CH628171A5 - FLAME DETECTOR. - Google Patents

Description

The invention relates to a flame detector with a first circuit which receives the flicker frequency component of the emission of a flame at least in the wavelength range of the resonant radiation of carbon dioxide by photoelectric means and a bandpass filter and generates useful signals for an alarm means.

It is generally known that most flammable substances, such as wood, petrol, oil and hydrocarbons or carbohydrates, in short the organic substances, burn at around X = 2.7 μm and in particular around X = 4, when burning in the wavelength ranges. 4 (strongly emit xm. The radiation is emitted in line spectra and band spectra, the wavelength range of 2.7 (in water and CO2 and that of 4.3 Jim for carbon dioxide being characteristic. In the journal "Report of Fire Research Institute of Japan ”, Serial No. 30, December 1969, in the article“ Fire Detection Using Infrared Resonance Radiation ”, pages 55-60, in FIG. 6 the circuit of a detector sensitive to flame radiation and temperature is shown. This detector is designed for the infrared range, however it is not safe against false alarms: in the presence of interference radiation in the infrared range, such as radiators or stoves, whose heat radiation is caused by If the fan or the like is interrupted at a certain rhythm, a detector can undesirably generate an alarm even though there is no flame.

In French magazine 2151 148 two wavelength ranges or bands are evaluated for the alarm in case of fire. The selectivity results from the arrangement of two narrow-band optical filters, which are only transparent for the two wavelength ranges X = 2.7 and X = 4.3. The photoelectric voltages generated by these two wavelength ranges are evaluated for the fire alarm. The detector tilts - like attempts

628 171 4

have shown - in the case of interference radiation sources of suitable color temperatures - by means of FIGS. 9, 10, 11

to false alarms, so that the false alarm rate with this in FIGS. 1 a ', 1 b, 1 c are pulses A, B, C on the time

Detector could not be lowered effectively. açhse t carried out. These impulses appear at the connection

The object of the present invention is to drastically reduce the false alarm points A, B, C of the exemplary embodiments in FIGS. 9, 1 and 11 and 11. A flame detector is shown in FIG. which, despite the occurrence of sources of interference, circles every flame that receives the flickering frequency of a flame, clearly recognizes it as such and generates the fire alarm. Pulse is generated and in connection point A of the above

Emissions in the wavelength range of exemplary embodiments in FIGS. 9, 10, 11 are also to be pending. According to FIG. About X = 4.4 p.m can be evaluated for the alarm. The 1 a is assumed that at the same time in the second current standard window glass or lamp glass the emission in io circle an interference signal has been received and at point B it does not pass through this waveband. This ensures that a rectangular pulse is present. The linking means, that the solar radiation as well as the normal electrical ches later in connection with the various execution light in the rooms in which the detector is housed, examples of Figures 9,10,11,12,13, none discussed Has an influence on the alarm generation of the detector. The jsj is constructed in such a way that in this case no flame detector output signal can also be used outdoors. H. is generated outside of 15. In Fig. 1 this has been shown by housing rooms, since it is known that the emission dasC = 0.

spectrum of sunlight a so-called energy gap at Fig. 1b shows the case) that in the first circuit there is an X = 4.3 (in. Also here the sun is generated as an interference flame signal and a corresponding pulse is switched off in the source. Connection point A is present, assuming that

Furthermore, parts of the wavelength range X = 6 [i.m 2o in the second circuit at the same time no interference signal should have no influence on the alarm generation. This will catch and that the connection point B of the second eliminates the effects of radiators and stoves. Circuit interference pulses occur with the useful pulses The flame detector is also designed so that at a point A do not coincide. At the starting point, interfering radiation from a hot body below X = 6 [in the 0 of the linking means of the exemplary embodiments of the FIG. No false alarm can be generated. 25 ren 9, 10 and 11, a signal only appears when a user

An alarm can only be generated if there is a signal in point A of the first circuit.

There is a flame in the wavelength range of X = 4.4. Fig. 1 c shows the point p emitted at point A of the first circuit. This alarm is also given if there is still a useful signal due to a flame and a hot body in the wavelength range X ^ 6 p, m in the second circuit (connection point B) which emits interference radiation over time. The alarm must be delayed even after the presence of an interference signal. The linking takes place when the interference radiation of the hot body is generated approximately by means of FIGS. 9, 10 and 11 only when an output is modulated with the flickering frequency of the flame. signal when a useful pulse at connection point A and no

The invention, which has to solve these objects, is defined in the glitch at the connection point B at the same time existing part of claim 1. that are. Fig. Lc shows that at a certain time

Embodiments of the invention are explained in more detail with reference to the 35 overlap of these two pulses of the output pulse on the drawing. They show: Connection point C of the connecting means disappears.

