Sear Return Delay Mechanism for Select Fire Rifle
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Solution Overview
Problem
The rapid return of the sear to its stop-fire position in firearms, particularly in select fire rifles with op rods having two sear notches, can cause premature engagement with the rearward sear notch, preventing successful semi-automatic firing and leading to undesirable wear between the sear tip and op rod.
Innovation Solution
A sear return delay mechanism that employs a movable mass and a cam plate system, where the sear must work against the movable mass to return to the stop-fire position, providing a controlled delay to avoid premature engagement with the rearward sear notch, and can include magnetic forces or biasing elements to enhance the delay mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sear returns quickly to the stop-fire position, then the firing cycle speed is improved, but the sear tip and op rod experience excessive wear and premature engagement with the rearward sear notch occurs
Solution Approach 1:
The patent introduces a periodic delay action in the sear return mechanism using a cam plate and movable mass. The cam plate rotates periodically during the firing cycle, and the movable mass is displaced during sear return, creating a controlled delay that prevents premature engagement while maintaining overall cycle efficiency.
Solution Approach 2:
The patent introduces an intermediary mechanism (cam plate and movable mass) between the sear and the stop-fire position. This intermediary system controls the sear's return motion, delaying its engagement with the stop-fire position to reduce wear and prevent premature engagement with the rearward sear notch.
2Reliability
If the sear returns quickly to the stop-fire position, then the semi-automatic firing reliability is improved, but the sear engages the rearward sear notch prematurely preventing successful firing
Solution Approach 1:
The cam plate and movable mass create a periodic delay action that timing the sear return to occur at the optimal moment in the firing cycle. This ensures the sear engages the stop-fire position at the correct time, preventing premature engagement with the rearward sear notch while maintaining smooth operation.
Solution Approach 2:
The patent changes the temporal parameter of the sear return by introducing a controlled delay. The cam plate rotation and movable mass displacement modify the timing characteristics of the sear return, transforming it from an immediate action to a delayed action that occurs at the optimal moment in the firing cycle.
3Reliability
If a sear return delay mechanism is added, then wear between sear tip and op rod is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the delay mechanism components (cam plate and movable mass) with the existing trigger assembly structure. The cam plate is integrated into the trigger housing and the movable mass is positioned within the existing sear return path, combining multiple functions into a unified assembly rather than adding separate independent components.
Solution Approach 2:
The cam plate serves multiple functions: it controls the timing of the sear return, transfers motion to the movable mass, and prevents premature engagement with the rearward sear notch. The movable mass both delays the sear return and provides a mechanical stop to control the timing, making each component multi-functional to minimize overall complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sear return delay mechanism effectively prevents the sear from engaging the rearward sear notch too quickly, ensuring successful semi-automatic firing and reducing wear between the sear tip and op rod, thereby improving the functionality of select fire trigger assemblies in firearms.
Implementation Method 1
A sear return delay mechanism is provided that delays the return of the sear tip from a fire position to a stop-fire position
Implementation Method 2
can include magnetic forces or biasing elements to enhance the delay mechanism
Implementation Method 3
can include magnetic forces or biasing elements to enhance the delay mechanism
Data Source
AI summary
A firearm includes a sear with a sear tip, the sear movable between a stop-fire position, wherein a discharge mechanism is held by the sear tip against movement that would result in firing of a round, and a fire position, wherein the discharge mechanism is released by the sear tip to permit movement of the discharge mechanism to fire a round. The firearm includes a sear return delay mechanism delaying the return of the sear tip to the stop-fire position from the fire position.