Patent Publication Number: US-6705231-B1

Title: Safing and arming device for artillery submunitions

Description:
This application claims benefit of Ser. No. 60/122,258 Feb. 28, 1999 and claims benefit of WO/251,349 Dec. 4, 2000. 
    
    
     U.S. GOVERNMENT INTEREST 
     The inventions described herein may be manufactured, used and licensed by or for the U.S. Government for U.S. Government purposes. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to control devices for rounds shot by artillery and, more particularly, to a control device for automatically and sequentially making safe and then arming a fired round. 
     2. The Related Art 
     A need exists for safety controls during the firing of artillery submunitions which ensure that the detonator device (fuze) is safe during the initial firing stage but which also ensures that the fuze is armed at the proper time. To the extent that the problem has been previously addressed, current proposals suffer shortcomings and are less than fully satisfactory. One application of such a control device is for SADARM submunitions developed by the U.S. Army but such a device could be applied to other artillery submunitions as well. 
     SUMMARY OF THE INVENTION 
     According to the invention, there is provided a safing and arming device for artillery submunitions which meets stringent safety and arming requirements. The device is compact and rugged as well as highly reliable and effective. 
     In accordance with a preferred embodiment of the invention, there is provided a safing and arming device for a warhead or round which is to be launched by a rifled gun and which includes at least one submunition, the device comprising: 
     a housing; 
     a detonator and lead cup disposed in spaced, aligned relation within said housing; 
     a slider disposed in the housing between the detonator and lead cup and including an opening therein, the slider being movable between a first, safe position wherein a portion of the slider spaced from the opening is disposed between the detonator and lead cup so as to act as an interrupter, and a second, armed position wherein the opening is in alignment with the detonator and lead cup and the device is thus armed; 
     a setback sensor disposed in the housing for initially locking the slider in the safe position and for, responsive to a setback force produced at gun launch, unlocking the slider; and 
     an ejection sensor disposed in the housing for initially locking said slider in the safe position and for continuing to lock the slider against movement to the armed position during a period between gun launch and exiting of the warhead from the gun, and for, responsive to the ejection force produced at the exiting of the warhead from the gun, unlocking the slider to enable movement thereof to the armed position. 
     Preferably, the device further comprises a slider spring for biasing said slider into said safe position. The slider spring preferably comprises a coil spring producing an axially acting force against one end of the slider. 
     Preferably, the setback sensor comprises a setback sensor member received in a cavity in the housing and the device further comprises a setback spring for biasing the setback sensor member towards engagement with the slider. The setback spring preferably exerts a spring force orthogonal to an axially active spring force produced by the slider spring. The slider preferably includes an abutment portion having surface engaged by the setback sensor member in the safe position of the slider. The setback spring is compressed by the setback force so as to disengage the setback sensor member from the abutment portion and the abutment portion preferably includes a further surface engaged by the setback sensor member after movement of the slider to the armed position thereof so as to provide locking of the slider in the armed position by the setback sensor member. 
     Preferably, the slider includes a recess therein, the device further comprises an ejector spring received in the recess, and the ejection sensor comprises an ejection sensor member received in the recess and biased by the ejection spring against a portion of the housing in a locking position of the ejection sensor member. Advantageously, the ejection spring exerts a spring force orthogonal to an axially acting spring force produced by the slider spring. Preferably, a portion of the housing includes a stop member and the ejection member engages the stop member responsive to movement of the slider caused by the setback force to thereby limit the movement of the slider. The ejection spring is compressed by the ejection force to disengage the ejection sensor member from the stop member and to unlock the slider to permit movement of the slider to the armed position. The movement of the slider to the armed position causes positioning of the ejection sensor member on the other side of the stop member and a diminishing of the ejection force enables the ejection spring to bias the ejection sensor member in a locking position thereby locking the slider in the armed position. 
    
