US 3640225 A
A centrifugally displaced fluid barrier for a spin-operated fuze arming delay. Safing and delay arming is provided by a relatively high density fluid positioned along the spin axis of a munition to block the output of a detonator along the spin axis. The fluid completely fills a chamber with the exception of a relatively small volume air bubble. Under sustained spin environment, the air bubble is displaced by centrifugal forces within the fluid into a position along the axis of the munition, allowing the detonator output to pass through the air chamber. Various configurations of the chamber to provide arming delay are contemplated.
Description (OCR text may contain errors)
United States atent Carlson et al.
[ Feb. 8, 1972 both of Minneapolis, Minn.
 Assignee: Honeywell Inc., Minneapolis, Minn.
 Filed: June 20, 1969  Appl. No.: 835,186
FOREIGN PATENTS OR APPLICATIONS 17,795 1905 Great Britain l02/80 Primary Examiner-Samuel W. Engle Attorney-Charles J. Ungemach, Ronald T. Reiling and Albin Medved  ABSTRACT A centrifugally displaced fluid barrier for a spin-operated fuze arming delay. Safing and delay arming is provided by a relatively high density fluid positioned along the spin axis of a munition to block the output of a detonator along the spin axis. The fluid completely fills a chamber with the exception of a relatively small volume air bubble. Under sustained spin environment, the air bubble is displaced by centrifugal forces within the fluid into a position along the axis of the munition, allowing the detonator output to pass through the air chamber. Various configurations of the chamber to provide arming delay are contemplated.
3 Claims, 2 Drawing Figures Pmmanrw 8H7? 3.640.225
INVENTORS DONOVAN R. CARLSON WILLIAM O. MARUSKA ATTORNEY ruzr: APPARATUS BACKGROUND OF THE INVENTION I. Field of the Invention The present invention pertains to percussive fuzes having safety means rendering the fume inactive for handling purposes and fuzes which are centrifugally armed in response to rotation of the projectile.
2. Description of the Prior Art Centrifugal arming is well known in the prior art. Most centrifugal arming arrangements, however, comprise mechanical locks and weights. Fluid has been utilized in some cases for the purpose of delaying the operation of the fuze.
U.S. Pat. No. 3,425,354, issued Feb. 4, 1969 and assigned to the assignee of the present invention, discloses a centrifugally armed fuze wherein fluid is used as a positive force in the arming sequence. A detonator positioned within a chamber has a normal position toward the periphery of the chamber. Upon spin, a buoyant slider member is displaced by the centrifugal force of the fluid to the center of the chamber in line with the spin axis of the munition where it is in position to be actuated by a firing pin and in turn initiate a pyrotechnic chain.
It is an object of the present invention to provide a simple spin-operated arming mechanism utilizing no moving parts.
SUMMARY OF THE INVENTION The present invention provides a centrifugally actuated fluid barrier for spin-actuated, delay arming fuzes. The fluid barrier is positioned across the spin axis to block a detonator output along the spin axis. The barrier is made up of a preferably circular cross-sectional chamber positioned perpendicular to the spin axis. The chamber is filled with a relatively high-density fluid containing a bubble. The chamber design is such that the bubble stays around the periphery of the chamber and will not locate itself along the spin axis except under sustained spin.
Under sustained spin, centrifugal force tends to push the fluid radially outward from the spin axis which centers the bubble along the spin axis. The detonator, having anoutput along the spin axis, can then initiate a lead cup or other explosive through the gap. Delay is achieved by selecting a viscous fluid through which the bubble will move at a controlled rate commensurate with chamber diameter, spin rate, and delay requirements. The delay may therefore be adapted to suit almost any spin to arm fuze application.
Premature initiation of the detonator will cause the detonator output to be blocked by the fluid barrier, thus protecting a lead explosive. The central portion of the chamber located along the spin axis is restricted in dimensions to prevent the bubble from entering this region accidentally during handling.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a typical embodiment of the invention.
