US3698315A - Non-metallic mine pressure fuse - Google Patents

Abstract

A non-metallic mine pressure fuse, having a housing comprising upper and lower portions secured together, a leaf spring with its peripheral surface retained between the upper and lower housing portions and its central portion projecting upwardly in the unbiased state, a percussion pin supported for axial displacement relative to the housing and retained at a central aperture provided therefor in the leaf spring so as to penetrate a percussion explosive charge in the lower housing upon flexing of the leaf spring to a downwardly projecting position, a trip member projecting from the upper surface of the housing and arranged for axial displacement relative thereto, and a pressure translating member interposed between the trip member and the leaf spring to cause a downward flexing of the spring upon an external pressure in excess of a predetermined value applied to the trip member, wherein detent means are provided to prevent restoration of the pressure translating member to its initial position prior to the exertion of a pressure of lesser magnitude than the predetermined value.

Description

United States Patent Becker Oct. 17, 1972 Primary Examiner-Samuel W. Engle Attorney-Craig, Antonelli & Hill [72] Inventor: Franz Becker, Bonn, Germany [57] ABSTRACT [73] Asslgnee: g Nobel Akhengeseuschah A non-metallic mine pressure fuse, having a housing rolsdorf, Germany comprising upper and lower portions secured {22] Filed: June 13, 1969 together, a leaf spring with its peripheral surface retained between the upper and lower housing por- [21 1 Appl 833025 tions and its central portion projecting upwardly in the unbiased state, a percussion pin supported for axial [30] Foreign Application Priority Data displacement relative to the housing and retained at a g 1 1968 Germany up 17 71 9356 central aperture provided therefor in the leaf spr ng so as to penetrate a percussion explosive charge In the lower housing upon flexing of the leaf spring to a Zll "mi/823125;: downwardly projecting position, a trip member [58] i 70 79 73 jecting from the upper surface of the housing and ar- 0 ranged for axial displacement relative thereto, and a pressure translating member interposed between the [56] Reerences Cited trip member and the leaf spring to cause a downward UNITED STATES PATENTS flexing of the spring upon an external pressure in excess of a predetermlned value applied to the trip 2,488,547 ll/l949 Llcuegren ..lO2/8 member, wherein detem means are provided to 2,598,157 5/1952 Everett ..l02/79 prevent restoration of the pressure translating member 2,857,842 10/1958 Malm ..i02/8 to its initial position prior to the exertion of a pressure 2,923,237 2/1960 Bletkamp, ll 102/8 f lesser magnitude than the predetermined value. 3,392,47l 7/1968 Foote ..42/l0 X 9 Claims, 1 Drawing Figure i 35 i I 5 41 39 ,1 5 6o ,1 5 t I l4 M A I 8 v l3 h u T3 T M. 9 fir:

'\ fifi''l i 1 i L z Jf g 3'59! PATENTEDUET 17 m2 1 m w M 5 M M LVN w 3 3 INVENTOR FRANZ BECKER W Mr ATTORNEYS NON-METALLIC MINE PRESSURE FUSE BACKGROUND OF THE INVENTION The present invention relates to a non-metallic mine pressure fuse or detonator, having a housing including upper and lower portions secured together, a percussion pin disposed, in an axially-displaceable manner, in the upper portion of the housing with its tip extending, through a leaf spring, with which it is secured for conjoint axial displacement, and a trip member projecting out of the upper portion of the housing and operatively connected with the leaf spring to cause a downward flexing of the spring, and a corresponding depression of the percussion pin into a percussion explosive charge, upon application of an external pressure, in excess of a predetermined value, upon the trip member.

In conventional non-metallic mine pressure fuses or detonators of the type described above, the percussion pin can be actuated by means of an intermediate pressure translating member causing a downward flexing of the leaf spring. This pressure or force translating member is positioned within the upper portion of the housing and adapted for axial displacement therein. At its lowermost portion, the member is adapted to engage the leaf spring by means of beads or other projections disposed so as to cooperate with the leaf spring between the peripheral rim and the center thereof. The beads or other projections are generally provided in an annular manner or in another arrangement wherein the points of contact between the pressure translating member and the leaf spring are spaced equidistant from the center of the spring.

