US3906861A

US3906861A - Fuze sterilization system

Info

Publication number: US3906861A
Application number: US435047A
Authority: US
Inventors: C Robert Hamilton; John E Crossley; Thomas W Hampton; Kenneth N Morris
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1974-01-21
Filing date: 1974-01-21
Publication date: 1975-09-23
Anticipated expiration: 1992-09-23

Abstract

A safety device for an ordnance fuze in a projectile that is armed by movement of an unbalanced rotor subjected to acceleration forces acting on the projectile, where complete arming of the fuze requires movement of the rotor through a predetermined angle to complete an explosive firing train or trains during projectile travel to the target. Upon the occurrence of an unusual flight condition, for example a sudden deceleration of the projectile, before the predetermined lapse of time necessary to completely arm the fuze, causes explosive actuators to come in contact with the rotor to prevent further angular movement toward the armed position thus causing the projectile fuze to become sterilized or dearmed.

Description

United States te Hamilton et a1,

1 1 Sept. 23, 1975 1 FUZE STERILIZATION SYSTEM [75] Inventors: C. Robert Hamilton, China Lake;

John E. Crossley, Ridgecrest; Thomas W. Hampton, China Lake; Kenneth N. Morris, Ontario, all of Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: Jan. 21, 1974 [21] App]. No.: 435,047

[52] U.S. Cl. 102/76 R; 102/79 [51] Int. Cl. F42c 15/04 [58] Field of Search 102/70, 70.2, 76, 78, 79

[56] References Cited UNITED STATES PATENTS 2,486,362 10/1949 OBrien 102/702 R 2,830,539 4/1958 Cecil, Jr..... 1. 89/1 B X 2,889,777 6/1959 Rabinow 102/78 2,913,984 11/1959 Meek et a1 102/78 Voida et a1. 102/78 X Lunt et a1. .1 102/702 R [57] ABSTRACT A safety device for an ordnance fuze in a projectile that is armed by movement of an unbalanced rotor subjected to acceleration forces acting on the projectile, where complete arming of the fuze requires movement of the rotor through a predetermined angle to complete an explosive firing train or trains during projectile travel to the target. Upon the occurrence of an unusual flight condition, for example a sudden deceleration of the projectile, before the predetermined lapse of time necessary to completely arm the fuze, causes explosive actuators to come in contact with the rotor to prevent further angular movement toward the armed position thus causing the projectile fuze to become sterilized or dearmed.

5 Claims, 2 Drawing Figures US Patent Sept, 23,1975

FUZE STERILIZATION SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a safety device to dearm or sterilize projectile fuzes that use acceleration mechanisms to arm the fuze.

2. Description of the prior art Air to air and ground to air missiles and projectiles may have target mission requirements that necessitate utilization of many different types of fuzes. Certain of these fuzes could detonate upon impact or contact with the target. Another type. the proximity fuze. will explode when in the vicinity of a target. These fuzes once completely armed would create a hazardous condition if they have not traveled a safe distance from the firing source. A safety device is desirable that would prevent arming of the missile or to inactivate the fuze by stopping arming movement where an inadvertant firing causes the missile to strike an object before a safe separation distance is obtained between the object struck by the missile and the vehicle from which the missile or projectile was fired.

Due to the rapid technological advances in the missile and projectile fields, velocities of travel have now been attained that render ineffective mechanisms that provide long time delays or require complex or intricate mechanisms to arm a missile fuze during flight.

Prior art attempts to solve this problem have involved the use of various timing or delay mechanisms that require completion of an explosive firing train to arm the missile fuze. These devices arm the fuze a predetermined time after firing the missile so that the missile or projectile has traveled a reasonably safe distance from the firing source. One of the most critical problems confronting designers of fuzes of this type has been the need to safe or dearm the fusing system once the arming action has started. The need is for a simple, foolproof device that will positively lock the fuze mecha nism from further arming movement to prevent firing of the warhead when an abnormal condition arises. Numberous fuzes presently used have no means to stop arming action once it has been initiated thus causing a potential dangerous situation to exist to personnel and equipment whenever an unexpected missile flight condition occurs.

SUMMARY OF THE INVENTION An object of the invention is to provide a fuze sterilizing or dearming device that can be used to positively stop a fuze mechanism that is of the delay arming type.