FIG. 2 is a cross-sectional view of the embodiment of FIG. 1 in combination with a percussive fuze.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, a radially symmetrical chamber generally designated 1 is filled with a high-density fluid 2. The chamber 1 is completely filled with the exception of a small void 3 taking the form of a bubble. The central portion of the chamber is separated from the periphery by a restriction 4. The bubble 3 is therefore prevented from crossing through the center section due to this restriction. Upon spinning this barrier about the axis of symmetry, however, the centrifugal forces in the fluid displace the bubble 3 toward the center, causing it to deform from its natural spherical shape and pass through the restriction 4. In the absence of sustained spin, the bubble 3 will never enter the central region of the chamber 1.
Referring to FIG. 2, the chamber 1 is shown positioned in a munition comprising a nose 6 crimped onto a base portion 7 and having a plastic probe 8 inserted in the forward portion. A firing pin is located in a cavity directly aft of the probe 8. The firing pin 9 is separated from a detonator 10, also located along the axis of the munition, by a collar 11. The detonator 10 is positioned to fire toward the rear of the projectile along the axis into a lead cup 12. Between the detonator 10 and the lead cup 12 is a fluid barrier mechanism as represented in FIG. 1. The port between the detonator output and the lead cup 12 is blocked by the fluid contained within the chamber 1.
During launch of the embodiment shown in FIG. 2, all components are stationary. After the specified delay time in a spin environment, the air (or other appropriate gas) bubble is forced through the restriction and aligns with the explosive train along the munition axis between the detonator l0 and the lead cup 12. Upon impact, the plastic probe 8 is extruded through the hole in the ogive, shearing off the shoulder 11 on the firing pin 9. The firing pin is thus driven into the stab-initiating detonator 10. The detonator output initiates the lead cup through the air bubble and the frangible walls of the chamber.
The many variations possible on the configuration of the chamber will be realized by those skilled in the art. The considerations for the design of the chamber are that the bubble never pass through the center of the chamber under normal handling and that the barrier be of sufficient thickness to block the detonator output should it be initiated before arming is achieved. The thickness of thechamber is adjusted to require deformation of the bubble from its normal spherical shape in an armed" position. Due to the tendency of the bubble to remain spherical, a continuous force from all sides must be maintained to hold the bubble in its armed position.
Wherein I claim:
1. A centrifugally displaced fluid barrier for positioning on a spin axis of a spin munition, and between a lead explosive and a detonator positioned to initiate said lead explosive along the spin axis, comprising:
a hermetically sealed housing defining a chamber, said chamber being completely filled with a relatively highdensity fluid except for a buoyant bubble contained within and defined by said fluid, said housing having a restriction therein which prevents said bubble from being positioned along said spin axis unless said munition experiences sustained spin.
2. A fluid barrier safing and arming mechanism for separating an axially positioned detonator and lead cup in a spin operated fuze, comprising a hermetically sealed housing defining a chamber, said chamber being completely filled with a viscous fluid except for an air bubble contained within and defined by said fluid, said housing having a annular restricted thickness portion requiring deformation of said air bubble to occupy a position along the axis of said fuze, whereby said air bubble remains away from the axis of the fuze in all orientations except under a sustained spin environment thereby allowing the detonator to fire through the air bubble to initiate the lead cup.
3. A centrifugally displaced fluid barrier for positioning on a spin axis of a spin munition, and between a lead explosive and a detonator positioned to initiate said lead explosive along the spin axis, comprising:
a radially symmetrical hermetically sealed housing defining a first chamber and a second chamber, said chambers being positioned coaxially with said spin axis between said detonator and said lead explosive, said second chamber being further from said spin axis than said first chamber and communicating with said first, chamber through a restricted portion, said chambers being filled with a relatively high-density fluid free to flow therebetween, said fluid containing and defining a bubble, said bubble being normally within said second chamber and unable to pass through said restricted portion into said first chamber until said munition fuze experiences sustained spin whereupon said bubble becomes positioned along said spin axis.