US2978982A

US2978982A - Magnetically delayed arming device for a fuze

Info

Publication number: US2978982A
Application number: US382015A
Authority: US
Inventors: Bianchi Renato
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-09-23
Filing date: 1953-09-23
Publication date: 1961-04-11
Anticipated expiration: 1978-04-11

Description

April 11, 1961 R. BIANCHI 2,978,982

MAGNETICALLY DELAYED ARMING DEVICE FOR A FUZE Filed Sept. 23, 1953 2 Sheets-Sheet 1 FIG.2. zl 1 16. 3. 2|

INVENTOR RENATO BIANCHI- 'ATTORNEYS April 11, 1961 R. BIANCHI 2,978,982

MAGNETICALLY DELAYED ARMING DEVICE FOR A FUZE Filed Sept. 25, 1953 2 Sheets-Sheet 2 INVENTOR RENATO BIANCHI ATTORNEYS MAGNETICALLY DELAYED AG DEVICE FOR A FUZE Renato Bianchi, Laurel, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed Sept. 23, 1953, Ser. No. 382,015

7 Claims. (Cl. 102-79) (Granted under Title '35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a fuze and more particularly to a delayed arming device for a fuze adapted for use in various types of ordnance missiles such, for example, as both small and large caliber projectiles.

Prior art delay arming devices such, for example, as the type employing rotors actuated to an armed position in response to frictional and inertia forces and the type actuated by escapement devices have not proven entirely satisfactory for the reason that the devices depending upon the aforesaid forces have not given reproduce'able results and sufiicient time delay periods to meet the desired requirements and the escapement devices often times being erratic in operation due to the faulty functioning of the delicate and intricate mechanisms thereof.

In view of the foregoing, the present invention contemplates the provision of a new and improved rotor device for a fuze adapted to overcome the objectional characteristics heretofore encountered in prior art devices of this type by providing simpleand efficient damping means which delays the movement of the arming rotor from an initial position to an armed position to meet the desired requirements and which is void of delicate and intricate mechanisms.

Moreover, the arming device comprises a magnetized ball rotatably supported within a spherical cavity formed in aconductive housing, the ball rotor carrying a detonator and, if desired, suitable centrifugally actuated locking detents may be employed, to maintain the rotor in an initial safe position. In response to the spin of the projectile, however, the rotor is adapted to be moved from an unarmed position to an armed position. In accordance with the present invention, however, as the ball moves toward an armedposition in response to centrifugal force eddy-currents are induced in the conductive casing in response to such movement. These eddy-currents create a force proportional to the relative velocity of the rotor and casing which opposes the force tending to move the rotor thus retarding the movement of the rotor to an armed position. When the rotor has been moved to an armed position, the detonator is in alignment with the percussion primer and the lead-in charge and provides a continuous firing train from the primer to the usual booster charge mounted in the fuze casing, the explosive charges being fired in successive. order as the firing pin is forcibly driven into engagement with the aforesaid primer. 7

An object of the present inventionis to provide anew and improved delayed arming device for a fuze.

. Another object of the invention is the provision of a' magnetic damping means for delaying" the arming of a projectile fuze.

Still anotherobject of the invention is the provision of a new and improved magnetic damping device wherein an arming rotor'is subjected to adamping action as'the Patented Apr. 11, 196.1

rotor is rotated in a conductive casing thereby to prevent premature arming of a fuzed projectile.

A still further object of the-invention of a new an improved magnetic damping device for a fuze which is economical to manufacture, reliable in operation and which possess all the qualities of durability in service.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is a longitudinal section of a fuze illustrating a preferred embodiment of the present invention arranged therein with the arming rotor thereof in an unarmed position;

Fig. 2 is a view in diagrammatical form of the delay device of Fig. 1 with the ball arming rotor thereof in an unarmed position; 1

Fig. 3 is a view similar to Fig. 2 with the device in an armed position; V i

Fig. 4 is a longitudinal sectional view of a fuze illustrating an alternate arrangement of the present invention;

Fig. 5. is a view in diagrammatical form of arrangement of the device of Fig. 4 with the cylindrical rotor thereof in an unarmed position; and I Fig. 6 is a view similar to Fig. 4 with the rotor in armed position.

Referring now to the drawings and more particularly to Fig. 1 thereof, the numeral 10 generally indicates a fuze comprising, a casing 11 threaded as at 12 for attachment to an explosive shell. The casing 11 is provided with a centrally disposed bore 13 terminating in a restricted bore '14. Bore 13 is threaded as at 15 for threaded engagement with a container 16 having a booster charge 17 arranged therein and bore 14 having an impact responsive firing pin 18 releasably supported therein by a support 19.

