HP-EGR Cooler for Engine Coolant Heating
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Solution Overview
Problem
During a cold start, engines experience high friction due to cold engine fluids and heat loss to coolant, leading to reduced thermal efficiency and lower fuel economy.
Innovation Solution
A method involving the operation of a high-pressure exhaust gas recirculation system to heat engine coolant by routing exhaust gas through a cooler, while adjusting engine operating parameters like cam timing and fuel injection to maintain combustion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If HP-EGR is increased during cold start to heat coolant, then fuel economy is improved, but combustion stability deteriorates
Solution Approach 1:
The system dynamically adjusts the HP-EGR valve position and engine operating parameters (cam timing, fuel injection) in real-time during cold start to maintain optimal balance between coolant heating and combustion stability. The control system continuously monitors engine conditions and modifies EGR rates and parameter settings as the engine warms up.
Solution Approach 2:
The system changes multiple engine parameters simultaneously - increasing HP-EGR rates while adjusting cam timing and fuel injection settings - to compensate for the destabilizing effect of cold EGR gases on combustion. These coordinated parameter changes allow the engine to tolerate higher EGR rates for coolant heating without sacrificing combustion stability.
2Temperature
If HP-EGR is used to heat coolant rapidly, then thermal efficiency is improved, but engine component stress increases
Solution Approach 1:
The system initiates coolant heating through HP-EGR immediately after engine start while the engine is still cold. By performing this heating action early in the warm-up period, the system reduces the overall time the engine operates at suboptimal temperatures, thereby reducing cumulative thermal stress on components during the cold start phase.
Solution Approach 2:
The HP-EGR coolant heating operates continuously during the cold start warm-up period, maintaining a steady heat transfer process rather than intermittent heating. This continuous action ensures efficient heat utilization from exhaust gases while avoiding thermal shock through controlled, sustained heating rates.
3Power
If additional components are added for coolant heating, then heating effectiveness is improved, but device complexity increases
Solution Approach 1:
The HP-EGR cooler, which is part of the existing exhaust gas recirculation system, is utilized for dual purposes: its primary function of cooling EGR gases and its secondary function of heating engine coolant during cold start. This multi-functional use eliminates the need for separate heating components while providing effective coolant heating capability.
Solution Approach 2:
The system uses the engine's own exhaust heat, which would otherwise be wasted, to heat the coolant through the HP-EGR cooler. This self-service approach converts a waste resource (exhaust thermal energy) into a useful heating function, eliminating the need for external heating components or additional energy input systems.
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
Improves fuel economy by rapidly increasing coolant temperature and maintaining combustion stability during cold starts without adding extra components, enhancing engine thermal efficiency.
Implementation Method 1
initiating operation of a high-pressure exhaust gas recirculation system (HP-EGR) by opening a HP-EGR valve, the HP-EGR system having a cooler which is part of an engine coolant circuit
Data Source
AI summary
Various systems and method for heating an engine in a vehicle during a cold start are described. In one example, thermal efficiency of the engine is improved by heating engine coolant via a high-pressure exhaust gas recirculation (HP-EGR) system. For example, after light-off of an exhaust catalyst, exhaust gas is routed through the HP-EGR system which includes a HP-EGR cooler. Heat from the exhaust gas is then used to warm the engine coolant via the HP-EGR cooler.