Keyed Cartridge Insertion Mechanism for Tolerance and Thermal Alignment
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Solution Overview
Problem
Existing fluid delivery devices face issues with cartridge insertion due to length tolerance and thermal expansion, leading to compressible gaps and misaligned needle insertion, which affect accurate medicament delivery in hydraulically driven systems.
Innovation Solution
A cartridge insertion mechanism with a keyed feature on the cartridge that mates with corresponding features in the hydraulic drive unit, ensuring proper alignment and minimizing compressible gaps, while compensating for thermal expansion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cartridges are manufactured with standard length tolerances, then manufacturing cost is reduced, but compressible gaps occur during insertion affecting delivery accuracy
Solution Approach 1:
The seal member is designed as a compressible element (e.g., elastomeric material) that dynamically adapts to cartridges of varying lengths. The compressibility allows the seal to maintain contact and sealing function across a range of cartridge lengths, accommodating manufacturing tolerances while preventing harmful fluid communication.
2Manufacturing precision
If the device structure is made rigid to maintain alignment, then alignment precision is improved, but thermal expansion effects cause misalignment
Solution Approach 1:
The seal member's material properties (compliance, durometer) are selected to provide thermal compensation. The elastomeric material expands and contracts with temperature changes, maintaining the sealed relationship between the needle assembly and cartridge septum across varying temperatures, thereby preserving alignment precision.
3Reliability
If compressible gaps are minimized through tight tolerances, then delivery accuracy is improved, but device complexity increases
Solution Approach 1:
The compressible seal member automatically compensates for length variations and maintains sealing without requiring active control mechanisms, sensors, or complex adjustment systems. The elastic deformation of the seal itself provides the corrective action, simplifying the overall device architecture while ensuring accurate fluid delivery.
4Adaptability or versatility
If the seal member is made highly compliant to accommodate length variations, then adaptability is improved, but sealing effectiveness deteriorates
Solution Approach 1:
The seal member exhibits different degrees of compliance in different regions or aspects: highly compliant in the axial direction to accommodate length variations, while maintaining sufficient radial stiffness and structural integrity to ensure effective sealing. This localized differentiation of mechanical properties resolves the contradiction between adaptability and sealing effectiveness.
Data Source
AI summary
A fluid delivery device comprises a drive unit including an actuator and one or more first features and a cartridge filled with a fluid prior to being inserted into the housing. The cartridge having a fluid reservoir sealed at one end by a movable piston and sealed at another end by a pierceable septum. The cartridge includes one or more second features that are configured to align and mate with the one or more first features allowing the cartridge to be inserted into the drive unit. The piston is moveabe by the actuator once the cartridge is inserted into the drive unit.