JPH01239317A - Combustion control device - Google Patents

Abstract

PURPOSE:To prevent fuel from being discharged even when a control circuit malfunctions, by regulating a solenoid valve according to fixed signal generated corresponding to the start of combustion, and a frame signal detecting the flame of a burner. CONSTITUTION:When an operation switch 43 is turned ON, a fixed signal circuit 50 transmits a power source voltage V as an operation signal from terminal 44 to a CPU. And, the base of a transistor 50d is impressed and is turned ON causing a capacitor 51 to be discharged. Therefore, the electric potential of a positive input terminal 52a on a comparator 52 falls causing an output terminal 52c to go to L level. A timer circuit 60 reduces the electric potential of an positive input terminal 61a on a comparator 61. In case the electric charge of a condenser 62 is discharged, that is, when the output of the fixed signal circuit 50 goes to L level, the flame signal is transmitted from a flame detecting circuit through a terminal 66 causing a transistor 65 to turn on a switching circuit, so that the L level signal is generated. As for a solenoid valve power supply circuit 70, when the L level signal is input to a transistor 72 and H level signal to a terminal 74 as a signal of 'solenoid valve open', a transistor 75 becomes ON, so that power is supplied to solenoid valves through a relay 71.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a combustion control device that automatically ignites based on a signal S such as an operation switch operated by a user, and particularly to a combustion control device that The present invention relates to a combustion control device that, once started, continues to burn until the operation switch is turned on.

[Prior Art] In a combustion control device that automatically ignites the burner by controlling a solenoid valve that controls fuel supply to the burner and an ignition device that ignites the burner, if the flame goes out for some reason, To ensure safety, the solenoid valve's energizing circuit is equipped with a safety circuit that includes a flame rod that detects the burner flame, and the safety circuit controls the solenoid valve in response to control signals from the control circuit. When the burner flame is detected, the solenoid valve is continuously energized, and when the burner flame is no longer detected, the solenoid valve is de-energized regardless of the control signal from the control circuit.

In order to supply fuel to the burner even during ignition when no flame is detected, the control signal of the control circuit is as follows.
A separate ignition signal is sent to the safety circuit and replaces the flame detection signal.

[Problems to be Solved by the Invention] Conventionally, the safety circuit can close the solenoid valve and stop the fuel supply when the burner flame is no longer detected. Since the solenoid valve can be opened with just a signal, if the control circuit malfunctions and sends out the control signal that opens the solenoid valve and the ignition signal at the same time regardless of the operation of the ignition device, the solenoid valve will open. There is a problem that the valve becomes closed jf3 and fuel flows out.

An object of the present invention is to provide a combustion control device that can prevent fuel outflow even if a control circuit malfunctions.

[Means for Solving the Problems] The present invention provides a solenoid valve provided in a fuel supply path to a burner, a flame detection means for sending out a flame detection signal when detecting a flame in the burner, and a flame detection means for transmitting a flame detection signal when detecting a flame in the burner. a combustion start means for sending a combustion start signal to start combustion; an ignition means for igniting the burner; and a combustion start means for controlling the electromagnetic valve and the ignition means based on the combustion start signal, and igniting the burner. a signal generating means that generates a fixed signal based on the combustion start signal; and a signal generating means that generates a fixed signal based on the combustion start signal; signal stopping means for stopping the signal; timer means for sending an output signal when either the flame detection signal or the fixed signal is input and at a certain time after the input is stopped; and the control means controls the solenoid valve to be in an open state and a solenoid valve driving means which opens the solenoid valve when a solenoid valve control signal is sent out to control the solenoid valve and an output signal is sent out from the timer means.

[Function] According to the present invention, when a combustion start signal is sent from the combustion start means, a fixed signal is generated from the signal generation means, the control means controls the C solenoid valve and the ignition means, and the ignition operation of the burner is performed. done automatically.

At this time, the timer means generates an output signal based on the fixed signal, but when the ignition activation signal is sent out in conjunction with the ignition operation of the control means, the fixed signal is stopped by the signal stop means, so that the output signal remains constant thereafter. Generates an output signal in time. Then, the solenoid valve 1 driving means opens the solenoid valve according to the output signal of the timer means and the solenoid valve control signal of the control means, and the burner is ignited within a certain period of time when the output signal is sent from the timer means, and flame is detected. When detected by means,
The timer means sends out an output signal based on the flame detection signal of the flame detection means.

