Dosing Member Spring Restoration for Injection Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional injection devices allow setting of intermediate doses, leading to accidental injection of unintended doses due to the lack of precise control over latching positions and torque requirements, which can result in user error.
Innovation Solution
An injection device with a dosing member that can be rotated to set defined doses, featuring a latching unit with specific latching positions and a spring mechanism to automatically restore the dosing member to intended positions, preventing accidental injection of intermediate doses by ensuring only defined quantities can be ejected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the latching device is made strong to ensure reliable automatic restoration from intermediate positions, then the reliability of dose setting is improved, but the torque required by the user to rotate the operating button increases
Solution Approach 1:
The latching device transitions from a static strong latching mechanism to a dynamic selective latching system. The latching element is designed to engage strongly only at specific latching positions (intended doses) while allowing free rotation at intermediate positions. This dynamic behavior resolves the contradiction by providing strong restoration force only when needed (at latching positions) without increasing torque requirements during normal dose setting rotation.
Solution Approach 2:
The latching force is made non-uniform along the rotation path. The latching element provides strong engagement force only at specific localized positions (latching positions corresponding to intended doses) and minimal resistance at other positions (intermediate positions). This localized application of strong latching force improves reliability for intended doses while maintaining ease of rotation during dose setting.
2Reliability
If the radial latching positions are located close together to enable automatic jumping from intermediate positions, then the reliability of dose setting is improved, but the device complexity increases
Solution Approach 1:
The latching mechanism is segmented into discrete latching positions rather than requiring continuous or densely spaced latching points. The latching element engages at specific segmented positions along the rotation path, allowing reliable automatic restoration without requiring complex densely-spaced latching structures. This segmentation simplifies the device while maintaining reliability.
3Adaptability or versatility
If the dosing member can be set in intermediate positions to allow flexible dose setting, then the adaptability is improved, but the risk of accidental injection of unintended doses increases
Solution Approach 1:
The latching element acts as an intermediary safety mechanism between the user's rotation action and the final dose setting. It allows intermediate positions to be reached (maintaining adaptability) but introduces a selective engagement mechanism that only confirms the dose at intended latching positions. This intermediary latching mechanism prevents accidental injection by ensuring that only latched positions can trigger injection, while still allowing flexible intermediate positioning during the setting process.
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 device ensures accurate and secure setting and ejection of intended doses, preventing accidental injection of intermediate quantities by automatically restoring the dosing member to the next lowest intended position when the user releases the operating element.
Implementation Method 1
a spring configured to act between the dosing member and the housing so as to return the dosing member, when the operator-manipulated element is unactuated, from the intermediate position to the at least one injection position or the zero position
Data Source
AI summary
An injection device includes a housing having a receptacle for a vessel for holding injection fluid; an operator-manipulated element for setting an injection dose; a dosing member rotatable about a longitudinal center axis relative to the housing when setting the injection dose; a feed part; and, a latching unit acting between the feed part and housing. The dosing member has a zero position whereat no dose is set and an injection position whereat an intended dose of injection fluid is set. A spring acts between the dosing member and the housing to return the dosing member from an intermediate position to the injection position or a zero position.