JP4639708B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner, and more particularly to a heating-enhanced structure in which heating capacity is not lowered even in a cold region.

A conventional air conditioner forms a refrigerant circuit by sequentially connecting a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger. During cooling operation, the refrigerant discharged from the compressor is Circulates through the valve, outdoor heat exchanger, expansion valve, and indoor heat exchanger in sequence, and during heating operation, the refrigerant discharged from the compressor is sequentially circulated through the four-way valve, indoor heat exchanger, expansion valve, and outdoor heat exchanger. It is supposed to let you. However, when the heating operation is started, the outdoor heat exchanger is cooled, so that the outdoor heat exchanger is frosted, so that the defrosting operation is required, and the heating capacity is lowered at a low outdoor temperature. It was.

In order to prevent these phenomena, for example, as shown in FIG. 4, the compressor 40, the first four-way valve 41, the indoor heat exchanger 42, the cooling expansion valve 43, the second four-way valve 44, and the third four-way The valve 45, the heating expansion valve 46, the outdoor heat exchanger 47, and the accumulator 51 are sequentially connected, and branch from one side of the outdoor heat exchanger 47, and the on-off valve 48, the third four-way valve 45, and the There is an example in which a bypass passage 49 in which an auxiliary heat exchanger 50 is formed in the outdoor heat exchanger 47 through the second four-way valve 44 is provided (for example, see Patent Document 1).

In the above configuration, during the cooling operation, the refrigerant condensed in the outdoor heat exchanger 47 is guided to the auxiliary heat exchanger 50 through the bypass passage 49, and the refrigerant flowing through the outdoor heat exchanger 47 is supercooled to While evaporating capacity in the heat exchanger 42 is increased, during heating operation, the defrosting is performed by heating with the auxiliary heat exchanger 50 and then acts as an evaporator to increase heating capacity.

However, the provision of the bypass passage 49 including the on-off valve 48, the second four-way valve 44, and the third four-way valve 45 complicates the configuration of the refrigerant circuit, while one of the refrigerant flowing through the refrigerant circuit. The capacity is limited by supplying the auxiliary heat exchanger 50 to the auxiliary heat exchanger 50 and performing heating or cooling. For example, when performing a heating operation in a low outdoor temperature of less than zero degrees or in a cold region, the outdoor heat exchange is performed. In addition to not being able to completely prevent frost formation in the vessel 47, there is a possibility that the heating operation itself may be hindered.

As another conventional example, as shown in FIG. 5, for example, an outdoor heat exchanger 63 provided with a compressor 60, a four-way valve 61, a blower fan 63a, an expansion valve 64, and an indoor heat provided with a blower fan 65a. The exchanger 65 and the accumulator 66 are sequentially connected to form a main circuit, while the radiator 68, the open / close valve 69, the hot water pump 70, and the auxiliary heat exchanger 71 including the burner 72 are sequentially connected to There is an example in which the circuit 67 is configured (see, for example, Patent Document 2).

When the heating operation is performed in the main circuit, the outdoor heat exchanger 63 is cooled and frost may be generated in the outdoor heat exchanger 63. Therefore, the burner 72 provided in the hot water circuit 67 is burned. The auxiliary heat exchanger 71 is heated to generate hot water. The generated hot water is supplied to the radiator 38 by the hot water pump 70, and the radiator 38 generates hot air to heat the outdoor heat exchanger 63. Thereby, frost formation in the outdoor heat exchanger 63 is prevented, and the heating operation is started smoothly.

However, generating hot water using another heat source such as the burner 72 has a low so-called energy conversion efficiency, which also reduces the coefficient of performance (COP) in the entire refrigerant circuit, and therefore from the viewpoint of energy saving. There was a need for improvement.

JP 59-229149 (2 pages, FIG. 3) Japanese Patent Laid-Open No. 2001-12829 (page 3, FIG. 1)

In view of the above-mentioned problems, the present invention can prevent frost formation in the outdoor heat exchanger at the time of low outside air temperature of 0 ° C. or less, or in a cold district, thereby eliminating the need for a defrosting operation. An object of the present invention is to provide a heating-enhanced air conditioner that improves the capacity, improves the capacity of heating operation, and further improves the coefficient of performance of the refrigerant circuit, so-called COP.

