JPH10253179A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a deteriorated product of freezer oil from being produced by providing a bypass circuit which branches from a refrigerant piping located between a condenser and a drawing apparatus, and is connected with a refrigerant piping located between the drawing apparatus and a compressor. SOLUTION: Upon cooling a gas refrigerant compressed in a compressor 1 is converted into a high temperature high pressure liquid refrigerant in a heat source machine side heat exchanger 3. Then, part of the liquid refrigerant after passage through a second drawing apparatus 6 flows into a bypass circuit 15, and is converted into a low temperature low pressure gas/liquid binary refrigerant in a third drawing apparatus 17 after passage through a drier 16, and in bypass heat exchangers 18a, 18b it heat exchanges with a liquid refrigerant flowing out from the heat source machine side heat exchanger 3 and with a liquid refrigerant flowing out from the second drawing apparatus 6. It joints a refrigerant passing through indoor machines B, C, D between a changeover valve 2 and the compressor 1 and is returned to the compressor 1. Thereupon, hydrolysis is sufficiently restricted with the aid of water adsorption capability of the drier 16 so that generation of sludge component in the compressor 1 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an air conditioner using a hydrofluorocarbon-based refrigerant as a working medium and an oil compatible with the refrigerant as a refrigerating machine oil.

[0002]

2. Description of the Related Art FIG. 28 is a refrigerant circuit diagram of a conventional air conditioner, in which A is a heat source unit, B, C, and D are indoor units, 1 is a compressor, 2 is a switching valve, and 3 is a heat source unit. Machine side heat exchanger,
4 is an accumulator, 5 is an oil return hole of the accumulator 4, 6 is a throttle device for heating (hereinafter referred to as a second throttle device), 7b, 7c and 7d are indoor unit side heat exchangers, 8b and 8
Reference numerals c and 8d denote cooling-time expansion devices (hereinafter referred to as first expansion devices), 9 denotes one end of the heat source device A on the heat source device side heat exchanger 3 side and the first expansion devices 8b of the indoor units B, C, and D. , 8c, 8d, is connected to one end of the heat source unit A on the switching valve 2 side and the indoor unit B, C, D indoor unit side heat exchangers 7b, 7c, The gas-side connecting refrigerant pipes connecting the one end on the 7d side, 11 and 12 have a desiccant mainly composed of synthetic zeolite or the like incorporated in a cylindrical container or a pipe.
Dryer for absorbing moisture mixed in the refrigerant circuit, 13,
Reference numerals 14b, 14c, and 14d denote sludge filters that capture sludge by incorporating a fine mesh filter in a cylindrical container or a pipe.

Next, the flow of the refrigerant will be described with reference to the drawings.
In the figure, solid arrows indicate flows during cooling, and broken arrows indicate flows during heating. First, during cooling, the gas refrigerant compressed to a high temperature and a high pressure by the compressor 1 flows into the heat source device side heat exchanger 3 through the switching valve 2 and exchanges heat with air or the like to be condensed. It becomes a refrigerant. Further, the indoor units B, C, and D pass through the second expansion device 6 and the liquid-side connection refrigerant pipe 9 that are fully opened during cooling.
And the first expansion devices 8b, 8c, 8d are controlled so that the degree of superheat at the outlets of the indoor unit side heat exchangers 7b, 7c, 7d is within a certain range. Can be The low-pressure gas-liquid two-phase refrigerant is supplied to the indoor unit side heat exchanger 7b,
7c, 7d, gas exchange by heat exchange with the indoor air, gaseous connection refrigerant pipe 10, switching valve 2, accumulator
And returns to the compressor 1 via the compressor 4. The refrigerating machine oil inside the accumulator 4 returns to the compressor 1 through the oil return hole 5 together with the liquid refrigerant.

At the time of heating, the gas refrigerant compressed to a high temperature and a high pressure by the compressor 1 reaches the indoor units B, C and D via the switching valve 2 and the gas side connection refrigerant pipe 10, and the indoor unit side heat exchanger. It flows into 7b, 7c, 7d, exchanges heat with indoor air and condenses, and becomes a high-temperature and high-pressure liquid refrigerant. Indoor heat exchanger 7
The liquid refrigerant that has exited from b, 7c, and 7d is almost completely open.
The pressure is slightly reduced by the expansion devices 7b, 7c, and 7d, and reaches the second expansion device 6 via the liquid-side connection refrigerant pipe 9, where it is reduced to a low-pressure gas-liquid two-phase state. The low-pressure gas-liquid two-phase refrigerant flows into the heat source-side heat exchanger 3, exchanges heat with air or the like to gasify, and returns to the compressor 1 via the switching valve 2 and the accumulator 4. The refrigerating machine oil inside the accumulator 4 returns to the compressor 1 through the oil return hole 5 together with the liquid refrigerant.

In such a refrigerant circuit, a hydrofluorocarbon-based refrigerant has recently been used as a working medium instead of a hydrochlorofluorocarbon-based refrigerant. However, since the hydrofluorocarbon-based refrigerant has no chlorine component, it is not compatible with the conventional mineral oil used as refrigerating machine oil, and separates from the liquid refrigerant inside the accumulator 4 and floats on the upper portion. Then, the refrigerating machine oil does not return to the compressor 1 from the oil return hole 5. Therefore, in an air conditioner in which a large amount of liquid refrigerant is stored in an accumulator and the compressor 1 is driven by a motor, polyester which is compatible with a hydrofluorocarbon-based refrigerant and has excellent insulation properties. Oils or polyether oils are commonly used.

However, these polyester oils and polyether oils absorb moisture and are hydrolyzed when exposed to high temperatures such as the sliding parts of the compressor 1, and cause oxygen and refrigerant circuit components. Deterioration may occur due to residual components of processing oil and cleaning agents mixed in during processing. In particular, among the additives used in the polyether oil, the antiwear agent is generally an ester-based one having high activity. Even if the polyether oil is not hydrolyzed, the additive is hydrolyzed and compressed at a high temperature. Thermal degradation occurs in the sliding part of the machine 1.

[0007] The degradation products generated at this time include those present as solids in the refrigerating machine oil and those present as being dissolved therein. When the high-temperature and high-pressure gas refrigerant is discharged from the compressor 1 in both the solid component and the dissolved component, the gas refrigerant is discharged into the refrigerant circuit while being mixed with the discharge gas together with the refrigerating machine oil. The deterioration product of the refrigerating machine oil flows into a condenser (the heat source unit side heat exchanger 3 during cooling, and the indoor unit side heat exchangers 7b, 7c, 7d during cooling) together with the refrigerant, and the refrigerant is liquefied here. When the refrigerant is liquefied and the concentration of the refrigerant increases, the degradation products of the refrigerating machine oil dissolved in the refrigerating machine oil flowing together with the refrigerant cannot be dissolved and precipitate as solids and precipitate directly on the pipe wall of the pipe. Things appear.

[0008] These newly precipitated degradation products flow into the first expansion devices 8b, 8c, 8d and the second expansion device 6 together with the degradation products originally existing as solids. Incompatibility with the hydrofluorocarbon-based refrigerant in the remaining components of the processing oil and cleaning agent mixed when processing the refrigerant circuit components forms a film on the pipe wall of the piping, The dissolved component becomes a binder, and the degradation products of the refrigerating machine oil adhere to the pipe wall of the pipe. In particular, in a throttle device such as a capillary tube whose channel cross-sectional area changes suddenly, the flow becomes stagnant, and the degradation products of the refrigerating machine oil are remarkably attached. In this way, the refrigerating machine oil degraded substance present as a solid in the refrigerating machine oil is converted into sludge by the first expansion devices 8b, 8c, 8
d and adheres to the second aperture device 6. Further, when the liquid refrigerant is accumulated in the accumulator 4, degradation products as solid or dissolved components of the refrigerating machine oil are deposited and adhere to the oil return hole 5 as in the expansion device.

As a countermeasure against the sludge adhesion as described above,
Dryers 11 and 12 in which a desiccant mainly composed of synthetic zeolite or the like is built in a cylindrical container or a pipe are refrigerant pipes between the switching valve 2 and the accumulator 4, and first throttle devices 8b and 8c. A sludge filter provided in the liquid-side connection refrigerant pipe 9 between the second throttle device 8d and the second expansion device 6, and having a fine mesh filter built in a cylindrical container or pipe,
A refrigerant pipe between the heat source unit side heat exchanger 3 and the second expansion device 6 and a refrigerant pipe between the indoor side heat exchangers 7b, 7c, 7d and the first expansion devices 8b, 8c, 8d. Provided.

A dryer 11 provided between the switching valve 2 and the accumulator 4 has an indoor unit side heat exchanger 7 during cooling.
From b, 7c and 7d, the gas refrigerant flows from the heat source device side heat exchanger 3 via the switching valve 2 during heating, and the moisture contained in the gas refrigerant is absorbed. First diaphragm devices 8b, 8c, 8d
The dryer 12 provided in the liquid-side connection refrigerant pipe 9 between the heat source unit side heat exchanger 3 and the second expansion device 6 during cooling.
From the second expansion device 6 which is almost fully opened, and from the indoor unit side heat exchangers 7b, 7c, 7d during heating, to the first expansion device 8b, 8c, 8d which is almost fully opened, and a little. A depressurized liquid single-phase refrigerant flows in. Therefore, the pressure loss in the dryer 12 is small, the flow becomes quiet, and moisture is sufficiently absorbed.

In the sludge filter 13 provided in the refrigerant pipe between the heat source unit side heat exchanger 3 and the second expansion device 6, the deterioration of the refrigerating machine oil which flows into the heat source unit side heat exchanger 3 together with the refrigerant during cooling. Product and the heat exchanger 3
The degradation products dissolved in the refrigerating machine oil deposited and adhered due to the liquefaction of the refrigerant and the decrease in the flow rate at the time are captured as sludge. In addition, the indoor heat exchangers 7b, 7c, 7d
Filters 14b, 14c, 14d provided in the refrigerant pipes between the first expansion devices 8b, 8c, 8d and the first expansion devices 8b, 8c, 8d. The degradation products and the degradation products dissolved in the refrigerating machine oil deposited and adhered due to the liquefaction of the refrigerant in the indoor heat exchangers 7b, 7c, and 7d and the decrease in the flow velocity are captured as sludge.

[0012]

In a conventional air conditioner using a dryer as described above, a dryer 11 is used.
As a result, the suction pressure loss occurs due to the passage of the refrigerant gas, and the evaporating capacity is reduced. Conversely, in order to suppress the decrease in the evaporating capacity, it is necessary to enlarge the dryer 11. In addition, if sufficient non-oxidation brazing is not performed during the construction of the refrigerant pipe, an oxidation scale is generated.
There was a risk that the gas would flow into the channels 1 and 12 to block the flow path and the dryer 11 would be crushed. In addition, starting the compressor,
There is also a danger that the dryers 11 and 12 may be pulverized due to a sudden liquid back that occurs during a transient operation such as switching between cooling and heating, defrost start / end, and an intense flow of the refrigerant liquid.

In a conventional air conditioner provided with the above-described sludge filter, the heat exchanger 7 between the heat source unit side heat exchanger 3 and the second expansion device 6 and the indoor heat exchanger 7
It is necessary to install sludge filters at all positions between b, 7c, 7d and the first expansion devices 8b, 8c, 8d, and there is a problem that the entire air conditioner becomes large. Further, the sludge caught by the sludge filter 13 between the heat source unit side heat exchanger 3 and the second expansion device 6 during cooling is separated when the flow is switched to heating, and the heat source unit side heat exchanger 3 Then, the oil flows into the accumulator 4 via the switching valve 2, and the oil return hole 5 is closed. Similarly, at the time of heating, the indoor heat exchangers 7b, 7c, 7d and the first expansion devices 8b, 8c,
8d and sludge filters 14b, 14c, 14d
The sludge caught in the above is separated when the flow is switched to cooling, flows into the accumulator 4 via the indoor heat exchangers 7b, 7c, 7d and the switching valve 2, and the oil return hole 5 is closed. You. Furthermore, if sufficient non-oxidation brazing is not performed during the construction of the refrigerant pipe, an oxidation scale will be generated, which will cause sludge filters 13, 14b, 14c, 14 during operation.
d, there is also a risk that the flow path will be blocked or the sludge filter will be damaged.

The present invention has been made to solve the above-mentioned problems, and it is possible to use a hydrofluorocarbon-based refrigerant as a working fluid and use an oil compatible with the refrigerant as a refrigerating machine oil. It is another object of the present invention to provide a highly reliable air conditioner that does not easily cause deterioration products of refrigeration oil even if deterioration products are generated.

[0015]

According to a first aspect of the present invention, there is provided an air conditioner including a main refrigerant circuit including a compressor, a condenser, a throttle device, and an evaporator. In an air conditioner using a refrigerant as a working medium and an oil compatible with the refrigerant as a refrigerating machine oil, a dryer and a bypass throttle that branch from a refrigerant pipe between the condenser and the throttle device to absorb moisture. There is provided a bypass circuit connected to a refrigerant pipe between the expansion device of the main refrigerant circuit and the compressor via the device.

An air conditioner according to a second aspect of the present invention includes a main refrigerant circuit comprising a compressor, a condenser, a throttle device, and an evaporator, and uses a hydrofluorocarbon-based refrigerant as a working medium. In an air conditioner that uses oil compatible with this refrigerant as refrigerating machine oil, the refrigerant is branched from a refrigerant pipe on the discharge side of the compressor, and is supplied to a suction side of the compressor via a dryer and a bypass throttle device that absorb moisture. In which a bypass circuit connected to the refrigerant pipe is provided.

According to a third aspect of the present invention, in the air conditioner of the first or second aspect, a bypass heat exchanger for cooling the refrigerant flowing into the dryer is provided in the middle of the bypass.

According to a fourth aspect of the present invention, there is provided an air conditioner comprising a heat source unit including a compressor, a switching valve, a heat source unit side heat exchanger and a heating throttle unit, and a cooling source throttle unit and an indoor heat exchanger. An indoor unit, a liquid-side connecting refrigerant pipe connecting one end of the heat source unit on the heating throttle side and one end of the indoor unit on the cooling throttle side, and one end of the heat source unit on the switching valve side. A main refrigerant circuit having a gas-side connecting refrigerant pipe connecting to one end of the indoor unit on the indoor heat exchanger side, using a hydrofluorocarbon-based refrigerant as a working medium, and having compatibility with the refrigerant; An air conditioner using oil as refrigerating machine oil, comprising: a dryer that branches off from the liquid-side connection refrigerant pipe, absorbs moisture, a bypass expansion device, and a bypass heat exchanger that cools a refrigerant flowing into the dryer. Machine suction section Is provided with a bypass circuit connected to the refrigerant pipe between said switching valve.

According to a fifth aspect of the present invention, there is provided an air conditioner comprising: a heat source unit comprising a compressor, a switching valve and a heat source unit side heat exchanger; and an indoor unit comprising a throttle unit and an indoor side heat exchanger.
A liquid-side connecting refrigerant pipe connecting one end of the heat source unit on the heat source unit side heat exchanger side and one end of the indoor unit on the expansion device side, one end of the heat source unit on the switching valve side and the indoor side of the indoor unit A main refrigerant circuit having a gas-side connection refrigerant pipe connecting one end of the heat exchanger side is provided, and a hydrofluorocarbon-based refrigerant is used as a working medium, and oil compatible with the refrigerant is used as a refrigerating machine oil. In the air conditioner to be used, the compressor suction is branched from a refrigerant pipe between the compressor discharge part and the switching valve, via a bypass heat exchanger for cooling the refrigerant, a dryer for absorbing moisture, and a bypass throttle device. A bypass circuit connected to a refrigerant pipe between the section and the switching valve.

