IL204223A

IL204223A - Method for initiating a warhead of a shell and a vehicle

Info

Publication number: IL204223A
Application number: IL204223A
Authority: IL
Original assignee: Diehl Bgt Defence Gmbh & Co Kg
Priority date: 2009-03-03
Filing date: 2010-03-01
Publication date: 2014-06-30
Also published as: DE102009011447B4; EP2226607A2; DE102009011447A1; DE102009011447B9; EP2226607B1; EP2226607A3

Description

METHOD FOR INITIATING A WARHEAD OF A SHELL, AND A VEHICLE Pearl Cohen Zedek Latzer P-73782-IL CM/GS/bu Diehl BGT Defence GmbH & Co. KG, Alte NuBdorfer Strafie 13, 88662 Oberlingen Method for initiating a warhead of a shell, and a vehicle The invention relates to a method for initiating a warhead of a shell. It also relates to a vehicle having a device for initiating a warhead of a shell.

Vehicles, in particular tanks, armoured vehicles or the like, are sometimes attacked by projectiles which can penetrate the armour. The passive protection provided by the vehicle armour is therefore not always adequate. So-called active protection systems have recently been developed in order to counteract this disadvantage. In this case, a projectile approaching the vehicle is detected, for example by means of a radar. A shell is fired for defence against the projectile, with the aim of destroying the projectile before it strikes the vehicle. For this purpose, the shell is provided with a proximity fuze, which initiates a warhead in the shell when a predetermined minimum distance from the projectile is detected. In practice, it has been found that the accuracy or delivery accuracy which can be achieved in this way is not always adequate. Apart from this, shells with proximity fuzes are relatively expensive.

The object of the invention is to overcome the disadvantages according to the prior art. One particular aim is to specify a method for initiating a warhead of a shell, which method has a better delivery accuracy. A further aim of the invention is to specify a vehicle which is equipped with a device for carrying out the method.

By way of example, this object is achieved by the features of Claims 1 and 8. The expedient refinements of the invention are specified in the features of Claims 2 to 7 and 9 to 14.

By way of example, a method is provided for initiating a warhead of a shell, having the following steps: detection of a moving target; calculation of a first initiating time and setting a time fuze, which is provided in the warhead, to the first initiating time; firing of a shell in the direction of the target and activation of the time fuze; measurement of the time interval between activation of the time fuze and time at which the shell leaves a firing barrel (T4-time), and determination of an initial velocity of the shell on leaving the firing barrel; calculation of a second initiating time using the measured time interval as well determined initial velocity; and replacement of the first initiating time by the second initiating time.

It is noted that the calculation of the first initiating time and the setting of the time fuze which is provided in the warhead to this first initiating time, as well as the replacement of the first initiating time by the second initiating time are not necessarily essential for the operation of the present invention. The setting of the time fuze to the second initiating time (which then represents the only initiating time) is sufficient for success. In this case, it is advantageous for the time fuze to be set only after the shell has been fired (= initiation of the propellant charge of the shell) in the direction of the target, preferably at the time at which the shell or the warhead of the shell leaves the firing barrel. The present invention is able to compensate for discrepancies on the previously calculated norm for the launch time and the initial velocity of the shell. Discrepancies such as these are inherent in a pyrotechnic system, as represented by the propellant charge of the shell, since the burning parameters of a propellant charge cannot be predicted exactly. By way of example, the following two options may be considered for such compensation for discrepancies, although these do not represent a final solution, and can be applied individually or cumulatively.

If the time fuze is activated at the time when the shell is fired (= initiation of the propellant charge of the shell) in the direction of the target, the time interval of T4-time represents a delay, that is to say an extension to what is actually required, previously calculated initiating time duration (= time interval from activation of the time fuze to detonation of the warhead). In order now to obtain the actually required initiating time duration from the first initiating time duration (time interval from activation of the time fuze to the first initiating time), the time interval of T4-time is subtracted from the first initiating time duration. This difference then represents the second initiating time duration, which is applied to the time fuze at the moment when it leaves the firing barrel. The second (or only) initiating time duration is the time interval from the shell leaving the firing barrel to detonation of the warhead.

However the calculation of the initiating time duration also depends on the actual initial velocity of the shell. If the actual initial velocity is less than the nominal initial velocity, the initiating time duration can be correspondingly lengthened. Conversely, the initiating time duration can be shortened to correspond to the discrepancy from the norm, if the actual initial velocity is higher than the nominal initial velocity.

