JP2002228297A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce transmission lines used for transmitting thermo-off signals and thermo-on signals among units in a refrigerating device provided with a multi-circuit constituted by connecting an outdoor unit (2), an indoor unit (3), a cold storage unit (4), and a refrigerating unit (5) to each other. SOLUTION: In the case where the low pressure in a refrigerant circuit (6) becomes a prescribed value or lower when the operating frequency of an inverter compressor (11) is a prescribed lowest frequency, the operation of the compressor (11) is stopped. When the low pressure of the circuit (6) becomes higher than the prescribed value after a prescribed period of time has elapsed from the operation stoppage of the compressor (11), the compressor (11) is restarted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus having a heat source side unit, an indoor air conditioning unit, and a cooling unit.

[0002]

2. Description of the Related Art For example, in a convenience store or the like, cooling and heating of food and drink and food are performed by a single refrigeration apparatus. This type of refrigeration apparatus includes an outdoor unit provided with a compressor, an indoor air conditioning unit for performing indoor air conditioning, and a cooling unit (refrigeration unit, refrigeration unit) for cooling food and drink in order to perform air conditioning and cooling of food and drink. Unit etc.) are connected.

When the load on the refrigerating apparatus is small, the refrigerant cannot sufficiently evaporate in the evaporator, and the wet refrigerant returns to the compressor. Therefore, if the operation is continued as it is, the reliability of the compressor may be reduced. Therefore, in the conventional refrigeration system, the following control is executed to protect the compressor.

[0004] That is, each of the indoor air-conditioning unit and the cooling unit at the time of cooling is switched to a thermo-off state in which operation is stopped when the indoor air temperature or the temperature in the refrigerator falls below a predetermined temperature, and a thermo-off state indicating the thermo-off state. Send the signal to the outdoor unit. on the other hand,
When the indoor air temperature or the indoor temperature becomes higher than the predetermined temperature, the mode is switched to a thermo-on state for restarting the operation, and a thermo-on signal indicating the thermo-on state is transmitted to the outdoor unit. When the outdoor unit receives the thermo-off signals from all the indoor air conditioning units and the cooling units, the outdoor unit temporarily stops the operation of the compressor to avoid the wet operation. After stopping the operation of the compressor,
Upon receiving a thermo-on signal from at least one of the indoor air conditioning unit and the cooling unit, the compressor is restarted. Conventionally, the wet operation is prevented by the above control.

[0005]

However, in the conventional apparatus, the indoor air-conditioning unit and the outdoor unit, and the cooling unit and the outdoor unit require a transmission line for transmitting and receiving a thermo-off signal and a thermo-on signal. Therefore, the configuration of the device has been complicated by the amount of the transmission path.
In particular, since a refrigeration apparatus having a multi-circuit has a complicated unit configuration, the transmission line tends to be complicated accordingly.

Further, when a plurality of units are combined to form an apparatus, a unit capable of transmitting and receiving to and from an outdoor unit has to be selected as an indoor air conditioning unit or a cooling unit. There were few. In other words, a unit that can be transmitted and received must be selected in advance, and a unit that meets the user's preference cannot be freely combined.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and simplifies the configuration of an apparatus and enables free combination of units by reducing the number of transmission paths for a thermo-off signal and a thermo-on signal. The purpose is to.

[0008]

In order to achieve the above-mentioned object, the present invention provides a method of controlling the capacity of a refrigerant circuit using a compressor whose capacity can be controlled, and controlling the refrigerant circuit when the compressor is operating at a minimum capacity. When the low pressure falls below a predetermined value, the compressor is stopped,
When a predetermined time elapses after the stop and the low pressure becomes equal to or higher than a predetermined value, the compressor is restarted.

