US2712575A - Squib switch - Google Patents

Description

July 5, 1955 K, KlEL 2,712,575

SQUIB SWITCH Filed Feb. 27, 1948 J??- F [V24 24? I8 I6 JNVENTOR. F; KENNETH M. KIEL BY X 9. 6/3;

ATTORNEY United States Patent Office Patented July 5, 1955 SQUIB SWITCH Ann Arbor, Mich., assignor to the America as represented by the Secre- Kenneth M. Kiel, United States of tary of the Navy The present invention relates to an improved squiboperated switch which is particularly adapted for use with projectile fuzes.

In an anti-aircraft shell equipped with a fuze, operated by a reflected wave, hereinafter referred to an a proximity fuze, it has until the shell approaches the altitude at which it is to operate, in order to protect any friendly aircraft, which may be near its path during the course of its flight at lower altitudes. This requires that the circuit from the battery, Which is energized when the shell is fired, to the electronic components of the fuze shall remain open for a predetermined time and then be closed. Accordingly, one of the principal objects of the present invention is to provide a simple switch which can be actuated by an associated timing device to close a proximity fuze at a desired time, and which will be of light weight and small size to be readily installed in the fuze.

Another similar use for the present invention is as a safety switch in any type of projectile employing an electric circuit. Said safety switch may be closed either at the instant of launching the projectile or at a definite time thereafter.

In the drawings:

Figure l is an axial section of the switch, greatly enlarged and showing it in open, or circuit breaking, condition.

Figure 2 is a transverse sectional view on the line 2-2 in Figure 1.

Figure 3 is an axial sectional view, on a reduced scale, of my improved switch in circuit closing condition.

Referring to the drawings, my entire switch is enclosed in a cylindrical case 10. The fixed portion of the switch is supported by a cylindrical block 12 of insulating material held in position in the crimped rim 14 and by crimping over the adjacent end of said case, as shown at 16. Spaced conductors 18 are molded into the block 12 and have inner end portions bent radially inwardly to form opposed spaced spring contacts 20 projecting over a conical depression 22 in the inner face of the block, while the outer end portions 24 project beyond the outer end wall of the block 12 to form terminals for external circuit connections.

The movable portion of the switch includes a conducting ring 26 mounted on and at the base of an axially located stud 28 formed on a plunger 30 axially movable in the case 10. Said stud passes between the spring contacts 20 and is guided by an axial cylindrical bore 32 which communicates with the conical depression 22 in the fixed block 12. The outer end of the conducting ring 26 is provided with a substantially frusto-conical flange 34 which can be moved past the spring contacts 20 in one direction but which is held by them to prevent motion in the reverse direction. The plunger is normally positioned to hold the ring 26 away from the contacts 20 by the inter-engagement of a flange 36 on the plunger been found desirable to keep the fuze inert the battery circuit of case 10 by an annular inwardly with an annular inwardly crimped rim 38 formed in the case in spaced relation to the rim 14.

An explosive charge 40 is confined in a cup 41 defined by a liner 42 and a block 44, both of insulating material. The block 44 closes the lower end of the case 10 (as seen in Figure 1) and is held in place by crimping over the end margin of said case, as shown at 48. Said block is reduced in diameter near its upper end to define an annular recess to receive the lower end of the liner. A filament 50 for exploding the charge 40 is embedded in said charge and is supported by leads 52 which are embedded in the block 44. Said leads, like the leads 24, are extended beyond the case to define terminals.

In use, the electrical circuit to be controlled is connected to the switch leads 24, and the control circuit is connected to the filament leads 52. The control circuit is energized at the time when operation of the switch is desired. If such operation is to start as the projectile is launched, the control circuit may be connected to the firing circuit; while, if operation is to start at a later time, the control circuit will include a voltage source and a suitable time switch to complete the circuit. In either case, energizing of the control circuit causes the filament 50 to heat and explode the charge 40. The charge is sufiiciently powerful to force the flange 36 of the plunger 30 past the annular crimp 38 and toward the bolck 12, driving the conical flange 34 of the ring 26 on the stud 28 past the contacts 20 to permit the ring to complete the controlled circuit between them. The charge 40, however, is not powerful enough to break the case 10 and damage any surrounding equipment.

