WO2003064939A1

WO2003064939A1 - Oil collecting method for refrigerator

Info

Publication number: WO2003064939A1
Application number: PCT/JP2003/000704
Authority: WO
Inventors: Hiroshi Komano; Manabu Yoshimi; Atsushi Yoshimi; Ryuzaburo Yajima
Original assignee: Daikin Industries, Ltd.
Priority date: 2002-01-28
Filing date: 2003-01-27
Publication date: 2003-08-07
Also published as: JP2003214715A

Abstract

An oil collecting method for collecting oil in a refrigerating circuit (1A) to an outdoor unit (20) in a refrigerator having the outdoor unit (20) and an indoor unit (30) connected to each other through pipes (51, 52) and the refrigerating circuit (1A) for performing a vapor compression refrigerating cycle, comprising a first step for continuously driving a compressor (21) in the refrigerating circuit (1A) in the operating state of normal cycle of the refrigerating circuit (1A) where refrigerant is condensed in the outdoor unit (20) to perform a circulating operation to circulate the refrigerant in the refrigerant circuit (1A) until a specified time is elapsed and a second step for closing a liquid side stop valve (41) and continuously driving the compressor (21) to perform a collecting operation to collect the refrigerant in the refrigerant circuit (1A) together with oil to the outdoor unit (20).

Description

Description Oil recovery method for refrigeration equipment Technical field

The present invention relates to an oil recovery method for a refrigeration apparatus, and more particularly to a method for recovering oil in a pipe connecting a heat source unit and a utilization unit. Background art

Conventionally, refrigeration systems such as air conditioners equipped with a refrigerant circuit performing a vapor compression refrigeration cycle have used CFC (chlorofluorocarbon) -based refrigerants or HCFC (hydrochlorofluorocarbon) -based refrigerants. However, these CFC-based refrigerants and HCFC-based refrigerants had environmental problems such as destruction of the ozone layer. Therefore, it is desired to replace these existing refrigeration units with new refrigeration units that use HFC (hydrofluorocarbon) -based refrigerants or HC (hydrocarbon) -based refrigerants.

When renewing this refrigeration system, it is difficult to replace the pipes because the pipes are often embedded inside the building. Therefore, a new refrigeration system is being introduced by diverting the existing piping as it is.

On the other hand, naphthenic mineral oil or alkylbenzene oil is used as the refrigerating machine oil in a conventional refrigeration system using a CFC-based refrigerant or an HCFC-based refrigerant containing chlorine. This refrigerating machine oil is not compatible with HFC refrigerant containing no chlorine. If the refrigerant and the refrigerating machine oil are not compatible, the refrigerating machine oil discharged from the compressor does not return to the compressor again, and thus there is a problem that seizure occurs due to a shortage of the refrigerating machine oil.

Refrigeration oils mainly used for HFC refrigerants or HC refrigerants that do not contain chlorine are synthetic oils such as polyol esters and polyvinyl ether. The refrigerating machine oil, which is a synthetic oil, has a problem that, for example, if the conventional refrigerating machine oil such as mineral oil is mixed, the compatibility temperature (lower limit temperature), that is, the temperature at which the refrigerant and the refrigerating machine oil are separated increases according to the mixing ratio. Occurs. Therefore, when diverting existing pipes, it is conceivable to manually clean the pipes, but this has the problem that it takes time and effort.

Therefore, a pipe cleaning device for cleaning pipes has been proposed as disclosed in Japanese Patent Application Laid-Open No. 2001-141340. This pipe cleaning device includes a compressor, an oil separator, a four-way valve, a high / low pressure heat exchanger, a pressure reducing device, a separating device, a heat source side heat exchanger, and an accumulator. Then, the outdoor unit and the indoor unit are removed from the existing air conditioner, and only the pipe connecting the outdoor unit and the indoor unit is left. The pipe cleaning device is connected to one end of the pipe, and the other end of the pipe is connected by a bypass pipe to form a refrigerant circuit.

The refrigerant circuit is filled with R 407 C of HFC-based refrigerant as a cleaning agent, and the cleaning agent is circulated to remove refrigeration oil inside the piping. Solution 1

As described above, there has been a problem that the use of a conventional pipe cleaning device is extremely expensive.

On the other hand, it has been considered to use R22, R225 or R141b, which is a HFCFC-based refrigerant containing chlorine, as a cleaning agent. However, since R22 and R141b have a high boiling point of 32 to 56 ° C, they hardly evaporate and remain in the pipe after washing. Therefore, there is a concern that sludge or the like may be generated due to the residual cleaning agent as it is. Therefore, it is necessary to blow the inside of the pipe with nitrogen gas or the like to remove the cleaning agent. As a result, even if the above-mentioned pipe cleaning device is used, it takes a long time to recover. In addition, both cleaning agents have environmental problems.

Also, when alkylbenzene is used, its boiling point is as high as about 300 ° C., and the same trouble as the above-mentioned HFCFC-based refrigerant is required. Furthermore, there is almost no cleaning agent having a low boiling point and no dissolution in existing refrigerating machine oil, which has no environmental problem, so that the above-described procedure must be followed.

The present invention has been made in view of the above, and an object of the present invention is to make it possible to easily remove oil from an existing pipe without using a pipe cleaning device or the like. Disclosure of the invention

—Summary of the Invention I

The present invention utilizes a pump-down operation, which is a refrigerant recovery operation, to reduce the amount of oil remaining in a pipe to an allowable value or less.

In other words, the inventors of the present application have found the following matters as a result of long-term research on the removal of oil from piping.

The compatibility temperature T1 at which the CFC-based refrigerant or HFCC-based refrigerant and the refrigerating machine oil dissolve is higher than the compatibility temperature T2 at which the HFC-based refrigerant or the HCC refrigerant and the refrigerating machine oil are dissolved. In the new refrigeration system, the compatible temperature T increases according to the amount of refrigeration oil in the existing refrigeration system remaining in the existing piping. However, if the compatibility temperature T in the newly installed refrigeration system is lower than the compatibility temperature T1 in the existing refrigeration system (T <T1), mixing of refrigeration oil in the existing refrigeration system does not pose a problem. This is evident from the fact that compatibility temperature Τ1 does not matter in existing refrigeration equipment.

