JPS6080027A - Combustion machine safety device - Google Patents

Abstract

PURPOSE:To prevent mulfunctioning of an oxygen deficiency detecting circuit due to a cause, except an oxygen starvation condition, such as combustion instability occurring when a room temperature is temporarily decreased, combustion instability occurring when a rise of a room temperature is poor, by a method wherein, when the room temperature is decreased, an oxygen deficiency level is caused to decrease. CONSTITUTION:When a room temperature is decreased, the resistance value of a thermistor 18 is increased, and thereby the positive input of an amplifier 57 is lowered, and an output is also naturally decreased at the degree of amplification determined by resistors 55 and 56. When the output level of the amplifier 57 becomes below the Zener voltage of a constant- voltage diode 52, the positive input of an oxygen starvation detector 10, i.e., an oxygen starvation level is determined by the output level of the amplifier 57, and when a room temperature is decreased, an action is effected in a direction in which oxygen starvation level is decreased. This, even if a room temperature is decreased, a combustion condition is made unstable, and the negative input of the oxygen starvation detector 10 is decreased, causing a positive input to be also decreased simultaneously, and thereby an output is prevented from being inverted to ''H'', if, with this it is brought into an oxygen starvation condition, a combustion condition is further worsened, and thereby said negative input is further decreased, the output of the oxygen starvation detector 10 is inverted to ''H'', and the input of an OR circuit 37 is brought to an ''H'' to operate a rest.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a safety device for a combustion machine provided with an oxygen deficiency detection circuit.

Conventional configuration and its problems Page 2 The safety device for a combustion machine with a conventional oxygen deficiency detection circuit is
As shown in the figure, the output of the oxygen deficiency detection circuit 10, which is set to a higher level than the misfire detection circuit 11, which operates when the combustion condition has deteriorated extremely, and the output of the timer circuits 13 to 17, which operate for a certain period of time after the start of combustion. It was provided with an AND circuit 12 as an input, and the output of the AND circuit 12 was simply connected to the input of a safety circuit constituted by an OR circuit 37. This safety device has a timer circuit that locks the output of the oxygen deficiency detection circuit for a certain period of time after the start of combustion, in order to prevent the oxygen deficiency detection circuit from malfunctioning due to instability of combustion immediately after combustion starts. Consideration has been taken that the oxygen deficiency detection is activated after the timer circuit times out, that is, after combustion becomes stable.

However, according to this configuration, when the indoor temperature, that is, the temperature of the combustion air, is extremely low, the timer circuit will be in the same state as if the amount of combustion air was increasing even after the time-up, and the combustion The state of instability continues. As a result, the oxygen deficiency detection circuit was activated even though there was no oxygen deficiency, causing combustion to stop.

Purpose of the Invention The present invention was made to solve the above-mentioned problems.
By changing the detection level of the oxygen deficiency detection circuit according to the indoor temperature, the purpose is to prevent the oxygen deficiency detection circuit from malfunctioning due to unstable combustion when the indoor temperature drops. In other words, when the indoor temperature decreases, the oxygen deficiency detection level also decreases accordingly, and the purpose is to prevent the activation of the oxygen deficiency detection circuit due to a decrease in the combustion signal when the indoor temperature decreases and combustion becomes unstable. This is what I did.

Note that if an oxygen deficiency occurs in this state, combustion will further deteriorate, so the combustion signal will drop and the oxygen deficiency detection circuit will operate to stop combustion.

Structure of the Invention In order to achieve the above object, the present invention includes an amplifying circuit whose output voltage changes depending on the indoor temperature, and an amplifying circuit in which the output of the amplifying circuit is used as a reference input and the other input is connected to a combustion signal. An AND circuit is provided which takes as inputs the output of an oxygen deficiency detection circuit composed of a combustion chamber and the output of a timer circuit that operates for a certain period of time after the start of combustion, and the output of the AND circuit is connected to a safety circuit.

Example paddle 1-w light An example of this will be described below with reference to FIG.

