Capless Retractable Instrument Valve Assembly Design
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Solution Overview
Problem
Cap-less writing instruments face issues with complexity, high manufacturing costs, and reproducibility due to multiple sub-assemblies and potential seal breaches, leading to premature drying of the writing point.
Innovation Solution
A cap-less retractable writing instrument with a simplified design featuring a barrel, reservoir holder, and a closure assembly with a biasing element, retention ring, and closure arms, which integrates support into the tool holder to reduce assembly complexity and tolerance requirements, ensuring the valve remains secure during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monofilament line connects the writing member to the seal cover, then the seal cover is pulled backward to prevent writing point drying, but the monofilament line is subject to fatigue failure from repeated uses and must be positioned by hand
Solution Approach 1:
The patent removes the monofilament line from the system entirely and replaces it with an integrated valve body that directly connects the writing member to the seal cover through rigid structural elements. This extraction of the problematic flexible connector eliminates fatigue failure while simplifying assembly through hand-free positioning.
Solution Approach 2:
The valve body integrates multiple functions that were previously separate components: the writing member support, the seal cover connection, and the positioning mechanism are merged into a single rigid structure. This consolidation eliminates the need for separate monofilament lines and hand positioning steps.
2Duration of action of stationary object
If ink builds up on the inner surface of the seal cover, then the seal between seal cylinder and seal cover is breached, but this leads to premature drying of the writing point
Solution Approach 1:
The patent introduces a valve body as an intermediary structure between the writing member and seal cover. This rigid intermediary prevents direct contact between ink and the seal cover inner surface, eliminating the ink buildup problem that causes seal breaches while maintaining writing point wetness through proper sealing.
3Ease of manufacture
If the supporting device is movably disposed on the reservoir holder, then assembly is possible, but manufacturing reproducibility is difficult to optimize because the sub-assembly can become dislodged or damaged
Solution Approach 1:
The patent merges the supporting device with the valve body into a single integrated structure. This eliminates the movable connection between supporting device and reservoir holder, preventing dislodgement and damage during assembly while maintaining manufacturing reproducibility through fixed positioning.
Solution Approach 2:
The patent segments the valve body as a separate integrated component that combines support functions, allowing it to be manufactured and assembled as a unified piece rather than as multiple movable sub-assemblies. This segmentation improves reproducibility while maintaining assembly feasibility.
4Ease of operation
If adequate slack is provided in the internal assembly, then movement is allowed, but the reservoir holder can move back through the valve far enough to breach the seal
Solution Approach 1:
The patent removes the excessive slack from the internal assembly by integrating the reservoir holder positioning into the rigid valve body structure. This extraction of unnecessary movement freedom prevents the reservoir holder from moving back far enough to breach the seal while maintaining adequate operational movement through controlled design.
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 design results in a more reproducible and cost-effective manufacturing process with fewer points of failure, preventing premature drying of the writing point and improving the reliability of the cap-less retractable writing instrument.
Implementation Method 1
A biasing element is disposed between the valve and the tool holder, the biasing element biases the valve away from the tool holder
Data Source
AI summary
A retractable instrument in accordance with the disclosure advantageously has a simple construction and fewer pieces or sub-assemblies than known retractable instruments. The retractable instrument includes a barrel that encloses a tool holder. The tool holder has an extension, and a tool extending from the distal end of the extension. A valve selectively covers the tool to protect the tool from environmental conditions. A biasing element is disposed between the valve and the tool holder, the biasing element biases the valve away from the tool holder. A movable closure assembly retains the valve on the extension and selectively allows the lid to open and close. The closure assembly includes a closure ring and a retention ring connected by one or more closure arms. The retention ring is disposed on the tool holder and the retention ring is prevented from sliding off of the tool holder by a retention stop.