It has been known heretofore to interpose a pressure translating member between a leaf spring and a trip or trigger member, which is guided in the upper portion of the housing by means of a conical shell or casing provided about the periphery of the trip member, which is designed to break upon application of a load or pres sure in excess of a predetermined value. The trip member is preferably secured to the upper portion of the housing in a tightly sealed manner, for example, by welding or the like, along the rim of the conical casing. The shank of the percussion pin is guided within a central bore provided in the trip member.

Generally, the pressure translating member incorporates a toroidal or annular bead which engages the leaf spring during the triggering process until the tip of the percussion pin approximately impinges upon the percussion explosive charge of the detonator cap, the contact between the member and the leaf spring being precisely symmetrical about the central axis thereof. In accordance with this conventional arrangement, a precisely symmetrical bending of the spring is achieved; thus, when the spring flexes, in a snap-like manner, all portions of the spring move simultaneously, with the result that the percussion pin is depressed into the percussion explosive charge in a precisely vertical direction.

The conventional fuses described immediately above have been found to be generally satisfactory when used in conjunction with tank mines having a normal pressure lid. However, for various reasons, such as to prevent accidental detonation of a mine in the presence of extreme pressure waves, as from a nuclear explosion, alternative constructions of tank mines are often employed, wherein a rocker lid is provided in place of the normal pressure lid. In mines of this type, the tilting or rocker lid system incorporates inherent forces of restoration which causes the lid to execute a rocking motion when passed over by a tracked vehicle, under the influence of each wheel rolling thereof. This rocking motion is translated by the central detonator system of the mine into vertical motions in accordance with a predetermined translation ratio.

When employing mines having a rocker lid, the path traversed by the peripheral or rim portion of the rocker lid, in the vertical direction, may be sufficiently large, depending upon the translation ratio, to detonate the mine when the first wheel of a tracked vehicle traverses the lid. However, if the displacement of the rim portion of the rocker lid is of a lesser magnitude than the critical value, the mine may not be detonated, even though the specific pressure forces of a vehicle passing over the lid might normally be sufficient to trigger the mine. In such cases, detonation failures may be traceable to unsuitable surface conditions, to an improperly implanted mine (in a hole without sufficiently beveled edges), or merely to a light-weight construction of tracked vehicles.

Accordingly, it is an object of the present invention to provide a non-metallic mine pressure fuse of the type described above which insures detonation even when incorporated in a tank mine utilizing a tilting or rocker lid.

Further, it is an object of the present invention to provide a fuse of the type described above which is responsive to a series of deflections each of which is of lesser magnitude than a predetermined critical value.

Finally, it is an object of the present invention to provide a fuse of the type described hereinabove which can readily be incorporated within conventional mines and detonating equipment therefore.

SUMMARY OF THE INVENTION The foregoing objects are accomplished, in accordance with the present invention, by providing means within the fuse mechanism to accumulate the effects of a plurality of applied impulses, each of which, alone, would otherwise be insufficient for causing detonation, which means produce detonation when the total of the individual impulses exceeds the critical value. Since normal tracked vehicles include several wheels, each of which exerts a particular impulse upon a mine fuse, the present invention contemplates accumulating the total effects of the relatively small individual impulses to define an effective deflection path representing a total of the individual impulses, eventually causing detonation when the effective path exceeds the predetermined critical value.

This accumulation is accomplished, in accordance with the present invention, by providing a detent arrangement between the trip member and the pressure translating member and a second detent member between the pressure translating member and the upper portion of the housing. This double detent arrangement effectively provides for a locking of the pressure translating member in the position to which it has been depressed by an individual impulse, while permitting the trip member to resume its original position relative to the upper portion of the housing after transferring the effects of a non-critical impulse.

Thus, as the next wheel traverses the mine, the pressure pin is again depressed, the deflection being added to the deflection produced by the first wheel and fully transmitted to the leaf spring. Thereafter, the trip member is again returned to its initial position to transmit still another impulse. In this manner, depending upon the sensitivity of the locking detents provided, a desired number of incremental deflections can be totaled to achieve a final critical deflection path resulting in detonation of the mine.

