JP2012198020A - Air conditioning system and oil return control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioning system and an oil return control method of the air conditioning system which can carry out oil return at a suitable timing.SOLUTION: When a power supply of the air conditioning system is turned on and electric power from a commercial power supply is supplied to a microcomputer inside an outdoor controller via a power supply circuit (step SC1 of Fig.8), the microcomputer determines whether a compressor is started (step SC2). When the compressor is started, an oil return operation is performed with a lapse of a fixed period of time after the start of the compressor. Further, the microcomputer determines whether an instruction for operation stop is output from a remote control, etc. (step SC8), and when the instruction for the operation stop is output, the oil return operation is performed (step SC9).

Description

  The present invention relates to an air conditioning system, and more particularly, to an oil return control method for an air conditioning system that returns lubricating oil in a refrigerant circuit to a compressor.

Conventionally, in an air conditioner, it is known to perform a so-called oil return operation in which oil accumulated in the refrigeration circuit is forcibly recovered by a compressor (see, for example, Patent Document 1 and Patent Document 2).
This oil return operation is performed, for example, when the operation time reaches a predetermined time or when the total amount of oil discharged from the compressor reaches a predetermined value.

Japanese Patent No. 3750145 Japanese Patent No. 3191719

By the way, when the oil return operation is performed when the total amount of oil discharged from the compressor reaches a predetermined value, for example, the amount of oil discharged from the compressor is detected every predetermined period, and the detected value is integrated. By doing so, a method to grasp the total oil amount can be considered.
However, when the power to the air conditioner is turned off, this accumulated oil amount is reset, so when the power is turned on again, the actual total oil amount cannot be grasped, and the oil return operation is properly performed. There was a problem that it could not be done at the right time.
In particular, in the case of a multi-type air conditioning system in which one outdoor unit and a plurality of indoor units are connected by the same refrigerant pipe, trial operation is repeatedly performed when the air conditioner is installed. In such a case, every time the power is turned off, the error between the actual total oil amount and the total oil amount grasped by the air conditioner increases, and there is a possibility that the timing of oil return will be greatly shifted. .

  The present invention has been made to solve the above problem, and an object thereof is to provide an air conditioning system and an oil return control method for an air conditioning system that can perform oil return at an appropriate timing.

In order to solve the above problems, the present invention employs the following means.
A first aspect of the present invention is an air conditioning system that performs oil return control for returning lubricating oil that has flowed into the refrigerant circuit to the compressor by holding and operating the lubricating oil in the compressor, and the compressor is activated. In this case, the oil return operation is performed after a certain time has elapsed since the start of the compressor.

  According to such a configuration, when the compressor is activated, the oil return operation is performed after a certain time has elapsed since the activation, so that the shortage of oil in the compressor can be solved.

  According to a second aspect of the present invention, there is provided an air conditioning system that performs oil return control for returning the lubricating oil that has flowed into the refrigerant circuit to the compressor by holding the lubricating oil in the compressor and operating the instruction, and for stopping the operation. Is an air conditioning system that performs an oil return operation and then stops the operation.

  According to such a configuration, when the operation is stopped, the oil return operation is always performed before the operation is stopped, and then the operation is stopped. Therefore, the total amount of discharged oil at the start of the operation can always be kept constant. it can.

  According to a third aspect of the present invention, there is provided an oil return control method for an air conditioning system that performs an oil return control for returning the lubricant that has flowed into the refrigerant circuit to the compressor by holding and operating the lubricant in the compressor, This is an oil return control method for an air conditioning system that performs an oil return operation after a predetermined time has elapsed since the power was turned on when the power is turned on.

  According to a fourth aspect of the present invention, there is provided an oil return control method for an air conditioning system that performs an oil return control for returning the lubricant that has flowed into the refrigerant circuit to the compressor by holding and operating the lubricant in the compressor, This is an oil return control method for an air conditioning system that performs an oil return operation when an instruction to stop the operation is input, and then stops the operation.

