Fluid Dispensing Head Torsion Return Mechanism
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Solution Overview
Problem
Existing dispensing heads with elastic return means suffer from poor reliability due to intense bending stresses, leading to notch formation and breakage during endurance tests, even after a low number of cycles.
Innovation Solution
A dispensing head with an elastic return element made of plastic material, specifically polyoxymethylene resin, arranged outside the pumping chamber, utilizing a torsion-based return mechanism that engages with a radial projection on the piston, reducing bending stresses and enhancing reliability through a snap-wise coupling system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an elastic element is arranged outside the pumping chamber to simplify assembly, then the assembly time and complexity are reduced, but the element is still subject to intense bending stresses causing poor reliability
Solution Approach 1:
The patent changes the stress type from bending to torsion by modifying the engagement geometry between the elastic element and the radial projection. The element engages tangentially with the projection at a distance from the piston axis, creating a torsional moment arm that reduces bending stresses on the elastic element while maintaining the external arrangement for easy assembly.
2Reliability
If a metal helical spring is used inside the dispensing chamber, then reliable return force is achieved, but the assembly complexity and manufacturing time increase
Solution Approach 1:
The patent extracts the elastic return element from the internal pumping chamber environment and places it outside, engaging with the piston through a radial projection that extends through the enclosure wall. This extraction simplifies assembly by allowing the elastic element to be installed independently of the precision internal components while maintaining reliable return force through the external engagement mechanism.
3Ease of manufacture
If the elastic element is made of plastic material to reduce assembly complexity, then manufacturing simplicity improves, but resistance to bending stresses decreases
Solution Approach 1:
The patent changes the stress parameter from bending to torsion, which plastic materials like polyoxymethylene can withstand better. The torsional engagement with the radial projection creates a loading pattern that exploits the material's torsional strength while minimizing bending moments, allowing plastic material to provide both manufacturing simplicity and adequate stress resistance.
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 solution provides high reliability and resistance to a high number of cycles with minimal bending stress, facilitating easy assembly and adaptability to different dimensions, while maintaining efficient fluid dispensing functionality.
Implementation Method 1
the return element (10) comprises an elastic portion (20) integral with the coupling portion (14) and projecting therefrom along a torsion axis (Z), inclined relative to the dispensing axis (X), preferably perpendicular thereto
Implementation Method 2
the coupling portion (14) of the return element (10) is constrained to abutment (16) of the pumping means so as to prevent at least partly the stiff rotation of the elastic portion (20) about said torsion axis (Z), obtaining a return action on the pumping means from the dispensing configuration to the stand-by configuration
Data Source
Figure 1
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AI summary
The object of the present invention is a head (1) of a fluid dispensing device, provided with elastic return means, outside the pumping chamber, comprising a return element (10) provided with an elastic portion which when the trigger (6) is actuated, is mainly subject to a torsion status. The head (1) exhibits considerably improved reliability.