US3715988A - Missile fuses - Google Patents

Abstract

A fuse for a ballistic missile comprising a hammer and a firing chain so arranged that when the missile strikes its objective the hammer penetrates the firing chain and causes the missile to explode. The firing chain includes two detonators carried in a rotor which has a safety position in which the detonators are out of alignment with the firing hammer, the detonators being brought into active position with a delay period after firing of the missile due to an imbalance in the rotor so that rotation of the missile after firing causes the detonators to be aligned with the hammer. In consequence when the missile strikes an objective after a predetermined time from the initiation of its flight the hammer penetrates the detonators and causes the missile to explode.

Description

United States Bares atent Feb. 13,1973

l54l MISSILE FUSES [75] Inventor: Roger Bares, Roques S/ Garonne,

France [73] Assignee: Societe E. Lacroix 221 Filed: July 29, 1970 [21] Appl. No.: 59,126

[30] Foreign Application Priority Data Aug. 26, 1969 France .6929160 [52] US. Cl ..102/80, 102/78 [51 1 Int. Cl. ..F42c 15/26 [58] Field of Search ....l02/76, 79, 80, 70

[56] References Cited UNITED STATES PATENTS 3,500,748 3/1970 Hager et al. 102/79 2,977,883 4/1961 Czajkowski ..l02/79 FOREIGN PATENTS OR APPLICATIONS 17,795 1905 Great Britain ..102'/8O Primary Examiner--Samuel W. Engle Attorney-Andrus, Sceales, Starke & Sawall [57] ABSTRACT A fuse for a ballistic missile comprising a hammer and a firing chain so arranged that when the missile strikes its objective the hammer penetrates the firing chain and causes the missile to explode. The firing chain includes two detonators carried in a rotor which has a safety position in which the detonators are out of alignment with the firing hammer, the detonators being brought into active position with a delay period after firing of the missile due to an imbalance in the rotor so that rotation of the missile after firing causes the detonators to be aligned with the hammer. In con sequence when the missile strikes an objective after a predetermined time from the initiation of its flight the hammer penetrates the detonators and causes the missile to explode.

E we 3 \b- F 1 m '2 l6 to 33m MISSILE FUSES The present invention is concerned with a fuse for missiles, projectiles or shells.

It is known that a fuse for a missile is an arrangement associated with the missile and adapted to make it explode when the latter strikes its objective.

Such a fuse generally comprises a hammer and a firing or pyrotechnic chain disposed in such a manner that the hammer, under the effect of the impact of the projectile on its objective, penetrates into a detonator or percussion cap and initiates the firing chain which causes the shell to explode.

For reasons of safety, the fuse must be inert or the chain interrupted, on the one hand, when the shell is in storage and, on the other hand, for an initial part of the trajectory of the shell when the shell is fired. Further, the fuse must be armed a certain determined distance after the instant of firing.

To attain these objectives, the fuse, according to the invention, comprises a rotatably mounted member, or rotor, carrying the active firing or pyrotechnic chain and able to take up two positions, namely a first position called safety in which the rotor is locked in such a manner that the firing chain is interrupted and a second position called alignment in which the firing chain is continuous, the passage from the "safety" position to the alignment position being effected under the effect of the rotation of the projectile due to a want of balance of or unbalance in, the rotor, the hammer also being able to take up two positions, namely a locking position in which it secures the rotor in the safety position and an armed position in which the rotor is free to take up the alignment" position, a delaying arrangement being provided whereby the hammer passes from the locking position to the armed position with a predetermined delay after firing of the missile.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is an axial section of a fuse according to the invention, in the inert position;

FIGS. 2 and 3 are sections of the fuse of FIG. 1 respectively on the lines II-II and III-III;

FIG. 4 is a similar view to FIG. 1 with the fuse armed; and

FIG. 5 is a similar view of the fuse at the instant of impact.

In FIG. 1, reference 1 designates the point or leading end 1 of the fuse, which is appreciably of parabolic form and open at the bottom. The fuse comprises a hammer 2 and a firing or pyrotechnic chain constituted by a primary detonator 3, a second detonator 4 and a booster 5. The primary and secondary detonators 3 and 4 constitute the active firing or pyrotechnic chain.

The hammer 2 is constituted by a tail 6 and a piston 7 slidably mounted in the chamber 8 of cylinder or housing 8a filled with balls 9, the piston 7 pressing on the balls under the action of aspring 10.

The part of the firing chain constituted by the two detonators 3 and 4 is mounted in a rotatable member, or rotor 11. The rotor 11 is mounted for rotation about an axis perpendicular to the plane of the Figure (and thus also to the axis of the fuse) and rests in bearings provided for this purpose in a member 12 supported on the body 13 of the fuse and is held thereon by a member 14. The member 12 is constituted by a cylindrical receptacle comprising a base 12a and a cylindrical wall 12b in which are cut two borings 23 and 24 serving as the bearings for axles 25 and 26 of the rotor 11, and two openings 27 and 28 to permit location and pivoting of the rotor 11. The holding member 14 also has the form ofa body of revolution. It has two projecting parts 29 and 30 which rest on the axles 25 and 26 of the rotor to maintain the latter in place. The member 14 has a central boring 31 for receiving the tail 6 of the hammer and serving thus to support the hammer.

The spring 10 rests also on a shoulder of this holding member 14.

The booster 5 is mounted in the body 13. The rotor is formed so as to have a want of balance or unbalance, that is to say, its center of gravity does not coincide with the axis of rotation, and it thus has a defined sense of rotation. This want of balance or unbalance is obtained for example due to a displacement of the axis of the detonators relative to the axis of the fuse (FIG. 1) obtained by machining a face of the rotor. It must be noted that the fuse in its assembly has no want of balance or unbalance which is very important to limit the movement of precession of the shell.

A boring 15, cut in the rotor, serves to receive the tail 6 of the hammer to lock the rotor in the safety position shown (FIG. 1) in which the firing chain is interrupted. It is to be noted that in the case of accidental initiation of the detonators, the action of their explosion is directed towards the exterior and in no instance towards the booster 5.

The rotor has a cut-out 16 serving to lock the rotor on a pin in the alignment position as will be seen later.

Around the cylinder 8a is slidably mounted a ring 17 held by pins 18. The hammer is maintained in axial alignment by the support member 14 screwed on the cylinder 8.

The operation of the fuse is as follows:

At the instant of the firing or shot, the ring 17, by inertia, shears the pins 18 under the effect of acceleration and slides till a resilient ring 19 carried by the ring 17 comes to wedge behind a shoulder 20 of the fuse body. The sliding of the ring 17 towards the fuse bottom uncovers a hole 32 cut in the cylinder 8a permitting the outflow of the balls 9 from chamber 8 into the space between the pointed casing 1 and cylinder 8a. The ejection of the balls is effected under the action of the hammer 2 moving into the chamber 8 thanks to the spring 10 so as finally to take up the armed position in which the tail of the hammer has left the boring 15. This results in the rotor 15 rotating in the predetermined direction under the action of centrifugal force resulting from rotation of the missile. The rotor turns through due to its want of balance or unbalance. The rotation is limited by a pin 33 abutting the end of the peripheral cut-out 16 in the rotor 11 so that the firing chain aligns automatically with the hammer. This abutment permits a perfect alignment whatever may be the speed of rotation of the missile.

At impact of the missile on its objective, the nose of the fuse is crushed which forces the tail of the hammer into the primary detonator 3 which detonates so actuating the secondary detonator 4 and the booster 5.

The booster 5 finally makes the shell explode.

The angle of impact and the nature of the objective have great importance on the firing or non-firing of the fuse so that the sensitivity of the fuse is variable and difficult to determine in advance.

This problem is resolved by the fact that the wall of the cylinder 8a enclosing the balls and the hammer is constituted of two cylindrical parts of different diameters connected'by a shoulder 21.

At impact, this shoulder is crushed, the front part of the cylinder 8a penetrating into the rear part of a greater diameter so that the hammer plays its role in penetrating into the primary detonator (FIG.

As the necessary crushing force can be easily calculated knowing the thickness of the shoulder 21 and the desired sensitivity, it is sufficient to select a thickness suitable for the desired object. Further, the pointed end 1 has a line of rupture 22 so that on impact the upper part of the fuse body is forced into the lower part; this results in a greater regularity in the sensitivity of the fuse (FIG. 5).

The delaying arrangement is constituted by the system of balls and permits the introduction of a predetermined delay in a precise manner in the arming of the fuse. In one embodiment, this delay is controlled in such a manner that it corresponds to a distance of about 60m. Thus, one is sure that the shell will not explode if it meets an obstacle within this distance.

The delay may be a little greater but it is made to match a given distance, for example 100m from the departure of the missile, before the fuse is armed with certainty.

What is claimed is:

1. A fuse for a missile, comprising a casing having a booster at the rear end of the casing for exploding of the missile, a rotor adjacent the rear end of the casing carrying detonator means and adapted to be rotated from a safety position to a firing position, a movable hammer adapted at the rear end thereof to engage the rotor to hold the rotor in locked safety position, and actuating means for moving the hammer out of engagement with the rotor to permit rotation of the rotor from the locked safety position to an armed position whereby the detonator means is placed in line with the hammer when the fuse is actuated for firing, the said fuse having a safety arrangement for locking the hammer in the rest position and for allowing the hammer to move from the rest to the armed position only after a predetermined time delay after firing of the missile, characterized by a housing in said casing having a chamber therein, a piston on the forward end of said hammer adapted to be slidably received in the chamber of said housing, a plurality of balls confined in said housing by the piston on said hammer with the balls normally holding the hammer in rest position, an exit passage in the wall of the housing from said chamber, and an inertia operated member slidably mounted on said housing and closing said exit passage when the fuse is in rest position and slidable to a position to open said exit passage when the missile is fired to permit flow of the balls through the exit passage over a predetermined delayed period of time so that the hammer is free to move forward out of engagement with the rotor and the rotor is then free to rotate under centrifugal force to position the detonator in position to be detonated by the hammer when the fuse strikes an obiect.

