JP2017146015A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of improving performance of cooling and heating while suppressing rise in a discharge refrigerant temperature.SOLUTION: In a cooling operation, a refrigerant discharged from a compressor 101 flows in a four-way valve 103, an outdoor heat exchanger 104, an outdoor expansion mechanism 106, a receiver tank 105, a supercooling heat exchanger 109, indoor expansion mechanisms 301a, 301b and indoor heat exchangers 302a, 302b in this order. In a heating operation, the refrigerant discharged from the compressor 101 flows in the four-way valve 103, the indoor heat exchangers 302a, 302b, the indoor expansion mechanisms 301a, 301b, the supercooling heat exchanger 109, the receiver tank 105, the outdoor expansion mechanism 106 and the outdoor heat exchanger 104 in this order. An air conditioner includes a by-pass pipe 145 for allowing the gas refrigerant in the receiver tank 105 to pass a supercooling expansion mechanism 110 and the supercooling heat exchanger 109 in this order and returning it to a suction port side of the compressor 101.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air conditioner.

In an air conditioner that includes one or a plurality of outdoor units and a plurality of indoor units, and that can operate the plurality of indoor units by either cooling or heating, a compressor, a four-way valve, and outdoor heat An outdoor unit provided with an exchanger and a plurality of indoor units provided with an indoor heat exchanger are connected by a gas pipe and a liquid pipe which are pipes between the units (for example, see Patent Document 1). During the heating operation, the refrigerant discharge pipe of the compressor is connected to the gas pipe via the four-way valve, and is connected in the order of the indoor heat exchanger, the liquid pipe, and the outdoor heat exchanger. And is connected to the refrigerant suction pipe of the compressor. During cooling operation, the refrigerant discharge pipe of the compressor is connected to the outdoor heat exchanger via the four-way valve, and is connected in the order of the liquid pipe, the indoor heat exchanger, and the gas pipe. And is connected to the refrigerant suction pipe of the compressor. Such an air conditioner is configured to perform a cooling operation or a heating operation by switching the four-way valve.
In the conventional configuration, when R32 or a mixed refrigerant containing R32 is used as the refrigerant, R32 has a larger latent heat than R410A, so that the refrigerant circulation amount can be reduced and the refrigerant side pressure loss is reduced. You can make use of it. In this case, a reduction in the diameter of the heat exchanger can be expected. However, when the volume of the outdoor heat exchanger is equal to or less than the volume of the indoor heat exchanger, there is a problem that surplus refrigerant is generated during the cooling operation.
In order to solve the above problem, in Patent Document 1, as shown in FIG. 3, a receiver tank 505 is provided between the outdoor heat exchanger 504 and the outdoor expansion mechanism 506 of the outdoor unit 500, and excess refrigerant is supplied to the receiver tank 505. A bypass pipe 520 and a flow rate adjusting mechanism 515 are provided for storing and returning the refrigerant gas component in the receiver tank 505 to the compressor 501 or the suction pipe, and the flow rate adjusting mechanism 515 is opened during heating operation and closed during cooling operation A configuration is proposed. In FIG. 3, the flow of the refrigerant during the cooling operation is indicated by arrows. In FIG. 3, reference numeral 502 is an oil separator, reference numeral 503 is a four-way valve, and reference numerals 531a and 531b are indoor expansion mechanisms.
By opening the flow rate adjustment mechanism 515 during heating operation, gas components that do not contribute to evaporation bypass the outdoor heat exchanger 504, so that the flow rate of the refrigerant flowing through the outdoor heat exchanger 504 decreases, and the outdoor heat exchanger The refrigerant side pressure loss at 504 can be suppressed.
Further, by closing the flow rate adjusting mechanism 515 during the cooling operation, surplus refrigerant generated when the volume of the outdoor heat exchanger 504 becomes less than or equal to the volume of the indoor heat exchangers 532a and 532b is accommodated in the receiver tank 505. Therefore, it is possible to prevent the refrigerant from being hindered.

JP 2013-204922 A

However, in the prior art, during the cooling operation, the refrigerant condensed in the outdoor heat exchanger 504 flows into the receiver tank 505 and the refrigerant liquid component in the receiver tank 505 is sent to the outdoor expansion mechanism 506. For example, outdoor heat exchange When the degree of supercooling of the refrigerant after passing through the vessel 504 is small or in a gas-liquid two-phase state, the refrigerant flashes due to the pressure loss of the outdoor expansion mechanism 506, and the pressure loss on the refrigerant side of the liquid pipe increases, resulting in performance. There was a problem that would decrease.
Further, during the heating operation, the flow rate adjusting mechanism 515 is opened and the low-temperature and high-pressure refrigerant returns to the suction side of the compressor 501, so that the effect of reducing the discharged refrigerant temperature is obtained. However, during the cooling operation, the flow rate adjusting mechanism 515 is closed, and the effect of reducing the discharged refrigerant temperature cannot be obtained. For this reason, for example, when the number of indoor units 530a and 530b is large and R32 is used as a refrigerant in a system that is connected by a long pipe, the suction pressure decreases due to pipe pressure loss on the refrigerant side, so the pressure ratio However, since the refrigerant flowing through the flow rate adjusting mechanism 515 cannot be cooled, there has been a problem that the discharged refrigerant temperature becomes high during the cooling operation.
The present invention solves the above-described problems, and an object of the present invention is to improve cooling and heating performance in an air-conditioning apparatus while suppressing an increase in discharged refrigerant temperature.