Specifically, the first invention is a heat source side unit having a compressor and a heat source side heat exchanger whose capacity can be controlled between a predetermined minimum capacity and a maximum capacity, and heating or cooling indoor air. An indoor air-conditioning unit having an indoor heat exchanger,
A refrigeration apparatus including a refrigerant circuit including at least a cooling unit having a cooling heat exchanger for cooling an object to be cooled, comprising: a pressure detection unit configured to detect a low pressure of the refrigerant circuit; Capacity control means for controlling the capacity of the compressor based on the low pressure of the compressor, when the low pressure of the refrigerant circuit is less than or equal to a predetermined value when the compressor is operating at the minimum capacity, Starting and stopping control means for restarting the operation of the compressor when a predetermined time has elapsed since the operation of the compressor was stopped and the low pressure of the refrigerant circuit became equal to or higher than a predetermined value while the operation of the compressor was stopped. Is what it is.

[0010] In the first aspect of the invention, when the capacity of the apparatus becomes insufficient and the low pressure of the refrigerant circuit increases, the capacity control means increases the capacity of the compressor. This increases the capacity of the device and reduces the low pressure. On the other hand, when the capacity of the apparatus becomes excessive and the low pressure decreases, the capacity control means reduces the capacity of the compressor. This reduces the capacity of the device and increases the low pressure. By such capacity control, operation commensurate with the load is performed between the minimum capacity and the maximum capacity of the compressor.

[0011] However, even if the capacity of the compressor is reduced to the minimum capacity, the capacity may still be excessive, and in such a case, the suction refrigerant becomes moist. In this case, since the capacity of the compressor cannot be further reduced, the wet operation cannot be avoided by the capacity control. Therefore, in the first aspect of the invention, attention is paid to the fact that the low pressure decreases when the capacity becomes excessive. When the low pressure falls below a predetermined value, it is estimated that the operation state becomes the wet operation state, and the compressor is stopped. Let it. This avoids wet running. On the other hand, after the operation of the compressor is stopped, the refrigeration load increases, and the low pressure increases. Therefore,
When a predetermined time has elapsed since the operation of the compressor was stopped and the low pressure became equal to or higher than the predetermined value, the compressor restarts operation because there is no danger of wet operation. This restarts the cooling operation in the cooling unit.

As described above, the operation stop and restart of the compressor are performed based on the low pressure of the refrigerant circuit.
The transmission and reception of the thermo-off signal and the thermo-on signal between the indoor air conditioning unit and the heat source side unit and between the cooling unit and the heat source side unit become unnecessary. Therefore, transmission-less operation between units is achieved. Accordingly, the configuration of the device is simplified, and the units can be freely combined.

According to a second aspect of the present invention, in the refrigeration apparatus according to the first aspect, the cooling unit includes a refrigeration unit having a refrigeration heat exchanger and cooling the object to be cooled at a lower temperature than the refrigeration heat exchanger. And a refrigerating unit having a refrigerating heat exchanger.

In the second aspect of the present invention, the structure of the refrigerant circuit becomes more complicated, so that the effect of reducing transmission is more remarkably exhibited.

[0015]

As described above, according to the present invention, the operating state is estimated based on the operating capacity of the compressor and the low pressure of the refrigerant circuit, and the operation of the compressor is stopped when the wet operation is likely. Therefore, wet operation can be avoided even if there is no transmission path for transmitting and receiving the thermo-off signal. In addition, since the compressor is restarted based on the elapsed time after the operation of the compressor is stopped and the low pressure, the operation can be automatically restarted even if there is no transmission line for transmitting and receiving the thermo-on signal. Can be. Accordingly, transmissionless transmission between units can be achieved, and the configuration of the device can be simplified. In addition, the degree of freedom in unit combination can be increased.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

-Configuration of Refrigeration Apparatus- As shown in FIG. 1, a refrigeration apparatus (1) according to the embodiment is a refrigeration apparatus that performs indoor air conditioning and refrigeration and freezing of food and drink, and is installed in a convenience store. ing. The refrigeration apparatus (1) includes a refrigerant circuit (6) in which an outdoor unit (2), an indoor unit (3), a refrigeration unit (4), and a refrigeration unit (5) are connected. The outdoor unit (2) is a unit on the heat source side, and the indoor unit (3), the refrigeration unit (4), and the freezing unit (5) are units on the use side. The refrigerant circuit (6) is constituted by a so-called multi-circuit.

