JPH04268179A - Device for control of defrosting of air conditioner - Google Patents

Abstract

PURPOSE:To prevent droplets of melted frost from freezing when outdoor temperature is low and surely discharge the droplets in a device for control of defrosting of an air conditioner during the heating operation thereof. CONSTITUTION:A timer 16 to delay the restoration to a heating operation a predetermined period is provided in a controller 10 of an air conditioner and an outdoor temperature sensor 9 to detect outdoor temperature is provided in an outdoor machine. When the outdoor temperature is below a predetermined value at the completion of defrosting, by delaying the restoration of heating operation a predetermined period of time by means of the timer 16, droplets of melted frost can be prevented from freezing and melted frost can be surely discharged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting control device for an air conditioner during heating operation.

0002

[Prior Art] Conventionally, in a heat pump type air conditioner, the temperature of the outdoor heat exchanger is detected after heating has started and the compressor has been operating for a certain cumulative time, and a predetermined value (for example, -10
°C), it is determined that frost has formed on the outdoor heat exchanger and the defrosting operation is started. Defrosting operation is performed by switching the four-way valve installed in the refrigerant circuit, allowing high-temperature refrigerant gas from the compressor to flow through the outdoor heat exchanger, warming the outdoor heat exchanger, melting frost, and cooling the bottom plate of the outdoor unit. drop it into
When the temperature of the outdoor heat exchanger reaches a predetermined value (e.g. 10°C) or higher, it is determined that all frost has been removed and the four-way valve is switched. , a method of returning to heating operation is used. However, if the outside air temperature is low (e.g. 0°C) or below, the bottom plate of the outdoor unit and its surroundings will be kept at a low temperature even during defrosting operation, and dripping water will not flow to the drain, causing heating operation to continue. When the water returns to normal condition, it is cooled by the outdoor heat exchanger and may form ice on the bottom plate, and due to repeated defrosting and heating operations, it may grow and cause problems such as blocking the drain, so these frozen water droplets must be removed. Therefore, heating operation had to be stopped, and comfortable heating operation could not be performed for a long time.

0003

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to provide an air conditioner that can reliably discharge defrosted water droplets even when the outside temperature is low. The purpose is to provide a frost control device.

0004

[Means for Solving the Problems] In order to achieve the above object, the defrosting control device is provided with an outside air temperature sensor that detects the outside air temperature, and when the outside air temperature is less than a predetermined value, the outside heat exchanger temperature sensor is activated. When the detected temperature reaches the defrosting release temperature, the return to heating operation is delayed for a predetermined period of time.

[0005]

[Operation] According to the above configuration, if the outside air temperature detected by the outside air temperature sensor is below a predetermined temperature (0°C), when the outdoor heat exchanger reaches the defrosting release temperature, it will take a certain period of time ( By delaying the return to heating operation (for example, for 5 minutes) and reliably discharging dropped water droplets, it is possible to prevent problems such as freezing on the bottom plate and blocking the drain port.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a refrigerant circuit diagram showing the configuration of the present invention, in which the refrigerant returns from the discharge side of the compressor 1 to the four-way valve 2 via the four-way valve 2, the indoor heat exchanger 3, the expansion valve 4, and the outdoor heat exchanger 5. A refrigerant circuit leading to the compressor 1 is formed, and an indoor fan 6 and an outdoor fan 7 are arranged adjacent to the indoor heat exchanger 3 and the outdoor heat exchanger 5, respectively. stored in the casing. The figure shows the heating operation state, and the refrigerant gas compressed to high temperature and high pressure by the compressor 1 is sent to the indoor heat exchanger 3 by the four-way valve 2 as shown by the arrow, and is then exchanged for indoor heat by the indoor blower 6. The cooled refrigerant gas is liquefied, passes through the expansion valve 4, enters the outdoor heat exchanger 5, is vaporized, and is vaporized from the outdoor air by the outdoor blower 7. It removes heat and returns to the suction side of the compressor 1 via the four-way valve 2. If the heating operation continues when the outside air temperature is low, the temperature of the outdoor heat exchanger 5 will drop below the outside air temperature, causing frost to form on the outdoor heat exchanger 5, which will grow due to changes in the outside air temperature and cause outdoor heat. In order to reduce the heat exchange efficiency of the exchanger 5, it is necessary to defrost it periodically. An outdoor heat exchanger 5 is installed on the inlet side of the outdoor heat exchanger 5.
An outdoor heat exchanger temperature sensor 8 is arranged to detect the temperature of the outdoor unit, and an outside air temperature sensor 9 is arranged in a part of the outdoor unit exposed to the outside air.

