GB2202926A - Control circuit - Google Patents

Description

1 1 A CONTROL CIRCUIT FOR AN ELECTRICAL IGNITION-ENERGY STORE 220292C The

-invention relates to a control circuit for an electrical 5 ignitionenergy store.

Such a circuit is known, for instance, from DE-OS 33 17 376, where the charging of the capacitive ignition store of each of several existing ignition circuits is effected by means of a wind-wheel 10 generator during the free flight of a munition dropped from a carrier. The ignition circuits for pyrotechnically triggered auxiliary functions are initiated from a programme control circuit, whilst the ignition circuit for the combat charge is controlled by a voltage source being switched through, by way of an impact contact, to an 15 ignition-circuit switching member.

With a munition of a different kind, a simple impact contact does not serve as sensor for triggering the ignition signal, but rather a logic gate combination (processing) of the analysed output signals of various sensors is provided, in order to provide only a targetspecific initiation of the combat charge; see, for instance, the combination of magnetic and optronic sensors in accordance with DE OS 3 33 15 1086 or the evaluation and comb in-at i on (processing) of sensor information, obtained in different spectral regions of the electromagnetic radiation, in accordance with DE-OS 33 23 519.

Since, for constructional or. functional reasons, frequently the sensor evaluation or sensor arrangement for obtaining an ignition signal cannot be effected in the immediate spatial vicinity of the 30 actual ignition circuit, the control of the ignition switching member t in the case of modern munition is very frequently effected over relatively long ignition lines. Such a long run of wires acts, as is well known, as an antenna for internally generated or externally irradiated electromagnetic fields, which can thus 'Lead to interference

2 or stray information on the ignition line and thus, in use, despite the considerable expenditure on sensor-signal processing, finally to faulty ignitions.

In recognition of these factors, an aim of the present invention is to design a control circuit such that it may be more free from interference and in this way, for example with modern seeker-fuze munition, the increase in performance obtained "per se" through the sensor-signal processing may not then be nullified again by stray interference functions.

According to the present invention there is provided a control circuit for the discharging circuit of an electrical ignition-energy store, or method of controlling said discharging circuit, characterised in that during the existence of an ignition signal with a predetermined gate timespan control pulses supplied by an asynchronously-working oscillator are counted, and only when a predetermined counting result is reached is a counter-state signal issued for the switching through or activation of the discharge circuit.

In accordance with this solution, as a result of simple additional circuit measures, during the ignition-signal control of the ignition- circuit switching member, it is apparently ensured that only an ignition signal actually occurring over a specific space of time and only during the appearance of freely (thus asynchronously generated) control pulses will lead to the control of the ignitioncircuit switching member and thus to initiation of the combat charge. On the other hand, as a result of the still not controlled (inactive) ignition circuit, the munition remains ready to function if the ignition signal is (still) not present over the minimum space of time, predetermined by the circuitry, during the occurrence of the control pulses - not correlated with the appearance of the ignition signal.

Thus, disturbances on the long ignition line leading to the control circuit (in contrast to the conditions upon the existence of an ignition signal) do not lead within the predetermined space of time t 3 to the predetermined number of control pulses that are to be added up by means of a counter, and therefore, do not lead to (premature) triggering of the ignition circuit. Only when the ignition signal is maintained within the predetermined space of time and a predetermined number of- control pulses is counted up is the ignition circuit controlled for the initiation of the combat charge. The forced gatetime delay between start of the ignition signal and control of the ignition means can, since it is system-dictated, be compensated for functionally, for example in the lead of the ignition sensors relative to the effective system or, with the sensor signal arrangement, in the ignition logic. Moreover, with most types of munition with which we are concerned, an ignition-signal delay in the order of magnitude up to 100 microseconds is functionally unobjectionable; a compensation allowance (Vorhalt) would be superfluous when the gate-time delay lies within such a non-critical time interval.

An increase arises in the operating reliability in the control of the ignition circuit by way of the control circuit, if operations are carried out within the seemingly shortest possible control or counting pulses from the oscillator, because, then the probability of coincidence of a sequence of interference impulses with counting impulses becomes all the more improbable. Only upon extremely high interference density on the ignition line would a malfunction have to be feared, because, then the probability becomes greater that also some of the interference impulses may coincide temporally with the sequence of the short control pulses.

This additional control circuit can be built up very compactly and thus can also be arranged in the spatial vicinity of the ignition circuit, so that no long lines, sensitive to inductive interference.

are any longer necessary between the control circuit and ignition circuit.

It is advantageous to utilise the charging voltage for the ignition stores (which voltage is generated, for example, upon launching the munition and transferred upon discharging the munition from the carrier on-board power supply or for.safety is built up only 4 during the delivery of the munition by means of a wind-wheel generator) in the sense of a pre-activation as release signal, in order only then to put the control circuit into operational readiness for checking of the ignition signal following soon thereafter.

