Partial Draining of Liquid Additive Feeding Path
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Solution Overview
Problem
Devices for providing liquid additives, such as urea-water solutions, face issues with freezing and crystalline precipitate formation, which can damage components due to increased pressure and abrasive effects, especially during long standstill times, leading to potential system damage and inaccurate metering.
Innovation Solution
A method involving a feeding path with a peristaltic pump and components susceptible to freezing, where the path is partially drained to prevent liquid additive from being present on freezing-sensitive components, and the liquid additive remains in first portions to minimize evaporation and precipitate formation, using capillary, surface tension, and hydrostatic forces to maintain liquid in first portions while draining second portions, and reversing the pump direction for efficient draining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the device is completely drained to prevent freezing damage, then components susceptible to freezing are protected, but the peristaltic pump and other components are exposed to precipitate formation and abrasive damage
Solution Approach 1:
The feeding path is divided into at least two portions: a first portion where liquid additive remains and a second portion that is drained. This segmentation allows different portions of the system to serve different functions during standstill - the first portion maintains liquid to prevent precipitates while the second portion is drained to prevent freezing damage to temperature-sensitive components.
Solution Approach 2:
Different portions of the feeding path are given different quality states - the first portion maintains liquid additive to protect pump components from precipitates, while the second portion is drained to protect temperature-sensitive components from freezing. This local differentiation of quality resolves the contradiction between preventing freezing and preventing precipitate formation.
2Object-affected harmful factors
If the device is completely drained to prevent freezing, then freezing damage is avoided, but exact metering cannot be performed until the system is completely refilled
Solution Approach 1:
By segmenting the feeding path into drained and non-drained portions, the system enables faster refilling compared to complete draining. Only the second portion needs to be drained and subsequently refilled, while the first portion retains liquid, reducing the overall refilling time and allowing quicker resumption of exact metering.
Solution Approach 2:
The first portion of the feeding path is prepared in advance by maintaining liquid additive in it during standstill periods. This preliminary action ensures that when operation resumes, the pump and feeding system are already primed and ready for immediate exact metering, eliminating the need for complete refilling delays.
3Reliability
If liquid additive remains in the feeding path during standstill, then precipitates may form and damage the peristaltic pump, but draining the path causes freezing damage to temperature-sensitive components
Solution Approach 1:
The feeding path is segmented into a first portion containing the peristaltic pump where liquid additive is retained to prevent precipitate formation, and a second portion with temperature-sensitive components that is drained to prevent freezing damage. This spatial segmentation resolves the contradiction by protecting different components through different strategies.
Solution Approach 2:
Different local regions of the feeding path are assigned different quality states - the first portion near the pump maintains liquid to prevent abrasion and precipitates, while the second portion is drained to eliminate freezing risk. This local quality differentiation allows simultaneous protection of both pump and temperature-sensitive components.
4Reliability
If the feeding path is partially drained with liquid remaining in the first portion, then components are protected from both freezing and precipitate damage, but the system complexity increases
Solution Approach 1:
The feeding path is structurally segmented into distinct portions with different drainage characteristics. This segmentation can be achieved through simple geometric design (e.g., elevated sections, air pockets, or valve positions) rather than complex active control systems, thereby maintaining reliability while minimizing added complexity.
Solution Approach 2:
The system uses passive mechanisms such as capillary forces, surface tension, or hydrostatic pressure to automatically maintain liquid in the first portion while draining the second portion. This self-service approach eliminates the need for complex active control systems, achieving component protection without significant increases in device complexity.
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 method effectively protects components from freezing and precipitate damage, ensures precise metering, and extends the service life of the device by maintaining liquid in first portions and removing it from second portions, reducing the risk of damage and ensuring accurate refilling.
Implementation Method 1
a peristaltic pump, which can be damaged by deposits precipitated from the liquid additive
Implementation Method 2
using capillary, surface tension, and hydrostatic forces to maintain liquid in first portions while draining second portions
Implementation Method 3
using capillary, surface tension, and hydrostatic forces to maintain liquid in first portions while draining second portions
Implementation Method 4
using capillary, surface tension, and hydrostatic forces to maintain liquid in first portions while draining second portions
Data Source
AI summary
A method for operating a device for providing a liquid additive includes feeding the liquid additive along a feeding path. The feeding path has at least one first portion in which a peristaltic pump is disposed. The pump, in particular, has a reversible feeding direction and can be damaged by deposits discharged from the liquid additive. The feeding path also has at least one second portion in which a component susceptible to freezing is disposed. At first liquid additive is fed along the feeding path of the device. Subsequently, the feeding of the liquid additive is stopped. The feeding path is then partially emptied in such a way that liquid additive remains in the at least one first portion of the feeding path while the at least one second portion is emptied. A device for providing a liquid additive is also provided.