According to the proposed method, a time fuze is used for initiating the warhead. In comparison to the proximity fuze used according to the prior art, a time fuze such as this can be produced easily and cost-effectively.

Data supplied on detection of the target is evaluated in order to set the time fuze to a first initiating time. That time at which it is predicted that the target and the shell that is fired at it will meet, is calculated as the first initiating time. In order now to achieve particularly high delivery accuracy, the invention also provides that, when the shell is fired, the T4-time is measured and the initial velocity of the shell on leaving the firing barrel is determined. A second initiating time is calculated with the aid of these two parameters. The calculated second initiating time is more exact than the first initiating time since, in this case, the measured T4-time and the determined initial velocity of the shell are additionally used for calculation. The first initiating time is then replaced by the second initiating time. This makes it possible to considerably improve the delivery accuracy. With the proposed method, it is possible to highly effectively protect vehicles against approaching projectiles, for example anti-tank missiles and the like.

For the purposes of the present invention, the term "shell" refers to a unit which is fired from a firing barrel. The "T4-time" means a time interval which extends from the activation of the time fuze of the shell to the shell leaving the firing barrel. The T4-time is therefore that time interval which the shell requires from the time of activation of the time fuze to the time it reaches a predetermined waypoint, which is provided at the firing barrel. The latter time is preferably that time at which the rear part of the warhead of the shell passes the front end of the firing barrel. The accelerating effect of the propellant charge for the shell decreases at the latest at this time. This time is the firing time or the launch time of the shell. At this launch time, other parts than the warhead of the shell (for example a fin assembly and sensors connected to this assembly) may still be located in the firing barrel. The term "initial velocity" means the velocity of the shell on leaving the firing barrel. The initial velocity is the velocity of the shell relative to the firing barrel at a specific predetermined waypoint on the firing barrel.

According to one advantageous refinement, the target is detected by means of a radar device, preferably a Doppler radar device, and/or an IR device. In consequence, the direction and/or velocity of the approach to the target can be calculated using conventional algorithms by means of a control computer. On the basis of the results achieved in this way, the first initiating time is then calculated using a preset T4-time and a preset initial velocity, and the time fuze is set to the first initiating time.

As soon as this has been done, a clock contained in the time fuze is switched on by a trigger signal which is produced by the control computer. The production of the trigger signal results in a common time base between the clock and the control computer for all further calculations. This common time base is used, in particular, to carry out the further time measurements and to calculate the second initiating time. This increases the accuracy of the method.

In order to measure the T4-time and in order to determine the initial velocity, a plurality of markings, which are separated from one another in the axial direction, are advantageously provided on the firing barrel. The shell expediently has at least one sensor, by means of which a signal is produced when a predetermined distance from the respective marking is undershot. For the purposes of the present invention, the term "marking" means a section which can be physically detected by a sensor and is applied at a predetermined distance from one end of the firing barrel. In this case, the markings and the sensor are designed such that a signal is produced only when the sensor is in the immediate vicinity of the marking.

The markings are preferably ferromagnetic elements. Ferromagnetic elements such as these may be designed to be annular with respect to an axis of the firing barrel. When markings such as these are provided, the firing barrel is produced from a non-ferromagnetic material. A Hall sensor may be used as the sensor for detection of the ferromagnetic elements. Sensors such as these are generally known according to the prior art, and are available at low cost.

According to a further refinement of the method according to the invention, the clock is in each case used to measure time differences between the time when the trigger signal is produced and further times when the sensor signals are produced. At least two, and preferably three, measured time differences are used to determine the initial velocity. When three measured time differences are used, it is also possible to check whether the shell is moving at a constant velocity.

The time fuze and the control computer are connected to one another via a data transmission path in order to set the time fuze and in order to transmit the time differences and time periods measured by the clock. The data transmission path may be formed without the use of cables, or may be formed from a cable. In particular, the first and the second initiating times are transmitted via a cable which connects the time fuze to the control computer. The cable-based transmission proposed here is particularly reliable and not susceptible to interference.

A further measure according to the invention provides a vehicle having: a detection device for detection of a moving target, a shell launcher device with a measurement device for measurement of a T4-time and at least one further time value for determination of an initial velocity of a shell when it leaves the firing barrel, a control computer which is connected to the detection device and to the shell launcher device, for calculation of a first initiating time and a second initiating time as a function of a measured T4-time and a specific initial velocity, and a data transmission path for transmission of the first and second initiating times from the control computer to the time fuze.

