JPS6080025A - Burning detecting device - Google Patents

Abstract

PURPOSE:To prevent the device from the miss-operation of an oxygen starvation detecting circuit caused by the factor other than the oxygen starvation by detecting whether a burning condition returns the normal condition after the increasing of a fuel supply for fixed time at the operation of an oxygen starvation detecting circuit. CONSTITUTION:At the wrong burning condition caused by some reason, a flame electric current is decreased. When the both ends voltages of a capacitor 6 are dropped, an oxygen starvation detector 13 is operated, an output ''H'' is outputted, an input for an AND circuit 19 becomes ''H'', while the output ''H'' is self-maintained by a diode 18, and the output ''H'' is made to be continued. A transistor 25 is energized by the output ''H'' of the AND circuit 19, an electric current is flowed through light emitting part 27a of a light conductive element. By the operation of the light emitting part 27a, the frequency of a pulse electric voltage impressed to an electromagnetic pump is increased, then a fuel is supplied slightly more than a regular value. Thereby, the flame electric current is changed toward increasing trend when the burning air temperature is lower and the burning air quantity is much more. In case of the oxygen starvation, the flame electric current is still in decreasing trend. The phenomenon is detected in the next stage circuit. In case of the oxygen starvation, a latch relay 55 is energized, a contact 55a is opened, accordingly, the all operations are stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion detection device for a combustor equipped with an oxygen deficiency detection circuit.

Conventional configuration and its problems Conventionally, in this type of combustion device, even if the combustion condition deteriorates due to a cause other than oxygen deficiency, the oxygen deficiency detection circuit, which is set to a higher level than the misfire detection circuit, operates and the reset circuit is activated. The configuration was such that the engine was activated to stop combustion. However, with this configuration, if the indoor temperature, that is, the temperature of the combustion air, is extremely low, the combustion will not be stable even if the state shifts to the combustion state after ignition, and the unstable state will continue, causing the oxidation There was a problem in which the oxygen deficiency detection circuit was activated and combustion stopped even though there was no deficiency condition.

Purpose of the Invention The present invention was made to solve the above-mentioned problems.
When the oxygen deficiency detection circuit is activated, the fuel is increased for a certain period of time and it is detected whether the combustion state returns to normal. If it does not return to normal, it is determined that there is an oxygen deficiency and combustion is stopped and the combustion is restored. If this is the case, it is assumed that the cause is other than oxygen deficiency, and the oxygen deficiency detection level /L/wo is lowered for a certain period of time to continue combustion. That is, the purpose is to prevent malfunction of the oxygen deficiency detection circuit due to causes other than oxygen deficiency.

Structure of the Invention In order to achieve the above object, the present invention provides a self-holding circuit composed of an AND circuit to memorize the state when the oxygen deficiency detection circuit is activated, and a timer circuit to increase the amount of fuel for a certain period of time. A variable oscillation frequency circuit for the supply electromagnetic pump is provided, and an AND circuit that determines the output based on the output state of the oxygen deficiency detection circuit that is opened at a certain time after the variable oscillation frequency circuit is activated, and the operation starts with the output IHf of the AND circuit. The logic of the output of the timer circuit is inverted via a transistor and connected to the input level of an oxygen deficiency detection circuit set by a resistor connected in series, and the output of the timer circuit and the output of the AND circuit are input. The output of the circuit is inverted by a transistor and connected to the input of an AND circuit forming the self-holding circuit.

Description of examples An example of this will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a control circuit section including a combustion detection circuit, and FIG. 2 shows an oscillation circuit section of an electromagnetic pump for fuel supply. In Fig. 1, 1 is an AC power source for combustion detection, 2 is a burner, a GVi flame rod, 4 and 5 are resistors, and 6 is a capacitor.
6 constitutes a combustion detection circuit that utilizes the rectifying effect of the flame, and the current value changes depending on the state of the combustion flame, causing the capacitor 6 to
The voltage across it changes. 7 to 11 are resistances of 10 degrees, 7 and 8 are misfire detection levels, and 9 and 1 are oxygen deficiency detection levels) Vf stages are set. 12 is a misfire detection detector, 13
14 is an open collector drive circuit, and the output of the combustion initial misfire detector 12 is used to detect an oxygen deficiency detector 13.
This is to send the output of %Ll to %Ll. 15 is a resistor, and 16 is an inverter for inverting the output logic of the oxygen deficiency detector 13.

