JPS62405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion safety device, which includes a combustion detection element that detects combustion flame, a voltage comparator that receives the output voltage of this combustion detection element, and a combustion detection device that detects combustion. It is driven by an oscillator composed of a voltage comparator or the like that superimposes an oscillation signal in a direction that cancels the output voltage of the element, and an output signal of the voltage comparator that is driven at the oscillation frequency of the oscillator by the input of the combustion detection element. A delay timer circuit comprising a fuel valve drive unit for controlling a fuel valve, a delay circuit receiving the oscillation output signal of the voltage comparator as input, and a voltage comparator etc. receiving the output of the delay circuit as input. The output of the is connected to the reference voltage terminal of the voltage comparator, and after the combustion detection element detects ignition, the reference voltage (detection level of the output voltage of the combustion detection element) is changed from the reference voltage before ignition to the combustion detection By configuring the device so that the reference voltage is changed in steps so that the reference voltage is close to the steady output voltage of the element, it is possible to speed up the detection of combustion flame ignition and misfire, and improve safety, fail-safe performance, and operability. The purpose is to measure the

Conventionally, there is a push-and-turn safety valve system that uses a thermocouple as a combustion flame detection element and is used in water heaters, bathtubs, stoves, and the like. In this method, a valve is opened by pressing a push button, knob, etc., and the fuel is ignited, and an electromagnet is operated by a thermocouple that is heated by the combustion flame generated by the ignition, and is configured to engage with the electromagnet. This structure holds the valve in the open position and attracts it.

Another method is to directly operate an electromagnetic relay using the electromotive force of the thermocouple, and use its contacts to control combustion control parts such as a fuel valve igniter and a timer. Since all of these safety devices use a thermocouple to directly drive a load such as a fuel valve, the valve drive current cannot be obtained unless the thermocouple is made of a material with a large wire diameter. Therefore, the heat capacity, or thermal time constant, of the combustion detection element becomes large, which poses a problem in responsiveness, and even if the fuel ignites, the safety valve cannot be held by suction until the thermocouple is sufficiently heated, causing problems in operability. In addition, there was a problem that the ignition response time and the misfire response time were long.

The present invention solves the above-mentioned conventional problems.

Embodiments of the present invention will be described below based on the drawings.

1 is the power supply, 2 is the operation switch, 3 is the power supply circuit,
4 is a combustion detection circuit consisting of a voltage comparator 5 which inputs the output voltage of a combustion detection element 6 for detecting a combustion flame; 7 is an oscillator having a voltage comparator 8; 9 is an AC drive output signal of the voltage comparator 5; 10 is a delay timer circuit having a voltage comparator 11 that receives the delay circuit 9 as an input; 12 is a fuel valve drive unit; and 13 is a fuel valve.

The operation switch 2 is operated in conjunction with a gas cock, and the pilot flame can be ignited in some way by separately operating the cock, and the fuel valve body is also configured to be able to be held under pressure.

14 is a transformer of the power supply circuit 3, and the low voltage terminal 14
a, 14b. 15 is a full-wave bridge rectifier diode, 16 is a smoothing capacitor, 17 is a resistor, and 18 is a constant voltage diode. Power circuit 3
is composed of the above components and has output terminals A, B, and C.

A voltage comparator 5 has power terminals 5a, 5b, input terminals 5c, 5d, and an output terminal 5e.

A voltage comparator 8 has power terminals 8a, 8b, input terminals 8c, 8d, and an output terminal 8e.

19 is a resistor, 20 is a capacitor, 21 and 22 are resistors, 23 is a resistor, 24 is a diode, 25 is a resistor, 26 is a diode, and 27 and 28 are resistors. Oscillator 7 having voltage comparator 8 with the above components
Configure.

A transistor 29 is driven at the oscillation frequency of the oscillator 7. A resistor 30 and a resistor 31 are connected in series with the combustion detection element 6 such as a thermocouple, and are connected to the input of the voltage comparator 5.

32, 33, 34, 35, and 36 are resistors connected to the input terminals 5a and 5b of the voltage comparator 5 to form the combustion detection circuit 4.

