Injection Device Insertion Sleeve Interference Fit and Transparent Dose Window
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing medical injection devices face challenges in achieving accurate dose setting and dispensing due to manufacturing inaccuracies and lack of clear dosing mechanisms, which affect user precision and contamination risks.
Innovation Solution
The design includes a mechanically strengthened dispensing mechanism with a rotatable display sleeve and an insertion sleeve that fits into the housing part with a precise interference fit, featuring a transparent raised surface section for easier dose reading and a locking device to secure the insertion sleeve, along with seals to prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard fit is used between the insertion sleeve and housing part, then assembly is easier, but manufacturing inaccuracies cannot be compensated and dosing accuracy decreases
Solution Approach 1:
The patent changes the dimensional parameters of the insertion sleeve and housing part to create an interference fit. The outer diameter of the insertion sleeve is made slightly larger than the inner diameter of the housing part, creating a tight fit that compensates for manufacturing inaccuracies and ensures precise dosing while maintaining assembly feasibility through controlled interference dimensions.
Solution Approach 2:
The patent applies local quality by creating a specific interference fit zone at the interface between the insertion sleeve and housing part. The raised surface section on the insertion sleeve and the corresponding recess in the housing part are dimensioned to provide localized interference fitting, which compensates for manufacturing tolerances in this critical area without affecting the entire component assembly process.
2Ease of operation
If the display sleeve is made transparent with a raised surface section, then dose reading becomes easier, but the structure becomes more complex
Solution Approach 1:
The patent applies the color changes principle by making the raised surface section of the display sleeve transparent or translucent. This optical property change allows users to clearly see the dose markings and read the set dose accurately through the transparent portion, improving readability without adding separate optical components.
Solution Approach 2:
The patent merges the display function with the structural component by integrating the raised surface section directly into the display sleeve. The raised surface serves both as a structural element for mechanical engagement and as a transparent window for dose reading, combining multiple functions into a single component to reduce overall device complexity.
3Reliability
If the insertion sleeve is secured with a locking device, then axial position stability is improved, but the mechanism becomes more complex
Solution Approach 1:
The patent applies the inversion principle by designing the locking mechanism to engage automatically when the insertion sleeve is inserted into the housing part. Instead of requiring an active locking action, the mechanism is designed so that the act of insertion itself triggers the locking engagement, reversing the conventional approach where a separate locking action is required.
Solution Approach 2:
The locking device is designed to perform self-service by automatically locking the insertion sleeve in its axial position upon insertion. The locking protrusion and recess engage automatically without requiring additional user actions or external actuation, making the system self-securing and reducing operational complexity.
4Reliability
If seals are added to prevent contamination, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies the flexible shells and thin films principle by using seals (likely rubber or elastomeric materials) to create flexible barriers against contamination. These seals are positioned at critical interfaces to prevent the ingress of contaminants while maintaining the integrity of the internal mechanism, providing reliable protection through simple flexible membrane structures.
Data Source
AI summary
Injection device for dispensing a medicament, comprising: a cartridge module, a dispensing mechanism which is actuated to dispense the injectable preparation, a dose-setting mechanism for setting the dose at which the injectable preparation is dispensed when the dispensing mechanism is actuated, the dose-setting mechanism comprising: a housing part (11) in which at least part of the dispensing mechanism is received, a display sleeve (13) rotatable therein, and an insertion sleeve (15) that can be inserted into the housing part (11), whereinthe insertion sleeve (15) has, on its outer face, a raised surface section (20) that is transparent at least in some areas, andthe housing part (11) has a recess (25) which is open at its distal edge (24) and which receives the insertion sleeve (15) in a rotationally fixed manner from the direction of the open end of the recess (25),and insertion sleeve for an injection device, dose-setting mechanism for an injection device for dispensing a medicament, and method for assembling an injection device.