US3000302A - Mine protective device - Google Patents

Description

Sept. 19, 1961 L, R, |TTLET0N 3,000,302

MINE PROTECTIVE DEVICE Filed March 22, 1960 1N V EN TOR.

Leunida's RLiHlEn'n United States Patent() 3,000,302 MINE PROTECTIVE DEVICE Leonidas R. Littleton, Emory, Va., assignor to the United States of America as represented by the Secretary of the Army Filed Mar. 22, 1960, Ser. No. 16,897 1 Claim. (Cl. 102--8) (Granted under Title 35, U.S. Code (1952), sec. 266) 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 there- The present invention relates to mine protective devices and more particularly to a mine fuze which will not be detonated by a suddenly applied force, but which will be detonated upon the application of gradually applied pressure.

Land mines have become an integral part of defensive land warfare, materially hindering the advance of enemy infantry or vehicles and affording protection for retreating forces. Mine fields must be cleared before the attacking force can advance.

Various methods have been devised to clear an area of mines. One method is to spread over the area explosives in various forms and then detonate them to actuate the mine `fuzes. Another method is to drop shells or bombs into the mined area. Yet another method which has been partially successful is to push a rotating fiail over the field which beats the ground in front of the machine and detonates the mines.

It will be seen that in each of the above noted clearing methods, detonation of the mine is caused by a sudden impact of short duration. Thus, it will be seen that if the mine is provided with a fuze which responds to a gradually applied pressure such as would be caused by vehicles or troops, but not to a sudden impact of short duration, a Very effective mine which Would be difficult to clear would be obtained.

My invention comprises a device which is placed over the land mine containing a plunger or trigger which upon being depressed will strike the fuze mechanism and activate it. The plunger or trigger is restrained by uid pressure such that it will not be depressed by a sudden impulse, but will be depressed by a gradually applied pressure.

It is an object of this invention to provide a mine having a fuze which will be sensitive to gradually applied pressure, but insensitive to a suddenly applied impulse.

Another object is to provide a mine having a fuze actuating pressure plate, the movement of the pressure plate being resisted by fluid pressure.

These and other objects will become more apparent when reference is had to the following detailed description and drawing in which:

The iigure is an axial sectional view of the mine protective device and mine with the mine being shown fragmentarily.

Referring now to the drawing there is shown the upper portion of a land mine 1 which is provided with fuze 2 by which the mine is detonated. The upper surface of the mine is provided with an annular iiange 3 for receiving the mine protective device to be described.

The mine protective device is generally indicated at 4 and comprises a body having the outer cylindrical wall 5 received in the flange 3r on the mine. The body is further provided with inner annular Wall 6 and intermediate annular wall 7. The end wall 8 connects all three walls 5, 6 and 7 and end Wall 9 connects walls 5 and 7. Thus, there is formed an annular outer chamber 10 and an annular inner chamber 11. The chamber 10 may be vented near the top if desired as shown at 20` Mice Apertures 12 are provided in the Wall 7 to provide restrlcted communication between the chambers 10 and 11. The inner wall 6 defines a central passage 13 through 4the body and the lower end of this passage is provided with a guide sleeve 14. A quantity of hydraulic iiuid is supplied to the two chambers 10 and 11 as indicated on the drawing. An annular iioating piston 15 is provided and is of such size as to slidably contact the Walls 6 and 7. This piston rests on the top of the liquid in chamber 11. Seals may be provided between the piston 1S and walls 6 and 7 if desired. Connected to or resting on the top of piston 15 is the cup shaped pressure plate 16 having flange'17 which ltelescopes with the outside of wall 5. An actuating pin 18 is connected to pressure plate 16 and is slidably received in sleeve 14. Spring 19 surrounds the pin 18 and reacts between the sleeve 14 and pressure plate 16 to urge the plate upward. It will be seen that this spring could be omitted if desired if the chamber 10 1s not vented, as the air in the chamber 10 would then form an air spring.

Operation It will be seen that the parts will have an equilibrium position as shown in the drawing with the spring 19 counterbalancing the weight of the piston 15 and pressure plate 16 with the actuating pin spaced from the fuze 2.

If a sudden shock or impulse of short duration occasioned by one of the previously noted mine clearing methods is applied to the pressure plate the mine will not detonate. Such a force would be transmitted through the piston 15 to the incompressible hydraulic liuid. In View of the restricted size and small number of orifices 12, iiuid transfer from chamber 11 to chamber 10 wil-l be slow and the force from the shock or impulse ceases before sufficient fluid ow has occurred to permit the actuating pin 18 to operate the fuze 2. After the impulse the spring 19 returns the pressure plate to normal positlon.

If now the pressure plate is actuated by personnel or equipment coming in contact therewith, a force is applied thereto which is relatively of much longer duration. Under these circumstances the pressure is applied yfor a sufiicient length of time for enough iiuid to pass from chamber 11 to chamber 10 to permit the actuating pin 1S to contact and operate fuze 2. The sensitivity can be varied by changing the total area of the orifices 12 and varying the strength of spring 19.

It is to be noted that the shape of the annular cylinders and pressure plate need not be circular, but may be square, oval or any other shape dictated by the particular application. The term annular as used `in the specification and claim is intended to cover these various shapes.

The hydraulic iiuid used may be any fluid having a low coefficient of viscosity such as the silicone oils.

It will be apparent that the embodiment shown is only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claim.

I claim:

In combination with a mine having a fuze, a mine protective device comprisinga cylindrical housing having an inner Wall, an intermedia-te annular Wall, an outer wall and an end wall, said end wall connecting said inner, intermediate and outer walls whereby an inner chamber and an outer chamber are formed for receiving a hydraulic fiuid therein, said intermediate .Wall being apertured to provide restricted communication between said inner and said outer chambers, there being a central passage provided through said housing by said inner wall, a guide sleeve secured in the lower end of said central 3,000,802 3 4 passage, an annular oatng piston slidabiy contacting to urge said pressure plate and said annular plate upsaid inner and said intermediate Walls, a pressure plate Wardly. having an annular fiange in telescoping contact with the aforesaid outer wall, said pressure plate being secured References Cited ill the file 0f this Patent to the upper side of said piston, an actuating pin con- 5 UNTTED STATES PATENTS nected at one end to said pressure plate, its other end 1702133 Remondy Feb 12 1929 being slidably received in said guide sleeve and a spring surrounding said actuating pin, said spring normally re- FOREIGN PATENTS acting between said guide sleeve and said pressure plate 796,981 Great Britain June 25, 1958

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