Figures la, b, c show the mode of operation of the linkage flame spectrum shown in the embodiment. The distribution of the intensity of a typical example of FIGS. 9, 10, 11 is shown in FIGS. On the abscissa is the Wel circuit; ..... length range X shown in the unit jj, m. On the ordinate

Figure 2 is a graphical representation of the intensity distribution 40, the intensity is drawn in the respective length range over the wavelength range of a flame; 2 clearly recognizes a strong intensity in the wave

FIG. 3 shows a typical spectral length range X = 4.4 μm in graphical representation. This is the wavelength range of intensity distribution over the wavelength range of a hot carbon dioxide. The intensity distribution has two distinct bodies; pronounced maxima at 2.8 and 4.4 µm. The intensity of the

Figure 4 in a graphical representation the passband of the 45 flame can be neglected at> 6 p.m.

optical filters 1 and 9 of the two circuits; FIG. 3 shows the intensity distribution of a hot one

Figure 5 is a graphical representation of the passband of the body at about 300 ° C. On the abscissa, the wavelength is two useful signal circuits and one interference signal current in the unit (in and on the ordinate is the intensity of the Kre's; ... Emission of an interfering emitter applied

Figure 6 in a graphical representation the characteristic 50 corresponds to a heat radiator, for. B. heating spirals or Koch intensity distribution of solar radiation over their emission plates. It is assumed that the radiation e.g. B. by wavelength; ... a fan is interrupted periodically. This periodic

Figure 7 different cases of the mode of action for the interruptions, which are in the frequency range of 4-15

Flame detector according to the invention; Hz can be used later in connection with the off

FIG. 8 shows a construction example of an optical filter 55, exemplary embodiments of FIGS. 9, 10, 11 and 12 are described and photoelectric means in more detail; ben. Another source of interference of the same type can turn off

FIG. 9 shows a first exemplary embodiment of the entire electric puff tube in an internal combustion engine, which is known to see a circuit in a partially digital version for the Flam-only JOSe and therefore carries out movements that are unreleased; are in the frequency range of 4-15 Hz. How later

FIG. 10 shows a second exemplary embodiment of the circuit of the flame detector designed in more detail in part 60, which is explained in more detail in connection with FIGS. 9, 10, 11, 12, this frequency lies in the area of the flickering flame, which; . . The type of sources of interference discussed so far will be

Figure 11 shows a third embodiment of the circuit according to the invention with Si, which later in connection with flame detector, which is partially digitized; Figures 7a to f and the associated table

Figure 12 shows a fourth embodiment of the in part 6? is explained in more detail. Another type of interference source can be an analog circuit for the flame detector heating element or radiator or furnace, which is an essential

the; have a lower radiation temperature than the Si type

Figure 13 shows another embodiment of the linking of the pig. 3. The radiator, stove or radiator will be

5

referred to by appointment as S2 and emit radiation in the wavelength range above 5.5 (im. According to the agreement, this interference source type S2 is also intended to interrupt the radiation in the range of 4-15 Hz For the sake of completeness, it should be pointed out that the interference radiation in the exemplary embodiments in FIGS. 9 to 12 does not prove to be disruptive if it is not interrupted the exemplary embodiments 10 described in more detail.

The interference source type S1 / S2 is explained in more detail in the table which is described in connection with FIGS. 7 and 8.

FIG. 4 shows in a graphic representation the pass regions 15 of the filters 1 and 9 of the two circuits of the exemplary embodiments in FIGS. 9, 10, 11, 12. According to FIG. 4, the first circuit, which responds to the emission of flames, is provided with a filter 1, which has a wavelength pass band around 4.4 μm. The filter 9, which is arranged in front of the second circuit of the exemplary embodiments mentioned, has a wavelength passband which is greater than 6 p.m. In FIG. 4, the filter 9, which transmits the interference radiation, has a passband with a near 6 (in the steeply rising flank and a gradually falling flank in the larger wavelength ranges).

This means that a relatively inexpensive filter can be used for these purposes and does its job very well in the exemplary embodiments in FIGS. 9 to 12.

