Cannula Tip Bevel Angle for Fluid Dispenser Leak Prevention
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Solution Overview
Problem
Existing fluid dispenser devices, particularly of the bidose type, suffer from leaks during actuation due to the acute angle of the bevel in the cannula's piercing tip, leading to inconsistent dosing and reproducibility issues.
Innovation Solution
The cannula's piercing tip has a bevel angle between 10° and 80°, with an axial extent less than the stopper's radial wall thickness, ensuring the opening is smaller than the stopper's thickness, preventing leaks and maintaining precision and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bevel angle of the cannula tip is made acute to facilitate piercing of the stopper, then the piercing action is improved, but leakage occurs during actuation
Solution Approach 1:
The patent changes the geometric parameters of the cannula tip by specifying a bevel angle between 10° and 80° (avoiding acute angles) and controlling the axial extent of the opening to be less than the stopper wall thickness. This parameter optimization allows the tip to pierce the stopper effectively while preventing fluid leakage during actuation.
2Ease of operation
If the axial extent of the opening is increased to facilitate stopper piercing, then the piercing capability is improved, but dosing precision deteriorates due to leakage
Solution Approach 1:
The patent optimizes the axial extent parameter of the cannula opening, specifying it should be less than the stopper wall thickness. This precise parameter control ensures the opening is sufficient for piercing while preventing excessive fluid flow that would compromise dosing precision and reproducibility.
3Force
If the bevel angle is made acute to improve piercing, then stopper penetration is enhanced, but fluid leakage increases
Solution Approach 1:
The patent changes the bevel angle parameter from acute to a range of 10°-80°, and controls the axial extent to be less than stopper wall thickness. This parameter modification maintains sufficient penetration force while eliminating the harmful leakage effect that occurs with acute angles.
Data Source
Figure 1
Figure 2~5
AI summary
The invention relates to a device for dispensing a fluid product comprising a body (1) and a dispensing head (2) provided with a dispensing opening (3) and axially movable relative to said body (1) during actuation, said body (1) receiving a vessel (10) containing a fluid product, said vessel (10) comprising a hollow tube (11) having a proximal axial opening (12) closed by a plug (20) suitable for sealingly sliding inside said tube (11) upon actuation, said dispensing head (2) comprising a hollow cylindrical cannula (4) connected on one side to said dispensing opening (3) and provided on the other side with a puncturing tip (5) provided with an opening (6) and intended for puncturing said plug (20), said plug (20) having a radial wall (22) punctured by said cannula (4) during actuation, said opening (6) of said cannula (4) defining a peripheral edge (7) extending around said opening (6) and comprising a distal axial end and a proximal axial end, the axial distance between said distal axial end and said proximal axial end of said peripheral edge (7) defining an axial span of said opening (6), said vessel (10) containing two metered amounts of fluid product dispensed during two consecutive actuations of the device, said axial span of said opening (6) of said puncturing tip (5) being smaller than the axial thickness of said radial wall (22) of said plug (20).