GB2221284A

GB2221284A - Proximity fuse.

Info

Publication number: GB2221284A
Application number: GB8404945A
Authority: GB
Inventors: Hubert Schmidt
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1983-04-27
Filing date: 1984-02-27
Publication date: 1990-01-31
Anticipated expiration: 2004-02-27
Also published as: DE3315166A1; GB8404945D0; DE3315166C2; FR2635861A1; GB2221284B

Abstract

The invention relates to a proximity fuze for projectiles (rounds) having at least one sensor where the variable which is monitored by said sensor changes on approaching a conductive body and is utilised to initiate detonation. Frequency changes which occur in the sensor oscillator as a result of production tolerances, aging processes and temperature effects in the components are compensated for immediately with the aid of a follow-up synchronisation circuit, so that there is no longer any need for circuit tuning (calibration). The high sensitivity of the fuzing circuit is maintained when the projectile approaches the target by means of two selectively acting control loops.

Description

Description Proximity fuse The invention concerns a proximity fuse for projectiles with at least one sensor, the magnitude monitored by which is utilised for the triggering of an ignition on approaching a conducting body.

From the DE-OS 16 78 631, a proximity fuse is known for projectiles, rockets or dropped bombs, which contains an oscillator circuit, the frequency-determining resonant circuit of which contains a capacitor, the electrodes of which consist of two projectile parts insulated each from the other. When the projectile approaches a surface, for example of the earth, then the capacitance between earth and the electrodes becomes connected in parallel with this capacitor. A rapid change in frequency produces an output signal, which is employed for the ignition of the fuse, at the output of the frequency discriminator connected behind the oscillator.

This fuse is however very insensitive to changes in capacitance and can therefore be used only in special metal detecting devices. The individual resonant circuits must be frequently retested and, in a given case, re-adjusted because of the possible occurrence of ageing effects, particularly in the case of longer storage times.

The invention is based on the task of so developing the ignition circuit of a fuse according to the species that present production tolerances as well as occurring ageing processes or temperature effects on the components are compensated for by circuit technique and thus do not influence the optimum ignition behaviour of the fuse. In particular, the high sensitivity of the ignition circuit on approaching the target shall not be impaired thereby.

Accordind to the invention, the construction according to the characterising clause of the claim 1 is provided for the solution of this problem. Present production tolerances as well as occurring ageing processes or temperature effects in the components are compensated for by the invention named in the claim 1. An additional frequency compensation of the fuse is therefore not required.

Advantageous refinements and developments of the invention are stated in the subclaims.

According to claim 4, two low pass filters built up with RC-members are employable for the selective processing of the control signal, which appears at the output of the regulating voltage amplifier, for the voltage-controlled oscillator.

According to one embodiment of the invention, the oscillator drift due to ageing or temperature change is compensated for in advantageous manner by the regulating circuit of large RC-value. The regulating circuit of small RC-value and an insensitive control input of the voltagecontrolled oscillator effects a high sensitivity of the circuit on approach of the projectile towards the target.

Further features of advantageous embodiments and developments of the invention are evident in the following description of the figures in conjunction with the claims.

Fig. 1 block circuit diagram of the proximity fuse Fig. 2 regulating circuits and frequency-determining part of the voltage-controlled oscillator Illustrated by Fig. 1 is an example of a proximity fuse for projectiles with a sensor 1, the magnitude monitored by which changes on approaching a conducting object. The sensor lies in the resonant circuit of the sensor oscillator 2 and changes the sensor oscillator frequency on a change in its magnitude to be monitored. This can be effected, for example, by an arising additional capacitance or inductance through the approach of the sensor to a conducting object. For the switching-on of the fuse, the discriminator 4 operates as frequency discriminator.

When the frequency of the sensor oscillator 2 is higher or lower than that of the voltage-controlled oscillator 3, the frequency discriminator 4 supplies an output voltage which is determined by the difference between both the oscillator frequencies. The output signal A of the regulating voltage amplifier 5 connected therebehind pulls the voltage-controlled oscillator 3 to follow until both oscillator frequencies are equal. When the frequency spacing of both the oscillators amounts to zero, the discriminator 4 operates as phase discriminator. The catchment range of the circuit corresponds to the pulling range.

The discriminator output signal, which is generated through slowly devolving frequency fluctuations of the sensor oscillator 3, immediately pulls the frequency of the voltage-controlled oscillator to follow by way of the low pass filter of low limit frequency 6a and the highly sensitive control input E2 of the voltage-controlled oscillator 3. These changes in the coarse regulating circuit do not appear at the evaluating circuit and therefore do not cause any ignition pulse. Connected in parallel with the coarse regulating circuit is a fine regulating circuit which however plays a subordinate part for this case.