5 shows the passband areas of two useful signal circuits of the first type and an interference signal circuit of the second type in a graphical representation. A first circuit has a filter 1 with a wavelength pass band of about 2.8 (im. Another first circuit has a pass filter 1 with the wavelength pass band around 4.4 µm. A second circuit has a 'filter 9 with a wavelength passband of over 6 (im. At this point it is pointed out that three circuits can be provided according to FIG. 5. Of course, even more circuits can be arranged. The exemplary embodiments of FIGS. 9 to 12 are described with reference to FIGS 5 has a passband which has steep flanks on both sides, and is a filter which is relatively more expensive than the filter of Fig. 4 which does not have a 45 It should only be said here that in the exemplary embodiments which will be discussed in more detail later, both expensive and bi Any filters can be used.

6 shows a graphical representation of the characteristic intensity distribution of normal solar radiation. The wavelength X is in [im on the abscissa and the intensity is plotted on the ordinate in relative units. The graphical representation of FIG. 6 shows that the sunlight has maxima at some characteristic points and minima at certain 55 points. Particular reference is made to the intensity minimum, which is close to 4.3 (im.

7 shows a graphic representation of the mode of operation of the exemplary embodiments in FIGS. 9 to 12 in combination with the details in FIGS. 8 to 13. In the individual FIGS. 7a, b, c, d, e, f, the wavelengths are X. in (im plotted on the abscissa and the intensities of the passband of filters 1 and 9 in relative units on the ordinate.

7a shows that there is no flame and no interference. At points A and B of FIGS. 9, 10, 11, 12 there is therefore no pulse or voltage. This means that no alarm is generated.

Fig. 7b shows the presence of a flame in the

628171

Wavelength range of Figures 4 or 5. In this case there should be no interference. Therefore, there is a pulse or a voltage at point A of the first circuit of the exemplary embodiments in FIGS. 9 to 12. There is no voltage at point B of the second circuit. In this case an alarm is generated.

FIG. 7c shows the case where there is a disturbance which may be in the wavelength range of FIG. 4 or 5 and that there is no flame. The source of interference is assumed to be type S2, which according to the previous definition can be a radiator, radiant heater or oven with a temperature of around 100 ° C. According to the case shown in FIG. 7c, there is no voltage at point A and at point B of the circuits in FIGS. 9 to 12 there is a voltage or a pulse. An alarm is not given in this case.

FIG. 7d shows the case in which there is both a flame and interference radiation from the interference source of type S2. The wavelength ranges are selected in accordance with FIGS. 4 or 5. In this case there is a voltage or a pulse at points A and B of the circuits in FIGS. 9 to 12. If voltage and pulse are present at these points A and B at the same time, there is no output signal at point C via the connecting means 18, 26, 59 with the inverters 17, 25, 58, but since flame and interference radiation in a wide frequency range from 4 to 15 Hz flicker, there is a statistical distribution in such a way that flame and interference radiation occur only here and there synchronously at points A and B (Fig. 7d) or not synchronously (Fig. 7b or Fig. 7c). There are so-called intermediate stations between these situations, where the voltages or pulses at points A and B can partially overlap. In this case, too, which is shown in FIG. 1 c, there is a clear alarm signal at point C. This ensures that a flame triggers an alarm even when there is interference radiation.

7e shows the case in which interference radiation of an interference radiation type Si radiates over a very wide wavelength range. Such an interference radiator, which can be a heat radiator (heating spirals or hot plates) with a radiation temperature of about 300 ° C (Fig. 3), affects not only the circuit for receiving the interference radiation (filter 9), but also the circuit for receiving the flames of the exemplary embodiments in FIGS. 9 to 12. This means that at points A and B there are synchronous voltages or pulses. This is shown in Fig. 1 a. As a result of this synchronization between the useful voltage and the interference voltage, no alarm signal is generated at the starting point C of the linking means 18, 26, 59. This is also correct since there is no flame. For better illustration, the portion of the interference radiation which reaches the linking means via the first circuit (useful signals) is denoted by A 'in FIG. 7e.

Another case is provided in FIG. 7f. There should be a flame there and, at the same time, interference radiation of the interference source type Si. The portion that is transmitted into the first circuit due to the interference radiation is denoted by A '. The interference radiation part that reaches the second circuit is denoted by B. Since both parts originate from the same source of interference, they are also synchronous, that is, at points A and B, voltages or pulses occur simultaneously, so that no interference signal at output C of the connecting means of FIGS 12 can be generated. This is the case as shown in Fig. 7e. The flame of FIG. 7f generates a voltage or a pulse at point A of the exemplary embodiments in FIGS. 9 to 12, which can either occur simultaneously or not simultaneously with the interference radiation A 'and B. The linking means 18 generates an alarm signal on

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6

Output C if there is a voltage or a pulse corresponding to the flame at point A and at the same time there is no voltage signal from the interference radiation at point B. After a certain waiting time, the detector issues an alarm.

