Patent Description:
<CIT> and <CIT> respectively disclose an air conditioner including a compressor unit, a heat source heat exchanger unit, and a utilization unit.

When an air conditioner has damage at a pipe or the like constituting a refrigerant circuit, refrigerant leakage might occur from the refrigerant circuit. The air conditioner disclosed in <CIT> includes a refrigerant circuit constituted by a single refrigerant cycle circuit, and therefore the entire refrigerant may leak from the refrigerant circuit. Accordingly requested is reduction in volume of a leaking refrigerant. Another refrigeration apparatus is disclosed in <CIT> forming the basis for the preamble of claim <NUM>. Further refrigeration apparatuses are disclosed in <CIT> and <CIT>.

A refrigeration apparatus according to a first aspect includes the features of claim <NUM>.

This configuration divides a refrigerant circuit constituted by the compressor unit into the first refrigerant cycle and the second refrigerant cycle. Both the first refrigerant and the second refrigerant are thus less likely to leak in a case where the refrigerant circuit has damage or the like, achieving reduction in volume of a leaking refrigerant.

Subsequently, refrigeration apparatuses according to a second to a fourteenth aspect are presented which comprise features which supplement the features of the first aspect.

A refrigeration apparatus according to a second aspect is defined in claim <NUM>.

The second refrigerant cycle in this configuration additionally includes the subcooling heat exchanger. This configuration is thus likely to secure subcooling in a utilization unit.

A refrigeration apparatus according to a third aspect is defined in claim <NUM>.

The compressor unit according to this configuration includes the leakage detection sensor. This enables quick detection of refrigerant leakage in an exemplary case where a vibration source such as a compressor damages the refrigerant circuit.

A refrigeration apparatus according to a fourth aspect is defined in claim <NUM>.

The first refrigerant cycle in this configuration includes the first shutoff valve. The first shutoff valve is shut off upon detection of refrigerant leakage, to inhibit a leaking refrigerant from reaching outside the compressor unit.

A refrigeration apparatus according to a fifth aspect is defined in claim <NUM>.

The control unit in this configuration automatically closes the first shutoff valve upon detection of refrigerant leakage. This enables quick shutoff of the refrigerant circuit.

A refrigeration apparatus according to a sixth aspect is defined in claim <NUM>.

The control unit is disposed outside the first case in this configuration. This enables effective release of heat generated by the control unit.

A refrigeration apparatus according to a seventh aspect is defined in claim <NUM>.

The control unit is cooled by the cooling refrigerant pipe in this configuration. This achieves effective cooling of the control unit that generates heat.

A refrigeration apparatus according to an eighth aspect is defined in claim <NUM>.

The leakage detection sensor is the refrigerant detection sensor in this configuration. This enables direct detection of refrigerant leakage.

A refrigeration apparatus according to a ninth aspect is defined in claim <NUM>.

The first case has airtightness in this configuration. This inhibits a refrigerant leaking in the first case from reaching outside the first case.

A refrigeration apparatus according to a tenth aspect is defined in claim <NUM>.

The leakage detection sensor is the pressure sensor in this configuration. When a refrigerant leaks in the first case having airtightness, refrigerant leakage can be detected in accordance with pressure change.

A refrigeration apparatus according to an eleventh aspect is defined in claim <NUM>.

The first case in this configuration includes the rupture disk. The rupture disk is thus destroyed to release abnormally increased pressure in the first case.

A refrigeration apparatus according to a twelfth aspect is defined in claim <NUM>.

The first refrigerant and the second refrigerant are natural refrigerants in this configuration.

A refrigeration apparatus according to a thirteenth aspect is defined in claim <NUM>.

The heat source heat exchanger unit in this configuration is invisible from outside the building. The refrigeration apparatus thus does not affect quality in outer appearance of the building.

A refrigeration apparatus according to a fourteenth aspect is defined in claim <NUM>.

In this configuration, each refrigerant pipe in the first refrigerant cycle and the second refrigerant cycle has a flow of a liquid refrigerant during heating operation. This reduces pressure loss of a refrigerant flow in each connection pipe.

