JP2010127482A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide satisfactory reliability of a compressor by storing part of a refrigerant charged in anticipation of an operation of all of indoor units, in part of a refrigerant circuit, and returning the refrigerant to the compressor according to changing situations. <P>SOLUTION: In the air conditioner including the compressor 21, a four-way valve 22, an outdoor heat exchanger 23, a pressure reducer 24, and an indoor heat exchanger 47, an accumulator 25 for storing a gas-liquid mixture of the refrigerant including oil after heat exchange, is disposed between the four-way valve 22 and the compressor 21, a plurality of return adjustment pipes 36a, 36b, ... respectively set in different heights of returned liquid, are disposed in the accumulator 25, the return adjustment pipes 36a, 36b, ... are connected with the return pipe 35 through solenoid valves 37a, 37b, ... respectively selectively opened and closed according to driving situation, and the return pipe 35 is connected between the accumulator 25 and the compressor 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  According to the present invention, a part of refrigerant including oil filled in anticipation of operation of all connected indoor units is stored in a part of the refrigerant circuit, and arbitrarily returned to the compressor in accordance with a change in the operation state. The present invention relates to an air conditioner that makes it possible.

  A VRF (Building Multi-Air Conditioner) system is operated by connecting a large number of indoor units to one or a plurality of outdoor units. For example, when 18 indoor units are connected and the maximum pipe length is 150 m, the lubricating oil for the compressor of the outdoor unit is previously set so that the optimum operation can be performed in the operating state at the maximum connection. The refrigerant circuit is filled in the refrigerant circuit. However, in spite of the fact that the actual number of operating units has not reached the maximum number, circulating all the refrigerant in the refrigerant circuit not only lowers the operation efficiency but also adversely affects the performance of the compressor. Therefore, a part of the refrigerant is stored in the accumulator according to the operation status. The refrigerant stored in the accumulator is returned to the compressor when the number of indoor units increases.

Conventionally, there has been known a method of always returning a refrigerant containing lubricating oil to a compressor from an accumulator regardless of various operating states such as light load operation, normal load operation, and overload operation (Patent Document 1).
According to this Patent Document 1, as shown in FIG. 4, the accumulator body 10 is provided through the gas discharge pipe 11 having the gas discharge port 12, and the accumulator body 10 has the gas suction port 14. A first oil return pipe provided through the gas suction pipe 13, an orifice 15 provided on the side of the gas suction pipe 13 connected to the compressor, and the bottom of the accumulator body 10 having different heights sequentially. 16a, a second oil return pipe 16b, and a third oil return pipe 16c are provided, and the other ends of these oil return pipes 16a, 16b, and 16c are connected to the rear side of the orifice 15 in the gas suction pipe 13.

The operation in the configuration as described above is described in Patent Document 1 as follows. Note that FIG. 4 showing the conventional example is shown as FIG. 5 in Patent Document 1 and the operation explanation is described for the case of FIG. 4. Therefore, in the following explanation, one example is given to correspond to the case of FIG. The part has been rewritten.
“When the load is reduced and the capacity control operation is performed, the liquid level in the accumulator rises and the upper ends of the oil return pipes 16a, 16b, and 16c are in the liquid. The upper end of the return pipe 16a is in the lubricating oil layer when the refrigerant liquid and the lubricating oil are two-phase separated in a refrigerant liquid with a high density of lubricating oil or in the case of a low temperature. Then, due to the differential pressure PL2-P, the refrigerant gas is returned to the compressor together with the refrigerant gas from the gas suction pipe 13 following the compressor suction port.
Also, in the case of a normal operation state, when the liquid level is not as high as in the above case, similarly, the upper end of the oil return pipe 16b is in a refrigerant liquid with a high density of lubricating oil or separated into two phases. If it is, it is in the lubricating oil layer and returns the lubricating oil to the compressor.
Similarly, when the liquid level decreases due to overload operation, the upper end portion of the oil return pipe 16c is in the lubricating liquid layer portion when the lubricating oil density is high or in the case of two-phase separation. Yes, return the lubricant to the compressor.
As described above, the lubricating oil can always be returned to the compressor from the accumulator regardless of various operating states such as light load operation, normal operation, and overload operation. "
Japanese Utility Model Publication No. 52-70319.