The following table may serve to provide a better overview of the various cases in FIGS. 7a to f. The numbers that are listed in the table under the “Comments” heading have the following meanings:

1. no alarm pulse because there is no flame

2nd alarm pulse because of flame

3. Monitoring status

4. without interference

5. with disorder

6. A 'and B coinciding in time gives C = 0; A: = A + A '

7. A and B not coinciding in time gives C = 1; A: = A + A '

table

adoption

Result too

flame

A

Disorder

B

A 'type of

C Comments

Figure 7

Yes No

Yes No

Disorder

on a

0

No

0

0 1) 3) 4)

b yes

1

No

0

- -

1 2) 4)

c no

0

Yes

1

0 Sz

0 1) 3) 5)

d yes

1

Yes

1

0 S2

1 2) 5)

e no

0

Yes

1

1 Si

0 1) 3) 5) 6)

f yes

1

Yes

1

1 Si

0; 12) 5) 6) 7)

FIG. 8 shows the constructive embodiment of the filter including photoelectric means as used in the exemplary embodiments in FIGS. 9 to 12. 8, the filter 1 of the first circuit consists of a germanium or silicon layer 70, an interference filter 71 and a quartz layer 72. These different layers are plane-parallel, the thickness of the germanium layer 70 being approximately 1 mm and the interference filter 71 being approximately 1 to 50 µm and the thickness of the quartz layer 72 is about 0.5 mm. The diameter of these layers or the filter 1 is approximately 8 to 12 mm. The interference filter 71 can consist of several layers. Each layer is made of a dielectric material. The filter consisting of layers 70, 71 and 72 is housed in a so-called «TO-5» housing. Such a housing is available everywhere on the market under this brand name. The housing is connected to the filter via an adhesive connection 73. The sensitive element 74 is possibly accommodated in the housing with a field effect transistor. This element converts the optical rays into electrical signals. These signals pass through lines 75 to the circuits of FIGS. 9 to 12. The sensitive element 74 can be a pyroelectric detector, such as, for. B. lithium tantalate or lead zirconate titanate, or an NTC thermistor or a photoconductor or a thermopile. The filter or the photoelectric means 1, 2 of FIG. 8 is provided for the first circuit in the exemplary embodiments of FIGS. 9 to 12. The filter 9 for the second circuit of the same exemplary embodiments is constructed somewhat differently. The quartz layer is eliminated. The spatial dimensions are the same as previously described. In addition, the sensitive means 74 is constructed in accordance with its application in the first circuit or in the second circuit. For example, a pyroelectric detector can be used for both circuits. The NTC thermistor, the photoconductor and the thermopile can also be used for both circuits. If that's sensitive

Element 74 is designed as a photovoltaic cell or as a UV-sensitive, gas-filled tube, the photoelectric means 2 can only be used in the first circuit. In this case, one can even do without the filter consisting of the layers 70.71.72 s.

Fig. 9 shows a first embodiment, which consists of two circuits. The first circuit is equipped with a filter 1 and a photoelectric means 2, whereby the wavelength range X = 4.1 to 4.8 µm is transmitted. This wavelength range is set so that the emission radiation of a flame through filter 1 onto the photoelectric means (sensitive element 74 of FIG. 8) arrives and triggers corresponding electrical useful signals there. These useful signals are amplified in the following amplifier 3. These amplified signals are designated 53 below FIG. 9. The subsequent bandpass filter 4 has a passband for the flickering frequency of the flame, which is between 4 and 15 Hz. This is followed by an amplitude limiter 5, which cuts off the amplitudes of the amplified signal 53 and generates 20 trapezoidal signals 54. These arrive at the differentiator 6, which generates a voltage pulse 55 on each rising edge of the signals 54. These are rectified in the following rectifier 7 in such a way that only the differentiated voltage pulses 56 of the one polarity reach the subsequent monostable multivibrator 8. This generates pulses 50 of constant amplitude and width. In this case, the amplitude and width are not dependent on the intensity of the flame. The second circuit, the filter 9 of which has a wavelength pass band of X = 6 to 6.7 μm, is constructed in the same way as the first circuit just discussed. The amplifier 11 amplifies the electrical signals of the photoelectric means 10. The bandpass filter 12 has a passband for the flickering frequency of the interference source, which is also in the range from 4 to 15 Hz. The amplitude limiter 13, the differentiator 14, the rectifier 15 and the monostable multivibrator 16 function in the same way as already discussed in connection with the first circuit. The monostable multivibrator 16 generates pulses 51 with constant amplitude and constant width. The amplitude and width of these pulses are not dependent on the intensity of the interference radiation. It is now assumed that only one flame emission is present in FIG. 9. In this case, the first circuit generates the pulses 50 at point A. The 45 second circuit generates no pulse at point B (state = 0). The subsequent inverter circuit 17 therefore generates the state “1”, which reaches the logic element which is designed as an AND gate, so that the AND gate generates a pulse at its output C. This pulse thus reaches the downstream integrator 19, which by means of the timer 20 after a certain time of, for. B. 5 to 15 s is reset. In the digital embodiment of the AND gate 18, the integrator 19 contains a counter which counts the output pulses C of a minimum width. Only when a 55 series of output pulses reaches the counter and a certain threshold value, which is set beforehand on the counter, is exceeded, does the integrator 19 give an alarm pulse to the subsequent circuit parts. The alarm pulse can only be generated by the integrator if the threshold 60 value of the counter has been exceeded before the timer 20 resets it. So that an alarm is not triggered too quickly, e.g. B. within two seconds, a delay element 21 is also provided, which delays the transmission of the alarm signal by a few seconds and only controls the alarm center 22 when the alarm signal from the integrator 19 continues within this time. The case that is drawn in FIG. 7b was discussed with reference to FIG. 9. The case of FIG. 7f will now be briefly explained.

7

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Since there is a flame, the monostable multivibrator 8 generates the pulses 50 at point A. Because of the presence of a type Si interference source, the monostable multivibrator 16 also generates pulses 51 at point B, which are present at the same time as the pulses 50. Furthermore, the type Si interference source has such a large emission range that the interference radiation influences the first circuit and the monostable multivibrator generates 8 pulses 50 at point A. The pulses 50, which originate from the interference radiation (see portion A 'of FIG. 7f), are always in synchronism with the pulses 51 at point B. As a result of the inverter 17, the AND gate 18 is 50.51 when these synchronously located pulses occur blocked. Since the flickering frequencies of flame and interference radiation are statistically distributed to one another, there are temporal differences between the pulses 50 and 51 at points A and B, so that the AND gate 18 is largely open for the transmission of the useful pulses 50 to the subsequent integrator 19. This ensures the generation of the alarm in the presence of a flame and fault. All of the examples in FIG. 7 and the table subsequently presented can be carried out using the exemplary embodiment in FIG. 9. The individual electronic circuit parts of the two circuits in FIG. 9 have not been described in detail since they are known as such in the electronic literature. The following literature is referred to:

"Linear Applications Handbook", Volume 1,2,1977, from National Semiconductor.

Applications of Operational Amplifiers, McGraw-Hill Verlag, New York, 1976.

"Sourcebook of Electronic Circuits", McGraw-Hill Verlag,

New York, 1968.

CH-PS 519 716, CH-PS 558 577.

The embodiment of FIG. 10 is constructed essentially similar to the embodiment of FIG. 9. The only difference is that the pulses which appear at points A and B are no longer independent of the flickering frequency of the flame and the interference radiation Have width. In the exemplary embodiment in FIG. 10, the pulses 41 have a width which depends on the period of the vibrations 40. The period of these vibrations 40 represents the flickering frequency of the flame or the interference radiation. The width or duration of the pulses 41 and 43 are determined by the threshold 42 of the comparators 30 and 31, respectively. The two circuits are equipped with the same electronic components. The filters 1 and 9 have the same passband ranges as in the exemplary embodiment in FIG. 9. The photoelectric means 2 and 10, the amplifiers 3 and 11 and the bandpass filters 4 and 12 are constructed in the same way as described above. The bandpass filters 4 and 12 are followed by the comparators 30 and 31. The output signals from these comparators, which are shown at the top in FIG. 10, reach the rectifiers 32 and 33. The mode of operation of the comparators 30 and 31 is explained in more detail on the basis of the following consideration. The value of the output signal is:

a if SA (t)> e

-awennSA (t) <e \

Herein mean: SA = amplitude of the input signal on the two comparators 30 and 31, e = threshold value.

The mathematical expression states that the same input signal SA can be present both for the first circuit (comparator 30) and for the second circuit (comparator 31) and the output pulses of the two comparators have a constant amplitude + a or -a. The threshold e is therefore provided so that the so-called noise in the two circuits can be better suppressed. The operation of the elements 19, 20, 21, 22 after the AND gate 18 is the same as in the exemplary embodiment in FIG. 9. Here too, the integrator 19 has a counter with a predetermined threshold value. The counter is reset after a certain time of about 5 to 15 s. If the counter has exceeded its threshold value before this reset, a signal is sent to the delay element 21. Instead of the counter, a capacitor can be provided in the integrator 19, which capacitor is successively charged by the pulses 41, which are passed through the AND gate 18 at point B of the second circuit when the pulses 43 are absent. For the sake of completeness, it should also be pointed out that the inverter 17 gives the inverted pulses 44 to the second input of the AND gate 18 and thus blocks or opens the AND gate for the transmission of the pulses 41 from the first circuit.

The embodiment of FIG. 11 shows the two circuits with similar electronic components as previously described. However, 4 and 12 demodulators 38 and 39 are arranged after the bandpass filter. Each of these demodulators consists of a rectifier 34 or 36 and a low pass 35 or 37. These demodulators 38, 39 are again followed by comparators 30, 31 and rectifiers 7.15. By arranging the demodulators 38 and 39, the modulation envelope 46 of the rectified signal half-waves 45 can be formed from the flicker frequency 40 of the flame and the interference radiation. The demodulators 38, 39 are not particularly described here since they are generally known from the literature. Reference is made to the literature references already mentioned.

The comparators 30 and 31 take into account the predetermined threshold value e in the same way as already described in connection with FIG. 10. 7, the first circuit generates corresponding envelopes 46. At point A, the pulses 47 result, the width of which depends on the modulation envelope 46, which envelops the oscillations 45 of the flickering frequency of the flame. The amplitude of the pulses 47 is always constant. In the presence of interference radiation according to the various cases of FIG. 7, the second circuit also generates modulation envelopes 46. The modulator 31 takes the threshold value e into account. At point B, the pulses 48 are generated, the width of which depends on the modulation envelope 46, which envelop the vibrations 45 of the flicker frequency of the interference radiation. The downstream inverter 17 generates the inverted pulses 49. The AND gate 18 functions in the same way as has already been explained in connection with the previous exemplary embodiments. The integrator 19 can include either a counter or a capacitor. The formation of the threshold value and the time reset by the timer 20 have also been described several times.

The fourth embodiment of FIG. 12 also again consists of the two circuits and a linkage 26, which in this case is designed as a phase comparator. Filters 1 and 9 have the same passband as in the previous embodiments. Likewise, the photoelectric means 2 and 10 are of equivalent design. Amplifiers 3 and 11 amplify the signals. Pass filters 4 and 12 only let the flicker frequency in the range from 4 to 15 Hz. These vibrations in the flicker frequency range of the flame and the interference radiation are designated by 60 above FIG. 12. These vibrations reach the threshold value detectors 23 and 24. If there is a flame, a vibration 61 is present at point A of the first circuit. In the presence of interference radiation, an oscillation 62 is present at point B of the second circuit. The oscillation 62 is

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

628 171 8

sweeper 25 converted into vibration 63. The vibration only reaches a circuit of the second type for the interference signals of the supply signal 61 of point A only through the pha interference source. This is to be understood in such a way that the comparator 26 on the rectifier 27 and the integrator 19, if each useful signal circuit in a different wavelength - the signal 63 is in the same direction as the signal 61. This means that the range is working, while the interference signal circuit in the other Words that the signal 62 must be in the same direction 5 length range over 6 | im, as z. B. in Fig. 5 for signal 61. The expression, "in the same direction" or.

“Inconsistent” should be understood to mean that if the sign is the same, the sign is the same and if the difference is the same, FIG. The mode of operation until the alarm is given. The linking device is designed as a NOR gate. The integrator 19 and the delay element 21 are the same as for a NOR gate 59, one input of which has already been described several times. ter 58 contains. The operation of the linking agent 58.59

Finally, it should also be pointed out that the configuration is the same as the mode of operation of the connecting means, exemplary embodiments of FIGS. 9, 10, 11, 12, several circuits 17, 18 of the exemplary embodiments of FIGS. 9, 10 and 11. Therefore of the first type for the Useful signals of the flame emission and 15 are not discussed in more detail here.

