JP6881424B2 - Refrigerator - Google Patents

Description

The present disclosure relates to a refrigeration system.

Patent Document 1 discloses an air conditioner which is a kind of refrigerating apparatus for performing a refrigerating cycle. In Patent Document 1, in order to prevent damage to the compressor due to the liquid back phenomenon, the degree of superheat of the refrigerant sucked into the compressor (hereinafter referred to as "suction superheat degree") is defined as the operating load of the compressor. It is disclosed to adjust according to. The liquid back phenomenon is a phenomenon in which the compressor sucks wet vapor.

Jikkai Sho 59-8345

In order to surely prevent the liquid back phenomenon, it is conceivable to adjust the opening degree of the expansion valve so that the suction superheat degree becomes a relatively large value. However, when the suction superheat degree is increased, the region in which the refrigerant in the gas single-phase state flows in the heat exchanger functioning as the evaporator becomes large, and the cooling capacity of the heat exchanger cannot be fully exerted. Therefore, the conventional refrigerating apparatus has a problem that the operating efficiency is low.

An object of the present disclosure is to improve the operating efficiency of a refrigerating apparatus.

In each of the first and second aspects of the present disclosure, a refrigerant circuit in which a compressor (31), an expansion valve (36,22a, 22b) and a heat exchanger (15,21a, 21b) are provided to perform a refrigeration cycle is performed. (11) and the controller (90) that adjusts the opening degree of the expansion valve (36,22a, 22b) so that the degree of superheat of the refrigerant sucked into the compressor (31) becomes the target degree of superheat. The refrigerating device () equipped with is targeted. Then, the controller (90) adjusts the target superheat degree according to the state of the refrigerating cycle performed by the refrigerant circuit (11), and during the target adjusting operation, the compressor (31) When the first condition indicating that there is a high possibility of the liquid back phenomenon of sucking the wet vapor is satisfied, the first target holding operation for keeping the target superheat degree at the first target value is performed.

In each of the first and second aspects, the controller (90) performs a target adjusting operation. In the target adjusting operation, the controller (90) adjusts the target degree of superheat according to the state of the refrigeration cycle performed by the refrigerant circuit (11). By adjusting the opening degree of the expansion valve (36,22a, 22b) based on the target superheat degree determined by the controller (90) in the target adjustment operation, the superheat degree of the refrigerant sucked into the compressor (31) ( The suction superheat degree) can be set to an appropriate value according to the state of the refrigeration cycle. Therefore, according to this aspect, it is possible to improve the operating efficiency of the refrigerating apparatus (1).

Further, in each of the first and second aspects, when the first condition is satisfied during the target adjustment operation, the controller (90) switches the operation from the target adjustment operation to the first target holding operation. When the possibility of the liquid back phenomenon becomes high, this controller (90) stops the adjustment of the target superheat degree by the target adjustment operation and keeps the target superheat degree at the first target value. If the first target value is set to a sufficiently large value, the refrigerant sucked into the compressor (31) can be kept in a gas single-phase state. Therefore, according to this aspect, it is possible to suppress damage to the compressor (31) due to the liquid back phenomenon and improve the reliability of the refrigerating apparatus (1).

The third aspect of the present disclosure is the first or second aspect, in the target adjusting operation, the controller (90) has the target superheat degree within the range of the minimum target value or more and the maximum target value or less. In the first target holding operation, the controller (90) keeps the target superheat degree at the first target value, which is a value equal to or higher than the maximum target value.

The controller (90) of the third aspect keeps the target superheat degree at the first target value in the first target holding operation. The first target value is a value equal to or higher than the maximum target value. In the first target holding operation of this aspect, the target superheat degree is held at a sufficiently large value. Therefore, according to this aspect, the refrigerant sucked into the compressor (31) can be kept in a gas single-phase state, and damage to the compressor (31) due to the liquid back phenomenon can be suppressed.

Further, in the first aspect , in addition to the above configuration, in the target adjustment operation, the controller (90) satisfies the second condition indicating that the liquid back phenomenon does not occur. In addition, the target superheat degree is lowered, and the target superheat degree is raised when the third condition indicating that the possibility of the liquid back phenomenon is higher than that during the condition of the second condition is satisfied. is there.

In the first aspect , the controller (90) lowers the target degree of superheat when the second condition is met. When the second condition is satisfied, it can be determined that the liquid back phenomenon has not occurred. Therefore, the controller (90) lowers the target degree of superheat and improves the operating efficiency of the refrigerating device (1). The controller (90) raises the target degree of superheat when the third condition is satisfied. When the third condition is satisfied, the possibility of the liquid back phenomenon is higher than when the second condition is satisfied. Therefore, the controller (90) raises the target degree of superheat and reduces the possibility of the liquid back phenomenon.

A second aspect above SL, in addition to the above configuration, the controller (90) is in said first target holding operation, the second condition indicating that the liquid back phenomenon does not occur is established, The target adjustment operation is performed.

In the second aspect , when the second condition is satisfied during the first target holding operation, the controller (90) switches the operation from the first target holding operation to the target adjusting operation. When the second condition is satisfied, it can be determined that the liquid back phenomenon has not occurred. Therefore, when the second condition is satisfied during the first target holding operation, the controller (90) adjusts the target superheat degree according to the state of the refrigeration cycle performed by the refrigerant circuit (11). According to this aspect, when it can be determined that the liquid back phenomenon has not occurred, it is possible to improve the operating efficiency of the refrigerating apparatus (1) by adjusting the target degree of superheat.

In each of the first and second aspects of the present disclosure, in addition to the above configuration, the second condition includes both an appropriate discharge side condition and a stable condition indicating that the fluctuation of the state of the refrigeration cycle is small. The condition is that the condition is satisfied, and the appropriate condition on the discharge side is that the degree of superheat of the refrigerant discharged from the compressor (31) is equal to or higher than the third reference discharge degree of superheat, or the condition is discharged from the compressor (31). It is a condition that the temperature of the refrigerant is equal to or higher than the third reference discharge temperature.

Here, when the degree of superheat or temperature of the refrigerant sucked into the compressor (31) is a value above a certain level and the fluctuation in the state of the refrigerating cycle performed by the refrigerant circuit (11) is small, the liquid back phenomenon does not occur. It can be said that. Therefore, in the controller (90) of each of the first and second aspects, the condition that both the discharge side appropriate condition and the stable condition are satisfied is set as the second condition.

A fourth aspect of the present disclosure further comprises a fan (5) that sends air to the heat exchangers (21a, 21b) in the first or second aspect, while the stability condition is the first compressor. The amount of change in the rotation speed of the compressor (31) during the working time is equal to or less than the reference value for the first compressor, or the amount of change in the rotation speed of the fan (5) during the time for the first fan is for the first fan. The condition is that it is below the standard value.

Here, when the rotation speed of the compressor (31) changes, the flow rate of the refrigerant circulating in the refrigerant circuit (11) changes. Further, when the rotation speed of the fan (5) changes, the amount of heat exchange between the refrigerant and the air in the heat exchangers (21a, 21b) changes. Thus, the rotational speeds of the compressor (31) and fan (5) affect the state of the refrigeration cycle performed by the refrigerant circuit (11). Therefore, the controller (90) of the fourth aspect has a condition indicating that the change in the rotational speed of the compressor (31) or the fan (5) is small, and a stabilizing condition indicating that the change in the state of the refrigeration cycle is small. And.

In the fifth aspect of the present disclosure, in the second aspect, the controller (90) has a second target value which is a value equal to or less than the minimum target value when the fourth condition is satisfied during the target adjustment operation. The second target holding operation for maintaining the target superheat degree is performed, and the fourth condition is the condition that the superheat degree of the refrigerant discharged from the compressor (31) is equal to or higher than the fourth reference discharge superheat degree, or the above. The condition is that the temperature of the refrigerant discharged from the compressor (31) is equal to or higher than the fourth reference discharge temperature.

In the fifth aspect , when the fourth condition is satisfied during the target adjustment operation, the controller (90) switches the operation from the target adjustment operation to the second target holding operation. When the fourth condition is satisfied, it can be determined that the temperature of the refrigerant discharged from the compressor (31) is relatively high. Therefore, when the fourth condition is satisfied during the target adjustment operation, the controller performs the second target holding operation. In the second target holding operation, the controller (90) keeps the target superheat degree at the second target value which is a value equal to or less than the minimum target value. When the degree of superheat of the refrigerant sucked into the compressor becomes low, the temperature of the refrigerant discharged from the compressor (31) becomes low. Therefore, according to this aspect, the reliability of the compressor (31) can be ensured by preventing the refrigerant discharged from the compressor (31) from being overheated.

In the sixth aspect , in the first aspect, the third condition is that the second discharge side low temperature condition is satisfied and the fluctuation condition indicating that the state of the refrigeration cycle fluctuates greatly is not satisfied. The second discharge side low temperature condition is that the degree of superheat of the refrigerant discharged from the compressor (31) is equal to or less than the second reference discharge superheat degree, or the condition is that the refrigerant is discharged from the compressor (31). The condition is that the temperature of the refrigerant is equal to or lower than the second reference discharge temperature.

