US3839963A

US3839963A - Proximity fuse for missiles

Info

Publication number: US3839963A
Application number: US00349124A
Authority: US
Inventors: G Nathan; C Varaud
Original assignee: Constructions Navales et Industrielle de la Mediterranee CNIM SA
Current assignee: CNIM Groupe SA
Priority date: 1972-04-10
Filing date: 1973-04-09
Publication date: 1974-10-08
Anticipated expiration: 1991-10-08
Also published as: DE2318039A1; GB1371480A; NL7304993A; NO135446C; JPS4948200A; FR2180159A5; IL41998A; IL41998A0; IT983756B; NO135446B

Abstract

A compact fuse designed to be armed after cessation of acceleration and provided with a plurality of safety means; a cap adapted to be set in an inoperative position by a rotation of 90* with reference to the fuse body, a cover for the cap adapted to collapse towards the striker and to prevent its releasing operation in case of a premature impact, a detonator-carrier adapted to be shifted laterally out of registry with the striker, a weight controlled by inertia and controlling operation of the striker and an arming weight releasing through inertia in striker.

Description

United States Patent [1 1 Nathan et a1.

[ 1 Oct. 8, 1974 PROXIMITY FUSE FOR MISSILES [75] Inventors: Guy E. Nathan,

' lssy-Les-Moulineaux; Claude A.

Varaud, Nogent-Sur-Mar, both of France [73] Assignee: Constructions Navales et lndustrielles de la Mediterranee C.N.I.M., Paris, France 22 Filed: Apr. 9, 1973 21 Appl. No.: 349,124

[30] Foreign Application Priority Data Apr. 10, 1972 France "72.12527 [52] U.S.'Cl. 102/702 P, 102/76 R, 102/78 [51] Int. Cl F420 15/00, F42C 13/00 [58] Field 01' Search 102/702 R, 70.2 P, 78,

102/76 P, 76 R; 343/7 PF [56] References Cited I UNITED STATES PATENTS 1/1959 Saloranta et al 102/78 2,900.911 8/1959 Stath'am 102/702 P 2,951,444 9/1960 Hunt, Jr. et a1 102/78 3,151,558 10/1964 Lunati 102/78 Primary Examiner-Benjamin A. Borchelt Assistant Examiner- C. T. Jordan Attorney, Agent, or Firm-Finnegan, Henderson, Farabow & Garrett [5 7] ABSTRACT A compact fuse designed to be armed after cessation of acceleration and provided with a plurality of safety means; a cap adapted to be set in an inoperative position by a rotation of 90 with reference to the fuse body, a cover for the cap adapted to collapse towards the striker and to prevent its releasing operation in case of a premature impact, a detonator-carrier adapted to be shifted laterally out of registry with the striker, a weight controlled by inertia and controlling operation of the striker and an arming weight releasing through inertia in striker.

3 v Claims, Drawing Figures um 8l974 PAIENTEU sum 10F 3 839 963 PROXIMITY FUSE FOR MISSILES The present invention has for its object preventing premature ignition of a fuse and ensuring fuse ignition upon a missile reachinga point at a predetermined distance from the objective or from grounder upon impact therewith. Fuses of this type are already known which are generally extremely complex both electrically and mechanically and which are not wholly reliable for all conditions of use.

The invention removes these drawbacks by means of a fuse for missiles, of the type considered, which is mechanically and electrically very simple while it is perfectly reliable.

Briefly described, the invention comprises a fuse including a cap rotatable with reference to the fuse body and terminating with a conical point forming a deformable radome, the deformable radome protecting the detecting aerial and being rigid with the electronic system forming a compact unit which is slidable after the manner of a striker piston. The fuse also employs a mechanism including a detonator-carrier adapted to slide transversely within the body under the action of a spring or of centrifugal force, if required, said detonator-carrier being held normally aside by the end of the rod of an axial striker the front end of which forms a cylindrical tailpiece round which is slidingly fitted a striker weight urged forwardly by a spring and locked in its inoperative position by a first ball engaging a first groove in the tail-piece. Said first ball is itself held in position by a second ball or the like part adapted to move transversely and locked by an arming weight adapted to move within the cap in parallelism with the striker and to be urged forwardly by a further spring while it includes an extension towards the rear constituted by a rod passing through the spring.

The striker weight includes further locking means constituted, for instance, by a circlips adapted to be locked within a further groove of the tail-piece after the said weight has traveled sufficiently'towards the rear upon starting of the missile and after the arming weight has itself receded through inertia and has thus released the balls. When the striker weight is returned forwardly under the action of its spring, the front end of the striker tail-piece engages the striker piston and, simultaneously, its rear tip releases the detonator-carrier permitting its transverse movement which sets the detonator in front of said tip and closes at the end of its travel the general switch controlling the electronic circuitry.