As a result, in the existing piping, there is an allowable value for the residual amount of refrigerating machine oil in the existing refrigerating equipment.

On the other hand, the pump-down operation provided in general refrigerant recovery equipment and refrigeration equipment is intended only for the recovery of refrigerant, and no consideration is given to the recovery of oil remaining in the piping when the pump is down.

However, as a result of earnest research, the inventors of the present application have found that it is possible to collect not only the refrigerant but also the remaining amount of the refrigerating machine oil in the existing piping to an allowable range using the pump-down operation of the existing refrigerating device. Then, this matter is as follows.

(1) In order to collect oil during the pump-down operation, which is a recovery operation, a preliminary operation, which is a circulation operation, is required before the pump-down operation.

In other words, it is necessary to perform a preliminary operation in which the refrigerant circulates through the refrigerant circuit in order to increase the compatibility between the refrigerant and the refrigerating machine oil. If this preliminary operation is not performed, before the pump-down operation, the oil will fall into large oil droplets and be laid down in the indoor unit, which is the utilization unit. In particular, in an installation environment where the outdoor unit, which is a heat source unit, is installed on the rooftop and the height difference between the outdoor unit and the indoor unit is large, the outdoor unit stays in the indoor unit during the pump-down operation. Refrigerant and oil must be recovered by the outdoor unit against gravity. If the oil separates from the refrigerant to form oil droplets, the oil will lose its gravity and will not be collected in the outdoor unit, but will remain attached to the piping. Therefore, we decided to perform preliminary operation to make the refrigerant and the refrigerating machine oil sufficiently compatible.

In this regard, as shown in Fig. 3, the triangle mark indicates the case where the preliminary operation was not performed, and the amount of oil remaining is twice the allowable value B. On the other hand, the squares in Fig. 3 indicate the case where the preliminary operation was performed, and the amount of oil remaining within the allowable value B range.

(2) Preliminary operation (circulation operation) must be continuous operation with the cooling cycle, which is the normal cycle.

In other words, since the pre-operation is performed, the oil becomes mist-like, and even if there is a difference in height between the pipes, it is possible to recover the oil with a certain degree of gravity. On the other hand, in the case of the heating cycle operation, which is the reverse cycle, the indoor heat exchanger (use-side heat exchanger) becomes a condenser, and the steady oil amount in the indoor heat exchanger is the cooling cycle. It is several times as large as. As a result, the amount of oil adhering in the middle of the pipe during refrigerant recovery increases. Therefore, as shown by the circle in Fig. 3, the residual oil amount exceeds the allowable value B.

In addition, in the case of normal cooling operation, not forced operation of the cooling cycle in which forced continuous operation is performed, the load may be insufficient depending on the indoor and outdoor environment, and the operation and stop may be repeated. In this case, the circulation of the refrigerant is deteriorated, and the amount of oil flowing out at the time of restart is increased, so that the amount of oil stored in the indoor heat exchanger is increased. In other words, the amount of oil adhering to the piping during the recovery operation increases. Therefore, when pre-operation is performed in normal cooling operation, it is necessary for the compressor to operate continuously for a predetermined time.

(3) From the end of the pre-operation to the start of the pump-down operation, perform the operation without stopping. Or, when the operation must be stopped, the pump must be closed after closing the liquid side shut-off valve after the end of the preliminary operation.

In other words, at the start of operation, the oil that has accumulated in the compressor etc. flows out at once, so if the liquid side stop valve is closed after the start of the pump-down operation, a large amount of oil will adhere to the pipes and the indoor heat exchanger and will be recovered. It will be difficult. In general pump-down operation, the liquid side shutoff valve may be closed after 1-2 minutes of operation. In this case, the amount of residual oil increases rather than decreases. At this point, as shown in Fig. 2, if the liquid-side shut-off valve is closed before the pump-down operation, which is the refrigerant recovery operation, the amount of oil remaining within the allowable value A will be obtained. On the other hand, if the liquid-side shutoff valve is closed after the pump-down operation, which is a refrigerant recovery operation, the amount of oil remaining will be several times the allowable value A.

(4) When the pump-down operation is performed after stopping the operation by one B after the end of the preliminary operation, it is necessary to minimize the time from the end of the preliminary operation to the start of the pump-down operation.

In other words, while the operation is stopped, the refrigerant rapidly cools down and the viscosity of the oil increases, resulting in oil droplets. Therefore, there is a limit to the stop time before starting the pump-down operation. This is particularly noticeable during the heating period. If the operation has been stopped for more than the specified time, it is necessary to perform the preliminary operation again.

By observing the above items (1) to (4), the existing piping can be used as it is without washing the existing piping or installing an oil recovery device. One solution one

Specifically, the first invention includes a refrigerant circuit (1A) in which a heat source unit (20) and a utilization unit (30) are connected by piping (51, 52), and performs a vapor compression refrigeration cycle. It is intended for an oil recovery method for a refrigeration system that recovers oil in the refrigerant circuit (1A) to the heat source unit (20) side. Then, in a normal cycle operation state of the refrigerant circuit (1A) in which the refrigerant condenses in the heat source unit (20), the compressor (21) of the refrigerant circuit (1A) is continuously driven, and the refrigerant circuit (1A) is driven. The method includes a first step of performing a circulating operation for circulating the refrigerant in the) until a predetermined time elapses. In addition, following the first step, a recovery operation is performed in which the compressor (21) is continuously driven to recover the refrigerant in the refrigerant circuit (1A) together with oil to the heat source unit (20) side. It has a second process.

