JP2007178051A - Air conditioner, and control method of air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a compressor without lowering the temperature of refrigerating machine oil even in low loads, while preventing returning of liquid. <P>SOLUTION: When an operation duration time from a thermo-on to a thermo-off is shorter than a prescribed standard operation duration time, an initial opening of an expansion valve in the next thermo-on is determined to be smaller than that in a case when the operation duration time is longer than the standard operation duration time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an air conditioner and an air conditioner control method.

In general, an air conditioner including a compressor, an outdoor heat exchanger, and an indoor heat exchanger is known (see, for example, Patent Document 1).
In such an air conditioner, the opening of the electronic expansion valve at the start of operation (when the thermo is on) is set according to the operating frequency of the compressor, temperature conditions, etc., and the behavior of the refrigerant is stable after a certain period of time has elapsed since the start. After that, it is controlled by the degree of superheat of the evaporator, the refrigerant discharge temperature of the compressor, and the like, improving the heat exchange efficiency and preventing liquid return (so-called liquid back) of the refrigerant to the compressor.
JP 2001-235200 A

However, in the above-described conventional air conditioner, when the operation is stopped (thermo-off state) in a short time after the operation is started under a low load condition, the operation is performed before reaching the appropriate electronic expansion valve opening degree by superheat control or the like. Will stop.
In such a case, if the short-term intermittent operation is repeated, there is a problem that the liquid return to the compressor continues for a long period of time, the state where the refrigerator oil temperature is lowered, and the durability deteriorates.
Therefore, an object of the present invention is to provide an air conditioner and an air conditioner that can improve the durability of the refrigerant compressor without reducing the temperature of the refrigerator oil even at a low load while preventing liquid return. It is to provide a control method.

In order to solve the above problems, an air conditioner including an outdoor unit having an accumulator, a compressor, a four-way valve, and an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger is provided in a refrigerant circuit. And an expansion valve whose opening degree is controlled according to the air conditioning load, and when the operation duration time from the thermo-on to the thermo-off is shorter than a predetermined reference operation continuation time, And an opening degree control unit that sets the initial opening degree of the expansion valve to be smaller than the initial opening degree when the operation duration time is equal to or longer than the reference operation duration time.
According to the above configuration, when the opening degree control unit controls the opening degree of the expansion valve in accordance with the air conditioning load, and the operation duration time is shorter than the predetermined reference operation duration time, the expansion valve at the next thermo-on time The initial opening is set smaller than the initial opening when the operation duration is equal to or longer than the reference operation duration.

In this case, the opening control unit reduces the opening of the expansion valve from the initial opening during the operation duration so that the opening of the expansion valve becomes an opening corresponding to the air conditioning load. You may make it control to the side.
Moreover, you may make it provide the driving | running | working continuation time memory | storage part which memorize | stores the said measured driving | running continuation time.
Further, the reference operation continuation time is set as a time during which the decrease in the oil temperature of the lubricating oil in the compressor falls within a predetermined temperature range when a liquid return occurs in which the liquid refrigerant returns to the compressor. It may be.

In addition, in a control method of an air conditioner including an outdoor unit having an accumulator, a compressor, a four-way valve, an expansion valve, and an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger, the thermo-ON is switched to the thermo-OFF. An operation duration measurement process for measuring an operation duration time to reach the initial opening degree of the expansion valve at the next thermo-on when the operation duration time is shorter than a predetermined reference operation duration time An opening degree control process for setting the opening duration to be smaller than the initial opening degree when the operation continuation time is equal to or longer than the predetermined time.
In this case, in the opening degree control process, the opening degree of the expansion valve is reduced from the initial opening degree during the operation duration so that the opening degree of the expansion valve becomes an opening degree corresponding to the air conditioning load. You may make it control to the side.

  According to the present invention, even when the load is low, it is possible to prevent the refrigerating machine oil temperature from being excessively lowered while preventing the refrigerant from returning, and thus to improve the durability of the compressor.

Next, preferred embodiments of the present invention will be described with reference to the drawings.
Drawing 1 is an explanatory view of the refrigerant circuit of the air harmony device of an embodiment.
The air conditioner 10 includes an outdoor unit 100 and an indoor unit 200 when roughly classified.
The outdoor unit 100 has a gas pipe service valve 300A and a liquid pipe service valve 300B. Each service valve 300 is connected to refrigerant pipes 400A and 400B of the gas pipe and liquid pipe, and each refrigerant pipe 400 is connected to the indoor unit 200. Has been.
The outdoor unit 100 includes an accumulator 1. A sub-accumulator 2 and a compressor 3 are connected to the accumulator 1 in order, and a four-way valve 5 is connected to the compressor 3. In the four-way valve 5, the solid line position indicates the cooling operation switching position, and the broken line position indicates the heating operation switching position. An outdoor heat exchanger 7 is connected to the four-way valve 5, and a receiver tank 9 is connected to the outdoor heat exchanger 7, and a pressure reducing device 10 that acts as a so-called “expansion valve” is connected to the receiver tank 9. The 1st electric expansion valve 11 and the 2nd electric expansion valve 13 which comprise are connected in parallel. The indoor unit 200 is provided with an indoor heat exchanger 15, and the refrigerant pipes 400 are connected to the indoor heat exchanger 15.

In the present embodiment, the outdoor unit 100 is provided with a control unit 100A. The control unit 100A switches the four-way valve 5 to a position corresponding to the cooling operation or the heating operation, and adjusts the opening degrees of the first electric expansion valve 11 and the second electric expansion valve 13 while controlling the compressor 3. Is.
Here, the decompression device 10 is constituted by the first electric expansion valve 11 and the second electric expansion valve 13 in order to increase the opening adjustment range, and it is necessary to reduce the flow amount with a small amount of refrigerant. When the adjustment range is within the opening range of one electric expansion valve, the opening adjustment is performed by the first electric expansion valve 11 which is one electric expansion valve, and the other electric expansion valve is used. The second electric expansion valve 13 is fully closed.
When the opening adjustment range of the first electric expansion valve 11 is exceeded, the first electric expansion valve 11 is fully opened and the opening adjustment is performed by the second electric expansion valve 13.

During the cooling operation, the four-way valve 5 is switched to the solid line position. The high-temperature and high-pressure refrigerant discharged from the compressor 3 passes through the four-way valve 5, the outdoor heat exchanger 7 and the receiver tank 9, reaches the decompression device 10, and further reaches the indoor heat exchanger 15, where it evaporates and becomes gas And returned to the compressor 3 through the accumulator 1 and the sub-accumulator 2.
During the heating operation, the four-way valve 5 is switched to the broken line position. The high-temperature and high-pressure refrigerant discharged from the compressor 3 reaches the indoor heat exchanger 15 from the four-way valve 5, where it condenses and liquefies, passes through the decompression device, the receiver tank 9, and the outdoor heat exchanger 7, and then passes through the four-way valve 5. To the compressor 3 via the accumulator 1 and the sub-accumulator 2.

Next, the operation according to the present invention will be described.
FIG. 2 is an operation flowchart of the embodiment.
FIG. 3 is a timing chart of the embodiment.
For example, when the operation is started at time t1 (step S1), the control unit 100A drives the compressor 3 in the thermo-on state (step S2), and measures the operation continuation time, which is the duration of the thermo-on state ( Step S3).
Thereafter, for example, when the thermo-off state is reached at time t2, the control unit 100A ends the measurement of the operation continuation time and stores the operation continuation time (step S4).

Next, for example, when the controller 100A enters the thermo-on state (re-start) again at time t3 (step S5), the operation continuation time stored before the thermo-on is a predetermined reference operation continuation time (in the embodiment, 12 minutes) or more (step S6).
Here, the reference operation continuation time is set as a time during which the decrease in the oil temperature of the lubricating oil in the compressor 18 falls within a predetermined temperature range even when the liquid refrigerant returns to the compressor 18. .
In the determination in step S6, when the operation continuation time before the thermo-on is equal to or longer than the predetermined reference operation continuation time (step S6; Yes), the total opening degree of the first electric expansion valve 11 and the second electric expansion valve 13 is set. The normal opening degree set in advance is set (step S7), the process proceeds again to step S3, the measurement of the operation duration time is started again, and the same process is performed thereafter.