The outdoor unit (2) includes an inverter compressor (11) and a non-inverter compressor connected in parallel with each other.
(12), an outdoor heat exchanger (13), and a receiver (14). The inverter compressor (11) is a compressor whose capacity can be freely controlled. The range of the operating frequency of the inverter compressor (11) is not particularly limited.
00 Hz is set. That is, the inverter compressor
(11) is configured such that the capacity is freely changed between a predetermined minimum capacity and a maximum capacity.

A four-way switching valve is provided on the discharge side of the compressor (11, 12).
(15) is provided. The discharge pipe of the compressor (11, 12)
It is connected to the first port (lower port in FIG. 1) of the four-way switching valve (15). Between the compressors (11, 12) and the four-way switching valve (15), an oil separator (16), a temperature sensor (81), and a pressure sensor (8
2) is provided. A high-pressure switch (40) is provided on a discharge pipe of the inverter compressor (11). The suction pipe (17) of the compressor (11, 12) is provided with a low pressure sensor (83) for detecting the low pressure LP of the refrigerant circuit (6). The oil return pipe (18) connects the oil separator (16) and the suction pipe (17). The oil return pipe (18) is provided with a solenoid valve (19). One end of the oil equalizing pipe (20) of the compressor (11, 12) is connected to the side of the non-inverter compressor (12), and the other end of the oil equalizing pipe (20) is connected to the suction pipe of the inverter compressor (11). Connected to 22). The oil equalizing pipe (20) is provided with a solenoid valve (21).

The refrigerant circuit (6) of the refrigeration system (1) includes:
No low pressure switch is provided. Therefore, even if the low pressure of the refrigerant circuit (6) decreases, the compressors (11, 12) are not forcibly stopped by the low pressure switch.

The second port (port on the right side in FIG. 1) of the four-way switching valve (15) is connected to one end of the outdoor heat exchanger (13) via a refrigerant pipe. The other end of the outdoor heat exchanger (13) is connected to a receiver (14) via a refrigerant pipe (24). The liquid pipe (25) and the refrigerant pipe (24) of the receiver (14) are connected via a bypass pipe (26). In the bypass pipe (26),
An electronic expansion valve (27) is provided. One end of a refrigerant pipe (28) is connected between the electronic expansion valve (27) and the connection part of the liquid side pipe (25) in the bypass pipe (26). Refrigerant piping (2
The other end of 8) is connected to a suction pipe (17). Refrigerant piping
(28) is provided with an electromagnetic valve (29).

The gas side pipe (30) of the receiver (14) is branched, one branch pipe (31) is connected to the suction pipe (17), and the other branch pipe (32) is connected to the non-inverter compressor ( 12) It is connected to the discharge pipe. The branch pipe (31) is provided with a solenoid valve (33) and a temperature sensor (34). The branch pipe (32) is provided with a check valve (CV1) for preventing the flow of the refrigerant from the compressors (11, 12).

The liquid side pipe (25) of the receiver (14) branches into two refrigerant pipes (35, 36), and these refrigerant pipes (35, 36) extend outside the outdoor unit (2). . The refrigerant pipe (35) and the portion of the refrigerant pipe (24) near the receiver (14) are the refrigerant pipe (41)
Connected through. The refrigerant pipe (41) has a receiver
A check valve (CV2) for preventing the flow of the refrigerant from (14) is provided. The refrigerant pipe (24) is also provided with a check valve (CV3) for preventing the flow of the refrigerant from the receiver (14).

The suction pipe (17) of the compressor (11, 12) is connected to the third port (upper port in FIG. 1) of the four-way switching valve (15). A temperature sensor (37) is provided in the suction pipe (17). An outdoor unit is provided between the connection part of the suction pipe (17) to the four-way switching valve (15) and the connection part to the branch pipe (31).
A refrigerant pipe (38) extending to the outside of (2) is connected.

