US2463210A

US2463210A - Delayed-action fuse

Info

Publication number: US2463210A
Application number: US741452A
Authority: US
Inventors: Ben W Sewell
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-04-15
Filing date: 1947-04-15
Publication date: 1949-03-01
Anticipated expiration: 1966-03-01

Description

March 1, 1949 B. w. SEWELL DELAYED-ACTION FUSE Filed April 15, 1947 2 Sheets-Sheet 1 w mm w r J an m M F E: F m

' INVENTOR EEK! W. $EWEL v ATTORNEY March 1, 19 49. 3, w s w 2,463,210

DELAYED-ACTION FUSE Filed April 15, 1947 2 Sheets-Sheet 2 i F! 3 24\ v 28- 30 23' 29 A ,W 4 N9. 9 ,2/ k "V ii 35 J 31 34 Q Fm. S-

I2 22 Q i l INVENIOR ATTORNEY Patented Mar. 1, 1949 UNE'FED STATES DELAYED-ACTION FUSE Application April 15, 1947, Serial No. 741,452

2 Claims.

The present invention relates to a delayed action fuse for military missiles; more particularly to a fuse for projectiles used in destroying armored and concrete structures.

An object of the invention is to provide a delayed action fuse for all types of military missiles.

Another object of the invention is to provide a fuse in which the firing pin is cocked upon impact and afterwards fires the primer when the negative acceleration or deceleration of the projectile drops to a selected value as the missile is further retarded during penetration.

A further object of the invention is to provide a fuse which will permit a projectile to penetrate a considerable thickness of armor or concrete before the fuse explodes the bursting Charge within the projectile.

Among the advantages of this invention is the simple construction of this fuse over devices of the prior art. Moreover, deterioration in storage is reduced, inasmuch as none of its mechanical parts other than detent springs, are under any strain prior to being fired and also because the fuse is completely sealed against the elements.

The advantages of the present invention will be best understood in connection with the accompanying drawings:

Fig. 1 is a detailed sectional view of a fuse embodying the invention taken through the axis of the fuse when in the unarmed condition.

Fig. 2 is a similar view of the fuse when the projectile is in flight.

Fig. 3 is a similar View of the fuse at the moment of impact of the projectile on the target.

Fig. i is a similar view of the fuse at an infinitesimally later time.

Fig. 5 is a similar view of the fuse at the moment of firing the primer.

In the preferred embodiment of the invention, the cylindrical fuse body H has an axial bore l2 extending from the rear to the forward edges of the detents 53. The right or rear end of the bore I2 is tapped to receive the primer holder 54 containing detonator or primer l5. Within the bore !2, the cylindrical firing pin it is housed in the cylindrical inertia sleeve l! in a slide fit and locked to this sleeve by a shear Wire E8. The shear wire 18 passes through the holes IS] of the sleeve and 2?: of the firing pin, and each end of the wire is bent over in the annular groove 2i of the inertia sleeve El. The rear face of sleeve I? has a recess of greater diameter than the firing pin is to accommodate the segmental split ring 22. The internal diameter of ring 22 is less than the diameter of firing pin l6, and the ring prevents the point 23 of the firing pin from reaching the primer I5.

The forward end of the fuse body II has a stepped circular recess 24. In the narrower portion of this recess 24 is located a resilient, conical Belleville washer 25 anchored in position by a retaining ring 25 which fits into the stepped or wider portion of the recess 24. An interior partition or flange 2! with an aperture of the same diameter as the interior of sleeve I1 separates recess 2s from the bore 12. Flange 21 serves to limit the throw of the Belleville washer. A flanged guide button 28 is mounted in the center of the Belleville washer 25 and is equipped with a stud 29 projecting to the rear along the axis of the fuse. The stud 29 fits into a counter-sunk guide hole 38 in the forward end of the firing pin it to maintain the pin in alignment. Two or more safety detents l3 bear on the sides of the firing pin l6 in order to prevent the inertia sleeve I? from sliding forward prior to firing the projectile from a gun. Detents l3 are slideably mounted on helical springs 35 in the detent cups 32 and channels 33 radially located in the fuse body II. The entire fuse assembly is inserted in a cylindrical metal cover 34 which is open at one end. The open end is then crimped over the rear base of the fuse body at 35.

Prior to a projectile being fired, the fuse is in the condition shown in Fig. 1. Firing pin [6 and sleeve I! are locked together by shear wire I 8. The point 23 of the firing pin I6 is prevented from approaching primer 15 by the split ring 22. The Belleville washer 25 is in its uncooked. position. Sleeve i? cannot move, as it bears against the primer holder M at the rear and the detents l3 :at the forward end. It is apparent that the fuse in the unarmed condition is absolutely safe with the firing pin separated from the primer by a split ring, locked by a shear Wire and having its driving member, in this case the Belleville washer, uncooked. The only working parts which are stressed in any degree are the detent springs 3| which are under light compression in their extended position.

In the operation of the fuse the projectile containing it is first fired from a gun. Under the influence of the high speeds of rotation caused by the rifiing of the barrel, the detents l3 spin out, that is, they are moved radially outward in the channels 33 and detent cups 32 as shown in Fig. 2. During the flight of the projectile no other action occurs in the fuse mechanism.

The condition of the fuse at the instant of the impact on a target is illustrated in Fig. 3. From the inertial forces resulting from the negative acceleration, firing pm Hi and inertia sleeve 11 move forward as a unit thereby flattening and cocking the resilient Belleville washer 25. In cocking the washer, the mass of both the firing pin l6 and sleeve H is required to overcome the peak resisting force of the washer 25. The firing pin, Bellevillewasher and guide button reach the limit of their travel at this stage but the inertia sleeve only partially completes its travel.

An infinitesimal fraction of a second later, the fuse attains the condition disclosed in Fig. l. Due to inertia, sleeve ll continues forward thereby shearing the shear wire H3. The segments of the split ring 22 are pushed out of the rear recess in the inertia sleeve by reaction against the relatively stationary firing pin 10. Sleeve l1 slides down the bore l2 until it is stopped by flange 2i. Centrifugal force drives the segments of the split -ring 22 outward against the walls of bore I2 where the segments will not interfere in later movement of the firing pin. The fuse which was armed by rotation upon leaving the gun barrel has now been cocked by impact upon a target.

At the-moment of impact the negative acceleration (sometimes referred to as reverse setback) of the-projectile starts at a maximum value and steadily decreases as the projectile penetrates the target and slows down due to the resistance encountered. The negative acceleration decreases to a selected-value whereupon the inertial force of the firing pin [6 is no longer sufficient to hold the-Belleville washer 25 in the cocked position.

As is evident in Fig. 5, the flattened or cocked Washer returns to the conical shape shown in Fig.

-1-sharply driving the firing pin it to the rear ingthe fuse;- that is, by varying the weight of the firing pin and the inertia sleeve or by varying -the-stiffness-f the Belleville washer, it is possible to regulate the depth of penetration in a given material at which detonation of the projectile will occur. While various materials may be employed for the construction of this fuse, metal is preferred because of its strength. As an example, in designing a fuse which will be cocked at a negative acceleration of 2000 times that of gravity (2000 g) and detonate the projectile when this negative acceleration drops to 1500 times gravity 1500 g), a Belleville washer is selected which has a peak or cocking force of 19 pounds and a minimum holding force of 6 pounds, a firing pin weighing 0.004 pound, inertia sleeve Weighing 0.008 pound together with a copper shear wire having a shearing strength of more than 5.5 pounds and less than 8.0 pounds. -With this assembly, upon'impact as in Fig. 3, the combined inertia force of the firing pin l6 and inertia sleeve I1 is 24- pounds which is ample to cock the Belleville Washer against a resistance of 19 pounds.

