GB2070739A - A projectile having a thermo- electrical generator - Google Patents

Abstract

There is described a projectile having a thermo-electrical generator for the operation of a circuit arrangement in the projectile, the operating voltage of said generator being acquired by virtue of a temperature gradient or gradients at or in the projectile which occur in operationally-caused manner as a result of the projectile acceleration in a weapon tube and/or of the projectile deceleration in free flight. In this respect there can result an intrinsically-safe projectile when the generator is formed or provided over a projectile region over which there occurs substantially by virtue of free-flight factors after emergence from the weapon tube temperature gradients of such order of magnitude and direction as to supply by way of the generator, according to amplitude and polarity, possibly by way of a voltage multiplier, the necessary voltage for the feeding of the circuit arrangement. Such regions are more especially (i) a projectile tip, (ii) a transitional region from the tip to cylindrical projectile walling, (iii) (in the case of a projectile having a spike tip) a region directly in front of a shoulder of the projectile, and (iv) a projectile region behind a guide ring of the projectile. In the latter case, the heat impingement of the generator by the propellant gases in the weapon tube can also be utilised to feed the circuit arrangement prior to passage of the projectile through a dead region immediately in front of the weapon tube muzzle and for acquiring tube-emergence sensing information. In the embodiment shown, a projectile 1 has a thermo- electrical generator 9 which is arranged in the tip 10 and by which is operable a circuit arrangement 8. 12 is a heat sink. <IMAGE>

Description

SPECIFICATION A projectile having a thermo-electrical generator The invention relates to a projectile of that kind having a thermo-electrical generator for the operation of a circuit arrangement in the projectile.

Such a projectile is known from German Offenlegungsschrift 24 34 700 as an air defence projectile, in which, after launching from a weapon tube, a pyrotechnical charge which is arranged in the rear part of the projectile is ignited, in order to act as a radiation source for the radiation of a target tracking beam. Arranged between this pyrotechnical charge, as source of heat, and the explosive-charge payload of the projectile as heat sink, is a thermo-electrical generator which consists of thermocouple elements connected together in series connection and which, by virtue of the temperature gradient between the ignited pyrotechnical charge and the still not ignited explosive charge, emits a thermo-voltage for the operation of a circuit arrangement for the evaluation of the bearing beam information for the ignition triggering.

What is disadvantageous in the case of this arrangement in the projectile for the preparation of the electrical energy for the operation of the circuit arrangement is more especially the fact that there has to be provided, in the projectile, a heat source of its own which is to be ignited expressly after the launching and which, with predetermined projectile dimensions, considerably reduces the space available for the payload, in which respect additional expenditure for ensuring an ignition of this heat source only after leaving the weapon tube is necessary, in order to make the projectile intrinsically safe.This solution is therefore justified only in those special cases where in any case there has to be present for the operation of the projectile a heat source to be set in operation after the launching but prior to the detonation, which heat source can then at the same time be utilised for energy acquisition for the operation of the circuit arrangement, insofar as the circuit arrangement does not previously already have to be ready for operation.

In cases where such special conditions are not present, it is known to provide, in the projectile, a battery as an energy source for the circuit arrangement. It is disadvantageous that batteries have a very large weight in relation to their electrical output, in other words reduce the payload of the projectile with the given iimiting conditions, and that in addition to this a peak current, available for triggering the detonation, is, in the case of a battery. by virtue of the high internal resistance of the battery, comparatively slight.

Moreover, projectiles surviving long store time (corresponding to require.ments for the period in which stored projectiles remain operable) without impermissible self-discharge are very expensive, and additional expenditure on apparatus and financial expenditure has to be incurred for the intrinsic safety, in other words for the release of the battery energy to the circuit arrangement only after emergence of the projectile from the weapon tube.

Furthermore, it is known to equip projectiles with piezoelectric generators which are activated by virtue of the dynamic pressure in front of the projectile in free flight, in other words after leaving the weapon tube. The energy thereby available is, however, as a rule even with intermediate storage of the energy, supplied by the piezoelectric elements, in capacitors, not sufficient for the feeding of an electronic circuit arrangement, only for the triggering of an electrical gap fuze to initiate the detonation.