However, the method described in Patent Document 1 has the following problems.
That is, since all three oil return pipes 16a, 16b, and 16c are opened inside the accumulator body 10, when the liquid level 46 is higher than h1 of the first oil return pipe 16a, the lowest third oil The refrigerant containing oil is returned in all of the three oil return pipes 16a, 16b and 16c until the return pipe 16c reaches h3.
Even when the liquid level 46 is slightly higher than h2 of the oil return pipe 16b, the refrigerant containing oil is returned by the two oil return pipes 16b and 16c until it reaches h3 of the oil return pipe 16c.
When the liquid level 46 is slightly higher than h3 of the oil return pipe 16c, the refrigerant containing oil is returned through one oil return pipe 16c until the liquid level 46 reaches h3 of the oil return pipe 16c.
Therefore, in the method described in Patent Document 1, regardless of overload, normal load, and light load, the refrigerant containing oil is returned until the oil return pipe 16c reaches h3. This has the problem that the oil return cannot be controlled according to overload, normal load, or light load.

  According to the present invention, a part of refrigerant including oil filled in anticipation of operation of all connected indoor units is stored in a part of the refrigerant circuit, and arbitrarily returned to the compressor in accordance with a change in the operation state. Accordingly, an object of the present invention is to provide an air conditioner that can sufficiently reduce the consumption of electric power in the compressor and sufficiently satisfy the reliability.

An air conditioner according to the present invention is an air conditioner including a compressor, a four-way valve, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger, and heat exchange is performed between the four-way valve and the compressor. An accumulator that stores the gas-liquid mixture of the refrigerant that contains the later oil is arranged, and a plurality of return adjustment pipes with different return liquid heights are provided in the accumulator, and each of these return adjustment pipes is adapted to the operating situation. The return pipe is connected via a solenoid valve that is selectively opened and closed, and the return pipe is connected between the accumulator and the compressor.

The amount of refrigerant including oil charged for operation at the maximum load in the air conditioner is circulated in the refrigerant circuit for the amount necessary for optimal operation according to the operating condition, and the rest is stored in the accumulator. The valve is controlled to open and close.

When a plurality of indoor units are connected to the outdoor unit, the plurality of return adjustment pipes for setting the return liquid height of the refrigerant containing oil are, in order from the highest, cooling operation by one indoor unit, by one indoor unit It is characterized by being adapted to heating operation, cooling operation by all connected indoor units, and heating operation by all connected indoor units.

It is characterized in that it is also used as a return adjustment pipe for cooling operation by all indoor units connected to heating operation by one indoor unit.

In the case where a plurality of indoor units are connected to the outdoor unit, the plurality of solenoid valves are selectively controlled to open and close based on the number of actually operating indoor units scanned.

The plurality of solenoid valves are selectively opened and closed based on changes in the discharge temperature of the refrigerant containing the oil of the compressor.

  The plurality of solenoid valves can also be controlled to open simultaneously the solenoid valve of the return adjustment pipe that is higher than the solenoid valve at the height of the selected return adjustment pipe.

According to the first aspect of the present invention, in an air conditioner including a compressor, a four-way valve, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger, the air conditioner is provided between the four-way valve and the compressor. An accumulator that stores the gas-liquid mixture of the refrigerant that contains the heat-exchanged oil is arranged, and a plurality of return adjustment pipes with different return liquid heights are provided in the accumulator, and each of these return adjustment pipes has an operating status. Since the return pipe is connected between the accumulator and the compressor through an electromagnetic valve that is selectively opened and closed according to the pressure, the oil that has been filled in assuming the maximum load of the air conditioner. The refrigerant containing unnecessary oil during normal operation, light load, etc. is stored in the accumulator, and one of multiple return adjustment pipes with different return liquid heights is used depending on the operating conditions. By selectively opening with a solenoid valve, The can be sent to the compressor, the reliability of the compressor can be sufficiently satisfied.

