US3760734A

US3760734A - Delayed arming device

Info

Publication number: US3760734A
Application number: US00248470A
Authority: US
Inventors: J Brothers
Original assignee: US Department of Army
Current assignee: US Department of Army
Priority date: 1972-04-28
Filing date: 1972-04-28
Publication date: 1973-09-25
Anticipated expiration: 1990-09-25

Abstract

A delayed arming device for fuzes and the like wherein a slide member carrying a detonator is biased toward an armed position such that the detonator is aligned with a firing pin but restrained by a bore riding pin in its unarmed state. The slider carries a vibratory member whose shaft extends through a fixed, restricted opening so that as the slider moves between the unarmed and armed positions the effective shaft length decreases. The munition within which the device is operative, upon firing, produces a setback force therein that initiates the vibratory motion of the member. Upon exiting the bore, the bore riding pin is ejected and the slider commences its travel toward the armed position. The movement of the slider is slowed by the vibratory impact of the shaft against the walls of the opening through which it passes thereby acting as an effective fulcrum. Thus, the slider motion is delayed and when the vibration amplitude sufficiently decreases the slider will quickly complete its travel to arm the fuze.

Description

[73] Assignee: The United States of America as represented by the Secretary of the 102/81; ZOO/61.45, 61.53

llnited States Patent 1 [111 anaemia Brothers 51 Sept. 2%, 119 733 4] DELAYED ARMING DEVICE [57] ABSTRACT A delayed arming device for fuzes and the like wherein a slide member carrying a detonator is biased toward an armed position such that the detonator is aligned with a firing pin but restrained by a bore riding pin in its unarmed state. The slider carries a vibratory member whose shaft extends through a fixed, restricted opening so that as the slider moves between the unarmed and armed positions the effective shaft length decreases. The munition within which the device is operative, upon firing, produces a setback force therein that initiates the vibratory motion of the member. Upon exiting the bore, the bore riding pin is ejected and the slider commences its travel toward the armed position. The movement of the slider is slowed by the [56] References Cited vibratory impact of the shaft against the walls of the UNITED STATES PATENTS opening through which it passes thereby acting as an 9 3 08 I effective fulcrum. Thus, the slider motion is delayed g g glanscheld and when the vibration amplitude sufficiently de- 3O22393 2/1962 222; I61 53 creases the slider will quickly complete its travel to arm 1,992,926 2/1935 Towner 102/78 the 2,595,757 5/1952 Brandt 102/78 6 Claims, 2 Drawing Figures Primary ExaminerSamuel Feinberg Assistant ExaminerH. J. Tudor Attorneyl-larry M. Saragovitz et al.

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3/ 22 4 27 1 5 j /l m I PMEWEU SW25 I973 SHEETZUFZ A///////////////// 9%? M c V M M l/IIIII" W 4 w l DELAYED ARMING DEVICE The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION The present invention relates to munition arming systems and more particularly pertains to delayed arming devices wherein a vibratory reed-like member impedes the movement of a slide member that aligns the explosive train with a firing mechanism.

In the field of delayed arming devices, it has been the general practice to employ pneumatic or hydraulic dashpots, friction, gravity and pyrotechnic delays as well as mechanical timers to provide the necessary delay. The dashpots and electrical timers are expensive as well as complex in structure, while those delay dependent on friction and gravity or pyrotechnics have proved to be unreliable and subject to malfunction under the extreme military environments to which they are subjected. The present invention overcomes these problems and fills this need.

SUMMARY OF THE INVENTION The general purpose of this invention is to provide a fuze delay that has all the advantages of similarly employed prior art devices and has none of the above described disadvantages. To attain this, the present invention provides a unique structural arrangement wherein a vibratory member that includes a cantilevered stem is affixed to an element movable under the action of a biasing force. The free end of the stem supports a selectable mass while the stem passes through a restricted orifice. In the unarmed position, prior to launch of the projectile carrying the fuze, the movable element is positioned such that the stern extends almost entirely through the orifice. Upon launch, the generated setback force deflects the mass so that vibratory oscillations commence on the termination of the setback and at the same time the movable element under the biasing force, initiated by the exit of the projectile from the barrel, starts to move in a direction to align the explosive firing train (armed). In initially so moving, the element is temporarily restrained by the frictional forces induced by the stem repetitively striking the wall of the orifice through which it passes. As the element progresses in its line of travel, the effective fulcrum length of the vibratory member decreases and the element moves more rapidly until it reaches a point at which it acts as if it were free of the vibratory restraint.

