US2487056A - Hydraulic fuse - Google Patents

Description

J. M. KING HYDRAULIC FUSE Nov. 8, 1949 2 Sheets-Sheet 1 Filed July 9, 1941 Nov. 8, 1949 J. M. KING 2,437,955

HYDRAULIC FUSE Filed July 9, 1941 2 Sheets-Sheet 2 INVENTOR ATTORNEYS Patented Nov. 8, 1949 HYDRAULIC FUSE John M. King, Dover, N. J assignor to the United States of America as represented by the Secretary of War Application July 9, 1941, Serial No. 401,584

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 6 Claims.

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

This invention relates to a hydraulic fuse, and more particularly to a fuse for aerial drop bombs which will fire upon impact with solid surfaces or at predetermined depths after striking water.

In carrying out bombing operations from aircraft over water, it is desirable to employ a fuse which will permit selective settings for the various depths at which the fuse will operate. Likewise it is important that there be incorporated in the fuse, detonating elements which will function instantaneously or with a short time delay when the missile strikes the ground or some solid object.

In accordance with a preferred embodiment of the invention, the fuse is provided with an expansible fluid chamber which is actuated by predetermined hydraulic pressures when the bomb is dropped into water and also an inertia device which fires a delay primer-detonator when the missile strikes a solid objective.

An object of the invention is to provide a fuse for a drop bomb which will function when it 1 strikes water or a solid surface.

Another object of the invention is to provide a detonating fuse which will fire upon impact with a solid objective or at predetermined depths after impact with water.

A further object of the invention is to provide a fuse which is safeguarded from accidental operationduring handling and shipment.

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

Fig. 1 is a front elevation of the fuse,

Fig. 2 is an enlarged vertical longitudinal sectional view of the fuse showing details of construction,

Fig. 3 is a section on the line 3-3 of Fig. 2 showing the equalizer mountings,

Fig. 4 is a sectional view on the line 4--4 of Fig. 2 showing the depth setting mechanism,

Fig. 5 is an enlarged front elevation of a port1on of the fuse when forced into the firing position by hydraulic pressure,

Fig. 6 is a sectional view on the line 6-6 of F1g. 2 showing the Sylphon bellows locked in the inoperative or safety position,

Fig. 7 is a sectional view on the line l--! of Fig.2,and s Fig. 8 is a view in axial section of the pressure disk and its associated pin shearing sleeve.

Referring to the drawings by numerals of reference, the metal fuse body 8 is threaded at 9 to engage the base of a shell or tail of a bomb. A hollow protuberance l0 extends into the shell and carries a firing pin II, which when actuated, engages the primer I2 and detonates the shell.

A cylindrical block l3 has a central bore l4 and is in threaded engagement at I5 with the body 8. See Figs. 2 and 3. The lower end of the block l3 has a threaded skirt I6 which engages an annulus H which in turn engages a threaded plate closure l8. The plate I 8 has an extension l9 and carries a primer 20 which includes a five second delay primer detonator 2i.

Fastened to the extension H! by suitable means is a sleeve 22 having a back plate 23. Within the sleeve 22 is a sliding metal plunger 24 containing at its front end a firing pin 25 facing the primer 20. A coiled spring 26 keeps the plunger and firing pin separated from the primer 20 except under certain conditions which will be discussed later. A headed locking pin 21 passes through apertures in the plunger 24 and the sleeve 22 as shown in Fig. 2. A spring 28 encompasses the pin 21 and is compressed between the head 29 and the sleeve 22 and the assembly is locked in position by the release pin 30.

Block I3 is annularly grooved at 3| and riding in the groove is a rotatable setting ring 32. Ring 32 carries opposed fins 33 which rests in annular channels 34 in the fuse body 8 and the block l3. Packing material 35 is employed to seal the joints between the fins 33 and channels 34 to make this portion of the fuse water-proof.

A cup-shaped cylinder 36 (see Fig. 5) rests with its flanged end 3! on the body 8 and the perforated opposite end 38 engages the open end of a cylinder 39 containing a tetryl charge 40. The lower end of cylinder 39 is threaded into the central portion of plate l8 and communicates with the primer detonator 2 I. A hollow plunger 4| having a tapered nose 42 slides in the cup 36. One end of the firing pin II is threaded into the nose of the plunger 4|. Seated in the hollow plunger is a coiled compression spring 43 which also bears against the base of the cup 36. The side wall of the cup 36 is pierced by a pair of apertures 44 which receive steel locking balls 45.

In the armed position a steel sleeve 46 surrounds the cup 36 covering the apertures 44. The sleeve 46 also encloses a portion of the tetryl charge containing cylinder 39 and is free to slide bsqlswardly in bore l4 on both the fixed cup 36 and the charge container 39. The upper end of the sleeve 46 has an annular enlargement 41 with a tapered upper face 48 and a right angle annular shoulder 49 as shown in Fig. 8. The lower end of the sleeve 46 carries an annular groove 50.

