve <NUM>, and the second heat source-side gas refrigerant pipe P3, and is sucked back into the compressor <NUM>.

In the refrigeration apparatus <NUM>, the controller <NUM> is configured as a result of the heat-source-unit control unit <NUM> and the utilization-unit control units <NUM> being interconnected by the communication line cb1. <FIG> is a block diagram schematically showing the general configuration of the controller <NUM> and units connected to the controller <NUM>.

The controller <NUM> has plural control modes and controls the operation of the refrigeration apparatus <NUM> in accordance with the control mode to which it has transitioned. For example, the controller <NUM> has, as control modes, a normal operating mode, to which it transitions during normal times, and a refrigerant leakage control mode, to which it transitions when refrigerant leakage has occurred.

The controller <NUM> is electrically connected to each of the actuators (specifically, the compressor <NUM> (the compressor motor M11), the heat source-side expansion valve <NUM>, the injection valve <NUM>, and the heat source-side fan <NUM> (the heat source-side fan motor M19)) included in the heat source unit <NUM> and the various types of sensors (the suction pressure sensor <NUM>, the discharge pressure sensor <NUM>, the receiver outlet temperature sensor <NUM>, and the heat source-side air temperature sensor <NUM>, etc.). Furthermore, the controller <NUM> is electrically connected to the actuators (specifically, the utilization-side fan motors M35 and the on/off valves <NUM>) included in each of the utilization units <NUM> (30a, 30b, and 30c). Furthermore, the controller <NUM> is electrically connected to each of the refrigerant leakage sensors <NUM> (40a, 40b, and 40c) and each of the remote controllers <NUM> (50a, 50b, and 50c).

The controller <NUM> mainly has a storage component <NUM>, a communication component <NUM>, a mode control unit <NUM>, an actuator control unit <NUM>, and a display control unit <NUM>. It will be noted that each of these components in the controller <NUM> is realized by components included in the heat-source-unit control unit <NUM> and/or the utilization-unit control units <NUM> integrally functioning.

The storage component <NUM> is configured by a ROM, a RAM, and a flash memory, for example, and includes a volatile storage region and a nonvolatile storage region. Stored in the storage component <NUM> is a control program in which processing in each component of the controller <NUM> is defined. Furthermore, predetermined information (e.g., detection values of each of the sensors, commands that have been input to each of the remote controllers <NUM>, etc.) is appropriately stored in predetermined storage regions of the storage component <NUM> by the components of the controller <NUM>.

Furthermore, plural flags having a predetermined number of bits are provided in the storage component <NUM>. For example, refrigerant leakage discrimination flags F1, F2, and F3 for discriminating whether or not refrigerant leakage is occurring inside each of the utilization units <NUM> are provided in the storage component <NUM>. It will be noted that the refrigerant leakage discrimination flag F1 corresponds to the refrigerant leakage sensor 40a, the refrigerant leakage discrimination flag F2 corresponds to the refrigerant leakage sensor 40b, and the refrigerant leakage discrimination flag F3 corresponds to the refrigerant leakage sensor 40c.

Furthermore, a control mode discrimination flag F4 capable of discriminating the control mode to which the controller <NUM> has transitioned is provided in the storage component <NUM>. The control mode discrimination flag F4 is set in a case where the controller <NUM> has transitioned to the refrigerant leakage control mode.

The communication component <NUM> is a functional component that fulfills a role as a communication interface for sending signals to and receiving signals from each of the devices connected to the controller <NUM>. The communication component <NUM> receives requests from the actuator control unit <NUM> and sends predetermined signals to designated actuators. Furthermore, the communication component <NUM> receives signals that have been output from the various types of sensors (<NUM> to <NUM>), each of the refrigerant leakage sensors <NUM>, and each of the remote controllers <NUM>, and stores the signals in predetermined storage regions of the storage component <NUM>.

Furthermore, when the communication component <NUM> receives the refrigerant leakage signals from the refrigerant leakage sensors <NUM>, the communication component <NUM> raises the refrigerant leakage discrimination flags (F1, F2, or F3). Specifically, the communication component <NUM> raises the refrigerant leakage discrimination flag F1 in a case where it has received the refrigerant leakage signal from the refrigerant leakage sensor 40a, raises the refrigerant leakage discrimination flag F2 in a case where it has received the refrigerant leakage signal from the refrigerant leakage sensor 40b, and raises the refrigerant leakage discrimination flag F3 in a case where it has received the refrigerant leakage signal from the refrigerant leakage sensor 40c. That is, the refrigerant leakage discrimination flag F1 is set in a case where refrigerant leakage has occurred in the utilization unit 30a, the refrigerant leakage discrimination flag F2 is set in a case where refrigerant leakage has occurred in the utilization unit 30b, and the refrigerant leakage discrimination flag F3 is set in a case where refrigerant leakage has occurred in the utilization unit 30c.

The mode control unit <NUM> is a functional component that switches the control mode. The mode control unit <NUM> switches the control mode to the normal operating mode in a case where none of the refrigerant leakage discrimination flags F1, F2, and F3 is set. Specifically, the mode control unit <NUM> cancels the control mode discrimination flag F4 in a case where none of the refrigerant leakage discrimination flags F1, F2, and F3 is set.

On the other hand, the mode control unit <NUM> switches the control mode to the refrigerant leakage control mode when any of the refrigerant leakage discrimination flags F1, F2, and F3 is set. Specifically, the mode control unit <NUM> raises the control mode discrimination flag F4 when any of the refrigerant leakage discrimination flags F1, F2, and F3 is set.

The actuator control unit <NUM> controls the operation of each of the actuators (e.g., the compressor <NUM>, the on/off valves <NUM>, etc.) included in the refrigeration apparatus <NUM> (the heat source unit <NUM> and the utilization units <NUM>) in accordance with the situation in line with the control program. The actuator control unit <NUM> discriminates the control mode to which the controller <NUM> has transitioned by referencing the control mode discrimination flag F4 and controls the operation of each of the actuators on the basis of the control mode.

