Writing Implement Cap Screwing Mechanism With Variable Resistance
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Solution Overview
Problem
Existing writing instruments lack a reliable mechanism to indicate when the cap is approaching its end position and securely held, leading to potential sealing issues and cap loosening due to insufficient friction.
Innovation Solution
A writing instrument design featuring a screwing mechanism with increasing resistance at an intermediate position, utilizing a spring device and support ring to enhance unscrewing resistance and secure cap retention, reducing wear and tear on threaded sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cap is screwed onto the shaft part with standard thread engagement, then the cap can be easily screwed on and off, but the friction generated is insufficient to hold the cap securely in place, allowing it to come loose unintentionally
Solution Approach 1:
The screwing path is divided into two distinct phases: a first phase with low screwing resistance for easy engagement, and a second phase with increased resistance for secure locking. This segmentation allows the cap to be easily operated while ensuring reliable holding at the end position.
Solution Approach 2:
The screwing resistance parameter is changed dynamically during the screwing process. It starts at a low level for easy engagement, then increases at the intermediate position to provide secure holding. This parameter change resolves the contradiction between ease of operation and reliable retention.
2Reliability
If excessive friction is generated by thread engagement to hold the cap securely, then the cap is held firmly in place, but the user may end the screwing-on process too early and not reach the end position
Solution Approach 1:
The screwing process is segmented into two phases with different friction characteristics. The first phase has low friction allowing the user to easily reach the intermediate position, while the second phase has high friction to provide secure holding at the end position.
Solution Approach 2:
The friction force acts periodically - low friction during the first portion of screwing, then high friction during the second portion. This periodic variation in friction ensures both accessibility and secure retention.
3Ease of operation
If the cap is only partially screwed onto the shaft part, then the user experiences less resistance, but no sealing covering takes place and the cap may come loose
Solution Approach 1:
The spring device provides tactile feedback to the user during the screwing process. When the cap reaches the intermediate position, the spring engages and increases resistance, signaling to the user that they should continue screwing to achieve proper sealing and retention.
Solution Approach 2:
The spring device is pre-positioned to engage at the intermediate position, preparing the mechanism in advance to provide increased holding force once the cap reaches that point, ensuring both sealing and retention are achieved.
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
Provides a clear indication for users to screw the cap to the end position, ensuring secure engagement and minimizing unintentional cap loosening, while maintaining consistent thread friction throughout.
Implementation Method 1
spring means (7) acting on the cap (10) in use, which has a spring (7) acting in the axial direction of the shaft part (1), for example in the form of a corrugated spring washer
Implementation Method 2
the friction generated by the thread engagement is not sufficient to hold the cap securely in place
Data Source
Figure 1
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AI summary
The invention relates to a writing implement with a shaft part (1, 2) that holds a stylus (4) and with a cap (10, 12), which can be screwed onto the shaft part in order to cover the stylus from an initial position of engagement up to a final position. A resistance against the screwing on, which is greater than the resistance when screwing on from the initial position of engagement up to an intermediate position acts upon the cap when screwing on the cap from the intermediate position, which is located between the initial position of engagement and the final position, until reaching the final position.