According to a sixth aspect of the present invention, there is provided an air conditioner according to any one of the first to fifth aspects, wherein a hydrofluorocarbon-based mixed refrigerant is used as a working medium, and an inlet of a bypass expansion device is provided. A first temperature detecting means provided in the compressor, a second temperature detecting means provided downstream of the bypass throttle device in the middle of the bypass, a suction pressure detecting means provided in the compressor suction section, , A second temperature detecting means and a composition calculating means for calculating the composition of the refrigerant based on the detected value of the suction pressure detecting means.

An air conditioner according to a seventh aspect of the present invention includes a main refrigerant circuit including a compressor, a condenser, a throttle device, and an evaporator, and uses a hydrofluorocarbon-based refrigerant as a working medium. An air conditioner using an oil compatible with this refrigerant as a refrigerating machine oil, wherein an oil separator is provided at the compressor discharge part, and an oil return bypass circuit is provided for returning the separated refrigerating machine oil to the compressor suction part. It is.

According to an eighth aspect of the present invention, in the air conditioner of the seventh aspect, a sludge filter is provided in the middle of the oil return bypass circuit.

According to a ninth aspect of the present invention, in the air conditioner of the eighth aspect, a bypass heat exchanger for cooling refrigerating machine oil is provided upstream of the sludge filter in the middle of the oil return bypass circuit. .

According to a tenth aspect of the present invention, in the air conditioner of the eighth aspect, a liquid refrigerant injection circuit for injecting a liquid refrigerant upstream of the sludge filter in the oil return bypass circuit is provided. .

According to an eleventh aspect of the present invention, in the air conditioner according to any one of the sixth to tenth aspects, the sludge filter in the middle of the oil return bypass absorbs moisture and has a sludge filter function. It is what it was.

According to a twelfth aspect of the present invention, there is provided an air conditioner according to any one of the first to sixth and eleventh aspects, wherein the mounting posture of the dryer is downward with respect to the flow direction.

According to a thirteenth aspect of the present invention, in the air conditioner according to any one of the third to sixth, ninth, eleventh, and twelfth aspects, the heat source device side heat exchanger is used as all or a part of the bypass heat exchanger. It is configured to pass through the lowermost part of the exchanger.

According to a fourteenth aspect of the present invention, there is provided an air conditioner comprising a compressor, a condenser, a throttle device, an evaporator, an accumulator.
An air conditioner comprising a main refrigerant circuit composed of a refrigerant, a hydrofluorocarbon-based refrigerant as a working medium, and an oil compatible with the refrigerant as a refrigerating machine oil. An oil return mechanism is provided for returning the refrigerating machine oil to be stored in parallel at two locations above and below a refrigerant outflow pipe from the accumulator to the compressor.

An air conditioner according to a fifteenth aspect of the present invention includes a main refrigerant circuit composed of a compressor, a condenser, a throttle device, and an evaporator, and uses a hydrofluorocarbon-based refrigerant as a working medium. In the air conditioner using the oil compatible with the refrigerant as the refrigerating machine oil, the throttling device is adjusted so that the degree of superheat at the evaporator outlet calculated from the medium temperature at the evaporator inlet and outlet is within a certain range. And an upper limit opening is provided to suppress excessive valve opening due to control divergence, the degree of superheat at the evaporator outlet exceeds a certain range, and the opening degree of the expansion device reaches the upper limit opening. When the refrigerant temperature on the inlet side of the expansion device, the discharge side pressure of the compressor and the supercooling degree of the expansion device inlet calculated from the composition of the refrigerant are equal to or more than a predetermined value, the upper limit opening is increased. Supplement Those having a diaphragm device control apparatus.

An air conditioner according to a sixteenth aspect of the present invention is a main refrigerant having a heat source unit including a compressor and a heat source unit side heat exchanger, and a plurality of indoor units including a throttling device and an indoor side heat exchanger. An air conditioner including a circuit, using a hydrofluorocarbon-based refrigerant as a working medium, and using oil compatible with the refrigerant as a refrigerating machine oil, wherein each of the indoor units includes a blower for defrosting, The air blower is operated when the medium temperature at the outlet side of the indoor heat exchanger of the indoor unit that is not performing the cooling operation continuously falls below the predetermined temperature for a predetermined time when only the indoor unit of the unit is performing the cooling operation. A defrost control device is provided.

According to a seventeenth aspect of the present invention, in the air conditioner according to the nineteenth aspect, the operation of each of the indoor units is started simultaneously with the defrosting fan, and a predetermined time has elapsed since the operation of the blower was stopped. A drain pump for draining drain generated in the indoor unit, which is controlled by a defrost control device so as to stop after a lapse of time, is provided.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 1. In the figure, A is a heat source unit, B, C and D are indoor units, 1 is a compressor, 2 is a switching valve, 3
Is a heat source side heat exchanger, 4 is an accumulator, 5 is an oil return hole of the accumulator 4, 6 is a second expansion device, 7b, 7
c and 7d are indoor unit side heat exchangers, and 8b, 8c and 8d are first heat exchangers.
Reference numeral 9 denotes a liquid side connection refrigerant pipe, and 10 denotes a gas side connection refrigerant pipe. The above is the same as the conventional example shown in FIG.

A bypass circuit 15 branches from the second expansion device 6 to the liquid side connection refrigerant pipe 9, and the other end is connected to a refrigerant pipe between the switching valve 2 and the compressor 1. A dryer 17 provided in the piping of the circuit 15; a bypass throttle device (hereinafter referred to as a third throttle device) provided downstream of the dryer 16 in the piping of the bypass circuit 15;
18a is a first bypass heat exchanger in which a portion of the bypass circuit 15 downstream of the third expansion device 17 and a portion between the second expansion device 6 and the heat source device side heat exchanger 3 exchange heat. 1
Reference numeral 8b denotes a second bypass heat exchanger in which a portion of the bypass circuit 15 downstream of the third expansion device 17 and a portion between the second expansion device 6 and the liquid-side connection refrigerant pipe 9 exchange heat.
Is a first temperature detecting means provided in a portion of the bypass circuit 15 at a position upstream of the expansion device 17, and reference numeral 20 is a temperature of the first and second bypass heats downstream of the expansion device 17 and a portion of the bypass circuit 15. Second temperature detecting means 21 provided at a portion upstream of the exchangers 18a, 18b is a suction pressure detecting means provided at a portion between the switching valve 2 and the compressor 1.

Next, the flow of the refrigerant will be described with reference to the drawings.
First, during cooling, the gas refrigerant compressed to a high temperature and a high pressure by the compressor 1 flows into the heat source device side heat exchanger 3 through the switching valve 2 and exchanges heat with air or the like to be condensed. It becomes a refrigerant. Further, the air reaches the indoor units B, C, and D through the second expansion device 6 and the liquid-side connection refrigerant pipe 9 that are fully opened during cooling, and reaches the indoor units B, C, and D. First aperture devices 8b, 8 controlled to be within a certain range
By c and 8d, the pressure is reduced to a low-pressure gas-liquid two-phase state.
The low-pressure gas-liquid two-phase refrigerant is supplied to the indoor unit side heat exchangers 7b, 7c, 7
d, gas exchanges with the indoor air by heat exchange, and returns to the compressor 1 via the gas side connection refrigerant pipe 10, the switching valve 2, and the accumulator 4. The refrigerating machine oil inside the accumulator 4 returns to the compressor 1 through the oil return hole 5 together with the liquid refrigerant.

A part of the liquid refrigerant that has passed through the second expansion device 6 in the fully opened state from the heat source unit side heat exchanger 3 flows into the bypass circuit 15. In the bypass circuit 15, the pressure is reduced to a low pressure by the third expansion device 17 via the dryer 16, and becomes a low-temperature low-pressure gas-liquid two-phase refrigerant. The low-temperature and low-pressure gas-liquid two-phase refrigerant is connected to the high-temperature and high-pressure liquid refrigerant exiting the heat-source-unit-side heat exchanger 3 and the high-temperature and high-pressure refrigerant exiting the second expansion device 6 in the bypass heat exchangers 18a and 18b. The refrigerant exchanges heat with the liquid refrigerant, gasifies, and joins the refrigerant that has passed through the indoor units B, C, and D between the switching valve 2 and the compressor 1 and returns to the compressor 1. On the other hand, the liquid refrigerant that has exited the heat source unit side heat exchanger 3 is cooled by the first bypass heat exchanger 18a, and the liquid refrigerant that flows into the bypass circuit 15 has a higher temperature than the liquid refrigerant that has exited the heat source unit side heat exchanger 3. Decrease. The refrigerant further passes through the second expansion device 6 and is cooled by the second bypass heat exchanger 18b, and the liquid refrigerant flowing into the liquid-side connection refrigerant pipe 9 is sufficiently supercooled. Therefore, even if the length of the liquid-side connection refrigerant pipe 9 is long and the pressure drop of the refrigerant is large while flowing through the pipe, the indoor units B, C, and D are also connected to the heat source unit A.
The refrigerant flowing into the first expansion devices 8a, 8b, 8c can maintain the liquid state even when the influence of the gravity of the liquid refrigerant in the liquid-side connection refrigerant pipe installed above is large, and the stable operation can be achieved. Is possible.

At the time of heating, the gas refrigerant compressed to a high temperature and a high pressure by the compressor 1 reaches the indoor units B, C and D via the switching valve 2 and the gas side connection refrigerant pipe 10, and the indoor unit side heat exchanger. It flows into 7b, 7c, 7d, exchanges heat with indoor air and condenses, and becomes a high-temperature and high-pressure liquid refrigerant. Indoor heat exchanger 7
The liquid refrigerant that has exited b, 7c, and 7d is slightly depressurized by the first expansion devices 7b, 7c, and 7d that are almost fully open during heating, reaches the second expansion device 6 via the liquid-side connection refrigerant pipe 9, and Here, the pressure is reduced to a low-pressure gas-liquid two-phase state. The low-pressure gas-liquid two-phase refrigerant flows into the heat source-side heat exchanger 3, exchanges heat with air or the like to gasify, and returns to the compressor 1 via the switching valve 2 and the accumulator 4. The refrigerating machine oil inside the accumulator 4 returns to the compressor 1 through the oil return hole 5 together with the liquid refrigerant.

The indoor unit side heat exchangers 7b, 7c, 7d
A part of the liquid refrigerant that has passed through the first expansion devices 8a, 8b, 8c and the liquid-side connection refrigerant pipe 9 in the fully opened state flows into the bypass circuit 15. In the bypass circuit 15, the pressure is reduced to a low pressure by the third expansion device 17 via the dryer 16, and becomes a low-temperature low-pressure gas-liquid two-phase refrigerant. The low-temperature and low-pressure gas-liquid two-phase refrigerant is supplied to the high-temperature and high-pressure liquid refrigerant exiting the liquid-side connection refrigerant pipe 9 at the bypass heat exchanger 18b and to the second refrigerant at the bypass heat exchanger 18a.
Heat exchanges with the low-pressure gas-liquid two-phase refrigerant throttled by the expansion device 6, gasifies, and merges with the refrigerant that has passed through the heat source device side heat exchanger 3 between the switching valve 2 and the compressor 1; Return to the compressor 1. On the other hand, the liquid refrigerant that has exited the liquid-side connection refrigerant pipe 9 is cooled by the second bypass heat exchanger 18b, and the temperature of the liquid refrigerant that flows into the bypass circuit 15 is lower than that of the liquid refrigerant that has exited the liquid-side connection refrigerant pipe 9. However, the refrigerant flowing into the second expansion device 6 can maintain a liquid state, and stable operation is possible.

Next, the operation of the dryer 16 will be described. The moisture contained in the refrigerant / refrigerant oil discharged from the compressor 1 does not change until it reaches the starting point of the bypass circuit 15 if it is equal to or lower than the saturation upper limit. From this point, in the main refrigerant circuit reaching the junction with the bypass circuit 15 via the switching valve 2 through the indoor heat exchangers 7b, 7c and 7d during cooling, and via the heat source unit side heat exchanger 3 during heating during heating. After that, the moisture contained in the refrigerant / refrigeration oil does not change. On the other hand, in the bypass circuit 15, when the refrigerant / refrigeration oil flows into the dryer 16, the moisture is absorbed there, and the water content in the refrigerant / refrigeration oil decreases downstream of the dryer 16. At the point where the refrigerant / refrigerant oil flowing through the bypass circuit 15 between the switching valve 2 and the compressor 1 and the refrigerant / refrigerant oil flowing through the main refrigerant circuit merge, the refrigerant / refrigerant oil flowing through the main refrigerant circuit up to that point The moisture contained and the moisture contained in the refrigerant / refrigeration oil flowing through the bypass circuit 15 are mixed, and the moisture after merging is smaller than the water content contained in the refrigerant / refrigeration oil flowing through the main refrigerant circuit. The amount decreases at that concentration. That is, moisture is absorbed by the dryer 16 in the bypass circuit 15, and the moisture content in the refrigerant circuit decreases.

In this embodiment, the moisture adsorption speed is lower than when a dryer is provided in the main refrigerant circuit.
Since the rate of hydrolysis and degradation of the polyester oil is low, hydrolysis is sufficiently suppressed by the moisture adsorption ability of the dryer 16 in the piping of the bypass circuit 15, and the generation of sludge components in the compressor 1 can be suppressed. Further, by providing the dryer 16 in the middle of the piping of the bypass circuit 15, the impact of the refrigerant flow flowing through the dryer 16 can be reduced, and the dryer 16 is less likely to be crushed. In addition, the first,
Since the refrigerant flowing into the dryer 16 is cooled by the second bypass heat exchangers 18a and 18b, the refrigerant flowing into the dryer 16 is in a liquid state even when the compressor 1 is started or during a transient operation such as defrost. Dryer 1
6 becomes more difficult to grind. Further, when the temperature of the refrigerant is low, the water has a low saturation of water solubility in the refrigerant, and in the coexistence with the dryer, the water moves relatively easily to the dryer than in the refrigerant, and the moisture adsorption capacity of the dryer increases. Therefore, as the temperature of the refrigerant flowing into the dryer 16 decreases, the amount of water adsorbed by the dryer 16 increases accordingly, and hydrolysis of the refrigerating machine oil can be suppressed.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 shows the second embodiment.
FIG. 2 is a refrigerant circuit diagram of the air conditioner according to FIG. In the figure, A is a heat source unit, B, C, D are indoor units, 1 is a compressor, 2
Is a switching valve, 3 is a heat exchanger on the heat source side, and 4 is an accumulator.
And 5 are oil return holes of the accumulator 4, 6 is a second expansion device, 7b, 7c and 7d are indoor unit side heat exchangers, 8b and 8
c and 8d are first expansion devices, 9 is a liquid side connection refrigerant pipe, 1
Reference numeral 0 denotes a gas-side connection refrigerant pipe, which is the same as the conventional example shown in FIG.