For example, in the normal operating mode, the actuator control unit <NUM> controls in real time the rotational speed of the compressor <NUM>, the rotational speeds of the heat source-side fan <NUM> and the utilization-side fans <NUM>, and the opening degrees of the heat source-side expansion valve <NUM> and the injection valve <NUM> in accordance with the set temperature and the detection values of the various types of sensors.

Furthermore, in the refrigerant leakage control mode, the actuator control unit <NUM> controls the operation of each of the actuators in such a way that predetermined operations are performed. Specifically, the operations performed in the refrigerant leakage control mode include a refrigerant recovery operation, a residual refrigerant quantity determination operation, and a fallback operation.

The refrigerant recovery operation is an operation that recovers, to the heat source unit <NUM> (particularly the heat source-side heat exchanger <NUM> and the receiver <NUM>), the refrigerant inside the utilization unit <NUM> in which refrigerant leakage has occurred (hereinafter called "the refrigerant-leaking utilization unit <NUM>") and the utilization units <NUM> in which refrigerant leakage has not occurred (hereinafter called "the operable utilization units <NUM>"). The residual refrigerant quantity determination operation is an operation for causing the refrigerant to circulate in the refrigerant circuit RC after the completion of the refrigerant recovery operation to determine the quantity of refrigerant (residual refrigerant quantity) remaining (i.e., not leaking) in the refrigerant circuit RC. The fallback operation is an operation that causes the compressor <NUM> to operate in accordance with the residual refrigerant quantity to cause the refrigeration cycle to continue in the operable utilization units <NUM>.

When the control mode discrimination flag F4 is raised (i.e., when the controller <NUM> transitions to the refrigerant leakage control mode), the actuator control unit <NUM> references the refrigerant leakage discrimination flags F1, F2, and F3 to identify the refrigerant-leaking utilization unit <NUM>. Then, the actuator control unit <NUM> controls, to the closed state, the on/off valve <NUM> corresponding to the refrigerant-leaking utilization unit <NUM> (the utilization unit <NUM> in which the refrigerant leakage has been detected). As a result, as regards the utilization unit <NUM> in which the refrigerant leakage is occurring, the flow of inflowing refrigerant is cut off so that the refrigerant is no longer supplied. For this reason, further refrigerant leakage is restrained.

Furthermore, the actuator control unit <NUM> also controls, to the closed state, the on/off valves <NUM> corresponding to each of the operable utilization units <NUM> (the utilization units <NUM> in which refrigerant leakage has not been detected). Then, the actuator control unit <NUM> causes the compressor <NUM> to be driven at a predetermined rotational speed for the refrigerant recovery operation. Because of this, the refrigerant recovery operation is started and the refrigerant inside each of the utilization units <NUM> is recovered to the heat source unit <NUM>. It will be noted that in the present embodiment the rotational speed of the compressor <NUM> in the refrigerant recovery operation is set to the maximum rotational speed so that the refrigerant recovery is completed in the shortest amount of time.

The actuator control unit <NUM> ends the refrigerant recovery operation when a state is reached in which it is assumed that the refrigerant recovery has been completed (specifically, a state in which the suction pressure LP is less than a predetermined threshold value ΔTh) after the start of the refrigerant recovery operation. It will be noted that the threshold value ΔTh is set to a value that is not enough to fall below atmospheric pressure on the basis of the quantity of refrigerant contained inside the refrigerant circuit RC and the quantity of refrigerant in circulation determined from the characteristics of the compressor <NUM>. In the present embodiment, the threshold value ΔTh is set to <NUM> MPa.

Next, the actuator control unit <NUM> switches, to the open state, the on/off valves <NUM> corresponding to the operable utilization units <NUM> (the utilization units <NUM> that are not leaking refrigerant). Thereafter, the actuator control unit <NUM> causes the compressor <NUM> to operate at a predetermined rotational speed for the residual refrigerant quantity determination operation. Because of this, the residual refrigerant quantity determination operation is started. Specifically, the refrigerant is sent from the heat source unit <NUM> to the operable utilization units <NUM>, and the refrigerant circulates in the refrigerant circuit RC.

It will be noted that in the present embodiment the actuator control unit <NUM> causes the compressor <NUM> to stop temporarily before causing the residual refrigerant quantity determination operation to start after the refrigerant recovery operation. This is to prevent damage to joint sections of refrigerant pipes and devices caused by an abrupt change in the pressure inside the refrigerant circuit RC in a case where the actuator control unit <NUM> has switched the on/off valves <NUM> from the closed state to the open state in a state in which the compressor <NUM> is operating.

Furthermore, in the residual refrigerant quantity determination operation, the actuator control unit <NUM> causes the on/off valve <NUM> corresponding to the refrigerant-leaking utilization unit <NUM> to maintain its closed state without switching to the open state. Because of this, the refrigerant is not supplied to the refrigerant-leaking utilization unit <NUM>, so further refrigerant leakage from the refrigerant-leaking utilization unit <NUM> is restrained.

In the residual refrigerant quantity determination operation, the actuator control unit <NUM> determines the residual refrigerant quantity by comparing the detection value (the suction pressure LP) of the suction pressure sensor <NUM> with a predetermined pressure standard value SP at a predetermined timing. In the present embodiment, the actuator control unit <NUM> is configured to determine the residual refrigerant quantity upon the elapse of a predetermined amount of time t1 after the start of the residual refrigerant quantity determination operation. The predetermined amount of time t1 is appropriately set in accordance with the design specifications and installation environment, and, for example, is set to three minutes.

Here, the pressure standard value SP is decided in accordance with the detection values of the receiver outlet temperature sensor <NUM> and the heat source-side air temperature sensor <NUM>, the quantity of refrigerant in circulation determined from the characteristics of the compressor <NUM>, the Cv value of the heat source-side expansion valve <NUM>, and the pipe lengths of the various types of refrigerant pipes, and a pressure standard value table (not shown in the drawings) in which pressure standard values SP by situation are defined is stored in the storage component <NUM>. The actuator control unit <NUM> decides the pressure standard value SP on the basis of the pressure standard value table. Additionally, the actuator control unit <NUM> determines the extent of the deficiency (gas deficiency) in the residual refrigerant quantity by comparing the suction pressure LP with the decided pressure standard value SP.