A free-running oscillator for the non-synchronised supply of the control counting impulses can at the same time be utilised for triggering a selfdestruction of the munition, if, after a predetermined waiting time from appearance of the release signal or ignition signal, no initiation of the combat charge is effected. Thus a live munition is prevented from remaining as a "dud" and unauthorised persons would be prevented from analysing the sensor algorithms for obtaining the ignition signal in a functional munition.

Additional alternatives and further developments as well as further -features and advantages of the present invention will become apparent from the claims and from the following description of an embodiment in accordance with the present invention, which is shown as a single-pole block wiring diagram in the drawings, and which will now be described, by way of example only with reference to the much simplified drawings, in which:

FIGURE 1 shows schematically the operational elements of a control circuit in accordance with the invention; and FIGURE 2 shows a logic time diagram.

Referring to the drawings, the depicted control circuit 11 for the discharging circuit 12 of an ignition store 13 has a gate time transmitter 14 which, after pre-activation by a release signal 1 5, is activated by way of an AND logic circuit,16 by an ignition signal 17, and thus supplies a data signal 18 arising over the gate space of time tT. With the appearance of the gate signal 18 at the reset input 19 of a counter, the compulsory zero setting thereof is cancelled, and the counter adds up the control or counting pulses 21 now running in, which are triggered by an oscillator 22.

To clarify or determine the temporal limitation of this counting function to the gate space of time tT, in the block wiring diagram of FIGURE 1, connected prior to the counting input 23, is an AND-gate 24 which is prepared by the gate signal 18 and is switched through periodically from the oscillator 22.

With the running of the counting pulses 21 into the counter 20 there appears in succession at the counter outputs 25 a counter-state signal 26. However, only one of the outputs 25 is conducted by way of the circuit output 27 to the electronic switching member 28 of an ignition circuit 29. Only if, and when, upon occurrence of the ignition signal 17 within the triggered gate space of time tT, a predetermined number of counting pulses 21 has occurred does the interrogated counter- state signal 26 thus appear for switching through on activation of the switching member 28, and thus for the discharge of the electrical ignition store 33 by way of its ignition means 30 (for instance a bridge detonator) for the initiation of the combat charge 31 of a munition.

Since, for reasons of functional reliability or safety against interference impulses 44 occurring in an uncorrelated manner and scattered or strewn inductively onto the ignition line, the counting input 23 of the counter 20 is to be controlled with the seemingly shortest possible needle-shaped counting impulses 21, whilst on the other hand a customary oscillator 22 as a rule supplies an output impulse sequence with the keying ratio of 1:1; in the block wiring diagram of Fig. 1 provision is made for connecting subsequent to the oscillator 22 an impulse converter. 32 for shortening the high impulse times. The convertor 32 may be a monostable trigger stage or flip flop 33 which is set in each case by the output impulse 34 and, after an extremely short time flips back again into its monostable functioning position, and thus replies to each oscillator output impulse 34 with an extremely short counting pulse 21, which only has to be so long that it just controls the counter 20.

6 For making clear the function, and in circuitry respects for increasing the functional reliability, in the exemplified representation of Fig. 1, provided within the impulse converter 32 is again and AND-gate 24, so that the fliP-floP 33 can be set periodically, only and not until after preparation by occurrence of the ignition signal, from a free-running oscillator 22. Instead, or additionally, provision can be made for releasing the operation of the oscillator 22 not upon application of the operating voltage 35, but only upon a release signal 15 or ignition signal 17 or gate signal 18.

It serves for additional functional reliability if, as taken into account in the circuit diagram, charging of the ignition store 13 is effected only upon existence of the release signal 15, and then advantageously from this. To this end, the store 13, preferably a capacitor of relatively high capacitance, is connected by way of a charging resistor 36 subsequently to the release input 37 of the control circuit 11.

In the interests of additional security against functional disturbances by reason of interference voltage peaks coupled in by way of the long release-signal and ignition-signal lines 38, 39, arranged advantageously directly in front of or after the release and ignition inputs 37, 40 is in each case a low-pass filter 41, designed for example as an integrating R-C-circuit, the time constant of which is very small in comparison with the gate timespan tT.

If, for any reason, after the occurrence of the release signal 15, nevertheless no initiation of. the munition combat charge occurs (thus the munition becomes a "dud") self-destruction of the munition is to be striven after, in order to prevent unauthorised persons from analysing, in the case of a dud, the algorithm of its ignition logic 42, in which sensor signals are evaluated and are linked (processed) for the issuance of the ignition signal 17. (also to prevent such persons from deriving for example from this analysis interference and deception measures against the function of similar munition with such ignition logic 42). Therefore, a further ignition circuit 29, is provided, the ignition means 30 of which initiates a self-destruction 7 charge 43 (for reasons of handling safety preferably not an explosive charge, but an incendiary composition) if the munition and thus also its control circuit 11 has not been destroyed after a specific waiting time tW as a result of initiation of the combat charge 31. The determination of this waiting time tW can, as indicated in Fig. 2, be effected equally as a function of the beginning or end of the gate timespan tT or else - advantageously - as a function of the occurrence of the release signal 15 (because this is made available only in the event of immediately impending live use of the munition by the munition carrier). For determining the waiting time tW until the triggering of the self-destruction charge 43, additionally a counter 20' is provided, in the ignition circuit 29', which in the instance illustrated is released by way of its reset input 19', upon occurrence of the release signal 15 for adding-up of the output impulses 34 of the free- running oscillator 22. Upon reaching a suitably high counting position (thus upon activation of the associated output 25') the counter-state signal 26' leads to the switching through or activation of the switching member 28 in the ignition circuit 29' and thus to the initiation of the self-destruction charge 43 from the ignition store 13 which is likewise charged by way of the release signal 15.

