US2808000A - Point detonating fuze - Google Patents

Description

Oct. 1, 1957 H. B. LINDSAY POINT DETONATING FUZE Filed June 10, 1954 INVENTOR firm/fy 5. L/NDSAY ATTORNEYS POINT DETONATDIG EFUZE Harvey B. Lindsay, Oakland, Caiif.

Application June 10, 1954, Serial No. 435,678

14 Claims. (Cl. 1132-73) Point detonating fuzes have been widely used for projectiles directed against personnel, light building construction, aircraft, and other targets, where it is desired to have the detonation occur substantially simultaneously with impact. However, the presently available fuz es of this character possess a number of shortcomings in operation,

construction, and/ or safety, which the fuze of this invention will effectively overcome.

It is therefore an object of the present invention to provide a point detonating fuze which will function with far greater impact sensitivity than the fuzes heretofore available, whereby the impact of the fuze on extremely light targets, such as tents or other very light construction will effect detonation of the associated projectile.

Another object of my invention is to provide a fuze of the type described which will remain in safe unarmed position until the projectile has been fired from the gun, notwithstanding blows, falls or other accidental loads imparted thereto during handling, transportation and firing.

A further object of the invention is to provide a fuze of the above character in which accidental pro-explosion of the detonator will not cause ignition or detonation of the main projectile charge.

A still further object of my invention is to provide a point detonating fuze which possesses superior functioning reliability, and in which means are provided to insure proper arming of the fuze in flight without the dependence upon other forces than high centrifugal force alone, found in prior art devices.

Another object of this invention is to provide a fuze of the type described which possesses relatively few working parts, and which may be produced more economically than fuzes previously utilized.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawing ac companying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawing and description maybe adopted within the scope of the invention as set forth in the claims.

Referring to said drawing:

Figure 1 is a longitudinal cross-sectional view of the fuze of the present invention shown in its unarmed position, the general plane of the view being indicated by line 1--1 of Figure 2.

Figure 2 is a cross-sectional view taken substantially in the plane indicated by line 22 of Figure 1.

Figure 3 is a view similar to Figure 1, but showing the fuze in its armed position.

Z,8fi,ii Patented Oct. 1, 1957 Figure 4 is a portional cross-sectional view taken substantially in the plane indicated by line 4-4 of Figure 2.

Figure 5 is a PQI iQnal cross-sectional view taken substantially in the plane indicated by line 55 of Figure 2.

Figure 6 is a perspective view of one of the pellet detonator stop members.

Figure 7 is a portional view of the rear end portion of a modified type of firing pin and associated pellet stop members.

The fu e of the present invention is adapted for mounting on the front end portion 12 of a projectile, the latter carrying the main detonating or bursting charge which is arranged to be exploded when the fuzeand its detonator is actuated. It will be understood, however, that in some instances, it may be desirable to utilize an auxiliary booster which is detonated or ignited by the detonator and which in turn detonates the burster charge in the projectile. However, whether or not an auxiliary booster is used has no bearing on the present invention.

As shown in the drawing, the fuze includes a relatively massive substantially cylindrical body 13 having threads 14 for attachment to the projectile portion 12 and threads 16 for receiving the threaded end of the conically formed nose or ogive 17. The latter defines with the body a chamber 18 in which the major portions of the fuze are disposed. The body is provided with an axially extending passage 19 which acts as a flash duct between the det- Ionator and burster as will be hereinafter explained.

Secured to the front surface of the body 13 by means of screws 21 or the like, is a yoke member 22, the latter having .flat peripheral portions 23 in contiguous relation.- ship with peripheral portions of the body, and a forwardly .oifset central portion 24 of generally semi-cylindrical form. By referring to Figure 1, it will be seen that the body has a corresponding semircylindrical cavity 26 which defines with yoke portion 24 a cylindrical chamber 27 for revolvably receiving a rotor 28. The size of the parts per.- inits relatively free rotation of the rotor within opening 27 about an axis perpendicular to and intersecting the longitudinal axis of the projectile, ogive and flash duct.

Rotor 28 is provided with a diametrical bore 29 medially of its ends, and such bore, upon rotation of the rotor .(clockwise as shown in the drawing) may move from the unarmed position shown in Figure 1 wherein it is axially aligned with a bore 31 in the fuze body to an armed position wherein it is aligned with the previously mentioned flash duct 19. Thus, if a detonator is posiltioned in bore 29, and the bore is not aligned with flash duct 19., setting off of the detonator will have no effect on the projectile charge, and the force of the detonator explosion will be directed along bore 29. However, as an added feature of safety, I provide a passage 32 from the bore 29 to the ogive chamber so that the expanding gases from such van explosion may be spent in the relatively large chamber and escape therefrom through a passage 33 positioned at the front end'of the nose on the longitudinal axis thereof. It should be mentioned at this time that passage 33 is primarily for receptionof the firing pin, to be explained in detail later, and its gas escape utility is only a secondary feature.

;A detonator is arranged to be positioned within bore 29 and as here shown, such detonator comprises a generally cylindrical pellet 36 which may consist of any of the-conventional fuze explosives such as azide, tetryl or the like. Referring to Figures ,1 and 3, the pellet will be seen to occupy a position in bore 29 radially ,outwardly from the center of rotation and is maintained in such position by front and rear pellet stop members designated 37 and 38 respectively. The pellet stop members are preferably constructed of extremely thin spring metal and have parallel side portions 39, and end portions 41 lying on segments of a circle slightly larger which the point 55 protrudes.

than the diameter of bore 29. These end portions are adapted to engage a pair of spaced peripheral grooves 42 and 43 in bore 29 and preferably are on a larger diameter than the groove diameter so that'when seated in the groove, the members will flex into the curvate shape indicated. To install the pellet and its associated stop members, member 37 is first introduced into bore 29, forced past groove 43 and snapped into position in groove 42, groove 42 being spaced from the rearend of firing pin portion 52, in unarmed position. The pellet 36 is then carefully pushed through the bore to stop 37, and stop 38 is then snapped into groove 43, the position of the latter spacing the rear end of the pellet from stop member 38. It will be understood that'loading of the stopmembers and pellet is preferably performed after the rotor is positioned in the yoke, and it is for this reason that rotor bore 29 is aligned with the yoke bore 31 when the rotor. is in an unarmed position. Bore 31 constitutes a loading channel .through which the pellet and stops are introduced, and access may be made by unscrewing the ogive from the fuze body and removing a threaded plug 46 from the end of bore 31, the use of whichplug 46 is optional.

. Where the detonator is formed of an explosive merely requiring an impact from the firing pin to effect detonation, the front stop member may be made, of a solid piece of material. However, many modern fuzes employ lead azide which is of substantially solid form, and which is actuated by piercing with a sharp instrument, such piercing causing local friction heating in the crystals 'which results in initiation of a flash and shock wave.

Accordingly, for such a detonator, the arrangement shown in Figure 7 is preferably utilized. As there indicated,

the enlarged .firing pin head 54, later to be described 'in detail, is provided with an axially extending point 55 which is adapted to pass through a central aperture 47 formed in the front stop member 37. Although the point 55 will be axially spaced from stop 37, it might be possible that in armed position, air pressure on the front end of the firing pin would cause the latter to move rearwardly until the point 55 penetrated the azide detonator. To prevent such an occurrence, I provide an auxiliary stop member 40 engaged in a peripheralbore groove 45, such stop having .a central aperture through However, stop 40 serves to prevent movement of the firing pin rearwardly until an actual impact is effected on the firing pin nose, at

which time, stop 40 may be forced rearwardly to permit point 55 to forcibly penetrate the pellet through aperture 47 in stop member 37.

In conventional point detonating fuzes, the firing pin has consisted of a straight piece of metal held in inoperative position by suitable detents, preventing its being driven against the detonator. Certain operational difiiculties accompany such an arrangement, and as an important feature of this invention, the firing pin is not in firing position until the fuze is armed. This is accomplished by utilizing a jointed firing pin consisting of a relatively long front portion 51 and a shorter rear portion 52, the latter preferably being bifurcated to receive the rear end of portion 51 and is pivotally secured thereto by a pin 53 or the like. Portion 52 is provided with a radially enlarged rear head 54, which may include a sharp point 55 where an azide detonator is utilized, and such portion is slidably mounted in bore 29, with the pivot connection 53 being positioned exteriorly of such here. When the fuze is unarmed, as viewed in Figure l, the front portion of the firing pin is disposed entirely within the ogive chamber 18 and forms an angle of slightly more than ninety degrees with the rear portion 52, with the leading end 56 of the pin being positioned adjacent the nose opening 33. The rearend 57 of the pin is seated in a socket 58 formed in the fuze body 13, and thus irrespective of any impact on the fuze, the firing pin cannot actuate the pellet. V I

However, if the rotor is permitted to rotate into itsarmed position (shown in Figure 3), the rear firing pin portion 52 will likewise be rotated, and due to the jointed connection at 53, the front firing pin portion 51 will be caused to move forwardly and upwardly until it is axially aligned with the rear portion and capable of unitary axial In this armed position, the leading end 56 of the firing pin, extends forwardly of the ogive movement therewith.

vided on yoke portion 24 which permits the aforesaid movement of the firing pin relative thereto. Also, to provide clearance for the pivotal action of the rear end 57 of the front pin portion, the rotor is notched at 62 adjacent the front end of bore 29. Thus, clearance is obtained in both the rotor and yoke to permit movement .of the firing pin from its inoperative angularly disposed position to its operative axial position;

If bore 29 was of constant diameter, and the firing pin portion 52 freely mounted therein for axial movement, it

might be possible for the pin to move forwardly from the firing position shown in Figure 3 due to the creep effect. .Creep may be defined as the continuous inertia force resulting from the deceleration of the projectile caused by air resistance, which tends to move fuze parts not directly exposed to air resistance towards the nose of the projectile. Although the force is not a great one, and in the armed position tends to be nullified by the air pressure on the exposed-end of the firing pin, I prefer to positively maintain the firing pin in fixed relation tothedetonator. This may be accomplished by reducing the diameter of .bore 29 just forwardly of the rear pin head 54 as shown at 64, so that pin portion 52'may freely move rearwardly, 1

such as when the front end 56 strikes a target, but will be restrained from forward movement by the engagement of head 54 on the shoulders defined at the juncture of bores 29'and 64.

Movement'of the rotor from its unarmed position to its armed position is effected by the centrifugal force created by the rotation of the shell in flight, such rotation being imparted by the rifiing in the gunbore. Centrifugal force will tend to rotate the rotor within chamber 27,

and to assist such rotation, I provide a pair of cylindrical .lugs 67 extending through the rotor which are not on the axial center line of the fuze. The ends of, the lugs extend beyond the rotary periphery, arcuate notches 68 being provided in yoke portion'24 and similar notches 69 being provided in body 13 to permit movement of the lugs and the rotor. Thus, these off-center weights will be more greatly affected by centrifugal force and forcibly'rotate the rotor to the armed position where further rotation is stopped by the lugs engaging a cut out portion 71 on the fuze body 13.

Means are provided for retaining. the rotor in an unarmed position until the centrifugal force exerted on the lugs reaches a predetermined value. Preferably, this value is reached when the projectile is rotating at approximately revolutions per second. As here shown, detents 72 are provided adjacent each end of the rotor, each detent comprising a piece of spring wire or'the like engaged in suitable V-shapecl notches 73 in the end walls of yoke portion 24. One end of the Wire may be anchored in a cavity 74 in the rotor end walls with the distal portion of the detent resting in the housing groove. Thus, by regulating the spring size, the detent can be freed from its seated position in the notch upon a predetermined centrif- .ugal force which may be readily calculated. When centrifugal force has reached this amount, thedetent will be It will be clear that in the armed posiasosnoo forced from the notch, and the rotor permitted to rotate as hereinabove described. Clearance may be had for the raised detent by providing a grooved portion 76 in the yoke housing along the path of rotation of the detent with its rotor. If desired, a second notch 77 may be utilized to receive the detent when the rotor has moved to its armed position.

From the above described detent arrangement it will be readily understood that only extremely rapid rotation of the projectile (and fuze) will permit arming of the fuze. Thus, no accidental rolling of the shell will be sufiicient to impart the centrifugal force required to permit rotor rotation. As further safety factors, attention'is again directed to the out of line or jointed firing pin, the reception of the rear end of pin portion 51 held in socket 58, and the solid enclosure of rotor bore in which the pellet is positioned. Even if an accidental blow was given to the nose sufficient to crumple the ogive and distort the firing pin in such a manner that portion 52 would be forced towards the pellet 36, pin portion 51 would engage the outer periphery of the rotor, halting movement of head 54 before pellet contact. However, even if the pellet was detonated from any cause, the provision of safety passage 32 would prevent the explosive flash or force from reaching the main projectile charge.

With the foregoing description in mind, the phases of operation of the fuze will be discussed. We will as- .sume the fuze is mounted on a projectile which is to be fired from a gun having a foot rifled barrel, one com- ,plete 360 degree twist of the lands in the barrel, and .a muzzle velocity of 2500 feet per second. Maximum acceleration of the projectile will not occur until the projectile has left the mouth of the barrel -or until the rapid outrush of highly compressed gases in the barrel .have escaped. Upon full forward acceleration; the projectile and its associated fuse will be rotating at about 250 revolutions per second, but even at this rate of rotation, the centrifugal force exerted on the rotor lugs will not be sufiicient to rotate the rotor, due to the bind- .ing of the setback force of the rotor in its housing created by the pressure of the firing impact. Thus, notwithstanding immediate rotation of the projectile, the rotor will bind itself to its housing until forward acceleration of the projectile terminates, this usually occurring from six to twenty inches beyond the mouth of the barrel.

After the initial period of acceleration, the main forces acting upon the shell and fuze parts will be centrifugal force due to rotation, creep as previously described, and air pressure on the front end of the nose and firing pin. The latter two forces for the most part are minor and tend to neutralize each other. Therefore, as acceleration, setback and binding forces have been eliminated, centrifugal force on the relatively massive rotor lugs 67 cause the rotor to rotate and overcome the spring action of detents 72. This rotation effects a forward movement of firing pin portion 51, removing the same from socket 53, and urging the forward end 56 through the nose opening 33. At the same time the two portions of the firing pin are brought into axial alignment with bore 29 and flash duct 19. When the rotor has been rotated to this armed position, detents 72 will engage the notches 77 and serve to hold the rotor in an armed position The foregoing will be accomplished in approximately one-tenth of a second from the beginning of the projectile flight.

With the fuze armed, actuation requires only a slight contact on the exposed end 56 of the firing pin, the required impact being merely sufficient to have the head 54 strike the pellet stop 37 out of its shallow groove 42 and with it to strike and detonate the pellet against the momentary resistance of pellet stop 38. As previously explained, where an azide detonator is used, the sharpened rear end 55 of the firing pin would pass through 6 stop aperture 47 after displacing the auxiliary stop merriber 40 to pierce and detonate the pellet.

To prevent dust or other foreign matter from entering the ogive chamber, and to effectively seal the latter against accidental insertion of objects which could damage the firing pin, I provide a seal preferably consisting of a soft metal disk 80, such as lead, which may be releasably retained in a peripheral groove 81 formed in the ogive passage 33. This disk is constructed so that it maybe readily displaced from its sealing position upon arming of the fuze and forward movement of the firing pin.

From the foregoing description, the construction and operation of my fuze should be understood. It will be appreciated that the fuze of this invention is safer, more positive in action, and more economical to produce than point detonating fuzes heretofore available. It Will be further understood that the fuze is dynamically balanced in flight, thereby assuring higher accuracy. A final consideration includes the fact that most prior art devices could for reasons of safety only use a very small detonator, thereby requiring increasingly progressive boosters and the like. By means of the novel safety vent arrangement, and other safety factors of this invention a more powerful detonating charge may be safely utilized so that its explosive flash or force may readily detonate the main projectile charge.

I claim:

1. A fuze comprising a longitudinally extending and substantially hollow body provided with a base portion having a rotor chamber therein and a longitudinally extending passage adapted to communicate with said chamher, a rotor rotatable in said chamber for rotation about an axis perpendicular to the longitudinal axis of said body, means defining a diametrical bore extending through said rotor perpendicular to the axis of rotation thereof and arranged to have one end thereof register with said passage in one position of rotation of said rotor, means in said bore for receiving a detonator charge, and a firing pin having a first portion extending into said bore from the other end thereof and a second portion pivotally connected to said first portion exteriorly of said bore.

2. A point detonating fuze comprising a longitudinally extending nose portion having an opening at the forward end thereof, a base at the rear end of said nose portion, means defining with the forward portion of said base a substantially cylindrical rotor chamber having an axis normal to the longitudinal axis of said nose portion, means defining a longitudinal passage in said base adapted to communicate with said chamber, a generally cylindrical rotor slidably mounted in said chamber for rotation therein about said chamber axis, said rotor having a diametrical bore positionable along a longitudinal axis in alignment with said passage in a first position of rotor rotation, means for selectively and releasably holding said rotor in said first and in a second position of rotation, said rotor in said second position closing said passage, and a firing pin having a first element slidably mounted in said bore and a second element pivotally connected thereto exteriorly of said bore, said elements being angularly related with a distal end of second element adjacent said nose opening when said rotor is in said second position and said elements being axially aligned with said distal end of said second element extending forwa rdly and exteriorly of said nose portion through said opening when said rotor is in said first position of rotation.

3. A fuze of the character described comprising a conical nose portion having an axial opening at the apex thereof and defining a fuze chamber, means within said chamber defining a rotor housing, a rotor mounted for rotation in said housing about an axis substantially normal to the nose axis, means defining a diametrical bore through said rotor lying in a common plane with said nose axis, detent means normally maintaining the rotor in a first position wherein said bore is angularly related to said nose axis, axially offset weights on said rotor a 7 whereby centrifugal force can effect rotation of said rotor to overcome said detent means and rotate said rotor to a second position wherein said bore is axially aligned with said nose axis, a jointed firing pin having a first element slidable in said bore and a second element pivotally connected thereto exteriorly of said bore, said second element having a distal portion movable through said nose opening upon movement of said rotor from said first position to said second position. I 4. A device as set forth in claim 3 including means for stopping rotation of said rotor when the latter has rotated from said first position to said second position. 5. A point detonating fuze assembly arranged to be attached to the front end of a projectile carrying an explosive charge comprising a longitudinally extending tapered nose portion having an axial opening at the front end thereof, a base positioned adjacent the rear end of said nose portion and defining therewith a chamber, a substantially cylindrical rotor positioned in said chamber with its axis perpendicular to and intersecting the longitudinal axis of said nose portion, means for rotatably supporting said rotor for rotation about said axis, a diametrical bore in said rotor having an axis lying in a plane containing said nose portion axis, means for supporting a detonator in said bore, a firing pin consisting of a first element slidable in said bore and a second element pivotally attached thereto exteriorly of'said rotor bore and having a front end adjacent said nose opening, means for normally and releasably positioning said rotor with the bore thereof angularly related to the nose axis and with the elements of the firing pin disposed in regular relationship to each other and to said longitudinal axis, said means being releasable upon the rotation of said fuze assembly and development of centrifugal force of predetermined magnitude to permit rotation of said rotor and to overcome said positioning means to a second position wherein said bore is aligned with said nose axis and the elements of the firing pin are axially aligned with the front end of said second element extending axially through said nose passage and the rear end of said first element adjacent said detonator supporting means, and an axial flash duct in said base whereby communication may be had between said bore and the explosive charge in said projectile when said rotor is in said second position, and whereby such communication between said bore and said passage is wholly blocked by a solid portion of said rotor in said first position.

6. A device as set forth in claim 5 including a socket portion in said base for receiving the rear end of said second element when said rotor is in said normal position.

7. A fuze including a longitudinally extending nose portion defining a chamber having axially aligned front and rear openings therethrough, a substantially cylindrical rotor in said nose portion, means substantially enclosing said rotor for supporting the latter for rotation about an axis perpendicular to and intersecting the longitudinal axis of said nose portion, means defining a diametrical bore through said rotor having an axis lying in a plane containing said nose axis, means defining a bore of substantially the same size as said rotor bore in said supporting means having an axis lying in said plane and angularly related to said nose axis, duct means establishing communication between said latter bore and said chamber, said duct means having an effective crosssectional area for the entire length thereof of substantially the same size as said rotor bore, the total space occupied by said bores and duct means being substantially less than the volume of said chamber, a detent operatively connecting said supporting means and said rotor for normally positioning the latter with the rotor bore in communication with the supporting means bore, a weight extending from said rotor angularly related to said nose axis and adapted to overcome the force of'the detent and permit rotation of said rotor upon the development of a predetermined centrifugal force created v V i, 8 l by rotation of said fuze, said rotor being movable to "a second position wherein the rotor bore is axially aligned with said nose portion openings, and a firing pin having a front end slidable through said front nose opening to extend axially forwardly thereof and a rearend slidable in said rotor bore for engaging a detonator in said bore upon impact on the front end of the firing pin.

8. Apparatus as set forth in claim 7 in which said bore includes means for supporting a detonator therein, said means including a pair of parallel detonator stop members spaced axially within said bore, and peripheral grooves in said bore for releasably receiving said stop members. p

9. A fuze as set forth in claim 7 including a pair of detonator support members positioned in axially spaced relation in said rotor bore, one of said members con- 'sisting of thin spring-like material having a central aperture therein through which the rear end of said firing pin may enter, and groove means for supporting said mem' bers in position in said bore.

10. A- point detonating fuze comprising a longitudinally extending nose portion having axially aligned front and rear openings therethrough, a substantially cylindrical rotor in said nose portion, means substantially enclosing said rotor for supporting the latter for rotation about an axis perpendicular to and intersecting the longitudinal axis of said nose portion, means defining a diametrical bore through said rotor having an axis lying in a plane containing said nose axis, means defining a bore in said supporting means having an axis lying in said plane and angularly related to said nose axis, means defining a passage leading from said latter bore exteriorly of said rotor to within the nose portion, means normally positioning said rotor in a first position wherein the rotor bore is aligned and in communication with the supporting means bore, means effecting rotation of said rotor to a second position upon application of centrifugal force to said nose portion wherein the rotor bore is axially aligned with said nose portion openings, means for supporting a detonator in said rotor bore, and a firing pin having a front end slidable through said front nose opening and a rear end slidable in'said rotor bore for engaging a detonator in said bore upon. impact on the front end of the firing pin.

11. A fuze of the character described comprising a longitudinally extending and substantially enclosed nose portion having front and rear openings therein on the longitudinal axis thereof, a substantially cylindrical rotor in said nose portion, means supporting said rotor for rotation about an axis normal to and intersecting said nose axis, said rotor having a diametrical bore therethrough having an axis lying in a plane containing said nose axis, means normally maintaining said rotor in a first position wherein said bore is angularly related to said nose axis, means permitting movement of said rotor to a second position wherein said bore is aligned with said nose axis, a firing pin having first and second elements, said first element being mounted for axial sliding movement in said rotor bore with the front end thereof extending outwardly of said bore, means pivotally connecting said front end to said second element adjacent the rear end of the latter about an axis parallel to the rotational axis of said rotor, the front end of said second element being slidable in said front nose opening, said elements being angularly related when said rotor is in its first position with the front end of said second element disposed within said nose portion, and said elements upon movement of said rotor to said second position being axially aligned with said front end extending through said front nose opening.

12. A fuze as set forth in claim 1 further characterized by each of said firing pin portions lying in a plane containing said body axis and each being angularly related to each other and to said axis in all positions of rotor rotation except when said diametrical bore registers with said passage.

13. A fuze as defined in claim 1 in which the end of said body remote from said base portion is provided with References Cited in the file of this patent UNITED STATES PATENTS Watson Sept. 23, 1919 FOREIGN PATENTS Great Britain May 25, 1926 France Nov. 12, 1938 Switzerland Dec. 1, 1941

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