Thereafter, the actuator control unit <NUM> causes the compressor <NUM> to operate at a rotational speed according to the determination result (a rotational speed for the fallback operation). Because of this, the fallback operation is started. As a result, a refrigeration cycle using the residual refrigerant is performed between the heat source unit <NUM> and the operable utilization units <NUM>. For this reason, refrigeration of refrigerated products (particularly food products requiring temperature management) in the interior spaces where the operable utilization units <NUM> are installed is continued, so that deterioration is restrained. Furthermore, at this time, the on/off valve <NUM> of the refrigerant-leaking utilization unit <NUM> is maintained in the closed state without being switched to the open state, so it is also possible to perform repair work on the refrigerant-leaking utilization unit <NUM> while the operable utilization units <NUM> perform the fallback operation.

Furthermore, in the fallback operation, the compressor <NUM> is operated at a predetermined rotational speed that has been appropriately determined in accordance with the residual refrigerant quantity. Because of this, a failure of the compressor <NUM> is restrained. It will be noted that a fallback operation table (not shown in the drawings) in which rotational speeds of the compressor <NUM> in the fallback operation are defined is stored in the storage component <NUM>, and the actuator control unit <NUM> decides the rotational speed of the compressor <NUM> in the fallback operation by referencing the fallback operation table.

The display control unit <NUM> is a functional component that controls the operation of the remote controllers <NUM> serving as display devices. The display control unit <NUM> causes the remote controllers <NUM> to output predetermined information in order to display information pertaining to the operating state and situation to the manager. For example, during the refrigeration operation in the normal mode, the display control unit <NUM> causes the remote controllers <NUM> to display various types of information such as the set temperature. Furthermore, in the refrigerant leakage control mode, the display control unit <NUM> causes the remote controllers <NUM> to display information (notification information) specifically indicating that refrigerant leakage is occurring and the refrigerant-leaking utilization unit <NUM>. Furthermore, in the refrigerant recovery operation in the refrigerant leakage control mode, the display control unit <NUM> causes the remote controllers <NUM> to display notification information indicating that the refrigerant recovery operation is being performed. Furthermore, in the fallback operation in the refrigerant leakage control mode, the display control unit <NUM> causes the remote controllers <NUM> to display notification information indicating that the fallback operation is being performed in the operable utilization units <NUM> and information urging that a service technician be notified.

An example of a flow of processes executed by the controller <NUM> will be described with reference to <FIG> is a flowchart showing an example of a flow of processes executed by the controller <NUM>.

When the controller <NUM> is powered on, the controller <NUM> performs processes in the flow shown in steps S101 to S117 in <FIG>. In <FIG>, processes pertaining to the normal operating mode are shown in steps S102 to S104, and processes pertaining to the refrigerant leakage control mode are shown in steps S105 to S116. More specifically, <FIG> shows the refrigeration operation being performed in step S104, the refrigerant recovery operation being performed in steps S106 to S110, the residual refrigerant quantity determination operation being performed in steps S112 to S114, and the fallback operation being performed in step S115.

It will be noted that the flow of processes shown in <FIG> is an example and can be appropriately changed. For example, the order of the steps may be changed to the extent that there are no incompatibilities, and some steps may be executed in parallel with other steps.

In step S101, in a case where the controller <NUM> is receiving the refrigerant leakage signal from any of the refrigerant leakage sensors <NUM> (i.e., a case where it is assumed that refrigerant leakage is occurring in any of the utilization units <NUM>), the controller <NUM> proceeds to step S105. On the other hand, in a case where the controller <NUM> is not receiving the refrigerant leakage signal from any of the refrigerant leakage sensors <NUM> (i.e., a case where it is assumed that refrigerant leakage is not occurring in any of the utilization units <NUM>), the controller <NUM> proceeds to step S102.

In step S102, the controller <NUM> transitions to the normal operating mode. Thereafter, the controller <NUM> proceeds to step S103.

In step S103, in a case where a command to operate (an instruction to start operating) has not been input, the controller <NUM> returns to step S101. On the other hand, in a case where a command to operate has been input, the controller <NUM> proceeds to step S104.

In step S104, the controller <NUM> controls in real time the states of each of the actuators and causes the refrigeration operation to be performed in accordance with the set temperature that has been set and the detection values of the various types of sensors (<NUM> to <NUM>). Furthermore, the controller <NUM> causes the remote controllers <NUM> to display various types of information such as the set temperature. Thereafter, the controller <NUM> returns to step S101.

In step S105, the controller <NUM> transitions to the refrigerant leakage control mode in accordance with having received the refrigerant leakage signal. Thereafter, the controller <NUM> proceeds to step S106.

In step S106, the controller <NUM> identifies the refrigerant-leaking utilization unit <NUM> in accordance with the statuses of the refrigerant leakage discrimination flags F1, F2, and F3. Then, the controller <NUM> controls to the closed state the on/off valve <NUM> of the refrigerant-leaking utilization unit <NUM> that it has identified. Because of this, the inflow of the refrigerant to the refrigerant-leaking utilization unit <NUM> stops. Furthermore, the controller <NUM> causes the remote controllers <NUM> to display information specifically indicating that refrigerant leakage is occurring and the refrigerant-leaking utilization unit <NUM>. Thereafter, the controller <NUM> proceeds to step S107.

In step S107, the controller <NUM> controls to the closed state the on/off valves <NUM> of the operable utilization units <NUM>. Thereafter, the controller <NUM> proceeds to step S108.

In step S108, the controller <NUM> causes the compressor <NUM> to operate at the rotational speed for the refrigerant recovery operation (maximum rotational speed). Because of this, the refrigerant recovery operation is started and the refrigerant inside the refrigerant-leaking utilization unit <NUM> and the operable utilization units <NUM> is recovered to the heat source unit <NUM>. Thereafter, the controller <NUM> proceeds to step S109.

