DE1952551A1 - Electric ignition assembly - Google Patents

Description

Our reference: P 2036

THE PLESSEY COMPANY LIMITED

2/60 Vicarage Lane, Ilford, - Essex, UK

Electric ignition arrangement

The invention relates to an electrical ignition assembly and in particular to an electrical ignition arrangement to be fed from the alternating current network, which is suitable as a gas igniter in gas stoves.

According to the invention, the electrical ignition arrangement to be fed for igniting gas and from deoi alternating current network designed in such a way that a first capacitor, which is charged via a second capacitor, has no loss Load forms that, in parallel with the first capacitor, the primary winding of a voltage transforming device and there is a switching element connected in series therewith, and that the switching element is arranged in such a way that that it can then be triggered to achieve the discharge of the first capacitor via the primary winding when the voltage across the first capacitor in a half-wave or full-wave system is essentially its peak value reached, so that at spark electrodes one of the voltage transformers in the secondary winding Device induced high output voltage of derived sparks is generated.

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Switching element preferably consists of a so-called triac, which can be triggered _{by an I m pulse generating circuit as a result of the actuation of an ignition switch arrangement.}

The pulse generation circuit can be used as a differentiating circuit be carried out, are applied to the triangular voltage pulses, which in a suitable manner by a Zener diode switched on in the capacitor charging circuit can be derived. The pulse generation circuit can on the other hand also simply consist of a saturable choke coil to which the impulses are applied the control electrode of the triac is generated via a resistor when the ignition switch arrangement mentioned above is operated.

Of course, controllable silicon crystal rectifiers can also be used for the triac or other triggerable switching elements can be used.

The above-mentioned switching element of the ignition arrangement can be switched on in such a way that it is dependent on can be triggered by the breakdown of a trigger diode (DIAC), which is connected between a Impedance circuit and the switching element inserted is. To determine the breakdown point of the trigger diode, it can be connected to the connection point of a voltage divider be connected to the impedance circuit, which in turn is connected to the connection point of two capacitors.

The capacitor charging circuit can be parallel to the network; there can also be an isolating transformer in between

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be arranged.

When the ignition arrangement according to the invention is used on gas cookers, several pairs of radio oil electrodes can be used are provided, each of which with the exception of a further pair of electrodes, which is close to the usual Oven burner is arranged, is effectively assigned to one of the usual gas ring burners. These point electrode pairs can be connected in parallel to the associated secondary windings of individual transformers, whose primary windings are connected in series in the capacitor discharge circuit. The primary winding of the transformer for the oven burner point electrodes can be activated by actuating a Oven ignition switch switched on in the condenser circuit or be separated from him. This is the way to operate the oven spark electrodes the ignition switch assembly and the oven ignition switch at the same time be operated.

In a further embodiment of the invention takes place the control of the triggering of the switching element of the ignition arrangement in that the switching element is supplied Tripping pulses normally applied across the primary winding of a transformer to the neutral of the network the secondary winding of the transformer is short-circuited by a control switch. If the If the arrangement is to ignite, the control switch is opened and the trigger pulses are sent to the switching element and put this into operation. The trigger pulses can be derived from a trigger diode, as described above is. To prevent the operation of one or more pairs of spark electrodes until the switch is actuated,

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an additional control switch can be provided.

Embodiments of the invention are shown in the drawing.

1 shows the circuit diagram of an electrical ignition arrangement according to the invention,

Fig. 2 shows another embodiment of an ignition arrangement according to the invention,

Pig. 3 an ignition arrangement suitable for use in gas stoves,

Fig. 4 is a circuit diagram of a similar ignition arrangement as in Figure 1 with another embodiment of the triggering and switching device and

5 shows a circuit diagram of an electrical ignition arrangement with a trip control circuit for the switching device.

