Bidirectional Rolling Diaphragm Dosing Pump for Low-Flow Leak Control
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Solution Overview
Problem
Existing additive dosing pumps face leakage issues at low flow rates due to imperfect sliding seals, leading to stalling and failure in introducing additives, while diaphragm-based pumps are bulkier and less efficient for low flow rates.
Innovation Solution
A hydraulic proportional additive dosing pump using a bidirectional roll diaphragm with a rolling seal between a cylinder and plunger, driven by water flow to introduce a proportional dose of liquid additive, employing a switchable valve arrangement to generate reciprocating motion and minimize leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piston with sliding seal is used to drive the additive pump, then the pump structure is simple and reliable, but leakage occurs around the piston at low water flow rates leading to pump stalling and failure to introduce additive
Solution Approach 1:
The patent employs a flexible diaphragm membrane instead of a rigid piston with sliding seals. The diaphragm is disposed within the cylinder and responds to pressure differentials by flexing to displace the plunger, thereby eliminating the sliding seal leakage problem entirely while maintaining pump reliability
Solution Approach 2:
The patent introduces a fluid coupling mechanism where water pressure acts on a diaphragm that indirectly drives the plunger through pressure transmission rather than direct mechanical contact. This intermediary approach eliminates the need for sliding seals between moving parts while maintaining effective force transmission
2Loss of substance
If a diaphragm is used to generate bidirectional motion in the proportional ADP, then leakage is minimized due to static peripheral seals, but the pump becomes significantly larger and bulkier
Solution Approach 1:
The patent uses a thin flexible diaphragm membrane that flexes under pressure to drive the plunger. This thin-film approach maintains the leakage-free advantage of diaphragms while minimizing the volume required, contrasting with the bulky dish-like diaphragms of prior art
Solution Approach 2:
The patent changes the operational parameters of the diaphragm by utilizing bidirectional pressure differentials across the membrane to generate reciprocating motion. This allows the diaphragm to function dynamically with smaller dimensions compared to unidirectional diaphragm systems that require larger sizes
3Reliability
If a bidirectional roll diaphragm is used to drive the plunger, then leakage is minimized and pump size is reduced, but the valve arrangement complexity increases
Solution Approach 1:
The patent employs automatic valve mechanisms that respond to pressure differentials created by the diaphragm's bidirectional motion. The valves self-regulate flow paths based on instantaneous pressure conditions, eliminating the need for complex external control systems while maintaining reliable seal performance
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 bidirectional roll diaphragm design provides efficient and compact additive delivery at low flow rates by minimizing leakage and maintaining consistent additive introduction, overcoming the limitations of piston and diaphragm-based pumps.
Implementation Method 1
a bidirectional roll diaphragm deployed at least partially in a gap between an internal surface of the cylinder and the outer surface of the plunger, the bidirectional roll diaphragm sealingly interconnected with the cylinder and with the plunger so as to form a rolling seal
Implementation Method 2
driven by a flow of water from an inlet to an outlet to introduce a proportional dose of a liquid additive into the flow of water
Implementation Method 3
applying an inlet pressure above the plunger to power a down-stroke of the plunger, and a second state in which: the flow path from the water inlet to the lower chamber is open; the flow path from the water inlet to the upper chamber is closed; the flow path from the lower chamber to the outlet is closed; and the flow path from the upper chamber to the outlet is open, thereby applying an inlet pressure below the plunger to power an up-stroke of the plunger
Data Source
AI summary
A hydraulic proportional additive dosing pump (ADP) has a plunger associated with an actuator rod and displaceable along a cylinder. A bidirectional roll diaphragm is deployed between an internal surface of the cylinder and an outer surface of the plunger so as to form a rolling seal between upper and lower chambers of the cylinder. An additive pump is driven by motion of the actuator rod. A switchable valve arrangement directs inlet water pressure alternately to the upper chamber and the lower chamber, switching at end of each stroke. The bidirectional roll diaphragm is deployed such that, for at least part of the down-stroke and for at least part of the up-stroke, a majority of an area of the bidirectional roll diaphragm is supported in contact with either the cylinder or the plunger.