  To achieve the above object, the present invention comprises one or a plurality of outdoor units and a plurality of indoor units, the outdoor unit comprising a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion mechanism, and A receiver tank, the indoor unit has an indoor expansion mechanism and an indoor heat exchanger, and the outdoor unit and the indoor unit are connected to each other by a gas pipe and a liquid pipe. In any one of the air conditioners that can be operated, the outdoor unit includes a supercooling heat exchanger that exchanges heat with the refrigerant flowing through the outdoor unit, and a supercooling expansion mechanism. The discharged refrigerant includes the four-way valve, the outdoor heat exchanger, the outdoor expansion mechanism, the receiver tank, the supercooling heat exchanger, the indoor expansion mechanism, and the indoor heat exchange. The refrigerant discharged from the compressor during heating operation is the four-way valve, the indoor heat exchanger, the indoor expansion mechanism, the supercooling heat exchanger, the receiver tank, the outdoor expansion mechanism, The receiver tank has a structure for separating the refrigerant into a gas and liquid, and the gas refrigerant in the receiver tank is passed in the order of the supercooling expansion mechanism and the supercooling heat exchanger. And a bypass circuit for returning to the suction port side of the compressor.

In addition, the present invention includes a branch pipe that connects the upstream side of the supercooling expansion mechanism in the bypass circuit and a pipe that connects the supercooling heat exchanger and the indoor expansion mechanism.
In the present invention, a first temperature sensor is provided between the four-way valve and a junction where the bypass circuit merges between the suction port and the four-way valve, and the receiver tank and the supercooling heat A second temperature sensor is provided between the exchanger and a third temperature sensor is provided between the junction and the suction port of the compressor, and the first temperature sensor and the second temperature sensor are provided. The opening degree of the supercooling expansion mechanism is adjusted so that the detection value of the third temperature sensor becomes a predetermined value using the detection value of the temperature sensor.
Furthermore, the present invention is characterized in that a diameter of a pipe connecting the receiver tank and the supercooling expansion mechanism in the bypass circuit is larger than a diameter of the branch pipe.
In addition, the present invention is characterized in that the refrigerant is R32 or a mixed refrigerant containing R32.

  According to the air conditioner of the present invention, during cooling operation, the gas refrigerant separated in the receiver tank passes through the bypass circuit in the order of the supercooling expansion mechanism and the supercooling heat exchanger, and is cooled by the supercooling expansion mechanism. , The suction refrigerant temperature of the compressor can be lowered, and the discharge refrigerant temperature of the compressor during the cooling operation can be lowered. Further, during the cooling operation, the liquid refrigerant flowing from the receiver tank to the indoor heat exchanger side is cooled by the supercooling heat exchanger through which the refrigerant in the bypass circuit flows, and the degree of supercooling increases. For this reason, the ratio of the liquid refrigerant which contributes to evaporation in the gas-liquid two-phase refrigerant flowing into the indoor heat exchanger can be increased, and the cooling performance can be improved. In addition, during the heating operation, the refrigerant gas refrigerant that has returned from the indoor unit side to the receiver tank returns to the compressor suction port through the subcooling expansion mechanism of the bypass circuit. Can be reduced. Moreover, since the gas refrigerant that does not contribute to evaporation passes through the bypass circuit and bypasses the outdoor heat exchanger during heating operation, the refrigerant circulation amount of the outdoor heat exchanger can be reduced, and the pressure loss of the refrigerant can be reduced. For this reason, performance improvement can be aimed at suppressing the raise of discharge refrigerant temperature at the time of air_conditionaing | cooling operation and heating operation.

It is a refrigerant circuit figure of the air harmony device concerning an embodiment of the invention. It is a refrigerant circuit figure of the air harmony device at the time of heating operation. It is a refrigerant circuit figure of the conventional air conditioning apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention. Here, FIG. 1 illustrates a state during the cooling operation.
The air conditioner 10 in FIG. 1 has a configuration in which a plurality of indoor units are connected to one outdoor unit. The configuration of the refrigeration cycle is not limited to that shown in FIG. For example, two or more outdoor units can be connected in parallel.

  The air conditioner 10 includes an outdoor unit 100 and a plurality of indoor units 300a and 300b, and the outdoor unit 100 and the indoor units 300a and 300b are connected by inter-unit piping through which a refrigerant flows. This inter-unit pipe includes a liquid pipe 210 and a gas pipe 220. The indoor units 300a and 300b are connected in parallel to the inter-unit pipe. Here, the refrigerant flowing through the air conditioner 10 is R32 or a mixed refrigerant partially including R32.

