JP4032993B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-type air conditioner to which two or more indoor units are connected, and particularly relates to prevention of refrigerant leakage from an expansion valve.
[0002]
[Prior art]
Conventionally, the expansion valve control of this type of air conditioner is shown in the flowchart of FIG. Although a certain indoor unit is thermo-off, a state in which another indoor unit is thermo-ON and the compressor is operating is a phenomenon that can occur normally. Here, for example, in the conventional control, when one of the indoor units stops operating in the cooling operation, the refrigerant leakage of the indoor unit is detected by the refrigerant leak detecting means, and the recovery operation of the expansion valve is performed. As this refrigerant leak detection means, a heat exchanger temperature sensor of the indoor heat exchanger is used to detect the refrigerant leak when the heat exchanger temperature becomes lower than a predetermined value. (For example, see Patent Document 1)
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-26429
[Problems to be solved by the invention]
However, in the above-described conventional configuration, it is an effective means to detect the failure of the expansion valve because it detects the circulation of the refrigerant that should not flow to the thermo-OFF indoor unit at the start of the cooling or dehumidifying operation. In spite of being normal, there is a problem that the valve cannot be detected when the valve opens slightly with a pulse shift and a minute amount of refrigerant gas flows. To solve this problem, changing the heat exchanger outlet temperature setting increases the probability of false detection that would be judged abnormal even though it was normal when trying to detect minute refrigerant leaks. There was a limit to detecting degree abnormalities.
[0005]
The present invention solves such a conventional problem. Even though the expansion valve is normal, even if the valve opens slightly with a pulse shift and a minute amount of refrigerant gas flows, an abnormality is detected and the valve is opened. An object of the present invention is to provide an air conditioner that can prevent refrigerant leakage by being completely closed and that can ensure a normal operation state without stopping the compressor.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention is a case where the compressor continues to operate for a predetermined time in the cooling operation or the dehumidifying operation, and when the indoor unit is thermo-off, the indoor unit continues thermo-off for a predetermined time. And the indoor unit heat exchanger outlet temperature is equal to or greater than a predetermined temperature difference compared to the temperature immediately after the thermo-off and the indoor suction temperature of the indoor unit is higher by a predetermined value than immediately after the thermo-off. By performing the initialization of the expansion valve provided on the heat exchanger inlet side of the machine, the expansion valve can be completely closed and refrigerant leakage can be prevented.
[0007]
In addition to the above conditions, when the operating frequency of the compressor after thermo-off is unchanged, the detection accuracy is further improved by initializing the expansion valve provided on the heat exchanger inlet side of the indoor unit Can be made.
[0008]
Furthermore, the expansion valve is initialized after the compressor is stopped, and the influence of the initialization on other indoor units can be prevented.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0010]
(Embodiment 1)
FIG. 1 is a refrigeration cycle diagram showing a first embodiment of the invention. In the figure, the refrigeration cycle includes a variable capacity compressor 1 (hereinafter simply referred to as a compressor), an indoor heat exchanger 2, an indoor blower 3, an indoor electronic expansion valve 4 (hereinafter simply referred to as an expansion valve), a chamber. It comprises an outer heat exchanger 5, an outdoor fan 6, a four-way valve 7 that switches between heating operation and defrosting operation, a thermistor 8 that detects room temperature, and a thermistor 9 that detects the indoor heat exchanger outlet temperature.
[0011]
The operation of the expansion valve opening abnormality detection control will be described with reference to the flowchart of FIG. When two or more indoor units are in a cooling operation or a dehumidifying operation and the compressor 1 is in an operating state for 10 minutes or more (S1), when one of the operating indoor units is thermo-off, The thermistor 8 and 9 detect the suction temperature T0 and the heat exchanger outlet temperature N0 immediately after the thermo-off of the machine, respectively. If the thermo-off continues for 10 minutes, the suction temperature T1 and the heat exchanger outlet temperature T2 at that time are obtained. To detect.
[0012]
Next, the suction temperature and the heat exchanger outlet temperature immediately after 10 minutes have passed after the thermo-off, and the suction temperature after 10 minutes has passed is equal to or higher than the temperature immediately after the thermo-off (S2), and If the heat exchanger outlet temperature after 10 minutes is higher than the temperature immediately after the thermo-off by 5K or more (S3), it is determined that a minute amount of refrigerant is leaking due to an opening abnormality due to a pulse shift of the indoor electronic expansion valve 4, Immediately, the indoor electronic expansion valve 4 is initialized (S4), and the valve is completely closed to prevent the refrigerant from leaking.
[0013]
Since the temperature at the outlet of the heat exchanger is also affected by the change in the suction temperature in the room, erroneous detection of refrigerant leakage can be prevented by using both as the determination parameters.
[0014]
(Embodiment 2)
The operation of the second embodiment will be described with reference to the flowchart of FIG. The difference from the first embodiment is that a change in the frequency of the compressor 1 is taken into account as a condition for initializing the indoor electronic expansion valve 4. That is, the operating frequency of the compressor 1 is monitored after the thermo OFF, and the indoor electronic expansion valve 4 is initialized when the condition of the first embodiment is satisfied and the operating frequency is not changed (S5) (S6). ) Thus, refrigerant leakage can be detected more accurately by eliminating the influence of changes in the heat exchanger outlet temperature and suction temperature due to changes in the compressor frequency.
[0015]
In the first or second embodiment, the initialization is performed immediately after the condition is satisfied. However, after the condition is satisfied, when all the indoor units are thermo-off and the compressor is stopped. You may make it initialize. If initialization is performed while the compressor is in operation, the refrigeration cycle state changes, which may affect the indoor unit in operation, but this can be prevented.
[0016]
The initialization in the above description means that the opening degree of the expansion valve is closed by a predetermined pulse from that point in time, or is once opened with a predetermined pulse and then closed with a pulse set larger than the predetermined pulse. To do.
[0017]
【The invention's effect】
As is clear from the above, the present invention can accurately detect refrigerant leakage from the expansion valve without erroneous detection, and can always ensure a normal operating state of the air conditioner.
[Brief description of the drawings]
FIG. 1 is a refrigeration cycle diagram of an air conditioner of the present invention. FIG. 2 is a control flowchart of an air conditioner according to Embodiment 1 of the present invention. FIG. 3 is a control flowchart of an air conditioner according to Embodiment 2 of the present invention. Explanation of]
DESCRIPTION OF SYMBOLS 1 Capability variable type compressor 2 Indoor side heat exchanger 4 Indoor electronic expansion valve 8 Thermistor 9 Thermistor

Claims (3)

In a multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit, when the compressor continues to operate for a predetermined time during cooling operation or dehumidifying operation, and the indoor unit is thermo-off, When the indoor unit continues the thermo-off for a predetermined time, the heat exchanger outlet temperature of the indoor unit is a predetermined temperature difference or more compared to the temperature immediately after the thermo-off, and the indoor suction temperature of the indoor unit is immediately after the thermo-off An air conditioner characterized by initializing an expansion valve provided on a heat exchanger inlet side of the indoor unit when the predetermined value is higher than the predetermined value. In a multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit, when the compressor continues to operate for a predetermined time during cooling operation or dehumidifying operation, and the indoor unit is thermo-off, When the indoor unit continues the thermo-off for a predetermined time, the heat exchanger outlet temperature of the indoor unit is a predetermined temperature difference or more compared to the temperature immediately after the thermo-off, and the indoor suction temperature of the indoor unit is immediately after the thermo-off An air conditioner characterized by initializing an expansion valve provided on the inlet side of the heat exchanger of the indoor unit when the predetermined frequency is higher than that and the operation frequency of the compressor after the thermo-OFF is not changed Machine. The air conditioner according to claim 1 or 2, wherein the expansion valve is initialized after the compressor is stopped.

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