US3238321A - Explosive actuated switch in whitch contact pierces nonconductor - Google Patents

Description

March 1, 1966 R. c. LAWWILL ETAL EXPLOSIVE A H 3,238,321 CTUATED SWITC IN WHICH CONTACT PIERCES NON-CONDUCTOR 2 Sheets-Sheet 1 Filed May 15, 1964 IN VEN TORS A iTOR/VE Y March 1, 1966 R. c. LAWWILL ETAL 3,233,321 EXPLOSIVE ACTUATED SWITCH IN WHICH CONTACT PIERCES NON-CONDUCTOR Filed May 13, 1964 2 Sheets-Sheet 2 32 Q l/ N 2 jbs \4 u 5 F g. 5

RON/4L0 c. LAWW/LL Fl 4 HAROLD L. ANDERSON INVENTORS ATTORNEY United States Patent 3 238,321 EXPLOSIVE ACTUATIiD SWITCH IN WHICH CON- TACT PIERCES NONCONDUCTOR Ronald C. Lawwill and Harold L. Anderson, Albuquerque, N. Mex., assignors, by mesne assignments, to the United States of America as represented by the United States Atomic Energy Commission Filed May 13, 1964, Ser. No. 367,263 7 Claims. (Ci. ZOO-61.08)

The present invention relates generally to electric switches and more particularly to a fast acting switch for transferring electrical energy with high eificiency.

The invention aims to provide improved switches or circuit cont-rolling means of fast action, relatively simple construction and operation, small size, high reliability and high efiiciency.

An object of the present invention is to provide new and improved electrical switch means.

Another object of the invention is to provide a switch for transferring electrical energy with maximum efficiency.

Another object of the invention is to provide an improved fast action switch of high reliability and relatively simple construction and operation.

A further object of the invention is to provide improved switch means that may be readily manufactured by employing injection molding techniques to form synthetic resin molding material about conducting elements.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration and description. The preferred embodiment illustrated is not intended to be exhaustive nor to limit the invention to the precise form disclosed. It is chosen and described in order to best explain the principles of the invention and their application in practical use to thereby enable others skilled in the art to best utilize the invention in various embodiments and modifications as are best adapted to the particular use contemplated.

In the accompanying drawings:

FIG. 1 is a sectional view through one form of the present switch means;

FIG. 2 is a top plan view of the device shown in FIG. 1;

FIG. 3 is a horizontal sectional view taken generally along line 33 of the device of FIG. 1;

FIG. 4 is an enlarged fragmentary sectional View of one form of explosive actuator and plunger construction; and

FIG. 5 is an enlarged fragmentary sectional view showing a portion of the switch subsequent to actuation.

Described generally the present switch may comprise a first terminal or anvil 1 spaced from terminal means 2 and separatedtherefrom by solid insulating material 4, with the terminal means 2 carrying tubular portions 5 each of which houses a movable plunger 6. An explosive actuator 7 serves to drive the plunger 6 along the tubular portion 5 and through the insulating material 4 at an appropriate instant, so as to bridge the space between terminal means 2 and first terminal 1 and establish electrical continuity between the first terminal and the terminal means.

In more detail, the switch is shown to comprise a first terminal or anvil ll of appreciable mass electrically isolated by a barrier of molded plastic material 4 and a layer of insulating material 8 from a terminal means 2. The first terminal and terminal means may each be of some durable and good electrically conducting material, such as brass or the like. In the illustrated embodiment one or more conductors (not shown) may be coupled in any suitable manner with the first terminal 1, e.g., by the illustrated threaded connection 10, and one or more other conductors (not shown) may be coupled with the exposed flange 2a of the terminal means 2 e.g., by wires inserted into the apertures 11 and thereafter soldered into position. In un-actuated condition, no electrical path exists between the first terminal 1 and the terminal means 2, which are electrically isolated from each other by the molded material 4 and insulating layer 8. At a desired instant electrical interconnection may be established between the first terminal 1 and the terminal means 2 by one or more of the connecting plungers 6, which move from the positions illustrated in FIGS. 1 through 4 to interconnecting or actuated positions such as shown in FIG. 5, in response to impelling force provided by the explosive actuators 7.

Terminal means 2 is shown provided with four pockets lined with the molded material 4 and having apertures 13 therethrough, into each of which is press-fitted a plungerguiding tubular member or bushing 5 so that a shoulder 14 abuts an adjacent surface of the terminal means 2. It Will be noted that the shoulder 14 is formed with what may be termed a reverse slope or angle, for a purpose which will be hereinafter described. Into each of the tubular members 5, preferably of brass or the like, is press-fitted a movable steel plunger 6, the plunger being of relatively small mass to facilitate movement under the influence of pressure or shock wave supplied by the actuator 7. Under normal or un-actuated conditions the base or rear surface of the plunger is substantially flush with the base surface of the tubular member 5, as illustrated more particularly in FIG. 4.

