Drug Delivery Drive Mechanism Reset State Decoupling
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Solution Overview
Problem
Existing drug delivery devices lack a mechanism for easy reset and reuse, leading to waste and inefficiency in administering fixed dose therapies.
Innovation Solution
A drive mechanism that can switch between normal operation and reset states, allowing decoupling of the stop, drive, and rotation members, enabling the piston rod to move proximally for cartridge replacement and reinitialization, with a separation member and resilient member facilitating this transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the drive mechanism is designed for single-use with interlocked components, then manufacturing simplicity is improved, but device reusability and adaptability deteriorate
Solution Approach 1:
The drive mechanism transitions from a static interlocked state during normal operation to a dynamic decoupled state during reset. The stop member and drive member can rotate relative to each other during reset, enabling the piston rod to return to its initial position while maintaining manufacturing simplicity through a relatively simple mechanical structure with movable components.
2Reliability
If the stop member and drive member are interlocked during normal operation, then operational reliability is improved, but reset capability and ease of operation deteriorate
Solution Approach 1:
The drive mechanism is segmented into functionally independent components (stop member, drive member, piston rod, resilient member) that can be decoupled during reset. This segmentation allows each component to perform its specific function while enabling easy separation for reset operations, maintaining reliability during normal use and ease of operation during reset.
Solution Approach 2:
The resilient member acts as an intermediary element between the stop member and drive member. It stores energy during normal operation to maintain the interlocked state, and releases this energy during reset to facilitate the decoupling and rotation of components, thereby enabling easy reset capability while maintaining operational reliability.
3Measurement precision
If the drive member is prevented from rotating in the first direction during dose setting, then dosing precision is improved, but reset operation complexity increases
Solution Approach 1:
The rotational constraint on the drive member is dynamic rather than static. During normal dose setting, the stop member prevents rotation in the first direction to ensure dosing precision. During reset, the drive member and stop member can rotate relative to each other, allowing the piston rod to return to its initial position without requiring complex reset mechanisms.
Data Source
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AI summary
A drive mechanism for a drug delivery device which can be switched between a normal operation state and a reset state comprises: - a housing (17, 13) having a proximal end and a distal end, - a rotation member (21) which is adapted to rotate in a first direction (44) and in a second direction (47) with respect to the housing (17, 13), - a drive member (20), wherein in the normal operation state the rotation member (21) is coupled with the drive member (20) so that the drive member (20) follows rotational movement of the rotation member (21) in the second direction (47), - a piston rod (12), wherein in the normal operation state the piston rod (12) is displaced in a distal direction with respect to the housing (17, 13) when the drive member (20) rotates in the second direction (47) with respect to the housing (17, 13), - a stop member (26), wherein in the normal operation state the stop member (26) is coupled with the drive member (20) so that the stop member (26) prevents rotational movement of the drive member (20) with respect to the housing (17, 13) in the first direction, and - a separation member (70) for switching the operation state, the separation member (70) being adapted to move the stop member (26) and the drive member (20) in the distal direction with respect to the housing (17, 13) when the normal operation state is switched to the reset state, thereby decoupling the stop member (26) and the drive member (20) and decoupling the drive member (20) and the rotation member (21).