JP2008190767A - Refrigeration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the accumulation of refrigerants when the outside air temperature is low. <P>SOLUTION: This refrigeration system is provided with a refrigerant circuit (10) to which two outdoor units (3a, 3b) each having a compressor (11) are connected in parallel. When the outside air temperature is lowered to 10°C or below during cooling operation of the refrigerant circuit (10), the compressor (11) of the stopped outdoor unit (3b) is forcibly driven, thereby preventing the accumulation of liquid refrigerants in the compressor (11) of the outdoor unit (3b). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a refrigeration apparatus, and more particularly to measures for preventing refrigerant accumulation at low outside air temperatures.

Conventionally, as disclosed in Patent Document 1, there is an air conditioner including a plurality of indoor heat exchangers and a plurality of outdoor heat exchangers. This air conditioner controls the operating capacity of the compressor of the outdoor unit corresponding to the air conditioning load in the room, and also controls the number of operating outdoor units.
Japanese Patent Laid-Open No. 8-200902

    However, in the conventional air conditioner, since the number of outdoor units operated is controlled, an outdoor unit that stops when the outside air temperature is low occurs during cooling operation in winter or the like.

    For this reason, liquid refrigerant accumulates in the outdoor unit that has been stopped for a long time, and so-called stagnation occurs. As a result, there are problems that a refrigerant shortage in the refrigerant circuit, a liquid back at the time of starting the compressor, and the like occur.

    The present invention has been made in view of such a point, and an object thereof is to prevent refrigerant from being accumulated at a low outside air temperature.

    The present invention drives the compressor (11) of the stopped outdoor units (3a, 3b) when the outside air temperature falls below a predetermined temperature during operation of the refrigerant circuit (10).

    The first invention presupposes a refrigeration apparatus including a refrigerant circuit (10) in which a plurality of outdoor units (3a, 3b) each having a compressor (11) are connected in parallel.

    Compressor control means (41) for driving the compressor (11) of the outdoor unit (3a, 3b) that is stopped when the outside air temperature falls below a predetermined temperature during the cooling operation of the refrigerant circuit (10). Yes.

    In the first aspect of the invention, when the outside air temperature becomes a predetermined temperature or less during normal cooling operation, the compressor (11) of the outdoor unit (3a, 3b) in the stopped state is driven.

    In other words, if the outdoor unit (3a) is stopped for a long time, liquid refrigerant may accumulate, so the compressor (11) of the outdoor unit (3a) is driven and liquid refrigerant accumulates in the compressor (11). In advance.

    According to a second aspect, in the first aspect, the outdoor unit (3a, 3b) that drives the compressor (11) is stopped when the outside air temperature becomes higher than a predetermined temperature.

    In the second aspect of the invention, when the outside air temperature becomes higher than the predetermined temperature, it is determined that the liquid refrigerant does not accumulate, and the driven outdoor units (3a, 3b) are stopped.

    According to a third aspect of the present invention, in the first aspect of the present invention, the capacity of the compressor (11) that is driven is increased as the outside air temperature becomes lower than a predetermined temperature.

In the third invention, for example, when the outdoor unit (3a) in a stopped state is driven,
The operating capacity of the compressor (11) of the outdoor unit (3a) is increased as the outside air temperature becomes lower, thereby reliably preventing liquid refrigerant from accumulating.

    According to a fourth aspect of the present invention, in the first aspect, the outdoor unit (3a, 3b) is stopped when the outdoor air temperature drops below a predetermined temperature in a state where the outdoor unit (3a, 3b) has been stopped for a predetermined time or longer. , 3b) to drive the compressor (11).

    In the fourth aspect of the present invention, when the outdoor unit (3a) has been stopped for a predetermined time or longer and the outside air temperature is lower than the predetermined temperature, the liquid refrigerant is very likely to accumulate. The compressor (11) is driven.

    According to the present invention, the compressor (11) of the outdoor unit (3a, 3b) in the stopped state is driven when the outside air temperature falls below a predetermined temperature during the cooling operation of the refrigerant circuit (10). It is possible to prevent liquid refrigerant from accumulating in the machine (11). As a result, shortage of refrigerant, so-called compressor liquid back, and the like can be reliably prevented, so that the reliability of the compressor (11) can be improved.

    According to the second aspect of the invention, the outdoor unit (3a, 3b) that drives the compressor (11) is stopped when the outdoor temperature becomes higher than the predetermined temperature. Is higher, the driven compressor (11) can be stopped. As a result, since the drive of the compressor (11) can be minimized, the operating capacity can be made to correspond to the load.

    According to the third aspect of the invention, since the capacity of the compressor (11) that is driven as the outside air temperature is lower than the predetermined temperature and becomes lower, the capacity of the compressor (11) is increased. Can be prevented.

    Further, according to the fourth aspect of the invention, when the outdoor unit (3a, 3b) has been stopped for a predetermined time or more and the outdoor temperature falls below a predetermined temperature, the stopped outdoor unit (3a, 3b) ) Of the compressor (11) of the outdoor unit (3a, 3b) based on the relationship between the stop time of the outdoor unit (3a, 3b) and the outside air temperature. ) Can be driven. As a result, it is possible to reliably prevent liquid refrigerant from accumulating in the compressor (11).

    Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 is a circuit configuration diagram showing a refrigerant circuit (10) of an air conditioner (1) according to Embodiment 1 of the present invention. This air conditioner (1) is a so-called outdoor multi-type air conditioner (1) in which two outdoor units (3a, 3b) are connected in parallel to one indoor unit (2). The indoor unit (2) and each outdoor unit (3a, 3b) are connected by a gas side communication pipe (4) and a liquid side communication pipe (5). The gas side communication pipe (4) is branched into the gas side first branch pipe (4a) and the gas side second branch pipe (4b) on the outdoor unit (3a, 3b) side, and the liquid side communication pipe (5) On the outdoor unit (3a, 3b) side, the liquid side first branch pipe (5a) and the liquid side second branch pipe (5b) are branched.

    Each outdoor unit (3a, 3b) is installed outside the air-conditioning target room (6). Each outdoor unit (3a, 3b) is composed of a compressor (11), a four-way selector valve (12), an outdoor heat exchanger (13), and an electronic expansion valve that are configured to have a variable operating capacity by frequency control of the inverter. An outdoor expansion valve (14) configured and an accumulator (15) are provided. Although an outdoor fan is provided in the vicinity of the outdoor heat exchanger (13), illustration is omitted.

    In each outdoor unit (3a, 3b), the compressor (11) is connected to the first port (P1) of the four-way selector valve (12) via the discharge pipe (21). The second port (P2) of the four-way selector valve (12) is connected to the gas side end of the outdoor heat exchanger (13). The compressor (11) is connected to the third port (P3) of the four-way selector valve (12) via a suction pipe (22) provided with an accumulator (15) on the way. The fourth port (P4) of the four-way selector valve (12) is connected to the branch pipe of the gas side communication pipe (4) via the outdoor gas pipe (23).

    The four-way switching valve (12) has a first position (solid line in the figure) where the first port (P1) and the second port (P2) communicate and the third port (P3) and the fourth port (P4) communicate. Can be switched between the first port (P1) and the fourth port (P4) and the second position (see the broken line in the figure) where the second port (P2) and the third port (P3) communicate. It is configured. The four-way selector valve (12) is set to the first position during the cooling operation and is set to the second position during the heating operation.

    The liquid side end of the outdoor heat exchanger (13) is connected to a branch pipe of the liquid side communication pipe via an outdoor liquid pipe (24) provided with an outdoor expansion valve (14) on the way.

    The indoor unit (2) is installed in the air-conditioning target room (6), and includes an indoor heat exchanger (16) and an indoor expansion valve (17) (expansion mechanism). The indoor expansion valve (17) is an electronic expansion valve. The liquid side communication pipe is connected to the liquid side end of the indoor heat exchanger (16) via an indoor liquid pipe (25) having an indoor expansion valve (17) on the way. The gas side end of the indoor heat exchanger (16) is connected to the gas side communication pipe (4) via the indoor gas pipe (26). An indoor fan (18) is installed in the vicinity of the indoor heat exchanger (16).

    The outdoor unit (3a, 3b) has a high pressure that stops the operation of the compressor (11) when the discharge pressure of the outside temperature sensor (36) and the compressor (11) that measures the outside temperature rises above a predetermined value. A switch (38) and the like are provided. In addition, illustration is abbreviate | omitted about other sensors.

    This air conditioner (1) includes a controller (40) as control means. The controller (40) is connected to the outside air temperature sensor (36) and the detected value is input (in the figure, the connection state between the controller (40) and the outside air temperature sensor (36) is omitted). is doing). The controller (40) is provided with a compressor control unit (41) for collecting the accumulated refrigerant.

    The compressor control unit (41) is a feature of the present invention, and detects that the outside air temperature is equal to or lower than a predetermined temperature during the cooling operation of the refrigerant circuit (10). The compressor (11) of 3a, 3b) is forcibly driven.

    Further, when the compressor control unit (41) detects that the outside air temperature is equal to or higher than a predetermined temperature, the compressor control unit (41) performs control to stop the compressor (11) that is forcibly driven.

    When the outdoor unit (3b) that has been stopped is operated, the operating capacity increases and the cooling operation itself is stopped (so-called thermo-off state). In this case, since the pump-down operation is performed and the cooling operation is stopped, the liquid refrigerant does not accumulate in the compressor (11).

-Driving action-
Next, the operation of the above-described air conditioner (1) will be described.

    During the cooling operation, when the compressor (11) is driven, the refrigerant discharged from the compressor (11) is condensed in each outdoor heat exchanger (13), then depressurized by the indoor expansion valve (17), and then Then, it evaporates in the indoor heat exchanger (16) and returns to the compressor (11). This operation is repeated to cool the indoor air in the indoor heat exchanger (16).

    On the other hand, when detecting that the outside air temperature is 10 ° C. or lower during the cooling operation, the compressor control unit (41) forcibly drives the compressor (11) of the stopped outdoor units (3a, 3b).

    Specifically, the compressor control of the outdoor unit (3b) will be described. When the compressor control unit (41) detects that the outside air temperature is 10 ° C. or less during the cooling operation of the refrigerant circuit (10), FIG. The state of 2 shifts to the state of FIG. 3, and the compressor (11) of the outdoor unit (3b) in the stopped state is forcibly driven to circulate the refrigerant. That is, when the outside air temperature is reached, the refrigerant condenses in the compressor (11), the liquid refrigerant accumulates, and so-called stagnation occurs.

    Therefore, the compressor (11) of the stopped outdoor unit (3b) is driven to circulate the refrigerant.

    On the other hand, when detecting that the outside air temperature is higher than 10 ° C., the compressor control unit (41) stops the forcedly driven outdoor unit (3b).

    In addition, the compressor control unit (41) causes the compressor (11) in the stopped state to stop when the outdoor air temperature decreases to 10 ° C. or lower while the outdoor unit (3a, 3b) has been stopped for a predetermined time or longer. You may make it perform the compressor control which prevents that a liquid refrigerant accumulates.

-Effect of Embodiment 1-
As described above, according to the present embodiment, when it is detected that the outside air temperature is 10 ° C. or less during the cooling operation of the refrigerant circuit (10), the compressor (3a, 3b) of the stopped outdoor unit (3a, 3b) Since 11) is forcibly driven, it is possible to prevent liquid refrigerant from accumulating in the compressor (11). As a result, shortage of refrigerant, so-called compressor liquid back, and the like can be reliably prevented, so that the reliability of the compressor (11) can be improved.

    The compressor control unit (41) stops the compressor (11) of the outdoor units (3a, 3b) that are forcibly driven when the outside air temperature becomes 10 ° C. or higher. ) Prevents the refrigerant from collecting.

