JP2010255859A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent lowering of oil concentration in a compressor when liquid return to an outdoor unit occurs, and to improve reliability in an operation of a refrigerating machine by preventing failure of the compressor. <P>SOLUTION: This refrigerating device includes two outdoor units 2a, 2b, two distributors 8a, 8b for distributing a refrigerant flowing out from an evaporator 7 to each of the outdoor units, oil amount detecting means of temperature sensors 12a, 12b detecting amounts of oil in the compressors, a return liquid amount adjusting means of flow rate adjustment valves 15a, 15b for adjusting amounts of return liquid to the outdoor units, and a control device 18 for controlling the return liquid amount adjusting means to adjust the amounts of return liquid to the outdoor units on the basis of the amounts of oil in the compressors detected by the oil amount detecting means, before an evaporator fan is started during fan delay control for delaying the start of the evaporator fan with respect to the start of the compressor after the termination of a defrosting operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a combined multi-refrigeration apparatus that uses a plurality of outdoor unit units in combination, and particularly relates to the configuration and operation control of a refrigerant circuit that prevents a decrease in refrigeration machine oil concentration due to liquid return.

An air conditioner that implements a method of appropriately supplying refrigeration oil to a plurality of conventional compressors, a plurality of outdoor units equipped with a compressor, an oil separator, an outdoor heat exchanger, and an accumulator are connected in parallel, Furthermore, a refrigeration cycle is formed by connecting an indoor unit equipped with an expansion valve and an indoor heat exchanger.
The oil circuit returns the refrigerating machine oil separated by the oil separator to the compressor, and stores surplus refrigerating machine oil in an oil container common to all outdoor units and in each accumulator mounted on each outdoor unit.
Each accumulator is provided with an oil return hole, and the refrigeration oil stored in each accumulator is returned to each compressor.
Install a throttling device according to the number of outdoor units between the common oil container and each accumulator so that each accumulator is properly lubricated. (See, for example, Patent Document 1).

Japanese Patent No. 3413044 (first page, FIG. 1)

The conventional air conditioner that implements the method of properly supplying refrigeration oil to multiple compressors is a fan delay that delays the start of the evaporator fan from the start of the compressor in order to prevent hot air blowing at the end of the defrosting operation. Introducing control.
A large amount of liquid refrigerant flows into each outdoor unit during this fan delay control, but especially when there is a variation in the installation angle of the distributor that distributes the refrigerant to each outdoor unit, the outdoor unit has an extremely large amount of liquid return during the fan delay control. A machine appeared.
In addition, in an air conditioner that does not have an oil container and retains all excess oil in an accumulator, when the oil separation efficiency of the oil separator varies, an outdoor unit that has an extremely small amount of oil in the accumulator appears.
As described above, the outdoor unit with a large liquid return amount and a small oil holding amount during the fan delay control has a problem that the oil concentration in the compressor falls below the oil concentration necessary for the compressor operation, which causes a compressor failure. there were.

  The present invention has been made to solve such problems, and when liquid returns to the outdoor unit, the oil concentration in the compressor is avoided and the compressor malfunction is prevented by preventing the compressor failure. An object of the present invention is to obtain a refrigeration apparatus capable of improving the performance.

The refrigerating apparatus of the present invention includes an outdoor unit and an indoor unit, and the outdoor unit compresses and discharges a refrigerant, and oil separation that separates refrigerating machine oil contained in the refrigerant discharged from the compressor. And
A condenser for condensing the refrigerant flowing out from the oil separator; and an accumulator for separating the refrigerant and the refrigerating machine oil, and returning the refrigerating machine oil separated by the oil separator to the compressor. An oil pipe is connected to the suction pipe of the compressor, and the indoor unit includes a decompression unit that decompresses the refrigerant flowing out from the condenser, and an evaporator that evaporates the refrigerant decompressed by the decompression unit. The apparatus comprises a plurality of the outdoor units, a plurality of distributors for distributing the refrigerant flowing out of the evaporator to the outdoor units, and an oil amount detection means for detecting the oil amount of the compressors, The liquid return amount adjusting means for adjusting the liquid return amount to each outdoor unit, and the evaporator fan in the fan delay control for delaying the start of the evaporator fan from the start of the compressor after the completion of the defrosting operation. Before starting up, the amount of oil Knowledge means is constituted by a said Kaeeki amount adjusting means based on the amount of oil each compressor having detected control device for controlling so as to adjust the Kaeeki amount to the outdoor units.