The proposed vehicle, which is preferably an armoured vehicle, is particular effectively protected against projectiles that are fired at it, for example anti-tank missiles, shells or the like.

Because of the advantageous refinements of the vehicle, reference is made to the features described relating to the method which, in the same sense, may also form refinements of the vehicle.

One refinement of the invention will be explained in more detail in the following text with reference to the drawing, in which: Figure 1 shows a schematic overview of the major components of an active system, Figure 2 shows a schematic section view through a shell launcher device having a measurement device, and Figure 3 shows a detail view of the measurement device shown in Figure 2.

In Figure 1 , a target detection device 1 , for example a Doppler radar, is connected to a control computer 2 in order to evaluate the signals received by this device. The control computer 2 is connected via a cable connection 3 to a time fuze 4 for a warhead of a shell. The reference symbol 5 denotes a measurement device by means of which a T4-time and at least one further time value can be measured in order to determine an initial velocity of the shell. The measurement device 5 is likewise connected to the control computer 2. A firing barrel control device 6 is also connected to the control computer 2.

Figure 2 shows a schematic cross-sectional view through a shell launcher device, which is annotated in general by the reference symbol 11. The shell launcher device 11 has a firing barrel 7 which is open at both ends. In this case, the firing barrel 7 is produced from a non-ferromagnetic material. On its wall, the firing barrel 7 has four ferromagnetic rings 8a-8d which are separated from one another axially. The reference symbol 9 denotes a shell which is provided with a warhead 10. The warhead 10 has the time fuze 4. The warhead 10 furthermore has an interface (not shown here) to which at least one Hall sensor 12 is connected. In this case, the Hall sensor 12 is fitted to a fin assembly 13 on the shell 9. A tubular body 14 with apertures connects the fin assembly 13 to the warhead 10. A propellant charge, which is provided in the area of the tubular body 14, is not illustrated in any more detail here.

Figure 3 shows a schematic section view through the Hall sensor 12 and through a section of the firing barrel 7. In this case, the Hall sensor 12 has a first sensor element 15a and a second sensor element 15b, which are connected to an evaluation component 16 in the form of a semiconductor. The reference symbol 17 denotes a permanent magnet. The Hall sensor 12 illustrated here is a differential sensor in which the sensor elements 15a and 15b are used for subtraction.

The apparatus operates as follows: As soon as the Doppler radar 1 detects an approaching projectile, the control computer 2 calculates the velocity of this projectile, and its flight path. The control computer 2 furthermore calculates an earliest possible engagement time with a shell 9 to be fired. This is used to determine a first initiating time for the warhead 10 in the shell 9. The first initiating time is transmitted via the cable connection 3 to the time fuze 4. The firing barrel 7 is aimed in the direction of the approaching projectile by means of the firing barrel control device 6. The shell 9 is then fired. In this case, a trigger signal is transmitted to the clock for the time fuze 4, literally at the same time, by the control computer 2, thus starting the clock 4. The trigger signal is used as a common time base for the further time measurements and calculations.

After the shell 9 has been fired, the Hall sensor 12 moves past the ferromagnetic rings 8a-8d. Whenever the Hall sensor 12 passes a ferromagnetic ring 8a, 8b, 8c or 8d, a signal is produced. A first signal on passing the first ferromagnetic ring 8a is expediently used for calibration. A count of the clock is detected whenever a signal is produced. The detected counts or time differences, on passing the ferromagnetic rings 8a-8d, are transmitted to the control computer 2. An initial velocity of the shell 9 is calculated from two, and preferably three, measured time differences. In this case, the time on passing the second ferromagnetic ring 8b is used as the T4-time. The control computer 2 uses the initial velocity and the T4-time and preferably also the values relating to the approaching projectile that has been updated in the meantime, to calculate a second initiating time for the warhead 10. The second initiating time is more exact than the first initiating time, because the initial velocity and the T4-time have been taken into account. The second initiating time is transmitted via the cable connection 3 to the time fuze 4. The programmable clock for the time fuze 4 is set to the second initiating time.

For the purposes of the present invention, it has been found to be advantageous for the firing barrel 7 to be open at its rear end or to be closed only by a bursting membrane, which can be broken open easily when the shell 9 is fired. This ensures that the propellants released backwards from the propellant charge of the shell 9 do not transmit the axial forces, or transmit only very minor axial forces, to the firing barrel 7. The firing barrel 7 therefore remains (absolutely) at rest, or stationary with respect to the surrounding area and with respect to the projectile to be defended against. This in turn has the advantage that there is no additional relative movement between the firing barrel 7 and the shell 9 (that is to say there is no movement beyond the absolute firing movement of the shell 9), which could otherwise corrupt the measurement of the actual, absolute launch velocity of the shell from the firing barrel 7.

