Variable Volume Droplet Dispenser for Adhesive Handling
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Solution Overview
Problem
Conventional fluid droplet dispensers require a reservoir of fixed volume, limiting the size and number of droplets that can be dispensed, and struggle with materials like cyanoacrylate adhesives due to sliding seal issues and contact requirements.
Innovation Solution
A droplet dispenser system with a variable chamber volume controlled by dual valving, allowing for adjustable droplet size and number without changing the reservoir, using a reservoir and dual valving arrangement to handle a range of viscosities and surface tensions, including non-contact dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed volume reservoir is used in conventional dispensers, then the reservoir structure is simple, but the droplet volume cannot be adjusted and the number of droplets is limited
Solution Approach 1:
The reservoir is segmented into a main reservoir body and a separate dispense chamber. The dispense chamber has a defined volume that is much smaller than the main reservoir, allowing multiple droplets to be dispensed from a single reservoir fill. This segmentation enables adjustable droplet volume through the dispense chamber design while keeping the main reservoir simple.
Solution Approach 2:
The system employs a movable piston within the dispense chamber that can be actuated to control droplet ejection. The piston creates variable volume changes within the dispense chamber, enabling dynamic control of droplet volume and ejection force without changing the main reservoir structure.
2Reliability
If sliding seal elements are used in conventional adhesive dispensers, then the dispensing mechanism is simple, but the seals are readily bonded by cyanoacrylate adhesives requiring cleaning or replacement
Solution Approach 1:
The invention removes sliding seal elements entirely from the fluid path. Instead of using seals that contact the adhesive, the system uses a piston-based displacement mechanism where the piston moves within a sealed chamber but does not create sliding seals that are exposed to the cyanoacrylate adhesive. This extraction of problematic sealing elements eliminates the bonding issue.
Solution Approach 2:
The system introduces a disposable tip assembly as an intermediary between the piston mechanism and the substrate. The tip can be easily replaced if bonded by adhesive, while the main piston mechanism remains protected. This intermediary isolates the expensive or complex piston mechanism from direct contact with the adhesive.
3Reliability
If the dispense tip is brought into actual contact with the substrate to transfer adhesive, then adhesive transfer is effective, but applications are limited to where direct substrate contact is possible
Solution Approach 1:
The invention replaces direct mechanical contact transfer with a pneumatic/hydraulic ejection system. The piston creates pressure changes that force the adhesive through the dispense tip and onto the substrate without requiring the tip to contact the substrate. This substitution enables non-contact dispensing applications while maintaining effective adhesive transfer.
4Quantity of substance
If a small reservoir is used to achieve small droplet dispensing, then droplet volume is small, but the total number of droplets that can be dispensed is limited
Solution Approach 1:
The system segments the fluid storage into a large main reservoir and a small dispense chamber. The dispense chamber volume is optimized for small droplet formation, while the main reservoir provides large total capacity. The piston reciprocates between these two chambers, transferring fluid in controlled amounts, enabling thousands of small droplets to be dispensed from a single large reservoir fill.
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
Enables precise control over droplet volume, handles difficult-to-dispense materials like cyanoacrylates, and allows for thousands of droplets without reservoir change, suitable for various sectors including industrial and medical applications.
Implementation Method 1
the volume of the chamber may be varied in use to cause fluid to be alternately drawn in to the chamber through the inlet valve then subsequently expelled from the chamber through the outlet valve to dispense a droplet
Data Source
AI summary
A droplet dispenser comprises a chamber (3) with a fluid inlet valve (2) and a fluid outlet valve (4). The chamber (3) is arranged such that the volume of the chamber may be varied in use to cause fluid to be alternately drawn in to the chamber (3) through the inlet valve (2) then subsequently expelled from the chamber through the outlet valve (4) to dispense a droplet. The droplet dispenser is capable of dispensing from an open reservoir and one may change the dispensed drop volume simply and easily. The droplet dispenser can also handle liquids which are normally seen as difficult to dispense, such as cyanoacrylate adhesives.