Fuze

Oct. 20, 1953

J. D. JORDAN

2,655,867

FUZE

Filed Nov. 30, 1945

Sheets-Sheet 1

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INVENTOR

JAMES D. JORDAN

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ATTORNEY

Oct. 20, 1953

J. D. JORDAN

-FUZE

2,655,867

Filed Nov. 30, 1945

Sheets-Sheet 2

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ATTORNEY

Patented Oct. 20, 1953

2,655,867

UNITED STATES PATENT OFFICE

2,655,867 FUZE

James D. Jordan, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Navy

Application November 30,1945, Serial No. 631,951

Claims. (Cl.

The present invention relates to electromagnetic fuzes of the type adapted to be installed in ordnance missiles and more particularly to quick-acting fuzes of the type employed to cause instantaneous detonation of a projectile on im- ⁵pact with a target.

Representative of this general class of fuzes is that disclosed in United States Patent No. 1,858,969 to Herbert Ruhlemann, issued May 17, 1932 and entitled “Electric Fuze for Projectiles.” Such fuzes generally comprise: (1) An electromagnetic generator for developing energy; (2) a condenser for storing energy so developed; (3) means for permitting the storage of energy during the time of firing of the projectile until the ¹⁰displacement between the generator elements attains a critical value and for thereafter breaking the circuit between the condenser and generator; (4) a firing squib consisting of a thin resistance wire embedded in a priming composition ²⁰and adapted to be energized by the discharge current of the condenser to cause detonation of the projectile; (5) inertia-operated means for closing a circuit between firing squib and condenser upon target impact; (6) an expedient for pre- ²³venting operation of the generator until a predetermined time following the firing of the projectile.

It is an object of the present invention to provide an improved fuze of this type in which 30 motion of the magnetic member included in the generator is employed upon attainment of a critical displacement from the conductive member to break conductors, thereby to permit the condenser to retain its charge until the target is im- 33 pacted and also to remove a short circuit from the firing squib thereby to place it in operative condition.

It is also an object of the invention to provide an improved arrangement for performing these 40 functions without necessarily employing switches and other moving contacts.

Another object of the invention to provide an improved means for coupling the condenser to the firing squib to cause instantaneous detonation of 45 the projectile upon impact, a means which is sensitive to mere contact with the target.

Another object of the invention resides in the provision of mechanical safety means for affording protection in handling the fuze before it is 50 armed, coupled with means for releasing the safety means to arm the projectile.

For a better and further understanding of the present invention, together with other objects thereof, reference is made to the accompanying 55

102—70.2) drawings, together with the following specification and the claims appended thereto. In the drawings:

Fig. 1 is a schematic of the circuit included in the preferred embodiment of the present invention illustrated in Fig. 2;

Fig. 2 is an elevational sectional view of a preferred form of base fuze in accordance with the present invention;

Fig. 3 is a modified form of base fuze according to the invention;

Fig. 4 is a form of switch suitable for use in the Fig. 3 embodiment; and

Fig. 5 is an elevational sectional view of a projectile and fuze assembly, illustrating the manner in which either of the forms of fuze herein disclosed may be installed in a projectile.

Referring now specifically to Fig. 5, there is illustrated a fuze unit ¹1 &gt; installed in contact with a bursting charge 12 and in the base of an explosive projectile 13. Fitted to the nose of the projectile are a hood 14 and a plastic windshield 15. Projecting through the plastic windshield and insulated from the hood and projectile body are conductors 16 and 17, so disposed and arranged as to be in circuit with each other upon impact of the projectile nose with a target. The conductors are protected by insulation and spacers 18 and 19. Slidably fitted to the base of the projectile is a case 21 which contains an appropriate propellant powder charge 22. The conductors have such operation, in conjunction .with other fuze components presently to be described, as to cause detonation of the projectile at any desired instant either preceding or substantially at the time of impact of the main body 13 of the projectile with a target.

Referring now specifically to Fig. 2, it will be seen that the fuze unit 11 comprises an externally-threaded hollow base block 24, which is adapted to be mounted along the longitudinal axis of the projectile with its interior chamber 25 isolated from the charge-containing projectile chamber.

An externally-threaded steel coil block 26 is .fitted into the base block. A portion of the coil block projects from block 24 and an outer shell or barrel 27 is threaded at its open end upon this projecting portion, the opposite end of this barrel being closed.

The steel coil block is fashioned with an annular recess to accommodate a coil member 28. This coil is wound upon a magnetic core 29. Disposed within chamber 25 is a circular permanent magnetic inducing member 31, normally in contact

2,665,867 with core 29, and cooperating with the core and coil to function as an electro-magnetic voltage generator.