FIG. 2 is a control block diagram, and the control section 10 includes a setting input circuit 11 that receives a signal from an operation section (not shown) as an input, an indoor temperature sensor 12, and an outdoor heat exchanger temperature sensor. 8. Various sensors such as an outside air temperature sensor 9 are connected, and the control unit 10 is provided with an A/D converter 13, a comparison circuit 14, a memory 15, a timer 16, etc., and outputs include an indoor blower 6 and an outdoor blower. 7, the compressor 1 and the four-way valve 2 are connected. From the setting input circuit 11, the indoor temperature setting, the defrosting start temperature and defrosting end temperature of the outdoor heat exchanger 5, the reference value of the outside air temperature, each time setting of the timer 16, the control conditions of the output side equipment, etc. are input. , are stored in the memory 15. In this state, the control unit 10 starts the operation of the compressor 1, and at the same time starts the operation of the indoor side blower 6 and the outdoor side blower 7, and the signals detected by various sensors such as the indoor temperature sensor 12 are Comparison circuit 1 via D converter 13
4 and stored in the memory 15, the output side equipment is controlled to comply with the control conditions.

FIG. 3 is a flowchart of the present invention, in which the operation time of the compressor 1 is integrated from the start of the heating operation, and the defrosting operation is prohibited until a certain period of time, for example, 40 minutes or more has elapsed (21), and after the certain period of time has elapsed, the operation time of the compressor 1 is The signal from the heat exchanger temperature sensor 8 is taken into the comparison circuit 14 via the A/D converter 13,
When the temperature of the outdoor heat exchanger falls below the set value of -10°C, it is determined that frost has formed (22), the indoor fan 6 and the outdoor fan 7 are stopped, and the four-way valve 2 is switched to the cooling side to remove the frost. Start frost operation (23). In this state, defrost operation continues until the outdoor heat exchanger temperature exceeds the set value of 5°C (2
4) When the outside temperature exceeds 5°C, the outside air temperature sensor 9
If the temperature is below the set value of 0°C (25), the timer 16 is set for a certain period of time, for example, 5 minutes, and the defrosting operation continues (26). After the time is up (27), the indoor blower 6 and the indoor The outside blower 7 is operated and the four-way valve 2 is switched to the heating side to return to heating operation (28).

[0009]

As described above, in the present invention, when the outside air temperature is low at the end of the defrosting operation and there is a risk that the defrosting water droplets may freeze, the defrosting return is delayed for a certain period of time to reduce the temperature inside the outdoor unit housing. At the same time, by reliably discharging dropped water droplets, it is possible to prevent problems such as freezing on the bottom plate and blocking the drain port.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram showing the configuration of the present invention.

FIG. 2 is a control block diagram of the same.

FIG. 3 is the same flowchart.

[Explanation of symbols]

1 Compressor 2 Four-way valve 3 Indoor heat exchanger 4 Expansion valve 5 Outdoor heat exchanger 6 Indoor blower 7　Outdoor side blower 8 Outdoor heat exchanger temperature sensor 9 Outside air temperature sensor 10 Control section 11 Setting input circuit 12 Indoor temperature sensor 13 A/D converter 14 Comparison circuit 15 Memory 16 Timer

Claims (1)

[Claims] Claim 1: The operating time of the compressor is accumulated by a timer, and when the operating time exceeds a predetermined time, the temperature of the outdoor heat exchanger is detected by an outdoor heat exchanger temperature sensor, and when the detected temperature is reached, defrosting starts. When the temperature reaches the temperature, the four-way valve is switched to flow high-temperature refrigerant gas to the outdoor heat exchanger to start defrosting, and when the detected temperature reaches the defrost release temperature, the air conditioner returns to heating operation. In the frost control device, the defrost control device is provided with an outside air temperature sensor that detects outside air temperature, and when the outside air temperature is less than a predetermined value, the temperature detected by the outdoor heat exchanger temperature sensor reaches a defrosting release temperature. A defrosting control device for an air conditioner, characterized in that the return to heating operation is delayed.