EGR Drive Pressure Control for Heavy-Duty Vehicle Systems
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Solution Overview
Problem
Heavy-duty vehicle systems equipped with turbocompound and turbocharger units face insufficient drive pressure for exhaust gas recirculation (EGR) at low load and low engine speed, leading to suboptimal fuel consumption and limited system optimization.
Innovation Solution
A method that determines the pressure difference between the exhaust gas manifold and the air intake line downstream the charge air cooler, directing recirculated exhaust gas to either the air intake line or the compressor of the turbocharger unit based on a predetermined threshold, ensuring sufficient EGR levels across all operating points, and optionally bypassing the charge air cooler to maintain high exhaust gas temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a turbocompound unit is equipped along with a fuel optimized high efficiency turbocharger, then fuel efficiency is improved, but drive pressure for EGR becomes insufficient at low load and low engine speed
Solution Approach 1:
A separate EGR drive pressure generator is introduced as an intermediary component to specifically address the EGR drive pressure deficiency. This dedicated pressure generation system works independently from the main turbocharger, providing the necessary pressure differential for EGR flow without interfering with the optimized turbocharger performance that ensures fuel efficiency.
Solution Approach 2:
The function of exhaust gas recirculation is segmented into two independent systems: a main turbocharger unit optimized for fuel efficiency and a separate EGR drive pressure generator optimized for providing sufficient EGR pressure. This segmentation allows each component to be optimized for its specific function without compromise.
2Temperature
If recirculated exhaust gas is directed to the air intake line downstream of the charge air cooler, then EGR cooling is achieved, but EGR drive pressure becomes insufficient at low load operating points
Solution Approach 1:
The EGR drive pressure generator acts as an intermediary pressure source that enables exhaust gas to be directed to the downstream air intake line position. By providing dedicated pressure generation, it overcomes the pressure deficiency at low load conditions, allowing the thermally beneficial downstream positioning to be utilized without sacrificing EGR flow capability.
Solution Approach 2:
The system dynamically adjusts the EGR drive pressure parameter through the dedicated pressure generator to maintain sufficient pressure differential across the EGR valve under varying operating conditions. This parameter control enables consistent EGR functionality regardless of the exhaust gas temperature or main system pressure variations.
3Use of energy by moving object
If EGR level is increased to improve fuel consumption, then fuel efficiency improves, but charge air cooler deterioration accelerates due to reduced exhaust gas temperature
Solution Approach 1:
The EGR drive pressure generator serves as a mediator that decouples the relationship between EGR flow rate and exhaust gas temperature. By providing dedicated pressure generation, it enables high EGR levels to be achieved without necessarily requiring high exhaust gas temperatures, thereby protecting the charge air cooler from thermal deterioration while maintaining fuel efficiency benefits.
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 approach ensures consistent and efficient EGR at all operating points, improving fuel consumption and reducing the deterioration of the charge air cooler by maintaining high exhaust gas temperature, thereby optimizing the vehicle system's performance.
Implementation Method 1
directing the recirculated exhaust gas into a diffuser part of the compressor where the velocity of the air creates a lower static pressure and thereby increases the drive pressure for the exhaust gas
Data Source
AI summary
The invention relates to a method for a vehicle system (100) comprising an internal combustion engine (10) having a turbocharger unit (110) connected thereto, a turbocompound unit (120) arranged to receive exhaust gas flowing from the turbocharger unit (110), and an exhaust gas recirculation system (130). The method comprises controlling the exhaust gas flowing through the exhaust gas recirculation system (130) by determining a pressure difference, and, if the determined pressure difference is above a predetermined threshold value directing the recirculated exhaust gas to an air intake line (160) downstream a charge air cooler (170), and, if the determined pressure difference is not above the predetermined threshold value directing the recirculated exhaust gas to a compressor (114) of the turbocharger unit (110).