Medicament Delivery Locking Mechanism Fatigue
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Solution Overview
Problem
Reusable medicament delivery devices face reliability issues due to material fatigue in locking mechanisms, leading to failure in repositioning the plunger rod and maintaining secure locking, which affects the device's operational lifespan and user experience.
Innovation Solution
A medicament delivery device with a locking mechanism that uses a separate resilient member, such as a wire spring or sheet metal spring, to bias the movable locking means into an inactive position, preventing fatigue-related failures and ensuring reliable axial movement and locking of the plunger rod, along with a locking wheel and flexible arms for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the locking member uses its own elastic properties to bias towards the inactive position, then the structure is simpler, but the reliability deteriorates due to material fatigue over time
Solution Approach 1:
A separate resilient member (spring) is introduced as an intermediary element to provide the biasing force on the locking means. This mediator component ensures reliable return to the inactive position without relying on the fatigue-prone locking member's own elastic properties, thereby resolving the contradiction between structural simplicity and long-term reliability
2Device complexity
If the locking means remains in the active position due to fatigue, then the device can be simplified, but the operational lifespan deteriorates
Solution Approach 1:
The separate resilient member provides a cushioning biasing force that compensates for material fatigue before it causes failure. This pre-emptive measure ensures the locking means returns to the inactive position even after prolonged use, extending the device's operational lifespan without requiring complex fatigue compensation mechanisms
3Reliability
If the locking means is made more robust to prevent fatigue, then the reliability improves, but the device complexity increases
Solution Approach 1:
The locking mechanism is segmented into distinct functional components: the locking means, the resilient member, and the locking wheel. This segmentation allows each component to be optimized independently - the locking means can be simple while the separate resilient member provides the necessary reliability, avoiding the need to make the entire locking mechanism overly complex
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
Enhances the device's reliability and user-friendliness by reducing the risk of locking mechanism failure, ensuring consistent performance over time and easy reconfiguration for new medicament containers, with improved locking reliability and reduced wear on components.
Implementation Method 1
A resilient member is arranged to act on the moveable locking means to bias the movable looking means towards the inactive position where the locking means allow the locking wheel to rotate
Data Source
AI summary
The invention relates to a medicament delivery device comprising a locking mechanism (5) for locking a plunger rod (4). The locking mechanism (5) comprises a locking wheel (6) and locking means (7), said locking means (7) being moveable between an active position where the locking means (7) prevent the locking wheel (6) from rotation and an inactive position where the locking means (7) allow the locking wheel (6) to rotate, wherein said plunger rod (4) extends through an opening in the locking wheel (6); and a resilient member (8) arranged at the moveable locking means (7) and being arranged to act on the moveable locking means (7) to displace said movable looking means (7) towards the inactive position where the locking means (7) allow the locking wheel (6) to rotate.