Piston Pump Outlet Valve Timing to Prevent Dispensing Tube Drip
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Solution Overview
Problem
Existing fluid delivery systems, such as automatic soap dispensers, often experience unwanted dripping from the dispensing tube due to the lack of effective mechanisms to manage fluid flow during the dispensing process.
Innovation Solution
A fluid delivery system that utilizes a piston reciprocally movable within a cylinder, with a one-way inlet valve and an outlet valve that is selectively kept open during the initial downstroke to allow fluid to be sucked back into the cylinder, preventing dripping by maintaining back pressure in the dispensing tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pump with inlet and outlet valves is used, then fluid can be dispensed through the dispensing tube, but unwanted dripping occurs from the dispensing tube
Solution Approach 1:
The piston is designed to perform a preliminary action by moving downward to create negative pressure that sucks fluid back into the cylinder before the normal dispensing cycle begins. This preliminary anti-action counteracts the harmful dripping effect by establishing back pressure that prevents fluid from flowing out of the dispensing tube.
Solution Approach 2:
The system dynamically changes the operational sequence by introducing a preliminary downward stroke of the piston before the upward dispensing stroke. This dynamic modification allows the outlet valve to remain closed during the initial phase, creating the necessary back pressure condition, then opens during dispensing to allow fluid flow.
2Reliability
If additional devices or complex components are added to prevent dripping, then dripping can be controlled, but device complexity increases
Solution Approach 1:
The existing piston is made multi-functional by assigning it an additional preliminary downward stroke function beyond its normal dispensing role. This existing component is utilized to create back pressure and prevent dripping, eliminating the need for separate anti-dripping devices and maintaining system simplicity while achieving reliable dripping control.
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
This solution effectively reduces or prevents dripping by using existing components, such as the piston and outlet valve, without requiring additional devices, ensuring efficient and controlled fluid dispensing.
Implementation Method 1
the piston is arranged to selectively contact the outlet valve to maintain it open during the initial portion of its downstroke and to allow it to close for the remainder of the downstroke. Because the piston holds the outlet valve open during the initial portion of its downstroke, liquid is sucked back through the outlet.
Implementation Method 2
liquid is sucked back through the outlet. It is therefore sucked back along the dispensing tube and dripping is prevented or reduced.
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A fluid delivery system comprising a pump arranged to draw fluid, in use, from a reservoir (1) and dispense it through a dispensing tube (4), the pump comprising a cylinder (21) in which a piston (22) is reciprocally movable; an inlet into the cylinder; a one-way inlet valve (17) for controlling flow through the inlet; an outlet from the cylinder and leading to the dispensing tube; and an outlet valve (27) controlling flow through the outlet, wherein the piston is arranged to selectively contact the outlet valve to maintain it open during the initial portion of its downstroke and to allow it to close for the remainder of the downstroke.