In contrast thereto, the problem underlying the invention is to design a projectile of the kind referred to in the first paragraph hereof in such a way that it can yield the necessary energy for the operation of a complex electronic circuit arrangement during the movement in free flight between leaving the weapon tube and triggering of the detonation, and possibly also in the weapon tube, with comparatively slight production-technology expenditure but high operational safety.

According to the invention, there is provided a projectile having a thermo-electrical generator for the operation of a circuit arrangement in the projectile, characterised in that the generator is formed or arranged over a region or regions over which occur a temperature gradient or gradients caused by operational acceleration. (The said acceleration can be an increasing of speed (positive acceleration), or a decreasing of speed (negative acceleration) (deceleration).

Thus there is not necessitated the provision of the projectile with a heat source that is provided expressly and that is to be ignited at a definite point in time; on the contrary, there can be utilised a heat gradient or gradients from the projectile environment into the projectile which occur as a result of braking of the free flight in the surrounding air and possibly also a heat gradient or gradients occuring upon launching of the projectile, in other words conditions arising from negative and positive acceleration connected with the projectile movement.

The generator may be formed or arranged over a region or regions over which occur a temperature gradient or gradients substantially caused by free-flight friction deceleration, such arrangement being based on the recognition that, in the case of projectiles flying for a fairly long time, what would be most suitable for the energy supply of the circuit arrangement would be a thermo-electrical generator which is so incorporated into the projectile that there is utilised a heat gradient or gradients occurring, over the generator, in free flight (in other words between leaving the weapon tube and triggering of the detonation) and caused by self-friction, in other words caused by deceleration and thus without an additional heat source.Special additional measures to ensure intrinsic safety can be left out of consideration, since the air friction heat becomes effective only outside the weapon tube, for the projectile, to thereby energise the generator.

In this respect, in accordance with advantageous embodiments constructed in accordance with the invention, alternatively or cumulatively there may be utilised various typical friction heating regions on the projectile in connection with the design of the generator.

Comparatively simple and operationally noncritical additional means in the projectile in the form of heat sinks or heat stores to ensure a favourable heat gradient during the freeflight time may, in this respect, be expedient.

Such preferred regions for utilisation in connection with the design of the thermo-electrical generator for (intrinsically-safe) electrical feeding of an electronic circuit arrangement in the projectile during the free flight of the projectile are more especially on the one hand a transition from a projectile tip to an approximately cylindrical part of the projectile, or, in the case of a projectile design having a spike tip, the tip region situated directly in front of a shoulder of the projectile, and on the other hand a region behind a projectile guide ring, in the vicinity of a crimping groove for the fastening of a propellant case or cartridge case.

In the first-mentioned case, there occurs, directly after leaving the weapon tube, by virtue of the braking air friction during the entire free flight, a high heating which rises, depending on the geometry of the projectile, up to 600cm or even still higher. To ensure the temperature gradient, a substance which has a heat capacity in proportion to the flight time can be provided as a heat sink in the interior of the projectile; whilst impermissible heating of the hot sides of thermo-element or Peliter material pairings of the generator is preventable by a surrounding thermal screening.In the case of the utilisation of shoulder heating in the case of a projectile design having a spike tip, the temperature gradient over the longitudinal extent of the spike can be utilised for the energising of the generator, without an additional formation of a heat sink being needed. In the case of the secondmentioned alternative, the fact of a temperature gradient reversal at the projectile generator when the projectile is leaving the weapon tube is utilised, since the projectile part situated behind the guide ring is acted upon in the barrel by the hot powder fumes of the propellant charge, but after leaving the weapon tube is cooled by turbulences behind the guide ring.In the case of this latter variant constructed in accordance with the invention it is thus merely necessary to store away the powder fume energy, prior to leaving the weapon tube, in the rearward region of the interior of the projectile to such an extent that in the region behind the guide ring, in free flight, a temperature gradient from the inside outwardly becomes effective.

In the case of these variants there thereby results, by virtue of the generator energisation factors, on the one hand prior to, and on the other hand after leaving, the tube, without additional auxiliary measures, an intrinsicallysafe projectile which is not subject to any ageing with regard to the generator and which after traversing a certain dead zone in front of the weapon tube muzzle can become live by the generator then feeding the ignition circuit arrangement.

