Rotatable Needle Cover Locking Against Accidental Retraction
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Solution Overview
Problem
Medicament delivery devices face the risk of accidental activation due to a safety shield moving into the device body upon impact, which can be mitigated by design modifications that compromise user-friendliness, as seen in prior art solutions.
Innovation Solution
An assembly for a medicament delivery device featuring a rotatable delivery member cover with locking structures and a cap that prevents axial movement when fitted, allowing rotation upon cap removal to enable retraction, thereby reducing the risk of accidental activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the delivery member cover is designed with extended stroke length or higher spring constant to prevent accidental activation, then the risk of accidental activation is reduced, but the device becomes less user-friendly
Solution Approach 1:
The cap is fitted to the delivery member cover in advance before use. This preliminary action physically blocks the cover from moving axially, preventing accidental activation during transport or storage. The user simply needs to remove the cap before operation, maintaining ease of use while ensuring safety during non-use periods.
Solution Approach 2:
The cap acts as an intermediary element between the user and the delivery member cover. It provides an additional layer of protection by physically blocking the cover's movement, while the cam surface mechanism serves as an intermediary that allows easy removal of the cap through rotational motion, thus maintaining user-friendliness.
2Reliability
If the delivery member cover is prevented from axial movement by structural modifications, then accidental activation is reduced, but the device complexity increases
Solution Approach 1:
The protection mechanism is segmented into distinct functional components: the cap as a separate removable element, the blocking structure on the delivery member cover, and the cam surface on the body. This segmentation allows each component to perform its specific function independently, simplifying the overall design while maintaining reliability.
Solution Approach 2:
Instead of making the delivery member cover itself complex with built-in prevention mechanisms, the solution inverts the approach by adding a simple external cap that provides the protection. The complexity is minimized in the cover while the cap and its interaction mechanisms provide the necessary safety function.
3Reliability
If the cap is designed to lock the delivery member cover in position, then accidental movement is prevented, but the ease of removal and operation is reduced
Solution Approach 1:
The locking mechanism transitions from a static blocked state to a dynamic release state through rotational motion. The cam surface converts the rotational movement of the cap into axial movement that disengages the blocking structure, allowing easy removal. This dynamic mechanism maintains position stability during storage while enabling simple operation during use.
Solution Approach 2:
The cam surface utilizes a curved geometric profile that naturally guides the cap's removal motion. The curved surface provides a mechanical advantage, allowing the user to easily rotate and remove the cap with minimal force, thus maintaining ease of operation while the engaged position provides stable locking.
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
An assembly for a medicament delivery device, the assembly comprising: a body, a delivery member cover (9) arranged in the body and configured to move axially relative to the body from an extend position relative to the body 5to a retracted position, and wherein the delivery member cover (9) is configured to be rotatable relative to the body, and a cap configured to receive a proximal portion (9a) of the delivery member cover (9) extending from the body when the delivery member cover (9) is in the extended position, and wherein the cap is configured to be removably attached to and 10rotationally locked relative to the body, wherein the delivery member cover (9) has a first locking structure (9c) and the cap has a second locking structure configured to engage with the first locking structure (9c) when the delivery member cover (9) is in the extended position, to prevent rotation of the delivery member cover (9) relative to the cap in a first rotational direction 15and thereby maintain the delivery member cover in a first rotational position relative to the body, wherein the delivery member cover (9) has a first blocking structure (9d) and the body has a second blocking structure configured to engage with the first blocking structure (9d) when the delivery member cover (9) is in the first rotational position to prevent the delivery 20member cover (9) to move axially from the extended position towards the retracted position, wherein one of the first blocking structure (9d) and the second blocking structure has a cam surface configured to cooperate with the other one of the first blocking structure (9d) and the second blocking structure such that when the cap has been removed from the body and the 25delivery member cover (9) is subjected to an axial force directed distally, the delivery member cover (9) is rotated in the first rotational direction, causing the first blocking structure (9d) and the second blocking structure to disengage, enabling the delivery member cover (9) to move axially from the extended position towards the retracted position.