JP5655014B2 - Air conditioner - Google Patents

Description

  The present invention relates to an outdoor unit having a plurality of compressors and an air conditioner that constitutes a refrigeration cycle with a plurality of indoor units, and particularly to an oil return structure for evenly storing lubricating oil in each compressor. Regarding improvements.

  There are air conditioners that are optimal for buildings with multiple air-conditioned locations. In this type of air conditioner, an oil return circuit that takes out the lubricating oil that has accumulated in each compressor over a specified amount through the oil equalizing pipe and passes it to the compressor that lacks the extracted lubricating oil. It has.

  Further, since the high-temperature and high-pressure gas refrigerant discharged from each compressor contains lubricating oil, and there are a plurality of compressors, the amount of discharged lubricating oil cannot be ignored. Therefore, an oil separator is provided in the refrigeration cycle to separate the oil content of the lubricating oil contained in the discharge gas. The separated lubricating oil is also returned to each compressor via an oil return circuit.

  The problem is whether or not the lubricating oil can be returned to each compressor evenly without excess or deficiency. In order to avoid unbalance of the oil amount, it is conceivable to provide an electromagnetic switching valve in the oil return circuit, but this affects the cost. If a capillary tube is attached to the oil return circuit for the purpose of detecting the oil level, it will not be possible to cope with changes in the operating capacity or the number of operating units of the compressor, resulting in a difference in the amount of oil returned.

  For example, as a branch pipe for distributing return lubricant oil connected to three compressors, an example using a branch section capable of three distributions instead of a T-shaped pipe is disclosed (for example, Japanese special No. 2006-112668).

  Specifically, the branch portion includes a strainer portion provided with a lubricant inlet, a connecting pipe portion having one end connected to the outlet of the strainer portion, and a distributor connected to the other end of the connecting pipe portion. Consists of A plurality of outflow passages are provided at the end of the distributor, and each of the outlets communicates with the outlet.

  Usually, the distributor used for refrigerant distribution is provided at a certain distance from a vibration source such as a compressor in order to avoid pipe fatigue failure. However, the secondary side pipe in the oil return distributor is connected to a refrigerant suction pipe that communicates the accumulator and the suction part of the compressor.

  Therefore, the distributor is provided at a position very close to the compressor, and vibration accompanying the drive of the compressor propagates from the secondary side pipe to the distributor, and is liable to cause fatigue of the pipe. In addition, the flow divider disclosed in the above-mentioned document is attached so that the lubricating oil flows from the bottom to the top with the inlet facing the lower part and the outlet facing the upper part in a substantially vertical posture.

  If the branching portion is installed obliquely, the lubricating oil in the piping is biased, and when the branching portion is split, it is diverted while being biased. For this reason, it is described that the branching portion is in a vertical posture. However, on the other hand, the vibration propagating from the compressor is easily expanded, and the pipe fatigue breakage further proceeds.

  The present invention has been made on the basis of the above circumstances, and the object thereof is to provide a plurality of compressors, and easily and reliably fix a distributor provided to return oil evenly to each compressor, An object of the present invention is to provide an air conditioner that can reduce manufacturing variations and avoid concentration of piping stress due to driving of a compressor to prevent damage to piping fatigue.

In order to satisfy the above object, the present invention provides an outdoor unit having a plurality of compressors connected in parallel and an air conditioner that forms a refrigeration cycle with a plurality of indoor units. An oil equalizing pipe that takes out the accumulated lubricating oil, a distributor that introduces the lubricating oil from these oil equalizing pipes, and distributes it to a plurality of flow paths. An oil return pipe for returning the lubricating oil to the machine, and the distributor is attached to the refrigerant suction pipe in a horizontal posture through a pipe fixture in a horizontal portion of the refrigerant suction pipe connected to the plurality of compressors. Fixed.

FIG. 1 is a configuration diagram of a refrigeration cycle of an air conditioner according to an embodiment of the present invention. FIG. 2 is a perspective view showing an oil return structure to the compressor according to the embodiment. FIG. 3 is a side view showing the structure of the distributor according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a refrigeration cycle of an air conditioner.

  This air conditioner includes one outdoor unit 1 and a plurality (four in this case) of indoor units 2A to 2D.

