JPH01107070A - Method of detecting shortage of refrigerant for air conditioner - Google Patents

Abstract

PURPOSE: To securely detect lack of the encapsulated amount of a refrigerant without permitting mistaken operation even under any operation conditions, and issuing alarming and interrupting operation, and hence previously preventing a burning accident of a compressor by detecting a difference between refrigerant temperatures at an inlet and an outlet of a heat exchanger. CONSTITUTION: On a liquid refrigerant assembly piping 7 of a heat exchanger 6 that actuates as an evaporator upon cooling operation and as a condenser upon heating operation there is provided a thermistor 9, and on a gas refrigerant assembly piping 8 provided a thermistor 10, and further inside an air suction inlet there is provided a thermistor. When a temperature difference between an inlet refrigerant and an outlet refrigerant of the heat exchanger 6 becomes larger than a set value, when a temperature difference of the outlet refrigerant and heat exchanger suction air at the air suction inlet 4 is smaller than a predetermined value, and when a temperature difference between a temperature difference between the suction air and blowoff air is smaller than a set value, an alarming signal is issued from a controller 12 to light an alarming lamp or interrupt the operation. Hereby, a burning accident of a compressor 13 is previously prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a protection device for an air conditioner, and is particularly intended to prevent burnout accidents of the compressor when the amount of refrigerant is insufficient or when the refrigerant leaks. How to detect refrigerant shortage in air conditioners.

[Conventional technology]

In the conventional technology, as described in Kokai Technical Report No. 85-374, a discharge gas thermostat is activated when the discharge gas temperature reaches a certain value to detect a shortage in the amount of refrigerant charged. However, this method does not take into consideration the need to correct changes in discharge gas temperature under various operating conditions.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, the temperature of the discharged gas for detecting an insufficient amount of refrigerant is fixed at one point. Therefore, even though the discharge gas temperature is actually different under load conditions, for example, overload operation and low load operation, even if the same amount of refrigerant is charged, this point has not been taken into consideration, and there has been a problem of malfunction.

Furthermore, if the amount of refrigerant enclosed is extremely small, the temperature of the discharged gas does not rise, so the discharged gas thermostat does not operate and has a problem in that it cannot perform its protective function.

An object of the present invention is to reliably detect an insufficient amount of refrigerant and issue an alarm or stop operation without malfunctioning under any operating conditions.

[Means for solving problems]

The above object is achieved by detecting the temperature difference in the refrigerant temperature at the inlet and outlet of the heat exchanger, which does not change much due to operating conditions but changes greatly due to insufficient amount of refrigerant.

[Effect]

(1) The temperature difference between the refrigerant at the inlet and outlet of the evaporator has the characteristic of increasing when the amount of refrigerant charged is insufficient, so this is detected and when it is greater than a certain value, it is taken as a signal that the amount of refrigerant charged is insufficient.

(2) The difference between the temperature of the refrigerant at the evaporator outlet and the temperature of the evaporator intake air has the characteristic of decreasing when the amount of refrigerant charged is insufficient. It is used as a signal of shortage.

(3) The temperature difference between the refrigerant at the inlet and outlet of the condenser has a characteristic of increasing when the amount of refrigerant charged is insufficient, so this is detected and when it is greater than a certain value, it is taken as a signal that the amount of refrigerant charged is insufficient.

(4) The difference between the temperature of the refrigerant at the condenser outlet and the temperature of the condenser suction air has the characteristic of decreasing when the amount of refrigerant charged is insufficient, so this is detected and if it is smaller than a certain value, the amount of refrigerant charged is It is used as a signal of shortage.

(6) The temperature difference between the air inlet and outlet of the evaporator has a characteristic of decreasing when the amount of refrigerant charged is insufficient, so this is detected and when it is smaller than a certain value, it is taken as a signal that the amount of refrigerant charged is insufficient.

(6) The temperature difference between the air inlet and outlet of the condenser has a characteristic of decreasing when the amount of refrigerant charged is insufficient, so this is detected and when it is smaller than a certain value, it is taken as a signal that the amount of refrigerant charged is insufficient.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 2 is a block diagram of an air-cooled heat pump type bubble cage air conditioner, in which an indoor unit 1 and an outdoor unit 2 are connected by a refrigerant pipe 3 to form one refrigeration cycle. FIG. 1 is an internal structural diagram of the indoor unit 1 shown in FIG. 2. The heat exchanger 6 acts as an evaporator during cooling operation and as a condenser during heating operation. The thermistor A9 is connected to the liquid refrigerant collecting pipe 7 of the heat exchanger 6. ``-Mister B I Q is installed in close contact with the gas refrigerant collecting pipe 8 to detect the temperature of the refrigerant.

The thermistor C1l is installed inside the air suction port 4 to detect the temperature of the intake air. Furthermore, Sirkista A,
B and C are connected to the control device 12, and during cooling operation, thermistor C temperature - thermistor B smoke level ≦6℃, and during heating operation, the thermistor human temperature - thermistor C temperature≦10'C are satisfied. If so, the control device 12 issues an alarm signal, lights up an alarm lamp, or stops the operation. Figure 3 shows the amount of refrigerant sealed in the refrigeration cycle (
The difference between the evaporator intake air temperature and the evaporator outlet gas refrigerant temperature during cooling operation (temperature difference E
) 15, and the difference between the condenser outlet liquid refrigerant temperature and the condenser suction air temperature during heating operation (temperature difference C) 16. If the amount of refrigerant charged is small, the above temperature difference is small. It shows what will happen. In Fig. 2, if refrigerant leaks from the refrigerant pipe 3 etc. during cooling operation and the refrigerant in the refrigeration cycle decreases, the difference between the evaporator intake air temperature and the evaporator outlet gas refrigerant temperature will be shown as temperature difference E15 in Fig. 3. (Temperature difference E)
15 becomes smaller as the amount of refrigerant decreases, and when the amount of refrigerant charged decreases to the normal amount of 60 inches, this temperature difference becomes 6°C and an alarm signal is generated by the action of thermistor C11 and thermistor B10 in FIG. 1 and the control device 12. The warning lamp will light up or the operation will stop.

Even during heating operation, thermistor A9 and thermistor C1
1 and the control device 120 perform similar functions.

〔Effect of the invention〕

According to the present invention, an insufficient amount of refrigerant can be reliably detected and an alarm can be issued or the operation can be stopped without malfunctioning under any operating conditions, which has the effect of preventing compressor burnout accidents. There is.

[Brief explanation of the drawing]

FIG. 1 shows an indoor unit of an air conditioner according to an embodiment of the present invention, where (a) is a front view and (Φ) is a side view. FIG. 2 is a block diagram of a typical air-cooled heat pump type package air conditioner, and FIG. 3 is a diagram showing an example of the amount of refrigerant sealed in a refrigeration cycle and the temperature difference at each part. 1... Indoor unit 2... Outdoor unit 3... Refrigerant piping 4... Air suction port 5... Air outlet 6.
...Heat exchanger 7...Liquid refrigerant collection pipe 8...
Gas refrigerant collection pipe 9...Thermistor A 10
...Thermistor B 11...Thermistor C12
...Control device 13...Compressor 14...Blower 15...Temperature difference E 16...Temperature difference C0

Claims (1)

[Claims] 1. A method for detecting refrigerant shortage in an air conditioner, characterized by generating an alarm signal or stopping operation of a refrigerator when at least one of the following items is satisfied in the air conditioner. (1) The temperature difference between the evaporator inlet refrigerant and the evaporator outlet refrigerant is greater than a certain value. (2) The temperature difference between the evaporator outlet refrigerant and the evaporator intake air is smaller than a certain value. (3) The temperature difference between the refrigerant at the condenser inlet and the refrigerant at the condenser outlet is greater than a certain value. (4) The temperature difference between the condenser outlet refrigerant and the condenser suction air is smaller than a certain value. (6) The temperature difference between the evaporator intake air and the evaporator outlet air is smaller than a certain value. (6) The temperature difference between the condenser intake air and the condenser outlet air is smaller than a certain value.