The fourth port (port on the left side in FIG. 1) of the four-way switching valve (15) is connected to a refrigerant pipe (39) extending outside the outdoor unit (2). The four-way switching valve (15) is set so as to be freely switchable between a first state and a second state described below. The first state communicates between the first port and the second port and sets the third state. The second state is a state in which the first port communicates with the fourth port and the second port communicates with the third port.

Further, the outdoor unit (2) is provided with an outdoor fan (23) for supplying air to the outdoor heat exchanger (13) and a temperature sensor (50) for detecting outdoor air temperature.

The indoor unit (3) performs indoor air conditioning, and includes an indoor heat exchanger (42) and an indoor electronic expansion valve.
(43) and an indoor fan (44). Indoor heat exchanger (4
One end of 2) is connected to the refrigerant pipe (39). The other end of the indoor heat exchanger (42) is connected to a refrigerant pipe (35). The indoor electronic expansion valve (43) is provided in the refrigerant pipe (35).
The indoor heat exchanger (42) is provided with a temperature sensor (45), and the refrigerant pipe (39) is provided with a temperature sensor (46). In addition,
(51) is a temperature sensor for detecting the indoor air temperature.

The refrigerating unit (4) is for refrigerating food and drink, and includes a refrigerating cooler (47), a refrigerating electronic expansion valve (48), and a refrigerating fan (49). One end of the refrigerating cooler (47) is connected to the refrigerant pipe (36). Refrigerator cooler
The other end of (47) is connected to the refrigerant pipe (38). The refrigeration electronic expansion valve (48) is provided in the refrigerant pipe (36). The refrigerating cooler (47) is provided with a temperature sensor (53), and the refrigerant pipe (38) is provided with a temperature sensor (54). (52) is a temperature sensor for detecting the internal temperature.

The refrigerating unit (5) is for freezing food and drink, and includes a refrigerating compressor (55), a refrigerating cooler (56),
An electronic expansion valve for refrigeration (57) and a fan for refrigeration (58) are provided. The refrigeration unit (5) is connected to a refrigerant pipe (59) branched from the refrigerant pipe (36) and a refrigerant pipe (60) branched from the refrigerant pipe (38). Electronic expansion valve for refrigeration (5
7), the refrigerating cooler (56) and the refrigerating compressor (55) are connected in this order, and the refrigerating electronic expansion valve (57) is connected to the refrigerant pipe (5).
9), and the discharge side of the refrigerating compressor (55) is connected to the refrigerant pipe (6
0). Temperature sensor for refrigeration cooler (56)
A temperature sensor (62) is provided at the outlet pipe of the refrigerating cooler (56) (that is, the pipe between the refrigerating cooler (56) and the refrigerating compressor (55)). Is provided. (63) is a temperature sensor for detecting the internal temperature.

The refrigerating compressor (55) is a variable displacement type compressor and is constituted by an inverter compressor. An oil separator (64) is provided in a discharge pipe of the refrigerating compressor (55). The oil return pipe (65) of the oil separator (64) is a refrigerating compressor
It is connected to the suction pipe (68) of (55). The oil return pipe (65) is provided with a capillary tube (66). In addition,
In FIG. 1, (CV) is a check valve, and (F) is a filter.

The outdoor unit (2) includes a controller (90)
Is provided. The controller (90) includes a capacity control unit (91) that executes capacity control of the inverter compressor (11), and a start / stop control unit (92) that executes start / stop control of the inverter compressor (11).
And Although not shown, the controller (90) includes a first timer and a second timer described later.

In the present embodiment, the capacity control of the entire compressor (11, 12) is performed as follows. That is, when the load is small, only the inverter compressor (11) is driven, and the capacity of the inverter compressor (11) is adjusted according to the load. On the other hand, when the load is large, both the inverter compressor (11) and the non-inverter compressor (12) are driven. Note that when starting the non-inverter compressor (12), the inverter compressor (11, 12) is designed so that the overall capacity changes continuously.
Reduce the capacity of (11). When both the inverter compressor (11) and the non-inverter compressor (12) are running,
The capacity of the inverter compressor (11) is adjusted according to the load.
With the above-described control, capacity control corresponding to a wide range of loads is performed.