  The outdoor unit 1 includes a first compressor 3a, a second compressor 3b, and a third compressor 3c, which are a plurality of compressors. The discharge refrigerant pipes 4 a to 4 c connected to the compressors 3 a to 3 c are provided with check valves 5 a to 5 c, and the discharge refrigerant pipes are gathered into one refrigerant pipe 6. In other words, the first to third compressors 3 a to 3 c are connected to the refrigerant pipe 6 in parallel.

  The refrigerant pipe 6 includes an oil separator 7 having a function of separating lubricating oil contained in the gas refrigerant, a first port Qa and a second port Qb of the four-way valve 8, and two outdoor units connected in parallel. The heat exchangers 9a and 9b, the two outdoor expansion valves 10a and 10b connected in parallel, the liquid tank 11, and the first packed valve 12 which is a connection part of the liquid pipe 20 of the outdoor unit 1 are connected. The refrigerant pipe 13 connected to the third port Qc of the four-way valve 8 is connected to a second packed valve 14 that is a connection part of the gas pipe 21 of the outdoor unit 1. The refrigerant pipe connected to the fourth port Qd of the four-way valve 8 is connected to the accumulator 15.

  The refrigerant pipe 16 bent in a U-shape inside the accumulator 15 is branched into three in front of the accumulators 17a to 17c provided in the suction portions of the first to third compressors 3a to 3c, and is compressed. Connected to machines 3a-3c.

In particular, the refrigerant pipe 16 that is bent in a U-shape in the accumulator 15 and extends along the first to third compressors 3a to 3c is called a main refrigerant suction pipe . (However, the “refrigerant suction pipe” is referred to as a “suction refrigerant pipe” in comparison with the “discharge refrigerant pipes 4a to 4c” described above. The same applies hereinafter.) The first compressor is branched from the main suction refrigerant pipe 16. The refrigerant pipe 18a connected to the 3a accumulator 17a is referred to as a first suction refrigerant pipe.

Similarly, the refrigerant pipe 18b branched from the main suction refrigerant pipe 16 and connected to the accumulator 17b of the second compressor 3b is referred to as a second suction refrigerant pipe, and is branched from the main suction refrigerant pipe 16 to be third compressed. The refrigerant pipe 18c connected to the accumulator 17c of the machine 3c is referred to as a third suction refrigerant pipe .

  As will be described later, the refrigerant derived from the accumulator 15 is sucked from the main suction refrigerant pipe 16 into the first to third compressors 3a to 3c via the first to third suction refrigerant pipes 18a to 18c, respectively. Be turned. Accordingly, the first compressor 3a is located on the most upstream side, and hereinafter, located on the downstream side in the order of the second compressor 3b and the third compressor 3c.

The first packed valve 12 is connected to a liquid pipe 20 extending toward the indoor units 2A to 2D. Similarly, a gas pipe 21 extending toward the indoor units 2A to 2D is connected to the second packed valve 14.
The liquid pipe 20 is branched into a plurality of pipes at the terminal portion and connected to the indoor heat exchangers 23a to 23d provided in the indoor units 2A to 2D via expansion valves 24a to 24d, respectively. The gas pipe 21 is also branched into a plurality of terminals at the terminal portion and connected to the indoor heat exchangers 23a to 23d in the indoor units 2A to 2D.

Thus, the refrigeration cycle circuit of the air conditioner is configured.
An outdoor fan 25 is arranged opposite to the outdoor heat exchangers 9a and 9b provided in the outdoor unit 1, and is electrically connected to a remote controller (not shown) together with the first to third compressors 3a to 3c and the like. The operation is controlled by the outdoor controller.

The outdoor unit 1 is provided with an inverter, rectifies the voltage of the commercial downstream power supply, converts the rectified voltage into a downstream voltage having a frequency according to a command from the outdoor control unit, and outputs the converted voltage. The first to third compressors 3a to 3c are variable capacity type and are driven by the output of the inverter, respectively.
Indoor fans 26a to 26d are arranged facing the indoor heat exchangers 23a to 23d provided in the indoor units 2A to 2D. The indoor fans 26a to 26d are driven and controlled by a driving operation on the remote controller.

Further, the outdoor unit 1 is provided with an oil equalization circuit, which will be described in detail below.
One end of the first oil equalizing pipe 30 a is connected to a predetermined height position on the side surface of the case of the first compressor 3 a, and the other end of the oil equalizing pipe 30 a is connected to the oil sump tube 31. The first oil equalizing pipe 30a is provided with a check valve 32a and a capillary tube 33a, and a first temperature sensor 34 is provided on the downstream side of the capillary tube 33a.

