JP7741769B2 - air conditioner - Google Patents

Description

An embodiment of the present invention relates to an air conditioner.

Air conditioners, such as air conditioners, regulate indoor temperatures by condensing and evaporating refrigerant in a refrigeration cycle. During heating operation, the refrigerant evaporates in the outdoor heat exchanger (evaporator) and condenses in the indoor heat exchanger (condenser). Conversely, during cooling operation, the refrigerant condenses in the outdoor heat exchanger (condenser) and evaporates in the indoor heat exchanger (evaporator).

Patent No. 5821709

If the efficiency of the indoor or outdoor heat exchanger is improved, the heat exchanger can be increased in capacity or made smaller. If the heat exchanger is made smaller, the total amount of refrigerant in the air conditioner can be reduced.

One example of the problem solved by this invention is to provide an air conditioner that can reduce the amount of refrigerant used.

An air conditioner according to one embodiment of the present invention comprises an outdoor heat exchanger, an indoor heat exchanger, a first pipe, a second pipe, a compressor, an ejector, a gas-liquid separator, a third pipe, a fourth pipe, and a third heat exchanger. The first pipe connects the outdoor heat exchanger and the indoor heat exchanger, and a refrigerant flows through it. The second pipe connects the indoor heat exchanger and the outdoor heat exchanger, and the refrigerant flows through it. The compressor is provided on the first pipe and has an inlet for drawing in the refrigerant and an outlet for discharging the refrigerant. The ejector is provided in the second piping and has an outlet connected to a first heat exchanger, which is one of the outdoor heat exchanger and the indoor heat exchanger, via the second piping, a first inlet connected to a second heat exchanger, which is the other of the indoor heat exchanger and the indoor heat exchanger, via the second piping, and a second inlet, and is capable of mixing the refrigerant supplied to the first inlet with the refrigerant supplied to the second inlet, increasing the pressure of the refrigerant, and supplying the refrigerant from the outlet to the first heat exchanger. The gas-liquid separator is provided in the second piping between the second heat exchanger and the first inlet, and separates the refrigerant supplied from the second heat exchanger into the liquid refrigerant and the refrigerant containing gas, and supplies the refrigerant containing gas to the first inlet via the second piping. The third pipe is connected to the second pipe between the second heat exchanger and the gas-liquid separator, and is connected to the first pipe between the discharge port and the second heat exchanger. The fourth pipe connects the gas-liquid separator to the second inlet and distributes the liquid refrigerant from the gas-liquid separator. The third heat exchanger exchanges heat between the refrigerant flowing through the third pipe and the refrigerant flowing through the fourth pipe.

The air conditioner may further include, for example, a first expansion valve provided in the fourth pipe between the gas-liquid separator and the third heat exchanger.

The air conditioner further includes, for example, a first sensor, a second sensor, and a control device. The first sensor measures the temperature of the refrigerant flowing through the fourth pipe between the third heat exchanger and the gas-liquid separator. The second sensor measures the temperature of the refrigerant flowing through the fourth pipe between the third heat exchanger and the second inlet. The control device acquires measurement results from the first sensor and the second sensor and controls the opening of the first expansion valve based on the measurement results.

The air conditioner may further include, for example, a second expansion valve provided in the second piping between the gas-liquid separator and the second heat exchanger.

The air conditioner may further include, for example, a heat storage material thermally connected to the third heat exchanger.

In the above air conditioner, for example, the fourth pipe has an inlet portion located at one end of the third heat exchanger and an outlet portion located at the other end of the third heat exchanger, the outlet portion being closer to the second inlet than the inlet portion. The inner diameter of the outlet portion is larger than the inner diameter of the inlet portion.

The above air conditioner allows, for example, to reduce the amount of refrigerant used.

FIG. 1 is a refrigerant system diagram that schematically shows an air conditioner during heating operation according to one embodiment. FIG. 2 is a refrigerant system diagram that schematically shows the air conditioner of the above embodiment during cooling operation. FIG. 3 is a cross-sectional view schematically showing the ejector of the embodiment. FIG. 4 is a block diagram showing the functional configuration of the air conditioner of the above embodiment. FIG. 5 is a flowchart showing an example of heating operation control of the air conditioner of the above embodiment. FIG. 6 is a flowchart showing an example of cooling operation control of the air conditioner of the above embodiment. FIG. 7 is a block diagram showing an example of the hardware configuration of the control device of the above embodiment.

One embodiment will be described below with reference to Figures 1 to 7. Note that in this specification, components according to the embodiment and descriptions of those components may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. Components may also be identified by names different from those used in this specification. Furthermore, components may also be described using expressions different from those used in this specification.

Figure 1 is a refrigerant system diagram that schematically illustrates an air conditioner 10 during heating operation according to one embodiment. The air conditioner 10 is, for example, a home air conditioner. However, the air conditioner 10 is not limited to this example and may be another type of air conditioner, such as a commercial air conditioner.

As shown in FIG. 1, the air conditioner 10 has an outdoor unit 11, an indoor unit 12, refrigerant piping 13, and a control device 14. The outdoor unit 11 is, for example, located outdoors. The indoor unit 12 is, for example, located indoors.

The air conditioner 10 has a refrigeration cycle in which an outdoor unit 11 and an indoor unit 12 are connected by refrigerant piping 13. Refrigerant flows between the outdoor unit 11 and the indoor unit 12 through the refrigerant piping 13. The outdoor unit 11 and the indoor unit 12 are also electrically connected to each other, for example, by electrical wiring.

The outdoor unit 11 has an outdoor heat exchanger 21, an outdoor blower fan 22, a compressor 23, an accumulator 24, a first four-way valve 25, a second four-way valve 26, an ejector 27, a gas-liquid separator 28, a first expansion valve 31, a second expansion valve 32, a first valve 33, a second valve 34, a check valve 35, an intermediate heat exchanger 37, a heat storage material 38, and multiple temperature sensors 41, 42, 43, 44, 45, and 46. The intermediate heat exchanger 37 is an example of a third heat exchanger. The temperature sensor 41 is an example of a first sensor. The temperature sensor 42 is an example of a second sensor. The indoor unit 12 has an indoor heat exchanger 51, an indoor blower fan 52, and a temperature sensor 53.

The refrigerant piping 13 is a pipe made of a metal such as copper or aluminum. The refrigerant piping 13 includes a first pipe 61, a second pipe 62, a third pipe 63, and a fourth pipe 64.

The first pipe 61 connects the outdoor heat exchanger 21 and the indoor heat exchanger 51. The compressor 23, accumulator 24, and first four-way valve 25 are provided on the first pipe 61. The second pipe 62 connects the indoor heat exchanger 51 and the outdoor heat exchanger 21. The second four-way valve 26, ejector 27, gas-liquid separator 28, and second expansion valve 32 are provided on the second pipe 62.

The third pipe 63 connects the first pipe 61 and the second pipe 62. The first valve 33, the second valve 34, and the check valve 35 are provided on the third pipe 63. One end 64a of the fourth pipe 64 is connected to the ejector 27. The other end 64b of the fourth pipe 64 is connected to the gas-liquid separator 28. The first expansion valve 31 is provided on the fourth pipe 64.

During heating operation, the refrigerant flows through the first pipe 61 from the outdoor heat exchanger 21 to the indoor heat exchanger 51, and then flows through the second pipe 62 from the indoor heat exchanger 51 to the outdoor heat exchanger 21. The arrows in Figure 1 indicate the flow of refrigerant during heating operation.