In step S109, the controller <NUM> determines whether or not the suction pressure LP is less than the threshold value ΔTh. In a case where the result of the determination is that the suction pressure LP is equal to or greater than the threshold value ΔTh, the controller <NUM> repeats the determination in step S109. On the other hand, in a case where the suction pressure LP is less than the threshold value ΔTh, the controller <NUM> proceeds to step S110.

In step S110, the controller <NUM> stops the compressor <NUM> and causes the refrigerant recovery operation to end due to the suction pressure LP having become less than the threshold value ΔTh and a state having been reached in which it is assumed that the refrigerant recovery to the heat source unit <NUM> has been completed. Thereafter, the controller <NUM> proceeds to step S111.

In step S111, in a case where a command to operate (an instruction to start operating) has not been input in relation to the operable utilization units <NUM>, the controller <NUM> stands by in step S111. On the other hand, in a case where a command to operate has been input, the controller <NUM> proceeds to step S112.

In step S112, the controller <NUM> controls to the open state the on/off valves <NUM> of the operable utilization units <NUM>. Thereafter, the controller <NUM> proceeds to step S113.

In step S113, the controller <NUM> causes the compressor <NUM> to operate at the rotational speed for the residual refrigerant quantity determination operation. Because of this, the residual refrigerant quantity determination operation is started, and the refrigerant circulates between the heat source unit <NUM> and the operable utilization units <NUM>. Thereafter, the controller <NUM> proceeds to step S114.

In step S114, the controller <NUM> performs the residual refrigerant quantity determination. Specifically, the controller <NUM> decides the pressure standard value SP on the basis of the pressure standard value table and determines the extent of the deficiency (gas shortage) in the residual refrigerant quantity by comparing the suction pressure LP with the pressure standard value SP it has decided. Thereafter, the controller <NUM> proceeds to step S115.

In step S115, the controller <NUM> causes the compressor <NUM> to operate at the rotational speed according to the result of the residual refrigerant quantity determination (the rotational speed for the fallback operation). Because of this, the fallback operation is started and a refrigeration cycle using the residual refrigerant is performed between the heat source unit <NUM> and the operable utilization units <NUM>. Furthermore, the controller <NUM> causes the remote controllers <NUM> to display this information. Thereafter, the controller <NUM> proceeds to step S116.

In step S116, in a case where a command to stop operating (an instruction to stop operating) has not been input in relation to the operable utilization units <NUM>, the controller <NUM> returns to step S115. On the other hand, in a case where a command to stop operating has been input in relation to the operable utilization units <NUM>, the controller <NUM> proceeds to step S117.

In step S117, the controller <NUM> stops the compressor <NUM> and causes the fallback operation to end. Thereafter, the controller <NUM> returns to step S111.

Changes in states according to the situation of the on/off valves <NUM> and the compressor <NUM> will be described below. <FIG> is a timing chart showing an example of changes in the states of the on/off valves <NUM> and the compressor <NUM> at the time of operation. <FIG> shows each part being controlled in the normal operating mode in period A and being controlled in the refrigerant leakage control mode in periods B to F.

In period A, the controller <NUM> performs control in the normal operating mode, and the on/off valves <NUM> of each of the utilization units <NUM> are controlled to the open state. Furthermore, the compressor <NUM> is controlled to a state in which it operates at the predetermined rotational speed for the refrigeration operation (a rotational speed according to the set temperature and the load), and the refrigeration operation is performed.

In period B, the controller <NUM> transitions to the refrigerant leakage control mode in response to having received the refrigerant leakage signal from the refrigerant leakage sensor 40a (i.e., in response to refrigerant leakage having occurred in the utilization unit 30a). As a result, the on/off valve <NUM> of the utilization unit (refrigerant-leaking utilization unit) 30a is controlled to the closed state. Because of this, the flow of refrigerant flowing into the utilization unit 30a is cut off so that the refrigerant is no longer supplied, and further refrigerant leakage is restrained.

Furthermore, each of the on/off valves <NUM> of the utilization units (operable utilization units) 30b and 30c is also controlled to the closed state, the compressor <NUM> is controlled to a state in which it operates at the predetermined rotational speed for the refrigerant recovery operation (here, the maximum rotational speed), and the refrigerant recovery operation is performed.

In period C, in response to the suction pressure LP having become less than the threshold value ΔTh (i.e., in response to a situation having been reached where it is assumed that the refrigerant recovery has been completed) after the start of the refrigerant recovery operation, the compressor <NUM> is controlled to a stopped state and the refrigerant recovery operation ends.

In period D, each of the on/off valves <NUM> of the utilization units (operable utilization units) 30b and 30c is controlled to the open state. In this way, each of the on/off valves <NUM> is controlled to the open state in a state in which the compressor <NUM> is stopped, so damage to refrigerant pipes and devices caused by an abrupt pressure fluctuation inside the refrigerant circuit RC is restrained. It will be noted that the on/off valve <NUM> of the utilization unit (refrigerant-leaking utilization unit) 30a remains controlled to the closed state.

In period E, in a state in which each of the on/off valves <NUM> of the utilization units (operable utilization units) 30b and 30c is controlled to the open state, the compressor <NUM> is controlled to a state in which it operates at the predetermined rotational speed for the residual refrigerant quantity determination operation, and the residual refrigerant quantity determination operation is performed. That is, the refrigerant circulates between the heat source unit <NUM> and the operable utilization units <NUM>.

In period F, in a state in which each of the on/off valves <NUM> of the utilization units (operable utilization units) 30b and 30c is controlled to the open state, the compressor <NUM> is controlled to a state in which it operates at the predetermined rotational speed for the fallback operation, and the fallback operation is performed. As a result, the refrigeration cycle is performed between the heat source unit <NUM> and the operable utilization units <NUM>, refrigeration of the refrigerated products in the interior spaces where the operable utilization units <NUM> are installed is continued, so that deterioration of the products is restrained.