  One end of the second oil leveling pipe 30 b is connected to a predetermined height position on the case side surface of the second compressor 3 b, and the other end of the oil leveling pipe 30 b is connected to the oil sump pipe body 31. The second oil equalizing pipe 30b is provided with a check valve 32b and a capillary tube 33b, and a second temperature sensor 35 is provided on the downstream side of the capillary tube 33b.

  One end of the third oil equalizing pipe 30c is connected to a predetermined height position on the side surface of the case of the third compressor 3c, and the other end of the oil equalizing pipe 30c is connected to the oil reservoir pipe body 31. The third oil equalizing pipe 30c is provided with a check valve 32c and a capillary tube 33c, and a third temperature sensor 36 is provided on the downstream side of the capillary tube 33c.

A bypass pipe 38 that branches from the high-pressure refrigerant pipe 6 is connected to one end of the oil sump pipe 31, and a capillary tube and a fourth temperature sensor 39 are provided in the bypass pipe 38. An oil equalizing guide tube 40 and a balance tube 41 are connected to the other end of the oil sump tube 31.
The oil equalizing guide pipe 40 is connected to an inlet of a distributor 43 described later via a first electromagnetic opening / closing valve 42. A fifth temperature sensor 44 is provided in the oil equalizing guide pipe 40 between the oil sump pipe 31 and the first electromagnetic opening / closing valve 42.

  The balance pipe 41 is provided with a second electromagnetic opening / closing valve 46 and a check valve 47 and connected to a balance pipe packed valve 48 provided on the end face of the outdoor unit 1. The balanced pipe packed valve 48 is provided to balance the amount of oil of the compressor and lubricating oil provided in each outdoor unit when a plurality of outdoor units are connected in parallel.

  One end of an auxiliary bypass pipe 49 is connected between the check valve 47 and the balanced pipe packed valve 48 in the balance pipe 41. The other end of the auxiliary bypass pipe 49 is connected to the main suction refrigerant pipe 16 between the accumulator 15 and the first suction refrigerant pipe 18a, and a check valve 50a and a fourth electromagnetic switching valve are provided in the middle of the auxiliary bypass pipe 49. A parallel circuit with 50b is connected.

On the other hand, a first oil outlet pipe 51 is connected to the bottom of the oil separator 7, and a second oil outlet pipe 52 is connected to the side of the oil separator 7.
The first oil outlet pipe 51 is provided with a capillary tube and a third electromagnetic opening / closing valve 53, and is connected between the first electromagnetic opening / closing valve 42 and the distributor 43 in the oil equalizing guide pipe 40. The second oil outlet pipe 52 is provided only with a capillary tube, and is connected between the oil reservoir pipe body 31 and the first electromagnetic opening / closing valve 42 in the oil equalizing guide pipe 40.

  The distributor 43 is mounted in a horizontal posture as will be described later, and one inflow port is opened on one end surface, and three outflow ports are provided on the other end surface. Inside the distributor 43, the flow path connected to the inflow port is branched into three, and each flow path communicates with the outflow port.

As shown in FIG. 3, in the side view of the distributor 43, the first outlet Rf is located on the upper left side, the second outlet Rg is located in the lower center, and the third outlet Rh is located on the upper right side. To position. Note that the first outlet Rf and the third outlet Rh are located at substantially the same height.

  A first oil return pipe 55 is connected to the first outlet Rf, and the oil return pipe 55 is connected to a first suction refrigerant pipe 18 a branched from the main suction refrigerant pipe 16. A second oil return pipe 56 is connected to the second outlet Rg, and this oil return pipe 56 is connected to a second suction refrigerant pipe 18 b branched from the main suction refrigerant pipe 16.

A third oil return pipe 57 is connected to the third outlet Rh, and this oil return pipe 57 is connected to a third suction refrigerant pipe 18 c branched from the main suction refrigerant pipe 16. Of the three compressors 3a to 3c provided, only the second oil return pipe 56 connected to the second compressor 3b disposed in the middle has an oil recirculation shutoff valve 58 that is an electromagnetic on-off valve. Is provided.
The oil leveling circuit is configured as described above.

  FIG. 2 is a perspective view showing the actual piping structure around the first to third compressors 3a to 3c.

