EGR Cooler Flow Reversal for Deposit and Condensate Removal
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Solution Overview
Problem
Existing EGR devices face challenges in accurately estimating and removing deposit and condensed water accumulation in the EGR cooler, as cooling efficiency can be affected by refrigerant flow and pressure differences, leading to potential misidentification of deposit accumulation and difficulty in quantifying retained condensed water.
Innovation Solution
An internal combustion engine with an EGR device that includes an EGR cooler, a switching unit, and a control device with deposit and condensed water control units. The control device calculates deposit and condensed water amounts using fuel injection and engine speed parameters, triggering mode switches to remove accumulated substances when thresholds are exceeded, ensuring accurate estimation and timely removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cooling efficiency is used to estimate deposit accumulation in the EGR cooler, then deposit detection is enabled, but false detection occurs when refrigerant flow amount changes
Solution Approach 1:
The patent introduces a switching unit as an intermediary component that enables bidirectional flow through the EGR cooler. This allows the system to alternate between forward and reverse flow modes, using the switching mechanism itself as a mediator to overcome the limitations of unidirectional deposit accumulation and false detection caused by refrigerant flow variations.
Solution Approach 2:
The control device implements periodic switching between first and second modes, where the flow direction through the EGR cooler is alternated at predetermined intervals. This periodic action prevents continuous deposit accumulation in one location and enables regular cleaning cycles, transforming a static detection problem into a dynamic periodic process that maintains detection accuracy.
2Measurement precision
If pressure drop is used to recognize deposit accumulation, then deposit detection is enabled, but erroneous recognition occurs due to pressure difference changes from EGR valve operation
Solution Approach 1:
The control device implements periodic switching between first and second modes, where the flow direction through the EGR cooler is alternated at predetermined intervals. This periodic action prevents continuous deposit accumulation in one location and enables regular cleaning cycles, transforming a static detection problem into a dynamic periodic process that maintains detection accuracy.
Solution Approach 2:
The patent applies inversion by reversing the flow direction through the EGR cooler. Instead of always flowing in one direction, the system periodically reverses the flow, causing deposits to be dislodged and removed during the reverse flow phase. This inversion approach transforms the harmful effect of pressure drops into a beneficial cleaning mechanism.
3Temperature
If EGR gas is cooled by the EGR cooler to improve NOx reduction and fuel efficiency, then cooling efficiency is improved, but deposit and condensed water accumulate in the cooler
Solution Approach 1:
The control device implements periodic switching between first and second modes, where the flow direction through the EGR cooler is alternated at predetermined intervals. This periodic action prevents continuous deposit accumulation in one location and enables regular cleaning cycles, transforming a static detection problem into a dynamic periodic process that maintains detection accuracy.
Solution Approach 2:
The patent converts the harmful effect of condensed water and deposit accumulation into a beneficial cleaning mechanism. By reversing the flow direction during the second mode, the system uses the kinetic energy of the flowing EGR gas to dislodge and remove accumulated deposits and condensed water, transforming what was previously a harmful accumulation problem into a self-cleaning benefit.
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 configuration allows for accurate estimation and timely removal of deposits and condensed water, maintaining EGR cooler efficiency and reducing operational impacts from switching modes, thereby enhancing engine performance and reducing maintenance needs.
Implementation Method 1
an EGR cooler (61) that is provided in an EGR passage (50) through which EGR gas flows and that cools EGR gas
Implementation Method 2
when the EGR gas is cooled, condensed water contained in the EGR gas (exhaust) and oil mist are joined to soot in the EGR gas and thereby generate foreign matters (deposit)
Data Source
AI summary
A deposit amount calculation unit calculates an accumulation amount ΣDp of deposit by using an amount of fuel injection fq and a rotation speed NE as parameters, and when the accumulation amount ΣDp exceeds a first threshold value, then an inlet and an outlet of an EGR cooler are switched. A condensed water calculation unit calculates a retention amount ΣCw of condensed water by using the amount of fuel injection fq and the rotation speed NE as parameters, and when the retention amount ΣCw exceeds a second threshold value, then the inlet and the outlet of the EGR cooler are switched.