Diesel Exhaust Fluid Delivery System with Backflow Dosing Module
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Solution Overview
Problem
Diesel engine manufacturers face increased pressure to reduce NOx emissions, leading to higher diesel exhaust fluid (DEF) consumption due to complex powertrain systems and stringent emission requirements, necessitating enhanced DEF delivery capacity and pressure control within diesel exhaust fluid delivery systems.
Innovation Solution
A diesel exhaust fluid delivery system incorporating a backflow dosing module with a pump, dosing valves, a pressure sensor, and an electronic controller that controls the system to manage fluid flow and pressure, allowing DEF to flow back into the storage tank, optimizing pump operation, and regulating valve actuation based on dosing requests to maintain efficient delivery and reduce pressure disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher DEF consumption is used to meet emission requirements, then NOx reduction effectiveness is improved, but delivery system capacity requirements increase
Solution Approach 1:
The delivery system is segmented into multiple dosing valves (first dosing valve, second dosing valve) that can operate independently or in combination. This segmentation allows the system to meet higher DEF consumption requirements by distributing the dosing load across multiple valves, thereby improving NOx reduction effectiveness without overwhelming a single delivery pathway.
Solution Approach 2:
The system dynamically adjusts the operation of dosing valves based on real-time dosing requests and system conditions. The electronic controller selectively activates the first dosing valve, second dosing valve, or both, depending on the required DEF consumption level, enabling the delivery system to adapt its capacity to meet varying emission reduction demands.
2Productivity
If pump speed is increased to meet higher dosing requests, then DEF delivery capacity is improved, but mechanical wear increases
Solution Approach 1:
Instead of continuously operating the pump at high speed, the system uses periodic action by selectively activating dosing valves based on dosing requests. The pump operates only when DEF delivery is needed, and the dosing valves are activated in a periodic manner according to the required dosing amount, reducing overall pump runtime and mechanical wear while maintaining the ability to meet high delivery capacity requirements.
Solution Approach 2:
The dosing valves act as intermediaries between the pump and the exhaust system. By positioning dosing valves in the flow path, the system can regulate DEF delivery without requiring the pump to continuously operate at high speeds. The valves control the timing and amount of DEF dosing, allowing the pump to operate at lower speeds while still achieving the required delivery capacity through precise valve actuation.
3Productivity
If multiple dosing valves are used to increase delivery capacity, then DEF consumption capability is improved, but system complexity increases
Solution Approach 1:
The first dosing valve and second dosing valve are designed with universal functionality, each capable of independently delivering DEF to the exhaust system. Both valves connect to the same fluid storage tank and are controlled by the same electronic controller, allowing either valve or both valves to operate depending on the dosing request. This multi-functionality enables the system to achieve higher DEF consumption capability without proportionally increasing system complexity, as the valves share common infrastructure.
Solution Approach 2:
The system merges the control of multiple dosing valves under a single electronic controller that receives a unified dosing request. The controller intelligently distributes the dosing request between the first dosing valve and second dosing valve, combining their capabilities to meet the total DEF consumption requirement. This merging of control functions simplifies the overall system architecture compared to having independent control systems for each valve.
4Productivity
If pump operates continuously at high speed, then DEF delivery rate is improved, but energy consumption increases
Solution Approach 1:
The pump operates in a periodic manner rather than continuously, activating only when DEF delivery is required based on dosing requests. The electronic controller manages pump operation timing, turning the pump on only during periods when dosing valves need to deliver DEF, and turning it off during periods when no dosing is required. This periodic operation maintains the ability to achieve high DEF delivery rates when needed while significantly reducing overall pump energy consumption compared to continuous high-speed operation.
Data Source
AI summary
A diesel exhaust fluid (DEF) delivery system and method for operating same. The method includes controlling a pump to operate at an idle speed to pressurize a pressure line. The method includes controlling a backflow dosing module (BFDM) valve to open to allow an amount of the DEF to flow into a fluid storage tank through a backflow line. The method includes determining a dosing request, a first dosing actuation request for the first dosing valve and a second dosing actuation request for the second dosing valve based on the dosing request. The method includes, when a sum of the first and second dosing actuation requests is less than 100%, controlling the BFDM valve to close when either of the first and second dosing valves is open; and controlling the BFDM valve to open when the first dosing valve is closed and the second dosing valve is closed.