JPS6030598Y2 - Combustion control circuit - Google Patents

Description

[Detailed explanation of the idea] [Technical field of invention] The present invention relates to a control circuit for a kerosene-fired combustor.

[Technical background and problems of the invention]

Conventionally, this type of combustion control circuit has an ignition transformer for igniting the burner, a burner fan motor for supplying air to the burner, and an electromagnetic pump for supplying kerosene. It is configured.

In particular, since the burner control sequence circuit, temperature adjustment circuit, and bilimiter circuit are integrated, if one part of the control circuit breaks down, the entire operation will be affected, which poses a particular safety problem. there were.

Furthermore, if the relays that turn on and off the power supply to the electromagnetic pump were welded, etc., and kerosene was allowed to flow out, a deflagration phenomenon would occur when the igniter was activated, which was extremely dangerous.

[Purpose of invention]

The present invention was developed to solve these conventional problems, and by making the temperature adjustment circuit and the bi-limiter circuit separate, and by providing a safety circuit that can stop the operation of the combustor main body in the event of an abnormality. The purpose is to provide a combustion control circuit with high reliability and safety.

[Summary of the idea]

In order to achieve the above object, the present invention has an electromagnetic supply circuit to which the burner fan motor FM that supplies air to the combustion chamber, the electromagnetic pump SP that supplies kerosene, and the ignition transformer Ig are connected, and the ignition transformer operates. Detection by an electromagnetic pump operation circuit 4 that operates the electromagnetic pump after a predetermined time Tp, an ignition transformer operation stop circuit 5 that operates the electromagnetic pump and stops operation of the ignition transformer after a predetermined time Ti, and a first temperature detector TH. A temperature adjustment circuit 3 that compares the temperatures at a first level by a first comparator IC2 and controls the operating time of the burner fan motor and the electromagnetic pump based on the comparison result, and a temperature detected by the first temperature detector. switch means (transistor Q2) that stops the electromagnetic pump by stopping the power supply to at least the electromagnetic pump operating circuit when the temperature is equal to or higher than the first level; The comparator IC□ compares the temperature at a second level higher than the first level, and when the temperature detected by the second temperature detector exceeds the second level, the power supply to at least the electromagnetic pump is stopped. A bi-limiter circuit 2, a flame detection circuit 6 that detects a flame and outputs a signal, and a flame detection circuit that detects a flame when the flame detection circuit does not output a detection signal when the electromagnetic pump operation circuit is in operation and when the electromagnetic pump operation circuit is inactive. outputs a detection signal, for example, by opening contact RL42, the power supply to the burner fan motor and electromagnetic pump is stopped, and the electromagnetic pump operation circuit is activated to stop the operation of the electromagnetic pump (in the embodiment, contact R
L4. The present invention provides a combustion control circuit including a safety circuit 7 (which is performed by opening a contact RL21 by closing the safety circuit 7).

[Example of idea]

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

The embodiment shown in FIG. 1 includes a combustor main body BOD connected to the AC side of the power source, and a rectifier C that converts AC voltage into DC voltage.
A constant voltage circuit 1 that makes the output of V a constant voltage, and a bi-limiter circuit 2 that stops power supply to the combustor main body BOD when the temperature becomes extremely high due to trouble in other parts of the control circuit, especially the temperature adjustment function. , a temperature adjustment circuit 3 that controls the operation time of the burner fan motor FM that supplies air and the electromagnetic pump SP that supplies kerosene according to the temperature at that time, and adjusts the temperature to an appropriate value, and the ignition transformer Ig. an electromagnetic pump operating circuit 4 that operates the electromagnetic pump SP to supply kerosene after a pre-ignition time Tp (pre-ignition time);
+ An ignition transformer operation stop circuit 5 that stops the operation of the ignition transformer Ig after (post-ignition time), a flame detection circuit 6 that detects flame, and an electromagnetic pump operation circuit 4
When the flame detection circuit 6 does not detect a flame even though the flame detection circuit 6 is operating (that is, when the ignition does not occur smoothly or when the flame is extinguished), the power supply to the combustor main body BOD is stopped and the flame detection circuit 6 Even in the event of a failure, the combustor body $
It is barked from the safety circuit 7 which stops the power supply to 30D.