Therefore, in the first invention, the circulation operation and the recovery operation of the refrigerant are performed, and the oil in the pipes (51, 52) is recovered to the heat source unit (20) side.

The second invention provides a refrigerant circuit (1A) in which a heat source unit (20) and a utilization unit (30) are connected by pipes (51, 52) to perform a vapor compression refrigeration cycle. The present invention is directed to an oil recovery method for a refrigeration system that recovers oil from the refrigerant circuit (1A) to the heat source unit (20). Then, in a normal cycle operation state of the refrigerant circuit (1A) in which the refrigerant condenses in the heat source unit (20), the compressor (21) of the refrigerant circuit (1A) is continuously driven, and the refrigerant circuit (1A) is driven. The method includes a first step of performing a circulating operation for circulating the refrigerant in the) until a predetermined time elapses. In addition, when the first step is completed, the compressor (21) is temporarily stopped, and then the compressor (21) is driven to drive the refrigerant of the refrigerant circuit (1A) together with oil to the heat source unit (20). ) Side, and a second step of performing a recovery operation for recovery.

Therefore, in the second invention, the circulation operation and the recovery operation of the refrigerant are performed, and in this recovery operation, the compressor (21) is temporarily stopped, and the oil in the pipes (51, 52) is discharged to the heat source unit (20) side. To be collected.

In a third aspect, in the first or second aspect, the heat source unit (20) includes a compressor (21), a heat source side heat exchanger (23), and an expansion mechanism (24). The heat source unit (20) is connected to the liquid side pipe (51) via the liquid side shutoff valve (41), and is connected to the gas side pipe (52) via the gas side shutoff valve (42). It is connected to the. In the second step, the recovery operation is started with the liquid-side stop valve (41) closed, and the gas-side stop valve (42) is closed after the completion of the recovery operation.

Therefore, in the third invention, the refrigerant and the oil are trapped in the heat source unit (20) by the liquid-side stop valve (41) and the gas-side stop valve (42).

In a fourth aspect based on the first or second aspect, the utilization unit (30) includes a utilization-side heat exchanger (31) and a utilization-side fan (32) having a variable air volume. . Then, in the first step, the use side fan (32) is driven at a high air flow with a large air flow to perform a circulation operation.

Therefore, in the fourth aspect of the present invention, since the air volume of the use side fan (32) is large, the circulation of the refrigerant is promoted.

In a fifth aspect based on the first or second aspect, the utilization unit (30) includes a utilization-side heat exchanger (31) and a utilization-side fan (32) having a variable air volume. . Then, in the first step, the use side fan (32) is driven at a low air flow with a small air flow to perform a circulation operation. Therefore, in the fifth invention, since the air volume of the use side fan (32) is small, the refrigerant in the use unit (30) during the recovery operation is reduced.

In a sixth aspect based on the first or second aspect, the utilization unit (30) includes a utilization-side heat exchanger (31) and a utilization-side fan (32) having a variable air volume. . In the first step, the use side fan (32) is driven at a high air flow with a large air flow in the first half of the circulation operation, and the use side fan (32) is driven at a low air flow with a small air flow in the second half of the circulation operation. Drive.

Therefore, in the sixth invention, the circulation of the refrigerant is promoted by the high air flow of the use side fan (32), and the refrigerant in the use unit (30) at the time of the recovery operation is promoted by the low air flow of the use side fan (32). Is reduced.

In a seventh aspect based on the first or second aspect, the first step is such that the height difference between the pipes (51, 52) is small in accordance with the height difference between the pipes (51, 52). The shorter the cycle operation time, the shorter the time.

Therefore, in the seventh invention, the circulation operation is shortened in a horizontal pipe or the like.

In an eighth aspect based on the first or second aspect, the first step is such that the length of the pipe (51, 52) is short corresponding to the length of the pipe (51, 52). The shorter the circulation operation time, the shorter the time.

Therefore, in the eighth invention, when the length of the pipe (51, 52) is short, the circulation operation is short.

In a ninth aspect, in the first or second aspect, the heat source unit (20) includes a compressor (21), a heat source side heat exchanger (23), and an expansion mechanism (24). I have. The heat source unit (20) is provided with an oil separator (60) on the discharge side of the compressor (21) or on the downstream side of the expansion mechanism (24) in the normal cycle.

Therefore, in the ninth invention, the oil is recovered by the oil separator (60), so that the degree of freedom in controlling the recovery operation is improved.

Effect of one invention

Therefore, according to the present invention, since the refrigerant circulation operation and the recovery operation are performed, the oil in the pipes (51, 52) is reliably and easily recovered to the heat source unit (20) side. δ

can do.

As a result, the residual amount of the refrigerating machine oil used in the existing CFC-based or HFCC-based refrigerant devices in the pipes (51, 52) can be reduced to an allowable value or less. Therefore, the pipes (51, 52) of the existing CFC-based or HCFC-based refrigerant equipment do not need to be washed with a cleaning device, etc., and the newly installed HFC-based or HC-based refrigerant equipment can be connected to the existing piping (51, 52). ) Can be installed.

Also, since there is no need to provide an oil recovery device or the like, an increase in the number of parts can be prevented.

In particular, according to the first invention, the circulation operation and the recovery operation are continuously performed while the compressor (21) is continuously driven. Oil can be collected on the heat source unit (20) side. As a result, oil recovery can be performed more reliably and promptly.

According to the second invention, even when the compressor (21) is temporarily stopped to perform the recovery operation, the refrigerant and the oil are mixed with the heat source unit (20) in a state where the refrigerant and the oil are dissolved. Can be collected on the side.

Further, according to the third aspect, since the liquid-side stop valve (41) and the gas-side stop valve (42) are provided, the refrigerant and the oil can be reliably sealed in the heat source unit (20).

Further, according to the fourth invention, since the air volume of the use side fan (32) is set to a large high air volume, heat exchange in the use side heat exchanger (31) can be promoted to increase the refrigerant circulation. However, the refrigerant and the oil can be rapidly dissolved. As a result, the oil can be reliably recovered.

