US3453406A - Impact arming and tamper switch - Google Patents

Description

July 1, 1969 K. E. POPE 3,453,406

IMPACT ARMING AND TAMPER SWITCH Filed Sept. 8, 1967 Sheet of 2 III 7 3 INVENTOR j KENNETH E. POPE ATTORNEYS K. E. POPE July 1, 1969 IMPACT ARMING AND TAMPER SWITCH Sheet Filed Sept. 8, 1967 INVENTOR. KENNETH. POPE ATTORNEYS United States Patent 3,453,406 IMPACT ARMING AND TAMPER SWITCH Kenneth E. Pope, Litchfield Park, Ariz., assignor to UMC Industries, Inc., a corporation of Missouri Filed Sept. 8, 1967, Ser. No. 666,430 Int. Cl. H01h 35/02 U.S. Cl. ZOO-61.45 Claims ABSTRACT OF THE DISCLOSURE The present invention pertains to impact switches, and, more specifically, to an impact switch responsive to a predetermined impact giving rise to a specific fluid pressure to rupture an enclosure. A variety of impact switches have been provided by the prior art utilizing various acceleration responsive elements. A suitable acceleration responsive switch is described in my co-pending application, Ser. No. 648,914, filed June 26, 1967, and assigned to the assignee of the present invention. In that application, the utilization of the increase in fluid pressure in response to acceleration in an enclosure is described. The present invention utilizes the increased fluid pressure resulting from an impact to an enclosure containing the fluid to rupture the container. Prior art impact switches do not provide means for delaying the closure or opening of an electrical circuit immediately after sensing the impact; the prior art impact responsive devices immediately result in actuation of the contacts therein in response to the detonation of the required acceleration force. For example, in such applications as aerially implanted antipersonnel devices, it is necessary to arm tamper and disturb switches after the device has struck the ground. However, a delay is necessary after the device decelerates upon striking the ground and before arming the tamper and disturb switches to permit vibrations and other disturbances to dampen. Prior art impact switches, when placed in such an environment are incapable of accurately effecting a switch closure after a predetermined time delay following a predetermined impact acceleration force without substantial sophistication and resulting decreased reliability.

It is therefore an object of the present invention to provide an impact switch capable of providing an inherent delay before the actuation of the electrical con tacts after the predetermined impact.

It is a further object of the present invention to provide an impact switch that is relatively insensitive to accelerations and impacts giving rise thereto less than the predetermined actuation acceleration force.

It is still another object of the present invention to provide an impact switch that may be utilized to arm a second switch after a predetermined delay.

It is still another object of the present invention to provide an arming switch responsive to a predetermined impact for arming a second switch sensitive to deviation 3,453,406 Patented July 1, 1969 ICC from horizontal without regard to the precise attitude of the switches at the time of arming.

These and other advantages of the present invention will become apparent to those skilled in the art as the description thereof proceeds.

Briefly, in accordance with the embodiment chosen for illustration, a vertically aligned cylindrical enclosure containing a fluid such as silicon oil is provided with an electrically conductive float therein. A pair of contacts extend into the enclosure and are positioned such that the float can complete an electrical circuit through the contacts. One end of the enclosure is rupturable at a predetermined acceleration force in response to the pressure rise in the fluid caused by the acceleration of the impact. The resulting impact fluid pressure ruptures the enclosure, permitting the fluid to flow into a second enclosure containing a floatable platform therein having a tilt-sensitive switch mounted thereon. The resulting interaction of the fluid in the first enclosure with the ruptured portion of the enclosure permits the closing of an electrical circuit arming the tilt-sensitive switch after a predetermined delay.

The present invention may more readily be described by reference to the accompanying drawings, in which:

FIGURE 1 is a schematic block diagram of an antipersonnel actuation utilizing the impact switch of the present invention.

FIGURE 2 is a cross-sectional view of an impact arming switch constructed in accordance with the teachings of the present invention.

FIGURE 3 is a perspective view, partly in section, showing the deflection means of FIGURE 2.

FIGURE 4 is a perspective view, partly in section, of the floatable platform of FIGURE 2.