The combustor body pOD has normally closed contact RL4□ (auxiliary contact of relay RL4 controlled by bilimiter circuit 2 and safety circuit 7) and contact RL□1 (auxiliary contact of relay RL1 controlled by temperature adjustment circuit 3). A fan motor FM connected to an AC power supply via the ignition transformer Ig and a normally closed contact RL connected in parallel to the fan motor FM.
A series circuit of 3□ (relay RI controlled by the ignition transformer operation stop circuit 5, auxiliary contact of 3), a rectifier that rectifies the AC voltage, a solenoid valve SP connected in series to this, and a normally open contact RL21 ( It consists of a series circuit of auxiliary contacts of relay RL2 controlled by electromagnetic pump operation circuit 4.

The constant voltage circuit 1 includes a capacitor C1 that smoothes the output voltage of the rectifier Hv, and a transistor Q1 whose collector is connected to the capacitor C1, and whose base is connected to a constant voltage diode D□, which outputs a constant voltage from its collector. The bark is made from.

Note that a resistor R is inserted between the collector and base of the transistor Q1.

In the bilimiter circuit 2, the voltage dividing resistor R3°R4 divides the output voltage of the constant voltage circuit 1, and applies this as a reference voltage to the (+) terminal of the differential amplifier IC1 (second comparator).

In addition, the series circuit of the thermistor HL (second temperature detector) that senses temperature, variable resistor VR1 for temperature setting, and resistor R6 outputs a voltage according to the temperature setting value and the temperature at that time to the differential amplifier IC□. Apply to the (-) terminal.

The differential amplifier IC1 outputs a voltage according to the difference between the inputs of the (+) and (-) terminals, and when the output value exceeds a predetermined value (that is, the temperature exceeds the temperature range set for safety maintenance). (When the temperature exceeds
Transistor Q□ in safety circuit 7 connected via 3
Turn on □, energize relay RL4 and close normally open contact RL41 in electromagnetic pump operating circuit 4, thereby returning the state of the electromagnetic pump operating circuit to the original state and opening normally closed contact RL42. to stop power supply to the combustor main body BOD.

Note that since the bilimiter circuit 2 is for preventing an abnormal rise in temperature, the temperature set value by the resistor VR□ is a relatively high value.

In the temperature adjustment circuit 3, the output voltage of the constant voltage circuit 1 is connected to the (+) terminal of the differential amplifier IC2 (first comparator) with a temperature setting variable resistor VR2, the resistance value of which changes depending on the temperature. (Resistance value decreases as temperature rises) Thermistor T
H (first temperature sensor), a series circuit consisting of a resistor,
A reference voltage obtained by dividing the output voltage of the constant voltage circuit 1 by a resistor R89R9 is applied to the (-) terminal.

The output side of the differential amplifier IC2 is a resistor R1o and a diode D.
, to the base of the transistor Q, and the collector of the transistor Q is connected to the relay RL□.

Then, when the output of the differential amplifier IC2, which changes according to the temperature set value and the actual temperature, exceeds a predetermined value (temperature is below a certain value), the transistor Q3 turns on, and the relay RLi
is excited and closes contact RLII.

Transistor Q2 has its emitter connected to the emitter of transistor Q1, and its base connected to the collector of transistor Q3 via diode D2 and resistor R2.

Therefore, the temperature drops below a certain value and transistor Q3
When turned on, the transistor Q2 is turned on, and the output voltage of the constant voltage circuit 1 is applied to the electromagnetic pump operation circuit 4, the ignition transformer operation stop circuit 5, the flame detection circuit 6, and the safety circuit 7.

On the other hand, when the differential amplifier IC2 output is below a predetermined value (temperature is above a certain value) and the transistor is off,
The transistor Q2 is in an off state, and application of the output voltage of the constant voltage circuit 1 to the electromagnetic pump operation circuit 4, the ignition transformer operation stop circuit 5, the flame detection circuit 6, and the safety circuit 7 is stopped.

Therefore, the normally open contact RI, 1. Even if Q3 is shorted due to welding, when the temperature exceeds a certain value and transistor Q3 turns off, transistor Q2 will also turn off.
The electromagnetic pump SP does not operate, and only the fan motor FM operates.