Figure 2 is a refrigerant system diagram that schematically illustrates the air conditioner 10 during cooling operation in this embodiment. As shown in Figure 2, during cooling operation, the refrigerant flows through the first pipe 61 from the indoor heat exchanger 51 to the outdoor heat exchanger 21, and then flows through the second pipe 62 from the outdoor heat exchanger 21 to the indoor heat exchanger 51. The arrows in Figure 2 indicate the flow of refrigerant during cooling operation.

The outdoor heat exchanger 21 of the outdoor unit 11 acts as an evaporator E to absorb heat from the refrigerant, or as a condenser C to release heat from the refrigerant, depending on the direction of refrigerant flow. The evaporator E is an example of a first heat exchanger. The condenser C is an example of a second heat exchanger. The outdoor unit 11 of this embodiment has a small outdoor heat exchanger 21. For example, the volume of the outdoor heat exchanger 21 is smaller than the volume of the indoor heat exchanger 51. However, the volume of the outdoor heat exchanger 21 is not limited to this example.

The outdoor blower fan 22 generates an airflow that passes through the outdoor heat exchanger 21, promoting heat exchange between the refrigerant and the air in the outdoor heat exchanger 21. In other words, the outdoor blower fan 22 generates an airflow that exchanges heat with the outdoor heat exchanger 21.

The compressor 23 has an intake port 23a and a discharge port 23b. The compressor 23 draws in refrigerant through the intake port 23a and discharges the compressed refrigerant from the discharge port 23b. In this way, the compressor 23 compresses the refrigerant in the refrigeration cycle and causes the refrigerant to circulate.

The accumulator 24 is connected to the suction port 23a of the compressor 23. The accumulator 24 separates the gaseous refrigerant from the liquid refrigerant. This allows the compressor 23 to draw the gaseous refrigerant that has passed through the accumulator 24 through the suction port 23a. The accumulator 24 is configured integrally with the compressor 23, so it can serve as the suction port of the compressor 23.

The first four-way valve 25 is connected to the outdoor heat exchanger 21, the indoor heat exchanger 51, the discharge port 23b of the compressor 23, and the accumulator 24 (the suction port 23a of the compressor 23). The first four-way valve 25 switches the flow paths connected to the outdoor heat exchanger 21, the indoor heat exchanger 51, the discharge port 23b of the compressor 23, and the accumulator 24 between heating and cooling operation, changing the direction of refrigerant flow.

The indoor heat exchanger 51 of the indoor unit 12 absorbs heat as an evaporator E or releases heat as a condenser C, depending on the direction of refrigerant flow. The indoor blower fan 52 generates an airflow that passes through the indoor heat exchanger 51, promoting heat exchange between the indoor heat exchanger 51 and the air. In other words, the indoor blower fan 52 generates an airflow that exchanges heat with the indoor heat exchanger 51.

As shown in FIG. 1, during heating operation, the first four-way valve 25 connects the outdoor heat exchanger 21 (evaporator E) to the accumulator 24. Furthermore, during heating operation, the first four-way valve 25 connects the indoor heat exchanger 51 (condenser C) to the discharge port 23b of the compressor 23. As a result, the refrigerant compressed by the compressor 23 flows to the condenser C, and the refrigerant evaporated by the evaporator E flows to the accumulator 24.

As shown in FIG. 2, during cooling operation, the first four-way valve 25 connects the outdoor heat exchanger 21 (condenser C) to the discharge port 23b of the compressor 23. Furthermore, during cooling operation, the first four-way valve 25 connects the indoor heat exchanger 51 (evaporator E) to the accumulator 24. As a result, the refrigerant compressed by the compressor 23 flows to the condenser C, and the refrigerant evaporated by the evaporator E flows to the accumulator 24.

The second four-way valve 26 divides the second piping 62 into an outdoor piping 71, an indoor piping 72, and an intermediate piping 73. In other words, the second piping 62 has the outdoor piping 71, the indoor piping 72, and the intermediate piping 73. Note that the second piping 62 may also have other sections.

The outdoor piping 71 connects the outdoor heat exchanger 21 and the second four-way valve 26. The indoor piping 72 connects the second four-way valve 26 and the indoor heat exchanger 51. The ejector 27, gas-liquid separator 28, and second expansion valve 32 are provided in the intermediate piping 73. The intermediate piping 73 has an upstream end 73a and a downstream end 73b. The upstream end 73a and the downstream end 73b are connected to the second four-way valve 26.

As shown in FIG. 1, during heating operation, the second four-way valve 26 connects the outdoor pipe 71 to the downstream end 73b of the intermediate pipe 73, and connects the indoor pipe 72 to the upstream end 73a of the intermediate pipe 73. Therefore, refrigerant condensed in the indoor heat exchanger 51 (condenser C) flows from the indoor pipe 72 to the upstream end 73a and from the downstream end 73b to the outdoor pipe 71.

As shown in FIG. 2, during cooling operation, the second four-way valve 26 connects the outdoor pipe 71 to the upstream end 73a and the indoor pipe 72 to the downstream end 73b. Therefore, refrigerant condensed in the outdoor heat exchanger 21 (condenser C) flows from the outdoor pipe 71 to the upstream end 73a and from the downstream end 73b to the indoor pipe 72.

The second four-way valve 26 connects the upstream end 73a to the condenser C and the downstream end 73b to the evaporator E in both heating and cooling operation. Therefore, in both heating and cooling operation, the refrigerant in the intermediate pipe 73 flows from the upstream end 73a to the downstream end 73b.

Figure 3 is a cross-sectional view schematically showing the ejector 27 of this embodiment. As shown in Figure 3, the ejector 27 has a simple structure, making it easy to maintain and install in the air conditioner 10. Note that the structure of the ejector 27 is not limited to the example shown in Figure 3. The ejector 27 is provided with a first inlet 81, a second inlet 82, an outlet 83, a nozzle portion 84, a suction portion 85, a mixing portion 86, and a diffuser portion 87.

As shown in FIG. 1, the first inlet 81 is connected to the second four-way valve 26 via the upstream end 73a of the intermediate pipe 73. Therefore, the first inlet 81 is connected to the condenser C via the second pipe 62.

The second inlet 82 is connected to the end 64a of the fourth pipe 64. The fourth pipe 64 connects the gas-liquid separator 28 to the second inlet 82. The outlet 83 is connected to the second four-way valve 26 via the downstream end 73b of the intermediate pipe 73. Therefore, the outlet 83 is connected to the evaporator E via the second pipe 62.

The ejector 27 mixes the refrigerant supplied to the first inlet 81 with the refrigerant supplied to the second inlet 82, increases the pressure, and releases it from the outlet 83. As a result, the ejector 27 can supply the refrigerant from the outlet 83 through the second pipe 62 to the evaporator E.

As shown in FIG. 3, the nozzle portion 84 is provided between the first inlet 81 and the mixing portion 86. The nozzle portion 84 is a flow path having a portion that tapers toward the mixing portion 86. The nozzle portion 84 reduces the pressure of the refrigerant that has flowed into the first inlet 81, expands it, and sprays it into the mixing portion 86. Because the pressure near the outlet of the nozzle portion 84 is low, the first inlet 81 connected to the nozzle portion 84 can draw in the refrigerant.

The suction section 85 is provided between the second inlet 82 and the mixing section 86. The suction section 85 is provided around the nozzle section 84 and is a substantially cylindrical flow path with a portion tapering toward the mixing section 86. The suction section 85 decompresses and expands the refrigerant that has flowed into the second inlet 82, and then sprays it into the mixing section 86. Because the pressure near the outlet of the suction section 85 is low, the second inlet 82 connected to the suction section 85 can suck in the refrigerant.