The invention is defined solely in and by the following claims.

I claim:

1. An electrical switch for a projectile fuze, said switch having a cylindrical case, a pair of opposed resilient contact members supported in one end thereof and terminating at an angle to the axis of the case, an axially shiftable plunger in the case, a central cylindrical stud on said plunger passing between the resilient contact members, a ring-shaped contact member on said stud and inteiposable between said resilient contact members said ring-shaped contact member having a frusto-conical flange formed on one edge thereof, means on said case for normally resisting any tendency of the plunger to move axially to bring the ring-shaped contact member into engagement with the resilient contact members, and explosive means carried in said case for propelling said plunger axially in the case to overcome the resistance of said first mentioned means to cause the terminations of the resilient contact members to slide over and snap behind the said flange and to lock the ring-shaped contact member in engagement with the resilient contact members.

2. An electrical switch for the fuze of a projectile, said switch having a cylindrical case, a pair of opposed resilient contact members supported in one end thereof, an axially shiftable plunger in the case, a central cylindrical stud on said plunger passing between the fixed contact members, a ring-shaped contact member on said stud and interposable between said fixed contact members, said case having a bead internally thereof for normally resisting any tendency of the plunger to move axially to bring the ring-shaped contact member into engagement with the fixed contact members, electrically fired explosive means for propelling said plunger axially in the case to overcome the resistance of said bead and bring the ring-shaped contact member into engagement with the fixed contact members, and a flange on said ring-shaped contact member engaged by the resilient contact members for preventing motion of the plunger in the reverse direction.

3. A fuze switch for use with an explosive projectile,

comprising a sheet-metal case of generally cylindrical configuration having two spaced beads formed inwardly in the central portion thereof, a block of insulating material in one end of the casing and held in place by one of said beads, said block having a recess formed in the inner transverse surface thereof, said recess comprising a large conical walled portion which merges interiorly into a relatively narrow cylindrical bore, a block of explosive material situated in the other end of the casing and having an ignition filament embedded therein, a plunger of insulating material having a generally disk-like shape situated between said blocks and having an annular shoulder which normally resides adjacent the other of said beads on the side thereof away from the first-mentioned bead, said plunger having a stud extending axially therefrom and of such size and shape as to slide freely in the bore portion of said recess, two conductors embedded in said block of insulating material and having resilient free ends which extend into said recess, the free ends extending radially into said recess from opposite directions and terminating at an angle to the axis of the container and directed toward said bore, and a ring of conductive material fixed around said stud at the portion thereof adjacent the plunger, the edge of said ring which is away from said plunger having a frusto-conical flange having its surface formed to mate with the terminations of the free ends of the conductors, whereupon ignition of said explosive by said filament throws said plunger toward said conductors to force said ring between them.

4. In a switch of the type having a casing, a plunger slidable in said casing, contact members fixed relative to said casing, and an explosive member for propelling said plunger into position against said contact members, a bead formed in said casing adjacent said explosive memher, a shoulder on said plunger located adjacent said bead whereby said plunger is normally maintained away from said contact members, said contact members terminating in opposed portions directed at an angle to the direction of motion of the plunger and in a direction away from said plunger, said plunger being provided with a ring of conducting material having a frusto-conical flange formed on the edge thereof which is directed toward the contact members, the large portion of the frusto-conical flange being directed away from the contact members so that movement of the flange past the contact members due to movement of the plunger permits the contact members to snap behind the flange into contact with the ring and to prevent the plunger from returning to its initial position.

References Cited in the file of this patent UNETED STATES PATENTS 535,069 McElroy et al Mar. 5, 1895 769,824 Hopkinson Sept. 13, 1904 1,116,458 Matos Nov. 10, 1914 1,159,602 Scheuer Nov. 9, 1915 1,630,359 Scott May 31, 1927 2,235,917 Campbell Mar. 25, 1941 2,330,690 Dannerberg Sept. 28, 1943 2,559,024 McFarlin July 3, 1951

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