Therefore, even if there is a problem with the contact RL11, safety is maintained.

A series circuit of diode D23 and resistor R4° is connected between the input and output of differential amplifier IC2 to provide a difference between the open and close operating points of relay RL1, and a series circuit between the base and emitter of transistor Q3 is connected to stabilize the operation. Capacitor C
2 is connected, and a diode D5 is connected in parallel to relay RL1.
is connected.

In the electromagnetic pump operating circuit 4, the differential amplifier IC3 (
+) terminal has two resistors R1□ and R□ that divide the output voltage of constant voltage circuit 1 applied via transistor Q2.
2 connection points are connected, and the (-) terminal is connected to the transistor Q2.
A capacitor C3 is connected to the collector of the capacitor C3, and is grounded by a resistor R13.

Capacitor C3 is charged when transistor Q2 is turned on, and after the above-mentioned predetermined time 'rp (time constant T = C3R13)
A predetermined voltage is applied to the differential amplifier IC3.

The output side of the differential amplifier IC3 is a resistor B□5 and a diode D.
6 to the base of transistor Q4, and the collector of transistor Q is connected to relay RL, and the (-) input terminal of differential amplifier ■C3 is connected to resistor RIB.
and a diode D6, and the output end of the rectifier CV is connected to the relay RL2.

Therefore, when the output of differential amplifier IC3 exceeds a predetermined value, transistor Q turns on, relay RL2 is energized, and normally open contact RL! of main body $OD! i is closed and the electromagnetic pump SP operates.

Note that a series circuit including a normally open contact RL4□ (controlled by relay RL4) and a resistor R1 is connected in parallel to the capacitor C3.

However, R14 and R13 have a relationship of R13>>R14.

Through this series circuit, as will be described in detail in the operation description, when the ignition does not occur smoothly or when the flame detection circuit 6 fails, the relay RL in the safety circuit 7 is turned on.
In conjunction with this, the normally open contact RL41 is turned on.

Then, the electric charge charged in the capacitor C3 is transferred to the resistor R41.
, is discharged through a series circuit of normally open contacts RL4□.

Then, the potential of the (-) terminal of the differential amplifier IC3 increases, and the output voltage of IC3 decreases, so that the transistor Q is turned off.

Turning off transistor Q4 causes demagnetization of relay RL,
Therefore, the normally open contact RL! Since i is turned off, the operation of electromagnetic pump SP stops.

Further, a parallel circuit of a capacitor C4 and a resistor R17 is connected between the base and emitter of the transistor Q4 to stabilize the operation.

In the ignition transformer operation stop circuit 5, a differential amplifier IC
Two resistors R□9 divide the output voltage of the constant voltage circuit 1 applied via the transistor Q2 to the (+) terminal of 4.
．． The connection point of R2o is connected, and the (-) terminal is connected to a capacitor C5 whose one end is connected to the collector of the transistor Q2, and the collector of the transistor Q is connected via a diode D9 and a resistor. be done.

Capacitor C5 connects constant voltage circuit 1 when transistor Q4 is turned on (this causes electromagnetic pump SP to operate).
It is charged by the current flowing through → transistor Q2 → capacitor C5 → resistor B□8 → diode D9, and after the aforementioned predetermined time TI, a predetermined voltage is applied to the (-) terminal of differential amplifier IC4.

The output side of the differential amplifier IC is connected to the base of the transistor Qs via a resistor R2□ and a diode D1o,
The collector of transistor Q5 is connected to a parallel circuit of relays R1, J and diode D□1, one end of which is connected to rectifier CV.

Relay RL3 is energized by turning on transistor Q after the aforementioned predetermined time T+ after relay R1 is energized;
The normally closed contact RL3t is opened to stop the operation of the ignition transformer Ig.

The reason for providing the predetermined time TI here is to maintain the ignition state until the combustion state is stabilized after the excitation of relay RL2, that is, the start of the electromagnetic pump SP, and to stop the operation of the lighting transformer rg after the combustion is stabilized. It's for a reason.

In the flame detection circuit 6, the resistance value of cadmium sulfide CdS becomes small when a flame is detected (when it is bright), and the resistance value becomes large when a flame is not detected (when it is dark).

