Apr 29, 2025

US12287186 - Safe-and-arm device

The present invention describes a safe-and-arm device, mechanism or assembly ( 160 ) for a projectile ( 100,102 ) equipped with a second-stage propellant ( 124 ). The second-stage propellant ( 124 ) is ignited after the projectile has been ejected out from a launcher barrel. A lockpin ( 190 ), being urged by a spring ( 194 ), is responsive to ignition of the second-stage propellant; after the lockpin ( 190 ) and spring ( 194 ) sense and respond to the second propulsion, an unbalanced rotor ( 164 ) forming part of the safe-and-arm device or assembly ( 160 ), is released to rotate from a “safe” state to an “armed” state, as the projectile continues traveling along its trajectory to a target. In one embodiment, the projectile is configured with a 40 mm cartridge containing a first propellant ( 122 ). An impact sensor may trigger an electric detonator or a point detonator may trigger a stab detonator to set off explosives disposed in the projectile.

Inventors: Yong Peng Tan, Soo Chew Sie, Siwei Huang
Filing date: 2022-06-29

The patent describes a safe-and-arm device for projectiles featuring a two-stage propulsion system, where the second-stage propellant ignites after the projectile is launched, allowing for a controlled transition from a “safe” to an “armed” state. The mechanism utilizes an unbalanced rotor and a lockpin that responds to acceleration and spin forces, ensuring the projectile is at a safe distance before becoming armed.

Claim 1

A safe-and-arm device or mechanism for a projectile equipped with 2-stage propulsion comprising: an unbalanced rotor that is configured to rotate inside the safe-and-arm device or mechanism, with a rate of rotation of the unbalanced rotor being controlled by a pinion and verge assembly; and a lockpin located on the unbalanced rotor, with the lockpin being disposed in a bore formed parallel to a longitudinal axis of the projectile, and the lockpin is urged by a spring to extend, so that a tip of the lockpin is engaged in a locating hole formed on a cover plate that is disposed over the safe-and-arm device or mechanism; wherein, after the projectile is propelled out of a launcher barrel and the projectile is a safe distance away from the launcher barrel, a second propellant is ignited, and the projectile experiences a second acceleration force or impulse together with spin forces, the lockpin, in response to both the second acceleration and spin forces, retracts and releases the unbalanced rotor to turn, such that after a predetermined elapsed of time, the safe-and-arm device or mechanism is rotated from a “safe” state to an “armed” state, as the projectile continues on its trajectory to a target. an unbalanced rotor that is configured to rotate inside the safe-and-arm device or mechanism, with a rate of rotation of the unbalanced rotor being controlled by a pinion and verge assembly; and a lockpin located on the unbalanced rotor, with the lockpin being disposed in a bore formed parallel to a longitudinal axis of the projectile, and the lockpin is urged by a spring to extend, so that a tip of the lockpin is engaged in a locating hole formed on a cover plate that is disposed over the safe-and-arm device or mechanism; wherein, after the projectile is propelled out of a launcher barrel and the projectile is a safe distance away from the launcher barrel, a second propellant is ignited, and the projectile experiences a second acceleration force or impulse together with spin forces, the lockpin, in response to both the second acceleration and spin forces, retracts and releases the unbalanced rotor to turn, such that after a predetermined elapsed of time, the safe-and-arm device or mechanism is rotated from a “safe” state to an “armed” state, as the projectile continues on its trajectory to a target.

Google Patents

https://patents.google.com/patent/US12287186

USPTO PDF

https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/12287186