Dosing Valve Spring Calibration for Freezing Urea
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Solution Overview
Problem
Dosing valves used in automotive exhaust-gas treatment systems face challenges in withstanding freezing temperatures, particularly when handling urea-water solutions, which can expand and generate high pressures, leading to potential damage and increased costs due to the need for more robust designs.
Innovation Solution
A dosing valve design featuring a cohesive connection between the calibration body and support component within the valve housing, combined with a spring mechanism, allows for reliable operation without permanent deformation under ice pressure, using a combination of press-fit and welded connections to distribute forces and maintain precise spring force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dosing valve components are made more robust to withstand ice pressure, then the reliability under freezing conditions is improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The support component is divided into two distinct parts: a first support portion that contacts the calibration body and a second support portion that extends into the additive reservoir. This segmentation allows each portion to handle specific forces independently, with the first portion maintaining calibration precision and the second portion distributing ice pressure, thereby achieving reliability without requiring the entire component to be overly robust
Solution Approach 2:
The support component acts as an intermediary element between the calibration body and the additive reservoir. It mediates the force transmission from the spring through the calibration body while simultaneously distributing ice pressure from the freezing additive to the valve housing, protecting the calibration body from direct exposure to extreme forces
2Manufacturing precision
If the spring force is precisely calibrated for dosing accuracy, then the dosing precision is improved, but the vulnerability to displacement under ice pressure increases
Solution Approach 1:
The support component merges multiple functions into a single element: it provides precise positioning for spring force calibration, supports the calibration body, and distributes ice pressure. This consolidation ensures that the calibration precision is maintained while simultaneously protecting against displacement through the integrated pressure distribution mechanism
Solution Approach 2:
The support component is pre-configured with a specific geometry where the first support portion extends beyond the calibration body's outer surface. This preliminary structural arrangement ensures that when ice pressure occurs, the force is distributed to areas beyond the calibration body, preventing displacement before it can affect dosing precision
3Volume of moving object
If the valve housing is designed to contain the spring and calibration body, then the compactness is improved, but the vulnerability to damage from freezing additive increases
Solution Approach 1:
The support component serves as a protective intermediary between the freezing additive and the sensitive internal components (spring and calibration body). The second support portion extends into the additive reservoir to distribute ice pressure, while the first support portion shields the calibration body, allowing compact housing design without compromising protection
Solution Approach 2:
The support component exhibits local quality variations: the first support portion has a geometry optimized for precise positioning and force transmission, while the second support portion has a geometry optimized for pressure distribution. This localized functional differentiation allows compact overall design while providing targeted protection where needed
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 prevents permanent displacement or deformation of the dosing valve components under ice pressure, ensuring consistent operation and reducing the need for more expensive, stable designs, while maintaining the valve's functionality and precision.
Implementation Method 1
a spring which exerts a spring force on the valve body and thus holds the valve body in a rest position
Implementation Method 2
The welded connection is preferably produced in the presence of a protective gas in order to keep oxygen away from the weld location during the welding process and ensure particularly high quality of the welded connection
Implementation Method 3
A cohesive connection may for example be a brazed connection or a welded connection
Data Source
AI summary
A metering valve having a valve housing, a channel, a valve body that can be moved in order to open and close the metering valve, and a spring, which applies a spring force to the valve body and thus keeps the valve body in a rest position. The spring is supported on at least one calibration body. The valve body, the spring, and the at least one calibration body are arranged in the channel, and the at least one calibration body is supported by a supporting component fastened in the valve housing by a material-bonding connection. A segment of the supporting component protrudes from the valve housing.