It should be noted, however, that the novel arrangement contemplated by the present invention does not preclude detonation of the mine in response to the first wheel of the tracked vehicle. Thus, if a mine provided with a fuse as contemplated by the present invention is traversed by a tracked vehicle causing a sufficient deflection to traverse the required number of detents, the deflection can be fully effective to cause detonation upon the impulse of the first wheel.

Preferably, the pressure translating member is provided with an annular recess between inner and outer circumferential walls on which the locking detents are disposed, so that the annular walls can yield elastically in a corresponding manner when the trip member is displaced.

In order to enhance the restoring force of the spring, the trip member can be further supported, at the upper portion of the housing, by means of additional spring arms. Toward this end, the bearing surface for the spring arms provided on the upper portion of the housing, can be of a conical configuration.

DETAILED DESCRIPTION OF THE DRAWING The foregoing objects, features and advantages of the present invention will become more readily apparent from a consideration of the detailed description hereinbelow, when considered in conjunction with the accompanying drawing, which is a schematic sectional view of a non-metallic mine pressure fuse constructed in accordance with one embodiment of the present invention.

The non-metallic mine pressure fuse or detonator constructed in accordance with the present invention includes an upper housing portion 1 and a lower housing portion 2, which are threadedly engaged and sealingly cemented together. Between the upper housing portion 1 and the lower housing portion 2, the peripheral surface of a leaf spring 8, oriented in the direction of the upper housing portion 1, is retained. A percussion pin is retained, by its neck-like constriction 14, by centrally-provided aperture in leaf spring 8. A detonator cap or percussion explosive charge 9 is disposed within a recess of lower housing portion 2. A trip member 4 is attached, by means of conical jacket 27, to which it is glued, to upper housing portion 1. Percussion pin 5 is disposed within a central bore provided in trip member 4.

Between trip member 4 and upper housing portion 1, a pressure or force translating member 6a is disposed. Member 6a is provided, at its lowermost surface, with a toroidal projection 13, which can engage, in a symmetric manner, with the upper surface of leaf spring 8.

6 Pressure translating member 6a IS constructed as a stop member and is provided with an annular recess 35. The annular wall 36 includes detent teeth 37 on the circumferential surface thereof facing the corresponding surface of trip member 4. Detent teeth 37 serve to block movement of trip member 4 in the direction of percussion explosive charge 9. Trip member 4 is provided, on its outer circumferential surface, with teeth 38 having a configuration corresponding to and adapted to engage with detent teeth 37.

The outer annular wall 39 of pressure translating member 6a is provided with ring-shaped teeth 40 on the upper circumferential surface, which teeth serve to prevent displacement of member 6a in a direction opposite to the direction of detonator cap 9. The ringshaped teeth 40 cooperate with correspondinglyshaped teeth 41 provided on the opposing circumferential surface of upper housing portion 1.

Additionally, trip member 4 is provided with arms, or a disk-like member 42, which guides the trip member 4 with respect to upper housing portion 1. The arms 42 engage within a conically-shaped recess 43 of upper housing portion 1.

In the ready position of the mine pressure fuse illustrated, the pressure translating member 6a is in its uppermost position and abuts against an annular projection of the upper housing portion, whereas the trip member 4 is in its lowermost position with respect to the engagement of its annular teeth 38 with detent teeth 37. As individual impulses of a relatively small magnitude are applied to trip member 4, the pressure translating member 6a is, in each instance, displaced downwardly along the locking detents 41 in increments of one or more teeth, depending upon the magnitude of the impulse. Of course, member 6a is effectively blocked from a return upward displacement by the cooperating teeth 40 and 41.

The restoring force of the leaf spring, until the flexing position of the spring has been reached, operates to return trip member 4 upwardly in increments of one or more teeth so that trip member 4 is always returned to its uppermost initial position. Eventually, the addition effect of the individual impulses applied, afforded by the fuse contemplated by the present invention, results in a position being attained wherein a relatively small incremental impulse applied to trip member 4 will serve to cause leaf spring 8 to be flexed downwardly, thus permitting percussion pin 5 to penetrate into detonator cap 9.

