EP1277024B1 - Electronic self-destruct device - Google Patents

Abstract

The capacitors (C0-C4) are charged up by a piezoelement (P) for operation during flight of the shell. At least two of the capacitors (C1,C2) are connected to the input of a comparator (K) so that the influence of a continuously varying operating voltage and the influence of the output of variable voltage amplitudes by the piezoelement does not affect the timing function.

Description

The present invention relates to a device for an electronic self-destructor in a projectile fuze without the use of a battery installed in the fuze.

For today's projectile or Submunitionszünder often a self-decomposition function is also required in addition to the main ignition criteria such as service or time function, which ignites the explosive means even after not responding to the primary ignition criteria after expiration of a maximum operating time. This function, which is connected in parallel with the other ignition criteria, is intended to limit the danger zone of the ammunition in the weft direction and / or to minimize the occurrence of unexploded ordnance. As a result, operations in previously fought areas safer because of lower risk of own duds. On the other hand, this function also allows the detonation of an entrapped enemy without endangering opposing troops or civil facilities beyond a reasonable level.

Mechanical, pyrotechnic and electronic Selbstzerlegereinrichiungen are known in various embodiments. The present task is based on the required operation of an electronic self-destructor without the use of a battery. This has the advantage that the Selbstzerlegerfunktion thus equipped igniter with very high reliability is maintained over a long storage period of the igniter, since the reliability of igniter functions depends essentially on the reliability of the power supply. However, the reliability of the self-destructor function is not only critical to the functioning of the tactical use but safety-critical. For this reason, as far as possible all functional reliability-impairing components should be eliminated.

Starting from this prior art, it is therefore an object of the present invention to provide a new device with the Selbstzerlegerfunktion, especially of Geschoßzündem that does not require battery.

It is known to use the electrical energy of one or more piezoelectric elements for the electrical operation of the self-destructor device. The piezo element emits a high voltage during the firing process as a result of the high accelerations occurring there for a period of a few milliseconds, which is reloaded into storage capacitors for the longer-term operation of a power-saving electronics with a different voltage level.

The problem of such a power supply is the use of the electronics to realize the most accurate time function, although the supply voltage varies greatly, since the power supply capacitors are charged only by the launch, but are then constantly discharged by the power to be supplied. The time function should be realized instead of mechanical oscillators, such as quartz or resonators that can be damaged during firing, for cost and reliability reasons with RC elements. However, the oscillation frequency of RC oscillators are so much dependent on the operating voltage that use for self-decomposition is generally out of the question.

Now you could stabilize the output voltage of an energy storage capacitor using a switching regulator to offer the electronics as constant as possible voltage. This has the disadvantage of a relatively large amount of circuitry associated with energy losses through the voltage conversion.

From the US 4,712,477 a time fuse is known in which the potential of a slowly charging capacitor due to a time constant of a Time delay circuit is compared with a reference voltage to detect the exceeding of a certain voltage level.

auftritt. Der Komparatorausgang wechselt nach dieser Zeit seinen Zustand. Dieser Wechsel wird zum Zünden eines nachgeschalteten Zündthyristors verwendet, der einen ebenfalls durch das Piezoelement getrennt aufgeladenen Zündkondensator in ein elektrisches Zündmittel entlädt.A second solution would be to use the output voltage of the piezoelectric element to implement the time function, thereby charging a capacitor C to the voltage Uo and discharging it via a resistor R in order to detect, with the aid of a comparator, the undershooting of a specific voltage level U _S. that after the time $${\mathrm{t}}_{\mathrm{S}}\mathrm{=}\mathrm{-}\mathrm{RC\; ln}\left({\mathrm{U}}_{\mathrm{S}}\mathrm{/}{\mathrm{U}}_{\mathrm{0}}\right)$$

occurs. The comparator output changes state after this time. This change is used to ignite a downstream Zündthyristors that discharges a likewise charged separately by the piezoelectric element ignition capacitor in an electrical ignition means.

In this solution, the disadvantage lies in the dependence of Selbstzerlegerzeit t _S of U ₀ and U _S. Since piezoelectric elements are subject to production fluctuations and are temperature-dependent, the voltage U ₀ can fluctuate from shot to shot and thus also the self-destructor times. In addition, a stable switching threshold U _S in turn requires a variable operating voltage circuit complexity, which leads to a higher complexity and power consumption.

A similar solution is from the US 5,269,223 , which forms a basis for the preamble of claim 1, which describes a safety circuit for the time-delayed ignition of a detonator, in which a time delay is achieved with the involvement of capacitors, by comparing the discharge of a capacitor with a reference voltage generated in a piezoelectric element.

It is therefore a circuit to be provided, on the one hand as simple as possible and energy-saving, inexpensive and thereby (due to reduced number of components) is reliable and on the other hand allows to realize the time function with RC elements regardless of a fluctuating supply voltage level.

This is possible with the device described in claim 1. As a result, neither the influences of a constantly changing operating voltage nor the influences of the output of variable voltage levels by the piezoelectric element affect the time function. The claims 2 to 3 relate to advantageous embodiments of the invention. In the following, the invention will be briefly explained with reference to the accompanying Fig. 1.

Via a piezoelectric element P, a series resistor R0, a Zener diode Z (for limiting the voltage) and the diodes D0 to D3, the capacitors C0 to C4 are charged during firing. The charged capacitor C0 then provides, via the resistor R4 and the second storage capacitor C3 delayed, the supply voltage for the operation of the comparator K ready. The comparator K is a commercially available integrated module with extremely low current consumption (<1 μA), very small input currents (<1 pA) and a common mode range extending to the operating voltage limits.