The indoor units 300a and 300b include indoor expansion mechanisms 301a and 301b and indoor heat exchangers 302a and 302b that heat and cool the room by a blower (not shown).
One ends of the indoor units 300a and 300b on the side where the indoor expansion mechanisms 301a and 301b are provided are connected to the liquid pipe 210 by distribution pipes 303 and 303, respectively. The other ends of the indoor units 300a and 300b are connected to the gas pipe 220 by distribution pipes 304 and 304, respectively.

The outdoor unit 100 switches the refrigerant circuit according to the operating state of the cooling operation and the heating operation, the compressor 101, the oil separator 102 that separates the refrigeration oil contained in the refrigerant discharged from the compressor 101, and returns the oil to the compressor 101. A four-way valve 103, an outdoor heat exchanger 104 that radiates and absorbs heat by a blower (not shown), a receiver tank 105 that can store refrigerant and separates gas refrigerant and liquid refrigerant, and outdoor expansion Mechanism 106, electromagnetic valve 108, supercooling heat exchanger 109, supercooling expansion mechanism 110 for adjusting the temperature of the refrigerant flowing into supercooling heat exchanger 109, check valves 107 and 111, and control unit 150.
The outdoor unit 100 includes a liquid pipe connection port 116 to which an end of the liquid pipe 210 on the outdoor unit 100 side is connected, and a gas pipe connection port 117 to which an end of the gas pipe 220 on the outdoor unit 100 side is connected. .

The outdoor unit 100 includes a refrigerant discharge pipe 140 that connects the refrigerant discharge port of the compressor 101 and one end of the outdoor heat exchanger 104, and a refrigerant that connects the other end of the outdoor heat exchanger 104 and the liquid pipe connection port 116. A pipe 141, a refrigerant pipe 142 connecting the gas pipe connection port 117 and the four-way valve 103, and a refrigerant suction pipe 143 connecting the four-way valve 103 and the refrigerant suction port of the compressor 101 are provided.
The refrigerant discharge pipe 140 is provided with an oil separator 102 and a four-way valve 103 in order from the compressor 101 side.
In the refrigerant pipe 141, an outdoor expansion mechanism 106, a receiver tank 105, and a supercooling heat exchanger 109 are provided in order from the upstream side of the refrigerant flow during the cooling operation.

The outdoor unit 100 also includes a refrigerant return pipe 144 that connects the gas refrigerant outlet 105 a of the receiver tank 105 and the refrigerant discharge pipe 140, and a bypass pipe 145 that connects the outlet 105 a of the receiver tank 105 and the refrigerant suction pipe 143 ( A bypass circuit) and a branch pipe 146 connecting the refrigerant pipe 141 and the bypass pipe 145.
Specifically, the end of the refrigerant return pipe 144 is connected between the oil separator 102 and the four-way valve 103 in the refrigerant discharge pipe 140. The refrigerant return pipe 144 is provided with an electromagnetic valve 108, and the flow rate of the refrigerant in the refrigerant return pipe 144 is controlled by the electromagnetic valve 108.

In addition, a check valve 107, a supercooling expansion mechanism 110, and a supercooling heat exchanger 109 are connected to the bypass pipe 145 in order from the upstream side. The check valve 107 is a check valve that allows only the flow from the receiver tank 105 to the supercooling expansion mechanism 110 side. In the supercooling heat exchanger 109, heat is exchanged between the refrigerant in the bypass pipe 145 and the refrigerant in the refrigerant pipe 141.
One end of the branch pipe 146 is connected to a pipe 141 a that forms a section between the supercooling heat exchanger 109 and the liquid pipe connection port 116 in the refrigerant pipe 141. Here, the pipe 141a constitutes a part of the pipe connecting the supercooling heat exchanger 109 and the indoor expansion mechanisms 301a and 301b.
The other end of the branch pipe 146 is connected to a portion of the bypass pipe 145 upstream of the supercooling expansion mechanism 110, that is, between the check valve 107 and the supercooling expansion mechanism 110. A check valve 111 is provided in the branch pipe 146. The check valve 111 is a check valve that allows only a flow from the pipe 141a to the bypass pipe 145 side.
In the bypass pipe 145, at least the diameter of the pipe 145 a on the upstream side of the subcooling expansion mechanism 110 is formed larger than the diameter of the branch pipe 146.

The outdoor unit 100 includes a first temperature sensor 114 in the refrigerant suction pipe 143 between the junction portion 145 b where the bypass pipe 145 merges with the refrigerant suction pipe 143 and the four-way valve 103.
The outdoor unit 100 includes a second temperature sensor 112 between the receiver tank 105 and the supercooling heat exchanger 109.
Furthermore, the outdoor unit 100 includes a third temperature sensor 113 in the refrigerant suction pipe 143 between the junction 145 b and the suction port of the compressor 101.
That is, the temperature of the refrigerant before the bypass pipe 145 merges in the refrigerant suction pipe 143 is detected by the first temperature sensor 114, and the temperature of the refrigerant after the bypass pipe 145 merges in the refrigerant suction pipe 143 is the third temperature. It is detected by the sensor 113. Further, the temperature of the refrigerant before leaving the receiver tank 105 and flowing into the supercooling heat exchanger 109 is detected by the second temperature sensor 112.

