US1944780A - Percussion fuse of high sensitivity - Google Patents

Description

Jan. 23, 1934. E w. BRANDT PERCUSSION FUSE OF HIGH SENSITIVITY Filed Nov. 12, 1952 4 Sheets-Sheet 1 4 Sheets-Sheet 2 E. W. BRANDT PERCUSSION FUSE OF HIGH SENSITIVITY Filed Nov. 12, 1932 1E ll Jan. 23, 1934.

Jan. 23, 1934.

E. W. BRANDT PERCUSSION FUSE OF HIGH SENSITIVITY Filed NOV. 12, 1932 4 Sheets-Sheet S Jan. 23, 1934. E. w. BRANDT PERCUSSION FUSE OF HIGH SENSITIVITY 4 Sheets-Sheet 4 Filed Nov. 12, 1932 Patented Jan. 23, 1934 Application November 12, 1932, Serial No. 642,443, and in France November 30, 1931 9 Claims.

The present invention relates to a percussion fuse of high sensitivity which is capable of being employed with projectiles of various types, whether discharged from smooth-bore barrels or from rifled barrels.

It more particularly proposes a fuse of this type in which the number of individual pieces is reduced to a minimum, and which has especially the advantage of an absolute safety against premature percussion resulting from encounter with an accidental obstacle either within the barrel, or at its mouth, or even at a certain distance from the barrel.

This type of fuse, having a primer holder capable of sliding longitudinally in an axial recess which opens, adjacent a firing pin, into an annular space of larger diameter, is remarkable especially in that one or more locking elements located in lateral recesses of the primer holder, are retained by the walls of the cavity in such fashion as to form a safety screen above the primer, these locking elements only being able to escape laterally, for permitting percussion, at the moment when the primer holder penetrates into the annular space of larger diameter.

According to another characteristic of this invention, the primer holder is normally held against movement by means of a safety device which is eliminated at the moment of firing.

Further, the primer holder is disposed in such manner as to be moved forward by inertia, by reason of the deceleration impressed upon the projectile byair resistance; its movement being, however, pneumatically braked by the air which may only escape gradually from the front toward the rear between the walls of the primer holder and the walls of its cavity.

Further advantages and details of the invention will appear from the following description.

On the accompanying drawings, given only by way of example:

Figure 1 is an axial section of a fuse according to this invention, shown in the state of rest.

Figures 2 to 4 are similar views showing, respectively, the positions taken by the parts at the moment of firing, during the safety distance from the mouth of the weapon, and beyond this distance.

Figures 5 and 6 show, respectively, the positions of the parts in case of sudden braking or retardation in the barrel and in case of premature impact during the safety distance.

Figures 7 and 8 represent, respectively, the fuse at the moment of impact, by simple driving back, and of impact by driving back and inertia.

Figure 9 shows a detail in elevation.

Figure 10 is a section on line 1010 of Figure 5.

Figure 11 is a transverse section on line 1111 of Figure 7.

Figures 12 and 13 are analogous views of a modified form showing, respectively, the positions occupied by the parts while at rest and at im- 5 pact.

According to the form of execution represented in Figures 1 to 11, the fuse comprises a body 1, pierced by a drilled or bored hole 2, in which may slide a very light striker or firing pin 3 which is urged forward by a spring 4. This spring is supported at the rear by a flanged washer 5 which surrounds a tubular element 6 that rests on the bottom of the hole 2. The washer 5 assists in guiding the firing pin 3. The forward portion of the element 6 is hollowed internally and provides just below the firing pin 3 an annular space '7 of greater diameter than the rest of its internal bore. The element 6 can slide in the hole 2 in which it is perfectly guided by a ring 8 and by the washer 5.

A primer holder 9, enclosing a primer 10, is disposed in the tubular element 6, within which it can slide longitudinally. Locking or distance elements such as the balls 11 are disposed above the primer 10 in perforations 12 provided in the walls of the primer holder, and oppose the' passage of the firing pin 3, while the channels 12 are opposite the small diameter of the bore hole in the element 6. The diameter of balls 13 is preferably greater than the thickness of the wall of the primer holder augmented by the side clearances between the primer holder and the tubular element 6 on one side and the firing pin 3 on the other side. The perforations or channels 12 are preferably obliquely directed to the longitudinal axis of the fuse body as shown in the drawings.

The primer holder itself is, prior to any functioning of the fuse, locked in a safety position by aid of a suitable safety device. In the present example, this safety device is constituted by a set of balls 13 which are disposed in cavities 14. (Figs. 1 and 9). A groove 15, which is capable of receiving the balls, extends over the external periphery of the element 6, at the point of the cavities 14.

