JP2008249230A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner, simply adjusting the recovery quantity in oil recovery in the air conditioner in which a plurality of outdoor units are parallel-connected. <P>SOLUTION: In this air conditioner 1, a plurality of outdoor units 3a, 3b respectively having oil separators 32a, 32b are connected in parallel to indoor-to-outdoor connecting pipes 11, 12 connecting the indoor units 2a, 2b and the outdoor units 3a, 3b, compressor inlet lines of the respective outdoor units 3a, 3b are connected by an outdoor-to-outdoor connecting pipe 13, and the oil separators 32a, 32b of the respective outdoor units 3a, 3b and the outdoor-to-outdoor connecting pipe 13 are connected to each other. Oil return pipes 323a, 323b from the bottoms of the respective oil separators 32a, 32b are communicated to own compressors 31a, 31b, oil recovery pipes 19a, 19b from predetermined positions of the respective oil separators 32a, 32b are connected to the outdoor-to-outdoor connecting pipe 13 through the oil recovery opening and closing valve SV51, and the oil recovery switching valve SV51 of an oil surplus side outdoor unit 3b is opened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air conditioner in which a plurality of outdoor units are connected in parallel to an internal / external communication pipe that connects the indoor unit and the outdoor unit.

  In general, an air conditioner in which a plurality of outdoor units are connected in parallel to an internal / external communication pipe that connects the indoor unit and the outdoor unit is known.

  In such an air conditioner, since the compressor oil used in the compressor is dissolved in the refrigerant, it passes through the oil separator during the air conditioning operation and flows out from the outdoor unit to the external indoor unit and the external / internal communication pipe. . In this case, if there is only one outdoor unit, the oil that flows out as the refrigerant circulates returns to the outdoor unit.However, in the configuration in which multiple outdoor units are connected in parallel to the internal and external communication pipes of the same system, the installation height difference of each outdoor unit Depending on the installation conditions such as the inclination of the inner and outer communication pipes, an outdoor unit is generated in which oil is difficult to return. Also, when the operating capacities are different, the large operating capacity tends to be short of oil due to the difference in the refrigerant discharge amount.

  Therefore, conventionally, an air conditioner that collects oil from other outdoor units has been proposed on the outdoor unit side where such oil shortage has occurred (see, for example, Patent Document 1).

The air conditioner of Patent Document 1 connects return pipes that return oil separated by an oil separator of each outdoor unit to a compressor by connecting pipes, and connects these return pipes and connecting pipes by valves. The amount of oil returned to each compressor can be adjusted.
Japanese Patent No. 2925715

  However, in the case of the air conditioner of Patent Document 1 described above, if the oil is collected too much, the oil is insufficient in other outdoor units, so that there is a disadvantage that the oil must be collected while considering not to collect excessively. It was.

  The present invention has been made in view of such circumstances, and provides an air conditioner that can easily adjust the amount of oil recovered when an oil is recovered in an air conditioner in which a plurality of outdoor units are connected in parallel. It is an object.

  In order to solve the above problems, an air conditioner according to the present invention includes a parallel connection of a plurality of outdoor units each having an oil separator to an internal / external communication pipe connecting the indoor unit and the outdoor unit, and a compressor suction line of each outdoor unit. In the air conditioner that connects with the external and external communication pipes and connects the oil separator of each outdoor unit and the external and external communication pipes, the oil return pipe from the bottom of each oil separator is connected to the compressor suction side of its own machine, An oil recovery pipe from a predetermined position of the oil separator is connected to the external / external communication pipe via an oil recovery on-off valve, and the oil recovery on-off valve of the oil surplus outdoor unit is opened.

  In the above air conditioner, the drive source of the compressor of each outdoor unit is an engine, and a waste heat recovery device that evaporates the refrigerant with engine waste heat is provided in the compressor suction line, and the outdoor communication pipe is connected to each outdoor unit. It is configured to be connected to the upstream side of the waste heat recovery unit.

  Further, the air conditioner is configured to open the oil recovery on-off valve of the stop transition machine when there is a stop transition machine and a driving machine that have received the operation stop signal.

  Further, in the above air conditioner, when there are two operating units, the oil recovery on-off valve of one outdoor unit is closed after being opened for a predetermined time or until the oil separator oil level is detected to be below a predetermined position, Next, the oil recovery on-off valve of the other outdoor unit is configured to open for a predetermined time or until the oil separator oil level is detected to be below a predetermined position.