The proposed method makes it possible to achieve a particularly high delivery accuracy. A vehicle equipped with the proposed active system can effectively be protected against bombardment with shells, anti-tank missiles and the like.

List of reference symbols 1 Doppler radar Control computer 3 Cable connection Time fuze Measurement device 6 Firing barrel control device 7 Firing barrel 8a, 8b, 8c, 8d Ferromagnetic ring 9 Shell Warhead 11 Shell launcher device 12 Hall sensor 13 Fin assembly 14 Tubular body 15a, 15b Sensor element 16 Evaluation component 17 Magnet

Claims

Patent Claims Method for initiating a warhead (10) of a shell (9), having the following steps: detection of a moving target; calculation of a first initiating time and setting a time fuze (4), which is provided in the warhead (10), to the first initiating time; firing of the shell (9) in the direction of the target and activation of the time fuze (4); measurement of a time interval (T4-time) between activation of the time fuze and a time at which the shell (9) leaves a firing barrel (7), and of at least one further time value for determination of an initial velocity of the shell (9) on leaving the firing barrel (7); calculation of a second initiating time using the measured time interval (T4-time) as well as the determined initial velocity; and replacement of the first initiating time by the second initiating time.
Method according to Claim 1 , wherein the target is detected by means of a radar device (1), preferably a Doppler radar device, and/or an IR device.
Method according to one of the preceding claims, wherein a clock which is contained in the time fuze (4) is switched on by a trigger signal which is produced by a control computer (2).
Method according to one of the preceding claims, wherein a plurality of markings (8a, 8b, 8c, 8d), which are separated from one another in the axial direction, are provided on the firing barrel (7) and the shell (9) has at least one sensor (12) which produces a signal when a predetermined distance from the respective marking (8a, 8b, 8c, 8d) is undershot.
Method according to one of the preceding claims, wherein the markings (8a, 8b, 8c, 8d) are preferably annular ferromagnetic elements, and the sensor (12) is a Hall sensor.
Method according to one of the preceding claims, wherein the clock in each case measures time differences between the time when the trigger signal is produced and further times when the sensor signals are produced.
Method according to one of the preceding claims, wherein the first and second initiating times are transmitted via a cable (3) which connects the time fuze (4) to the control computer (2).
Vehicle having a detection device (1) for detection of a moving target, a shell launcher device (1 1) with a measurement device (5) for measurement of a time interval (T4-time) between activation of the time fuze and a time at which the shell (9) leaves the firing barrel (7), and of at least one further time value for determination of an initial velocity of a shell (9) when it leaves the firing barrel (7), a control computer (2) which is connected to the detection device (1) and to the shell launcher device (11), for calculation of a first initiating time and a second initiating time as a function of the measured time interval (T4-time) and a specific initial velocity, and a data transmission path (3) for transmission of the first and second initiating times from the control computer (2) to the time fuze (4).
9. Vehicle according to Claim 8, wherein the detection device (1) is a radar device, preferably a Doppler radar device, and/or an IR device.
Vehicle according to Claim 8 or 9, wherein the measurement device (5) has a plurality of markings (8a, 8b, 8c, 8d), which are provided at a distance from one another in the axial direction on the firing barrel (7), and at least one sensor (12), which is provided on the shell (9) and produces a signal when a predetermined distance from the marking (8a, 8b, 8c, 8d) is undershot.
Vehicle according to one of Claims 8 to 10, wherein the markings (8a, 8b, 8c, 8d) are preferably annular, ferromagnetic elements, and the sensor (12) is a Hall sensor.
12. Vehicle according to one of Claims 8 to 1 1 , wherein the time fuze (4) has a clock for measurement of time differences in each case between the production of the trigger signal and the occurrence of the signals produced by the sensor (12).
13. Vehicle according to one of Claims 8 to 12, wherein the firing barrel (7) is open at both ends.
14. Vehicle according to one of Claims 8 to 13, wherein the data transmission path comprises a cable (3).
15. Method according to any one of claims 1-7 as described in the specification.
16. Method according to any one of claims 1-7 as illustrated in any of the drawings.
17. Vehicle according to any one of claims 8-14 as described in the specification.
18. Vehicle according to any one of claims 8-14 as illustrated in any of the drawings. For the Applicant