The present invention comprises an outdoor heat exchanger composed of a first heat exchange part and a second heat exchange part, a first compressor, a first flow path switching means, and a first heat exchange part of the outdoor heat exchanger. And the first pressure reducing means and the indoor heat exchanger are sequentially connected to form a main cycle,
A second compressor, a second heat exchange unit that heats the first heat exchange unit during heating operation of the main cycle, and a first check that bypasses the first auxiliary heat exchanger and the first auxiliary heat exchanger A first bypass passage having a valve, a second bypass passage having a second check valve for bypassing the second auxiliary heat exchanger and the second auxiliary heat exchanger, the first auxiliary heat exchanger, and the A second pressure reducing means provided between the second auxiliary heat exchanger and a second flow path switching means for switching the flow path to the first auxiliary heat exchanger or the second auxiliary heat exchanger; Composing a cycle,
Either the first auxiliary heat exchanger or the second auxiliary heat exchanger is used as an evaporator, and when it is determined that the evaporator has formed frost, the other auxiliary heat exchange is performed by the second flow path switching means. It is configured to be used as an evaporator by switching to an evaporator .
Further, when it is determined that the first auxiliary heat exchanger has formed frost, the first auxiliary heat exchanger that has formed frost by flowing a refrigerant through both the first auxiliary heat exchanger and the first bypass passage. Defrost
When it is determined that the second auxiliary heat exchanger has frosted, the frosted second auxiliary heat exchanger is removed by flowing a refrigerant through both the second auxiliary heat exchanger and the second bypass passage. It is configured to frost.

According to the present invention, the first compressor, the first four-way valve as the first flow path switching means, the first heat exchange part of the outdoor heat exchanger, the first expansion valve as the first pressure reducing means, A main cycle is configured by sequentially connecting a heat exchanger, a second compressor, a second heat exchange of the outdoor heat exchanger, a second four-way valve as a second flow path switching means, a first An auxiliary heat exchanger, a second expansion valve as a second flow path switching means, and a second auxiliary heat exchanger are sequentially connected, and a first check valve is provided that bypasses the first auxiliary heat exchanger. Providing a second bypass path with a second check valve, which bypasses the second auxiliary heat exchanger, and constitutes a sub-cycle. The outdoor heat exchanger is heated by the circulating refrigerant, and frost forms on the surfaces of the fins or heat transfer tubes. The amount of refrigerant condensed in the indoor heat exchanger is increased by increasing the amount of refrigerant evaporated in the outdoor heat exchanger by heating. Thus, the heating operation can be continued without lowering the capacity even in a low outdoor temperature or in a cold region. Further, when the heating operation is continued, frost is generated in the second auxiliary heat exchanger by the low-temperature and low-pressure refrigerant, but the second compressor is switched by switching the second four-way valve provided in the subcycle. The high-temperature and high-pressure refrigerant from the refrigerant flows into the second auxiliary heat exchanger, and the attached frost is removed. Thereby, even in the state of extremely low temperature, the heating operation in the main cycle can be continued without any trouble. Also, heating-enhanced air-conditioning that can perform so-called energy-saving operation by increasing the energy conversion efficiency and generating a coefficient of performance (COP) by generating hot water without using a separate heat source such as a burner or a heater. It becomes a machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings.

FIG. 1 (A) is a refrigerant circuit diagram of a heating-enhanced air conditioner according to the present invention, and FIG. 1 (B) is a cross-sectional view of an outdoor heat exchanger. FIG. 2 is a refrigerant circuit diagram illustrating the refrigerant flow during the cooling operation, and FIGS. 3A and 3B are refrigerant circuit diagrams illustrating the refrigerant flow during the heating operation.

As shown in FIG. 1 (A), the heating-enhanced air conditioner according to the present invention is an outdoor unit provided with a first compressor 3, a first four-way valve 4 as first flow path switching means, and a blower fan 6. A main cycle 1 is configured by sequentially connecting a heat exchanger 5, a first expansion valve 7 as a first pressure reducing means, and an indoor heat exchanger 8 having a blower fan 9. Further, the second compressor 10, the outdoor heat exchanger 5, the second four-way valve 11 as the second flow path switching means, the first auxiliary heat exchanger 12, the second expansion valve 15, and the second auxiliary. A first bypass passage 13 having a first check valve 14 that bypasses the first auxiliary heat exchanger 12 and that sequentially connects the heat exchanger 16 is provided, and the second auxiliary heat exchanger 16 is bypassed. The second cycle 17 provided with the second check valve 18 is provided to constitute the sub-cycle 2. The first check valve 14 enters the first bypass passage 13 with the flow from the second four-way valve 11 through the first auxiliary heat exchanger 12 toward the second expansion valve 15 as a forward direction. The second check valve 18 is connected to the second bypass passage 17 with the flow from the second four-way valve 11 through the second auxiliary heat exchanger 16 toward the second expansion valve 15 as a forward direction. It is connected.

The outdoor heat exchanger 5 includes a large number of fins arranged in parallel and heat transfer tubes arranged in a meandering manner so as to be orthogonal to the fins. As shown in FIG. The first heat exchange part 5a in which the heat transfer tube connected to the main cycle 1 is arranged on the side and the second heat exchange part 5b in which the heat transfer tube connected to the subcycle 2 is arranged on the other side. Yes.

Also, HFC refrigerant or HCFC refrigerant circulates in the main cycle 1, and HFC refrigerant or HCFC refrigerant similarly in the subcycle 2 or HC refrigerant having high heat exchange efficiency in a low temperature state. Propane etc. are circulated.

Next, the operation will be described. During the cooling operation, the second compressor 10 is stopped and the refrigerant does not circulate in the subcycle 2. The high-temperature and high-pressure refrigerant discharged from the discharge side of the first compressor 3 passes through the first four-way valve 4 and the first heat exchange part of the outdoor heat exchanger 5 as shown by the arrows in FIG. It flows into 5a, discharge | releases heat | fever in the said 1st heat exchange part 5a, and condenses. Subsequently, the condensed refrigerant is adiabatically expanded by the first expansion valve 7 to become a low temperature and low pressure, flows into the indoor heat exchanger 9, absorbs heat in the indoor heat exchanger 8, and evaporates. The evaporated refrigerant returns to the suction side of the compressor 3 through the first four-way valve 4. Further, the air flowing around the air cooled by the indoor heat exchanger 8 is sent into the room by the blower fan 9 and is cooled.

Next, the heating operation will be described. During the heating operation, the second compressor 10 is driven, and the refrigerant circulates through the subcycle 2. The first four-way valve 4 is switched. In the main cycle 1, the high-temperature and high-pressure refrigerant discharged from the discharge side of the first compressor 3 passes through the four-way valve 4 and the indoor heat exchanger as indicated by an arrow in FIG. 8 is discharged into the indoor heat exchanger 8 to condense. The condensed refrigerant is then adiabatically expanded by the first expansion valve 7 to become a low temperature and low pressure, flows into the first heat exchange part 5a of the outdoor heat exchanger 5, and absorbs heat to evaporate. The evaporated refrigerant returns to the suction side of the first compressor 3 through the first four-way valve 4. Further, the air flowing around the space heated by the heat released from the indoor heat exchanger 8 is sent out indoors by the blower fan 9 and is heated.

The high-temperature and high-pressure refrigerant discharged from the second compressor 10 in the sub-cycle 2 flows into the second heat exchange part 5b of the outdoor heat exchanger 5 and releases heat in the second heat exchange part 5b. Condensed and condensed refrigerant then flows into the first auxiliary heat exchanger 12 and the first bypass passage 13 via the second four-way valve 11. The refrigerant flowing into the first auxiliary heat exchanger 12 is mixed with the refrigerant passing through the first bypass passage 13 while heating the first auxiliary heat exchanger 12, and is adiabatically expanded by the second expansion valve 15. And low temperature and low pressure. The low-temperature and low-pressure refrigerant flows into the second auxiliary heat exchanger 16, absorbs heat in the second auxiliary heat exchanger 16 and evaporates, and the evaporated refrigerant passes through the second four-way valve 11. The second compressor 10 is refluxed.

When the heating operation is started at a low outdoor temperature with high humidity, the outdoor heat exchanger 5 is cooled by the low-temperature and low-pressure refrigerant of the main cycle 1 flowing into the first heat exchange section 5a of the outdoor heat exchanger 5, There is a possibility that frost formation may occur around the fins or heat transfer tubes. Further, heat cannot be sufficiently absorbed from the outside air, and the low-temperature and low-pressure liquid phase refrigerant cannot sufficiently evaporate. Therefore, the amount of condensation in the indoor heat exchanger 9 is also reduced, and the heating capacity may be reduced.

However, at the start of the heating operation, the outdoor heat exchanger 5 is heated by the refrigerant circulating in the subcycle 2 to prevent frost formation on the surfaces of the fins or the heat transfer tubes, thereby temporarily stopping the heating operation. The defrosting operation performed by interruption is unnecessary, and the amount of refrigerant evaporated in the outdoor heat exchanger 5 is increased by heating, whereby the refrigerant condensation amount and the heat release amount in the indoor heat exchanger 9 are increased. By increasing the temperature, the heating operation can be continued without lowering the capacity even in a low outside temperature or in a cold region.

Further, when a heater or burner is used as a heat source for heating the outdoor heat exchanger 5, electric energy or combustion energy is converted into heat energy. This greatly increases power consumption or energy consumption. For this reason, if the coefficient of performance (COP), which is the ratio between the cooling capacity or heating capacity and the power consumption (energy consumption), decreases, for example, the coefficient of performance becomes a value of 1 or less, from the viewpoint of energy saving. This is undesirable. In the present application, a high-pressure refrigerant is generated by the compressor 13 provided in the sub-cycle 2, and the refrigerant performs heat exchange with air in the process of condensation and evaporation, and is an index of refrigerant capacity or heating capacity. The enthalpy difference can be made larger than the power consumption. For example, the coefficient of performance (COP) can be in the range of 2.5 to 3. Thus, so-called energy saving operation can be performed.

When the heating operation is continued in the above-described state, the low temperature and low pressure refrigerant flows into the second auxiliary heat exchanger 16 through the second expansion valve 15, so that the second auxiliary heat exchanger 16 is frosted, Heat exchange efficiency decreases. When the heat exchange efficiency is lowered, the heating capacity in the second heat exchange section 5b of the outdoor heat exchanger 5 is also lowered, so that the heating capacity in the main cycle 1 is also lowered. In order to prevent this, when the temperature of the fins or heat transfer tubes of the second auxiliary heat exchanger 16 falls below a predetermined value, the second four-way valve 11 provided in the sub-cycle 2 is switched. Yes. The switching may be performed based on the refrigerant temperature flowing in.

When the second four-way valve 11 is switched, the high-temperature and high-pressure refrigerant discharged from the second compressor 10 is changed to the second heat of the outdoor heat exchanger 5 as shown by the arrow in FIG. The refrigerant flows into the exchange section 5b and releases and condenses heat in the second heat exchange section 5b, and the condensed refrigerant subsequently passes through the second four-way valve 11 and the second auxiliary heat exchanger 16 and the It flows into the second bypass 17. The refrigerant flowing into the second auxiliary heat exchanger 16 is mixed with the refrigerant passing through the second bypass passage 17 while heating the second auxiliary heat exchanger 16, and is adiabatically expanded by the second expansion valve 15. Low temperature and low pressure. At this time, frost adhering to the second auxiliary heat exchanger 16 is removed by the released heat. The low-temperature and low-pressure refrigerant flows into the first auxiliary heat exchanger 12, absorbs heat in the first auxiliary heat exchanger 12, and evaporates. The evaporated refrigerant passes through the second four-way valve 11. The second compressor 10 is refluxed. When the operation is continued in this state, the second four-way valve 11 is switched again. Thereby, even in the state of extremely low temperature, the heating operation in the main cycle 1 can be continued without any trouble.

(A) is a refrigerant circuit diagram of the present invention. (B) is sectional drawing of an outdoor heat exchanger. It is a refrigerant circuit figure which shows the flow of the refrigerant | coolant at the time of air_conditionaing | cooling operation. (A) is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of heating operation. (B) is a refrigerant circuit diagram showing the flow of refrigerant during heating operation with the second four-way valve switched. It is a refrigerant circuit figure which shows an example in a prior art example. It is a refrigerant circuit diagram which shows the other example in the past.

DESCRIPTION OF SYMBOLS 1 Main cycle 2 Sub cycle 3 1st compressor 4 1st four-way valve 5 Outdoor heat exchanger 5a 1st heat exchange part 5b 2nd heat exchange part 6 Blower fan 7 First expansion valve 8 Indoor heat exchanger 9 Blower fan 10 Second compressor 11 Second four-way valve 12 First auxiliary heat exchanger 13 First bypass passage 14 First check valve 15 Second expansion valve 16 Second auxiliary heat exchanger 17 Second bypass passage 18 Second check valve

Claims (2)

The outdoor heat exchanger includes a first heat exchange unit and a second heat exchange unit, a first compressor, a first flow path switching unit, a first heat exchange unit of the outdoor heat exchanger, and a first The main cycle is configured by sequentially connecting the decompression means and the indoor heat exchanger,
A second compressor, a second heat exchange unit that heats the first heat exchange unit during heating operation of the main cycle, and a first check that bypasses the first auxiliary heat exchanger and the first auxiliary heat exchanger A first bypass passage having a valve, a second bypass passage having a second check valve for bypassing the second auxiliary heat exchanger and the second auxiliary heat exchanger, the first auxiliary heat exchanger, and the A second pressure reducing means provided between the second auxiliary heat exchanger and a second flow path switching means for switching the flow path to the first auxiliary heat exchanger or the second auxiliary heat exchanger; Composing a cycle,
Either the first auxiliary heat exchanger or the second auxiliary heat exchanger is used as an evaporator, and when it is determined that the evaporator has formed frost, the other auxiliary heat exchange is performed by the second flow path switching means. An air conditioner that is used as an evaporator by switching to a vacuum vessel.
When it is determined that the first auxiliary heat exchanger has formed frost, the frosted first auxiliary heat exchanger is removed by flowing a refrigerant through both the first auxiliary heat exchanger and the first bypass passage. Frost,
When it is determined that the second auxiliary heat exchanger has formed frost, the frosted second auxiliary heat exchanger is removed by flowing a refrigerant through both the second auxiliary heat exchanger and the second bypass passage. The air conditioner according to claim 1, wherein the air conditioner is frosted .