Fastener Gun Trigger Arm Roller Mechanism
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Solution Overview
Problem
Existing fastener guns require increased handle forces to drive larger fasteners, which can be difficult for users to exert, especially when initiating handle movement or prior to releasing the power spring, and may necessitate larger handles that not all users can effectively maneuver.
Innovation Solution
A fastener gun design featuring a trigger arm and roller mechanism that allows the power spring to be biased with reduced force requirements by changing the location of the applied force relative to the trigger pivot as the handle moves, using a link and roller system to transfer force efficiently and maintain constant user effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the power spring's force is increased to drive larger fasteners, then the fastener driving capability is improved, but the force required to rotate the handle increases making it difficult for users to operate
Solution Approach 1:
The trigger arm pivots about a trigger pivot point that is offset from the handle pivot axis, creating a dynamic mechanical advantage system. As the handle rotates through its arc, the trigger arm's position relative to the power spring changes, allowing the user to apply force at optimal leverage points throughout the motion range, thereby reducing peak handle effort while maintaining high fastener driving force
Solution Approach 2:
The trigger arm acts as an intermediary mechanism between the handle and the power spring. Instead of directly compressing the power spring, the handle rotates the trigger arm which then lifts the plunger to bias the spring. This intermediary leverages the offset pivot geometry to transform user input force into efficient spring compression with reduced effort
2Ease of operation
If the handle size is increased to reduce handle forces, then the biasing forces are maintained with reduced user effort, but users with smaller hands cannot effectively maneuver the larger handle
Solution Approach 1:
The offset trigger pivot creates a dynamic lever arm that changes in effective length during operation. This allows a compact handle design to provide variable mechanical advantage throughout the rotation arc, achieving low effort operation without requiring an oversized handle that would be difficult to maneuver for users with smaller hands
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
Enables increased fastener driving force without increasing handle size or user effort, accommodating users with varying hand sizes and physical limitations by optimizing force distribution and reducing the required handle force throughout the range of motion.
Implementation Method 1
a power spring for driving a fastener into a workpiece
Implementation Method 2
A roller 60 transfers force applied to the handle 20 to the trigger arm 30
Data Source
AI summary
An example fastener gun includes a housing having a plunger and a power spring for driving a fastener into a workpiece, and a trigger arm pivotally attached to the housing at a trigger pivot. The trigger arm lifts the plunger to bias the power spring when the trigger arm pivots in a first direction. The example fastener gun also includes a handle extending upwardly from the housing and pivotally attached to the housing at a handle pivot, and a roller for pivoting trigger arm in the first direction when the handle moves toward the housing. The roller moves away from the trigger pivot when the handle moves toward the housing.