Reference numeral 15 denotes a bypass circuit which branches from the second throttle device 6 and the liquid-side connection refrigerant pipe 9, and the other end is connected to a refrigerant pipe between the switching valve 2 and the compressor 1. A dryer 17 provided in the piping of the circuit 15, a third throttle device provided downstream of the dryer 16 in the piping of the bypass circuit 15, a portion upstream of the dryer 16 in the bypass circuit 15 and the switching valve 2. A bypass heat exchanger for exchanging heat between the heat exchanger and the accumulator 4; 19, a first temperature detecting means provided at a portion of the bypass circuit 15 upstream of the expansion device 17 in the piping; A second temperature detecting means 21 provided downstream of the expansion device 17 in the piping of the circuit 15 is a suction pressure detecting means provided at a portion between the switching valve 2 and the compressor 1.

Next, the flow of the refrigerant will be described with reference to the drawings.
Main refrigerant comprising compressor 1, switching valve 2, heat source unit side heat exchanger 3, second expansion unit 6, first expansion units 8b, 8c, 8d, and indoor unit side heat exchangers 7b, 7c, 7d The flow of the refrigerant at the time of cooling and heating of the circuit is completely the same as that of the first embodiment, and therefore the description is omitted, and the flow of the refrigerant in the bypass circuit 15 will be described.

During cooling, the heat passes from the heat source unit side heat exchanger 3 to the fully expanded second expansion device 6, and during heating, the indoor unit side heat exchangers 7b, 7c, 7d open to the fully expanded first expansion device 8.
a, 8b, 8c, and a part of the liquid refrigerant that has passed through the liquid side connection refrigerant pipe 9 flows into the bypass circuit 15. Bypass circuit 15
Liquid refrigerant flowing into the switching valve 2 by the bypass heat exchanger 18
The heat is exchanged with the low-temperature and low-pressure refrigerant that has passed through, and the temperature of the refrigerant is reduced. The low-temperature, low-pressure gas-liquid two-phase refrigerant joins the refrigerant in the main refrigerant circuit that has passed through the switching valve 2 between the switching valve 2 and the accumulator 4, and
To return to the compressor 1.

Next, the operation of the dryer 16 will be described. The moisture contained in the refrigerant / refrigerant oil discharged from the compressor 1 does not change until it reaches the starting point of the bypass circuit 15 if it is equal to or lower than the saturation upper limit. From this point, in the main refrigerant circuit reaching the junction with the bypass circuit 15 via the switching valve 2 through the indoor heat exchangers 7b, 7c and 7d during cooling, and via the heat source unit side heat exchanger 3 during heating during heating. After that, the moisture contained in the refrigerant / refrigeration oil does not change. On the other hand, in the bypass circuit 15, when the refrigerant / refrigeration oil flows into the dryer 16, the moisture is absorbed there, and the water content in the refrigerant / refrigeration oil decreases downstream of the dryer 16. At the point where the refrigerant / refrigerant oil flowing through the bypass circuit 15 between the switching valve 2 and the compressor 1 and the refrigerant / refrigerant oil flowing through the main refrigerant circuit merge, the refrigerant / refrigerant oil flowing through the main refrigerant circuit up to that point The moisture contained and the moisture contained in the refrigerant / refrigeration oil flowing through the bypass circuit 15 are mixed, and the moisture after merging is smaller than the water content contained in the refrigerant / refrigeration oil flowing through the main refrigerant circuit. The amount decreases at that concentration. That is, moisture is absorbed by the dryer 16 in the bypass circuit 15, and the moisture content in the refrigerant circuit decreases.

In this embodiment as well, the moisture adsorption speed is lower than when a dryer is provided in the main refrigerant circuit.
Since the rate of hydrolysis and degradation of the polyester oil is low, hydrolysis is sufficiently suppressed by the moisture adsorption ability of the dryer 16 in the piping of the bypass circuit 15, and the generation of sludge components in the compressor 1 can be suppressed. Further, by providing the dryer 16 in the middle of the piping of the bypass circuit 15, the impact of the refrigerant flow flowing through the dryer 16 can be reduced, and the dryer 16 is less likely to be crushed. Further, since the refrigerant flowing into the dryer 16 is cooled by the bypass heat exchanger 18, the refrigerant flowing into the dryer 16 can be easily changed to a liquid state even at the time of starting the compressor 1 or during a transient operation such as defrost. The dryer 16 is more difficult to pulverize. Further, when the temperature of the refrigerant is low, the water has a low saturation of water solubility in the refrigerant, and in the coexistence with the dryer, the water moves relatively easily to the dryer than in the refrigerant, and the moisture adsorption capacity of the dryer increases. Therefore, as the temperature of the refrigerant flowing into the dryer 16 decreases, the amount of water adsorbed by the dryer 16 increases accordingly, and hydrolysis of the refrigerating machine oil can be suppressed.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 shows the third embodiment.
FIG. 2 is a refrigerant circuit diagram of the air conditioner according to FIG. In the figure, A is a heat source unit, B, C, D are indoor units, 1 is a compressor, 2
Is a switching valve, 3 is a heat exchanger on the heat source side, and 4 is an accumulator.
And 5 are oil return holes of the accumulator 4, 6 is a second expansion device, 7b, 7c and 7d are indoor unit side heat exchangers, 8b and 8
c and 8d are first expansion devices, 9 is a liquid side connection refrigerant pipe, 1
Reference numeral 0 denotes a gas-side connection refrigerant pipe, which is the same as the conventional example shown in FIG.

A bypass circuit 15 branches from the second throttle device 6 to the liquid side connection refrigerant pipe 9, and the other end is connected to a refrigerant pipe between the switching valve 2 and the compressor 1. A dryer 17 provided in the middle of the piping of the circuit 15 is a third expansion device provided downstream of the dryer 16 in the middle of the piping of the bypass circuit 15, and a portion upstream of the dryer 16 in the bypass circuit 15 is connected to a heat source device. A bypass heat exchanger for exchanging heat with a part of the air flowing into the lowermost portion of the side heat exchanger 3, a first heat exchanger 19 provided at a portion upstream of the expansion device 17 in the piping of the bypass circuit 15. Temperature detection means,
Reference numeral 20 denotes a second temperature detecting means provided downstream of the expansion device 17 in the middle of the piping of the bypass circuit 15, and reference numeral 21 denotes a switching valve 2.
Suction pressure detecting means provided at a portion between the compressor and the compressor 1.

Next, the flow of the refrigerant will be described with reference to the drawings.
Main refrigerant comprising compressor 1, switching valve 2, heat source unit side heat exchanger 3, second expansion unit 6, first expansion units 8b, 8c, 8d, and indoor unit side heat exchangers 7b, 7c, 7d The flow of the refrigerant at the time of cooling and heating of the circuit is completely the same as that of the first embodiment, and therefore the description is omitted, and the flow of the refrigerant in the bypass circuit 15 will be described.

During cooling, the heat passes from the heat source unit side heat exchanger 3 to the second expansion unit 6 which is fully opened, and during heating, the indoor unit side heat exchangers 7b, 7c, 7d open the first expansion unit 8 which is fully opened.
a, 8b, 8c, and a part of the liquid refrigerant that has passed through the liquid side connection refrigerant pipe 9 flows into the bypass circuit 15. Bypass circuit 15
Is cooled by the bypass heat exchanger 18 with a part of the air flowing into the lowermost portion of the heat source device side heat exchanger 3, the temperature of the liquid refrigerant is reduced, and the liquid refrigerant passes through the dryer 16 to the third expansion device. 1
At 7, the pressure is reduced to a low pressure and becomes a low-temperature low-pressure gas-liquid two-phase refrigerant.
The low-temperature and low-pressure gas-liquid two-phase refrigerant joins the refrigerant of the main refrigerant circuit that has passed through the switching valve 2 between the switching valve 2 and the accumulator 4, separates gas and liquid by the accumulator 4, and returns to the compressor 1.
In the lowermost part of the heat source device side heat exchanger 3 provided with the bypass heat exchanger 18 which becomes an evaporator at the time of heating, the flow of the drain from the upper part makes it difficult for the wind to pass through, and frost is easily generated and grows. The frost is heated by the bypass heat exchanger 18 and frost formation is less likely.

In the third embodiment as well, a dryer 16 for absorbing moisture is provided in the bypass circuit 15, and the refrigerant flowing into the dryer 16 is cooled by the bypass heat exchanger 18, which is the same as in the first and second embodiments. In addition, the water content in the refrigerant circuit is reduced, so that the hydrolysis of the refrigerating machine oil can be suppressed, and the dryer 16 can be prevented from being crushed by the refrigerant flow.

Embodiment 4 FIG. Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 shows the fourth embodiment.
FIG. 2 is a refrigerant circuit diagram of the air conditioner according to FIG. In the figure, A is a heat source unit, B, C, D are indoor units, 1 is a compressor, 2
Is a switching valve, 3 is a heat exchanger on the heat source side, and 4 is an accumulator.
And 5 are oil return holes of the accumulator 4, 6 is a second expansion device, 7b, 7c and 7d are indoor unit side heat exchangers, 8b and 8
c and 8d are first expansion devices, 9 is a liquid side connection refrigerant pipe, 1
Reference numeral 0 denotes a gas-side connection refrigerant pipe, which is the same as the conventional example shown in FIG.

Reference numeral 15 denotes a bypass circuit which branches from the discharge section of the compressor 1 and the switching valve 2, and the other end is connected to a refrigerant pipe between the switching valve 2 and the compressor 1. The dryer provided in the middle of the piping, 17 is the bypass circuit 1
The third throttle device 18 provided downstream of the dryer 16 in the middle of the pipe 5 includes a portion upstream of the dryer 16 of the bypass circuit 15 and a third throttle device 17 of the bypass circuit 15.
A bypass heat exchanger for exchanging heat with a downstream portion, 19
Reference numeral 20 denotes a first temperature detecting means provided in a portion of the bypass circuit 15 upstream of the expansion device 17 in the piping, and reference numeral 20 denotes a second temperature detection device provided downstream of the expansion device 17 of the bypass circuit 15 in the piping. , 21 are second pressure detecting means provided in a portion between the switching valve 2 and the compressor 1.

Next, the flow of the refrigerant will be described with reference to the drawings.
Main refrigerant comprising compressor 1, switching valve 2, heat source unit side heat exchanger 3, second expansion unit 6, first expansion units 8b, 8c, 8d, and indoor unit side heat exchangers 7b, 7c, 7d The flow of the refrigerant at the time of cooling and heating of the circuit is completely the same as that of the first embodiment, and therefore the description is omitted, and the flow of the refrigerant in the bypass circuit 15 will be described.

In both cooling and heating, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the bypass circuit 15. The high-temperature and high-pressure gas refrigerant that has flowed into the bypass circuit 15 exchanges heat with the downstream low-pressure refrigerant in the bypass heat exchanger 18 to lower the temperature and liquefy, and passes through the dryer 16 to the third expansion device 17. The refrigerant is decompressed to a low pressure to become a low-temperature low-pressure gas-liquid two-phase refrigerant, and is gasified by exchanging heat with the high-pressure refrigerant in the bypass heat exchanger 18. The low-temperature and low-pressure gas refrigerant merges with the refrigerant in the main refrigerant circuit that has passed through the switching valve 2 between the switching valve 2 and the accumulator 4, performs gas-liquid separation in the accumulator 4, and returns to the compressor 1.

Also in the fourth embodiment, a dryer 16 for absorbing moisture is provided in the bypass circuit 15, and the refrigerant flowing into the dryer 16 is cooled by the bypass heat exchanger 18, so that the first, second and third embodiments are performed. Similarly to the case described above, the water content in the refrigerant circuit is reduced, the hydrolysis of the refrigerating machine oil can be suppressed, and the pulverization of the dryer 16 by the refrigerant flow can be prevented. Further, in the fourth embodiment, since the cycle of returning from the compressor 1 to the compressor 1 through the bypass circuit 15 is very short, the responsiveness is good, and the transient state in which the liquid is not supplied to the dryer is obtained. Very short, dryer 1
6 is hard to crush. Further, since this cycle does not include the liquid-side connection refrigerant pipe 9 and the gas-side connection refrigerant pipe 10, oxidation that occurs when sufficient non-oxidation brazing is not performed when these pipes 9 and 10 are constructed. The scale does not flow into the dryer 16 in the bypass circuit 15, thereby eliminating the risk of blocking the flow path and crushing the dryer.

Embodiment 5 Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 shows the fifth embodiment.
FIG. 2 is a refrigerant circuit diagram of the air conditioner according to FIG. In the figure, A is a heat source unit, B, C, D are indoor units, 1 is a compressor, 2
Is a switching valve, 3 is a heat exchanger on the heat source side, and 4 is an accumulator.
And 5 are oil return holes of the accumulator 4, 6 is a second expansion device, 7b, 7c and 7d are indoor unit side heat exchangers, 8b and 8
c and 8d are first expansion devices, 9 is a liquid side connection refrigerant pipe, 1
Reference numeral 0 denotes a gas-side connection refrigerant pipe, which is the same as the conventional example shown in FIG.

A bypass circuit 15 branches from between the compressor 1 and the switching valve 2, and the other end is connected to a refrigerant pipe between the switching valve 2 and the compressor 1. The dryer 17 provided is a third expansion device provided downstream of the dryer 16 in the middle of the piping of the bypass circuit 15, and the portion 18 upstream of the dryer 16 of the bypass circuit 15 and the heat exchanger 3 A bypass heat exchanger for exchanging heat with a part of the air flowing into the lowermost portion; 19, a first temperature detecting means provided at a portion upstream of the expansion device 17 in the piping of the bypass circuit 15; A second temperature detecting means 21 provided downstream of the expansion device 17 in the middle of the piping of the bypass circuit 15 is a second pressure detecting means provided at a portion between the switching valve 2 and the compressor 1.

Next, the flow of the refrigerant will be described with reference to the drawings.
Main refrigerant comprising compressor 1, switching valve 2, heat source unit side heat exchanger 3, second expansion unit 6, first expansion units 8b, 8c, 8d, and indoor unit side heat exchangers 7b, 7c, 7d The flow of the refrigerant at the time of cooling and heating of the circuit is completely the same as that of the first embodiment, and therefore the description is omitted, and the flow of the refrigerant in the bypass circuit 15 will be described.

In both cases of cooling and heating, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the bypass circuit 15. The high-temperature and high-pressure gas refrigerant that has flowed into the bypass circuit 15 exchanges heat with a part of the air that flows into the lowermost part of the heat source unit side heat exchanger 3 in the bypass heat exchanger 18 so that the temperature is reduced and liquefied. After the dryer 16, the third
The pressure is reduced to a low pressure by the throttle device 17, and the refrigerant merges with the refrigerant in the main refrigerant circuit passing through the switching valve 2 between the switching valve 2 and the accumulator 4, and is separated into gas and liquid by the accumulator 4 and returns to the compressor 1. In addition, also in this Embodiment 5, similarly to Embodiment 3,
At the bottom of the heat-source-unit-side heat exchanger 3 provided with the bypass heat exchanger 18 serving as an evaporator at the time of heating, the flow of the drain from the top makes it difficult for the wind to pass through, and frost is easily generated and grows. It is heated by the heat exchanger 18 and hardly forms frost.