These and other objects herein after defined are met by the present invention which relates to a relatively, simple, foolproof safety or securing device that is lightweight and easily adaptable to existing fuzes. The mechanism of the invention provides two unbalanced rotors geared together and disposed in the ignition conducting passage or train capable of rotation through a predetermined angle when acted on by acceleration forces during missile or projectile flight. In the safe position these rotors are locked by a set back weight and interrupt the ignition conducting passage to prevent inadvertant fuze firing. The acceleration of the missile causes the setback weight to unlock the rotors and permits their controlled movement from a safe fuze mode to an armed mode. During this period, if the missile is suddenly deeelerated a sensing switch actuates an explosive device causing a portion of its case end to expand and jam against the surface of the rotor or rotors to prevent further rotor movement toward arm position. This action effectively locks the rotors and prevents any possible movement of the rotors toward completion of the ignition conducting passage and thereby effectively dearms or sterilizes the fuze. The missile or projectile can then be safely moved with out hazard to personnel since any rough handling that could cause forces to further rotate the unbalanced rotor for complete arming would have no effect because of the jammed rotorsv BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a fuze mechanism to which a sterilization means or dearming means in accordance with the invention has been adapted.

FIG. 2 is a simplified schematic diagram of the fuze sterilization device.

Referring more particularly to the drawings, wherein similar reference characters are used to designate corresponding parts throughout, there is shown in FIG. 1 a portion of a missile or projectile housing 11 that contains a frame portion for supporting the fuzing elements. Mounted within

holes

18 and 19 on a portion of a frame projection are explosive actuated bellows l2 and 17 held in place by threaded plugs 14 and I5. Electrical leads l3 and 16 are connected to a power source in a circuitry configuration best shown with reference to FIG. 2. Bellows l2 and 17 have expandable tips that operate when explosive charges within the containers are actuated.

Arming rotors

35 and 36 are mounted for rotative movement on shafts 37 and 38. These shafts fit within shaft holes 42 within frame projection.

Arming rotors

35 and 36 are unbalanced about their respective axes so that free rotation will occur when the rotors are subjected to acceleration forces. The outer circumference of

rotors

35 and 36 are geared together by gear teeth. not shown, so that the rotors will move in unison with one another. An cscapement mechanism 32 is adaptive to be connected to geared rotor circumference 36. Escapement mechanism for regulating rotor movement is rigidly fastened within a cutout portion of frame projection by means of fastening screws 33 and 34 so that the faces of

rotors

35 and 36 are in close proximity with the face of the frame projection. This allows the positioning of

bellows

12 and 17 adjacent to and in close proximity to the face of rotor 36. Although the drawing shows bellows l2 and 17 both positioned to bear against the face of rotor 36, it is to be understood that there can be a bellows unit positioned for operation against each rotor.

A cover 29 is adaptive to be mounted so as to be held in spaced relationship from the face of the frame. This is accomplished by means of

spacers

27 and 28 and the face of the frame projection. The top cover 29 and frame form a protective housing over the

rotors

35 and 36 and allows a portion of each rotor circumference to extend through

openings

45 and 46. A setback weight 23 having

holes

25 and 26 for receiving

spacers

27 and 28 is mounted to slide freely within the space formed between cover plate 29 and the frame face. A spring 22 held in position by pin 21 and a hole, not shown. in the lower end-face of setback weight 23. This arrangement provides a spring bias of a predetermined force to hold setback weight against the bottom face of cover 29. A

machined out portion on the face of setback weight is adaptive to engage against rotor pin 24 positioned to project from the face of rotor 36. This mechanism holds rotor 36 locked in position and prevents both rotors from rotating whenever the fuzc is in the safe position. Setback weight 23 may be further mechanically locked by a locking mechanism, a safety pin or the like, not shown, to prevent movement of setback weight against spring 22 thus causing

rotors

35 and 36 to be released. Mechanical locks of this type are normally used to positively prevent arming of the fuze until the missile or projectile is ready for actual firing.

