PERCUSSION FUSE

Abstract

The invention relates to a percussion fuse having an active sensor, which generates a sensor voltage, having a filter circuit consisting of a high pass and at least one low pass, in order to be able to adjust dynamic percussion characteristics. The invention further relates to an operating state switch, which can transition the percussion fuse into one of two operating states, specifically into an activated and a deactivated operating state. To this end, the operating state switch is switched into one of the two operating states by means of a safety voltage. In the active operating state, the sensor voltage is supplied directly to the threshold value switch and in the deactivated operating state, the sensor voltage is held below the threshold value of the threshold value switch by an input limiter.

Claims

1.-16. (canceled)

17. A percussion fuse having an active sensor which can convert mechanical energy into electrostatic energy which can be used to generate a sensor voltage (U.sub.S), having a threshold value switch (D1) which blocks voltage signals below a threshold value and forwards voltage signals above the threshold value as a firing voltage (U.sub.Z), wherein a filter circuit comprising a high-pass filter (C1+R1) and at least one first low-pass filter (C6+R6) is provided, in that the filter circuit filters out low and high frequencies in the sensor voltage (U.sub.S), in that an operating state switch (Q2) is provided and can change the percussion fuse to one of two operating states, namely an activated operating state and a deactivated operating state, by means of a safety voltage (U.sub.V), wherein the sensor voltage (U.sub.S) is supplied to the threshold value switch (D1) in the activated operating state and the sensor voltage (U.sub.S) is limited, via input limitation (Q1), to below the threshold value of threshold value switch (D1) in the deactivated operating state.

18. The percussion fuse as claimed in claim 17, wherein the input limitation (Q1) is arranged upstream or downstream of the resistor (R2) of the low-pass filter.

19. The percussion fuse as claimed in claim 17, wherein two low-pass filters (C5+R5, C6+R6) are provided, the outputs of which can each be combined via a diode (D5, D6).

20. The percussion fuse as claimed in claim 19, wherein the two low-pass filters (C5+R5, C6+R6), when arranged in a parallel manner, a voltage barrier which is in series with the low-pass filter resistor is arranged, preferably as a Zener diode (in the reverse direction), for each low-pass filter.

21. The percussion fuse as claimed in claim 17, wherein the filters are programmable and can be connected and disconnected or adjusted.

22. The percussion fuse as claimed in claim 17, wherein capacitors (C3, C4) are provided and reduce the switch-on delay caused by the resistor R3 of the input limitation Q1.

23. The percussion fuse as claimed in claim 17, wherein a resistor R7 is provided in order to compensate for leakage currents of the threshold value switch (D1).

24. The percussion fuse as claimed in claim 17, wherein a buffer (for example capacitor in parallel with R8) is provided for the operating state switch (Q2) and retains the electrical state of the operating state switch (Q2) for a short time even in the event of a change.

25. The percussion fuse as claimed in claim 17, wherein potential coupling (R8) is provided and sets the activation voltage (U.sub.A) for the operating state switch (Q2) to a ground potential if no activation voltage (U.sub.A) is actively supplied to the percussion fuse.

26. The percussion fuse as claimed in claim 17, wherein the threshold value switch (D1) is implemented by means of an electronic circuit or a trigger diode (DIAC) is used as the threshold value switch (D1).

27. The percussion fuse as claimed in claim 17, wherein transistors are used as the input limitation (Q1) and/or as the operating state switch (Q2), wherein reverse-biased diodes can be provided in parallel with the collector and emitter inputs in the transistors.

28. The percussion fuse as claimed in claim 17, wherein a Zener diode, in particular a suppressor diode, is used as voltage limitation (D2).

29. The percussion fuse as claimed in claim 17, wherein the operating state switch (Q2) is in the form of an electronic switch or a relay contact.

30. The percussion fuse as claimed in claim 17, wherein the output of the percussion fuse (U.sub.Z) directly or indirectly initiates the active substance, usually the detonator.

31. The percussion fuse as claimed in claim 17, wherein further filters can be integrated in the circuit in order to produce a complex transfer function.

32. The percussion fuse as claimed in claim 17, wherein the input limitation (Q1) is in the form of a MOSFET and limits the positive sensor voltage (U.sub.S) to the maximum drain-source voltage and limits the negative sensor voltage (U.sub.S) to −0.7 V.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Further features emerge from the accompanying drawings, in which:

[0023] FIG. 1 shows an exemplary circuit diagram of a percussion fuse according to the invention.

