Proportional Additive Dosing Pump With Bidirectional Roll Sealing
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Solution Overview
Problem
Existing hydraulically-powered additive dosing pumps face issues with leakage at low flow rates due to imperfect sliding seals, leading to pump stalling, while diaphragm-based pumps are bulkier and less efficient for proportional dosing.
Innovation Solution
A hydraulic proportional additive dosing pump using a bidirectional roll diaphragm with a rolling seal between the cylinder and plunger, driven by a switchable valve arrangement to alternately apply pressure for reciprocating motion, minimizing leakage and reducing pump size.
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 at low flow rates causing pump stalling
Solution Approach 1:
The invention extracts and eliminates the sliding seal component by replacing the traditional piston-cylinder arrangement with a diaphragm-based system. The diaphragm is secured to the piston rod and cylinder head, creating sealed chambers without requiring sliding seals, thereby preventing leakage entirely.
Solution Approach 2:
The invention employs a flexible diaphragm as the sealing element instead of rigid piston seals. This thin film component flexes to create sealed chambers on either side of the piston rod, providing effective sealing without the leakage problems associated with sliding seals.
2Loss of substance
If a diaphragm is used to eliminate leakage, then leakage is reduced, but the pump becomes significantly larger and bulkier
Solution Approach 1:
The invention employs a rolling diaphragm that dynamically changes shape during operation. The diaphragm transitions from a relatively flat state to a convoluted state as it rolls over the piston rod, allowing effective sealing with minimal diameter and reducing overall pump size compared to traditional diaphragm designs.
Solution Approach 2:
The rolling diaphragm utilizes the axial dimension by rolling over the piston rod rather than expanding radially. This dimensional approach allows the diaphragm to achieve effective sealing path length without increasing the pump's radial footprint, maintaining compact dimensions.
3Volume of moving object
If a rolling diaphragm is used to reduce pump size, then pump dimensions are reduced, but the diaphragm must roll through large angles causing excessive wear
Solution Approach 1:
The invention optimizes the diaphragm's geometric parameters, specifically its diameter and thickness, to achieve an optimal balance between rolling angle and wear. The diaphragm is designed with specific dimensional ratios that limit the rolling angle to less than 180 degrees while maintaining effective sealing, thereby reducing wear and extending service life.
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 ensures efficient proportional dosing with reduced leakage and pump bulk, maintaining performance at low flow rates without the need for electrical power.
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
the flow path from the water inlet to the upper chamber is open; the flow path from the water inlet to the lower chamber is closed; the flow path from the upper chamber to the outlet is closed; and the flow path from the lower chamber to the outlet is open, thereby applying an inlet pressure above the plunger to power a down-stroke of the plunger
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
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.