The ignition arrangement shown in Figure 1 of the drawing contains a connected to the mains power supply MS iCiOndensa ^ sPrladeiSCihaltung, This jKonde, nsatorla.deschalljung ipeetehit; from the ßeriensCjhaiL & ung .eines iLonden- aatovs β ftf the over, he one a yerlusi; free L.as; t formeiiden iiadeikondensalpr fG _G aiüf ^ geiLadein ^ earth sojLl ^ a low resistance JR ^ which the discharge of the probe yerihnd _ß yerihnd ^ j iyenn sicih 4ev

eF? eneEf |. |? 4e Z _f & Le in äß® in the gpndensalorlaidioiSiC ^ l ^ ung

.m a rear corner voltage generated

9B3

In parallel with capacitor C, is a discharge circuit connected to the primary winding P of an up-transforming pulse transformer T and there is a triac TR in series with it.

The pulse transformer T has a secondary winding S, to which two radio electrodes S are connected.

To the control electrode of the triac TR is a capacitor C ~ and a capacitor connected in series Current limiting resistor Rp existing voltage differential circuit connected to which the square-wave Zener voltage is applied when the ignition switch I is actuated

If the ignition switch I is not operated, then is the voltage O applied to the voltage differential circuit and the trigger circuit of the triac TR therefore does not generate any impulses. Under these conditions, the triac remains unfired and the capacitor charging circuit takes only a small, effectively lossless capacitor from the network thanks to the lossless capacitor C Current.

If you look at the arrangement in operation with the ignition switch activated, you can see that the voltage applied to the differentiating circuit changes between the value 0 and a constant voltage (for example 24 volts), i.e. the voltage that occurs at the Zener diode Z, when there? Capacitor charging current reversed from one polarity to the other. The changes in the input voltage of the differential circuit generate trigger pulses which, because of the 90 ° phase shift between the capacitor charging current and the capacitor charging voltage, occur when the voltage across the capacitor C, has a maximum value.

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In this way the triac TR ignites at the apex every half cycle of the voltage across the capacitor C ^, thus This capacitor is via the primary winding: P des Transformer T discharges and thus a spark between the electrodes S to ignite gas, for example generated. The resistance R ^ limits the discharge of the capacitor C ^ the discharge current of the capacitor G, while the resistor R2 that of the control electrode of the Triacs supplied pulse current to a safe value limited.

W In another embodiment shown in Figure 2 of the drawing. the Zener diode of Pig.1 is replaced by a saturable choke coil CH1, which generates voltage pulses in the diull passages of the current in the charging circuit. These pulses are applied to the triac TR so that it is ignited when the capacitor voltage reaches its peak value following the actuation of the ignition switch 1. The pulse current is limited by the resistor R, in the triac control circuit.

Described in both in connection with Fig.1 and Iig.2 The pulse ignition of the triac depends on the ignition arrangement significant changes in the input line voltage off, and also has the maximum voltage on the ignition switch a safe low value (for example, 24 volts).

In Fig. 3 an electric gas igniter is shown, which is suitable for use in gas stoves.

In this particular embodiment, the mains voltage MS disconnected before application to the capacitor charging circuit with the help of a transformer TX. This can

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the switching operation can be carried out at a voltage value that is low in relation to ground. The discharge circuit used here for the capacitor C contains the series-connected primary windings P ₁ to P ₁ - of the transformers T ₁ to T ₁ -, pairs of spark electrodes SP ₁ to SP are connected to the secondary windings S ₁ to S _{c of these transformers.} connected, which are attached to the respective digester rings adjacent. The discharge circuit also contains the primary winding P ^ of a further transformer Tg, to whose secondary winding Sg two spark electrodes SPg are connected, which are attached to the usual oven burner. The primary winding Pg can einge- 0 _v in the discharge circuit by means of a 3ackrohrzündschalters. switched or separated from it, so that the two switches I and 0 are actuated at the same time

g ν

must be when the BaGk pipe is to be ignited. It should also be noted here that the voltage on the oven ignition switch is low for security reasons.

From Figure 4 of the drawing it can be seen that two capacitors G _G and C-. are connected in series with a resistor R ₁ to the power supply Vβ . A controllable silicon rectifier (triac) TR operating as a full-wave rectifier and the primary winding P of a transformer T whose secondary winding S is connected to the Funtaen-SP are parallel to the capacitor C.

To? Generation of Auslffpei: mpuJLs # ® && ® tIgnition of the triac TE is generally this version of the; control electrode of the triac for and the failure point of a voltage from the parallel zjj äe® | £ onde.nsat _; oren Q and G,

C u

0AD ORIGINAL

switched resistors R ₁₀ and R ₁ * a trigger diode TD switched on. To the resistors R ₁₀ and

R ₁₁ are capacitors C and G in parallel, it eg

In the operating state of the trigger circuit, the trigger diode TD breaks through at a precisely defined voltage value, and the breakdown point _u can by a suitable A swahl of the resistors R ₁₀ and R ₁₁ at each required value within the N _e tzperiöde be adjusted. This value is placed sufficiently below the mains peak voltage so that continuous ignition of the triac TR at the expected lowest mains voltage peak value is ensured.

It should be noted that the ignition of the rectifier TR always occurs at a predetermined voltage within the Mains period and therefore always at a point of constant energy with respect to that required by the capacitor C ^ Charging takes place.

The capacitor C connected in parallel with the resistor R ₁ Q is used to generate a pulse at the breakdown point of the trigger diode TD, which pulse forms the trigger pulse for igniting the triac TR. The other, parallel to the

Capacitor C lying resistor R ₁₁ prevents a g τι

unintentional ignition of the triac TR when the trigger diode TD "returns to the lit state.

The equation CR ₁₁ = CR ₁₀ results in the critical value for the capacitor C, which brings the trigger pulse voltage back into phase with the mains voltage. For safety reasons, the value of the capacitor G should be one and a half times as large so that tolerances of the components are permitted.

0098 3 1/0917
ßAD ORIGINAL

As can be seen, the triac TR receives the triggering impulses via two impulse _{formers PT 1} and PTp, which result in a mains disconnection, but are relatively cheap and small compared to a mains transformer. The trigger circuit of the triac TR is set powered by closing the contact SW1 in B _e. Such a closing contact effect is necessary in many applications.

Finally, FIG. 3 ig.5 of the drawing shows a release control arrangement shown, which forms a further, suitable for such Palls arrangement in which a Power disconnection of the trigger control switch is required. The components corresponding to the arrangement of Pig.4 Components have the same reference symbols.

As can be seen from Fig.5, there are also full-wave rectifiers working, controllable silicon rectifier TR the primary windings Pp, P- * and P. the transforming up Transformers T «, T, and T. connected in series. To the secondary windings, such as the secondary winding S ^ each of these transformers are radio electrodes, like the electrodes SP ,, connected. The trigger diode circuit can be used to derive a trigger pulse to ignite the triac TR can be used by Pig.4.

Regardless of how they are derived, the trigger pulses are suitable for being switched through to the control electrode of the triac TR under the control of a pulse transformer T. If the secondary winding S _{1 of the} transformer T ₁ is short-circuited by closing the switch TS as shown in the illustration, the trigger pulses are passed through the primary winding P _{1 of} the transformer to the neutral conductor N of the mains supply MS. If the

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Switch TS is open,. The trigger pulses are on placed the triac TR. In this way, the release control switch TS is disconnected from the network, and he can according to the representation to be connected to ground. The secondary windings Sp, 'S-, and S- can according to the illustration be connected directly to ground.

The transformer T ₂ also has a grounded third winding TEp, to which a short-circuit switch TX is connected in parallel. When the switch TX is closed as shown in the illustration, the transformer Tp is blocked, and no sparks are generated at its associated spark electrodes SPp when the triac TR is conductive, while sparks are generated at the electrodes connected to the transformers T and T. The arrangement can, for example, be such that the spark electrodes SP 1 and SP are assigned to the ring burners of a gas cooker, while electrodes SP _{2 are} provided for the oven burner, which must be blocked except when the oven is ignited.

It can be seen that the shown in Fig.4 and Fig.5. presented trip control arrangement the use of a "mains isolating transformer with the associated losses and heating is avoided, and that considerable savings in the size and cost of the arrangement be achieved. Has the arrangement shown in Figure 5 however, despite the possibility of saving a transformer, does not have the normally open contact feature of the ignition switch, and it can sometimes change because of the Change in sensitivity of the triac in cases where large temperature fluctuations are to be expected, prove to be critical.

Pit e nt claims

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Claims (1)

Claims Electrical ignition arrangement to be fed from the AC network for igniting gas, characterized in that a first capacitor, which is charged via a second capacitor, forms a vsclust-free load, that parallel to the first capacitor, the primary winding of a voltage-transforming device and a switching element connected in series and that the switching element is arranged in such a way that, in order to achieve the discharge of the first capacitor via the primary winding, it can then be triggered when the voltage on the first capacitor essentially reaches its peak value in a half-path or full-path system, so that at spark electrodes a the high output voltage induced in the secondary winding of the voltage-transforming device derived 3? _u is generated Potions. 2. Electrical ignition arrangement according to claim 1, characterized in that the switching element consists of a triac exists, which can be triggered via a pulse generation circuit. 3. Electrical ignition arrangement according to claim 2, characterized in that the pulse generation circuit is put into operation by actuation of an ignition switch arrangement for generating pulses. 4. Electrical ignition arrangement according to claim 2 or 5, characterized in that the pulse generating circuit consists of a differentiating circuit, to which square-wave voltage pulses are applied. 0 0 9 8 3 1/0917 3 * Electrical ignition arrangement according to claim 4, characterized in that the square-wave voltage pulses are derived from a Zener diode connected to the capacitor charging circuit. 6. Electrical ignition arrangement according to claim 2 or 3, characterized in that the pulse generation circuit consists of a saturable choke coil, the pulses for application to the control electrode of the triac when the ignition switch arrangement is actuated generated via a resistor. 7. Electrical ignition arrangement according to claim 1 or 2, characterized in that the switching element depending on the breakdown of a trigger diode can be triggered between an impedance circuit connected in parallel to the mains and the ignition switch arrangement is inserted. 8. Electrical ignition arrangement according to claim 7, characterized marked that the trigger diode laying down the breakdown point is connected to the common point of a voltage divider of the impedance circuit, which is connected to the common connection point between two capacitors. 9. Electrical ignition arrangement according to claim 1, characterized characterized in that an isolating transformer is inserted between the capacitor charging circuit and the network is. 10. Electrical ignition arrangement according to claim 1, characterized in that several pairs of point electrodes It is provided that each pair of spark electrodes, with the exception of a further pair, is one of the usual 009831/0917 The gas ring burner of the gas cooker is assigned that the other pair of electrodes is the burner of the oven is assigned, and that the spark electrode pairs in parallel to the secondary windings of each, the Voltage-transforming device forming transformers are connected, their primary windings are in series in the capacitor discharge circuit. 11. Electrical ignition arrangement according to claim 10, characterized in that a primary winding is one of the Transformer, which is assigned to the oven burner, is switched on so that it is activated by the operation an oven ignition switch arrangement in the capacitor discharge circuit or disconnected from it can. 12. Electrical ignition arrangement according to one of claims 1 and 10, characterized in that the triggering of the switching element is controlled in that the triggering pulses supplied to the switching element are normally via the primary winding of a pulse transformer, the secondary winding of which is short-circuited by a control switch, to the neutral conductor of the network are performed, wherein the circuit arrangement is made such that the control switch opens the circuit of the secondary winding when the A _n order is to ignite, whereupon the trigger pulses reach the switching element and trigger its operation. 13. Electrical ignition arrangement according to claim 12, characterized in that an additional control switch is provided which prevents the operation of a selected pair of spark electrodes until the control switch is actuated. 009831/0917 14.Electric ignition arrangement according to claim. 13, thereby characterized in that the additional control switch is inserted such that it has a third winding a control transformer whose primary winding is switched into the capacitor discharge circuit and oven point electrodes on its secondary winding connected in parallel, and that the additional control switch and the first mentioned control switch to ground and through that Pulse and control transformers are separated from the mains so that the switches are extremely safe. 009831/0917