JPS62131134A - Method of defrosting for air conditioner - Google Patents

Abstract

PURPOSE:To conduct most suitable defrosting operation in accordance with the state of frost formation on an outdoor heat exchanger by providing a temperature sensor which detects temperature change in an indoor heat exchanger, a frost formation sensing circuit, and a timer circuit which changes the setting of time for defrosting operation. CONSTITUTION:The input side of a microcomputer is provided with a thermistor 7 for temperature sensing via a comparator 8 and a setting resistor 13 for a set temperature difference DELTAT. The microcomputer 9 incorporates a memory 10 which stores the temperature Ts of an indoor heat exchanger at the time of starting defrosting operation and an arithmetic unit 12 which compares a set temperature difference with the temperature difference Ts-Td which is the temperature Ts minus Td, the temperature of an indoor heat exchanger at the time when a certain time has passed after starting the defrosting operation and conducts change-over of set defrosting operation time in a timer 11. A temperature difference DELTAT between a temperature Td after a certain time N1 has elapsed and the temperature Ts is taken and it is compared with temperature T1 set beforehand. If this temperature difference DELTAT is higher than T1, a shorter defrosting time N2 is used. On the contrary if DELTAT is lower than T1, a longer defrosting time N3 is used, and it is possible to carry out defrosting operation most suitable for the state of frost formation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a defrosting method for an air conditioner equipped with a toto pump type refrigeration cycle.

BACKGROUND OF THE INVENTION Until now, there is a defrosting method for air conditioners in which the defrosting time is set constant.

This conventional example is shown in FIG. That is, the frosting state detection circuit detects the frosting state of the outdoor heat exchanger and outputs a defrosting start signal based on the detection result. 'iff, the count contents of the 1st and 17th circuits that operate by outputting the above-mentioned defrosting start signal and outputting a short-time defrosting operation signal, and the count of the kakunta that counts the number of times of the above-mentioned defrosting start signal. a second timer circuit that is controlled according to the timing, operates every time a defrosting start signal is output a certain number of times, and outputs a long-term defrosting operation signal, and is output from the first timer circuit or the second timer circuit. A defrosting operation signal is generated to control the defrosting operation (Japanese Patent Publication No. 58-20944).

Problems to be Solved by the Invention However, in an air conditioner in which the defrosting operation time is set constant, the defrosting of the outdoor heat exchanger may still occur due to changes in the amount of frost on the outdoor heat exchanger. The defrosting operation may end even though the defrosting operation is not completed, or the defrosting operation may continue uselessly even though the defrosting operation has been completed.

SUMMARY OF THE INVENTION Therefore, the present invention aims to eliminate the above-mentioned conventional freezing point and to perform an optimal defrosting operation depending on the frosting state of the outdoor heat exchanger.

Means for Solving the Problems 6 and the technical means of the invention for solving the above problems include temperature detection means for detecting the temperature change of the indoor heat exchanger when the air conditioner starts defrosting operation. This device is equipped with a frosting state detection circuit that determines the frosting state of the outdoor heat exchanger based on this temperature change and performs optimal defrosting operation, and a timer circuit that sets the defrosting operation time.

Function When defrosting the air conditioner, the rate of decrease in the indoor heat exchanger temperature at the start of the defrosting operation changes depending on the amount of frost on the outdoor heat exchanger. The unexploded F3A is the line with the above points,
If the rate of decrease in the heat exchanger temperature is fast, the amount of frost formed is small, so set the timer for defrosting operation for a short time.On the other hand, if the rate of decrease is slow, the amount of frost formed is large, so set the timer for defrost operation. is a long time.

EXAMPLE Hereinafter, a method for defrosting an air conditioner according to an embodiment of the invention will be explained with reference to the drawings.

FIG. 4 shows the change in indoor heat exchanger temperature during heating operation and defrosting operation, with elapsed time plotted on the horizontal axis.

The defrosting operation is started when a certain period of time has passed after the start of the heating operation and the indoor heat exchanger temperature has become below a certain temperature.

In FIG. 4, the solid line shows the change in the indoor heat exchanger temperature when the amount of frost formation is large, and the dotted line shows the change in the indoor heat exchanger temperature when the amount of nitrogen deposited is small.

The indoor heat exchanger temperature T drops rapidly with the start of the defrosting operation, but once the temperature drops to a certain level, the high and low pressures are balanced and the rate of temperature drop becomes extremely small. The indoor heat exchange temperature T at the high-low pressure balance point is high when the amount of M deposited is large, and low when the amount of frost is small. That is, as shown in FIG. 4, when the temperature difference ΔT that decreases within a certain period of time N1 from the indoor heat exchanger temperature TS at the start of the defrosting operation is small, the amount of frost formation is large and the defrosting time is long. Conversely, when the temperature difference ΔT that decreases within a certain period of time Ni is large, the amount of frost formation is small and the defrosting time is short.