Here, when the degree of superheat or temperature of the refrigerant sucked into the compressor (31) is a value below a certain level, but the fluctuation of the state of the refrigeration cycle performed by the refrigerant circuit (11) is not large, the liquid back phenomenon is possible. It can be said that the sex is not so high. Therefore, in the controller (90) of the sixth aspect , the condition that the second discharge side low temperature condition is satisfied and the fluctuation condition is not satisfied is set as the third condition.

A seventh aspect of the present disclosure further comprises a fan (5) that sends air to the heat exchangers (21a, 21b) in the sixth aspect, while the variation conditions are in the time for the second compressor. The amount of change in the rotation speed of the compressor (31) is equal to or greater than the reference value for the second compressor, or the amount of change in the rotation speed of the fan (5) during the time for the second fan is greater than or equal to the reference value for the second fan. It is a condition that it is.

Here, when the rotation speed of the compressor (31) changes, the flow rate of the refrigerant circulating in the refrigerant circuit (11) changes. Further, when the rotation speed of the fan (5) changes, the amount of heat exchange between the refrigerant and the air in the heat exchangers (21a, 21b) changes. Thus, the rotational speeds of the compressor (31) and fan (5) affect the state of the refrigeration cycle performed by the refrigerant circuit (11). Therefore, in the controller (90) of the seventh aspect, the condition indicating that the change in the rotation speed of the compressor (31) or the fan (5) is large is set as the fluctuation condition indicating that the state of the refrigeration cycle has a large change. To do.

In the eighth aspect of the present disclosure, in the fifth aspect, the controller (90) performs the second target holding operation when the fourth condition is satisfied during the first target holding operation. is there.

When the fourth condition is satisfied during the first target holding operation, the controller (90) of the eighth aspect switches the operation from the first target holding operation to the second target holding operation. In the second target holding operation, the controller (90) keeps the target superheat degree at the second target value which is a value equal to or less than the minimum target value. When the degree of superheat of the refrigerant sucked into the compressor (31) becomes low, the temperature of the refrigerant discharged from the compressor (31) becomes low. Therefore, according to this aspect, the reliability of the compressor (31) can be ensured by preventing the refrigerant discharged from the compressor (31) from being overheated.

In the ninth aspect of the present disclosure, in the fifth aspect, the controller (90) performs the first target holding operation when the first condition is satisfied during the second target holding operation. is there.

When the first condition is satisfied during the second target holding operation, the controller (90) of the ninth aspect switches the operation from the second target holding operation to the first target holding operation. In the first target holding operation, the controller (90) keeps the target superheat degree at the first target value which is a value equal to or higher than the maximum target value. In the first target holding operation of this aspect, the target superheat degree is held at a sufficiently large value. Therefore, according to this aspect, the refrigerant sucked into the compressor (31) can be kept in a gas single-phase state, and damage to the compressor (31) due to the liquid back phenomenon can be suppressed.

FIG. 1 is a refrigerant circuit diagram showing the configuration of the chiller device of the embodiment. FIG. 2 is a refrigerant circuit diagram of the chiller device showing the flow of the refrigerant during the cooling operation. FIG. 3 is a refrigerant circuit diagram of the chiller device showing the flow of the refrigerant during the heating operation. FIG. 4 is a block diagram showing a configuration of a controller of the chiller device of the embodiment. FIG. 5 is a state transition diagram showing an operation performed by the target superheat degree setting unit of the controller of the embodiment.

The chiller device (1) of the present embodiment is a refrigerating device that performs a refrigerating cycle. This chiller device (1) includes a refrigerant circuit that circulates a refrigerant to perform a refrigeration cycle, and cools or heats the heat medium with the refrigerant. The heat medium cooled or heated in the chiller device (1) is supplied to a fan coil unit (not shown) and used for cooling or heating the indoor space.

As shown in FIG. 1, the chiller device (1) includes a first refrigerant circuit (11) and a second refrigerant circuit (12). The first refrigerant circuit (11) and the second refrigerant circuit (12) share one water heat exchanger (15). Further, the chiller device (1) is provided with one outdoor fan (5) for each refrigerant circuit (11, 12). Each outdoor fan (5) sends outdoor air to the outdoor heat exchangers (21a, 21b) of the corresponding refrigerant circuits (11,12). Further, the chiller device (1) includes a controller (90).

-Refrigerant circuit-
The first refrigerant circuit (11) and the second refrigerant circuit (12) have the same configuration. FIG. 1 illustrates the specific configuration of the first refrigerant circuit (11), and the illustration of the specific configuration of the second refrigerant circuit (12) is omitted. Here, the first refrigerant circuit (11) will be described.

The first refrigerant circuit (11) includes a compressor (31), a four-way switching valve (32), a bridge circuit (40), a liquid receiver (33), a heat exchanger for supercooling (35), and the like. A user-side expansion valve (36) is provided one by one. A water heat exchanger (15) is connected to the first refrigerant circuit (11). The first refrigerant circuit (11) includes a one-way pipeline (53), a supercooling pipeline (54), an equipment cooling pipeline (55), a suction connection pipeline (60), and a degassing pipeline (60). 61) and one by one. Further, the first refrigerant circuit (11) includes two branch pipelines (20a, 20b). Each branch line (20a, 20b) is provided with one outdoor heat exchanger (21a, 21b) and one heat source side expansion valve (22a, 22b).

<Compressor>
The compressor (31) is a fully enclosed scroll compressor. Further, the operating capacity of the compressor (31) is variable. Specifically, alternating current is supplied to the motor of the compressor (31) from an inverter (not shown). When the output frequency of the inverter is changed, the rotation speed of the motor provided in the compressor (31) changes, and the operating capacity of the compressor (31) changes.

The suction pipe of the compressor (31) is connected to the suction pipe (51). The discharge pipe of the compressor (31) is connected to the discharge pipe (52). The intermediate injection tube of the compressor (31) connects to the supercooled pipeline (54). A check valve (CV13) is provided in the discharge pipe (52). This check valve (CV13) allows the flow of the refrigerant flowing out of the compressor (31) and blocks the flow of the refrigerant in the opposite direction.

<Four-way switching valve>
The four-way switching valve (32) is a switching valve having four ports. The first port of the four-way switching valve (32) is connected to the compressor (31) via the discharge pipe (52). The second port of the four-way switching valve (32) is connected to the compressor (31) via the suction pipe (51). The third port of the four-way switching valve is connected to one end of each branch line (20a, 20b). The fourth port of the four-way switching valve (32) connects to the water heat exchanger (15).

The four-way switching valve (32) switches between the first state shown by the solid line in FIG. 1 and the second state shown by the broken line in FIG. In the four-way switching valve (32) in the first state, the first port communicates with the third port, and the second port communicates with the fourth port. In the four-way switching valve (32) in the second state, the first port communicates with the fourth port, and the second port communicates with the third port.

<Branch pipeline>
The two branch pipelines (20a, 20b) are connected in parallel with each other. The gas side end of each branch line (20a, 20b) is connected to the third port of the four-way switching valve (32). The liquid side end of each branch line (20a, 20b) is connected to the bridge circuit (40).

In the first branch pipeline (20a), the first outdoor heat exchanger (21a) and the first heat source side expansion valve (22a) are arranged in series. In the second branch pipeline (20b), the second outdoor heat exchanger (21b) and the second heat source side expansion valve (22b) are arranged in series. In each branch line (20a, 20b), an outdoor heat exchanger (21a, 21b) is arranged near the gas side end of the branch line (20a, 20b), and the liquid side end of the branch line (20a, 20b). Heat source side expansion valves (22a, 22b) are arranged closer to each other.

Each outdoor heat exchanger (21a, 21b) is a heat source side heat exchanger that exchanges heat with the outdoor air for the refrigerant. The heat exchange capacity of the first outdoor heat exchanger (21a) is larger than the heat exchange capacity of the second outdoor heat exchanger (21b). Each heat source side expansion valve (22a, 22b) is an electronic expansion valve with a variable opening.

The outdoor fan (5) corresponding to the first refrigerant circuit (11) sends outdoor air to both the first outdoor heat exchanger (21a) and the second outdoor heat exchanger (21b) of the first refrigerant circuit (11). send.

<Bridge circuit>
The bridge circuit (40) comprises four pipes (41-44). The first check valve (CV1) is attached to the first pipe (41), the second check valve (CV2) is used for the second pipe (42), and the third check valve (CV2) is used for the third pipe (43). A CV3) is provided, and a fourth check valve (CV4) is provided in the fourth pipe (44). Each check valve (CV1 to CV4) allows the flow of refrigerant in the direction from the inflow end to the outflow end of the corresponding pipe (41 to 44) and blocks the flow of the refrigerant in the opposite direction.

The outflow end of the first pipe (41) and the inflow end of the second pipe (42) are connected to the liquid side ends of the branch pipes (20a, 20b). The outflow end of the second pipe (42) and the outflow end of the third pipe (43) are connected to one end of the one-way pipe (53). The inflow end of the third pipe (43) and the outflow end of the fourth pipe (44) are connected to one end of the expansion valve (36) on the utilization side. The inflow end of the fourth pipe (44) and the inflow end of the first pipe (41) are connected to the other end of the one-way pipe (53).

