US2880672A

US2880672A - Electric fuze

Info

Publication number: US2880672A
Application number: US439832A
Authority: US
Inventors: Menke Joseph Ferdinand; Doerpinghaus Ernst Hans
Original assignee: BRINRO Ltd SOC
Current assignee: BRINRO Ltd SOC; SOCIETY BRINRO Ltd
Priority date: 1953-06-29
Filing date: 1954-06-28
Publication date: 1959-04-07
Anticipated expiration: 1976-04-07
Also published as: GB752153A; FR1107717A; NL102231C; CH323354A; LU32256A1; BE528698A; NL234031A; NL188455B; DE1009981B

Description

April 7, 1959 J. F. MENKE ET'AL 'ELECTRIC Fuza:

3v Sheets-Sheet 1 VFiled June '28., 1954 W ATTDHNEY Filed June 2a, v1954 April?, 1.959 Emma UAL Y 2,880,672

ELECTRIC FUZE s shets-sneet 2 iV 31" EY Q, ATTUHNEY April?, 1959' v .1. F. MENK ETA'. 24,880,572

' v ELECTRIC` FUZE Filed June 28. '19521. 3 Sheets-Sheet 3 271 96 f Y i6 @J @Pig O l zal En(` v ATTUHNEY United States Patent O ELECTRIC FUZE Joseph Ferdinand Menke and Ernst Hans Doerpinghaus, Zurich, Switzerland, assignors to Society Brinro Limited, Tangiers, a society of Tangiers Application June 28, 1954, Serial No. 439,832 Claims priority, application Luxembourg June 29, 1953 Claims. (Cl. 102-70.2)

The present invention relates to projectiles, and in particular self-propelling projectiles such as rockets, and it is more especially but not exclusively concerned with such projectiles fitted with an electric fuze, that is to say a fuze the detonator of which is fired by an electric igniting device.

' Itis known to control the arming of the fuzeby means of two devices which are successively brought into play and the first of which keepsvthe second one inoperative for a time.l This first device serves to prevent the fuze from being armed before the projectile is launched and during the handling thereof, in particular during its transportation. The second device, which serves either to release the arming means proper or to prepare or start the operation thereof, is arranged in such manner that the fuze cannot be armed as long as the projectile has not travelled agiven distance from its launching apparatu'sI (which may be constituted by a gun, launching track, etc.), whereby explosion of the projectile inv or on the launching apparatus is impossible.

According to our invention, the iirst mentioned device is arranged to be rendered inoperative by an electric impulse which is automatically produced by contacts the operation of which (in particular the closing of which) is produced by a short initial movement of the projectile, when the projectile has not yet left its launching apparatus. j;

According to another feature of our invention,which isapplicable to the case where the fuze is an electric o ne supplied with current from voltage accumulating 'means carried by the projectile (and preferably constitutedby a condenser), said voltage accumulating means is charged from a source carried by the launching apparatus and through the circuit connection and contact means which serve 'to transmit the electrical impulse which is to render inoperative the first mentioned device. In particular, said circuit connection may be providedrbetween a source of direct current which serves to charge the voltage accumulating means and a source of alternating current serving to produce the above mentioned electrical impulse which renders the first device inoperative.

According to still another feature of our invention, the iirst device consists of an element capable ofl being sheared and constituted for instance by a wire, a small bar or a rod, this element being sheared by the explosion of a small primer. Preferred embodiments of our invention will be hereinafter described with reference to the accompanying drawings given merely by way of example andv in which:

Fig. l'diagrammatically shows the front part of a projectilefitted with an electrical fuze and arranged according to the present invention. II-iig. 2 shows the lay-out of the electrical fuze itself.

Fig. 3 is an axial section on the line IIl-III of Fig. 7, showing the switch means ofthe electric system of a pro jectileV according to the invention, the movable portion of' said switch means being in the first position. l

u response to the initial movement of projectile 1. i this purpose a Patented Apr. 7, 1959 Figs. 4 and 5 are part axial views with the movable element of the switch means respectively in the locked position and after it has been iirst released.

Fig. 6 is an axial section of the same switch means, on the line VI-VI of Fig. 7, the movable element of the switch means being in the position corresponding to the arming of the fuze.

Fig. 7 is a diagrammatic plan view of the above mentioned switch means.

Fig6. 8 is a sectional view on the line VIII-VIII of Fig.

Our invention will now be more particularly described as applied to a self-propelling missile, such as a rocket, iitted with an electric fuze, that is to say a fuze the detonator of which is red by an electric igniting device.

The projectile 1 itself, as diagrammatically illustrated on Fig. l, is of any suitable construction whatever, with the exception of its fuze and of the means for charging' and arming this fuze. The fuze includes voltage accu# mulating means constituted for instance by a condenser 2. In order to charge condenser 2 before the projectile is fired off, we provide a contact 3 insulated from the envelope of the projectile and which may be connected to a source of direct current 4. The charging circuit is closed through the conducting envelope of the projectile cooperating with a contact 5.

When the projectile is fired off, condenser 2 must be cut oi from contact 3, by means of a switch U which will be hereinafter described in detail, this condenser being then connected to several circuits of the fuze system which are to be fed from said condenser. This switch U includes, as diagrammatically shown by Fig. 1, a movable arm 7 pivoted about axis 6 and cooperating with a contact 8. This switch U cuts ofi, before the projectile is launched, any connection between condenser 2 and the circuits of the electric fuze which are to be fed from said condenser. Fig. 1 diagrammatically shows this position, where arm 7 is not in contact with stud 8 which is connected to said circuits. Arm 7 has an inertia such that it prevents rotation thereof toward contact 8 as long as the acceleration of theprojectile has not reached a value suihcient to overcome the inertia of the mass of said arm. Furthermore, before the projectile is launched, the movable arm 7 of the switch is kept, by a first holding device, in the position shown by Fig. 1. According to a particular feature of our invention, said holding device consists of a fusible wire 9 extending between arm 7 add a fixed point 10. This wire 9 is inserted in series between contact 3 and condenser 2.

In order to melt wire 9 and thus to render they rst locking device inoperative, a current impulse of sutiicient intensity is sent through the connection between condenser 2 and source 4. Furthermore, in order to be able to pass through condenser 2, this impulse is an alternating current impulse, whereas the condenser is charged, as already known, by means of direct current. The alternating current impulse passes through contacts which are closed by the initial displacement of the pro jectile when it is being ired off. For instance, contact 3 may be cut olf from the direct current source 4 by this initial displacement and it may be arranged to pass, for a short time, along another contact (not shown on the drawings) connected with a source of alternating current or with a condenser charged at a relatively high voltage.

However it seems particularly advantageous to insert, between the direct current source 4 and contact 3, the secondary 11 of a transformer the primary 12 of which is inserted in a circuit fed from an alternating current source 13. This last mentioned circuit includes a switch 14 which is normally open and which is to be closed in For push-rod 15, connected with the movable .arm of switch 14,is arranged to bear against a portion of the envelope of projectile 1 which is so shaped thatv `must be limited to a value such that the fusible wire v9 inserted in the charging Circuit .does not rneltrThiS een. be obtained by yinserting a resistance. not shown by 'the drawing, in one of the connections extending from source 4 tocondenser l2. Such a current limiting resist- .ance may be eonstituted. in the construction of Fig- 1, by the secondary 1 1 of the tranSfOrrner. It may also be constituted by the internal resistance of the direct Ycurrent source.

Qnce condenser 2 is charged, the projectile is ready Vto be launched. I f the projectile is launched, that is to -say if there` is no misre, the initial movement of the projectile closes switch 14, whereby an Valternating current impulse is supplied through transformer 12, 11 to ,the charging circuit connected to the condenser. This impulse melts wire 9, so that on the one hand the means .for holding the movable arm 7 of switch U in inoperative 1position is eliminated and on the other hand condenser `2 is ent olf from the eharsing Contact .3-

`I f there is a mistire, switch 1 4, does ynot close and condenser 2 then remains connected with the charging contacts 3 and 5. I t can then be discharged by means of switch 16 (Fig. l) through resistance 1 7. When this has been done, the projectile can be examined without danger, to lind the reason of the breakdown.

Fig. 2 shows the circuits to be fed from condenser 2 when switch arm 7, after having overcome its inertia vowing to the acceleration of the projectile,V shifts from `the position shown by this ligure to a position where it is applied on contact 8. Fig. 2 indicates by a dotted lines connection that arm 7 is coupled With a second switch arm 7a arranged to be applied on a contact 8a when arm 7 is applied against contact 8. As a consefquence of this movement (closing of switch 7a, 8a), the cathode of a gas tube 18 of the so-called thyratron kind, is heated,y the heating current being supplied from a battery element 19.

Among the circuits to be fed from condenser 2 after

switch

7, 8 has been closed, there is the charging circuit of a condenser 20 called the ignition condenser. This condenser 20 is inserted in a circuit including also thyra- .tron 18 and a device for firing the detonator, said device being for instance constituted by an electrically ignited primer 21.