<FIG> is a circuit diagram of a refrigeration apparatus <NUM> according to the first embodiment. The refrigeration apparatus <NUM> is typically exemplified by an air conditioner, but is not limited thereto. For example, the refrigeration apparatus <NUM> may be a refrigerator, a freezer, and a hot water supplier. The refrigeration apparatus <NUM> includes a heat source heat exchanger unit <NUM>, a compressor unit <NUM>, a first connection piping <NUM>, utilization units <NUM> and <NUM>, and a second connection piping <NUM>.

The heat source heat exchanger unit <NUM> is disposed outside a building B. The heat source heat exchanger unit <NUM> includes a case 10a, a heat source heat exchanger <NUM>, a heat source fan <NUM>, a heat source heat exchanger unit expansion valve <NUM>, and a heat source heat exchanger unit control unit <NUM>. The heat source heat exchanger unit <NUM> handles a first refrigerant R1.

The case 10a accommodates components constituting the heat source heat exchanger unit <NUM>. The case 10a is made of a metal or the like.

The heat source heat exchanger <NUM> functions as a heat source. The heat source heat exchanger <NUM> exchanges heat between air outside the building B and the first refrigerant R1. During cooling operation, the heat source heat exchanger <NUM> functions as a heat radiator (or a condenser) for the first refrigerant R1. During heating operation, the heat source heat exchanger <NUM> functions as a heat absorber (or an evaporator) for the first refrigerant R1.

The heat source fan <NUM> generates an air flow to promote heat exchange at the heat source heat exchanger <NUM>.

The heat source heat exchanger unit expansion valve <NUM> decompresses the first refrigerant R1. The heat source heat exchanger unit expansion valve <NUM> is configured to adjust its opening degree.

The heat source heat exchanger unit control unit <NUM> includes a microcomputer and a memory. The heat source heat exchanger unit control unit <NUM> controls the heat source fan <NUM>, the heat source heat exchanger unit expansion valve <NUM>, and the like. The memory stores software for control of these components.

The heat source heat exchanger unit control unit <NUM> transmits and receives data and a command, via a communication line (not depicted), to and from each of a compressor unit control unit <NUM> and a utilization unit control unit <NUM>, which will be described later.

The compressor unit <NUM> has external appearance depicted in <FIG>. As depicted in <FIG>, the compressor unit <NUM> is disposed inside the building B. The compressor unit <NUM> includes a case 20a, a first compressor <NUM>, a first four-way switching valve <NUM>, a first connecting port <NUM>, a cascade heat exchanger <NUM>, a second compressor <NUM>, a second four-way switching valve <NUM>, a compressor unit expansion valve <NUM>, a second connecting port <NUM>, a leakage detection sensor <NUM>, and the compressor unit control unit <NUM>. The compressor unit <NUM> handles the first refrigerant R1 and a second refrigerant R2.

The case 20a accommodates components constituting the compressor unit <NUM>. The case 20a is made of a metal or the like.

The first compressor <NUM> compresses the first refrigerant R1 that is sucked and is in a low-pressure gas state to obtain the first refrigerant R1 in a high-pressure gas state. The first compressor <NUM> includes a first compressor motor 21a. The first compressor motor 21a generates motive power necessary for compression.

The first compressor <NUM> is a vibration source and may thus cause refrigerant leakage from the first compressor <NUM> and a component adjacent thereto.

The first four-way switching valve <NUM> switches connection of a refrigerant circuit. During cooling operation, the first four-way switching valve <NUM> achieves connection depicted by solid lines in <FIG>. During heating operation, the first four-way switching valve <NUM> achieves connection depicted by broken lines in <FIG>.

The first connecting port <NUM> includes a pair of ports provided for connection of the first connection piping <NUM> to be described later. The first connecting port <NUM> is provided with a first liquid side shutoff valve 23a and a first gas side shutoff valve 23b. The first liquid side shutoff valve 23a and the first gas side shutoff valve 23b shut off a refrigerant flow path in response to a received command.

The cascade heat exchanger <NUM> includes two refrigerant flow paths and exchanges heat between the first refrigerant R1 and the second refrigerant R2. During cooling operation, the cascade heat exchanger <NUM> functions as a heat absorber (or an evaporator) for the first refrigerant R1, and as a heat radiator (or a condenser) for the second refrigerant R2. During heating operation, the cascade heat exchanger <NUM> functions as a heat radiator (or a condenser) for the first refrigerant R1, and as a heat absorber (or an evaporator) for the second refrigerant R2.

