Trigger Assembly Transfer Bar Segmentation for Bullpup Creep

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Solution Overview

Problem

Bullpup rifles with short configurations often experience unresponsive triggers due to the distance between the trigger and firing mechanism, resulting in creep and tolerance issues from additional parts, leading to unreliable firing.

Innovation Solution

A trigger assembly featuring a transfer bar with a stepped proximal end and a sear that selectively engages the transfer bar, reducing creep and providing a complete reset, while a biasing member and adjustable trigger spring ensure reliable operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a transfer bar is used to connect the trigger to the firing mechanism in bullpup rifles, then the overall length can be reduced, but the trigger becomes unresponsive with creep and movement before firing

Engineering Contradiction:

Improveoverall lengthVSAvoidtrigger responsiveness

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The transfer bar is segmented into two distinct portions: a first portion that engages the trigger and a second portion that engages the firing mechanism. This segmentation allows each portion to be optimized for its specific function, reducing creep and improving trigger responsiveness while maintaining the compact bullpup configuration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The transfer bar acts as an intermediary component between the trigger and the firing mechanism, but its segmented design allows it to minimize unwanted movement. The first portion transfers motion from the trigger while the second portion engages the firing mechanism, reducing the effect of tolerance stack and creep associated with additional connection parts.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If additional parts are added to connect the trigger to the firing mechanism, then the trigger can be positioned for compact configuration, but tolerance stack increases causing creep and unreliable firing

Engineering Contradiction:

Improvecompact configurationVSAvoidtolerance stack

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The transfer bar combines multiple functions into a single component: it connects the trigger to the firing mechanism, provides structural support, and reduces tolerance stack. By merging these functions, the design achieves compact configuration while minimizing the cumulative effect of tolerances from multiple separate parts.

Inventive Principle:

Principle #5Merging (Combining)

3Length of moving object

If the trigger is positioned farther from the firing mechanism, then the overall configuration can be compact, but the trigger pull becomes unresponsive with excessive creep

Engineering Contradiction:

Improvedistance between trigger and firing mechanismVSAvoidtrigger pull responsiveness

Core Design Contradiction:

Length of moving objectVSEase of operation

Solution Approach 1:

The transfer bar's segmented design creates a dynamic system where the first portion can move relative to the second portion. This allows the trigger to have adequate travel distance for a responsive pull while the segmented structure controls the transmission of motion to the firing mechanism, reducing creep and improving responsiveness.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11300377B2Trigger assembly for firearms

Publication Date: 2022.04.12 DESERT LEASING & LICENSING LLC

AI summary

A trigger assembly includes a trigger, a transfer bar having a distal end and a proximal end, the distal end of the transfer bar being coupled to the trigger and the proximal end having a step defined therein; and a sear configured to selectively engage the proximal end of the transfer bar.