JPS62125272A - Method of controlling electronic expansion valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a DDC type electronic expansion valve, and particularly to a control method effective for shortening defrost time.

[Background of the invention]

Related publications include Japanese Utility Model Application Publication No. 55-139859, but these simply perform defrosting with the expansion valve fully open, and do not store liquid refrigerant in an accumulator immediately before defrosting. , there is no consideration given to resolving the refrigerant shortage in the compressor suction during defrosting. [Object of the Invention] The object of the present invention is to provide a refrigerant control method (for a refrigeration cycle) that can complete defrosting in a short time. In particular, the object of the present invention is to provide a digital internal processing method for electronic expansion valves.

[Summary of the invention]

The most important thing to finish defrosting in a short time is (
1) Ensure a sufficient flow rate of the refrigerant, which is a heat transport medium. → To this end, increase P8 to keep the specific volume of the compressor suction gas small.

(2) Securing a heat source → If heat cannot be obtained from indoors, prepare for sufficient indoor heat exchange in advance. Otherwise, set the operating point so that the compressor input is large during defrost. →It is necessary to increase Pg. Conventionally, the (-) expansion valve was opened as much as possible. (1)) In the last few minutes, it was proposed to increase high pressure and store heat in a heat exchanger for heating. (a) has the purpose of quickly returning the refrigerant to the suction side of the compressor during defrost operation, but it is not necessarily effective because the difference between high and low pressures is only a few Kq/dL. Although (1)) is somewhat useful as a heat source, it has a greater effect of accumulating high-pressure liquid refrigerant in the indoor heat exchanger.

And, when you cut to defrost, the amount of refrigerant on the low pressure side (it gasifies because it is depressurized) j! Leads to the 1st major. However, since it is gasified, it cannot be used in an hour and runs out in a short period of time.

The most effective method is to store low-pressure liquid refrigerant in the accumulator just before entering the defrost (I came to think that this could save time because even if the four-way valve is switched, this liquid will not be gasified.) The defrost time shortening effect was a little over 1 minute.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to FIGS. 1 to 8.
do. An example of the acid-resistant refrigeration cycle of the present invention is shown in FIG. In cooling, the high-pressure refrigerant discharged from the compressor 1t passes through the four-way valve 2 and is liquefied in the outdoor heat exchanger 8.The electronic expansion valve 4 reduces the pressure and produces a cooling effect in the indoor heat exchanger 5, and the refrigerant is gasified. It returns to the compressor via the four-way valve 2 and the accumulator 6. For heating, the four-way valve 2 switches to the side shown by the broken line. During heating, the super heat 8H is controlled to a constant value of 8HI (25° C.) as shown in FIG. 1 until time T1. When the defrost sensor is turned ON at this time T, the super heat setting is changed to 5R2 (1° C.). Since the valve is under feedback control, the liquid tends to return at 5a41, and while the liquid is accumulating in the aqueous emulator, the time T
Parrots continue to be heated. When the four-way valve is turned off at time T2 and switched to the defrost cycle (cooling cycle), the valve is fully opened and the super heat is not controlled and is turned off. In this case, liquid refrigerant returns to the compressor after tightening, which is usually not the case, so it is undesirable for it to last for a long time. Therefore, when time T3 is reached after a relatively short period of time, the super heat setting is returned to S H+ (g 5 ) and % feedback control is performed. The defrost continues as it is and the liquid no longer returns), and at time T4 when the defrost sensor turns off, the heating (four-way valve turns on)
K returns and is operated so as to maintain the same <EiH+ (=5). As described above, during the time (T2-T+) immediately before the start of the defrost cycle, unevaporated refrigerant is stored in the accumulator and is prepared for the primary defrost operation.

Next, when this is indicated by control 70-, it becomes as shown in FIG. In other words, it detects whether the defrost sensor is ON or OFF and turns it ON.
Then, the set superheat is 1°C. Next, the actual superheat is read and the deviation ε from the set value is calculated. Next, the setting superheat is 1℃, so it takes 1 hour.
When the temperature has not exceeded 1, the valve opening degree is feedback-controlled (F(ε)) based on the above ε, and the superheat is kept constant at 1°C. During this operation, liquid refrigerant tends to return, so low-pressure liquid refrigerant is accumulated in the Akiemulator during this period. Then, when time t has elapsed (the four-way valve is turned off, the four-way valve is fully opened, and defrost operation begins. This fully open state lasts until time t).
After the temperature has passed, the set superhysade becomes 5°C. Then, the actual super heat is read and the valve opening is controlled by feedback of the deviation ε (=5U-(SH) arsenic). In this state, I constantly check the defrost sensor.

Once the defrost is finished (as shown at the top of the flow), only the defrost sensor is constantly checked.

〔Effect of the invention〕

According to the present invention, sufficient refrigerant is secured on the suction side of the compressor during defrosting, so that P8 does not drop much and the defrosting time can be shortened.

[Brief explanation of drawings]

FIG. 1 shows a defrost operation control sequence which is the core of the present invention, FIG. 2 shows an example of a refrigeration cycle at that time, and FIG. 8 shows a control flow. 1... Capacity control compressor 4... Electronic expansion valve 2
... Four-way valve 5 ... Indoor heat exchanger 8 ... Outdoor heat exchanger tester 6 ... Accumulator representative Patent attorney Masaru Ogawa Male figure 1 Figure 2

Claims (2)

[Claims] 1. In a heat pump refrigeration cycle that has a capacity-controlled compressor and uses an electronic expansion valve to digitally control the refrigerant flow rate, when the defrost sensor turns on, the digital processing for controlling the electronic expansion valve sets the superheat setting. intentionally changed the setting to a specific value around 0℃, and then
The electronic expansion valve is operated with heating for 10 seconds to 10 minutes, during which time the electronic expansion valve performs feedback control for superheat detection from beginning to end, and then switches to a defrost cycle, and the valve opening is controlled in a predetermined pattern. A method of controlling a digitally controlled electronic expansion valve for a refrigeration cycle. 2. 2. The method of controlling an electronic resin valve according to claim 1, characterized in that, instead of setting the superheat setting to 0° C., the superheated refrigerant gas temperature detection thermistor is appropriately heated with an electric heater.