The mixing section 86 is provided between the nozzle section 84 and the suction section 85 and the diffuser section 87. In the mixing section 86, the ejector 27 mixes the refrigerant sprayed from the suction section 85 with the refrigerant sprayed from the nozzle section 84.

The diffuser section 87 is provided between the mixing section 86 and the outlet 83. The diffuser section 87 is a flow path that has a portion that expands toward the outlet 83. The refrigerant mixed in the mixing section 86 is decelerated and pressurized in the diffuser section 87 and released from the outlet 83.

The ejector 27 has a solenoid valve 88. The solenoid valve 88 can open and close the first inlet 81. Note that in FIG. 3, the solenoid valve 88 is located outside the nozzle portion 84, but the solenoid valve 88 may be provided inside the nozzle portion 84 or in another location. The solenoid valve 88 adjusts the amount of refrigerant supplied to the first inlet 81 by controlling its opening degree. Note that the ejector 27 may also have a solenoid valve that can adjust the amount of refrigerant supplied to the second inlet 82.

As shown in FIG. 1, the gas-liquid separator 28 is provided between the second four-way valve 26 and the first inlet 81. In other words, the gas-liquid separator 28 is provided in the second pipe 62 between the condenser C and the first inlet 81.

The gas-liquid separator 28 is, for example, a surface tension gas-liquid separator. However, the gas-liquid separator 28 may be another type of gas-liquid separator. The gas-liquid separator 28 is provided with a refrigerant inlet 28a, a gas outlet 28b, and a liquid outlet 28c.

The refrigerant inlet 28a is connected to the second four-way valve 26 via the upstream end 73a of the intermediate pipe 73. Therefore, the refrigerant inlet 28a is connected to the condenser C via the second pipe 62. The refrigerant condensed in the condenser C flows from the refrigerant inlet 28a into the gas-liquid separator 28. The refrigerant passing through the refrigerant inlet 28a may contain gas.

The gas-liquid separator 28 separates the refrigerant supplied from the condenser C to the refrigerant inlet 28a into a liquid refrigerant and a two-phase gas-liquid refrigerant. A two-phase gas-liquid refrigerant is an example of a refrigerant that contains gas. However, the gas-liquid separator 28 may also separate the refrigerant into a liquid refrigerant and a gas refrigerant.

The gas outlet 28b is connected to the first inlet 81 of the ejector 27 through the intermediate pipe 73. The liquid outlet 28c is connected to the end 64b of the fourth pipe 64. Therefore, the liquid outlet 28c is connected to the second inlet 82 via the fourth pipe 64.

The gas-liquid separator 28 distributes the separated refrigerant to the gas outlet 28b and the liquid outlet 28c. The gas-liquid separator 28 supplies the two-phase gas-liquid refrigerant from the gas outlet 28b via the second pipe 62 to the first inlet 81. The gas-liquid separator 28 distributes the liquid refrigerant from the liquid outlet 28c to the fourth pipe 64. In the fourth pipe 64, the refrigerant flows from one end 64b of the fourth pipe 64 (the liquid outlet 28c of the gas-liquid separator 28) to the other end 64a (the second inlet 82 of the ejector 27).

The first expansion valve 31 and the second expansion valve 32 are, for example, electromagnetic expansion valves. However, the first expansion valve 31 and the second expansion valve 32 may be other expansion valves. Furthermore, the outdoor unit 11 may omit the second expansion valve 32.

By controlling the opening degree, the first expansion valve 31 adjusts the amount of refrigerant flowing in the fourth pipe 64 from the liquid outlet 28c of the gas-liquid separator 28 to the second inlet 82 of the ejector 27. The second expansion valve 32 is located between the second four-way valve 26 and the gas-liquid separator 28. In other words, the second expansion valve 32 is provided in the second pipe 62 between the gas-liquid separator 28 and the condenser C. By controlling the opening degree, the second expansion valve 32 adjusts the amount of refrigerant flowing in the second pipe 62 from the condenser C to the refrigerant inlet 28a of the gas-liquid separator 28.

The third pipe 63 has a main pipe 90, a first inlet pipe 91, and a second inlet pipe 92. The third pipe 63 may also have other components. A check valve 35 is provided in the main pipe 90. A first valve 33 is provided in the first inlet pipe 91. A second valve 34 is provided in the second inlet pipe 92.

The main pipe 90 is connected to the intermediate pipe 73 between the refrigerant inlet 28a of the gas-liquid separator 28 and the second expansion valve 32. In other words, the third pipe 63 is connected to the second pipe 62 between the condenser C and the gas-liquid separator 28.

The first inlet pipe 91 is connected to the first pipe 61 between the first four-way valve 25 and the indoor heat exchanger 51. The second inlet pipe 92 is connected to the first pipe 61 between the first four-way valve 25 and the outdoor heat exchanger 21. The first inlet pipe 91 and the second inlet pipe 92 each connect the first pipe 61 and the main pipe 90.

The first valve 33 and the second valve 34 are, for example, solenoid valves. However, the first valve 33 and the second valve 34 may be other valves. The first valve 33 opens during heating operation and closes during cooling operation. The second valve 34 closes during heating operation and opens during cooling operation.

As shown in FIG. 1, during heating operation, the refrigerant discharged from the discharge port 23b of the compressor 23 flows through the first pipe 61 toward the indoor heat exchanger 51 (condenser C). A portion of the refrigerant flowing through the first pipe 61 passes through the first inlet pipe 91 and the main pipe 90 and is supplied to the intermediate pipe 73.

As shown in FIG. 2, during cooling operation, the refrigerant discharged from the discharge port 23b of the compressor 23 flows through the first pipe 61 toward the outdoor heat exchanger 21 (condenser C). A portion of the refrigerant flowing through the first pipe 61 passes through the second inlet pipe 92 and the main pipe 90 and is supplied to the intermediate pipe 73.

In both heating and cooling operation, the third pipe 63 is connected to the second pipe 62 between the condenser C and the gas-liquid separator 28, and is connected to the first pipe 61 between the discharge port 23b and the condenser C. Therefore, the third pipe 63 bypasses the condenser C and connects the first pipe 61 and the second pipe 62.

The check valve 35 allows refrigerant to pass through the third pipe 63 from the discharge port 23b of the compressor 23 toward the intermediate pipe 73. On the other hand, the check valve 35 blocks the flow of refrigerant from the intermediate pipe 73 toward the first pipe 61.

The intermediate heat exchanger 37 exchanges heat between the refrigerant flowing through the main pipe 90 of the third pipe 63 and the refrigerant flowing through the fourth pipe 64. The intermediate heat exchanger 37 is a double-pipe heat exchanger. For example, the fourth pipe 64 is located inside the main pipe 90, and the refrigerant flowing through the main pipe 90 exchanges heat with the refrigerant flowing through the fourth pipe 64 via the fourth pipe 64. That is, the intermediate heat exchanger 37 of this embodiment includes a portion of the main pipe 90 and a portion of the fourth pipe 64. Note that the intermediate heat exchanger 37 is not limited to this example. For example, the intermediate heat exchanger 37 may be another heat exchanger, such as a plate-type heat exchanger.

The intermediate heat exchanger 37 is located between the first expansion valve 31 and the second inlet 82 of the ejector 27. Therefore, the first expansion valve 31 is provided on the fourth pipe 64 between the liquid outlet 28c of the gas-liquid separator 28 and the intermediate heat exchanger 37.

The fourth pipe 64 has an inlet 64c and an outlet 64d. The inlet 64c is located at one end 37a of the intermediate heat exchanger 37. The outlet 64d is located at the other end 37b of the intermediate heat exchanger 37.