Then, the output voltage of the constant voltage circuit 1 applied via the transistor Q2 is divided by the resistance value of CdS and the resistance value of the resistor R22, and this divided voltage is applied to the (+) of the differential amplifier IC5.
) to the terminal.

A transistor Q2 is connected to the (-) terminal of the differential amplifier IC5.
The output voltage of the constant voltage circuit 1 applied via the resistor R2
3, R2, and the partial pressure is added.

When no flame is detected, the differential amplifier IC5 outputs a voltage higher than a predetermined value.

In the safety circuit 7, the base of the transistor q is connected to the resistor R.
25 and the output of the differential amplifier IC5 via the diode D12, the collector of which is connected to the base of the transistor Q via the diode D14, and the bias resistors R27 and R28 of the transistor Q7 via the diode D□3. connected to the connection point.

The base of transistor Q7 is connected to the collector of transistor Q through an anti-series connected diode D□59D16.

Diode D engineer. The connection point of D16 is resistor R27, R2
, is connected to the connection point of .

The base of transistor Q8 is connected to the collector of transistor Q4 via diode D17 and grounded by resistor R30, and its collector is connected to the base of transistor Q by resistor R3°.

The base of the transistor Q9 is grounded by a resistor R3a, and the collector thereof is connected to a diode D□9.
Transistor Q via D2o.

connected to the base of

Diode D19. The connection point of D2o is the transistor QI
This is the connection point of the bias resistors R35t and R36 of O.

In addition, the connection point of resistors R35 and R36 is a diode D,
is connected to the collector of transistor Q7 via.

The collector of transistor QIO is connected via resistor R37 to the (+) terminal of differential amplifier IC, which is also connected via resistor R38 to the collector of transistor Q2, and connected to ground via capacitor CI3. be done.

The (-) input terminal of the differential amplifier IC6 is connected to the transistor Q2.
A constant voltage applied through resistor B39. A voltage divided by R40 is added, and its output terminal is connected to resistors R1,
and is connected to the base of the transistor Q□1 via the diode D21.

The collector of the transistor Qll has one end connected to the rectifier Cv.
A parallel circuit of relay RL4 and diode D2□ is connected, and a capacitor C for stabilizing operation is connected to its base.
7 is connected.

In addition, resistance R2,, R2g. R3□, R3, are transistors Qe, Q? , Q8= for the collector bias of Qe.

When transistor Q10 is turned off, current flows from constant voltage circuit 1 to transistor Q2 to resistor 138 to capacitor C6, capacitor C6 is charged, and after a predetermined time Ts (safety switch time), its terminal voltage reaches a predetermined value, and differential amplifier IC6 Transistor Q11 is turned on by the output of
Relay RL is energized, normally closed contact RL, 2 is opened, and power supply to the combustor main body BOD is stopped.

In addition, as mentioned above, relay RL4 is connected to bilimiter circuit 2.
It is also operated by

Next, the operation of the combustion control circuit having such a configuration will be explained with reference to the operation explanatory diagram of FIG. 2.

. First, the case of normal operation (FIG. 2a) will be explained.

In this case, the transistor Q is turned on together with the power switch means, the relay RL1 is energized, the contact RL11 is closed, the burner fan motor FM is operated, and the ignition transformer Ig is operated.

When the transistor Q3 is turned on, the transistor Q2 is turned on, and the capacitor C3 is charged. After a predetermined time Tp, that is, after the pre-ignition time has elapsed, the output of the differential amplifier IC3 in the electromagnetic pump operating circuit 4 causes the transistor Q to be turned on.
is turned on, relay RL2 is energized, normally open contact RL11 is fully closed, and electromagnetic pump sp is operated to supply kerosene.

When transistor Q is turned on, its collector becomes equal to negative potential, so capacitor q1 resistor R□8, diode D9 . A charging current flows through the collector-emitter path of the transistor Q4, and the capacitor C5 of the ignition transformer operation stop circuit 5 is charged.

The charging time constant corresponds to the predetermined time Ti, that is, the post-ignition time.

Eventually, after a predetermined time Ti, the (-) terminal voltage of the differential amplifier IC4 falls, so the output of the differential amplifier IC4 rises.
This turns on transistor Q4.