G

8 sheets of drawings

Claims (16)

628171 PATENT CLAIMS 1. Flame detector with a first circuit which receives the flicker frequency component of the emission of a flame at least in the wavelength range of the resonance radiation of the carbon dioxide by means of photoelectric means and a bandpass filter and generates useful signals for an alarm means, characterized in that to prevent the response to one generated by a heat radiator Interference radiation a second circuit with an optical filter (9) with a wavelength passband for wavelengths above the resonance wavelength range of the carbon dioxide and a photoelectric means (10) which receives the transmitted radiation and generates an interference signal, and a further bandpass filter (12) with the same flicker frequency passband of the interference radiation as in the first circuit for the flicker frequency of the flame, and a linking means (18, 26, 59, 17, 25, 58) that links the first and second circuits and is designed to take into account de r statistical distribution of the flickering frequencies of the flame emission and the interference radiation, the useful signals of the first circuit are blocked in the event of a simultaneous output signal of the second circuit and are passed to the alarm means (22) in the absence or inconsistent occurrence of the output signal of the second circuit. 2. Flame detector according to claim 1, characterized in that the first circuit contains: an optical filter (1) with a passband for the infrared radiation of the flame, which includes the resonance radiation at 4.4 µm, a photoelectric means (2) for receiving the infrared radiation and for generating corresponding electrical useful signals, an amplifier (3) for amplifying the electrical useful signals of the photoelectric means (2), a bandpass filter (4) with a passband for the flickering frequency of the flame, a signal converter (5, 6, 7, 8) which converts, differentiates the amplified output signals of the bandpass filter and generates right-hand corner pulses (50) of the same width and amplitude, and that the second circuit contains: an optical filter (9) with a wavelength transmission range X> 6 (in the interference radiation, a further photoelectric means (10) for receiving the interference radiation and for generating corresponding electrical interference signals, a further amplifier (11) for amplifying the electrical interference signals, a further bandpass filter (12) with the same passband for the flickering frequency of the interference radiation as in the first circuit for the flickering frequency of the flame, a further signal converter (13, 14, 15, 16), which converts and differentiates the amplified output signals of the further bandpass filter and generates interference pulses (51) of the same width and amplitude, the linking means (18) formed as a UN D gate having the useful square-wave pulses (50) on its first input and the inverted interference square-wave pulses (52) the same on its second input, which contains an inverter (17) Latitude and amplitude receive (Fig. 19). 3. Flame detector according to claim 1, characterized in that the first circuit contains: an optical filter (1) with a passband for the infrared radiation of the flame, which includes the resonance radiation at 4.4 n.m, a photoelectric means (2) for receiving the infrared radiation and for generating corresponding electrical useful signals, an amplifier (3) for amplifying the electrical useful signals of the photoelectric means, a bandpass filter (4) with a passband for the flickering frequency of the flame, a signal converter (30, 32) which generates useful rectangular pulses (41), the width of which depends on the period of each individual oscillation (40) of the useful signals representing the flickering frequency of the flame and the amplitude of which is constant, and the second circuit contains: a further optical filter (9) with a wavelength passband of X> 6 (in the interference radiation, a further photoelectric means (10) for receiving the interference radiation and for generating corresponding electrical signals, a further amplifier (11) for amplifying the electrical interference signals of the further photoelectric means (10), a further bandpass filter (12) with the same passband for the flicker frequency of the interference radiation as in the first circuit for the flicker frequency of the flame, a further signal converter (31, 33) which generates interference rectangular pulses (43), the width of which depends on the period of each individual oscillation (40) of the interference signals representing the flickering frequency of the interference radiation and the amplitude of which is constant, the linking means (18) formed as an AND gate having the useful square-wave pulses (41) on its first input and the inverted interference rectangular-wave pulses (44) of different widths on its second input, which contains an inverter (17) and constant amplitude (Fig. 10). 4. Flame detector according to claim 1, characterized in that the first circuit contains: an optical filter (1) with a wavelength passband for the infrared radiation of the flame, which includes the resonance radiation at 4.4 (im, a photoelectric means (2) for receiving the infrared radiation and for generating corresponding electrical useful signals, an amplifier (3) for amplifying the electrical useful signals of the photoelectric means (2), a bandpass filter (4) with a passband for the flickering frequency of the flame, a signal converter (38,30,7), the useful square-wave pulses (47) generated, the width of one of the vibrations (45) of the Flickering frequency of the envelope enveloping the flame (46) depends and whose amplitude is constant, and that the second circuit contains: another optical filter (9) with a wavelength Pass range of X> 6 (in the interference radiation, another photoelectric means (10) for receiving the interference radiation and to generate corresponding electrical Signals, a further amplifier (11) for amplifying the electrical interference signals of the further photoelectric means (10), a further bandpass filter (12) with the same passband for the flicker frequency of the interference radiation as in the first circuit for the flicker frequency of the flame, a further signal converter (39, 31, 15) which generates interference rectangular pulses (48), the width of which depends on an envelope curve (46) enveloping the vibrations (45) of the flicker frequency of the interference radiation and the amplitude of which is constant, the linking means (18) formed as an AND gate having the useful square-wave pulses (47) on its first input and the inverted interference square-wave pulses (49) of different widths on its second input, which contains an inverter (17) and constant amplitude (Fig. 11). 