Medication Administration Device Plunger Guide Ribs Eccentricity
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Solution Overview
Problem
The existing medication administration devices face challenges with piston movement stability due to radial eccentricity and rotational issues within the casing, affecting smooth medication administration and signal generation.
Innovation Solution
The device incorporates guide ribs and guide grooves on the inner and outer surfaces of the casing and plunger, respectively, to guide the plunger axially and prevent rotation, thereby maintaining straightness and reducing eccentricity, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the piston diameter is controlled to suppress radial eccentricity, then the axial movement stability is improved, but the manufacturing precision requirements increase and rotation may occur
Solution Approach 1:
The patent introduces guide ribs and guide grooves as intermediary elements between the piston and casing. The guide ribs protruding from the casing inner peripheral surface engage with guide grooves on the piston outer peripheral surface, creating a mechanical guidance system that mediates the interaction between piston and casing, ensuring stable axial movement without requiring extreme manufacturing precision
Solution Approach 2:
The patent transitions from controlling piston stability through one-dimensional diameter control to a multi-dimensional solution using guide ribs extending in the axial direction. The guide ribs create engagement surfaces in multiple dimensions (radial and axial), transforming the stability control mechanism from simple diameter matching to a complex geometric engagement system
2Manufacturing precision
If the piston diameter is highly controlled, then radial eccentricity is suppressed, but circumferential rotation relative to the casing may occur
Solution Approach 1:
The patent employs curved or inclined guide rib surfaces that engage with corresponding guide grooves. The curved geometry of the guide ribs and grooves creates a mechanical constraint that prevents circumferential rotation while accommodating manufacturing tolerances, transforming the interaction from simple cylindrical fitting to geometrically constrained engagement
3Stability of the object's composition
If guide ribs are added to guide the plunger axially, then straightness is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the guidance function with the existing structural elements of the casing and plunger. The guide ribs are integrated into the casing wall and the guide grooves into the plunger surface, combining multiple functions (structural support and axial guidance) into unified components rather than adding separate guidance mechanisms
Solution Approach 2:
The patent uses multiple guide ribs distributed around the circumference of the casing, providing redundant guidance contact points. This excessive action ensures that even with manufacturing variations, at least some guide ribs maintain proper engagement, guaranteeing plunger straightness through multiple contact points rather than relying on a single guidance element
Data Source
AI summary
A medication administration device includes: a casing; a syringe including: a barrel housed in the casing, and a puncture needle in fluid communication with the barrel and configured to administer the medication to a living body; a needle cover having a hollow cylindrical shape, disposed inside the casing, covering a distal end of the syringe, and configured to be displaced toward a proximal end relative to the casing when the needle cover is pressed against a puncture target; a plunger disposed inside the casing and configured to eject the medication through the puncture needle upon movement of a distal end of the plunger inside the barrel; and a cap detachably disposed at a distal end of the needle cover, and configured to be detached before the puncture needle punctures the puncture target.