JPH0443175B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an air conditioner, and particularly to a control circuit for an indoor unit.

[Conventional technology]

Figure 7 is a circuit diagram showing a control device for an indoor unit in a conventional air conditioner, which is shown on page 108 of the 1985 edition of the Mitsubishi Refrigeration and Refrigeration Handbook, for example. A transformer that converts voltage into a low-voltage AC voltage, 3 is an indoor unit control circuit, 4 is a connector for connecting wires, 5 is a fuse, 6 and 9 are connectors provided in the indoor unit control circuit 3, 7 and 8 are This is a connection terminal provided within the indoor unit control circuit 3. 10 and 12 are terminal boards, 11
1 is a remote control, and 13 is an outdoor unit control circuit.

Next, the operation will be explained. The AC voltage supplied from the power supply 1 is stepped down by the transformer 2, thereby becoming two types of low-voltage AC voltages. transformer 2
A connector 4 and a fuse 5 are provided on the connection lines for supplying the low-voltage AC voltage from the indoor unit control circuit 3 to the indoor unit control circuit 3, respectively. One side of this communication line is connected to the connector 6 of the indoor unit control circuit 3, and the other side is connected to the connection terminal 7, so that a low voltage AC voltage is supplied to the indoor unit control circuit 3 through this communication line. Further, a connection terminal 8 and a connector 9 are provided at another position of the indoor unit control circuit 3. The connection terminal 8 is connected to a terminal board 10, and a remote control 11 is connected to this terminal board 10 via a communication line, so that operation data can be transmitted and received between the indoor unit control circuit 3 and the remote control 11 through this communication line. Power is supplied to the remote control. On the other hand, the connector 9 is connected to a terminal board 12, and an outdoor unit control circuit 13 is connected to this terminal board 12, so that the indoor unit control circuit 3 is connected to the outdoor unit control circuit 1 via a communication line.
The driving signal is now sent to 3.

[Problem that the invention seeks to solve]

Conventional air conditioner control devices are configured as described above, so if there is incorrect wiring or short circuit during wiring work between the remote control and the indoor unit control circuit, or between the outdoor control circuit and the indoor control circuit. However, the indoor unit control circuit and remote control were damaged within the time it took for the fuse to blow, and the fuse had to be replaced.

This invention was made to solve the above-mentioned problems, and in the event of incorrect wiring or short circuit during wiring work, the power supply and signals to the remote control and outdoor unit control circuit are immediately cut off, and the indoor unit control circuit is immediately shut off. Another object of the present invention is to provide a control device for an air conditioner that prevents damage to the remote control and eliminates the need for fuse replacement.

[Means for solving problems]

A control device for an air conditioner according to the present invention includes a reset circuit that is operated by the output of a voltage and current detection circuit that detects DC voltage and overload current in the control circuit of the indoor unit, and a reset circuit that operates by the output of the voltage and current detection circuit that detects DC voltage and overload current. Activate the cut-off circuit that cuts off the power supply and operation signal to the outdoor unit control circuit, and set the delay time for turning off the output of the reset circuit to be longer than the time required for the capacitor in the remote control's power supply circuit to completely discharge. This is what I did.

[Effect]

The air conditioner control device according to the present invention operates a reset circuit based on the inputs of the voltage detection and current detection circuits, and switches the voltage level of the output terminal of this reset circuit to operate the cut-off circuit to control the remote control and the outdoor. The power supply to the machine control circuit and the supply of operation signals are cut off, and the delay time set in the reset circuit causes
Even in the absence of voltage and current inputs, the delay time delays switching of the voltage level at the output terminal of the reset circuit to its pre-operational state.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 14 is a full-wave rectifier that converts alternating current into direct current, 15 is a stabilizing power supply circuit that smoothes the direct current voltage obtained by the full-wave rectifier 14, and 1
6 is a voltage detection circuit that generates an output when the DC voltage is lower than the level; 17 is a voltage detection circuit 1
18 is a reset circuit having an input terminal whose voltage level changes depending on the operation of transistor 17 and an output terminal that operates transistor 19; 20 is the output voltage level of the output terminal of reset circuit 18; The microcomputer 21 is reset by the signal output from the transistor 19 and sends an operating signal to the outdoor unit control circuit 13.
a cut-off circuit that cuts off a power cut-off signal of the remote control 11 and an operation signal to the outdoor unit control circuit 13;
22 is Batsuhua.