37 is a diode, 38 is a resistor, 39 is a timer capacitor, and 40 is a resistor, which inputs the AC drive output signal of the voltage comparator 5 formed by connecting the diode 37 to the output terminal 5e of the voltage comparator 5. A delay circuit 9 is configured.

11 is a voltage comparator and power terminals 11a, 11
b, has input terminals 11c and 11d, and an output terminal 11e.

The delay circuit 9 is connected to the voltage comparator 11 as an input.

41, 42, 43, 44, and 45 are resistors, and 46 is a diode, and these components constitute the delay timer circuit 10.

The diode 46 is connected to the input terminal 5 of the voltage comparator 5.
connected to d.

47 and 48 are resistors, 49 is a diode, 50,
51 and 52 are resistors, 53 and 54 are transistors,
Resistors 55 and 56 and a coupling capacitor 57 constitute a power amplifier circuit, which is connected to a transformer 58.

59 and 60 are rectifying diodes, 61 is a smoothing capacitor, and the fuel valve driving section 12 is composed of the above components, and has output terminals D and F to the winding 63 of the electromagnet 62 that constitutes the fuel valve 13.

Next, the operation will be explained.

By operating the gas stove, the operation switch 2 is turned on, and the pilot flame is ignited by piezoelectric ignition or discharge from an igniter.

The current passes through the operation switch 2, is applied to the power supply circuit 3, becomes a low voltage by the transformer 14, is full-wave rectified by the full-wave bridge diode 15, is smoothed by the smoothing capacitor 16, and is made constant by the voltage regulator diode 18. A smoothed DC voltage is obtained at the output terminals A and B, and a smoothed voltage is also obtained at the C terminal. becomes.

The oscillator 7 has resistors 21 and 22 connected to the input terminal 8c of the voltage comparator 8, and if the resistance value of the resistor 21 is R ₂₁ and the resistance value of the resistor 22 is R ₂₂ , then
It is set at the reference voltage V _s5 set by R ₂₂ /R ₂₁ +R ₂₂ × (voltage between A and B), and the other input terminal 8
A resistor 19 and a capacitor 20 are connected to d, and when the capacitor 20 is charged through the resistor 19 and the potential of 8d becomes higher than the reference voltage of 8c, the output terminal 8e becomes L (on). The basic operation of the voltage comparator 8 will be explained as follows.

Assuming that the voltages at input terminals 8c and 8d are V _8c and V _8d , (a) When V _8d < V _8c , output terminal 8e is H (off) (b) When V _8d > V _8c , output terminal 8e is L (on) When 8e becomes L (on), if the reference voltage of 8c and the resistance value of resistor 23 are R ₂₃ , (parallel resistance of R ₂₂ and R ₂₃ ) / (parallel resistance of R ₂₂ and R ₂₃ ) +R ₂₁ × (voltage between A and B), that is, The potential drops to the reference voltage V _S6 set in .

Then, the charge in the capacitor 20 is discharged through the resistor 25. When the potential of the input terminal 8d becomes lower than the potential of the input terminal 8c due to discharge, the output terminal 8
e becomes H (off). This state is shown in FIG.

In this way, the time T ₁ obtained by setting the reference voltages V _S5 and V _S6 , the charging time constant C ₂₀ × R ₁₉ of the capacitor 20 and the resistor 19, and the discharging time constant C ₂₀ × R 25 of the capacitor 20 and the resistor ₂₅ During the time T ₂ obtained by , the output terminal 8e repeatedly oscillates H (off) and L (on), and the transistor 29 turns off when the voltage comparator 8 is H (off) and turns on and off when it is L (on). An oscillator 7 is obtained.

Here, C ₂₀ × R ₁₉ and C ₂₀ × so that T ₁ = T ₂
By setting the time constant of R ₂₅ and the resistance values R ₂₁ , R ₂₂ , R ₂₃ , and R ₂₅ , it is possible to obtain the oscillator 7 that operates at a rectangular wave duty 1:1 oscillation frequency.