  Furthermore, in the above air conditioner, when there are two operating units, the oil recovery on-off valve of one outdoor unit is closed after being opened until the oil separator oil level is detected to be below a predetermined position, The oil recovery on / off valve of the other outdoor unit is opened after the oil separator oil level is detected to be below a predetermined position and then closed, and two detection times from the opening of the oil recovery on / off valve to the oil level below the predetermined position are detected. The oil recovery on-off valve of the outdoor unit on the opposite side to the time of detection is opened for half of the longer detection time.

  Further, in the air conditioner, the compressor of the operating unit is operated at a predetermined number of revolutions or more for a predetermined time before opening the oil recovery on-off valve of the outdoor unit.

  As described above, according to the air conditioner of the present invention, the oil recovery amount can be easily adjusted.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a refrigerant circuit diagram during oil recovery operation of the air conditioner 1 according to the present invention, FIG. 2 shows an oil amount adjustment method by oil recovery operation of the air conditioner 1, and FIG. An example of an operation schedule during single-machine operation is shown. 4 to 7 show the operating state of the air conditioner 1 during normal cooling or heating.

  1, FIG. 4 to FIG. 7, the air conditioner 1 connects indoor units 2a, 2b and outdoor units 3a, 3b to a liquid side inside / outside connecting pipe 11 and a gas side inside / outside connecting pipe 12. The outdoor units 3a and 3b are configured to be connected in parallel to the liquid side inside / outside connecting pipe 11 and the gas side inside / outside connecting pipe 12. The outdoor units 3 a and 3 b are connected to each other by an external / external communication pipe 13.

  The outdoor unit 3a includes a compressor 31a, an oil separator 32a, a four-way valve 33a, an outdoor heat exchanger 34a, a bridge circuit 35a, a liquid receiver 36a, a supercooler 37a, and shut-off valves BV1 and BV2 (both are manually openable and normally open). ), A waste heat recovery unit 38a, and an outdoor fan 39a. Since the outdoor unit 3b is the same as the outdoor unit 3a, description thereof is omitted.

  The indoor unit 2a includes an electronic expansion valve 21a, an indoor heat exchanger 22a, and an indoor fan 23a. Since the indoor unit 2b is the same as the indoor unit 2a, description thereof is omitted.

  In the refrigerant path of the air conditioner 1, EV1 to EV3 are electronic expansion valves, CV1 to CV5, CV51, CV53, CV54, CV56, and CV57 are check valves, SV1 is an oil return on-off valve, and SV51 is an oil recovery on-off valve. SV52 to SV57 are on-off valves, and TS1 to TS5 and TD1 to TD2 are temperature sensors.

  In the air conditioner 1 of the present invention, the oil separator 32a is connected to an inlet pipe 321a into which refrigerant from the compressor 31a enters and an outlet pipe 322a through which the refrigerant is discharged. The refrigerant that has entered the oil separator 32a from the inlet pipe 321a is separated into refrigerant and oil, and only the refrigerant is discharged from the outlet pipe 322a.

  An oil return pipe 323a connected to the refrigerant suction side of the compressor 31a is connected to the bottom of the oil separator 32a. The oil return pipe 323a returns the oil separated by the oil separator 32a from the refrigerant suction side of the compressor 31a back to the compressor 31a, thereby lubricating the drive unit of the compressor 31a. The oil return pipe 323a is provided with a capillary tube CT, and the oil flow rate of the oil return pipe 323a is adjusted.

  Further, the oil separator 32a is configured such that an oil recovery pipe 19a is connected between the oil separator 32a at a predetermined oil level height and the outer / outer connecting pipe 13. The oil recovery pipe 19a is provided with a check valve CV51 that stops the flow of oil from the outer / outer communication pipe 13 side to the oil separator 32a side. Further, an oil recovery on-off valve SV51 is provided at a position of the oil recovery pipe 19a adjacent to the oil separator 32a from the check valve CV51.

  Between the oil separator 32a of the oil recovery pipe 19a and the oil recovery on-off valve SV51, there is an oil return branch pipe 324a that branches from the oil recovery pipe 19a and communicates with the refrigerant suction side of the compressor 31a. Is provided. Similar to the oil return pipe 323a, the oil return branch pipe 324a is provided with a capillary tube CT, and the oil flow rate of the oil return branch pipe 324a is adjusted.