When the functioning of the fuse has not been initiated, the balls 13 are normally retained in locking position for the primer holder by a sleeve 16 which is urged forward by a spring 17 bearing rearwards against ring 8. An abutment 18 limits the displacement of the ring toward the front with respect to the element 6.

A closing ring 19, mounted in the fuse body in front of the firing pin 3, preferably assures the water tightness of the fuse.

The operation is as follows:

At the moment of firing, under the prolonged action of the positive acceleration impressed on the projectile by the propulsive charge, the firing pin 3 and the sleeve 16 are displaced by inertia and compress their respective springs 4 and 1'7; the balls 13 are liberated and escape into the groove 15 (Fig. 2). After the cessation of this positive acceleration, the spring 4 returns the firing pin into its initial position (Fig. 3) and the sleeve 16, pressed by the spring 17, blocks the balls 13 in the groove 15 and prevents their inward movement.

When the velocity of the projectile is being slowed down by reason of the air resistance (negative acceleration), the primer holder moves forward in the tubular element 6 by inertia, and finally comes to occupy the position of Fig. 4. The balls 11, located around the primer holder from point to point, find an annular space of greater diameter than that in the lower portion of the tubular element 6, and can move radially away from the firing pin and permit it free passage toward the primer. From this moment, the fuse is armed.

However it is proper to remark that the primer holder requires a certain length of time for moving forward by inertia under the effect of the negative acceleration of the projectile body, from the position of Figure 2 into that of Figure 4; further this displacement provokes the passage, to the rear face of the primer holder, of a part of the air which was originally present at the front face of this holder. This fiow of air, which may only occur gradually by reason of the small play left between the walls of the primer holder and the walls of the tubular element 6, constitutes a resistance which determines the time of retardation, for arming, and which may be modified by the particular construction of these two elements.

This length of time corresponds to a safety distance for the extent of which the fuse remains inert. In effect, in this space:

1. An encounter with an accidental obstacle of suflicient consistency to provoke at the same time a driving back of the firing pin and a certain deceleration of the projectile will occasion, by inertia, the displacement of the primer holder toward the front of the tubular element 6 (Fig. 6), but the balls 11, maintained in safety position by the walls of this tubular element, will absolutely prevent the contact of the firing pin and the primer.

2. A sudden braking, occurring accidentally in the gun barrel, will cause, by inertia, a projection of all the elements toward the front (Fig. 5) However, even in this case, the balls 11 are retained interposed between the firing pin and the primer, and will render any percussion impossible.

Safety at the mouth and safety within the barrel are thus attained in a positive manner in all cases.

At impact, the percussion may be effected either by driving back of the firing pin (Fig. 7), or by forward movement of the primer holder by inertia, or by driving back and inertia (Fig. 8).

In the first case, the primer holder is precipitated with a velocity substantially equal to that of the projectile onto the firing pin which has been abruptly arrested on the target. The balls remain in contact with the primer holder and thus prevent any possible rearward movement of the latter on being encountered by the firing In the second case, which may occur if the projectile alone come into contact with the target, the tubular element 6 and the balls 13 and the sleeve 16 under the effect of the high negative acceleration to which the projectile is subjected then add their mass to that of the primer holder for overcoming the spring 4, and thus permit the primer holder to precipitate itself onto the firing pin.

Finally, in a case where the firing pin encounters an obstacle of insuflicient resistance to drive it fully backward, yet the percussion is obtained under the combined effect of the partial driving back of the firing pin and of the inertia of the primer holder (Fig. 8).

The functioning of the fuse is very sensitive and an obstacle of very slight mass is sufficient to actuate it. This sensitivity is attained on the one hand by reason of the extreme lightness of the firing pin, and on the other hand by the absence of any safety element (pin, diaphragm, etc.) capable of opposing, at the moment of impact, the driving back of the firing pin.

V In case of a fall of the projectile during trans.- portation and handling, no percussion may be produced, since:

The sleeve 16 will maintain, in a positive manner, the balls 13 in safety position in case of a fall of a projectile on its head or nose.

The sleeve 16 will simply compress its spring without uncovering the openings for the escape of balls 13, in case of a fall of projectile'on its base; and even if the projectile is dropped from a height sufiicient to permit the sleeve 16 to come, under the effect of shock, to the bottom of its movement, its spring 17 will return it into the locking position before the balls 13 will have time to assume an appreciable displacement in their cavities.

The safety is thus complete in all cases.

The fuse according to this invention is, preferably, combined with a device permitting obtaining, at will, the firing of the detonator either instantaneously or with delay. In the present example, this device comprises two passages20, 21 (Fig. 1) traversing the base 22 of the fuse and capable of establishing communication between the primer 10 and the detonator 23-- In one of these passages (20) is mounted a retarding composition 24 and, in the other, a valve 25 which may be actuated directly from. the exterior. When the valve is in the open position (Fig. 1) the flame from the primer 10 is transmitted directly by passage 21 to the detonator 23 (instantaneous operation); when the valve is in closed position (Fig. 2), the primer first ignites the composition 24 which burns fora certain length of time and thereafter transmits the fire to the detonator (delay operation).