A fuse according to claim 1, wherein the inertia operated member is a ring assembled around said cylinder, pin means securing the inertia operated member in the position to close the aperture and being sheared upon firing of the missile by the inertia operated member as the latter by inertia slides on said cylinder and opens said aperture for release of the balls from the cylinder.

3. A fuse according to claim 1, wherein the rotor has a central elongated hole to receive the inner end of the hammer to hold the rotor in non-firing position.

4. A fuse according to claim 1 wherein said housing is an axially extending cylinder with one portion of the cylinder having a greater diameter than a second portion and an annular shoulder therebetween, said shoulder adapted to be crushed on impact of the fuse.

5. A fuse according to claim 1, and bearing means mounted within the casing for supporting the rotor, said bearing means comprising a hollow cylindrical member having two opposed openings extending in one direction to receive the rotor in the openings and support the rotor for rotation on the cylindrical member, and two other openings in the cylindrical member in a direction at right angles to the first stated openings permitting rotation of the rotor therein.

Claims (5)

1. A fuse for a missile, comprising a casing having a booster at the rear end of the casing for exploding of the missile, a rotor adjacent the rear end of the casing carrying detonator means and adapted to be rotated from a safety position to a firing position, a movable hammer adapted at the rear end thereof to engage the rotor to hold the rotor in locked safety position, and actuating means for moving the hammer out of engagement with the rotor to permit rotation of the rotor from the locked safety position to an armed position whereby the detonator means is placed in line with the hammer when the fuse is actuated for firing, the said fuse having a safety arrangement for locking the hammer in the rest position and for allowing the hammer to move from the rest to the armed position only after a predetermined time delay after firing of the missile, characterized by a housing in said casing having a chamber therein, a piston on the forward end of said hammer adapted to be slidably received in the chamber of said housing, a plurality of balls confined in said housing by the piston on said hammer with the balls normally holding the hammer in rest position, an exit passage in the wall of the housing from said chamber, and an inertia operated member slidably mounted on said housing and closing said exit passage when the fuse is in rest position and slidable to a position to open said exit passage when the missile is fired to permit flow of the balls through the exit passage over a predetermined delayed period of time so that the hammer is free to move forward out of engagement with the rotor and the rotor is then free to rotate under centrifugal force to position the detonator in position to be detonated by the hammer when the fuse strikes an object.

1. A fuse for a missile, comprising a casing having a booster at the rear end of the casing for exploding of the missile, a rotor adjacent the rear end of the casing carrying detonator means and adapted to be rotated from a safety position to a firing position, a movable hammer adapted at the rear end thereof to engage the rotor to hold the rotor in locked safety position, and actuating means for moving the hammer out of engagement with the rotor to permit rotation of the rotor from the locked safety position to an armed position whereby the detonator means is placed in line with the hammer when the fuse is actuated for firing, the said fuse having a safety arrangement for locking the hammer in the rest position and for allowing the hammer to move from the rest to the armed position only after a predetermined time delay after firing of the missile, characterized by a housing in said casing having a chamber therein, a piston on the forward end of said hammer adapted to be slidably received in the chamber of said housing, a plurality of balls confined in said housing by the piston on said hammer with the balls normally holding the hammer in rest position, an exit passage in the wall of the housing from said chamber, and an inertia operated member slidably mounted on said housing and closing said exit passage when the fuse is in rest position and slidable to a position to open said exit passage when the missile is fired to permit flow of the balls through the exit passage over a predetermined delayed period of time so that the hammer is free to move forward out of engagement with the rotor and the rotor is then free to rotate under centrifugal force to position the detonator in position to be detonated by the hammer when the fuse strikes an object.

2. A fuse according to claim 1, wherein the inertia operated member is a ring assembled around said cylinder, pin means securing the inertia operated member in the position to close the aperture and being sheared upon firing of the missile by the inertia operated member as the latter by inertia slides on said cylinder and opens said aperture for release of the balls from the cylinder.

3. A fuse according to claim 1, wherein the rotor has a central elongated hole to receive the inner end of the hammer to hold the rotor in non-firing position.

4. A fuse according to claim 1 wherein said housing is an axially extending cylinder with one portion of the cylinder having a greater diameter than a second portion anD an annular shoulder therebetween, said shoulder adapted to be crushed on impact of the fuse.

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