The mechanism includes furthermore an electric primer arranged in parallelism within the striker and communicating through ports formed within the cap and the body with the main detonator when the latter is moved into an axial position. The electric primer is connected with the electronic detecting means through a delaying condenser. The whole arrangement is such that after a rotation, through say 90, of the cap with reference to the fuse body, the port connecting the electric primer in the cap registers no longer with the corresponding port inthe fuse body whereby the first series of firing means. is severed while the rear rod on the arming weight registers no longer with its releasing port in the body, which severs the second series of firing means by locking the striker in its rearmost position, this forming a second safety preventing the transverse movement of the detonator-carrier and cutting off the double pyrotechnical chain together with the electric circuit.

An embodiment of the invention will now be described by way of example and by no means in a limiting sense. Said embodiment is illustrated in the accompanying drawings wherein.

FIG. 1 is an axial cross-sectional view of a missile proximity fuse formed in accordance with this invention.

FIG. 2 is an axial cross-section, at right angles with that of FIG. 1, through line IIII of FIG. 4.

FIG. 3 shows on a larger scale a detail of the central portion of FIG. 1.

FIG. 4 is a transverse cross-section through line IV-IV of FIG. 1.

FIG. 5 is a cross-section through line V-V of FIG. 1.

DETAILED DESCRIPTION The fuse illustrated includes a body 1 and a cap 2 revolvably carried by said body 1 over which it is held by an expansible ring 3 held by a screw 4 (FIG. 2) both inside a groove in the cap and a groove in the extension 5 of the body inside the cap.

The body 1 includes a rear threaded section 6 so that it may be screwed as usual into the nose of a missile. The cap 2 is provided with a'cover 7 of a plastic perme able for hyperfrequency waves and acting as a radome while being sufficiently deformable. Inside said cover 7 is housed the aerial 8 of the hyperfrequency system forming a proximity radar system.

According to the invention, the system including the aerial 8, the hyperfrequency circuit 9 and the electronic detecting circuit 10 is carried as a compact unit within a metal socket 11 by means of a molded piece of plastic, the whole arrangement being fitted inside a bore located to the front of the cap 2, so as to slide axially. Thereby, in the case of a failure of the electromagnetic detecting means, the fuse will operate under direct impact against the target, the deformation of the cover 7 allowing said sliding arrangement to operate as a striker piston while it is urged forwards when inoperative by a spring 12a.

The actual mechanical part of the fuse includes a central metal block 13 bored axially at 14, a tubular striker weight 15 slidably mounted in said bore 14 and being permanently urged forwardly by a spring 16. Inside the bore in the striker weight may slide in its turn, the cylindrical tailpiece 17 of a striker 18, ending to the rear with a pointed end and slidingly engaging the center of a disc 20 rigid with the block 13 rigidly secured in its turn to the cap 2 by means of a screw 21 (FIGS. 1 and 4).

The same block-13 is provided with a further bore 22 parallel with the central bore 14 (FIG. 1) and wherein an arming weight 23 slides, which arming weight is urged forwardly by a spring 24. The arming weight 23 extends rearwardly, so as to form the rear tail-piece 25 of a smaller diameter passing through the spring 24 and slidingly engaging a port 26 in the disc 20.

In its inoperative position, as clearly shown in FIG. 3, the weight 23 locks a ball 27 housed inside a transverse bore 28 in the block 13 and acting on a further ball 29 housed in a bore 30 in the weight 15 associated with the striker, said ball 29 engaging anannular groove 31 in the tail-piece 17 of the striker. Now, the weight 15 on the striker is provided with a milled portion 30a which allows the ball 27 to enter slightly within said weight, so as to prevent its rotation. The transverse bore 28 opens into the longitudinal bore 22 through a preferably hammered or crimped clearance port as shown in FIG. 3, so as to prevent the ball 27 dropping into said bore 22.

The tail-end 17 of the striker is provided with a further sharp-edged annular groove 32 adapted to cooperate with a circlips 32a engaging a groove and slot in the weight of the striker, so as to ensure the interlocking of the

parts

15 and 17. At the upper end of the block 13 there is inserted a further disc 33 against which the arming weight 23 normally abuts.

Within the body 1 there is fitted another metal block 34 in which there is milled a parallelepipedic housing 35 the rear opening of which is closed by a disc 36 while a transversely shiftable substantially parallelepipedic detonator-carrier 37 is slidingly carried inside said housing. A bore provided in said detonator-carrier is engaged by the detonator 38 the front end of which registers with a port 39 in the carrier 37 while a further smaller bore 40 in said carrier in parallelism with the first-mentioned bore is adapted to house the rear tip 19 of the striker when the detonator-carrier 37 is in its outermost position illustrated in FIGS. 1 and 2. A return spring 41 housed in the threaded plug 42 urges normally the detonator-carrier 37 in the direction of the arrow 43 (FIG. 2) if the fuse is intended for cooperation with a self-propelled or semi-self-propelled missile. On the contrary, if the fuse is to be fitted on a missile fired by a rifled bore, the return spring may be replaced by an eccentric weight the centrifugal force acting on which urges the detonator-carrier in the direction of said arrow 43.

As is shown in FIG. 1, the block 34 and also the body 1 are provided with a longitudinal bore 44 affording a passage towards the rear for the rear tail-piece 25 of the arming weight 23.

In alignment with the axis of the striker 18, that is axially of the fuse body, a port 45 extends through the disc 36. To the rear of said port 45, there is a tube 46 filled with an explosive acting as a relay for the explosive in the detonator 38 when the latter faces the striker, said relay acting then on the booster charge 47 enclosed in the cup-shaped member 48 screwed over the rear end of the body 1.

The central block 13 is laterally milled at 49 (FIGS. 2 and 4), so as to house a block 50 of plastic in which are embedded a number of electric parts including an electric primer 51 with its feeding wires. The flame produced by said primer 51 is transmitted through the sloping bore 52in the disc and a further sloping bore 53 in the auxiliary block 34, to the detonator 38 through the port 39 when the latter registers with the fuse axis as described below. Inside said block 50 is also embedded a condenser 54 feeding the electric primer 51 into which it is discharged upon detection by the circuit l0.

Lastly, the rear extension 55 of the plastic block 50 passes through the fuse body as provided by suitable openings, which allows the cap 2 to turn by one quarter of revolution with reference to the body 1, said extension 55 serving thus as an abutment for such a rotation. The rear end of the extension 55 carries two connectors 56 adapted to engage corresponding parts in a further block of plastic 57 in which are embedded the supply batteries 58, said block 57 being revolvable around the explosive-filled tube 46. The extension 55 of the block 50 is provided furthermore with a transverse port 59 inside which lie two elastic conductive blades 60 adapted to be short-circuited upon insertion between them of a shaped member 61 having an annular retaining groove. The shaped member 61 is fitted in the detonator-carrier 37 with the interposition of an insulating sleeve 62.

The two conductive blades are inserted in a circuit section passing through one of the connectors while the other connector ensures direct feeding. Of course, in order to ensure operation, it is essential to electrically connect the parts embedded or carried in the plastic block 12 with those carried by the plastic block 50 and its extension 55. This can be obtained by yielding wires which are not illustrated without this leading to any difficulty since the two

blocks

12 and 50 do not revolve with reference to each other and, furthermore, move towards each other only upon impact, that is at a moment when the electric connections are no longer necessary. In contradistinction, the electric connections between the

blocks

55 and 57 are rigid by reason of the above'disclosed possibility of rotation of the block 57, so as to avoid the drawbacks arising from the use of a connection through yielding wires.

In order to make the operation more readily understandable, it will be first assumed that the fuse is adjustable for operation as illustrated, that is the cap 2 is angularly set on the body 1 in a manner such that the oblique bores 52 and 53 register and that the port 26 registers also with the bore 44.

Upon starting of the missile, the acceleration to which the fuse is subjected produces through inertia the recoil of the arming weight 23 which, after a sufficient travel, releases the ball 27 which, in its turn, releases the ball 29. This allows the striker weight 15 to recede also through inertia within the bore 14 and, provided the acceleration'is sufficiently lasting, to reach a position for which its circlips 32a drops into the groove 32 of the tail-piece 17 of the striker. When the acceleration ceases, the striker weight 15 returns forwardly under the action of the spring 16 and carries along with it the actual striker 18. This produces two results: on the one hand, the front end of the striker tail-piece 17 engages the block 12 and, on the other hand, the rear end 19 of the striker passes completely out of the bore 40 and releases the detonator-carrier 37. The latter moves under the action of the spring 41, or possibly of centrifugal force, in the direction of the arrow 43 and this leads, on the one hand, to make the port 39 and the detonator 38 register with the axis of the fuse and thus face the striker tip and, on the other hand, to set the shaped member 61 between the connecting blades 60, which closes the circuit feeding the electronic system.