The capacity control and start / stop control of the inverter compressor (11) will be described later.

-Operation of Refrigeration System- <Cooling Operation> In the cooling operation, the four-way switching valve (15) connects the first port to the second port and connects the third port to the fourth port. The state is set to the state (first state). The electronic expansion valve (27) of the outdoor unit (2) is set to a fully closed state.
Then, the refrigerant in the refrigerant circuit (6) circulates as shown in FIG.

Specifically, the refrigerant discharged from the compressor (11 or 12) condenses in the outdoor heat exchanger (13) and flows into the receiver (14). After flowing out of the outdoor unit (2), the refrigerant in the receiver (14) is divided into the indoor unit (3), the refrigeration unit (4), and the refrigeration unit (5). Indoor unit
The refrigerant flowing into (3) is decompressed by the indoor electronic expansion valve (43), and then evaporates in the indoor heat exchanger (42) to cool the indoor air. The refrigerant flowing into the refrigeration unit (4) is reduced in pressure to the first predetermined pressure PL1 by the refrigeration electronic expansion valve (48), and then evaporates in the refrigeration cooler (47) to cool the air in the refrigerator.

On the other hand, the refrigerant flowing into the refrigeration unit (5) is reduced to a second predetermined pressure PL2 lower than the first predetermined pressure PL1 by the refrigeration electronic expansion valve (57). The decompressed refrigerant evaporates in the freezing cooler (56) to cool the air in the refrigerator. The refrigerant flowing out of the refrigerating cooler (56) is subjected to a first predetermined pressure PL1 by the refrigerating compressor (55).
, And merges with the refrigerant flowing out of the refrigerator cooler (47) and flows into the outdoor unit (2). The refrigerant flowing into the outdoor unit (2) flows from the indoor unit (3) to the outdoor unit (2).
And is sucked into the compressor (11 or 12).

The refrigerant sucked into the compressor (11 or 12)
It is compressed by the compressor (11 or 12) and repeats the above-described circulation operation again. By the above operation, the refrigerant circuit
In (6), a two-stage compression refrigeration cycle is formed.

In the refrigeration unit (5), the oil separator (64)
The refrigerating machine oil thus separated returns to the suction pipe (68) through the oil return pipe (65), and is collected by the refrigerating compressor (55).

<Heating operation> In the heating operation, the outdoor heat exchanger (1
The operation using 3) and the operation not using the outdoor heat exchanger (13) can be divided. The operation that does not use the outdoor heat exchanger (13) is an operation that is performed when the heating capacity of the indoor unit (3) and the refrigerating capacity of the refrigeration unit (4) and the refrigerating unit (5) are balanced. This is an operation in which the heat balance is maintained between each other. In this operation, there is no need to release heat to the outside via the outdoor heat exchanger (13), so that useless heat exchange does not have to be performed. Therefore, energy saving can be promoted.

First, a heating operation using the outdoor heat exchanger (13) will be described. In this operation, the four-way switching valve
(15) is set to a state (second state) in which the first port and the fourth port communicate with each other and the second port and the third port communicate with each other. The electronic expansion valve (27) of the outdoor unit (2) is set in an open state, and the degree of opening is appropriately adjusted according to the operation state.

The refrigerant in the refrigerant circuit (6) circulates as shown in FIG. Specifically, the refrigerant discharged from the compressor (11 or 12) flows into the indoor unit (3), and is supplied to the indoor heat exchanger.
The air is condensed in (42) and the room air is heated. The refrigerant flowing out of the indoor heat exchanger (42) returns to the outdoor unit (2) and flows into the receiver (14). The refrigerant flowing out of the receiver (14) is divided, and one of the refrigerants is decompressed by the electronic expansion valve (27).
Evaporates in the outdoor heat exchanger (13). The other refrigerant flows out of the outdoor unit (2), and the refrigeration unit (4) and the freezing unit
(5). Refrigeration unit (4) and refrigeration unit
In (5), cooling and freezing are executed in the same manner as in the cooling operation described above. The refrigerant flowing out of the refrigeration unit (4) and the refrigeration unit (5) joins and the outdoor unit (2)
Flows into. The refrigerant flowing into the outdoor unit (2) merges with the refrigerant flowing out of the outdoor heat exchanger (13), and is sucked into the compressor (11 or 12). This refrigerant is supplied to the compressor (11 or 12)
And the above-described circulation operation is repeated again.