17 is a resistor, 18 is an evening ruler ode for forming self-holding, 19
is an AND circuit, 20 is a capacitor, 21 is a resistor, 22 is a capacitor, 23 is a resistor, 24 is a constant voltage diode, 25 is a transistor, and these 22 to 25 are timers for increasing the fuel for a certain period of time, which will be described later. It constitutes a circuit. 26FiAND circuit, 27a is a light emitting part of a photoconductive element, which emits light when the output 25 of the timer circuit is turned on. 27b is a light receiving section (see FIG. 2), and the light emitting section 27a is
By emitting light, a conductive state is established between the outputs. 2
8 is a resistor, 29 is a capacitor, and the AND circuit 26 constitutes a timer circuit. 30 is an AND circuit which inputs the output of the AND circuit 26 and the output of the oxygen deficiency detection circuit, and determines what happens to the output of the oxygen deficiency detection circuit during a time constant determined by the resistor 28 and the capacitor 29. This is a circuit for detecting.

31 is a resistor, 32 is a timer-dedicated IC circuit containing an oscillation circuit and an F-F circuit, etc., 32a is a power supply terminal, and 3
2b is a reset terminal, 320 is a nut terminal, 32d is an output terminal, 32e and 32f are input terminals, and 32g is a ground terminal. 33 is a resistor, and 34.35 is a capacitor, whose time constant determines the oscillation period. 36 and 37 are resistors, and 38 is a transistor, which becomes conductive or non-conductive depending on the output of the timer IC circuit 32, thereby changing the input level (v) of the oxygen deficiency detector 13.

39 is an ExoR circuit that outputs 'Hr only when two input states are different, and is connected to the AND circuit 30 and the timer IC.
The output of the circuit 32 is used as an input. 40.41
is a resistor, 42 is a transistor, and the ExoR circuit 39
The circuit becomes conductive and non-conductive depending on the output of the timer IC circuit 32, and becomes conductive when the timer IC circuit 32 times out, thereby releasing the self-holding state of the AND circuit 19. 43 is a capacitor, and 44 is an AND circuit configured to receive the output of the oxygen deficiency detector 13 and the output of the AND circuit 26 as inputs, and the output thereof is input to a reset circuit configured with an OR circuit 51 described later. 45 is a combustion control circuit, 46 is a resistor, 4
7 is a capacitor, 48.49 is a resistor, 50 is an amplifier,
46 to 50 constitute a misfire safety timer circuit that starts operating upon receiving a signal from the combustion control circuit 45. 51
52 is an OR circuit, 52 is a resistor, and 53 is a daubernoide, which controls the operation of the non-ignition safety timer circuit based on the signal from the combustion detection circuit. 54 is an open collector drive circuit, 55 is a two-winding latch relay, 55a is a contact of the relay, 56 is a return switch, and 57 is a DC power supply for the control circuit.

Fig. 2 shows an oscillation circuit of an electromagnetic pump for fuel supply, where 58 is a resistor, 59 is a rectifying diode, 60 is a smoothing capacitor, 61 is a resistor, 62 is a constant voltage diode, 63 to 66 are resistors, 67 is a PUT, 68 and 69 are resistors, and 70 is a capacitor, and the above 63 to 70 constitute a relaxation oscillation circuit using PUT, and the light receiving part 27b of the photoconductive element is connected in parallel to the resistor 65 that sets the charging time constant. It is connected. 7
1 is a capacitor, 72 is an SCR, 73 is an electromagnetic pump, 7
4 is a diode, 75 is a resistor, 76 is a capacitor, 77
is a resistor, 78 is a bidirectional diode, 79 is a diode, 80.81 is a resistor, 82 is a diode, 83 is an SCR
In 75 to 83, a commutation circuit is formed to set the conduction time of the 5CR72, that is, the time that the electromagnetic pump 73 is ON. IQ6G-80025 (3) Yes.

To explain the operation of the above configuration, first, in FIG. 1, the ignition operation is started by the combustion control circuit 45,
When transitioning to ignition and combustion, claim rod 3 and combustion flame 2
A frame current flows through the capacitor 6, the voltage across the capacitor 6 increases, and the input relationship of the oxygen deficiency detector 13 becomes %L'' with 10 inputs and multiple outputs.For this reason, the AND circuit 19 With the output of
7a remains OFF, and the output of AND circuit 26 is also output! L
Because of #, the output of the AND circuit 30.44 at the next stage also becomes -L#. The timer IC 32 is also turned off, and the oxygen deficiency detection level remains at the normal setting level. Also, the input relationship of the misfire detector 12 is 10 inputs per person, and the multiple outputs are 1.
It becomes Ll. Therefore, the input of the misfire safety timer circuit is fixed at sLe via the diode 53, and the operation of the reset circuit is stopped. Normal combustion continues in this state.

Next, when the combustion condition deteriorates for some reason, the flame current decreases, and the pressure across the capacitor 6 decreases. Therefore, first, the oxygen deficiency detector 13 operates and outputs "1Hf," and the input of the AND circuit 19 is set to "1P," which is self-maintained by the diode 18 and continues to output %H'.