The second compressor <NUM> compresses the second refrigerant R2 that is sucked and is in a low-pressure gas state to obtain the second refrigerant R2 in a high-pressure gas state. The second compressor <NUM> includes a second compressor motor 25a. The second compressor motor 25a generates motive power necessary for compression.

The second compressor <NUM> is a vibration source and may thus cause refrigerant leakage from the second compressor <NUM> and a component adjacent thereto.

The second four-way switching valve <NUM> switches connection of the refrigerant circuit. During cooling operation, the second four-way switching valve <NUM> achieves the connection depicted by the solid lines in <FIG>. During heating operation, the second four-way switching valve <NUM> achieves the connection depicted by the broken lines in <FIG>.

The compressor unit expansion valve <NUM> decompresses the second refrigerant R2. The compressor unit expansion valve <NUM> is configured to adjust its opening degree.

The second connecting port <NUM> includes a pair of ports provided for connection of the second connection piping <NUM> to be described later. The second connecting port <NUM> is provided with a second liquid side shutoff valve 28a and a second gas side shutoff valve 28b. The second liquid side shutoff valve 28a and the second gas side shutoff valve 28b shut off the refrigerant flow path in response to a received command.

The leakage detection sensor <NUM> detects refrigerant leakage. The leakage detection sensor <NUM> is a refrigerant detection sensor 61a configured to detect presence of at least one of the first refrigerant R1 or the second refrigerant R2.

The compressor unit control unit <NUM> includes a microcomputer and a memory. The compressor unit control unit <NUM> controls the first compressor motor 21a, the first four-way switching valve <NUM>, the first liquid side shutoff valve 23a, the first gas side shutoff valve 23b, the second compressor motor 25a, the second four-way switching valve <NUM>, the compressor unit expansion valve <NUM>, the second liquid side shutoff valve 28a, the second gas side shutoff valve 28b, and the like. The compressor unit control unit <NUM> receives a signal from the leakage detection sensor <NUM>. The memory stores software for control of these components.

The compressor unit control unit <NUM> transmits and receives data and a command, via a communication line (not depicted), to and from each of the heat source heat exchanger unit control unit <NUM> and the utilization unit control unit <NUM> to be described later.

The first connection piping <NUM> connects the heat source heat exchanger unit <NUM> and the compressor unit <NUM>. The first connection piping <NUM> includes a first liquid connection pipe <NUM> and a first gas connection pipe <NUM>.

The first liquid connection pipe <NUM> connects the heat source heat exchanger unit <NUM> and the first liquid side shutoff valve 23a. The first liquid connection pipe <NUM> guides the first refrigerant R1 principally in a high-pressure liquid state or in a low-pressure gas-liquid two-phase state.

The first gas connection pipe <NUM> connects the heat source heat exchanger unit <NUM> and the first gas side shutoff valve 23b. The first gas connection pipe <NUM> guides the first refrigerant R1 principally in the high-pressure gas state or in the low-pressure gas state.

The utilization units <NUM> and <NUM> each have external appearance depicted in <FIG>. As depicted in <FIG>, the utilization units <NUM> and <NUM> are disposed inside the building B. The utilization units <NUM> and <NUM> handle the second refrigerant R2. The utilization unit <NUM> and the utilization unit <NUM> are configured identically to each other. The following description will thus be made to only the utilization unit <NUM> without repetitively describing the utilization unit <NUM>. The utilization unit <NUM> includes a case 50a, a utilization unit expansion valve <NUM>, a utilization heat exchanger <NUM>, a utilization fan <NUM>, and the utilization unit control unit <NUM>.

The case 50a accommodates components constituting the utilization unit <NUM>.

The utilization unit expansion valve <NUM> decompresses the second refrigerant R2. The utilization unit expansion valve <NUM> limits a flow rate of the second refrigerant R2. The utilization unit expansion valve <NUM> is configured to adjust its opening degree.