The device of the present invention is arranged within the bore 13 and is generally indicated by the reference character 21. The aforesaid device comprises a magw netized casing 22 composed of any siutable electroconductive paramagnetic material such, for example, as iron or the like and having a spherical cavity or recess 23 formed therein. The cavity 23 communicates with a well 24 formed in the casing 22 at one end thereof and with a bore 25 formed in the other end thereof, The well 24 is threaded as at 26 for threaded engagement with a plug or retaining element 27. The bore 25 has arranged therein a percussion primer 28 in alignment with the firing pin 18 and a lead-in charge 29 disposed within a bore 31 formed in the plug 27, the charge 29 being in engagement with the booster charge 17.

A magnetized spherical rotor 32 is rotatably supported within the spherical recess 23 of the casing 22 and a complementary spherical recess 33 formed in the plug 27, the ball being adapted to be rotated from an initial safe position, Fig. 1, to an armed position, Fig. 3, as the rotor is moved in response to centrifugal force during the spin of the projectile along its trajectory. The ball rotor 32 is provided with a-centrally disposed bore 34 extending therethrough in which is arranged a detonator 35 normally out of alignment with the foresaid primer when the rotor is in the initial safe position, Figs. 1 and 2. It will be noted that the ball 32, Fig. 2, is arranged within the rotor casing 22 with the magnetic south pole on the rotor disposed opposite the magnetic north pole on the casing and the magneticnoith pole on the rotor disposedoppositc the magnetic south pole on the casing.

Thus by this arrangement, the rotor is initially mainrotor in an initial safe position and to release the rotor for rotation to an armed position, may be omitted.

It will be understood, however, that as the missile spins along its trajectory the rotor 32 is rotated within the aforesaid spherical recesses in response to centrifugal force. Such movement of the rotor within the conductive casing assembly induces eddy-currents and these eddy-currents create an electromagnetic force, proportional to the relative velocity of the members, opposing the centrifugal force tending to move the rotor from an initial safe position to an armed position thus re tarding the rate of movement of the rotor. While the aforesaid device has been described in connection with a magnetized rotor disposed within a magnetized casing as illustrated, it will be understood that the same results may be obtained by employing a non-magnetized rotor disposed within a magnetized casing or by having the rotor magnetized and casing non-magnetized. 7

Referring now to an alternate arrangement ofthe device illustrated in Figs. 4 to 6 and more particularly to Fig. '4 thereof, the numeral 38 generallyindicates the rotor device. The device is arranged in the fuze housing 40 and comprises a casing 41 composed of suitable conductive material such, for example, as iron or the like and having arranged therein a rotor support or base 42 for rotatably supporting a magnetized wafer or disc type arming rotor 43 as by a shaft 44 carried thereby. In this arrangement it will be noted that the rotor 43 is maintained in an initial safe position by a pair of oppositely disposed centrifugally actuated detents 46 disposed within a pair of notches, respectively, formed in the rotor. The detents are pivotally mounted on the base 42 as at 47, each detent being maintained in engagement with the notches by a spring 48.

As the projectile is fired from a gun and during the angular acceleration thereof the inertial force of the rotor moves the rotor angularly sufficiently to disengage the detents from the notches and to wind at torsional spring 49 secured to the rotor and base. When the angular acceleration of the projectile has disappeared and before the detens are returned to an initial position by the springs, the spin of the projectile is sufiicient to maintain the detents in a release position with the detents out of engagement with the notches. With the detents out of engagement with the notches the arming rotor is free to be rotated to an armed position by the aforesaid torsional spring 49. It will be understood, however, that the rotor is first moved in one direction to a release position by the inertial force thereof in response to the initial angular acceleration of the projectile and thereafter moved in a reverse direction to an armed position, Fig. 6, by the spring 49.

When the rotor 43 is in the initial safe position, Fig. 5, it will be noted that the detonator 51 carried thereby is normally out of alignment with the electroresponsive detonator 52 mounted in the base 42. Upon release of the rotor, however, the rotor is moved to an armed position, Fig. 6, in the aforesaid manner with the detonator 51 in alignment with the detonator or primer 52 and the rotor locked in the armed position by the aforsesaid detent and notch arrangement.