According to the second aspect of the present invention, among the refrigerant amount including oil filled for the operation at the maximum load in the air conditioner, an amount necessary for the optimum operation according to the operation state is circulated in the refrigerant circuit. Since the plurality of solenoid valves are selectively opened and closed so as to store the remainder in the accumulator, it is possible to perform an optimal operation with less power consumption without using wasted power.

According to the third aspect of the present invention, when a plurality of indoor units are connected to the outdoor unit, the plurality of return adjustment pipes for setting the return liquid height of the refrigerant containing the oil are sequentially set from the higher one to the indoor unit 1. The cooling operation by the stand, the heating operation by one indoor unit, the cooling operation by all the connected indoor units, and the heating operation by all the connected indoor units are supported. It can cope with changes in all situations such as light loads.

According to the invention of claim 4, since the heating operation by one indoor unit and the return adjustment pipes for the cooling operation by all the connected indoor units are also used, the number of return adjustment pipes is reduced. Operation control can be simplified with less.

  According to the fifth aspect of the present invention, when a plurality of indoor units are connected to the outdoor unit, the plurality of solenoid valves are selectively controlled to open and close based on the number of actually operated indoor units. Therefore, the efficiency as an air conditioner corresponding to a load that is actually driven can be improved.

  According to the invention described in claim 6, since the plurality of solenoid valves are selectively controlled to open and close based on the change in the discharge temperature of the refrigerant including the compressor oil, the compressor is always driven normally. Useless driving can be eliminated.

  According to the seventh aspect of the present invention, the plurality of solenoid valves are controlled so as to simultaneously open the solenoid valves of the return adjustment pipe having a higher return liquid height than the solenoid valves having the height of the selected return adjustment pipe. As a result, the oil can be quickly returned to the compressor, the movable part including the compressor can be prevented from being damaged, and air conditioning can be promptly performed according to the intended purpose. Therefore, it is possible to provide an air conditioner that can sufficiently satisfy the reliability of the compressor in response to changes in various situations in the VRF (multi air conditioner for buildings) system.

The present invention relates to an air conditioner including a compressor, a four-way valve, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger, and the oil after heat exchange is provided between the four-way valve and the compressor. An accumulator for storing the gas-liquid mixture of the refrigerant is disposed, and a plurality of return adjustment pipes set with different return liquid heights are provided in the accumulator, and each of these return adjustment pipes is selectively selected according to the operating situation. The return pipe is connected via an electromagnetic valve that is opened and closed, and this return pipe is connected between the accumulator and the compressor.

A plurality of refrigerant quantities including oil filled for operation at the maximum load in the air conditioner are circulated in the refrigerant circuit, and the rest is stored in the accumulator. The solenoid valve is selectively opened and closed. Specifically, in the case where a plurality of indoor units are connected to the outdoor unit, the plurality of return adjustment pipes for setting the return liquid height of the refrigerant containing oil are cooled by one indoor unit in order from the highest. Operation, heating operation with one indoor unit, cooling operation with all connected indoor units, and heating operation with all connected indoor units are made to correspond.
You may make it also serve as the return adjustment pipe for the cooling operation by all the indoor units connected with the heating operation by one indoor unit.
The plurality of solenoid valves may be selectively controlled to open and close based on the number of actually operated indoor units that have been scanned or the single information on the change in the oil discharge temperature due to the refrigerant in the compressor.