Next, a heating operation without using the outdoor heat exchanger (13) will be described. Also in the heating operation, the four-way switching valve (15) communicates with the first port and the fourth port,
A state is set in which the port and the third port communicate with each other. However, in the main heating operation, the electronic expansion valve of the outdoor unit (2)
(27) is set to the fully closed state.

The refrigerant in the refrigerant circuit (6) circulates as shown in FIG. Specifically, the refrigerant discharged from the compressor (11 or 12) flows into the indoor unit (3), and is supplied to the indoor heat exchanger.
The air is condensed in (42) and the room air is heated. The refrigerant flowing out of the indoor heat exchanger (42) returns to the outdoor unit (2) and flows into the receiver (14). The refrigerant flowing out of the receiver (14) flows out of the outdoor unit (2), and is divided into a refrigeration unit (4) and a refrigeration unit (5). In the refrigerating unit (4) and the refrigerating unit (5), cooling and freezing are performed in the same manner as in the cooling operation described above. The refrigerant flowing out of the refrigeration unit (4) and the refrigeration unit (5) merges and flows into the outdoor unit (2). The refrigerant flowing into the outdoor unit (2)
It is sucked into the compressor (11 or 12). The sucked refrigerant is compressed by the compressor (11 or 12) and repeats the above-described circulation operation again.

-Control of Inverter Compressor- For the inverter compressor (11), the operating frequency is 30H.
Capacity control is performed between z (lowest frequency) and 200 Hz.

Specifically, when the operating frequency is not the above minimum frequency, the frequency is decreased when the operating state of the low pressure LP <2.5 kg / cm ² continues for a predetermined time (for example, 60 seconds); 5 kg / cm ² ≦ low pressure LP <3 kg / cm ²
In this case, the frequency is not changed. When the operation state of 3 kg / cm ² ≦ low pressure LP continues for a predetermined time (for example, 60 seconds), the frequency is increased.

In the above and below, each pressure indicates a gauge pressure. In the above and the above, the reason why the frequency is not changed unless the predetermined operation state continues for the predetermined time is to prevent hunting.

On the other hand, when the operation frequency is the lowest frequency, the operation of the inverter compressor (11) is stopped when the low pressure LP ≦ 0 kg / cm ² , and 0 kg / cm ² <low pressure LP <3 kg / cm ² In the case of, the operation at the lowest frequency is continued, and when the operation state of 3 kg / cm ² ≦ low pressure LP continues for a predetermined time (for example, 60 seconds), the frequency is increased.

-Capacity control- Next, referring to FIGS. 5 to 8, the inverter compressor (1
The capacity control of 1) will be described in detail. As shown in FIG. 5, first, in step ST1, the low pressure LP is set to 3 kg /
It is determined whether it is cm ² or more. If the result of the determination is YES, the operation proceeds to step ST2, where the first timer T1 is reset. The first timer T1 has a low pressure LP of 2.5.
This is a timer for measuring the duration of the operation state of less than kg / cm ² .

Next, in step ST3, it is determined whether or not the second timer T2 is measuring a predetermined duration. The second timer T2 is a timer for measuring the duration of the operation state where the low pressure LP is 3 kg / cm ² or more. If the determination result in step ST3 is NO, in step ST4, measurement of the second timer T2 is started. On the other hand, if the decision result in the step ST3 is YES, the process proceeds to a step ST5.

In step ST5, the second timer T
It is determined whether the measurement time of No. 2 has reached a predetermined time (60 seconds in this embodiment). If the result of the determination is YES, the process proceeds to step ST6 to perform frequency increase control. On the other hand, if the result of the determination is NO, the process from step ST1 is continued again without changing the operating frequency.

FIG. 6 is a flowchart showing details of the frequency increase control in step ST6. In the frequency increase control, in step ST31, it is determined whether or not the target frequency is equal to or higher than a predetermined maximum frequency fmax. Note that the target frequency can be calculated by a known method.
For example, the frequency increment Δf calculated based on the low pressure
Can be calculated by adding to the operating frequency f at that time. If the determination result in step ST31 is YES, the highest frequency fmax is set as the target frequency, and the operation is performed at the highest frequency fmax (step ST3).
2). On the other hand, if the result of the determination is NO, the operating frequency is increased by a predetermined frequency (step ST33).

As shown in FIG. 5, when the frequency increase control in step ST6 is completed, the process proceeds to step ST7, where the second
The timer T2 is reset.

[0053] In contrast, if the decision result in the step ST1 is NO, the process proceeds to step ST8, and determines whether the low pressure LP is 2.5 kg / cm ² or more and less than or 3 kg / cm ^2. If the determination result is YES, the low pressure LP
Is within the proper range, so that the operating frequency is not changed. On the other hand, if the result of the determination is NO, step ST9
Then, the second timer T2 is reset. Subsequently, in step ST10, it is determined whether the first timer T1 is measuring a predetermined duration. If the result of the determination is YES, the operation proceeds to step ST12. On the other hand, when the result of the determination is NO, the process proceeds to step ST11, where measurement of the first timer T1 is started.

In step ST12, it is determined whether or not the time measured by the first timer T1 has reached a predetermined time (60 seconds in this embodiment). If the judgment result is YES,
Proceeding to step ST13, frequency reduction control is performed. On the other hand, if the result of the determination is NO, the process from step ST1 is continued again without changing the frequency.

FIG. 7 is a flowchart showing the details of the frequency reduction control in step ST13. In the frequency reduction control, in step ST41, it is determined whether or not the target frequency is equal to or lower than a predetermined minimum frequency fmin. If the result of the determination is YES, the operation is performed with the lowest frequency fmin as the target frequency (step ST42). On the other hand, if the result of the determination is NO, the operating frequency is decreased by a predetermined frequency (step ST43).

As shown in FIG. 5, when the frequency reduction control in step ST13 ends, the process proceeds to step ST14,
The first timer T1 is reset.

-Start / Stop Control- As described above, if the low pressure falls below a predetermined pressure when the operating frequency is the lowest frequency, the inverter compressor (11) stops. Then, the activation control shown in FIG. 8 is executed.

Specifically, first, in step ST21, it is determined whether or not a predetermined time (for example, 3 to 5 minutes) has elapsed since the operation of the inverter compressor (11) was stopped. If the result of the determination is YES, the process proceeds to step ST22, where it is determined whether or not the low pressure LP is 2.5 kg / cm ² or more. On the other hand, if the decision result in the step ST21 is NO, the processes after the step ST21 are performed again.

If the decision result in the step ST22 is YES, the operation of the inverter compressor (11) is restarted with the lowest frequency as the operating frequency (step ST23). on the other hand,
If the decision result in the step ST22 is NO, the processes after the step ST21 are performed again.

-Effects of Embodiment- As described above, in the present refrigeration system (1), the inverter compressor
When the low pressure LP becomes equal to or less than the predetermined pressure when the operation frequency of (11) is the lowest frequency, the inverter compressor (11) is temporarily stopped. Therefore, the user side unit (3,
Even if the thermo-off signal is not transmitted from 4,5) to the outdoor unit (2), the wet operation can be avoided. Further, when a predetermined time has elapsed since the operation of the inverter compressor (11) was stopped and the low pressure LP becomes equal to or higher than a predetermined pressure,
The inverter compressor (11) was restarted. Therefore, the operation can be automatically restarted without transmitting a thermo-on signal from the use side units (3, 4, 5) to the outdoor unit (2). Therefore, it is possible to reduce the number of transmission paths for transmitting and receiving the thermo-off signal and the thermo-on signal, and to achieve transmission-less transmission between units.

With the reduction in transmission, the wiring configuration of the device is simplified. In addition, there is no need to select the use side units (3, 4, 5) according to the type of the outdoor unit (2), and the degree of freedom in unit combination is increased.

When the heat balance is maintained between the use side units during the heating operation, the indoor heat exchanger (42)
As a condenser, a refrigerator cooler (47) and a refrigerator cooler (5
Since 6) is used as an evaporator and the outdoor heat exchanger (13) is not used, heat is not released to the outside, and wasteful heat exchange can be eliminated. Therefore, energy saving can be achieved.

In the above embodiment, the refrigerant circuit (6) is configured to form a two-stage compression refrigeration cycle.
Of course, it may be configured to form an original refrigeration cycle.

The numerical values such as the pressure and the time specified in the above embodiment are examples, and the predetermined time and the predetermined pressure according to the present invention are not limited to those values.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus according to an embodiment.

FIG. 2 is a refrigerant circuit diagram for explaining a refrigerant circulation operation during a cooling operation.

FIG. 3 is a refrigerant circuit diagram for explaining a refrigerant circulation operation during a heating operation using an outdoor heat exchanger.

FIG. 4 is a refrigerant circuit diagram for explaining a refrigerant circulation operation during a heating operation without using an outdoor heat exchanger.

FIG. 5 is a flowchart of capacity control of the inverter compressor.

FIG. 6 is a flowchart of frequency increase control.

FIG. 7 is a flowchart of frequency reduction control.

FIG. 8 is a flowchart of start control.

[Explanation of symbols]

 (1) Refrigeration equipment (2) Outdoor unit (heat source side unit) (3) Indoor unit (indoor air conditioning unit) (4) Refrigeration unit (5) Refrigeration unit (6) Refrigerant circuit (11) Inverter compressor (12) Non Inverter compressor (13) Outdoor heat exchanger (heat source side heat exchanger) (42) Indoor heat exchanger (47) Refrigerator cooler (refrigerator heat exchanger) (56) Refrigerator cooler (refrigerator heat exchange) (83) Low pressure sensor (pressure detection means) (90) Controller (91) Capacity control unit (capacity control means) (92) Start / stop control unit (start / stop control means)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhide Nomura 1304 Kanaokacho, Sakai City, Osaka Daikin Industries, Ltd. Sakai Seisakusho Kanaoka Factory F-term (reference) 3L092 DA17 EA02 FA02

Claims (2)

[Claims] 1. A heat source side unit (2) having a compressor (11) whose capacity can be controlled between a predetermined minimum capacity and a maximum capacity and a heat source side heat exchanger (13); At least an indoor air conditioning unit (3) having an indoor heat exchanger (42) for cooling and a cooling unit (4, 5) having a cooling heat exchanger (47, 56) for cooling an object to be cooled are connected. A refrigeration apparatus provided with a refrigerant circuit (6) comprising: a pressure detecting means (8) for detecting a low pressure of the refrigerant circuit (6).
3), the compressor (11) based on the low pressure of the refrigerant circuit (6)
Capacity control means (91) for controlling the capacity of the compressor (11), when the compressor (11) is operating at the minimum capacity, when the low pressure of the refrigerant circuit (6) becomes equal to or less than a predetermined value, the compressor ( While the operation of the compressor (11) is stopped, when a predetermined time has elapsed since the operation of the compressor (11) was stopped and the low pressure of the refrigerant circuit (6) became a predetermined value or more, the compressor (11) And a start / stop control means (92) for restarting the operation of the refrigeration apparatus. 2. The refrigeration apparatus according to claim 1, wherein the cooling unit includes a refrigeration unit (4) having a refrigeration heat exchanger (47) and an object to be cooled. And a refrigerating unit (5) having a refrigerating heat exchanger (56) for cooling at a temperature lower than (3).