  Further, on the further upstream side of the oil return branch pipe 324a connected to the refrigerant suction side of the compressor 31a, waste heat recovery for evaporating the refrigerant using waste heat of an engine (not shown) that drives the compressor 31a. A container 38a is provided. The external / external communication pipe 13 is connected to the upstream side of the waste heat recovery unit 38a via an open / close valve SV52. A capillary tube CT is provided between the on-off valve SV52 and the waste heat recovery unit 38a. The oil recovery pipe 19a is connected to the external / external communication pipe 13 at a position facing the opposite side of the capillary tube CT with the open / close valve SV52 interposed therebetween. The outdoor unit 3b is configured similarly.

  First, based on FIG. 4 thru | or FIG. 7, the flow of the refrigerant | coolant of a refrigerant circuit at the time of the normal operation of the air conditioner 1 which concerns on this invention is demonstrated.

  FIG. 4 shows a normal cooling operation by the two outdoor units 3a and 3b. At this time, the refrigerant of the outdoor units 3a, 3b is discharged from the compressors 31a, 31b and separated from the oil by the oil separators 32a, 32b, and then to the outdoor heat exchangers 34a, 34b via the four-way valves 33a, 33b. And flows in. Thereafter, the refrigerant that has passed through the bridge circuits 35a and 35b from the outdoor heat exchangers 34a and 34b is stored as liquid refrigerant in the liquid receivers 36a and 36b. This liquid refrigerant is supplied again from the closing valve BV1 to the liquid side inside / outside connecting pipe 11 via the bridge circuits 35a and 35b.

  The refrigerant from the liquid side inside / outside connecting pipe 11 evaporates and evaporates in the indoor heat exchangers 22a, 22b through the electronic expansion valves 21a, 21b of the indoor units 2a, 2b, and then from the closing valve BV2 through the gas side inside / outside connecting pipe 12. Suction to the compressors 31a and 31b. At this time, the cooling is controlled by adjusting the opening of the electronic expansion valves 21a and 21b. In addition, when the cooling capacity is insufficient, a part of the refrigerant from the liquid receivers 36a and 36b to the bridge circuits 35a and 35b is adjusted to the opening degree of the electronic expansion valve EV2 and then to the supercoolers 37a and 37b. Led. As a result, the liquid refrigerant in the liquid receivers 36a and 36b is controlled to be supercooled to eliminate the lack of cooling capacity. The refrigerant that has passed through the subcoolers 37a and 37b merges with the gas refrigerant that passes through the normal refrigerant path.

  FIG. 5 shows a normal heating operation by the two outdoor units 3a and 3b. At this time, the refrigerant of the outdoor units 3a and 3b is discharged from the compressors 31a and 31b and separated from the oil by the oil separators 32a and 32b, and then communicated from the shut-off valve BV2 to the gas side inside / outside via the four-way valves 33a and 33b. Supplied to the tube 12.

  The refrigerant from the gas side inside / outside connecting pipe 12 is condensed and liquefied by the indoor heat exchangers 22a, 22b of the indoor units 2a, 2b, and then led to the liquid side inside / outside connecting pipe 11 via the electronic expansion valves 21a, 21b. The liquid refrigerant in the liquid side inside / outside connecting pipe 11 is recovered from the closing valve BV1 of the outdoor units 3a, 3b to the liquid receivers 36a, 36b via the bridge circuits 35a, 35b. The liquid refrigerant is led to the outdoor heat exchangers 34a and 34b after the opening degree is adjusted again by the electronic expansion valve EV1 of the bridge circuits 35a and 35b. After evaporating and evaporating in the outdoor heat exchangers 34a and 34b, the air is sucked again from the four-way valves 33a and 33b to the compressors 31a and 31b. In addition, in the heating operation, in order to compensate for the lack of evaporation capability of the outdoor heat exchangers 34a and 34b, a part of the refrigerant is led from the electronic expansion valve EV2 to the waste heat recovery units 38a and 38b via the subcoolers 37a and 37b. It is burned. In the waste heat recovery units 38a and 38b, the refrigerant evaporated by the waste heat of the engine (not shown), which is the driving source of the compressors 31a and 31b, joins the gas refrigerant passing through the normal refrigerant path.