On the other hand, 23 is a current detection circuit, 24 is a transistor operated by the output of the current detection circuit 23,
It is connected in series with the transistor 17 via a resistor 25, and its collector side is connected to the input terminal of the reset circuit 18. 26 represents a direct current voltage (hereinafter referred to as V _D ), and 27 represents 0V.

FIG. 2 is an electrical circuit diagram of the remote control, and in the figure, 28 is a full-wave rectifier, 29 is a remote control 11
30 is a control circuit for the remote control.

The operation of the circuit with the above configuration will be explained below using the time charts shown in FIGS. 3 and 4.
First, when the DC voltage is lower than the set level,
Since the output signal of the DC voltage detection circuit 16 is supplied to the base terminal of the transistor 17, the transistor 17 is turned off and the voltage level is determined by the ratio of the values of the two resistors 25 connected in series. The voltage that was kept at 0V becomes 0V. As a result of this operation, the voltage at the input terminal of the reset circuit 18 becomes 0V at time _t0 shown in FIG. 3, and the voltage level accordingly becomes "L". At this point, when the output of the reset circuit 18 becomes "H" due to the circuit operation, a reset signal is input to the reset terminal of the microcomputer 20, which is connected to the output terminal of the reset circuit 18 via a resistor 25. . When the microcomputer 20 is reset, it prepares to perform a reset operation to restart operation from the beginning of the program stored in memory, and the transistor 19, which had been off until now, is turned on and the cutoff circuit 21 is turned on. An “L” signal is input. Since the cutoff circuit 21 has an AND circuit configuration, all signals outputted from the cutoff circuit 21 become "L". As a result, the operation of the buffer 22 causes the power line of the remote control 11 and the outdoor unit control circuit 13 connected to this buffer 22 to
The signal line to the terminal becomes "H", and the power supply line connected to the power supply V _D becomes at the same potential, and the potential difference between the terminal boards 10 and 12 becomes 0V.
becomes. As a result, the power supply of the remote control 11 and the signal line to the outdoor unit control circuit 13 are electrically cut off. Next, at time _t1 shown in FIG. 3, when the power supply voltage becomes higher than the set level of the DC voltage detection circuit 16, the potential of the input terminal of the reset circuit 18 rises by the operation opposite to the above, but the reset Due to the delay operation time setting function of the circuit 18, the output terminal voltage of the reset circuit 18 is set to "H".
level is maintained for a delay time, and during this time, the power supply of the remote control 11 and the control signal of the outdoor unit control circuit 13 are kept cut off. In this state, power is not supplied to the remote control 11, so
The voltage that had been operating the control circuit 30 of the remote controller 11, that is, the voltage that had been applied to the capacitor 29, is discharged and gradually approaches 0V. Here, the delay time is the time until the discharge is completed t ₂
(Fig. 3), no malfunction will occur even if an instantaneous voltage drop as described above occurs.

Next, in FIG. 4, when the power is turned on with the connection wires to the remote controller 11 and the outdoor unit control circuit 13 incorrectly wired and shorted, an overcurrent flows through the current detection circuit 23, and at time t ₀ the current An overcurrent detection signal is output from the detection circuit 23, and this output turns on the transistor 24, and the input terminal potential of the reset circuit 18 becomes 0V, that is, "L". After the above operation, the power supply of the remote control 11 and the outdoor The signal line of the control circuit 13 is electrically cut off. As a result, unless the overcurrent continues to flow, the power source of the remote controller 11 and the signal line of the outdoor control circuit 13 are kept electrically cut off, and the potential of the capacitor 29 of the remote controller 11 becomes 0V, so the remote controller does not operate at all.