The delayed supply of the operating voltage is to prevent a malfunction during the tube passage phase and the delayed charged capacitor C3 supplies the energy for driving the thyristor Th at the time of ignition.

The ignition capacitor C4 is charged via the diode D3, and remains until the ignition of the thyristor at a sufficient voltage level.

In order to realize a time-independent function of the voltage delivered by the piezoelectric element, the two capacitors C1 and C2 are charged to the same voltage U _o by the piezoelectric element via the two high-blocking diodes D1 and D2.

The capacitor C1 is connected via a voltage divider R1 and R2 to the positive input of the comparator K. The capacitor C2 is connected directly to the negative input of the comparator and is discharged after the firing via the resistor R3.

For fast and safe switching of the comparator K is coupled via the resistor R5, so has a hysteresis. After firing is because of the voltage divider R1 and R2 at the negative input of the comparator K, a higher positive voltage than at the plus input. The output of the comparator is therefore at zero potential at this time. The capacitor C1 is then discharged via the equivalent resistance R _e = R 1 + R 2 * with R 2 * = R 2 ∥ R 5 = R 2 R 5 / (R 2 + R 5).

unterschreitet das Potential an C2 (am Minuseingang des Komparators K) das sich langsamer ändernde und um den Faktor R2* / R_e verminderte Potential von C1 am Pluseingang des Komparators K. Danach schaltet der Komparator seine Ausgangsspannung auf Pluspotential und zündet damit den Zündthyristor Th über den Strombegrenzungswiderstand R6 und den Spannungsteiler R7 und R8. Der Kondensator C5 dient zur Störunterdrückung und spielt für das Funktionsprinzip keine Rolle.The time constants τ ₁ = R _e C1 and τ ₂ = R3 C2 are chosen so that τ ₁ > τ ₂ , ie C2 discharges faster than C1. At the time of the set self-disassembly time $${\mathrm{t}}_{\mathrm{s}}\mathrm{=}{\mathrm{\tau }}_{\mathrm{1}}{\mathrm{\tau }}_{\mathrm{2}}\mathrm{/}\left({\mathrm{\tau }}_{\mathrm{2}}\mathrm{-}{\mathrm{\tau }}_{\mathrm{1}}\right)\ln \left(\mathrm{R}\mathrm{2}\mathrm{*}\mathrm{/}{\mathrm{R}}_{\mathrm{e}}\right)$$

the potential at C2 (at the negative input of the comparator K) drops below the potential of C1 which decreases more slowly and is reduced by the factor R2 * / R _e at the plus input of the comparator K. Thereafter, the comparator switches its output voltage to positive potential and thus ignites the ignition thyristor Th the current limiting resistor R6 and the voltage divider R7 and R8. The capacitor C5 is used for interference suppression and plays no role for the operating principle.

The energy stored in the ignition capacitor C4 is thereby switched through to the electrical ignition means EZ and this causes it to trigger. On the sketched input T, the thyristor Th can be ignited by other circuit parts not shown here also on the Hauptzündkriterien.

d.h. daß sie sich in weiten Bereichen fast linear durch alleinige Änderung des Widerstands R3 einstellen läßt.A further simplification of the circuit and the calculation results if the capacitors C1 and C2 are chosen to be the same size: C1 = C2 = C. The self-destructor time t _s then becomes equal to $${\mathrm{t}}_{\mathrm{s}}\mathrm{=}{\mathrm{R}}_{\mathrm{e}}C/(1-{\mathrm{R}}_{\mathrm{e}}/\mathrm{R}3)\ln \left(\mathrm{R}2*/{\mathrm{R}}_{\mathrm{e}}\right)$$

that is, they can be adjusted almost linearly by changing the resistance R3 in a wide range.

Due to the difference formation of the present comparator circuit, neither the equation (2) nor the equation (3) assumes a variable which is variable during firing. The goal of the task is thus achieved.

A changed field of use of the circuit is revealed when you can do the charging of the capacitors C0 to C4 instead of a piezoelectric element when fired by a voltage in a warhead, either permanently applied or shortly before the emission of submunition, controlled by a warhead electronics produced becomes. The circuit then serves for timed initiation of a self-decomposition of the ejected submunition. As long as on-board voltage is applied, neither C1 nor C2 discharges and nothing happens at the comparator output. Only when the voltage supply stops (ejection of the submunition), the self-destruct device is activated; the capacitors C1 and C2 begin to discharge and, as described, initiate the ignition process

Instead of the piezoelectric element used in connection with the exemplary embodiment, a shock generator can also be used. In Fig. 1, the piezoelectric element P would then be replaced by a shock generator, not shown.

Claims (3)

1. Apparatus for the time-controlled self-destruction of a projectile by means of an electronic self-destruct device without batteries, wherein a plurality of capacitors (C0, C1, C2, C3, C4) which are charged during firing by a piezo element (P) or a surge generator are used for operation in the flight phase, characterised in that at least a first and a second of the capacitors (C1, C2) have the same voltage (U₀) after charging, and in that the first capacitor (C1) is connected via a voltage divider (R1, R2) to the plus input of a comparator (K) and the second capacitor (C2) is connected directly to the minus input of the comparator (K) in such a way that the potential at the minus input of the comparator (K) after firing is greater than the potential at the plus input of the comparator (K), and in that the time constant (τ₁) for discharging the first capacitor (C1) is greater than the time constant (τ₂) for discharging the second capacitor (C2).
2. Apparatus according to claim 1, characterised in that the first capacitor (C1) is discharged across the voltage divider (R1, R2) and the second capacitor (C2) is discharged across a resistor (R3).
3. Apparatus according to one of the preceding claims, characterised in that the comparator (K) is coupled via a resistor (R5).

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