It should be noted that the external dimensions of a conventional fuse need not be altered by the particular construction of the pressure translating member 6a contemplated by the present invention. Thus, the mine pressure fuse contemplated by the present invention can be incorporated, as desired, within mines provided with either a conventional pressure lid or rocker lid.

While the present invention has been disclosed with reference to but a single specific embodiment, it is to be clearly understood that the scope of the invention is in no way limited to the specific details thereof, but is susceptible of numerous changes and modifications as would be apparent to one with normal skill in the pertinent technology.

What is claimed is:

l. A non-metallic mine pressure fuse, comprising:

housing means,

leaf spring means retained, at the peripheral surface thereof, by said housing means, the central portion of said leaf spring means projecting upwardly in the initial unbiased position thereof and defining a centrally-disposed aperture therein, percussion pin means supported for axial displacement relative to said housing means, including means for operatively connecting said pin means with said leaf spring means for axial displacement together therewith, detonating cap means disposed within said housing means so as to receive the tip of said pin means upon downward flexing of said leaf spring means,

trip means projecting from the upper surface of said housing means and supported for axial displacement relative thereto a distance corresponding to an applied force, .7

pressure translating means interposed, within said housing means, between said trip means and said leaf spring means, said pressure translating means being displaceable in the axial direction to translate a downward axial displacement of said trip means into a downward axial displacement of unretained portions of said leaf spring means corresponding to the magnitude of the force applied, and

detent on said housing and on said pressure translating means permitting the downward axial displacement of said pressure translating means relative to said housing means and precluding upwardly directed axial displacement of said pressure translating means upon removal of said force so that said leaf spring can be fixed in positions intermediate its initial unbiased condition and the position wherein said detonating cap receives said pin means whereby said fuse can be activated by the cumulation of successive forces each individually insufficient.

2. A mine pressure fuse according to claim 1, wherein said detent means includes cooperating sets of teeth provided on mating surfaces of said housing means and said pressure translating means, permitting downwardly directed axial displacement of said pressure translating means relative to said housing means, but effectively blocking corresponding displacement in an upward direction.

3. A non-metallic mine pressure fuse, comprising:

housing means,

leaf spring means retained, at the peripheral surface thereof, by said housing means, the central portion of said leaf spring means projecting upwardly in the initial unbiased position thereof and defining a centrally-disposed aperture therein,

percussion pin means supported for axial displacement relative to said housing means, including means for operatively connecting said pin means with said leaf spring means for axial displacement together therewith,

detonating cap means disposed within said housing means so as to receive the tip of said pin means upon downward flexing of said leaf spring means, trip means projecting from the upper surface of said housing means and supported'for axial displacement relative thereto a distance corresponding to an applied force,

pressure translating means interposed, within said housing means, between said trip means and said leaf spring means, said pressure ranslating means tive to saidhousing means and precludingupwardly directed axial displacement of said pressure translating means upon removal of said force so that said leaf spring can be fixed in positions intermediate its initial unbiased condition and the position wherein said detonating cap receives said pin means whereby said fuse can be activated by the cumulation of successive forces each individually insufficient, said detent means including cooperating sets of teeth provided on mating surfaces of said housing means and said pressure translating means and further including cooperating sets of teeth provided on mating surfaces of said trip means and said pressure translating means permitting upwardly directed axial displacement of said trip means relative to said pressure translating means but effectively blocking corresponding relative displacement in a downward direction.

4. A mine pressure fuse according to claim 3, wherein said housing means includes an upper housing portion and a lower housing portion threadedly and sealing engaged therewith, said peripheral surface of said leaf spring means being retained between said upper housing portion and said lower housing portion.

5. A mine pressure fuse according to claim 4, wherein said means operatively connecting said pin means with said leaf spring means includes a constricted portion of said pin means disposed within said aperture of said leaf spring means.

6. A mine pressure fuse according to claim 3, wherein said pressure translating means includes two annularly extending wall members defining an annular recess therebetween.

7. A mine pressure fuse according to claim 3, wherein said trip means is connected with said housing means by a conical jacket means, said trip means being glued to said conical jacket means.

8. A mine pressure fuse according to claim 7, further comprising disk-shaped bearing means of conical configuration, guiding said trip means for axial displacement relative to said housing means.