Next, the operation of the combustion detection circuit 4 before combustion detection will be explained using FIG. 6.

The input terminal 5d of the voltage comparator 5 is connected to the resistors 32 and 3.
Reference voltage V _S1 set in 3 = R ₃₃ /R ₃₂ +R ₃₃
× (A-B voltage V _AB ), and resistors 35 and 3
6 and 34 adjust the input offset due to component variations of the voltage comparator 5 with respect to the reference voltage V _S1 , and are connected to the input terminal 5c.

With respect to the reference voltage V _S1 of the input terminal 5d, the potential of the input terminal 5c is the voltage e 2 set by the resistance values R 30 and R 31 of the resistors ₃₀ and ₃₁ when not receiving the electromotive force of the combustion detection element _6. =R ₃₁ /R ₃₀ +R ₃₁ × (voltage across R _32, that is, V _AB -V _S1 ) is the input terminal 5 of the voltage comparator
Since it is driven by a transistor 29 that is turned on and off at the oscillation frequency of the oscillator 7 between c and 5d, the oscillation signal e ₂ is superimposed on the reference voltage V _S1 .

However, the potential of the input terminal 5c is lower than the potential of the input terminal 5d.
Since the potential is higher than that of , the output terminal 5e is L (on).
As a result, transistor 53 turns on, and a charging current temporarily flows to coupling capacitor 57 and transformer 58.
The current is applied to the transformer 58, but it soon stops flowing and the transformer 58
Because no alternating current flows through the winding 6 of the fuel valve 13
3 is not energized.

FIG. 7 shows the state after combustion is detected. When the combustion detection element 6 is heated by the combustion flame and a thermoelectromotive force is generated, and the input voltage e ₁ is applied to the input terminal 5c, the potential of the input terminal 5c changes to the input terminal. Since the potential is lower than the potential V _S1 of 5d, the output terminal 5e becomes H (off). However, since the oscillation signal of the oscillator 7 is superimposed between the input terminals 5c and 5d, the output terminal 5e repeats L (on) and H (off) due to the voltage _e2 across the resistor 31, and changes in conjunction with the oscillation frequency. Operate.

When the output terminal 5e is L (on), the transistor 5
3 is turned on, and when the output terminal 5e is H (off), the transistor 54 is turned on, and the transistors 53 and 54 are turned on.
is alternately turned on and off, and an alternating current flows to the transformer 58 through the coupling capacitor 57. transformer 58
Full-wave rectification and smoothing are performed on the secondary side of the DC power supply, and DC power is obtained at terminals D and E, and the winding 63 of the fuel valve 13 is energized. The time during which this current is applied is _t1 shown in FIG.

By energizing the winding 63, the electromagnet 62 of the fuel valve 13, which is pressed by the push operation, is attracted and held. Then, by opening the passage to the main burner with a quick operation, the main burner is ignited.

On the other hand, when the output terminal 5e of the voltage comparator 5 is H (off), the delay circuit 9
is input. The voltage of the timer capacitor 39 is the voltage divided by the resistors 38 and 40, and the time constant of C ₃₉ and R ₄₀ is V _C1 = R ₄₀ /R ₃₈ + R ₄₀ × (H of 5e).
(off) voltage) x (1-e-R ₃₈ +R ₄₀ /C ₃₉ R ₃₈ R
₄₀ t).

Reference voltage set by resistors 41 and 42 is connected to the input terminal 11d of the voltage comparator 11, and the input voltage V _C39 to the input terminal 11c is V _S
When t becomes higher than ₃ after ₂ hours, the output terminal 11e
becomes L (on). Therefore, when there is no combustion, the output terminal 5e is L (on), so the delay circuit 9
Since the voltage of the input terminal 11c is lower than that of the input terminal 11d, the output terminal 11e becomes H.
(off). This state is shown in FIG.

_Two hours after igniting the pilot flame, the output terminal 11e becomes L.
(ON), the input terminal 5d of the voltage comparator 5
The reference voltage V _S1 = R ₃₃ /R ₃₂ + R ₃₃ ×V _AB means that a resistor 45 is inserted in parallel with the resistor 33, so V _S1
teeth, The potential is lower than V _S1 shown by .