  The first compressor 3a is disposed on the right side of the figure, the second compressor 3b is disposed in the middle, and the third compressor 3c is disposed on the left side. Each of the compressors 3a to 3c is a vertical type, and discharge refrigerant pipes 4a to 4c are projected from the upper end portion, and accumulators 17a to 17c are provided along the respective side portions.

  The pipe extending from the upper part of the first compressor 3a along the installation surface is a main suction refrigerant pipe 16 connected to an accumulator 15 (not shown here), and is provided up to the vicinity of the third compressor 3c. It is done. A T-shaped tube 60 is provided in the main suction refrigerant pipe 16 in the vicinity of the first compressor 3a, and the first suction refrigerant pipe 18a is connected thereto.

  The first suction refrigerant pipe 18a is once formed to rise along the accumulator 17a connected to the first compressor 3a, and then bent into an inverted U shape. Then, after extending to the arrangement surface, it is bent into a U-shape and is bent again into an inverted U-shape above the accumulator 17a, and then connected to the upper end of the accumulator 17a.

  The main suction refrigerant pipe 16 in the vicinity of the second compressor 3b is also provided with a T-shaped pipe 61, to which the second suction refrigerant pipe 18b is connected. The second suction refrigerant pipe 18b is also bent in the same manner as the first suction refrigerant pipe 18a described above, and is connected to the upper end portion of the accumulator 17b provided along the second compressor 3b.

  A third suction refrigerant pipe 19c is directly connected to the terminal portion of the main suction refrigerant pipe 16. The third suction refrigerant pipe 18c is also bent in the same manner as the first and second suction refrigerant pipes 18a and 18b. And it connects to the upper end part of the accumulator 17c provided along the 3rd compressor 3c.

  On the other hand, the distributor 43 is connected to a part of the horizontal posture of the main suction refrigerant pipe 16, which is a portion provided along the installation surface of the compressors 3 a to 3 c in the main suction refrigerant pipe 16, via a pipe fixture 62. Mounted. That is, the distributor 43 takes a horizontal posture from where it is attached along the horizontal portion of the main suction refrigerant pipe 16.

  An oil equalizing guide tube 40 extending from an oil sump tube 31 (not shown here) is connected to the left side of the distributor 43 in the drawing. From the right side, a total of three oil return pipes 55, 56, 57 are extended, two at the top and one at the bottom.

  On the upper side, one pipe is once formed as a first oil return pipe 55 along the horizontal portion of the main suction refrigerant pipe 16 and rising along the first suction refrigerant pipe 18a. Connected. The lower pipe is once formed as a second oil return pipe 56 that rises along the horizontal portion of the main suction refrigerant pipe 16 and along the second suction refrigerant pipe 18b.

  The second oil return pipe 56 is bent horizontally at substantially the same height as the inverted U-shaped portion of the second suction refrigerant pipe 18b, and the oil reflux shutoff valve 58 is connected to the second oil return pipe 56. The In the figure, only the valve body of the oil recirculation cutoff valve 58 is shown, and the electromagnetic coil portion is omitted.

  The second oil return pipe 56 exiting from the oil recirculation shutoff valve 58 is fixed to the second suction refrigerant pipe 18b via a pipe fixture 62, and is connected to the second suction refrigerant pipe 18b at a lower portion. The other pipe on the upper side of the distributor 43 is bent as a third oil return pipe 57 so as to be parallel to the oil equalizing guide pipe 40 and connected to the rising portion of the third suction refrigerant pipe 18c.

Next, the flow of the refrigerant in the refrigeration cycle circuit will be described.
When the first to third compressors 3a to 3c are driven, high-temperature and high-pressure gas refrigerants discharged from the respective compressors 3a to 3c are discharged through the discharge refrigerant tubes 4a to 4c connected to the respective compressors. Guided to tube 6. Then, the gas refrigerant is supplied to the oil separator 7 through the refrigerant pipe 6 where the lubricating oil contained in the gas refrigerant is separated.

  The gas refrigerant exiting the oil separator 7 is guided to the four-way valve 8, and is guided to the outdoor heat exchangers 9a and 9b during the cooling operation to exchange heat with the outdoor air. The gas refrigerant is condensed and liquefied, and is converted into liquid refrigerant and led to the indoor units 2A to 2D through the outdoor expansion valves (10a, 10b), the liquid tank 11, the first packed valve 12, and the liquid pipe 20 in this order.

  In the indoor units 2A to 2D, they are adiabatically expanded by the expansion valves 24a to 24d and flow to the indoor heat exchangers 23a to 23d, and are evaporated by exchanging heat with the indoor air in the indoor heat exchangers 23a to 23d. At this time, latent heat of evaporation is taken from the room air, and the room air is changed to cold air. The cool air is blown into the room by the action of the indoor fans 26a to 26d, and the air is cooled.

  The evaporative refrigerant derived from the indoor heat exchangers 23a to 23d exits the indoor units 2A to 2D and is guided to the outdoor unit 1 through the gas pipe 21 and the second packed valve 14. In the outdoor unit 1, after being led from the four-way valve 8 to the accumulator 15 and separated into gas and liquid, the main suction refrigerant pipe 16 is divided into first to third suction refrigerant pipes 18 a to 18 c.

  The evaporative refrigerant is sucked into the first to third compressors 3a to 3c from the first to third suction refrigerant tubes 18a to 18c via the accumulators 17a to 17c. Each compressor 3a-3c is compressed, becomes a high-temperature and high-pressure gas refrigerant, and circulates in the above-mentioned system.

  During the heating operation, the refrigerant is guided in the opposite direction to that during the cooling operation by switching the four-way valve 8. The refrigerant is condensed in the indoor heat exchangers 23a to 23d of the indoor units 2A to 2D, and the condensation heat is released to the indoor air. The indoor air changes into warm air and is blown into the room, thereby heating the room.

Next, the flow of lubricating oil in the oil equalizing circuit will be described.
Lubricating oil is stored in each of the sealed cases of the first to third compressors 3a to 3c. The oil level is the first to third oil leveling pipes 30a connected to the respective side portions. It may be higher than the connection position of ˜30c.

  The first to third oil leveling pipes 30a to 30c are used as excess oil in the first to third compressors 3a to 3c in excess of the connection positions of the first to third oil leveling pipes 30a to 30c. To be derived. The lubricating oil is guided to the oil sump tube 31 via the capillary tubes 33a to 33c.

  A small amount of high-pressure gas refrigerant that has been diverted from the high-pressure side refrigerant pipe 6 to the bypass pipe 38 flows into the oil sump pipe 31. The lubricating oil that has flowed into the oil sump tube 31 is guided to the oil equalization guide tube 40 by the pressure applied from the bypass tube 38 via the capillary tube.

  The first electromagnetic open / close valve 42 provided in the oil equalizing guide pipe 40 is normally controlled to be opened, and the lubricating oil flowing from the oil reservoir pipe 31 is guided to the distributor 43. In the distributor 43, it guide | induces to the flow path isolate | separated into 3 directions from the inflow port, and flows out from each outflow port.

  That is, in the distributor 43, the lubricating oil is equally divided into each of the first to third oil return pipes 55 to 57. And it guide | induces from the 1st-3rd oil return pipes 55-57 to the 1st-3rd suction refrigerant pipes 18a-18c. In particular, the lubricating oil guided to the second oil return pipe 56 flows through the oil recirculation cutoff valve 58 that is controlled to be opened.

  The lubricating oil flowing into the first to third suction refrigerant pipes 18a to 18c circulates in the refrigeration cycle and is sucked into the first to third compressors 3a to 3c together with the evaporated refrigerant led out from the accumulator 15. .

  For example, the oil level height of the first compressor 3a is higher than the connection position of the first oil leveling pipe 30a, and the oil level height of the second compressor 3b is higher than the connection position of the second oil leveling pipe 30b. When the oil level is low and the oil level height of the third compressor 3c is the connection position of the third oil equalizing pipe 30c. That is, in each compressor 3a-3c, a bias | deviation may arise in a mutual oil level.

  At this time, lubricating oil flows into the first oil leveling pipe 30a connected to the first compressor 3a, and high-pressure gas refrigerant flows into the second oil leveling pipe 30b connected to the second compressor 3b. The lubricating oil and the gas refrigerant that have flowed into these oil leveling pipes 30a and 30b gather in the oil sump pipe 31, and when they flow out of this, they are mixed and guided to the oil leveling guide pipe 40.

  And it flows into the distributor 43 from the oil equalization guide pipe 40, and is equally divided into three flow paths. It is led from the distributor 43 to the first to third compressors 3a to 3c via the first to third oil return pipes 55 to 57 and the first to third suction refrigerant pipes 18a to 18c.