The plurality of solenoid valves may be selectively controlled to open and close based on changes in the discharge temperature of the compressor.
Further, the plurality of solenoid valves can be controlled so as to simultaneously open the solenoid valves of the return adjustment pipe having a higher return liquid height than the solenoid valve having the height of the selected return adjustment pipe.

A first embodiment of an air conditioner according to the present invention will be described with reference to FIGS.
In FIG. 1, reference numeral 18 denotes an outdoor unit, which functions as a condenser during a cooling operation and functions as an evaporator during a heating operation, in addition to the outdoor heat exchanger 23, the compressor 21, and the four-way valve 22. The accumulator 25 is a main component. One example of the outdoor unit 18 is illustrated, but a plurality of the outdoor units 18 may be connected in parallel.
An indoor unit 19 is connected to the outdoor unit 18 by a pipe 20.
This indoor unit 19 is configured by connecting in parallel a plurality of each indoor unit in which an indoor heat exchanger 47 and a decompressor 24 that function as an evaporator during cooling operation and function as a condenser during heating operation are connected in series. used. In a VRF (building air conditioner) system, the maximum number of operating units is, for example, 18 indoor units connected and a pipe length of 150 m.

  The compressor 21 is a rotary type variable speed first compressor 21a and a scroll type constant speed second compressor 21b connected in parallel. An accumulator 27 for the first compressor 21a is connected to the inlet side of the first compressor 21a, an oil separator 30a is connected to the outlet side, and an oil separator is connected to the outlet side of the second compressor 21b. A device 30b is connected. The oil separator 30a and the oil separator 30b are respectively connected to the port A of the four-way valve 22 via a check valve 32, and are connected to a bypass pipe 38 having an electronic expansion valve 28 and a capillary tube 29. . In addition, the circulation path 31 of the first compressor 21a and the circulation path 31 of the oil separator 30a are coupled to the inlet side of the second compressor 21b via an electronic expansion valve 28 and a capillary tube 29, respectively. A circulation path 31 of the vessel 30b is coupled to the accumulator 27 through a capillary tube 29. 43 is a temperature sensor which detects the temperature of the refrigerant | coolant containing the oil in the main body side surface and discharge end of the 1st compressor 21a and the 2nd compressor 21b.

  An inlet side of the outdoor heat exchanger 23 is coupled to the port B of the four-way valve 22. The outdoor heat exchanger 23 is provided with a fan 39 for promoting heat radiation during cooling operation and heat absorption during heating operation. In addition, temperature sensors 43 are attached to the outdoor heat exchanger 23 at two locations on the side of the main body and at the discharge end.

  The outlet side of the outdoor heat exchanger 23 is connected to a subcool heat exchanger 42 via a check valve 32, an on-off valve 40, an electronic expansion valve 28, and a pressure valve 41 that are connected in parallel to each other. In the subcool heat exchanger 42, a part of the flowing refrigerant is heat-exchanged and returned to the gas discharge pipe 33 described later. The subcool heat exchanger 42 is provided with temperature sensors 43 at three locations.

  In general, the accumulator 25 temporarily stores a refrigerant containing oil. However, in the present invention, a part of the refrigerant containing oil filled in anticipation of operation of all connected indoor units is used. Then, the refrigerant containing the stored oil is arbitrarily returned to the compressor 21 so as to be stored in the accumulator 25 and in an optimum operation state according to the change of the situation, and wasteful consumption of electric power in the compressor 21 is omitted. It plays a role.

A gas discharge pipe 33 connected to the port C of the four-way valve 22 passes through the accumulator 25, and a discharge port 44 at the tip is provided toward the inner wall of the accumulator 25 for gas-liquid separation. A gas suction pipe 34 having a suction port 45 is provided therethrough. At the bottom of the accumulator 25, four first return adjustment pipes 36a, second return adjustment pipes 36b, and third return adjustment pipes for returning the refrigerant containing oil whose opening portions at the upper end are successively different in height. 36c and a fourth return adjustment pipe 36d are provided, and connected to the return pipe 35 via the electromagnetic valve 37a, the electromagnetic valve 37b, the electromagnetic valve 37c, and the electromagnetic valve 37d, respectively, at the other end thereof, and further as required. The return pipe 35 is connected to the gas suction pipe 34 through a capillary tube 29 for gasification.