  The control unit 150 controls operations of the compressor 101, the four-way valve 103, the outdoor expansion mechanism 106, the electromagnetic valve 108, and the supercooling expansion mechanism 110. In addition, the control unit 150 acquires detection values of the first temperature sensor 114, the second temperature sensor 112, and the third temperature sensor 113.

Next, operations of the outdoor unit 100 and the indoor units 300a and 300b will be described.
In FIG. 1, the flow of the refrigerant during the cooling operation is indicated by arrows.
As shown in FIG. 1, during the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 to the refrigerant discharge pipe 140 is separated from the refrigeration oil by the oil separator 102 and then passes through the four-way valve 103 to the outdoor. It flows into the heat exchanger 104. The high-pressure liquid refrigerant that has radiated heat to the outside air and condensed by the outdoor heat exchanger 104 passes through the outdoor expansion mechanism 106 and then flows into the receiver tank 105 through the refrigerant pipe 141. At this time, the outdoor expansion mechanism 106 is controlled so that the degree of supercooling of the refrigerant at the outlet of the outdoor heat exchanger 104 becomes a predetermined value.
The refrigerant flowing into the receiver tank 105 is separated into a gas refrigerant and a liquid refrigerant, and only the liquid refrigerant is led to the supercooling heat exchanger 109 through the refrigerant pipe 141. The refrigerant flowing into the supercooling heat exchanger 109 through the refrigerant pipe 141 exchanges heat with the refrigerant flowing into the supercooling heat exchanger 109 through the bypass pipe 145. This heat exchange will be described later.

  The main flow of the refrigerant that has passed through the supercooling heat exchanger 109 is guided to the indoor units 300a and 300b through the liquid pipe 210 and the distribution pipes 303 and 303. The liquid refrigerant flowing into the indoor units 300a and 300b from the liquid pipe 210 is decompressed by the indoor expansion mechanisms 301a and 301b to be in a gas-liquid two-phase state, and after cooling the room with the indoor heat exchangers 302a and 302b, the distribution pipe 304 , 304 through the gas pipe 220. The refrigerant that has passed through the gas pipe 220 returns to the outdoor unit 100, and is sucked into the compressor 101 through the refrigerant pipe 142, the four-way valve 103, and the refrigerant suction pipe 143 in order.

The gas refrigerant separated in the receiver tank 105 branches and flows into the refrigerant return pipe 144 and the bypass pipe 145.
The refrigerant that flows into the refrigerant return pipe 144 from the receiver tank 105 flows between the oil separator 102 and the four-way valve 103 in the refrigerant discharge pipe 140, and then flows to the outdoor heat exchanger 104 through the four-way valve 103.
Specifically, the control unit 150 opens the electromagnetic valve 108 when detecting a refrigerant shortage by a sensor or the like (not shown), whereby the liquid refrigerant stored in the receiver tank 105 is a high-pressure gas refrigerant. And flows into the refrigerant discharge pipe 140 through the refrigerant return pipe 144. Thereby, the refrigerant shortage on the refrigerant discharge pipe 140 side is solved. Moreover, the control part 150 makes the solenoid valve 108 a closed state, when lack of a refrigerant | coolant is not detected.

  The refrigerant flowing into the bypass pipe 145 from the receiver tank 105 flows into the supercooling expansion mechanism 110 through the check valve 107. Further, a part of the refrigerant flowing into the supercooling heat exchanger 109 from the refrigerant pipe 141 and flowing through the pipe 141a branches and flows to the branch pipe 146, passes through the check valve 111, and is a supercooling expansion mechanism in the bypass pipe 145. 110 and then flows to the supercooling expansion mechanism 110.

The refrigerant that has flowed into the supercooling expansion mechanism 110 is decompressed by the supercooling expansion mechanism 110 to become a low temperature, and flows into the supercooling heat exchanger 109. The low-temperature refrigerant that has flowed into the supercooling heat exchanger 109 through the supercooling expansion mechanism 110 exchanges heat with the refrigerant that has flowed into the supercooling heat exchanger 109 from the refrigerant pipe 141, and the supercooling heat exchanger from the refrigerant pipe 141. The refrigerant flowing into 109 is cooled. Thereby, since the supercooling degree of the refrigerant | coolant which flows into the indoor unit 300a, 300b from the supercooling heat exchanger 109 increases, it can cool efficiently.
As described above, in the bypass pipe 145, at least the diameter of the pipe 145 a on the upstream side of the subcooling expansion mechanism 110 is formed larger than the diameter of the branch pipe 146. Thereby, while the pressure loss of the refrigerant | coolant of the bypass pipe 145 becomes small, the pressure loss of the refrigerant | coolant of the branch pipe 146 becomes large, and it can prevent that the refrigerant | coolant amount which flows into the branch pipe 146 becomes excess.