<Usage side expansion valve>
The user-side expansion valve (36) is an electronic expansion valve with a variable opening. The other end of the user-side expansion valve (36) is connected to the water heat exchanger (15).

<Water heat exchanger>
The water heat exchanger (15) is a user-side heat exchanger. The water heat exchanger (15) exchanges heat between the refrigerants of the first refrigerant circuit (11) and the second refrigerant circuit (12) with the heat medium.

The water heat exchanger (15) is formed with a water flow path (16), a first refrigerant flow path (17), and a second refrigerant flow path (18). A heat medium water circulation circuit is connected to the water flow path (16). The first refrigerant circuit (11) is connected to the first refrigerant flow path (17). A second refrigerant circuit (12) is connected to the second refrigerant flow path (18). One end of each refrigerant flow path (17,18) is connected to the fourth port of the four-way switching valve (32) of the corresponding refrigerant circuit (11,12). The other end of each refrigerant flow path (17,18) is connected to the other end of the utilization side expansion valve (36) of the corresponding refrigerant circuit (11,12).

<One-way pipeline, supercooled pipeline, supercooled heat exchanger>
In the one-way pipeline (53), a liquid receiver (33) and a supercooling heat exchanger (35) are arranged in order from one end to the other end.

One end of the supercooling line (54) is connected between the receiver (33) and the supercooling heat exchanger (35) in the one-way line (53). The other end of the supercooled conduit (54) is connected to the intermediate injection tube of the compressor (31). In the supercooling pipeline (54), a supercooling expansion valve (34) and a supercooling heat exchanger (35) are arranged in order from one end to the other end.

The supercooling heat exchanger (35) is formed with a primary side flow path (35a) and a secondary side flow path (35b). The primary side flow path (35a) connects to the unidirectional pipeline. The secondary side flow path (35b) connects to the supercooled pipeline. The supercooling heat exchanger (35) cools by exchanging heat with the refrigerant in the primary side flow path (35a) with the refrigerant in the secondary side flow path (35b).

<Equipment cooling pipeline, equipment cooler>
One end of the equipment cooling pipeline (55) is connected between the first outdoor heat exchanger (21a) and the first heat source side expansion valve (22a) in the first branch pipeline (20a). The other end of the equipment cooling line (55) is connected to the pipe connecting the liquid side ends of the two branch lines (20a, 20b) and the bridge circuit (40).

A flow rate control valve (57) and an equipment cooler (56) are arranged in this order from one end to the other end in the equipment cooling pipeline (55). The flow rate control valve (57) is an electronic expansion valve having a variable opening degree. The equipment cooler (56) is a member for cooling the components of the chiller device (1). An example of a component cooled by the equipment cooler (56) is an electric component that generates heat, such as a power element of an inverter. The equipment cooler (56) is thermally connected to the component to be cooled, and the heat generated in the component is absorbed by the refrigerant.

<Suction connection pipeline>
One end of the suction connection line (60) is connected to the downstream side of the supercooling heat exchanger (35) in the supercooling line (54). The other end of the suction connection line (60) is connected to the suction pipe (51).

A solenoid valve (SV1) and a check valve (CV11) are arranged in this order from one end to the other end in the suction connection line (60). The check valve (CV11) allows the flow of refrigerant from one end to the other end of the suction connection line (60) and blocks the flow of refrigerant in the opposite direction.

<Gas vent pipeline>
One end of the degassing line (61) connects to the top of the receiver (33). The other end of the degassing line (61) is connected to the downstream side of the check valve (CV11) in the suction connection line (60).

In the degassing pipeline (61), a solenoid valve (SV2), a capillary tube (62), and a check valve (CV12) are arranged in order from one end to the other end. The check valve (CV12) allows the flow of refrigerant from one end to the other end of the degassing pipeline (61) and blocks the flow of refrigerant in the opposite direction.

<Pressure sensor, temperature sensor>
The first refrigerant circuit (11) is provided with a suction pressure sensor (81) and a discharge pressure sensor (82). The suction pressure sensor (81) is connected to the suction pipe (51) and measures the pressure of the refrigerant sucked into the compressor (31) through the suction pipe (51). The discharge pressure sensor (82) is connected to the discharge pipe (52) and measures the pressure of the refrigerant discharged from the compressor (31) and flowing through the discharge pipe (52).

The first refrigerant circuit (11) is provided with a suction temperature sensor (83) and a discharge temperature sensor (84). The suction temperature sensor (83) is attached to the suction pipe (51) and measures the temperature of the suction pipe (51). The measured value of the suction temperature sensor (83) is substantially the temperature of the refrigerant sucked into the compressor (31) through the suction pipe (51). The discharge temperature sensor (84) is attached to the discharge pipe (52) and measures the temperature of the discharge pipe (52). The measured value of the discharge temperature sensor (84) is substantially the temperature of the refrigerant discharged from the compressor (31) and flowing through the discharge pipe (52).

Further, the first refrigerant circuit (11) is provided with a first gas side temperature sensor (85a) and a second gas side temperature sensor (85b). The first gas-side temperature sensor (85a) is mounted between the gas-side end of the first branch line (20a) and the first outdoor heat exchanger (21a). The second gas-side temperature sensor (85b) is mounted between the gas-side end of the second branch line (20b) and the second outdoor heat exchanger (21b). Each gas side temperature sensor (85a, 85b) measures the temperature of the corresponding branch line (20a, 20b). The measured value of each gas side temperature sensor (85a, 85b) is substantially the temperature of the refrigerant flowing through the corresponding branch line (20a, 20b) where the gas side temperature sensor (85a, 85b) is attached. Is. Although not shown in FIG. 1, the first refrigerant circuit (11) includes a large number of sensors other than the suction temperature sensor (83), the discharge temperature sensor (84), and the gas side temperature sensor (85a, 85b). A temperature sensor is provided.

-Control-
As shown in FIG. 4, the controller (90) includes an arithmetic processing unit (91) and a memory unit (92). The arithmetic processing unit (91) is, for example, a microprocessor including an integrated circuit. The arithmetic processing unit of the controller (90) functions as a compressor control unit (95), a fan control unit (96), an expansion valve control unit (97), and a target superheat degree setting unit (98).

The memory unit (92) is, for example, a semiconductor memory composed of an integrated circuit. The memory unit (92) stores a program for causing the control (90) to execute a predetermined operation and data necessary for the operation of the control (90).

The compressor control unit (95) adjusts the rotation speed of the compressor (31) in each of the cooling operation and the heating operation described later. The fan control unit (96) adjusts the rotation speed of the outdoor fan (5) in each of the cooling operation and the heating operation described later.

The expansion valve control unit (97) adjusts the opening degree of the utilization side expansion valve (36) during the cooling operation described later, and expands the first heat source side expansion valve (22a) and the second heat source side expansion during the heating operation described later. Adjust the opening of the valve (22b). The expansion valve control unit (97) adjusts the opening degree of the expansion valve (36,22a, 22b) by using the target superheat degree set by the target superheat degree setting unit (98).

The target superheat degree setting unit (98) sets the target superheat degree used in the operation of the expansion valve control unit (97). The target superheat degree setting unit (98) records the set target superheat degree in the memory unit (92). This target superheat degree is a target value for the superheat degree (suction superheat degree) of the refrigerant sucked into the compressor (31).

-Operating operation of the chiller device-
The chiller device (1) performs a cooling operation and a heating operation. The cooling operation is an operation of cooling the heat medium in the water heat exchanger (15). The heating operation is an operation of heating the heat medium in the water heat exchanger (15).

<Cooling operation>
In the cooling operation, the controller (90) sets the four-way switching valve (32) to the first state, and sets the first heat source side expansion valve (22a), the second heat source side expansion valve (22b), and the utilization side expansion valve. The opening degree between (36), the supercooling expansion valve (34), and the flow rate control valve (57) is adjusted.

As shown in FIG. 2, in the cooling operation, a part of the refrigerant discharged from the compressor (31) flows into the first branch line (20a), and the rest flows into the second branch line (20b). To do. The refrigerant flowing into each branch line (20a, 20b) dissipates heat to the outdoor air in the outdoor heat exchanger (21a, 21b), condenses, and then passes through the heat source side expansion valve (22a, 22b). Join. Further, a part of the refrigerant flowing out from the first outdoor heat exchanger (21a) in the first branch pipeline (20a) flows into the equipment cooler (56) after passing through the flow rate control valve (57) to cool the equipment. Heat is absorbed from the constituent equipment in the vessel (56) and merges with the refrigerant flowing out from the liquid side end of each branch pipeline (20a, 20b) on the upstream side of the bridge circuit (40).

