Fuze Setback And Angular Acceleration Detent

Abstract

A safety fuse is shown incorporated in rocket propelled round of ammunition. Two complementary mechanisms act upon a slider to maintain it in a position wherein a primer charge therein is out of register with a firing pin. When the round of ammunition is discharged from a gun, linear and angular acceleration are effective on a locking ball to overcome the action of a spring and disengage the ball to overcome the action of a spring and disengage the ball from a notch in the slider's guideway. Angular acceleration of the round causes the ball to roll into a laterally extending position in the slider. After discharge from the gun, centrifugal force disengages two plungers from the slider permitting it to travel laterally bringing the primer charge into register with the firing pin.

Description

The present invention relates to improvements in safety fuzes for ammunition.

Safety fuzes for ammunition have attained a high degree of reliability in preventing inadvertant detonation. This is particularly true of known fuzes which comprise a pair of spring loaded plungers that maintain a slider in a "safe" position. When a predetermined spin rate is attained, centrifugal forces cause the plungers to release the slider allowing it to travel to an "armed" position in which a primer charge is brought into register with the firing pin of the fuze. The firing pin will then impinge the primer charge to detonate the ammunition, upon impact with a target.

One object of the present invention is to provide a complementary mechanism, compatible with the above-described type of safety, which will be responsive to other than centrifugal force and prevent inadvertant arming of a fuze in the remote and unlikely event the spring loaded plungers are inoperative for that purpose.

In its broader aspects, the invention has for its object, the provision of a simple inexpensive and highly reliable safety mechanism for preventing inadvertant arming of fuzes employed to detonate ammunition.

These ends are attained in a fuze construction wherein a locking element is resiliently maintained in a locking position to prevent lateral movement of a slider from a "safe" position in which operative contact between a firing pin and primer charge is prevented. The locking element, preferably in the form of a ball, is displaced from its locking position by linear acceleration and maintained so displaced by rotational acceleration of the round of ammunition in which the fuze is incorporated.

While the described safety mechanism can be used independently it cooperates uniquely in a construction wherein spring loaded plungers also prevent movement of the slider from its "safe" position until a predetermined rate of spin has been imparted to the round of ammunition as evidenced by the centrifugal force required to disengage the locking plungers.

The above and other related objects and features of the invention will be more fully apparent from a reading of the following description of the accompanying drawing and the novelty thereof pointed out in the appended claims.

In the drawing:

FIG. 1 illustrates a round of ammunition in which a fuze of the present invention is embodied;

FIG. 2 is a longitudinal section, on an enlarged scale, through the fuze identified in FIG. 1;

FIG. 3 is a section taken on line III--III in FIG. 2, illustrating the "safe" position of the fuze;

FIG. 4 is a section taken on line III--III in FIG. 2, illustrating the "armed" position of the fuze;

FIG. 5 is a section taken on line V--V in FIG. 3; and

FIG. 6 is a section taken on line VI-VI in FIG. 3.

While the present invention may be employed in fuzes, for a wide variety of ammunition, certain aspects are particularly applicable to the type of ammunition illustrated by the round 10 and seen in FIG. 1. The round 10 comprises an igniter 12, a rocket motor 14, a fuze 16, a warhead 18 and a ogival cap 20.

Such a round is fired from a rifled barrel by igniting a prime in the igniter 12 to initiate combustion of a solid propellant in the rocket motor 14. The gases generated in this fashion accelerate the round through the barrel as an initial spin is imparted to it by the rifling of the barrel. After discharge from the barrel the round is further accelerated by the rocket motor and additional spin is imparted to the round of discharge of hot gases through tangential spin ports 22. Thereafter, the fuze 16 detonates the warhead 18 upon impact with the target.

The fuze 16, now to be described, provides two complementary mechanisms for preventing inadvertent detonation of the warhead. Referencing FIGS. 2 and 3, the fuze 16 comprises a container 24 having a flange 26 which is spun inwardly to retain a body member 28. The safety and firing elements of the fuze are contained within the chamber formed by the container 24 and body member 28.

A slider 30 is retained in a symmetrical radial slot 32, formed in the body member 28 by a plate 33. The slider carries a primer charge 34 which in the "safe" position of the fuze, is maintained out of register with the path of travel of a firing pin 36. The slider 30 is held in this "safe" position by a pair of locking plungers 38 which are respectively urged into notches 40, on opposite sides of the slider by springs 42.

A slot 44 is formed in one side of the slider 30 and receives a ball 46. A leaf spring 48 maintains the ball 46 in a recess 50 (FIGS. 5 and 6) formed in the body member 28. The spring 48 is of simple construction having one bent end 52 positioned by a hole in the slider 30 with its other end 54, being reversely folded within a slider slot 56 to overlie the ball 46. The ball 46 thus provides a second means for preventing inadvertent displacement of the slider 30 to its "armed" position.

A second ball 58 is carried within a slot 60, formed in a slider 30, opposite the slot 44. The purpose of this second ball will be described later.

The firing pin 36 is mounted on a weight 62 and is biased from the slider 30 by a spring 64. The firing pin 36 travels in a generally axially direction, passing through an opening 66 in the retaining plate 33. A recess 68 in the slider 30 is registered with the firing pin 36 in the safe position of the fuze. The firing pin thus will not be damaged in the event it is thrown forwardly during handling or otherwise when the slider 30 is in its "safe" position.

In normal use the round of ammunition 10 would be loaded into a gun barrel with the fuze 16 in its described "safe" position. Upon firing of the igniter 12, the round will be accelerated both linearly and angularly as it is discharged along the gun barrel. The linear acceleration of the round will cause the ball 46 to deflect the free end 54 of the leaf spring 48 as the ball 46 is moved out of the body member recess 50. The angular acceleration of the round will cause the ball 46 to then roll within the slot in or passageway 44 toward the sidewall of the slot 32. As this occurs, the free end 54 of the leaf spring 48 will return toward its original position preventing the ball 46 from reentering the recess 50. The described movement of the ball 46 is best shown by the phantom line positions in FIG. 6.

In the environment of a rocket powered ammunition round, it is preferred that the described release of the safety provided by ball 46 occur within the limits of the rounds travel through the gun barrel.

After discharge from the barrel the round is further accelerated both linearly and angularly by the rocket motor. When the resultant centrifugal forces reach a predetermined level, the spring forces on locking plungers 38 are overcome and then they are withdrawn from the notches 40. The slider 30 has a greater mass at its upper end so that, it will be displaced by centrifugal force to the "armed" position of FIG. 4 once the plungers 38 have been so withdrawn. The balls 46, 58 are thrown by centrifugal force, into notches 70, formed in the sidewalls of slot 32, to lock the slider 30 in this armed position.

When the round 10 hits its target, the firing pin will be thrown forward to strike the primer charge 34, thus providing a high energy discharge which passes through an explosion 72 in the body member 28 to detonate the warhead 18.

The described safety action of the ball 46 is particularly suited to use in combination with a safety of the type provided by the plungers 38 in that it imposes a maximum number of force loadings which must be imposed in a proscribed sequence before the fuze is armed. Such loadings and sequence are virtually impossible to obtain except in actual firing of a round of ammunition. Therefore, an ultimate measure of safety is provided.

While it is extremely unlikely, if the locking plungers 38 failed to perform their safety function, the ball 46 would be capable of providing a fully adequate measure of safety. Thus it will be apparent that the described safety functions of the ball 46 will be adequate, per se, for the requirements of many types of ammunition.

In this connection it should be noted that the ball must be subjected to both linear and angular acceleration before it can be displaced to permit arming of the fuze. Not only is it unlikely that both such forces would occur in ordinary handling of ammunition or even accidental mishandling, it is further unlikely that they would occur with a magnitude comparable to those generated in the discharge of ammunition. Beyond this the linear force to displace the ball 46 may be in an opposite direction, as described, to that required to cause the firing pin to impact the primer charge. With this in mind it could be advantageous to have the leaf spring return the ball 46 into the locking recess 50 if there is not sufficient centrifugal force, in addition to linear and acceleration, to arm the fuze.

This and other modifications of the described and preferred embodiment of the invention will occur to those skilled in the art within this scope of the inventive concepts which are delineated by the following claims.

Claims

Having thus described the invention what is claimed as novel and desired to be secured by Letters Patent of the United States is:

1. A fuze for incorporation in a round of ammunition which will be linearly and angularly accelerated, relative to a central spin axis, when discharged from a gun, said fuze comprising:

a slider;

housing means including a guideway receiving said slider for movement in a path transverse to said spin axis;

a primer charge;

an igniting means;

means for lockin said slider in a "safe" position preventing operative contact between the igniting means and the primer charge;

said locking mean comprising:

a locking element partially engaging said slider and said housing means and maintaining the slider in said "safe" position;

a reversely folded leaf spring anchored in said slider, effective on said locking element in the same direction as the round of ammunition is to be linearly accelerated, for maintaining the locking element in its locking position;

said slider having a passageway transverse to said guideway and receiving said locking element when the locking element is displaced from its locking position against the action of said resilient means, upon linear acceleration of said ammunition round;

whereby the locking element will only be displaced from its locking position by a predetermined linear acceleration and only maintained so displaced in said slider passageway by angular acceleration, thereby permitting movement of the slider from its "safe" position only under conditions encountered in discharge of the round of ammunition from a gun.

2. A fuze as in claim 1 wherein the locking element is a ball.

3. A fuze as in claim 1 wherein:

the slider has a greater mass on one side of the spin axis,

whereby when the locking element is displaced from its locking position the slider may be displaced by centrifugal force from its "safe" position to a position permitting operative contact between the igniting means and the primer charge.

4. A fuze as claim 1 further comprising:

a plunger; and

resilient means urging said plunger radially inwardly, relative to said spin axis, against the side of said slider in said "safe" position,

thereby providing additional means for retaining said slider in its "safe" position, which means will be released only upon a spin rate producing a predetermined centrifugal force.

5. A fuze as in claim 2 further comprising:

a pair of plungers;

resilient means respective urging said plungers radially inwardly, relative to said spin axis, against opposite sides of said slider in said "safe" position;

thereby providing additional means for retaining the slider in its "safe" position, which means will not be released upon a radial loading in only one direction relative to said spin axis.

6. A fuze as in claim 5 wherein the resilient means acting upon the locking element comprise:

a reversely folded leaf spring anchored in said slider; and

the slider has a greater mass on one side of the spin axis;

whereby when the locking element is displaced from its locking position and the plungers are displaced from retaining contact with said slider, the slider may be displaced, by centrifugal force from its "safe" position to a position permitting operative contact between the igniting means and the primer charge and wherein said locking element now locks said slider in the armed position.