US3256817A

US3256817A - Piezoelectric fuse

Info

Publication number: US3256817A
Application number: US251807A
Authority: US
Inventors: Rabinow Jacob; Henry D Saunderson; Rotkin Israel; William M Piper
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-10-17
Filing date: 1951-10-17
Publication date: 1966-06-21
Anticipated expiration: 1983-06-21

Description

June 21, 1966 J. RABlNow ETAL PIEZOELECTRIC FUSE Filed Oct. 17, 1951 INVENTOR5-' Jacznb Rah-naw flinrheys 1 11.5 aund eraan the United States of America as represented by the Secretary of the Army Filed Oct. 17, 1951, Ser. No. 251,807 3 Claims.` (Cl. 102-70.2)

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to a piezoelectric fuse for explosive missiles and more particularly to a piezoelectric fuse in combination with a shaped-charge missile.

In shaped-charge missiles itis necessary that the shapedcharge be initiated at a predetermined distance, called the standoff distance, from the target in order to obtain optimum result. The stand-off distance of such missiles employing point initiatingmeans is achieved by means of a windshield fastened to the body of the projectile and extending forwardly of the shaped-charge liner. Electrical connection must be made between the point initiating element xed in the tip of the windshield and the detonator in the base of lthe shaped-charge. It has been found that the connecting Wire forming the electrical connection between point initiating element and the detonator which must be insulated from the missile cannot be satisfactorily supported in the missile due to the load created by acceleration. It is impractical to devise supporting means for the connecting wire, especially 'since the supporting means. must be cheap and simple to permit their use in mass production.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from the following description of a preferred embodiment as shown in the accompanying drawings in which:

FIGURE l is a longitudinal cross-sectional view of an explosive missile in which the invention is incorporated.

- FIGURE 2 is an enlarged detail of the juncture and connection between the cone shaped crystal supporting member and the missile body.

FIGURE 3 is an enlarged detail of the tip of the missile showing the mounting means for the electrical generating means. FIGURE 4 is a plan view of a -typical missile employi ing the invention.

Referring now to FIGURE l, a conductive windshield or ogive 1 of general conical coniiguration is separated from a similarly conductive internal cone-shaped member 2 by an air space 3. These members are aflixed to a missile body 4 in a manner described in connection with FIGURE 3.

Between the apices of members 1 and 2 is a piezoelectric crystal 5 supported by a rubber mounting 6 which is pierced to permit passage of a connector 7. This assembly can be clearly seen in the detail drawing of FIGURE 3. Rubber or rubber-like material i-s used as the mounting 6 since it acts to absorb shocks of small magnitude,

but will transmit strong shocks such as would be caused by the missile striking a target, and so would cause the generation of electrical energy by transmitting such shock 'to the piezoelectric crystal 5 and causing distortion thereof.

Referring now to FIGURE 2, the inner cone 2 of the nose assembly bears against contact ring '14 to which is connected insulated conducting cable 9. Cable 9 passes through aligned holes in

rings

12, 13 and 14 and a hole 11a in cone 11 and protective conduit 10 to a terminal 32 of electrical detonator 30 which is fixed in housing 8 intermediate 4the ends thereof. As shown in FIGURE 1, hous- United States Patent() rice ing 8 is located in the rear portion of explosive charge 118. Terminal 32 is insulated from housing 8 and terminal 33 of the detonator is soldered to housing 8 as indicated by reference character 33a thereby providing electrical connection between the detonator and body 4. Adjacent the detonator 30 is a first element 31a of an explosive train 31.

The second element 31b of the explosive train is separated from element 31a by means of housing 34 which contains a clockwork mechanism (not shown) and a third element 31C of the explosive train. normally held out of line with elements 31a and 31b by the clockwork mechanism. The clockwork mechanism is activated by the forces of setback when `the missile is launched and after a predetermined period of time aligns the third element with the rst and second elements. The explosive train 31, housing 34 and detonator 30 are -retained in housing 8 by means of potting compound 35. The inner cone 2 and contact ring 14 are insulated from the body 4 by insulating ring 13 and insulating washer 15. Metallic support ring 12 provides abearing surface for the insulating ring 13. Threaded lock ring 16 clamps the assembly comprising the shaped-charge cone 1l1, inner cone 2 and

rings

12, 13, 14 and 15 tightly against the shoulder 4a formed in the front end opening of the missile body 4.

