Dosing Lever Cam Design for Consistent Cold-Weather Fuel Delivery
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Solution Overview
Problem
Existing combustion powered fastener driving tools experience inconsistent fuel dispensing due to dosing lever engagement issues, particularly in cold weather, leading to variations in combustion and tool operation.
Innovation Solution
A dosing lever design with beveled portions and flat contact surfaces that prevent engagement with the fuel cell door and ensure smooth interaction with the combustion chamber ring, ensuring consistent and repeatable fuel delivery to the combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional dosing lever is used in cold weather, then the tool can operate, but the dosing lever gets stuck causing inconsistent fuel dispensing
Solution Approach 1:
The dosing lever engagement surface is replaced with a cam surface featuring a curved profile. This cam surface interacts with a corresponding cam follower on the fuel cell door, providing smooth, guided movement that prevents the lever from getting stuck during engagement and disengagement, thereby ensuring consistent fuel dispensing operation
Solution Approach 2:
The geometry of the dosing lever engagement surface is modified to include specific angular parameters (cam profile angles). This parameter change transforms the linear engagement motion into a controlled rotational cam motion, eliminating sticking issues and ensuring reliable operation across varying temperature conditions
2Device complexity
If the dosing lever engages with the fuel cell door, then the mechanism is simpler, but it causes inconsistent fuel doses due to engagement interference
Solution Approach 1:
The dosing lever is designed to engage with the cam surface rather than directly with the fuel cell door. This extraction of the direct engagement path eliminates the interference problem where the dosing lever would catch on the fuel cell door edge, while maintaining the necessary mechanical linkage through the cam-follower interface
Solution Approach 2:
The cam surface acts as an intermediary between the dosing lever and the fuel cell door. Instead of direct contact, the cam surface mediates the engagement process, providing a controlled, stick-free interaction that ensures consistent dosing lever positioning and reliable fuel dispensing
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 solution provides consistent and repeatable fuel doses to the combustion chamber, maintaining tool performance even in extreme cold conditions.
Implementation Method 1
A combustion chamber ring is configured to engage the dosing lever to move the dosing lever between the actuated and non-actuated positions
Implementation Method 2
a fuel cell metering valve of a fuel cell, the fuel cell metering valve configured to dispense a dose of fuel from the fuel cell
Implementation Method 3
a spark generator to deliver a spark and ignite the fuel/air mixture in the combustion chamber
Implementation Method 4
ignite the fuel/air mixture in the combustion chamber to start the fastener driving cycle
Implementation Method 5
high-pressure combustion gases that expand and act on the piston to force the driving assembly to move through the cylinder
Data Source
Figure 1
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Figure 3~4
AI summary
A combustion powered fastener driving tool including a dosing lever that reduces the likelihood of causing inconsistent amounts of fuel to be dispensed by the fuel supply assembly of the tool.