The utilization heat exchanger <NUM> provides a user with low temperature heat or high temperature heat. The utilization heat exchanger <NUM> exchanges heat between air inside the building B and the second refrigerant R2. During cooling operation, the utilization heat exchanger <NUM> functions as a heat absorber (or an evaporator) for the second refrigerant R2. During heating operation, the utilization heat exchanger <NUM> functions as a heat radiator (or a condenser) for the second refrigerant R2.

The utilization fan <NUM> generates an air flow to promote heat exchange at the utilization heat exchanger <NUM>.

The utilization unit control unit <NUM> includes a microcomputer and a memory. The utilization unit control unit <NUM> controls the utilization unit expansion valve <NUM>, the utilization fan <NUM>, and the like. The memory stores software for control of these components.

The utilization unit control unit <NUM> transmits and receives data and a command, via a communication line (not depicted), to and from each of the heat source heat exchanger unit control unit <NUM> and the compressor unit control unit <NUM>.

The second connection piping <NUM> connects the compressor unit <NUM> and the utilization units <NUM> and <NUM>. The second connection piping <NUM> includes a second liquid connection pipe <NUM> and a second gas connection pipe <NUM>.

The second liquid connection pipe <NUM> connects the second liquid side shutoff valve 28a and the utilization units <NUM> and <NUM>. The second liquid connection pipe <NUM> guides the second refrigerant R2 principally in a high-pressure liquid state or in a low-pressure gas-liquid two-phase state.

The second gas connection pipe <NUM> connects the second gas side shutoff valve 28b and the utilization units <NUM> and <NUM>. The second gas connection pipe <NUM> guides the second refrigerant R2 principally in the high-pressure gas state or in the low-pressure gas state.

The refrigeration apparatus <NUM> entirely constitutes two refrigerant cycles.

The first refrigerant cycle C1 causes circulation of the first refrigerant R1. The first refrigerant cycle C1 adopts the heat source heat exchanger <NUM> as a heat source. The first refrigerant cycle C1 is constituted by components such as the first compressor <NUM>, the first four-way switching valve <NUM>, the first gas side shutoff valve 23b, the heat source heat exchanger <NUM>, the heat source heat exchanger unit expansion valve <NUM>, the first liquid side shutoff valve 23a, and the cascade heat exchanger <NUM>.

The second refrigerant cycle C2 causes circulation of the second refrigerant R2. The second refrigerant cycle C2 adopts the cascade heat exchanger <NUM> as a heat source. The second refrigerant cycle C2 is constituted by components such as the second compressor <NUM>, the second four-way switching valve <NUM>, the cascade heat exchanger <NUM>, the compressor unit expansion valve <NUM>, the second liquid side shutoff valve 28a, the utilization unit expansion valve <NUM>, the utilization heat exchanger <NUM>, and the second gas side shutoff valve 28b.

The first refrigerant R1 is R32 or carbon dioxide. The first refrigerant R1 can thus be reduced in global warming potential (GWP) valve. This leads to inhibition of global warming due to use of the refrigeration apparatus <NUM>.

The second refrigerant R2 is R32 or R410A. The second refrigerant R2 can thus be reduced in GWP valve. This leads to inhibition of global warming due to use of the refrigeration apparatus <NUM>.

Exemplarily adopting R32 or carbon dioxide as the first refrigerant R1 and R32 as the second refrigerant R2 inhibits global warming caused by the refrigeration apparatus <NUM>.

The first refrigerant R1 and the second refrigerant R2 are preferably natural refrigerants.

When the leakage detection sensor <NUM> detects refrigerant leakage, the compressor unit control unit <NUM> shuts off the first liquid side shutoff valve 23a, the first gas side shutoff valve 23b, the second liquid side shutoff valve 28a, and the second gas side shutoff valve 28b. This inhibits the first refrigerant R1 and the second refrigerant R2 in the compressor unit <NUM> from flowing out of the compressor unit <NUM>.

(<NUM>-<NUM>)
The refrigerant circuit constituted by the compressor unit <NUM> is divided into the first refrigerant cycle C1 and the second refrigerant cycle C2. Both the first refrigerant R1 and the second refrigerant R2 are thus less likely to leak in a case where the refrigerant circuit has damage or the like, achieving reduction in volume of a leaking refrigerant.

