GunClaims
Weekly firearms and ammunition patent grants.
Jan 13, 2026

US12523457 - Shear-pin based inertia igniters with preset no-fire protection for munitions and the like

An inertial igniter including: a base having a first projection; a striker mass rotatably connected to the base, the base having a second projection aligned with the first projection such that the first and second projections impact when rotated; a member having a first portion engaging with a second portion of the striker mass to restrict rotation of the striker mass unless the predetermined acceleration is experienced; a mass movable from a first position where an acceleration is less than the predetermined acceleration and a second position where the acceleration is greater than the predetermined acceleration, the second position permitting the first and second portions to come out of engagement; a spring biasing the movable mass in the first position; and a shear member permitting impact of the first and second projections when the predetermined acceleration is experienced and the movable mass moves to the second position.

The patent describes an inertial igniter designed to activate a thermal battery upon reaching a specific acceleration threshold, utilizing a mechanism that restricts the striker mass’s rotation until the predetermined acceleration is met. This system incorporates a movable mass, spring biasing, and shear members to ensure safety by preventing unintended ignition during lower accelerations.

Claim 1

1 . An inertial igniter for igniting a thermal battery upon a predetermined acceleration, the inertial igniter comprising: a base having a first projection; a striker mass rotatably connected to the base through a rotatable connection, the base having a second projection, the second projection is aligned with the first projection when the striker mass is rotated towards the base such that the first projection impacts the second projection; a member having a first portion, the first portion of the member engaging with a second portion of the striker mass to restrict rotation of the striker mass unless the predetermined acceleration is experienced; a movable mass that is movable from a first position where an acceleration is less than the predetermined acceleration and a second position where the acceleration is greater than the predetermined acceleration, the second position permitting the first and second portions to come out of engagement; a spring for biasing the movable mass in the first position; and a shear member for permitting impact of the first and second projections when the predetermined acceleration is experienced and the movable mass moves to the second position. a base having a first projection; a striker mass rotatably connected to the base through a rotatable connection, the base having a second projection, the second projection is aligned with the first projection when the striker mass is rotated towards the base such that the first projection impacts the second projection; a member having a first portion, the first portion of the member engaging with a second portion of the striker mass to restrict rotation of the striker mass unless the predetermined acceleration is experienced; a movable mass that is movable from a first position where an acceleration is less than the predetermined acceleration and a second position where the acceleration is greater than the predetermined acceleration, the second position permitting the first and second portions to come out of engagement; a spring for biasing the movable mass in the first position; and a shear member for permitting impact of the first and second projections when the predetermined acceleration is experienced and the movable mass moves to the second position.

Google Patents

https://patents.google.com/patent/US12523457

USPTO PDF

https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/12523457