Also in the fifth embodiment, a dryer 16 for absorbing moisture is provided in the bypass circuit 15, and the refrigerant flowing into the bypass circuit 15 is cooled by the bypass heat exchanger 18, which is the same as in the first to fourth embodiments. In addition, the amount of water contained in the refrigerant circuit is reduced, so that hydrolysis of the refrigerating machine oil can be suppressed, and pulverization of the dryer 16 by the refrigerant flow can be prevented. Further, similarly to the fourth embodiment, since the cycle of returning from the compressor 1 to the compressor 1 through the bypass circuit 15 is very short, the responsiveness is good, and the time required for a transient state in which the liquid is not supplied to the dryer is obtained. It is very short and the dryer 16 is hard to be crushed. Further, since this cycle does not include the liquid-side connection refrigerant pipe 9 and the gas-side connection refrigerant pipe 10, oxidation that occurs when sufficient non-oxidation brazing is not performed when these pipes 9 and 10 are constructed. The scale does not flow into the dryer 16 in the bypass circuit 15, thereby eliminating the risk of blocking the flow path and crushing the dryer.

Embodiment 6 FIG. Hereinafter, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 6 shows the sixth embodiment.
FIG. 2 is a refrigerant circuit diagram of the air conditioner according to FIG. In the figure, A is a heat source unit, B, C, D are indoor units, 1 is a compressor, 2
Is a switching valve, 3 is a heat exchanger on the heat source side, and 4 is an accumulator.
And 5 are oil return holes of the accumulator 4, 6 is a second expansion device, 7b, 7c and 7d are indoor unit side heat exchangers, 8b and 8
c and 8d are first expansion devices, 9 is a liquid side connection refrigerant pipe, 1
Reference numeral 0 denotes a gas-side connection refrigerant pipe, which is the same as the conventional example shown in FIG.

A bypass circuit 15 branches from between the compressor 1 and the switching valve 2, and the other end is connected to a refrigerant pipe between the switching valve 2 and the compressor 1. The provided dryer, 17 is a third expansion device provided downstream of the dryer 16 in the middle of the piping of the bypass circuit 15, and 18a is a portion of the bypass circuit 15 upstream of the dryer 16 and the heat source unit side heat exchanger 3. A first bypass heat exchanger in which a part of the air flowing into the lowermost part exchanges heat;
Reference numeral 18b denotes a second bypass heat exchanger in which a portion of the bypass circuit 15 between the first bypass heat exchanger 18a and the dryer 16 and a portion downstream of the third expansion device 17 exchange heat. Throttling device 1 in piping of bypass circuit 15
First temperature detecting means provided at a portion upstream of 7;
Reference numeral 0 denotes second temperature detecting means provided downstream of the expansion device 17 in the piping of the bypass circuit 15, and reference numeral 21 denotes second pressure detecting means provided at a portion between the switching valve 2 and the compressor 1. is there.

Next, the flow of the refrigerant will be described with reference to the drawings.
Main refrigerant comprising compressor 1, switching valve 2, heat source unit side heat exchanger 3, second expansion unit 6, first expansion units 8b, 8c, 8d, and indoor unit side heat exchangers 7b, 7c, 7d The flow of the refrigerant at the time of cooling and heating of the circuit is completely the same as that of the first embodiment, and therefore the description is omitted, and the flow of the refrigerant in the bypass circuit 15 will be described.

In both cases of cooling and heating, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the bypass circuit 15. The high-temperature and high-pressure gas refrigerant flowing into the bypass circuit 15 is supplied to the first bypass heat exchanger 18.
In (a), heat exchange occurs with a part of the air flowing into the lowermost portion of the heat source unit side heat exchanger 3 to lower the temperature and liquefy, and the second bypass heat exchanger 18b exchanges heat with the downstream low pressure side refrigerant. As a result, the temperature of the refrigerant further decreases. After that, through the dryer 16,
The pressure is reduced to a low pressure by the third expansion device 17 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. The refrigerant merges with the refrigerant in the main refrigerant circuit passing through the valve 2, is separated into gas and liquid by the accumulator 4, and returns to the compressor 1. In the sixth embodiment, as in the third embodiment, the lowermost part of the heat source unit side heat exchanger 3 provided with the first bypass heat exchanger 18a, which serves as an evaporator at the time of heating, is provided from above. The flow of the drain makes it difficult for the wind to pass through, and frost is generated and grows easily. However, it is heated by the bypass heat exchanger 18 and hardly formed.

In the sixth embodiment as well, a dryer 16 for absorbing moisture is provided in the bypass circuit 15, and the refrigerant flowing into the dryer 16 is cooled by the bypass heat exchangers 18a and 18b. Similarly to the case described above, the water content in the refrigerant circuit is reduced, the hydrolysis of the refrigerating machine oil can be suppressed, and the pulverization of the dryer 16 by the refrigerant flow can be prevented. Further, similarly to the fourth and fifth embodiments, the cycle of returning from the compressor 1 to the compressor 1 through the bypass circuit 15 is very short, so that the responsiveness is good and a transient state occurs in which the liquid is not supplied to the dryer. The time is very short, and the dryer 16 is hard to be crushed. Further, since this cycle does not include the liquid-side connection refrigerant pipe 9 and the gas-side connection refrigerant pipe 10, oxidation that occurs when sufficient non-oxidation brazing is not performed when these pipes 9 and 10 are constructed. The scale does not flow into the dryer 16 in the bypass circuit 15, thereby eliminating the risk of blocking the flow path and crushing the dryer.

Embodiment 7 Hereinafter, a seventh embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a refrigerant circuit diagram of an air conditioner according to the seventh embodiment, FIG. 7 is a block diagram relating to composition calculation of the air conditioner according to the seventh embodiment, and FIG. This is a flowchart. 2 to 6 differ from each other in the position, configuration, and refrigerant flow of the bypass circuit 15, but the seventh embodiment is applied similarly to FIG. Further, as a working medium in this embodiment, hydrofluorocarbon is used.
A Bonn-based mixed refrigerant is used.

In the figure, reference numeral 19 designates a portion provided upstream of the expansion device 17 in the piping of the bypass circuit 15,
A first temperature detecting means 20 for detecting the temperature of the high-temperature and high-pressure liquid refrigerant at the inlet of the expansion device 17; 18a, 18b provided in the upstream portion,
A second temperature detecting means 21 for detecting the temperature of the low-temperature low-pressure gas-liquid two-phase refrigerant at the outlet of the third expansion device 17 is provided at a portion between the switching valve 2 and the compressor 1. The pressure detecting means 22 is a composition calculating means for calculating the composition of the mixed refrigerant based on the detection values of the first temperature detecting means 19, the second temperature detecting means 20, and the second pressure detecting means 21. .

Next, the composition calculation operation will be described with reference to FIG. First, in step 100, the composition Xi of each component of the mixed refrigerant is assumed. In step 101, the first temperature detecting means 19 and the second temperature detecting means 2
0, the respective detected values T1, T
2, P2 is detected. In step 102, the high-pressure liquid enthalpy H1 is calculated from the circulation composition Xi assumed in step 100 and the detection value T1 of the first temperature detecting means 19 described above. In step 103, a low-pressure two-phase enthalpy H2 is calculated from the circulation composition Xi, the detected value T2 of the second temperature detecting means 20, and the detected value P2 of the suction pressure detecting means 21. In step 104, the above H1 and H2 are compared, and the assumption of the circulation composition is repeated until they are equal. As a result, the value of Xi at the time when H1 and H2 become equal is calculated as the circulation composition. Here, the subscript i indicates that the refrigerant is a mixture of i kinds of components.

Embodiment 8 FIG. Hereinafter, an eighth embodiment of the present invention will be described with reference to FIG. FIG. 9 shows this eighth embodiment.
FIG. 2 is a refrigerant circuit diagram of the air conditioner according to FIG. In the figure, A is a heat source unit, B, C, D are indoor units, 1 is a compressor, 2
Is a switching valve, 3 is a heat exchanger on the heat source side, and 4 is an accumulator.
And 5 are oil return holes of the accumulator 4, 7b, 7c, 7
d is an indoor unit side heat exchanger, 8b, 8c and 8d are first expansion devices, 9 is a liquid side connection refrigerant pipe, 10 is a gas side connection refrigerant pipe, and the above is the same as the conventional example shown in FIG. It is.
23 is provided between the discharge part of the compressor 1 and the switching valve 2,
An oil separator that separates the refrigerating machine oil discharged together with the refrigerant from the compressor 1 from the gas refrigerant; Oil return bypass circuit for returning oil to the suction section of the compressor 1, 2
5 is a fourth oil pump provided in the middle of the piping of the oil return bypass circuit 24.
Of the diaphragm device.

Next, the flow of the refrigerant will be described with reference to the drawings.
First, during cooling, the gas refrigerant compressed to a high temperature and a high pressure by the compressor 1 flows into the heat source device side heat exchanger 3 through the switching valve 2 and exchanges heat with air or the like to be condensed. It becomes a refrigerant. Further, the refrigerant flows through the liquid-side connection refrigerant pipe 9 to reach the indoor units B, C, and D, and the indoor-unit-side heat exchangers 7b, 7c, 7d
Is controlled so that the degree of superheat at the outlet of the tank is within a certain range.
Are narrowed down to a low-pressure gas-liquid two-phase state by the throttle devices 8b, 8c, 8d. The low-pressure gas-liquid two-phase refrigerant flows into the indoor unit-side heat exchangers 7b, 7c, 7d, exchanges heat with indoor air and gasifies, and connects the gas-side connecting refrigerant pipe 10, the switching valve 2, the accumulator 4, and the like. And returns to the compressor 1. The refrigerating machine oil inside the accumulator 4 returns to the compressor 1 through the oil return hole 5 together with the liquid refrigerant.

At the time of heating, the gas refrigerant compressed to a high temperature and a high pressure by the compressor 1 reaches the indoor units B, C and D via the switching valve 2 and the gas side connection refrigerant pipe 10, and the indoor unit side heat exchanger. It flows into 7b, 7c, 7d, exchanges heat with indoor air and condenses, and becomes a high-temperature and high-pressure liquid refrigerant. Indoor heat exchanger 7
The liquid refrigerant that has exited b, 7c, 7d is supplied to the first throttle device 8b, 8
The low-pressure gas-liquid two-phase refrigerant is throttled to the low-pressure gas-liquid two-phase state at c and 8d. The gas returns to the compressor 1 via the switching valve 2 and the accumulator 4. The refrigerating machine oil inside the accumulator 4 is returned to the oil return hole 5 together with the liquid refrigerant.
Return to the compressor 1.

In both cases of cooling and heating, the low-temperature and low-pressure gas refrigerant sucked into the compressor 1 is compressed into a high-temperature and high-pressure gas refrigerant and discharged from the compressor 1. At this time, a part of the refrigerating machine oil inside the compressor 1 is also discharged and flows into the oil separator 23 together with the gas refrigerant, where it is separated from the gas refrigerant. The gas refrigerant separated by the oil separator 23 flows to the switching valve 2, and the refrigeration oil flows into the oil return bypass circuit 24. The refrigerating machine oil that has flowed into the oil return bypass circuit 24 is reduced in pressure to a low pressure by the fourth expansion device 25, and merges with the refrigerant in the main refrigerant circuit that has passed through the switching valve 2 between the switching valve 2 and the accumulator 4. Since the refrigerating machine oil is separated at the discharge part of the compressor 1 in this manner, the circulating flow ratio of the refrigerating machine oil in the main refrigerant circuit is very low, and the first expansion devices 8b, 8b, The flow rate of the refrigerating machine oil flowing through 8c and 8d is significantly reduced.

The refrigerating machine oil degraded product generated in the sliding part of the compressor 1 exists as a solid or is dissolved in the refrigerating machine oil. When the refrigerant is discharged from the compressor 1, the refrigerant is discharged together with the refrigerating machine oil in the discharge gas, but is separated by the oil separator 23 and does not flow into the main refrigerant circuit. The flow rate of the refrigerating machine oil flowing through the first expansion devices 8b, 8c, and 8d inside the refrigerating machine significantly decreases, and the integrated flow rate of the refrigerating machine oil degraded material circulating together with the refrigerating machine oil also decreases. As a result, the amount of the deteriorated refrigerating machine oil that becomes sludge and adheres to the first expansion devices 8b, 8c, 8d is reduced, and accordingly, the first expansion devices 8b, 8c, 8d are reduced.
Insufficient flow rate can be avoided, air conditioning capacity can be avoided, and reliability can be significantly improved.

Embodiment 9 Hereinafter, a ninth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a refrigerant circuit diagram of an air conditioner according to the ninth embodiment. In the figure, A is a heat source unit, B, C, and D are indoor units, 1 is a compressor,
2 is a switching valve, 3 is a heat source side heat exchanger, and 4 is an accumulator.
And 5 are oil return holes of the accumulator 4, 7b, 7c, 7
d is an indoor unit side heat exchanger, 8b, 8c and 8d are first expansion devices, 9 is a liquid side connection refrigerant pipe, 10 is a gas side connection refrigerant pipe, 23 is an oil separator, 24 is an oil return bypass circuit, Reference numeral 25 denotes a fourth diaphragm device, which is the same as that of the eighth embodiment shown in FIG. Reference numeral 26 denotes a sludge filter provided upstream of the fourth expansion device 25 in the piping of the oil return bypass circuit 24.

Next, the flow of the refrigerant and the refrigerating machine oil will be described with reference to the drawings. At the time of cooling of the main refrigerant circuit including the compressor 1, the switching valve 2, the heat source unit side heat exchanger 3, the first expansion devices 8b, 8c, 8d, and the indoor unit side heat exchangers 7b, 7c, 7d,
The flow of the refrigerant at the time of heating and the operation of the oil separator 23 are exactly the same as those in the eighth embodiment, and therefore the description is omitted, and the flow of the refrigerating machine oil in the oil return bypass circuit 24 will be described. Oil separator 2
The refrigerating machine oil separated in 3 flows into the oil return bypass circuit 24, passes through the sludge filter 26, and passes through the fourth expansion device 25.
The pressure in the main refrigerant circuit passes through the switching valve 2 and merges between the switching valve 2 and the accumulator 4.

The deteriorated refrigerating machine oil produced in the sliding portion of the compressor 1 is mixed with the refrigerating machine oil in the discharge gas and discharged into the refrigerant circuit, separated by the oil separator 23 together with the refrigerating machine oil, and returned. In the bypass circuit 24, it is captured by the sludge filter 26. Therefore, accumulator 4
To the compressor 1 and returns to the compressor 1, the content of the refrigerating machine oil deteriorated in the refrigerating machine oil decreases, and the amount of sludge adhering to the oil return hole 5 decreases. As a result, the refrigerating machine oil inside the compressor 1 is not depleted, and abnormal high pressure rise, low pressure fall, and discharge gas temperature rise due to the abnormal rise can be avoided, and the reliability is remarkably improved. Further, the cycle in which the refrigerant discharged from the compressor 1 returns to the compressor 1 via the oil return bypass circuit 24 does not pass through the liquid side connection refrigerant pipe 9 and the gas side connection refrigerant pipe 10 on the way. Therefore, the oxidized scale generated when the sufficient non-oxidation brazing is not performed when the liquid-side connection refrigerant pipe 9 or the gas-side connection refrigerant pipe 10 is installed may flow into the sludge filter 26 during operation. Therefore, there is no danger of blocking the flow path or deforming or breaking the sludge filter.