Figures 12 and 13 show a modification of construction of the fuse according to this invention. In this examplethe primer holder 9 slides in a hole 2 of the fuse body itself. The locking sleeve 16 for the ball or balls 13 is mounted within the primer holder and is urged forwardly by its spring 1'7 which bears, at the rear, on a ring 30 fixed to the primer holder. The balls 13 are lodged. in channels 14: of the primer holder,

which are preferably inclined rearwardly toward the axis. Screws 31 or analogous elements are mounted in perforations of the fuse body and permit placing the balls 13, during assembly, in

position for blocking the primer holder.

A cup 33 rests on a shoulder 34 of the fuse body and serves as a rearward support for the spring 4 of the firing pin and can itself slide forwardly in the fuse body 1.

At the moment of firing, under the effect of the continuous positive acceleration impressed on the projectile by the propulsive charge, the sleeve lfi is moved out of the way and liberates the ball or balls 18 which escape to the interior of the primer holder. The latter, being thus unlocked moves forward in the hole 2 and carries the ball or balls 13 with it, these being locked by the spring 17 (Fig. 12), and the functioning of this fuse is thereafter in all ways similar to that of the preceding example. The position of the elements at impact, with the driving back of the firing pin is represented in Figure 13. The fuse, mounted on a rotative projectile, will operate in a manner identical with that which has just been indicated; the conditions for safety remain the same.

The simplicity of its construction permits manufacturing it even of very small dimensions and, consequently, of using it, if desired, for the priming of projectiles of very small calibre.

Naturally the invention is not limited to the forms of construction shown and described, as these have only been chosen by way of examples.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:-

l. A direct-action percussion fuse comprising a body having an axially directed elongated cavity, said cavity opening out adjacent its forward end into an enlarged space, a striker adapted to be pushed backward through and beyond said enlarged space into said cavity by an obstacle, a primer, 2. primer holder movable axially in the cavity, a releasable safety device for locking said primer holder adjacent the backward end of the cavity, distance elements carried by the primer holder and retained by the wall of the cavity in an inward position where they screen the primer against impact of the striker, the primer holder being free after firing to creep forward in the cavity by inertia when the projectile is being retarded air resistance and thus reach the enlarged space into which the distance elements can escape outwardly for unscreening the primer thus arming the fuse.

2. A direct-action percussion fuse comprising a body having an axially directed elongated cavity, said cavity opening out adjacent its for ward end into an enlarged space, a striker adapted to be pushed backward through and beyond said enlarged space into said cavity by an obstacle, a primer, a primer holder closely fitting and movable axially in the cavity, a releasable safety device for locking said primer holder adjacent the backward end of the cavity, distance elements carried by the primer holder and retained by the wall of the cavity in an inward position where they screen the primer against impact of the striker, the primer holder being free after firing to creep forward in the cavity by inertia when the projectile is being retarded by air resistance and thus reach the enlarged space into which the distance elements can escape outwardly for unscreening the primer thus arming the fuse, the clearance between the primer holder and the wall of the cavity being such that the air in the cavity can flow but gradually towards the rear end of the primer holder whereby to brake its forward movement.

3. A direct-action percussion fuse comprising a body having an axially directed elongated cavity, said cavity opening out adjacent its forward end into an enlarged space, a striker adapted to be pushed backward through and beyond said enlarged space into said cavity by an obstacle, a primer, a primer holder movable axially in the cavity, a releasable safety device for locking said primer holder adjacent the backward end of said cavity, distance balls lodged in holes of the primer holder and retained by the wall of the cavity in an inward position where they screen the primer against impact of the striker, the primer holder being free after firing to creep forward in the cavity by inertia when the projectile is being retarded by air resistance and thus reach the enlarged space into which the distance balls can escape outwardly for unscreening the primer thus arming the fuse.

4. A direct-action percussion fuse comprising a body having an axially directed elongated cavity, said cavity opening out adjacent its forward end into an enlarged space, a striker adapted to be pushed backward through and beyond said enlarged space into said cavity by an obstacle, a primer, a primer holder movable in the cavity, a releasable safety device for locking said primer holder adjacent the backward end of said cavity, distance balls lodged in holes of the primer holder, said holes being obliquely directed forwardly and outwardly with respect to the'lon'gitudinal axis of the fuse body, said balls being retamed by the wall of the cavity in an inward position where they screen the primer against impact of the striker, the primer holder being free after firing to creep forward in the cavity'by inertia when the projectile is being retarded by air resistance and thus reach the enlarged space into which the distance balls can escape outwardly for unscrecning the primer thus arming the fuse.