The refrigerant flows from the inlet 64c into a portion of the fourth pipe 64 included in the intermediate heat exchanger 37 and flows out from the outlet 64d. Therefore, the inlet 64c is located upstream of the outlet 64d and closer to the liquid outlet 28c of the gas-liquid separator 28 than the outlet 64d. The outlet 64d is located downstream of the inlet 64c and closer to the second inlet 82 of the ejector 27 than the inlet 64c.

The inner diameter of the fourth pipe 64 at the outlet 64d is larger than the inner diameter of the fourth pipe 64 at the inlet 64c. Furthermore, the inner diameter of the fourth pipe 64 between the inlet 64c and the outlet 64d is smaller than the inner diameter of the fourth pipe 64 at the inlet 64c and also smaller than the inner diameter of the fourth pipe 64 at the outlet 64d. Note that the inner diameter of the fourth pipe 64 is not limited to this example.

The heat storage material 38 is thermally connected to the intermediate heat exchanger 37. The heat storage material 38 includes, for example, a latent heat storage material filled in a block-shaped container. The latent heat storage material is, for example, calcium chloride. The heat storage material 38 may also include other latent heat storage materials.

The temperature sensor 41 measures the temperature of the refrigerant flowing through the fourth pipe 64 between the gas-liquid separator 28 and the intermediate heat exchanger 37. In this embodiment, the temperature sensor 41 is provided between the first expansion valve 31 and the intermediate heat exchanger 37. The temperature sensor 42 measures the temperature of the refrigerant flowing through the fourth pipe 64 between the intermediate heat exchanger 37 and the second inlet 82.

The temperature sensor 43 measures the temperature of the refrigerant flowing through the first pipe 61 between the intake port 23a of the compressor 23 and the evaporator E. In this embodiment, the temperature sensor 43 is provided between the accumulator 24 and the first four-way valve 25. The temperature sensor 44 measures the temperature of the refrigerant flowing through the outdoor heat exchanger 21. For example, the temperature sensor 44 is positioned at a position where the saturation temperature of the refrigerant flowing through the outdoor heat exchanger 21 can be obtained.

The temperature sensor 45 measures the temperature of the refrigerant flowing through the second pipe 62 between the second four-way valve 26 and the indoor heat exchanger 51. The temperature sensor 46 measures the temperature of the refrigerant flowing through the second pipe 62 between the gas-liquid separator 28 and the second expansion valve 32. In this embodiment, the temperature sensor 46 is provided between the second expansion valve 32 and the portion where the second pipe 62 and the third pipe 63 are connected.

The temperature sensor 47 measures the temperature of the refrigerant flowing through the second pipe 62 between the second four-way valve 26 and the outdoor heat exchanger 21. The temperature sensor 53 measures the temperature of the refrigerant flowing through the indoor heat exchanger 51. For example, the temperature sensor 53 is positioned at a position where the saturation temperature of the refrigerant flowing through the indoor heat exchanger 51 can be obtained.

The control device 14 includes, for example, an outdoor control device 14a and an indoor control device 14b. The outdoor control device 14a and the indoor control device 14b are electrically connected to each other via electrical wiring. At least one of the outdoor control device 14a and the indoor control device 14b is a computer including, for example, a control device such as a CPU (Central Processing Unit) or a microcontroller, and a storage device such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash memory. Note that the control device 14 is not limited to this example. For example, the control device 14 may include only one of the outdoor control device 14a and the indoor control device 14b.

The outdoor control device 14a controls the outdoor blower fan 22, compressor 23, first four-way valve 25, second four-way valve 26, first expansion valve 31, second expansion valve 32, first valve 33, second valve 34, and solenoid valve 88 of the ejector 27 of the outdoor unit 11. The indoor control device 14b controls the indoor blower fan 52 of the indoor unit 12.

The control device 14 controls the outdoor unit 11 and the indoor unit 12, causing the air conditioner 10 to perform cooling operation, heating operation, dehumidification operation, defrosting operation, and other operations. The indoor control device 14b may receive signals, for example, from a remote controller, or may receive signals from an information terminal such as a smartphone via a communication device.

As shown in FIG. 1, during heating operation, gaseous refrigerant discharged from the discharge port 23b of the compressor 23 is supplied to the indoor heat exchanger 51 (condenser C) through the first pipe 61. The refrigerant condensed in the condenser C is decompressed by the second expansion valve 32 and flows into the refrigerant inlet 28a of the gas-liquid separator 28.

The two-phase gas-liquid refrigerant is supplied from the gas outlet 28b of the gas-liquid separator 28 to the first inlet 81 of the ejector 27. The liquid refrigerant flows into the fourth pipe 64 from the liquid outlet 28c of the gas-liquid separator 28. In the fourth pipe 64, the liquid refrigerant is decompressed by the first expansion valve 31.

Meanwhile, a portion of the high-temperature, high-pressure refrigerant discharged from the discharge port 23b of the compressor 23 flows from the first inlet pipe 91 into the third pipe 63. The intermediate heat exchanger 37 exchanges heat between the high-temperature refrigerant flowing through the third pipe 63 and the liquid refrigerant flowing through the fourth pipe 64. As a result, the intermediate heat exchanger 37 partially evaporates the liquid refrigerant flowing through the fourth pipe 64, converting it into a two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant that has passed through the intermediate heat exchanger 37 flows from the fourth pipe 64 into the second inlet 82 of the ejector 27. The refrigerant that has passed through the third pipe 63 mixes with refrigerant decompressed by the second expansion valve 32 and flows into the refrigerant inlet 28a of the gas-liquid separator 28.

The ejector 27 mixes and pressurizes the two-phase gas-liquid refrigerant supplied to the first inlet 81 and the two-phase gas-liquid refrigerant supplied to the second inlet 82, and supplies the resulting mixture to the outdoor heat exchanger 21 (evaporator E) through the outlet 83. The refrigerant evaporated in the evaporator E passes through the accumulator 24 and flows into the suction port 23a of the compressor 23.

In this embodiment, the outdoor heat exchanger 21 is small. As a result, the total amount of refrigerant in the air conditioner 10 is small, and the degree of subcooling is likely to be small. However, by including an ejector 27, the air conditioner 10 of this embodiment can achieve high refrigeration capacity even with a small degree of subcooling.

As shown in FIG. 2, during cooling operation, gaseous refrigerant discharged from the discharge port 23b of the compressor 23 is supplied to the outdoor heat exchanger 21 (condenser C) through the first pipe 61. The movement of refrigerant from the condenser C to the indoor heat exchanger 51 (evaporator E) is substantially the same as the movement of refrigerant during heating operation. In addition, a portion of the high-temperature, high-pressure refrigerant discharged from the discharge port 23b of the compressor 23 flows from the second inlet pipe 92 into the third pipe 63. The movement of refrigerant from the third pipe 63 to the refrigerant inlet 28a of the gas-liquid separator 28 is substantially the same as the movement of refrigerant during heating operation.

The ejector 27 can operate with two-phase gas-liquid refrigerant. Therefore, even if the small outdoor heat exchanger 21 (condenser C) does not fully liquefy the refrigerant, the ejector 27 can operate sufficiently with two-phase gas-liquid refrigerant, thereby preventing a decrease in the refrigeration capacity of the refrigeration cycle in the air conditioner 10.

Figure 4 is a block diagram showing the functional configuration of the air conditioner 10 of this embodiment. As shown in Figure 4, the air conditioner 10 of this embodiment further includes an outdoor fan drive circuit 101, an indoor fan drive circuit 102, an inverter circuit 103, and multiple valve drive circuits 111-117.

The outdoor fan drive circuit 101 is a drive circuit for the outdoor blower fan 22. The indoor fan drive circuit 102 is a drive circuit for the indoor blower fan 52. The inverter circuit 103 inverter-controls the compressor 23 and changes the operating frequency of the compressor 23. The inverter circuit 103 is, for example, a PAM (pulse amplitude modulation) inverter circuit. Note that the compressor 23 may also be controlled by a method other than inverter control.

Valve drive circuit 111 is the drive circuit for the first four-way valve 25. Valve drive circuit 112 is the drive circuit for the second four-way valve 26. Valve drive circuit 113 is the drive circuit for the first expansion valve 31. Valve drive circuit 114 is the drive circuit for the second expansion valve 32.

The valve drive circuit 115 is the drive circuit for the solenoid valve 88 of the ejector 27. The valve drive circuit 116 is the drive circuit for the first valve 33. The valve drive circuit 117 is the drive circuit for the second valve 34.

The control device 14 is connected to multiple temperature sensors 41-47 and temperature sensor 53, the outdoor fan drive circuit 101, the indoor fan drive circuit 102, the inverter circuit 103, and multiple valve drive circuits 111-117. The control device 14 includes a temperature acquisition unit 121, an operation switching unit 122, an outdoor fan control unit 123, an indoor fan control unit 124, a compressor control unit 125, and a valve control unit 126.

The temperature acquisition unit 121 acquires refrigerant temperature measurement results from multiple temperature sensors 41-47 and temperature sensor 53. For example, the temperature acquisition unit 121 calculates the refrigerant temperature from the output signals of temperature sensors 41-47 and temperature sensor 53.

The operation switching unit 122 switches the air conditioner 10 between cooling operation, heating operation, dehumidification operation, and defrosting operation. Note that the operation switching unit 122 may also switch the operation of the air conditioner 10 to another operating mode.

The outdoor fan control unit 123 controls the outdoor blower fan 22. For example, the outdoor fan control unit 123 controls the outdoor fan drive circuit 101 to control the rotation speed of the motor of the outdoor blower fan 22.

The indoor fan control unit 124 controls the indoor blower fan 52. For example, the indoor fan control unit 124 controls the rotation speed of the motor of the indoor blower fan 52 by controlling the indoor fan drive circuit 102.

The compressor control unit 125 controls the compressor 23. For example, the compressor control unit 125 controls the inverter circuit 103 to control the operating frequency of the compressor 23 through inverter control.

The valve control unit 126 controls the first four-way valve 25, the second four-way valve 26, the first expansion valve 31, the second expansion valve 32, the first valve 33, the second valve 34, and the solenoid valve 88. By controlling the valve drive circuits 111 and 112, the valve control unit 126 drives the actuators of the first four-way valve 25 and the second four-way valve 26, causing the first four-way valve 25 and the second four-way valve 26 to change the direction of refrigerant flow.

The valve control unit 126 controls the valve drive circuits 113-115 to change the opening degrees of the first expansion valve 31, the second expansion valve 32, and the solenoid valve 88. Furthermore, the valve control unit 126 controls the valve drive circuits 116 and 117 to open and close the first valve 33 and the second valve 34.

The heating operation control and cooling operation control of the air conditioner 10 of this embodiment will be described below. As mentioned above, the air conditioner 10 is not limited to heating operation and cooling operation, and can also perform other operations such as dehumidification operation and defrosting operation. Furthermore, the heating operation control and cooling operation control of the air conditioner 10 are not limited to the examples described below.

Figure 5 is a flowchart showing an example of heating operation control of the air conditioner 10 of this embodiment. For example, if the air conditioner 10 is started and heating operation begins simultaneously, the outdoor blower fan 22, compressor 23, and indoor blower fan 52 are stopped. In this case, the outdoor fan control unit 123, indoor fan control unit 124, and compressor control unit 125 start the outdoor blower fan 22, compressor 23, and indoor blower fan 52 when heating operation begins.

As shown in FIG. 5, when heating operation is started, the valve control unit 126 controls the valve drive circuits 111, 112 to switch the direction of refrigerant flow through the first four-way valve 25 and the second four-way valve 26 to the heating operation direction (S101). As a result, as shown in FIG. 1, the indoor heat exchanger 51 is connected to the discharge port 23b of the compressor 23, and the outdoor heat exchanger 21 is connected to the accumulator 24 (suction port 23a of the compressor 23). Furthermore, the outdoor heat exchanger 21 is connected to the outlet 83 of the ejector 27, and the indoor heat exchanger 51 is connected to the second expansion valve 32.

Next, as shown in FIG. 5, the valve control unit 126 controls the first valve 33 and the second valve 34 to open the first valve 33 and close the second valve 34 (S102). As a result, the second valve 34 blocks the flow of refrigerant through the second inlet pipe 92. Meanwhile, the refrigerant discharged from the discharge port 23b of the compressor 23 flows from the first inlet pipe 91 into the third pipe 63.

Next, the operation switching unit 122 determines whether to end the heating operation (S103). For example, if the indoor control device 14b receives a stop signal or a signal to switch to another operation from the remote controller, the operation switching unit 122 determines that the heating operation should be ended (S103: Yes) and ends the heating operation.

On the other hand, if the heating operation has not ended (S103: No), the valve control unit 126 determines whether the temperatures TN1 and TN2 are approximately 3.5°C (S104). For example, the temperature acquisition unit 121 acquires the temperature TN1 of the refrigerant between the first expansion valve 31 and the intermediate heat exchanger 37 from the temperature sensor 41. Furthermore, the temperature acquisition unit 121 acquires the temperature TN2 of the refrigerant between the intermediate heat exchanger 37 and the second inlet 82 of the ejector 27 from the temperature sensor 42. The valve control unit 126 determines whether each of the temperatures TN1 and TN2 is within the range of 3.5±0.5°C. Note that the determination in S104 is not limited to this example.

By setting the temperature TN1 to approximately 3.5°C, the pressure P1 of the refrigerant flowing into the intermediate heat exchanger 37 in the fourth pipe 64 becomes approximately 0.9 MPa. Furthermore, by setting the temperature TN2 to approximately 3.5°C, the pressure P2 of the refrigerant supplied from the intermediate heat exchanger 37 to the second inlet 82 of the ejector 27 also becomes approximately 0.9 MPa.

When pressures P1 and P2 are close to 0.9 MPa and are approximately equal to or higher than pressure P1, the capacity of the ejector 27 increases. Therefore, by setting temperatures TN1 and TN2 to approximately 3.5°C, the refrigeration capacity of the outdoor heat exchanger 21 (evaporator E) can be improved.

If temperatures TN1 and TN2 are not approximately 3.5°C (S104: No), the valve control unit 126 controls the first expansion valve 31 to adjust the opening degree of the first expansion valve 31 (S105). The valve control unit 126 adjusts the opening degree of the first expansion valve 31 so that temperatures TN1 and TN2 are approximately 3.5°C. In other words, the valve control unit 126 controls the opening degree of the first expansion valve 31 based on the measurement results (temperatures TN1 and TN2) of the temperature sensors 41 and 42.

If temperatures TN1 and TN2 are approximately 3.5°C in S104 (S104: Yes), or if the opening degree of the first expansion valve 31 is adjusted in S105, the valve control unit 126 determines whether the difference between temperature SU and temperature TC1 (degree of superheat) is approximately 1°C (S106).

For example, the temperature acquisition unit 121 acquires the refrigerant temperature SU between the accumulator 24 and the outdoor heat exchanger 21 (evaporator E) from the temperature sensor 43. Furthermore, the temperature acquisition unit 121 acquires the refrigerant temperature TC1 in the outdoor heat exchanger 21 from the temperature sensor 44. The valve control unit 126 determines whether the degree of superheat (SU-TC1) is within the range of 1±0.5°C. Note that the determination in S106 is not limited to this example.

If the degree of superheat (SU-TC1) is not approximately 1°C (S106: No), the valve control unit 126 controls the solenoid valve 88 of the ejector 27 to adjust the opening degree of the solenoid valve 88 (S107). The valve control unit 126 adjusts the opening degree of the solenoid valve 88 so that the degree of superheat (SU-TC1) is approximately 1°C.

If the degree of superheat (SU-TC1) is approximately 1°C in S106 (S106: Yes), or if the opening of the solenoid valve 88 is adjusted in S107, the valve control unit 126 determines whether the difference between temperature TC3 and temperature TC4 is approximately 5°C (S108).

For example, the temperature acquisition unit 121 acquires the refrigerant temperature TC3 between the indoor heat exchanger 51 (condenser C) and the second expansion valve 32 from the temperature sensor 45. Furthermore, the temperature acquisition unit 121 acquires the refrigerant temperature TC4 between the second expansion valve 32 and the gas-liquid separator 28 from the temperature sensor 46. The valve control unit 126 determines whether the temperature difference (TC3 - TC4) is within the range of 5 ± 0.5°C. Note that the determination in S108 is not limited to this example.

If the temperature difference (TC3 - TC4) is not approximately 5°C (S108: No), the valve control unit 126 controls the second expansion valve 32 to adjust the opening degree of the second expansion valve 32 (S109). The valve control unit 126 adjusts the opening degree of the second expansion valve 32 so that the temperature difference (TC3 - TC4) is approximately 5°C.

For example, when high-pressure refrigerant flows into the gas-liquid separator 28, the liquid refrigerant and the two-phase gas-liquid refrigerant may not be sufficiently separated in the gas-liquid separator 28. However, by setting the temperature difference (TC3 - TC4) to approximately 5°C, the second expansion valve 32 sufficiently reduces the refrigerant pressure. As a result, the liquid refrigerant and the two-phase gas-liquid refrigerant are sufficiently separated in the gas-liquid separator 28.

If the temperature difference (TC3 - TC4) is approximately 5°C in S108 (S108: Yes), or if the opening of the second expansion valve 32 is adjusted in S109, the process returns to S103, and the operation switching unit 122 again determines whether to end the heating operation. S103 to S109 are repeated until the heating operation ends.

The control device 14 is not limited to the above control and may perform other control. For example, the indoor fan control unit 124 may control the indoor blower fan 52 so that the temperature difference (degree of subcooling) between the refrigerant temperature TE1 in the indoor heat exchanger 51 (condenser C) obtained from the temperature sensor 53 and the refrigerant temperature TC3 obtained from the temperature sensor 45 is approximately 2°C.

In the heating operation of this embodiment, the ejector 27 increases the pressure of the refrigerant. That is, in the air conditioner 10 of this embodiment, not only the compressor 23 but also the ejector 27 increases the pressure of the refrigerant. As a result, the air conditioner 10 can reduce the workload and power consumption required for the compressor 23 to increase the pressure of the refrigerant to the desired condensation pressure.

Furthermore, during heating operation in this embodiment, the refrigerant discharged from the outlet 83 of the ejector 27 is supplied directly to the outdoor heat exchanger 21 without passing through an expansion valve or gas-liquid separator. This allows the air conditioner 10 of this embodiment to suppress pressure loss caused by the expansion valve or gas-liquid separator, and allows sufficient refrigerant to be returned to the suction port 23a of the compressor 23.

In this embodiment, the refrigeration capacity of the outdoor heat exchanger 21 is improved by supplying the refrigerant pressurized by the ejector 27 to the outdoor heat exchanger 21. Therefore, the outdoor heat exchanger 21, which serves as an evaporator E, can sufficiently exchange heat between the refrigerant and the outside air even when the refrigerant temperature is relatively high.

If frost forms on the outdoor heat exchanger 21, the valve control unit 126 closes the first expansion valve 31 and maximizes the opening of the second expansion valve 32 and the solenoid valve 88. This allows relatively high-temperature refrigerant to pass through the second expansion valve 32, gas-liquid separator 28, and ejector 27 and flow into the outdoor heat exchanger 21. This allows the high-temperature refrigerant to melt the frost on the surface of the outdoor heat exchanger 21.

Figure 6 is a flowchart showing an example of cooling operation control of the air conditioner 10 of this embodiment. For example, if the air conditioner 10 is started and the cooling operation begins simultaneously, the outdoor fan control unit 123, indoor fan control unit 124, and compressor control unit 125 start the outdoor blower fan 22, compressor 23, and indoor blower fan 52 at the start of the cooling operation.

As shown in FIG. 6, when cooling operation is started, the valve control unit 126 controls the valve drive circuits 111, 112 to switch the direction of refrigerant flow through the first four-way valve 25 and the second four-way valve 26 to the direction of cooling operation (S201). As a result, as shown in FIG. 2, the outdoor heat exchanger 21 is connected to the discharge port 23b of the compressor 23, and the indoor heat exchanger 51 is connected to the accumulator 24 (suction port 23a of the compressor 23). Furthermore, the indoor heat exchanger 51 is connected to the outlet 83 of the ejector 27, and the outdoor heat exchanger 21 is connected to the second expansion valve 32.

Next, as shown in FIG. 6, the valve control unit 126 controls the first valve 33 and the second valve 34 to close the first valve 33 and open the second valve 34 (S202). As a result, the first valve 33 blocks the flow of refrigerant through the first inlet pipe 91. Meanwhile, the refrigerant discharged from the discharge port 23b of the compressor 23 flows into the third pipe 63 through the second inlet pipe 92.

Next, the operation switching unit 122 determines whether or not to terminate the cooling operation (S203). As in S103, if the operation switching unit 122 determines that the cooling operation should be terminated (S203: Yes), the operation switching unit 122 terminates the cooling operation.

On the other hand, if the cooling operation has not ended (S203: No), the valve control unit 126 determines whether the temperatures TN1 and TN2 are approximately 3.5°C (S204). If the temperature TN2 is not approximately 3.5°C (S204: No), the valve control unit 126 controls the first expansion valve 31 to adjust the opening degree of the first expansion valve 31 (S205). S204 and S205 are substantially the same as S104 and S105.

If temperatures TN1 and TN2 are approximately 3.5°C in S204 (S204: Yes), or if the opening degree of the first expansion valve 31 is adjusted in S205, the valve control unit 126 determines whether the difference between temperature SU and temperature TE1 (degree of superheat) is 2°C or more (S206).

For example, the temperature acquisition unit 121 acquires the temperature SU from the temperature sensor 43. Furthermore, the temperature acquisition unit 121 acquires the temperature TE1 of the refrigerant in the indoor heat exchanger 51 from the temperature sensor 53. The valve control unit 126 determines whether the degree of superheat (SU-TE1) is 2°C or higher. Note that the determination in S206 is not limited to this example.

If the degree of superheat (SU-TE1) is lower than 2°C (S206: No), the valve control unit 126 controls the solenoid valve 88 of the ejector 27 to adjust the opening degree of the solenoid valve 88 (S207). The valve control unit 126 adjusts the opening degree of the solenoid valve 88 so that the degree of superheat (SU-TE1) is 2°C or higher.

If the degree of superheat (SU-TE1) is 2°C or higher in S206 (S206: Yes), or if the opening of the solenoid valve 88 is adjusted in S207, the valve control unit 126 determines whether the difference between the temperature TC3 and the temperature TC4 is approximately 5°C (S208). If the temperature difference (TC3-TC4) is not approximately 5°C (S208: No), the valve control unit 126 controls the second expansion valve 32 to adjust the opening of the second expansion valve 32 (S209). S208 and S209 are substantially the same as S108 and S109.