The forcesinvolved are calculated by the-equation F=ma where F represents force in pounds, m'represents mass in pounds and a represents acceleration in units ofgravity, Thus the firing pin weighing .004 pound multiplied by2000 g "6 pounds.

eXerts a force of 8 pounds, and the sleeve with a mass of .008 pound times 2000 g exerts a force of 16 pounds, when the negative acceleration is 2000 times the acceleration of gravity.

The action shown in Fig. 4 is readily understood by recalling that the inertia sleeve is exerting a force of 16 pounds on a shear wire which hasa shearing strength of between-U 5.6 and 8 pounds and therefore requires: atotaliforce of 11 to 16 pounds to shear the wire at both ends of hole 20 in firing pin I 6.

In the stage illustrated in Fig. 5, the value of negative acceleration drops below 1500 g and the firing pin, which by then is alone holding the washer cocked, will exert a force of less than Since this force is less than the designed minimum holding force of 6 pounds, the Belleville washer reacts and hurls the firing pin to the rear with a net force of about 13 pounds (19 pounds less the inertia force of approximately 6 pounds which is exerted. by. the ifirin'gupin in a forward direction) The Bellevillewasher ofthe present -example has a total travel of. .050'-*between' the relaxe'd ornormal position and the cooked position." A gap of .025" is used between the point 23 ofthe firing pin and the forward end of the primer fi. Accordingly, the firing pin travel is -in-excess' of .075"'and all travel in excess of '.050"""is--"overtravel. The firing pin derives suflicient'momentum toaccomplish this overtravel and-also to-set off the primer from the force applied'by the-Belle,- ville washer.

The fuse of' the invention, although'particularly intended for use againstconcrete fortifications, may be used with equal successagainststeel and other varieties ofarmor. In addition to'the particular application shown for rotatinglprojectiles, in place of the radial detents, the fuse could be readily adapted for other types ofmilitary missiles of the non-rotatingkind by substituting an,- other arming device. Fuses for. bombs,...mortar shells and rockets are obviously within thescope of the invention. Thus it is evident thatthe device disclosed is capable of aw-ideevariety-of applicationsasa delayed action fuse.

Accordingly, it is to be understoodswthatathe invention is limitedonly by the-scope of athe-xappended claims and not to the preferred embodi'e ment disclosed.

What is claimed is:

1. In a delayed-action fuse, az fusezrbodym rovided with a longitudinal boregarprimer at -the rear end of the-bore. a;firing'pin.assembledi;wi thin and joined by a shear member to aninerti'a-sleeve located inside the bore, asegmental ring'looateel in a recess. the rearend '-of-the sleeve a'nd adapted to separate the -fir-ing"' pi-n and -theprimer; a safety detent extending'radially into the bore to prevent forward'movement of the-sleeve and displaceable by'centrifugal force, aresilient conical washer adjacent the-forward end of the firing pin and adapted" to be fiattened by a force' and maintained fiat bya lesser force ,=-whereby-,upon rotation the detent" is. displaced from-' thewore thereby arming the fuse, thereafter-uponimpact the inertia of said firing pin and sleeve assembly carries it forward to flatten theresilient washer with the'sleeve continuing forward 'to shear the shear member-and. displace the segmental 'ring from said'irecess: thereby. cocking the "fuse,'- and thereafter upon reductionof th /negative acceleration to a predetermined value the resilient washer resumes-its normal conical-shape -thereby driving the firing pin into contact with the primer to detonate the fuse.

2. A fuse for a missile that spins when fired from an ordnance piece, and comprising a firing pin, a primer, spacing means holding said pin out of contact with said primer, a snap spring normally urging said pin toward said primer, locking means normally preventing movement of said pin toward said spring, but releasing said pin due to centrifugal force when the fuse spins, a slidable 10 turn motion of the firing pin into the primer under the urging of the snap sprin under further negative acceleration will be removed.

BEN W. SEWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,309,768 Newell July 15, 1919 1,385,610 Flam July 26, 1921 15 2,336,701 Rasmussen Dec. 14, 1943 FOREIGN PATENTS- Number Country Date 188,377 Great Britain Nov, 6, 1922