Then, as shown in Fig. 2, V at the time of ignition detection
Compared to _S1 , when the output terminal 11e turns on after ignition, the input terminal 5d becomes V _S2 , so a voltage close to the steady output voltage becomes the reference voltage with respect to the output voltage of the combustion detection element 6, and the input terminal For example, when the output voltage of the combustion detection element 6 drops when the combustion flame misfires, and when the input voltage of the input terminal 5c is high, the output terminal 5e is set to 5d.
becomes L (on) and is no longer engaged at the oscillation frequency of the oscillator 7, and the fuel valve drive unit 12 stops operating at _t3 hours, the power to the winding 63 of the fuel valve 13 is cut off, and the gas is cut off. Ru.

Therefore, when the reference voltage of the input terminal 5d becomes V _S2 , the misfire detection level is shifted to speed up the response.

Furthermore, the output of the output terminal 11e is the output of the output terminal 5e.
When the output of V _C39 becomes L (ON) and the fuel valve 13 is shut off, it is not input to the delay circuit 9.
is discharged through resistor 40 and v _C2 = V _C39e −
Descend at t/C ₃₉ R ₄₀ . However, input terminal 11
The reference voltage of d is Therefore, the reference voltage V _S2 of the input terminal _5d is maintained for ₄ hours until v _C2 falls below V _S4 and the output terminal 11e turns H (off), and the residual voltage of the thermoelectromotive force The voltage comparator 5 is set not to operate again.

Therefore, in the present invention, since the misfire detection level is set higher than that of the prior art, the misfire response time can be made faster. That is, in the conventional case, the time t ₅ in FIG. 2 can be made as early as time t ₃ in the present invention. In addition, in FIG. 2, 100 is the ignition detection level;
101 is a misfire detection level, 102 is a conventional misfire detection level, 103 is a thermoelectromotive force waveform of the combustion detection element 6, 5c is a voltage waveform of the input terminal 5c, 5d is a voltage waveform of the input terminal 5d, and the above-mentioned level V _S1 and V
Consists of _S2 . In FIG. 3, 11c is the voltage waveform of the input terminal 11c, which consists of v _C1 and v _C2 . 11d is the voltage waveform of the input terminal 11d,
It consists of the above-mentioned levels V _S3 and V _S4 . 11e is the voltage waveform of the output terminal 11e.

In addition, in the fuel drive unit 12, by matching the initial vibration frequency obtained by resonance between the coupling capacitor 57 and the transformer 58 and the oscillation frequency of the oscillator 7, an efficient sine wave alternating current is transmitted to the transformer 5.
Obtained at 8.

In addition, in the fuel valve drive unit 12, as shown in FIG.
4 through a coupling capacitor 57,
By configuring a power amplifier circuit that discharges the charge of the coupling capacitor 57 through the transistor 53 when it is L (on), the number of parts is small and the transistors 53 and 54 can be turned on and off reliably. It is. 65,6
6 and 67 are resistances.

Next, safety and fail-safe properties in the event of component failure in FIG. 1 will be explained.

In both cases of disconnection and short-circuit failure of the combustion detection element 6, even if a combustion flame occurs, no electromotive force is generated, so the output terminal 5e of the voltage comparator 5 does not turn on or off, and is not driven at the oscillation frequency of the oscillator 7. fuel valve 1
3 is not energized.

Furthermore, even when the oscillator 7 does not oscillate and the voltage comparator 8 is disconnected or short-circuited, and the voltage comparator 5 is disconnected or short-circuited, the oscillation is not transmitted to the transformer 58, so the fuel valve 13 is not energized.

The same applies when the transistors 53 and 54 are disconnected or short-circuited. In short, safety can be ensured because the oscillation system is not established when each component fails.

As described above, the combustion safety device of the present invention provides the following effects.