For special projectiles which already have to be live after, and already have to be able to make the ignition energy available after, an inner combat zone measuring between about 50 and 100 m, the free-flight dead-zone in front of the weapon tube muzzle is however, even in the case of very high exit speeds, in the circumstances too large. In a further embodiment constructed in accordance with the invention, for a projectile requiring to be effective in such regions there is utilised, for the thermo-electric feeding of the circuit arrangement, the heating, occurring in the course of the acceleration upon launching in the weapon tube, of the projectile rear end by the powder gases upon and after separation of the projectile from its cartridge or propellant case.

In this case, the generator already begins to operate in the weapon tube, in order to be able to initiate the ignition of the projectile at a short distance in front of the tube muzzle.

The thermo-electrical energy acquisition itself can then no longer be utilised for the intrinsically-safe operation of the projectile. On the contrary, recourse can be had to provide co!n- ventional mechanical safety means based for example on the guide function of the weapon tube. These safety means can be supplemented by the function of the circuit arrangement fed from the thermo-generator, by using a discriminator which is effective by virtue of the fact of the large voltage gradient which occurs upon emergence of the projectile from the tube muzzle, in other words in an operating phase of the projectile in which the rear of the projectile is precisely no longer heated by powder fumes but is for example cooled by air swirls. The voltage jump or polarity jump thereby occurring at the output terminals of the thermogenerator can be utilised as a sensor signal for the detection, in the circuit arrangement incorporated into the projectile, of the effected launching, in order to prepare, by way of the circuit arrangement, fed already from the thermo-electrical generator during the running time of the projectile in the tube, an ignition directly in front of the tube muzzle and thus already in the very short range.

The generator can advantageously be of ring-shaped or disc-shaped form or of hollowcylindrical or cylindrical form, whereby it can be produced separately and then be able to be inserted, in the course of the projectile production or the projectile charging, into the projectile or be installed between two projectile parts.

In the accompanying drawings, which show, by way of example, and in simplified manner, preferred exemplary embodiments constructed in accordance with the invention: Figure 1 shows in side view, partially cut away, a projectile, intended for fairly long free-flight distances, having an attached case prior to launching, and with there being a thermo-electrical generator in the tip of the projectile; Figure 2 shows in basic representation the feeding, from a thermo-electrical generator having thermoelements, of a circuit part of a circuit arrangement of a projectile constructed in accordance with Fig. 1; Figure 3 shows, in a modification of the construction in accordance with Fig. 1, the form of the generator in a region of the transition from a tip of the projectile to a cylindrical part of the projectile;; Figure 4 shows the generator arrangement in accordance with Fig. 3 in a sectional view on the line IV-IV, Fig. 3; Figure 5 shows a generator arrangement in the rearward part of a projectile behind a guide ring of the projectile; Figure 6 shows a modified generator arrangement in the case of a projectile having a spike tip; Figure 7 shows a construction, influenced by the installation factors in the case of the construction shown in Fig. 5, having a generator of a projectile which has to be ready for ignition within a so-called inner combat zone; Figure 8 is a section on the line VIII-VIII, Fig. 7 showing an arrangement of thermoelement pairs; and Figure 9 shows, with respect to a modification of the factors in accordance with Fig. 2, a circuit arrangement, which also undertakes safety functions, for a thermogenerator, in accordance with Fig. 7 and Fig. 8, which feeds the circuit arrangement during the projectile launching in the weapon tube.

Referring to the drawings, Fig. 1 shows in side view, partially broken away, a projectile 1 with a case 2 for the reception of a cartridge propellant charge 3. The projectile 1 is, in the rearward region of a cylinder jacket 4 thereof, surrounded by a guide ring 5 which, by virtue of co-operation with rifling in an inner jacket surface of a weapon tube (not shown in the drawing), provides the projectile 1, upon launching, with the projectile twist necessary for directional stability.

Formed behind the guide ring 5, in the cylinder jacket 4 of the projectile 1, is at least one peripherally-encircling crimping groove 6 which serves for the form-locking and forcelocking fastening of the front region of the case 2 on the projectile when, as in the instance of example shown, there is concerned ammunition that is to be introduced in one piece into the weapon tube; in the other instance, the ammunition is formed in two parts consisting of projectile 1 and case 2 without the shown mutual fastening.

