DE1298232B - Flame monitoring device for a burner - Google Patents

Description

wisely not for use with certain types of gas flames because the gas flame possibly not enough light to operate such a flame detector device testifies. Flame detector devices responding to ultrared radiation have the disadvantage that they can be affected by heat from the combustion chamber even if the flame is extinguished.

Once the fuel supply devices 10 have been set, the two detectors are simply connected in parallel, to the burner and the device for ignition and the subsequent relay circuit speaks to the This fuel is made ineffective until the sum of the output signals from the two detectors Flame monitoring device back on by hand, obviously already with the output signal is provided. a photocell for the normal operation of the

Such flame monitoring devices are sufficient. Such a one hold as a necessary component a double arrangement with two DeFlamme connected in parallel appealing detector device, the two detectors provides a safeguard against total for example, a visible failure of a detector emanating from the flame; a hedge against ultra-red or ultraviolet radiation. about the above-mentioned disturbance states as they are caused by Flame detector responsive to visible light- 20 change in the characteristic properties of the devices have the disadvantage that they are, for example, UV-sensitive detectors and related

The pretense of the presence of the burner flame is known with this However, facility also not achievable.

The invention thus relates to a flame monitoring device for a burner with two the same flame-responding radiation detectors that detect when radiation from the Flame produce an electrical signal, as well as with For these reasons, one to ultraviolet radiation 30 is one responsive to the sum of the signals An appealing flame detector device is preferable - a relay which, in the absence of a flame, causes the fire to break out. interruption of the fuel supply to the burner

Let flames respond to ultraviolet radiation.

Detector devices can over time. The present invention is intended to produce a flame characteristic Properties and parameters 35 menüberwachungseinrichtung are created at change in such a way that their mode of operation is prevented from deviating from the normal State differs and a potential gear mentioned type in the operation of the on the driving source represents. Such a detector pre-flame radiation responsive detectors from direction generally indicates a photoelectron normal condition becomes a hazard and emitting surface, which is in an envelope 40 in which it is ensured in particular that a Kurzbzw, a flask made of quartz glass is enclosed. End or a line break in any-die Abnormal operation is usually caused by a circuit element or a malfunction Any cracks or cracks in the device that occur in the envelope do not indicate the presence of the flame caused; through these cracks air can enter the pretend after the circuit is initially when enter wrapping; As a result, the 45 heating power required has been checked. Flame detector device behaves as if for this purpose a flame

Ultraviolet radiation will be seen on them, even if such a monitoring device of the type mentioned does is not the case. measured the invention by a second relay that on

There are already flame monitors - a difference between the two gen known, which addresses several photocells as Flam- 50 detectors supplied signals and one Have sensor detectors, but the individual interruption of the fuel supply causes so-photocells for monitoring different zones, this difference soon has a predetermined value of a furnace or different burner flames.

are seen. A safeguard against possible danger - By the second relay on a possible under-

the above-mentioned 55 differentiated between those by the normally the same Deviation of the photocells from their normal ar- photocell flowing currents can be fixed can result is to be provided with such excess if one of the photocells is abnormal specialist arrangements of detectors obviously does not work and, as soon as this occurs, the setting up can be achieved. practically immediately in one of the security

A flame monitoring device 60 is also to be brought into an effective (locking) state, known, in which the flame detector Ionisa- Das is based on the sum of the two photo-

tion tubes are used, which flow on from the cells in the presence of the flame Address the ultraviolet radiation emitted by the flame. This prevents the first relay from responding to currents Among other things, there is also an arrangement in front of the locking device in the normal operating state seen in which several such detectors 65 monitoring device, while the one parallel to each other in a monitoring circuit any predetermined difference between the lying, whereby for normal operation of the switching currents of the two photocells responding second tion is sufficient that at least one of the Detek relays the device in a locked state

can convict. In the monitoring device according to the invention the fuel supply to the burner is thus interrupted when the sum of the detector signals is below a predetermined value or when the difference between the detector signals exceeds a predetermined threshold value.

According to a preferred embodiment of the invention it is provided that the radiation detectors to monitor the flame, two normal

The establishment of the contact closure with the fixed contact 24 is a resetting of the contact arm 23 required by hand.

The first flame relay FR 1, the second flame relay FR 2, the first delay device FD and the second delay device SD are accommodated in a common housing FSD which has terminals LN for connection to a single-phase power source. The housing FSD is also

the same photocells are provided so that the io is also provided with a warning light 26, the radio first relay of which is described below in the de-energized state. Furthermore, the switch is closed in an excitation circuit
for the second relay, this Erre

supply circuit is closed when the flame

A transformer 11 for feeding the windings 3 and 7 is provided in the housing FSD.

The flame monitoring device comprises to be pre-ignited, and that the second relay 15 ner also has certain parts arranged outside the housing FSD, a switch which is open in the de-energized state, namely firstly a thermo which is closed when the mentioned
Excitation circuit is interrupted or if
the currents flowing through the photocells are reversed
differ from each other by an amount that exceeds the voltage spark between ignition electrodes by a specified value, the combustion chamber generating, thirdly photocells 8 and 10, closing the open switch, locking with a resistor 9 with a center tap, which causes the device. a probe head near the combustion chamber like this

In the following, embodiments of the Er- are arranged that the cells 8 and 10 of finding described on the basis of the drawing; into the ultrasers originating from the flame in the combustion chamber indicates exposure to violet radiation, as well as fourth one

staten T, the closing of which is an indication that heat is required, secondly an ignition transformer /, which in the fully excited state is high-

F i g. 1 is a partially schematic circuit diagram of a flame monitoring device according to a Embodiment of the invention,

F i g. 2 and 3 schematically two alternative embodiments a probe head assembly.

As shown in FIG. 1, the flame monitoring device essentially has a first flame relay Fi? 1, a second flame relay FR 2,

Motor or a valve M, which, when energized, causes the fuel to be supplied to the burner arranged in the combustion chamber.

The circuit connections between the elements listed above can be seen from the drawing.

When the thermostat T closes, indicating that heat is required, the flame passes through

a first thermal delay device FD 35 normally monitors for the following states as well as a second thermal delay device.

tungSD on. A pre-ignition period that begins with

The first flame relay FR 1 has a moving closing of the thermostat T begins and ends with borrowed contact arm 1, a fixed contact 2 and one of the actuation of the contact arms 17 and 19; in relay winding 3. The contact arm 1 closes 4 ° of this period, the following processes take place. normally with contact 2; by suitable a) An excitation circuit for the second flame

Menrelais FR 2 is closed as follows: From the terminal L via the contact arm 23, the contact 24, the thermostat T, the contact arm 1, the contact 2, the winding 6 and the terminal N. The contact arm 4 therefore closes with the fixed contact 5 .

b) An excitation circuit for the ignition transformer / is closed, namely as follows: From the terminal L via the contact arm 23, the contact 50 24, the thermostat T, the ignition transformer /, the contact 5, the contact arm 4 and the terminal N. The ignition transformer / is therefore fully excited in such a way that high-voltage sparks pass between the ignition electrodes, namely during such that these contact arms with corresponding 55 a sufficiently long time to the ignition electrical fixed contacts 18 and 20 in the warm state of the from any deposits to free. Close bimetal strip 13, but in the cold c) For the heating device 15 of the first delay

State of the bimetallic strip from the fixed contacts approximately device FD , an excitation circuit 18 and 20 will drop. from the terminal L via the contact arm 23,

The second delay device SD has a 60 the contact 24, the thermostat T and the heating bimetallic strips 21, which the heating device 15 is exposed to the terminal N closed by a heating device 22 and in sen.

There is an operative connection with a contact arm 23, which - d) For the heating device 16 of the first type of delay, that this in the cold state of the bimetallic disruption device FD and the heating device 22 of the window 21 with a fixed contact 24, in the warm condition of the 65 second delay device SD, which stood in series of the bimetallic strip 21 but are fixed to one another, the following excitation current contact 25 closes. To solve the contact of the circuit closed: From the connection terminal L via contact arm 23 to the fixed contact 25 under the contact arm 23, the contact 24, the thermal

When the winding 3 is energized, it is caused to fall off the contact 2. The conditions under where this occurs are described in more detail below.

The second flame relay FR 2 has a contact arm 4 which is normally open with respect to a fixed contact 5, furthermore a first winding 6 and a second winding 7 with a center tap.

The first delay device FD has a bimetallic strip 13 which is exposed to the heating by heating devices 15 and 16 and is in operative connection with contact arms 17 and 19,

5 6

staten T, the heating device 16, the heating device ("lock-out period") stops, the bimetallic

22, the contact 5 and the contact 4 to the strip 21 and brings the contact arm 23 to the

Terminal N. fall from the contact 24 and to close with

As a result of the series connection of the heating devices to the fixed contact 25.

16 and 22 passes through the heater 22 5 Play before the end of the locking period

The current does not flow to the contact arm 23 from the following processes:

to fall off contact 24 and to close j) When the fuel is ignited, UV-

ßung with the contact 25 to cause. The light from the flame on the photocells 8 and 10;

resulting slight warming of the bimetallic strip these allow normal, proper working

22 is sufficient, however, that the second delay mode 10 enough current to flow through the winding 3,

device can respond quickly as soon as that the contact arm 1 falls off the contact 2.

Heater 22 is fully energized, as below k) When the contact arm 1 falls from the

still described. Contact 2 is the pathogen mentioned above under a)

e) For the winding 7 of the second flame relay circuit for the second flame relay FR 2 interrupted FR 2 the following circuit is closed: Of the 15 broke. The contact arm 4 falls from the contact 5 connection terminal L via the contact arm 23, which causes the above-mentioned second ErKontakt 24, the thermostat T, the primary winding excitation circuit for the heating device 22 under -12 'of the transformer 11 to the terminal N; which is broken, with the result that the contact arm 23 induces excitation of the primary winding 12 α while in the closed position with the contact 24 remains. The one voltage in the secondary winding 12 b of the 20 motor and the valve M therefore remain erTransformators 11. The secondary winding 12 b is energized until the thermostat T opens.

in series with the winding 3 between the central 1) When the contact arm 4 falls from the taps on the winding 7 and on the resistance contact 5, the above under b) is also purchased 9. If the photocells 8 and 10 normal and imagined excitation circuit for the ignition transformer work properly, let them interrupt the Wir- 35 matorZ, with the result that the three effects of the heating devices 15, 16 and 22 induced in the secondary winding 12 b in series with the voltage through the same currents; this same ignition transformer / are switched. The ignition currents flow in the corresponding halves of the transformer is then no longer sufficiently excited, winding 7 and practice equal and opposite to generate ignition sparks. As a result of the processes directed forces on the contact arm 4, such as 30 j), k), 1) the fuel is ignited and the contact arm 4 remains in its closed position with contact 5 until the thermostat T opens. while the ignition transformer stops generating ignition sparks at the end of the period prior to ignition. This represents the normal occurrence of the following processes: Operating status of the flame monitoring device

f) As a result of the above under b) and c).

written excitation of heaters 15 and 16 at the end of the locking period play out

caused curvature of the bimetallic strip 13 are the following processes:

the contact arms 17 or 19 to close with m) If the flame does not ignite, no light falls

brought the fixed contacts 18 and 20, respectively. on the photocells 8 and 10, so that the through the

g) By closing the contact arms 17 or 40 winding 3 is not sufficient to the current flowing 19 with the fixed contacts 18 and 20, contact arm 1 will obviously fall off from the fixed contact 2 borrowed an excitation circuit for the motor or the leave.

Valve M closed, namely from the terminal n) The maintenance of the contact arm 1 in terminal L to the terminal N via the Kon-closed position with the fixed contact 2 causes clock arms 17 and 19 as well as the contacts 18 and 20. 45 as a result of the continued full excitation As a result of the excitation of the motor or the valve M of the heating device 22, the heating of the bimetal starts the fuel supply to the burner; Since the strip 21 causes the contact arm 23 to drop off at the same time as the ignition transformer / is already energized, the contact 24 and to close with the contact normally takes place after a short time delay, the ignition of the burner occurs. 50 o) When the contact arm 23 falls from the

h) When the contact arm 19 is closed with the contact 24, the ErKontakt 20 mentioned above under b), the heating device 16 is short-circuited excitation circuit for the ignition transformer / and sen. The sustained excitation of the heating device 15 of the excitation circuit mentioned above under g) is sufficient to interrupt the contact arms 17 or 19 in the closing motor or the valve M. The position with the contacts 18 and 20 to keep 55 burner is therefore switched off and can only after, although the excitation of the heating device 15 alone resetting the contact arm 23 by hand in its not enough to restore the contact arms 17 and 19 to their original position Gear are set, press. p) When closing the contact arm 23 with the

i) By closing the contact arm 19 with the fixed contact 25, an obvious excitation fixed contact 20 is closed, a second excitation circuit 60 is closed for the warning light 26, which therefore lights up for the heating device 22 to its now full and indicates that the device excitation is closed, as follows: From which is in a locked state and a terminal L via the contact arm 23, the manual reset is required before the contact 24, the thermostat T, the contact 20, operation can be resumed, the contact arm 19, the heater 22, the 65 effects of an imbalance between the currents passed from the contact 5 and the contact arm 4 to the connection to the photocells, for example clamping. If this full excitation of the heating element is due to cracks in the bulb of the photo direction 22 during what is called a "locking period":

a) Before the flame is ignited: Since only the faulty photocell lets current through, the current flowing through the winding 3 will not be sufficient to cause the contact arm 1 to drop off to bring the contact 2. The winding 6 is therefore excited in such a way that the contact arm 4 with the fixed contact 5 closes and heater 22 full at the end of the pre-ignition period is energized, such that the device is in the locking state at the end of the locking period got.

b) After the flame has been ignited: The winding is before the unbalanced state occurs 3 energized, so that the contact arm 1 falls from the contact 2 and the contact arm 4 of the Contact 5 is released. As soon as the unbalanced state develops, those in the two become Halves of the winding 7 flowing currents sufficiently unequal, such that the contact arm 4 to Closure with the fixed contact 5 comes and the ao flame monitoring device so in their Locking state is set.

F i g. 2 illustrates one embodiment of a Probe head; this has a housing 27 in which two separate photocells 28 are arranged in this way »5 are that they receive light from the flame 29 through a tubular part 30 of the housing. Of the tubular part is cylindrical and can have a lens 31 to direct the rays onto the photocells to judge.

F i g. 3 shows an alternative embodiment in which the tubular part 30 has a conical shape and the ratio of the radiation incident on the two photocells by rotating one for the radiation coming from the flame permeable prism 32 is adjustable.

In the description above, the two flame relays are described as electromechanical relays. Of course, they can alternatively also include solid-state switching elements Transistors are replaced.

Claims (3)

Patent claims: 1. Flame monitoring device for a burner with two responding to the same flame Radiation detectors that generate an electrical signal when radiation from the flame hits Generate a signal, thus with a relay responding to the sum of the signals, which is in The absence of the flame causes the fuel supply to the burner to be interrupted, characterized by a second relay (Fi? 2) pointing to a difference between the two detectors (8,10) Signals responds and causes an interruption of the fuel supply as soon as this difference exceeds a predetermined value. 2. Flame monitoring device according to claim 1, characterized in that two normally identical photocells (8, 10) are provided as radiation detectors for monitoring the flame, that the first relay (FR 1) has a closed switch (1, 2) in a de-energized state Excitation circuit (L, 23, 24, T, 1, 2, 6, N) for the second relay, this excitation circuit is closed when the flame is to be ignited, and that the second relay (FR 2) is in the de-energized state open switch (4, 5) which is closed when the mentioned excitation circuit is interrupted or when the currents flowing through the photocells (8,10) differ from each other by an amount that exceeds the mentioned predetermined value, the closing of the open switch (4,5) causes a locking of the device. 3. Flame monitoring device according to one of the preceding claims, characterized in that the relays (FR 1, FR 2) are electromechanical relays. 1 sheet of drawings 909 526/119