The fuze mechanism shown in FIG. ll provides for safety against accidental firing of the warhead. not shown, by providing means to interrupt the initiating firing train by an out of line mechanism..This is accomplished by providing

holes

47 and 49 for rotor 35 and holes 48 and 51 for rotor 36. These holes meet at right angles within the respective rotors and are charged with an explosive material. Additional explosive material is packed within

holes

43 and 44 in cover 29. With the edges of

rotors

35 and 36 positioned within

holes

45 and 46 the initiating firing train may be either interrupted or continuous depending on the position of

rotors

35 and 36. The firing train is initiated by a means not shown and forms no part of the present invention.

An inertial contact sensing switch is mechanically fastened to the bottom surface of cover 29. This switch 30 has electrical leads 31 for electrical connection with explosively actuated bellows l2 and 17, best shown with reference to FIG. 2. Leads 31 are cabled together to extend through housing 11 by means electrical cable 39.

Electrical switch 40 is mechanically fastened to the frame of housing 11. Switch 40 has electrical contacts 41 that engage shaft 37 of rotor 35. This shaft may be constructed of insulation with certain metalized portions that engage contacts 40 whenever rotor 36 is in certain positions. Switch 40 provides additional safety by providing a means to electrically interrupt the firing signal that initiates the firing train. This switch 40, although shown as a type of commutator leaf spring contact switch, may be other types of rotary switches capable of interrupting a multiplicity of independent circuits. Jamming of the rotor would also prevent electrical switch movement since the switch is an integral part of rotor 35.

Turning now to FIG. 2 there is shown a schematic diagram of the electrical circuit. Terminal 52 is connected to a direct current source of energy. not shown. Terminal 52 is electrically connected to ground via limiting resistor 53, diode 54 and resistor 55. In parallel circuit arrangement with resistor 55 is a first network of a series capacitor 56 electrically connected to a parallel arrangement of

explosive bellows

12 and 17 having one side tied to ground potential. The inertial contact switch 30 forms a second network that is electrically connected in parallel arrangement with resistor 55. A lead connected to junction 57 electrically connects to fuze firing capacitor. not shown, via switch 40. The schematic diagram of FIG. 2 represents a simplified schematic of the electrical connection of the explosive bellows 12, 17 and inertial switch 30 in a conventional fuzc firing circuit that utilizes a charged firing capacitor for storing sufficient energy during missile flight to initiate a firing train.

In operation, the mechanical firing pin, not shown is removed to release setback weight 23. When the missile or projectile is fired acceleration forces upon the missile force setback weight against spring 22 overcoming its biasing force and allowing rotor 36 to freely move due to these acceleration forces.

Rotors

35 and 36 are initially positioned in the safe mode thus interrupting initiating fuze train extending through

holes

43 and 44 in cover plate 29.

Rotors

35 and 36 are controlled in the time that is required to move from full safe mode to full arm mode. The rate of angular movement of each rotor depends upon the construction of the escapcment mechanism 32 which causes a predetermined time delay before complete arm mode is accomplished. This occurs whenever rotor hole 49 is in alignment with hole 43 and rotor hole 51 is aligned with hole 44. Electrical initiation of the firing train by an initiator, not shown, will cause firing train to be ignited for firing the missile or projectile warhead.

At the same time that the firing train is completed, rotor 35 also completes an electrical Contact or contacts through switch 40 to permit electrical energy to flow to ignite the two firing trains by means of an initiator.

Since an unsafe condition could arise because of failure of the explosive missile to reach a safe separation distance from the firing source during the time period between safe and arm modes whenever the

rotors

35 and 36 are moving between these two modes. It is necessary in situations of inadvertent missile launch, where the missile has accelerated sufficiently to start movement of

rotors

35, 36 through an angular position between safe and arm mode, to provide a mechanism to sterilize the fuze when the missile impacts against a solid object. The warhead could be initiated a short time thereafter upon receipt of an electrical signal from the proximity or contact fuze thus initiating the firing train to explode the warhead.

To prevent warhead initiation when the missile im pacts a solid object inertial contact switch 30 closes causing capacitor 56 to dissipate its charge through explosive bellows l2 and 17. These devices will fire causing each end to expand to contact the face of rotor 36. This effectively jams the rotor 36 from further movement and positively prevents further rotor motion toward armed position. The

rotors

35 and 36 since they are geared to each other will remain in a position that interrupts the firing train and even if fuzc is fired the warhead will not explode.

The employment of explosive bellows such as 12 and 17 can be used against one rotor such as shown by FIG. 1 or explosive bellows can be used against each rotor. The use of explosive bellows in conjunction with an impact-triggered firing circuit can be applied to other types of fuzcs to prevent full fuze arming from occurring if the missiles or projectile's weapon flight to the target is interrupted before safe separation distance is achieved between missile and launching source.

Although there is shown and described a preferred embodiment of the present invention it should be understood that numerous modifications or alterations are possible without departing from the spirit of the invention as set forth in the appended claims.

We claim:

1. An ordnance fuze in a projectile that arms said fuze when subjected to acceleration forces and which has a firing train, a safety and arming device comprising:

rotor means operatively arranged to interrupt said firing train when said fuze is in an unarmed condition and unbalanced about its rotation axis for rotating when said rotor is subjected to forces normal to its axis of rotation to complete said firing train when said fuze is in an armed condition;

rotation regulation means for allowing said rotator to move in one direction when subjected to acceleration forces until a predetermined angular rotation is obtained:

deceleration sensing means for initiating an electrical signal when the acceleration forces acting on said rotor decrease to a predetermined force; and

expandable means fixed adjacent said rotor means and electrically coupled to receive an electrical signal from said deceleration sensing menas for actuation of said expandable means to its enlarged mode;

whereby the rotor means is allowed to rotate when subjected to acceleration forces and is rapidly locked from rotative movement whenever the acceleration forces acting on said rotor decrease to a predetermined force.

2. The ordnance fuze apparatus defined in claim wherein said rotor means comprises:

a control rotor having gear teeth positioned on its circumfercnce;

a switch rotor having gear teeth positioned on its outer circumference and having an axis shaft forming a movable electrical switch element:

said control rotor and said switch rotor operativcly connected by means of said gear teeth to rotate together through a predetermined angle.

3. The ordnance fuze apparatus as defined in claim wherein said rotation regulation means comprises:

an escapemcnt means operatively attached to said rotor means.

4. The ordnance fuze apparatus as defined in claim wherein said expandable means comprises:

an expandable element having a portion of its surface area contacting said rotor with sufficient frictional force upon actuation to prevent further rotor movement by acceleration forces.

5. The apparatus as defined in claim 4 wherein said expandable element comprises:

a metallic capsule filed with explosive material that distends and endwise wall portion when explosively actuated.

Claims

1. An ordnance fuze in a projectile that arms said fuze when subjected to acceleration forces and which has a firing train, a safety and arming device comprising: rotor means operatively arranged to interrupt said firing train when said fuze is in an unarmed condition and unbalanced about its rotation axis for rotating when said rotor is subjected to forces normal to its axis of rotation to complete said firing train when said fuze is in an armed condition; rotation regulation means for allowing said rotator to move in one direction when subjected to acceleration forces until a predetermined angular rotation is obtained; deceleration sensing means for initiating an electrical signal when the acceleration forces acting on said rotor decrease to a predetermined force; and expandable means fixed adjacent said rotor means and electrically coupled to receive an electrical signal from said deceleration sensing menas for actuation of Said expandable means to its enlarged mode; whereby the rotor means is allowed to rotate when subjected to acceleration forces and is rapidly locked from rotative movement whenever the acceleration forces acting on said rotor decrease to a predetermined force.

2. The ordnance fuze apparatus as defined in claim 1 wherein said rotor means comprises: a control rotor having gear teeth positioned on its circumference; a switch rotor having gear teeth positioned on its outer circumference and having an axis shaft forming a movable electrical switch element; said control rotor and said switch rotor operatively connected by means of said gear teeth to rotate together through a predetermined angle.

3. The ordnance fuze apparatus as defined in claim 1 wherein said rotation regulation means comprises: an escapement means operatively attached to said rotor means.

4. The ordnance fuze apparatus as defined in claim 1 wherein said expandable means comprises: an expandable element having a portion of its surface area contacting said rotor with sufficient frictional force upon actuation to prevent further rotor movement by acceleration forces.

5. The apparatus as defined in claim 4 wherein said expandable element comprises: a metallic capsule filed with explosive material that distends and endwise wall portion when explosively actuated.