The interior of the projectile 1 contains in the main a payload chamber 7, more especially for the reception of ignition and explosive material. Accommodated in the front, conically-tapering region of the projectile 1 is a circuit arrangement 8 which serves more especially for the preparation or conversion of electrical energy for the processing of sensors for determining the instant of ignition and initiation of ignition. For the acquisition of this electrical energy a thermal generator 9 is arranged in the region of the projectile tip 1 0.

Arranged in front of the generator 9 there can be a thermally-resistant, good heat-conductive reinforcing material 11, in which for example sensors for initiation of the ignition can also be arranged. Arranged behind the generator 9, related to the longitudinal axis 22 and flight direction of the projectile 1, is a heat sink 1 2 of high heat capacity. It can in this respect be for example a container made of poorly heat-conductive material which is filled with a fluid, for example distilled water.

After launching of the projectile 1, when this has thereby separated from the case 2 and has left the weapon tube, there arises in front of the projectile tip 10, by virtue of the air resistance in the free flight of the projectile 1, a heat accumulation which is transmitted by way of the reinforcement material 11 to the hot side 1 3 (see Figure 2) of the generator 9, the cold side 14 of which generator butts against the heat sink 1 2. The generator 9 itself consists in the main of a grouted mass of heat-resistant material 1 5 which as a result of poor heat conduction maintains the temperature gradient in the best possible manner over the generator (for example commerciallyavailable hardenable ceramic casting material), into which are embedded element pairs 16, for the conversion, in accordance with the Peltier or Seebek effect, of the temperature gradient (between the hot and the cold side 13/14) into an electrical voltage. The generator element pairs 1 6 are (at least partially, as shown in Fig. 2) connected in series, in order to be able to tap the thermo-voltage between two output terminals 1 7. This thermo-voltage can operate the components of the electrical circuit arrangement 8 with interpolation of a voltage multiplier 47 which oscillates at small excitation voltages, or else be imparted directly to circuit parts 18.In order to be able to use, in the case of these circuit parts, for example connected-up operational amplifiers, small operating voltages, it is advantageous to provide the series circuit of the element pairs 1 6 with a central tap 19, which is connected to a reference potentialconnection of the circuit parts 18, which require a bipolar voltage supply.

The amount of heat passing from the tip 10 or from the reinforcement material 11 through the generator 9 is picked up by the heat sink 1 2, so that during the operating period of this thermal generator 9 the cold side 1 4 thereof is not markedly heated, in other words the temperature gradient for the production of the thermo-voltage is substantially maintained.It is particularly advantageous to form the element pairs 1 6 in the grouted material 1 5 of the generator 9 as Peltier elements, since these have a particularly high heat-transfer resistance and thereby delay the heating of the heat sink 1 2 serving as thermal counterweight, which makes possible the space-saving incorporation of a spatially-small heat sink 1 2. Moreover, Peltier elements themselves represent spatially small element pairs 16, which at a moderate temperature difference of the order of magnitude of about 150 Celsius make achievable a no-load voltage of the order of magnitude of 0.5 volts.A critical over-heating of the Peltier elements as the element pairs 1 6 is constructionally easily precludable, in that the reinforcement material 11 in the tip 1 0 of the projectile is selected accordingly and, in addition to this, in that the element pairs 1 6 in the generator 9 do not extend as far as into the vicinity of the wall region of the projectile 1, or in that there the generator 9 is surrounded by a thermal shielding ring 21.The element pairs 16 can be arranged spirally or circularly in the grouted material 1 5. If, to increase the available output power of the generator 9, individual series circuits are to be connected in parallel in groups, it is, in the interests of operationally-reliable electrical connections one with another, more advantageous to group also the element pairs 1 6 accordingly.

If the circuit parts 18 in accordance with the representation in Fig. 2 are not fed directly from the generator 9, but by way of a voltage multiplier 47, then there can be used relatively few element pairs 16, if the multiplier 47 is realised with semiconductor structural elements on a silicon base, because this, upon the exceeding of a defined low generator output voltage (typically 0.6 volts), begins to oscillate almost abruptly, and then supplies the supply voltage for the circuit parts 1 5.

In contrast to the exemplary embodiment in accordance with Fig. 1, in the exemplary embodiment in accordance with Fig. 3 the thermal generator 9' is, with respect to its temperature gradient, orientated not parallel, but transversely, to the flight direction and thus to the longitudinal axis 22 of the projectile 1. The element pairs 1 6 are here (see Fig.

4) embedded radially in star-shaped manner, into the grouted material 1 5 which, as a generator ring 23, surrounds the heat sink 1 2 concentrically, which heat sink can again be a container, preferably made of electrically-insulating material, with a filling of high heat capacity, for example with a liquid filling. The cold connection points 14 of the elements pairs 1 6 communicate thermally with the heat sink 12; the hot connection points 1 3 thereof lie, electrically mutually insulated, directly under projectile walling 24, or they project, for better thermal connection to a surrounding" envelope of air, into recesses or clearances 25 in the projectile walling 24, as is shown by way of example in Fig. 4.

The annular generator 9' in accordance with Figs. 3 and 4 can have star-shaped arrangements of element pairs 1 6 in several mutually parallel planes transversely to the projectile longitudinal axis 22. This annular generator 9' is incorporated, in the projectile 1, in the transitional region 26 between the projectile tip 10 and the projectile cylinder jacket 4, consequently in a region in which, in the case of free flight after launching of the projectile 1 from a weapon tube, a heat accumulation occurs by virtue of the flow factors and in which there thereby occurs the greatest heating relative to the approximately constant temperature of the heat sink 1 2. This temperature in the transitional region 26 reaches about 600"C. The thermal properties of the grouted material 1 5 of the generator 9' as well as of the heat sink 1 2 are to take into account the fact that the flight time of such a projectile 1 amounts to about 6 to 8 seconds, within which the temperature gradient from the hot side 1 3 to the cold side 14 of the generator 9 may not be substantially reduced, in order, even at the end of the flight time and if possible without-the requirement of having to store electrical energy intermediately, to have still available the necessary oprerating voltage for the circuit arrangement 8, either directly as a terminal voltage of the thermal generator 9', or else by way of the intermediately-connected voltage multiplier 47.

In the exemplary embodiment shown in Figs. 3 and 4, the generator 9' is penetrated by a detonator 27, which on the one hand is connected to ignition circuit parts of the circuit arrangement 8 and on the other hand extends into the payload chamber 7, in order at the appropriate time to ignite the charge present there. Provided in the tip 10, in the case of the exemplary embodiment in accordance with Fig. 3, in front of the circuit arrangement 8 is additionally an impact trig ger device 28, which communicates function ally, by way of parts of the circuit arrange ment 8, with the detonator 27; instead of this, or in addition thereto, there can be arranged, in this front region, also sensors, for the function of projectile 1, which are not accommodated in the region of the circuit arrangement 8.

The generator construction in accordance with Fig. 4 with an arrangement in accor dance with Fig. 3 (or in accordance with Fig.

5 hereinafter explained) is particularly suitable for conventional thermo-element material pair ings, which indeed have a lesser thermo 'electrical sensitivity than Peltier elements, but which on the other hand are operable at a higher temperature; thus protective measures against thermal destruction of the generator 9 are superfluous; on the contrary, the maxi mum occurring frictional heat in the ambiency of the projectile 1 can be utilised for the thermo-electrical energy production directly and by means of cheap materials.

The exemplary embodiment in accordance with Fig. 5 has a generator 9" having a ring 23', similar to the generator 9' having a ring 23 as is described in connection with Fig. 4.

In Fig. 5, the generator 9" is arranged in the region of the rearward end of the projectile 1, for example in the region of the crimping groove 6 and in any event behind the projec tile guide ring 5. The generator ring 23' now, however, surrounds not a heat sink 12, but a heat store 29, for example a block of fireclay like material. In the case of this embodiment, there is utilised for the thermal voltage prod uction not the frictional heat of the surround ing air at the projectile walling 24, but the heat energy, of the propellant gases, which is transmitted, in the course of the launching of the projectile 1 from the weapon tube, from the cartridge propellant charge 3 (see Fig. 3) into the heat store 29.Said propellant gases release their heat energy in the weapon tube behind the guide ring 5 of the projectile 1 lifting off from the case 2 (see Fig. 1).

In contrast to the conditions in accordance with Fig. 4, in the case of the generator ring .23' in accordance with Fig. 5 the cold sides 1 4 of the element pairs 1 6 lie outwardly, in other words at the periphery of the cylinder jacket 4 beyond the guide ring 5; whilst the hot sides thereof (not shown in Fig. 5) com municate thermally with the heat store 29. So iong as the projectile 1 is still being moved forward in the weapon tube, the hot propel lant gases act directly on the outer periphery of the generator ring 23', but on the other hand only act on the inner conection points of the elements pairs by way of the intermedi ately-connected heat store 29.During this launching interval the external connection points 1 4 of the element pairs are thus ex posed to a equally-great or even greater heating than the internal ones; this means that there is at the output terminals 1 7 of the thermal generator 9" during the launching still no thermo-voltage, or else a thermo-voltage having a polarity which is reversed in relation to the later operating factors.In any event, when in the case of the circuit parts 1 8 or possibly in the case of the advance-connected voltage multiplier 47, there are structural elements having a poled operating behavious (expressed in Fig. 2 by advance-connected operating-voltage crystal diodes 30 which are shown in broken lines), there still then does not ensue an activation in the critical interval of time in which the projectile is moving forward through the weapon tube.

After leaving the weapon tube, on the other hand, in other words in free flight of the projectile 1, there occur, behind the guide ring 5, air swirls which lead to a cooling of the region, situated there, of the cylinder jacket 4 and thus also of the cold side 14 of the generator 9". On the other hand, the heat store 29 heated in the tube now gives off its heat to the internal hot connection points of the element pairs, and there now occurs (in contrast to the conditions in accordance with Fig. 3) a temperature gradient from within outwardly; that is to say there is at the output connections of the generator 9" a thermovoltage having a polarity in accordance with the conductive polarity of the crystal diodes 30 (see Fig. 2).Since, at the rear 31 of the projectile 1 there prevails in free flight practically a vacuum, there occurs here, during the short operating time of the generator 9" (namely during the free flight-time of the projectile 1 up to detonation), practically no heat loss from the heat store 29.

For rapid introduction of the heat of the propellant gases into the heat store 29 with simultaneous ensuring of a heat profile, desirable with regard to the geometry of the element pairs, in the heat store 29, it can be advantageous, as is taken into account by way of example in the embodiment shown in Fig.

5, to insert heat-conducting bodies 32 in the form of rods and/or sheets, possibly with a staggered extent of depth, into the heat store 29, the free ends of which bodies 32, which may even be ends protruding from the projectile rear 31, are acted upon directly by the propellant-gas heat and makes possible a more aimed and faster heat introduction into the region of the generator ring 23' than through the material of the heat store 29 itself.

More especially in the case of the generator 9, 9' or 9" having the form of a ring 23 or 23' respectively, it is expedient to produce this as an independent component part which is inserted, in the course of the completion of the projectile 1, into the interior thereof or, in the case of a projectile 1 of multi-part construction, is introduced by screwing or other force-locking and/or form locking bond between the projectile parts.

In a modified embodiment (not shown) in which the thermo-electrical generator is in a rear portion of the projectile, the generator has element pairs orientated longitudinally of the projectile axis and is embedded between a thermally-insulating projectile connection part and a heat store, a region whereof which is averted from the generator faces towards a propellant case. The heat store may be provided with heat-conducting bodies similar to the bodies 32 shown in Fig. 5.

There is shown diagrammatically in simplified manner in Fig. 6 a modified generator construction in the case of a projectile design with a pronounced shoulder 33 behind a spike tip 34. Here there is required neither special measures for the formation of a heat sink, nor the provision of a heat store; this is because, by virtue of locally very concentrated extremely high heating of the shoulder 33 itself and of the directly adjoining end of the spike tip 34, there occurs in the free flight of the projectile 1, in the longitudinal direction of the spike tip 34, a temperature gradient which is directly adequate for the energisation of the generator 9"' Provided here for the voltage production is a generator winding 35, namely a banderole made from commerciallyavailable thermo-elements in foil form, the hot sides 1 3 of which are orientated towards the shoulder 33. In this respect, this element foil 36 is, as taken into account in the drawing, advantageously inserted into a groove 37 in the outer walling of the spike tip 34, in order if possible not to affect the flow-technology behaviour of the projectile 1.This winding design having a thermo-element arrangement in foil form makes possible the accomodation of element pairings in a very great number in a small space, in other words the acquisition of a high generator no-load voltage.

More especially the exemplary embodiments in accordance with Fig. 1 to Fig. 4 and Fig. 6, but also the exemplary embodiment in accordance with Fig. 5, are suitable for projectiles having a comparatively great tactical range amounting to up to several 100 metres, and accordingly with a free-flight time, after leaving the weapon tube, of the order of magnitude of 1.5 seconds and more. The described generator construction and installation is, all the more so in accordance with Fig.

1 to Fig. 4 and Fig. 6, optimally suitable for long-time supply, in other words if a dead zone, limited as far as possible, between leaving the weapon tube and ignition preparedness, is not a matter of importance. On the other hand, there are fast-flying projectiles which are intended for the so-called inner combat zone and which for example after only 0.1 seconds free-flight time or within a range of 50... 1 00 m have to hold ready the ignition energy for a detonation.

For such modified instances of use it is expedient to modify the utilisation of a generator similar to that in accordance with Fig. 5 in such a way that (whilst retaining the conventional for example mechanical safety measures during the advance of the projectile through the weapon tube) the heat impingement of the thermo-generator in the weapon tube by the hot propellant gases of the cartridge is already utilised for the energy supply of the circuit arrangement contained in the projectile, in other words the occurrence of a specific heat gradient at the projectile during free flight after leaving the tube mouth is not first awaited for the activation of the circuit feed from the generator.

A preferred exemplary embodiment is shown, referring back to the representation, in accordance with Fig. 5 taking into account Fig. 1, in Fig. 7. The thermal generator 9"" is, orientated parallel to the longitudinal axis 22 of the projectile, arranged in the rearward region of the projectile 1 approximately between the guide ring 5 thereof and its rear 31 facing the cartridge propellant charge 5 (see Fig. 1). Provided against direct destructive action of the hot propellant-charge powder fumes during the firing of the projectile 1 in the weapon tube (not shown in the drawing) is, behind the hot side 1 3 of the thermoelement pairs 16, a thermal protective layer 38 made of heat-resistant, and at the same time electrically-insulating, material.The cold sides 14 of the thermo-element pairs 1 6 are orientated towards the payload chamber 7 of the projectile 1 and butt against a heat sink 12, as which there can be utilised a metallic mass of a mechanical safety device provided anyway in the case of-such a projectile 1 (for example a clockwork-mechanism plate, or a separating plate, which can be swung out of an ignition effect chain, between a detonator and a transfer charge; not shown in the drawing).

For a good space utilisation in the interests of high thermo-electrical efficiency of the generator 9"", the thermo-element pairs 1 6 are, as shown in Fig. 8 in rear view, advantageously grouped spirally into a cylinder, with there being cast in the intermediate spaces commercially-available temperature-resistant ceramic casting material as form-keeping grouted material 1 5 (for example KAGER aluminium oxide ceramic material), which then hardens whilst holding the thermo-element pairs 1 6. Instead of this spiral generator 9"" having individual element pairs 16, however, there can be used an element foil 36 introduced, along with interpolation of grouted material 1 5 (as in Fig. 8), or as a tight winding, into the rearward end of the projectile 1.

As already indicated in connection with Fig.

2, there occurs at the projectile rear 31 a sudden reduction of the temperature impinge ment when the hot combustion gases of the propellant charge 3 have pushed the projectile 1, along with axial separation from the propel lant-charge case 2, out of the weapon tube.

Fig. 9 is an example of how the correspond ing course of the generator output voltage can be utilised as sensor information for reporting the fact of the effected launching from the tube and thus (besides a tube-connected me chanical one) as an additional arming device.

For operation, or at least for operational readi ness, the circuit arrangement 8', before the projectile 1 emerges from the weapon tube, is, in accordance with Fig. 9, acted upon directly, or by way of a previously-connected voltage multiplier 47 in accordance with Fig.

2, by the thermo-voltage as operating voltage, which the generator 9"" supplies by virtue of activation by the hot propelling-powder gases.

Immediately after emergence of the projectile 1 from the weapon tube, the heat impinge ment at the projectile rear 31 (see Fig. 7), and thereby the output voltage supplied by the generator 9"", drops severely, which is trans mitted by way of a polarity discriminator 39 (for example in the form of a series connection consisting of differentiating means 40 and a diode 41 which is connected so as to pass the corresponding differentiation voltage impulse) as a control signal at a live input 42 of the already operationally-ready circuit arrange ment 8'.Connected subsequent to the live input 42 is the setting input 43 of a trigger circuit 44 which has been prepared as a result of operational readiness of the circuit arrange ment 8' and upon setting via the live input 42 transmits release information to an ignition device (not shown in more detail, for example an electronic or electro-mechanical device).

If by virtue of the thermal factors in the region of the rearward end of the projectile 1 after emergence from the weapon tube a reversal of the warm/cold impingement of the thermo-element pairs 16, and thus a polarity reversal of the output voltage of the generator 9"", occurs, it is expedient to undertake the ,feeding of the circuit arrangement 8' from the generator 9"" by way of a rectifier bridge 45, so that the feed polarity is maintained. A storage capacitor 46 connected subsequent to said bridge can advantageously be provided, in order to keep the operating voltage for the circuit arrangement 8' available in uninter rupted manner during the polarity reversal of the generator voltage, in other words during traversing of the generator dead region di rectly in front of the weapon tube opening.

If several generators 9 are formed at vari ous regions of the projectile 1, then the circuit arrangement 8' can be fed parallel from these, whereby it is already in operation dur ing the launching of the projectile 1 and after a very short muzzle dead region after that also during fairly long flight times.

Claims (11)

1. A projectile having a thermo-electrical generator for the operation of a circuit arrangement in the projectile, characterised in that the generator is formed or arranged over a region or regions over which occur a ternperature gradient or gradients caused by operational changing of speed.

2. A projectile as claimed in Claim 1, characterised in that the generator is formed or arranged over a region or regions over which occur a temperature gradient or gradients substantially caused by free-flight friction deceleration.

3. A projectile as claimed in Claim 2, characterised in that the generator is installed in a tip of the projectile.

4. A projectile as claimed in Claim 1, characterised in that generator element pairs connected together electrically are arranged in star-shaped manner in at least one plane which extends transversely to the longitudinal axis of the projectile.

5. A projectile as claimed in Claim 4, characterised in that the element pairs penetrate, in the region of a transition from a tip of the projectile to a cylinder jacket of the projectile, a hollow-cylinder walling made of thermally-insulating material which surrounds a heat sink.

6. A projectile as claimed in Claim 4, characterised in that the element pairs are arranged in a region behind a guide ring of the projectile and surround a heat store a free surface or surfaces of which face towards a connection region for a propellant case.

7. A projectile as claimed in Claim 1, characterised in that the generator is embedded between a thermally-insulating projectile connection part and a heat store, a region whereof which is averted from the generator faces towards a propellant case.

8. A projectile as claimed in Claim 6 or 7, characterised in that the heat store is provided with heat-conducting bodies.

9. A projectile as claimed in Claim 1 or 2, characterised in that generator element pairings which are connected together electrically are arranged in star-shaped manner in at least one cylinder jacket wall which is situated concentrically to the projectile longitudinal axis at a spike tip in front of a shoulder of the projectile.

10. A projectile as claimed in Claim 9, characterised in that the generator is a winding consisting of thermo-element pairings in foil form.

11. A projectile as claimed in Claim 1, characterised in that the generator is arranged with warm/cold thermoelement pairs thereof orientated parallel to the longitudinal axis of the projectile, and with a hot side situated in the projectile towards the projectile rear.

1 2. A projectile as claimed in Claim 11, characterised in that the generator is a wind- ing. arranged spirally into a cylinder, of element pairs.

1 3. A projectile as claimed in Claim 11 or 12, characterised in that a heat sink is associated with the cold sides of the element pairs in the projectile.

1 4. A projectile as claimed in Claim 13, characterised in that a metallic fuze safety device of the generator forms the heat sink.

1 5. A projectile as claimed in Claim 1, characterised in that the generator is arranged as a prefabricated component part in the interior of the projectile or between parts of the projectile.

1 6. A projectile as claimed in any one of the preceding claims, characterised in that connected subsequent to the generator is a polarity discriminator which is conducted to a live input of the circuit arrangement.

1 7. A projectile as claimed in any one of the preceding claims, characterised in that a voltage multiplier is connected subsequent to the generator.

1 8. A projectile having a thermo-electric generator, substantially as herein described with reference to Figs. 1 and 2, or Figs. 3 and 4, or Fig. 5, or Fig. 6, or Figs. 7 to 9, of the accompanying drawings.