    In addition, the compressor control unit (41) is configured to stop the outdoor unit (3a, 3b) when the outdoor unit (3a, 3b) has been stopped for a predetermined time or more and the outside air temperature has decreased to 10 ° C. or lower. If the compressor (11) of 3b) is forcibly driven, it is possible to prevent liquid refrigerant from accumulating in the compressor (11).

<Embodiment 2 of the invention>
Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

    In the present embodiment, when the outside air temperature drops below a predetermined temperature in the first embodiment, the stopped compressor (11) is forcibly driven, and the refrigerant accumulated in the compressor (11) is supplied to the refrigerant circuit ( Instead of returning to 10), the capacity of the compressor (11) forcibly driven is increased as the outside air temperature becomes lower than a predetermined temperature and becomes lower.

    Specifically, as shown in FIG. 4, when the outside air temperature is higher than 10 ° C., the compressor (11) of the stopped outdoor unit (3b) is not driven.

    On the other hand, when the outside air temperature is 0 ° C. or higher and 10 ° C. or lower, the compressor (11) of the outdoor unit (3b) in the stopped state is forcibly driven to operate at the minimum capacity.

    On the other hand, when the outside air temperature is lower than 0 ° C., the compressor (11) of the outdoor unit (3b) driven from the stopped state is increased to an intermediate capacity.

    That is, in the present embodiment, as shown in FIG. 4, the capacity of the compressor (11) that is forcibly driven increases as the operating temperature increases due to a decrease in the outside air temperature.

-Effect of Embodiment 2-
As described above, according to the present embodiment, as the outside air temperature is lowered, the compressor (11) that has been forcibly driven is controlled to be driven by increasing its capacity, so even when the outside air temperature is lower than 0 ° C. Thus, the liquid refrigerant can be reliably prevented from accumulating. As a result, the refrigerant shortage can be prevented more reliably. Other effects are the same as those of the first embodiment.

<Other embodiments>
The present invention may be configured as follows with respect to the first embodiment.

    Although each embodiment described the air conditioner (1), the present invention can be applied to various refrigeration apparatuses in addition to the air conditioner (1).

    In addition, the refrigeration apparatus of the present invention is suitable for use in an environment where annual cooling is performed.

    In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

    As described above, the present invention is useful for a refrigeration apparatus including a plurality of outdoor units.

It is a circuit block diagram which shows the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows the state which one outdoor unit has stopped. It is a schematic block diagram which shows the state which forcedly driven the outdoor unit which has stopped. It is a figure which shows the relationship between the external temperature which concerns on Embodiment 2 of this invention, and a compressor capacity | capacitance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Indoor unit 3a Outdoor unit 3b Outdoor unit 10 Refrigerant circuit 11 Compressor 12 Four-way switching valve 13 Outdoor heat exchanger 14 Outdoor expansion valve 16 Indoor heat exchanger 17 Indoor expansion valve 36 Outdoor temperature sensor 38 High pressure switching Valve 40 Controller 41 Compressor controller

Claims (4)

A refrigerating apparatus including a refrigerant circuit (10) in which a plurality of outdoor units (3a, 3b) each including a compressor (11) are connected in parallel with each other,
Compressor control means (41) for driving the compressor (11) of the stopped outdoor unit (3a, 3b) when the outside air temperature falls below a predetermined temperature during the cooling operation of the refrigerant circuit (10). A refrigeration apparatus characterized by comprising: In claim 1,
The compressor control means (41) is configured to stop the outdoor units (3a, 3b) that have driven the compressor (11) when the outside air temperature becomes higher than a predetermined temperature. apparatus. In claim 1,
The refrigeration apparatus, wherein the compressor control means (41) is configured to increase the capacity of the compressor (11) that is driven as the outside air temperature becomes lower than a predetermined temperature and becomes lower. In claim 1,
The compressor control means (41) is configured to stop the outdoor unit (3a, 3b) when the outdoor unit temperature (3a, 3b) has been stopped for a predetermined time or more and the outside air temperature falls below a predetermined temperature. A refrigeration apparatus configured to drive the compressor (11).

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