Referring now to FIGURE 1, an anti-personnel device may include the arrangements of elements schematically shown therein. Characteristically, a power source, as a battery 10, provides the necessary electrical power to explode the device through a bridge wire-type detonator 11. To insure that predetermined conditions exist before detonation occurs, a variety of control functions are interposed in series with the power source 10 and the detonator 11. A manual arming switch 12 is usually provided to permit the device to be handled prior to delivery; the arming switch 12 is closed, thus arming the remaining control functions of the device. A diode 14 may be provided to prevent reverse current and possible accidental detonation. An impact switch 15 is provided and is responsive to a predetermined acceleration force imparted to the device; for example, the impact switch may be designed to close when a force of 300 gs is exerted thereon, such as by air delivery, causing the acceleration force to be experienced when the device strikes the ground. The impact switch is connected in series with a disturb switch 20 and one or more tamper switches 21. The disturb and tamper switches are connected to the detonator 11 on the side opposite from the power supply 10. The impact switch is also connected to a timer 23 which may be utilized to close the circuit to the detonator 11 through a silicon controlled rectifier 24.

The operation of the application shown in FIGURE 1 may be described as follows. The device is manually armed by closing the switch 12 prior to air delivery to the target. The device is released from an airplane and,

upon striking the ground, the impact switch is closed. The device is thus armed, and closure of the disturb switch or the tamper switches 21 results in detonation. The timer 23 is designed to gate the SCR 24 after a long delay (e.g., six (6) months). Gating of the SCR 24 also results in detonation. The present invention will now be described by reference to FIGURES 2, 3, and 4; to more readily describe the function of the present invention, the terminals A, B, and C have been indicated on FIGURE 1 and in FIGURE 2, thus showing the connection of the present invention into the system of FIGURE 1. A first cylindrical enclosure 25 contains a fluid 26 such as silicon oil and is provided with an electrically conductive float 27. When the enclosure 25 is in a normally upright position as shown in FIGURE 2, the float 27 will remain in the top thereof. The bottom of the enclosure 25 includes a cap 30 having a conical inner surface 31 terminating in a small opening 32. The cap 30 supports electrical contacts 34 and 35 which extend into the enclosure. A frangible or rupturable disc covers the opening 32 in the cap 30 and maintains the fluid 26 in the enclosure 25. An air bleed passage 41 is provided in the cap 30 and connects to a capillary tube 42 extending from the cap to the top of the enclosure.

A second cylindrical enclosure is provided and is positioned adjacent to the rupturable disc 40. The enclosure 50 contains a second fluid which is most instances will simply be air. An opening 51 is provided in the enclosure 50 and is positioned opposite the opening 32. A fluid deflecting means 55 is positioned at the top of the enclosure 50 and provide a conical surface 56 supported by a plurality of legs 57 extending from a supporting plate 58 to receive the fluid 26 through an opening 60 and direct the fluid to the inside surface 61 of the enclosure 50. A floatable platform is contained within the enclosure 50 and normally rests at the bottom of the enclosure until the fluid 26 enters the enclosure 50. The floatable platform is obviously heavier than the air contained in the enclosure 50, but the toroidal pontoon 72 provides buoyancy for the platform when the fluid 26 enters the enclosure 50. A tilt-sensitive switch 75 is mounted on the platform 70 and is electrically connected externally to the enclosure 50 through flexible leads 78 and 79.

In operation, the device of the present invention is oriented so that the acceleration forces resulting from impact are substantially in the direction indicated in FIGURE 2 by the arrow 80. The impact force gives rise to substantial increase in the pressure within the enclosure 25, causing the disc 40 to rupture. The fluid 26 thus flows through the relatively small opening 32, through the openings 51 and 60 onto the surface 56 of the deflecting means 55. The air within the enclosure 50 travels through the passage 41 and capillary tube 42; the capillary tube as well as the opening 32 is calibrated to permit the fluid 26 to escape from the enclosure 25 at a, predetermined rate such that the conductive float 27 contacts the electrical contacts 34 and 35 only after a predetermined time delay. Thus, the switch represented by the contacts 34 and 35 and the float 27 is not closed until the fluid 26 has escaped through the opening 32 down the walls 61 into the enclosure 50. It will be seen that before the contacts above described are closed, the floatable platform 70 will he supported by the fluid 26 in the enclosure 50.