  The refrigerant that flows into the supercooling heat exchanger 109 from the supercooling expansion mechanism 110 and exchanges heat further flows through the bypass pipe 145, merges with the refrigerant suction pipe 143 at the junction 145b, passes through the refrigerant suction pipe 143, and is compressed by the compressor. 101 is inhaled. That is, in the present embodiment, the refrigerant that has passed through the supercooling expansion mechanism 110 and has reached a low temperature returns to the compressor 101, and the suction refrigerant temperature of the compressor 101 decreases, so the discharge refrigerant temperature of the compressor 101 decreases. Can be made.

  Specifically, the control unit 150 detects the suction refrigerant temperature T1 (not shown) detected by the first temperature sensor 114 and the refrigerant temperature T2 (not shown) on the outlet side of the receiver tank 105 detected by the second temperature sensor 112. ). When the suction refrigerant temperature T1 <the refrigerant temperature T2, the control unit 150 causes the supercooling expansion mechanism 110 to be fully closed. As a result, it is possible to prevent the refrigerant on the outlet side of the receiver tank 105 having a temperature higher than the suction refrigerant temperature T1 from returning to the suction port of the compressor 101 through the bypass pipe 145, and to suppress an increase in the discharge refrigerant temperature of the compressor 101. it can.

Moreover, the control part 150 increases the opening degree of the subcooling expansion mechanism 110, when the suction refrigerant temperature T1> refrigerant temperature T2. Thereby, since the refrigerant | coolant which passed the supercooling expansion mechanism 110 and became low temperature returns to the compressor 101, the suction | inhalation refrigerant | coolant temperature of the compressor 101 can be reduced.
Further, the control unit 150 adjusts the opening degree of the subcooling expansion mechanism 110 in a state where the suction refrigerant temperature T1> the refrigerant temperature T2, and the refrigerant on the suction port side of the compressor 101 detected by the third temperature sensor 113. The supercooling expansion mechanism 110 is controlled so that the temperature T3 (not shown) becomes a predetermined value. Here, the predetermined value of the refrigerant temperature T3 is set so that the refrigerant does not excessively return to the compressor 101 through the bypass pipe 145. For this reason, the performance fall by a refrigerant | coolant returning excessively can be suppressed.

FIG. 2 is a refrigerant circuit diagram of the air-conditioning apparatus 10 during heating operation. In FIG. 2, the flow of the refrigerant during the heating operation is indicated by arrows.
As shown in FIG. 2, during heating operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 to the refrigerant discharge pipe 140 passes through the four-way valve 103 after the refrigeration oil is separated by the oil separator 102. It flows into the pipe 142. The refrigerant that has flowed into the refrigerant pipe 142 is led to the indoor units 300a and 300b through the gas pipe 220 and the distribution pipes 304 and 304.
The refrigerant led to the indoor units 300a and 300b condenses in the indoor heat exchangers 302a and 302b to heat the room. At this time, the indoor expansion mechanisms 301a and 301b are controlled so that the degree of supercooling of the refrigerant at the outlets of the indoor heat exchangers 302a and 302b becomes a set value.

The high-pressure liquid refrigerant that has passed through the indoor units 300 a and 300 b passes through the liquid pipe 210 and then flows into the outdoor unit 100. The high-pressure liquid refrigerant that has flowed into the outdoor unit 100 passes through the pipe 141 a and branches into a flow toward the supercooling heat exchanger 109 and a flow through the branch pipe 146.
The refrigerant that has passed through the supercooling heat exchanger 109 from the pipe 141 a is guided to the receiver tank 105, and is separated into liquid refrigerant and gas refrigerant in the receiver tank 105.
The liquid refrigerant separated in the receiver tank 105 flows through the refrigerant pipe 141, becomes a low-pressure and low-temperature gas-liquid two-phase state by the outdoor expansion mechanism 106, and then absorbs heat from the outside air and evaporates in the outdoor heat exchanger 104, and the low-pressure gas Becomes a refrigerant. This refrigerant flows into the refrigerant suction pipe 143 through the four-way valve 103 and is sucked into the compressor 101. Thus, during the heating operation, the gas refrigerant is separated by the receiver tank 105 upstream of the outdoor heat exchanger 104, and the gas refrigerant that does not contribute to evaporation during the heating operation is suppressed from flowing into the outdoor heat exchanger 104. Thereby, since the refrigerant | coolant circulation amount of the outdoor heat exchanger 104 can be made small and the pressure loss of a refrigerant | coolant can be reduced, heating performance can be improved.

The gas refrigerant separated in the receiver tank 105 branches and flows into the refrigerant return pipe 144 and the bypass pipe 145.
The refrigerant that flows into the refrigerant return pipe 144 from the receiver tank 105 flows between the oil separator 102 and the four-way valve 103 in the refrigerant discharge pipe 140, and then flows to the outdoor heat exchanger 104 through the four-way valve 103.
Specifically, the control unit 150 opens the electromagnetic valve 108 when detecting a refrigerant shortage by a sensor or the like (not shown), whereby the liquid refrigerant stored in the receiver tank 105 is a high-pressure gas refrigerant. And flows into the refrigerant discharge pipe 140 through the refrigerant return pipe 144. Thereby, the refrigerant shortage on the refrigerant discharge pipe 140 side is solved. Moreover, the control part 150 makes the solenoid valve 108 a closed state, when lack of a refrigerant | coolant is not detected.