By turning on transistor Q, relay RL, 3
is excited, its normally closed contact RL31 is opened, and as a result, the operation of the ignition transformer Ig is stopped.

In this way, the burner is ignited by the action of the ignition transformer Ig and the electromagnetic pump operation circuit 4, and then the operation of the ignition transformer Ig is stopped by the action of the ignition transformer operation stop circuit 5, and when combustion continues, the temperature during combustion The resistance value of the thermistor TH in the temperature adjustment circuit 3 changes accordingly.

Then, the output of differential amplifier IC2 changes according to this resistance value change, transistor q turns on and off, and relay R
Contact RL11 of L1 opens and closes, and burner fan motor FM
And the operating time of the electromagnetic pump SP is controlled.

That is, the burner fan motor FM and the electromagnetic pump SP are controlled by the temperature adjustment circuit 3 so that the temperature is maintained at a value set by the variable resistor VR2 (an appropriate value for the combustor).

Here, when the normally open contact RL11 is welded and no longer opens or closes (when it remains closed due to a short circuit), safety is ensured by the action of the transistor Q2 (switch means).

That is, when the transistor Q3 is turned off, the transistor Q2 is also turned off, and power supply to the electromagnetic pump operation circuit 4 is stopped.

Therefore, relay RL21 is opened and the operation of electromagnetic pump SP is stopped.

Temperature adjustment circuit 3 does not work properly for some reason,
Alternatively, if the temperature rises to a predetermined value or higher despite the operation, the resistance value of the thermistor (2) of the bilimiter circuit 2 decreases, and the transistor Q□ is turned on by the output of the differential amplifier IC□.

Then, relay RL4 is energized, normally closed contact RL42 is opened, and burner fan motor FM and electromagnetic pump sp
stops working.

At the same time, normally open contact RL41 is closed, transistor Q is turned off, relay RL2 is demagnetized, and normally open contact RL2□ is opened, so even if contact RL4° is shorted, the operation of electromagnetic pump SP is stopped. .

In this way, the function of the bilimiter circuit 2, which is configured separately from the temperature adjustment circuit 3, prevents an abnormal rise in temperature.

Next, the operation when ignition does not occur smoothly, that is, when there is no ignition (FIG. 2b) will be explained.

When the electromagnetic pump SP operates but no flame is detected (when the burner is not ignited due to ignition failure, etc.), the resistance value of cadmium sulfide CdS is large, so the output of the differential amplifier IC6 causes the safety circuit 7 to be detected. transistor Q
6 turns on.

On the other hand, since transistor Q4 is on, no base current is supplied from diode D, and transistor q is off, and Q8 is off, so when transistor Q9 is on, forward current flows through diode D and 9. As a result, the base potential of transistor Q□0 falls, and Qlo is turned off.

Therefore, after the predetermined time Ts, that is, after the safety switch time has elapsed, the output of the differential amplifier ■C6 causes the transistor Q1 to
□ turns on, relay RL is energized, thereby closing normally open contact RL, 1 and opening normally closed contact RL42.

Therefore, when the contact RL4° is opened, the operation of the contact RL21 of the burner fan motor FM and the electromagnetic pump SP is stopped.

Further, even if contact RL4□ is welded and cannot be opened, relays R1, 2 are demagnetized by opening contact RL,1, contact RL2□ is opened, and the operation of electromagnetic pump SP is stopped.

Therefore, double safety is achieved. In this way, when the flame detection signal is not output even though the electromagnetic pump SP is operating, that is, when there is a failure in ignition, the burner fan motor FM and the electromagnetic pump SP are stopped by the movement of the safety circuit 7, ensuring safety. be done.

Next, when a signal indicating that a flame has been detected is output from the flame detection circuit 6 before the electromagnetic pump sp operates (for example, a flame detection signal is output due to a failure of cadmium sulfide CdS as shown in Fig. 2C). )

In this case, since the resistance value of cadmium sulfide CdS is small, the transistor Q6 in the safety circuit 7 is turned off.