An object of the present invention is to provide a reliable, simple and inexpensive delayed arming device for use in a munition fuzing system.

Another object is the provision of a slider type delay which initially impedes the progress of the slider and thereafter permits the slider to'properly impact.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a cross-sectional view of an embodiment made in accordance with the principle of this invention prior to release or launch of the projectile while in the safe or unarmed condition; and,

FIG. 2 is a cross-sectional view of the embodiment after launch and in the armed condition.

DlESCRIPTlON OF A PREFERRED EMfiODlMENT In the illustrated embodiment of HG. l the delay fuze mechanism W is supported within a fuze structure 1111 (partially removed) which includes a body 112 that is provided with an internal cavity H3. The cavity has disposed therein for sliding movement, a slider assembly H4. The body 12 is formed with a lateral opening which is aligned for entry therein of an impact firing pin 16. An explosive lead cup assembly 117 is supported within the fuze body in opposed relation with the firing pin 36. The slider lid carries intermediate its ends a detonator l8 and communicates outwardly thereof via

slider passages

19 and 20. The slider is restricted in its downward movement by bore riding pin 211 which extends transversely of the slider and passes through an opening in the projectile. Biasing means urge the pin outwardly and while the projectile is within the barrel or launch tube it rides on the bore thereof.

Affixed by threads 22 into the fuze body, the slider plug 23 is disposed above the slider M and is formed with an internal cavity 24 while closed across the upper end. Fulcrum cap 25 which is in the form of an inverted cup has an orifice 26 in its lower wall 27 and is positioned within the plug cavity 24. Annular lateral lip 28 of the cap 25 bears against the inner lower wall 29 and thereby forms a longitudinal channel 30 between the inner wall 31 of the plug and the outer face 32 of the fulcrum cap. Disposed about the cap in the channel is a biasing means such as helical spring 33 whose upper end abuts the lip 28 and whose lower terminus bears against the outwardly extending lip 34 of cylindrical spring keeper 35. The lower face 36 of the keeper 35 under the compress force of the spring 33, bears against the slider face 37 to urge it downwardly but which is itself restrained by the bore pin 21. Rigidly attached to the upper slider face 37 and extending centrally and upwardly thereof through orifice 26 is the shaft 38 of the vibratory member 39 that also includes the mass M carried by the free end of the flexible shaft 38. The parameters including the mass and length of the member 39 can be selected to provide optimum operational characteristics. Since the movement of the slider is not entirely uniform throughout its path, the fuze is provided with a slide guide pin 41 which rides in a slot within the slide.

Operationally the delay mechanism 10 is carried in a projectile that is initially at rest within the barrel or launch tube and oriented for flight in the direction of the firing pin, namely to the left. Upon firing, the projectile commences its movement up the barrel and this immediately induces a setback force that deflects the mass 30 to the right, as the projectile moves toward the left. When the setback force terminates the member 39 commences its oscillatory or vibratory motion about the fulcrum effectively defined by the orifice 26. Although the slider is being urged downwardly, its position is fixed by the bore pin 22. As the projectile exits the barrel, the bore pin is ejected and the slider is free to commence its travel. lFlG. 2 illustrates the slider assembly at the lower end of its path. Spring 33 forces the slider to move down but at the same time the vibratory member 39 is continuously oscillating and in so doing the shaft intermittently abuts the annular inner wall 4l2 of the orifice 26 at each extremity of its travel. This striking of the shaft slows the movement of the slider initially but permits it to increase its velocity thereafter. This is true due to the fact that at the start the effective vibratory shaft length is approximately its full dimension but as the slider progresses this length continually diminishes to a point where the vibratory motion is ineffective in impeding the slider movement. During the terminal portion of travel the slider attains sufficient speed to properly seat and position itself. In the armed position the slider is disposed so that the detonator 18, which it carries, is disposed intermediate the impact firing pin 16 and the explosive lead cup assembly 17 so as to provide an explosive train which is initiated by impact of the projectile and the subsequently stabbing of the detonator by the firing pin.

