JP2001289493A - Control method for air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for stopping overheat of the fan motor in an air conditioner surely and transmitting an alarm signal externally at a low cost. SOLUTION: An fan motor output signal from a microcomputer 1 and a CT current are ANDed (logical sum) (step S7). A decision is then made whether a specified value set in the microcomputer 1 (fan motor output set value) and the CT current fall within the range of normal value or not (step S8). If both values fall within the range of normal value, the control skips to step S11 before ending the processing. If the value of the CT current deviates from the range of normal value, a CT voltage is compared with a initial voltage set in the microcomputer 1 and temporary operation of the fan motor 11 is started if a failure is predicted (steps S9-S10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner, and more particularly, to a technology of a protection circuit when a fan motor temperature is abnormal.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a circuit diagram showing an electric system diagram of a conventional refrigerant compressor protection device disclosed in Japanese Patent Application Laid-Open Publication No. H10-15095.

[0003] The operation of this protection circuit is as follows. A 200 V AC is applied to the internal thermo 20, the internal thermo 20 is operated by a rise in temperature, and the microcomputer controls the operation of the internal thermo 20 via the photocoupler 21 (not shown). Z)
, The fan motor temperature rises → the operation of the internal thermo 20 → input to the microcomputer → the fan motor stops.

[0004]

However, there has been a demand for a method for reliably stopping overheating of the fan motor and transmitting a warning signal to the outside without increasing the cost.

Further, once the fan motor is overheated and the internal thermometer operates (operates at 130.degree. C. and returns at 85.degree. C.), it takes about one hour to recover, so the internal thermometer predicts the operation in advance. In addition, it has been demanded that the operation of the air conditioner should not be stopped as much as possible.

[0006]

In order to solve the above-mentioned problems, an invention according to claim 1 is an air conditioner comprising a compressor, an outdoor heat exchanger and a fan motor, and an indoor heat exchanger. When the fan motor of the air conditioner reaches a certain temperature, the internal thermo in the fan motor is directly cut off to stop supplying power.

According to a second aspect of the present invention, in an air conditioner including a compressor, an outdoor heat exchanger and a fan motor, and an indoor heat exchanger, voltage detecting means for detecting a voltage from the fan motor. Is provided, and a failure is predicted based on the voltage detected from the fan motor. If a failure is predicted, a provisional operation mode is performed.

As described above, the operation of the air conditioner according to the present invention is as follows. The fan motor is directly cut off, so that it can be safely and reliably stopped. Judgment, life extension operation in the provisional operation mode is possible until the internal thermometer operates.

Further, by reducing the 200 V circuit from the control board, the board area can be reduced and the cost can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

Generally, a fan motor provided in an air conditioner or the like has a high device temperature due to various factors such as an overcurrent, a long-time operation, and an abnormality of a motor device. In addition to being unable to operate, it is possible that a fire may occur from the equipment.

For this reason, an internal thermo is attached to the control circuit of the fan motor, and when the internal thermo is operated upon detecting a temperature rise, it is transmitted to the microcomputer via the operation signal photocoupler to display an alarm, The operation of the fan motor was stopped.

In addition, since the internal thermo uses a 200 V power supply, a control circuit is required to operate at 200 V together with a control circuit composed of a normal weak electric circuit. When a 200 V circuit is formed on a printed circuit board, ,
It is necessary to make the printed wiring thick and widen the wiring interval.

For this reason, a control board using a 200V power supply such as an air conditioner has a large board area and requires a high cost.

FIG. 1 shows a control configuration diagram. In the figure,
Reference numeral 10 denotes a power supply for the control board 6, reference numeral 2 denotes an internal thermo sensor, reference numeral 3 denotes a CT (current transformer) sensor, reference numeral 4 denotes an AND circuit for the output of the microcomputer 1 and the current of the CT, and reference numeral 5 denotes a voltage preset from the CT. It is a comparator with a voltage (set at a rated 100% of the fan motor 11 that varies with R).

FIG. 2 is a flowchart showing the operation of the control circuit of FIG.

In step S1, a fan motor start signal is issued from the microcomputer, and the R phase in the three-phase input power supply of the fan motor is turned on by a switch (1 ×) (step S2).

Subsequently, the fan motor is energized via the internal 2 (step S3), and a CT (current transformer) is connected to the S phase in the three-phase input power supply (step S4).

In step S5, it is determined whether or not the internal 2 is energized.
The jump processing ends at step S11, and if current is supplied, a CT current (overcurrent) is detected (step S6).

Next, the fan motor output signal from the microcomputer 1 and the CT current are calculated as an AND (logical sum) (step S7).

It is determined whether or not the predetermined value set in the microcomputer 1 (the value in which the magnitude of the fan motor output is set) and the CT current are within a normal value range (step S8).

If both of the results are within the normal value range, the process jumps to step S11, and if the value of the CT current is out of the normal value range, the CT voltage is compared with the initial setting voltage of the microcomputer 1 to determine a failure. Fan motor 1 when expected
The first provisional operation is started (steps S9 to S10).

Finally, the process ends in step S11,
These series of processes are repeated again.

Although the present invention has been described based on the above embodiment, the present invention is not limited to this.

[0025]

As described above, the method for controlling an air conditioner according to the present invention can reduce the printed circuit board area and the manufacturing cost because the control circuit can reduce the 200 V circuit by the internal thermo input. Can be.

Further, since the input power of the fan motor can be directly cut off, it is possible to safely and reliably stop the microcomputer irrespective of abnormality of the microcomputer (system runaway or the like).

In addition, the accuracy is improved by detecting the current by the CT or the logical sum of the fan motor output signal, and the provisional operation mode up to the stop of the internal thermostat by the CT input is provided. The device can be repaired while the operation of the harmony device is stopped and cannot be used until the repair is completed and the case can be avoided as much as possible, so that the convenience for the user can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a control circuit of an air conditioner according to the present invention.

FIG. 2 is a flowchart showing the operation of the control circuit of the present invention.

FIG. 3 shows a control circuit of a conventional air conditioner.

FIG. 4 shows a conventional protection circuit for a fan motor.

[Explanation of symbols]

 2 Internal thermo 11 Fan motor

Claims (2)

[Claims] An air conditioner comprising a compressor, an outdoor heat exchanger and a fan motor, and an indoor heat exchanger, wherein when the fan motor of the air conditioner reaches a certain temperature, A method for controlling an air conditioner, wherein an internal thermostat in a fan motor is directly cut off and power supply is stopped. 2. An air conditioner comprising a compressor, an outdoor heat exchanger and a fan motor, and an indoor heat exchanger, comprising: voltage detecting means for detecting a voltage from the fan motor; A method for controlling an air conditioner, comprising: performing a failure prediction based on a voltage to be performed; and performing a provisional operation mode when a failure is predicted.