JPH056103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a defrosting control device for a frequency-controlled air conditioner, the operation control device of which is equipped with a microcomputer.

Conventional technology Conventionally, in air conditioners, frost builds up on the outdoor heat exchanger as the outside temperature drops during heating operation.
Various ideas have been devised regarding defrosting methods.

An example of the conventional air conditioner mentioned above will be described below with reference to the drawings.

FIG. 6 is a refrigeration cycle diagram of a heat pump type air conditioner, and the refrigeration cycle is composed of a compressor 1, a four-way valve 2, an indoor heat exchanger 3, a pressure reducer 5, and an outdoor heat exchanger 4. During heating, the refrigerant discharged from the compressor 1 passes through the four-way valve 2, radiates heat in the indoor heat exchanger 3, reduces the pressure in the pressure reducer 5, and absorbs heat in the outdoor heat exchanger 4, as shown by the solid line. , and then returns to compressor 1.

When the outside temperature is low during heating, the condensed water condensed in the outdoor heat exchanger 4 will gradually start to form frost on the outdoor heat exchanger 4, so the four-way valve 2 will be switched to cooling operation, and the outdoor heat exchanger 4 will be cooled. Melt the frost that has formed. (Dotted arrow) Conventionally, gas refrigerant is injected into the compressor during defrosting, or air conditioners equipped with a frequency-controlled compressor operate at the highest frequency during defrosting to increase the compressor input. The defrosting time was shortened. (For example, Japanese Patent Publication No. 55-20332) Problems to be Solved by the Invention However, in the configuration shown in FIG.
Since the orifice is constant, if the compressor is operated at a fixed maximum frequency during defrosting, the suction pressure will drop dramatically as shown in Figure 7, and the refrigerant will not return to the suction side of the compressor. This has the disadvantage that the input to the compressor does not increase, and the input to the compressor that contributes to defrosting decreases, resulting in a longer defrosting time. In addition, especially when the outside temperature is low, the region (time) in which the suction pressure becomes negative during defrosting expands, and as the defrosting time becomes longer, supercooled refrigerant returns to the suction side of the compressor, so it is compressed. This had the disadvantage of shortening the life of the machine.

In view of the above problems, the present invention aims to reduce the defrosting time by controlling the optimal defrosting operation by changing the frequency while monitoring the combined suction pressure of the compressor according to the suction temperature during defrosting operation of an air conditioner. The purpose is to measure.

Means for Solving the Problems In order to solve the above problems, the air conditioner of the present invention detects the suction temperature (pressure) of the compressor using a temperature detection means provided on the suction side of the compressor, as shown in FIG. is detected and compared by a comparing means at the timing given by the timing means, and the operating frequency of the compressor is changed by the electric signal from the comparing means. The output means is configured to operate the compressor at a frequency specified by an electric signal stored in a storage means storing a variable number output mode for controlling the compressor in a step-by-step manner.

Effect The present invention has the above-described configuration, detects the suction temperature (pressure) of the compressor during defrosting operation, and lowers the operating frequency when the suction pressure approaches negative pressure, and when the suction pressure recovers again, it reaches the maximum. This system aims to shorten the defrosting time by operating the compressor at a high frequency and controlling the compressor so that the input to the compressor is always at the maximum during defrosting. Furthermore, since the suction pressure does not become negative pressure, the life of the compressor can be extended.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 5 of the accompanying drawings. Here, since the refrigeration cycle is the same as the conventional example, illustration and description thereof are omitted, and here, the content of compressor frequency control during defrosting operation will be explained.

In FIG. 1, the control circuit includes a thermistor 6 that detects the suction temperature t of the compressor 1, a temperature detection device 7 that converts the detected temperature t into an electrical signal and outputs it, and a resistance device 8 that provides an electrical signal of the temperature set value T. , an oscillation device 10 that provides pulses of a constant frequency to a microcomputer (hereinafter referred to as LSI) 9, a temperature detection device 7
A comparison circuit that compares and determines the electric signal from the temperature setting value T with the electric signal from the temperature set value T, a timer circuit that provides the timing of this comparison, and a frequency pulse of the frequency oscillator 10 is counted to vary the operating frequency of the compressor 1 in stages. LSI 9 has a built-in variable frequency output circuit that outputs an electrical signal that sequentially shifts the operating frequency of the compressor 1 according to the electrical signal of the comparison circuit; The compressor 1 is equipped with an output device using a power transistor 11 for operating the compressor 1, a power supply device 12 for applying the operating voltage of the compressor 1 to the power transistor 11, and the compressor 1.