  The refrigerant flowing into the bypass pipe 145 from the receiver tank 105 flows into the supercooling expansion mechanism 110 through the check valve 107. Further, the refrigerant flowing from the pipe 141 a to the branch pipe 146 passes through the check valve 111, joins the upstream side of the supercooling expansion mechanism 110 in the bypass pipe 145, and then flows to the supercooling expansion mechanism 110.

  The refrigerant that has flowed into the supercooling expansion mechanism 110 is decompressed by the supercooling expansion mechanism 110 to become a low temperature, and flows into the supercooling heat exchanger 109. The low-temperature refrigerant that has flowed into the supercooling heat exchanger 109 through the supercooling expansion mechanism 110 exchanges heat with the refrigerant that has flowed into the supercooling heat exchanger 109 from the refrigerant pipe 141, and the temperature rises.

The refrigerant that flows into the supercooling heat exchanger 109 from the supercooling expansion mechanism 110 and exchanges heat further flows through the bypass pipe 145, merges with the refrigerant suction pipe 143 at the junction 145b, passes through the refrigerant suction pipe 143, and is compressed by the compressor. 101 is inhaled. That is, in the present embodiment, the refrigerant that has passed through the supercooling expansion mechanism 110 and has reached a low temperature returns to the compressor 101, and the suction refrigerant temperature of the compressor 101 decreases, so the discharge refrigerant temperature of the compressor 101 decreases. Can be made.
In the present embodiment, the low-temperature refrigerant that has flowed into the supercooling heat exchanger 109 through the supercooling expansion mechanism 110 exchanges heat with the supercooling heat exchanger 109 and then returns to the compressor 101 after the temperature rises. . Thereby, even when the flow rate of the bypass pipe 145 is increased, it is possible to prevent the refrigerant on the refrigerant suction pipe 143 side from being overcooled and to prevent liquid back to the compressor 101. Therefore, a large amount of the gas refrigerant separated in the receiver tank 105 can be caused to flow to the bypass pipe 145, and the gas refrigerant that does not contribute to evaporation during heating operation can be efficiently bypassed to the outdoor heat exchanger 104. Can be improved.

  Specifically, when the discharge refrigerant temperature of the compressor 101 detected by a sensor (not shown) is lower than a predetermined value, the control unit 150 closes the supercooling expansion mechanism 110 and connects the compressor from the bypass pipe 145 to the compressor. The refrigerant 101 is prevented from flowing. This prevents the refrigerant from bypassing excessively and returning to the compressor 101 in a state where the discharged refrigerant temperature is low.

Further, the control unit 150 increases the opening degree of the supercooling expansion mechanism 110 when the discharge refrigerant temperature of the compressor 101 detected by a sensor (not shown) is equal to or higher than a predetermined value. Thereby, since the refrigerant | coolant which passed the supercooling expansion mechanism 110 and became low temperature returns to the compressor 101, the suction | inhalation refrigerant | coolant temperature of the compressor 101 can be reduced.
Furthermore, when the controller 150 adjusts the opening degree of the supercooling expansion mechanism 110 when the discharged refrigerant temperature is equal to or higher than a predetermined value, the refrigerant on the inlet side of the compressor 101 detected by the third temperature sensor 113 is used. The supercooling expansion mechanism 110 is controlled so that the temperature T3 (not shown) becomes a predetermined value. Here, the predetermined value of the refrigerant temperature T3 is set so that the refrigerant does not excessively return to the compressor 101 through the bypass pipe 145.