A rigid pressure disk having a perforated cylindrical side wall 52 is contained in a chamber 53 and is centrally clamped in the groove 50 of sleeve 46. The side wall 52 is shallower than the depth of chamber 53. An expansible fluid chamber 54 is formed by "the use of a pair of Sylphon bellows 55 and 56. The inner bellows 55 has one end clamped in the annular groove 50 in sleeve 46 and forms a fluidtight seal. The other end is brazed or soldered to the block |3 near the edge of bore l4. The lower end of the outer bellows 56 is brazed to the disk 5| and the upper end is securely clamped between the skirt l6 of block I3 and the ring IT. This provides a fiuidtight expansion chamber 54.

The skirt l6 of ring I13 has a plurality of apertures 5'! which serve as fiuid ports and permit water to enter the expansible chamber 54. A safety pin 53 is insertable in one of these ports 57 and has its inner end 59 conditioned to engage one of the apertures in the wall 52 of the pressure disk 5|. This prevents movement of the disk 5| and associated movable elements and negatives the danger of accidental firing, in a manner to be described, during handling of the fuse.

Block I3 is provided with a plurality of radially disposed bores 6t which terminate in restricted inner passages of unequal diameters. Shear pins 6! having enlarged heads 62 rest in these bores and carry compression springs 63. pins are restrained by ring 32 against which they are forced by the springs 63. Each shear pin has a different diameter and is selected to shear when a predetermined force corresponding to a hydrostatic pressure at a definite depth .is applied I transversely to the length of the pin. Six pins are employed and five may be selectively presented to be sheared at depths in the order of ten, twenty, thirty, forty, andyfifty feet. The remaining pin is overs-ized and will not be sheared. When cammed inwardly it represents a safety stop for the moving elements.

The inner periphery of the rotary setting ring 32 is provided with five spaced recesses 64 to receive the ends of the heads-62 of the shear pins 6 I. See Fig. 4. The axis of the bore of ring 32 is eccentric to that of the block |3 which carries the shear pins 6|. When the ring 32 is rotated to a selected position so that five of the pins 6| are lodged in recesses 64, a high spot 65 engages the sixth pin and forces it inwardly against the resistance of its spring 63. This pin is conditioned to be sheared by the shoulder 49 on sleeve 46 as shown in Fig. 2. The ring 32 and the body 8 of the fuse are graduated as shown in Fig. 1 to indicate the pin to be sheared at the selected depth.

To counteract the forces of deceleration on the moving parts of the fuse upon water impact, an equalizer is employed. The equalizer comprises a pair of fiyweights 66 on arms 61 which are attached to pivot pins 68 as shown in Figs. 2 and 3. Pins 68 are mounted in the circular block or ring I3. On the side of each pin 68 opposite the flyweight 66 is a projection 68 having a tapered face. This projection 69 is in engagement with the angular enlargement 4'! on the sleeve 46.

The shear The operation of the fuse is as follows: Before the drop bomb is inserted in the bomb suspension of an aeroplane, the safety pin 58 is removed from the fuse to permit the operation of the hydraulic mechanism. When the bomb is released, the pin 30 is withdrawn by the safety wire of the release mechanism. Compression spring 28 expands and withdraws the safety pin 21 to free the plunger 24 which is held in its inoperative position by spring 26.

Should the bomb strike a solid target, the

- plunger 24 is influenced by-inertia and moves forward :the sleeve 22 against the resistance of the spring 2.6 whereupon the firing pin 25 strikes the primer 2.0 and fires the delay primer detonator .21. This in turn fires the tetryl charge 40 which forces the plunger 4| carrying the firing pin H past the retaining balls 45 and into the primer l2 and detonates the shell.

When the bomb falls into water and the hydrostatic mechanism fails to operate, the plunger 24 actuates the firing pin as described above and detonates the shell, thus assuring certainty of function.

Upon landing in water, fluid enters the expansible chamber 54 through the water ports 51. As the bomb sinks below the surface, the hydrostatic head increases and the pressure on the disk 5| is directly proportional to the head. Pressure of the disk 5| is communicated to the attached sleeve 46 and force is applied by the shoulder 49 to a pin 6| which was previously indexed into the shearing position by the setting ring 32. If the fuse was set to operate the firing rod H at a fifty-foot depth, the pin 6| corresponding to that setting will be sheared by the shoulder 49 on sleeve 46' by the fluid pressure existing at that depth. When this occurs the disk 5| strikes the wall of closure |8 as shown in Fig. 5 and the free end of sleeve 46 slides beyond its zone of influence on the retaining balls 45. The tapered face 42 of the plunger 4| forces these balls later- :ally in the recesses 44 because of the force exerted by compression spring '43, and also forces the now released firing pin into the primer I2 and the bomb is exploded.