Embodiment 10 FIG. Hereinafter, a tenth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a refrigerant circuit diagram of an air conditioner according to the tenth embodiment.
In the figure, A is a heat source unit, B, C and D are indoor units, 1 is a compressor, 2 is a switching valve, 3 is a heat source unit side heat exchanger, 4 is an accumulator, and 5 is an oil of the accumulator 4. Return hole, 7b, 7
c and 7d are indoor unit side heat exchangers, and 8b, 8c and 8d are first heat exchangers.
9 is a liquid side connection refrigerant pipe, 10 is a gas side connection refrigerant pipe, 23 is an oil separator, 24 is an oil return bypass circuit,
25 is a fourth diaphragm device, 26 is a sludge filter, which is the same as that of the ninth embodiment shown in FIG.
27 is a sludge filter 26 of the oil return bypass circuit 24
This is a bypass heat exchanger in which the upstream portion and a part of the air flowing into the lowermost portion of the heat source device side heat exchanger 3 exchange heat.

Next, the flow of the refrigerant and the refrigerating machine oil will be described with reference to the drawings. At the time of cooling of the main refrigerant circuit including the compressor 1, the switching valve 2, the heat source unit side heat exchanger 3, the first expansion devices 8b, 8c, 8d, and the indoor unit side heat exchangers 7b, 7c, 7d,
The flow of the refrigerant at the time of heating and the operation of the oil separator 23 are exactly the same as those in the eighth embodiment, and therefore the description is omitted, and the flow of the refrigerating machine oil in the oil return bypass circuit 24 will be described. Oil separator 2
The refrigerating machine oil separated in 3 flows into the oil return bypass circuit 24, and exchanges heat with a part of the air flowing into the lowermost portion of the heat source device side heat exchanger 3 in the bypass heat exchanger 27 to lower the temperature. ,
The pressure is reduced to a low pressure by the fourth expansion device 25 through the sludge filter 26, and merges with the refrigerant in the main refrigerant circuit that has passed through the switching valve 2 between the switching valve 2 and the accumulator 4. In addition,
In the tenth embodiment, as in the third, fifth, and sixth embodiments, the bypass heat exchanger 1 that serves as an evaporator during heating.
At the lowermost part of the heat source device side heat exchanger 3 provided with 8, the flow of the drain from the upper part makes it difficult for the wind to pass and frost is easily generated and grows. However, it is heated by the bypass heat exchanger 18 and hardly forms frost. Become.

The deteriorated refrigerating machine oil produced in the sliding portion of the compressor 1 is mixed with the refrigerating machine oil in the discharge gas and discharged into the refrigerant circuit, separated by the oil separator 23 together with the refrigerating machine oil, and returned. In the bypass circuit 24, it is captured by the sludge filter 26. Moreover, the bypass heat exchanger 27
, The temperature of the refrigerating machine oil decreases, and the concentration of the refrigerant in the refrigerating machine oil increases. As a result, the refrigerating machine oil deteriorated in the refrigerating machine oil is precipitated, and the sludge filter 26 can also capture what was originally dissolved in the refrigerating machine oil. Therefore, the content of degraded refrigerating machine oil in the refrigerating machine oil that flows into the accumulator 4 and returns to the compressor 1 further decreases, and the amount of sludge adhering to the oil return hole 5 decreases. Thereby, the refrigerating machine oil inside the compressor 1 is not depleted, and abnormal high pressure rise, low pressure drop,
As a result, a rise in the discharge gas temperature can be avoided, and the reliability is significantly improved. Further, the cycle in which the refrigerant discharged from the compressor 1 returns to the compressor 1 via the oil return bypass circuit 24 does not pass through the liquid side connection refrigerant pipe 9 and the gas side connection refrigerant pipe 10 on the way. Therefore, the oxidized scale generated when the sufficient non-oxidation brazing is not performed when the liquid-side connection refrigerant pipe 9 or the gas-side connection refrigerant pipe 10 is installed may flow into the sludge filter 26 during operation. Therefore, there is no danger of blocking the flow path or deforming or breaking the sludge filter.

Embodiment 11 FIG. Hereinafter, an eleventh embodiment of the present invention will be described with reference to FIG. FIG. 12 is a refrigerant circuit diagram of an air conditioner according to the eleventh embodiment.
In the figure, A is a heat source unit, B, C and D are indoor units, 1 is a compressor, 2 is a switching valve, 3 is a heat source unit side heat exchanger, 4 is an accumulator, and 5 is an oil of the accumulator 4. Return hole, 7b, 7
c and 7d are indoor unit side heat exchangers, and 8b, 8c and 8d are first heat exchangers.
9 is a liquid side connection refrigerant pipe, 10 is a gas side connection refrigerant pipe, 23 is an oil separator, 24 is an oil return bypass circuit,
25 is a fourth diaphragm device, 26 is a sludge filter, which is the same as that of the ninth embodiment shown in FIG.
27 is a sludge filter 26 of the oil return bypass circuit 24
The upstream portion and the portion between the switching valve 2 and the accumulator 4 constitute a bypass heat exchanger for exchanging heat.

Next, the flow of the refrigerant and the refrigerating machine oil will be described with reference to the drawings. At the time of cooling of the main refrigerant circuit including the compressor 1, the switching valve 2, the heat source unit side heat exchanger 3, the first expansion devices 8b, 8c, 8d, and the indoor unit side heat exchangers 7b, 7c, 7d,
The flow of the refrigerant at the time of heating and the operation of the oil separator 23 are exactly the same as those in the eighth embodiment, and therefore the description is omitted, and the flow of the refrigerating machine oil in the oil return bypass circuit 24 will be described. Oil separator 2
The refrigerating machine oil separated in 3 flows into the oil return bypass circuit 24, and exchanges heat with the low-temperature and low-pressure refrigerant returning to the compressor 1 via the switching valve 2 in the bypass heat exchanger 27, whereby the temperature is reduced and the sludge filter is reduced. The pressure is reduced to a low pressure by the fourth expansion device 25 through 26, and merges with the refrigerant in the main refrigerant circuit passing through the switching valve 2 between the switching valve 2 and the accumulator 4.

The refrigerating machine oil degraded product generated in the sliding portion of the compressor 1 is mixed with the refrigerating machine oil in the discharge gas and discharged into the refrigerant circuit, separated by the oil separator 23 together with the refrigerating machine oil, and returned. In the bypass circuit 24, it is captured by the sludge filter 26. Moreover, the bypass heat exchanger 27
, The temperature of the refrigerating machine oil decreases, and the concentration of the refrigerant in the refrigerating machine oil increases. As a result, the refrigerating machine oil deteriorated in the refrigerating machine oil is precipitated, and the sludge filter 26 can also capture what was originally dissolved in the refrigerating machine oil. Therefore, the content of degraded refrigerating machine oil in the refrigerating machine oil that flows into the accumulator 4 and returns to the compressor 1 further decreases, and the amount of sludge adhering to the oil return hole 5 decreases. Thereby, the refrigerating machine oil inside the compressor 1 is not depleted, and abnormal high pressure rise, low pressure drop,
As a result, a rise in the discharge gas temperature can be avoided, and the reliability is significantly improved. Further, the cycle in which the refrigerant discharged from the compressor 1 returns to the compressor 1 via the oil return bypass circuit 24 does not pass through the liquid side connection refrigerant pipe 9 and the gas side connection refrigerant pipe 10 on the way. Therefore, the oxidized scale generated when the sufficient non-oxidation brazing is not performed when the liquid-side connection refrigerant pipe 9 or the gas-side connection refrigerant pipe 10 is installed may flow into the sludge filter 26 during operation. Therefore, there is no danger of blocking the flow path or deforming or breaking the sludge filter.

Embodiment 12 FIG. Hereinafter, a twelfth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a refrigerant circuit diagram of an air conditioner according to the twelfth embodiment.
In the figure, A is a heat source unit, B, C and D are indoor units, 1 is a compressor, 2 is a switching valve, 3 is a heat source unit side heat exchanger, 4 is an accumulator, and 5 is an oil of the accumulator 4. Return hole, 7b, 7
c and 7d are indoor unit side heat exchangers, and 8b, 8c and 8d are first heat exchangers.
9 is a liquid side connection refrigerant pipe, 10 is a gas side connection refrigerant pipe, 23 is an oil separator, 24 is an oil return bypass circuit,
25 is a fourth diaphragm device, 26 is a sludge filter, which is the same as that of the ninth embodiment shown in FIG.
Reference numeral 28 denotes a liquid refrigerant injection circuit which branches from between the oil separator 23 and the switching valve 2 and joins an upstream portion of the sludge filter 26 of the oil return bypass circuit 24. Reference numeral 29 denotes a pipe of the liquid refrigerant injection circuit 28 and a heat source side This is a liquid injection circuit heat exchanger that exchanges heat with a part of the air flowing into the lowermost part of the heat exchanger 3.

Next, the flow of the refrigerant and the refrigerating machine oil will be described with reference to the drawings. At the time of cooling of the main refrigerant circuit including the compressor 1, the switching valve 2, the heat source unit side heat exchanger 3, the first expansion devices 8b, 8c, 8d, and the indoor unit side heat exchangers 7b, 7c, 7d,
The flow of the refrigerant at the time of heating and the operation of the oil separator 23 are completely the same as those in the eighth embodiment, and thus the description thereof will be omitted, and the flow of the refrigerant and the refrigerating machine oil in the oil return bypass circuit 24 and the liquid refrigerant injection circuit 28 will be described. Part of the high-temperature and high-pressure gas refrigerant from which the refrigerating machine oil has been separated by the oil separator 23 flows into the liquid refrigerant injection circuit 28, and flows into the lowermost part of the heat source device side heat exchanger 3 by the liquid injection circuit heat exchanger 29. It exchanges heat with part of the air to lower the temperature and liquefies, and is separated by the oil separator 23 and returned to the oil return bypass circuit 2.
4. Merge with the refrigeration oil flowing into 4. The combined liquid refrigerant and refrigerating machine oil are reduced to a low pressure by the fourth expansion device 25 through the sludge filter 26, and merge with the refrigerant of the main refrigerant circuit passing through the switching valve 2 between the switching valve 2 and the accumulator 4. I do. In the twelfth embodiment, the third and third embodiments are used.
Like 5, 6, and 10, it becomes an evaporator during heating.
At the lowermost part of the heat source device side heat exchanger 3 where the liquid injection circuit heat exchanger 29 is provided, the flow of the drain from the upper part makes it difficult for the wind to pass through, and frost is easily generated and grows. It is warmed and hard to frost.

The refrigerating machine oil degraded product generated in the sliding portion of the compressor 1 is mixed with the refrigerating machine oil in the discharge gas and discharged into the refrigerant circuit. By flowing into the circuit 24 and joining the liquid refrigerant flowing out of the liquid injection circuit heat exchanger 29 of the liquid refrigerant injection circuit 28, the concentration of the refrigerant in the refrigerating machine oil is increased and the refrigerant flows into the sludge filter 26 and is captured. As a result, the refrigerating machine oil deteriorated in the refrigerating machine oil precipitates out, so that the sludge filter 26 can capture not only sludge existing as a solid but also what was originally dissolved in the refrigerating machine oil. Therefore, the content of degraded refrigerating machine oil in the refrigerating machine oil that flows into the accumulator 4 and returns to the compressor 1 further decreases, and the amount of sludge adhering to the oil return hole 5 decreases. As a result, the refrigerating machine oil inside the compressor 1 is not depleted, and abnormal high pressure rise, low pressure fall, and discharge gas temperature rise due to the abnormal rise can be avoided, and the reliability is remarkably improved. In the cycle in which the refrigerant and the like discharged from the compressor 1 return to the compressor 1 via the oil return bypass circuit 24, the liquid side connection refrigerant pipe 9 and the gas side connection refrigerant pipe 1
Do not go through 0. Therefore, the oxidized scale generated when the sufficient non-oxidation brazing is not performed when the liquid-side connection refrigerant pipe 9 or the gas-side connection refrigerant pipe 10 is installed may flow into the sludge filter 26 during operation. Not
There is no danger of blocking the flow path or deforming or breaking the sludge filter.

Embodiment 13 FIG. Hereinafter, a thirteenth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a refrigerant circuit diagram of an air conditioner according to Embodiment 13 of the present invention.
In the figure, A is a heat source unit, B, C and D are indoor units, 1 is a compressor, 2 is a switching valve, 3 is a heat source unit side heat exchanger, 4 is an accumulator, and 5 is an oil of the accumulator 4. Return hole, 7b, 7
c and 7d are indoor unit side heat exchangers, and 8b, 8c and 8d are first heat exchangers.
9 is a liquid side connection refrigerant pipe, 10 is a gas side connection refrigerant pipe, 23 is an oil separator, 24 is an oil return bypass circuit,
25 is a fourth throttle device, 26 is a sludge filter, 28
Is a liquid refrigerant injection circuit, which is the same as that of the twelfth embodiment shown in FIG.
Is a liquid injection circuit heat exchanger in which heat is exchanged between the piping and the portion between the switching valve 2 and the accumulator 4.

Next, the flow of the refrigerant and the refrigerating machine oil will be described with reference to the drawings. At the time of cooling of the main refrigerant circuit including the compressor 1, the switching valve 2, the heat source unit side heat exchanger 3, the first expansion devices 8b, 8c, 8d, and the indoor unit side heat exchangers 7b, 7c, 7d,
The flow of the refrigerant at the time of heating and the operation of the oil separator 23 are completely the same as those in the eighth embodiment, and thus the description thereof will be omitted, and the flow of the refrigerant and the refrigerating machine oil in the oil return bypass circuit 24 and the liquid refrigerant injection circuit 28 will be described. A part of the high-temperature and high-pressure gas refrigerant from which the refrigerating machine oil has been separated by the oil separator 23 flows into the liquid refrigerant injection circuit 28 and returns to the compressor 1 via the switching valve 2 in the liquid injection circuit heat exchanger 29 via the low-temperature and low-pressure gas refrigerant. The refrigerant exchanges heat with the refrigerant to lower the temperature and liquefy, and joins with the refrigerating machine oil separated by the oil separator 23 and flowing into the oil return bypass circuit 24. The combined liquid refrigerant and refrigerating machine oil are reduced to a low pressure by the fourth expansion device 25 through the sludge filter 26, and merge with the refrigerant of the main refrigerant circuit passing through the switching valve 2 between the switching valve 2 and the accumulator 4. I do.