The compressor unit <NUM> and the heat source heat exchanger unit <NUM> are constituted as separate units. The refrigeration apparatus <NUM> accordingly includes the first connection piping <NUM> connecting the compressor unit <NUM> and the heat source heat exchanger unit <NUM>. The refrigeration apparatus <NUM> including the first connection piping <NUM> having a large length uses a more refrigerant in comparison to a refrigeration apparatus including a compressor and a heat source heat exchanger belonging to an identical unit. However, the refrigeration apparatus <NUM> thus configured has two refrigerant cycles including the first refrigerant cycle C1 and the second refrigerant cycle C2 to inhibit spread of a leaking refrigerant.

(<NUM>-<NUM>)
The compressor unit <NUM> includes the leakage detection sensor <NUM>. This enables quick detection of refrigerant leakage in an exemplary case where a vibration source such as a compressor damages the refrigerant circuit.

The leakage detection sensor <NUM> is the refrigerant detection sensor 61a. This enables direct detection of refrigerant leakage.

(<NUM>-<NUM>)
The first refrigerant cycle C1 includes the first liquid side shutoff valve 23a and the first gas side shutoff valve 23b. The first liquid side shutoff valve 23a and the first gas side shutoff valve 23b are shut off upon detection of refrigerant leakage to inhibit a leaking refrigerant from reaching outside the compressor unit <NUM>.

The second refrigerant cycle C2 includes the second liquid side shutoff valve 28a and the second gas side shutoff valve 28b. The second liquid side shutoff valve 28a and the second gas side shutoff valve 28b are shut off upon detection of refrigerant leakage to inhibit a leaking refrigerant from reaching outside the compressor unit <NUM>.

(<NUM>-<NUM>)
Upon detection of refrigerant leakage, the compressor unit control unit <NUM> automatically closes the first liquid side shutoff valve 23a and the first gas side shutoff valve 23b. This enables quick shutoff of the refrigerant circuit.

This configuration can also confine the first refrigerant R1 within the first connection piping <NUM> and the heat source heat exchange unit <NUM>.

(<NUM>-<NUM>)
During heating operation, a liquid refrigerant flows in each of the first liquid connection pipe <NUM> in the first refrigerant cycle C1 and the second liquid connection pipe <NUM> in the second refrigerant cycle C2. This reduces pressure loss of a refrigerant flow in each of the first liquid connection pipe <NUM> and the second liquid connection pipe <NUM>.

<FIG> depicts the refrigeration apparatus <NUM> according to the modification example 1A of the first embodiment. Unlike the above embodiment, the refrigeration apparatus <NUM> includes neither the second liquid side shutoff valve 28a nor the second gas side shutoff valve 28b at the second connecting port <NUM>.

Also in this configuration, the first liquid side shutoff valve 23a and the first gas side shutoff valve 23b are shut off upon detection of refrigerant leakage to inhibit refrigerant leakage.

The second refrigerant R2 used in the second refrigerant cycle C2 is preferably an incombustible refrigerant such as R410 in this configuration. Adopting such an incombustible refrigerant in the second refrigerant cycle C2 including the utilization units <NUM> and <NUM> secures safety of the user even in a case where the second refrigerant R2 leaks in the second refrigerant cycle C2.

Furthermore, adopting R32 or carbon dioxide as the first refrigerant R1 used in the first refrigerant cycle C1 inhibits global warming caused by the refrigeration apparatus <NUM>.

<FIG> depicts the refrigeration apparatus <NUM> according to the modification example 1B of the first embodiment. Unlike the above embodiment, the compressor unit <NUM> includes a decompression valve <NUM> and a subcooling heat exchanger <NUM>. The decompression valve <NUM> and the subcooling heat exchanger <NUM> belong to the second refrigerant cycle C2. The subcooling heat exchanger <NUM> includes a first refrigerant flow path 63a and a second refrigerant flow path 63b.

The decompression valve <NUM> decompresses the second refrigerant R2 to obtain the second refrigerant R2 in a low-temperature gas state. The second refrigerant R2 in the low-temperature gas state passes through the second refrigerant flow path 63b. The second refrigerant R2 passing through the first refrigerant flow path 63a is cooled by the second refrigerant R2 passing through the second refrigerant flow path 63b to acquire a degree of subcooling. The second refrigerant R2 flowing out of the second refrigerant flow path 63b is sucked into a suction pipe of the second compressor <NUM>.