Contrary to the simplified representation shown, also the gate time transmIssion 14 and/or the stage 33 can, instead of being designed as monostable flip-flops, be designed digitally, thus as counting stages; and the function of the AND gates 16, 24 can be realised in the CD input stage of integrated circuits in which several such functions (for the gate time transmitter 14 and the trigger stage 33) are available. Equally, for further saving on discrete circuit parts, the counter 20' can by R-Cbackcoupling wiring of consecutive binary stages at the same time serve as the oscillator 22, which is c likewise, for ease of illustration, not taken into account in the drawings.

To summarise,a control circuit 11 for the discharging circuit 12 of an electrical ignition-energy store 13 is electrically protected against faulty ignitions, as can be triggered if 4rterference voltages 8 are coupled capacitively or inductively into a long ignition control line between a sensor ignition logic 42 and the igni tion- capacitor discharge switching member 28. To - this end, the signal 26 for the release of the ignition-store discharge circuit 12 is triggered only if and when within a gate timespan (tT) as from onset of the ignition 5 signal (17) a predetermined number of asynchronously acting impulses 21 are able to be added up, but which appear at the counter 20 only when the existence of the ignition signal 17 also coincides with the output pulses 304 of a freely-running oscillator 22.

A counting pulse 21 is triggered when, within the gate timespan tT set by the timing transmitter 14, a signal on the ignition line 39 coincides in time with very short control pulses 34 from the output of the free-running oscillator 22.

Individual features of the control circuit of the present invention, or other circuitry illustrated or described herein functions, method or combination thereof may be patentably inventive, and the terminology used throughout this specification should not be construed as being unduly limiting. It is to be understood that the use of any particular term herein may extend to the use of any reasonable generally equivalent term and/or generic term where sensible.

Further according to the present invention there is provided a method of controlling an ignition or initiation circuit, in which method, an ignition or initiation signal activates the ignition or initiation circuit after a predetermined gate timespan and after a predetermined counting result is reached by a counter which counts up usually asynchronous control pulses.

9 1

Claims (14)

1. A control circuit for the discharging circuit of an electrical ignition-energy store or method of controlling said discharging circuit, characterised in that during the existence of an ignition - signal with a predetermined gate timespan control pulses supplied by an asynchronously -working oscillator are counted, and only when a predetermined counting result is reached is a counter-state signal issued for the switching through or activation of the discharge circuit.

2. A control circuit or method according to claim 1, in which the output pulses of the oscillator are shortened by means of a pulse converter into very short control pulses which in accordance with temporal coincidence with signals on an ignition line by way of an AND-gate supply the control pulses for a counter which controls an ignition circuit when a predetermined counter state is reached.

3. A control circuit or method according to claim 1 or 2, in which a, or the, control-pulse counter is kept outside the gate timespan in 20 its counting initial position.

4. A control circuit or method according to any one of the preceding claims, in which a gate time transmitter which is prepared by a release signal and which is settable by the ignition signal is provided.

5. A control circuit or method acpording to any one of the preceding claims, in which a release signal for its operational readiness and for the charging of the ignition stores is provided.

6. A control circuit or method according to any one of the preceding claims, in which the ignition signal and possibly a release signal are fed into it by way of low-pass filters.

7. A control circuit or method according to any one of the preceding claims, in which a common oscillator is provided for the control counting pulses and for the control of a further counter for the triggering of a self-destruction charge after expiry of a waiting time which is large compared with the gate timespon.

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8. A control circuit or method according to claim 7, in which an incendiary device is provided as self-destruction charge.

9. A control circuit or method for the discharging circuit of an electrical ignition energy store, substantially as herein described and illustrated with reference to the accompanying drawings.

10. The combination of a control circuit as claimed in any one of the preceding claims and an ignition circuit.

11. The combination as claimed in claim 10 in which the ignition circuit is that shown by reference numeral 29 in Figure 1 of the drawings.

12. The combination as claimed in claim 11 or claim 12 including a further ignition circuit, for example that referenced by numeral 29' in Figure 1 of the drawings, for ignition in the event of ignition failure of the first mentioned ignition circuit.

13. A circuit substantially as herein described with reference to Figure 1 of the accompanying drawings.

14. A munition including a circuit as claimed in any one of claims 1 to 9 or the combination of any one of claims 10 to 13.

9 Published 1988 at The Patent Office, State House, 66171 High Holborn, London WC1R 4TP. Further copies may be obtained frorn The Patent Ofnce, Sales Branch, St Mary Cray, Orpington, Xent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1187.

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