JP6350577B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner that performs air conditioning using cold or warm heat of a liquid heat source medium.

  Conventionally, in an air conditioner equipped with a refrigerant circuit that performs a vapor compression refrigeration cycle, the refrigerant circuit is generally configured by sequentially connecting a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger. . Here, as an outdoor heat exchanger, a water heat source type air conditioner using a heat exchanger in which heat is exchanged between refrigerant and heat source water (liquid heat source medium), for example, plate heat exchange is used as the outdoor heat exchanger. A device is used (see, for example, Patent Document 1). The heat source water is supplied to the outdoor heat exchanger from the chilled water tower equipment and boiler equipment installed outside the air conditioner through the water pipe, and returns to the chilled water tower equipment and boiler equipment after exchanging heat with the refrigerant. ing.

  By the way, when the outdoor heat exchanger is a plate heat exchanger that exchanges heat between the refrigerant and the heat source water, compared to the case where an air heat exchanger that exchanges heat between the refrigerant and air is used as the outdoor heat exchanger, The internal volume of the outdoor heat exchanger is extremely small relative to the internal volume of the indoor heat exchanger. Therefore, a large amount of excess refrigerant is generated during the cooling operation. The surplus refrigerant is likely to be generated particularly when the amount of the refrigerant charged is large, and when the surplus refrigerant is excessive, the high-pressure pressure is excessively increased and the operation of the refrigeration cycle is not performed normally.

  On the other hand, in a water heat source type air conditioner, it has been common to provide a container for storing excess refrigerant on the high pressure side of the refrigerant circuit to take measures against excess refrigerant during cooling operation.

JP 2006-046779 A

  However, in the configuration in which the container is arranged on the high-pressure side of the refrigerant circuit as a countermeasure against surplus refrigerant, a receiver with a high-pressure design is required, and there is a problem that the cost of parts increases.

  In addition, in order to store the refrigerant in the receiver, which is a high-pressure vessel, it is necessary to connect a gas vent valve for extracting gas from the receiver to the receiver, which complicates the refrigerant circuit and increases the cost.

  In addition to the case where the outdoor heat exchanger (12) is a plate heat exchanger that exchanges heat between the refrigerant and the heat source water, the problem is that the refrigerant and the liquid heat source medium such as a double-tube heat exchanger are heated. This is a problem that may occur when the heat exchanger is to be replaced.

  The present invention has been made in view of such problems, and an object of the present invention is to use an air conditioner that uses a heat exchanger that exchanges heat between a refrigerant and a liquid heat source medium as an outdoor heat exchanger (12). In the apparatus, it is possible to take measures against excess refrigerant during cooling operation while suppressing an increase in component costs and a complicated circuit configuration.

The first invention includes a refrigerant circuit (10) that includes a compressor (11), an outdoor heat exchanger (12), an expansion mechanism (13, 14), and an indoor heat exchanger (15), and circulates the refrigerant. The refrigerant circuit (10) has a switching mechanism (16) for reversibly switching the refrigerant circulation direction, and the outdoor heat exchanger (12) is a heat exchanger for exchanging heat between the refrigerant and the liquid heat source medium. der is, the internal volume of the outdoor heat exchanger (12) assumes a small air conditioner than the internal volume of the indoor heat exchanger (15).

The air conditioner includes a refrigerant / refrigerant heat exchanger (17) having a high pressure channel (17a) and a low pressure channel (17b), and an accumulator (19) provided on the suction side of the compressor (11). ), And the high-pressure flow path (17a) of the refrigerant / refrigerant heat exchanger (17) is connected to the liquid pipe (10b) of the refrigerant circuit (10) and branched from the liquid pipe (10b). The passage (20) is connected to the accumulator (19) via the pressure adjustment mechanism (18) and the low pressure flow path (17b) of the refrigerant / refrigerant heat exchanger (17), and the high pressure is targeted only during cooling operation. It is characterized by having a control part (5) for adjusting the pressure adjustment mechanism (18) so as not to rise above the value and performing surplus refrigerant storage control for returning the refrigerant to the accumulator (19).