If short-term, pulse-like frequency fluctuations appear at the sensor oscillator output, then these are compensated for at once by way of the fine regulating circuit which contains a low pass filter of high limit frequency b and a less sensitive control input El of the voltagecontrolled oscillator 3. Also in this case, no ignition pulses are initiated in the evaluating circuit.

The less sensitive control input El of the voltage-controlled oscillator 3 is realised by a loose, for example capacitive coupling 9 of a capacitance diode 10 to the resonant circuit 11 of the voltagecontrolled oscillator 3, as illustrated for example in Fig. 2. This leads at the same time to a high sensitivity of the circuit in the case of a rapid approach of a projectile towards a target, because the steady rapid increase or decrease in the magnitude to be monitored by the sensor, for example of an additionally arising capacitance or inductance, can then be compensated for only by this fine regulating circuit and the voltage present at the output of the regulating voltage amplifier therefore causes an ignition pulse in the evaluating circuit. Simultaneously arising, slowly devolving frequency fluctuations continue to be compensated for by way of the coarse regulating circuit.

TRANSLATION OF LEGENDS IN THE DRAWINGS Diskriminator = discriminator Zündimpuls = ignition pulse

Claims

Patent Claims 1. Proximity fuse for projectiles with at least one sensor, the physical magnitude monitored by which is utilised for the ignition on approaching a conducting body, characterised thereby, that the magnitude monitored by the sensor (1) influences the frequency-determining part of a sensor oscillator (2), that a voltage-controlled oscillator (3) is the component of a tracking synchronisation with a discriminator (4), the one input of which is connected with the output of the sensor oscillator, the other input of which is connected with the output of the voltage-controlled oscillator and the output of which is connected with the input of a regulating voltage amplifier,that an output signal (A) of the regulating voltage amplifier pulls the voltage-controlled oscillator in a regulating loop through at least one low pass filter (6) until the sensor oscillator frequency and the frequency of the voltage-controlled oscillator (3) are equal and that the output signal (A) of the regulating voltage amplifier - on agreement with a predeterminable time and amplitude behaviour generates an ignition pulse in a connected evaluating circuit (8).

2. Proximity fuse according to claim 1, characterised thereby, that two low pass filters (Ea and 6b), lying in parallel each to the other, with differently high limit frequencies are connected between the output (A) of the regulating voltage amplifier and the control input of the voltagecontrolled oscillator.

3. Proximity fuse according to claim 2, characterised thereby, that the voltage-controlled oscillator (3) possesses two control inputs (El and E2), which are provided with different sensitivity and through which the frequency of oscillation of the oscillaror is pulled.

4. Proximity fuse according to claim 3, characterised thereby, that the output of the low pass filter (5b) of high limit frequency is connected with the less sensitive control input (El) and the output of the low pass filter (6a) of low limit frequency is connected with the highly sensitive contol input (E2) of the voltage-controlled oscillator (3).

Amendments to the claims have been filed as follows CLAIMS 1. A proximity fuse for missiles and comprising a sensor to monitor a physical magnitude subject to change on the missile approaching a target, a sensor oscillator arranged to oscillate at a frequency influenceable by the sensor, a voltage-controlled oscillator, a discriminator circuit provided with first input meana connected to output means of the sensor oscillator and with second input means connected to output means of the voltage-controlled oscillator, a regulating loop which includes a regulating voltage amplifier and low pass filtor means and which o couples output means of the discriminator circuit with control input means of the voltage-controlled oscillator as to cause the frequency of the voltage-controlled oscillator to be regulated to a value which is at least approximately equal to that of the sensor oscillator, and evaluating circuit means responsive to a signal of predetermined characteristics received from the regulating voltage amplifier to generate an ignition pulse for the fuse.
2. A proximity fuse as claimed in claim 1, the low pass filter means comprising two low pass filters of different cut-off frequencies.
3. A proximity fuse as claimed in claim 2, the control input means comprising two control input circuits of different sensitivities.
4. A proximity fuse as claimed in claim 3, wherein the low pass filter of higher cut-off frequency is connected to the control input circuit of lower sensitivity and the low pass filter of lower cut-off frequency is connected to the control input circuit of higher sensitivity.
5. A proximity fuse substantially as hereinbefore described with reference to and as illustrated by Fig. 1 of the accompanying drawings.
6. A proximity fuse substantially as hereinbefore described with reference to and as illustrated by Figs. 1 and 2 of the accompanying drawings.