Referring nowto FIGURE 3, 1the crystal mount 6 comprises a cup-shaped member of rubber having a recess -19 formed therein in which is retained a piezoelectric crystal 5. A resilient conductor 7 is formed with a head 20` positioned in the recess in contact with the crystal. The legs 21-22 of the conductor pass through an aperture 23 in the mount and are bent in opposite directions, conforming to outer surface of the mount. The mount -snugly tits the end 2a of the inner cone and holds the crystal in engagement with the inner cone. The legs 21-22 engage the inner surface of the apex of the windshield.

FIGURE 4 shows a typical configuration of a missile embodying the invention wherein 1 is the windshield, 4 is the body and 17 is the tail assembly, it being understood that the invention is not limited to this particular c onfiguration.

In operation the missile is detonated when the nose por- -tion of the missile -strikes a target, setting up a shock wave in the crystal mount which is .transmitted therethrough to the crystal. Under the shock of impact the crystal is distorted and thereby generates electrical energy which is transmitted to the electrical detonator 30 inhousing 8 positioned in the explosive charge 18. The circuit is formed from one side of the crystal by means of the inner cone 2 contact ring 14, and cable 9 which -is connected to terminal 32 of the electrical detonator, and from the other side of the crystal by means of conductor 7 in contact with the crystal and windshield, through the body of the missile and housing 8 to which the terminal 33 of the detonator is connected.

It will be apparent that the embodiment shown is only exemplary and that various modifications can be made aflixed to said body but electrically insulated therefrom and in spaced relationship to the outer conical member, a resilient cup-shaped member having electrical energy means ixed therein mounted on the forward end of the inner conical member and in engagement with the inner The third element issurface of the apex of the outer conical member, the cupshaped member holding one terminal of the electrical generating means in contact with the inner conical member, the other terminal of the electrical generating means maintained in contact with the outer conical member by means of a resilient conductor passing through an aperture in the cup-shaped member.

2. The invention of claim 1 wherein said electrical generating means comprises a ferro-electric crystal.

3. The combination of a detonator comprising a piezoelectric element, a detonating charge mounted in the base of a projectile, a windshield aixed to the projectile, and circuit means connecting said element and said charge, said circuit means comprising said windshield having a similar conic element positioned inside thereof in spaced relationship thereto, said conic element being axed to said projectile by electrical insulating means, an insulated cable extending -through the -body of the projectile and l connecting said conic element and said charge, said windshield and body of the projectile forming the return circuit and said circuit means, said piezoelectric element resiliently mounted between the apices of the Windshield and the conic element in electrical contact therewith.

References Cited by the Examiner UNITED STATES PATENTS 2,764,091 9/1956 Hudson 102-702 FOREIGN PATENTS 277,052 8/ 1951 Switzerland.

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL BOYD, Examiner.

D. D. DOTY, W. C. ROCH, Assistant Examiners.

Claims

3. THE COMBINATION OF A DETONATOR COMPRISING A PIEZOELECTRIC ELEMENT, A DETONATING CHARGE MOUNTED IN THE BASE OF A PROJECTILE, A WINDSHIELD AFFIXED TO THE PROJECTILE, AND CIRCUIT MEANS CONNECTING SAID ELEMENT AND SAID CHARGE, SAID CIRCUIT MEANS COMPRISING SAID WINDSHIELD HAVING A SIMILAR CONIC ELEMENT POSITIONED INSIDE THEREOF IN SPACED RELATIONSHIP THERETO, SAID CONIC ELEMENT BEING AFFIXED TO SAID PROJECTILE BY ELECTRICAL INSULATING MEANS, AN INSULATED CABLE EXTENDING THROUGH THE BODY OF THE PROJECTILE AND CONNECTING SAID CONIC ELEMENT AND SAID CHARGE, SAID WINDSHIELD AND BODY OF THE PROJECTILE FORMING THE RETURN CIRCUIT AND SAID CIRCUIT MEANS, SAID PIEZOELECTRIC ELEMENT RESILIENTLY MOUNTED BETWEEN THE APICES OF THE WINDSHIELD AND THE CONIC ELEMENT IN ELECTRICAL CONTACT THEREWITH.