US 3848531 A
A self-destruct fuze comprises inner and outer rotors mounted in a housing for rotation relative to each other and the housing and having safe, armed and fired positions, a primary lead carried by the housing, a detonator carried by the outer rotor, inertia and spin-actuated detents for releasably locking the rotor together prior to spin decay, a detent ball holding the key in locking position prior to launch, a spin-actuated lever geared to the inner rotor and retarded by a timing mechanism for rotating the two rotors against a spring biased from an outer safe position, where it is initially held by the outer rotor, to an inner firing position in line with the detonator, to be struck thereby when the outer rotor is released from the spin key during spin decay and rotated by its spring to fired position.
Description (OCR text may contain errors)
United States Patent [1 1 Mellen 1 SELF-DESTRUCT FUZE  Inventor: George P. Mellen, Wayzata, Minn.
 Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC,
 Filed: Oct. 30, 1973  App1.No.: 41l,107
 US. Cl. 102/70 R, 102/71, 102/80  Int. Cl. F42c 9/04  Field of Search 102/70, 71, 80, 79, 78
 References Cited UNITED STATES PATENTS 2,943,573 7/1960 Graser 102/78 X 3,465,676 9/1969 Simmen 102/80 3,724,384 4/1973 Donahue 102/79 3,786,759 1/1974 Mellen et al 102/80 X Primary Examiner-Samuel W. Engle Attorney, Agent, or Firm-Edward J. Kelly; Herbert Ber]; Thomas R. Webb Nov. 19, 1974  ABSTRACT A self-destruct fuze comprises inner and outer rotors mounted in a housing for rotation relative to each other and the housing and having safe, armed and fired positions, a primary lead carried by the housing, a detonator carried by the outer rotor, inertia and spin-actuated detents for releasably locking the rotor together prior to spin decay, a detent ball holding the key in locking position prior to launch, a spin-actuated lever geared to the inner rotor and retarded by a timing mechanism for rotating the two rotors against a spring biased from an outer safe position, where it is initially held by the outer rotor, to an inner firing position in line with the detonator, to be struck thereby when the outer rotor is released from the spin key during spin decay and rotated by its spring to fired posi- Hon.
9 Claims, 8 Drawing Figures PATENTE NOV 1 9 I974 SHEET 2 0F 2 IIIIIHI FIRED SELF-DESTRUCT FUZE BACKGROUND AND SUMMARY OF THE INVENTION An explosive projectile or shell is normally provided with a high explosive charge and some form of fuze which is designed to detonate the explosive charge when the shell impacts, or reaches the vicinity of the desired target.
Problems arise when the shell fuze, for some reason, fails to function in the target area, and the shell becomes a dud. Not only has the shell failed to accomplish its intended mission, e.g. to destroy or damage equipment of the enemy and/or to inflict casualties on enemy personnel, but also the dud may be salvaged and re-used by the enemy.
Therefore, an object of the present invention is to prevent, or at least minimize, the production of duds by providing the shell with a seIf-destruct fuze. This fuze could be the only fuze carried by the shell, but preferably, is a back-up fuze for the main fuze. The main fuze may, for example, be a point detonating, or impact type, fuze. On the other hand, the self-destruct fuze of the present invention responds to a different environmental element, namely spin decay.
The self-destruct fuze comprises a housing containing a primary lead, first and second arming rotors rotatably mounted in the housing relative to each other and the housing and having safe, armed and fired positions, means releasable during launch for locking one rotor in the housing in safe position prior to launch, spinactuated means for locking the rotors against relative rotation prior to spin decay, spring means normally biasing the second rotor toward the safe and fired positions, spin-actuated means for rotating the first rotor, against the spring means, from the safe position to the armed position after release of the releasable locking means, a detonator carried by the second rotor, a firing member mounted in the housing in positionto be struck by the detonator when the spring means rotates the second rotor from the armed position to the fired position after release of the second rotor from the spinactuated locking means during spin decay, and an explosive lead connected between the detonator and the primary lead when the detonator is in fired position.