DETAILED DESCRIPTION

[0024] FIG. 1 shows the percussion fuse according to the invention, wherein the active sensor which may be a piezo sensor, for example, is not shown. The sensor is connected to GND at the two points of the sensor voltage U.sub.S and provides electrostatic energy E.sub.el. This electrostatic energy is supplied, in the form of charge, to the capacitor C1 directly at the input of the sensor voltage U.sub.S and is converted into a proportional electrical voltage in the capacitor. This voltage, stored charge, is used for the further connection of the percussion fuse.

[0025] The invention is divided into two operating states, an activated state and a deactivated state.

[0026] The operating states are switched over via an operating state switch Q2. The latter is in the form of an NMOSFET in the present case. This NMOSFET is used as an electronic switch and can deactivate the input limitation Q1 when the activation voltage U.sub.A is applied.

[0027] Potential coupling R8 which keeps the potential at ground potential when the activation voltage U.sub.A disappears is introduced in parallel with the activation voltage U.sub.A. As a result, the percussion fuse is deactivated, that is to say changed to a safe state.

[0028] When the operating state switch Q2 is activated, the operating state switch Q2 in FIG. 1 connects the gate of the transistor Q1 to ground. The transistor Q1 can no longer turn on and therefore will no longer limit the sensor voltage to less than approximately 3 V. This operating state switch Q2 is controlled by the fuse electronics or the voltage U.sub.A.

[0029] Controlled in the deactivated operating state, the MOSFET, as the input limitation Q1, is then no longer turned off by the operating state switch Q2, with the result that the capacitor C4 is charged in the case of a positive sensor voltage.

[0030] If the capacitor voltage of the capacitor C4 exceeds the threshold gate-source voltage of the input limitation Q1 after a short delay caused by the resistor R3, the input limitation Q1 turns on and then short-circuits the voltage to the downstream filters. The threshold value switch D1 does not receive any voltage for connection. This function is supplied by the active sensor.

[0031] The circuit advantageously need not be externally supplied, with the result that the energy from the active sensor is sufficient to generate the firing pulse of the firing voltage U.sub.Z. If the threshold value switch D1 turns on, the energy stored in the low-pass filters C5+R5 and C6+R6 is large enough to guarantee a trigger pulse even in the event of an additional trigger delay. A so-called pump effect is not possible as a result.

[0032] The above-mentioned pump effect occurs if shockwaves run through the munition body during impact of the munition, which is the case with hard targets, in particular. These shockwaves generate an oscillating signal from the active sensor and therefore an oscillating sensor voltage. In conventional percussion fuses, the firing pulse can be suspended or delayed as a result.

[0033] The input limitation Q1 is preferably likewise in the form of an NMOSFET. In order to now safely keep this sensor voltage below the threshold value, the input limitation Q1 is arranged in parallel with the sensor voltage U.sub.S or downstream of the first low-pass filter (drain Q1 at the capacitor C2). If there is now a positive sensor voltage U.sub.S, the capacitor C4 is charged between the gate and the source. If the NMOSFET exceeds its threshold gate-source voltage, it turns on between the drain and the source with a very low resistance. The input limitation which is now on short-circuits the sensor voltage U.sub.S to the threshold gate voltage. A negative sensor voltage U.sub.S is likewise limited by the drain-source diode. Assuming that the diode voltage is 0.7 V and the threshold gate voltage of the input limitation has a value of 3.5 V, the sensor voltage U.sub.S is therefore limited to values of between −0.7 V and 3.5 V. For this reason, the downstream threshold value switch has a higher breakdown voltage (breakover) than 3.5 V, for example 20 V.

[0034] If an activation voltage U.sub.A is applied, the input limitation Q1 is changed to the deactivated state by the operating state switch Q2, with the result that there is no longer any voltage limitation of the sensor voltage U.sub.S. In this case, the full sensor voltage U.sub.S or the proportional voltage applied to the capacitor C1 is passed, through the downstream low-pass filter group, to the threshold value switch D1. In the present figure, this threshold value switch D1 is in the form of a trigger diode which operates with a breakdown voltage of 20 V, for example. This means that voltage signals of the sensor voltage U.sub.S below 20 V are not passed through the trigger diode but voltage signals above 20 V are passed through the trigger diode. The drain-source diode of the NMOSFET still remains active, with the result that the sensor voltage U.sub.S is still limited to 0.7 V in the negative case, irrespective of the operating state of the percussion fuse. The current through the drain-source diode results in a zero point shift.