In the determination of step S6, when the operation continuation time before the thermo-on is less than the predetermined reference operation continuation time (step S6; No), the total opening of the first electric expansion valve 11 and the second electric expansion valve 13, That is, the opening degree of the decompression device 10 is set smaller by a predetermined number of pulses than the normal opening degree set in advance (step S8).
More specifically, in the present embodiment, the initial opening is reduced by 30 pulses from the normal opening, for example, the maximum opening (the electric expansion valves 11 and 13 of the electric expansion valves 11 and 13 as the normal decompression device 10). When the maximum total opening) is 200 pulses and the minimum opening (minimum total opening of the electric expansion valves 11 and 13) is 100 pulses, the decompression device is used when the operation continuation time before the thermo-on is less than a predetermined time. The control is performed with the maximum opening as 10 being 200-30 = 170 pulses and the minimum opening being 100-30 = 70 pulses.

Thereafter, the control unit 100A shifts the process to step S3 again, starts measuring the operation continuation time again, and thereafter performs the same process.
As a result, liquid return to the compressor 3 is reduced, and as shown in FIG. 3, the oil temperature of the lubricating oil in the compressor 3 rises from 0 ° C. in the initial state to 5 ° C. Since the function of the oil can be sufficiently exhibited, the durability and reliability of the compressor 3 can be improved.

As mentioned above, although this invention was demonstrated based on one Embodiment, this invention is not limited to this.
For example, in the above description, the case where the two electric expansion valves 11 and 13 are provided in parallel has been described. However, if the flow rate of the refrigerant can be secured, the number is one, or three or more are provided in parallel if the refrigerant flow rate is insufficient. It is also possible to configure.
In the above description, the superheat degree control is performed as the opening degree control of the electric expansion valve, but the present invention is not limited to this.

It is a circuit diagram which shows one embodiment of this invention. It is an operation | movement flowchart of embodiment. It is a timing chart of an embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Accumulator 3 Compressor 5 Four-way valve 7 Outdoor heat exchanger 9 Receiver tank 10 Pressure reducing device 11 First electric expansion valve 13 Second electric expansion valve 15 Indoor heat exchanger 100 Outdoor unit 100A Control unit 200 Indoor unit 300A Gas pipe service valve 300B Liquid pipe service valve

Claims (6)

In an air conditioner comprising an accumulator, a compressor, a four-way valve, an outdoor unit having an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger,
An expansion valve that is inserted in the refrigerant circuit and whose opening is controlled according to the air conditioning load;
When the operation continuation time from the thermo-on to the thermo-off is shorter than a predetermined reference operation continuation time, the initial opening degree of the expansion valve at the next thermo-on is equal to or more than the reference operation continuation time. An opening degree control unit that is set smaller than the initial opening degree in the case of
An air conditioner comprising: The air conditioner according to claim 1, wherein
The opening degree control unit controls the opening degree of the expansion valve to be smaller than the initial opening degree during the operation duration so that the opening degree of the expansion valve becomes an opening degree corresponding to the air conditioning load. An air conditioner characterized by that. The air conditioner according to claim 1 or 2,
An air conditioning apparatus comprising an operation duration storage unit that stores the measured operation duration. The air conditioner according to any one of claims 1 to 3,
The reference operation continuation time is set as a time during which a decrease in the oil temperature of the lubricating oil in the compressor falls within a predetermined temperature range when a liquid return occurs in which the liquid refrigerant returns to the compressor. Air conditioner. In an air conditioner control method comprising an accumulator, a compressor, a four-way valve, an expansion valve, an outdoor unit having an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger,
An operation duration measurement process for measuring an operation duration time from a thermo-on to a thermo-off,
When the operation continuation time is shorter than a predetermined reference operation continuation time, the initial opening of the expansion valve at the next thermo-on is set smaller than the initial opening when the operation continuation time is the predetermined time or more. Opening control process;
A control method for an air conditioner, comprising: In the control method of the air harmony device according to claim 5,
In the opening degree control process, the opening degree of the expansion valve is controlled to be smaller than the initial opening degree during the operation duration so that the opening degree of the expansion valve becomes an opening degree corresponding to the air conditioning load. A control method for an air conditioner.

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