Any satisfactory degree of firm press fit may be employed between the exterior of the tubular member 5 and the aperture walls 13 into which it is fitted, and between the plunger 6 and the tubular bore of the member 5 into which it is fitted. An appreciation of the small size and mass of the plunger may be obtained when it is realized that in actual usage, its base or cylindrical portion may have a diameter of about .06 inch, overall length of around .14 inch, with a tapering forward portion of around 30. The front end of the plunger is preferably not sharply pointed but somewhat blunted as generally indicated, to thereby minimize objectionable breaking off of the plunger tip. The reverse angle on the shoulder of the tubular portion 5 may be in the neighborhood of about 15.

Movement of plungers 6 to interconnecting positions, such as in FIG. 5, may be achieved by explosive actuators 7, shown resting against and substantially flush with the tubular members 5 and the plungers 6 and electrically isolated therefrom by insulator cups 15 of suitable plastic insulating material, e.g., a thin (about .005 inch) film of polyethylene terephthalate (Mylar). The insulator cups need not be adhesively secured to the explosive actuators but may be merely fitted thereover as indicated. Each actuator may comprise (FIG. 4) a flanged steel shell 19 containing a quantity of quick-acting explosive material 24 such as a mixture of lead azide and lead styphnate, and housing an electrical contact assembly of Kovar tube 20, Kovar terminal pin 21 separated from the tube 20 by insulating glass 22, and bridging wire 23 interconnecting the terminal pin 21 and tube 20. The flanges of the tube 20 and shell 19 may be joined together by any suitable solder or conducting bonding material, and the joined flanges electrically connected by solder 25 with individual brass terminal members 26, from the latter of which project conducting terminal pins 27 of steel, brass, or the like.

Each explosive actuator and its terminal pin 21 is electrically isolated from the others and each may, if desired, be hooked-up in such manner (not shown) as to respond to a different external event or selection. Also, if desired, two or more actuators may be coupled together in parallel arrangement to an external hook-up so as to simultaneously fire the actuators in response to an external event or selection. Actuation of two or more actuators coupled in parallel affords increased reliability by insuring that at least one of the paralleled actuators ilfiresl As will be clear more particularly from FIGS. 1, 2 and 5, firing of an explosive actuator may be achieved by current passing, for example, through terminal pin 21, across bridge wire 23, through shell 19 and tube 20, across brass terminal member 26, and thence through a conducting terminal pin 27 which may be secured to the terminal member in any suitable manner such as soldering, pressed-fit, etc. When current reaches a bridge wire 23 the explosive material 24 is initiated to exert force against the flush ends of both a plunger 6 and tubular portion 5. As a result a plunger moves with great rapidity to penetrate the isolating synthetic resin material 4 and insulating layer 8 and penetrate partially into the first terminal or anvil 1. The actuated plunger 6 spans the distance between the previously isolated terminals so as to now electrically interconnect them.

As a plunger moves through a tubular portion 5, force exerted on the base end of the tubular portion tends to swing or fulcrum the upper part of the tubular portion inwardly about the contacting rim of the shoulder 14 so as to decrease the cross sectional dimension of the bore behind the moving plunger 6, thus tending to minimize or prevent objectionable rebounding or bouncing of the plunger back up the bore subsequent to striking the first terminal or anvil 1.

The relatively thin (about .005 inch) layer or film of insulating synthetic resin material 8 over the terminal 1, which film may be polyethylene terephthalate and preferably secured in position by some suitable adhesive, provides a very desirable feature. In some instances the electrically isolating and encapsulating material 4 between the first terminal 1 and terminal means 2 tends to crack or break apart, thus creating objectionable arcing paths between the two terminals. It has been found that the noted thin film or layer 8 over the first terminal 1 prevents such cracks from penetrating entirely through to the terminal 1 and hence if any cracks or breaks occur such do not go through the film or layer 8 and the latter continues to provide effective electrical insulation except at the location of penetration by a plunger 6.

In manufacturing the switches, the first terminal or anvil 1 (with insulating layer 8 adhered thereto), the terminal means 2, and the terminal members 26 may be positioned and retained in any suitable mold and suitable synthetic resin molding material injected under pressure into the mold to firmly embed and encapsulate the noted elements or members therein. Diallyl phthalate has been found very satisfactory for the molding material. The upper recess 31 (FIG. 1) and recesses 32 for receiving the tubular members 5 and explosive actuators 7 may be formed in connection with the injection molding operation or, for example, only the upper recess 31 may be so formed and the other recesses 32 formed by subsequent drilling operations. For insuring good electrical contact care should be exercised to see that metal to metal contact is obtained between each of the tubular members 5 and adjacent portions of the terminal means 2.

