JPH0886438A - Heating device - Google Patents

Abstract

PURPOSE: To prevent a dangerous condition in which a heating device is left at its heated condition after its power failure is recovered in the heating device in which there is provided a control circuit to which a power supply voltage is applied through a operation switch that is not automatically restorable and the control circuit starts to perform a heating operation of a heat generating source when the power supply voltage is applied to the control circuit. CONSTITUTION: There are provided a capacitor 34 for discriminating a power failure state electrically charged when a power supply plug is connected, an electrical discharging resistor 35 for electrically discharging electrical charge stored in the capacitor 34 for discriminating the power failure to its ground terminal, a reference voltage setting circuit 36 for discriminating an electrical charged amount of the capacitor for discriminating the power failure and producing a power failure signal in the case that the capacitor is not electrically charged to its reference level and a discriminating circuit comprised of a comparator 37. When the power supply voltage is applied to the control circuit 3, if the power failure signal is being produced from the discriminating circuit, the heat generating source is kept at a heat generation stopped state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for a stove, a stove or the like, and more particularly to a heating device which prevents the risk of being left in a heat-generating state after a power failure is restored.

[0002]

2. Description of the Related Art As a heating device for a stove or the like of which instrument operation is controlled by a microcomputer, a heat source, a control circuit incorporating a microcomputer for controlling the heat source, and a control circuit Some operation switches are configured to apply a power supply voltage to start them, and some of the operation switches are non-reset type switches, such as seesaw switches, whose contacts do not automatically return.

In this device, when the operation switch is turned on, a power supply voltage is applied to the control circuit, and at the same time when the operation of the control circuit is started, this starts controlling the heat source. The reason why the control circuit is not energized until the operation switch is turned on is to avoid the risk that the control circuit suddenly starts to operate and the heat generation operation starts due to noise or the like when the device is not used. However, in the case of the above, the operation switch does not automatically return to the OFF state even if a power failure occurs during operation, so the power supply voltage is automatically reapplied to the control circuit via the operation switch when the power is restored. Therefore, there is a problem that the heat source is left in a heat generating state, which is not preferable for safety measures.

The present invention has been made in view of the above points. "A control circuit to which a power supply voltage is applied through a non-reset type operation switch in which contacts are not automatically restored, and an operation control by the control circuit In a heating device that has a heat source that supplies heat to the control circuit and the control circuit starts the heat generating operation of the heat source when the power supply voltage is applied to the control circuit, it is safe to prevent the heat source from being left in a heat-generating state when the power is restored. The task is to ensure the condition. [Invention of Claim 1]

[0005]

[Technical Means] To solve the above-mentioned problems, the technical means of the invention of claim 1 is "a power failure judgment capacitor charged at the time of connection of a power plug and an electric charge accumulated in the power failure judgment capacitor to ground. When the power supply voltage is applied to the control circuit, a judgment circuit is provided to judge the discharge resistance discharged to the side and the amount of charge of the above power failure judgment capacitor and output a power failure signal if this is not charged to the reference level. When the power failure signal is output from the judgment circuit, the heat source is kept in the heat generation stopped state. ”

[0006]

The above technical means operates as follows. When power is supplied to the heating device by connecting the power plug to the outlet, charging of the power failure determination capacitor begins, and a power failure signal is output from the determination circuit that monitors the output until this charge reaches the reference level. The Rukoto. Then, when the capacitor for power failure determination is continuously charged and the charged amount reaches the reference level, the power failure signal from the determination circuit disappears.

Now, when the operation circuit is turned on and the control circuit starts controlling the heat source after the judgment circuit does not output the power failure signal, the judgment circuit does not output the power failure signal at this point. Therefore, the control for maintaining the heat generation source in the heat generation stopped state is not executed, and the heat generation source is maintained in the heat generation state as in the above-described conventional one, and the heating operation is continued.

Next, when a power failure occurs during the above heating operation and electricity is no longer supplied to the power failure determination capacitor, the charge stored in the power failure determination capacitor is discharged to the ground side through the discharging resistor. . If the operation switch is left turned on when the power failure continues, when the power failure is restored, the control circuit is simultaneously supplied with electricity and starts to operate. However, when the power is restored, the charge amount of the power failure determination capacitor does not reach the reference level, and a predetermined charging time is required until the reference level is reached. Therefore, the determination circuit that monitors the output of the power failure determination capacitor remains in the state of outputting the power failure signal until the charging time elapses after recovery from the power failure, and the heat source generates heat by the power failure signal. It is kept in a stopped state.

[0009]

The invention of claim 1 has the following unique effect. Even if the operation switch is turned on after the power failure is restored, the heat source is not left in the heat generation state, so safety after power failure is secured. [Invention of Claim 2] The invention of Claim 2 solves the same problem as the invention of Claim 1 above.

