JP2005180764A - Heat-pump type air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems of an air conditioner wherein, in a reverse-cycle operation in which the localization of refrigerant is predicted from a temperature difference between inside and outside during heating operation to operate the air conditioner for, e.g., air-conditioning for a few minutes after the start of operation, the comfort of air-conditioning could be hindered; and seizure of a compressor could occur because refrigerator oil is not secured inside the compressor during the reverse-cycle operation. <P>SOLUTION: The air conditioner is operated for heating R410A as refrigerant and ester- or ether-based compatible oil as refrigerator oil are combined and caused to flow in a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger and an accumulator are sequentially connected to one another by a refrigerant pipe. When operation of the air conditioner for heating is started, outdoor temperature is detected, and when the outdoor temperature is low, the air conditioner is controlled to operate in an air-conditioning cycle simultaneously with starting of heating. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to securing refrigerating machine oil in a compressor of a heat pump air conditioner that uses R410A as a refrigerant and ester-ether compatible oil as refrigerating machine oil.

  If the operation of the heat pump air conditioner is stopped for a long time, such as at night, liquid refrigerant dissolves and accumulates in the refrigeration oil in the compressor, so-called stagnation occurs, and oil forming occurs when the compressor starts up. The compressor is burned out by being discharged together with the refrigeration oil and refrigerant. In order to prevent the stagnation in the compressor in this case, the stopped compressor is generally heated by a heater.

  In addition, when the heat pump air conditioner is not in operation, the refrigerant condenses and accumulates in the lower room air and outdoor air temperatures. The liquid refrigerant that has accumulated in the outdoor heat exchanger of the machine and accumulated in the outdoor heat exchanger at the start of heating operation flows into the accumulator on the suction side of the compressor, and is sucked into the compressor as refrigerant with low dryness. Therefore, there is a problem that liquid compression and oil forming occur. In order to secure refrigeration oil in the compressor, oil discharged by oil forming or the like is returned to the compressor suction side without being discharged into the refrigeration cycle. The oil separator was mounted on (see, for example, Patent Document 1).

  In addition, there is a case where the accumulation of refrigerant is predicted by comparing the indoor temperature and the outdoor temperature, and the refrigeration cycle is reversed by switching the four-way valve for the number of operation start (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 2003-083629 JP-A-63-129257

  The conventional heat pump type air conditioner has a problem that it is costly. The heat pump air conditioner predicts uneven distribution of the refrigerant based on the temperature difference between the room and the outside, and performs a reverse cycle operation. In the reverse cycle operation, for example, the cooling operation is performed for the number of start times during the heating operation, so that comfort is deteriorated.

When the outdoor temperature is high to some extent and the indoor temperature is higher than that, the refrigerant accumulates on the outside of the room. Since the amount of liquid refrigerant returning to the compressor is small, and the compatibility between the refrigerant and the refrigerating machine oil is reduced in the compressor, the refrigerating machine oil discharged from the compressor is small. Moreover, since the compatibility fall of the refrigerant | coolant and refrigerator oil in an accumulator is also the same, the return property of refrigerator oil is also good.
Therefore, in the case of high outside air, it is not necessary to perform the reverse cycle operation, but if only the refrigerant accumulation is predicted from the temperature difference between the indoor and the outdoor, the reverse cycle operation is performed even when unnecessary. .

  This invention was made in order to solve the above problems, and a first object is to obtain a heat pump air conditioner that can secure refrigeration oil in the compressor at a low cost.

  The second object is to obtain a heat pump type air conditioner that can achieve the above object without impairing comfort.

  The heat pump type air conditioner according to the present invention includes a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, and an accumulator, which are sequentially connected to each other by refrigerant piping. In the case of heating operation with a combination of ester and ether compatible oil, the outdoor temperature is detected at the start of heating operation, and when the outdoor air is at a low outside air temperature, the heating operation is started at the same time as the cooling operation. This is performed for a predetermined time.

  The heat pump type air conditioner of the present invention includes a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, and an accumulator connected in order by a refrigerant pipe, R410A as a refrigerant, and ester as a refrigerator oil.・ In the case of heating operation with a combination of ether-based compatible oil, the outdoor temperature is detected at the start of heating operation, and the cooling operation is performed for a predetermined time at the same time as the heating operation is started when the outdoor air is at a low outside air temperature. Therefore, there is an effect that the oil level of the compressor is secured and the refrigerating machine oil is prevented from being depleted.