  Another aspect as a reference example of the present invention is an air-conditioning system that performs oil return control for holding the lubricating oil in the compressor and returning the lubricating oil that has flowed into the refrigerant circuit by operation to the compressor. When the power is turned off, the total oil discharge means determined by the oil amount integration means when the oil amount integration means for obtaining the total discharge oil amount by integrating the oil amount discharged from the compressor, the nonvolatile memory, and the power is turned off. An air conditioning system comprising memory writing means for writing an oil amount into the non-volatile memory.

According to such a configuration, the total oil amount discharged is obtained by integrating the oil amount discharged from the compressor by the oil amount integrating means, and the oil return is performed at a predetermined timing based on the total oil amount discharged. Driving will be carried out.
Further, when the power is turned off, the total discharge oil amount obtained by the oil amount integration means is written in the nonvolatile memory, so that the total discharge oil amount when the power is turned off is held. . Thereby, when the power is turned on next time, the total amount of discharged oil written in the non-volatile memory is read, so that the current amount of discharged oil can be grasped when the power is turned off last time.

  In the air conditioning system, when the power is turned on, the air conditioning system further includes a memory reading unit that reads the latest total discharge oil amount from the non-volatile memory, and the oil amount integration unit reads the total discharge amount read from the non-volatile memory. The integration may be started from the oil amount.

  As described above, when the power is turned on, the latest discharge total oil amount is read from the non-volatile memory, and integration of the discharge oil amount is started based on the total discharge oil amount. It is possible to reduce an error between the total oil amount and the discharged total oil amount obtained by the oil amount integrating means.

  The air conditioning system further includes a power failure detection means for detecting a power failure, and when the power failure is detected by the power failure detection means, the memory writing means indicates the total discharge oil amount obtained by the oil amount integration means in the nonvolatile manner. It is also possible to write to the volatile memory.

  According to such a configuration, when a power failure is detected by the power failure detection means, the total discharge oil amount obtained by the oil amount integration means is written in the non-volatile memory. Will be held. Thus, when the power is turned on after a power failure, the total discharge oil amount immediately before the power failure, that is, the current total discharge oil amount can be grasped by reading the total discharge oil amount from the nonvolatile memory. .

  Another aspect as a reference example of the present invention is an air-conditioning system that performs oil return control for holding the lubricating oil in the compressor and returning the lubricating oil that has flowed into the refrigerant circuit by operation to the compressor. An oil amount integrating means for obtaining a total discharge oil amount by integrating the oil amount discharged from the compressor, a non-volatile memory, and the discharge total oil amount obtained by the oil amount integrating means are periodically It is an air conditioning system provided with the memory writing means which writes in a property memory.

According to such a configuration, since the total discharge oil amount obtained by the oil amount integrating means is periodically written to the nonvolatile memory, the total discharge oil at that time when the power is turned off or when a power failure occurs The amount will be held in non-volatile memory. Thereby, when the power is turned on, the total discharge oil amount at that time can be grasped by reading the total discharge oil amount from the nonvolatile memory.
The write cycle of the total discharge oil amount to the nonvolatile memory may be determined according to, for example, the number of data rewrites guaranteed in the nonvolatile memory and the guaranteed operation period of the air conditioning system. For example, when the number of data rewrites in the nonvolatile memory is 1 million times and the guaranteed operation period of the air conditioning system is 10 hours / day, the written total oil amount is written 1 million times. / 30,000 hours = 33 times / hour, in other words, writing can be performed at a cycle of 2 minutes at the fastest. Therefore, an arbitrary period of 2 minutes or more may be determined according to the design, and writing may be performed at that period. For example, writing may be performed at time intervals of 5 to 10 minutes.

  Another aspect as a reference example of the present invention is an oil return control method for an air conditioning system that performs oil return control for holding lubricant oil in the compressor and returning the lubricant oil that has flowed out of the refrigerant circuit to the compressor by operation. A process of obtaining a total discharge oil quantity by integrating the amount of oil discharged from the compressor, and a process of writing the total discharge oil quantity in a nonvolatile memory when the power is turned off. This is an oil return control method for an air conditioning system.

