Diesel Exhaust Fluid Tank Venting System Crystallization Control
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Solution Overview
Problem
Existing diesel exhaust fluid tank venting systems fail to effectively regulate the flow of air and fluid vapor, leading to potential crystallization of diesel exhaust fluid due to exposure to air, and do not adequately manage pressure changes during refilling, which can cause unwanted vacuum conditions.
Innovation Solution
A tank venting control system comprising a fill-limit valve module, a vapor-transfer module with separate fluid-conducting passageways, and a breather-valve module with a semi-permeable membrane, which regulates the flow of vapor and air to prevent crystallization and maintain optimal pressure within the tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple vent system is used, then device complexity is reduced, but the system cannot effectively regulate vapor flow and pressure, leading to fluid crystallization
Solution Approach 1:
The venting system is divided into three distinct functional modules: a fill-limit valve module for level control, a vapor-transfer module for vapor redirection, and a breather-valve module for pressure regulation. This segmentation allows each component to perform its specific function effectively, preventing fluid crystallization while maintaining manageable overall system complexity.
Solution Approach 2:
The vapor-transfer module acts as an intermediary component between the fill-limit valve and the breather-valve. It receives vapor from the fill-limit valve and redirects it to either the filler neck or the breather-valve, mediating the vapor flow to prevent direct exposure of the fluid to atmospheric air that would cause crystallization.
2Device complexity
If vapor is vented directly to atmosphere, then pressure regulation is simplified, but diesel exhaust fluid crystallizes due to air exposure
Solution Approach 1:
The vapor-transfer module serves as an intermediary that controls vapor discharge. It provides a controlled pathway for vapor to exit the tank either through the filler neck or the breather-valve, preventing direct atmospheric air exposure to the diesel exhaust fluid that would cause crystallization, while still allowing pressure regulation.
Solution Approach 2:
The system maintains an inert environment within the tank by preventing atmospheric air from contacting the diesel exhaust fluid. The vapor-transfer module and breather-valve arrangement ensures that vapor can be discharged without allowing outside air to enter and cause fluid crystallization.
3Object-affected harmful factors
If the tank is sealed tightly to prevent air entry, then fluid crystallization is prevented, but vacuum conditions develop during refilling
Solution Approach 1:
The breather-valve module provides localized pressure relief functionality while maintaining overall tank sealing. The semi-permeable membrane in the breather-valve allows pressure equalization during refilling operations, preventing vacuum conditions, while the system overall maintains protection against fluid crystallization through controlled vapor pathways.
Solution Approach 2:
The venting system dynamically adjusts its behavior based on operating conditions. During normal operation, the system maintains sealing to prevent crystallization. During refilling, the breather-valve activates to allow pressure equalization and prevent vacuum conditions. This dynamic response resolves the contradiction between sealing and pressure management.
4Reliability
If multiple separate valves are used for venting and pressure control, then regulation effectiveness is improved, but device complexity increases
Solution Approach 1:
The fill-limit valve module, vapor-transfer module, and breather-valve module are merged into a single integrated venting control unit that mounts through one aperture in the tank. This combining maintains the functional benefits of multiple specialized components while reducing overall device complexity and simplifying installation and maintenance.
Solution Approach 2:
The integrated venting control unit performs multiple functions: level control via the fill-limit valve, vapor redirection through the vapor-transfer module, and pressure regulation via the breather-valve. This multi-functionality allows a single component assembly to replace what would otherwise require multiple separate devices, improving regulation effectiveness without proportionally increasing 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
The system effectively recirculates vapor during refilling, prevents diesel exhaust fluid crystallization, and manages pressure to ensure continuous operation without exposing the fluid to excessive air, thereby maintaining the fluid in a stable liquid state and preventing vacuum development.
Implementation Method 1
a buoyant fill-limit valve included in the fill-limit valve module to float upwardly on the rising fluid
Implementation Method 2
The semi-permeable membrane is configured to provide breathing means for regulating discharge of fluid vapor through the membrane to the atmosphere and also for regulating admission of atmospheric air through the membrane into the interior region of the tank
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An exhaust after-treatment system associated with a diesel engine includes a diesel exhaust fluid storage unit. The storage unit includes a diesel exhaust fluid tank and a vent system coupled to the tank and configured to regulate flow of air into the tank and fluid vapor out of the tank.