5. Flame detector according to claim 1, characterized in that the first circuit contains: an optical filter (1) with a wavelength passband 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 628 171 25th 30th rich for the infrared radiation of the flame, a photoelectric means (2) for receiving the infrared radiation and for generating corresponding electrical useful signals, an amplifier (3) for amplifying the electrical useful signals of the photoelectric means (2), a bandpass filter (4) with a passband for the flickering frequency of the flame, a threshold detector (23) which detects the electrical vibrations representing the flickering frequency of the flame (60) receives a useful output signal from the bandpass filter (4) and when a certain threshold value is exceeded (61) generated, and that the second circuit contains: a further optical filter (9) with a wavelength transmission range of X <6 um the interference radiation, a further photoelectric means (10) for receiving the interference radiation and for generating corresponding electrical signals, a further amplifier (11) for amplifying the electrical interference signals of the further photoelectric means (10), a further bandpass filter (12) with the same passband for the flicker frequency of the interference radiation as in the first circuit for the flicker frequency of the flame, a further threshold value detector (24) which receives the electrical vibrations representing the flicker frequency of the interference radiation from the further bandpass filter and generates an interference output signal (62) when a certain threshold value is exceeded, wherein the linking means (26), formed as a phase comparator, receives the useful output signal (16) of the threshold value detector on its first input and the inverted interference output signal (63) of the other threshold value detector (24) on its second input, which contains an inverter (25). Fig. 12). 6. Flame detector according to claim 1, characterized in that the linking means (18) is designed as a NOR circuit (59) and contains an inverter (58) in its first input (Fig. 13). 7. Flame detector according to one of claims 1-6, characterized in that the linking means (18) is followed by an integration element (19) that adds up the useful output signals of the linking means, and that contains a reset circuit (20) that added up the Resets the content of the integration element (19) and thus avoids false alarms due to 45 isolated, undesired impulses (FIGS. 9, 10, 11, 12). 8. Flame detector according to claim 7, characterized in that the integration element (19) contains a counter counting the output signals of the linking means (18), and the 50 reset circuit (20) contains means which periodically or in the absence of the output signals within a certain counter Reset time period. 9. Flame detector according to claim 7, characterized in that the integrating element (19) contains a capacitor which sums up the output signals 55 of the linking means (18), and the reset circuit (20) contains means which discharge the capacitor with a greater discharge time constant than it does through the Output signals is charged. 10. Flame detector according to one of claims 7-9, characterized in that the integration element (19) is followed by a threshold switch which generates an output signal for the alarm means (22) when the summed useful signals of the integration element (19) exceed a certain threshold value (FIGS. 9, 10, 11, 12). 11. Flame detector according to claim 10, characterized in that a delay element (21) is arranged between the threshold switch and the alarm means (22), which gives the output signal of the threshold switch to the alarm means (22) with a time delay. 12. Flame detector according to one of claims 1-11, characterized in that at least two circuits of the first type (1,2,3,4,5,6,7,8; 30,32; 38,30,7; 23) for generating electrical useful signals corresponding to the optical wavelength ranges X = 4 to 4.8 μm, 3 to 3.8 μm, m, 1.8 to 2.8 μm, 0.7 to 1.2 pm or 0.1 to 0 , 5 | im in the flame and a circuit of the second type (9,10,11,12,13,14,15,16; 31, 33; 39,31,15; 24) for generating electrical interference signals corresponding to the optical wavelength range X <6 around the interference source are connected to the linking means (18, 26, 59, 17, 25, 58). 13. Flame detector according to one of claims 2-12, characterized in that the optical filter (1) of the first circuit from a quartz layer (72), semiconductor layer (70) and a broadband interference filter (71) in the wavelength range X = 4.0 to 4.8 n, m exists (Fig. 8). 14. Flame detector according to one of claims 2-12; characterized in that the optical filter (1) of the first circuit consists of a quartz layer (72), germanium layer (70) and a broadband interference filter (71) in the wavelength range X = 4.0 to 4.8 Jim (Fig. 8). 15. Flame detector according to one of claims 1-14, characterized in that the first photoelectric means (2) consists of lithium tantalate or lead selenide. 16. Flame detector according to one of claims 1-15, characterized in that the second photoelectric means (10) consists of lithium tantalate. 35 60 65