As the bombis sinking beneath the surface of the water, deceleration takes place because of the added resistanceto its movement. Inertia begins to act upon the movable disk 5|, the bellows mechanism 55 and 516, and the sliding sleeve 46. Its effect is to pull this movable mechanism forward in opposition to the force exerted rearwardly by the increasing hydrostatic force which is being applied to the shear pin 6|. To compensate for this undesirable effect, the fiyweights 6B are rotated about the pins 68 by the effect of inertia upon deceleration. Theextensions 69 on the opposite side of the pivot pins 68 are forced back on the shoulder 48 on sleeve 46 and exert a counterbalancing force for the effect of inertia on the movable pressure system. The pin 6| is therefore sheared at the correct predetermined depth.

I claim:

1. A fuse for a depth bomb comprising a body having fluid ports, a normally armed firing pin in said body, a way for said pin, a compression spring for driving said pin when the pin is released, a fluid pressure operated member in said body adjacent said ports, a latch on said way to retain said firing pin in the armed position, selective depth setting mechanism in said body in latching engagement with said pressure member, said mechanism including shear pins of different shear resistance and a selecting ring, one of said pins adapted to be sheared by a hydrostatic head on said pressure member at a predetermined depth to release said latch and firing pin.

2. A fuse for a depth bomb operable alternatively on water or heavy impact comprising a perforated body, a normally armed firing pin in said body, a way for said pin, a compression spring for driving said pin when the pin is released, a fluid pressure operated member in said body, a latch on said way to retain said firing pin in the armed position, selective depth setting mechanism in said body in latching engagement with said pressure member, said mechanism including shear pins and a selecting ring, one of said pins adapted to besheared by a hydrostatic head on said pressure member at a predetermined depth to release said latch and firing pin, and an inertia firing mechanism to release forceably said latch and firing pin on heavy impact.

3. A fuse for a depth bomb operable alternatively on water or heavy impact comprising a perforated body, a normally armed firing pin in said body, a way for said pin, a compression spring for driving said pin when the pin is released, a fluid pressure operated member in said body, a latch on said pressure member to retain said firing pin in the armed position, selective depth setting mechanism in said body in latching engagement with said pressure member, said mechanism including shear pins and a selecting ring, one of said pins adapted to be sheared by a hydrostatic head on said pressure member at a predetermined depth to release said latch and firing pin, and an inertia firing mechanism having a delay action to release forceably said latch and firing pin on heavy impact.

4. A fuse for a depth bomb operable alternatively on water or heavy impact comprising a perforated body, a normally armed firing pin in said body, a way for said pin, a spring for driving said pin when the pin is released, a fluid pressure operated member in said body, a latch on said pressure member to retain said firing pin in the armed position, selective depth setting mechanism in said body in latching engagement with said pressure member, said mechanism including shear pins and a selecting ring, one of said pins adapted to be sheared by a hydrostatic head on said pressure member at a predetermined depth to release said latch and firing pin, a deceleration compensating lever of the first order pivoted to said body, a flyweight on one end of said lever and the other end engaging said pressure member, and an inertia firing mechanism to release forceably said latch and firing pin on heavy impact.

5. A fuse for a drop bomb comprising a body, a cylindrical block therein, a firing mechanism within said body, an expansible fluid pressure means within said body, selective depth setting means mounted in said body and including a plu rality of shear pins of different shear resistances, respectively, said shear pins being slidably mounted in said cylindrical block and selectively moved into association with said expansible fluid pressure means for causing the same to maintain said firing mechanism inoperative, said expansible fluid pressure means having an annular shoulder cooperating with said cylindrical block and movable relative thereto by expansion of said fluid pressure means for shearing the shear pin selectively moved into association with said expansible fluid pressure means whereby the same will release said firing mechanism for operation.

6. In a fuse for a drop bomb, the combination of a body, a cylindrical block therein, a firing mechanism within said body, a fluid pressure mechanism within said body, a plurality of shear pins of difierent shear resistances, respectively, slidably mounted in said cylindrical block and selectively moved into association with said expansible fluid pressure means for causing the same to maintain said firing mechanism inoperative, a camming ring means rotatively mounted on said body and encompassing the said cylindrical block, spring means biasing said shear pins against said ca/mming ring means whereby the same can selectively move one of said shear pins into association with said expansible fluid pressure means, said expansible fluid pressure means having an annular shoulder relatively movable with respect to said cylindrical block by expansion of said fluid pressure means for shearing the shear pin selectively moved by said camming ring whereby said expansible fluid pressure means will release said firing mechanism for operation.

JOHN M. KING.

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

UNITED STATES PATENTS Number Name Date 431,374 Merriam July 1, 1890 1,314,663 Huber Sept. 2, 1919 1,368,569 Minkler Feb. 15, 1921 1,415,614 Sperry May 9, 1922 1,534,126 Lucas et a1 Apr. 21, 1925 1,639,665 Pratt Aug. 23, 1927 1,943,706 Varaud Jan. 16, 1934

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