JPH0887301A - Microcomputer control type heating device - Google Patents

Abstract

PURPOSE: To evade the danger that a heating source is left in a heat generating state by holding the heating source in a heat-generation stop state when a reset signal is inputted to a microcomputer. CONSTITUTION: This heating device is provided with a capacitor 34 for safety decision and deciding circuits 36-38 which judge the charging quantity of the capacitor 34 for safety decision and output heat generation stop signals unless the charging quantity reaches a reference level; and the heating device holds the heating source 1 in the heat generation stop state on condition that the deciding circuits 36-38 output the heat generation stop signals when the microcomputer 6 is reset, and holds the charging quantity of the capacity 34 for safety decision at a level other than the reference level unless the heat generation stop signals are outputted when the output of the deciding circuits 36-38 are judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device such as a stove or a stove, and more particularly to a heating device of a type controlled by a microcomputer. The microcomputer is reset by an abnormal signal or noise of a watchdog circuit. In this case, the heat generation operation is stopped so that a safe state can be secured.

[0002]

2. Description of the Related Art As a heating device such as a stove for controlling a heating operation of a heat source by a microcomputer, a heat source, a control circuit incorporating a microcomputer for controlling the heat source, and a heat generation state of the heat source. There is an abnormality detection circuit for monitoring the above, and an operation switch for applying a power supply voltage to the microcomputer to start it.

In this device, when the operation switch is turned on, a power source voltage is applied to the microcomputer, and at the same time when the power source voltage is applied, the microcomputer starts heating the heat source. Then, when the abnormality detection circuit detects an abnormal operation of the heat source, the heat generating operation is forcibly stopped and a safe state is ensured. However, in the case of the above, when the microcomputer abnormally operates and it is in the reset state, especially when it is reset while the appliance is abnormally stopped, the fever operation is suddenly restarted and the safety state is secured. There was a problem that I couldn't.

The above problems will be described in more detail. The microcomputer has a built-in watchdog circuit that controls its own operation, and the output of the circuit is output from a specific output terminal of the microcomputer. In a general instrument controlled by a microcomputer, a reset circuit for applying a reset signal to a reset input terminal when the watchdog circuit outputs an abnormal signal is externally attached. Therefore, if the microcomputer is reset by noise or an abnormal signal from the watchdog circuit while an abnormal state occurs and the microcomputer keeps the instrument in the forced stop state, the program counter becomes "0". The microcomputer is restarted. Then, the microcomputer re-executes the instruction for causing the heat source to generate heat, and the device that has been forcibly stopped becomes in a heat generation state, and the safe state cannot be secured. [Invention of Claim 1] The invention of Claim 1 is made in view of the above-mentioned point, and has a function of inputting a start signal for starting heat generation of a heat source into a microcomputer and having an operating force. In the case of a microcomputer-controlled heating device equipped with an operation switch of the type in which the above start signal does not disappear even if it is released, in the case where a reset signal is input to the microcomputer, the heat source is maintained in the heat generation stopped state. Therefore, it is an object of the present invention to avoid the risk that the heat source is left in a heat generating state even if the microcomputer resets at the time of abnormal stop.

[0005]

[Technical Means] To solve the above-mentioned problems, the technical means of the invention of claim 1 is "a safety judgment capacitor charged at the time of connection of a power plug and a judgment amount of the safety judgment capacitor. If this is below the reference level, a judgment circuit that outputs a heat generation stop signal and a discharge circuit that discharges the safety judgment capacitor are provided, and even if a start signal is output from the operation switch when the microcomputer is reset, the judgment circuit If the heat generation stop signal is output from the device, the heat source is maintained in the heat generation stopped state, and if the heat generation stop signal is not output when the output of the determination circuit is determined, the discharge circuit is maintained in the operating state. At the same time, the discharge circuit is stopped when the operation switch is turned off. ”

[0006]

The above technical means operates as follows. When the power supply voltage is applied to the heating device by connecting the power plug to the outlet, the safety judgment capacitor starts charging, and when the charging continues and the charged amount reaches the reference level, a signal indicating this state is output. It is output from the determination circuit. Note that the signal output from the determination circuit when the charge amount of the safety determination capacitor is equal to or lower than the reference level is the heat generation stop signal described in the technical means section, and after the safety determination capacitor is charged to the reference level. Indicates that the heat generation stop signal from the determination circuit has disappeared.

Now, when the start signal is output from the operation switch and the microcomputer begins to generate heat from the heat source when the charge amount of the safety judgment capacitor is below the reference level, the heat generation stop signal is output from the judgment circuit at this point. In this case, the heating source continues to generate heat in the same manner as in the conventional case described above, and the heating operation continues. On the other hand, according to the above technical means, when the heat generation stop signal is not output when the output of the determination circuit is determined, the discharge circuit is maintained in the operating state. Therefore, after that, the determination circuit that monitors the output of the safety determination capacitor continuously outputs the heat generation stop signal (a signal indicating that the safety determination consensor is in the discharging state).

When a reset signal is input to the reset input terminal of the microcomputer due to abnormal operation or noise in the above-mentioned state where the heat stop signal is output from the safety judgment circuit, the program counter of the microcomputer is set to " It is reset to "0" and this causes the control program to be re-executed from the beginning. However, since the safety determination capacitor is already in the discharged state and the determination circuit outputs the heat generation stop signal at this time, the heat generation source is maintained in the heat generation stop state when the microcomputer is restarted.

[0009]

The invention of claim 1 has the following unique effect. When the reset signal is input to the microcomputer, the heat source is maintained in the heat generation stopped state, so that it is possible to avoid the risk that the heat source is left in the heat generation state even if the microcomputer performs a reset operation during an abnormal stop.

[0010]

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. It is designed to be supplied with electricity. That is, the operation switch (31)
When the power is turned on, the power supply voltage is supplied to the microcomputer (6) and other circuits incorporated in the control circuit (3), and these start operating. In addition, the control circuit (3)
The output of the safety circuit (4) is applied to the
(4) is a safety judgment capacitor (34) charged by the connection of the power plug (33), and the safety judgment capacitor (34)
The discharge resistance (35) inserted in the circuit connected to the ground from the high potential side of, and the reference voltage setting circuit (36) for setting the reference voltage to be compared with the output of the safety judgment capacitor (34),
The reference voltage setting circuit (36) and the safety judgment capacitor (3
It is composed of a comparator (37) for comparing the outputs of 4) 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 in the section of the technical means. 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) constituting the control circuit (3) and 3
The circuit between 9) and the combustion lamp (41) and the output part of the safety judgment capacitor (34) are connected by a short circuit (43).

In the microcomputer (6) shown in FIG.
A control program having the contents shown in the flowchart of FIG. 3 is stored, and the operation of the stove of the illustrated embodiment will be described below with reference to FIG. When the power plug (33) is connected to an outlet (not shown), the safety judgment capacitor (34) starts to be charged, and when the predetermined charging time (about 1 second) elapses after the power plug (33) is connected, the safety judgment The output voltage of the capacitor (34) for use becomes larger than the output of the reference voltage setting circuit (36), and "H" is output from the comparator (37).

When the operation switch (31) is turned on while the comparator (37) is outputting the "H" signal, the power supply voltage is applied to the microcomputer (6) and the microcomputer (6) starts to operate. The microcomputer (6) is shown in FIG.
Perform step (80). That is, by checking the output of the comparator (37), this is outputting the "H" signal, and the operation switch (31)
If it is determined that the
(81) is executed to drive the igniter (2) and open the gas valve (11) to start combustion of the gas burner (1).
Next, in step (82), the output of the flame detector (21) is checked to see if the gas burner (1) has ignited. Then, if the gas burner (1) is maintained in the combustion state, step (8
In 3), the igniter (2) is maintained in the OFF state and the "L" signal is output to the output port (39). Then the power circuit
(32) → Combustion lamp (41) → Current flows through the output port (39) and the combustion lamp (41) lights up, which causes the gas burner (1)
Is displayed in a burning state. Further, when the output port (39) is in the "L" state, a current flows through the safety judgment capacitor (34) → short circuit (43) → output port (39) and the safety judgment capacitor (34) is in a discharged state. As a result, the "L" signal, which is a heat generation stop signal, is output from the comparator (37). In this embodiment, the capacitor (34)
→ The short circuit (43) → The circuit connected to the output port (39) corresponds to the discharge circuit described in the section of the technical means.

Next, when the gas burner (1) is blown out and the flame detector (21) detects a combustion abnormality while continuing combustion, this is judged in step (84). And by closing the gas valve (11), the gas burner (1) is maintained in the extinguished state,
Further, the combustion lamp (41) is made to blink (step (8
Five)). That is, the combustion lamp (41) is blinked by alternately outputting the "H" signal and the "L" signal to the output port (39) of the microcomputer (6). At the time of this blinking, the time width of the “L” signal is set to be larger than that of the “H” signal.
The output of (34) is prevented from rising to the reference level (output of the reference voltage setting circuit (36)).

Then, when the gas burner (1) is stopped abnormally while the fire is stopped, a reset IC (61) for monitoring the output of the watch dock terminal (63) is activated by noise or the like to activate the microcomputer (6). When the reset signal is input to the reset terminal (64), the control operation is returned to step (80). However, as described above, during abnormal stop, the safety judgment capacitor (34) is maintained in the discharge state in conjunction with the blinking of the combustion lamp (41), so the heat generation stop signal “L” is output from the comparator (7). The signal is being output continuously.
Therefore, in this case, the control operation is moved from step (80) to step (85), the gas valve (11) is maintained in the closed state, and the combustion lamp (41) is maintained in the blinking state. A safe state is secured. After that, when a reset signal is input to the reset terminal (64) of the microcomputer (6), steps (80) and (85) are repeated each time and the gas burner (1)
Is extinguished.

Next, in the stove of the above embodiment, the gas burner (1) can be kept in a fire extinguished state when the power failure that occurred during combustion is restored. In other words, if a power failure occurs during the combustion of the gas burner (1), this will cause a discharge resistance (3
It is completely discharged to the ground side via 5). When the power is restored in this state, the operation switch (3
1) Restarting the power supply from the microcomputer
(6) works immediately, but the microcomputer (6)
Since the safety judgment capacitor (34) is being charged during the operation of, the output thereof has not risen to the reference voltage of the reference voltage setting circuit (36). Therefore, in such a case, when the microcomputer (6) is activated and step (80) is executed, the "L" signal which is the heat generation stop signal is still output from the comparator (37). In this case, step (85) is executed to control the gas valve (11) to be closed. That is, the gas burner (1) is maintained in a fire extinguishing state after the power failure is restored, and thus the risk of the gas burner (1) starting to burn suddenly after the power failure is restored can be avoided.

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 applied to the stove has been described as an example, but the present invention can be applied to a heating device such as a stove or a water heater. Further, in the above-mentioned embodiment, the non-reset type switch in which the contact does not automatically return is adopted as the operation switch, but if a holding circuit for keeping the state where the start signal is output is provided, it is a reset type switch. May be. This is because the holding circuit maintains the output of the start signal even if the operation force applied to the resettable switch is released. [Invention of Claim 2] The invention of Claim 2 is Claim 1
It solves the same problem as the invention of.

[0018]

[Technical Means] According to the technical means of the invention of claim 2, "a safety judgment capacitor discharged when an operation switch is turned off and a charge amount of the safety judgment capacitor are judged, and this is a reference level or more. In the case of, the judgment circuit that outputs the heat generation stop signal and the charging circuit that charges the safety judgment capacitor are provided, and even if the start signal is output from the operation switch when the microcomputer is reset, the heat generation stop signal is output from the judgment circuit. Is maintained, the heat generation source is maintained in the heat generation stopped state, and when the heat generation stop signal is not output when the output of the determination circuit is determined, the charging circuit is maintained in the operating state. That is.

[0019]

[Operation / Effect] The above technical means operates as follows.
When the power plug is connected to the outlet and the operation switch is turned on, control of the heat source by the microcomputer begins. At this time, the safety judgment capacitor is not charged and the judgment circuit does not output the heat generation stop signal. Therefore, in such a case, the heat generation source is not maintained in the heat generation stopped state, and the heating operation is started in the same manner as the conventional one.

On the other hand, according to the above technical means, when the heat generation stop signal is not output when the output of the determination circuit is determined, the charging circuit is activated and the safety determination capacitor is continuously charged. The determination circuit that monitors the output of the safety determination capacitor continues to output the heat generation stop signal. In this case, if the microcomputer malfunctions or becomes reset, the safety judgment capacitor is charged and the heat generation stop signal is output from the judgment circuit when the microcomputer (6) is restarted. The heat generation source is maintained in the heat generation stopped state to ensure a safe state.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the invention of claim 2 will be described with reference to FIGS. This one charges the safety judgment capacitor (34) when the microcomputer (6) is operated, and discharges the safety judgment capacitor (34) when the operation switch (31) is turned off.
The same parts as those in FIG. 1 described above will be described using the same reference numerals.

In this device, electricity is supplied to the power supply capacitor (38) and the circuits below the comparator (37) through the charging transistor (30), and further, the safety judgment capacitor ( A discharge switch (311) is mechanically interlocked with the operation switch (31) to open and close the output switch of (34) and ground. Next, the operation of the stove of the embodiment will be described with reference to the flowchart of FIG.

Even if the power plug (33) is connected to the outlet, it is a charging transistor before the operation switch (31) is turned on.
Since (30) is maintained in the OFF state, the safety judgment capacitor (34) is maintained in the discharged state. When the operation switch (31) is turned on, the discharge switch (311) is kept in the OFF state in conjunction with this, and the microcomputer (6) starts the control operation of FIG. 4, and first, at step (90). The output of the comparator (37) is confirmed. Then, when the safety judgment capacitor (34) is not charged to the reference level and the comparator (37) outputs the "L" signal (it is judged to be immediately after the operation switch (31) is turned on). If)
In step (91), the igniter (2) is driven and the gas valve (11) is opened to start the combustion of the gas burner (1), and the charging transistor (30) is maintained in the ON state. Then, electricity is supplied to the safety judgment capacitor (34) and the power supply capacitor (38) to charge them. In this embodiment, the circuit connecting the charging transistor (30) to the safety judgment capacitor (34) corresponds to the charging circuit described in the technical means section.

Next, in steps (92) and (93), it is judged whether or not the gas burner (1) is ignited based on the signal from the flame detector (21), and if it is in a combustion state, the combustion lamp (41) ) Is turned on to maintain the combustion state. If the gas burner (1) goes into an abnormal state by abnormally extinguishing the gas at step (94), step (95) is executed to close the gas valve (11) and burn the lamp.
Keep (41) flashing. Also, the charging transistor (30) is turned on. Then, when the reset IC (61) operates in this state and the microcomputer (6) enters the reset state, the microcomputer (6) again executes the step (90). However, at this point, the safety judgment capacitor (34) is in a charged state and the comparator (37)
From the "H" signal (in this embodiment, it becomes a heat generation stop signal)
Is output, and in this case, step (95) is repeated to keep the gas burner (1) in a fire extinguishing state.

The fact that an electric heater can be used as a heat source, that the present invention can be applied to a heating device such as a stove or a water heater, and that a resettable switch can be used as an operation switch is an embodiment of the invention of claim 1. Similar to the example.

[Brief description of drawings]

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

FIG. 2 is a flowchart for explaining the control operation of the invention of claim 1.

FIG. 3 is a circuit diagram illustrating an embodiment of the invention of claim 2;

FIG. 4 is a flow chart explaining a control operation of the invention of claim 2;

[Explanation of symbols]

 (6) ・ ・ ・ Microcomputer (31) ・ ・ ・ Run switch (33) ・ ・ ・ Power plug (34) ・ ・ ・ Safety judgment capacitor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G05D 23/19 C

Claims (2)

[Claims] 1. A microcomputer control provided with an operation switch of a type having a function of inputting a start signal for starting heat generation of a heat source to a microcomputer and not losing the start signal even when an operating force is released. In a heating device of the formula, a safety judgment capacitor charged when the power plug is connected, and a judgment circuit which judges the charge amount of the safety judgment capacitor and outputs a heat generation stop signal when this is below a reference level, Provided with a discharge circuit that discharges the safety judgment capacitor, even if a start signal is output from the operation switch when the microcomputer is reset, if the heat generation stop signal is output from the judgment circuit, the heat generation source is stopped If the heat generation stop signal is not output when the output of the determination circuit is determined, the discharge circuit is maintained. Is maintained in an operating state, and the discharge circuit is stopped when the operation switch is turned off. 2. A microcomputer control provided with an operation switch having a function of inputting a start signal for starting heat generation of a heat source to the microcomputer and not losing the start signal even when the operating force is released. In a type of heating device, the safety judgment capacitor discharged when the operation switch is turned off and the charge amount of the safety judgment capacitor are judged, and if this is above the reference level, a judgment is made to generate a heat generation stop signal. A circuit and a charging circuit to charge the safety judgment capacitor are provided.If the heat generation stop signal is output from the judgment circuit even if the start signal is output from the operation switch when the microcomputer is reset, the heat generation source If the heat generation stop signal is not output when the output of the judgment circuit is judged, Is a microcomputer-controlled heating device for maintaining the charging circuit in an operating state.