Abstract:
A mechanical, rotary, spring driven, snap action mechanism which has two snap positions, with an intervening intermittent delay.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a snap action mechanism and, more particularly, to such a mechanism that is mechanical, rotary, spring-driven and which has two snap positions, with an intermittent delay. 
     A need has arisen for a mechanical delay which has a double snap action. More specifically, the interfacing (i.e., driving) element of the escapement should, upon release, snap through an arc. Then, move slowly through another arc in the same direction to provide the desired delay time. Then, and finally, snap through a third arc also in the same direction, to its final position. 
     I have invented a mechanism which fulfills this need; and, thereby, I have significantly advanced the state-of-the-art. 
     SUMMARY OF THE INVENTION 
     The invention pertains to a double snap acting delay mechanism which satisfies the aforesaid need. 
     accordingly, the principal object of this invention is to provide the aforesaid described double snap acting delay mechanism. 
     This object, as well as other related objects, of this invention will become readily apparent after a consideration of the description of the invention, together with reference to the Figures of the drawings, in which the same reference character refers to the same component and the like. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-3, inclusive, are top plan views, in simplified pictorial and schematic form, of a preferred embodiment of my inventive mechanism, in a working environment, during the following sequential phases or conditions of operation: FIG. 1, initial position (i.e., engaged); 
     FIG. 2, intermediate (i.e., released; and, 
     FIG. 3 final position (i.e., re-engaged). 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As a preliminary matter, it is to be noted that in FIGS. 1-3, the preferred embodiment 10 of my inventive mechanism is shown in an adaptation where the mechanism serves as a safing and arming device timer gate to trap, then release, then retrap a safety pin 20. This adaptation or application is for illustrative purposes only, and is not intended as a limitation of my inventive mechanism. 
     Still with reference to FIGS. 1-3, inclusive, the preferred embodiment of my inventive double snap acting delay mechanism includes: a shaft 11; a first member 12 that is pivotally mounted on the shaft 11, and that has a first end 12A of a preselected configuration (i.e., in this instance, to complement the periphery of safety pin 20); a means, generally designated 13, for selectively restraining and releasing the first end 12A of the first member 12; a second member 14 that is adjacent to the first member 12, that is pivotally mounted on the shaft 11, and that has a first leg 14A which is complementary to the first end 12A of the first member 12, a second leg 14B, and a third leg 14C; means, generally designated 15, for biasing the first member 12 to the second member 14, with this biasing means 16 also interconnecting the first member 12 near its first end 12A and the second member 14 near its second leg 14B; and, means, generally designated 16, for selectively and arcuately (i.e., angularly) moving the third leg 14C of the second member 14. 
     The means 13 for selectively restraining and releasing the first end 12A of the first member 12 (and, of course, the first member 12) is disposed at the first end 12A of the first member 12, and is movable (as indicated by the directional arrow) from that position. 
     The means 15 for biasing the first member 12 to the second member 14 includes, preferably, a torsion spring 15A (i.e., a drive spring) that is attached to the first member 12. The spring 15A has a first end 15B which passes into, and extends through, the first member 12 near the first end 12A of that member 12. The first end 15B of the spring 15A also engages an arcuate slot 14D in the second member 14, near the second leg 14B of that member 14. 
     The means 16 for selectively and arcuately (i.e., angularly) moving the third leg 14C of the second member 14 includes: a gear segment (i.e., sector) 16A at the first end 14E of the third leg 14C of the second member 14; and, a rotatable pinion 16B that is complementary to, and mates with, the gear segment 16A. 
     It is to be noted that, as a matter of preference and not of limitation, the first leg 14A, the second leg 14B, and the third leg 14C of second member 14 are disposed in equal spaced-apart relationship. 
     MANNER OF OPERATION OF THE PREFERRED EMBODIMENT 
     The manner of operaation of the preferred embodiment 10 can be easily ascertained by any person of ordinary skill in the art from the foregoing description, coupled with reference to FIGS. 1-3, inclusive. 
     For others, it is sufficient to say in explanation that, when the first end 12A of the first member 12 is selectively released by moving restraint 13, the first member 12 is released and snaps arcuately (i.e., angularly) clockwise (as indicated by the phantom arrow, FIG. 2) until the first end 15B of the drive spring 15A reaches the end of slot 14D in second member 14. At this point, both the first member 12 and the second member 14 (including gear segment 16A) are driven (by drive spring 15A) arcuately clockwise. As soon as the gear segment 16A has rotated out of mesh with the pinion 16B, FIG. 3, the first and second members 12 and 14 snap to the terminal position. 
     As previously stated herein, an application of my invention is as a safing and arming device timer gate. The two &#34;arms&#34; (i.e., configurated first end 12A of first member 12, and complementarily configured first leg 14A of second member 14) trap, then release, then retrap a safety pin, such as 20, FIGS. 1-3, inclusive. 
     CONCLUSION 
     It is abundantly clear from all of the foregoing, and from the Figures of the drawings, that the stated desired principal object, as well as other related objects, of the invention have been achieved. 
     It is to be noted that, although there have been described and shown the fundamental and unique features of my invention as applied to a preferred embodiment adapted for a particular application, various other embodiments, variations, adaptations, substitutions, additions, omissions, and the like may occur to, and can be made by, those of ordinary skill in the art, without departing from the spirit of my example. For example, first member 12 and second member 14 preferably are made of metal, but may be made of what is colloquially referred to as &#34;plastic&#34; material.