[0010]

[Technical Means] The technical means of the invention according to claim 2 is "a power failure judgment capacitor charged when a power plug is connected,
A judgment circuit that judges the amount of charge of the power failure judgment capacitor and outputs a power failure signal if it is not charged to the reference level and a discharge circuit that discharges the power failure judgment capacitor are provided, and power is supplied to the control circuit. Sometimes when the power failure signal is output from the determination circuit, the heat source is maintained in the heat generation stopped state, and the discharge circuit is maintained in the operating state after the output of the determination circuit is determined.

[0011]

According to the above technical means, when the operation switch is turned on and the power supply voltage starts to be applied to the control circuit,
When the output of the determination circuit for determining the charge amount of the power failure determination capacitor is determined and the power failure determination capacitor is charged and the power failure signal is not output from the determination circuit, the heat source is set as in the invention of claim 1. Heat up.

On the other hand, according to the above technical means, the discharge circuit for continuously discharging the electric charge of the power failure judging capacitor operates after judging the output of the judging circuit.
Therefore, when a power failure occurs after the discharge, the power failure determination capacitor is already maintained in the discharged state. That is, even after the occurrence of a power failure, there is no circuit for flowing the charge of the power failure determination capacitor to the ground side, the capacitor will be in a discharged state. Therefore, at the time when the power failure is restored and the power supply to the control circuit is started, the charge amount of the power failure determination capacitor does not reach the reference level as in the invention of claim 1, which causes the heat source to stop generating heat. The state is maintained and the safe state is secured.

[0013]

EXAMPLES Next, examples in which the present invention is applied to a stove will be described. As shown in Fig. 1, a gas valve (11) is inserted in the gas circuit (10) to the gas burner (1), which is a heat source, and it is ignited in the vicinity of the gas burner (1). An igniter (2) and a flame detector (21) are provided.

The gas valve (11) and the like are microcomputers.
It is designed to be controlled by a control circuit (3) that incorporates (6), and the control circuit (3) is connected from the power supply circuit (32) via a seesaw-type operation switch (31) whose contacts do not automatically return. Power supply voltage is applied. That is, the operation switch (3
By turning on (1), electric power is supplied to the microcomputer (6) incorporated in the control circuit (3) and other circuits so that they start operating. or,
The output of the power failure determination circuit (4) is applied to the control circuit (3), and the power failure determination circuit (4) is charged by the power plug (33) when connected to the power failure determination capacitor (34). When,
A reference voltage setting circuit for setting a reference voltage to be compared with the discharge resistance (35) inserted in the circuit connected to the ground from the high potential side of the power failure determination capacitor (34) and the output of the power failure determination capacitor (34). (36) and a comparator (37) for comparing the outputs of the reference voltage setting circuit (36) and the power failure judgment capacitor (34)
And a power supply capacitor (38) for applying a voltage to the comparator (37) and the like. In this embodiment, the set of the reference voltage setting circuit (36), the comparator (37) and the power supply capacitor (38) corresponds to the determination circuit described as the technical means of claim 1. Further, the combustion lamp (41) which is supplied with electricity from the power supply circuit (32) is connected to a specific output port (39) of the microcomputer (6) which constitutes the control circuit (3) and the output port (39 39) and the above combustion lamp (4
The circuit between 1) and the output of the power failure determination capacitor (34) are connected by a short circuit (43).

A control program having the contents shown in the flow chart of FIG. 2 is stored in the microcomputer (6) constituting the control circuit (3), and the operation of the stove of the illustrated embodiment will be described below with reference to FIG. To do. Power plug (3
If you connect 3) to the outlet, the power failure judgment capacitor (34)
The charging starts and the output gradually increases. And, while the output of the power failure judgment capacitor (34) is lower than the output voltage of the reference voltage setting circuit (36) which is the reference voltage, the comparator
An "L" signal which is a power failure signal is output from (37), and this is monitored by the microcomputer (6) of the control circuit (3).
Then, after connecting the power plug (33) for a predetermined time (about 1
After the elapse of seconds, the output voltage of the power failure judging capacitor (34) becomes larger than the output of the reference voltage setting circuit (36), and "H" is output from the comparator (37). That is, the "L" signal, which is a power failure signal, is not output from the comparator (37).

Now, when the operation switch (31) is turned on after the comparator (37) does not output the power failure signal, the microcomputer (6) to which the power supply voltage is applied through the operation switch (31). Starts to work. Then, the microcomputer (6) executes the step (80) of FIG. That is, when the output of the comparator (37) is checked and the comparator (37) does not output the power failure signal (when the comparator (37) outputs the “H” signal), the step (81) is executed. Run and Igniter (2)
Drive the gas burner and open the gas valve (11).
Start the combustion of (1). This starts the heating operation. Next, in step (82), it is confirmed by looking at the output of the flame detector (21) whether the gas burner (1) is in the ignition state. When the gas burner (1) is maintained in the combustion state, the igniter (2) is maintained in the OFF state and the "L" signal is output to the output port (39) in step (83). Then the power circuit (32) → combustion lamp (41) → output port (39)
And the electric current flows and the combustion lamp (41) lights up.
It is displayed that the gas burner (1) is being maintained in combustion condition. When the output port (39) is in the "L" state, a current flows through the power failure determination capacitor (34) → short circuit (43) → output port (39) and the power failure determination capacitor (34) is in a discharged state. As a result, the "L" signal is output from the comparator (37). In this example, the capacitor (3
The circuit connected to 4) → short circuit (43) → output port (39) corresponds to the discharge circuit described as the technical means of the invention of claim 2.

Next, when a power failure occurs in the above-mentioned state where the gas burner (1) is burning, if electric charge remains in the power failure determination capacitor (34), this is connected to the ground side via the discharge resistor (35). Can be completely discharged. When the power failure is restored in this state, the microcomputer (6) operates immediately by restarting the power supply from the closed operation switch (31) .However, when the microcomputer (6) is operating, the power failure judgment capacitor ( Since 34) is being charged, its output has not risen to the reference voltage of the reference voltage setting circuit (36). Therefore, in such a case, when the microcomputer (6) reactivates and executes step (80), the comparator (37) outputs the "L" signal which is the power failure signal. In this case, step (85) Is executed by the gas valve (1
Keep 1) closed and let the combustion lamp (41) blink. That is, the output port (3
The combustion lamp (41) is made to blink by alternately outputting the "H" signal and the "L" signal to 9). At the time of this blinking, the time width of the "L" signal is set to be larger than that of the "H" signal, which causes the output of the safety judgment capacitor (34) to reach the reference level (reference voltage setting circuit (36 ) Output).

On the other hand, when the gas burner (1) burns normally and the flame detector (21) no longer detects the combustion state, this is judged in step (84) and the gas valve
The gas burner (1) is kept extinguished by closing the valve (11) (step (85)). Then, while maintaining the gas burner (1) in the fire extinguishing state, the reset IC (61) that monitors the output of the watchdog terminal (63) operates and resets the reset terminal (64) of the microcomputer (6). When the signal is input, the control operation is returned to step (80). However,
After executing step (83) as described above, output terminal (3
Since 9) is maintained in the “L” state,
After the execution of (83), the power failure determination capacitor (34) is maintained in the discharged state and the comparator (7) continuously outputs the "L" signal which is a power failure signal. Therefore, in this case, step (8
The control operation is moved from 0) to step (85) and the gas valve (11) is maintained in the closed state, whereby the safe state is secured.

In the above embodiment, the gas burner (1) was used as the heat source, but it goes without saying that an electric heater can be used instead. Further, in the above embodiment, the case where the present invention is implemented as a stove is described as an example,
The present invention can be applied to a heating device such as a stove or a water heater.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control operation.

[Explanation of symbols]

 (1) ・ ・ ・ Gas burner (2) ・ ・ ・ Igniter (34) ・ ・ ・ Capacitor for power failure judgment (35) ・ ・ ・ Discharge resistance

Claims (2)

[Claims] 1. A control circuit to which a power supply voltage is applied via a non-reset type operation switch in which contacts are not automatically restored, and a heat source whose operation is controlled by the control circuit are provided, and the power supply voltage is applied to the control circuit. In the heating device in which the control circuit starts the heat generation operation of the heat source when the power source is connected, the capacitor for power failure determination that is charged when the power plug is connected, and the charge stored in the capacitor for power failure determination are discharged to the ground side. A judgment circuit is provided to judge the amount of charge of the discharge resistance and the above-mentioned power failure judgment capacitor and to output a power failure signal when this is not charged to the reference level, and when the power supply voltage is applied to the control circuit, a power failure will occur from the judgment circuit. A heating device that keeps the heat source stopped when a signal is output. 2. A control circuit to which a power supply voltage is applied via a non-reset type operation switch whose contacts do not automatically recover, and a heat source whose operation is controlled by the control circuit are provided, and the power supply voltage is applied to the control circuit. In the heating device in which the control circuit starts the heat generation operation of the heat generation source, the power failure determination capacitor to be charged when the power plug is connected, and the charge amount of the power failure determination capacitor are determined to reach the reference level. A judgment circuit that outputs a power failure signal when not charged and a discharge circuit that discharges the power failure judgment capacitor are provided.If a power failure signal is output from the judgment circuit when power is supplied to the control circuit, the heat source is turned on. A heating device which maintains a heat generation stopped state and also maintains a discharge circuit in an operating state after determining the output of the determination circuit.