As described above, according to the embodiment of the present invention, the air conditioner 10 includes the outdoor unit 100 and the plurality of indoor units 300a and 300b. The outdoor unit 100 includes the compressor 101 and the four-way valve 103. The outdoor heat exchanger 104, the outdoor expansion mechanism 106, and the receiver tank 105. The indoor units 300a and 300b include indoor expansion mechanisms 301a and 301b and indoor heat exchangers 302a and 302b. The indoor units 300a and 300b are connected by a gas pipe 220 and a liquid pipe 210 and can be operated in either a cooling operation or a heating operation. The outdoor unit 100 exchanges heat with the refrigerant flowing in the outdoor unit 100. A supercooling heat exchanger 109 and a supercooling expansion mechanism 110 are provided, and the compressor 1 is used during cooling operation. The refrigerant discharged from 1 includes a four-way valve 103, an outdoor heat exchanger 104, an outdoor expansion mechanism 106, a receiver tank 105, a supercooling heat exchanger 109, indoor expansion mechanisms 301a and 301b, and indoor heat exchangers 302a and 302b. The refrigerant discharged from the compressor 101 during the heating operation is the four-way valve 103, the indoor heat exchangers 302a and 302b, the indoor expansion mechanisms 301a and 301b, the supercooling expansion mechanism 110, the receiver tank 105, and the outdoor expansion mechanism. 106 and the outdoor heat exchanger 104, the receiver tank 105 has a structure for separating the refrigerant into gas and liquid, and the gas refrigerant in the receiver tank 105 is separated into the supercooling expansion mechanism 110 and the supercooling heat exchanger 109 in this order. A bypass pipe 145 that passes through and returns to the suction port side of the compressor 101 is provided.
Thus, during the cooling operation, the gas refrigerant separated in the receiver tank 105 passes through the bypass pipe 145 in the order of the supercooling expansion mechanism 110 and the supercooling heat exchanger 109, and is compressed after being cooled by the supercooling expansion mechanism 110. Since it returns to the suction port of the machine 101, the suction refrigerant temperature of the compressor 101 can be lowered, and the discharge refrigerant temperature of the compressor 101 during the cooling operation can be lowered. Further, during the cooling operation, the liquid refrigerant flowing from the receiver tank 105 toward the indoor heat exchangers 302a and 302b is cooled by the supercooling heat exchanger 109 through which the refrigerant in the bypass pipe 145 flows, and the degree of supercooling increases. For this reason, the ratio of the liquid refrigerant which contributes to evaporation in the refrigerant in the gas-liquid two-phase state flowing into the indoor heat exchangers 302a and 302b can be increased, and the cooling performance can be improved. Further, during the cooling operation, even when the outdoor expansion mechanism 106 is fully opened, pressure loss occurs at the orifice portion of the outdoor expansion mechanism 106 and the refrigerant tends to flush (bubbles are generated). Since the refrigerant that has passed through the mechanism 106 is separated from the gas refrigerant in the receiver tank 105 and flows to the liquid pipe 210 side, the refrigerant can be prevented from flashing on the liquid pipe 210 side, and the cooling performance can be improved. Also, when there is a heat source near the outdoor unit 100, when the fins of the outdoor heat exchanger 104 are clogged, or when the outdoor unit 100 is installed in a place with poor ventilation, the ambient temperature rises. However, even in this case, the receiver tank 105 can similarly suppress the occurrence of flash.
Further, during the heating operation, the refrigerant gas refrigerant that has returned to the receiver tank 105 from the indoor units 300a and 300b side returns to the suction port of the compressor 101 through the supercooling expansion mechanism 110 of the bypass pipe 145. The discharge refrigerant temperature of the compressor can be lowered. In addition, during heating operation, the gas refrigerant that does not contribute to evaporation passes through the bypass pipe 145 and bypasses the outdoor heat exchanger 104. Therefore, the refrigerant circulation amount of the outdoor heat exchanger 104 can be reduced, and the pressure loss of the refrigerant can be reduced. . For this reason, performance improvement can be aimed at suppressing the raise of discharge refrigerant temperature at the time of air_conditionaing | cooling operation and heating operation.

  In addition, the air conditioner 10 includes a branch pipe 146 that connects the upstream side of the subcooling expansion mechanism 110 in the bypass pipe 145 and a pipe that connects the subcooling heat exchanger 109 and the indoor expansion mechanisms 301a and 301b. Thereby, at the time of cooling operation, a part of the liquid refrigerant flowing from the receiver tank 105 to the supercooling heat exchanger 109 is caused to flow to the supercooling expansion mechanism 110 and the supercooling heat exchanger 109 via the branch pipe 146. Can be returned to the suction port of the compressor 101 to lower the discharge refrigerant temperature. Further, during the heating operation, a part of the refrigerant that has returned to the outdoor unit 100 through the indoor expansion mechanisms 301a and 301b is caused to flow to the supercooling expansion mechanism 110 and the supercooling heat exchanger 109 via the branch pipe 146. Can be returned to the suction port of the compressor 101 to lower the discharge refrigerant temperature.

  In addition, a first temperature sensor 114 is provided between the merging portion 145 b where the bypass pipe 145 merges between the suction port of the compressor 101 and the four-way valve 103 and the four-way valve 103, and the receiver tank 105 and the supercooling heat A second temperature sensor 112 is provided between the exchanger 109 and a third temperature sensor 113 is provided between the merging portion 145b and the suction port of the compressor 101, and the first temperature sensor 114 and the second temperature sensor 114 are provided. The opening degree of the supercooling expansion mechanism 110 is adjusted using the detected value of the temperature sensor 112 so that the detected value of the third temperature sensor 113 becomes a predetermined value. Thereby, the refrigerant temperature on the suction side before the bypass pipe 145 joins can be detected by the first temperature sensor 114, the refrigerant temperature on the outlet side of the receiver tank 105 can be detected by the second temperature sensor 112, 3, the temperature of the refrigerant near the suction port can be detected downstream of the merge portion 145 b, so that the amount of the refrigerant returning to the suction port of the compressor 101 through the bypass pipe 145 can be appropriately controlled. The discharged refrigerant temperature can be effectively reduced.