  Another aspect as a reference example of the present invention is an oil return control method for an air conditioning system that performs oil return control for holding lubricant oil in the compressor and returning the lubricant oil that has flowed out of the refrigerant circuit to the compressor by operation. An oil return for an air conditioning system comprising: a process for obtaining a total discharge oil quantity by integrating the oil quantity discharged from the compressor; and a process for periodically writing the total discharge oil quantity into a nonvolatile memory. It is a control method.

The oil return control method for the air conditioning system is particularly suitable for use in a multi-type air conditioning system in which one outdoor unit and a plurality of indoor units are connected by the same refrigerant pipe.
Moreover, the said aspect can be utilized combining in the possible range.

  According to the present invention, there is an effect that oil return can be performed at an appropriate timing.

It is a refrigerant circuit figure showing the refrigerating cycle of the air-conditioning system concerning a 1st embodiment of the present invention. It is the figure which showed the schematic internal structure and peripheral circuit of the outdoor control apparatus shown in FIG. It is the flowchart which showed the process sequence of the oil return control method of the air conditioning system which concerns on the 1st Embodiment of this invention. It is the figure which showed an example of transition of the discharge total oil amount at the time of performing the oil return control method which concerns on the 1st Embodiment of this invention. It is the figure which showed the outline internal structure and peripheral circuit of the outdoor control apparatus for implement | achieving the oil return control method of the air conditioning system which concerns on the 2nd Embodiment of this invention. It is the flowchart which showed the process sequence of the oil return control method of the air conditioning system which concerns on the 2nd Embodiment of this invention. It is the figure which showed the outline internal structure and peripheral circuit of the outdoor control apparatus for implement | achieving the oil return control method of the air conditioning system which concerns on the 3rd Embodiment of this invention. It is the flowchart which showed the process sequence of the oil return control method of the air conditioning system which concerns on the 3rd Embodiment of this invention. It is the figure which showed an example of transition of the discharge total oil amount at the time of performing the oil return control method which concerns on the 3rd Embodiment of this invention.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a refrigerant circuit diagram showing a refrigeration cycle of the air conditioning system according to the first embodiment of the present invention.
The air conditioning system according to this embodiment includes an outdoor unit 1a and a plurality of indoor units 2a to 2c. The outdoor unit 1a and the indoor units 2a to 2c are connected by the same refrigerant pipe 11a. Specifically, the outdoor unit refrigerant circuit unit 4a included in the outdoor unit 1a and the indoor unit refrigerant circuit units 5a-5c included in the indoor units 2a-2c are connected by the same refrigerant pipe 11a.

  In FIG. 1, the outdoor unit 1 a includes an outdoor control device 9 and an outdoor unit refrigerant circuit unit 4 a, and each of the indoor units 2 a to 2 c (hereinafter, all the indoor units 2 a to 2 c are simply indicated by a symbol “ In the case where each indoor unit is identified by “2”, the reference numerals “2a”, “2b”, and “2c” are attached. The same applies to each component included in each indoor unit). A control device 10 and an indoor unit refrigerant circuit unit 5 are provided. The air conditioning system having such a configuration includes a compressor 12 that compresses the refrigerant, a condenser 13 that condenses the compressed refrigerant, a receiver 15 that stores the condensed liquid refrigerant, and a receiver 15. An expansion valve 17 that expands the liquid refrigerant, and a heat exchanger 19 that evaporates the liquid refrigerant expanded by the expansion valve 17.

Among the above configurations, the compressor 12, the condenser 13, and the liquid receiver 15 are provided in the outdoor unit refrigerant circuit unit 4a that configures the outdoor unit 1a. On the other hand, the heat exchanger 19 and the expansion valve 17 are respectively provided in the indoor unit refrigerant circuit unit 5 constituting the indoor unit 2.
In addition, in this embodiment, although the compressor 12 and the liquid receiver 15 are provided in the outdoor unit refrigerant circuit part 4a, these do not necessarily need to be provided in the outdoor unit refrigerant circuit part 4a.

  The compressor 12 compresses the low-temperature and low-pressure gas refrigerant from the heat exchanger 19 to produce a high-temperature and high-pressure gas refrigerant, and a scroll compressor is preferably used. A low pressure sensor 51 is provided in the refrigerant system on the suction side of the compressor 12, and a high pressure sensor 52 is provided in the refrigerant system on the discharge side. The outputs of these pressure sensors 51 and 52 are output to the outdoor control device 9 of the outdoor unit 1a. The refrigerant pipe is provided with a bypass pipe that bypasses the compressor 12. This bypass pipe operates when the differential pressure between the pressure sensors 51 and 52 exceeds a predetermined value, and is a pressure control valve for maintaining the suction side pressure and the discharge side pressure of the compressor 12 at a substantially constant pressure. 60 is provided. The opening degree of the pressure control valve 60 is adjusted by the outdoor control device 9. Furthermore, a temperature sensor 27 is provided in the refrigerant pipe on the discharge side of the compressor 12, and this output is sent to the outdoor control device 9.

The condenser 13 is a heat exchanger that condenses the high-temperature and high-pressure gas refrigerant from the compressor 12 by exchanging heat with air that is outside air. An outdoor fan 13a is disposed opposite to the condenser 13, and heat exchange is promoted by forced convection by air sent by the outdoor fan 13a. The outdoor fan 13a is started and stopped by the outdoor control device 9, or the rotational speed is controlled.
A temperature sensor 23 is provided in the refrigerant pipe on the upstream side of the condenser 13, and a temperature sensor 24 is provided on the downstream side. Outputs of these temperature sensors 23 and 24 are sent to the outdoor control device 9. The outdoor unit refrigerant circuit section 4 a is provided with an outdoor temperature sensor 26, and this output is sent to the outdoor control device 9.

  The liquid receiver 15 is a container in which the liquid refrigerant condensed in the condenser 13 is stored. At a normal outside air temperature that is not a low outside air temperature, surplus refrigerant that has been surplus in the system is stored. A liquid receiver temperature sensor 28 is provided on the side wall of the liquid receiver 15. The output of the liquid receiver temperature sensor 28 is sent to the outdoor control device 9, and the liquid level position in the liquid receiver 15 is estimated based on this output value.

Next, the internal configuration of the indoor unit refrigerant circuit unit 5 will be described.
The expansion valve 17 expands the liquid refrigerant supplied from the outdoor unit refrigerant circuit section 4a side in an approximately isenthalpy manner. The expansion valve 17 is preferably an electronic expansion valve (EEV), and the opening degree is controlled by the indoor control device 10. The amount of circulating refrigerant circulating in the system is determined by the opening of the expansion valve 17. Moreover, it is controlled by the indoor control device 10 so that a predetermined degree of superheat (for example, 3 deg) is maintained.

  The heat exchanger 19 is a heat exchanger that evaporates the low-pressure liquid refrigerant from the expansion valve 17 by exchanging heat with room air. A temperature sensor 21 is provided in the refrigerant pipe on the upstream side of the heat exchanger 19, and a temperature sensor 22 is provided in the refrigerant pipe on the downstream side. Outputs of these temperature sensors 21 and 22 are sent to the indoor control device 10. The degree of superheat is determined by the temperature obtained by subtracting the temperature sensor 21 from the temperature sensor 22.

An indoor fan 29 is disposed opposite to the heat exchanger 19, and heat exchange is promoted by forced convection by air sent by the indoor fan 29. The indoor fan 29 is started and stopped by the indoor control device 10 or the rotational speed is controlled. Reference numeral 70 denotes a pressure sensor.
A heat exchanger temperature sensor 25 is provided at an intermediate position of the heat exchanger 19 in the indoor unit refrigerant circuit unit 5, and its output is sent to the indoor control device 10.

The outdoor control device 9 includes, for example, a microcomputer, a volatile memory, a non-volatile memory, and the like, and is based on various commands sent from the indoor control device 10, an indoor intake air temperature, a set indoor temperature, and the like. The refrigeration capacity is adjusted by controlling the start / stop of the engine or the number of rotations thereof, the indoor air temperature is controlled, and the oil return control described later is performed.
Moreover, the indoor control apparatus 10 contains a microcomputer etc., for example, and each controls the indoor unit refrigerant circuit part 5 based on each sensor in the indoor unit refrigerant circuit part 5, and the data from the outdoor control apparatus 9.

An air conditioning system having such a configuration operates as follows, for example, at a normal outside temperature such as in summer.
The high-temperature and high-pressure gas refrigerant compressed by the compressor 12 is condensed in the condenser 13 to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is partly surplus refrigerant stored in the liquid receiver 15 and then sent to the expansion valve 17 where it is depressurized in a substantially equal enthalpy manner. The low-pressure liquid refrigerant evaporates in the heat exchanger 19 and takes heat from the indoor air sent by the indoor fan 29. The air that has been deprived of heat and cooled is sent into the room, and cooling is realized by lowering the room temperature. The low-pressure gas refrigerant evaporated in the heat exchanger 19 is guided to the suction side of the compressor 12 and is compressed again.

  Here, the outdoor unit refrigerant circuit unit 4a and the indoor unit refrigerant circuit units 5a to 5c constituting the air conditioning system are not only the single cooling unit described above, but also a single cooling / heating unit and a multiple cooling / heating unit that perform heating operation by heat pump operation. The multi-combination multi-cooling / heating machine, the cooling / heating-free multi-air conditioner, and the combination cooling / heating-free multi-air conditioner may be combined as a plurality of systems.

Next, an oil return control method in the air conditioning system shown in FIG. 1 will be described.
The oil return control method according to the present embodiment is realized by, for example, the outdoor control device 9 illustrated in FIG.
FIG. 2 is a diagram showing a schematic internal configuration and peripheral circuits of the outdoor control device 9.
As described above, the outdoor control device 9 includes the microcomputer 100 and the nonvolatile memory 101. The outdoor control device 9 is connected to a commercial power supply 103 via a power supply circuit 102. The power supply circuit 102 converts AC power from the commercial power supply 103 into power suitable for the outdoor control device 9 and supplies the converted power to the outdoor control device 9. Further, the power supply circuit 102 can supply power to the outdoor control device 9 in a predetermined time when the power supply from the commercial power supply 103 is interrupted due to a power failure or the like.

  Further, a power failure detection circuit 104 is provided as a peripheral circuit of the outdoor control device 9. The power failure detection circuit 104 monitors the power supplied from the commercial power source 103 to the power circuit 102 and detects a power failure. Various known methods can be applied to the power failure detection. For example, the power failure detection circuit 104 detects a zero cross point of AC power at any time, determines that a power failure has occurred when the zero cross point cannot be detected, and outputs a power failure detection signal to the outdoor control device 9. Alternatively, the power failure detection circuit 104 monitors the power after full-wave rectification in the power supply circuit 103, determines that a power failure has occurred when the waveform cannot be detected, and outputs a power failure detection signal to the outdoor control device 9. To do.

  The microcomputer 100 in the outdoor control device 9 predetermines an oil amount integrating function (oil amount integrating means) for determining the total amount of oil discharged by integrating the amount of oil discharged from the compressor 12, and the calculated total amount of discharged oil. A memory writing function (memory writing means) for writing to the nonvolatile memory 101 at the timing of the above, and a memory reading function (memory reading means) for reading the oil amount from the nonvolatile memory 101.

In an air conditioning system having such a configuration, oil return control is performed according to the following procedure.
First, when the power of the air conditioning system is turned on and the power from the commercial power supply 103 is supplied to the microcomputer 100 in the outdoor control device 9 via the power supply circuit 102 (step SA1 in FIG. 3), the microcomputer 100 is turned on. Is determined for the first time (step SA2). In the first time, the oil amount set in advance as an initial value is set as the integration start value (step SA3). On the other hand, when the microcomputer 100 determines that the power is not turned on for the first time, the microcomputer 100 reads the latest total discharge oil amount from the non-volatile memory 101, and sets this total discharge oil amount as an integration start value (step SA4).

  Subsequently, the microcomputer 100 determines whether or not the compressor 12 is activated (step SA5). In other words, the microcomputer 100 determines whether or not the air conditioning operation is being performed and determines that the compressor 12 is activated. In this case, the amount of oil discharged from the compressor 12 is detected, and the total amount of discharged oil is updated by adding the detected amount of oil to the total amount of discharged oil (step SA6).

Subsequently, the microcomputer 100 determines whether or not the total discharged oil amount exceeds a preset specified amount (step SA7), and if it exceeds, performs an oil return operation (step SA8). Thereby, the oil staying in the refrigerant circuit returns to the compressor 12, and the shortage of oil in the compressor 12 is solved.
Next, the microcomputer 100 determines whether or not the power is turned off (step SA9). If the power is not turned off, the microcomputer 100 returns to step SA5 and repeats the processes after step SA5. On the other hand, if the microcomputer 100 determines in step SA9 that the power supply has been turned off, the current discharge total oil amount is written in the nonvolatile memory 101 (step SA10), and the oil return control process is terminated.

Next, an example of the transition of the total discharge oil amount when the oil return control method according to the present embodiment is executed will be described with reference to FIG. First, when the power is turned off at time t1, the total discharge oil amount at this time is stored in the nonvolatile memory 101. When the power is turned on at time t2, the microcomputer 100 reads the latest discharge total oil amount from the nonvolatile memory 101, and starts integrating the discharge oil amount using the total discharge oil amount as an integration start value. When the total discharge oil amount reaches the specified value at time t3, the microcomputer 100 starts the oil return operation. As a result, the lubricating oil staying in the refrigerant circuit is returned to the compressor 12, thereby reducing the total discharge oil amount. When the oil return operation ends at time t4, the microcomputer 100 resumes the air conditioning operation. Thereby, the lubricating oil is discharged from the compressor 12, whereby the total discharged oil amount gradually increases. When the power is turned off at time t5, the microcomputer 100 writes the total discharge oil amount at this time in the nonvolatile memory 101, and ends the oil return control.
When the power is turned on again at time t6, the microcomputer 100 reads the latest total discharge oil amount from the nonvolatile memory 101, sets this total discharge oil amount as an integration start value, and sets the discharge oil amount. Accumulate.

  As described above, according to the present embodiment, when the power is turned off, the total discharge oil amount at that time is written in the nonvolatile memory 101, so that the total discharge oil amount is maintained until the next power-on. can do. As a result, when the power is turned on, the latest discharge total oil amount is read from the non-volatile memory 101, so that the total discharge oil amount at that time can be grasped. Then, by setting this total discharge oil amount as the integration start value and integrating the discharge oil amount, the total discharge oil amount can be accurately grasped, and the oil return operation can be performed at an appropriate timing. .

In the present embodiment, when the power is turned off, the total discharge oil amount at that time is written in the nonvolatile memory 101. In addition, a power failure detection signal is output from the power failure detection circuit 104. When input, the total discharge oil amount at that time may be written in the nonvolatile memory 101.
Moreover, in this embodiment, although the oil return control method in a multi type air conditioning system was demonstrated, this oil return method is not restricted to the said multi type air conditioning system, One outdoor unit and one indoor unit It can also be applied to an air conditioning system consisting of
Moreover, in this embodiment, although the outdoor control apparatus implement | achieved the oil return control method, it may replace with this and one of indoor control apparatuses may implement | achieve.

[Second Embodiment]
Next, an air conditioning system and an oil return control method for the air conditioning system according to the second embodiment of the present invention will be described with reference to FIGS. 5 and 6.
The air conditioning system and the oil return control method for the air conditioning system according to the present embodiment are realized by the outdoor control device 9 as in the first embodiment described above.
FIG. 5 is a diagram showing a peripheral circuit of the outdoor control device 9 according to the present embodiment.
As shown in FIG. 5, the outdoor control device 9 includes a microcomputer 100 and a nonvolatile memory 101. The outdoor control device 9 is connected to a commercial power supply 103 via a power supply circuit 102.

In an air conditioning system having such a configuration, oil return control is executed according to the following procedure.
First, when the power supply of the air conditioning system is turned on and power from the commercial power supply 103 is supplied to the microcomputer 100 in the outdoor control device 9 via the power supply circuit 102 (step SB1 in FIG. 6), the microcomputer 100 is turned on. Is determined for the first time (step SB2), and in the case of the first time, an oil amount set in advance as an initial value is set as an integration start value (step SB3). On the other hand, when the microcomputer 100 determines that the power is not turned on for the first time, the microcomputer 100 reads the latest total discharge oil amount from the non-volatile memory 101, and sets this total discharge oil amount as an integration start value (step SB4).
Subsequently, the microcomputer 100 determines whether or not the compressor 12 is activated (step SB5), and if it is determined that the compressor 12 is activated, the amount of oil discharged from the compressor 12 is determined. By detecting and adding the detected oil amount to the total discharge oil amount, the total discharge oil amount is updated and the total discharge oil amount is periodically written in the nonvolatile memory 101 (steps SB6 and SB7).

Subsequently, the microcomputer 100 determines whether or not the total discharged oil amount exceeds a preset specified amount (step SB8), and if it exceeds, performs an oil return operation (step SB9). As a result, the oil staying in the refrigerant circuit returns to the compressor 12 and the shortage of oil in the compressor 12 is resolved.
Next, the microcomputer 100 determines whether or not the power is turned off (step SB10). If the power is not turned off, the microcomputer 100 returns to the above-described step SB5 and repeats the processing after the step SB5. On the other hand, in step SB9, when the microcomputer 100 determines that the power is turned off, the microcomputer 100 ends the oil return control.

  As described above, according to the air conditioning system and the oil return control method of the air conditioning system according to the present embodiment, the total amount of discharged oil is periodically written in the nonvolatile memory 101. Even when a power failure occurs, the current total discharge oil amount can be held until the next power-on. Thereby, when the power is turned on, it is always possible to grasp the total amount of oil discharged at that time.

[Third Embodiment]
Next, an air conditioning system and an oil return control method for the air conditioning system according to the third embodiment of the present invention will be described with reference to FIGS.
The air conditioning system and its oil return control method according to the present embodiment are realized by the outdoor control device 9 as in the first and second embodiments described above.
The outdoor control device 9 according to the present embodiment is different from the outdoor control device 9 according to the second embodiment shown in FIG. 5 in that the non-volatile memory 101 is not provided as shown in FIG. .
Hereinafter, the air conditioning system and its oil return control method according to the present embodiment will be described mainly with respect to differences from the air conditioning system and the oil return control method according to the second embodiment.

First, when the power supply of the air conditioning system is turned on and power from the commercial power supply 103 is supplied to the microcomputer 100 in the outdoor control device 9 via the power supply circuit 102 (step SC1 in FIG. 8), the microcomputer 100 12 is activated (step SC2). If it is determined that the compressor 12 is activated, it is determined whether or not the power is turned on for the first time (step SC3).
As a result, when the power is turned on for the first time, the oil return operation is performed after a predetermined time T2 has elapsed since the power was turned on (steps SC4 and SC5). On the other hand, if the power is not turned on for the first time, the microcomputer 100 performs an oil return operation after a predetermined time T1 has elapsed since the power was turned on (steps SC6 and SC7). Subsequently, the microcomputer 100 determines whether or not an operation stop instruction has been issued from the remote controller or the like (step SC8). If no operation stop instruction has been issued, the microcomputer 100 returns to step SC2 and repeats the subsequent processing. .
On the other hand, if the operation stop instruction is issued from the remote controller or the like, the oil return operation is performed (step SC9), and then it is determined whether the power is turned off (step SC10). As a result, if the power is not turned off, the process returns to the above-described step SC2, and the subsequent processing is repeated. On the other hand, if the power is turned off, this process is terminated.

Next, an example of transition of the total discharge oil amount when the oil return control process according to the present embodiment is executed will be described with reference to FIG. Here, a case where the power is not turned on for the first time will be described.
First, when the power is turned on at time t1 and the compressor 12 is started, the oil return operation is performed at time t2 after a predetermined period T1 has elapsed since the start of the compressor 12. Thereby, the lubricating oil staying in the refrigerant circuit is returned to the compressor 12, and the total amount of discharged oil gradually decreases. At time t3, when the total discharge oil amount reaches a predetermined value, the microcomputer 100 ends the oil return operation and restarts the air conditioning operation. Thereby, the lubricating oil is discharged from the compressor 12, whereby the total discharged oil amount gradually increases.
At time t4, when the total discharge oil amount reaches the specified value, the microcomputer 100 starts the oil return operation. Thereby, the lubricating oil staying in the refrigerant circuit is returned to the compressor 12, and the total amount of discharged oil gradually decreases. When the total discharge oil amount reaches a predetermined value at time t5, the microcomputer 100 ends the oil return operation and restarts the air conditioning operation.
Thereby, the lubricating oil is discharged from the compressor 12, whereby the total discharged oil amount gradually increases. At time t6, when an operation stop instruction is issued from the remote controller or the like, the microcomputer performs an oil return operation. Thereby, the lubricating oil staying in the refrigerant circuit is returned to the compressor 12, and the total amount of discharged oil gradually decreases. At time t7, when the total discharge oil amount reaches a predetermined value, the microcomputer 100 ends the oil return operation and stops the operation of the compressor 12.

  As described above, according to the air conditioning system and the oil return control method of the air conditioning system according to the present embodiment, when the power is turned on, the oil return operation is performed after a predetermined time has elapsed since the power was turned on. Therefore, the lubricating oil in the compressor 12 can be made a sufficient amount, and the total discharge oil amount can be set to a predetermined value. Furthermore, when the operation is stopped, the oil return operation is always performed before the operation is stopped, so that the total discharge oil amount in the compressor 12 can be kept constant at the start of the next operation.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

9 Outdoor control device 11a Refrigerant piping 12 Compressor 70 Pressure sensor 100 Microcomputer 101 Non-volatile memory 102 Power supply circuit 103 Commercial power supply 104 Power failure detection circuit

Claims (6)

An air conditioning system that performs oil return control to return the lubricating oil that has flowed out to the refrigerant circuit by holding and operating the lubricating oil in the compressor to the compressor,
An air conditioning system that performs an oil return operation after a certain period of time has elapsed since the start of the compressor when the compressor is started. When the compressor is started, it is determined whether or not the current power on is the first time,
If the power was not turned on for the first time, the oil return operation was carried out after the first predetermined time had elapsed since the power was turned on. If the power was turned on for the first time, the second predetermined period had passed since the power was turned on. The air conditioning system according to claim 1, wherein the oil return operation is performed later.   The air conditioning system according to claim 1 or 2, wherein when an instruction to stop the operation is input, the oil return operation is performed, and then the operation is stopped. An air conditioning system that performs oil return control to return the lubricating oil that has flowed out to the refrigerant circuit by holding and operating the lubricating oil in the compressor to the compressor,
An air conditioning system that performs an oil return operation when an instruction to stop the operation is input, and then stops the operation. An oil return control method for an air conditioning system that performs oil return control to return the lubricant that has flowed into the refrigerant circuit by holding and operating the lubricant in the compressor to the compressor,
An oil return control method for an air conditioning system in which an oil return operation is performed after a predetermined time has elapsed since the start of the compressor when the compressor is started. An oil return control method for an air conditioning system that performs oil return control to return the lubricant that has flowed into the refrigerant circuit by holding and operating the lubricant in the compressor to the compressor,
An oil return control method for an air conditioning system that performs an oil return operation when an instruction to stop the operation is input, and then stops the operation.

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