  In the first aspect of the invention, when the high pressure reaches the target value during the cooling operation, the control section (5) performs surplus refrigerant storage control. In surplus refrigerant storage control, the pressure adjustment mechanism (18) is adjusted so that the high pressure does not rise above the target value, and the refrigerant is returned to the accumulator (19). At the time of this surplus refrigerant storage control, surplus refrigerant is returned to the accumulator, so that it is possible to prevent the high-pressure pressure from rising excessively even if the refrigerant charge amount is relatively large, and the refrigeration cycle operates normally. It can suppress that it is not performed.

  In a second aspect based on the first aspect, the control unit (5) is configured so that the supercooling degree of the liquid refrigerant is maintained constant until the high pressure reaches a target value during the cooling operation. While the supercooling control for adjusting (18) is performed, when the high pressure reaches a target value, the control is switched to the surplus refrigerant storage control so that the high pressure does not increase further.

  In the second aspect of the invention, during the cooling operation, the control unit (5) determines whether or not the high pressure has reached the target value, and the pressure adjustment mechanism (18) is turned on until the high pressure reaches the target value. By adjusting, the supercooling control is performed to keep the supercooling degree of the liquid refrigerant constant. At this time, the refrigerant / refrigerant heat exchanger (17) functions as a supercooling heat exchanger. On the other hand, when the high pressure reaches the target value, the control unit (5) switches to excess refrigerant storage control, so the high pressure does not increase any further.

  According to a third invention, in the first or second invention, the control unit (5) adjusts the pressure adjusting mechanism (18) so that the degree of supercooling of the liquid refrigerant is always kept constant during heating operation. It is characterized by performing supercooling control.

  In the third aspect of the invention, during the heating operation, supercooling control is performed in which the supercooling degree of the liquid refrigerant is always kept constant by adjusting the pressure adjusting mechanism (18) with the control unit (5). That is, during the heating operation, the refrigerant / refrigerant heat exchanger (17) always functions as a supercooling heat exchanger.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a surplus refrigerant | coolant increases at the time of air_conditionaing | cooling operation, and a high pressure rises too much, and it can suppress that a refrigerating cycle does not perform normal operation | movement. Further, in the present invention, an accumulator (19) generally provided in the refrigerant circuit (10) can be used, unlike the refrigerant stored in the receiver which is a high-pressure vessel. Accordingly, an increase in cost due to the provision of the receiver can be suppressed, and a gas vent valve that needs to be provided in accordance with the receiver need not be provided, which also makes it possible to suppress an increase in cost.

  According to the second aspect of the invention, in addition to obtaining the same effect as the first aspect of the invention, high-efficiency operation is achieved by performing supercooling control until the high pressure reaches the target value during cooling operation. It becomes possible to do.

  According to the third aspect of the present invention, since the high pressure does not increase excessively during heating operation, it is possible to perform highly efficient operation by always performing supercooling control.

FIG. 1 is a refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a refrigerant flow during cooling operation in the refrigerant circuit of FIG. 1. FIG. 3 is a diagram illustrating a refrigerant flow during heating operation in the refrigerant circuit of FIG. 1. FIG. 4 is a graph showing the relationship between the refrigerant charge amount and the high pressure during the cooling operation of the air conditioner of FIG. FIG. 5 is a graph showing the relationship between the refrigerant charge amount and the opening of the expansion valve during the cooling operation of the air conditioner of FIG. FIG. 6 is a graph showing the relationship between the refrigerant charge amount and the COP ratio during the cooling operation of the air-conditioning apparatus of FIG.

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

  This embodiment is provided with one outdoor unit (2) and a plurality of indoor units (3), and the air conditioner (1) is configured such that the indoor unit (3) is connected in parallel to the outdoor unit (2). It is about. This air conditioner (1) is configured to air-condition the room using the cold and hot heat of heat source water that is a liquid heat medium.

  The air conditioner (1) has a refrigerant circuit (10) through which refrigerant circulates. The refrigerant circuit (10) is a circuit that can reversibly switch the circulation direction of the refrigerant so that the cooling operation and the heating operation are switched. The refrigerant circuit (10) includes a compressor (11), an outdoor heat exchanger (11), an expansion valve as an expansion mechanism (outdoor expansion valve (13) and indoor expansion valve (14)), and an indoor heat exchanger (15). And. The air conditioner (1) further includes a four-way switching valve (16), which is a switching mechanism for switching the refrigerant circulation direction, and a refrigerant / high-pressure channel (17a) and a low-pressure channel (17b). It has a refrigerant heat exchanger (17), a pressure adjustment valve (18) which is a pressure adjustment mechanism, and an accumulator (19). The expansion valve (13, 14) includes an outdoor expansion valve (13) and an indoor expansion valve (14).

  The outdoor unit (2) includes the compressor (11), the four-way switching valve (16), the outdoor heat exchanger (11), the outdoor expansion valve (13), the refrigerant / refrigerant heat exchanger (17), and the accumulator ( 19). Each indoor unit (3) is provided with the indoor expansion valve (14) and the indoor heat exchanger (15).

  The outdoor heat exchanger (11) is a heat exchanger that exchanges heat between the refrigerant and the heat source water (liquid heat source medium). Specifically, the outdoor heat exchanger (11) is configured by a plate heat exchanger having a refrigerant channel (12a) and a heat source water channel (12b). The refrigerant flow path (12a) is connected to the refrigerant pipe (gas pipe (10a) and liquid pipe (10b)) of the refrigerant circuit (10), and the heat source water flow path (12b) is a heat source connected to the chilled water tower equipment and boiler equipment. It is connected to the water pipe (31) of the water circuit (30).

  The indoor heat exchanger (15) is a cross fin heat exchanger. Although not shown, the indoor heat exchanger (15) is connected to the indoor unit (3) so that indoor air flows through the indoor heat exchanger (15) to exchange heat with the refrigerant in the refrigerant circuit (10). An indoor fan is provided in the vicinity.

  The discharge side of the compressor (11) is connected to the first port (16a) of the four-way selector valve (16), and the second port (16b) of the four-way selector valve (16) is the outdoor heat exchanger (11). Connected to the gas side end. The third port (16c) of the four-way selector valve (16) is connected to the suction side of the compressor (11) via the accumulator (19), and the fourth port (16d) of the four-way selector valve (16) is It is connected to the gas side end of the indoor heat exchanger (15).

  In addition, the liquid side end of the outdoor heat exchanger (11) and the liquid side end of the indoor heat exchanger (15) are connected by a liquid pipe (10b). The liquid pipe (10b) has an outdoor unit (2 ) Is connected to the outdoor expansion valve (13), and the indoor unit (3) is connected to the indoor expansion valve (14).

  The four-way selector valve (16) has a first position during cooling operation in which the first port (16a) and the second port (16b) communicate with each other and the third port (16c) and the fourth port (16d) communicate with each other. (Refer to FIG. 2) and the second position during heating operation in which the first port (16a) and the fourth port (16d) communicate with each other and the second port (16b) and the third port (16c) communicate with each other (FIG. 3). It is configured to be able to switch to

  The refrigerant / refrigerant heat exchanger (17) has a high-pressure channel (17a) and a low-pressure channel (17b). The high-pressure channel (17a) of the refrigerant / refrigerant heat exchanger (17) is connected to the liquid pipe (10b). The pressure regulating valve (18) is provided in the return refrigerant passage (20) branched from the liquid pipe (10b). The return refrigerant passage (20) is connected to the inflow side of the accumulator (19) via the low pressure flow path (17b) of the refrigerant / refrigerant heat exchanger (17).

  An oil separator (21) is provided on the discharge side of the compressor (11). The oil separator (21) is connected to the suction side of the compressor (11) via an oil return pipe (24) provided with a solenoid valve as an oil return on-off valve (22) and a capillary tube (23). ing. The discharge pipe of the compressor (11) is provided with a discharge temperature sensor (T1) and a high pressure switch (SW), and there is a check between the oil separator (21) and the four-way selector valve (16). A valve (CV) and a high pressure sensor (P1) are provided. The discharge temperature sensor (T1) detects the refrigerant temperature discharged from the compressor (11), and the high pressure switch (SW) stops the compressor (11) when the high pressure rises too much, and the high pressure sensor (P1) Detects the high pressure of the refrigerant.

  The liquid pipe (10b) is provided with an outdoor heat exchanger temperature sensor (T2) in the vicinity of the outdoor heat exchanger (11), and a refrigerant heat exchanger temperature in the vicinity of the refrigerant / refrigerant heat exchanger (17). A sensor (T3) is provided. A return refrigerant temperature sensor (T4) is provided in the return refrigerant passage (20) connected to the refrigerant / refrigerant heat exchanger (17), and a low pressure refrigerant temperature sensor (T5) is provided at the inlet side of the accumulator (19). And a low pressure sensor (P2).

  The air conditioner (1) of the present embodiment is provided with a controller (5) that is a control unit. The controller (5) is configured to control by switching between cooling operation and heating operation.

  In addition, the controller (5) opens the pressure regulating valve (18) so that the high pressure does not rise above a predetermined target value during cooling operation, and adjusts the refrigerant to return to the accumulator (19). It is comprised so that storage control may be performed. The reason why the excess refrigerant storage control is performed in the present embodiment is as follows. In other words, the fact that the internal volume of the outdoor heat exchanger (11), which is a plate heat exchanger, is smaller than the internal volume of the indoor heat exchanger (15) is that the condenser (outdoor heat exchanger (11) during cooling operation) ) Is smaller than the volume of the indoor heat exchanger (15), which is an evaporator, and then the amount of liquid refrigerant is larger than the amount processed by the evaporator, which becomes surplus refrigerant It is. In other words, in normal operation with the above configuration, the refrigerant circuit (10) increases in pressure due to excess refrigerant, particularly when the refrigerant charge increases, and the operation of the refrigeration cycle is normal. This is because it is not performed and problems such as the compressor (11) stopping occur.

  Further, as described above, the controller (5) performs the surplus refrigerant control when the high pressure is excessively increased during the cooling operation as described above, but during the normal operation until the high pressure reaches the target value, the controller (5) It is configured to perform supercooling control for maintaining the degree of supercooling of the liquid refrigerant constant by adjusting 18) to a predetermined opening. That is, at this time, the refrigerant / refrigerant heat exchanger (17) functions as a supercooling heat exchanger.

  Furthermore, the controller (5) is configured to perform supercooling control that constantly maintains the degree of supercooling of the liquid refrigerant by adjusting the pressure regulating valve (18) to a predetermined opening degree during heating operation. ing. That is, in the present embodiment, surplus refrigerant is not generated during the heating operation, so the refrigerant / refrigerant heat exchanger (17) always functions as a supercooling heat exchanger, and surplus refrigerant storage control is not performed.

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

<Cooling operation>
In the cooling operation of FIG. 2, when the compressor (11) is started, the refrigerant discharged from the compressor (11) passes through the oil separator (21) and then flows into the outdoor heat exchanger (11). The refrigerant from which oil has been almost removed by the oil separator (21) dissipates heat to the heat source water (cold water) of the heat source water circuit (30) in the outdoor heat exchanger (11) and condenses to the outdoor heat exchanger (11). Spill from. The oil separated from the refrigerant in the oil separator (21) passes through the oil return pipe (24) by opening the oil return on-off valve (22), and then passes through the accumulator (19). It merges with the refrigerant and returns to the compressor (11).