Further, the diameter of the pipe connecting the receiver tank 105 and the subcooling expansion mechanism 110 in the bypass pipe 145 is larger than the diameter of the branch pipe 146. Since the gas refrigerant flowing from the receiver tank 105 through the bypass pipe 145 has a lower density than the liquid refrigerant or the gas-liquid two-phase refrigerant that merges from the branch pipe 146 to the bypass pipe 145, the diameter of the pipe of the bypass pipe 145 is increased. As a result, the pressure loss of the refrigerant in the bypass pipe 145 is reduced. Further, by reducing the diameter of the branch pipe 146 through which the liquid refrigerant or the gas-liquid two-phase refrigerant flows, the pressure loss of the refrigerant in the branch pipe 146 increases. For this reason, it can suppress that a refrigerant | coolant flows biased to the branch pipe 146 and the refrigerant | coolant amount of the bypass pipe 145 decreases. Thereby, when the gas refrigerant of the bypass pipe 145 and the liquid refrigerant or the gas-liquid two-phase refrigerant of the branch pipe 146 flow together and then flow into the supercooling heat exchanger 109, it is possible to suppress performance degradation due to poor refrigerant distribution.
Further, since the refrigerant is R32 or a mixed refrigerant containing R32, the global warming potential (GWP) is smaller than that of the R410A refrigerant. For this reason, when R32 or a mixed refrigerant containing R32 is used, the influence on the environment can be reduced while suppressing an increase in the discharge refrigerant temperature.

In addition, the said embodiment shows the one aspect | mode which applied this invention, Comprising: This invention is not limited to the said embodiment.
In the above-described embodiment, the refrigerant that has flowed into the supercooling heat exchanger 109 from the supercooling expansion mechanism 110 and exchanged heat further flows through the bypass pipe 145, and merges with the refrigerant suction pipe 143 at the junction 145b. Although described as what is sucked into the compressor 101 through 143, the present invention is not limited to this. The refrigerant in the bypass pipe 145 may be returned to the suction side of the compressor 101. For example, in a multistage compression compressor in which a low pressure side compression chamber and a high pressure side compression chamber are connected in series, It is good also as a structure which returns the refrigerant | coolant of the bypass pipe 145 to the part of the intermediate pressure between high pressure side compression chambers.

DESCRIPTION OF SYMBOLS 10 Air conditioning apparatus 100 Outdoor unit 101 Compressor 103 Four way valve 104 Outdoor heat exchanger 105 Receiver tank 106 Outdoor expansion mechanism 109 Cooling heat exchanger 110 Cooling expansion mechanism 112 2nd temperature sensor 113 3rd temperature sensor 114 1st temperature sensor Temperature sensor 145 Bypass pipe (bypass circuit)
146 Branch pipe 210 Liquid pipe 220 Gas pipe 300a, 300b Indoor unit 301a, 301b Indoor expansion mechanism 302a, 302b Indoor heat exchanger

Claims (5)

One or a plurality of outdoor units and a plurality of indoor units, the outdoor unit includes a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion mechanism, and a receiver tank, the indoor unit is An air conditioner having an indoor expansion mechanism and an indoor heat exchanger, wherein the outdoor unit and the indoor unit are connected by a gas pipe and a liquid pipe, and can be operated in either a cooling operation or a heating operation. ,
The outdoor unit includes a supercooling heat exchanger that exchanges heat with the refrigerant flowing through the outdoor unit, and a supercooling expansion mechanism,
The refrigerant discharged from the compressor during the cooling operation includes the four-way valve, the outdoor heat exchanger, the outdoor expansion mechanism, the receiver tank, the supercooling heat exchanger, the indoor expansion mechanism, and the indoor heat. Flows in the order of the exchanger,
The refrigerant discharged from the compressor during the heating operation includes the four-way valve, the indoor heat exchanger, the indoor expansion mechanism, the supercooling heat exchanger, the receiver tank, the outdoor expansion mechanism, and the outdoor heat. Flows in the order of the exchanger,
The receiver tank has a structure for separating the refrigerant into gas and liquid,
An air conditioner comprising a bypass circuit that passes the gas refrigerant in the receiver tank in the order of the supercooling expansion mechanism and the supercooling heat exchanger and returns the refrigerant to the suction port side of the compressor.   The air conditioner according to claim 1, further comprising a branch pipe that connects an upstream side of the subcooling expansion mechanism in the bypass circuit and a pipe that connects the supercooling heat exchanger and the indoor expansion mechanism. . A first temperature sensor is provided between the merge portion and the four-way valve where the bypass circuit merges between the suction port and the four-way valve;
A second temperature sensor is provided between the receiver tank and the supercooling heat exchanger;
A third temperature sensor is provided between the junction and the suction port of the compressor;
Using the detection values of the first temperature sensor and the second temperature sensor, the opening degree of the supercooling expansion mechanism is adjusted so that the detection value of the third temperature sensor becomes a predetermined value. The air conditioning apparatus according to claim 2.   The air conditioning apparatus according to claim 2, wherein a diameter of a pipe connecting the receiver tank and the supercooling expansion mechanism in the bypass circuit is larger than a diameter of the branch pipe.   The air conditioner according to any one of claims 1 to 4, wherein the refrigerant is R32 or a mixed refrigerant containing R32.

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