FIG. 5 is an electric circuit diagram showing another embodiment, in which the outputs from the voltage detection circuit 16 and the current detection circuit 23 are directly input to the microcomputer 20. Furthermore, FIG. 6 shows the operation of another embodiment,
In particular, this is a flowchart when a program programmed in the microcomputer 20 includes a program that performs the same operation as in the above embodiment. In the figure, in step 31, it is determined whether or not there is a voltage input, and only when the result of the determination is NO, the process moves to step 32, and it is determined whether or not there is a current input. Then, only if the determination in step 32 is NO, normal control in step 33 is performed. If the determination in step 32 is YES, all output is stopped in step 34, that is, the power supply to the remote controller 11 and the signal line to the outdoor unit control circuit 13 are cut off. Next, in step 35, the initial setting of normal control is performed, and
Next, in step 36, a timer is set.
After that, the presence or absence of voltage input is determined again in step 37, and if the determination result is NO,
The current input is confirmed in step 38, and the judgment result in either step 37 or 38 is determined.
If YES, return to step 36. Also, if both voltage and current inputs are not available, step 39
to confirm the timer setup, and if the set time has elapsed, go to step 33, and if the set time has not elapsed, go to step 37 again.
Repeat the process of returning to .

〔Effect of the invention〕

As described above, according to the present invention, the voltage in the control circuit of the indoor unit and the current flowing into the remote control and outdoor control circuit are detected, and this detection signal is used to reset the microcomputer 20 of the indoor unit to power up the remote control. In addition to electrically cutting off the signal to the outdoor unit control circuit, the delay time set in the reset circuit was set to be longer than the time required for the remote control's power supply voltage to completely discharge, resulting in incorrect wiring or short circuits in each control circuit. Even if a power supply voltage drops due to an instantaneous voltage drop or the like, each control circuit is always reliably reset, thereby preventing malfunctions and runaway of the microcomputer, thereby increasing reliability. Furthermore, since no fuses are required, the cost is reduced, and there are also advantages such as no need for maintenance such as replacing fuses.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a control device for an air conditioner according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the remote control shown in FIG. 1, and FIGS. 5 is a circuit diagram showing another embodiment, FIG. 6 is a flowchart showing the operation of FIG. 5, and FIG. 7 is a conventional air conditioner control device. FIG. 1 is a power supply, 2 is a transformer, 3 is an indoor unit control circuit,
7 and 8 are connection terminals, 9 is a connector, 10 and 12 are terminal boards, 11 is a remote control, 13 is an outdoor unit control circuit, 14 is a full-wave rectifier, 15 is a stabilized power supply circuit,
16 is a voltage detection circuit, 17, 19, 24 are transistors, 18 is a reset circuit, 20 is a microcomputer, 21 is a cut-off circuit, 22 is a buffer, 23 is a current detection circuit, 25 is a resistor, 26,
27 indicates the level of DC voltage. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A transformer that steps down the AC power source, a full-wave rectifier that full-wave rectifies the low-voltage AC power source obtained by the transformer, and a predetermined digital voltage source that operates with the DC voltage source obtained by the full-wave rectifier. In a control circuit for an air conditioner having a microcomputer that performs arithmetic processing, the voltage detection circuit detects the voltage level of the DC voltage, the current detection circuit detects overload current, and the voltage detection circuit and current detection circuit. a reset circuit that outputs a reset signal to the reset terminal of the microcomputer operated by either or both of the signals, and outputs a control signal for cutting off the power supply of the remote control and the operation signal output from the microcomputer; 1. A control device for an air conditioner, comprising: a cut-off circuit for cutting off an operation signal.