Therefore, the solenoid valve is kept open while the flame is detected, and if the flame goes out for some reason, even if the control means sends a signal S to open the solenoid valve, the solenoid valve remains open. Not be left behind.

[Effects of the Invention] According to the present invention, when the flame of the burner is not detected, the solenoid valve is not opened unless a fixed signal is sent from the combustion starting means. Therefore, even if the control means malfunctions and sends out a control signal to open the solenoid valve, no fixed signal is sent out, so it is possible to prevent fuel from flowing out.

[Example] Next, a combustion control device of the present invention will be described based on an example shown in the drawings.

The gas hot air pump 1 shown in FIG. 2 is composed of a heater main body 20 including a combustor 10, a gas supply path 30, and a control device 40.

The combustor 10 is of a forced air type that sucks air from outside with a combustion fan 11 and supplies it into the combustion chamber B10, and the combustion exhaust gas combusted in a ceramic burner 12 passes through a heat exchanger 13. The air is exhausted from the exhaust port 14 to the outside.

A sparker 15 as an ignition means is provided near the burner 12, and a thermocouple 16"F+ detects the flame based on the combustion temperature, and the signal is sent to the control device 40.
send to

The heater main body 20 uses a convection fan 21 to circulate warm air indoors to introduce indoor air from an air inlet 22, and to mix it with high-temperature combustion gas passing through the heat exchanger 13 of the combustor 10. Heat is exchanged and the hot air is sent indoors from the hot air outlet 23.

The gas supply path 30 is a gas pipe 31 that supplies fuel gas supplied from a not-shown fuel supply source into the combustor 10. This gas pipe 31 is provided with a 7L solenoid valve 32 and a main solenoid valve 33 from the downstream side, and these solenoid valves supply fuel gas to the burner 12 when energized, and cut off the fuel gas when not energized. Further downstream, a governor valve 34 for supplying fuel gas at a constant pressure, and a proportional valve 35 for adjusting the supply amount of fuel gas according to the energized current are provided.
The upstream and 1st streams are connected by a bypass pipe 36, and an orifice 37 is provided in the bypass pipe 36 to allow a constant flow rate of fuel gas to pass therethrough.

The fuel gas that has passed through the gas supply path 30 is transferred to the combustor 10 from a nozzle 38 provided in the outside air introduction path 17 of the combustor 10.
supplied within.

As shown in FIG. 1, the control device 40 includes a microcomputer (hereinafter referred to as CPU) 80, a flame detection circuit 41, a sparker drive circuit 42, a fixed signal circuit 50,
It consists of a timer circuit 60 and a solenoid valve energizing circuit 70.
The control device 40 is operated by an operation switch 43, and the control device 40 also includes a combustion temperature thermistor (not shown),
Equipped with a blowout air temperature thermistor and temperature control volume.

The flame detection circuit 41 detects that the thermocouple 16 is heated by the combustion of the burner 12, and its output voltage is a predetermined voltage amount.
, a flame detection signal is generated and transmitted to the CPU 80 and the timer circuit 60.

The sparker drive circuit 42 drives a circuit that generates a high voltage in order to cause a spark discharge to the discharge gap of the sparker 15, and is activated when an H level control signal is transmitted from the CPtJ80. A spark discharge occurs in the gap.

Fixed signal same ii! 850, the timer circuit 60, and the solenoid valve energizing circuit 70 are comprised of the circuits shown in FIG.

The fixed signal circuit 50 generates an output signal when the operation switch 43 is closed, and stops outputting the signal when a sparker activation signal as an ignition activation signal is transmitted from the CPU 80. explain.

When the operation switch 43 is closed to operate the gas warm air heater 1, the power supply voltage V is sent from the terminal 44 to the CPU 80 as an operation signal. Further, the power supply voltage (2) applied to the resistor boa is applied to the base of the transistor 50d via the resistor 50b and the capacitor bOc, and a base current flows through the transistor 50d. Then, the transistor 50d is turned on, and if the capacitor 51 has charge, the charge is discharged. Therefore, the potential of the positive input terminal 52a of the comparator 52 becomes low, and the resistor 53
It becomes lower than the reference voltage on the negative input terminal 52b side set by a and 53b.

At this time, the output terminal 52 of the comparator 52 is I7.
Since the resistor 54 will be grounded by the diode 55, the capacitor 51 will not be charged by the diode 56, and therefore the comparator 52 will maintain the level.

The charge in the capacitor 51 is discharged by the transistor 50d. However, the transistor 50d is ON only for a limited time until the capacitor 50c is charged. When the capacitor 51 is closed, it is opened by -degree and the capacitor 51 is not charged until the operation switch 43 is closed again, so that the capacitor 51 is discharged only when the operation switch 43 is closed.

When the CPU 80 generates an H level control signal for operating the C and sparker 15 according to a predetermined sequence and transmits it to the terminal 45, the capacitor 51 is charged via the resistor 57 and the diode 58.

When the charging potential of the capacitor 51 rises due to this charging and becomes higher than the reference potential on the negative input terminal 52b side, the comparator 52 inverts its output and becomes an output of H1/bell. Then, the potential of the cathode 55a of the diode 55 rises, so that the resistor 54 is no longer grounded, and the potential of the anode 56a of the diode 56 also rises. Therefore, since the power supply voltage V is applied to the capacitor 51 via the resistor 54 and the diode 56 and the capacitor 51 is further charged, the comparator 5
The output of No. 2 is fixed at I (level).The state of this output at H level does not change unless the charge in the capacitor 51 is discharged and the voltage drops below the reference voltage, so it remains at H level until the operation switch 43 is closed again. will continue to be fixed.

The timer circuit 60 controls, together with the CPU 80, the energization of each solenoid valve by the solenoid valve energizing circuit IO, which will be described later. A low level output signal is generated.

This L level output signal is output when the potential of the positive input terminal 61a of the comparator 61 is lower than the reference voltage set by the resistors 62a and 62b.
The potential of 1a becomes low in the next case when the charge in the capacitor 63 is discharged.

In the first case, the output of the fixed signal circuit 50 is at level 7; in this case, the potential of the cathode 64a of the diode 64 connected to the output terminal 52c of the comparator 52 decreases, The charge in capacitor 63 connected to 64b is discharged. Conversely, if the output of the comparator 52 becomes 1 (level
Since a potential difference in the opposite direction occurs in the diode 64, the capacitor 63 is not charged.

In the second case where the charge in the capacitor 63 is discharged,
This is when the switching circuit formed by the transistor 65 is turned on. A flame detection signal from the flame detection circuit 41 is transmitted to the base 65a of the transistor 65 via a terminal 66. Therefore, whenever a flame is detected in the burner 12, the timer circuit 60 is activated and generates an output signal at the L level.

The timer circuit 60 continues to generate output signals for a certain period of time T1 even after these signals stop.

The solenoid valve energizing circuit 70 energizes the relay 71 based on control signals from the timer circuit 60 and the CPU 80 to energize each solenoid valve connected to a contact point (not shown). In this solenoid valve energizing circuit 70, the transistor
The output of the timer circuit 60 is transmitted to the base 72a of the stuff 2 via a resistor 73, and the solenoid valve opening signal from the CPU 80 is transmitted to the terminal 74. and) When an L level signal is input to the Langistav 2 and an H level signal is input to the terminal 74 as a solenoid valve open signal, the transistor 75 is turned on and energizes the relay 71 to energize each solenoid valve. Is going. Therefore, even if the electromagnetic valve opening signal is transmitted to the terminal 74, if the flame detection signal from the flame detection circuit 41 disappears and the output of the timer circuit 60 is at H level, each electromagnetic valve is not energized.

The CPU 80 energizes the combustion fan 11, the sparker drive circuit 42, the convection fan 21, the main solenoid valve 32, the main solenoid valve 33, and the proportional valve 35 according to a predetermined operating sequence, and also energizes the combustion temperature thermistor, the blowout air temperature thermistor, Based on signals from the temperature control volume and thermocouple 16, combustion and ventilation are performed according to the set conditions.

Next, the operation of the control device 40 in the gas hot air heater 1 of this embodiment having the above configuration will be explained based on FIG. 4.

When the operation switch 43 is turned off at time t1, the CPU 80 starts operating in a predetermined sequence, and the combustion fan 11 rotates. In addition, the transistor 50d is connected to the capacitor 50.
The state is ON for the charging time of c, and this operation discharges the charge in the capacitor 51, and the fixed signal circuit 50
The output of becomes [, level. L of this fixed signal circuit 50
The level output is maintained as it is until a sparker activation signal is output under sequence control of the CPU 80.

On the other hand, the output of the timer circuit 60 becomes L level at time t1 when the output of the fixed signal circuit 50 becomes L level, and the output of the fixed signal circuit 50 becomes L level. The L level is maintained according to the level output.

At time t2, the sparker activation signal and the solenoid valve opening signal are H.
When the level signal is output from the CPU 80, the output of the fixed signal circuit 50 becomes H level, but since the timer circuit 60 continues to output the L level for a certain period of time T, the solenoid valve energizing circuit 70 Open the solenoid valve.

Therefore, fuel gas is supplied to the burner 12 together with combustion air supplied by the combustion fan 11 and ignited by the sparker 15.

At time t, thermocouple 16 is activated by the flame of burner 12.
When the flame detection circuit 41 is heated and an output of a predetermined voltage or higher is output from the flame detection circuit 41, an H level output signal is generated as a flame detection signal. As a result, the sparker activation signal stops, and the timer #150 continues to change to L level due to the flame detection signal.
Even after time t4, which is a predetermined period of time T1 from time t2, the I level continues to be output. During operation, if the flame goes out at time t for some reason, the output of the flame detection circuit 41 becomes L level, and based on that signal, the CP
A level signal is sent from U80 as a solenoid valve closing signal, and the solenoid valve becomes closed. After this, the timer circuit 60
The output of is inverted to H level at time t6 when the predetermined time T1 has elapsed.

Therefore, leakage of fuel gas can be prevented.

Also, time t5. Even if the sparker activation signal or solenoid valve opening signal is sent irregularly due to a malfunction of the CPU 80, there is no flame detection signal or fixed signal from the fixed signal circuit 50 to output the L level from the timer circuit 60. Therefore, the solenoid valve is closed and fuel does not flow out.

In this way, once the flame is no longer detected, the solenoid valve is never opened, so even if each signal is sent due to a malfunction of CI) U 80, fuel gas will not flow out.

Thereafter, when the user operates the operation switch 43 again, a fixed signal is generated from the fixed signal circuit 50, and the ignition operation can be performed again under the control of the CPU 80.

As described above, in the present invention, once operation is started and combustion is started, each electromagnetic valve is not energized unless flame is detected. Therefore, the CPU of the control device 40
Even if 80 malfunctions and a sparker activation signal or solenoid valve open signal is generated, once the flame goes out, the solenoid valve will not be opened unless the operation switch 43 is operated, so fuel gas will not flow out. There isn't.

In this embodiment, a sparker operation signal is used as the ignition operation signal, but any control signal associated with the ignition operation, such as an electromagnetic valve opening signal or a sparker operation detection signal, may be used.

In addition, an operation switch was used as a means to start combustion, but
Even when combustion is started by timer operation, control can be performed in exactly the same way.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the operation of the main parts of the control device of this embodiment, Fig. 2 is a configuration diagram showing the gas hot air fan of this embodiment, and Fig. 3 is a block diagram showing the operation of the main parts of the control device of this embodiment. The partial circuit diagram shown in FIG. 4 is a time chart 1 for explaining the operation of this embodiment. In the figure, 32... Original solenoid valve, 33... Main solenoid valve, 41...
... Flame detection circuit (flame detection means), 43 ... Operation switch (combustion start means), 50 ... Fixed signal circuit (signal train generation means, signal stop means), 60 ... Timer circuit (timer means) ), 70... Solenoid valve energizing circuit (solenoid valve driving means)
, 80・Microcomputer (control means).

Claims (1)

[Claims] 1) a solenoid valve provided in a fuel supply path to a burner; a flame detection means for sending a flame detection signal when detecting a flame in the burner; and for starting combustion in the burner. combustion start means for sending out a combustion start signal; ignition means for igniting the burner; and controlling the solenoid valve and the ignition means based on the combustion start signal to automatically ignite the burner. a control means; a signal generation means for generating a fixed signal based on the combustion start signal; and a signal for stopping the fixed signal when an ignition activation signal sent from the control means in conjunction with the ignition operation of the control means is input. a stop means; a timer means for sending an output signal when either the flame detection signal or the fixed signal is input and at a certain time after the input is stopped; and a solenoid valve that is controlled by the control means to open the solenoid valve. A combustion control device comprising electromagnetic valve driving means for opening the electromagnetic valve when a control signal is sent and an output signal is sent from the timer means.