Drug Delivery Drive Assembly Dose Selection Mechanism
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Solution Overview
Problem
Existing drug delivery devices face challenges in providing simple and precise operation for users without medical training, particularly in delivering accurate and predefined doses over short or long-term periods.
Innovation Solution
A drive assembly comprising a housing, a rotation sleeve, and a piston rod, where the rotation sleeve is rotatable relative to the housing, and the piston rod is axially movable, allowing for precise dosing through mechanical cooperation, with features like threads and guide tracks ensuring stability and control, enabling easy transformation of axial force into rotational movement for dose selection and delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotation sleeve is made rotatable relative to the housing for dose selection, then ease of operation is improved, but mechanical stability between the piston rod and rotation sleeve deteriorates
Solution Approach 1:
The drive assembly is segmented into distinct functional components: a rotation sleeve for dose selection, a piston rod for drug delivery, and a drive member connecting them. This segmentation allows each component to perform its specific function independently while maintaining overall system stability through defined mechanical interfaces.
Solution Approach 2:
A drive member acts as an intermediary element between the rotation sleeve and piston rod. This intermediary component translates rotational movement of the sleeve into precise axial movement of the piston rod, ensuring mechanical stability is maintained during the dose delivery process while allowing the rotation sleeve to remain rotatable for ease of operation.
2Productivity
If axial movement of the piston rod is enabled for dose delivery, then productivity is improved, but device complexity increases
Solution Approach 1:
The drive member combines both rotational and axial movement capabilities into a single component. By merging these two types of motion in one element, the design achieves efficient dose delivery without requiring separate mechanisms for each movement type, thereby limiting the increase in device complexity.
Solution Approach 2:
The drive assembly employs dynamic movement where the piston rod transitions from a stationary state during dose selection to an axially movable state during dose delivery. This dynamic approach allows the system to perform multiple functions (dose selection and delivery) using the same components, improving productivity without proportionally increasing device complexity.
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 achieves high mechanical stability and precise dosing with reduced risk of incorrect dosing, enhancing user convenience and accuracy in administering medication.
Implementation Method 1
An axial force exerted on the drive member, for example by a user, is transformed into a rotational movement of the rotation sleeve with respect to the housing
Implementation Method 2
The piston rod is in mechanical cooperation, e.g. in engagement, with the rotation sleeve to be moveable in the distal direction relative to the housing when the rotation sleeve rotates in a first direction
Data Source
Figure 1~2
Figure 3~4
Figure 4A~4B
AI summary
A drive assembly for a drug delivery device (100), comprising a housing (10) with a proximal end (11) and a distal end (12), and a longitudinal axis (A) extending between the proximal end (11) and the distal end (12), a rotation sleeve (40) being rotatable relative to the housing (10), and a piston rod (50) being axially moveable relative to the housing (10). The piston rod (50) is in mechanical cooperation with the rotation sleeve (40) to be rotatable and moveable in the distal direction relative to the housing (10) when the rotation sleeve (40) rotates in a first direction (D1) and to be stationary in axial direction relative to the housing (10) when the rotation sleeve (40) rotates in a second direction (D2) opposite to the first direction (D1).