The second refrigerant cycle C2 in this configuration includes the subcooling heat exchanger <NUM>. This configuration is thus likely to secure subcooling in the utilization units <NUM> and <NUM>.

Furthermore, the second refrigerant R2 in this configuration partially passes through the second refrigerant flow path 63b serving as a bypass route. Even in a case where the second connection piping <NUM> (the second liquid connection pipe <NUM> and the second gas connection pipe <NUM>) in the second refrigerant cycle C2 has a large length, the second refrigerant R2 flowing in the second connection piping <NUM> is reduced in volume to achieve reduction in pressure loss of the second refrigerant R2 as well as secure subcooling.

The second refrigerant R2 flowing out of the second refrigerant flow path 63b may alternatively be intermediately injected, i.e., be injected directly to a compression chamber of the second compressor <NUM>, instead of being sucked into the suction pipe of the second compressor <NUM>.

<FIG> depicts the refrigeration apparatus <NUM> according to the modification example 1C of the first embodiment. Unlike the above embodiment, the compressor unit <NUM> includes the subcooling heat exchanger <NUM>. The subcooling heat exchanger <NUM> belongs to the second refrigerant cycle C2. The subcooling heat exchanger <NUM> includes a first refrigerant flow path 63a and a second refrigerant flow path 63b.

This secures the degree of subcooling even in a case where the second refrigerant R2 has less circulation volume. In this case, the second refrigerant R2 flowing in the second connection piping <NUM> (the second liquid connection pipe <NUM> and the second gas connection pipe <NUM>) can be reduced in pressure loss while the compressor <NUM> can be reduced in electric power consumption.

<FIG> depicts the refrigeration apparatus <NUM> according to the modification example 1D of the first embodiment. Unlike the above embodiment, the compressor unit <NUM> includes refrigerant jackets <NUM> and <NUM>. The refrigerant jackets <NUM> and <NUM> thermally couple circuit boards constituting compressor unit control units <NUM> and <NUM>, and cooling pipes <NUM> and <NUM>, respectively. The cooling pipes <NUM> and <NUM> each guide a liquid refrigerant. The circuit boards constituting the compressor unit control units <NUM> and <NUM> are thus cooled by the cooling pipes <NUM> and <NUM>, respectively.

In this configuration, the compressor unit control units <NUM> and <NUM> are cooled by the cooling pipes <NUM> and <NUM>, respectively. This achieves effective cooling of the compressor unit control units <NUM> and <NUM> that generate heat.

<FIG> depicts the refrigeration apparatus <NUM> according to the modification example 1E of the first embodiment. In this refrigeration apparatus <NUM>, unlike the above embodiment, the circuit board constituting the compressor unit control unit <NUM> is disposed outside the case 20a. This enables effective release of heat generated by the compressor unit control unit <NUM>.

The heat source heat exchanger unit <NUM> according to the above embodiment is disposed outside the building B. The heat source heat exchanger unit <NUM> may alternatively be disposed inside the building B and be fluid connected to an outside of the building B. As exemplarily depicted in <FIG>, the heat source heat exchanger unit <NUM> may be disposed at a duct provided to the building B and allowing passage of outdoor air.

The heat source heat exchanger unit <NUM> in this configuration is invisible from outside the building B. The refrigeration apparatus <NUM> thus does not affect quality in outer appearance of the building B.

The above embodiment employs two utilization units, namely, the utilization units <NUM> and <NUM>. The number of the utilization units may alternatively be other than two. For example, the number of the utilization units may be one, three, or four.

The heat source heat exchanger <NUM> mounted to the heat source heat exchanger unit <NUM> according to the above embodiment is configured to exchange heat between the first refrigerant R1 and air. The heat source heat exchanger <NUM> may alternatively be configured to exchange heat between the first refrigerant R1 and water. The heat source heat exchanger <NUM> may still alternatively be configured to exchange heat between the first refrigerant R1 and brine. In this case, the heat source heat exchanger <NUM> is connected to the first refrigerant cycle C1 as well as to a cooling tower or the like.

The utilization heat exchanger <NUM> mounted to each of the utilization units <NUM> and <NUM> according to the above embodiment is configured to exchange heat between the second refrigerant R2 and air. The utilization heat exchanger <NUM> may alternatively be configured to exchange heat between the second refrigerant R2 and water. This configuration achieves provision of hot water to the user. The utilization heat exchanger <NUM> may still alternatively be configured to exchange heat between the second refrigerant R2 and brine. In this case, the utilization heat exchanger <NUM> is connected to the second refrigerant cycle C2 as well as to a heat radiator or the like. The heat radiator provides the user with heat energy carried by the brine.

<FIG> is a circuit diagram of a refrigeration apparatus <NUM> according to the second embodiment. In this refrigeration apparatus <NUM>, unlike the first embodiment, the leakage detection sensor 61is a pressure sensor 61b. The pressure sensor 61b detects pressure in the case 20a. The case 20a has airtightness. The case 20a further includes a rupture disk <NUM>. The rupture disk <NUM> is destroyed by pressure exceeding a predetermined value.

(<NUM>-<NUM>)
The case 20a has airtightness. This inhibits a refrigerant leaking in the case 20a from reaching outside the case 20a.

(<NUM>-<NUM>)
The leakage detection sensor <NUM> is the pressure sensor 61b. When a refrigerant leaks in the case 20a having airtightness, refrigerant leakage can be detected in accordance with pressure change.

(<NUM>-<NUM>)
The case 20a includes the rupture disk <NUM>. The rupture disk <NUM> is thus destroyed to release abnormally increased pressure in the case 20a.

(<NUM>-<NUM>)
The case 20a has airtightness. The compressor unit <NUM> thus has higher sound insulation. This is particularly useful when the compressor unit <NUM> is disposed inside the building B.

(<NUM>-<NUM>)
The case 20a has airtightness. The case 20a thus achieves a higher electromagnetic noise cutoff effect when the case 20a is made of a metal.

The above embodiment does not refer to cooling of the circuit board constituting the compressor unit control unit <NUM>. The case 20a of the compressor unit <NUM> has airtightness, so that the case 20a is likely to contain heat generated by the circuit board. As in the modification example 1D, there may be provided the refrigerant jacket thermally connecting the circuit board and the cooling pipe.

The circuit board in this configuration is cooled to inhibit containment of heat in the case 20a.

The circuit board constituting the compressor unit control unit <NUM> according to the above embodiment is disposed inside the case 20a. The case 20a of the compressor unit <NUM> has airtightness, so that the case 20a is likely to contain heat generated by the circuit board. As in the modification example 1E, the circuit board may alternatively be disposed outside the case 20a.

This configuration can inhibit containment of heat in the case 20a.

Claim 1:
A refrigeration apparatus (<NUM>) comprising:
a compressor unit (<NUM>) comprising:
a first case (20a);
a first compressor (<NUM>) accommodated in the first case;
a first connecting port (<NUM>); and
a second connecting port (<NUM>),
a heat source heat exchanger unit (<NUM>) including
a second case (10a) provided separately from the first case and
a heat source heat exchanger (<NUM>),
a utilization unit (<NUM>) including
a third case (50a) provided separately from the first case and
a utilization heat exchanger (<NUM>),
wherein the first connecting port is connected to the heat source heat exchanger via a first connection piping (<NUM>), and the second connecting port is connected to the utilization heat exchanger via a second connection piping (<NUM>),
characterized in that
the compressor unit (<NUM>) further comprises
a cascade heat exchanger (<NUM>) accommodated in the first case; and
a second compressor (<NUM>) accommodated in the first case; and in that
the first compressor, the cascade heat exchanger, and the heat source heat exchanger (<NUM>) constitute a first refrigerant cycle (C1) adopting the heat source heat exchanger as a heat source and configured to cause circulation of a first refrigerant (R1),
the second compressor, the cascade heat exchanger, and the utilization heat exchanger (<NUM>) constitute a second refrigerant cycle (C2) adopting the cascade heat exchanger as a heat source and configured to cause circulation of a second refrigerant (R2), and
the cascade heat exchanger is configured to exchange heat between the first refrigerant and the second refrigerant.