9. A mine pressure fuse according to claim 7, further comprising radially oriented bearing arm means guiding said trip means for axial displacement relative to said housing means.

Claims (9)

1. A non-metallic mine pressure fuse, comprising: housing means, leaf spring means retained, at the peripheral surface thereof, by said housing means, the central portion of said leaf spring means projecting upwardly in the initial unbiased position thereof and defining a centrally-disposed aperture therein, percussion pin means supported for axial displacement relative to said housing means, including means for operatively connecting said pin means with said leaf spring means for axial displacement together therewith, detonating cap means disposed within said housing means so as to receive the tip of said pin means upon downward flexing of said leaf spring means, trip means projecting from the upper surface of said housing means and supported for axial displacement relative thereto a distance corresponding to an applied force, pressure translating means interposed, within said housing means, between said trip means and said leaf spring means, said pressure translating means being displaceable in the axial direction to translate a downward axial displacement of said trip means into a downward axial displacement of unretained portions of said leaf spring means corresponding to the magnitude of the force applied, and detent on said housing and on said pressure translating means permitting the downward axial displacement of said pressure translating means relative to said housing means and precluding upwardly-directed axial displacement of said pressure translating means upon removal of said force so that said leaf spring can be fixed in positions intermediate its initial unbiased condition and the position wherein said detonating cap receives said pin means whereby said fuse can be activated by the cumulation of successive forces each individually insufficient.

2. A mine pressure fuse according to claim 1, wherein said detent means includes cooperating sets of teeth provided on mating surfaces of said housing means and said pressure translating means, permitting downwardly directed axial displacement of said pressure translating means relative to said housing means, but effectively blocking corresponding displacement in an upward direction.

3. A non-metallic mine pressure fuse, comprising: housing means, leaf spring means retained, at the peripheral surface thereof, by said housing means, the central portion of said leaf spring means projecting upwardly in the initial unbiased position thereof and defining a centrally-disposed aperture therein, percussion pin means supported for axial displacement relative to said housing means, including means for operatively connecting said pin means with said leaf spring means for axial displacement together therewith, detonating cap means disposed within said housing means so as to receive the tip of said pin means upon downward flexing of said leaf spring means, trip means projecting from the upper surface of said housing means and supported for axial displacement relative thereto a distance corresponding to an applied force, pressure translating means interposed, within said housing means, between said trip means and said leaf spring means, said pressure translating means being displaceable in the axial direction to translate a downward axial displacement of said trip means into a downward axial displacement of unretained portions of said leaf spring means corresponding to the magnitude of the force applied, and detent means permitting the downward axial displacement of said pressure translating means relative to said housing means and precluding upwardly-directed axial displacement of said pressure translating means upon removal of said force so that said leaf spring can be fixed in positions intermediate its initial unbiased condition and the position wherein said detonating cap receives said pin means whereby said fuse can be activated by the cumulation of successive forces each individually insufficient, said detent means including cooperating sets of teeth provided on mating surfaces of said housing means and said pressure translating means and further including cooperating sets of teeth provided on mating surfaces of said trip means and said pressure translating means permitting upwardly-directed axial displacement of said trip means relative to said pressure translating means but effectively blocking corresponding relative displacement in a downward direction.

4. A mine pressure fuse according to claim 3, wherein said housing means includes an upper housing portion and a lower housing portion threadedly and sealing engaged therewith, said peripheral surface of said leaf spring means being retained between said upper housing portion and said lower housing portion.

5. A mine pressure fuse according to claim 4, wherein said means operatively connecting said pin means with said leaf spring means includes a constricted portion of said pin means disposed within said aperture of said leaf spring means.

6. A mine pressure fuse according to claim 3, wherein said pressure translating means includes two annularly extending wall members defining an annular recess therebetween.

7. A mine pressure fuse according to claim 3, wherein said trip means is connected with said housing means by a conical jacket means, said trip means being glued to said conical jacket means.

8. A mine pressure fuse according to claim 7, furtHer comprising disk-shaped bearing means of conical configuration, guiding said trip means for axial displacement relative to said housing means.

9. A mine pressure fuse according to claim 7, further comprising radially-oriented bearing arm means guiding said trip means for axial displacement relative to said housing means.

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