Subsequently, the refrigerant flows into the one-way pipeline (53) through the second pipe (42) of the bridge circuit (40), and then flows into the receiver (33). A part of the refrigerant flowing out of the liquid receiver (33) flows into the supercooling pipeline (54), and the rest flows into the primary side flow path (35a) of the supercooling heat exchanger (35). The refrigerant flowing into the supercooling pipeline (54) expands to an intermediate pressure when passing through the supercooling expansion valve (34), and then the secondary side flow path of the supercooling heat exchanger (35). It flows into (35b), absorbs heat from the refrigerant in the primary side flow path (35a), and then flows into the compressor (31).

The refrigerant cooled in the primary side flow path (35a) of the supercooling heat exchanger (35) passes through the fourth pipe (44) of the bridge circuit (40) and the utilization side expansion valve (36) in order. The refrigerant expanded to a low pressure when passing through the user-side expansion valve (36) flows into the first refrigerant flow path (17) of the water heat exchanger (15) and from the heat medium of the water flow path (16). It absorbs heat and evaporates. In the water heat exchanger (15), the heat medium flowing through the water flow path (16) is cooled by the refrigerant. The refrigerant flowing out of the water heat exchanger (15) is sucked into the compressor (31). The compressor (31) compresses and discharges the sucked refrigerant.

<Heating operation>
In the heating operation, the controller (90) sets the four-way switching valve (32) to the second state, and expands for supercooling with the first heat source side expansion valve (22a) and the second heat source side expansion valve (22b). The opening degree of the valve (34) and the flow rate adjusting valve (57) is adjusted to keep the opening degree of the utilization side expansion valve (36) substantially fully open.

As shown in FIG. 3, in the heating operation, the refrigerant discharged from the compressor (31) flows into the first refrigerant flow path (17) of the water heat exchanger (15) and heats the water flow path (16). It dissipates heat to the refrigerant and condenses. In the water heat exchanger (15), the heat medium flowing through the water flow path (16) is heated by the refrigerant.

The refrigerant flowing out of the water heat exchanger (15) passes through the utilization side expansion valve (36) and the third pipe (43) of the bridge circuit (40) in order, and then flows into the liquid receiver (33). A part of the refrigerant flowing out of the liquid receiver (33) flows into the supercooling pipeline (54), and the rest flows into the primary side flow path (35a) of the supercooling heat exchanger (35). The refrigerant flowing into the supercooling pipeline (54) expands to an intermediate pressure when passing through the supercooling expansion valve (34), and then the secondary side flow path of the supercooling heat exchanger (35). It flows into (35b), absorbs heat from the refrigerant in the primary side flow path (35a), and then flows into the compressor (31).

The refrigerant cooled in the primary side flow path (35a) of the supercooling heat exchanger (35) passes through the first pipe (41) of the bridge circuit (40). After that, a part of the refrigerant flows into the equipment cooling line (55), and the rest flows toward the liquid side end of the branch line (20a, 20b). The refrigerant flowing into the equipment cooling pipeline (55) absorbs heat from the constituent equipment in the equipment cooler (56), expands to a low pressure when passing through the flow rate control valve (57), and then the first branch pipeline. It flows into (20a).

A part of the refrigerant flowing toward the liquid side end of the branch line (20a, 20b) flows into the first branch line (20a), and the rest flows into the second branch line (20b). The refrigerant flowing into each branch line (20a, 20b) expands to a low pressure when passing through the heat source side expansion valve (22a, 22b), and then flows into the outdoor heat exchanger (21a, 21b). At that time, in the first branch pipeline (20a), the refrigerant that has passed through the first heat source side expansion valve (22a) merges with the refrigerant that has passed through the equipment cooling pipeline (55), and then the first outdoor heat exchanger (21a). ). The refrigerant flowing into the outdoor heat exchangers (21a, 21b) absorbs heat from the outdoor air, evaporates, and is then sucked into the compressor (31). The compressor (31) compresses and discharges the sucked refrigerant.

-Control operation-
The controller (90) controls the constituent devices of the chiller device (1).

<Compressor control unit>
The compressor control unit (95) adjusts the rotation speed of the compressor (31). Specifically, the compressor control unit (95) adjusts the rotation speed of the compressor (31) by changing the output frequency of the inverter that supplies electric power to the motor of the compressor (31).

In the cooling operation of the chiller device (1), the compressor control unit (95) reads the measured value of the suction pressure sensor (81). The compressor control unit (95) adjusts the rotation speed of the compressor (31) so that the measured value of the suction pressure sensor (81) is within the target suction pressure range. When the measured value of the suction pressure sensor (81) falls below the lower limit of the target suction pressure range, the compressor control unit (95) reduces the rotation speed of the compressor (31). On the other hand, when the measured value of the suction pressure sensor (81) exceeds the upper limit of the target suction pressure range, the compressor control unit (95) increases the rotation speed of the compressor (31).

In the heating operation of the chiller device (1), the compressor control unit (95) reads the measured value of the discharge pressure sensor (82). The compressor control unit (95) adjusts the rotation speed of the compressor (31) so that the measured value of the discharge pressure sensor (82) is within the target discharge pressure range. When the measured value of the discharge pressure sensor (82) falls below the lower limit of the target discharge pressure range, the compressor control unit (95) increases the rotation speed of the compressor (31). On the other hand, when the measured value of the discharge pressure sensor (82) exceeds the upper limit of the target discharge pressure range, the compressor control unit (95) reduces the rotation speed of the compressor (31).

<Fan control unit>
The fan control unit (96) adjusts the rotation speed of the outdoor fan (5). Specifically, the fan control unit (96) adjusts the rotation speed of the outdoor fan (5) by changing the output frequency of the inverter that supplies electric power to the motor of the outdoor fan (5).

In the cooling operation of the chiller device (1), the fan control unit (96) reads the measured value of the discharge pressure sensor (82). The fan control unit (96) adjusts the rotation speed of the outdoor fan (5) so that the measured value of the discharge pressure sensor (82) is within the target discharge pressure range. When the measured value of the discharge pressure sensor (82) falls below the lower limit of the target discharge pressure range, the fan control unit (96) reduces the rotation speed of the outdoor fan (5). On the other hand, when the measured value of the discharge pressure sensor (82) exceeds the upper limit of the target discharge pressure range, the fan control unit (96) increases the rotation speed of the outdoor fan (5).

In the heating operation of the chiller device (1), the fan control unit (96) reads the measured value of the suction pressure sensor (81). The fan control unit (96) adjusts the rotation speed of the outdoor fan (5) so that the measured value of the suction pressure sensor (81) is within the target suction pressure range. When the measured value of the suction pressure sensor (81) falls below the lower limit of the target suction pressure range, the fan control unit (96) increases the rotation speed of the outdoor fan (5). On the other hand, when the measured value of the suction pressure sensor (81) exceeds the upper limit of the target suction pressure range, the fan control unit (96) reduces the rotation speed of the outdoor fan (5).

<Expansion valve control unit>
The expansion valve control unit (97) adjusts the opening degree of the expansion valve (36,22a, 22b) so that the degree of superheat of the refrigerant sucked into the compressor (31) becomes the target degree of superheat.

In the cooling operation of the chiller device (1), the expansion valve control unit (97) reads the measured value of the suction pressure sensor (81) and the measured value of the suction temperature sensor (83). The expansion valve control unit (97) calculates the degree of superheat SHs of the refrigerant flowing through the suction pipe (51) using the measured values of the suction pressure sensor (81) and the suction temperature sensor (83). Further, the expansion valve control unit (97) reads out the target superheat degree SHs_tgt recorded in the memory unit (92). The expansion valve control unit (97) compares the calculated superheat degree SHs with the target superheat degree SHs_tgt.

The expansion valve control unit (97) adjusts the opening degree of the expansion valve (36) on the utilization side so that the calculated superheat degree SHs falls within the target superheat degree range. This target superheat degree range is a numerical range including the target superheat degree SHs_tgt (for example, a range of SHs_tgt ± 0.5 ° C.). When the calculated superheat degree SHs falls below the lower limit value of the target superheat degree range (SHs_tgt-0.5 ° C. in the above example), the expansion valve control unit (97) adjusts the opening degree of the utilization side expansion valve (36). to shrink. On the other hand, when the calculated superheat degree SHs exceeds the upper limit value of the target superheat degree range (SHs_tgt + 0.5 ° C. in the above example), the expansion valve control unit (97) increases the opening degree of the utilization side expansion valve (36). Expanding.

In the heating operation of the chiller device (1), the expansion valve control unit (97) uses the measurement value of the suction pressure sensor (81), the measurement value of the first gas side temperature sensor (85a), and the second gas side temperature sensor. Read the measured value of (85b). The expansion valve control unit (97) uses the measured values of the suction pressure sensor (81) and the first gas side temperature sensor (85a) to make the first outdoor heat exchanger (21a) in the first branch pipeline (20a). The superheat degree SHs1 of the refrigerant flowing out from is calculated. Further, the expansion valve control unit (97) uses the measured values of the suction pressure sensor (81) and the second gas side temperature sensor (85b) to perform the second outdoor heat exchanger (20b) in the second branch pipeline (20b). Calculate the superheat degree SHs2 of the refrigerant flowing out from 21b). Further, the expansion valve control unit (97) reads out the target superheat degree SHs_tgt recorded in the memory unit (92). The expansion valve control unit (97) compares each of the calculated superheat degree SHs1 and superheat degree SHs2 with the target superheat degree SHs_tgt.