Condenser 2 must also supply a negative bias voltage to the grid 22 of thyratron 18, whereby said thyratron vcuts off the passage of current through its circuit until the detonator is lired. Explosion of primer 2 1 is p roduced by the movement of a member 23 or by an auto destruction device which causes the. voltage of grid 242 to pass from a negative value to a positive value.

Member 23 is for instance inertia operated.

Still another circuit fed from condenser 2 is the charge circuit of a condenser 24 which serves to achieve autodestruetion of the projectile.

Resistances R1 and R2 belong to the charge circuit of ianitins ,Condenser .2.0 and serve lfor instance to sive the e. Constant. the. .entraine of Condenser 29 veine o bout .25 second (thisindication having no limitative ehnrneterl- Resistance R2. also acts, together- With another resistnnee. R3, as. a. voltage dvider. This resistance. R3, when 4 it is-not lshoi-t-circuited by member 23, supplies a negative bias to grid 22, as above mentioned.

The feed circuit of condenser 24 includes the charge resistance R4, which is calculated so that the time constant corresponding to the charge of condenser 24 is for instance of about 5-6 seconds (this indication having no limitative character).

In shunt with condenser 24, there is a glow lamp 25 and Va grid resistor R5 in series.

This f uze system works as follows:

As soon as

contacts

7, 8 and 7a, 8a are closed, ignition condenser 20 starts being charged and it is practically charged after 0.25 second approximately, so that after this delay, whichserves to prevent any possibility of explosion in the gun or the launching apparatus, the fuze is armed. Then, when member 23 is operated and the negative bias of grid 22 is eliminated, the ignition current can pass from condenser 20 to primer 21 and ignite it. If, on the contrary, the, projectile does not meet any target and therefore. if member 23 is not actu,- ated, condenser 24, after a delay of vfrom tive or six sec.- onds, is s uciently charged to supply glow tube 25 with its glow potential, and therefore in this caseto supply a positive voltage to the grid 2 2 of the thyratron. There- Afore condenser 20 discharges into primer 21 and the projectile is exploded.

According to a modcation which is not shown by lthe drawing, we further increase protection againstan accidental operation of the fuze by short-crcuiting theigni.- tion element 2 1 by means of a conductormounted in parallel `with said element and in which thereis interposed a switch which is opened at the same time Aas switches 7, 8 and 7a, 8a. are closed.

In the construction of switch U diasrammaticallyillnstrated by Figs. 1 and 2, the mechanical safetyvmeans for .normally ,holding `saidswitch in cut-off position consists of a fusible wire 9 which is melted by a current impulse.

According to a preferred embodiment of our invention an example of which is shown by Figs. 3 to. 8 said mechanical safety means is constituted by a locking member capable of beingshearecl and which is actually sheared by the explosion of a` smaller primer produced by an electric current impulse fed to said primer.

Advantageously, said primer is mounted similarly vto fusible wire 9, that is to say in the connection serving to charge condenser 2 so that explosion of said primer not .only renders said mechanical locking member inoperatine, but also cuts off condenser 2v from input contact 3. In the construction of Figs. 3 to 7, the switch includes .an .outer casing o r chamber 26 made of an electrically insu,- lating material. In the wall of this casing are .disposed three pairs. Of contacts, to wit,` in one axial plane- (that of Fig. 3.),f two pairs of contacts a, a1 and b, Yb1, located .above one. another, and in another axial Plane (that .of Fia- 6). at: right angles. t0. the. first mentioned. one.. .a third pair of contacts c, o1, In en -amber 26 ,there isslidf ably mounted, a piston 27 of substantial weight made of an insulating material, This piston 2 7 is provided with two

diametral holes

28, 29 located respectively in. tngo different; axialplanes at rightangles'; to each other. In each of these holesr vthere is, provided a pair of contact balls 3.0.321. and asprins? nrginasnidA ballsawnyzfrgnr each. .other ,Se as lto push. thern` against the .inner-wall of casing 26.

I n the position villustrated by Figs. 3I and 4, piston 2 7 is locked against axial movement by a safetyv wire 33 which, extends across the wall of casing 26 and through a hole A2.7.1191? pieten .2.7, the .inner end of Said wire nroieetins.; into a .recess 34. provided .at the top part; of .the piston, this wire constituting the. l1Ql/.e. mentioned loplgy inanaeniber@ 'In position Q f. ariston. balls .3 .,31 4and Spring :32, whihextend 'n .tb., upper hole. 2.8 .ofthe piston,v .eonsti.t.nte.. .a .eenneetion bete/eel.:A .contacts a.. al which are locatedv in the charging circuit of condenser-2;. For this position of ,the piston.. condenser 2.-.ean1tl1eref 2,sso,67a

. fore be charged from the outside, throughfcontact 3. The locking action of wire 33 must be sutciently strong to prevent shocks as high as 200 g (g--acceleration of gravity) from causing the piston to move from its position shown by Figs. 3 and 4.

In order to eliminate the locking action exerted by wire 33 on piston 27, there is provided at the lower end of casing 26 a small detonator 35 containing a small amount of a material capable of exploding under the effect of a spark, for instance tricinate of lead (trinitroresorcinate of lead). This detonator vis fed with current from a connection 36 which may constitute a portion of the connection serving to charge condenser 2, andin this vcase is in series with contacts a, a1. j

When the detonator is exploded under the effect of a current impulse, safety wire 33 is sheared off and piston Z7 is projected upwardly from the position of Figs. 3 and 4 to that of Fig. 5. The top of the piston is then applied upon shoulder 37 provided inside'chamber 26. `At the end of this movement, the portion 33a sheared ofi from wire 33 is moved, under the effect of its inertia, away from the aperture 27a of the piston and passes into recess 34, so that there is no danger of its braking the movement of piston 27. The direction of the movement of the piston from the position of Figs. 3 and 4 to that of Fig. 5 is that of the projectile as it is being launched and it is therefore opposed to that of the movement that would tend to be imparted by the inertia forces to

piston

2,7` inside chamber 26. V

Once the projectile has been launched and when its acceleration has reached a sutiicient value (for instance 30 g), piston 27 moves rearwardly in its chamber under thev effect of its own inertia and passes from the position of Fig. 5 to that of Fig. 6. In this last mentioned position, the balls present in the upper conduit 28 form a connection between contacts b, b1 and the balls present in the lower conduit 29 form a connection between contacts c and c1. The groups of contacts b, b1 and c, c1 correspond to the

elements

6, 8 and 6a, 8a of Fig. 2. The group of contacts a, a1 corresponds to' the

contact elements

7, 9 of Fig. l.

Advantageously, we provide a recess 38, at least in one of the inner walls of the chamber along the path of movement of contacts b, b1, c, c1, for instance of contact c1, so as to obtain, by cooperation with contact balls 31, a locking of piston 27 in the position shown by Fig. 6.

In a general manner, while we have, in the above description, disclosed what we deem to be practical and efficient embodiments of our invention, it should be well understood that we do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What we claim is:

l. In combination, a projectile to be fired off from a launching apparatus, an electric fuze fitted on said projectile and including fuze arming means, electric voltage accumulating means carried by said projectile to feed electric current to said fuze arming means, switch means inserted between said fuze arming means and said accumulating means, safety means carried by said projectile 4for holding said switch means in cut olf ,position between said accumulating means and said fuze arming means, an electric circuit in said projectile including in series a contact carried by the external wall of said projectile, said electric voltage accumulating means, said switch means in cut off position, said safety means and a contact, insulated from the tirst mentioned contact, carried by the external wall of said projectile, a iixed circuit carried by said launching apparatus including a source of direct current and having its terminals located on said two contacts respectively when said projectile is in said launching apparatus, whereby direct current is then fed before launching to said accumulating means through both of said circuits connected together, an electrical impulse responsive device carried by saidprojectile and inserted in said first mentioned circuit to make, when an electrical impulse is passed therethrough, said safety means inoperative and thus to cause said switch means to shift from cut off position to connecting position between said voltage accumulating means and said fuze arming means, a source of alternating current impulse carried byysaid launching apparatus and cooperating means carried by said projectile and said launching apparatus for temporarily coupling said last mentioned source with said xed circuit in response to the initial launching movement of said projectile with respect to said launching apparatus. l,

2. In combination, a projectile to be fired off from a launching apparatus, an electric fuze tted on said projectile and including fuze arming means, electric voltage accumulating means carried by said projectile to feed electric current to said fuze arming means, switch means inserted between said fuze arming means and said `accumulating means, safety means carried by said projectile for holding said switch means in cut olf position between said accumulating means and said fuze arming means, an electric circuit in said projectile including in series acontact carried by the external wall of said projectile, said electric voltage accumulating means, said switch`means in cut off position, said safety means and a contact, insulated from the first mentioned contact, carried by thev external wall of said projectile, a fixed circuit carried by said launching apparatus including a source of direct current and having its terminalslocated on said two contacts respectively when said projectile is in said launch-` ing apparatus, whereby direct current is then fed before launching to said accumulating means through both of said circuits connected together, an electrical impulse responsive device carried by said projectile and inserted in said first mentioned circuit to make, when an electrical impulse is passed therethrough, said safety means inoperative and thus to cause said switch means to shift fromv cut off position to connecting position between said voltage accumulating means `and said fuze arming means, a third circuit, including a source of alternating current impulses, 4carried by said launching apparatus, a transformer having its primary in said third circuit and its secondary in said xed circuit, a normally open switch in said third circuit, and cooperating means carried by said projectile and said launching apparatus for closing said switch in response to the initial launching movement of said projectile with respect to said launching apparatus.

3. A combination according to claim l further including, in said xed circuit, a resistance, and switch means forming a short-circuit path for discharge of said voltage accumulating means through said resistance in case of failure of said projectile to be launched.

4. In combination, a projectile to be fired off from a launching apparatus, an electric fuze titted on said projectile and including fuze arming means, electric voltage accumulating means carried by said projectile to feed electric current to said fuze arming means, switch means inserted between said fuze arming means and said accumulating means, said switch means including a tixed part and a movable part sensitive to the action of inertia so as to be urged by the inertia created by the launching of said projectile toward the position with respect to said xed part where it connects said voltage accumulating means with said fuze arming means, safety means carried by said projectile for holding said switch part in cut off position where said accumulating means and said fuze arming means are out of contact with each other, an electric circuit in said projectile including in series a contact carried by the external wall of said projectile, said electric voltage accumulating means, said switch means in cut olf position, said safety means and a contact, insulated from the first mentioned contact, carried by the external wall of said projectile, a fixed circuit carried by said launching apparatus including a source of direct ,ciment andihaving Aits terminals lecatedon said. two con:

o impulse is ypassed therethrough, said safety means inoperative `andlthus to cause said switch movable part to shift under the effect o'f the starting acceleration of the vehicle from its cut olf position to its connecting position between .Said voltage accumulating means and said fuze arming means, a source of alternating current impulse carried ,bysaid launching apparatus and cooperating means carried by said projectile and said launching apparatus for temporarily coupling said last mentioned source `with said finedv circuit in response to the initial launchingy movementv of said projectile with respect to said launching apparatus.

5. A combination according to. `clairrll 4 in which said Safety means consist of a fusible wire mounted in said first rnentioned circuit and normally holding ysaid switch movable part in cutol position with respect, to saidswitch tilted part- ,6. A combination accordingto claim 4 in `which said safety means include a locking wire normally holding said Switch movable part in cut-off position with respect to said switch fixed part, said wire extending transversely tothe direction of displacement of said movable part with respect to said fixed part so as to be sheared by said displacement, and a charge of explosive inserted in said first circuit and adapted to explode in response to the passage of said current impulse for moving saidmovablepart with respectv tol said fixed part..

`7 A combination according to claim 6 in which said xged part is a cylinder and said movable part a piston Slitlable in said cylinder.

A8 A combination according to claim 6 in whichsaid flared` part is a cylinder and said movable part a piston slidable in said cylinder, said combination further inleluding means for locking js'aid. piston/in connecting position nsaid cylinder..

9. In combination, a projectile, an electric fuze fitted on saidy projectile and including fuze arming means, electric voltage accumulating means carried by said projectile to feed electric current to said fuze arming means, switch means inserted between said fuze arming means and said accumulating means, mechanical safety means carried lby said projectile for normally holding said switch means in cut off position between said accumulatingV means and vsaid fuze arming means, electrical impulse operative means carried by said projectile and connected with said safety means for making said safety means inoperative, and means operatively connected with said eectrical impulse operative means ,for feeding thereto an electrical impulse in response to the tiring off of said projectile.

l0. In combination, a projectile, an electric fuze fitted on. said projectile and. having an electric circuit which comprises a control switch, said switch including av fixed part carried by said projectile and a movable part capable of occupying either of two positions with respect to said fixed part, a locking member normally holding said movable part in one of said positions, said member being fixed to each of said parts in the direction of their rela,- tive movement and being so dimensioned and made of such material as lto be shearable by a relative displacement of said parts from said lastv mentioned position toward the other one under the effect of a given thrust, said two parts fitting in each other so` as to form between them a variable volume chamber, an explosive charge insaidy chamber capable by its explosion to supply such said thrust, and electric means connected with said explosive charge to explode it by an electric impulse.

References Cited in the file of this patent UNITED STATES PATENTS