Medication Drive Assembly Axial-to-Rotational Motion Conversion
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Solution Overview
Problem
Existing medication delivery devices face challenges in providing simple and precise medication administration, particularly for users without formal medical training, as they often require complex operation and may not ensure accurate dosing.
Innovation Solution
A drive assembly comprising a housing, a drive member, a piston rod, a rotation sleeve, and a biasing member, where the rotation sleeve is axially displaceable and rotatable, transforming mechanical interaction into rotational movement of the piston rod for precise medication delivery, with features like guide tracks and ramps ensuring precise dosing and user-friendly operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a ratchet means with biasing means is used to drive the piston rod, then the medication delivery device can provide automated dosing, but the device complexity increases making it difficult for users without medical training to operate
Solution Approach 1:
The patent extracts the complex ratchet and biasing mechanism from the user-operated portion of the device. Instead of requiring users to manually operate ratchets or springs, the drive member simply pushes the rotation sleeve axially, which automatically engages guide fingers with guide tracks to convert linear motion into precise rotational movement of the piston rod. This separation simplifies user interaction while maintaining automated dosing functionality.
Solution Approach 2:
The rotation sleeve acts as an intermediary component between the simple linear push of the drive member and the complex rotational movement required to drive the piston rod. The rotation sleeve, guided by the guide tracks and engaged by the guide fingers, mediates the transformation of motion types without requiring the user to understand or manipulate the underlying mechanical complexity.
2Extent of automation
If complex ratchet mechanisms are used for medication delivery, then dosing can be automated, but the ease of operation decreases for non-medical users
Solution Approach 1:
The device performs the complex task of converting linear motion to rotational motion automatically through its self-contained guide mechanism. When the user simply pushes the drive member linearly, the guide fingers automatically engage the guide tracks and drive the rotation sleeve, which in turn rotates the piston rod through the threaded engagement. The system serves itself by automatically handling the motion transformation without requiring user knowledge of the internal mechanics.
3Manufacturing precision
If the rotation sleeve is guided axially by guide tracks during rotation, then the precision of medication delivery is improved, but the device complexity increases
Solution Approach 1:
The guide tracks are formed with a curvature that guides the guide fingers through a precise arc as the rotation sleeve moves axially. This curved geometry naturally converts the linear axial movement into the required rotational movement, ensuring precise dosing through the geometric relationship between the track curvature and the thread pitch on the piston rod, without requiring additional complex guiding mechanisms.
4Reliability
If the drive assembly uses multiple moving parts like rotation sleeve and guide fingers, then the reliability of dose delivery is improved, but the ease of manufacture decreases
Solution Approach 1:
The rotation sleeve serves multiple functions simultaneously: it acts as a guide for the guide fingers, a converter of linear to rotational motion, and a driver for the piston rod through threaded engagement. The guide fingers similarly perform multiple roles by engaging the guide tracks to guide the rotation sleeve while also being driven by the drive member's linear motion. This multi-functionality reduces the total number of separate components needed, improving manufacturability while maintaining reliability.
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
The drive assembly enables simple, precise, and accurate medication delivery, reducing the risk of wrongly administered doses by converting mechanical displacement into controlled rotational and linear movements of the piston rod, suitable for users without medical training.
Implementation Method 1
The biased biasing member exerts a force on the rotation sleeve acting in the proximal direction. The force is transformed into a rotational movement of the rotation sleeve with respect to the housing.
Data Source
Figure 1
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Figure 3A~3C
AI summary
A drive assembly suitable for a medication delivery device (101) comprises a housing (110), a drive member, a piston rod, a rotation sleeve, a guide member (130) and a biasing member (160). The rotation sleeve (140) is arranged to be displaced in a distal direction when the drive member (120) is displaced in the distal direction by mechanical interaction of the drive member (120) and the rotation sleeve (140) with the rotation sleeve (140) and the drive member (120) both being guided axially by the at guide member (130). The biasing member (160) exerts a force on the rotation sleeve (140) acting in the proximal direction, said force being transformed into a rotational movement of the rotation sleeve (140). The rotational movement of the rotation sleeve (140) being transformed into a rotational movement of the piston rod (150).