Embodiment 1 FIG.
FIG. 1 is a refrigeration cycle diagram of a heat pump type air conditioner according to Embodiment 1 of the present invention, and FIG. 2 is a time chart showing the operation of the heat pump type air conditioner according to Embodiment 1 of the present invention. In the figure, an outdoor unit 7 including a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an expansion valve 4, an accumulator 5 and a connection valve 6 is configured, and an indoor unit 9 including an indoor heat exchanger 8 is provided. A refrigerating cycle is configured which is connected to the connection valve 6 of the outdoor unit 7 and connected by a refrigerant pipe 10 to flow R410A as a refrigerant and ester-ether compatible oil as a refrigerating machine oil. The outdoor unit 7 includes an outdoor temperature sensor 11a that directly measures the outdoor temperature or a pipe temperature detection sensor 11b that detects the pipe temperature of the outdoor heat exchanger 3, and indirectly detects the outdoor temperature. Yes. An outdoor blower 13 for generating an air flow for exchanging heat with the outdoor air in the outdoor heat exchanger 3 is disposed in the outdoor unit 7, and indoor air and the indoor heat exchanger 8 are disposed in the indoor unit 9. An indoor blower 12 that generates an indoor air flow is disposed so as to exchange heat with each other.

  Next, the operation will be described. In the refrigeration cycle configured as described above, the operation shown in the time chart of FIG. 2 is performed during heating when the outdoor air has a low outdoor air temperature. That is, when heating operation is performed at an outdoor temperature below a certain temperature, the outside air temperature is detected by the outside air temperature sensor 11a or the pipe temperature detection sensor 11b simultaneously with the heating operation start t1, and the outside air temperature is, for example, −3 ° C. to −5 ° C. In the following, since the ester oil and the R410A refrigerant are separated into two phases, the operation of the compressor 1 is started so that the refrigerant flows in the direction of the cooling cycle to switch the four-way valve 2 in a state where the evaporation temperature is −3 ° C. . At this time, since the indoor blower 12 is not operated and is stopped, cold air is not blown out. Then, after a predetermined time t1 to t2 from the start of operation, the four-way valve 2 is switched to the heating cycle, the refrigerant flows, and the indoor blower 12 starts to operate simultaneously to blow out hot air into the room.

  As described above, since the operation is performed in the cooling cycle before the operation in the heating cycle, the liquid refrigerant accumulated in the outdoor heat exchanger 3 is decompressed by the expansion valve 4 when the outdoor air is at a low outdoor air temperature. After that, it evaporates in the indoor heat exchanger 8 and flows into the accumulator 5 in a two-phase or dry state. Since the refrigerant sucked into the compressor 1 is also kept at a high dryness, liquid compression and oil forming can be avoided.

  In addition, since the outdoor temperature is detected and the necessity of reverse cycle operation is determined, when the outdoor air is at a high outside air temperature, the reverse cycle operation is not performed when the heating temperature is assumed to be high. Does not spoil the sex.

  FIG. 3 is a characteristic diagram showing the compatibility between the ester oil and the R410A refrigerant. The necessity for the reverse cycle operation is largely due to the compatibility between the ester oil and the R410A refrigerant. For this reason, since ester oil and R410A refrigerant are two-phase separated at −3 ° C. or lower, in a state where the evaporation temperature falls below −3 ° C., the refrigerating machine oil and refrigerant are separated and the oil discharge amount from the compressor 1 increases. . Further, when separation occurs in the accumulator 5, since the refrigeration oil dissolved in the refrigerant is returned to the compressor 1 together with the refrigerant in the accumulator 5, the oil return property is deteriorated. In order to eliminate this deterioration, reverse cycle operation is required at an evaporation temperature of about -3 ° C.

  In the first embodiment described above, the evaporation temperature is predicted from the outside air temperature and the necessity of reverse cycle operation is determined. FIG. 4 shows another heat pump type air conditioner according to the first embodiment of the present invention. In the time chart which shows operation | movement of an apparatus, (a) shows the case where heating start is carried out in a short time from the end of the last driving | operation, (b) has shown the case where heating start is carried out in a long time from the end of the last driving | operation. .

When heating operation is intermittent in a short time shown in FIG. 4A, there is no time for the refrigerant to move to the outdoor heat exchanger, and the compressor body and the refrigeration oil have heat, so that the refrigerant with low dryness Liquid compression and oil forming are unlikely to occur even when sucked into the compressor.
For this reason, reverse cycle operation is not performed at the time of start-up within a certain time from the end of the previous operation.

  The operation will be described with reference to FIG. In the case of (a) where the heating is started in a short time from the end of the previous operation, the operation stop time is counted from the previous operation end t0, and at the same time the heating operation is started at t1 after the short time has elapsed, the four-way valve 2 is heated. Then, the refrigerant flows and the indoor blower 12 starts to operate simultaneously, and blows warm air into the room.

  In the case of (b) where the heating is started for a long time from the end of the previous operation, the operation stop time is counted from the end of the previous operation t0, and at the same time as the heating operation starts at the time t1, the outside air temperature sensor 11a is counted. Alternatively, the outside air temperature is detected by the pipe temperature detection sensor 11b. For example, when the outside air temperature is a low outside air temperature of −3 ° C. to −5 ° C. or less, the ester oil and the R410A refrigerant are separated into two phases, so that the evaporation temperature is In a state where the temperature falls below −3 ° C., the four-way valve 2 is switched to start the operation of the compressor 1 so that the refrigerant flows in the direction of the cooling cycle. At this time, since the indoor blower 12 is not operated and is stopped, cold air is not blown out. Then, after a predetermined time t1 to t2 from the start of operation, the four-way valve 2 is switched to the heating cycle, the refrigerant flows, the indoor blower 12 also starts operating simultaneously, blows warm air into the room, and heats up after the cooling cycle. Start operation in a cycle.

  As described above, since reverse cycle operation is not performed during intermittent operation in a short time, deterioration of comfort can be reduced.

  In the above description of the embodiment, the heating cycle operation is switched immediately after the reverse cycle cooling cycle operation, but FIG. 5 shows still another heat pump type air conditioner according to the first embodiment of the present invention. It is a time chart which shows this operation | movement. After the cooling cycle operation, the compressor is temporarily stopped, and then it is operated in the heating cycle.

  Next, the operation will be described. In the refrigeration cycle configured as described above, the operation shown in the time chart of FIG. 5 is performed during heating when the outdoor air has a low outdoor air temperature. That is, when heating operation is performed at an outdoor temperature below a certain temperature, the outside air temperature is detected by the outside air temperature sensor 11a or the pipe temperature detection sensor 11b simultaneously with the heating operation start t1, and the outside air temperature is, for example, −3 ° C. to −5 ° C. In the following, since the ester oil and the R410A refrigerant are separated into two phases, the operation of the compressor 1 is started so that the refrigerant flows in the direction of the cooling cycle to switch the four-way valve 2 in a state where the evaporation temperature is −3 ° C. . At this time, since the indoor blower 12 is not operated and is stopped, cold air is not blown out. The operation is started and the compressor 1 is once stopped after a lapse of a predetermined time t1 to t1a. Thereafter, the four-way valve 2 is switched to a heating cycle after the lapse of a predetermined time t1a to t2, and simultaneously the refrigerant flows, the indoor fan 12 Also starts to blow warm air into the room.

  As described above, in the operation shown in the time chart of FIG. 5, the main body of the compressor is heated so as not to cause oil forming during the operation of the cooling cycle, and is temporarily stopped to lower the refrigerant pressure inside the compressor. Therefore, the refrigerant contained in the oil warmed during the cooling operation is vaporized by setting it to a temporary saturation pressure or less during the stop period. This makes it difficult for oil forming to occur when the heating operation is performed again.

  Further, in the case of a high-pressure shell type compressor in the operations shown in the time charts of FIGS. 2, 4 and 5 showing the control operation of the heat pump type air conditioner according to Embodiment 1 of the present invention, the refrigerant pressure and When the superheat of the oil temperature that the degree of superheat of the refrigeration oil has the same oil pressure, the effect is more effective because the refrigerant in the oil vaporizes and there is a sudden oil forming It is.

It is a refrigerating cycle figure of the heat pump type air conditioner in Embodiment 1 of this invention. It is a time chart which shows operation | movement of the heat pump type air conditioner by Embodiment 1 of this invention. It is a characteristic view which shows the compatibility of ester oil and R410A refrigerant | coolant of the heat pump type air conditioner by Embodiment 1 of this invention. It is a time chart which shows operation | movement of the other heat pump type air conditioner by Embodiment 1 of this invention. It is a time chart which shows operation | movement of the other heat pump type air conditioner by Embodiment 1 of this invention.

Explanation of symbols

1 compressor,
2 Four-way valve,
3 outdoor heat exchanger,
4 expansion valve,
5 Accumulator,
6 Connection valve,
7 outdoor unit,
8 indoor units,
9 Indoor unit,
10 Refrigerant piping,
11a Outside air temperature sensor,
11b Pipe temperature detection sensor,
12 Indoor blower,
13 outdoor blower,

Claims (4)

Compressor, four-way valve, outdoor heat exchanger, expansion valve, indoor heat exchanger, accumulator are connected in order by refrigerant piping, combined with R410A as refrigerant and ester / ether compatible oil as refrigerant oil A heat pump type that detects the outdoor temperature at the start of the heating operation and performs the cooling cycle operation for a predetermined time simultaneously with the start of the heating operation when the outdoor air is at a low outside air temperature, in the case of performing the heating operation. Air conditioner. The heat pump type air conditioner according to claim 1, wherein the operation stop time from the end of the previous operation is counted, and when the compressor stop time is long, the cooling cycle operation is performed for a predetermined time before the heating operation is started. 3. The cooling operation is performed for a predetermined time simultaneously with the start of the heating operation when the outside air is low, and a time for temporarily stopping the compressor is provided during the heating operation after the cooling cycle operation. Heat pump air conditioner. The heat pump type air conditioner according to any one of claims 1 to 3, wherein the compressor to be mounted is a high-pressure shell type.

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