Furthermore, when the rotor moves to an armed position the detonator 51 in the rotor moves into alignment with a lead-in charge 55 arranged in the casing 41 in engagement with a booster charge 57 and'thus a con tinuous explosive train is provided from the detonator 51 to the booster charge 57.

The movement of the rotor to a release position and to an armed position is controlled by a stop pin 58 carried by the rotor and disposed in a substantially semicircular slot 59 formed in the base 42, Figs. and 6.

It will be understood, however, that during the rotation of the magnetized rotor 43 within the conductive casing 41 by the action of spring 49, eddy-currents are induced in the casing and these eddy-currents create a force retarding the rotor thereby delaying the arming of the fuzed projectile.

Furthermore, the aforesaid device is particularly adapted to use in connection with electric control fuzcs such, for example, as the type which fire in response to an electrical impulse generated or a voltage discharged from a storage device as the projectile strikes the target or the type which fires in response to an electrical impulse induced therein when the projectile is in proximate relation with respect to the target.

In view of the foregoing, it will be apparent that a new and improved delayed arming device has been devised for use with an ordnance missile. wherein magnetic damping means are provided for retarding the movement of the arming rotor thereof from an initial position to an armed position and which is economical to manufacture, reliable in operation and which possesses all thc qualities of durability in service.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A delayed arming device for a spin projectile com prising a casing composed of magnetic material having north and south magnetic poles in a plane normal to the axis of spin of the projectile, a magnetic rotor disposed within said casing and having north and south poles aligned with and in opposition with the magnetic poles on said casing for maintaining the rotor in an initial safe position in response to the magnetic flux therethrough, said rotor being adapted to be moved from said initial safe position to an armed position in response to centrifugal force, the movement of the magnetic rotor within said magnetic casing inducing eddy-currents to retard movement of the rotor from said initial position to said armed position.

2. A delayed arming device for a spin projectile comprising a casingcomposed of conductive material, a magnetic rotor movable within said casing, means for locking said rotor in an initial safe position and for releasing the rotor for rotation to an armed position as the rotor is moved a predetermined amount to'a release position in response to the initial angular acceleration of the projectile as the projectile is fired from a gun, resilient means operatively connected to said rotor for rotating the rotor from said release position to an armed position when the spin of the projectile has decreased to a predetermined value, the movement of said rotor from said release position to said armed position being retarded by the eddycurrents induced in response to the rotation of said magnetic rotor within said conductive casing.

3. A delayed arming device for a spin projectile Oil1- prising a casing composed of conductive material, a magnetic rotor normally locked within said casing in an initial safe position and moved to a release position in response to the initial acceleration of the projectile as the projectile is fired from a gun, means responsive to centrifugal force for locking said rotor in said initial position and for releasing the rotor for rotation from said initial position to an armed position as the locking means is moved to a release position by said force, resilient means operatively connected to the rotor for rotating the rotor from said release position to an armed position, said movement of the magnetic rotor within the conductive casing inducing eddy-currents to retard rotation of the rotor from said release position to said armed position, and means on said locking means for urging the locking means into locking engagement with'the rotor as the spin of the projectile reaches a predetermined value and the rotor is in said armed position.

4. A delayed arming device for a spin projectile comprising a. casing composed of 'magnetic material and magnetically poled in a plane normal to the axis of spin of the projectile, and a movable magnetically poled ele ment disposed within said casing and yieldably held in a safe position by magnetic attraction between the poles thereof and the poles of said casing, said element being dynamically constructed to be moved from an initial safe position to an armed position in response to centrifugalforce during the flight of the projectile, the movement of said element being retarded by eddy-currents induced therein during such movement.

5. A delayed arming device for a spin projectile comprising a casing composed of magnetic material and having a seat therein, a bipolar magnetized element disposed Within said seat in engagement with said casing and of dynamic structure to effect movement thereof in response to centrifugal force, said element being yieldably retained in an initial safe position by magnetic attraction between the poles of said element and the casing and adapted to be moved therefrom to an armed position by centrifugal force during the flight of the projectile, the rate of movement of the element being retarded by eddycurrents therein caused by said movement.

6. A claim according to claim 5 and including means I 6 l K for maintaining the element within said seat in engagement with the casing.

7. A delayed arming device for a spin projectile comprising a casing composed of magnetic material and having a spherical cavity therein, a spherical bipolar magnetized rotor disposed within said cavity in engagement with said casing and dynamically constructed for movement by centrifugal force from an initial safe position to an References Cited in the file of this patent UNITED STATES PATENTS Flather Sept. 12, 1916 McCaslin Feb. 24, 1948