When the float 27 closes the electrical circuit with the contacts 34 and 35, a tilt-responsive switch 75 will become armed. It will be seen that since the fluid 26 is now supporting the floatable platform 70 upon which the switch 75 is mounted, the platform 70 will assume a horizontal position without regard to the attitude of the device (within design limitations which may be, for example, up to 45 from vertical). The tilt-responsive switch 75 is thus armed and is held in a horizontal position; any subsequent disturbance of the device giving rise to a slight wave motion or ripple on the surface of the fluid supporting the platform 70 will cause the tilt switch 75 to close. Tilt-sensitive switches may be made responsive to such slight deviations from horizontal that merely touching the device of FIGURE 2 will result in switch closure of the tilt switch 75. It may be seen from FIGURE 1 that a closure of the impact switch and the disturb switch (tilt switch 75) results in detonation. A further inspection of FIGURE 2 reveals that if the rest attitude of the device exceeds a predetermined designed maximum (e.g., 45 from vertical), the floatable platform can readily be made to interfere with the walls of the enclosure 50 such that the tilt switch 75 will be closed at the time it is armed by the closure of the contacts 34 and 35. The device would therefore be self-destructive in the event it comes to rest in an unacceptable position.

-It will be obvious to those skilled in the art that the device of the present invention may be utilized in a variety of applications other than an anti-personnel mine and that applications requiring the activation of a second switch by a time delay impact switch may conveniently use the concepts of the present invention. It will also be obvious to those skilled in the art that the present invention was described in terms of a specific embodiment and that the invention is not limited by such limiting descriptive terms as cylindrical, normally open or normally closed, contacts, and so forth.

I claim:

1. An impact arming switch comprising: a fluid-containing enclosure having a rupturable wall; an electrically conductive float positioned in a rest position within said enclosure and having an operative position; a pair of electrical contacts extending into said enclosure and positioned to be electrically connected by said float when in one of said rest and operative positions and to be electrically disconnected when in the other of said positions; said rupturable wall responsive to a predetermined fluid impact pressure for rupturing and permitting said fluid to escape from said enclosure; said float responsive to the escape of fluid from said enclosure for assuming said operative position.

.2. The combination set forth in claim 1 wherein said enclosure is a vertically oriented cylinder having a rupturable bottom.

3. The combination set forth in claim 1 wherein said enclosure is a vertically oriented cylinder having a rupturable bottom and said electrical contacts are positioned in said cylinder adjacent said rupturable bottom.

4. The combination set forth in claim '1 wherein said electrical contacts are open when said float is in said rest position and closed when said float is in said operative position.

5. The combination set forth in claim 3 wherein said electrical contacts are open when said float is in said rest position and closed when said float is in said operative position.

6. An impact arming switch comprising: a first enclosure containing a first fluid and having an electrically conductive float therein; a second enclosure containing a second fluid having a lower density than said first fluid and having a floatable platform therein buoyant in said first fluid but not buoyant in said second fluid; a rupturable wall separating said first and second enclosures responsive to a predetermined fluid impact pressure for rupturing and permitting said first fluid to escape into said second enclosure; a pair of electrical, normally open contacts extending into said first enclosure adjacent said rupturable wall, said electrical contacts being closed by said conductive float when said first fluid escapes into said second enclosure; a tilt switch mounted on said floatable platform responsive to a predetermined deviation from horizontal, said switch and platform supported by said first fluid when the latter escapes into said second enclosure.

7. The combination set forth in claim 6 wherein said pair of electrical contacts are normally closed and wherein said contacts are opened by said conductive float when said first fluid escapes into said second enclosure.

8. The combination set forth in claim 6 including means connecting said pair of electrical contacts and said tilt switch in electrical series.

9. The combination set forth in claim 6 wherein said enclosures are vertically oriented cylinders.

10. The combination set forth in claim 6 including fluid deflecting means mounted in said second enclosure adja- 10 6 References Cited UNITED STATES PATENTS 3,049,601 8/1962 Hardesty 20061.08 XR 3,086,468 4/1963 Mountjoy et a1 102-702 3,167,018 1/1965 Brunner 102-702 ROBERT K. SCHAEFER, Primary Examiner.

M. GINSBURG, Assistant Examiner.

US. Cl. X.R.

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