US3872790A

US3872790A - Fuze

Info

Publication number: US3872790A
Application number: US717273A
Authority: US
Inventors: John H Mcivor
Original assignee: US Department of Army
Current assignee: US Department of Army
Priority date: 1958-02-24
Filing date: 1958-02-24
Publication date: 1975-03-25
Anticipated expiration: 1992-03-25

Abstract

1. In a fuze for detonating an anti-tank mine, a body, a base secured to said body, a spring-biased pressure plate slidably mounted in said body and said base, a pressure responsive counting-mechanism for delaying detonation of said fuze housed in said pressure plate comprising, a shaft journaled for rotation transversely in said pressure plate, a first retaining clutch integral with said pressure plate, a second driven clutch mounted for free rotation on said shaft, a third clutch mounted on said shaft for rotation therewith and disposed between said first clutch and said second clutch, means fixed with said base adapted to rotate said second clutch upon reciprocal movement of said pressure plate, a firing mechanism housed in said base and a pressure bar integral with said third clutch for actuating said firing means and rotating in response to reciprocal movement of said pressure plate to actuate said firing means.

Description

[ Mar. 25, 1975 0 United States Patent [1 1 Mclvor i 1 FUZE [75] inventor: John H. Mclvor, Denville, NJ.

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

[22] Filed: Feb. 24, 1958 [21] Appl. No.: 717,273

[52] US. Cl. 102/70 R, 102/8 [51] int. Cl F42c 7/02, F42b 23/04 {58] Field of Search 102/8, 70, 82

[56] References Cited UNITED STATES PATENTS 3.429.246 I0/l947 Traylor 102/8 1450,40? l0/l948 Bartgis 102/8 3.450657 l2/l948 Vagts l02/8 2.790.387 4/l957 Billon 102/8 FOREIGN PATENTS OR APPLICATIONS 779.937 7/1957 United Kingdom [02/8 Primary E.raminerBenjamin A. Borchelt Assistant ExaminerC. T. Jordan Attorney, Agent, or Firm-Robert P. Gibson; Eugene E. Stevens, III; Nathan Edelberg EXEMPLARY CLAIM 1. In a fuze detonating an anti-tank mine, a body, a base secured to said body, a spring-biased pressure plate slidably mounted in said body and said base, a pressure responsive countingmechanism for delaying detonation of said fuze housed in said pressure plate comprising, a shaft journaled for rotation transversely in said pressure plate, a first retaining clutch integral with said pressure plate, a second driven clutch mounted for free rotation on said shaft, a third clutch mounted on said shaft for rotation therewith and disposed between said first clutch and said second clutch. means fixed with said base adapted to rotate said sec ond clutch upon reciprocal movement of said pressure plate, a firing mechanism housed in said base and a pressure bar integral with said third clutch for actuating said firing means and rotating in response to reciprocal movement of said pressure plate to actuate said firing means.

2 Claims, 4 Drawing Figures FUZE The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a fuze for anti-tank mines and more particularly to a fuze for use with an anti-tank mine that will function after a specific number of impulses or pressures of a certain magnitude have been applied. Present standard anti-tank mine fuzes of this type are usually attached to the mine and the complete assembly is buried and camouflaged by earth to prevent visual delection, and the mine is exploded as soon as the first tank tread passes over the fuze, resulting in damage usually to the front of the tank only.

Tests have proven that if the detonation of the mine occurs directly under the middle of the tank, greater damage could be done thereto than if the explosion occuring under the front of the tank.

Data on the pressure signatures of tanks indicate that the tank tread creates ground pressures which form peaks under the road treads and return to a null between the treads, forming a somewhat uniform cyclic pattern of known frequencies and amplitude. These signatures vary and are dependent on the physical characteristics (elasticity and compression) of various types of soil. In other words, each tread develops a very similar individual pressure signature as it passes over a point. Based on this data, the fuze of the invention was designed to function under the most vulnerable part of the tank, i.e., the middle.

The present invention provides a fuze for overcoming this functioning deficiency inherent in present standard anti-tank mine fuze designs, and provides a fuze operating on the principle of a simple rack and pawl arrangement that functions as a mechanical counter to detonate the mine at a predetermined point under the treads of a tank. The fuze is further provided with an adjustment whereby the fuze may be made to detonate at the desired number of pressures, dependent upon the size of the tank to be destroyed.

While the fuze of the invention is designed for incorporation in an anti-tank mine, it is possible to design it for anti-personnel or other automotive type mines, if required.

It is therefore a principal object of this invention to provide an anti-tank mine fuze adapted to function after a specific number of impulses or pressures of a certain magnitude are applied.

It is another object to provide a fuze acting as a mechanical counter to function at a predetermined point under the treads of a tank.

It is a further object of this invention to provide a fuze for an anti-tank mine that is adjustable to function after a number of pressures thereon.