(<NUM>-<NUM>)
In the refrigeration apparatus <NUM> pertaining to the above embodiment, in a case where the refrigerant leakage sensors <NUM> have detected refrigerant leakage in any of the utilization units <NUM>, the controller <NUM> transitions to the refrigerant leakage control mode, controls to the closed state the on/off valve <NUM> disposed on the inlet side of the utilization-side heat exchanger <NUM> of the utilization unit <NUM> in which the refrigerant leakage has been detected, and causes the compressor <NUM> to operate at the predetermined rotational speed. Due to this, the supply of the refrigerant to the refrigerant-leaking utilization unit <NUM> is stopped. As a result, even in a case where refrigerant leakage has occurred in any of the utilization units <NUM>, an increase in the quantity of leaking refrigerant is restrained.

Furthermore, the compressor <NUM> is configured so as to be operated in a state in which the on/off valve <NUM> disposed on the inlet side of the utilization-side heat exchanger <NUM> of the refrigerant-leaking utilization unit <NUM> is closed. For this reason, the refrigerant remaining inside the refrigerant-leaking utilization unit <NUM> is recovered to the heat source unit <NUM>, so that an increase in the quantity of leaking refrigerant is restrained.

Thus, the concentration of leaking refrigerant is restrained from becoming greater in the interior space where the refrigerant-leaking utilization unit <NUM> is installed, and so security is excellent.

(<NUM>-<NUM>)
In the refrigeration apparatus <NUM> pertaining to the above embodiment, in the refrigerant leakage control mode, the controller <NUM> controls, to a predetermined opening degree for the refrigerant recovery operation, the on/off valves <NUM> disposed on the inlet sides of the utilization-side heat exchangers <NUM> of the operable utilization units <NUM> in which the refrigerant leakage has not been detected.

Due to this, the refrigerant inside each of the utilization units <NUM> including the refrigerant-leaking utilization unit <NUM> is recovered to the heat source unit <NUM>. As a result, a situation where the refrigerant flows into the refrigerant-leaking utilization unit <NUM> from the operable utilization units <NUM> so that the quantity of leaking refrigerant increases is restrained, and so security is excellent.

(<NUM>-<NUM>)
In the refrigeration apparatus <NUM> pertaining to the above embodiment, the check valves <NUM> that cut off the flow of the refrigerant from the outlet sides to the inlet sides are disposed on the refrigerant outlet sides of the utilization-side heat exchangers <NUM> of the utilization units <NUM>. Additionally, when it is assumed that the recovery of the refrigerant from each of the utilization-side heat exchangers <NUM> to the heat source unit <NUM> has been completed in the refrigerant leakage control mode, the controller <NUM> causes the fallback operation of the compressor <NUM> to be performed and controls, to a predetermined opening degree for the fallback operation, the on/off valves <NUM> disposed on the inlet sides of the utilization-side heat exchangers <NUM> of the operable utilization units <NUM>.

Due to this, the compressor <NUM> is fallback-operated and the refrigeration cycle is performed in the operable utilization units <NUM> even in a case where refrigerant leakage has occurred in any of the utilization units <NUM>. Thus, deterioration of the products requiring temperature management is restrained in the interior spaces where the operable utilization units <NUM> are disposed.

(<NUM>-<NUM>)
The refrigeration apparatus <NUM> pertaining to the above embodiment is equipped with the remote controllers <NUM> whose operation is controlled by the controller <NUM> and which output information, and in the refrigerant leakage control mode, the controller <NUM> causes the remote controllers <NUM> to output the predetermined notification information.

Due to this, in a case where refrigerant leakage has occurred in the utilization units <NUM>, the notification information identifying the fact that refrigerant leakage has occurred and the utilization unit <NUM> in which the refrigerant leakage is occurring is output. As a result, in a case where refrigerant leakage has occurred in any of the utilization units <NUM>, the manager easily becomes aware of this and is urged to take action, so security is even more excellent.

The above embodiment can be appropriately modified as described in the following modifications. It will be noted that each modification may also be combined with another modification and applied to the extent that incompatibilities do not arise.

In the above embodiment, the on/off valves <NUM> were disposed, as the "inlet valves" that cut off the flow of the refrigerant flowing into the utilization units <NUM>, on the refrigerant inlet sides of the utilization-side heat exchangers <NUM> in the utilization units <NUM>. However, the disposition (position) of the on/off valves <NUM> is not invariably limited to this and can be appropriately changed in accordance with the design specifications and installation environment.

For example, the on/off valves <NUM> may also be disposed as shown in <FIG> shows the general configuration of a refrigeration apparatus 100a having a refrigerant circuit RC1 where the disposition (position) of the on/off valves <NUM> is different from what it is in the refrigerant circuit RC.

In the refrigerant circuit RC1, the on/off valves <NUM> are disposed outside the utilization units <NUM> rather than inside the utilization units <NUM>. More specifically, in the refrigerant circuit RC1, the on/off valves <NUM> are disposed in the sections of the utilization-side liquid refrigerant pipes P5 that extend outside the utilization units <NUM> (that is to say, disposed between the utilization units <NUM> and the liquid refrigerant communication pipe L1). That is, in the refrigeration apparatus <NUM>, the on/off valves <NUM> were included among the constituent elements of the utilization units <NUM>, but the on/off valves <NUM> in the refrigeration apparatus 100a are disposed as elements independent of the utilization units <NUM> in the refrigerant circuit RC1.

Even in the refrigeration apparatus 100a having the refrigerant circuit RC1 instead of the refrigerant circuit RC, the on/off valves <NUM> are disposed on the refrigerant inlet sides of the utilization-side heat exchangers <NUM> and can cut off the flow of the refrigerant flowing into the utilization units <NUM>. For this reason, the same effects as those of the refrigeration apparatus <NUM> can be achieved.

In the above embodiment, the on/off valves <NUM> were disposed, as the "inlet valves" that cut off the flow of the refrigerant flowing into the utilization units <NUM>, on the refrigerant inlet sides of the utilization-side heat exchangers <NUM> in the utilization units <NUM>. However, the on/off valves <NUM> can also be appropriately omitted in accordance with the design specifications and installation environment.

For example, the on/off valves <NUM> may also be omitted from the refrigerant circuit RC, being disposed as in a refrigerant circuit RC2 shown in <FIG> shows the general configuration of a refrigeration apparatus 100b having a refrigerant circuit RC2 where the on/off valves <NUM> are omitted.

In the refrigerant circuit RC2, utilization-side electronic expansion valves 31a are disposed instead of the thermostatic utilization-side expansion valves <NUM>. The utilization-side electronic expansion valves 31a are electrically powered valves capable of opening degree adjustment in which their opening degrees change as a result of a predetermined drive voltage being supplied. The controller <NUM> appropriately adjusts the opening degrees of the utilization-side electronic expansion valves 31a, so that the same effects as those of the refrigeration apparatus <NUM> can be achieved.

That is, by replacing the closed state of each of the on/off valves <NUM> in the timing chart in <FIG> with a minimum opening degree (totally closed state) of the utilization-side electronic expansion valves 31a, the utilization-side electronic expansion valves 31a can function as the "inlet valves" in the same way as the on/off valves <NUM> to cut off the flow of the refrigerant flowing into the refrigerant-leaking utilization unit <NUM>. Furthermore, the refrigeration apparatus 100b can also, like the refrigeration apparatus <NUM>, perform the refrigeration operation, the refrigerant recovery operation, the residual refrigerant quantity determination operation, and the fallback operation.

In the refrigeration apparatus 100b, it is not invariably necessary for the controller <NUM> to cause the compressor <NUM> to stop before switching the utilization-side electronic expansion valves 31a of the operable utilization units <NUM> from the minimum opening degree to the open state after the end of the refrigerant recovery operation. This is because, since the utilization-side electronic expansion valves 31a are electrically powered valves whose opening degrees can be adjusted, even without causing the compressor <NUM> to stop it is possible to prevent an abrupt pressure fluctuation inside the refrigerant circuit RC2 by gradually increasing the opening degrees, so that damage to refrigerant pipes and devices is restrained.

Furthermore, in the refrigeration apparatus <NUM>, the on/off valves of the operable utilization units <NUM> were controlled to the closed state in the refrigerant recovery operation, but in the refrigeration apparatus 100b, the utilization-side electronic expansion valves 31a of the operable utilization units <NUM> do not invariably need to be controlled to the minimum opening degree in the refrigerant recovery operation. That is, it suffices for the opening degree of the utilization-side electronic expansion valves 31a to be set to an opening degree (e.g., a minute opening degree) at which the refrigerant can be recovered from the utilization units <NUM> to the heat source unit <NUM>.

In the above embodiment, the check valves <NUM> were disposed, as the "outlet valves" that prevent the inflow of the refrigerant from the outlet sides to the inlet sides, in the refrigerant outlet sides of the utilization-side heat exchangers <NUM>. However, instead of the check valves <NUM>, electromagnetic valves or electrically powered valves may also be disposed. The electromagnetic valves or the electrically powered valves are controlled to the closed state or the minimum opening degree (totally closed state) in the refrigerant recovery operation, the residual refrigerant quantity determination operation, and the fallback operation, so that further refrigerant leakage in the refrigerant-leaking utilization unit <NUM> can be restrained and the fallback operation can be performed in the operable utilization units <NUM>. That is, in this case, the electromagnetic valves or the electrically powered valves disposed instead of the check valves <NUM> function as the "outlet valves".

In the above embodiment, the controller <NUM> caused the compressor <NUM> to stop before switching the on/off valves <NUM> of the operable utilization units <NUM> from the closed state to the open state after the end of the refrigerant recovery operation. In this regard, according to the standpoint of preventing damage to refrigerant pipes and devices caused by an abrupt pressure fluctuation inside the refrigerant circuit RC, it is preferred that the controller <NUM> cause the compressor <NUM> to stop temporarily at this timing. However, in a situation where security is ensured even without causing the compressor <NUM> to stop, it is not invariably necessary for the controller <NUM> to cause the compressor <NUM> to stop at this timing. For example, in a case where there is no concern that there will be damage to refrigerant pipes and devices by setting low the rotational speed of the compressor <NUM> at this timing, it is alright if the controller <NUM> does not cause the compressor <NUM> to stop.

In the above embodiment, the controller <NUM> performed the residual refrigerant quantity determination operation after the end of the refrigerant recovery operation. In this regard, when performing the fallback operation in the operable utilization units <NUM> in a case where refrigerant leakage has occurred in any of the utilization units <NUM>, it is preferred from the standpoint of security that the controller <NUM> cause the compressor <NUM> to operate at a rotational speed according to the quantity of refrigerant remaining in the refrigerant circuit RC. However, in the case of a situation where security is ensured even without the controller <NUM> performing the residual refrigerant quantity determination, it is not invariably necessary for the controller <NUM> to perform the residual refrigerant quantity determination operation at this timing, and the residual refrigerant quantity determination operation can also be appropriately omitted.

Furthermore, the controller <NUM> may also be configured in such a way that, rather than performing the residual refrigerant quantity determination operation independently, the residual refrigerant quantity determination operation is performed during the fallback operation.

In the above embodiment, the controller <NUM> that controls the operation of the refrigeration apparatus <NUM> was configured as a result of the heat-source-unit control unit <NUM> and the utilization-unit control units <NUM> being interconnected via the communication line cb1. However, the configuration of the controller <NUM> is not invariably limited to this and can be appropriately changed in accordance with the design specifications and installation environment. For example, some or all of the elements (the storage component <NUM>, the communication component <NUM>, the mode control unit <NUM>, the actuator control unit <NUM>, and the display control unit <NUM>) included in the controller <NUM> do not invariably need to be disposed in either of the heat source unit <NUM> and the utilization units <NUM>, and may also be disposed in a separate device or may also be disposed independently in a remote location connected by a communication network. That is, the configuration of the controller <NUM> is not particularly limited so long as the elements (the storage component <NUM>, the communication component <NUM>, the mode control unit <NUM>, the actuator control unit <NUM>, and the display control unit <NUM>) included in the controller <NUM> can be constructed.