The battery 58 feeds then the circuit of the radar and of the detector and loads the condenser 54 which, after a delay of say 5 to 6 seconds, is ready to operate. The missile continues its flight until the radar detects the presence of a target or the proximity of ground. At such a moment, and for a predetermined distance, the electronic system causes the discharge of the condenser 54 into the primer 51, which leads to the firing of the detonator 38 and consequently to the explosion of the missile. This corresponds to normal operation.

In case of a failure ascribable to misoperation of one of the sequential parts, the exploding of the missile is nevertheless ensured upon impact of the latter against a target or against ground. In fact, in such a case, the cover 7 is crushed and the piston-shaped block 12 pushes the tail-piece 17 of the striker which hits directly on the detonator 38.

When handling the missile, before the starting of the shot, but after the cap has been set in its operative position, safety is however ensured through the fact that if the missile is dropped for instance, the acceleration to which the fuse is subjected is not sufficient, as to intensity and as to duration, for producing in succession the complete collapse of the arming weight 23. This is true even if the missile falls upon its tip since the striker in its rearmost position cannot move forwards and furthermore neither the detonator 38 nor the electric primer 51 can initiate the explosion. Still more, thearming weight 23 is braked by the thrust exerted by the balls in proportion with the violence of the shock, the outline of the groove 31 having a larger radius than the ball 29.

On the other hand, upon firing of the missile, the safety at the muzzle is ensured by the fact that throughout the duration of the acceleration and even after collapse of the arming weight 23 and after the striker weight 15 has receded, the spring 16 remains compressed, so that said striker weight 15 cannot bring the tail-piece 17 into contact with the electronic block 12. If the missile meets an obstacle during its acceleration, the block 12 is pushed inwardly and the tail-piece 17 of the striker can no longer travel far enough for releas ing the detonator-carrier 37 when the acceleration has come to end, which as precedingly breaks both the electric circuit and the two 'pyrotechnical sequential parts. If, on the'contrary, no hindrance is .then met by the missile and, after the fuse has been completely armed, the radar detects immediately beyond the muzzle the proximity of an obstacle, the missile cannot yet explode since the electric circuit has not been closed for enough time for loading the condenser 54. It has been stated that the time required for such a loading is of'a magnitude of 5 to 6 seconds and this allows the missile to be several miles beyond the muzzle before it can operate.

Of course, during transportation and dropping with a parachute, the cap 2 must be turned round its axis through say 90 with reference to the body 1, so as to be set in a safety position. Under such conditions and in addition to all the above described safeties, said rotation causes the rear tail-piece 25 of the arming weight and the bore 26 in the disc to be out of registry with the bore' 44 in the block 34, which positively locks the mechanical part of the fuse and the corresponding safety means. Simultaneously, the sloping bores 52 and 53 are out of registry, which produces a gap in the pyrotechnical chain of sequential parts adjacent the electric primer 51 while the electric circuit is broken by the locking of the detonator carrier in its inoperative position, the port 39 and the detonator 38 being also out of registry with the bore 53 and the tube 46.

Absolute safety is thus obtained through a plurality of means, so that nothing whatever can lead to an explosion during transportation or dropping through a parachute. The fuse according to the invention has thus reached a high degree of reliability and safety while it is comparatively simple, sturdy and of a reduced bulk.

Obviously many modifications may be brought to the above described embodiment and certain parts may be replaced by equivalent parts without widening thereby the scope of the invention as defined by the accompanying claims.

What we claim is:

l. A proximity fuse for missiles, including a body adapted to be fitted on the nose of a missile and a cap revolvably carried by the body and provided with a cover forming a radome permeable to hyperfrequency radiation, said fuse being characterized by the fact that the radome is inade of a deformable material and encloses a detecting aerial rigidly mounted on an electronic section adapted to slide inside the cap so as to form a striking plunger, said section including detecting means, the fuse including a detonator-carrier and detonator adapted to slide transversely in the body, first means for applying a transverse force on said detonator-carrier, switch means responsive to said detonatorcarrier, said detonator-carrier being normally held in an inoperative position by the rear tip of the rod of an axial striker having a fronttail-piece, a striker weight slidable on said tail-piece and urged forwardly by a spring and locked when inoperative by a first ball engaging an annular groove in said tail-piece, said first ball being held in said annular groove by second means adapted to move transversely and locked in its normal position by an arming weight adapted to move' inside the cap along a line parallel with the striker weight and urged forwardly by a further spring, said arming weight including a rearward extension passing through said further spring and aligned with a port when the cap and body are in a first position, third means on the striker weight adapted to engage a further groove in the striker tail-piece after the striker weight has traveled a predetermined distance in a rearward direction upon firing of the missile and after the arming weight has itself been shifted rearwardly through inertia and has thus released the first ball and second means, the striker weight having first returned forwardly under the action of its spring, the front end of the striker tail-piece engages the'striking plunger while the striker rear tip releases the detonator-carrier for transverse movement to bring the detonator into its operative position in front of said rear tip and to close at the end of its stroke said switch means, said swtich means controlling an electronic circuit including a battery, an electric primer arranged in parallel with the striker communicating through channels formed in the cap and in the body with said detonator when said detonator is brought into its operative position, said primer being connected with the detecting means through a delaying condenser, rotation of the cap'with reference to the fuse body to a second position causes the channel in the cap connected with the electric primer to be out of registry with the corresponding channel in the fuse body to prevent fuse ignition while the rear tail-piece on the arming weight is out of registry with said port provided in the fuse body to further prevent fuse ignition by preventing transverse movement of the detonator-carrier.

2. A fuse as claimed in claim 1, wherein the switch means includes two elastic conductive blades having an interval therebetween, a conductive member provided with an annular retaining groove mounted on the detonator-carrier in alignment with said interval whereby transverse movement of said detonatorthe cap with reference to the body, the rearward extension of the first block ending with connecting plugs engaging a second block of plastic molded over the battery, a rear booster and a tube containing an explosive forming a pyrotechnic relay between the detonator and the rear booster, the second block surrounding said tube and mounted for rotation thereabout.

Claims

1. A proximity fuse for missiles, including a body adapted to be fitted on the nose of a missile and a cap revolvably carried by the body and provided with a cover forming a radome permeable to hyperfrequency radiation, said fuse being characterized by the fact that the radome is made of a deformable material and encloses a detecting aerial rigidly mounted on an electronic section adapted to slide inside the cap so as to form a striking plunger, said section including detecting means, the fuse including a detonator-carrier and detonator adapted to slide transversely in the body, first means for applying a transverse force on said detonator-carrier, switch means responsive to said detonator-carrier, said detonator-carrier being normally held in an inoperative position by the rear tip of the rod of an axial striker having a front tail-piece, a striker weight slidable on said tail-piece and urged forwardly by a spring and locked when inoperative by a first ball engaging an annular groove in said tail-piece, said first ball being held in said annular groove by second means adapted to move transversely and locked in its normal position by an arming weight adapted to move inside the cap along a line parallel with the striker weight and urged forwardly by a further spring, said arming weight including a rearward extension passing through said further spring and aligned with a port when the cap and body are in a first position, third means on the striker weight adapted to engage a further groove in the striker tail-piece after the striker weight has traveled a predetermined distance in a rearward direction upon firing of the missile and after the arming weight has itself been shifted rearwardly through inertia and has thus released the first ball and second means, the striker weight having first returned forwardly under the action of its spring, the front end of the striker tail-piece engages the striking plunger while the striker rear tip releases the detonator-carrier for transverse movement to bring the detonator into its operative position in front of said rear tip and to close at the end of its stroke said switch means, said swtich means controlling an electronic circuit including a battery, an electric primer arranged in parallel with the striker communicating through channels formed in the cap and in the body with said detonator when said detonator is brought into its operative position, said primer being connected with the detecting means through a delaying condenser, rotation of the cap with reference to the fuse body to a second position causes the channel in the cap connected with the electric primer to be out of registry with the corresponding channel in the fuse body to prevent fuse ignition while the rear tail-piece on the arming weight is out of registry with said port provided in the fuse body to further prevent fuse ignition by preventing transverse movement of the detonator-carrier.

2. A fuse as claimed in claim 1, wherein the switch means includes two elastic conductive blades having an interval therebetween, a conductive member provided with an annular retaining groove mounted on the detonator-carrier in alignment with said interval whereby transverse movement of said detonator-carrier effects insertion of said conductive member into said interval to complete an electrical circuit.

3. A fuse as claimed in claim 1, wherein the cap carries a first block of plastic molded over the switch means controlling the electric circuit, the condenser, the electric primer and their connections, said first block extending rearwardly through an opening in the fuse body which provides abutments for the rotation of the cap with reference to the body, the rearward extension of the first block ending with connecting plugs engaging a second block of plastic molded over the battery, a rear booster and a tube containing an explosive forming a pyrotechnic relay between the detonator and the rear booster, the second block surrounding said tube and mounted for rotation thereabout.