  FIG. 6 shows the time when one outdoor unit 3a is in the normal cooling operation and the other outdoor unit 3b is stopped. At this time, in the outdoor unit 3a on the operation side, the refrigerant flows in the same manner as in the normal cooling operation described with reference to FIG.

  FIG. 7 shows a state where one outdoor unit 3a is in a heating operation state and the other outdoor unit 3b is in an operation stopped state. At this time, in the outdoor unit 3a in operation, the refrigerant flows as in the normal heating operation described with reference to FIG.

  Next, the flow of oil in the refrigerant circuit when the air conditioner 1 according to the present invention performs the oil recovery operation will be described with reference to FIG.

  FIG. 1 shows a state in which an oil recovery operation from the outdoor unit 3b to the outdoor unit 3a is performed.

  The compressor oil used to lubricate the drive unit in the compressors 3a and 3b is dissolved in the refrigerant, and a part of the compressor oil passes through the oil separator 32a during the air-conditioning operation to be connected to the liquid side inside / outside connecting pipe. 11. It flows out to the gas side inside / outside connecting pipe 12 and the indoor units 2a, 2b. The spilled oil eventually returns to the outdoor units 3a and 3b. However, in this air conditioner 1, the two outdoor units 3a and 3b are arranged in parallel with the liquid side inside / outside connecting pipe 11 and the gas side inside / outside connecting pipe 12 of the same system. Because it is connected, it depends on various conditions such as the difference in installation height of the outdoor units 3a and 3b, the difference in operating capability of the outdoor units 3a and 3b, and the difference in passage resistance between the liquid side internal / external communication pipe 11 and the gas side internal / external communication pipe The outdoor units 3a and 3b are not evenly returned to each other, and are biased toward one of the outdoor units 3a and 3b. For example, when oil is biased in the outdoor unit 3b and the oil in the outdoor unit 3a is insufficient, an oil recovery operation from the outdoor unit 3b to the outdoor unit 3a is required.

  In addition, when one of the two outdoor units 3a and 3b is in operation and the other outdoor unit 3b is stopped, the oil is retained in the stopped outdoor unit 3b. Since it is useless, if only one outdoor unit 3a is operated, it is desirable to stop the outdoor unit 3b after collecting oil from the outdoor unit 3b to the outdoor unit 3a.

  As described above, when the oil recovery operation from the outdoor unit 3b to the outdoor unit 3a is necessary, for example, the change from the normal cooling operation by the two outdoor units 3a and 3b shown in FIG. The automatic on-off valve SV52 is closed, and the oil recovery on-off valve SV51 is opened.

  As a result, the external and external communication pipes 13 that have been balanced by the suction forces of the compressors 31a and 31b are blocked from the suction of the compressor 31b, and the suction force of the compressor 31a becomes dominant. At the same time, the oil separator 32b communicates with the external / external communication pipe 13 through the oil collection pipe 19b by opening the oil collection on-off valve SV51. Accordingly, the oil in the oil separator 32b smoothly flows to the outdoor unit 3a via the external communication pipe 13 via the oil recovery pipe 19b in which the oil recovery on-off valve SV51 is opened. In the outdoor unit 3a, oil flows from the automatic opening / closing valve SV52 into the refrigerant flow path via the capillary tube CT. Therefore, even if liquid refrigerant is mixed in the oil passing through the outdoor communication pipe 13, The capillary tube CT is sufficiently decompressed and expanded to change the state into a mist refrigerant.

  After that, since it passes through the waste heat recovery unit 38a, the waste heat recovery unit 38a supplies the compressor 31a with the refrigerant surely vaporized by the engine waste heat, and the liquid compression in the compressor 31a. Can be prevented.

  In this embodiment, the capillary tube CT and the waste heat recovery unit 38a are passed through, but only the capillary tube CT or only the waste heat recovery unit 38a is passed through. There may be.

  Since oil can be recovered from the outdoor unit 3b in this manner, the shortage of oil in the outdoor unit 3a is resolved.