  During this cooling operation, the outdoor expansion valve (13) is controlled to be fully open, and the liquid refrigerant flowing out of the outdoor heat exchanger (11) passes through the outdoor expansion valve (13). When the liquid refrigerant flows through the liquid pipe (10b), a part of the liquid refrigerant returns from the liquid pipe (10b) to the refrigerant passage (20). The refrigerant divided here is depressurized by the pressure regulating valve (18) to become a low-pressure refrigerant. In the refrigerant / refrigerant heat exchanger (17), the high-pressure refrigerant flowing through the high-pressure channel (17a) and the low-pressure refrigerant flowing through the low-pressure channel (17b) exchange heat, and the low-pressure refrigerant flows into the accumulator (19) ( Supercooling control).

  The high-pressure refrigerant in the high-pressure channel (17a) that exchanges heat with the low-pressure refrigerant flows into each indoor unit (3). In each indoor unit (3), after the refrigerant is depressurized by the indoor expansion valve (14), the refrigerant absorbs heat from the indoor air and evaporates when passing through the indoor heat exchanger (15). This cools the room air.

  The refrigerant evaporated in the indoor heat exchanger (15) flows into the outdoor unit (2), passes through the four-way selector valve (16), and joins the low-pressure refrigerant returned from the refrigerant / refrigerant heat exchanger (17). It flows into the accumulator (19). In the accumulator (19), the liquid refrigerant and the gas refrigerant are separated, and the gas refrigerant is sucked into the compressor (11).

  In the air conditioner (1) of the present embodiment, the cooling operation is performed by circulating the refrigerant through the refrigerant circuit (10) as described above.

<Heating operation>
In the heating operation of FIG. 3, when the compressor (11) is started, the refrigerant discharged from the compressor (11) flows into the indoor units (3) after passing through the oil separator (21). The operation of returning the oil from the oil separator (21) is performed in the same manner as in the cooling operation. In each indoor unit (3), the refrigerant radiates heat to the indoor air in the indoor heat exchanger (15), condenses, and flows out from the indoor heat exchanger (15). This heats the room air.

  During this heating operation, the indoor expansion valve (14) is controlled to be fully open, and the liquid refrigerant flowing out of the indoor heat exchanger (15) passes through the indoor expansion valve (14). The liquid refrigerant flows through the liquid pipe (10b) and flows into the outdoor unit (2), and part of the liquid refrigerant returns from the liquid pipe (10b) to the refrigerant passage (20). The divided refrigerant is depressurized by the pressure regulating valve (18) to become a low-pressure refrigerant. In the refrigerant / refrigerant heat exchanger (17), the high-pressure refrigerant flowing through the high-pressure channel (17a) and the low-pressure refrigerant flowing through the low-pressure channel (17b) exchange heat, and the low-pressure refrigerant flows into the accumulator (19) ( Supercooling control).

  The high-pressure refrigerant in the high-pressure flow path (17a) that exchanges heat with the low-pressure refrigerant is depressurized by the outdoor expansion valve (13) and then passes through the outdoor heat exchanger (11), and the heat source water of the heat source water circuit (30) It absorbs heat from (warm water) and evaporates. The refrigerant evaporated in the outdoor heat exchanger (11) passes through the four-way switching valve (16), merges with the low-pressure refrigerant returned from the refrigerant / refrigerant heat exchanger (17), and flows into the accumulator (19). In the accumulator (19), the liquid refrigerant and the gas refrigerant are separated, and the gas refrigerant is sucked into the compressor (11).

  In the air conditioner (1) of the present embodiment, the heating operation is performed by circulating the refrigerant through the refrigerant circuit (10) as described above.

<Supercooling control and surplus refrigerant storage control>
During the cooling operation, the controller (5) determines whether or not the high pressure of the refrigerant detected by the refrigerant circuit (10) has reached a target value (for example, every 30 seconds). Then, until the high pressure reaches the target value, the controller (5) adjusts the pressure regulating valve (18) to a predetermined degree of opening so that the degree of supercooling of the liquid refrigerant is kept constant. Done. In this supercooling control, the high-pressure refrigerant flowing through the high-pressure channel (17a) is supercooled by the low-pressure refrigerant, so that the refrigerant supplied to each indoor expansion valve (14) becomes only liquid, and the low-pressure channel (17b) The low-pressure refrigerant flowing through is returned to the accumulator (19).

