Medium caliber high explosive dual-purpose projectile with dual function fuze

Abstract

A multi-mode fuze for a munition has at least one sensor that generates an electrical output dependent on a rate of deceleration when the munition impacts a target, a logic circuit electrically coupled to the at least one sensor effective to discriminate between a soft target and a hard target dependent on the electrical output and a fuze that transmits a detonation signal to an initiating explosive to thereby detonate the munition. The detonation signal is transmitted at a time dependent on target discrimination. The multi-mode fuze of the invention may be incorporated into an explosive projectile that includes an aerodynamically shaped metallic casing, an explosive contained within the metallic casing and an initiating explosive contacting the explosive. The multi-mode fuze communicates with the initiating explosive to trigger detonation of the explosive either on impact with a hard target or following a delay on impact with a soft target.

We claim:  
     
         1 . A multi-mode fuze for a munition, comprising: 
 at least one sensor that generates an electrical output dependent on a rate of deceleration when said munition impacts a target;    a logic circuit electrically coupled to said at least one sensor effective to discriminate between a soft target and a hard target dependent on said electrical output; and    a fuze that transmits a detonation signal to an initiating explosive to thereby detonate said munition, said detonation signal being sent at a time dependent on target discrimination.    
     
     
         2 . The multi-mode fuze of  claim 1  wherein said at least one sensor is a single piezoelectric crystal and said electrical output is a voltage that is dependent on said rate of deceleration.  
     
     
         3 . The multi-mode fuze of  claim 2  wherein said logic circuit determines that if said voltage is less than 3 volts, a soft target has been impacted.  
     
     
         4 . The multi-mode fuze of  claim 1  wherein said at least one sensor is an accelerometer and said electrical output is a voltage that is dependent on said rate of deceleration.  
     
     
         5 . The multi-mode fuze of  claim 4  wherein said accelerometer is MEMS device.  
     
     
         6 . The multi-mode fuze of  claim 1  wherein said at least one sensor is two sensors, a soft target sensor disposed closer to said target than a hard target sensor.  
     
     
         7 . The multi-mode fuze of  claim 6  wherein said soft target sensor and said hard target sensor are independently selected from the group consisting of piezoelectric crystals and mechanical switches.  
     
     
         8 . The multi-mode fuze of  claim 6  wherein said soft target sensor is actuated when a target is impacted sending a first electrical signal to said logic circuit and said hard target sensor and sends a second electrical signal to said logic circuit only if a hard target is impacted.  
     
     
         9 . The multi-mode fuze of  claim 8  wherein said logic circuit is programmed such that said second electrical signal overrides said first electrical signal.  
     
     
         10 . An explosive projectile, comprising: 
 an aerodynamically shaped metallic casing;    an explosive contained within said metallic casing;    an initiating explosive contacting said explosive;    a multi-mode fuze communicating with said initiating explosive effective to trigger detonation of said explosive either on impact with a hard target or following a delay on impact with a soft target.    
     
     
         11 . The explosive projectile of  claim 10  wherein said multi-mode fuze is disposed forward of said explosive.  
     
     
         12 . The explosive projectile of  claim 10  wherein said multi-mode fuze is disposed rearward of said explosive.  
     
     
         13 . The explosive projectile of  claim 10  wherein said multi-mode fuze includes a soft target sensor that is actuated when a target is impacted sending a first electrical signal to said logic circuit and a hard target sensor that sends a second electrical signal to said logic circuit only if a hard target is impacted wherein said soft target sensor is disposed closer to said target than said hard target sensor, a logic circuit electrically coupled to said at least one sensor effective to discriminate between a soft target and a hard target dependent on said electrical output and a fuze that transmits a detonation signal to said initiating explosive to thereby detonate said explosive.  
     
     
         14 . The explosive projectile of  claim 13  wherein said soft target sensor and said hard target sensor are independently selected from the group consisting of piezoelectric crystals and mechanical switches.  
     
     
         15 . The multi-mode fuze of  claim 8  wherein said logic circuit is programmed such that said second electrical signal overrides said first electrical signal.  
     
     
         16 . The explosive projectile of  claim 10  wherein said multi-mode fuze includes a piezoelectric crystal that has a first output when a soft target is impacted and a second output when a hard target is impacted, a logic circuit electrically coupled to said piezoelectric crystal effective to discriminate between a soft target and a hard target dependent on said electrical output and a fuze that transmits a detonation signal to said initiating explosive to thereby detonate said explosive.  
     
     
         17 . The explosive projectile of  claim 10  wherein said multi-mode fuze includes a MEMS accelerometer that has a first output when a soft target is impacted and a second output when a hard target is impacted, a logic circuit electrically coupled to said MEMS accelerometer effective to discriminate between a soft target and a hard target dependent on said electrical output and a fuze that transmits a detonation signal to said initiating explosive to thereby detonate said explosive.  
     
     
         18 . The explosive projectile of  claim 10  having a shaped charge liner disposed between a nose of said explosive projectile and said explosive.  
     
     
         19 . The explosive projectile of  claim 18  wherein a distance between said nose and said shaped charge liner is about equal to a set-off distance of said shaped charge liner.  
     
     
         20 . The explosive projectile of  claim 13  having a shaped charge liner disposed between a nose of said hard target sensor and said explosive.  
     
     
         21 . The explosive projectile of  claim 20  wherein a distance between said hard target sensor and said shaped charge liner is about equal to a set-off distance of said shaped charge liner.