According to the fifth aspect of the present invention, since the flow rate of the use side fan (32) is set to a small and low flow rate, the amount of refrigerant circulating is small, so that at the end of the circulation operation, the pipes (51, 52) and the use unit are not used. (30) The amount of refrigerant and oil in (30) can be reduced. As a result, the oil can be reliably collected.

According to the sixth aspect of the invention, in the circulation operation, the air volume of the first-side usage-side fan (32) is set to a high air volume, and the air volume of the second-half usage-side fan (32) is set to a low air volume. In the first half of circulation operation, increase refrigerant circulation to promote compatibility of refrigerant and oil On the other hand, in the latter half, the amount of refrigerant and oil in the pipes (51, 52) and the utilization unit (30) can be reduced. As a result, the oil can be reliably collected.

According to the seventh aspect of the invention, the circulation operation in the first step is performed in accordance with the height difference of the pipes (51, 52) as the height difference of the pipes (51, 52) is smaller. Since the length is shortened, the time for circulation operation can be shortened in the case of horizontal piping and the like.

According to the eighth invention, the circulation operation of the first step is performed in accordance with the length of the pipe (51, 52), and the shorter the length of the pipe (51, 52), the shorter the time of the circulation operation. Therefore, when the pipe length is short, the time of the circulation operation can be shortened.

Further, according to the ninth aspect, since the oil separator (60) is provided, it is not necessary to limit the closing time of the heat source unit (20) and the liquid side pipe (51) before the start of the recovery operation. That is, since the oil is collected by the oil separator (60), a large amount of oil does not flow out to the liquid side pipe (51) at the start of the collecting operation. As a result, the degree of freedom of the closing time is improved. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a refrigerant circuit diagram of an air conditioner illustrating a configuration of the present invention.

FIG. 2 is a characteristic diagram showing the residual oil amount according to the closing timing of the liquid side closing valve.

FIG. 3 is a characteristic diagram showing the residual oil amount according to the length of the preliminary operation.

FIG. 4 is a flowchart showing the oil recovery method according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing an oil recovery method according to Embodiment 2 of the present invention.

FIG. 6 is a flowchart showing an oil recovery method according to Embodiment 3 of the present invention.

FIG. 7 is a flowchart showing an oil recovery method according to Embodiment 4 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

One embodiment 11

Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the refrigeration apparatus of the present embodiment is an air conditioner (10) that switches between a cooling operation and a heating operation.

In the air conditioner (10), the refrigerant circulates and performs a vapor compression refrigeration cycle. ぅ Equipped with a refrigerant circuit (1A). The refrigerant circuit (1A) includes a liquid pipe (51), a gas pipe (52), and an outdoor unit (20), which is a heat source unit, and an indoor unit (30), which is a use unit. It is configured to be connected by.

The outdoor unit (20) includes a compressor (21), a four-way switching valve (22), an outdoor heat exchanger (23) as a heat source side heat exchanger, and an electric expansion valve (24) as an expansion mechanism. ing. The compressor (21), the four-way switching valve (22), the outdoor heat exchanger (23), and the electric expansion valve (24) are sequentially connected by an outdoor pipe (2a) that is a refrigerant pipe. . The outdoor heat exchanger (23) is provided with an outdoor fan (25) which is a heat source side fan.

The indoor unit (30) includes an indoor heat exchanger (31) as a use side heat exchanger, and an indoor pipe (3a) as a refrigerant pipe is connected to the indoor heat exchanger (31). . The indoor heat exchanger (31) is provided with an indoor fan (32) that is a use-side fan.

The end of the liquid side outdoor pipe (2a) in the outdoor unit (20), that is, the end of the outdoor pipe (2a) on the side of the electric expansion valve (24) is a liquid side closing mechanism which is a liquid side closing mechanism. A chain valve (41) is provided, and one end of a liquid pipe (51) is connected via a connector (26) such as a flare connection. The end of the outdoor pipe (2a) on the gas side in the outdoor unit (20), that is, the end of the outdoor pipe (2a) on the four-way switching valve (22) side is a gas-side closing mechanism. A side stop valve (42) is provided, and one end of a gas pipe (52) is connected via a connector (27) such as a flare connection.

One end of the liquid pipe (51) is connected to an end of the liquid side indoor pipe (3a) in the indoor unit (30) via a connector (33) such as a flare connection. The other end of the gas pipe (52) is connected to the end of the indoor pipe (3a) on the gas side in the indoor unit (30) via a connector (34) such as a flare connection.

The refrigerant circuit (1A) is configured to switch between a cooling cycle operation, which is a normal cycle, and a heating cycle operation, which is a reverse cycle, by switching the four-way switching valve (22). That is, when the four-way switching valve (22) is switched to the solid line side in FIG. 1, the refrigerant circuit (1A) operates in a cooling cycle in which the refrigerant condenses in the outdoor unit (20). The refrigerant circulates during the operation. In addition, the above four-way switching valve When (22) switches to the broken line side in FIG. 1, the refrigerant circuit (1A) circulates refrigerant in the heating cycle operation, which is the reverse cycle operation in which the refrigerant condenses in the indoor unit (30).

An example of the operation in the normal cycle is a cooling operation. In this cooling operation, refrigerant is discharged from the compressor (21), condensed in the outdoor heat exchanger (23), expanded by the electric expansion valve (24), and evaporated and compressed in the indoor heat exchanger (31). The circulation returning to the machine (21) is repeated. On the other hand, there is a heating operation as an example of the reverse cycle operation. In this heating operation, the refrigerant is discharged from the compressor (21), condensed in the indoor heat exchanger (31), expanded by the electric expansion valve (24), and evaporated in the outdoor heat exchanger (23). The circulation returning to the compressor (21) is repeated. One oil recovery method

Next, a method of recovering the oil that is the refrigerating machine oil in the above-described air conditioner (10) will be described. In other words, when replacing the existing air conditioner (10) with a new air conditioner (10), the liquid pipe (51) and the gas pipe (52) may be reused. At that time, it is necessary to collect the refrigerating machine oil attached to the liquid pipe (51) and the gas pipe (52).

Therefore, in the existing air conditioner (10), the oil that is the refrigerating machine oil is collected in the outdoor unit (20) such as the compressor (21). This oil recovery method basically includes a first step of performing a preliminary operation, which is a circulation operation in which the refrigerant is circulated in the refrigerant circuit (1A) so that the refrigerant and the oil are sufficiently compatible with each other; And a second step of performing a pump-down operation, which is a recovery operation for recovering the refrigerant and the oil to the outdoor unit (20) in a state where they are sufficiently compatible.

In this oil recovery method, as shown in FIG. 4, first, in step ST1, the refrigerant circuit (1A) is set to the cooling operation mode. That is, the four-way switching valve (22) is switched to the solid line side in FIG. 1, and the refrigerant circuit (1A) is set to the state of the cooling cycle, which is the normal cycle. Further, the temperature set value in the room is set to the lowest value so that the compressor (21) is driven continuously.

Then, move to step ST2, start the first process, and operate the cooling cycle. Start cooling operation (circulation operation). Subsequently, the process proceeds to step ST3 to start counting the operation time of the cooling operation, and proceeds to step ST4 to determine whether or not the compressor (21) has stopped. If the compressor (21) is continuously driven, the process proceeds from step ST4 to step ST5, where it is determined whether or not the cooling operation has been performed for a predetermined time. Returning to ST4, the above operation is repeated, and the compressor (21) performs a preliminary operation in which the compressor (21) is continuously driven.

The predetermined time of step ST5 is set to, for example, 30 minutes. That is, when the cooling operation is started, the refrigerant circulates in the refrigerant circuit (1A). However, in order for the refrigerant and the refrigerating machine oil to be compatible, the refrigerant circulates in the refrigerant circuit (1A) for a predetermined time. There is a need. Thus, for example, a cooling operation for 30 minutes is performed so that the refrigerant and the refrigerating machine oil are compatible.

Thereafter, when the predetermined time has elapsed and the compressor (21) is continuously driven for the predetermined time, the determination in step ST5 becomes YES, and the process proceeds to step ST6, in which the cooling operation is temporarily stopped, and As soon as the first step is completed, the second step starts. That is, the continuous driving of the compressor (21) is temporarily stopped.

Thereafter, the process proceeds to step ST7, where the liquid-side shutoff valve (41) is fully closed. For example, the liquid-side shutoff valve (41) is manually closed, and the outdoor piping (2a) of the outdoor unit (20) and the liquid piping are connected. (51) is closed. Thereafter, the process proceeds to step ST8, where it is determined whether or not the stop time of the compressor (21) is longer than a predetermined time. That is, if the stop time of the compressor (21) is long, the refrigerating machine oil becomes droplets.

Therefore, if the stop time of the compressor (21) becomes, for example, 30 minutes or more, the determination in step ST8 becomes YES, the process returns to step ST2, and the cooling operation as the circulating operation is performed again. .

On the other hand, if the stop time of the compressor (21) is within the predetermined time, the determination in step ST8 is NO and the process proceeds to step ST9, where the refrigerant circuit (1A) remains in the normal cycle. Starts the cooling operation which is the recovery operation. That is, although the air-conditioning apparatus (10) of the present embodiment does not have a pump-down function, since the liquid-side stop valve (41) is closed, the pump-down operation is started by the start of the cooling operation. Become. Subsequently, the process proceeds to step ST10, where it is determined whether or not the pump-down operation has been performed for a predetermined time, and the pump-down operation is performed until the predetermined time has elapsed. When the predetermined time has elapsed, the process proceeds to step ST11. Then, the gas side shut-off valve (42) is fully closed, and the process proceeds to step ST12 to stop the cooling operation. That is, the cooling operation, which is the pump-down operation, is stopped, and the second process ends. By this cooling operation, the refrigerating machine oil is confined in the outdoor unit (20).

After that, move to the third step, and remove the outdoor unit (20) and indoor unit (30) from the connecting pipes (26, 27, 33, 34) from the liquid pipe (51) and gas pipe (52). . Then, the new outdoor unit (20) and the new indoor unit (30) are connected to the existing liquid piping (51) and gas piping (52), and the installation of the new air conditioner (10) is completed. .

In step ST4, if the compressor (21) stops during the cooling operation which is the circulation operation, the compatibility of the refrigerant and the oil is not promoted. Therefore, the process proceeds to step ST13 to reset the time count of the cooling operation. And return to step ST3 to continue the cooling operation.

In addition, in the cooling operation as the circulation operation and the cooling operation as the recovery operation, the indoor fan (32) operates at a high air flow. For example, if the air volume of the indoor fan (32) can be set to four levels: strong, medium, low, and light, set the maximum air volume to “strong” or a large air volume to “medium”. As a result, heat exchange in the indoor heat exchanger (31) can be promoted to increase the refrigerant circulation.

Conversely, in the above-mentioned circulation operation, the air volume of the room / fan (32) may be set to “minimum air volume” of the minimum air volume or “weak” of the small air volume. In this case, since the refrigerant circulation amount is small, the refrigerant amount and the oil amount in the liquid pipe (51), the gas pipe (52), and the indoor unit (30) can be reduced at the end of the circulation operation.

Furthermore, in the above-mentioned circulation operation, in the first half, the air volume of the indoor fan (32) is set to “strong” of the maximum air volume or “medium” of the large air volume, and in the second half, the air volume of the indoor fan (32) is minimized. The air volume may be set to “light wind” or a small air volume “weak”. In this case, in the first half of the circulation operation, the refrigerant circulation is increased to promote the compatibility between the refrigerant and the oil, while in the second half, the liquid pipe (51) and the gas pipe (52) are connected to the indoor unit. (30) The amount of refrigerant and the amount of oil in (30) can be reduced. Effect of Embodiment 1

As described above, according to this embodiment, since the circulation operation and the recovery operation of the refrigerant are performed, the oil in the liquid pipe (51) and the gas pipe (52) is reliably supplied to the outdoor unit (20) side. And it can be easily collected.

As a result, the residual amount of the refrigerating machine oil used in the existing CFC-based refrigerant or HFCC-based refrigerant in the liquid pipe (51) and the gas pipe (52) can be reduced to an allowable value or less. Therefore, the liquid pipe (51) and gas pipe (52) of the existing CFC-based or HCFC-based refrigerant system need not be cleaned with a cleaning device or the like. It can be connected to the liquid pipe (51) and the gas pipe (52).

Further, since the liquid-side shut-off valve (41) and the gas-side shut-off valve (42) are provided, the refrigerant and the oil can be reliably sealed in the outdoor unit (20).

Further, when the air volume of the indoor fan (32) is set to a large high air volume, the heat exchange in the indoor heat exchanger (31) can be promoted to increase the circulation of the refrigerant, and the compatibility of the refrigerant and the oil can be rapidly increased. Can be done. As a result, the oil can be reliably recovered.

If the air volume of the indoor fan (32) is set to a small low air volume, the amount of refrigerant circulated is small, so that at the end of circulation operation, the liquid pipe (51) and gas pipe (52) and the indoor unit (30) , The amount of refrigerant and the amount of oil can be reduced. As a result, the oil can be reliably recovered.

Also, in the above-mentioned circulation operation, if the air volume of the first half indoor fan (32) is set to a high air volume and the air volume of the second half indoor fan (32) is set to a low air volume, the refrigerant circulation will increase in the first half of the circulation operation. In the latter half, the amount of refrigerant and oil in the liquid pipe (51), the gas pipe (52) and the indoor unit (30) can be reduced. As a result, the oil can be reliably collected. Embodiment 2—

Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 5, in the present embodiment, instead of the air conditioner (10) having no pump-down function in the first embodiment, an air conditioner (10) having a pump-down function is provided. This is the case.

The oil recovery method of the air conditioner (10) is the same as that of the first embodiment except that step ST9 in FIG. 4 in the first embodiment replaces step ST29 in FIG.

That is, first, the four-way switching valve (22) is switched to the solid line side in Fig. 1, the refrigerant circuit (1A) is set in the cooling cycle state, which is the normal cycle, and the indoor temperature set value is set to the lowest value. (Step ST 21).

After that, the first step is started, the cooling operation (circulation operation), which is the operation of the cooling cycle, is started, the operation time of this cooling operation is counted, and the compressor (21) is driven continuously. If so, the above operation is repeated until a predetermined time elapses, and the refrigerant is circulated (step ST22 to step ST25).

Thereafter, when the predetermined time has elapsed and the compressor (21) has been continuously driven for a predetermined time, the continuous driving of the compressor (21) is temporarily stopped to stop the cooling operation, and the first step is performed. At the same time, the second process starts (step ST26).

Thereafter, the liquid-side stop valve (41) is fully closed, and it is determined whether or not the stop time of the compressor (21) is longer than a predetermined time. After 30 minutes, the cooling operation, which is the circulation operation, is restarted (step ST27 and step ST28).

On the other hand, if the stop time of the compressor (21) is within the predetermined time, in step ST29, the refrigerant recovery operation switch, which is the pump down operation switch, is turned ON.

Subsequently, the system waits for the refrigerant recovery operation, which is the pump-down operation, to be performed for a predetermined time. After the predetermined time has elapsed, the gas-side shut-off valve (42) is fully closed, the refrigerant recovery operation is stopped, and the second process is performed. (Step ST30 to Step ST32). This By the refrigerant recovery operation, the refrigerating machine oil is confined in the outdoor unit (20).

After that, the process moves to the third step, where the outdoor unit is connected through the fittings (26, 27, 33, 34).

Remove (20) and the indoor unit (30) from the liquid pipe (51) and gas pipe (52). Then, the new outdoor unit (20) and the new indoor unit (30) are connected to the existing liquid piping (51) and gas piping (52), and the installation of the new air conditioner (10) is completed. .

It should be noted that in step ST24, the compressor is operated during the cooling operation, which is a circulation operation.

When (21) stops, the process moves to step ST33, resets the time count of the cooling operation, returns to step ST23, and continues the cooling operation. Other configurations, operations, and effects are the same as those of the first embodiment.

In addition, the above pump down function is generally a function of automatically performing a pump down operation. This automatic pump-down operation simulates a manual pump-down operation. After performing a running-in operation for several minutes, the electric expansion valve (24) is fully closed as an alternative to fully closing the liquid-side stop valve (41). There are cases. In order to prevent the oil of the outdoor unit (20) from flowing out of the outdoor unit (20) at a stretch due to this leveling operation, the liquid side closing valve (41) is fully closed in step ST27.

Also, in the above pump down function, since the electric expansion valve (24) is an alternative to the liquid side closing valve (41), the timing of fully closing the liquid side closing valve (41) may be the end point of the pump down. . Therefore, in step ST27, the liquid-side stop valve (41) is fully closed. Embodiment 3—

Next, a third embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 6, in the present embodiment, instead of temporarily stopping the compressor (21) in the second step in the first embodiment, the circulation operation is performed while the compressor (21) is continuously driven. The recovery operation is performed continuously.

The oil recovery method in this air conditioner (10) is different from the first embodiment in that steps ST6, ST8, and ST9 in FIG. Other than the above is the same as the first embodiment.

That is, first, the four-way switching valve (22) is switched to the solid line side in Fig. 1, the refrigerant circuit (1A) is set in the cooling cycle state, which is the normal cycle, and the indoor temperature set value is set to the lowest value. (Step ST41).

After that, the first step is started, the cooling operation (circulation operation), which is the operation of the cooling cycle, is started, the operation time of this cooling operation is counted, and the compressor (21) is driven continuously. If so, the above operation is repeated until a predetermined time elapses, and the refrigerant is circulated (step ST42 to step ST45).

Thereafter, when the predetermined time has elapsed and the compressor (21) is continuously driven for a predetermined time, the first step is completed while the compressor (21) is continuously driven, and the liquid side is closed simultaneously. The second step is started by fully closing the valve (41) (step ST46).

That is, since the compressor (21) is continuously driven, the liquid-side shut-off valve (41) is closed to start the pumping-down recovery operation. That is, although the air-conditioning apparatus (10) of the present embodiment does not have a pump-down function, the liquid-side closing valve (41) is closed, so that the pump-down operation is started. Wait for the pump-down operation to be performed for a predetermined time, and after the predetermined time has elapsed, close the gas side shut-off valve (42) completely, stop the cooling operation that is the pump-down operation, and execute the second step. The process ends (step ST47 to step ST49). By this cooling operation, the refrigerating machine oil is confined in the outdoor unit (20).

After that, the process moves to the third step, where the outdoor unit is connected via the fittings (26, 27, 33, 34).

In step ST44, the compressor is operated during the cooling operation, which is the circulation operation.

When (21) stops, the process moves to step ST50, resets the cooling operation time count, returns to step ST43, and continues the cooling operation.

Therefore, in the present embodiment, the circulation operation and the recovery operation are continuously performed while the compressor (21) is continuously driven, so that the refrigerant and the oil are mixed with each other. Refrigerant and oil can be recovered to the outdoor unit (20). As a result, oil recovery can be performed more reliably and promptly. Other configurations, operations, and effects are the same as those of the first embodiment. One embodiment 41

Next, a fourth embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 7, in the present embodiment, instead of the air conditioner (10) having no pump-down function in the third embodiment, an air conditioner (10) having a pump-down function is provided. This is the case.

The oil recovery method of this air conditioner (10) is the same as that of the third embodiment except that step ST67 of FIG. 7 is added after step ST46 of FIG. 6 in the third embodiment. is there.

That is, first, the four-way switching valve (22) is switched to the solid line side in Fig. 1, the refrigerant circuit (1A) is set in the cooling cycle state, which is the normal cycle, and the indoor temperature set value is set to the lowest value. (Step ST61).

After that, the first step is started, the cooling operation (circulation operation), which is the operation of the cooling cycle, is started, the operation time of this cooling operation is counted, and the compressor (21) is driven continuously. If so, the above operation is repeated until a predetermined time has elapsed, and the refrigerant is circulated (step ST62 to step ST65).

That is, in a state where the compressor (21) is continuously driven, the refrigerant recovery operation switch which is the pump down operation switch is turned on, and the recovery operation which is the pump down operation is started. Wait for the pump-down operation to be performed for a predetermined time, and when the predetermined time has elapsed, close the gas-side shut-off valve (42) completely, stop the refrigerant recovery operation that is the pump-down operation, and end the second process. (Step ST67 to Step ST70). By this refrigerant recovery operation, the refrigerating machine oil is sealed in the outdoor unit (20). After that, the process moves to the third step, where the outdoor unit is connected through the fittings (26, 27, 33, 34).

In step ST64, the compressor is operated during the cooling operation, which is the circulation operation.

When (21) stops, the process moves to step ST71, resets the cooling operation time count, returns to step ST63, and continues the cooling operation.

Therefore, in the present embodiment, since the circulation operation and the recovery operation are continuously performed while the compressor (21) is continuously driven, the refrigerant and the oil are mixed in a state where the refrigerant and the oil are mixed. It can be collected at the unit (20) side. As a result, oil recovery can be performed more reliably and promptly. Other configurations, operations, and effects are the same as those of the third embodiment. Further, since the pump-down function is the same as in the second embodiment, the liquid-side stop valve (41) is fully closed in step ST66. Another embodiment one

In the above embodiment, the cooling operation is performed as the circulating operation. However, as the normal cycle operation (cooling cycle operation), the reheat dehumidification operation, the inverter rated cooling operation for performing the inverter control, the emergency operation, and the forced operation are performed. Any of the cooling operation may be used.

The reheat dehumidification operation is an operation in which a reheat heat exchanger is provided in the indoor unit (30) in addition to the indoor heat exchanger (31) to perform the dehumidification operation.

If the normal operation cannot be performed due to a sensor error, transmission error between the outdoor unit (20) and the indoor unit (30), etc. This is the operation to keep the operation, and the actuator basically becomes a fixed value. In the case of this emergency operation, frequent start / stop due to low load is eliminated and continuous operation can be reliably performed.

In addition, the above emergency operation is temporarily stopped when a protection circuit such as protection of high pressure is operating. However, the operation will be restarted after the elapse of the specified time. Therefore, it is rare that the compressor (21) stops during the emergency operation which is the circulation operation. However, when the compressor (21) stops during the circulation operation, the time when the compressor (21) is restarted is set as a starting point. Start the time measurement again (for example, see step ST4 and step ST13 in Fig. 4).

The forcible operation is an operation for the purpose of a pump-down operation or a forcible defrosting operation, in which the refrigerant circuit (1A) is fixed, and the actuator also basically has a fixed value. In the case of this forced operation, frequent start / stop due to low load is eliminated, and continuous operation can be reliably performed.

Also, in the above-mentioned forced operation, when the protection circuit such as the protection of the high pressure is operated, the operation is temporarily stopped and the operation is not performed again. It is rare that the forced operation, which is the circulating operation, stops. However, when the compressor (21) stops, the time measurement is performed again starting from the time when the compressor (21) restarts.

Further, in each of the embodiments, the cooling operation (refrigerant recovery operation), which is the recovery operation, is manually stopped, but may be automatically stopped. That is, as shown by the dashed line in FIG. 1, when the compressor (21) has a low-pressure switch (61) on the suction side, when the low-pressure refrigerant pressure falls below the lower limit, the low-pressure switch (61) May be operated to forcibly stop the compressor (21) and stop the recovery operation.

In addition, in the circulation operation of the first step, the smaller the height difference between the liquid pipe (51) and the gas pipe (52) is, the smaller the difference in height is between the liquid pipe (51) and the gas pipe (52). The driving time may be shortened. As a result, in the case of a horizontal pipe or the like, the time for the pre-operation, which is the circulating operation, can be shortened.

In addition, the circulating operation in the first step is such that the shorter the length of the liquid pipe (51) and the gas pipe (52) is, the shorter the length of the liquid pipe (51) and the gas pipe (52) is. May be shortened. As a result, when the pipe length is short, the time for the preliminary operation, which is the circulation operation, can be shortened.

The outdoor unit (20) has an oil separator (60) on the discharge side of the compressor (21) or on the downstream side of the electric expansion valve (24) in the cooling cycle, as shown by the dashed line in FIG. May be provided. When this oil separator (60) is installed, the closing time of the liquid side shut-off valve (41) is limited to before the start of the pump-down operation, which is the recovery operation. No need. That is, since the oil is collected by the oil separator (60), a large amount of oil does not flow out to the liquid pipe (51) at the start of the pump-down operation. As a result, the degree of freedom of the closing timing of the liquid side closing valve (41) is improved.

Further, in each of the embodiments, one indoor unit (30) is provided, but the present invention may include a plurality of indoor units (30).

Further, in each of the embodiments, the liquid side closing valve (41) is provided as the liquid side closing mechanism. However, when the electric expansion valve (24) can be controlled to be fully closed, the liquid side closing mechanism is electrically expanded. It may be constituted by the valve (24) and the liquid-side shut-off valve (41) may be omitted.

In addition, the present invention is not limited to the air conditioner (10), and it is needless to say that the present invention can be applied to various refrigeration devices. Industrial applicability

As described above, the oil recovery method for a refrigerating apparatus according to the present invention is useful for recovering oil from a pipe connecting a heat source unit and a utilization unit, and particularly, an HFC-based refrigerant or an HC-based refrigerant. Suitable for oil recovery when upgrading to a new refrigeration unit using

Claims

The scope of the claims

1. The heat source unit (20) and the utilization unit (30) are connected by pipes (51, 52) and have a refrigerant circuit (1A) for performing a vapor compression refrigeration cycle. An oil recovery method for a refrigeration system that recovers oil to the heat source unit (20) side,

In a normal cycle operation state of the refrigerant circuit (1A) in which the refrigerant condenses in the heat source unit (20), the compressor (21) of the refrigerant circuit (1A) is continuously driven, and the refrigerant circuit (1A) A first step of performing a circulation operation to circulate the refrigerant until a predetermined time elapses,

Subsequent to the first step, a second step of performing a recovery operation of continuously driving the compressor (21) to recover the refrigerant of the refrigerant circuit (1A) together with oil to the heat source unit (20) side. Has

An oil recovery method for a refrigeration apparatus, comprising:

2. The heat source unit (20) and the utilization unit (30) are connected by pipes (51, 52) and have a refrigerant circuit (1A) for performing a vapor compression refrigeration cycle. An oil recovery method for a refrigeration system that recovers oil to the heat source unit (20) side,

When the first step is completed, the compressor (21) is temporarily stopped, and then the compressor (21) is driven to transfer the refrigerant in the refrigerant circuit (1A) together with oil to the heat source unit (20) side. And a second step of performing a recovery operation for recovery.

An oil recovery method for a refrigeration apparatus, comprising:

3. In Claim 1 or 2,

The heat source unit (20) includes a compressor (21), a heat source side heat exchanger (23), and an expansion mechanism (24), and the heat source unit (20) has a liquid side closing valve (41). Through the liquid side While being connected to the gas side pipe (52) via the gas side shutoff valve (42),

In the second step, the recovery operation is started with the liquid-side stop valve (41) closed, and the gas-side stop valve (42) is closed after the completion of the recovery operation.

An oil recovery method for a refrigeration apparatus, comprising:

4. In Claim 1 or 2,

The usage unit (30) includes a usage-side heat exchanger (31) and a usage-side fan (32) having a variable air volume,

In the first step, the utilization side fan (32) is driven at a high air flow with a large air flow to perform a circulation operation.

An oil recovery method for a refrigeration apparatus, comprising:

5. In Claim 1 or 2,

In the first step, the utilization side fan (32) is driven at a low air flow with a small air flow to perform a circulation operation.

An oil recovery method for a refrigeration apparatus, comprising:

6. In Claim 1 or 2,

In the first step, the use side fan (32) is driven at a high air flow with a large air flow in the first half of the circulation operation, and the use side fan (32) is driven at a low air flow with a small air flow in the second half of the circulation operation. Drive

An oil recovery method for a refrigeration apparatus, comprising:

7. In Claim 1 or 2, In the first step, the circulation operation time is shortened as the height difference of the pipes (51, 52) is smaller in accordance with the height difference of the pipes (51, 52).

An oil recovery method for a refrigeration apparatus, comprising:

8. In Claim 1 or 2,

In the first step, the circulation operation time is shortened as the length of the pipe (51, 52) is shorter in accordance with the length of the pipe (51, 52).

An oil recovery method for a refrigeration apparatus, comprising:

9. In Claim 1 or 2,

The heat source unit (20) includes a compressor (21), a heat source side heat exchanger (23), and an expansion mechanism (24).

The heat source unit (20) is provided with an oil separator (60) on the discharge side of the compressor (21) or on the downstream side of the expansion mechanism (24) in the normal cycle.

An oil recovery method for a refrigeration apparatus, comprising: