US2595757A - Fuse - Google Patents

Description

y 6, 1952 E. w. BRANDT 2,595,757

FL'ISE Filed July 11, 1947 4 Sheet s-Sheet 1 (Ittornegs E. w. BRANDT 2,595,757

FUSE

May 1952 Filed July 11, 1947 4 Sheets-Sheet 2 3nnentor attorneys May 6, 1952 Filed July 11, 1947 E. w. BRANDT FUSE 4 Sheets-Sheei 3 Zmnentor Gttomegs May 6, 1952 E. w. BRANDT 2,595,757

FUSE Filed July 11, 1947 4 Sheets-Sheet 4 m as.

giZfi 7 inventor (Ittomegs Patented May 6, 1952 FUSE Edgar William Brandt, Geneva, Switzerland, assignor to Anstalt fur die Entwicklung von Erfindungen und Gewerblichen Anwendungen Energa, Vaduz, Liechtenstein, a corporation of Liechtenstein Application July 1 1, 1947, Serial-No. 760,425 In Switzerland November 2, 1946 This invention relates to iuzes having a mechanical delay device.

Numerous types of fuze are already known which are designed to be mounted in the ogival head, inside or at the base of explosive projectiles, and which comprise devices intended to ensure security against shock during storage or handling, security'in the bore on firing, to give delayed arming in order to avoid premature bursting of the projectile if the latter should, after discharge, encounter an unexpected obstacle, such as camouflage, branches, or the like, in the vicinity of the firer, and, moreover, to ensure on impact either instantaneous or delayed bursting.

Such fuzes generally comprise a fairly complicated mechanical device, the functioning of which is controlled either by a clockwork move? ment or directly by the forces acting on the projectile on the firing of the shot.

The present invention relates to fuzescomplying with the above-mentioned conditions and with all requirements, while being of simple construction, capable of being made of very small dimensions, comprising a minimum of parts, being adapted to resist the stresses developed on the discharge of the shot, and, if so required, to resist the impact shock.

The fuzes of the present invention are of the type which are provided with a mechanical arming delay device, or mechanical safety orfiring device, comprising essentially two co-actingparts, one of which comprises at least one groove and the otherat least one slide adapted to run in 3 Claims. (01. 10278) inertia block in imposing it a rotary oscillating movement.

The opposing member can be an elastic opposing member such as, for instance, a spring.

With such a device, security against shock during storage and handling of the projectiles, as well as security in the bore of the gun on ,firing, and muzzle'safety are absolute, since no accidental force can act on the inertia block simultaneously in the axial direction and in the tangential direction, nor for a sufiicientlv long space of time to cause the slide to follow, first in one direction and then in the other, the zig-zag V- shaped path presented by the groove, which can only take place after the shot has been fired and within the period of time corresponding to the desired delay.

The length of the groove, the number and extent of the zig-zags, the diameter and the weight said groove, and are characterized by the fact that one of said co-acting parts is an inertia block maintained in a safety position by the action of at least one opposing member, and that the groove comprises two converging branches disposed substantially in the shape of a V and imposes on the slide forming the bolt, at least in one of its branches, a zig-zag path, so that, under the action of a sustained thrust greater than the action of the opposing member, said inertia block passes from the safety position to an intermediate position, the slide being caused to fork'from one of the branches ofthe groove into the other; the inertia block can from that moment reach the armed position when the thrust effect greater than the action of the opposing member ceases, its displacement havingrtaken'place first in one direction, in accordance with one of the branches of the groove, then in the opposite direction, under theopposing force, in accordance withthe other branch of the groove; saidjzig-Za P having thus slowed down thedisplacement of the of the inertia block are so many factors which can be varied at will in order to increase or decrease the desired efiect, which is to delay the moment when the arming of the fuze or the ignition takes place.

The fuze can be designed with consideration to the characteristics of the equipment serving to discharge the projectile, the value of the charges employed, the pressures and the accelerations given to the firing of the shot, while assuring either time operation or impact operation, or again, while providing the desired bursting effects such as instantaneous or delayed burst.

According to onefeature of the invention, the aforesaid groove comprises two unequal branches, one at least of which is blind, that is to say ends in a cul-de-sac. The longer of said branches is preferably open at the end. In the position of rest, or the safety position, the slideforming the bolt preferably abuts against the end of the blind branch, the inertia block being immobilised in that position by the thrust of the opposing memher, for example a spring, which tends to keep the slide abutting thereagainst.

Under the action of a sustained thrust greater than the action of the opposing member, such as a positive or negative acceleration, the inertia block is displaced, following the oscillating movement imposed on it by the zig-zag shape of the groove, and the slide proceeds to occupy at the point of the V the intermediate position in which it is engaged in the long branch of the groove. When the thrust or acceleration action ceases, the opposing member reacts, pushing back the inertia block in the opposite direction, while the slide runs along said branch of the groove, escapat the bottom of the blind groove, and the inertia block does not move.

If the accidental shock takes place in the opposite direction, only a slight displacement of the inertia block results; as the latter'is subjected, during this displacement, to the zig-zag movements imposed on it by the groove, it will be stopped by the fact that an axial shock cannot give rise to the necessary rotary lateral movement, and the opposing member will bring back the inertia block to its original safety position before the slide reaches its intermediate position at the point of the V formed by the groove.

This device, used for example to bring about delayed arming and mechanical functioning in an og'ival fuze, is also suitable, by simple inversion or change of direction, for carrying out similar functions in a base fuze, or again in a firing device located inside the projectile.

Thus, in one particular embodiment of the in vention, the groove comprises a long branch and a, blind cavity in which the slide is adapted to engage in such manner as to lock the inertia block, undr the action of the opposing member, when it comes into the armed position.

In this case, the slide first runs along the long branch of the groove under the action of a thrust, such as the propulsive force of the projectile, and then, when said thrust ceases, it is pushed back by the action of the opposing member into the blind cavity, which replaces the short branch of the groove, and thus immobilises the inertia block, which has come into the armed position.

In accordance with a further feature of the invention, the fork of the two branches of the groove is disposed in such manner that one of them, preferably the blind branch, joins the other laterally.

In this manner the slide, when it has run along one of the branches of the groove, engages in the other before or on abutting against the point of the V, and cannot re-enter the branch that it has just left; forking from one branch into the other is thus ensured in certain manner.

It may be desired that the displacement of the inertia block under the action of the opposing member should be rapid and undelayed when the slide leaves its intermediate position.

In this case, the long branch of the groove will be rectilinear and preferably disposed in the axial direction, only the blind branch being zigzag in shape.

In order to reduce the effects of inertia and to avoid all risk of caulking, deformation, and parasitic friction liable to affect the efficiency of operation of the device when it is desired that the latter should be able to resist very violent forces or shocks, for example on the firing of I the shot, provision hasbeen made, according to still a further feature of theinvention, to increase the number of the zig-zags and to decrease their pitch, to such an extent as to give to at least one branch of the groove a generally undulatory outline.

Moreover, in order to ensure, simply and perfectly, the passage of the slide from one branch of the groove into the other, and toavoid lateral tension of the opposingmember, particularly if a spring is involved, the branches of the groove are disposed in such a manner that the safety position and the intermediate position of the slide are on the same longitudinal axis.

It is naturally understood that the use of a lateral tension of the spring to ensure the functioning of the device is in no way excluded.

In one embodiment, the slide is a finger integral with one of the two co-acting pieces. I In another embodiment, a ball partially imprisoned in a groove provided in one of the two co-acting pieces attends to the same function.

Convenient solutions can be found for numerous problems by the practical application of devices complying with the features of the invention, among them, in particular, the following different cases:

A device comprising a cap-carrying inertia block provided with a groove in accordance with the invention;

A device comprising a cap-carrying inertia block provided with a slide in accordance with the invention;

A device comprising a striker-carrying inertia block provided with a groove in accordance with the invention;

A device comprising a striker-carrying inertia block provided with a slide in accordance with the invention;

A device comprising a cap carrier-detonator adapted to pass from an inactive safety position relative to the explosive charge of the projectile to an active position in which the transmission of the explosion can take place normally on impact.

In one example of a fuze corresponding to the features of the invention, two concentric coacting inertia blocks are provided, one of which is immobilised in the safety position in the body of the fuze, through the medium of a yielding member, such as a ball, the liberation of which is dependent on the functioning of the other inertia block, which is subject to the action of the opposing member.

Retarded arming on firing of the shot is thus simply obtained in an instantaneous percussion fuze for projectiles propelled by a gun or acquiring their speed through a self-propelling charge and provided with a percussion head adapted to be driven back on impact.

The external inertia block. can be disposed in such manner as to give, in the safety position, supplementary protection to the cap set back in the internal inertia block.

The invention also enables a very simple fuze to be designed for projectiles propelled by a gun or by self-propulsion, the arming of which takes place only on impact, the functioning of the fuze taking place through delayed percussion, only after braking and stopping of the projectile in the ground or any other objective, the opposing member being disposed in such manner that it reacts on the inertia block only on impact, the delay being produced at that moment.

Finally, the device of the invention can also be utilised to liberate, with delay, an obturator designed to prevent transmission of fire prematurely.

In this case, the inertia block can take the form of an obturating bell which, in the safety position, covers the piece with which it co-acts through the medium of the slide and groove of the invention, said bell preventing the transmission of fire until it is ejected by the action of the opposing member. Y

Other advantages and features of the invenreadily understood, reference is made to the ac-' 'companying drawings which illustrate diagram matically' and by way of example, various embodiments thereof, andin which:

Figs. l'to '7 inclusive represent in axial section a fuze: in accordance with the invention and, in front view, its inertia block provided with grooves, in the various stages of operation;

Figs. 8, 9 and 10' show a fuze comprising a mobile detonator, in the safety position and in the armed position, as well as its inertia block;

Figs. 11 and 12 represent respectively a fuze intended to be placed inside a projectile, and its inertia block; 2

Figs. 13 and 14 illustrate respectively an inertia fuze with delayed arming, and its inertia block;

Figs. 15 to 22 inclusive represent respectively various modifications of devices according to the invention, comprising an inertia block forming a bell-designed to prevent premature firing;

Fig. 22a shows an application of the device represented in Figs. 15 and 22.

Figs 23 to 27 inclusive represent respectively in various stages of operation,- a fuze designed to function with delayed percussion, together with its inertia block.

In order to facilitate understanding, parts serving the same purpose ineach of the various figures have been designated by the same reference numerals.

' The fu'zeillustrated in Figs. 1 to '7 is composed of a fuze body I provided in front with a percussion head 2, with a striker 3 and, at the rear, with a detonator 4'. An inertia block 5 provided with a cap 6 and subject to the action of a compression spring I, which acts as opposing member by hearing against a rear rest 8 on the fuze body, is adapted to move axially in a cylindrical cavity 9 provided in the member co-acting with said inertia block 5. This co-acting member is generally the body I itself; in the embodiment illustrated in Figs. 1, to '7, this member is a second inertia block II) concentric with the inertia block 5' and resting, in the safety position, on an annular projection II on the body I; this second inertia block I is disposed to be movable axially inside a cylindrical cavity I2 formed by the fuze body I.

Union between the two inertia blocks and Ill which are co-acting and concentric is achieved, according to the invention, by means of a slide I3 integral with the external inertia block I0 and adapted to run along a groove I4 hollowed out in the periphery of the internal inertia block-5.-

The groove I4 (Fig. 2)' comprises two branches of unequal lengths I ia and I4b, disposed in the shape of a V and providing a zig-zag path for the slide I3. The long branch Ma is open at its end I5, while the short branch I4b is blind, that is to say ends in a cul-de-sac at I6. The blind branch Mb runs laterally into the long branch I 4a,'near the end I! of the latter, in such manner that the slide I3, when it is engaged in the long branch, can no longer go back into the blind branch.

A ball i=8 lodged in aperture I9 in the external inertia block I3 (Fig. 1) projects from its aperture, in the safety position, and is engaged in a circular recess 29 provided inside the cylindrical cavity I2, thus immobilising said inertia block IB with the slide I3 when in the safety position.

6 The spring I for its part holds the grooved inertia block 5 against the bottom of the blind groove Itb in the slide I3 acting as bolt.

The outer inertia block Ill, which serves as seating for the inner cap-carrying inertia block 5, is adapted to act as a stop for the head 2' carrying the striker in the event of said head being accidentally driven into the interior of the fuse body I; to this end, said inertia block III is sumciently long so that the striker point 3 can in no case come into contact with the cap I5 as long as the latter is in the safety position (Fig. l), withdrawn in the cylindrical cavity 9.

The striker-carrying head 2 is immobilised by a pin 2i shearable on impact, or by any other means, such as, for example, a circular stop (not shown in the drawings) resting on a thin washer, which is likewis shearable on impact.

Complete tightness of the fuse is obtained by means of an elastic mass 22, consisting of cork, for example, and acting as a stopper at the extremity of the cylindrical cavity I2.

A spring 23, completely expanded, is placed in the housing constituted by the front part of the cylindrical cavity I2, between the internal face 24 of the striker-carrying head 2 and a shoulder 25 on the outer inertia block I9. This Very weak spring 23 serves to keep th unit comprising the two inertia blocks 5 and I0, and therefore the cap 6, at a distance from the striker point 3 when the fuze is armed, and enables the fuze to be given extreme sensitiveness to impact.

In the event of dropping, or if there should be a blow on the fuze head, with sufficient force to shear the pin 2|, while the inertia blocks 5 and Illare in the safety position (Fig. 1), the strikercarrying head can without danger strike with its face 2s against the extremity 26 of the inertia block I8, because the striker point 3 is too short to reach the cap S. The cap-carrying inertia block 5- itself, being immobilised by the slide I3 at th bottom of the path in the blind groove I4b (Fig. 2), cannot move forward; percussion is therefore impossible.

In the case of a blow in the opposite direction, the slide I3 acts as a bolt in the zig-zag groove 54 under the thrust of the spring I, and thus these three members resist any substantial displacement of the cap-carrying inertia block 5, which immediately returns to bear against the slide I3 at the bottom of th blind groove, at I6.

The mode of operation of the fuze illustrated in Figs. 1 to 7 is as follows:

On the firing of the shot, the inertia block 5, through inertia under the propulsive action, compresses the spring I and moves backwards to bear against a circular flange 21 on the fuse body I, taking up the position shown in Fig. 3, while the slide I3, running along the blind branch Nb of the groove I5, takes up its position at the point ll of the V (Fig. l), where it is engaged in the long branch I 4a, in the intermediate or pre-arming position. From that moment it can no longer re-enter the side branch Mb that it has just left.

When the positive acceleration ceases, the spring I pushes the cap-carrying inertia block 5 forward again, the slide I3 then making use of the long branch Ida of the groove, the Zig-zag shape of which obliges said inertia block to perform on its axis an oscillating movement which sloWs down its axial displacement, while the outer inertia block Ill still remains immobilised in the fuse body I by the ball I a-imprisoned in the aperture I9 and in the recess 20.

Before reaching the front extremity of the cylindrical cavity 9, the inertia block 5 releases the ball [-8, which escapes to the interior (Fig. 5), and then the slide l3, which emerges through the open end [5 of the groove 14a. The outer inertia block 10, being released, isin turn carried along axially by the inner inertia block 5 as soon as the latter strikes against a rim 28 on the inertia block H), causing the cap 5 to project forwards through the latter.

When the parts are.in this position, the fuze is armed, the striker 3 and the cap 6 being held apart from one another only by the weak resistance of the spring 23, while the spring i is completely extended.

From that moment percussion is ensured on impact, either by the driving back of the strikercarrying head 2 after shearing of the pin 2! (Fig. 6), or by inertia, the cap-carrying inertia block 5 and the outer inertia block l both moving forwards towards th point of the striker in the event of striker-carrying head 2 not having been'driven back by the objective (Fig. '7).

Figs. 8 to 10 illustrate a shell fuze capable of ensuring at the same time complete safety during storage and on firing, including prevention of any rebound, with displacement of the detonator cap which passes from an inactive safety position relative to the explosive charge of the projectile to an active position, in which the explosive transmission can normally be produced on impact.

A fuze body I, bored from end to end with a single diameter, carries slides l3 serving as stop and control fingers and disposed in such a manner asv to be able to slide in the corresponding grooves M provided, in accordance with the invention, in an inertia block 5 placed at any desired distance inside the body I.

Each groove M (Fig. 9) comprises two branches Ma and Mb disposed in the shape of a V, which provide a zig-zag path for the appertaining slide.

A spring 1 applies at one end a pressure against the inertia block 5, which keeps it bearing against the slides 13 at the bottom of the blind grooves Mb, and, at the other, keeps'the. detonator 4, mounted on a second inertia block [0, bearing against the rear end 29 of the fuze body I.

A spring 38, decidedly weaker than the spring I, remains compressed in the waiting position between the lower surface 3! of the inertia block In and the bottom 29 of the fuze body.

A striker-carrying stopper 2, placed in the head of the fuze body I, attends to the sealing of the latter; this stopper is provided with an extended striker 3, which passes right through the grooved inertia block 5 and enters the interior bore 9 of the cap-carrying inertia block Iii, at the base of which is located the cap 6.

' In the case of an accidental blow on the fuze, the grooved inertia block 5 will react as described above and ensure the absolute safety of the device.

On the firing of the shot, said inertia block 5, under the influence of the propulsive effect and through inertia, causes the spring 1 to yield, travels backwards in a reciprocating rotary movement imposed on it by the branches Mb of the grooves, and the slides l3 move to the point of the V, at N (Fig. 9)

After firing, at the end of the propulsive thrust, the spring I returns the inertia block 5 forwards, the slides 13 then each utilising respectively the zig-zag pathsof the grooves 14a. By reason of the backward and forward travel, displacement of the inertia block towards the front is slowed down until the slides l3, reaching the end iii of the grooves Ma, escape from the latter. At that moment, no longer under the influence of the spring 1, which is extended, but under that of the spring 30, the parts take up the armed position illustrated in Fig. 10. Percussion on impact is from that moment ensured.

The device forming the subject of the invention can also be utilised in such manner as to operate a pyrotechnical or mechanical time fuze, as illustrated in Fig. 11.

The fuze body I, bored throughout it length, is provided with a detonator-carrying head 2 carrying a cap 5 and a detonator 4. A slide l3, integral with the body I, is engaged in thesafety position in the blind branch Mb of a V-shaped zig-zag groove M disposed on a striker-carrying inertia block 5 which a spring 1, bearing on the base 29 of said body, holds against the slide i3 at the bottom of the blind groove Mb.

In the case of accidental shock, the strikercarrying inertia block 5 is held in the safety position, as hereinabove described, by the combined action of the'slide I3, the groove M, and the spring 1.

On the firing of the shot, the striker-carrying inertia block 5, under the influence of the propulsive effect and following the movements imposed on it by the zig-zag groove Mb, compresses the spring "I until the slide 13 reaches the end of the blind groove, where it forks into the long groove Ma. As soon as the propulsive effect ceases, the spring I returns the inertia block forwards; it then follows the movements imposed on it by the long branch Ma of the groove, and then, when the slide l3 reaches the outlet l5 of the latter, it is released and is thrown by the spring 1 towards the cap 6, in which its point penetrates and gives rise to the firing.

Fig. 12 shows that the blind branch Mb of the groove may, like the long branch Ma, have several successive zig-zags, the effect of which is to increase the delay and not to permit the slide [3 to assume the pre-arming position I! except under a longer thrust effect.

Figs. 13 and 14 relate to a device combined in such a manner as to obtain an inertia fuze with delayed arming, for projectiles preferably propelled by self-propulsion.

The fuze comprises a body I in which are housed a grooved inertia block 5 provided with a striker 3, a cap-carrying inertia block l0 provided with a cap 6 and a detonators, and a spring 7 bearing at one end on the striker-carrying inertia block and, at the other end, on the capcarrying inertia block. In the safety position, the sring -1 tends to keep the two inertia blocks apart from one another. The total path available to the cap-carrying inertia block [0 as far as a stop 32 provided on the fuze body does not enable the cap to touch the striker point.

Since, moreover, the striker is immobilised, as hereinbefore described, .by the combined action of slides I3 on grooves M and of the spring 1 on the grooved inertia block 5, security against shocks, either on the'nose of the fuze or in the opposite direction, is assured.

In this particular case, the blind branch Mb of the groove 14 is reduced to a blind cavity I6 adapted to receive the slide l3 at the end of the path, said slide being located at the entrance l5 of the long branch Ma (Fig. 14) as long as it is in the safety position.

On the firing of the shot, under the influence of the propulsive effect the striker-carrying the rear until the slide 13, has reached the extremity ll of said groove.

As soon as the propulsive effect ceases, the spring 1 returns the inertia block 5 in the opposite direction; the slide 13, taking up position in.

the cavity 16 which forms a stop, thus keeps the striker 3 held in such manner that, on impact, the point 3 will penetrate the cap 6 when the cap-carrying inertia block Iii meets it.

In one particular embodiment of the invention, the device of the invention may also be utilized to release, with delay, an obturator designed to prevent premature transmission of firing (Fig. .15).

Inside a suitable jacket 1, an inertia block 5 forms an obturation bell and carries a slide [3 in the form of a stop and control finger. The bell inertia block 5 fits over and caps a projection forming a support 33, which constitutes the coacting member and carries the zig-zag groove [4 (Fig. 16),,and has the central aperture 33a through which fire can pass to the detonator.

An ejection spring 1 in this aperture holds the bell inertia block 5 against the slide 13 at the bottom of the blind groove Mb of the support 33.

In this safety position, the bell prevents the transmission of firing or of the explosive wave from the cap of a fuze located in the front or nose end of the projectile.

On the firing of the shot, the bell inertia block 5, under the influence of the propulsive effect and through inertia, follows the movements imposed on it by the blind groove Mb, compressing the spring 1 until the end of the path of the slide I 3 in said groove, said slide then taking up position at IT.

As soon as the propulsive effect ceases, the spring I returns the obturation bell 5 to the front; said bell then follows the movements imposed on it by the zig-zags of the long branch Ma of the groove in which the slide I 3 runs, and then, when the latter reaches the outlet l5 of said groove, the bell is ejected by the spring 7, thus freeing the fire passage orifice. Transmission of firing may take place from that moment on.

The specific structure shown in Fig. 15 has the body I formed with a cylindrical inner wall spaced from the projection or support 33 to provide an annular cavity in which is closely received the cylindrical skirt 5b of the obturator bell. The externally conical closed forward end 5a of the bell is thicker than the lateral skirt Wall 5b. The illustrated arrangement has the technical advantage of increasing the safety factor of the mechanical delay device. Thus, if premature fire from a nose primer of a fuze 37 (Fig. 22a)'is projected against the head 5a, While the obturator is in safety position, the fire is compelled to follow a tortuous path between the wall 1 and the skirt of the obturator bell 5, and then between this skirt and the coaxial projection 33, and finally through the central aperture or passage in the projection 33. The illustrated shaping and proportioning of the 'j'closed forward end provides greater heat absorp- 1 5. .11 angg te ame t "p fi ation curin il rie jfiir ns. peri d o the jr imer c n J v Fig. 17 illustrates a' modification-of the device illustrated in Fig. 15,. in which modification the slide I3 is integral with the jacket I, while the groove I4 is carried by the bell inertia block 5 and is disposed in the opposite direction (Fig. 18). The mode of operation is the same as in the case of Fig. 15.

the

In the modification illustrated in Fig. 19, the general disposition is the same as in the case of Fig. 15, but it comprises two grooves disposed in such manner that the ejection of the bell inertia block 5 is instantaneous when theslide i 3 is caused to leave its intermediate position. This result is obtained by giving the long branch of Na of the groove a rectilinear shape,

while only the blind branch Mb has zig-zags.

(Fig. 20). The spring 7 being very weak in order to give the device great sensitiveness, the branch Mb of the groove hasbeen made longer than hitherto in order to force the slide to travel over a longer zig-zag path before reaching the intermediate position II.

In addition, by way of example, the slide is designed in the form of a ball is imprisoned in a recess .34 in the bell inertia block 5, which gives it greater flexibility in operation.

In order to enable the device to resist even very violent shocks, either during handling or on the firing of the shot, and to avoid all risk of caulking, deformation, or parasitic friction liable to impair good operation, provision has been made, in the arrangement illustratedin Fig. 2l,for a greater number of backward and forward movements in the groove 14, while reducing the length of each such movement. The branches Ma and Mb of the groove time assume a generally undulatory shape.

The grooves may also be disposedin the manner illustrated in Fig. 22, so that the safety position l6 of the slide l3 and its intermediate or pre-arming position I! are in the same longitudinal axis X--X. While ensuring in perfect fashion the passage of the slide l3 from the groove Mb into the groove Ma, this enables all lateral tension of the return spring 7 to be avoided in the event of that occurring in consequence of the oblique position of the groove.

Fig. 22a shows how the obturator device described in connection with Fig. 15 may be employed in'a projectile 4| having a cavity 42 between the front end and the obturator 5. The primer cap in an impact fuze 3! at the nose of the projectile is to be fired on impact, transmitting. its fire or explosive wave rearward through this cavity along the axis of the projectile: but so long as the obturator bell 5 is in safety position, the detonator 38 is not energized. Thus, the device is safe against explosion of the charge 39, 40 prior to the normal propulsion of the projectile. During the early part of thetrajectory of the projectile, the obturator hell 5 moves rearward from its safety position, with its slide I3 passing from the 'full line position to the dotted line position of in Fig. 2%., thereby uncovering the aperture through the 'projectioufit (Fig; '15) and permitting the fire from theprime r cap of fuse .37

11 then to have passage through the aperture to the detonator 38 for energizing the same, wherewith the explosive charge 39, 40 is detonated.

The device forming the subject of the invention also renders it possible to provide, for projectiles discharged by guns or by self-propulsion, a very simple fuze the arming of which takes place on impact, operation by delayed percussion taking place only after braking or stoppage of the projectile in the ground or any other objective.

Figs. 23 to 2'7 relate to such a device. A capcarrying fuze body I of great strength carries the slide or slides l3, the groove or grooves l4 being placed on a striker-carrying inertia block 5; a spring 1 holds said inertia block, in the safety position, against the slide l3 at the bottom of the blind groove Mb (Figs. 23 and 24). A supplementary stop, for example consisting of balls 35, may if desired be provided (Fig. 2'7) if firing is to take place with very great accelerations on discharge of the shot.

Safety in the position of rest is ensured by the cooperation of the slide I3, the groove [41), and the spring I, in the same manner as hereinbefore described.

n the firing of the shot, the position of the parts remains unchanged. On impact, the projectile loses its speed and, after penetration to a greater or lesser degree, depending on the resistance of the target, is completely stopped. In consequence of this braking effect, the strikercarrying inertia block 5, owing to its residual kinetic energy, is carried forward, compressing the spring 1 (Fig. 25).

In the embodiment illustrated in Fig. 27, the balls 35, released when the inertia block moves forward, leave their annular housing 36 and take up position behind the inertia block.

As soon as the projectile has stopped, the spring I returns the inertia block 5 to the rear, the zig-zag groove Ma first imposing on it a slow movement after which, when the slide I3 leaves said groove, the spring 1 throws the strikercarrying inertia block 5 against the cap 6, which fires.

What I claim is:

1. A mechanical safety delay device for a projectile fuze having a body with an aperture through which fire is to be transmitted as an incident of detonation, comprising two main co-acting parts, one of which parts is an ejectable obturator and the other part is a body projection having said aperture extending therethrough, said obturator part having the shape of a bell and being located when in safety position around said projection and covering the aperture and thereby preventing the transmission of fire, one of said main co-acting parts having at least one groove formed by two converging branches, the other of said co-acting parts having a sliding member adapted to run in said groove, one branch of said groove having a blind end for receiving the sliding member when in safety position and preventing forward movement of the said obturator part, said one branch having a zig-zag shape for co-acting with the sliding member during positive acceleration of the projectile and thereby effecting a slowing down of theinertial relative rearward movement of the obturator part by rotary oscillating movements imparted thereto, the converging point of saidg-branches being axially aligned with the ,said. .oth,er branchthereof so that a forward movement of the obturator part after the sliding member has come to the converging point will cause the sliding member to enter the said other branch, said other branch having an open end remote from said converging point whereby the sliding member is released by the groove during forward movement of the obturator part while the member is moving along said other branch, and therewith the obturator is ejected from its covering position, and an op posing member effective to maintain said obturator part normally in a safety position prior to the positive acceleration of the projectile.

2. A mechanical safety delay device for a projectile fuze having a body with an aperture through which fire is to be transmitted as an incident of detonation, comprising two main co acting parts, one of which parts is an ejectable obturator and the other part is a body projection having said aperture extended therethrough, said obturator part having the shape of a bell with the forward end thereof being a head of external conical shape and having greater thickness than the lateral wall portion of said bell, the bell being located when in safety position around said projection and covering the aperture and thereby preventing the transmission of fire, one of said main co-acting parts having at least one groove formed by two converging branches, the other of said co-acting parts having a sliding member adapted to run in said groove, one branch of said groove having a blind end for receiving the sliding member when in safety position and preventing forward movement of the said obturator part, said one branch having a zig-zag shape for co-acting with the sliding member during positive acceleration of the projectile and thereby effecting a slowing down of the inertial relative rearward movement of the obturator part by rotary oscillating movements imparted thereto, the converging point of said branches being axially aligned with the said other branch thereof so that a forward movement of the obturator part after the sliding member has come to the converging point will cause the sliding member to enter the said other branch, said other branch having an open end remote from said converging point whereby the sliding member is released by the groove during forward movement of the obturator part while the sliding member is moving along said other branch, and therewith the obturator is ejected from its covering position, and an opposing member efi'ective to maintain said obturator part normally in a safety position prior to the positive acceleration of the projectile.

3. A mechanical safety delay device for a projectile fuze having a body with an-aperture through which fire is to be transmitted as an incident of detonation, comprising two main co-acting parts, one of which parts is an ejectable obturator and the other part comprises a body projection having said aperture extended therethrough and a peripheral cylindrical wall spaced from and concentric with said projection, said obturator part having the shape of a bell with a cylindrical skirt closely fitting and movable in the space between said projection and said wall, said bell when in safety position covering the aperture in said projection and thereby preventing the transmission of fire through said aperture, one of the said main co-acting parts having at least one groove formed by two converging branches, the other of said co-acting parts having a sliding member adapted to run in "said groove, one branch of said groove having a blind end for receiv'ingthe sliding member when down of the inertial relative rearward movement of the obturator part by rotary oscillating movements imparted thereto, the converging point of said branches being axially aligned with th said other branch thereof so that a forward movement of the obturator part after the sliding member has come to the converging point will cause the sliding member to enter the said other branch, said other branch having an open end remote from said converging point whereby the sliding member is released by the groove during forward movement of the obturator part while the member is'moving along said other branch. and therewith the obturator is ejected from its covering position, and an opposing member effective to maintain said obturator part normally in a safety position prior to the positive acceleration of the projectile.

EDGAR WILLIAM BRANDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,053,857 Nordenfelt Feb. 18, 1913 1,792,631 Deevy Feb. 1'7, 1931 FOREIGN PATENTS Number Country Date 18,185 Great Britain of 1905 359,102 Germany Sept. 19, 1922 489,020 Great Britain App. data 1936 695,190 France Sept. 29, 1930

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