  On the other hand, when the high pressure reaches the target value, the controller (5) switches the operation from the supercooling control to the surplus refrigerant storage control. In surplus refrigerant storage control, the opening degree of the pressure regulating valve (18) is adjusted by the controller (5) so that the high pressure does not rise above the target value, and surplus refrigerant is returned to the accumulator (19). At the time of this excessive refrigerant storage control, the high pressure pressure is excessively increased to prevent the refrigeration cycle from operating normally, and control with an emphasis on the degree of refrigerant supercooling is not performed. The liquid refrigerant flowing through (17a) is actually supercooled by the low-pressure refrigerant. However, the surplus refrigerant storage control is more common for the pressure regulation valve (18) than the supercooling control for controlling the opening of the pressure regulation valve (18) so that the degree of refrigerant supercooling is constant at the target value. I feel like opening up. Further, during the surplus refrigerant storage control, whether or not the high pressure of the refrigerant detected by the refrigerant circuit (10) has reached the target value is determined every 30 seconds, for example.

  On the other hand, during heating operation, by adjusting the pressure regulating valve (18) with the controller (5), supercooling control is always performed to maintain the subcooling degree of the liquid refrigerant at a predetermined value, and refrigerant / refrigerant heat exchange is performed. The oven (17) always functions as a supercooling heat exchanger.

  Here, as a comparative example, an example in which surplus refrigerant storage control is not applied during cooling operation is given, and this comparative example is compared with this embodiment using FIGS. 4 to 6.

  As shown in FIG. 4, in the comparative example, if the charging amount of the refrigerant increases from Q1 to Q2, Q3, Q4 during the cooling operation, the high pressure increases excessively as shown by the broken line in the figure, The compressor (11) may stop or become low capacity during cycle operation. On the other hand, in the present embodiment, by adjusting the opening of the pressure regulating valve (18) so as to store surplus refrigerant in the accumulator (19), an excessive increase in the high pressure is caused as shown by the solid line in the figure. Since it is suppressed, the refrigeration cycle operates normally. At this time, the pressure adjustment valve (18) indicated as EVT in FIG. 5 has an opening degree that is more open than the comparative example, as can be seen from the vertical axis at the filling amount Q2 or Q3 in FIG. Be controlled. As shown in FIG. 6, in the comparative example, the COP (coefficient of performance) greatly decreases as the refrigerant charge increases. In this embodiment, even if the refrigerant charge increases, the COP Reduction can be suppressed.

  In the present embodiment, the charging amount of the refrigerant is set to Q3 so that the charging amount is increased as much as possible in consideration of the balance between the cooling operation and the heating operation, and the decrease in the operation efficiency is suppressed. .

  As described above, in the air conditioner (1) using a plate heat exchanger for the outdoor heat exchanger (11), high-pressure pressure rises during cooling operation, and surplus refrigerant is likely to be generated. In the present embodiment, excessive refrigerant storage control is performed in which a part of the refrigerant passing through the refrigerant / refrigerant heat exchanger (17) is returned to the accumulator (19) and stored. Thus, while increasing the charging amount of the refrigerant as much as possible, the high pressure is prevented from rising excessively. This reduces the risk of the compressor (11) stopping during operation, and allows the refrigeration cycle to operate normally.

-Effect of the embodiment-
According to the present embodiment, it is possible to suppress an increase in excess refrigerant during the cooling operation, and thus it is possible to suppress an excessive increase in the high pressure of the refrigerant circuit (10). Moreover, in the present embodiment, unlike storing the refrigerant in the receiver that is a high-pressure vessel, the surplus is obtained by using the accumulator (19) that is generally provided in the refrigerant circuit (10) and is less expensive than the high-pressure receiver. Refrigerant measures can be taken. Therefore, an increase in cost due to the provision of the receiver can be suppressed, and a gas vent valve that needs to be provided in accordance with the receiver need not be provided. In this respect, an increase in cost can be suppressed.

