Eccentric Diaphragm Pump for SCR Additive Metering
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Solution Overview
Problem
Pumps used for delivering liquid additives in exhaust-gas treatment systems face challenges in maintaining high dosing accuracy over their lifespan and are susceptible to damage from freezing temperatures, as the urea-water solution used can freeze and expand, causing volume expansion issues.
Innovation Solution
A pump design featuring a rotatable eccentric surrounded by a deformable diaphragm with a spring layer, forming a fluid-tight delivery path and seal, which accommodates volume expansion and maintains dosing accuracy by distributing forces uniformly and preventing backflow, while being resistant to aging and freezing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pump is used to deliver liquid additive for exhaust-gas treatment, then the pump can achieve high dosing accuracy, but the pump is susceptible to damage from freezing temperatures causing volume expansion
Solution Approach 1:
The pump employs a flexible membrane that separates the liquid additive chamber from the drive mechanism. This flexible membrane allows the chamber to expand when the liquid freezes, preventing damage to the pump structure while maintaining dosing accuracy through the membrane's ability to return to its original shape after deformation.
Solution Approach 2:
The pump design incorporates a cushioning mechanism that anticipates freezing conditions. The flexible membrane and chamber configuration are designed to accommodate volume expansion before damage can occur, effectively cushioning against the harmful effects of freezing temperatures.
2Productivity
If the pump delivers liquid additive continuously, then high productivity is achieved, but aging of the pump reduces dosing accuracy over time
Solution Approach 1:
The pump employs a self-regulating mechanism where the flexible membrane automatically compensates for wear and aging effects. The membrane's elasticity allows it to maintain consistent sealing and dosing accuracy throughout the pump's service life without requiring external adjustment or maintenance.
Solution Approach 2:
The pump design allows for changes in operational parameters to compensate for aging. The flexible membrane can adapt to gradual changes in the pump's mechanical properties over time, maintaining dosing accuracy by naturally adjusting to wear and structural changes that occur during continuous operation.
3Manufacturing precision
If the pump structure is made rigid to maintain dosing accuracy, then manufacturing precision is improved, but the pump cannot accommodate volume expansion during freezing
Solution Approach 1:
The pump incorporates a flexible membrane that provides both structural integrity for precise dosing and the flexibility to accommodate volume expansion during freezing. The membrane maintains a sealed, precise chamber for liquid delivery while allowing controlled deformation when the liquid expands upon freezing.
Solution Approach 2:
The pump employs composite construction combining rigid components for precise dosing mechanisms with flexible membrane elements for expansion accommodation. This composite approach allows different parts of the pump to have different mechanical properties, simultaneously achieving manufacturing precision and adaptability to freezing conditions.
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 pump achieves high accuracy in dosing and withstands freezing temperatures without damage, maintaining performance throughout its service life with minimal impact from aging, ensuring effective exhaust-gas purification.
Implementation Method 1
Between the eccentric and the deformable diaphragm there is arranged a spring layer by which the eccentric and the deformable diaphragm are braced against one another
Implementation Method 2
In the pump housing there is rotatably arranged an eccentric surrounded by a deformable diaphragm, wherein the deformable diaphragm and the pump housing delimit at least one delivery path
Data Source
AI summary
A pump for conveying a liquid, having a pump housing that has at least one inlet and at least one outlet, an eccentric element being rotatably arranged in said pump housing and surrounded by a deformable membrane, the deformable membrane and pump housing delimiting at least one conveyor path from the at least one inlet to the at least one outlet and forming at least one seal for the conveyor path, and the seal being able to be displaced along the conveyor path by a movement of the eccentric element. Between the eccentric element and the deformable membrane, a spring layer is arranged by the eccentric element and deformable membrane are tensioned relative to one another.