Urea Dosing Arrangement with Return Line for Freezing Prevention

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Solution Overview

Problem

Existing exhaust gas treatment systems for internal combustion engines face challenges in preventing the freezing of reducing agents like urea solutions at low temperatures, particularly in the operating tank during extended engine shutdowns, which requires costly and space-constrained heating solutions.

Innovation Solution

A supply arrangement with a dosing device that includes a return line from the dosing device back to the storage tank, allowing the solution to be emptied from the operating tank during engine shutdown, thereby preventing freezing and eliminating the need for heating devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a heating device is installed in the operating tank to prevent freezing of the reducing agent, then the freezing protection is improved, but the device complexity and installation space requirements increase

Engineering Contradiction:

Improvefreezing protectionVSAvoidheating device provisions

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the reducing agent from the operating tank during shutdown periods by introducing a return line that drains the operating tank back to the storage tank. This removes the harmful substance (reducing agent) from the vulnerable location (operating tank) where it would otherwise freeze, eliminating the need for heating devices while maintaining freezing protection reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system performs preliminary draining of the operating tank before shutdown conditions occur. The return line is configured to automatically drain the operating tank when the engine shuts down, proactively preventing freezing conditions from developing rather than reacting to them with heating equipment

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a heating device is installed in the operating tank to prevent freezing of the reducing agent, then the freezing protection is improved, but the installation space requirements increase

Engineering Contradiction:

Improvefreezing protectionVSAvoidinstallation space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

By extracting the reducing agent from the operating tank through the return line during shutdown periods, the invention eliminates the need for space-consuming heating devices, insulation layers, and associated control components, thereby reducing installation space requirements in the engine compartment

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If the reducing agent is kept in the operating tank during shutdown, then the readiness for immediate dosing is improved, but the freezing risk increases

Engineering Contradiction:

Improvereadiness for dosingVSAvoidfreezing risk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts the state of the operating tank based on engine operation status. During operation, the tank is filled for immediate dosing readiness. During shutdown, the tank is drained to eliminate freezing risk. This dynamic switching between states resolves the contradiction between readiness and freezing protection

Inventive Principle:

Principle #15Dynamics

4Object-affected harmful factors

If the operating tank is emptied during shutdown, then the freezing risk is reduced, but the complexity of the dosing control increases

Engineering Contradiction:

Improvefreezing riskVSAvoiddosing control

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system implements periodic draining of the operating tank synchronized with engine shutdown cycles. The dosing device alternates between dosing mode during operation and draining mode during shutdown, creating a simple periodic control pattern that reduces freezing risk without requiring complex control logic

Inventive Principle:

Principle #19Periodic action

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 solution effectively prevents freezing of the reducing agent, reduces component costs and installation space requirements, and ensures safe and energy-efficient operation by utilizing existing components synergistically, particularly beneficial for large diesel engines.

Implementation Method 1

the dosing arrangement includes a directional valve for directing solution to the injector during a first operating mode in which the engine is operating and, in a second operating mode in which the engine is shut down, directing the solution back to the storage tank

Methodology Applied

Scientific EffectFluid flow direction control:

Data Source

PatentUS9038371B2Arrangement and method for storing a reduction agent and supplying it to an exhaust gas system of an combustion engine and an internal combustion engine including such a system

Publication Date: 2015.05.26 ROLLS ROYCE SOLUTIONS GMBH

AI summary

In a supply arrangement for supplying a solution containing a reducing agent, in particular urea, to an exhaust gas system of an internal combustion engine wherein a supply line extending from a storage tank to an injector which is connected to the exhaust gas system includes an operating tank and a dosing arrangement, a return line extends between the dosing arrangement and the storage tank and the dosing arrangement includes a directional valve for directing solution to the injector during a first operating mode in which the engine is operating and, in a second operating mode in which the engine is shut down, directing the solution back to the storage tank for emptying the operating tank.