If the temperature difference (TC3 - TC4) is approximately 5°C in S208 (S208: Yes), or if the opening degree of the second expansion valve 32 is adjusted in S209, the valve control unit 126 determines whether the difference between temperature TC2 and temperature TC1 (degree of subcooling) is lower than -5°C (S210).

For example, the temperature acquisition unit 121 acquires the refrigerant temperature TC1 in the outdoor heat exchanger 21 from the temperature sensor 44. Furthermore, the temperature acquisition unit 121 acquires the refrigerant temperature TC2 between the outdoor heat exchanger 21 (condenser C) and the second expansion valve 32 from the temperature sensor 47. The valve control unit 126 determines whether the degree of subcooling (TC2 - TC1) is lower than -5°C. Note that the determination in S210 is not limited to this example.

If the degree of subcooling (TC2 - TC1) is -5°C or higher (S210: No), the outdoor fan control unit 123 controls the outdoor blower fan 22 to adjust the rotation speed of the outdoor blower fan 22 (S211). The outdoor fan control unit 123 adjusts the rotation speed of the outdoor blower fan 22 so that the degree of subcooling (TC2 - TC1) is lower than -5°C. Setting the degree of subcooling (TC2 - TC1) to be lower than -5°C prevents a decrease in the capacity of the indoor heat exchanger 51 (evaporator E).

If the degree of subcooling (TC2 - TC1) is lower than -5°C in S210 (S210: Yes), or if the rotation speed of the outdoor blower fan 22 is adjusted in S211, the process returns to S203, where the operation switching unit 122 again determines whether to end the cooling operation. S203 to S211 are repeated until the cooling operation ends.

Figure 7 is a block diagram showing an example of the hardware configuration of the control device 14 of this embodiment. The control device 14 is realized, for example, by a computer 140 with the hardware configuration shown in Figure 7.

The computer 140 includes, for example, a CPU 141, a ROM 142, a RAM 143, a storage device 144, and an interface (I/F) 146. The CPU 141, ROM 142, RAM 143, storage device 144, and I/F 146 are connected via a bus.

The CPU 141 loads programs stored in the storage device 144 into the RAM 143 and executes them, controlling each component to perform input and output and processing data. The ROM 142 stores a start program that reads the operating system startup program from the storage device 144 into the RAM 143.

Storage device 144 is, for example, a flash memory. Storage device 144 stores an operating system, application programs, and data. These programs are distributed as installable or executable files recorded on computer-readable storage media. The programs may also be distributed by downloading them from a server.

I/F 146 is an interface device for connecting to, for example, temperature sensors 41-47, temperature sensor 53, outdoor fan drive circuit 101, indoor fan drive circuit 102, inverter circuit 103, and valve drive circuits 111-117.

The program executed by the computer 140 of this embodiment can be provided as an installable or executable file recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, or DVD.

The program executed by the computer 140 of this embodiment may also be configured to be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. The program executed by the computer 140 of this embodiment may also be configured to be provided or distributed via a network such as the Internet. The program of this embodiment may also be configured to be provided by being pre-installed in ROM 142 or the like.

The program for causing the computer 140 to function as the control device 14 is modularly configured, including a temperature acquisition module, an operation switching module, an outdoor fan control module, an indoor fan control module, a compressor control module, and a valve control module. In terms of actual hardware, the computer 140 loads each module into the main memory device (RAM 143) by having the processor (CPU 141) read and execute the program from a storage medium (such as the storage device 144). As a result, the processor (CPU 141) functions as the temperature acquisition unit 121, operation switching unit 122, outdoor fan control unit 123, indoor fan control unit 124, compressor control unit 125, and valve control unit 126 shown in FIG. 4 . Note that the computer 140 may be configured such that some or all of the components of the temperature acquisition unit 121, operation switching unit 122, outdoor fan control unit 123, indoor fan control unit 124, compressor control unit 125, and valve control unit 126 are implemented by hardware.

In the air conditioner 10 according to the embodiment described above, the ejector 27 provided on the second pipe 62 is provided with an outlet 83 connected to the evaporator E via the second pipe 62, a first inlet 81 connected to the condenser C via the second pipe 62, and a second inlet 82. The ejector 27 mixes the refrigerant supplied to the first inlet 81 with the refrigerant supplied to the second inlet 82, increases the pressure of the refrigerant, and supplies it to the evaporator E from the outlet 83. This allows the air conditioner 10 to improve its refrigeration capacity relative to the amount of power consumed and increase the efficiency of the refrigeration cycle. The gas-liquid separator 28 is provided on the second pipe 62 between the condenser C and the first inlet 81. The gas-liquid separator 28 separates the refrigerant supplied from the condenser C into liquid refrigerant and refrigerant containing gas, and supplies the refrigerant containing gas to the first inlet 81 via the second pipe 62. The third pipe 63 is connected to the second pipe 62 between the condenser C and the gas-liquid separator 28, and is connected to the first pipe 61 between the discharge port 23b and the condenser C. Therefore, the high-temperature, high-pressure refrigerant compressed by the compressor 23 is supplied to the gas-liquid separator 28 through the third pipe 63. The fourth pipe 64 connects the gas-liquid separator 28 to the second inlet 82, and the liquid refrigerant is distributed from the gas-liquid separator 28. That is, the liquid refrigerant flows through the fourth pipe 64 from the gas-liquid separator 28 toward the second inlet 82. The intermediate heat exchanger 37 exchanges heat between the refrigerant flowing through the third pipe 63 and the refrigerant flowing through the fourth pipe 64. As a result, the liquid refrigerant flowing through the fourth pipe 64 is partially or completely vaporized by the heat exchange. In other words, the liquid refrigerant flowing through the fourth pipe 64 is at least partially vaporized by the heat exchange. Then, gaseous refrigerant is supplied to both the first inlet 81 and the second inlet 82 of the ejector 27, and thus the gaseous refrigerant is supplied from the ejector 27 to the evaporator E. In this way, because the ejector 27 is supplied with gaseous refrigerant, there is no need to fully liquefy the refrigerant using the condenser C, and the condenser C can be made smaller. This allows for a reduction in the amount of refrigerant in the air conditioner 10.

Furthermore, for example, when the room temperature approaches the set temperature during cooling operation, the cooling operation may be stopped. When the cooling operation is stopped, refrigerant may move from the outdoor heat exchanger 21 to the indoor heat exchanger 51. This may cause the temperature of the indoor heat exchanger 51 to rise. This results in energy loss in the air conditioner 10. In particular, when the cooling operation is stopped and restarted intermittently, the energy loss of the air conditioner 10 increases. However, the air conditioner 10 of this embodiment reduces the amount of refrigerant, thereby preventing the indoor heat exchanger 51 from overcooling the air and thereby preventing the cooling operation from stopping even when the room temperature approaches the set temperature. Furthermore, even when the cooling operation is stopped, the amount of refrigerant moving when the cooling operation is stopped is reduced, thereby preventing the temperature of the indoor heat exchanger 51 from rising when the cooling operation is stopped. Therefore, the air conditioner 10 can reduce energy loss and improve energy-saving performance. For example, the air conditioner 10 can improve an index such as a _CD value (coefficient of degradation).

The first expansion valve 31 is provided on the fourth pipe 64 between the gas-liquid separator 28 and the intermediate heat exchanger 37. Therefore, the first expansion valve 31 can adjust the pressure of the refrigerant supplied to the second inlet 82 so as to increase the capacity of the ejector 27. Furthermore, after the refrigerant flowing through the fourth pipe 64 is depressurized by the first expansion valve 31, it exchanges heat with the refrigerant flowing through the third pipe 63 in the intermediate heat exchanger 37. This makes it easier for the refrigerant flowing through the fourth pipe 64 to vaporize due to the heat exchange in the intermediate heat exchanger 37.

In addition, by reducing the pressure and accelerating the refrigerant (suction flow) supplied to the second inlet 82, the speed difference between the refrigerant (driving flow) supplied to the first inlet 81 and the suction flow is reduced. This reduces losses due to the speed difference between the driving flow and the suction flow, and also increases the kinetic energy of the suction flow, thereby improving the performance of the ejector 27.

The temperature sensor 41 measures the temperature TN1 of the refrigerant flowing through the fourth pipe 64 between the intermediate heat exchanger 37 and the gas-liquid separator 28. The temperature sensor 42 measures the temperature TN2 of the refrigerant flowing through the fourth pipe 64 between the intermediate heat exchanger 37 and the second inlet 82. The control device 14 acquires the measurement results from the temperature sensors 41 and 42 and controls the opening degree of the first expansion valve 31 based on the measurement results. The refrigerant pressures P1 and P2 at the inlet and outlet of the intermediate heat exchanger 37 can be calculated from the temperatures TN1 and TN2 measured by the temperature sensors 41 and 42. When the pressure P2 of the refrigerant supplied from the intermediate heat exchanger 37 to the second inlet 82 is within a predetermined range, the capacity of the ejector 27 is increased. Furthermore, when the refrigerant pressure P1 at the inlet of the intermediate heat exchanger 37 is approximately the same as or lower than the refrigerant pressure P2 at the outlet, the capacity of the ejector 27 is increased. Therefore, by controlling the opening degree of the first expansion valve 31, the control device 14 can control the refrigerant pressures P1 and P2 at the inlet and outlet of the intermediate heat exchanger 37 so as to increase the capacity of the ejector 27.

The second expansion valve 32 is provided on the second pipe 62 between the gas-liquid separator 28 and the condenser C. If the pressure of the refrigerant supplied to the gas-liquid separator 28 is high, separation of the refrigerant in the gas-liquid separator 28 may be hindered. However, in the air conditioner 10, the refrigerant is depressurized by the second expansion valve 32 before being supplied to the gas-liquid separator 28. This allows the air conditioner 10 to prevent problems with refrigerant separation in the gas-liquid separator 28 and adjust the amount of refrigerant distributed to the third pipe 63 and the fourth pipe 64.

The heat storage material 38 is thermally connected to the intermediate heat exchanger 37. As a result, even if the temperature of the refrigerant flowing through the third pipe 63 changes, the intermediate heat exchanger 37 can vaporize the refrigerant flowing through the fourth pipe 64 by exchanging heat between the refrigerant flowing through the fourth pipe 64 and the heat storage material 38. Furthermore, the intermediate heat exchanger 37 can improve the efficiency of heat exchange between the refrigerant flowing through the third pipe 63 and the refrigerant flowing through the fourth pipe 64.

The fourth pipe 64 has an inlet 64c located at one end 37a of the intermediate heat exchanger 37 and an outlet 64d located at the other end 37b of the intermediate heat exchanger 37. The outlet 64d is closer to the second inlet 82 than the inlet 64c. The inner diameter of the outlet 64d is larger than the inner diameter of the inlet 64c. This allows the fourth pipe 64 to suppress refrigerant pressure loss at the outlet 64d. Therefore, the air conditioner 10 can suppress a decrease in the performance of the ejector 27.

The intermediate heat exchanger 37 is a double-pipe heat exchanger that includes a portion of the third pipe 63 and a portion of the fourth pipe 64. This allows the air conditioner 10 to reduce the lengths of the third pipe 63 and the fourth pipe 64 in the intermediate heat exchanger 37, thereby suppressing refrigerant pressure loss in the intermediate heat exchanger 37.

In the above explanation, suppression is defined as, for example, preventing an event, action, or influence from occurring, or reducing the severity of an event, action, or influence. Also, in the above explanation, restriction is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a specified range and preventing movement or rotation beyond that specified range.

While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in a variety of other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their variations are within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

10...Air conditioner, 14...Control device, 21...Outdoor heat exchanger, 23...Compressor, 23a...Inlet, 23b...Outlet, 27...Ejector, 28...Gas-liquid separator, 31...First expansion valve, 32...Second expansion valve, 37...Intermediate heat exchanger, 37a, 37b...End, 38...Heat storage material, 41, 42...Temperature sensor, 51...Indoor heat exchanger, 61...First pipe, 62...Second pipe, 63...Third pipe, 64...Fourth pipe, 64c...Inlet, 64d...Outlet, 81...First inlet, 82...Second inlet, 83...Outlet, E...Evaporator, C...Condenser.

Claims (6)

An outdoor heat exchanger;
An indoor heat exchanger;
a first pipe connecting the outdoor heat exchanger and the indoor heat exchanger and through which a refrigerant flows;
a second pipe connecting the indoor heat exchanger and the outdoor heat exchanger and through which the refrigerant flows;
a compressor provided in the first pipe, the compressor having a suction port through which the refrigerant is drawn and a discharge port through which the refrigerant is discharged;
an ejector provided in the second piping, the ejector having an outlet connected to a first heat exchanger of either the outdoor heat exchanger or the indoor heat exchanger via the second piping, a first inlet connected to a second heat exchanger of the other of the indoor heat exchanger or the indoor heat exchanger via the second piping, and a second inlet, the ejector being capable of mixing the refrigerant supplied to the first inlet with the refrigerant supplied to the second inlet, increasing the pressure of the refrigerant, and supplying the refrigerant from the outlet to the first heat exchanger;
a gas-liquid separator that is provided in the second pipe between the second heat exchanger and the first inlet, that separates the refrigerant supplied from the second heat exchanger into the liquid refrigerant and the refrigerant containing gas, and that supplies the refrigerant containing gas to the first inlet through the second pipe;
a third pipe connected to the second pipe between the second heat exchanger and the gas-liquid separator and connected to the first pipe between the discharge port and the second heat exchanger;
a fourth pipe connecting the gas-liquid separator and the second inlet and distributing the liquid refrigerant from the gas-liquid separator;
a third heat exchanger that performs heat exchange between the refrigerant flowing through the third pipe and the refrigerant flowing through the fourth pipe;
An air conditioner equipped with the above. The air conditioner of claim 1, further comprising a first expansion valve provided in the fourth pipe between the gas-liquid separator and the third heat exchanger. a first sensor that measures the temperature of the refrigerant flowing through the fourth pipe between the third heat exchanger and the gas-liquid separator;
a second sensor that measures the temperature of the refrigerant flowing through the fourth pipe between the third heat exchanger and the second inlet;
a control device that acquires measurement results from the first sensor and the second sensor and controls the opening degree of the first expansion valve based on the measurement results;
3. The air conditioner of claim 2, further comprising: An air conditioner according to any one of claims 1 to 3, further comprising a second expansion valve provided in the second piping between the gas-liquid separator and the second heat exchanger. An air conditioner according to any one of claims 1 to 3, further comprising a heat storage material thermally connected to the third heat exchanger. the fourth pipe has an inlet portion located at one end of the third heat exchanger and an outlet portion located at another end of the third heat exchanger, the outlet portion being closer to the second inlet than the inlet portion;
The inner diameter at the outlet portion is larger than the inner diameter at the inlet portion.
4. An air conditioner according to any one of claims 1 to 3.