Compression Spring Sleeve Assembly for Drug Delivery Dose Dispensing
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Solution Overview
Problem
Existing pen-type drug delivery devices lack an efficient mechanism for dose setting and dispensing that simplifies the insertion and pre-tensioning of a compression spring, while ensuring easy resetting and minimizing component abrasion.
Innovation Solution
The assembly incorporates a compression spring that is compressed during dose setting, allowing its relaxation to cause both rotational and axial movement of a sleeve member, which drives the dispensing mechanism, with a thrust washer to prevent abrasion and a ratchet mechanism to control unintended rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a compression spring is used for dose setting and dispensing, then the mechanism becomes more complex, but the insertion and pre-tensioning become simpler
Solution Approach 1:
The drive assembly is divided into separate functional modules: the compression spring is inserted as a separate component between bearing surfaces rather than being integrated or torsionally fixed to other parts. This segmentation allows the spring to be independently inserted and pre-tensioned without complex assembly procedures, while maintaining a relatively simple overall mechanism structure.
2Reliability
If the compression spring is torsionally fixed to other parts, then the spring positioning is more secure, but the insertion and resetting become more difficult
Solution Approach 1:
The torsional fixation requirement is extracted and eliminated from the design. The compression spring is positioned between two bearing surfaces without being torsionally fixed to any other components. This extraction allows the spring to be easily inserted and reset while maintaining adequate positioning stability through the bearing surface arrangement, avoiding the complexity of torsional fixation mechanisms.
3Adaptability or versatility
If multiple sleeve members are connected to each other, then the dose setting mechanism is more functional, but the component wear increases
Solution Approach 1:
The compression spring acts as an intermediary element that transmits force between the dose setting mechanism and the dispensing mechanism. By using the spring's elastic deformation to couple these functions, the design reduces direct mechanical connections and friction between multiple sleeve members, thereby minimizing component wear while maintaining full dose setting functionality.
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
This design simplifies the insertion and pre-tensioning of the compression spring, facilitates easy resetting, and reduces component wear, providing a reliable and user-friendly mechanism for dose setting and dispensing.
Implementation Method 1
a compression spring (12), wherein the compression spring (12) is compressed during the setting of a dose of a drug
Implementation Method 2
The compression spring may be an element which may be deformed, in particular compressed, in order to store energy. This energy may be released when the compression spring is allowed to relax.
Data Source
Figure 1
AI summary
An assembly (2) for a drug delivery device (1 ) is provided, the assembly comprising a compression spring (12), wherein the compression spring (12) is compressed during the setting of a dose of a drug. The assembly further comprises a sleeve member (30), wherein the compression spring (12) is in direct contact with the sleeve member (30) and wherein the compression spring (12) and the sleeve member (30) are configured such that a relaxation of the compression spring (12) effects a rotational and an axial movement of the sleeve member (30) in a proximal direction, thereby causing a dispensing of a dose from the drug delivery device (1 ).