The height of the opening at the upper end of each of the four first return adjustment pipes 36a, second return adjustment pipes 36b, third return adjustment pipes 36c, and fourth return adjustment pipes 36d is determined by the actual operation of the indoor unit. The amount of refrigerant stored in the accumulator 25 is optimally set in accordance with the number of units, for example, the first highest first return adjustment pipe 36a is provided with a cooling operation by one indoor unit, and the second highest second return. The adjustment pipe 36b is a heating operation by one indoor unit, the third highest third return adjustment pipe 36c is a cooling operation by all the connected indoor units, and the fourth highest fourth return adjustment pipe 36d is connected. It is set corresponding to the amount of each refrigerant stored in the accumulator 25 in the heating operation by all indoor units.
The setting of the amount of refrigerant to be stored is not limited to the number of indoor units that are actually operating, but the installation length of other pipes, changes in the discharge temperature of refrigerant containing oil in the compressor, cooling or heating It is set in a plurality of stages depending on the combination of any one or two or more situation changes such as the difference in the operation mode.
The open / close control conditions of the electromagnetic valves 37a, 37b, 37c, and 37d provided in the first, second, third, and fourth return adjustment pipes 36a, 36b, 36c, and 36d are stored in a microcomputer (not shown). , And can be selectively switched corresponding to the four stages according to the driving situation.

  The other end of the gas suction pipe 34 connected to the return pipe 35 is divided into two by the flow divider 26 and connected to the first compressor 21a and the second compressor 21b side.

Next, the operation of the air conditioner will be described.
During the cooling operation, switching is performed so that the ports A and B of the four-way valve 22 communicate with each other and the ports C and D communicate with each other (solid arrow state in FIG. 1). Then, the refrigerant containing oil becomes high-pressure superheated steam by the first and second compressors 21a and 21b and is sent to the outdoor heat exchanger 23. The steam is condensed and radiated by the outdoor heat exchanger 23, and the high-pressure saturated liquid The check valve 32, the electronic expansion valve 28, the subcool heat exchanger 42, and the like are interposed, and further sent to the decompressor 24 of the indoor unit 19 through the pipe 20. The decompressor 24 forms a low-temperature wet steam and supplies it to the indoor heat exchanger 47. The indoor heat exchanger 47 evaporates the wet steam and absorbs heat (cooling effect) to form a low-pressure saturated steam. It returns to the 1st, 2nd compressor 21a, 21b through the valve 22 and the accumulator 25. FIG.

During the heating operation, switching is performed so that the ports A and D of the four-way valve 22 communicate with each other and the ports B and C communicate with each other (in the state of the dotted arrow in FIG. 1). Then, the oil-containing refrigerant becomes high-pressure superheated steam by the first and second compressors 21a and 21b and is sent to the indoor heat exchanger 47 of the indoor unit 19, where the high-pressure superheated steam condenses and dissipates heat. (Heating effect), becomes a high-pressure saturated liquid, is depressurized by the decompressor 24, and is sent to the outdoor heat exchanger 23 of the outdoor unit 18 through the subcool heat exchanger 42 and the electronic expansion valve 28. The wet steam evaporates in the outdoor heat exchanger 23, absorbs heat, becomes low-pressure saturated steam, and returns to the first and second compressors 21a and 21b via the four-way valve 22 and the accumulator 25.
During the operation of the first and second compressors 21a and 21b, the amount of refrigerant containing oil discharged from the second compressor 21b is larger than that of the first compressor 21a, so that the refrigerant circulates from the first compressor 21a side. Oil is supplied to the second compressor 21b side via the path 31, and the oil circulates from the oil separator 30b to the first compressor 21a.