[0035] The high-pass filter connected downstream of the sensor input U.sub.S comprises the capacitor C1 and the resistor R1. A low-pass filter C2+R2 which is arranged between the high-pass filter C1 +R1 and the threshold value switch D1 then follows. This low-pass filter C2+R2 ensures that high frequencies which are likewise not intended to result in the firing of the percussion fuse are likewise filtered out from the sensor voltage U.sub.S. 2 different further low-pass filters are connected downstream of this first low-pass filter.

[0036] The low-pass filter branch (C5, R5, with a low time constant) is for the strong signal components (hard targets) and has a reverse-biased Zener diode D2 in series. This reduces the voltage supplied to the filter C5, R5 by the Zener voltage of the Zener diode D2. The Zener diode D2 also prevents charge from flowing into the capacitor C5 in the case of a low voltage level and the overall sensitivity being reduced thereby because this part of the charge would be missing in the capacitor C6. Only at a sufficiently high level is the capacitor C5 charged to the trigger voltage of the threshold value switch D1 which then switches the capacitor voltage through to the output U.sub.Z.

[0037] The second low-pass filter C5+R5 is then assigned to the output signal, that is to say the firing voltage U.sub.Z, and filters high frequencies from the firing voltage U.sub.Z. The low-pass filter additionally has a Zener diode D2 in series with the resistor R5. The Zener diode D2 reduces the input voltage of the low-pass filter by the Zener voltage.

[0038] The low-pass filter branch (C6, R6) for the weaker signal components has a higher time constant, with the result that the capacitor C6 can be charged more slowly to the trigger voltage of the threshold value switch D1. The latter then likewise switches the capacitor voltage C6 through to the output U.sub.Z. There is no voltage-reducing Zener diode in this low-pass filter branch, and even small amplitudes can therefore contribute to charging C6.

[0039] A diode (D5 and D6) at the output of each low-pass filter branch respectively decouples the output voltages and prevents the mutual influence of the two filters. Dynamic signals are filtered by the two filters and are not supplied to the threshold value switch D1.

[0040] The voltage limitation D7 of the firing voltage U.sub.Z ideally limits the firing voltage U.sub.Z to a value which is slightly above the threshold value voltage of the threshold value switch D1.

[0041] The special feature of this embodiment is that the input voltage, that is to say the sensor voltage U.sub.S, of the first low-pass filter C2+R2 is not limited. A hard target or a high munition speed also results in a long delay, with the result that the active sensor provides a large amount of energy in the form of charge in a short time, which energy is converted into a high voltage pulse in the capacitor C1. A high voltage shortens the time needed to charge the first low-pass capacitor C2 and to turn on the threshold value switch D1. The firing pulse is therefore highly dynamic. If the target is soft or the munition is slower, the trigger pulse, that is to say the firing voltage U.sub.Z, is also slightly delayed. The trigger characteristic of the percussion fuse can therefore be set within certain limits by means of correct parameterization, that is to say setting of the filters.

[0042] In order to limit the firing voltage U.sub.Z provided when turning on the threshold value switch D1 to a certain value, voltage limitation D7 is provided, by means of a Zener diode or a suppressor diode in the present case. Voltages above the breakdown voltage of this Zener or suppressor diode are short-circuited via the diode, with the result that the firing voltage U.sub.Z is limited to a maximum voltage.

[0043] A diode D2 is also provided in series with the firing voltage U.sub.Z and is intended to protect the electronic circuit of the percussion fuse from currents which have been fed back.

[0044] So that the input limitation (Q1) can be arranged in a simple manner upstream or downstream of the resistor (R2) of the low-pass filter, disconnection of the connections 21-22 and connection of the connections 22-23 are provided.

[0045] The present invention is not restricted to the features mentioned above, but rather further embodiments are conceivable. It would be possible to provide a fuse which only activates the percussion function of the fuse after a programmed time. The transfer function could be programmable and/or higher-order low-pass and high-pass filters could likewise be used to more accurately set the percussion characteristic, that is to say is to set the dynamic response.

LIST OF REFERENCE SIGNS

[0046] U.sub.S Sensor voltage

[0047] U.sub.V Safety voltage

[0048] U.sub.Z Firing voltage

[0049] C1+R1 High-pass filter

[0050] C2+R2 Low-pass filter

[0051] C5+R5 First low-pass filter

[0052] C6+R6 Second low-pass filter

[0053] R8 Potential coupling

[0054] C3+C4+R3 Low-pass filter for Q1

[0055] C3+R4 High-pass filter for Q1

[0056] D1 Threshold value switch

[0057] D2 Zener diode

[0058] D3+D4 Decoupling diodes

[0059] D5 Voltage limitation

[0060] Q1 Input limitation

[0061] Q2 Operating state switch

[0062] R7 Leakage current compensation of D1