JPH0532659B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a defrosting control device for a heat pump type air conditioner, and particularly to an air conditioner that efficiently starts defrosting operation.

Conventional technology Generally, during heating operation, when the outdoor temperature is high, or when the indoor air flow is low, an overload condition occurs, so the outdoor heat exchanger's blower is turned on and off to protect the compressor. . However, if the outdoor fan is turned on and off repeatedly, the outdoor heat exchanger will freeze. Therefore, conventionally, defrosting was started when the stop time of the outdoor blower was accumulated and a certain amount of time was reached.

Problems to be Solved by the Invention However, in many cases, the pressure is high after integration for a certain period of time, and when defrosting starts (when the four-way selector valve operates), loud noises and vibrations occur, causing discomfort to the user. It had disadvantages such as giving.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to reduce noise and vibration when defrosting is started in a heating overload state.

Means for Solving the Problems In order to achieve the above object, the present invention includes a heating overload detection means for detecting the pressure within the refrigeration cycle, and a detection signal from the heating overload detection means to control the air volume of the outdoor blower. A heating overload control device, a frost formation detection means for detecting the presence or absence of frost formation, and a defrosting operation control device that starts defrosting operation based on a frost formation detection signal from the frost formation detection means and a heating overload end detection signal. It was established.

Effect: By reducing the pressure within the refrigeration cycle before defrosting operation and then switching the four-way valve, the refrigerant flow noise and vibrations that occur during switching can be suppressed.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a refrigeration cycle diagram showing an embodiment of the present invention.

In the figure, the refrigeration cycle is constructed by sequentially connecting a compressor 1, a four-way switching valve 2, an outdoor heat exchanger 3, a pressure reducer 4, and an indoor heat exchanger 5. 6 is an indoor heat exchanger temperature detection element corresponding to heating overload detection means. Reference numeral 7 denotes an outdoor blower, which corresponds to a control means for controlling the amount of heat absorbed by the outdoor heat exchanger.

In this case, during cooling operation, the refrigerant flows in the direction of the solid arrow shown in the figure, and during heating operation, the four-way switching valve 2 is switched, so that the refrigerant flows in the direction of the broken line arrow shown in the figure.

FIG. 2 is a main circuit diagram of the operation control section.

In the figure, a microcomputer 8 includes a storage section 9 that integrates the stop time (overload control time) of the outdoor blower 7, an overload control time integration circuit stored in the storage section 9, and an output signal as appropriate from the input value. It has drive signal generating means 10 for generating. An indoor heat exchanger temperature detection element (for example, a piping thermistor) 6 and a temperature setting resistor 12 are connected to the input side of the microcomputer 8 via a comparator 11. A relay 13 for driving and stopping the outdoor blower 7 and a relay 14 for driving the four-way switching valve 2 are connected to the output side via switching transistors TR ₁ and TR ₂ .

FIG. 3 is a flowchart up to the start of defrosting operation.

After the heating operation starts, the indoor heat exchanger temperature t is read and compared with the first set temperature _t1 , and if the indoor heat exchanger temperature t exceeds the first set temperature _t1 , an overload signal is generated. , a relay 1 which integrates time in an overload control time integration circuit in a storage section 9 and drives and stops the outdoor fan 7 from a drive signal generation means 10;
2 is operated, and the outdoor blower 7 is stopped.

After that, the indoor heat exchanger temperature t becomes the second set temperature t ₂
If it becomes less than 1, an overload end signal is generated, the overload control time integration circuit stops time integration, and the relay 12 that drives the outdoor fan 7 is activated to operate the outdoor fan and return to normal heating operation. .

By repeating the above, when the cumulative time T of the overload control time integrating circuit exceeds the predetermined cumulative time _T1 and the overload end signal is generated, the relay 13 that drives the four-way switching valve 2 is activated to defrost. start.

Next, the operation up to defrosting will be explained.

If the outdoor blower 7 is stopped during heating overload, the low pressure will drop and frost will adhere to the temperature of the outdoor heat exchanger. When the overload control ends and the outdoor blower 7 is operated, the low pressure increases and the frost that has formed starts to melt.

By repeating the above control, the outdoor heat exchanger 3
Freezes to grow. To thaw this freeze,
When the stop time (overload control time) of the outdoor blower 7 is accumulated and reaches a predetermined time _T1 , the defrosting start condition is satisfied.

However, when the cumulative time T reaches _T1 , the pressure is generally high, so if the four-way switching valve 2 is switched in this state, loud noises and vibrations are generated, making the user uncomfortable.

After the defrosting start conditions are satisfied, the system waits until the overload control ends, and when the high pressure has decreased (at the end of the overload control), the four-way switching valve 2 is switched to start defrosting.

The contents of the above operation are shown in FIG.

In this embodiment, the overload control detection means was performed by the indoor heat exchanger temperature detection element 6, but it could also be performed by an operating current detection element including a compressor, a pressure detection element for detecting high pressure, etc. The same effect can be achieved even when the temperature is high. Furthermore, although driving and stopping of the outdoor blower was used to control the amount of heat absorbed by the outdoor heat exchanger, switching the air volume of the outdoor blower may also be used.

Effects of the Invention As described above, according to the present invention, with the above-described configuration, the defrosting start condition is satisfied when starting defrosting during overload control (the cumulative time is constant by integrating the stop time of the outdoor blower). After the defrosting time is reached, defrosting is started based on the overload control end signal, which reduces the pressure on the high pressure side of the refrigeration cycle, reducing loud noises and vibrations when defrosting starts, making it more comfortable. It performs proper defrosting.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a refrigeration cycle diagram, Fig. 2 is a main circuit diagram of the operation control section, Fig. 3 is a flowchart up to the start of defrosting, and Fig. 4 is a refrigeration cycle diagram. The figure is a time diagram until the start of defrosting. 1... Compressor, 2... Four-way switching valve, 3... Outdoor heat exchanger, 4... Pressure reducer, 5... Indoor heat exchanger,
6...Indoor heat exchanger temperature detection element, 7...Outdoor blower, 8...Microcomputer, 9...Storage unit, 10...Drive signal generating means.

Claims (1)

[Claims] 1. Heating overload and termination of heating overload can be detected using a heat pump type refrigeration cycle consisting of a compressor, four-way switching valve, outdoor heat exchanger, pressure reducer, indoor heat exchanger, etc. connected in sequence and heating overload detection means. a heating overload control device that detects and controls an outdoor air blower air volume of the outdoor heat exchanger based on the detection signal;
A frost detection means detects the presence or absence of frost when the cumulative time reaches a certain time by converting the stop time of the outdoor blower, and a frost detection signal from the frost detection means and the end of the heating overload. A defrosting control device for an air conditioner, comprising a defrosting operation control device that switches the four-way switching valve to start defrosting operation upon receiving both detection signals at the same time.