  In this way, the lubricating oil moves from the compressor having the larger amount of lubricating oil, such as the first compressor 3a, to the compressor having the smaller amount of oil, such as the second compressor 3b. Therefore, the oil level in the first to third compressors 3a to 3c is quickly balanced.

  On the other hand, in the gas refrigerant discharged from the first to third compressors 3a to 3c, a part of the lubricating oil stored in each is mixed. These mixed fluids are discharged to the discharge refrigerant pipes 4 a to 4 c and guided from the high-pressure side refrigerant pipe 6 to the oil separator 7. The oil separator 7 separates the lubricating oil from the gas refrigerant.

  The first oil outlet pipe 51 connected to the bottom of the oil separator 7 is provided with a third electromagnetic opening / closing valve 53, which is normally in a closed state. Therefore, the lubricating oil separated here is temporarily stored in the oil separator 7, and only the gas refrigerant is guided to the four-way valve 8.

  The lubricating oil stored in the oil separator 7 increases, and finally rises to the connection position of the second oil outlet pipe 52 connected to the side portion. Lubricating oil in excess of the connection position of the oil lead-out pipe 52 flows into the oil equalizing guide pipe 40 from the oil lead-out pipe 52 and is described above via the distributor 43 and the first to third oil return pipes 55 to 57. In this manner, the first to third compressors 3a to 3c are returned.

  For some reason, the oil level in the sealed cases of all the compressors 3a to 3c may be lowered at the same time. At this time, an opening signal is output to the third electromagnetic opening / closing valve 53 provided in the first oil outlet pipe 51 at the bottom of the oil separator 7 and the first electromagnetic opening / closing valve 42 of the oil equalizing guide pipe 40 is closed. A signal is issued.

  All the lubricating oil stored in the oil separator 7 is guided from the first oil outlet pipe 51 to the oil equalizing guide pipe 40, and is distributed to the distributor 43, the first to third oil return pipes 55 to 57, and the main suction. The refrigerant is sucked into the first to third compressors 3a to 3c through the refrigerant pipe 16, the first to third suction refrigerant pipes 18a to 18c and the like, and is equally distributed to the compressors 3a to 3c.

In the embodiment of the present invention, the oil return distributor 43 is attached to the horizontal portion of the main suction refrigerant pipe 16 connected to each of the compressors 3a to 3c via the pipe fixing device 62 to be in a horizontal posture.
That is, in the distributor 43, the secondary pipe on the distribution side is connected to the first to third suction refrigerant pipes 18a to 18c, and is provided at a position very close to the first to third compressors 3a to 3c. It will be.

Therefore, the vibration accompanying the driving of the first to third compressors 3 a to 3 c is easily propagated to the distributor 43 via the first to third suction refrigerant tubes 18 a to 18 c and the main suction refrigerant tube 16.
However, as described above, the distributor 43 is placed in a horizontal posture and is fixedly attached to the main suction refrigerant pipe 16, so that the same vibration system can be obtained and pipe fatigue failure can be prevented.

  Further, when the distributor is in a vertical posture, it takes time to correct the inclination of the distributor in the manufacturing process, and the dimensional management with the connecting pipe is troublesome. Since it is attached and fixed, these management efforts are not required, and it is possible to reduce product variations and manufacturing costs.

In the outdoor unit 1 including a plurality of compressors, a compressor that is operating and a compressor that is not operating may be mixed. In such an operating situation, the ratio of the lubricating oil returning through the oil equalizing circuit may not be uniform.
For example, the first compressor 3a and the second compressor 3b are operating, and the third compressor 3c is not operating. At this time, the amount of lubricating oil returned from the distributor 43 to the first compressor 3a via the first oil return pipe 55 and returned to the second compressor 3b via the second oil return pipe 56. The amount of lubricating oil is the same.

  The distributor 43 includes three flow paths with respect to one inflow port, and is configured so that the lubricating oil flows evenly therethrough. As a matter of course, the same amount of lubricating oil is guided from the distributor 43 to the third oil return pipe 57, and goes to the third compressor 3c.

  However, since the third compressor 3c has stopped operating as described above, the lubricating oil flowing from the third oil return pipe 57 to the third suction refrigerant pipe 18c is sucked into the third compressor 3c. Absent. This lubricating oil loses its destination and flows from the third suction refrigerant pipe 18 c to the main suction refrigerant pipe 16.