(1) By operating a voltage comparator that inputs the output voltage of the combustion detection element that detects combustion flame, and by superimposing the oscillation frequency of the oscillator and applying an alternating current component to the fuel valve drive unit, all parts It is possible to ensure safety and fail-safe performance against breakdowns.

(2) By matching the oscillation frequency of the oscillator with the frequencies of the coupling capacitor and the resonant circuit of the transformer, a sine wave alternating current can be obtained and the efficiency of the transformer can be maximized, making it possible to use a small transformer. A large amount of current can be obtained.

(3) Since the output voltage of the combustion detection element is applied to the input of the voltage comparator, the voltage comparator can be operated at a few mV, resulting in faster response times and shorter ignition response times. The misfire response time can be made faster.

(4) Since the misfire response is faster, the time for gas outflow is shorter than before, making it safer.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is an operating waveform diagram of a voltage comparator, Figures 3a and b are operating waveform diagrams of a voltage comparator, Figure 4 is a main circuit diagram showing another embodiment, and Figures 5a and b are voltage comparators. Figures 6a and b are operating waveform diagrams of the input and output sides of the voltage comparator before combustion detection, and Figures 7a and b are the voltage comparator after combustion detection. FIG. 3 is an operation waveform diagram of the input side and output side of the . 4... Combustion detection circuit, 5... Voltage comparator, 6
... Combustion detection element, 7 ... Oscillator, 8 ... Voltage comparator, 9 ... Delay circuit, 11 ... Voltage comparator, 12 ... Fuel valve drive section, 53, 54 ... Transistor (switching element), 57...Coupling capacitor, 58...Transformer.

Claims (1)

[Claims] 1. A combustion detection element that detects a combustion flame, a voltage comparator that receives the output voltage of the combustion detection element as input, and an oscillation signal applied to the voltage comparator in the direction of canceling the output voltage of the combustion detection element. an oscillator configured with a voltage comparator or the like that superimposes the oscillator, and a fuel valve drive unit that controls a fuel valve that is driven by an output signal of the voltage comparator that is driven at the oscillation frequency of the oscillator based on the input of the combustion detection element. and a delay circuit that receives the oscillation output signal of the voltage comparator as an input, and outputs the output of a delay timer circuit composed of a voltage comparator or the like that receives the output of the delay circuit as the reference voltage of the voltage comparator. terminal, and after the combustion detection element detects ignition, the reference voltage (detection level of the output voltage of the combustion detection element) becomes a reference voltage close to the steady output voltage of the combustion detection element from the reference voltage before ignition. A combustion safety device configured to change in steps. 2 In the fuel valve drive unit, the output state of the voltage comparator that operates at the oscillation frequency of the oscillator is L (ON).
The transformer is coupled to a power amplifier circuit configured to charge through a coupling capacitor through one switching element when the switch is in the high state (off), and discharge through the coupling capacitor through the other switching element when the switch is in the high (off) state. The combustion safety device according to claim 1, characterized in that a direct current component is obtained on the secondary side. 3. Claims characterized in that in a power amplification circuit, the cut-off frequency of LC resonance between a coupling capacitor and a transformer is matched with the oscillation frequency of an oscillator, so that a sine wave alternating current is obtained in the transformer. Combustion safety device according to paragraph 2. 4 In the fuel valve drive unit, when the output state of the voltage comparator that operates at the oscillation frequency of the oscillator is H (off), one switching element is charged via the coupling capacitor, and when it is L (on), the other is charged. Claim 1, characterized in that a transformer is coupled to a power amplifier circuit configured to discharge electricity through a switching element and a capacitor, and a DC component is obtained on the secondary side of the transformer. Combustion safety device. 5. The combustion safety device according to claim 4, wherein in the power amplification circuit, the oscillation frequency of the oscillator and the vibration frequency of the LC resonance are matched to obtain a sine wave alternating current to the transformer. 6. Connected to a voltage comparator in order to make the misfire detection level of the combustion flame higher than the ignition detection level of the output voltage of the combustion detection element by turning the output of the voltage comparator L (on), and to speed up misfire detection. A combustion safety device according to claim 1, characterized in that: