DE1965790A1 - Burner control - Google Patents

Description

Pall 1527 May 30, 1969

LANDIS & GYR AG, ZUG (Switzerland)

Burner control

The invention relates to an automatic furnace for a furnace, with a flame monitor and a switching device, which successively an ignition device and a fuel release element and in the event of a malfunction turns on a shock switch.

As is well known, the task of an automatic firing system is to bring the organs belonging to the firing system close to one. to switch on a certain schedule and to monitor the combustion process operationally. The switching mues

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device on the one hand the pre-ignition or pre-ventilation time and on the other hand the safety time between the fuel release and the fault shutdown of the system if the Measure the flame as precisely as possible.

A known switching device consists of a cam scarf twerk with a plurality of mechanically moving parts, the wear -which are subjected ER and the demands on the Seibetüberwachung not satisfactorily fill mass W. Another disadvantage of such cam switches is the great expense.

Other known switching devices have thermal timing elements connected in series to determine the pre-ignition time and the safety time. Furthermore, automatic firing systems have become known in which a single thermal drive element actuates various switches one after the other. Such facilities have worked well in practice proven, but are relatively complex and require precise, time-consuming adjustment.

The invention is based on the object of creating an automatic firing system which has minimal technical requirements Outlay and still meet the high requirements for operational safety and self-monitoring.

The solution to this problem is, according to the invention, that the fuel release device and the push switch are controlled by a single member, <1 ···· η time function each-

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while the burner release device is switched off or at unresponsive flame detector expires, and that the Störachalter is controlled so that when the Timers only when the fuel release device is switched on or can assume the fault position when the flame monitor has been addressed.

The following is an embodiment of the invention explained in more detail with reference to the drawings. Show it:

Fig. 1 is a basic circuit diagram and Fig. 2 shows a relay arrangement.

In Fig. 1, the basic circuit diagram of an automatic furnace is shown, which consists of a feed part 1, a flame monitor 2, a timing element designed as a pulse generator 3, a torch switch 4 and a switching part 5 consists.

The feed part t contains a bridge rectifier 6, which is connected to the Lulleiter 8 of the feeding network via an impedance element 7 consisting of a resistor and a capacitor and is connected to a line 9. At the output of the bridge rectifier 6 are a Zener diode 10 and a Capacitor 11 for stabilizing and smoothing the rectified supply voltage. This tension passes over Feeding point 12, 13 below the electronic circuit parts 2, 3 and 4

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The feed part 1 can be omitted if the feed points 12, to the feed section of a low voltage device of the combustion system be connected.

The flame monitor 2 consists of a photo resistor 14 » an electronic flip-flop 15 and a flame relay F. The flip-flop 15 is used in the present example one of transistors 16, 17 »a common Eraitterwiderstarid 18, coupling resistors 19 »20 and a collector resistor 21 built-up Schmitt trigger. The excitation winding of the flame relay F is in the collector circuit of the transistor 17. The photoresistor 14 forms together with one Resistor 22 has a variable voltage divider and is connected to the base circuit of transistor 16. If there is a post-ignition period If desired, the flame monitor 2 can also be equipped with a response delay.

The pulse generator 3 is formed by a relaxation oscillator with a double base diode 23, the base Bg of which is connected to the W feed point 12 and the base B ₁ , which forms the output of the pulse generator 3, is connected to the feed point 13 via an excitation winding 24 of a trip relay A. The emitter E of the double base diode 23 is connected to a time-determining RC element 25, 26.

Da · Auelöeerelaie A has a secondary winding 27, which connected to the control electrode of a controllable rectifier 28 belonging to the torch switch 4 and so ge

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Polt is that the controllable rectifier 28 only when a pulse supplied by the pulse generator 3 disappears is ignited. A burner relay B is connected to the anode circuit of the controllable rectifier 28.

The switching part 5 includes a trip contact a of the trip relay A, which has a conductor 29 of the feeding network a thermostat switch 30 connects to line 9. The switching part 5 also consists of a break contact f of the flame relay P and from a normally open contact b of the burner relay B. The normally closed contact f is in the circuit of an ignition device 31 and the normally open contact b switched to that of a fuel release element 32.

The RC element 251 26 of the pulse generator 3 is via a diode connected to the anode of the controllable rectifier 28 and via a diode 34 to the collector of the transistor 17, is therefore only when the rectifier 28 is not ignited, i.e. when the fuel release element 32 is switched off, or when it is not addressed flame monitor 2 is connected to voltage. The time function of the timing element formed by the pulse generator 3 consequently runs only when the flame monitor 2 is not addressed or when the fuel release element 32 is switched off.

FIG. 2 shows a diagram of the arrangement of the relays A, B and F. The release relay A is between the flame relay F. and the burner relay B and has in its rest position a very large air gap and thus also one

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high magnetic resistance. The armature 35 of the flame relay F and the armature 36 of the burner relay B are over each a driver bracket 37 or 38 in such a way with the armature 39 of the Trigger relay A coupled that it is pressed into a preparatory position when the flame relay F or the burner relay B responds, and the armature air gap accordingly is reduced. It is thereby achieved in a simple manner that the release relay A when the timing element 3 can only assume the fault position if one of the two neighboring relays F or B is already energized, i.e. if the fuel release element 32 is switched on or the Flame monitor 2 has responded.

The trip relay A locks itself after responding

only

automatically and can / can be reset manually by a reset button not shown in the drawing.

The burner control described works as follows; When the switch 30 is closed, the commissioning process of the combustion system is initiated. The circuit parts 1 to 4 and the ignition device 31 are thereby switched on Tension laid. Relays A and B are initially not energized. The relay F is temporarily not picked up because the photoresistor 14 has a high resistance without exposure. The diodes 33 and 34 are polarized in the forward direction, so that the capacitor 26 is charged through the resistor 25 for a long time. Relays B and F cannot pick up because the resistor 25 has a very high resistance to its field windings. If after a predetermined time that

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corresponds to the pre-ignition time, the voltage across capacitor 26 reaches the breakover voltage of the double base diode 23, toggles this into the conductive state and the capacitor 26 discharges via the excitation winding 24 of the trip relay A. However, this cannot attract because its armature air gap is still very large. In the secondary winding 28 is a Voltage induced, which the controllable rectifier 28. ignites when the discharge pulse disappears. The burner relay B picks up, whereby on the one hand the fuel release element 32 is switched on and on the other hand the armature 39 of the Trip relay A is pressed into the preparation position with a correspondingly smaller armature air gap.

The diode 33 is now blocked. However, the diode 34 is still polarized in the forward direction, so that the capacitor 26 is charged again. If the burner starts well, however, a flame is created before the voltage is applied to the capacitor 26 the breakover voltage of the double base diode 23 is reached again, the flame monitor 2 responds, the diode 34 is blocked and the charging process of the capacitor 26 is aborted. This completes the commissioning process for the combustion system.

If the flame goes out during operation, the flame relay F drops out, the ignition device 31 is switched on again and the capacitor 26 is charged again. if If no flame forms before the end of the charging time, which this time corresponds to the safety time, the timer speaks 3 and delivers to the excitation winding 24 of the Aualösere-

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lais A an impulse. The trigger relay A attracts because its Anchor 39 has been pressed into the preparation position by the burner relay B before the timer 3 has responded was. This means that the firing system is switched off .

Another important malfunction is the erroneous response of the flame monitor 2 at the start of the commissioning process due to extraneous light or a defect in the ψ flame monitor. In this case, the diode 34 is blocked in the pre-ignition phase, but this has no further effect because the capacitor 26 can draw its charging current via the diode 33. After the pre-ignition time has ended, the timer 3 responds and delivers a pulse to the excitation winding 24. The trigger relay A now picks up immediately because its armature 39 had already assumed the preparatory position before this pulse from the flame relay F occurred.

The burner control according to the invention is characterized by the utmost simplicity and also meets the requirements for operational safety and self-monitoring to a high degree, because the timer 3 has to prove its functionality in the pre-ignition phase before it is able to do its job during the safety time to fulfill extremely important monitoring task. In the embodiment described here, for example, the ignition pulse at the control electrode of the controllable rectifier 28 is absent in all conceivable error possibilities of the timing element 3, so that a burner start is prevented.

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The idea of the invention disclosed here can of course not only be applied to a firing machine data with an electronic one Timing element, but also used, for example, in burner controls with a mechanical timing element will. Likewise, the condition placed on the fault switch can be that when the timer responds only when it is switched on Fuel release device or when the flame monitor is addressed may assume the fault position, except for described manner can also be met in other ways, for example by an electrical lock. Further the pre-ignition time and the safety time can be selected to be different "if the time constant of the timer is controlled depending on the switching state of the fuel release device.

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Claims (1)

1965730 - 10 - 1527 Landia ft Gyr AG. PATENT CLAIMS Automatic firing system for a firing system, with a flame monitor and a switching device, which sequentially activates an ignition device and a fuel release. organ and, in the event of a malfunction, switches on a fault switch, characterized in that the fuel release organ (32) and the fault switch (A) are controlled by a single timer (3) whose time function is switched off Fuel release device (32) or if not addressed Flame monitor (2) expires, and that the fault switch (A) is controlled in such a way that when the timer (3) responds it only when the fuel release device (32) is switched on or when the flame monitor (2) is activated, assume the disturbance division can. 2. Firing automat naoh claim 1, characterized in that that the time constant of the timing element (3) as a function of ./. 009887/1238 _GQpy - 11 - 1527 controlled by the switching state of the fuel release organ (32) is. 3. Automatic burner control according to claim 1, characterized in that that the flame monitor (2) has a flame relay (F), that in the circuit of the fuel release element (32) Contact (b) of a burner relay (B) switched and the fault switch (A) is formed by a trip relay, and that also the armature (35-36) of the flame relay (F) and the burner relay (B) with the armature (39) of the trip relay (A) are coupled that its armature air gap when responding of the flame relay F or the burner relay B is reduced. 4. Automatic burner control according to claim 1 or 3 t characterized by τ · shows that the timing element (3) is an electronic pulse generator whose co-determining circuit element (25t 26) when the fuel release element (32) is switched off or when it is not addressed flame monitor (2) is connected to voltage. 5. Automatic burner control according to claim 4, characterized in that the electronic pulse generator (3) is a double base diode (23) containing relaxation oscillator 1st. 6. Burner control according to claim 4, characterized in that the excitation winding (24) of the release relay «(A) is immediate 009887/1233 - 12 - 1527 bar In dtn output of the electronic pulse generator β (3) total is tet. 7 * automatic burner control according to claim 3 »characterized that the excitation winding of the burner relay (B) in the anode circuit of a controllable rectifier (28) and its control electrode to a secondary winding (27) of the trip relay (A) is switched. 8 · Automatic burner control according to claim 1, characterized in that » that the flame monitor (2) has an electronic toggle switch (15). 9. Automatic burner control according to claims 4, 7, 8 »characterized in that the electronic circuit parts (2) 3; 4) of the automatic firing unit are fed by the feed part of a low-voltage device of the firing system. HV / hf LAVDIS & GTR Au Patent department 009887/1238 Blank page