The expansion valve control unit (97) adjusts the opening degree of the heat source side expansion valve (22a, 22b) so that each of the calculated superheat degree SHs1 and superheat degree SHs2 falls within the target superheat degree range.

When the calculated superheat degree SHs1 falls below the lower limit value of the target superheat degree range (SHs_tgt-0.5 ° C. in the above example), the expansion valve control unit (97) opens the first heat source side expansion valve (22a). Reduce the degree. On the other hand, when the calculated superheat degree SHs1 exceeds the upper limit value of the target superheat degree range (SHs_tgt + 0.5 ° C. in the above example), the expansion valve control unit (97) opens the first heat source side expansion valve (22a). Increase the degree.

When the calculated superheat degree SHs2 falls below the lower limit value of the target superheat degree range (SHs_tgt-0.5 ° C. in the above example), the expansion valve control unit (97) opens the second heat source side expansion valve (22b). Reduce the degree. On the other hand, when the calculated superheat degree SHs2 exceeds the upper limit value of the target superheat degree range (SHs_tgt + 0.5 ° C. in the above example), the expansion valve control unit (97) opens the second heat source side expansion valve (22b). Increase the degree.

-Operation of target superheat setting unit-
As shown in FIG. 5, the target superheat degree setting unit (98) performs a target adjusting operation, a first target holding operation, and a second target holding operation. In addition, the target superheat degree setting unit (98) performs a target lowering operation and a target raising operation in the target adjusting operation. The target superheat degree setting unit (98) sets the target superheat degree by selectively performing these operations. As described above, the target superheat degree is a target value for the superheat degree of the refrigerant sucked into the compressor (31).

The target superheat degree setting unit (98) determines the success or failure of the first to fourth conditions described later every time a predetermined time elapses. The target superheat degree setting unit (98) has one of the target lowering operation, the target raising operation, the first target holding operation, and the second target holding operation according to the judgment result of the success or failure of the first to fourth conditions. Do one.

<Target adjustment operation>
In the target adjusting operation, the target superheat setting unit (98) adjusts the target superheat according to the state of the refrigeration cycle performed by the first refrigerant circuit (11). The target superheat degree setting unit (98) adjusts the target superheat degree by performing the target lowering operation and the target raising operation.

Further, the target superheat degree setting unit (98) adjusts the target superheat degree within a range of the minimum target value C or more and the maximum target value A or less. In the present embodiment, the maximum target value A is, for example, 5 ° C., and the minimum target value C is, for example, 2 ° C.

In the target lowering operation, the target superheat degree setting unit (98) lowers the target superheat degree by a predetermined value B. In the present embodiment, the predetermined value B is, for example, 0.5 ° C. Further, in FIG. 5, SHs_tgt is the target superheat degree after the update, and SHs_tgt'is the target superheat degree immediately before the update.

When the second condition is satisfied, the target superheat degree setting unit (98) performs a target lowering operation. The second condition is a condition indicating that the liquid back phenomenon in which the compressor (31) sucks wet vapor does not occur. The target superheat degree setting unit (98) executes a target lowering operation every time it determines that the second condition is satisfied, and lowers the target superheat degree by a predetermined value B. However, when the target superheat degree reaches the minimum target value C, the target superheat degree setting unit (98) does not further reduce the target superheat degree.

When the third condition is satisfied, the target superheat degree setting unit (98) performs a target raising operation. The third condition is a condition indicating that the possibility of the liquid back phenomenon is higher than that during the establishment of the second condition. The target superheat degree setting unit (98) executes a target raising operation every time it determines that the third condition is satisfied, and raises the target superheat degree by a predetermined value B. However, when the target superheat degree reaches the maximum target value A, the target superheat degree setting unit (98) does not raise the target superheat degree any further.

<First target holding operation>
In the first target holding operation, the target superheat degree setting unit (98) holds the target superheat degree at the first target value. In the present embodiment, the first target value is the maximum target value A. The first target value may be a value larger than the maximum target value A.

When the first condition is satisfied, the target superheat degree setting unit (98) performs the first target holding operation. When the first condition is satisfied, the target superheat degree setting unit (98) switches the operation to the first target holding operation during both the target adjusting operation and the second target holding operation.

The first condition is a condition indicating that the possibility of the liquid back phenomenon is high. Therefore, when the first condition is satisfied, the target superheat degree setting unit (98) sets the target superheat degree to the maximum target value A. In this state, the expansion valve control unit (97) adjusts the opening degree of the expansion valve (36,22a, 22b) so that the degree of superheat of the refrigerant sucked into the compressor (31) becomes the maximum target value A. To do. As a result, the degree of superheat of the refrigerant sucked into the compressor (31) becomes relatively large, and the possibility of the liquid back phenomenon is reduced.

When the second condition is satisfied during the first target holding operation, the target superheat degree setting unit (98) ends the first target holding operation and executes the target lowering operation. As described above, the second condition is a condition indicating that the liquid back phenomenon has not occurred. Therefore, when the second condition is satisfied during the first target holding operation, the target superheat degree setting unit (98) performs the target lowering operation to lower the target superheat degree.

<Second target holding operation>
In the second target holding operation, the target superheat degree setting unit (98) holds the target superheat degree at the second target value. The second target value is the minimum target value C. In the present embodiment, the second target value may be smaller than the minimum target value C.

When the fourth condition is satisfied, the target superheat degree setting unit (98) performs the second target holding operation. The target superheat degree setting unit (98) switches the operation to the second target holding operation when the fourth condition is satisfied during both the target adjusting operation and the first target holding operation.

The fourth condition is a condition indicating that the temperature of the refrigerant discharged from the compressor (31) is too high. Therefore, the target superheat degree setting unit (98) sets the target superheat degree to the minimum target value C when the fourth condition is satisfied. In this state, the expansion valve control unit (97) adjusts the opening degree of the expansion valve (36,22a, 22b) so that the degree of superheat of the refrigerant sucked into the compressor (31) becomes the minimum target value C. To do. As a result, the degree of superheat of the refrigerant sucked into the compressor (31) becomes relatively small, and the temperature of the refrigerant discharged from the compressor (31) becomes low.

When the third condition is satisfied during the second target holding operation, the target superheat degree setting unit (98) ends the second target holding operation and executes the target raising operation. The third condition is a condition indicating that the possibility of the liquid back phenomenon is higher than that during the establishment of the second condition. Therefore, when the third condition is satisfied during the second target holding operation, the target superheat degree setting unit (98) performs the target raising operation to raise the target superheat degree.

<First condition>
The first condition is a condition that the first discharge side low temperature condition or the fluctuation condition is satisfied. When this first condition is satisfied, it can be determined that the possibility of the liquid back phenomenon is high.

[First discharge side low temperature condition]
The first discharge side low temperature condition is a condition that the superheat degree SHd of the refrigerant discharged from the compressor (31) is equal to or less than the first reference discharge superheat degree SHd_r1 (SHd ≦ SHd_r1). In the present embodiment, the first reference discharge superheat degree SHd_r1 is, for example, 15 ° C. Further, the degree of superheat SHd is calculated using the measured value of the discharge temperature sensor (84) and the measured value of the discharge pressure sensor (82). When the first discharge side low temperature condition is satisfied, it can be determined that there is a high possibility that the liquid back phenomenon has occurred.

The first discharge side low temperature condition may be a condition that the temperature Td of the refrigerant discharged from the compressor (31) is equal to or less than the first reference discharge temperature Td_r1 (Td ≦ Td_r1). In this case as well, if the first discharge side low temperature condition is satisfied, it can be determined that there is a high possibility that the liquid back phenomenon has occurred.

[Variation conditions]
The fluctuation condition is a condition that the compressor fluctuation condition or the fan fluctuation condition is satisfied. This fluctuation condition is a condition indicating that the fluctuation of the state of the refrigeration cycle is large. If the state of the refrigeration cycle fluctuates greatly, it can be determined that the behavior of the refrigerant in the refrigerant circuit (11) becomes unstable and the liquid back phenomenon is likely to occur.

The compressor fluctuation condition is a condition that the amount of change in the rotation speed of the compressor (31) in the reference time for the second compressor (for example, 15 seconds) is equal to or greater than the reference value for the second compressor. Under this compressor fluctuation condition, the amount of change in the rotation speed of the compressor (31) is the absolute value of the amount of increase or decrease in the rotation speed of the compressor (31). The target overheating degree setting unit (98) changes from "rotation speed RC of the compressor (31) at the time of determining the compressor fluctuation condition" to "before the reference time for the second compressor at that time" (in the above example, The absolute value of the value (RC-RC') obtained by subtracting the rotation speed RC'" of the compressor (31) 15 seconds ago is defined as the" change amount of the rotation speed of the compressor (31) ". In the present embodiment, the reference value for the second compressor is 8% of the rotation speed of the compressor (31) at the time when the compressor fluctuation condition is determined.

The fan fluctuation condition is a condition that the amount of change in the rotation speed of the outdoor fan (5) during the second fan reference time (for example, 15 seconds) is equal to or greater than the second fan reference value. Under this fan fluctuation condition, the amount of change in the rotation speed of the outdoor fan (5) is the absolute value of the amount of increase or decrease in the rotation speed of the outdoor fan (5). The target overheating degree setting unit (98) changes from "the rotation speed RF of the outdoor fan (5) at the time of determining the fan fluctuation condition" to "before the reference time for the second fan at that time (15 seconds in the above example). The absolute value of the value (RF-RF') obtained by subtracting the rotation speed RF'" of the outdoor fan (5) in the previous case is defined as the" change amount of the rotation speed of the outdoor fan (5) ". In the present embodiment, the reference value for the second fan is 10% of the maximum value of the rotation speed of the outdoor fan (5).

<Second condition>
The second condition is that both the proper discharge side condition and the stable condition are satisfied. When this second condition is satisfied, it can be determined that the liquid back phenomenon has not occurred.

[Appropriate conditions on the discharge side]
The appropriate condition on the discharge side is that the superheat degree SHd of the refrigerant discharged from the compressor (31) is equal to or higher than the third reference discharge superheat degree SHd_r3 (SHd ≧ SHd_r3). In the present embodiment, the third reference discharge superheat degree SHd_r3 is, for example, 20 ° C. When the appropriate conditions on the discharge side are satisfied, it can be determined that the liquid back phenomenon has not occurred because the degree of superheat SHd is sufficiently large.

The appropriate discharge side condition may be a condition that the temperature Td of the refrigerant discharged from the compressor (31) is equal to or higher than the third reference discharge temperature Td_r3 (Td ≧ Td_r3). The third reference discharge temperature Td_r3 is set to a value higher than the first reference discharge temperature Td_r1. In this case as well, if the appropriate discharge side conditions are satisfied, it can be determined that the liquid back phenomenon has not occurred.

[Stable conditions]
The stable condition is a condition that the compressor stable condition or the fan stable condition is satisfied. This stable condition is a condition indicating that the fluctuation of the state of the refrigeration cycle is small. When the fluctuation of the state of the refrigeration cycle is small, the behavior of the refrigerant in the refrigerant circuit (11) becomes stable, and it can be determined that the liquid back phenomenon does not occur.

The compressor stability condition is a condition that the amount of change in the rotation speed of the compressor (31) in the reference time for the first compressor (for example, 120 seconds) is equal to or less than the reference value for the first compressor. Under this compressor stabilization condition, the amount of change in the rotational speed of the compressor (31) is the absolute value of the amount of increase or decrease in the rotational speed of the compressor (31). The target overheating degree setting unit (98) changes from "rotation speed RC of the compressor (31) at the time of determining the compressor stability condition" to "before the reference time for the first compressor at that time" (in the above example, The absolute value of the value (RC-RC') obtained by subtracting the rotation speed RC'" of the compressor (31) 120 seconds ago is defined as the" change amount of the rotation speed of the compressor (31) ". In the present embodiment, the reference value for the first compressor is 8% of the rotation speed of the compressor (31) at the time when the compressor stability condition is determined.

The fan stabilization condition is a condition that the amount of change in the rotation speed of the outdoor fan (5) in the reference time for the first fan (for example, 120 seconds) is equal to or less than the reference value for the first fan. Under this fan stabilization condition, the amount of change in the rotation speed of the outdoor fan (5) is the absolute value of the amount of increase or decrease in the rotation speed of the outdoor fan (5). The target overheating degree setting unit (98) changes from "the rotation speed RF of the outdoor fan (5) at the time of determining the fan stability condition" to "before the reference time for the first fan at that time (120 seconds in the above example). The absolute value of the value (RF-RF') obtained by subtracting the rotation speed RF'" of the outdoor fan (5) in the previous case is defined as the" change amount of the rotation speed of the outdoor fan (5) ". In the present embodiment, the reference value for the first fan is 10% of the maximum value of the rotation speed of the outdoor fan (5).

<Third condition>
The third condition is that the second discharge side low temperature condition is satisfied and the fluctuation condition is not satisfied. When the third condition is satisfied, it can be determined that the possibility of the liquid back phenomenon is lower than that during the first condition being satisfied. Further, when the third condition is satisfied, it can be determined that the possibility of the liquid back phenomenon is higher than that during the second condition being satisfied.

[Second discharge side low temperature condition]
The second discharge side low temperature condition is a condition that the superheat degree SHd of the refrigerant discharged from the compressor (31) is equal to or less than the second reference discharge superheat degree SHd_r2 (SHd ≦ SHd_r2). In the present embodiment, the second reference discharge superheat degree SHd_r2 is, for example, 18 ° C. When the second discharge side low temperature condition is satisfied, it can be determined that the possibility of the liquid back phenomenon is slightly high.

The second discharge side low temperature condition may be a condition that the temperature Td of the refrigerant discharged from the compressor (31) is equal to or less than the second reference discharge temperature Td_r2 (Td ≦ Td_r2). The second reference discharge temperature Td_r2 is set to a value higher than the first reference discharge temperature Td_r1 and lower than the third reference discharge temperature Td_r3. Also in this case, if the second discharge side low temperature condition is satisfied, it can be determined that the possibility of the liquid back phenomenon is slightly high.

<Fourth condition>
The fourth condition is that the temperature Td of the refrigerant discharged from the compressor (31) is equal to or higher than the fourth reference discharge temperature Td_r4 (Td ≧ Td_r4). The temperature Td is a measured value of the discharge temperature sensor (84). In the present embodiment, the fourth reference discharge temperature Td_r4 is, for example, 100 ° C. When the fourth condition is satisfied, it can be determined that the temperature of the refrigerant discharged from the compressor (31) is too high and there is a high possibility that the compressor (31) will be damaged.

The fourth condition may be a condition that the superheat degree SHd of the refrigerant discharged from the compressor (31) is equal to or higher than the fourth reference discharge superheat degree SHd_r4 (SHd ≧ SHd_r4). In a general refrigeration cycle, when the temperature Td of the refrigerant discharged from the compressor (31) is high, the superheat degree SHd of the refrigerant is also usually high. Therefore, even when the superheat degree SHd is 4th standard discharge superheat degree SHd_r4 or more, it is judged that the temperature of the refrigerant discharged from the compressor (31) is too high and there is a high possibility that the compressor (31) will be damaged. it can.

-Features of the embodiment (1)-
The chiller device (1) of the present embodiment includes a refrigerant circuit (11) and a controller (90). The refrigerant circuit (11) has a compressor (31), an expansion valve (36,22a, 22b) and a heat exchanger (15,21a, 21b), and performs a refrigeration cycle. The controller (90) adjusts the opening degree of the expansion valve (36,22a, 22b) so that the degree of superheat of the refrigerant sucked into the compressor (31) becomes the target degree of superheat. The controller (90) performs a target adjustment operation. In the target adjusting operation, the controller (90) adjusts the target degree of superheat according to the state of the refrigeration cycle performed by the refrigerant circuit (11). When the first condition is satisfied during the target adjustment operation, the controller (90) performs the first target holding operation. The first condition is a condition indicating that there is a high possibility of a liquid back phenomenon in which the compressor (31) inhales wet vapor. In the first target holding operation, the controller (90) keeps the target superheat degree at the first target value.

In the chiller device (1) of the present embodiment, the controller (90) performs a target adjusting operation. In the target adjusting operation, the controller (90) adjusts the target degree of superheat according to the state of the refrigeration cycle performed by the refrigerant circuit (11). By adjusting the opening degree of the expansion valve (36,22a, 22b) based on the target superheat degree determined by the controller (90) in the target adjustment operation, the superheat degree of the refrigerant sucked into the compressor (31) ( The suction superheat degree) can be set to an appropriate value according to the state of the refrigeration cycle.

When the suction superheat degree becomes an appropriate value, the refrigerant superheat degree at the outlet of the heat exchanger (15,21a, 21b) that functions as an evaporator is an appropriate value (specifically, a value that is neither too large nor too small). ), And the region where the saturated refrigerant flows in the heat exchangers (15, 21a, 21b) that function as an evaporator can be sufficiently secured. Therefore, according to the present embodiment, the heat exchange performance of the heat exchangers (15, 21a, 21b) functioning as an evaporator can be fully exhibited, and the operating efficiency of the chiller device (1) can be improved. Is possible.

Further, in the chiller device (1) of the present embodiment, when the first condition is satisfied during the target adjustment operation, the controller (90) switches the operation from the target adjustment operation to the first target holding operation. When the possibility of the liquid back phenomenon becomes high, this controller (90) stops the adjustment of the target superheat degree by the target adjustment operation and keeps the target superheat degree at the first target value. If the first target value is set to a sufficiently large value, the refrigerant sucked into the compressor (31) can be kept in a gas single-phase state. Therefore, according to the present embodiment, it is possible to suppress damage to the compressor (31) due to the liquid back phenomenon and improve the reliability of the chiller device (1).

-Characteristics of the embodiment (2)-
The controller (90) of the chiller device (1) of the present embodiment adjusts the target superheat degree within the range of the minimum target value or more and the maximum target value or less in the target adjustment operation. In addition, this controller (90) keeps the target degree of superheat at the first target value, which is a value equal to or higher than the maximum target value, in the first target holding operation.

The controller (90) of the chiller device (1) of the present embodiment keeps the target superheat degree at the first target value in the first target holding operation. The first target value is a value equal to or higher than the maximum target value. In this first target holding operation, the target superheat degree is held at a sufficiently large value. Therefore, according to the present embodiment, the refrigerant sucked into the compressor (31) can be kept in a gas single-phase state, and damage to the compressor (31) due to the liquid back phenomenon can be suppressed.

-Characteristics of the embodiment (3)-
In the controller (90) of the present embodiment, the first condition is a condition that the first discharge side low temperature condition or the fluctuation condition is satisfied. The fluctuation condition is a condition indicating that the state of the refrigeration cycle fluctuates greatly. The first discharge side low temperature condition is a condition that the superheat degree of the refrigerant discharged from the compressor (31) is equal to or less than the first reference discharge superheat degree.

Here, it can be said that there is a high possibility of a liquid back phenomenon when the degree of superheat of the refrigerant sucked into the compressor (31) is relatively low and when the state of the refrigeration cycle performed by the refrigerant circuit (11) fluctuates greatly. .. Therefore, in the controller (90) of the present embodiment, the condition that the first discharge side low temperature condition or the fluctuation condition is satisfied is set as the first condition.

-Characteristics of the embodiment (4)-
The controller (90) of the present embodiment lowers the target superheat degree when the second condition indicating that the liquid back phenomenon does not occur is satisfied in the target adjustment operation, and there is a possibility of the liquid back phenomenon. When the third condition, which indicates that the condition is higher than that during the second condition, is satisfied, the target degree of overheating is raised.

The controller (90) of the present embodiment lowers the target degree of superheat when the second condition is satisfied. When the second condition is satisfied, it can be determined that the liquid back phenomenon has not occurred. Therefore, the controller (90) lowers the target degree of superheat to improve the operating efficiency of the chiller device (1). The controller (90) raises the target degree of superheat when the third condition is satisfied. When the third condition is satisfied, the possibility of the liquid back phenomenon is higher than when the second condition is satisfied. Therefore, the controller (90) raises the target degree of superheat and reduces the possibility of the liquid back phenomenon.

-Characteristics of the embodiment (5)-
The controller (90) of the present embodiment performs the target adjusting operation when the second condition indicating that the liquid back phenomenon does not occur is satisfied during the first target holding operation.

When the second condition is satisfied during the first target holding operation, the controller (90) of the present embodiment switches the operation from the first target holding operation to the target adjusting operation. When the second condition is satisfied, it can be determined that the liquid back phenomenon has not occurred. Therefore, when the second condition is satisfied during the first target holding operation, the controller (90) adjusts the target superheat degree according to the state of the refrigeration cycle performed by the refrigerant circuit (11). According to the present embodiment, when it can be determined that the liquid back phenomenon has not occurred, it is possible to improve the operating efficiency of the chiller device (1) by adjusting the target degree of superheat.

In particular, the controller (90) of the present embodiment performs the target lowering operation of the target adjusting operation when the second condition is satisfied during the first target holding operation. Specifically, when the second condition is satisfied during the first target holding operation, the controller (90) changes the target superheat degree to "first target value-predetermined value B". As described above, in the present embodiment, the first target value is the maximum target value A. Therefore, the controller (90) of the present embodiment lowers the target degree of superheat and improves the operating efficiency of the chiller device (1) when the second condition indicating that the liquid back phenomenon does not occur is satisfied.

-Characteristics of the embodiment (6)-
In the controller (90) of the present embodiment, the second condition is that both the discharge side proper condition and the stable condition are satisfied. The stable condition is a condition indicating that the fluctuation of the state of the refrigeration cycle is small. The appropriate condition on the discharge side is that the degree of superheat of the refrigerant discharged from the compressor (31) is equal to or higher than the third reference degree of superheat of discharge.

Here, when the degree of superheat of the refrigerant sucked into the compressor (31) is a certain value or more and the fluctuation of the state of the refrigerating cycle performed by the refrigerant circuit (11) is small, it can be said that the liquid back phenomenon does not occur. .. Therefore, in the controller (90) of the present embodiment, the condition that both the discharge side appropriate condition and the stable condition are satisfied is set as the second condition.

-Characteristics of the embodiment (7)-
The chiller device (1) of the present embodiment includes an outdoor fan (5) that sends air to the outdoor heat exchangers (21a, 21b). In the controller (90) of the present embodiment, the stable condition is "the amount of change in the rotation speed of the compressor (31) during the time for the first compressor is equal to or less than the reference value for the first compressor" or "the first. The condition is that the amount of change in the rotation speed of the fan (5) during the time for one fan is equal to or less than the reference value for the first fan. "

Here, when the rotation speed of the compressor (31) changes, the flow rate of the refrigerant circulating in the refrigerant circuit (11) changes. Further, when the rotation speed of the outdoor fan (5) changes, the amount of heat exchange between the refrigerant and the air in the heat exchangers (21a, 21b) changes. Thus, the rotational speeds of the compressor (31) and the outdoor fan (5) affect the state of the refrigeration cycle performed by the refrigerant circuit (11). Therefore, the controller (90) of the present embodiment has a condition indicating that the change in the rotational speed of the compressor (31) or the outdoor fan (5) is small, and a stable condition indicating that the change in the state of the refrigeration cycle is small. And.

-Features of the embodiment (8)-
The controller (90) of the present embodiment performs the second target holding operation when the fourth condition is satisfied during the target adjusting operation. The fourth condition is that the temperature of the refrigerant discharged from the compressor (31) is equal to or higher than the fourth reference discharge temperature. The second target holding operation is an operation of maintaining the target superheat degree at the second target value which is a value equal to or less than the minimum target value.

When the fourth condition is satisfied during the target adjustment operation, the controller (90) of the present embodiment switches the operation from the target adjustment operation to the second target holding operation. When the fourth condition is satisfied, it can be determined that the temperature of the refrigerant discharged from the compressor (31) is relatively high. Therefore, when the fourth condition is satisfied during the target adjustment operation, the controller performs the second target holding operation. In the second target holding operation, the controller (90) keeps the target superheat degree at the second target value which is a value equal to or less than the minimum target value. When the degree of superheat of the refrigerant sucked into the compressor becomes low, the temperature of the refrigerant discharged from the compressor (31) becomes low. Therefore, according to the present embodiment, the reliability of the compressor (31) can be ensured by preventing the refrigerant discharged from the compressor (31) from being overheated.

-Characteristics of the embodiment (9)-
When the third condition is satisfied during the second target holding operation, the controller (90) of the present embodiment performs the target adjusting operation. The third condition is a condition indicating that the possibility of the liquid back phenomenon is lower than that during the establishment of the first condition.

When the third condition is satisfied during the second target holding operation, the controller (90) of the present embodiment switches the operation from the second target holding operation to the target adjusting operation. It can be determined that the possibility of the liquid back phenomenon is lower while the third condition is satisfied than when the first condition is satisfied. Therefore, when the third condition is satisfied during the second target holding operation, the controller (90) performs the target raising operation of the target adjusting operation instead of the first target holding operation. Specifically, when the third condition is satisfied during the second target holding operation, the controller (90) sets the target superheat degree from the second target value (minimum target value C in this embodiment) to the first target. The value is changed to "second target value + predetermined value B" instead of the value (maximum target value A in this embodiment). Therefore, according to the present embodiment, it is possible to increase the target superheat degree and reduce the possibility of the liquid back phenomenon while suppressing the decrease in the operating efficiency of the chiller device (1) due to the increase in the target superheat degree.

-Features of the embodiment (10)-
In the controller (90) of the present embodiment, the third condition is that the second discharge side low temperature condition is satisfied and the fluctuation condition is not satisfied. The fluctuation condition is a condition indicating that the state of the refrigeration cycle fluctuates greatly. The second discharge side low temperature condition is a condition that the superheat degree of the refrigerant discharged from the compressor (31) is equal to or less than the second reference discharge superheat degree.

Here, the degree of superheat of the refrigerant sucked into the compressor (31) is a value below a certain level, but when the fluctuation of the state of the refrigerating cycle performed by the refrigerant circuit (11) is not large, the possibility of the liquid back phenomenon is possible. It can be said that it is not so expensive. Therefore, in the controller (90) of the present embodiment, the condition that the second discharge side low temperature condition is satisfied and the fluctuation condition is not satisfied is set as the third condition.

-Features of the embodiment (11)-
The chiller device (1) of the present embodiment includes an outdoor fan (5) that sends air to the outdoor heat exchangers (21a, 21b). In the controller (90) of the present embodiment, the fluctuation condition is "the amount of change in the rotation speed of the compressor (31) during the time for the second compressor is equal to or greater than the reference value for the second compressor", or "the second compressor. The condition is that the amount of change in the rotation speed of the outdoor fan (5) during the time for two fans is equal to or greater than the reference value for the second fan. "

Here, when the rotation speed of the compressor (31) changes, the flow rate of the refrigerant circulating in the refrigerant circuit (11) changes. Further, when the rotation speed of the outdoor fan (5) changes, the amount of heat exchange between the refrigerant and the air in the heat exchangers (21a, 21b) changes. Thus, the rotational speeds of the compressor (31) and the outdoor fan (5) affect the state of the refrigeration cycle performed by the refrigerant circuit (11). Therefore, the controller (90) of the present embodiment has a condition indicating that the change in the rotation speed of the compressor (31) or the outdoor fan (5) is large, and a fluctuation condition indicating that the state of the refrigeration cycle has a large change. And.

-Characteristics of the embodiment (12)-
The controller (90) of the present embodiment performs the second target holding operation when the fourth condition is satisfied during the first target holding operation.

When the fourth condition is satisfied during the first target holding operation, the controller (90) of the present embodiment switches the operation from the first target holding operation to the second target holding operation. In the second target holding operation, the controller (90) keeps the target superheat degree at the second target value which is a value equal to or less than the minimum target value. When the degree of superheat of the refrigerant sucked into the compressor (31) becomes low, the temperature of the refrigerant discharged from the compressor (31) becomes low. Therefore, according to the present embodiment, the reliability of the compressor (31) can be ensured by preventing the refrigerant discharged from the compressor (31) from being overheated.

-Characteristics of the embodiment (13)-
The controller (90) of the present embodiment performs the first target holding operation when the first condition is satisfied during the second target holding operation.

When the first condition is satisfied during the second target holding operation, the controller (90) of the present embodiment switches the operation from the second target holding operation to the first target holding operation. In the first target holding operation, the controller (90) keeps the target superheat degree at the first target value which is a value equal to or higher than the maximum target value. In the first target holding operation of the present embodiment, the target superheat degree is held at a sufficiently large value. Therefore, according to the present embodiment, the refrigerant sucked into the compressor (31) can be kept in a gas single-phase state, and damage to the compressor (31) due to the liquid back phenomenon can be suppressed.

-Modified example of the embodiment-
In the chiller device (1) of the present embodiment, each refrigerant circuit (11, 12) may include one outdoor heat exchanger and one heat source side expansion valve. Further, each refrigerant circuit (11, 12) may be provided with three or more branch pipelines provided with one outdoor heat exchanger and one heat source side expansion valve.

The application of the refrigerating apparatus of the present embodiment is not limited to the chiller apparatus (1) that exchanges heat with the heat medium. The refrigerating device of the present embodiment may be, for example, a so-called direct expansion type air conditioner. In this case, the refrigerating apparatus, which is a direct expansion type air conditioner, exchanges heat with the air in the air-conditioned space for the refrigerant circulating in the refrigerant circuit.

Although the embodiments and modifications have been described above, it will be understood that various modifications of the forms and details are possible without departing from the purpose and scope of the claims. Further, the above embodiments and modifications may be appropriately combined or replaced as long as the functions of the subject of the present disclosure are not impaired.

As described above, the present disclosure is useful for refrigeration equipment.

1 Chiller device (refrigerator)
5 outdoor fan
11 Refrigerant circuit
15 Water heat exchanger (heat exchanger)
21a 1st outdoor heat exchanger (heat exchanger)
21b 2nd outdoor heat exchanger (heat exchanger)
22a 1st heat source side expansion valve (expansion valve)
22b 2nd heat source side expansion valve (expansion valve)
31 compressor
36 User side expansion valve (expansion valve)
90 controller

Claims (9)

A refrigerant circuit (11) in which a compressor (31), an expansion valve (36,22a, 22b) and a heat exchanger (15,21a, 21b) are provided to perform a refrigeration cycle, and
A freezer equipped with a controller (90) for adjusting the opening degree of the expansion valve (36,22a, 22b) so that the degree of superheat of the refrigerant sucked into the compressor (31) becomes the target degree of superheat. And
The above controller (90)
The target adjustment operation for adjusting the target superheat degree according to the state of the refrigeration cycle performed by the refrigerant circuit (11), and the target adjustment operation.
When the first condition indicating that the upper Symbol compressor (31) is likely the liquid back phenomenon for sucking wet steam is established in the target adjustment operation, the target degree of superheat by stopping the target adjustment operation Perform the first target holding operation to keep the first target value,
In the target adjustment operation, the controller (90)
When the second condition indicating that the liquid back phenomenon does not occur is satisfied, the target degree of superheat is lowered.
When the third condition, which indicates that the possibility of the liquid back phenomenon is higher than that during the second condition, is satisfied, the target superheat degree is raised.
The second condition is that both the proper discharge side condition and the stable condition indicating that the fluctuation of the state of the refrigeration cycle is small are satisfied.
The appropriate discharge side condition is that the degree of superheat of the refrigerant discharged from the compressor (31) is equal to or higher than the third reference discharge degree of superheat, or the temperature of the refrigerant discharged from the compressor (31) is the first. 3 A refrigerating apparatus characterized in that the temperature is equal to or higher than the reference discharge temperature. A refrigerant circuit (11) in which a compressor (31), an expansion valve (36,22a, 22b) and a heat exchanger (15,21a, 21b) are provided to perform a refrigeration cycle, and
A freezer equipped with a controller (90) for adjusting the opening degree of the expansion valve (36,22a, 22b) so that the degree of superheat of the refrigerant sucked into the compressor (31) becomes the target degree of superheat. And
The above controller (90)
The target adjustment operation for adjusting the target superheat degree according to the state of the refrigeration cycle performed by the refrigerant circuit (11), and the target adjustment operation.
When the first condition indicating that the upper Symbol compressor (31) is likely the liquid back phenomenon for sucking wet steam is established in the target adjustment operation, the target degree of superheat by stopping the target adjustment operation Perform the first target holding operation to keep the first target value,
When the second condition indicating that the liquid back phenomenon does not occur is satisfied during the first target holding operation, the controller (90) performs the target adjusting operation.
The second condition is that both the proper discharge side condition and the stable condition indicating that the fluctuation of the state of the refrigeration cycle is small are satisfied.
The appropriate discharge side condition is that the degree of superheat of the refrigerant discharged from the compressor (31) is equal to or higher than the third reference discharge degree of superheat, or the temperature of the refrigerant discharged from the compressor (31) is the first. 3 A refrigerating apparatus characterized in that the temperature is equal to or higher than the reference discharge temperature. In claim 1 or 2 ,
In the target adjustment operation, the controller (90) adjusts the target superheat degree within a range of the minimum target value or more and the maximum target value or less.
In the first target holding operation, the controller (90) is a freezing device that keeps the target superheat degree at the first target value, which is a value equal to or higher than the maximum target value. In claim 1 or 2 ,
While further equipped with a fan (5) that sends air to the heat exchangers (21a, 21b),
The stable condition is that the amount of change in the rotation speed of the compressor (31) during the time for the first compressor is equal to or less than the reference value for the first compressor, or the rotation of the fan (5) during the time for the first fan. A refrigerating apparatus characterized in that the amount of change in speed is equal to or less than the reference value for the first fan. In claim 3 ,
When the fourth condition is satisfied during the target adjustment operation, the controller (90) performs a second target holding operation for maintaining the target superheat degree at the second target value which is a value equal to or less than the minimum target value.
The fourth condition is that the degree of superheat of the refrigerant discharged from the compressor (31) is equal to or higher than the fourth reference degree of superheat of discharge, or the temperature of the refrigerant discharged from the compressor (31) is the fourth. A refrigerating apparatus characterized in that the temperature is equal to or higher than the standard discharge temperature. In claim 1,
The third condition is a condition that the second low temperature condition on the discharge side is satisfied and the fluctuation condition indicating that the state of the refrigeration cycle fluctuates greatly is not satisfied.
The second discharge side low temperature condition is a condition that the superheat degree of the refrigerant discharged from the compressor (31) is equal to or less than the second reference discharge superheat degree, or the temperature of the refrigerant discharged from the compressor (31). Is a refrigerating apparatus characterized in that the temperature is equal to or lower than the second reference discharge temperature. In claim 6 ,
While further equipped with a fan (5) that sends air to the heat exchangers (21a, 21b),
The fluctuation condition is that the amount of change in the rotation speed of the compressor (31) during the time for the second compressor is equal to or greater than the reference value for the second compressor, or the rotation of the fan (5) during the time for the second fan. A refrigerating apparatus characterized in that the amount of change in speed is equal to or greater than the reference value for the second fan. In claim 5 ,
The controller (90) is a refrigerating apparatus characterized in that when the fourth condition is satisfied during the first target holding operation, the second target holding operation is performed. In claim 5 ,
The controller (90) is a refrigerating apparatus characterized in that when the first condition is satisfied during the second target holding operation, the first target holding operation is performed.

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