Specific opening / closing control during such cooling or heating operation will be described.
(1) At the time of cooling operation at the minimum load, for example, at the time of cooling operation by one indoor unit, if the liquid level 46 is set to H1, as shown in FIG. The electromagnetic valve 37a of the return adjustment pipe 36a is opened.
When operating in this state, the refrigerant containing oil from the liquid level 46 to H1 is sucked from the upper end opening of the first return adjustment pipe 36a due to the negative pressure of the compressor 21, gasified by the capillary tube 29, and gas suction pipe 34 Together with the gas refrigerant from the first and second compressors 21a and 21b. Therefore, the refrigerant containing oil of H1 or less is stored in the accumulator 25.

(2) If the liquid level 46 is set to H2 at the time of heating operation at the minimum load, for example, at the time of heating operation by one indoor unit, the solenoid valve of the second return adjustment pipe 36b that is the second highest by a command from the microcomputer 37b is opened.
When operating in this state, the refrigerant containing oil from the liquid level 46 to H2 is sucked from the upper end opening of the first return adjustment pipe 36b by the negative pressure of the compressor 21, and is gasified by the capillary tube 29 to be gas suction pipe 34. Together with the gas refrigerant from the first and second compressors 21a and 21b. Therefore, the refrigerant containing oil of H2 or less is stored in the accumulator 25.

(3) If the liquid level 46 is set to H3 during the cooling operation at the maximum load, for example, during the cooling operation by all the connected indoor units, the third return adjustment pipe that is the third highest in response to a command from the microcomputer The solenoid valve 37c of 36c is opened.
When operating in this state, the refrigerant containing oil from the liquid level 46 to H3 is sucked from the upper end opening of the first return adjustment pipe 36c by the negative pressure of the compressor 21, and is gasified by the capillary tube 29 to be gas suction pipe 34. Together with the gas refrigerant from the first and second compressors 21a and 21b. Therefore, the refrigerant containing H3 or less oil is stored in the accumulator 25.

(4) If the liquid level 46 is set to H4 at the time of heating operation at the maximum load, for example, at the time of heating operation by all the connected indoor units, the fourth return adjustment pipe that is the fourth highest in response to a command from the microcomputer The 36d solenoid valve 37d is opened.
When operating in this state, the refrigerant containing the oil from the liquid level 46 to H4 is sucked from the upper end opening of the first return adjustment pipe 36d by the negative pressure of the compressor 21, and is gasified by the capillary tube 29 to be gasified. Together with the gas refrigerant from the first and second compressors 21a and 21b. Therefore, the refrigerant containing H4 or lower oil is stored in the accumulator 25.

In the first embodiment, four first, second, third, and fourth return adjustment pipes 36 having different heights are attached in the accumulator 25, but the number is not limited to this, and a plurality If so, it may be 5 or more.
In addition, the second highest second return adjustment pipe 36b and the third highest third return adjustment pipe 36c have one of the same height to be three in total, and are connected to the heating operation by one indoor unit. You may make it also use the return adjustment pipe for the cooling operation by all the indoor units which are present.
In the first embodiment, the compressor 21 is a parallel operation of the rotary first compressor 21a and the scroll second compressor 21b. However, the present invention is not limited to this, and one or three or more compressors are used. It doesn't matter what type of compressor it is.