In Figure 2, 1 is an AC power source for the combustion detection circuit, 2 is a burner, 3 is a flame rod inserted into the combustion flame, 4, 5
is a resistor, 6 is a capacitor, and 1 to 6 above constitute a combustion detection circuit that utilizes the rectifying effect of the flame, so that the current value changes depending on the state of the combustion flame, and the voltage across the capacitor 6 changes. It has become. 7 and 8 are resistors that set the misfire detection level. 10 is a detector for detecting oxygen deficiency, 11 is a detector for detecting a misfire, and 12 is an AND circuit, which combines the output of the oxygen deficiency detector 10 with an amplifier 17 that constitutes a timer circuit that operates for a certain period of time in the initial stage of combustion. The output is connected to the input of an OR circuit 37 forming a safety circuit. 13 to 15 are resistors, 16 are capacitors, 1
7 is an amplifier, and 13 to 17 constitute a timer circuit for not sending the output of the oxygen deficiency detection circuit 1.5 to the safety circuit for a certain period of time in the initial stage of combustion. 18 is a thermistor for indoor temperature detection, 19-22
is a resistor that sets the level for normal indoor temperature control. 2a is a detector, and 19 to 23 constitute a room thermo circuit. 24 is a resistor, 25 is a capacitor, 26 is an AND circuit, 27 is a diode, and 28 is a resistor, and these 24 to 27 constitute a prepurge circuit. 29 is a resistor, and 3° is an AND circuit, which is an igniter drive circuit which inputs the output of the pre-purge circuit and the output of the misfire detection detector 11. A diode 31 controls the operation of a non-ignition safety timer circuit, which will be described later, depending on the output state of the misfire detection detector 11. 32 to 34 are resistors, 35 is a capacitor, and 36 is an amplifier, and these 32 to 36 constitute a non-ignition safety timer circuit. 37 is an OR circuit which is a reset circuit which receives the output of the non-ignition safety timer circuit and the output of the oxygen deficiency detection circuit as inputs. 38 to 41 are open collector drive circuits, 42 is a motor drive unit, 43 is a fuel supply electromagnetic pump drive unit, 44 is an igniter drive 6 page unit, 45 is a two-winding latch relay, and two are used for setting and resetting. This relay has two coils, and has the characteristic that once one coil is set, it continues to hold that state until a different coil is energized. Reference numeral 46 denotes a contact point of the two-winding latch relay, which becomes open in the event of an abnormality and stops all circuits. 47 is a return switch, 48 is a DC power source for the control circuit, 49 is a resistor, and 50 is an open collector drive circuit, which is used to prevent malfunction of the oxygen deficiency detection circuit when combustion is stopped. 51 is a resistor, and 52 is a constant voltage diode, which is used to set the upper limit value of the oxygen deficiency detection level. 53 to 56 are resistors, and 57 is an amplifier. These 53 to 57 and the room temperature detection thermistor 18 constitute an amplifier circuit, and depending on the room temperature condition, the resistor 55
．． The output voltage of the amplifier 57 is changed by the degree of increase determined by 56.

To briefly explain the operation in the above configuration, first, when the indoor temperature is within a range that does not worsen the combustion condition, the output level of the amplifier circuit 57 is set to be higher than the Zener voltage of the constant voltage diode 52, so the acid Missing detection detector 1
■Input of 0 is constant voltage page 7.

It is regulated by the Zener voltage of the diode 52. At this time e
The input is OV because there is no combustion, and the output of the oxygen deficiency detector 10 is in the "H" state, but at the same time the misfire detection detector 1
Since the output of 1 is also "H", the drive circuit 50 becomes conductive, locking the output of the oxygen deficiency detection detector 10 at °L", and setting the input of the AND circuit 12 to °L". Since charging of the capacitor of the capacitor 17 is also started via the resistor 13, its output is in the "L°" state for a certain period of time. In other words, A
The other input of the ND circuit 12 is also “
This means that it is locked to "L".

In this state, if the indoor temperature is lower than the setting, the output of the detector 23 becomes "H", power is supplied to the next stage circuit, and the motor drive unit 42 is activated by the ON1 re-purge circuit to the fuel supply electromagnetic pump drive unit 43 and The igniter drive unit 44 is ONL
,, begins ignition operation and transitions to combustion.

When combustion starts, current flows between the flame rod 3 and the burner 2 and charges the capacitor 6.

Therefore, the force level of the misfire detector 11 and the oxygen deficiency detector 100e increases, and the relationship of θ input> ■ input changes, and the output reverses from °H" to °L", indicating normal combustion. continue. Also, when the charging of the capacitor 16 progresses and the relationship of ■ input > θ input of the amplifier 17 is reached, the output becomes.

Since it is in the H'' state, the AND circuit 12 is controlled by the output state of the oxygen deficiency detector 10.The oxygen deficiency level at this time is the normal level set by the constant voltage diode 52, as described above. .

Next, when the indoor temperature decreases, the resistance value of the thermistor 18 increases, so the input to the amplifier 57 decreases, and the output naturally decreases by the amplifier determined by the resistor 55.56. When the output level of the amplifier 57 becomes lower than the Zener voltage of the constant voltage diode 52, the input of the oxygen deficiency detector 10, that is, the oxygen deficiency level, is determined by the output level of the amplifier 57, and the indoor temperature decreases. As a result, it acts in the direction of lowering the oxygen deficiency level. As a result, the indoor temperature decreases, the combustion state becomes unstable, and even if the e input to the oxygen deficiency detector 10 decreases, the output will still be °H because the input has decreased.
” will no longer be reversed.

Page 9 If oxygen deficiency occurs in this state, the combustion condition will further deteriorate, so the e input will further decrease, and the output of the oxygen deficiency detector 10 will become '
H" and sets the input of the OR circuit 37 to 1) (l) to activate the reset. Here, when the indoor temperature decreases, the lower limit of operation for oxygen deficiency detection is the misfire detection level. When the indoor temperature rises again, the amplifier 57
As the level of oxygen production increases, so does the level of oxygen deficiency. In this way, the oxygen deficiency level is varied between the Zener voltage determined by the constant voltage diode 52 and the misfire detection level according to the indoor temperature, thereby preventing malfunction of the oxygen deficiency detection circuit due to unstable combustion due to the influence of room temperature. .

Effects of the Invention As described above, according to the present invention, when the indoor temperature decreases, by reducing the oxygen deficiency level, combustion instability occurs when the indoor temperature temporarily decreases, and combustion failure occurs when the indoor temperature rises slowly. This has the effect of preventing malfunction of the oxygen deficiency detection circuit due to reasons other than oxygen deficiency, such as stability.

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[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional safety device, and FIG. 2 is a circuit diagram of a safety device according to an embodiment of the present invention. 2...Burner, 3...Frame rod, 1o...
... Oxygen deficiency detection detector, 11 ... Misfire detector, 12 ... AND circuit, 13-15 ... Resistor, 16 ... Capacitor, 17. ...Intensifier for timer, 18...Thermistor for indoor temperature detection, 37...OR circuit, 53-56...Resistor, 57... Multiplier . Hemi 1 person portrait/v, l"xq-Niya AJ1% 1iu
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Claims (1)

[Claims] a misfire detection circuit that uses flame rectification to detect misfire conditions such as oil starvation; an oxygen deficiency detection circuit that is set at a higher level than the misfire detection circuit and detects abnormal combustion in the event of oxygen deficiency;
The oxygen deficiency detection circuit includes an amplifying circuit whose output voltage varies depending on the state of the indoor temperature, and the oxygen deficiency detection circuit uses the output of the amplifying circuit as one input, and uses the input on one side as a combustion signal obtained by rectifying the flame. , A whose inputs are the output of the oxygen deficiency detection circuit and the output of a timer circuit that operates for a certain period of time at the beginning of combustion.
A safety device for a combustion machine characterized by inputting the output of an ND circuit to a safety circuit.