In the embodiment illustrated, both inertia and spinactuated releasable locking means are provided. The spin-actuated locking means is a cylindrical key having a slot forming a D-section engaging the two rotors and a spin arm held in locking position prior to launch by a detent ball and during spin by centrifugal force. The spin-actuated rotating means is a spin-actuated lever having a gear meshing with another gear on the first rotor. The gear rotation is retarded by a star gear and associated pallet. The firing member is a lever pivoted in the housing and having a firing pin which is initially held in a safe position by a portion of the second rotor, and spring-biased during the arming operation to a firing position in-line with the detonator.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a top plan view of a fuze embodying the present invention in the safe condition, with the end plate removed.
FIG. 2 is an axial section view taken on line 22 of FIG. 1, with the end plate in place.
FIG. 3 is a similar view taken on line 3-3 of FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1-8 illustrate, for example, a fuze 1 embodying the present invention. Fuze 1 comprises a cylindrical body 3 with an end plate 5 attached thereto and an axial primary lead tube 7 containing a primary lead 9. The ends of tube 7 may be open and aligned with an opening 10 in end plate 5, as shown, if the fuze l is to be inserted serially between a point-detonating fuze and a booster device.
Rotatably mounted on the upper end of the lead tube 7 is a first arming rotor 11 having an external gear 13 on the lower end. Rotatably mounted on rotor 11 is a shorter second arming rotor 15. Relative rotation between the two rotors 11 and 15 is prevented in the safe and armed condition of FIGS. 1-4 and FIGS. 5 and 6, respectively, by a cylindrical spin key 16, having a notch 17 which leaves a D-shaped key section 18, rotatably mounted in substantially semi-cylindrical mating grooves 19 in the rotors 11 and 15 (see FIGS. 2 and 4). The lower end of key 16 extends into an arcuate recess 20 in body 3 and has an L-shaped arm 21 having an end surface 21' which, in the safe condition, engages a ball 22 at one end of a groove 23 of a semicircular cross section in body 3, to prevent inward movement of arm 20 (FIG. 4). Ball 22 is held within recess 23 by a quarter-circular groove 24 in rotor 15.
Rotor 15 is biased counter-clockwise (as seen in FIG. 1) in body 3 by a coil arming spring 25 seated in a chanml 26 in the rotor and abutting a stop pin 27 mounted in a support piece 28 attached to body 3. Prior to launch of the projectile containing the fuze, rotor 15 is locked against rotation by a spring-pressed axial detent 29 mounted in the rotor and extending into a hole 31 in end plate 5 (FIG. 3). At launch, the detent 29 releases rotor 15 by inertia.
Prior to launch, and during launch prior to achievement of a predetermined spin velocity, the rotor 15 is also locked to body 3 by two spin detent levers 33 pivoted on piece 28 and spring-biased into locking engagement with two notches 35 and 36 in rotor 15 (FIGS. 1 and 2).
At a predetermined point during spin-up, the detent levers 33 swing out due to centrifugal force and release the rotor 15. After such release, the rotor 15 is rotated clockwise, from the safe condition of FIGS. l-4 to the armed condition of FIGS. 5 and 6, by a spin-actuated arming lever 37 having a pivot stud 38 pivoted on body 3 and a drive gear 39 meshing with gear 13 of rotor 15 (FIGS. 2 and 4). This rotation is retarded during a predetermined time by a star wheel 41, having a small gear 42 driven by gear 39, and a pallet 43 engaging the star teeth of wheel 41.
As shown in FIGS. 1, 5, 7 and 8, a combustible or explosive lead 45 extends radially through the rotor 11 and tube 7, to the primary lead 9. An explosive detonator 47 is carried by rotor 15, in a position out-of-line with lead 45 in the safe and armed conditions (FIGS. 1 and and in-line therewith in the fired condition (FIG. 7). A firing pin lever or hammer 49 has a pivot stud 51 extending through a clearance slot 53 in rotor and into a pivot hole (not shown) in end plate 5. Lever 49 comprises a conical firing pin 54 and an arcuate control arm 55 which has a side surface 56 that engages an outer shoulder 57 on the rotor 15 in the safe condition of FIGS. 1-4 and initially holds the firing pin 54 out-ofline with the detonator (FIGS. 1 and 2). In the armed and fired conditions, arm 55 fits within a shaped recess 58 in the upper edge of rotor 11.
In operation, prior to launch, the parts of the fuze are held in their safe positions of FIGS. 1-4, as described above. At launch, the inertia detent 29 and spin detent levers 33 release the rotor 15. Then, the arming lever 37, actuated by spin, rotates the two rotors 11 and 15, which are locked together by key 16, for approximately 60, to the armed position of FIGS. 5 and 6, compressing spring 25, and retarded by star wheel 41 and pallet 43. During this rotation, the firing lever 49, when released from surface 57 of rotor 11, is pivoted inwardly to firing position by its spring, positioning arm 55 in recess 58. Also, ball 22, which initially blocked surface 21' of the arm 21 of spin key 16, moves by spin and centrifugal force along groove 23 and into a radial recess 59 connected therewith, leaving the spin key held in position only by spin.
Upon spin decay, when the restoring force of the arming spring exceeds the spin force on the spin key 16, the spin key 16 is rotated counter-clockwise by rotor 15, releasing the rotor 15 and permitting it to be driven counter-clockwise by spring 25, snapping the detonator 47 against the firing pin 54. When the detonator 47 strikes the firing pin 54, as shown in the fired condition of FIG. 7, the detonator is aligned with the lead 45, thus the firing train to the primary lead 9 is completed by the final rotation of rotor 15.
What is claimed is:
1. A-self-destruct fuze for a spin-type projectile, comprising:
a housing including a hollow cylindrical body adapted to be mounted in said projectile with its longitudinal axis coincident with the spin axis of the projectile, and a cover plate attached to the forward end of said body,
a'primary lead tube containing an explosive primary lead axially mounted in said body, at least the rear end of said tube being open for exposing said primary lead to an explosive charge in said projectile,
a firing arming rotor rotatably mounted on said tube,
a second arming rotor rotatably mounted on said first rotor, said rotors having safe, armed and fired positions,
means releasable during launch for locking one rotor against rotation relative to said housing prior to launch,
spin-actuated means for locking said rotors against relative rotation prior to spin decay in said safe and armed positions,
springs means normally biasing said second rotor toward said safe and fired positions,
spin-actuated means for rotating said first rotor against said spring means from said safe position to said armed position after release of said releasable locking means,
an explosive detonator carried by said second rotor,
21 firing member mounted in said housing in position to be struck by said detonator when said spring means rotates said second rotor from said armed position to said fired position after release of said second rotor from said spin-actuated locking means during spin decay, and
an explosive lead in said first rotor aligned with said detonator and said primary lead when said detonator is in said fired position.
2. A self-destruct fuze as in claim 1, wherein said releasable locking means comprises a spring-biased detent on said second rotor engaging a hole in said housing and released by inertia at launch.
3. A self-destruct fuze as in claim 1, wherein said releasable locking means comprises two detent levers pivoted in said housing, spring-biased into engagement with detent notches in said second rotor, and released by centrifugal force during spin-up at launch.
4. A self-destruct fuze as in claim 1, wherein said spin-actuated locking means comprises a spin key including a D-shaped body section rotatably mounted in mating semi-cylindrical grooves in said rotors and a spin arm adapted to maintain said key in locking position during spin by centrifugal force.
5. A self-destruct fuze as in claim 4, wherein said spin key is held in its rotor locking position prior to launch by means of:
complemental arcuate grooves in said housing and said second rotor, and
a detent ball located in one end of said grooves and engaging said spin arm in said safe position of said second rotor.
6. A self-destruct fuze as in claim 1, wherein said spin-actuated rotating means comprises:
a first gear on said first rotor, and
a spin-actuated arming lever pivoted in said housing and including a second gear meshing with said first gear.-
7. A self-destruct fuze as in claim 6, wherein said spin-actuated rotating means further comprises a delay means including a star wheel geared to said second gear, and a pallet engaging the star teeth of said star wheel.
8. A self-destruct fuze as in claim 1, wherein said firing member comprises a lever having one end pivoted in said housing and a firing pin at the other end movable between a safe outer position in which said firing pin is positioned out of the path of said detonator and an inner firing position, and spring means biasing said firing pin toward said firing position.
9. A self-destruct fuze as in claim 8, wherein said lever comprises a surface that engages a shoulder on said second rotor to maintain said firing pin in said safe position prior to the rotation of said second rotor to said armed position.