On the other hand, since transistor Q4 is off, resistor R27
When a base current is supplied through the transistor Q7 and the transistor Q7 is turned on, a forward current flows through the diode D18, and the base potential of the transistor Qto decreases.

is turned off. Therefore, after a predetermined period of time, the differential amplifier IC6
Transistor Q1□ is turned on by the output of
4 is energized, the normally open contact RL41 is closed, the normally closed contact RL42 is opened, and the electromagnetic pump operating circuit 4 is returned to its original state.

The operation of burner fan motor FM and electromagnetic pump SP is stopped by opening contacts RL and 2.

Even when this is short-circuited, the opening of contact RL41 demagnetizes RI,2, and the contact RL21 is opened, thereby stopping the electromagnetic pump SP.

Therefore, safety is maintained by the function of the safety circuit 7 in the same manner as explained with reference to FIG.

Also, when the flame goes out for some reason during combustion (Fig. 2 d)
The operation is the same as when ignition does not occur smoothly, the resistance of cadmium sulfide CdS increases, transistor Q1o in safety circuit 7 turns off, and burner fan motor FM
And 9 operations of electromagnetic pump SP will be stopped.

That is, safety is ensured by the function of the safety circuit 7.

[Effect of idea]

As is clear from the above explanation, the present invention has completely separate configurations of the temperature adjustment circuit and high limiter circuit, and separately provides a flame detection circuit, safety circuit, etc. Since it is equipped with a switching means (transistor Q2), its operation is highly reliable, and it has a temperature adjustment function and is fully equipped with measures against troubles (failures, disconnections, short circuits) of each component, making it extremely safe. .

This can be summarized as follows.

■ The temperature adjustment circuit and the high limiter circuit are constructed separately, each having independent temperature detectors (TH, HL), and independent comparison means (IC2゜IC4). Even if there is a problem with one component (particularly the temperature adjustment circuit), the other circuit (especially the high limiter circuit)
works normally and has high reliability (especially reliability against abnormal heating).

■ A switch means (transistor Q2 in the embodiment) that operates in conjunction with the temperature adjustment circuit is provided to control the power supply to the electromagnetic pump operating circuit. Even when the operation of the pump cannot be properly controlled, the switch means ensures normal operation (stopping) of the electromagnetic pump, improving safety.

■ The flame detection circuit and safety circuit are separate from other circuits, so even if the temperature adjustment circuit or electromagnetic pump operation circuit cannot properly control the electromagnetic pump, the safety circuit can stop the power supply and ensure safety. Secured.

Furthermore, since the entire control circuit is electronic, it is relatively inexpensive, and since a thermistor is used as the temperature sensing component, it has better responsiveness than a mechanical thermostat, making it advantageous for use in instantaneous combustors, for example.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing the operation of the circuit shown in the figure.

Claims (1)

[Scope of utility model registration request] an electric power supply circuit to which a burner fan motor that supplies air to the combustion chamber, an electromagnetic pump that supplies kerosene, and an ignition transformer are connected; an electromagnetic pump operating circuit that operates the electromagnetic pump after a predetermined time after the ignition transformer operates; an ignition transformer operation stop circuit that stops the operation of the ignition transformer after a predetermined time after the operation of the electromagnetic pump; and a first comparator that compares the temperature detected by the first temperature detector at a first level; a temperature adjustment circuit that controls the operating time of the burner fan motor and the electromagnetic pump based on the comparison results; and at least the electromagnetic pump operating circuit when the temperature detected by the first temperature detector is equal to or higher than the first level. a switch means for stopping the electromagnetic pump by stopping power supply to the electromagnetic pump; and a second comparator for comparing the temperature detected by the second temperature detector at a second level higher than the first level; a bi-limiter circuit that stops power supply to at least the electromagnetic pump when the temperature detected by the second temperature detector exceeds the second level; a flame detection circuit that detects a flame and outputs a signal; and the electromagnetic pump. Supplying power to the burner fan motor and the electromagnetic pump when the flame detection circuit does not output a detection signal in an operating state of the operating circuit and when the flame detection circuit outputs a detection signal while the electromagnetic pump operating circuit is in an inoperable state. Along with stopping the
A combustion control circuit comprising: a safety circuit that causes the electromagnetic pump operation circuit to stop operation of the electromagnetic pump.