Next, FIG. 2 shows the refrigeration cycle of this embodiment.

A compressor 1, a four-way valve 2, an indoor heat exchanger 3, a capillary tube 4, and an outdoor heat exchanger 5 are connected in a ring. Here, during heating operation, the refrigerant flows in the order of compressor 1, four-way valve 2, indoor heat exchange @ 3, capillary tube 4, and outdoor heat exchanger 5, and during defrosting operation, the refrigerant flows through compressor 1, four-way valve 2, and outdoor heat exchanger. It flows in the order of vessel 5.

Here, 6a to 6d are temperature detection means that indirectly detect the temperature of the indoor heat exchanger 3. That is, 6a is a temperature sensor that detects the pipe temperature of the indoor heat exchanger 3, 6b is a current detector that detects the current of the compressor 1, 6c is a pressure detector that detects the pressure of the discharge pipe of the compressor 1, and 6d is a pressure detector that detects the pipe pressure of the indoor heat exchanger 3. The pipe temperature of the indoor heat exchanger 3 can also be detected from the temperature, pressure, and current of each of the above parts, and any one of them can be selected or used in combination.

Next, a circuit diagram of the main part of this embodiment is shown in FIG.

On the input side of the microcomputer, a thermistor 7 which is a temperature detection means and a set temperature difference Δ are connected via a comparator 8.
T setting resistor 13, and four-way valve switching relay 1 on the output side
There are 4.

In addition, a storage unit 10 that stores the indoor heat exchanger temperature Ts at the time of starting the defrosting operation Vc/, ri in the microcomputer 9, and a certain period of time elapsed after the start of the defrosting operation from the indoor heat exchanger temperature 'rs at the time of starting the defrosting operation. It has a built-in calculation unit 12 that subtracts the indoor heat exchanger temperature Td at There is.

Next, the operation of this embodiment is shown in FIG. The figure is a 70-chart during defrosting operation.

At the same time as the defrosting operation starts, the indoor heat exchanger temperature T is read and the temperature at this time is stored as Ts.

Next, the temperature difference ΔT between the indoor heat exchanger temperature Td and the indoor heat exchanger temperature T after a certain period of time N1 has passed is taken and compared with a preset temperature T1. If this temperature difference ΔT is higher than T1, a short defrosting time N2 is set. Conversely, when the temperature difference ΔT is lower than T1, the defrosting time is set to be long N3.

Such an operation will be explained regarding heating operation at low outside temperature.

If heating operation is performed under conditions of low outside temperature and low humidity, the indoor heat exchanger piping temperature will drop even though the amount of frost on the outdoor heat exchanger is small, and when the temperature drops below a certain level, defrosting operation will begin. enter. Since the amount of frost is small, the temperature of the indoor heat exchanger rapidly decreases after the defrosting operation starts. As a result, the defrosting operation time is set to a short time. In other words, it is possible to set the defrosting operation time according to the amount of frost formation.

Effects of the Invention As is clear from the description of the above embodiments, the present invention allows the setting of the defrosting operation time to be changed depending on the amount of frost formed on the outdoor heat exchanger. Defrosting operation can be performed.

[Brief explanation of drawings]

Fig. 1 is a flowchart explaining the M removal operation of an air conditioner in an embodiment of the present invention, Fig. 2 is a refrigeration cycle diagram of the air conditioner in the embodiment, and Fig. 3 is an electric circuit of the air conditioner. Figure 4 is a characteristic diagram showing the change in indoor heat exchanger temperature to y during defrosting operation of the air conditioner, and Figure 5 is a time chart showing a conventional example. 1...Compressor, 3...Indoor heat exchanger,
5...Outdoor heat exchanger, 6&...Temperature sensor, 7...Thermistor, 10...Storage unit, 11...Timer, 12... Arithmetic unit. Name of agent: Patent attorney Hoo Nakao and 1 other person No.1
figure

Claims (1)

[Claims] A compressor, a four-way switching valve, an outdoor heat exchanger, a capillary tube, and an indoor heat exchanger are sequentially connected to form a heat pump type refrigeration cycle, and a temperature sensor detects the temperature of the indoor heat exchanger, and a temperature detector detects the temperature of the indoor heat exchanger, and An air conditioner equipped with a frosting state detection circuit that detects the frosting state of the exchanger based on the temperature detector and a timer circuit that changes the defrosting operation time setting based on a signal from the frosting state detection circuit. How to defrost a harmonizer.