For retaining the movable magnet 31 against accidental displacement there are provided a plurality of detents 33, 34, which may be retracted in any one of three selected modes in order to release the magnetic inducing member. Centrifugal force developed by projectile spin may be used to retract the detents against the force of biasing springs 35, 36. Gas pressure developed within the powder chamber of casing 21 upon firing of the projectile may be used for this purpose, the gas being led through ports 37, 33 in the base block. Additionally, the detents may, if desired, be sheared by reason of the displacement of magnet 31, under setback, before the projectile leaves the gun.

The coil block is fashioned with a reduced, tubular, neck portion 46, forming within barrel 27 a space occupied by an annular paper condenser energy-storage means 41.

Centrally mounted in neck portion 46 is a firing squib or igniter 42. The firing train is completed through a central charge 43 of lead azide, an additional charge 44 of tetryl, and a tetryl booster charge 45 placed in the integral upper cupped portion 46 of the coil block. A safetygate or barrier 48 is interposed between charges 43 and 44 and is provided with a longitudinal port 49 normally offset from the longitudinal axis of the projectile and closed. The gate maintains the unarmed conditions of the projectile until s, predetermined time after it leaves the gun. The gate is adapted to slide transversely of the projectile under the effect of centrifugal force developed by spin, thereby shearing detent 5G and aligning port 49 between charges 43 and ¢4.

The coil block and magnetic member 31 are provided with central openings to receive a concentric-circuit-breaking pin member 50α slidably mounted within the magnetic member. The pin has a head portion 51 against which magnetic member 31 bears, after having moved a predetermined distance with respect to coil 28, thereby to retract the pin. Retraction of the pin causes the breaking of conductors 54 and 55 which are secured in slots in the pin. As will be apparent from an inspection of Fig. 1, the breaking of conductor 54 uncouples condenser 41 from coil 28, effectively disables the generator, and prevents the discharge of stored-energy through the coil. Breaking of conductor 55, which conductor is provided for protectively short-circuiting igniter 42 and preventing accidental burning thereof, removes this short circuit and places the igniter in potentially operative condition. It will also be seen that conductors 16 and 17 are normally open circuited, but that when a target is impacted the conductors have such operation as to touch or be placed in circuit and thereby to couple the condenser to the firing squib.

When a projectile containing the above-described fuze is discharged from a gun, the following sequence of events occurs: (1) detents 33, 34, are retracted and magnet 31 moves rearward# under the force of setback, thereby inducing a voltage in coil 28; (2) this voltage causes energy to be stored in condenser 41; (3) continued motion of magnetic member 31 causes retraction of pin 50^a, thereby disconnecting the condenser from the generator and removing the short circuit from the firing squib; (4) centrifugal force causes slide 48 so to move as to align port 49 with charges 43 and 44; (5) upon impact with a target conductors 16 and Π are placed in circuit, so that condenser 41 instantaneously discharges through firing squib 42 and causes rapid detonation of the projectile.

Referring now to Fig. 3, there is illustrated a modified form of base fuze in accordance with the invention and in which a conventional circuit breaker is substituted for the conductorbreaking expedient hereinabove described. Components of this embodiment which are similar in structure and function to the corresponding components of the Figure 1 embodiment have the same reference numerals primed and further description thereof is deemed unnecessary.

The fuze illustrated in Figure 3 differs from the Figure 1 embodiment in two essential respects: (1) a circuit breaker 58 having an actuating plunger 59 and so disposed and arranged as to be operated by movement of magnet 51', is substituted for the expedient reflected in the breaking of conductor 54, and functions upon setback to uncouple coil 28' from condenser 41'; (2) a switch, indicated generally at 60, is substituted for the expedient involved in effecting contact of conductors 16 and 17 by impact, the switch being operative upon impact to couple condenser 41' to firing squib 42'.

Reference is made to Fig. 4 in describing the last-mentioned svzitch. It comprises a thin, flexible copper foil diaphragm 6i disposed between two conductor disks 62, 63, in such manner as to close the circuit therebetween upon target impact.

The disks are separated by insulating spacers 65, 66, and are individually coupled to conductors 16' and 17'. The flexible foil possesses sufficient inherent rigidity to be initially and normally held in the safety position, in contact with disk 62, but out of contact with disk 63.

While there have been shown and described what are presently considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the true spirit of the invention and it is therefore intended, in the appended claims, to cover all such changes and modifications as fall within the true scope of the invention and without that of the prior art.