IL37128A - Impact fuse for spin stabilized projectiles including a safety device - Google Patents

Description

IMPACT FUSS FOR STABILIZED A DEVICE AB T OF DISCLOSU 4 An impact fuze for a spin stabilized projectile of the type comprising a carrier for a detonator rotatable by spring means from a safe into an armed and a safety device in the form of an axially movable safety 5 The safety stud in a forward position locks the pellet carried in the safe The stud is displaceable by the acceleration on discharge of the projectile into a rear position in which it releases the The pellet carrier is positioned so that the centrifugal force acting on its centre of gravity will oppose the inertial force due to spin 10 Thus the frictional forces arising between the pellet carrier and the safety stud is limited to prevent the stud jamming and preventing the fuze from being The present invention relates to an impact fuze for a spin stabilized projectile of the type comprising a carrier for a detonator ro table by spring means from a safe into an armed and a safety device in the form of an axially movable safety A known construction of this type of fuze for spin stabilized projectiles contains a safety device which does not release the carrier until the acceleration of discharge has During discharge the acceleration of spin generates an inertial force that acts on the pellet carrier and may substantially increase the frictional forces between the pellet carrier and the safety In the case a safety device intended to release the pellet carrier before the acceleration of discharge has the said force of must not be allowed to increase since it might cause the stud to jam and thus prevent the fuze from being According to the present invention there is provided a a carrier for a detonator said carrier being rotatable by spring means from a safe into an armed and a safety device comprising an axially movable in which the safety stud in a forward position locks the pellet carrier in the safe the safety stud displaccable by the acceleration on discharge of the projectile into a rear position in which it releases the pellet and in which the pellet carrier is positioned so that the centrifugal force acting on its centre of gravity will oppose the inertial force due to spin acceleration and thereby prevent the safety stud from In a particular embodiment of the invention the pellet carrier is so contrived that in rojectile stabilised by right hand spin the cent re of gravity Of the pellet carrier is on the right hand viewed in the direction of of the line connecting the fuze axis and the axis of rotation of the pellet said connecting line subtending an acute angle the centre of The drawin illustrates an embodiment of the subject matter of the In the drawings Figure is an axial section of a fuze according to the invention along the line I I of Figure showing the pellet carrier in a safe Figure la shows a selector pin in position for delayed Figure 2 cross section of the fuze of Figure 1 along the line II II Figure 3 is a similar section of the fuze of Figure 1 showin pellet carrier in an armed Figure 4 is a section along the line IV of Figure 3 Figure 5 is a diagrammatic representation of the fuze of Figure 1 showing the forces acting on the centre of gravity of pellet and Figure 6 is a diagrammatic representation of the fuze of Figure 1 showing the centre of gravity of the pellet carrier in a further With to Figure 1 a cylindrical plug 2 is inserted into a central blind bore 3 in the body 1 of a A sleeve 4 with a substantially closed top 5 is also contained in the bore 3 above the plug the annular edge of the sleeve 4 resting n the top of the plug A fuze head 6 axially traversed by a central bore 7 is screwed into the body 1 of the fuze and locates the sleeve 4 and the plug A sleeve 8 is slidably movable inside the bore 7 in the head 6 of the A spring 9 is interposed between the top 5 of the sleeve 4 and a plug 10 positioned in the sleeve The sleeve 8 is formed with a shoulder 11 which the spring 9 holds in contact with a corresponding shoulder 12 having a face perpendicular to the fuze axis inside the bore central bore extending upwards to a face 13 in the body of fuze contains explosive core 14 which extends down to the bursting charge of the A percussion pin 15 is attached to the plug 10 in the sleeve The p in 15 is guided in a bore through the top 5 of the sleeve 4 and projects through a chamber 17 enclosed by the sleeve 4 and through a face of the plug 2 forming the bottom of the chamber 17 into a further bore in the plug The bore 18 leads into a cylindrical recess 19 in the eccentrically located with reference to the longitudinal axis A of the The inner end 20 of the recess 19 is increased in diameter and has a circularly arcuate peripheral enlargement 21 which has its centre on the longitudinal axis 5 of the A detonation pellet carrier 22 in the form of a hereinafter referred to as the is contained in the recess 19 in the plug The rotor 22 contains a bore 23 which is open on the side of the rotor facing The underside 24 of the rotor bottom 25 is parallel to the face 13 in the body of the A ring 26 is positioned partly in the bore 23 so projects that a face of the ring leading face of the rotor An arbor 27 is located in a further bore 28 in the plug 2 parallel to the bore 18 and secured against rotation by a The arrbor 27 extends into the bore 23 in the rotor 22 and bears against the face 13 in the body 1 of the A coiled torsion spring 29 is contained in the bore 23 of the rotor 22 and 30 embraces the arbor One end of the energised spring 29 bears against the ring 26 and is retained by the wall of a slit 33 connecting the bore 23 to a bore 32 in the rotor The other end 31 of the spring engages a slit which machined into a flange 34 on the arbor The ring 26 is pressed against the bottom of the recess by the thrust of the spring 29 which is also axially The fuze includes a safety device which makes the fuze safe transportation and The device comprises a pin 35 and a safety stud This device is contained in a bore 37 in the fuze The safety stud 36 projects into the arcuate enlargement 21 in the bore With reference to Figure 2 it will be seen that the rotor is formed with a gear quadrant 38 about its axis of and in its periphery with a concavity 39 that is concentric with the circumference of the safety stud This concavity partly embraces the safety stud 36 and thus prevents the rotor 22 from rotating in either Referring to Figure 4 the bore 40 in the body 1 of the fuze parallel to its axis contains an arrangement for delaying the action of the A cylindrical stem 41 is fixed at the bottom of the bore 40 and extends upwards into the A sleeve 42 surrounding this member 41 is movable inside the bore 40 and in the illustrated position of rest the sleeve bears against a foot 43 of the member A spring 44 is interposed between a shoulder 45 in the sleeve 42 and the rear end of a striker pin front end of the member 41 projects into a socket 47 in the back of the striker The striker pin is coupled to the stem by locking balls 49 contained bores machined transversely into the wall of the striker pin at right angles to the striker pin The locking balls are biased by the spring 44 into contact with a bevel face 50 in the stem 41 which is itself attached to the of the fuze and the balls are thus held in coupling position with the stem At the same time the balls 49 are retained by the internal wall of a second sleeve 51 which is likewise contained in the bore and which thus held in position by This latter sleeve 51 has a bevelled end face 52 resting oh the end face 53 of the sleeve 42 arid its forward s of reduced When the fuze is armed the bore 55 in the rotor 22 axially aligns with the striker pin This bore 55 contains a pellet A selector pin 57 is provided in the plug 2 and extends perpendicularly to the fuze In a manner not shown in the drawing this selector pin can be turned into either of two operative The end of the selector pin 57 extending across the fuze axis contains an axial bore 58 for the reception of the pointed end of the percussion pin When the selector pin is in position for direct action the percussion pin 15 can pass an opening 59 in the wall of the selector pin normal to the direction of the axial bore When the selector pin 57 is turned through into its alternative position for delayed action the passage of of the percussion pin 15 through the selector pin is as shown in Figure A pocket 60 in the shape of an arc concentric about its axis of rotation is machinej into the rotor This pocket 60 contains a filler 61 which is made of a material of greater specific gravity than that of the material forming the rotor The common centre of gravity S of the rotor 22 containing the filler 61 is not therefore located on the rotor axis but to one side of a line connecting the axis A of the fuze and the axis D of the The filler 61 has a socket 62 which in the safe position of the rotor 22 conincides with the axis A of the A detonator pellet 66 is contained in the rotor 22 in ore is parallel to the axis of The distance of this bore 65 from the axis of the rotor 22 equals the distance of the rotor axis from the axis of the The gear quadrant 38 on the rotor 22 meshes with a gear wheel that is mounted on a pin 64 rotatably mounted in the plug A gear train comprising a pinion 67 in the chamber 17 forms a transmission for cooperation with an escapement lever thus constituting an escapement delay train which in a known manner retards the rotation of the rotor In projectiles stabilised by right spin the fuze containing the plug 2 will experience an acceleration of spin about the axis A of the fuze in the direction P in Figure A consequent inertial force will tangential component with respect to the axis of rotor rotation At the same time a centrifugal force will act on the centre of gravity This centre of gravity S is located on the right hand side of a line V connecting the fuze axis A to the rotor axis the line V subtending an acute angle at the centre of assist in an understanding of later explanations the centre of gravity S is shown in Figure 6 in a position which differs from its actual In this instance the connecting line between the axes A and D subtends an obtuse angle β at the centre of The centre of gravity S of the rotor 22 experiences a centrifugal force Z2 and the tangential component of an inertial force The described arrangement functions as follows Before the projectile is fired the rotor 22 will be in the safe position shown in Figures 1 and in which the axis of the bore is offset from the axis A of the Immediately after having been fired the projectile is the rotor 22 being displaced to the rear against the res istance of the spring 29 until the underside 25 of the rotor bottom 24 finds support on face 13 in the body of the When the rotor is thus supported the force of inertia acting parallel to the axis of rotor rotation D at a point offset the axis cannot cause the arbor 27 to bend and the rotor to In the case of a spin stabilised projectile the rotor 22 will be subjected to a further inertial force for as long as the spin of the projectile is The position of the centre of gravity S is therefore so as illustrated in Figure that the tangential component of this inertial force will oppose the thrust of the 29 as well as the centrifugal force The contact pressure between the safety stud 36 and the concavity 39 in the rotor 22 is thus permitting the safety stud 36 to slide reliably rearward into the bore 37 for releasing the rotor If the centre of gravity were located as shown in Figure 6 the tangential component and the centrifugal force would be codirectional and additive and the contact pressure would be The safety stud might thus be fractionally jammed and unable to release the rotor for arming the If the selector pin 57 is turned into position the rotor 22 cannot immediately turn into arming position when the locking pin 36 withdraws the point of the percussion pin 15 is forced by inertia to the rear the socket 62 in the filler When the projectile has left the barrel and forward acceleration ceases spring 29 pushes the rotor 22 forward until the ring 26 bears against the bottom of the bore At the same time the spring 9 the sleeve 8 into its forward position in contact with the shoulder 12 in the fuze head The of the percussion pin is withdrawn from the socket 62 in the filler 61 and the rotor 22 is now free to The spring assisted in the case of spin stabilised projectiles by force turns the rotor 22 Figure out of the into the This rotary motion proceeds at a speed determined by the gear train and escapement lever 68 according to the time the projectile is desired to remain safe after leaving the bore of the When the fuze is armed the cylindrical concavity 39 in the rotor 22 lies adjacent the pinion 63 and the axis of the bore 65 containing the detonator pellet 66 aligns with axis the fuze When the fuze strikes the target the sleeve 8 is pushed into the body of the fuze and the percussion pin 15 penetrates the pellet thereby initiating the of the bursting charge of the through the If the selector pin 57 had been set to as shown in Figure then the percussion pin 15 could not have ignited the pellet 66 upon impact of the After having been released by the safety plug 36 the rotor 22 had turned into armed position in the above manner in which of the second striker pin 46 aligns with the axis of the bore 55 containing the detonator pellet Upon impact the two sleeves 42 and 51 are thrown notwithstanding the braking farce applied to them by the locking balls and the spring 44 is further When the delay of the fuze has nearly expired the spring 44 can move the sleeve 42 backwards and a free space is thus again opened up between the slee e 51 which is in its extreme forward position and the sleeve 42 that is again in contact with the foot of the stem The pressure of the bevel face 50 on the stem 41 now forces the balls 49 into this open thereby releasing the striker pin 46 to be propelled forward by the spring The balls 49 are deflected by the oblique end face 52 on the front sleeve 42 into the interior of the socket 47 in the striker pin which can move forward unimpeded to ignite the detonator pellet This communicates through the space between the rotor 22 and the bottom of the recess 19 with the pellet igniting the latter its flash and thus causing the bursting charge to be insufficientOCRQuality

Claims (5)

WHAT IS CLAIMED ISs

1. An impact fuse for a spin stabilised projectile comprising a body, a carrier for a detonator pelle * said carrier being rota able by spring means from a safe into and its center of gravity not located on the axis of ro ation armed position,/and a safety de ice comprising an axially movable stud, in which the safety stud, in a forward position, is in contact with and locks the pellet carrier in the safe position, the safety stud being dlsplaceable by the acceleration on discharge of the projectile into a rear position in which it releases the pellet carrier, an in which the pellet carrier is constituted and positioned so that the centrifugal force acting on its centre of gravity will bias the carrier for rotation in one direction whilst the inertia1 force due to spin acceleration will bias the carrier for rotation I the opposite direction, thereby reducing the contact pressure be ween the stud and the carrier and so enabling the stud to move reliably rearwards without jamming*

2. An impact fuse according to Claim 1, for use in a projectile stabilised by right hand spin in which the centre of gravity of the pellet carrier is on the right hand side, viewed in the direction of flight, of a line connecting the longitudinal axis of the fuse and the axis of rotation of the pellet carrier, said connecting line subtending an acute angle at the centre of gravity.

3. * An impact fuse according to either of Claims 1 or 2, in which the pellet carrier is axially movably, and has a face on the underside of its rear which is normal to the axis of the fuse and parallel to an adjacent face in the body of the fuse, and which during the acceleration on discharge of the projectile is supported b said latter face*

4. . An impact fuse for projectiles according to any one of the preceding Claims comprising a torsion spring surrounding the axis of rotation of the pellet carrie · in which the torsion spring is axially preeompressed and by bearing agains a ring attached to. its forward end causes the pellet carrier to be biased forwardly so that the ring is the only part of the pellet carrier in contact with the body of the fuse when the carrier rotates*

5. An impact fuse for a s in' stabilised projectile substantially as hereinbefore described with reference to the accompanying drawings* COHEN ZEDEK & SPISBACH P.O. BOX 33116, TEL AVIV. APPLICANT*S ATTORNEYS.