The relationship between the block diagram shown in FIG. 2 and the control circuit diagram shown in FIG. 1 will now be explained. The thermistor 6 serves as a temperature detection means, the resistance device 8 serves as a temperature set value, and the comparison circuit, timer circuit, transition circuit, and variable frequency output circuit built in the LSI 9 serve as comparison means, time measurement means, transition means, and storage means, respectively. The power transistor 11 corresponds to the output means.

Next, the operation of the control circuit having the above configuration will be explained with reference to FIGS. 3 and 4.

At the start of defrosting operation, a timer circuit built into the LSI 9 is turned on, and the detected temperature t detected by the thermistor 6 installed in the suction pipe 15 of the compressor 1 is compared with the set temperature T, and if t≧T, Proceed to operation (run compressor 1 at maximum frequency f ₁ ) and timer is n=n
It becomes +1 and the count advances. As defrosting progresses, the compressor 1 is operated at the highest frequency with the throttle constant, so the suction pressure (temperature) of the compressor 1 rapidly decreases and approaches negative pressure. Therefore, the temperature of the suction pipe 15 of the compressor 1 also decreases, and the operating temperature t of the thermistor 6 installed in the suction pipe 15 becomes t<T, so it operates (the compressor 1 is operated at a frequency f ₂ lower than f ₁ ). to prevent the suction pressure of the compressor 1 from becoming negative pressure.
As a result, a certain amount of refrigerant returns to the suction side of the compressor 1, making it possible to perform optimal control such that the input to the compressor 1 is always maximized, shortening the defrosting time, and Since the refrigerant for cooling does not return to the compressor 1, it is possible to prevent the life of the compressor 1 from decreasing.

The flow chart of FIG. 3 and the time chart of FIG. 4 show the flow of the above operations. The time chart in Fig. 5 is an example in which two temperature settings (T ₁ < T ₂ ) are provided, and the detected temperature t is T ₂
If the frequency drops below that level, the operating frequency of compressor 1 is lowered by one step.
Conversely, when t exceeds _T1 , the operating frequency of compressor 1 is increased by one step, and care is taken to maximize the input to compressor 1 during defrosting operation while managing the suction temperature of compressor 1. This is what I did. Similar effects can be obtained even if the operating frequency of the compressor is changed in multiple stages using multiple temperature settings and time controls in this way.

Effects of the Invention As is clear from the above explanation, the defrosting control device for a frequency-controlled air conditioner according to the present invention detects the suction temperature of the compressor during defrosting and controls the compressor so that the suction pressure does not become negative pressure. By controlling the operating frequency of the compressor, the input to the compressor contributing to defrosting can be always maximized, and as a result, the defrosting time can be shortened. Furthermore, since the suction pressure does not become a negative pressure, supercooled refrigerant does not return to the suction side of the compressor, which prevents shortening of the life of the compressor.

[Brief explanation of drawings]

Fig. 1 is a control circuit diagram of an operation control device equipped with a microcomputer according to the present invention, Fig. 2 is a block diagram expressing the same operation control device as a function realizing means, and Figs. Flow chart and time chart of the control device, FIG. 5 is a time chart regarding another embodiment of the present invention,
FIG. 6 is a refrigeration cycle diagram, and FIG. 7 is a diagram of changes in suction pressure and compressor input during defrosting operation, showing a conventional example. 1...Compressor, 4...Outdoor heat exchanger, 6...
Thermistor (temperature detection means), 7...Temperature detection device, 9...Microcomputer.

Claims (1)

[Claims] 1. A compressor, a four-way valve, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger are connected in a ring to form a heat pump refrigeration cycle, and temperature detection means for detecting the suction temperature of the compressor; comparing means for comparing the electrical signal from the temperature detecting means with a plurality of temperature setting values at fixed time intervals determined by the time measuring means; and a comparing means for inputting the electrical signal from the comparing means to operate the compressor during heating operation. a transition means for sequentially shifting the frequency; a storage means for storing a variable frequency output mode for controlling the operating frequency of the compressor in stages according to the electric signal of the transition means; and a specified frequency output mode according to the electric signal of the storage means; A defrosting control device for an air conditioner, comprising an output means for operating the compressor.