Firearm Trigger Return Spring Fatigue Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Trigger return springs in semiautomatic pistols suffer from premature fatigue failure due to high stress reversals, as their design primarily focuses on stiffness rather than fatigue life.
Innovation Solution
A trigger return spring assembly utilizing a compression spring, which is captured between a shoulder and a retaining surface within a bore, to mitigate fatigue failure and increase the fatigue life by exerting a force that pushes the retaining surface away from the shoulder, facilitating a pivoting motion and return mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If extension or torsion springs are used for trigger return, then the spring can provide the necessary stiffness for trigger operation, but the spring suffers from premature fatigue failure due to high stress reversals
Solution Approach 1:
The patent changes the fundamental operating mode of the spring from extension/torsion to compression. Compression springs experience more favorable stress conditions with fewer reversals compared to extension or torsion springs, thereby improving fatigue life while maintaining the necessary stiffness for trigger operation
Solution Approach 2:
Instead of using the conventional extension or torsion spring arrangement, the patent inverts the approach by using a compression spring. This inversion fundamentally changes the stress cycle characteristics, reducing fatigue damage accumulation while preserving the required mechanical performance
2Reliability
If a compression spring is used to mitigate fatigue failure, then the fatigue life increases, but the device complexity increases due to the plunger and retaining surface mechanism
Solution Approach 1:
The patent combines the spring retention function with existing trigger bar components. The compression spring is captured between the trigger bar and the piston, utilizing existing structural elements to hold the spring, thereby reducing overall device complexity despite the spring type change
Solution Approach 2:
The patent introduces a piston as an intermediary component that serves multiple functions: it transmits the trigger force, provides a mounting surface for the compression spring, and facilitates the conversion of linear piston motion to rotational trigger motion. This intermediary enables the compression spring arrangement while managing the added 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 compression spring assembly effectively increases the fatigue life of trigger return springs by distributing stress and reducing the likelihood of premature failure, enhancing the reliability of the firearm's trigger mechanism.
Implementation Method 1
The compression spring exerts a force pushing the retaining surface away from the shoulder
Data Source
AI summary
A trigger return spring assembly mountable on a frame of a firearm includes a trigger mounted on the frame pivoting about a first axis of rotation. A trigger bar attached to the trigger pivots relative to the trigger about a second axis of rotation fixed on the trigger. A bore extends through the trigger along a third axis oriented transversely to and positioned between the first and second axes of rotation. A plunger extends through the bore and is movable along the third axis. A first end of the plunger is attached to the trigger bar and a second end has a retaining surface oriented transversely to the third axis. A shoulder is positioned within the bore proximate to the trigger bar. A compression spring captured within the bore, between the shoulder and the retaining surface, exerts a force pushing the retaining surface away from the shoulder.