Depending on the output tH' of the AND circuit 19, the transistor 25
conducts, and a current flows through the light emitting portion 27a of the photoconductive element.

The conduction time of this transistor 25 is determined by a time constant determined by the capacitor 22 and the resistor 23, and by the constant voltage diode 24. Due to the light emission from the light emitting section 27a, the light receiving section 27b shown in FIG. 2 becomes conductive. Therefore, the time required to charge the capacitor 70 is shortened, and the oscillation cycle of the PUT 67 is shortened. In other words, the electromagnetic pump 7 is activated for a predetermined period of time when the oxygen deficiency detector 13 is activated.
Increase the frequency of the Varne voltage applied to No. 3 and supply fuel a little longer than the normal value. As a result, when the temperature of the combustion air is low or when the amount is large, the flame current tends to increase, and when there is oxygen deficiency, the flame current tends to decrease.

This phenomenon will be detected by the next stage circuit, but first of all, let's talk about the case where the flame current has increased, that is, the combustion state has been restored. The AND circuit 26 becomes SH after a certain period of time according to the time constant determined by 29. This is the time to wait for the combustion state to change due to an increase in fuel. One side of the AND circuit 30 is powered by the output -He of the AND circuit 26.
Since the flame current has increased at the other input, the output of the oxygen deficiency detector 13 becomes 1Lt, which is the output %H' of the inverter 16.

In other words, both inputs of the AND circuit 300 become %Hr, and the output is %
It becomes Hf. This supplies power to the timer IC 32 and starts counting. Since the output 32d of the timer IC 32 is initially at tHt, the transistor 38 becomes conductive, shorting both ends of the resistor 110.

In other words, the oxygen deficiency detection level μ is lowered, the transistor 25 is turned off, and the oxygen deficiency detection circuit is in a state where it is difficult to operate even if the combustion amount returns to the normal combustion amount. When the timer IC 32 counts up, the output 32d becomes %L#, and since the inputs of the ExoR circuit 39 become IH' and -L', the output becomes %Hq, and the transistor 42 conducts and the input (i) of the AND circuit 19 becomes %Hq.
, %Lf, the self-holding is divided by 11, and the next stage circuit is stopped, that is, the state is returned to the initial normal combustion state. If a similar phenomenon occurs thereafter, the above operation is repeated.

Next, when the flame current does not increase, that is, when there is an oxygen deficiency state, in the above explanation, the output tHt of the AND circuit 26 causes one side input tHtl of the AND circuit 44, and the other input also becomes the output ant of the oxygen deficiency detector 13. Because of Hl, the state is %H'. Therefore, at the output H#, the OR circuit 510 input %H'' is excited, and the latch relay 56 is energized at the output %H', and the contact 5
5a), all operations stop.

When the oxygen deficiency detection circuit operates in this way, it temporarily increases the fuel, detects the combustion state after that, and when the combustion state recovers, detects the oxygen deficiency for a certain period of time, lowers the Be/I/, and starts combustion. If the combustion state does not recover, it is assumed that there is an oxygen deficiency and all operations are stopped, thereby preventing the oxygen deficiency detection circuit from malfunctioning due to causes other than oxygen deficiency.

Effects of the Invention As described above, according to the present invention, when the oxygen deficiency detection circuit operates,
Since the combustion amount is temporarily changed in the direction of increasing, and the combustion state is detected after that, it is possible to distinguish whether the cause is due to an oxygen deficiency or something else, and to prevent the oxygen deficiency detection circuit from malfunctioning due to causes other than oxygen deficiency. It has the effect of preventing things from happening.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a combustion detection device showing an embodiment of the present invention, and FIG. 2 is a fuel supply electromagnetic pump drive circuit diagram thereof. 2...Burner, 3...Frame rod, 12゜13...Detector, 27a, 27b.
... photoconductive element, 30 ... AND circuit,
32... Timer IC. 39...ExoR circuit.

Claims (1)

[Scope of Claims] A misfire detection circuit that detects misfire conditions such as lack of oil by using flame rectification; and an acid detection circuit that is set at a higher level than the misfire detection circuit and detects abnormal combustion in the event of oxygen deficiency. Absence detection circuit;
AND means for increasing the oscillation frequency of the electromagnetic pump for fuel supply for a certain period of time when the oxygen deficiency detection circuit is activated, and determining the output based on the output state of the oxygen deficiency detection circuit that opens at a certain time after increasing the oscillation frequency. circuit, and a timer circuit that starts operating when the output of the AND circuit reaches %Hl, and the output of the timer circuit is connected to the input level change point of the oxygen deficiency detection circuit set by connecting a resistor in series. connection,
A combustion detection device characterized in that an output of an ExoR circuit whose output becomes %Hl only when the two inputs of the output of the AND circuit and the output of the timer circuit are different is connected to the input of the AND circuit. 2 pesos