  Further, at the time of this oil recovery, the oil recovery pipe 19b is branched and connected from an oil return branch pipe 324b provided at a predetermined oil level height of the oil separator 32b. This amount of oil is recovered only in excess of the predetermined oil level. Accordingly, since an amount of oil corresponding to the predetermined oil level height position can be left in the oil separator 32b, there is no fear of excessive recovery, and the oil amount can be easily adjusted. For example, even when oil is recovered from the outdoor unit 3b to the outdoor unit 3a before the outdoor unit 3b is stopped, the oil necessary for resuming operation may remain in the stopped outdoor unit 3b. Therefore, the outdoor unit 3b can be smoothly driven when the operation is resumed.

  In the present embodiment, the case where the two outdoor units 3a and 3b shown in FIG. 4 shift from the normal cooling operation to the oil recovery operation is described. However, the two outdoor units 3a and 3b shown in FIG. The transition from the normal heating operation by 3b to the oil recovery operation can be similarly performed by closing the automatic opening / closing valve SV52 of the outdoor unit 3b and opening the oil recovery opening / closing valve SV51.

  Further, in the present embodiment, the case where the oil of the outdoor unit 3b is recovered to the outdoor unit 3a is described. However, the oil of the outdoor unit 3a can be obtained by reversing the settings of the outdoor unit 3a and the outdoor unit 3b. It goes without saying that can be recovered into the outdoor unit 3b.

  Next, a method for adjusting the oil amount between the oil separators 32a and 32b of the outdoor units 3a and 3b when the oil recovery described above is performed by the air conditioner 1 will be described. As described above, in the air conditioner 1, even when oil is collected, the oil separators 32 a and 32 b contain a quantity of oil up to a predetermined oil level height position where the oil return branch pipes 324 a and 324 b are connected. Can leave.

  Therefore, after the automatic open / close valve SV52 of the outdoor unit 3b is closed and the oil recovery open / close valve SV51 is opened to collect oil from the oil separator 32b of the outdoor unit 3b to the oil separator 32a of the outdoor unit 3a, this time, on the contrary, The automatic open / close valve SV52 of the outdoor unit 3b is opened, the oil recovery open / close valve SV51 is closed, the automatic open / close valve SV52 of the outdoor unit 3a is closed, the oil recovery open / close valve SV51 is opened, and the oil separator 32a of the outdoor unit 3a is opened. By adjusting the amount of oil that recovers oil to the oil separator 32b of the outdoor unit 3b, an amount of oil up to a predetermined oil level height position can be left in at least both the oil separators 32a and 32b.

  For example, in FIG. 2A, an amount of oil equal to or greater than a predetermined oil level height position S remains in one oil separator 32a, and the predetermined oil level height position S or less remains in the other oil separator 32b. It shows the case where only the amount of oil remains. In this case, by collecting oil from one oil separator 32a to the other oil separator 32b, the amount of oil in the oil separator 32b in which only an amount of oil equal to or less than the predetermined oil level height position S remains is increased. be able to. Thereafter, the oil amount in the oil separator 32b increased to the amount of oil equal to or higher than the predetermined oil level height position S by recovering the oil from the oil separator 32b to the oil separator 32a and adjusting the oil amount. However, the amount of oil corresponding to the predetermined oil level height position S can be left in at least both of the oil separators 32a and 32b.

  FIG. 2B shows a case in which only an amount of oil of a predetermined oil level height position S remains in both the oil separators 32a and 32b. In this case, after the oil recovery from one oil separator 32a to the other oil separator 32b, the oil amount is adjusted from the oil separator 32b to the oil separator 32a. The oil amount in the oil separators 32a and 32b does not change, but at least the oil in the predetermined oil level height position S can be left in both the oil separators 32a and 32b.

  FIG. 2 (c) shows that only an amount of oil equal to or less than a predetermined oil level height position S remains in one oil separator 32a, and the oil separator 32b has a value equal to or higher than the predetermined oil level height position S. The amount of oil remaining is shown. In this case, there is no change in the situation even if the oil recovery is performed from one oil separator 32a to the other oil separator 32b, but then the oil recovery from the oil separator 32b to the oil separator 32a is performed conversely. By adjusting the oil amount, the amount of oil in the oil separator 32a in which only an amount of oil equal to or less than the predetermined oil level height position S remains is increased. At this time, the amount of oil in the oil separator 32b in which an amount of oil equal to or greater than the predetermined oil level height position S remains is reduced to the predetermined oil level height position S, but at least both of the oil separators 32a, An amount of oil of a predetermined oil level height position S can be left in 32b.

  As shown in FIGS. 2A to 2C, after oil recovery from one oil separator 32a to the other oil separator 32b, the oil amount is adjusted by continuously recovering oil in the reverse direction. By doing so, an amount of oil of a predetermined oil level height position S can be left in at least both of the oil separators 32a and 32b. Therefore, even if it is not clear which of the outdoor units 3a and 3b has the oil separators 32a and 32b below the predetermined oil level height position S, the outdoor units 3a and 3b can be obtained by performing this oil amount adjustment operation. The amount of oil necessary for the operation of can be secured.

  Further, in the case of this oil amount adjustment method, a quantity of oil of a predetermined oil level height position S is left in both the oil separators 32a and 32b, but more oil is left in one oil separator 32a. be able to.

  Therefore, when one of the two outdoor units 3a and 3b is operated, there is a concern about oil shortage by performing oil recovery so that the amount of oil on the operating unit side is increased. This makes it possible to drive more comfortably and stably. Further, even when the other outdoor unit 3b that has been stopped is restarted, the oil separator 32b retains a predetermined amount of oil in the oil level height position S, so that it can be restarted immediately. it can.

  Normally, when one of the two outdoor units 3a and 3b is continuously operated, the liquid side internal / external communication pipe 11, the gas side internal / external communication pipe 12, the indoors are not collected by the oil separator 32a. The oil flowing out to the machines 2a and 2b increases in proportion to the duration of operation. Accordingly, when only one of the outdoor units 3a is continuously operated, the oil becomes insufficient. Therefore, it is necessary to perform the oil recovery operation at regular intervals in consideration of the oil flowing out. Usually, the oil recovery operation is performed at regular intervals, and at the same time, the rotation is alternately switched from one outdoor unit 3a to the other outdoor unit 3b. In the case of the air conditioner 1 according to the present invention, since a large amount of oil can be left in the one oil separator 32a by adjusting the amount of oil described above, it is possible to lengthen the time of the oil recovery operation that needs to be performed at regular intervals. it can.

  FIG. 3 shows an example of an operation schedule when only one outdoor unit 3a or 3b is operated.

  First, when switching from the state in which the two outdoor units 3a and 3b are operating to the operation of only one outdoor unit 3a, the oil amount is adjusted in a stage (STEP 1) before the other outdoor unit 3b is stopped. This oil amount adjustment is performed by collecting oil from one outdoor unit 3a to the other outdoor unit 3b and then collecting oil from the other outdoor unit 3b to one outdoor unit 3a. Thereby, as shown in FIG. 2A or 2C described above, the outdoor unit 3b can be stopped in a state in which a large amount of oil has been collected by the oil separator 32a of one outdoor unit 3a.

  When only one outdoor unit 3a is operated, the amount of oil in the oil separator 32a is calculated for how long the outdoor unit 3a alone can be operated from the data at the time of adjusting the oil amount (STEP 2). ).

  Based on the calculated time, the oil amount is adjusted at a stage (STEP 3) before switching the operation from one outdoor unit 3a to the other outdoor unit 3b. This oil amount adjustment is performed by performing oil recovery from one outdoor unit 3a to the other outdoor unit 3b after performing oil recovery from the other outdoor unit 3b to the one outdoor unit 3a. Thereby, the operation of the outdoor unit 3b can be resumed and the outdoor unit 3a can be stopped in a state where a large amount of oil is recovered by the oil separator 32b of the other outdoor unit 3b.

  The duration of one continuous operation in the outdoor unit 3b depends on the operating capacity of the compressor 31b, the size of the oil separator 32b, the amount of oil recovered from the oil separator 32b, and the like. Even if it compares with time, it changes each time (STEP4).

  Moreover, what is necessary is just to stop as it is, when stopping the whole air conditioner 1 (STEP5). Since the oil does not flow out during this stop time, the operation of the outdoor unit 3b can be resumed by subtracting from the calculated continuous operation time (STEP 6).

  Then, at the stage before switching the operation from the other outdoor unit 3b to the one outdoor unit 3a (STEP 7), the same oil amount adjustment as described above is performed, and the operation is switched to the operation of only one outdoor unit 3a.

  In one outdoor unit 3a that is a driving unit, since one continuous operation time is calculated based on data obtained from the detection mechanism of each part, the operation is performed after adjusting the oil amount before the calculated time comes. Although it is basically switched, when the oil shortage of the outdoor unit 3a is irregularly detected, the other outdoor unit 3b is immediately operated regardless of this continuous operation time to adjust the oil amount. To switch the operation (STEP 8).