5. A direct-action percussion fuse comprising a body having an axially directed elongated cavity, said cavity opening out adjacent its forward end into an enlarged space, a striker adapted to be pushed backward through and beyondsai'd enlarged space into said cavity by an obstacle, a primer, a primer holder movable axially in the cavity, said primer holder having a tubular forward part, a releasable safety device for locking said primer holder adjacent the backward end of the cavity, distance balls lodged in holes of the primer holder, the diameter of said balls being greater than the thickness of the tubular part of the primer holder augmented by the clearances between the primer holder and the cavity, on one side and the striker on the other side, said balls being retained by the wall of the cavity in an inward position where they screen the primer against impact of the striker, the primer holder being free after firing to creep forward in the cavity by inertia when the projectile is being retarded by air resistance and thus reach the enlarged space into which the distance balls can escape outwardly for unscreening the primer thus arming the fuse.

6. A direct-action percussion fuse comprising a fixed structure having an axially directed elongated passage, a tube movable axially in the passage and having an axial cavity which is narrow toward the rearward end and has an enlargement adjacent the forward end, a spring constraining said tube in the opposite direction to the direction of travel of said projectile, a striker adapted to be pushed backward through and beyond said enlargement into the narrow portion of said tube by an obstacle, a primer, a primer holder movable axially in the tube, a releasable safety device for locking said primer holder adjacent the backward end of the tube, distance elements carried by the primer holder and retained by the wall of the tube in an inward position where they screen the primer against impact of the striker, the primer holder being free after firing to creep forward in the tube by inertia when the projectile is being retarded by air resistance and thus reach the enlarged space into which the distance elements can escape outwardly for unscreening the primer thus arming the fuse, the tube being free after firing to move forward against the spring by inertia and bring its narrower part opposite the striker, so that the striker will prevent said distance elements reaching the enlargements and thus the distance elements will be retained in safe position and percussion prevented in the case of a sudden deceleration being imparted to the projectile before the primer holder has reached the enlargement.

'7. A direct-action percussion fuse comprising a fixed structure having an axially directed elongated passage, a tube movable axially in the passage and having an axial cavity which is narrow toward the rearward end and has an enlargement adjacent the forward end, a striker adapted to be pushed backward through and beyond said enlargement into the narrow portion of said tube by an obstacle, a spring interposed between said tube and said striker, a primer, a primer holder movable in the tube, a releasable safety device for locking said primer holder adjacent the backward end of the tube, distance elements carried by the primer holder and retained by the wall of the tube in an inward position where they screen the primer against impact of the striker, the primer holder being free after firing to creep forward in the tube by inertia when the projectile is being retarded by air resistance and thus reach the enlarged space into which the distance elements can escape outwardly for unscreening the primer thus arming the fuse, the tube being free after firing to move forward against the spring by inertia and bring its narrower part opposite with the striker, so that the striker will prevent said distance elements reaching the enlargements and thus the distance-elements will be retained in safe position and percussion prevented in the case of a deceleration being imparted to the projectile before the primer holder has reached the enlargement.

8. A direct-action percussion fuse comprising a fixed structure having an axially directed elongated passage, a tube movable axially in the passage and having an axial cavity which is narrow toward the rearward end and has an enlargement adjacent the forward end, a spring constraining said tube in the opposite direction to the direction of travel of said projectile, a striker adapted to be pushed backward through and beyond said enlargement into the narrow portion of said tube by an obstacle, a primer, a primer holder movable axially in the tube, said tube having a perforation in its wall and a peripheral groove communicating with said perforation, and a ball located in said perforation and extending into the path of the primer holder while in safety position adjacent the backward end of the tube, a sleeve surrounding said tube, a setting spring constraining said sleeve forwardly for holding the ball in safety position, said sleeve being yieldable at firing to permit the escape of said ball into said groove whereby the primer holder is freed for movement into firing position, said setting spring also operating for returning said sleeve into forward position after the positive acceleration for blocking said ball in said groove, distance elements carried by the primer holder and retained by the wall of the tube in an inward position where they screen the primer against impact of the striker, the primer holder being adapted to creep forward in the tube by inertia on the projectile being retarded by air resistance and thus reach the enlarged space where the distance elements can escape outwardly for unscreening the primer thus arming the fuse, said tube being free after firing to move forward against the spring by inertia and bring its narrower part opposite the striker, so that the striker will prevent said distance elements reaching the enlargements and thus the distance elements will be retained in safe position and percussion prevented in the case of a sudden deceleration being imparted to the projectile before the primer holder has reached the enlargement.

9. A direct-action percussion fuse as in claim 8, wherin the setting spring bears rearwardly against an abutment on the said tube.

EDGAR WILLIAM BRANDT.

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