  Further, according to the present embodiment, it is possible to perform an efficient operation by performing the supercooling control until the high pressure reaches the target value during the cooling operation.

  Further, according to the present embodiment, since the high pressure does not increase excessively during the heating operation, it is possible to perform an efficient operation similarly by always performing the supercooling control.

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

  For example, in the above embodiment, a plate heat exchanger is used as the outdoor heat exchanger (11), but a double pipe heat exchanger may be used as the outdoor heat exchanger (11). The configuration of (11) may be changed as appropriate as long as the refrigerant and the liquid heat source medium exchange heat.

  Moreover, although the example which used water as a liquid heat medium was demonstrated in the said embodiment, you may use other liquid heat media, such as a brine.

  In the above-described embodiment, the present invention has one outdoor heat exchanger (11) and a plurality of indoor heat exchangers (15), and all the indoor heat exchangers (15) simultaneously become evaporators or simultaneously. This is an example applied to an air conditioner (1) that can be switched between cooling and heating so that it becomes a condenser, but in an air conditioner that can perform simultaneous cooling and heating operations that mix cooling and heating in multiple indoor heat exchangers You may apply. In that case, the “cooling operation” of the present invention to which the surplus refrigerant storage operation is applied means an operation performed when the total cooling load is larger than the heating load.

  The present invention can also be applied to an air conditioner (1) in which one outdoor heat exchanger (11) and one indoor heat exchanger (15) are connected to switch between heating and cooling. .

  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 an air conditioner that performs air conditioning using cold or hot heat of a liquid heat source medium.

1 Air conditioner
5 Controller (control unit)
10 Refrigerant circuit
10b Liquid piping
11 Compressor
12 Outdoor heat exchanger
13 Outdoor expansion valve (expansion mechanism)
14 Indoor expansion valve
15 Indoor heat exchanger
16 Four-way selector valve (switching mechanism)
17 Refrigerant / refrigerant heat exchanger
17a High pressure flow path
17b Low pressure flow path
18 Pressure regulating valve (pressure regulating mechanism)
19 Accumulator
20 Return refrigerant path

Claims (3)

A refrigerant circuit (10) including a compressor (11), an outdoor heat exchanger (12), an expansion mechanism (13, 14), and an indoor heat exchanger (15), in which the refrigerant circulates; 10) has a switching mechanism (16) for switching the reversible circulation direction of the refrigerant, Ri heat exchanger der the outdoor heat exchanger (12) which is a heat source medium of the refrigerant and a liquid to the heat exchanger, the outdoor heat An air conditioner in which the internal volume of the exchanger (12) is smaller than the internal volume of the indoor heat exchanger (15) ,
A refrigerant / refrigerant heat exchanger (17) having a high-pressure channel (17a) and a low-pressure channel (17b), and an accumulator (19) provided on the suction side of the compressor (11),
The high-pressure flow path (17a) of the refrigerant / refrigerant heat exchanger (17) is connected to the liquid pipe (10b) of the refrigerant circuit (10),
The return refrigerant passage (20) branched from the liquid pipe (10b) is connected to the accumulator (19) via the pressure adjustment mechanism (18) and the low pressure flow path (17b) of the refrigerant / refrigerant heat exchanger (17). And
A control unit (5) is provided that performs surplus refrigerant storage control that adjusts the pressure adjustment mechanism (18) and returns the refrigerant to the accumulator (19) so that the high pressure does not rise above the target value only during cooling operation. An air conditioner characterized by. In claim 1,
The controller (5) performs supercooling control for adjusting the pressure adjustment mechanism (18) so that the supercooling degree of the liquid refrigerant is maintained constant until the high pressure reaches a target value during the cooling operation. An air conditioner that switches to excess refrigerant storage control so that the high pressure does not increase further when the high pressure reaches a target value. In claim 1 or 2,
The air conditioner characterized in that the control unit (5) performs supercooling control for adjusting the pressure adjusting mechanism (18) so that the degree of supercooling of the liquid refrigerant is always kept constant during heating operation.

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