In the first embodiment, in the air conditioner that uses both the cooling operation and the heating operation by switching the four-way valve 22, the first return adjustment pipe 36a, the second return adjustment pipe 36b, and the third return according to the change of the situation. The example in which the height positions H1, H2, H3, H4 of the return adjustment pipe 36c and the fourth return adjustment pipe 36d are selectively set by opening / closing the electromagnetic valve 37 has been described.
However, the present invention is not limited to this, and even in an air conditioner dedicated to heating operation, it may be desired to store a refrigerant containing excess oil in an accumulator.
The same applies to an air conditioner dedicated to cooling operation.
For example, in the case of exclusive use for heating operation, the amount of refrigerant including oil circulating in the refrigerant circuit increases and the amount of refrigerant stored in the accumulator 25 decreases. Therefore, the first return adjustment pipe 36a, the second Finer control can be performed by finely setting the height positions H1, H2, H3, and H4 of the return adjustment pipe 36b, the third return adjustment pipe 36c, and the fourth return adjustment pipe 36d at low positions.
Similarly, in the case of cooling operation only, the amount of refrigerant including oil circulating in the refrigerant circuit decreases and the amount of refrigerant stored in the accumulator 25 increases. Therefore, the first return adjustment pipe 36a, Finer control can be performed by finely setting the height positions H1, H2, H3, and H4 of the second return adjustment pipe 36b, the third return adjustment pipe 36c, and the fourth return adjustment pipe 36d at high positions.
As a result, the return amount of the refrigerant containing oil is arbitrarily changed according to the change of the situation, the wasteful power consumption in the compressor is reduced as much as possible, and an air conditioner that can sufficiently satisfy the reliability is provided. can do.

  In the above-described embodiment, the first return adjustment pipe 36a, the second return adjustment pipe 36b, the third return adjustment pipe 36c, and the fourth return adjustment pipe 36d are provided to rise from the bottom of the accumulator 25, but are suspended from the ceiling side. Or you may provide horizontally or diagonally from the side.

When a plurality of indoor units are connected to the outdoor unit, the plurality of solenoid valves can be selectively opened and closed based on the number of actually operated indoor units. For that purpose, it is scanned whether each drive switch is turned on or off at regular intervals to determine which indoor unit is currently operating among the entire indoor units 19 configured by connecting a plurality of indoor units in parallel. The number of indoor units driven is counted, and electromagnetic valves 37a, 37b connected to the first, second, third, and fourth return adjustment pipes 36a, 36b, 36c, 36d based on the data. , 37c, 37d are selectively opened to set the amount of refrigerant stored in the accumulator 25.

  The plurality of solenoid valves can be selectively opened and closed based on a change in the discharge temperature of the refrigerant containing the compressor oil. For example, when the amount of refrigerant in the refrigerant circuit increases during heating operation, the discharge temperatures of the first and second compressors 21a and 21b gradually increase, and the detected value and the reference value of any one of the temperature sensors 43 are calculated. The comparison circuit compares. More specifically, when the discharge temperatures of the two temperature sensors 43a at the main body side wall and the discharge end of the first compressor 21a both exceed the set values, the measured value and the reference value are compared by the comparison circuit, and the data is Accordingly, the first, second, third, and fourth return adjustment pipes 36a, 36b, 36c, and 36d are provided so as to reduce the amount of refrigerant stored in the accumulator 25 and increase the amount of refrigerant returned to the compressor. The connected solenoid valves 37a, 37b, 37c, and 37d are selectively opened. The same applies to the second compressor 21b. The same applies when the discharge temperatures of the four temperature sensors 43 of the first and second compressors 21a and 21b all exceed the set value.

  The plurality of solenoid valves can be controlled to simultaneously open the solenoid valve of the return adjustment pipe having a higher return liquid height than the solenoid valve of the height of the selected return adjustment pipe. That is, only one of the electromagnetic valves 37a, 37b, 37c, and 37d connected to the first, second, third, and fourth return adjustment pipes 36a, 36b, 36c, and 36d is selectively opened. Instead, the solenoid valves of a plurality of return adjustment pipes having a higher return liquid height than the solenoid valve of the selected return adjustment pipe height can be simultaneously opened.

It is a refrigerant circuit figure which shows one Example of the air conditioner by this invention. It is explanatory drawing at the time of the driving | operation which set the liquid level 46 of the accumulator 25 provided in the air conditioner by this invention to H3. It is explanatory drawing at the time of the driving | operation which set the liquid level 46 of the accumulator 25 provided in the air conditioner by this invention to H1. It is explanatory drawing of the conventional accumulator main body 10. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Accumulator main body, 11 ... Gas discharge pipe, 12 ... Gas discharge port, 13 ... Gas suction pipe, 14 ... Gas suction port, 15 ... Orifice, 16 ... Oil return pipe, 16a ... First oil return pipe, 16b ... First 2 oil return pipe, 16c ... 3rd oil return pipe, 17a ... refrigerant (high oil density), 17b ... refrigerant (low oil density), 18 ... outdoor unit, 19 ... indoor unit, 20 ... piping, 21 ... compressor, 21a ... 1st compressor, 21b ... 2nd compressor, 22 ... Four way valve, 23 ... Outdoor heat exchanger, 24 ... Decompressor, 25 ... Accumulator, 26 ... Shunt, 27 ... Accumulator, 28 ... Electronic expansion valve, DESCRIPTION OF SYMBOLS 29 ... Capillary tube, 30a ... Oil separator, 30b ... Oil separator, 31 ... Circulation path, 32 ... Check valve, 33 ... Gas discharge pipe, 34 ... Gas suction pipe, 35 ... Return pipe, 36 ... Return adjustment pipe, 36a ... 1st return adjustment pipe, 36b ... 2nd return adjustment pipe 36c ... 3rd return adjustment pipe, 36d ... 4th return adjustment pipe, 37 ... Solenoid valve, 37a ... Solenoid valve, 37b ... Solenoid valve, 37c ... Solenoid valve, 37d ... Solenoid valve, 38 ... Bypass pipe, 39 ... Fan, DESCRIPTION OF SYMBOLS 40 ... Open / close valve, 41 ... Pressure valve, 42 ... Subcool heat exchanger, 43 ... Temperature sensor, 44 ... Discharge port, 45 ... Suction port, 46 ... Liquid level, 47 ... Indoor heat exchanger

Claims (7)

  In an air conditioner including a compressor, a four-way valve, an outdoor heat exchanger, a pressure reducer, and an indoor heat exchanger, a refrigerant gas containing oil after heat exchange between the four-way valve and the compressor. An accumulator for storing the liquid mixture is arranged, and a plurality of return adjustment pipes having different return liquid heights are provided in the accumulator, and the return adjustment pipes are electromagnetically selectively opened and closed according to operating conditions. An air conditioner characterized in that it is connected to a return pipe via a valve, and this return pipe is connected between the accumulator and the compressor. A plurality of refrigerant quantities including oil filled for operation at the maximum load in the air conditioner are circulated in the refrigerant circuit, and the rest is stored in the accumulator. The air conditioner according to claim 1, wherein the electromagnetic valve is selectively controlled to open and close. When a plurality of indoor units are connected to the outdoor unit, the plurality of return adjustment pipes for setting the return liquid height of the refrigerant containing oil are, in order from the highest, cooling operation by one indoor unit, by one indoor unit 2. The air conditioner according to claim 1, wherein the air conditioner is adapted for heating operation, cooling operation by all connected indoor units, and heating operation by all connected indoor units. The air conditioner according to claim 3, wherein the air conditioner is also used as a return adjustment pipe for cooling operation by all indoor units connected to heating operation by one indoor unit. The open / close control is selectively performed based on the number of actually operated indoor units when the plurality of indoor units are connected to the outdoor unit. Air conditioner.   The air conditioner according to claim 1, wherein the plurality of solenoid valves are selectively opened and closed based on a change in discharge temperature of refrigerant including oil of the compressor.   2. The solenoid valve according to claim 1, wherein the plurality of solenoid valves are controlled so as to simultaneously open the solenoid valves of the return adjustment pipe having a higher return liquid height than the solenoid valve having the height of the selected return adjustment pipe. Air conditioner.

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