  It is also possible to stop the outdoor unit 3b and continue the operation of the outdoor unit 3a after only collecting oil from the outdoor unit 3b without changing the operation from the outdoor unit 3a to the other outdoor unit 3b in STEP3. It is. For example, it is effective when it is necessary to prevent the occurrence of transient fluctuations in the air conditioning capacity due to the operation change of the outdoor unit.

  In the above, an example of the oil amount adjustment and the operation schedule in the case of operating one outdoor unit 3a, 3b of the air conditioner 1 has been shown, but when operating two outdoor units 3a, 3b simultaneously, The oil amount is adjusted by collecting the oil one more time from the oil amount adjustment.

  That is, after the oil recovery from one oil separator 32a to the other oil separator 32b, the oil recovery from the oil separator 32b to the oil separator 32a is performed on the contrary, and then the one oil separator 32a is further recovered. The oil amount is adjusted by performing oil recovery to the other oil separator 32b, so that the oil amount in each of the oil separators 32a and 32b is made uniform.

  FIG. 2 (d) shows the last oil recovery in this oil amount adjustment.

  When oil is recovered from one oil separator 32a to the other oil separator 32b and then oil is recovered from the oil separator 32b to the oil separator 32a, the amount of oil in the oil separator 32a increases. For example, in the case of FIG. 2A, the time required until the amount of oil in the oil separator 32a is detected at the predetermined oil level height position S in the first oil recovery is the oil required for the oil separator 32b in the subsequent oil recovery. It should be longer than the time required to detect that the amount of oil is at the predetermined oil level height position S. Therefore, in the last oil recovery, the oil is recovered only for half the detection time required for the long initial oil recovery. As a result, a large amount of oil remains in one oil separator 32a, whereas only the amount of oil corresponding to the predetermined oil level height position S remains in the other oil separator 32b. Therefore, the amount of oil in each oil separator 32a, 32b can be made substantially equal.

  In the case of FIG. 2C, the time required for detecting the amount of oil in the oil separator 32a at the predetermined oil level height position S in the first oil recovery is the oil recovery time in the oil separator 32b in the subsequent oil recovery. Should be shorter than the time required to detect that the amount of oil is at the predetermined oil level height position S. Therefore, in the last oil recovery, it is only necessary to recover the oil for half the detection time required for the long second oil recovery.

  As a result, as shown in FIG. 2D, the oil amount in each of the oil separators 32a and 32b can be made uniform. Therefore, when two outdoor units 3a and 3b are operated simultaneously, this oil amount adjustment is preferable.

  FIG. 2 (d) shows a state in which a large amount of oil remains in one oil separator 32a and an amount of oil corresponding to the predetermined oil level height position S remains in the other oil separator 32b. The case where the oil amount in each oil separator 32a, 32b is made substantially equal is shown. On the other hand, as shown in FIG. 2 (e), a large amount of oil remains in the other oil separator 32b, and an amount of oil corresponding to the predetermined oil level height position S remains in one oil separator 32a. When the oil amount in each of the oil separators 32a and 32b is made substantially equal from the state where the oil is separated, the oil separator 32b is also half the longer time until the predetermined oil level height position S is detected. The oil may be moved from 32 to 32a.

  The time required for the amount of oil to be detected at the predetermined oil level height position S during oil recovery is provided with a sensor for measuring the oil level in the oil separators 32a and 32b. It is also possible to detect when the oil that has branched from the oil return branch pipes 324a and 324b and flows into the oil return pipes 19a and 19b changes from liquid to mist during oil recovery. It may be. The state in which the oil changes from a liquid to a mist can be determined based on information obtained by providing a temperature sensor and a pressure sensor in the oil flow path.

  In addition, when the oil recovery operation is performed, in addition to the oil recovered by the oil separators 32a and 32b, oil flowing out to the liquid side internal / external communication pipe 11, the gas side internal / external communication pipe 12, and the indoor units 2a and 2b Exists. Therefore, before performing the oil recovery operation, the compressors 3a and 3b that are operating (one unit in the case of one unit and both units in the case of two units) are operated at a certain number of revolutions for a certain period of time After the oil flowing out to the liquid side inside / outside connecting pipe 11, the gas side inside / outside connecting pipe 12, and the indoor units 2a, 2b is collected in the oil separators 32a, 32b as much as possible by the suction force of the compressors 3a, 3b. It is preferable to perform oil recovery operation and oil amount adjustment.