    
     Further features and advantages of the present invention will be set forth in, or apparent from, the detailed description of preferred embodiments thereof which follows. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view, partially broken away, of a safing and arming device constructed in accordance with a preferred embodiment of the invention showing the device in the safe position; 
     FIGS.  2 ( a ) and  2 ( b ) are cross-sectional views taken generally along lines A—A and B—B, respectively; 
     FIG. 3 is a schematic representation of the sequence of events occurring during the launch of a warhead which has been launched by a rifled gun and which incorporates the safing and arming device of the invention; 
     FIGS.  4 ( a ) and  4 ( b ) are views similar to FIGS.  2 ( a ) and  2 ( b ) showing the setback mode or position of the device; 
     FIGS.  5 ( a ) and  5 ( b ) are further views similar to FIGS.  2 ( a ) and  2 ( b ) showing the setback spin mode or position of the device; 
     FIGS.  6 ( a ) and  6 ( b ) are further views similar to FIGS.  2 ( a ) and  2 ( b ) showing ignition mode or position of the device; 
     FIGS.  7 ( a ) and  7 ( b ) are further views similar to FIGS.  2 ( a ) and  2 ( b ) showing the ejection/spin mode or position of the device; and 
     FIGS.  8 ( a ) and  8 ( b ) are further views similar to FIGS.  2 ( a ) and  2 ( b ) showing spin mode or position of the device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring first to FIG.  1  and FIGS.  2 ( a ) and  2 ( b ), the safing and arming device or unit of the invention, which is generally denoted  10 , includes the following major components: a slider  12 , a setback sensor  14 , an ejection sensor  16 , and three spring, a slider spring  18 , a setback spring  20  and an ejection spring  22 . 
     The device or unit  10  also includes a housing  24  including an upper portion  24   a  which houses a conventional detonator  26  and lower portion  24   b  which supports a conventional lead cup  28  in alignment with detonator  26 . Slide  12  includes an opening  12   a  therein which, in the armed position of slide  12  described below, provides a passage between detonator  26  and lead cup  28 . 
     Before describing these figures and the other figures of the drawings in more detail, a brief overall overview would be presented for purposes of orienting the discussion which follows. As indicated above, slider  12  acts as an interrupter between the detonator  26  and the lead cup  28  and has a safe position (shown in FIGS. 1,  2 ( a ) and  2 ( b ) among others) and an armed position shown in other drawing figures. Slider  12  is held in the safe position by the setback sensor  14 , the ejection sensor  16 , and the slider spring  18 . As described in more detail below, the ejector sensor  16  is located within the slider  12 . The setback sensor  14  reacts to the gun launch setback force and unlocks the slider  12 . The ejection sensor reacts to the force produced by the ejection of the submunition from the warhead or round and unlocks the slider. The springs  18 ,  20  and  22  function in a manner described below to keep the slider  12  in the safe and locked position. 
     The basic operation can also be better understood by considering FIG. 3, which is a schematic representation of the operational sequence. The rifled gun is represented at  30 , the warhead and subparts at  32  and the raid deploy submunition at  34 . In FIG. 3, “A” generally indicates the point in the sequence at which the setback sensor  14 , in response to the gun launch setback force, unlocks slider  12 . “B” indicates the point at which the slider  12  moves to the ejector sensor lock position described below wherein the fuze  25  is in the safe mode. “C” indicates the point at which the ejection sensor  16  unlocks the slider  12  so that the fuze  25  is armed. Finally, “D” indicates the point at which the ejection sensor  16  locks the slider  12  in the armed position. 
     Referring again to FIGS. 1,  2 ( a ) and  2 ( b ), as illustrated, slide spring  18  is a coil spring which is captured within a cavity  24   c  in housing  24  and which bears on one end of slider  12  so as to bias slider  12  into the safe position shown. 
     As indicated above, and is best seen in FIG.  2 ( a ), ejector sensor  16  is received in an opening  12   c  in an upright end portion  12   d  of slider  12  and is biased by ejector spring  22  into a cavity  24   d  in upper housing  24   a  against an upper end wall defined by the cavity,  24   d . A stop  24   e  projects into cavity  24   d  as shown and performs a function described below. 
     As shown in FIG.  2 ( b ), setback sensor  14  is received in a further cavity  24   f  in housing  24 , and engages and is biased against one side of a further part  12   e  of the upright end portion  12   d  of slider  12 . 
     Referring to FIGS.  5 ( a ) and  5 ( b ), the setback/spin mode or position is shown. As the spin within the gun  30  (FIG. 3) decreases, the centrifugal force on slider  12  will be sufficient to move slider  12  against slider spring  18 . The slider  12  will move a short distance (0.050 in an exemplary embodiment) to a point where the ejection sensor  16  engages stop  24   e . In this position, slider  12  locks the setback sensor  14  in the unlocked position. However, the slider  12  remains in the detonation safe position and this situation is indicated at B in FIG.  3 . After the gun tube exit, the spin force keeps the slider  12  pressed against the slider spring  18  and the ejection sensor  16  keeps the slider  12  in the safe position. 
     FIGS.  6 ( a ) and  6 ( b ) illustrate the ejection mode or position. Upon the ejection of the submunition from the warhead as shown generally at  32  in FIG. 3, the resultant ejection force compresses the ejection sensor  16  against the ejection spring  22  and fully unlocks slider  12 . 
     Referring to FIGS.  7 ( a ) and  7 ( b ), the ejection/spin mode or position is shown. Upon unlocking of the slider  12  from the ejection sensor  16 , the spin present will force the slider  12  into the armed position, compressing the slider spring  18 . This situation is indicated at C in FIG.  3 . As soon as the slider  12  clears the setback sensor  14 , the ejection force will move the setback sensor  14 , together with the setback spring  20 , into a further slider lock position wherein sensor  14  engages the other side of the further part  12   e  of upright end portion  12   d  of slider  12 , as shown. 
     The final, spin position or mode is shown in FIGS.  8 ( a ) and  8 ( b ). As soon as the ejection force dissipates, the ejection spring  22  forces the ejection sensor  16  into the slider lock position. At this point, no forcing function will unlock the slider  12  since both of the locks now provided act in the opposing direction to any unlocking movement. Thus, the device is fully armed and cannot be unlocked. 
     It will be noted that the device  10  is quite small, with the length and width dimensions shown in FIG. 1 being 1.395 inches by 1.125 inches in a specific, non-limiting example. 
     Although the invention has been described above in relation to preferred embodiments thereof, it will be understood by those skilled in the art that variations and modifications can be effected in these preferred embodiments without departing from the scope and spirit of the invention.