It is a still further object to provide an anti-tank mine fuze that is highly efficient, reliable and of simple construction.

Other objects and advantages will be apparant from the following description, reference being had to the accompanying drawing forming a part of this application and in which like numerals designate like parts in all the views.

In the drawings:

FIG. 1 is a vertical section of a fuze, constructed in accordance with the invention, taken along line 1--1 of FIG. 3,

FIG. 2 is an exploded perspective view of the counting mechanism,

FIG. 3 is a vertical section taken along lines 3-3 of FIG. 1 and,

FIG. 4 is a fragmentary plan view taken in the plane 4-4 of FIG. 1 illustrating the setting indicia.

Referring to the drawing, 1 indicates generally the fuze of the invention which comprises a fuze body indicated generally by 3 and a base, indicated generally by 5 which is threadably united to body 3 by threads 7. Body 3 is axially bored as at 9 for housing operating mechanisms, and defines at its upper portion an annular flange 11 for attachment of the fuze to a mine (not shown). Base 5 is axially bored to provide an annular chamber 13 to contain operating mechanisms, and is internally threaded at its lower portion thereof and is further provided with an upper conical wall. Bores 13 and 15 are connected by a small axial bore 17 and a counter bore 19. The bottom of chamber 15 is milled axially to define a semi-circular well 21. A cylindrical pressure plate, indicated generally by 23, defines an upper portion slidable in bore 9 and a lower annular flanged portion slidable in chamber 13, and is prevented from rotational movement by pin 8 fixed in body 3 and extending into a slot 10 milled in the side wall of pressure plate 23. Which is biased upwardly in bore 9 and chamber 13 by a Belleville spring 27 in chamber 13, the upper portion thereof normally projecting above the upper surface of body 3 to be engaged by a tank tread or like impact. Pressure plate 23 is further bored to provide a mechanism housing 29 and is bored transversely as at 31 and counterbored as at 33 for a purpose to be later described. An O-ring 35 is received in an annular groove 37 in pressure plate 23 providing seal between the pressure plate 23 and body 3. The inner wall of chamber 29 is provided with an annular inwardly extending annular boss which is provided with ratchet teeth 41 on the inner face thereof to form a retaining clutch 39. A shaft 43 having a notched head 45 is received in bore 31 and counter bore 33 respectively. A pressure counting mechanism indicated generally by 34 is mounted on shaft 43 in bore 29 and comprises a clutch member 47, having ratchet teeth on either side thereof and arranged in a unidirectional direction, is mounted to rotate with shaft 43 by a pin 49, and is provided with a radially extending integral pressure bar 51. A driven clutch member 53 is mounted for free rotation on shaft 43 adjacent clutch 47 and is provided with ratchet teeth on its inner face that normally mesh with teeth on one side of clutch 47 and is further provided with gear teeth 55 about its outer peripheral surface that mesh with gear teeth on a stationary upstanding rack 57 rigidly mounted on the bottom surface of chamber 13 and is secured thereon by a screw 59 and dowel pin 61.

In their assembled relation on shaft 43, clutch 47 is mounted between driven clutch 53 and retaining clutch 39 so that the teeth on 53, 47 and 39 are in mesh. These elements are biased into their meshed relation by a clutch spring 63 mounted about shaft 43 in a counter bore of bore 31 in pressure plate 23.

Firing mechanism, indicated generally by 40, for fuze 1 is mounted in the base 5 and comprises a bearing cap 65 bored centrally at its lower end to receive a firing pin 69 in press fitted relation and defines an upwardly extending shaft 71 slidably mounted in bore 17 and is further provided with a beveled end surface 73. Shaft 71 is normally in vertical alignment with pressure bar 51 when it has been rotated whereby

surfaces

73 and 75 mate. A snap-through Belleville spring 77 is mounted in chamber and is held in position by a spring retainer 79 which is threadably engaged to base 5 and serves to hold the firing pin 69 in its retracted position. A detonator holder 81 is threadably engaged to spring retainer 79 and serves to hold a detonating element 83 in axial alignment below firing pin 69.

Setting means for regulating the counting mechanism are provided and comprise the notched head 45 of shaft 43 which is visable through a transverse bore 85 disposed coaxially with bore 31 and is closed at its outer end by a transparent threaded plastic plug 87 which is threadable in bore 85. Suitable setting indicia 89 is inscribed on the outer surface of body 3.

In operation, the fuze is placed in a mine well and the fuze 11 and is secured therein by suitable means (not shown). If it is desired to set the fuze for delayed detonation, i.e., after a certain number of tank treads have passed over the pressure plate 23, the plug 87 is removed and a screw driven is inserted through bore 85 to engage notched head 45 and the shaft 43 is turned to bring the pressure bar 51 into the correct position to actuate the firing mechanism 40. After the setting has been completed, the fuze is ready for use.

As each pressure is applied to the pressure plate 23, the plate 23 will be pressed downward against the Belleville spring 27 carting with it, the counting mechanism 34. Driven clutch 53'will be rotated clockwise by rack 57 which is fixed on the base 5 and the ratchet teeth on clutch 53 will slip past the adjacent ratchet teeth on clutch 47 due to the clutch spring 63, and clutch 47 will not rotate. Upon release of each pressure on plate 23, plate 23 will be moved upward by Belleville spring 27 and the rotation of driven clutch 53 is reversed and pressure bar 51 is rotated in a counterclockwise direction, the ratchet teeth on the side of clutch 47 adjacent the retaining clutch 39 slipping over the teeth 41 thereon. As each successive pressure is applied to the pressure plate 23, this procedure is repeated until the pressure bar 51 is in position whereby the beveled surface 75 on pressure bar 51 is in contact with the beveled surface 73 of shaft 71, then, when the next pressure is applied to plate 23, shaft 71 is pushed down in bore 17 carrying with it firing pin 69, Bellevile spring 77 will then snap through" to cause firing pin 69 to detonate the detonating element 83 and fire the anti-tank mine. (not shown) The fuze may also be set for instantaneous detonation of a mine upon a single downward movement of pressure plate 23, if desired, by moving the pressure bar 51 to a position whereby it engages shaft 71. This will allow the firing pin to fire the detonator upon a single tank tread or like impression upon the pressure plate 23.

It is apparent from the foregoing description that a highly efficient fuze has been devised to delay the mine detonation until the vehicle to be destroyed has reached the position over the mine to effect the most damage thereto. The fuze of the invention is simple of construction and is easily assembled.

It is to be understood that the form of the invention herein shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangements of parts may be resorted to without departing from the spirit of the invention, or scope of the subjoined claims.

What is claimed is:

2. In a fuze for detonating an anti-tank mine, a body, a base secured to said body, a spring-biased pressure plate slidably mounted in said body and said base. a detonator in said base, a pressure actuated counting mechanism for delaying detonation of said detonator comprising a shaft journaled for rotation transversely in said pressure plate, a first retaining clutch including a set of circumferentially arranged ratchet teeth integral with said pressure plate and surrounding said shaft, a second clutch mounted for free rotation about said shaft, said second clutch being provided with a set of ratchet teeth on its inner side and gear teeth about its peripheral surface, a third clutch having a set of ratchet teeth on either side thereof in unidirectional arrangement mounted on said shaft for rotation therewith, a clutch spring housed in said pressure plate and surrounding said shaft normally biasing said second clutch and said third clutch toward said first clutch, a spring held firing pin defining an upwardly extending shaft having a beveled upper end slidably mounted in said base, a pressure bar integral to said third clutch having a beveled end thereon, a toothed rack fixed with said base having its teeth meshing with said gear teeth on said second clutch, said pressure bar and said third clutch adapted to rotate in a counter clockwise direction only upon reciprocal movement of said pressure plate whereby said rack will rotate said second clutch to rotate said third clutch in a counter clockwise direction only, whereby said beveled end on said bar will contact said beveled end of said shaft on said firing pin to snap said pin downward to fire said detonator, and adjusting means for regulating detonating delay comprising a notched head on said counting mechanism shaft for receiving an adjusting tool.

l l= l

Claims

2. In a fuze for detonating an anti-tank mine, a body, a base secured to said body, a spring-biased pressure plate slidably mounted in said body and said base, a detonator in said base, a pressure actuated counting mechanism for delaying detonation of said detonator comprising a shaft journaled for rotation transversely in said pressure plate, a first retaining clutch including a set of circumferentially arranged ratchet teeth integral with said pressure plate and surrounding said shaft, a second clutch mounted for free rotation about said shaft, said second clutch being provided with a set of ratchet teeth on its inner side and gear teeth about its peripheral surface, a third clutch having a set of ratchet teeth on either side thereof in unidirectional arrangement mounted on said shaft for rotation therewith, a clutch spring housed in said pressure plate and surrounding said shaft normally biasing said second clutch and said third clutch toward said first clutch, a spring held firing pin defining an upwardly extending shaft having a beveled upper end slidably mounted in said base, a pressure bar integral to said third clutch having a beveled end thereon, a toothed rack fixed with said base having its teeth meshing with said gear teeth on said second clutch, said pressure bar and said third clutch adapted to rotate in a counter clockwise direction only upon reciprocal movement of said pressure plate whereby said rack will rotate said second clutch to rotate said third clutch in a counter clockwise direction only, whereby said beveled end on said bar will contact said beveled end of said shaft on said firing pin to snap said pin downward to fire said detonator, and adjusting means for regulating detonating delay comprising a notched head on said counting mechanism shaft for receiving an adjusting tool.