The degraded refrigerating machine oil generated in the sliding portion of the compressor 1 is mixed with the refrigerating machine oil in the discharge gas and discharged into the refrigerant circuit, separated by the oil separator 23 together with the refrigerating machine oil, and returned to the oil return bypass. By flowing into the circuit 24 and joining the liquid refrigerant flowing out of the liquid injection circuit heat exchanger 29 of the liquid refrigerant injection circuit 28, the concentration of the refrigerant in the refrigerating machine oil is increased and the refrigerant flows into the sludge filter 26 and is captured. As a result, the deteriorated refrigerating machine oil dissolved in the refrigerating machine oil precipitates, so that the sludge filter 26 can capture not only sludge existing as a solid but also the substance originally dissolved in the refrigerating machine oil. Therefore, the content of degraded refrigerating machine oil in the refrigerating machine oil that flows into the accumulator 4 and returns to the compressor 1 further decreases, and the amount of sludge adhering to the oil return hole 5 decreases. As a result, the refrigerating machine oil inside the compressor 1 is not depleted, and abnormal high pressure rise, low pressure fall, and discharge gas temperature rise due to the abnormal rise can be avoided, and the reliability is remarkably improved. In the cycle in which the refrigerant and the like discharged from the compressor 1 return to the compressor 1 via the oil return bypass circuit 24, the liquid side connection refrigerant pipe 9 and the gas side connection refrigerant pipe 1
Do not go through 0. Therefore, the oxidized scale generated when the sufficient non-oxidation brazing is not performed when the liquid-side connection refrigerant pipe 9 or the gas-side connection refrigerant pipe 10 is installed may flow into the sludge filter 26 during operation. Not
There is no danger of blocking the flow path or deforming or breaking the sludge filter.

Embodiment 14 FIG. Hereinafter, a fourteenth embodiment of the present invention will be described with reference to FIG. FIG. 15 is a refrigerant circuit diagram of an air conditioner according to Embodiment 14 of the present invention.
In the figure, A is a heat source unit, B, C and D are indoor units, 1 is a compressor, 2 is a switching valve, 3 is a heat source unit side heat exchanger, 4 is an accumulator, and 5 is an accumulator 4 oil. Return hole, 6 is second
7b, 7c, 7d are indoor unit side heat exchangers, 8
Reference numerals b, 8c, and 8d denote first expansion devices, 9 denotes a liquid-side connection refrigerant pipe, 10 denotes a gas-side connection refrigerant pipe, which is the same as in the first embodiment shown in FIG. 1, and 23 denotes an oil separator. , 24 are an oil return bypass circuit, 25 is a fourth throttle device, and 26 is a sludge filter, which are used in the twelfth embodiment shown in FIG.
28 is branched from between the second expansion device 6 and the liquid-side connection refrigerant pipe 9 and is connected to the oil return bypass circuit 24.
Is a liquid refrigerant injection circuit that joins the upstream portion of the sludge filter 26 of FIG.

Next, the flow of the refrigerant and the refrigerating machine oil will be described with reference to the drawings. Compressor 1, switching valve 2, heat source device side heat exchanger 3, second expansion device 6, first expansion device 8b, 8c, 8
d, and the flow of the refrigerant at the time of cooling and at the time of heating of the main refrigerant circuit including the indoor unit-side heat exchangers 7b, 7c, and 7d according to the first embodiment.
The operation of the oil separator 23 is exactly the same as that of the eighth embodiment.
Therefore, the description is omitted, and the flow of the refrigerant and the refrigerating machine oil in the oil return bypass circuit 24 and the liquid refrigerant injection circuit 28 will be described. The refrigerating machine oil separated by the oil separator 23 flows into the oil return bypass circuit 24. During cooling, the heat exchanger 3 exchanges heat with air to condense and liquefy, and the second heat exchanger 3 is fully opened.
The liquid refrigerant that has passed through the expansion device 6 is condensed by exchanging heat with air in the indoor unit side heat exchangers 7b, 7c and 7d during heating.
The liquid refrigerant that has passed through the first expansion devices 8a, 8b, and 8c and the liquid-side connection refrigerant pipe 9 that has liquefied and is fully open partially flows into the liquid refrigerant injection circuit 28, and refrigerating machine oil that flows into the oil return bypass circuit 24. Join. The combined liquid refrigerant and refrigerating machine oil are reduced to a low pressure by the fourth expansion device 25 through the sludge filter 26, and merge with the refrigerant of the main refrigerant circuit passing through the switching valve 2 between the switching valve 2 and the accumulator 4. I do.

The refrigerating machine oil degraded product generated in the sliding portion of the compressor 1 is mixed with the refrigerating machine oil in the discharge gas and discharged into the refrigerant circuit. By flowing into the circuit 24 and merging with the liquid refrigerant flowing into the liquid refrigerant injection circuit 28, the concentration of the refrigerant in the refrigerating machine oil is increased and flows into the sludge filter 26 to be captured. As a result, the refrigerating machine oil degraded material that has dissolved in the refrigerating machine oil precipitates.
In No. 6, together with the sludge existing as a solid, what was originally dissolved in the refrigerating machine oil can also be captured. Therefore, the content of degraded refrigerating machine oil in the refrigerating machine oil that flows into the accumulator 4 and returns to the compressor 1 further decreases, and the amount of sludge adhering to the oil return hole 5 decreases. As a result, the refrigerating machine oil inside the compressor 1 is not depleted, and abnormal high pressure rise, low pressure fall, and discharge gas temperature rise due to the abnormal rise can be avoided, and the reliability is remarkably improved. The refrigerant discharged from the compressor 1 is returned to the oil return bypass circuit 24.
The cycle of returning to the compressor 1 via the above does not pass through the liquid side connection refrigerant pipe 9 and the gas side connection refrigerant pipe 10 on the way. Therefore, the oxidized scale generated when the sufficient non-oxidation brazing is not performed when the liquid-side connection refrigerant pipe 9 or the gas-side connection refrigerant pipe 10 is installed may flow into the sludge filter 26 during operation. Therefore, there is no danger of blocking the flow path or deforming or breaking the sludge filter.

Embodiment 15 FIG. Hereinafter, a fifteenth embodiment of the present invention will be described with reference to FIG. FIG. 15 is a refrigerant circuit diagram of an air conditioner according to Embodiment 15 of the present invention.
In the figure, A is a heat source unit, B, C and D are indoor units, 1 is a compressor, 2 is a switching valve, 3 is a heat source unit side heat exchanger, 4 is an accumulator, and 5 is an oil of the accumulator 4. Return hole, 7b, 7
c and 7d are indoor unit side heat exchangers, and 8b, 8c and 8d are first heat exchangers.
9 is a liquid side connection refrigerant pipe, 10 is a gas side connection refrigerant pipe, 23 is an oil separator, 24 is an oil return bypass circuit,
Reference numeral 25 denotes a fourth expansion device, and reference numeral 26 denotes a sludge filter, which is the same as that of the twelfth embodiment shown in FIG. 28 is a liquid refrigerant injection circuit which branches from between the oil separator 23 and the switching valve 2 and the other end is connected to a refrigerant pipe between the switching valve 2 and the compressor 1, and 30 is in the liquid refrigerant injection circuit 28 The fifth expansion device 29 is a liquid injection circuit heat exchanger that exchanges heat between the upstream portion and the downstream portion of the fifth expansion device 30 of the liquid refrigerant injection circuit 28. Further, an upstream portion of the sludge filter 26 of the oil return bypass circuit 24 and a liquid refrigerant injection circuit 28
And an upstream portion of the fifth throttle device 30.

Next, the flow of the refrigerant and the refrigerating machine oil will be described with reference to the drawings. At the time of cooling of the main refrigerant circuit including the compressor 1, the switching valve 2, the heat source unit side heat exchanger 3, the first expansion devices 8b, 8c, 8d, and the indoor unit side heat exchangers 7b, 7c, 7d,
The flow of the refrigerant at the time of heating and the operation of the oil separator 23 are completely the same as those in the eighth embodiment, and thus the description thereof will be omitted, and the flow of the refrigerant and the refrigerating machine oil in the oil return bypass circuit 24 and the liquid refrigerant injection circuit 28 will be described. Part of the high-temperature and high-pressure gas refrigerant from which the refrigerating machine oil has been separated by the oil separator 23 flows into the liquid refrigerant injection circuit 28 and exchanges heat with the refrigerant on the low pressure side of the liquid refrigerant injection circuit 28 in the liquid injection circuit heat exchanger 29. The temperature is lowered and liquefied, a part of which flows into the fifth expansion device 30 and is reduced to a low pressure,
The refrigerant is heated and gasified by the high-pressure side refrigerant in the liquid injection circuit heat exchanger 29, and merges with the refrigerant in the main refrigerant circuit passing through the switching valve 2 between the switching valve 2 and the accumulator 4. The remaining portion of the refrigerant liquefied on the high pressure side of the liquid injection circuit heat exchanger 29 joins the refrigerating machine oil separated by the oil separator 23 and flowing into the oil return bypass circuit 24. The combined liquid refrigerant and refrigerating machine oil are reduced to a low pressure by the fourth expansion device 25 through the sludge filter 26, and merge with the refrigerant of the main refrigerant circuit passing through the switching valve 2 between the switching valve 2 and the accumulator 4. I do.

The refrigerating machine oil degraded products generated in the sliding portion of the compressor 1 are mixed with the refrigerating machine oil in the discharge gas and discharged into the refrigerant circuit. The refrigerant flows into the circuit 24 and joins a part of the liquid refrigerant flowing out from the high pressure side of the liquid injection circuit heat exchanger 29 of the liquid refrigerant injection circuit 28 to increase the refrigerant concentration in the refrigerating machine oil and to the sludge filter 26. Inflow and capture. As a result, the deteriorated refrigerating machine oil dissolved in the refrigerating machine oil precipitates, so that the sludge filter 26 can capture not only sludge existing as a solid but also the substance originally dissolved in the refrigerating machine oil. Therefore, the content of degraded refrigerating machine oil in the refrigerating machine oil that flows into the accumulator 4 and returns to the compressor 1 further decreases, and the amount of sludge adhering to the oil return hole 5 decreases. Thereby, the compressor 1
The internal refrigerating machine oil is not depleted, and abnormally high pressure rise, low pressure fall, and discharge gas temperature rise due to the abnormal rise can be avoided, and the reliability is remarkably improved. Further, the refrigerant and the like discharged from the compressor 1 pass through the oil return bypass circuit 24 and the compressor 1
The cycle to return to does not pass through the liquid side connection refrigerant pipe 9 and the gas side connection refrigerant pipe 10 on the way. Therefore, the oxidized scale generated when the sufficient non-oxidation brazing is not performed when the liquid-side connection refrigerant pipe 9 or the gas-side connection refrigerant pipe 10 is installed may flow into the sludge filter 26 during operation. Therefore, there is no danger of blocking the flow path or deforming or breaking the sludge filter.

Embodiment 16 FIG. FIG. 17 is Embodiment 1
Embodiment 16 of Dryer 16 Used in 6
FIG. 4A is a longitudinal sectional view showing a state in which the flow direction of the refrigerant is from left to right, FIG. 4B is a view in which the flow direction of the refrigerant is from bottom to top, and FIG. Each of the figures shows a case where a dryer is provided so that the flow direction of the refrigerant is from top to bottom. In the figure, 50 is a cylindrical vessel, 51 is an inflow pipe provided at one end of the vessel 50, 52 is an outflow pipe provided at the other end of the vessel 50, 53 is a synthetic zeolite as a main component, and activated alumina or the like. A dryer core compounded and hardened with a binder such as an adhesive is a refrigerating machine oil.

The refrigerant flowing from the inflow pipe 51 absorbs the moisture contained in the refrigerant by the dryer core 53. However, since the flow path of the refrigerant passes through the very fine eyes of the dryer core, it is larger than that. Is captured here. Further, some dryers have a configuration in which a filter is provided on the upstream side or the downstream side of the dryer core 53, but foreign matter is also captured in the filter portion. Therefore, the sludge filter 26 according to Embodiments 9 to 15
As such, a dryer having this configuration can be used. By using a dryer as the sludge filter 26 in this way, moisture can be directly absorbed from the refrigerating machine oil flowing through the oil return bypass circuit 24, and the sludge filter function and the moisture capturing function can be combined. As a result, while suppressing hydrolysis of the refrigerating machine oil, the content of degraded refrigerating machine oil in the refrigerating machine oil can be reduced.
The amount of sludge adhering to the squeezing devices 8b, 8c, 8d, the oil return hole 5, and the like is reduced.

In the case where the dryer 16 in the first to sixth embodiments and the sludge filter 26 in the ninth to fifteenth embodiments are used as shown in FIG. When the liquid refrigerant or the refrigerating machine oil is not sufficiently accumulated in the dryer container 50 in the transient state, the liquid refrigerant or the refrigerating machine oil cannot flow out of the container 50. On the other hand, when the refrigerant is arranged so that the flow direction of the refrigerant is from top to bottom, as shown in FIG. Operation of the compressor, and the refrigerating machine oil is not depleted than the compressor.

Embodiment 17 FIG. FIG. 18 is a longitudinal sectional view showing an example of the accumulator 4 according to the seventeenth embodiment used in each of the above embodiments.
Is an accumulator container, 61 is an inflow pipe inserted from the bottom of the container 60 to the upper portion of the container, 62 is an oil return inserted from the bottom of the container 60 to the upper portion of the container, and returns refrigeration oil to the lower portion. Outflow pipe with hole 5, 63 is vessel 60
Liquid mixture of liquid refrigerant and refrigerating machine oil stored in the lower part of the inside,
Numeral 64 denotes an oil return pipe connecting the lower space inside the container 60 and the upper pipe end of the outflow pipe 62, and numeral 65 denotes an orifice provided at one end of the oil return pipe 64 on the lower space side inside the container 60.

Next, the oil return operation of the accumulator 4 will be described. The height difference between the liquid level of the mixture 63 in the accumulator and the pipe end of the outflow pipe 62 is h, the flow velocity of the refrigerant in the outflow pipe is u, and the density of the refrigerant flowing out of the outflow pipe is ρ.
g, the density of the mixture 63 is ρ _l , and the orifice 65
The differential pressure ΔP generated before and after the orifice 65, which is obtained by subtracting the outlet pressure from the inlet pressure, is expressed by ΔP = k ₁ · ρ _g · u ₂ / 2-k ₂ · ρ _l · h (where k ₁ , k ₂ is a positive constant). However,
Since the oil return pipe 64 is made sufficiently thick, the pressure loss here is ignored. If ΔP is positive, it means that the oil can be returned; if it is negative, it means that the oil cannot be returned. In addition, the larger the ΔP is, the larger the oil return flow rate is.

As is clear from this equation, when the refrigerant flow velocity u is large, the first term is larger than the second term on the right side, and even if the liquid level is low, oil can be returned. On the other hand, when the refrigerant flow velocity u is small, the negative amount of the second term is large even if the liquid level is somewhat high, and the flow rate of the mixed liquid flowing out to the outflow pipe 64 is small. When the refrigerant flow rate is large, the ratio of the refrigerating machine oil discharged from the compressor is large, but when the refrigerant flow rate is small, the ratio of the refrigerating machine oil discharged from the compressor is small. Therefore, when the refrigerating machine oil-deteriorated component adheres to the oil return hole 5, the oil return is insufficient.
This is the case when the flow rate of the refrigerant is large. When the oil return hole 5 is enlarged, the oil returns sufficiently when the refrigerant flow rate is high, but when the refrigerant flow rate is low and the liquid level of the accumulator 4 is high, the liquid back increases and lubricity of the compressor increases. descend.