  In the present embodiment, two outdoor units 3a and 3b are connected in parallel, but three or more outdoor units may be connected in parallel. Although only two indoor units 2a and 2a are disclosed in the present embodiment, three or more indoor units may be connected.

  It can be used for various air conditioners in which a plurality of outdoor units having an oil separator are connected in parallel.

It is a refrigerant circuit figure explaining the flow of the oil at the time of the oil collection | recovery driving | operation of the air conditioner which concerns on this invention. (A) thru | or (e) is the schematic which shows the state of the oil separator at the time of oil quantity adjustment by the oil collection | recovery driving | operation of the air conditioner which concerns on this invention. It is a graph which shows an example of the driving schedule at the time of one outdoor unit driving | running of the air conditioner which concerns on this invention. It is a refrigerant circuit figure explaining the flow of the refrigerant at the time of normal cooling operation by two outdoor units of the air conditioner concerning the present invention. It is a refrigerant circuit figure explaining the flow of the refrigerant at the time of normal heating operation by two outdoor units of the air conditioner concerning the present invention. It is a refrigerant circuit diagram explaining the flow of the refrigerant | coolant at the time of normal cooling operation by the one outdoor unit of the air conditioner which concerns on this invention. It is a refrigerant circuit figure explaining the flow of the refrigerant at the time of normal heating operation by one outdoor unit of the air-conditioner concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioner 11 Liquid side internal / external communication pipe 12 Gas side internal / external communication pipe 13 External / external communication pipe 19a Oil recovery pipe 19b Oil recovery pipe 2a Indoor unit 2b Indoor unit 3a Outdoor unit 3b Outdoor unit 31a Compressor 31b Compressor 32a Oil separator 32b Oil separator 323a Oil return pipe 323b Oil return pipe 38a Waste heat recovery unit 38b Waste heat recovery unit SV51 Oil recovery on-off valve

Claims (6)

A plurality of outdoor units each having an oil separator are connected in parallel to the inner and outer connecting pipes connecting the indoor unit and the outdoor unit, and the compressor suction line of each outdoor unit is connected by the outer and outer connecting pipes. In the air conditioner that connects the external and external communication pipes,
An oil return pipe from the bottom of each oil separator is communicated to the compressor suction side of the own machine, and an oil recovery pipe from a predetermined position of each oil separator is connected to the external / external communication pipe via an oil recovery on-off valve, An air conditioner configured to open the oil recovery on-off valve of an oil surplus outdoor unit.   The drive source of the compressor of each outdoor unit is an engine, and a waste heat recovery unit that evaporates the refrigerant with engine waste heat is provided in the compressor suction line, and the outside communication pipe is disposed upstream of the waste heat recovery unit of each outdoor unit. The air conditioner according to claim 1, wherein the air conditioner is configured to be connected.   The air conditioner according to claim 1 or 2, wherein the oil recovery on-off valve of the stop transition machine is opened when there is a stop transition machine and a driving machine receiving an operation stop signal.   When there are two operating units, the oil recovery on-off valve of one outdoor unit is opened for a predetermined time or until the oil separator oil level is detected to be below a predetermined position and then closed, and then the other outdoor unit The air conditioner according to claim 1 or 2, wherein the oil recovery on-off valve is opened for a predetermined time or until an oil separator oil level is detected to be below a predetermined position.   When there are two operating units, the oil recovery on-off valve of one outdoor unit is opened and closed until the oil separator oil level is detected below the predetermined position, and then the oil of the other outdoor unit is closed. The recovery on-off valve is opened after the oil separator oil level is detected to be below a predetermined position and then closed, and the longer detection time of the two detection times from the opening of the oil recovery on-off valve to the oil level below the predetermined position. The air conditioner according to claim 1 or 2, wherein the oil recovery on-off valve of the outdoor unit on the side opposite to the time of detection is opened for half the time.   The air conditioner according to any one of claims 1 to 5, wherein the compressor of the operating unit is operated at a predetermined number of revolutions or more for a predetermined time before opening the oil recovery on-off valve of the outdoor unit.

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