Summarizing, the projectile is fired, set back deflects the vibrating reed rearwardly and, as the projectile leaves the launcher (mortar tube), the bore riding (safety pin) (21) is ejected. This permits the spring, which is pushing against the spring'keeper and thus against slider, to move the slider which is now free to move rapidly toward the armed position. Movement of the slider is delayed at the vibrating reed deflected by set back. The vibrating reed, set in motion at setback and when the setback forces decay, vibrates in the fulcrum cap in decreasing amplitudes, using the hole in the fulcrum cap as a fulcrum point for its vibrations. The reed straightens out as it passes the mean of its arc, so the slider may move slightly toward the armed position at that instant, by the constant pushing of the compression spring. However, most of the movement of the slider takes place after vibration amplitude has been reduced to the value where the spring can slam the slider to the armed position suddenly. When that happens, the slider has been delayed a sufficient length of time and the projectile has passed the point where a premature burst would injure the gun crew or friendly troops. With the slider in the armed position, the fuze can be functioned when the striker is depressed by impact with something, such as ground, stabbing the detonator in the slider which functions and also causes functioning of the rest of the explosive train and the munition.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

I claim:

1. In a fuze carried by a projectile wherein a firing pin is spaced from and aligned with an explosive assembly, a delay arming device which comprises:

a hollow housing provided with aligned openings extending laterally therethrough wherein said firing pin and said explosive assembly are operatively disposed,

a slider assembly supported for longitudinal sliding motion in said housing, and having a vibratory member extending centrally outwardly thereof,

a detonator carried by said slider assembly, where said detonator is in-line with said firing pin in one terminal position of said slider assembly and outof-line in the other terminal position.

safety means for preventing movement of said slider assembly prior to exit of said projectile from its launcher,

biasing means urging said slider assembly toward said one terminal position,

a removable plug means having an internal recess and supported in said fuze body axially of said slider assembly and having said biasing means disposed in said recess, and

an abutment fulcrum means having an axially restricted orifice therein through which said vibratory member extends, said fulcrum means operatively disposed in said recess whereby the walls of said restricted orifice provide a stationary fulcrum for said vibratory member as said vibratory member moves with said slider assembly,

whereby the movement of said slider assembly will be initially impeded due to the oscillatory motion of said vibratory member initiated by setback of said projectile to provide a delay in arming said projectile after said safety means have been inactivated.

2. The device according to claim 1 wherein said vibratory member includes:

a shaft rigidly affixed at one end to said slider assembly and a weighted mass carried at the free end of said shaft.

3. The device according to claim 1 wherein said fulcrum abutment means includes:

a fulcrum cap in the form of an inverted cup having a central orifice through which said shaft passes and a laterally extending lip abutting the upper inner wall of said plug thereby forming a channel intermediate said cap and the inner wall of said plug.

4. The device according to claim 3 wherein said biasing means includes a helical spring disposed in said channel having one end bearing against said fulcrum cap lip.

5. The device according to claim 4 further including a spring keeper intermediate said slider and the other end of said spring.

6. The device according to claim 5 wherein said safety means is a bore riding pin supported in said projectile transverse of said firing pin and being urged outwardly thereof.

Claims

1. In a fuze carried by a projectile wherein a firing pin is spaced from and aligned with an explosive assembly, a delay arming device which comprises: a hollow housing provided with aligned openings extending laterally therethrough wherein said firing pin and said explosive assembly are operatively disposed, a slider assembly supported for longitudinal sliding motion in said housing, and having a vibratory member extending centrally outwardly thereof, a detonator carried by said slider assembly, where said detonator is in-line with said firing pin in one terminal position of said slider assembly and out-of-line in the other terminal position. safety means for preventing movement of said slider assembly prior to exit of said projectile from its launcher, biasing means urging said slider assembly toward said one terminal position, a removable plug means having an internal recess and supported in said fuze body axially of said slider assembly and having said biasing means disposed in said recess, and an abutment fulcrum meAns having an axially restricted orifice therein through which said vibratory member extends, said fulcrum means operatively disposed in said recess whereby the walls of said restricted orifice provide a stationary fulcrum for said vibratory member as said vibratory member moves with said slider assembly, whereby the movement of said slider assembly will be initially impeded due to the oscillatory motion of said vibratory member initiated by setback of said projectile to provide a delay in arming said projectile after said safety means have been inactivated.

2. The device according to claim 1 wherein said vibratory member includes: a shaft rigidly affixed at one end to said slider assembly and a weighted mass carried at the free end of said shaft.

3. The device according to claim 1 wherein said fulcrum abutment means includes: a fulcrum cap in the form of an inverted cup having a central orifice through which said shaft passes and a laterally extending lip abutting the upper inner wall of said plug thereby forming a channel intermediate said cap and the inner wall of said plug.