However, as shown in FIG. 18, when the oil return pipe 64 is provided together with the oil return hole 5, the flow rate of the oil return becomes a problem due to the adhesion of the sludge. Oil can be used to compensate for the shortage of oil returned due to sludge adhesion. Further, even when the flow rate of the refrigerant is small and the liquid level of the accumulator 4 is high, the liquid back from the oil return pipe 64 is small. By providing the oil return pipe 64 in the accumulator 4 in this manner, even if the sludge adheres to the oil return hole 5, the oil return will not be insufficient, and the reliability will not be excessive. A high air conditioner can be obtained.

When the orifice 65 of the oil return pipe 64 is provided at one end of the oil return pipe 64 on the outflow pipe 62 side as shown in FIG. 19, the oil return pipe 64 is connected to the capillary 6 as shown in FIG.
6, when the function of the oil return pipe 64 and the function of the orifice 65 are combined, the outflow pipe 62 is inserted from above the container 60, and the oil return pipe 64 is connected to the container 60 as shown in FIG. When the oil return pipe 5 and the orifice 67 are provided instead of the oil return hole 5 provided on the outside, and the outflow pipe 62 is U-shaped as shown in FIG. It has an effect.

Embodiment 18 FIG. Hereinafter, an eighteenth embodiment of the present invention will be described with reference to FIGS. 23, 24, and 25. FIG. 23 is a block diagram showing a refrigerant circuit and a control circuit of an air conditioner according to the eighteenth embodiment, FIG. 24 is a block diagram showing a throttling device control device according to the twenty-second embodiment, and FIG. It is a flowchart explaining an apparatus control operation. In the figure, A is a heat source device, B, C,
D is an indoor unit, 1 is a compressor, 2 is a switching valve, 3 is a heat source unit side heat exchanger, 4 is an accumulator, 5 is an oil return hole, 7b, 7
c and 7d are indoor unit side heat exchangers, and 8b, 8c and 8d are first heat exchangers.
Reference numeral 9 denotes a liquid side connection refrigerant pipe, and 10 denotes a gas side connection refrigerant pipe. The above is the same as the conventional example shown in FIG.

Reference numeral 31 denotes a discharge pressure detecting means provided between the discharge part of the compressor 1 and the switching valve 2, and 32 denotes a means provided between the heat source unit side heat exchanger 3 and the liquid side connection refrigerant pipe 9. The third temperature detecting means, 33b, 33c, 33d are indoor units B, C,
The fourth temperature detecting means 34b, 34c, 34d provided between the first expansion devices 8b, 8c, 8d in D and the indoor heat exchangers 7b, 7c, 7d are indoor units B, C, F is a fifth temperature detecting means provided at one end of the indoor side heat exchangers 7b, 7c, 7d on the gas side connection refrigerant pipe 10 side, D is a throttling device control device, and 36 is a third temperature detecting means 32. SC calculation means for calculating the degree of supercooling of the installation part of the third temperature detection means 32 from the detected value, the detection value of the first pressure detection means 31 and the calculation result of the composition calculation means 22 of the mixed refrigerant;
7 is an SH calculating means for calculating the degree of superheat at the outlet of the indoor heat exchanger from the detected values of the fourth temperature detecting means 33b, 33c, 33d and the detected values of the fifth temperature detecting means 34b, 34c, 34d, 38 Are first throttle device control means 39b, 39c, 3c for controlling the degree of opening of the first throttle devices 8b, 8c, 8d based on the calculation results of the SC calculation means 36 and the SH calculation means 37.
9d is a blower provided in each indoor unit B, C, D, 40
b, 40c, and 40d are drain pumps provided in the indoor units B, C, and D, and 41b, 41c, and 41d are defrost control devices.

During cooling of the main refrigerant circuit including the compressor 1, the switching valve 2, the heat source unit side heat exchanger 3, the first expansion devices 8b, 8c, 8d, and the indoor unit side heat exchangers 7b, 7c, 7d. ,
Since the flow of the refrigerant at the time of heating is completely the same as that of the conventional example, the description is omitted, and the first expansion devices 8b and 8
The control operations c and 8d will be described with reference to the flowchart of FIG. In step 105, the fourth temperature detecting means 33
b, 33c, 33d and the fifth temperature detecting means 3
4b, 34c and 34d, and a calculation result SH calculated by the SH calculation means 37 from the detected values.
Is compared with the upper limit value SHH. If SH ≦ SHH, the process proceeds to step 106, and if SH> SHH, the process proceeds to step 1.
Proceed to 08. In step 106, the calculation result SH of the SH calculation means 36 is compared with a preset lower limit value SHL of SH, and if SH ≧ SHL, the routine proceeds to step 107, where the first throttle device 8b, 8c, 8d The opening is reduced, and if SH <SHL, nothing is performed. In step 108, the opening degree Sj of the first throttle device 8b, c, d
Is compared with a preset upper limit opening MAX.
If ≦ MAX, the routine proceeds to step 109, where the opening degree of the first expansion devices 8b, 8c, 8d is increased. If Sj> MAX, the routine proceeds to step 110.

In step 110, the third temperature detecting means 3
2, a calculation result calculated by the SC calculation means 36 from the detection value of the first pressure detection means 31 and a calculation result of the composition calculation means 22 of the mixed refrigerant, and a predetermined S
The lower limit value C of C is compared with the lower limit value SCL. If SC> SCL, the routine proceeds to step 111, where the upper limit opening MAX is reset to a large value, and if SC ≦ SCL, nothing is performed. As described above, when the first expansion devices 8b, 8c, and 8d fall short of the flow rate due to the sludge adhesion, the control is diverged because the subcooling is sufficiently ensured in a portion of the third temperature detection means 32. If not, the maximum opening is set to be large, so that the shortage of the flow rate is resolved.

Embodiment 19 FIG. Hereinafter, a nineteenth embodiment of the present invention will be described with reference to FIGS. 23, 26, and 27. FIG. 26 is a block diagram showing a defrost control device according to the nineteenth embodiment, and FIG. 27 is a flowchart for explaining the defrost control operation. In FIG. 26, 34
b, 34c, and 34d are fifth temperature detecting means provided at one end of the indoor heat exchangers 7b, 7c, and 7d in the indoor units B, C, and D on the gas-side connection refrigerant pipe 10 side;
9d is a blower provided in each indoor unit B, C, D, 40
Reference numerals b, 40c, and 40d denote drain pumps provided in the indoor units B, C, and D, 41b, 41c, and 41d defrost control devices, and 42, a system mode for determining whether the system mode is cooling. Judging means 43b, 43c and 43d are indoor unit mode judging means for judging whether the mode of each of the indoor units B, C and D is cooling, and 44b, 44c and 44d are each indoor unit B and
C and D time measuring means, and 45, an indoor unit defrosting operation control means for controlling an operation for defrosting the heat exchanger of the uncooled indoor unit.

When some of the indoor units, for example, B perform a cooling operation, the room temperature and the outside air temperature are low, and the remaining indoor units C and D are stopped, the first throttle of the stopped indoor units C and D is stopped. Device 8
There is a case where a small flow rate of the refrigerant flows without being completely closed due to the sludge to which d adheres. In this case, since there is no heat for gasifying the small flow rate refrigerant and the room temperature and the outside air temperature are low, the indoor heat exchanger 7d of the stopped indoor units C and D is frosted. In such a state, the temperatures of the fifth temperature detecting means 34c and 34d of the indoor units C and D become low. Such indoor unit C, a fifth temperature detecting means 34c and D, first the predetermined temperature T _L lower condition continues a first predetermined time tau _1B which 34d is detected values T ₅ of the preset, which Fifth temperature detecting means 34c, 34d, system mode determining means 42, indoor unit mode determining means 43c,
43d and timing means 44c and 44d,
By the indoor unit defrosting operation control means 45, the blower 39c,
39d is operated to defrost the indoor heat exchangers C and D,
At the same time, the drain pumps 40c and 40d are also operated to control drainage of drain water generated at this time.

After the second predetermined time τ _{2B has} elapsed after the operation of the blowers 39c and 39d has started, the detection value T ₅ of the fifth temperature detecting means 34c and 34d of the indoor units C and D is set higher than _TL in advance. the second predetermined temperature T _H higher than going on a blower 39c which is set to stop the 39d, blower 39c, 3
Since the drain water continues to be generated for a while after the 9d stop,
The control is performed so as to stop the drain pumps 40c and 40d after a lapse of a third predetermined time τ _3B after stopping the blowers 39c and 39d. As described above, even when the first throttle device of the stopped indoor unit cannot be completely closed due to the attached sludge, frost of the indoor heat exchanger of the stopped indoor unit does not continue to grow. No problem occurs.

Next, the control operation of the indoor unit defrosting operation control means 45 will be described with reference to the flowchart of FIG. As a result of the determination by the system mode determining means 42, the system mode is cooling and the indoor unit mode determining means 43b, 43c, 43
Results of the determination of d, indoor mode - de is not cooling, timing means 44b, 44c, 44d first timing tau ₁ has passed the first predetermined time tau _1B by, and, fifth temperature detection means 34
b, 34c, when the detection value T ₅ of 34d is below a first predetermined temperature T _L, step from step 112 113,11
The process proceeds to step 116 through steps 4 and 115,
The second timekeeping τ ₂ by b, 44c, 44d is cleared to 0, and the routine proceeds to step 117, where the blowers 39b, 39c, 3
The operation of the 9d and the drain pumps 40b, 40c, 40d is started.

Thereafter, the flow proceeds to step 118, where the second time measurement τ
Or ₂ has passed the second predetermined time tau _2B is step 119
When the process proceeds fifth temperature detection means 34b, 34c, the detected value T ₅ of 34d or becomes higher than the second predetermined temperature T _H is determined, until they conditions are satisfied the determination is continued, is satisfied Then, the process proceeds to step 120, where the blower 39b
The operations of 39c and 39d are stopped, the third time measurement τ ₃ by the time measurement means 44b, 44c and 44d is cleared to 0 in step 121, the process proceeds to step 122, and the third time measurement τ ₃
Proceeds to step 123 after the third predetermined time τ _{3B has} elapsed, and the operation of the drain pumps 40b, 40c, and 40d is stopped.

[0111]

As described above, according to the first aspect of the present invention, the main refrigerant circuit is branched from the refrigerant pipe between the condenser and the throttling device, via the dryer for absorbing moisture and the bypass throttling device. Since the bypass circuit connected to the refrigerant pipe between the expansion device and the compressor is provided, moisture is absorbed by the dryer in the bypass circuit, and the amount of water in the refrigerant and the refrigerating machine oil decreases downstream of the dryer. This rate is sufficiently faster than the rate of hydrolysis and degradation of the polyester oil, and has the effect of suppressing hydrolysis and suppressing the generation of sludge components in the compressor. Further, by providing the dryer in the middle of the piping of the bypass circuit, the impact of the flow flowing through the dryer can be reduced, and there is also an effect that the dryer is hardly crushed.

According to the second aspect of the present invention, the bypass is branched from the refrigerant pipe on the discharge side of the compressor, and is connected to the refrigerant pipe on the suction side of the compressor via the dryer and the bypass throttle device for absorbing moisture. Since the circuit is provided, in addition to the effects of the first aspect of the present invention, in the cycle in which the refrigerant discharged from the compressor returns to the compressor through the bypass, the heat source unit side heat exchanger and the indoor unit side heat exchange This is a very short cycle that does not pass through the vessel, the liquid side connection refrigerant pipe, and the gas side connection refrigerant pipe, so it has good responsiveness, and the transition time in which the liquid is not supplied to the dryer is very short. Is not easily crushed, and oxidized scale generated when the non-oxidizing brazing is not performed sufficiently when constructing the liquid-side connecting refrigerant pipe or the gas-side connecting refrigerant pipe may flow into the dryer during operation. Ku, or close the flow path, there is an effect that also eliminates the risk of or crushing the dryer.

According to the third aspect of the present invention, in the first or second aspect of the present invention, the bypass heat exchanger for cooling the refrigerant flowing into the dryer is provided in the middle of the bypass. In addition to the effects of the present invention, the refrigerant flowing into the dryer is further cooled by the bypass heat exchanger, so that the refrigerant flowing into the dryer is in a liquid state even at the time of starting the compressor or during a transient operation such as defrost. As the temperature of the refrigerant is low, the moisture saturation solubility in the refrigerant is low. This has the effect of increasing the amount of adsorbed moisture and suppressing the hydrolysis of refrigerator oil.

According to a fourth aspect of the present invention, the compressor includes a dryer branched from the liquid-side connecting refrigerant pipe, absorbing moisture, a bypass expansion device, and a bypass heat exchanger for cooling the refrigerant flowing into the dryer. Since the bypass circuit connected to the refrigerant pipe between the suction unit and the switching valve is provided, the same effects as those of the first and third aspects are obtained.

According to the fifth aspect of the present invention, the refrigerant is branched from the refrigerant pipe between the compressor discharge part and the switching valve, and passes through the bypass heat exchanger for cooling the refrigerant, the dryer for absorbing moisture, and the bypass throttle device. Since the bypass circuit connected to the refrigerant pipe between the compressor suction portion and the switching valve is provided, the same effects as those of the second and third aspects are obtained.

According to claim 6 of the present invention, claims 1 to
5. In the invention according to any one of the first to fifth aspects, a hydrofluorocarbon-based mixed refrigerant is used as a working medium, the first temperature detecting means provided at an inlet of the bypass throttle device, and a bypass throttle device in the middle of the bypass. The second provided downstream
Temperature detecting means, suction pressure detecting means provided in the compressor suction portion, and composition calculating means for calculating the composition of the refrigerant based on detection values of the first and second temperature detecting means and the suction pressure detecting means. Therefore, in addition to the effects of the invention according to any one of claims 1 to 5, it is possible to detect the circulating composition of the non-azeotropic refrigerant mixture while sufficiently absorbing moisture with a dryer, In addition, these two objectives can be achieved with one bypass, the refrigerant circuit can be simplified, and there is an effect that downsizing and high reliability can be obtained.

According to the seventh aspect of the present invention, the oil separator is provided at the compressor discharge part, and the oil return bypass circuit for returning the separated refrigerating machine oil to the compressor suction part is provided. The flow rate of the refrigerating machine oil flowing through the refrigerating machine drops remarkably, and the integrated flow rate of the refrigerating machine oil deteriorated circulating together with the refrigerating machine oil also decreases. As a result, the amount of the deteriorated refrigerating machine oil that becomes sludge and adheres to the expansion device of the main refrigerant circuit also decreases. As described above, the shortage of the flow rate of the expansion device of the main refrigerant circuit can be avoided, and the shortage of the air-conditioning capacity is eliminated. Further, an abnormal increase in high pressure, a decrease in low pressure, and an increase in the temperature of the discharge gas due to the abnormal increase can be avoided, and the reliability is significantly improved.

According to the eighth aspect of the present invention, in the seventh aspect of the present invention, the sludge filter is provided in the middle of the oil return bypass circuit. The refrigerating machine oil degraded matter generated inside the machine is captured by the sludge filter in the recirculation bypass, the refrigerating machine oil degraded matter content in the refrigerating machine oil is reduced, and the sludge adhering to the main refrigerant circuit expansion device and the oil return hole is reduced. The amount of the refrigerant decreases, and the cycle in which the refrigerant discharged from the compressor returns to the compressor via the oil return bypass does not pass through the liquid-side connected refrigerant pipe and the gas-side connected refrigerant pipe on the way. Oxidation scale generated when sufficient non-oxidation brazing is not performed during the installation of the gas side connection refrigerant piping or the gas side connection refrigerant piping does not flow into the sludge filter during operation, and may block the flow path. There is an effect such as there is no danger or to deformation and destruction of the sludge filter.

According to a ninth aspect of the present invention, in the eighth aspect, a bypass heat exchanger for cooling the refrigerating machine oil is provided upstream of the sludge filter in the middle of the oil return bypass circuit. In addition to the effects of the invention, the temperature of the refrigerating machine oil flowing into the sludge filter is lowered and the concentration of the refrigerant in the refrigerating machine oil is increased. What has dissolved in the machine oil is also captured by the sludge filter, and there is an effect that the refrigerating machine oil deteriorating content in the refrigerating machine oil of the main refrigerant circuit is further reduced.

According to claim 10 of the present invention, claim 8
In the invention described in the above, the liquid refrigerant injection circuit for injecting the liquid refrigerant upstream of the sludge filter in the middle of the oil return bypass circuit is provided. Merges with the liquid refrigerant flowing out of the liquid injection circuit, the refrigerant concentration in the refrigerating machine oil flowing into the sludge filter increases, and the refrigerating machine oil degraded substances dissolved in the refrigerating machine oil are deposited and originally dissolved in the refrigerating machine oil. This is also trapped by the sludge filter, and the content of the refrigerating machine oil in the refrigerating machine oil of the main refrigerant circuit is further reduced.

According to claim 11 of the present invention, claim 8
In the invention according to any one of claims 10 to 10, the sludge filter in the middle of the oil return bypass is a dryer that absorbs moisture and has a sludge filter function.
In addition to the effects of the invention according to any one of the above aspects, by directly absorbing moisture from the refrigerating machine oil flowing through the recirculation bypass, hydrolysis of the refrigerating machine oil is suppressed, and deterioration of the refrigerating machine oil in the refrigerating machine oil of the main refrigerant circuit is performed. There is an effect that the substance content further decreases.

According to claim 12 of the present invention, claim 1
In any of the inventions according to any one of the first to fifth and eleventh aspects, the mounting posture of the dryer is set downward with respect to the flow direction.
The liquid refrigerant or the refrigerating machine oil that has flowed into the dryer quickly flows out of the dryer, so that the operation can be quickly and stably started.

According to claim 13 of the present invention, claim 3
In any of the inventions described in any one of the above-described items 6, 9, 11, and 12, the lowermost portion of the heat source device side heat exchanger is passed as all or a part of the bypass heat exchanger.
In addition to the effects of the invention described in any one of 6, 9, 11 and 12, the lower part of the heat exchanger which is difficult to wind due to the flow of the drain at the upper part and is liable to frost is heated and frosted. There is an effect that it becomes difficult.

According to the fourteenth aspect of the present invention, the refrigerating machine oil stored at the bottom of the accumulator is supplied to the accumulator.
Oil return mechanism provided in parallel at two locations above and below the refrigerant outflow pipe from the compressor to the compressor, so that even if sludge adheres, there is no shortage of oil return and there is no excess liquid back. There is an effect that a highly reliable air conditioner can be obtained.

According to the fifteenth aspect of the present invention, the expansion device is controlled so that the degree of superheat at the outlet of the evaporator calculated from the medium temperatures at the inlet and outlet of the evaporator is within a certain range. An upper limit opening is provided to prevent excessive valve opening, and the degree of superheat at the evaporator outlet exceeds a certain range,
When the opening degree of the expansion device reaches the upper limit opening degree, the supercooling degree at the expansion device inlet calculated by the refrigerant temperature at the inlet side of the expansion device, the discharge pressure of the compressor, and the composition of the refrigerant is a predetermined value. With the above, since the throttle device control device that greatly corrects the upper limit opening degree is provided, even if the throttle device falls short of the flow rate due to sludge adhesion, sufficient supercooling is ensured and the control diverges. If not, the maximum opening is set to be large, and there is an effect that the shortage of the flow rate is resolved.

According to the sixteenth aspect of the present invention, each of the indoor units is provided with a blower for defrosting, and when only some of the indoor units are performing the cooling operation, the indoor heat of the indoor unit that is not performing the cooling operation is provided. When the medium temperature on the outlet side of the exchanger falls below the predetermined temperature for a predetermined time continuously, a defrost control device for operating the blower is provided. Even when the closed state is not set, there is an effect that the growth of frost in the indoor heat exchanger of the indoor unit can be prevented by the operation of the blower for defrosting.

According to claim 17 of the present invention, claim 1
In the invention described in 6, the operation of each indoor unit is started at the same time as the blower for defrosting, and is controlled by the defrosting control device to stop after a lapse of a predetermined time from the stoppage of the operation of the blower.
Since the drain pump for draining the drain generated in the indoor unit is provided, in addition to the effect of the invention described in claim 16, there is an effect that water leakage due to drain water drainage due to defrost does not occur.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 2.

FIG. 3 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 3.

FIG. 4 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 4.

FIG. 5 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 5.

FIG. 6 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 6.

FIG. 7 is a block diagram relating to a composition calculation of the air-conditioning apparatus according to Embodiment 7.

FIG. 8 is a flowchart showing the operation of the composition calculation means of the air conditioner according to the seventh embodiment.

FIG. 9 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 8.

FIG. 10 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 9;

FIG. 11 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 10.

FIG. 12 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 11;

FIG. 13 is a refrigerant circuit diagram of an air conditioner according to a twelfth embodiment.

FIG. 14 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 13;

FIG. 15 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 14;

FIG. 16 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 15;

FIG. 17 is a longitudinal sectional view showing Embodiment 16 of the dryer used in Embodiments 1 to 6.

FIG. 18 is a longitudinal sectional view showing a space 17 according to a seventeenth embodiment used in each embodiment.

FIG. 19 is a longitudinal sectional view showing an accumulator according to an eighteenth embodiment of the present invention.

FIG. 20 is a longitudinal sectional view showing an embodiment 19 of an accumulator.

FIG. 21 is a longitudinal sectional view showing an embodiment 20 of an accumulator.

FIG. 22 is a longitudinal sectional view showing an embodiment 21 of an accumulator.

FIG. 23 is a configuration diagram showing a refrigerant circuit and a control circuit of an air conditioner according to Embodiments 22 and 23.

FIG. 24 is a block diagram showing a diaphragm device control device according to a twenty-second embodiment.

FIG. 25 is a flowchart illustrating a diaphragm device control operation according to the twenty-second embodiment.

FIG. 26 is a block diagram showing a defrost control device according to a twenty-third embodiment.

FIG. 27 is a flowchart illustrating a defrost control operation according to the twenty-third embodiment;

FIG. 28 is a refrigerant circuit diagram of a conventional air conditioner.

[Explanation of symbols]

A heat source unit, B, C, D indoor unit, 1 compressor, 2 switching valve, 3 heat source unit side heat exchanger, 4 accumulator, 5
Oil return hole of accumulator 4, 6 Second expansion device (heating expansion device), 7b, 7c, 7d Indoor unit side heat exchanger, 8b, 8c, 8d First expansion device (cooling expansion device) , 9 liquid side connection refrigerant pipe, 10 gas side connection refrigerant pipe, 15 bypass circuit, 16 dryer, 17 third expansion device (bypass expansion device), 18, 27 bypass heat exchanger, 18a first bypass heat exchanger , 18
b second bypass heat exchanger, 19 first temperature detecting means, 20 second temperature detecting means, 21 suction pressure detecting means, 22 composition calculating means, 23 oil separator, 24 oil return bypass circuit, 25 fourth Throttle device, 26 sludge filter, 28 liquid refrigerant injection circuit, 29 liquid injection circuit heat exchanger, 30 fifth throttle device, 31 discharge pressure detecting means, 32 third temperature detecting means, 33b, 33c, 33
d Fourth temperature detecting means, 34b, 34c, 34d Fifth temperature detecting means, 35 Throttling device control device, 36 S
C calculating means, 37 SH calculating means, 38 throttle device controlling means, 39b, 39c, 39d blower for defrosting, 40b,
40c, 40d Drain pump, 41b, 41c, 41
d Defrosting control device, 62 Accumulator outflow pipe, 6
4 Oil return piping.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shin Sekiya 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Iijima et al. 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Rishi Electric Co., Ltd. (72) Inventor Toshihide Koda 2-3-2 Marunouchi, Chiyoda-ku, Tokyo

Claims (17)

[Claims] 1. A main refrigerant circuit comprising a compressor, a condenser, a throttle device, and an evaporator, wherein a hydrofluorocarbon-based refrigerant is used as a working medium, and oil compatible with the refrigerant is refrigerated. In air conditioners used as machine oil,
A bypass branched from a refrigerant pipe between the condenser and the expansion device and connected to a refrigerant pipe between the expansion device and the compressor of the main refrigerant circuit via a dryer and a bypass expansion device that absorb moisture; An air conditioner comprising a circuit. 2. A main refrigerant circuit comprising a compressor, a condenser, a throttle device, and an evaporator, wherein a hydrofluorocarbon-based refrigerant is used as a working medium, and oil compatible with the refrigerant is refrigerated. In air conditioners used as machine oil,
An air conditioner comprising a bypass circuit branched from a refrigerant pipe on a discharge side of the compressor and connected to a refrigerant pipe on a suction side of the compressor via a dryer for absorbing moisture and a bypass throttle device. apparatus. 3. The air conditioner according to claim 1, wherein a bypass heat exchanger for cooling the refrigerant flowing into the dryer is provided in the middle of the bypass. 4. A heat source unit comprising a compressor, a switching valve, a heat source unit side heat exchanger and a heating throttle unit, an indoor unit comprising a cooling unit and an indoor heat exchanger, and heating the heat source unit. A liquid-side connecting refrigerant pipe for connecting one end of the expansion device to one end of the indoor unit at the time of the expansion device, and one end of the heat source unit on the switching valve side and one end of the indoor unit on the indoor heat exchanger side An air conditioner using a hydrofluorocarbon-based refrigerant as a working medium, and an oil compatible with the refrigerant as a refrigerating machine oil. A branch that is branched from the liquid-side connection refrigerant pipe, has a dryer that absorbs moisture, a bypass expansion device, and a bypass heat exchanger that cools the refrigerant flowing into the dryer, between the compressor suction part and the switching valve. Connected to refrigerant pipe An air conditioner comprising a bypass circuit. 5. A heat source unit comprising a compressor, a switching valve and a heat source unit side heat exchanger, an indoor unit comprising a throttling device and an indoor side heat exchanger, and one end of the heat source unit on the heat source unit side heat exchanger side. And a liquid-side connection refrigerant pipe connecting one end of the indoor unit on the throttle device side, and a gas side connection connecting one end of the heat source unit on the switching valve side and one end of the indoor unit on the indoor heat exchanger side. An air conditioner including a main refrigerant circuit having a refrigerant pipe, using a hydrofluorocarbon-based refrigerant as a working medium, and using oil compatible with the refrigerant as refrigerating machine oil,
Branched from a refrigerant pipe between the compressor discharge portion and the switching valve, via a bypass heat exchanger that cools the refrigerant, a dryer that absorbs moisture and a bypass throttle device, the compressor suction portion and the switching valve An air conditioner comprising a bypass circuit connected to a refrigerant pipe between the air conditioners. 6. A method according to claim 1, wherein a hydrofluorocarbon-based mixed refrigerant is used as a working medium. The first temperature detecting means is provided at an inlet of the bypass expansion device, and is provided downstream of the bypass expansion device in the middle of the bypass. Second temperature detecting means;
A suction pressure detecting means provided in the compressor suction portion; and a composition calculating means for calculating a composition of the refrigerant based on detection values of the first and second temperature detecting means and the suction pressure detecting means. The air conditioner according to any one of claims 1 to 5, wherein 7. A main refrigerant circuit including a compressor, a condenser, a throttle device, and an evaporator, wherein a hydrofluorocarbon-based refrigerant is used as a working medium, and oil compatible with the refrigerant is refrigerated. In air conditioners used as machine oil,
An air conditioner comprising: an oil separator provided at the compressor discharge section; and an oil return bypass circuit for returning separated refrigeration oil to the compressor suction section. 8. The air conditioner according to claim 7, wherein a sludge filter is provided in the middle of the oil return bypass circuit. 9. The air conditioner according to claim 8, wherein a bypass heat exchanger for cooling refrigerating machine oil is provided upstream of the sludge filter in the oil return bypass circuit. 10. The air conditioner according to claim 8, further comprising a liquid refrigerant injection circuit for injecting the liquid refrigerant upstream of the sludge filter in the middle of the oil return bypass circuit. 11. The air conditioner according to claim 8, wherein the sludge filter in the middle of the oil return bypass is a dryer that absorbs moisture and has a sludge filter function. 12. The dryer according to claim 1, wherein the mounting posture of the dryer is downward with respect to the flow direction.
The air conditioner according to any one of the above. 13. The heat exchanger according to claim 3, wherein all or a part of the bypass heat exchanger passes through a lowermost portion of the heat source device side heat exchanger. Air conditioner. 14. A compressor, a condenser, a throttle device, an evaporator,
Equipped with a main refrigerant circuit composed of an accumulator, using a hydrofluorocarbon-based refrigerant as a working medium,
In an air conditioner using an oil compatible with the refrigerant as the refrigerating machine oil, the refrigerating machine oil stored at the bottom of the accumulator is arranged in parallel at two locations above and below a refrigerant outlet pipe from the accumulator to the compressor. An air conditioner comprising an oil return mechanism for returning oil to the air conditioner. 15. A refrigerant circuit comprising a main refrigerant circuit comprising a compressor, a condenser, a throttle device, and an evaporator, using a hydrofluorocarbon-based refrigerant as a working medium, and refrigerating oil compatible with the refrigerant. In air conditioners used as machine oil,
An upper limit opening for controlling the expansion device so that the degree of superheat at the outlet of the evaporator calculated from the medium temperatures at the inlet and outlet of the evaporator is within a certain range, and suppressing excessive valve opening due to control divergence; Is provided, the superheat degree of the evaporator outlet exceeds a certain range, when the opening degree of the expansion device reaches the upper limit opening degree, the refrigerant temperature on the inlet side of the expansion device,
A throttle device control device that greatly corrects the upper limit opening when the degree of supercooling at the throttle device inlet calculated from the discharge side pressure of the compressor and the composition of the refrigerant is a predetermined value or more. And air conditioners. 16. A hydrofluorocarbon system comprising a main refrigerant circuit having a heat source unit comprising a compressor, a heat source unit side heat exchanger, and a plurality of indoor units comprising a throttling device and an indoor side heat exchanger. In an air conditioner using a refrigerant as a working medium and an oil compatible with the refrigerant as a refrigerating machine oil, in each of the indoor units, a blower for defrosting, and when only some of the indoor units are performing a cooling operation. A defrost control device that operates the blower when the medium temperature at the outlet side of the indoor heat exchanger of the indoor unit that is not performing the cooling operation continuously falls below the predetermined temperature for a predetermined time. And air conditioners. 17. An indoor unit that starts operating at the same time as a blower for defrosting and is controlled by a defrosting control device to stop after a lapse of a predetermined time from the stoppage of the operation of the blower. The air conditioner according to claim 19, further comprising a drain pump for draining the drain.