Piston Pump Draw-Back Mechanism for Drip-Free Viscous Dispensing
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Solution Overview
Problem
Dispensers of viscous fluids like soaps and creams often experience issues with dripping and stringing, leading to obstructions that reduce fluid flow and can result in unsanitary spraying or leakage, as the liquid can harden or form strings at the nozzle outlet.
Innovation Solution
A piston pump dispenser with a reciprocating piston arrangement that, after dispensing fluid, draws back fluid through the outlet to reduce dripping and stringing, featuring a one-way valve mechanism and a piston with inner and outer discs that control fluid flow to prevent backflow during the charging stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional dispenser outlet is used to dispense viscous fluid, then fluid can be dispensed from the nozzle, but liquid remains at the end of the outlet causing dripping and stringing
Solution Approach 1:
The piston pump applies a draw-back stroke that actively pulls fluid back from the outlet after dispensing, preventing the formation of hanging strings and droplets before they can drip. This preliminary anti-action counteracts the gravitational force that causes fluid to hang from the outlet.
Solution Approach 2:
The piston pump operates with periodic reciprocating motion, alternating between forward dispensing strokes and backward draw-back strokes. This periodic action ensures that after each dispensing cycle, the outlet is cleared by drawing back any remaining fluid, preventing accumulation and subsequent dripping.
2Reliability
If liquid remains at the outlet after dispensing, then the outlet appears to be leaking, but the liquid can harden forming obstructions that reduce fluid flow area
Solution Approach 1:
The piston pump performs a draw-back action immediately after each dispensing stroke, clearing the outlet of excess fluid before it has time to harden or form obstructions. This preliminary clearing action prevents future flow restrictions.
Solution Approach 2:
The reciprocating piston pump maintains continuous operation with alternating dispensing and draw-back strokes, ensuring the outlet is consistently cleared throughout the dispensing process. This continuous action prevents interruption of fluid flow and maintains outlet patency.
3Productivity
If a piston pump draws fluid from the reservoir and dispenses it, then fluid can be delivered, but fluid may backflow during the charging stroke
Solution Approach 1:
The pump system is segmented into two separate valve mechanisms: an inlet valve that controls fluid entry from the reservoir during the charging stroke, and an outlet valve that controls fluid exit during the dispensing stroke. This segmentation ensures unidirectional flow and prevents backflow between strokes.
Solution Approach 2:
The one-way valve mechanisms act as intermediaries between the reservoir, piston chamber, and outlet. These valves mediate the fluid flow, allowing it to move in only one direction through each stage, thereby preventing backflow and maintaining stable flow composition throughout the reciprocating cycle.
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 effectively minimizes dripping and stringing by ensuring fluid is drawn back into the reservoir, maintaining a clear nozzle and preventing unsanitary spraying or leakage, enhancing the operational efficiency and user safety of fluid dispensers.
Implementation Method 1
a one-way valve mechanism between the reservoir and the chamber permitting fluid flow through the inner end of said chamber, only from the reservoir to the chamber
Implementation Method 2
a piston-forming element received in the piston chamber-forming member axially slidable inwardly and outwardly therein, said piston-forming element having an axially extending hollow stem
Implementation Method 3
the inner flexing disc elastically deforming away from the chamber wall of the outer chamber portion to permit fluid flow in the outer chamber portion past the inner disc in an outward direction
Implementation Method 4
the tubular member has its outlet opening downwardly and fluid passing through the tubular member is drawn downwardly by the forces of gravity
Data Source
AI summary
A piston pump dispenser having a reciprocating piston pump arrangement which in a dispensing stroke dispenses fluid from an outlet and in a charging stroke draws fluid from a reservoir and also draws back fluid from the outlet.