  In the refrigeration apparatus according to the present invention, the control means waits for the start of the evaporator fan during the fan delay control in which the start of the evaporator fan is delayed from the start of the compressor after the completion of the defrosting operation. The return amount adjustment means for adjusting the return amount to each outdoor unit based on the amount of oil in each compressor detected by the oil amount detection means for detecting the oil amount so as to adjust the return amount to each outdoor unit. All outdoor units are controlled during the fan delay control time by controlling and increasing the amount of liquid returned to the outdoor unit that has a large amount of oil and decreasing the amount of liquid returned to the outdoor unit that is less than the specified amount of oil. Thus, it is possible to maintain an appropriate oil concentration required for operating the compressor, to avoid a compressor failure, and to improve the reliability of the refrigerator operation.

The refrigerant circuit figure of the freezing apparatus of Embodiment 1 of this invention. The block diagram which shows the inside of the accumulator of the freezing apparatus. The perspective view which shows the structure of the divider | distributor of the freezing apparatus. Explanatory drawing which shows distribution of the gas and liquid in the outflow port of the divider | distributor of the freezing apparatus. The graph which shows the relationship between the inclination-angle of the divider | distributor of the freezing apparatus, and a liquid distribution ratio. The flowchart which shows the operation | movement in the liquid return operation | movement of the freezing apparatus. The refrigerant circuit figure of the freezing apparatus of Embodiment 2 of this invention. The flowchart which shows the operation | movement in the liquid return operation | movement of the freezing apparatus. The refrigerant circuit figure of the freezing apparatus of Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit of a refrigeration apparatus according to Embodiment 1, FIG. 2 is a configuration diagram showing the inside of an accumulator of the refrigeration apparatus, and FIG. 3 is a perspective view showing a configuration of a distributor of the refrigeration apparatus.
In the figure, the refrigeration apparatus 1 according to Embodiment 1 of the present invention has two outdoor units 2a and 2b.
The two outdoor units 2a and 2b have compressors 3a and 3b, a plurality of oil separators 4a and 4b connected to the discharge portions of the compressors 3a and 3b, and condensers 5a and 5b. ing. The condensers 5a and 5b of the two outdoor units 2a and 2b are sequentially connected to the expansion valve 6, the evaporator 7, the distributors 8a and 8b, and the accumulators 9a and 9b of the two outdoor units 2a and 2b.

These are sequentially connected by piping to form a refrigeration cycle, and refrigerant and refrigeration oil contained therein circulate.
Further, suction pipes 10a and 10b are provided between the accumulators 9a and 9b and the compressors 3a and 3b. These suction pipes 10a and 10b are connected to return oil pipes 11a and 11b for returning the refrigerating machine oil separated from the oil separators 4a and 4b to the compressors 3a and 3b, respectively.
Reference numeral 18 denotes a control device that drives the refrigeration cycle based on whether the power supply of the refrigeration apparatus 1 is turned on or off, and performs control such as opening / closing control of a flow rate adjusting valve and fan delay control based on a detection signal of a temperature sensor described later. .

Next, the flow of the refrigerant in the refrigeration apparatus 1 in the first embodiment will be described.
The high-temperature and high-pressure gas refrigerant discharged from the compressors 3a and 3b of the two outdoor units 2a and 2b is condensed and liquefied by the condensers 5a and 5b through the oil separators 4a and 4b, and then decompressed by the expansion valve 6. After being converted into a two-phase refrigerant and vaporized by the evaporator 7, it is distributed to the outdoor units 2a and 2b by the distributors 8a and 8b, and sucked into the compressors 3a and 3b through the accumulators 9a and 9b for circulation. A refrigeration cycle is formed, and the refrigerant circulates.

Next, the flow of the refrigeration oil in the refrigeration apparatus 1 in the first embodiment will be described.
The oil separation efficiency of the oil separators 4a and 4b is about 90%. That is, about 90% of the refrigerating machine oil discharged together with the gas refrigerant from the compressors 3a and 3b is separated by the oil separators 4a and 4b. The separated refrigerating machine oil is returned to the compressors 3a and 3b from the oil return pipes 11a and 11b through the suction pipes 10a and 10b.

The oil not returned by the oil separators 4a and 4b is distributed to the outdoor units 2a and 2b by the distributors 8a and 8b via the condensers 5a and 5b, the expansion valve 6 and the evaporator 7, and the accumulator 9a, Flows into 9b.
In the accumulators 9a and 9b, the refrigerating machine oil and the gas refrigerant are separated, and the separated oil stays at the bottom of the accumulators 9a and 9b.
As shown in FIG. 2, the oil return hole 11 is installed at a certain height in the accumulators 9a and 9b, and the refrigerating machine oil staying in the accumulators 9a and 9b has an oil surface height that reaches the oil return hole position. Then, it flows into the suction pipes 10a and 10b and is returned to the compressors 3a and 3b.

Next, the influence given by the oil separation efficiency of the oil separators 4a and 4b in the refrigeration apparatus 1 according to the first embodiment will be described.
The oil that has not been separated by the oil separators 4a and 4b travels around in the refrigerant circuit and flows into the outdoor units 2a and 2b again. However, since it takes time to travel around the refrigerant circuit, the oil separator 4a, If the amount of oil that is not separated by 4b is large, the amount of oil in the outdoor units 2a and 2b decreases.
Therefore, the amount of oil in the outdoor units 2a and 2b increases as the oil separation efficiency of the oil separators 4a and 4b increases. Further, when the oil separation efficiency of the oil separators 4a and 4b varies, the amount of oil flowing out from the outdoor units 2a and 2b varies.
Therefore, the smaller the variation in the oil separation efficiency of the oil separators 4a and 4b, the more equal the amount of oil in the outdoor units 2a and 2b. However, the variation in the oil separation efficiency is indeterminate and the inside of the outdoor units 2a and 2b. The amount of oil is different in each refrigeration system.

Next, the influence given by the initial amount of oil charged in the refrigeration apparatus 1 according to Embodiment 1 will be described.
If the initial amount of enclosed oil is increased, the amount of oil in the refrigerant circuit increases, so that the oil concentration during the liquid return operation in which the liquid refrigerant flows into the outdoor units 2a and 2b can be improved.
However, when the initial amount of the enclosed oil is increased and the amount of oil in the compressors 3a and 3b is increased, the input to the compressors 3a and 3b is increased due to the oil compression, and the operation efficiency of the refrigeration apparatus is reduced.

Next, the influence of the amount of oil in the compressors 3a and 3b in the refrigeration apparatus 1 according to Embodiment 1 will be described.
The refrigerating machine oil and the gas refrigerant flowing into the compressors 3a and 3b from the suction pipes 10a and 10b are separated, the separated oil stays at the bottom of the compressors 3a and 3b, and the gas refrigerant flows into the compression chamber and is compressed. Is done. The oil staying at the bottom of the compressors 3a and 3b is used as lubricating oil necessary for compressor operation.
However, when the amount of oil staying at the bottoms of the compressors 3a and 3b exceeds a predetermined amount, the amount of oil that is compressed together with the gas refrigerant increases rapidly. At this time, the input to the compressors 3a and 3b increases due to oil compression, and as the input increases, the amount of heat generated by the motor that drives the compressors 3a and 3b increases, and the oil temperature staying in the compressors 3a and 3b. Also rises in temperature.
That is, the surface temperature of the compressors 3a and 3b is also raised. At this time, the amount of oil in the compressors 3a and 3b can be detected by the inputs of the compressors 3a and 3b or the surface temperature of the bottom where the oil stays.
When the amount of oil is less than a predetermined amount, the input or surface temperature does not change even if the amount of oil changes, but when the oil is depleted, the surface temperature decreases, causing a compressor failure. If the amount of oil is less than a predetermined amount of oil and does not run out, for example, 1 L or more, it is an appropriate amount of oil.

Next, the operation | movement which maintains the oil density | concentration in the compressor appropriately in the liquid return operation | movement in the refrigerating apparatus 1 in this Embodiment 1 is demonstrated based on the flowchart of FIG.
The liquid return operation mainly occurs at the time of fan delay control for delaying the start-up of the evaporator fan (not shown) when returning from the defrosting operation. During operation of the refrigeration apparatus 1, frost adheres to the evaporator 7, and the air volume of the evaporator fan decreases.
Therefore, a defrosting operation is introduced in which frost is melted by heating the heater at predetermined time intervals. During the defrosting operation, the compressors 3a and 3b and the evaporator fan are stopped.

Since the evaporator is warm immediately after the defrosting operation is completed and the normal operation is restored, warm air is blown into the room when the evaporator fan is activated. In order to avoid this, the compressors 3a and 3b are first started after the defrosting operation is finished (step S1).
Fan delay control is introduced to delay the start-up timing of the evaporator fan from the start-up of the compressors 3a, 3b, and the evaporator fan is driven after a predetermined time, for example, 5 minutes to 10 minutes immediately after returning to normal operation. To start.
At the time of this fan delay control, since the refrigerant is not completely evaporated by the evaporator 7, a liquid return operation in which the liquid refrigerant returns in an uneven manner flows into the outdoor units 2a and 2b (step S2).
In the fan delay control, it is necessary to cool the evaporator 7 to such an extent that the hot air can be prevented from being blown out within a predetermined time. Therefore, the minimum necessary refrigerant flow rate flowing into the evaporator 7 is maintained.
The liquid return operation other than at the time of the fan delay control may be a case where the valve does not close due to a failure of the expansion valve 6.

During the liquid return operation, a large amount of liquid refrigerant flows into the accumulators 9a and 9b, and the oil concentration rapidly decreases. When the amount of liquid in the accumulators 9a and 9b overflows, it flows into the compressors 3a and 3b, so that the oil concentration in the compressors 3a and 3b also decreases (step S3).
In particular, when the amount of oil in each outdoor unit 2a, 2b is uneven, for example, when returning to the outdoor unit 2a with a small amount of oil, or when the liquid return amount is uneven between each outdoor unit 2a, 2b, When the outdoor unit 2a is present, the oil concentration in the compressor 3a is temporarily lower than the oil concentration in the compressor 3b immediately after the liquid return operation is started.
At this time, the proper oil concentration particularly required for operating the compressor 3a cannot be maintained, causing a compressor failure.

Such a deviation in the amount of liquid returned to the outdoor units 2a and 2b mainly depends on the inclination of the distributors 8a and 8b. FIG. 4 shows the distribution of gas and liquid at the outlet of the distributor of the refrigeration apparatus, and the graph of FIG. 5 shows the relationship between the inclination angle of the distributor of the refrigeration apparatus and the liquid distribution ratio.
In the Y-shaped distributors 8a and 8b having one inflow port and two outflow ports, when there is an inclination, as shown in FIG. The outlet is occupied by a low density gas refrigerant.
The distributors 8a and 8b should be installed horizontally if they are evenly distributed, but it is assumed that the installation angles of the distributors 8a and 8b vary and tilt to the left or right. However, it is uncertain to which direction it is inclined, and the unevenness of the returned liquid amount is different in each refrigeration apparatus.

  During the liquid return operation, the refrigerant is also in a two-phase state at the discharge portions of the compressors 3a and 3b. At this time, the refrigerant flowing into the oil separators 4a and 4b is also in a two-phase state. However, when the refrigerant is in a two-phase state, the oil separation efficiency is generally greatly reduced. If the oil separation efficiency is reduced, the amount of oil returned to the compressors 3a and 3b is reduced, and the oil concentration is further reduced.

The refrigerating apparatus 1 according to the first embodiment includes an oil amount detection unit that detects the amount of oil in each of the compressors 3a and 3b, specifically, a temperature sensor 12a that measures the temperature of the bottom surface of the compressors 3a and 3b, 12b, or an ammeter (not shown) or a wattmeter (not shown) as a power source for the compressors 3a and 3b.
As described above, when the amount of oil to the compressors 3a and 3b is equal to or greater than a predetermined amount, the power or current of the power source of the compressors 3a and 3b increases, and accordingly, the heat generation amount of the driving motor increases. The oil temperature staying in the compressors 3a and 3b is also raised.
That is, the surface temperature of the compressors 3a and 3b is also raised. Therefore, if the power or current of the power source of the compressors 3a and 3b or the bottom surface temperature of the compressors 3a and 3b is measured, the power in the compressors 3a and 3b can be determined from the power value, current value, or bottom surface temperature. It can be detected that the amount of oil is greater than or equal to a predetermined amount (step S4), and the amount of oil at that time can be detected.

When it is detected that the amount of oil in the compressor 3a or 3b is equal to or greater than a predetermined amount, the return amount is concentrated on the outdoor unit by the return amount adjusting means.
Note that an outdoor unit having a large amount of oil equal to or greater than a predetermined amount is detected in advance by the temperature sensors 12a and 12b, which are oil amount detection means, before the start of the defrosting operation.

Here, as a specific example of the liquid return amount adjusting means, there are flow rate adjusting valves 15a and 15b which can control the flow rate installed between the distributors 8a and 8b and the outdoor units 2a and 2b. For example, if the opening degree of the flow rate adjusting valve 15a provided at the inlet of the outdoor unit 2a is made larger than the opening degree of the flow rate adjusting valve 15b provided at the inlet of the outdoor unit 2b, the valve opening ratio is increased outdoor. The liquid return amount concentrates on the machine 2a.
However, since the fan delay control needs to cool the evaporator 7 so as to prevent the hot air blowout within a predetermined time, the valve opening degree is maintained so as to maintain the minimum necessary refrigerant flow rate flowing into the evaporator 7. Set the ratio.
As another specific example of the liquid return amount adjusting means, if the compressor operating capacity is controlled, that is, if the compressor 3a is operated at a capacity larger than the compressor 3b, the compressor 3a is supplied by the capacity ratio. The amount of returned liquid is concentrated.

In this way, the liquid is concentrated on the outdoor unit 2a or 2b that holds a large amount of oil, that is, the amount of liquid returned is increased (step S5), and the amount of liquid returned to the outdoor unit having an oil amount equal to or less than the other predetermined amount. (Step S6), it is possible to maintain an appropriate oil concentration required for operating the compressors in all the outdoor units during the fan delay control time (step S7). Thus, a highly reliable refrigeration apparatus can be obtained.
Appropriate oil required for operating the compressors in all the outdoor units within a predetermined period of time, for example, 5 minutes to 10 minutes after starting the fan delay control as described above and starting the compressors 3a and 3b Control for maintaining the concentration is performed, and after a predetermined time has elapsed (step S8), driving of the evaporator fan is started (step S9), and the normal operation is resumed.

Embodiment 2. FIG.
FIG. 7 is a refrigerant circuit diagram of the refrigeration apparatus according to Embodiment 2 of the present invention.
In the second embodiment, instead of the temperature sensors 12a and 12b which are oil amount detection means of the compressors 3a and 3b in the refrigeration apparatus 1 of the first embodiment, the suction pipes 10a to the compressors 3a and 3b, A temperature sensor (first temperature sensor) 13a, 13b is installed on the upstream side of the connecting portion of each oil return pipe 11a, 11b on 10b, and a temperature sensor (second temperature sensor) 14a, 14b is installed on the downstream side. Is.
In the second embodiment, the same configurations as those of the first embodiment are denoted by the same reference numerals, and the description of the overlapping configurations is omitted.

  The specific fan delay control in the refrigeration apparatus 1 according to the second embodiment delays the start timing of the evaporator fan from the start of the compressors 3a and 3b after the defrosting operation, as in the first embodiment. . At this time, the liquid return operation is performed, and a large amount of liquid refrigerant is returned to the outdoor units 2a and 2b. Appears. For example, when the distributor 8a is inclined and the returned liquid concentrates on the outdoor unit 2a, the accumulator 9a quickly overflows and the liquid flows out to the suction pipe 10a.

If the operation is continued in this state, the oil concentration in the compressor 3a becomes thin, and the specified oil concentration necessary for the operation of the compressor 3a cannot be maintained.
Therefore, in order to detect that the accumulator 9a has overflowed, a temperature sensor 13a and a temperature sensor 14a are provided on the upstream side of the connecting portion of the suction pipe 10a and the upper oil return pipe 11a.

When the accumulator 9a has not overflowed, the gas refrigerant is flowing through the suction pipe 10a. The oil separated by the oil separator 4a flows into the suction pipe 10a through the oil return pipe 11a. When the amount of oil separated by the oil separator 4a is small, a gas refrigerant may flow through the oil return pipe 11a.
The oil or gas refrigerant flowing in from the discharge part of the compressor 3a through the oil separator 4a is hot, and when it flows into the suction pipe 10a, the temperature of the gas refrigerant in the suction pipe 10a is raised.
Since the gas refrigerant has a small density, the temperature change is large, and when the accumulator 9a does not overflow and the gas refrigerant is circulating in the suction pipe 10a, there is always a significant difference between the temperatures measured by the temperature sensor 13a and the temperature sensor 14a. .

However, when the accumulator 9a overflows, the liquid refrigerant flows through the suction pipe 10a. Since the liquid refrigerant has a high density, the temperature change is small even when oil flows in, and there is no difference between the temperatures measured by the temperature sensor 13a and the temperature sensor 14a.
Thus, the overflow of the accumulator 9a can be detected by the presence or absence of the temperature difference measured by the temperature sensor 13a and the temperature sensor 14a.

Next, the operation | movement which maintains the oil density | concentration in a compressor appropriately in the liquid return operation | movement in the refrigerating apparatus 1 in this Embodiment 2 is demonstrated based on the flowchart of FIG.
About the operation | movement which maintains the oil density | concentration in the compressor in a liquid return operation appropriately, from step S11 in this Embodiment 2 to S13, the step S1-accumulator which starts a compressor after completion | finish of the defrost operation of the said Embodiment 1 Since the liquid refrigerant that has flowed into 9a and 9b flows into the compressors 3a and 3b and is similar to step S3 in which the oil concentration varies, description of steps S11 to S13 is omitted.
In step S13, the liquid refrigerant that has flowed into the accumulators 9a and 9b flows into the compressors 3a and 3b, and the oil concentration varies.
When the temperature difference measured by the temperature sensor 13a and the temperature sensor 14a disappears and an overflow of the accumulator 9a is detected (step S14), the liquid return amount to the outdoor unit 2a is decreased by the liquid return amount adjusting means (step S15). ).
Specific examples of the liquid return amount adjusting means are flow rate adjusting valves 15a and 15b that can control the flow rate installed between the distributors 8a and 8b and the outdoor units 2a and 2b, as in the first embodiment. .

If the opening degree of the flow rate adjusting valve 15a provided at the inlet of the outdoor unit 2a is made smaller than the opening degree of the flow rate adjusting valve 15b provided at the inlet of the outdoor unit 2b, the outdoor unit 2a is increased by the valve opening ratio. The amount of returned liquid can be reduced.
However, since the fan delay control needs to cool the evaporator 7 so as to prevent the hot air blowout within a predetermined time, the valve opening degree is maintained so as to maintain the minimum necessary refrigerant flow rate flowing into the evaporator 7. Set the ratio.
As another specific example of the liquid return amount adjusting means, if the compressor operating capacity is controlled, that is, if the compressor 3a is operated with a capacity smaller than the compressor 3b, the capacity ratio of the compressor 3a is increased. The amount of returned liquid can be reduced.

In this way, the amount of liquid returned to the outdoor unit 2a or 2b where the accumulator 9a or 9b has overflowed can be reduced (step S15), and the amount of liquid returned to the other non-overflowing outdoor unit can be increased. (Step S16), it is possible to maintain an appropriate oil concentration required for operating the compressors in all outdoor units during the fan delay control time (Step S17), and to avoid the compressor failure and to be reliable. A highly refrigerating apparatus can be obtained.
Appropriate oil required for operating the compressors in all the outdoor units within a predetermined period of time, for example, 5 minutes to 10 minutes after starting the fan delay control as described above and starting the compressors 3a and 3b Control for maintaining the concentration is performed, and after a predetermined time has elapsed (step S18), the evaporator fan is started to be driven (step S19), and the normal operation is resumed.

Embodiment 3 FIG.
FIG. 9 is a refrigerant circuit diagram of the refrigeration apparatus according to Embodiment 3 of the present invention.
In the third embodiment, each accumulator is replaced with the temperature sensors (first temperature sensors) 13a and 13b and the temperature sensors (second temperature sensors) 14a and 14b on the downstream side in the refrigeration apparatus 1 according to the second embodiment. The oil flow pipes 16a and 16b having the open / close valves 17a and 17b for circulating oil between the oil flow pipes 9a and 9b are installed, and the open / close valves 17a and 17b are opened to allow the oil flow pipes 16a and 16b to communicate with the compressor 3a, The oil adjustment control for operating 3b with different capacities is performed.
In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description of the overlapping components is omitted.

The oil adjustment control of the refrigeration apparatus 1 according to the third embodiment will be described.
When the oil separation efficiency of each oil separator 4a, 4b varies, the amount of oil in each accumulator 9a, 9b is biased. If the variation is large, accumulators that run out of oil also appear, so it is necessary to correct the uneven oil quantity.
Therefore, oil circulation pipes 16a and 16b for circulating oil between the accumulators 9a and 9b are installed, and the oil is moved from the accumulator having a large amount of oil to the accumulator having a small amount of oil. In order to move the oil through the oil circulation pipes 16a and 16b, it is necessary to generate a pressure difference between the accumulators.

In the oil adjustment control of the refrigerating apparatus 1 according to the third embodiment, the on-off valves 17a and 17b are opened to connect the oil circulation pipes 16a and 16b, and at the same time, the compressors 3a and 3b are operated with different capacities. A pressure difference is generated between the accumulators due to a pressure loss difference caused by a difference in the flow rate of the refrigerant flowing into 2a and 2b.
When the compressor is operated at a large capacity, the pressure loss increases and the pressure inside the accumulator is low.When the compressor is operated at a small capacity, the pressure loss decreases and the pressure inside the accumulator becomes high. Move from outdoor unit to large capacity outdoor unit.
Thereby, oil moves in the oil circulation pipes 16a and 16b. The oil head difference due to the difference in oil level in each accumulator is very small compared to the pressure loss difference caused by the difference in refrigerant flow rate, and therefore does not affect the oil movement.

Since the variation in the oil separation efficiency of each oil separator 4a, 4b is uncertain, the deviation of the oil amount in each accumulator 9a, 9b is also uncertain.
Therefore, in order to prevent oil outflow from a small amount of accumulator, for example, the end portions of the oil circulation pipes 16a and 16b are installed at a height of 2L of the accumulators 9a and 9b, and the amount of oil in the accumulator is 2L or less. Prevents oil spills when operating at low capacity.
Such oil adjustment control is performed at predetermined time intervals, and the outdoor unit for large capacity operation and the outdoor unit for small capacity operation are alternately switched, and the oil is transferred from the accumulator with a large amount of oil to the accumulator with a small amount of oil. To prevent oil depletion in the accumulator.

Next, specific fan delay control in the refrigeration apparatus 1 according to Embodiment 3 will be described.
As described above, the fan delay control delays the startup timing of the evaporator fan from the startup of the compressors 3a and 3b after the defrosting operation is completed. At this time, since the liquid return operation is performed, the liquid return amount to the outdoor unit with a small oil amount is reduced by the liquid return amount adjusting means.
The outdoor unit that has been subjected to the oil adjustment control and has been operated with a small capacity at the end of the operation causes the oil to flow out. Therefore, the outdoor unit with a small amount of oil is detected as an outdoor unit operated with a small capacity at the end of the oil adjustment control immediately before the start of the fan delay control. Whether the outdoor unit is operated with a small capacity can be known because the control device 18 performs control by itself in the oil adjustment control.

As another specific example of the liquid return amount adjusting means, there are flow rate adjusting valves 15a and 15b which can control the flow rate installed between the distributors 8a and 8b and the outdoor units 2a and 2b.
For example, an outdoor unit operated with a small capacity is an outdoor unit having the smallest amount of oil because oil is allowed to flow out. When the outdoor unit is the outdoor unit 2a, a flow control valve provided at the inlet of the outdoor unit 2a If the opening degree of 15a is made smaller than the opening degree of the flow control valve 15b provided at the inlet of the outdoor unit 2b, the liquid return amount of the outdoor unit 2a is decreased by the valve opening ratio.
However, since the fan delay control needs to cool the evaporator 7 so as to prevent the hot air blowout within a predetermined time, the valve opening degree is maintained so as to maintain the minimum necessary refrigerant flow rate flowing into the evaporator 7. Set the ratio.
As another specific example of the liquid return amount adjusting means, if the compressor operating capacity is controlled, that is, if the compressor 3a is operated with a capacity smaller than the compressor 3b, the capacity ratio of the compressor 3a is increased. The amount of returned liquid can be reduced.

  By such fan delay control, the amount of liquid returned to the outdoor unit with a small amount of oil can be reduced, and the amount of liquid returned to the outdoor unit with the other multiple oil amount or proper oil amount can be increased. It is possible to maintain an appropriate oil concentration required for operating the compressors in all outdoor units during the fan delay control time, and to obtain a highly reliable refrigeration apparatus by avoiding compressor failure. it can.

Any of the operation operations of the first to third embodiments is the same as long as the refrigerant and the refrigerating machine oil are compatible.
Therefore, HFC refrigerants, or mixed refrigerants or HC refrigerants thereof, and mixed refrigerants thereof, or natural refrigerants such as CO2 and water are used as refrigerants, and oils compatible with them as oil, such as HFC refrigerants, for example, In the case of ester oil, mineral oil in the case of HC refrigerant, and PAG oil in the case of CO2, the same operation is performed.

  DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus, 2a, 2b Outdoor unit, 3a, 3b Compressor, 4a, 4b Oil separator, 5a, 5b Condenser, 6 Expansion valve, 7 Evaporator, 8a, 8b Distributor, 9a, 9b Accumulator, 10a, 10b Suction pipe, 11a, 11b Oil return pipe, 11 Oil return hole, 12a, 12b Temperature sensor, 13a, 13b First temperature sensor, 14a, 14b Second temperature sensor, 15a, 15b Flow rate adjusting valve, 16a, 16b Oil Distribution pipe, 17a, 17b On-off valve, 18 Control device.

Claims (6)

An outdoor unit and an indoor unit,
The outdoor unit is
A compressor that compresses and discharges the refrigerant;
An oil separator for separating refrigerating machine oil contained in the refrigerant discharged from the compressor;
A condenser for condensing refrigerant flowing out of the oil separator;
An accumulator for separating the refrigerant and the refrigerating machine oil,
Connecting a return oil pipe for returning the refrigerating machine oil separated by the oil separator to the compressor, to a suction pipe of the compressor;
The indoor unit is
Decompression means for decompressing the refrigerant flowing out of the condenser;
In a refrigeration apparatus comprising an evaporator for evaporating the refrigerant decompressed by the decompression means,
A plurality of outdoor units,
A plurality of distributors for distributing the refrigerant flowing out of the evaporator to the outdoor units;
An oil amount detecting means for detecting the oil amount of each compressor;
A return amount adjusting means for adjusting the return amount to each outdoor unit;
Each of the compressors detected by the oil amount detection means during the fan delay control in which the start of the evaporator fan is delayed from the start of the compressor after the defrosting operation is started until the evaporator fan is started. A control device for controlling the return amount adjusting means to adjust the return amount to each outdoor unit based on the amount of oil;
A refrigeration apparatus comprising:   2. The refrigeration apparatus according to claim 1, wherein the oil amount detection means is a temperature sensor that detects a surface temperature of the compressor, or an ammeter or wattmeter that detects input current or input power of the compressor. . An outdoor unit and an indoor unit,
The outdoor unit is
A compressor that compresses and discharges the refrigerant;
An oil separator for separating refrigerating machine oil contained in the refrigerant discharged from the compressor;
A condenser for condensing refrigerant flowing out of the oil separator;
An accumulator for separating the refrigerant and the refrigerating machine oil,
A return pipe for returning the refrigeration oil separated by the oil separator to the compressor is connected to a suction pipe between the compressor and the accumulator;
The indoor unit is
Decompression means for decompressing the refrigerant flowing out of the condenser;
In a refrigeration apparatus comprising an evaporator for evaporating the refrigerant decompressed by the decompression means,
A plurality of outdoor units,
A plurality of distributors for distributing the refrigerant flowing out of the evaporator to the outdoor unit;
A first temperature sensor provided in the suction pipe on the upstream side of the junction between the suction pipes and the oil return pipes;
A second temperature sensor provided in the suction pipe on the downstream side of the junction between the suction pipes and the oil return pipes;
A return amount adjusting means for adjusting the return amount to each outdoor unit;
The first temperature sensor and the second temperature between the start of the compressor after the defrosting operation and the start of the evaporator fan during the fan delay control for delaying the start of the evaporator fan. A control device for controlling the liquid return amount adjusting means to adjust the liquid return amount to each outdoor unit according to the difference in temperature measured by the sensor;
A refrigeration apparatus comprising: An outdoor unit and an indoor unit,
The outdoor unit is
A compressor that compresses and discharges the refrigerant;
An oil separator for separating refrigerating machine oil contained in the refrigerant discharged from the compressor;
A condenser for condensing refrigerant flowing out of the oil separator;
An accumulator for separating the refrigerant and the refrigerating machine oil,
Connecting a return oil pipe for returning the refrigerating machine oil separated by the oil separator to the compressor, to a suction pipe of the compressor;
The indoor unit is
Decompression means for decompressing the refrigerant flowing out of the condenser;
In a refrigeration apparatus comprising an evaporator for evaporating the refrigerant decompressed by the decompression means,
A plurality of outdoor units,
A plurality of distributors for distributing the refrigerant flowing out of the evaporator to the outdoor units;
An oil circulation pipe having an on-off valve for circulating oil between the accumulators;
A return amount adjusting means for adjusting the return amount to each outdoor unit;
Opening the release valve and communicating the oil circulation pipe at the same time performing oil amount adjustment control to operate each compressor with a different operating capacity,
Furthermore, each of the compressors is operated according to different operating capacities until the evaporator fan is started during the fan delay control that delays the start of the evaporator fan from the start of the compressor after the defrosting operation is finished. A control device for controlling the liquid return amount adjusting means to adjust the liquid return amount to each outdoor unit;
A refrigeration apparatus comprising:   The said liquid return amount adjustment means is a flow control valve provided between each said distributor and the said accumulator controlled by the said control apparatus, The Claim 1 characterized by the above-mentioned. Refrigeration equipment.   The refrigeration apparatus according to any one of claims 1 to 4, wherein the liquid return amount adjustment means is a control of an operating capacity of the compressor by the control device.

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