  Then, most of the lubricating oil flowing through the third oil return pipe 57 is led to the second suction refrigerant pipe 18b by the suction force of the second compressor 3b on the upstream side. Here, it merges with the lubricating oil guided through the second oil return pipe 56 and is sucked into the second compressor 3b.

  Eventually, the ratio of the amount of lubricating oil recirculated to the first compressor 3a and the second compressor 3b is 1: 2, and the second compressor 3b accumulates too much lubricating oil, but the first compression The machine 3a is in an oil shortage state.

  In the present invention, the second oil return pipe 3b is provided with the oil recirculation shutoff valve 58, and in the above situation, the oil recirculation shutoff valve 58 is controlled to be closed. Therefore, the lubricating oil is guided from the distributor 43 to the first oil return pipe 55 and the third oil return pipe 57, but the lubricating oil does not flow to the second oil return pipe 56.

Lubricating oil recirculates from the first oil return pipe 55 to the first compressor 3a, and lubricating oil recirculates from the third oil return pipe 57 to the second compressor 3b. There is no change in that the lubricating oil does not recirculate to the third compressor 3c that has stopped operating.
That is, the oil return shutoff valve 58 is provided in the second oil return pipe 56 communicating with the compressor 3b in the middle of the three units, and the closing control is performed under the above situation. As shown in FIG. 3, since the first outlet Rf and the third outlet Rh of the distributor 43 are located at substantially the same height, the first oil return pipe 55 and the third oil A substantially equal amount of lubricating oil flows into the return pipe 57. That is, the same amount of lubricating oil is recirculated to the first compressor 3a and the second compressor 3b, and there is no occurrence of excess or deficiency of the lubricating oil.

Further, even when a temporary oil shortage occurs in any of the first to third compressors 3a to 3c, the oil recirculation shutoff valve 58 is controlled to be opened and closed to be retained in the operating compressor. The amount of lubricating oil can be adjusted.
For example, the second compressor 3b may fall short of oil while the oil recirculation shutoff valve 58 is closed. Oil shortage is based on comparison of detected temperatures between the fourth temperature sensor 39 provided in the bypass pipe 38 and the first to third temperature sensors 35 to 37 provided in the first to third oil leveling pipes 30a to 30c. I can know.

  When the lubricating oil flows through the first to third oil equalizing pipes 30 a to 30 c, these detected temperatures are higher than the detected temperatures of the bypass pipe 38. Conversely, when the refrigerant flows through the first to third oil leveling pipes 30a to 30c, the detected temperature of the bypass pipe 38 becomes higher than these detected temperatures, and the first to third compressors 3a to 3c are oiled. You can see that it is in shortage.

  As described above, when it is detected that the second compressor 3b falls short of oil while the oil recirculation shutoff valve 58 is closed, the oil recirculation shutoff valve 58 is controlled to be opened. As shown in FIG. 3, since the second outlet Rg of the distributor 43 is located on the lowermost side among the three outlets, the oil return pipe 56 connected to the second outlet Rg. More lubricating oil flows into the oil return pipes 55 and 57 than lubricating oil flows into. Accordingly, the amount of lubricating oil returning from the second oil return pipe 56 to the second compressor 3b increases, and the amount of lubricating oil held in the first compressor 3a and the second compressor 3b balances. .

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments.

  According to the present invention, it is possible to obtain an air conditioner that can easily and reliably fix the distributor, reduce manufacturing variations, and prevent the pipe fatigue failure caused by driving of the compressor.

Claims (2)

In an air conditioner that constitutes a refrigeration cycle with an outdoor unit including a plurality of compressors connected in parallel and a plurality of indoor units,
An oil equalizing pipe for taking out the lubricating oil accumulated in the compressor above the specified amount;
Distributing the lubricating oil from these oil leveling pipes and distributing it to multiple flow paths,
An oil return pipe that communicates the distribution flow path of this distributor with the refrigerant suction pipe of each compressor and returns the lubricating oil to each compressor,
The air conditioner is characterized in that the distributor is mounted and fixed to the refrigerant suction pipe in a horizontal posture via a pipe fixing tool on a horizontal portion of the refrigerant suction pipe connected to the plurality of compressors. Three compressors are provided in parallel,
2. The air conditioner according to claim 1, wherein an oil recirculation shutoff valve is provided on the oil return pipe in which lubricating oil is most likely to flow in such a manner that it can be opened and closed.

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