It will be noted (FIGS. 1 and 2) that the insulating and encapsulating material 4 is shown provided with recesses or cut-outs 28 at about intervals around the periphery of the switch, a recess being disposed intermediate each of adjacent terminal members 26. This feature further contributes toward optimum operation and reliability in that if a particular explosive actuator were, during firing, to exert objectionable or excessive lateral force tending to tear the switch apart, such objectionable force tends to be relieved or vented so that the quadrant with such actuator merely tends to separate itself from the remainder of the switch, without interfering with the remainder of the switch. For example, if one actuator of a pair of diametrically opposite actuators coupled in parallel for reliability in firing were to exert objectionable lateral or sidewise force, the quadrant with the objectionable actuator would separate itself from the switch but leave the diametrically opposite quadrant with its actuator free to operate its plunger and effectively close a circuit.

It will be seen that the present invention provides new and improved fast acting switch means of relatively simple and compact construction which is well adapted to hold off a wide range of voltages but to rapidly close when desired and transfer electrical energy with maximum efficiency. The compactness of the switch may be appreciated when it is realized that its overall dimensions may be only about one inch in length and diameter.

As various changes may be made in the form, construction and arrangement of parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.

We claim:

1. In an explosive actuated switch in which a contact pierces a nonconductor, the combination of a first electrically conducting terminal, electrically conducting terminal means spaced from said first terminal, a recess in said terminal means, a radially inwardly deformable tubular portion in said recess having an opening therethrough in alignment with said first terminal, an electrically conducting movable plunger carried by said tubular portion within said opening adapted to electrically interconnect said first terminal and said terminal means when the switch is actuated, solid insulating material normally filling the space between said first terminal and said terminal means, and plunger actuating means disposed in said recess axially with and in a contiguously abutting relationship and substantially overlying the tubular portion and the plunger.

2. The device of claim 1 in which the tubular portion is radially spaced from the recess and is supported on the terminal means by a contacting rim adjacent the wall of the recess.

3. The device of claim 2 in which the tubular portion deforms radially inwardly about the contacting rim so as to decrease the cross sectional dimension of the opening behind the plunger upon actuation of the switch.

4. The device of claim 1 in which a layer of insulating material closely overlies said first terminal at a surface thereof disposed toward said plunger.

5. The device of claim 1 in which the plunger has a tapering portion disposed toward said first terminal and the extremity thereof is of blunted configuration.

6. The device of claim 1 in which a layer of insulating material is disposed intermediate the plunger actuating means and the terminal means.

5 6 7. The device of claim 1 in which the solid insulating FOREIGN PATENTS material is provided with a plurality of recesses in spaced 921 463 1/1947 France relationship at the periphery of said switch adapted to 1291058 3/1962 France relieve objectionable lateral forces during actuation of Said Switch 5 BERNARD A. GILHEANY, Primary Examiner.

R f ren it by the Examiner I T. MAcBLAIN Assistant Examiner.

UNITED STATES PATENTS 2,816,196 12/1957 Daudelin 200 142 3,155,876 11/1964 Paul 200-61.08 1O

Claims (1)

1. IN AN EXPLOSIVE ACTUATED SWITCH IN WHICH A CONTACT PIERCES A NONCONDUCTOR, THE COMBINATION OF A FIRST ELECTRICALLY CONDUCTING TERMINAL, ELECTRICALLY CONDUCTING TERMINAL MEANS SPACED FROM SAID FIRST TERMINAL, A RECESS IN SAID TERMINAL MEANS, A RADIALLY INWARDLY DEFORMABLE TUBULAR PORTION IN SAID RECESS HAVING AN OPENING THERETHROUGH IN ALIGNMENT WITH SAID FIRST TERMINAL, AN ELECTRICALLY CONDUCTING MOVABLE PLUNGER CARRIED BY SAID TUBULAR PORTION WITHIN SAID OPENING ADAPTED TO ELECTRICALLY INTERCONNECT SAID FIRST TERMINAL AND SAID TERMINAL MEANS WHEN THE SWITCH IS ACTUATED, SOLID INSULTAING MATERIAL NORMALLY FILLING THE SPACE BETWEEN SAID FIRST TERMINAL AND SAID TERMINAL MEANS, AND PLUNGER ACTUATING MEANS DISPOSED IN SAID RECESS AXIALLY WITH AND IN A CONTIGUOUSLY ABUTTING RELATIONSHIP AND SUBSTANTIALLY OVERLYING THE TUBULAR PORTION AND THE PLUNGER.

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