In the above embodiment, the refrigerant recovery operation was configured to end based on the assumption that the refrigerant recovery has been completed when the detection value (suction pressure LP) of the suction pressure sensor <NUM> becomes less than the predetermined threshold value ΔTh (see step S109 and step S110 in <FIG>). However, the basis for ending the refrigerant recovery operation can also be appropriately changed in accordance with the design specifications and installation environment.

For example, the refrigerant recovery operation may also be configured to end based on the assumption that the refrigerant recovery has been completed when the detection value (the discharge pressure HP) of the discharge pressure sensor <NUM> becomes less than a predetermined value.

Furthermore, for example, the refrigerant recovery operation may also be configured to end based on the assumption that the refrigerant recovery has been completed when a predetermined amount of time set beforehand has elapsed after the start of the refrigerant recovery operation.

In the above embodiment, the threshold value ΔTh was set to a value that is not enough to fall below atmospheric pressure on the basis of the quantity of refrigerant contained inside the refrigerant circuit RC and the quantity of refrigerant in circulation determined from the characteristics of the compressor <NUM>, and was set to <NUM> MPa. However, the threshold value ΔTh is not invariably limited to <NUM> MPa, and it suffices for an appropriate value to be set in accordance with the design specifications and installation environment.

In the above embodiment, in the residual refrigerant quantity determination operation, the controller <NUM> determined the residual refrigerant quantity by comparing the detection value (the suction pressure LP) of the suction pressure sensor <NUM> with the predetermined pressure standard value SP. However, the method by which the controller <NUM> determines the residual refrigerant quantity is not invariably limited to this and can be appropriately changed. For example, the controller <NUM> may also be configured to determine the residual refrigerant quantity by comparing the detection value (the discharge pressure HP) of the discharge pressure sensor <NUM> with the predetermined pressure standard value SP.

In the above embodiment, the rotational speed of the compressor <NUM> in the refrigerant recovery operation was set to the maximum rotational speed so that the refrigerant recovery is completed in the shortest amount of time. However, the rotational speed of the compressor <NUM> in the refrigerant recovery operation is not invariably limited to this and can be appropriately changed in accordance with the design specifications and installation environment.

In the above embodiment, the fallback operation was performed after the residual refrigerant quantity determination operation, and in the fallback operation the compressor <NUM> was configured to operate at a rotational speed commensurate with the residual refrigerant quantity. In this regard, for example, in a case where plural compressors <NUM> are disposed in the refrigerant circuit RC, capacity may also be saved by limiting the number of the compressors <NUM> that the controller <NUM> causes to operate in the fallback operation.

Furthermore, for example, a tank charged with refrigerant for replenishment may also be connected beforehand to the refrigerant circuit RC, and the refrigerant circuit RC may be configured in such a way that it becomes appropriately replenished with a quantity of refrigerant corresponding to the deficiency before the fallback operation or during the fallback operation.

In the above embodiment, the controller <NUM> was configured to determine the residual refrigerant quantity upon the elapse of the predetermined amount of time t1 after the start of the residual refrigerant quantity determination operation, and the predetermined amount of time t1 was set to three minutes. However, the predetermined amount of time t1 is not invariably limited to three minutes and can be appropriately changed. For example, the predetermined amount of time t1 may also be set to one minute or may also be set to five minutes. Furthermore, rather than the controller <NUM> determining the residual refrigerant quantity upon the elapse of the predetermined amount of time t1 after the start of the residual refrigerant quantity determination operation, the controller <NUM> may also be changed in such a way that the residual refrigerant quantity is determined on the basis of another event.

In the above embodiment, the refrigerant leakage sensors <NUM> were disposed inside the utilization units <NUM>. However, the refrigerant leakage sensors <NUM> do not invariably need to be disposed inside the utilization units <NUM> provided that the refrigerant leakage sensors <NUM> are disposed in such a way that they can detect refrigerant leakage inside the corresponding utilization units <NUM>. For example, the refrigerant leakage sensors <NUM> may also be disposed in the spaces (interior spaces) where the corresponding utilization units <NUM> are installed.

In the above embodiment, the refrigerant leakage sensors <NUM> were disposed to detect refrigerant leakage in each of the utilization units <NUM>. However, in a case where it is possible to detect refrigerant leakage in each of the utilization units <NUM> without relying on the refrigerant leakage sensors <NUM>, the refrigerant leakage sensors <NUM> are not invariably necessary in the refrigeration apparatus <NUM>. For example, in a case where sensors such as refrigerant pressure sensors and/or refrigerant temperature sensors are disposed inside each of the utilization units <NUM> and it is possible to individually detect refrigerant leakage in each of the utilization units <NUM> on the basis of changes in the detection values of the sensors, the refrigerant leakage sensors <NUM> may also be omitted.

In the above embodiment, the controller <NUM> caused the remote controllers <NUM> serving as the "information output units" to output predetermined information in accordance with the operating situation. In particular, the controller <NUM> caused the remote controllers <NUM> to output predetermined notification information in the refrigerant recovery operation, the residual refrigerant quantity determination operation, and the fallback operation. In this regard, in a case where refrigerant leakage has occurred, the controller <NUM> may also cause devices other than the remote controllers <NUM> to function as the "information output units" so long as they can notify the manager.

For example, speakers capable of outputting audio may be disposed, and the controller <NUM> may cause the speakers to output a predetermined warning sound or audio message to thereby cause the speakers to output the notification information and function as the "information output units". Furthermore, light sources such as LED lamps may be disposed, and the controller <NUM> may cause the light sources to blink or light up to thereby cause the light sources to output the notification information and function as the "information output units". Furthermore, the controller <NUM> may also cause a device such as a central management device installed in the facility to which the refrigeration apparatus <NUM> is applied or a remote off-site location to output the notification information and function as the "information output units".

In the above embodiment, the present invention was applied to the refrigeration apparatus <NUM> that refrigerates interior spaces of refrigerated storage rooms or showcases in a store. However, the present invention is not limited to this and is also applicable to other refrigeration apparatuses having a refrigerant circuit having plural utilization units. For example, the present invention may also be applied to a refrigeration apparatus that refrigerates the insides of shipping containers. Furthermore, for example, the present invention may also be applied to an air conditioning system (air conditioner) that realizes air conditioning by cooling the inside of a building.

Furthermore, for example, by disposing a four-port switching valve in the refrigerant circuit RC in <FIG>, the utilization-side heat exchangers <NUM> may be caused to function as refrigerant radiators or condensers, so that the utilization units <NUM> are configured to perform a heat applying operation or a heating operation in the spaces where the utilization units <NUM> are installed.

In the above embodiment, the refrigeration apparatus <NUM> had one heat source unit <NUM> and three utilization units <NUM>. However, the number of the heat source units <NUM> disposed in the refrigeration apparatus <NUM> is not particularly limited and may also be two or more. Furthermore, the number of the utilization units <NUM> that the refrigeration apparatus <NUM> has is not particularly limited and may also be two or may also be four or more.

Furthermore, the number of the compressors <NUM> disposed in the refrigerant circuit RC was one, but the number of the compressors <NUM> is also not particularly limited, and two or more compressors <NUM> may also be disposed in accordance with the design specifications and installation environment.

Furthermore, in the above embodiment, a case was described where the utilization unit 30a was the refrigerant-leaking utilization unit and the utilization units 30b and 30c were the operable utilization units. However, the same effects as in the above embodiment are achieved even when a utilization unit other than the utilization unit 30a is the refrigerant-leaking utilization unit.

In the above embodiment, R32 was used as the refrigerant circulating through the refrigerant circuit RC. However, the refrigerant used in the refrigerant circuit RC is not particularly limited. For example, in the refrigerant circuit RC, HFO1234yf, HFO1234ze (E), or a mixed refrigerant including these refrigerants may also be used instead of R32. Furthermore, in the refrigerant circuit RC, an HFC refrigerant such as R407C or R410A may also be used. Furthermore, in the refrigerant circuit RC, a flammable refrigerant such as propane or a toxic refrigerant such as ammonia may also be used.

In the above embodiment, the controller <NUM> performed the refrigerant recovery operation and controlled the on/off valves <NUM> of the operable utilization units <NUM> to the closed state (step S107 in <FIG>). However, this control is not invariably necessary and can be omitted. Even in this case, the action and effects described in (<NUM>-<NUM>) above can be realized. That is, even in a case where the refrigerant recovery operation is performed in a state in which the on/off valves <NUM> of the operable utilization units <NUM> are controlled to the open state, so long as the on/off valve <NUM> of the refrigerant-leaking utilization unit <NUM> is controlled to the closed state, the inflow of the refrigerant to the refrigerant-leaking utilization unit <NUM> is stopped and the refrigerant in the refrigerant-leaking utilization unit <NUM> is recovered to the heat source unit <NUM>. Thus, an increase in the quantity of leaking refrigerant is restrained.

In the above embodiment, the operations performed in the refrigerant leakage control mode included the refrigerant recovery operation, the residual refrigerant quantity determination operation, and the fallback operation. However, the operations performed in the refrigerant leakage control mode may also include other operations instead of any of these operations or in addition to these operations.

For example, the controller <NUM> may also be configured in such a way that, in the refrigerant leakage control mode, instead of the refrigerant recovery operation, the residual refrigerant quantity determination operation, and the fallback operation, a continuity operation is performed in which the controller <NUM> causes the compressor <NUM> to operate continuously without the controller <NUM> particularly changing the rotational speed of the compressor <NUM> from what it is in the normal operating mode. In this continuity operation, the compressor <NUM> is operated at a random rotational speed according to the refrigerating load and so forth as in the normal operating mode.

In this case also, the action and effects described in (<NUM>-<NUM>) above can be realized. That is, in the continuity operation also, so long as the on/off valve <NUM> of the refrigerant-leaking utilization unit <NUM> is controlled to the closed state, the inflow of the refrigerant to the refrigerant-leaking utilization unit <NUM> is stopped so that an increase in the quantity of leaking refrigerant is restrained. Furthermore, when the operation of the compressor <NUM> is continued in a state in which the on/off valves <NUM> of the operable utilization units <NUM> are controlled to the open state, the refrigeration cycle is performed in the operable utilization units <NUM>, and deterioration of the products requiring temperature management is restrained in the interior spaces where the operable utilization units <NUM> are installed.

Claim 1:
A refrigeration apparatus (<NUM>, 100a, 100b) comprising:
a refrigerant circuit (RC, RC1, RC2) configured and arranged to include a heat source unit (<NUM>) which has a compressor (<NUM>), and a plurality of utilization units (<NUM>), each of which has a utilization-side heat exchanger (<NUM>) and which are disposed in parallel to each other;
a plurality of inlet valves (<NUM>, 31a) configured and arranged to cut off a flow of supplied refrigerant in a closed state; and
a control unit (<NUM>) configured and arranged to transition to a predetermined control mode in accordance with the situation and configured and arranged to control the operation of the compressor and each of the inlet valves in accordance with the control mode,
wherein
each of the inlet valves is disposed on a refrigerant inlet side of any of the utilization-side heat exchangers, and
the control unit is electrically connected to refrigerant leakage sensors (<NUM>) configured and arranged to detect refrigerant leakage inside each of the utilization units, the control unit is configured and arranged to transition to a refrigerant leakage control mode in a case where the refrigerant leakage sensors have detected refrigerant leakage in any of the utilization units, the refrigeration apparatus being characterized in that the control unit is configured and arranged to, in the refrigerant leakage control mode, perform a refrigerant recovery operation, and to control to the closed state the inlet valve disposed on the inlet side of the utilization-side heat exchanger of the utilization unit in which the refrigerant leakage has been detected, and to end the refrigerant recovery operation when a state is reached in which the suction pressure (LP) is less than a predetermined threshold value (ΔTh) after the start of the refrigerant recovery operation, the threshold value (ΔTh) being set to a value that does not fall below atmospheric pressure, and in that the control unit is further configured and arranged to, in the refrigerant leakage control mode, cause the compressor to operate at a predetermined rotational speed.