Parallel EGR Circuit for Rapid Engine Warm-Up
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Solution Overview
Problem
Cold start conditions in internal combustion engines lead to higher fuel consumption and pollutant emissions due to slow warming of engine components and inadequate activation of exhaust gas treatment systems, as lubricating oil is slow to heat up and exhaust gases are not hot enough to activate catalysts effectively.
Innovation Solution
The powertrain incorporates a third recirculation pipe that connects the exhaust pipe with the intake pipe in parallel with existing heat exchangers, allowing for selective control of exhaust gas flow to quickly heat the engine and lubricating fluid, with no additional heat exchanger in the third pipe, enabling efficient heat transfer between exhaust gases and lubricating fluid, and between lubricating fluid and cooling fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If exhaust gases are recirculated through heat exchangers to cool them, then exhaust gas temperature is reduced for NOx reduction, but the heating of engine and lubricating fluid during cold start is delayed
Solution Approach 1:
The exhaust gas recirculation system is segmented into multiple parallel lines: a first recirculation line with a first heat exchanger for cooling exhaust gases during normal operation, and a second recirculation line with a second heat exchanger for heating lubricating fluid during cold start. This segmentation allows selective operation of different recirculation paths based on engine temperature conditions, resolving the contradiction between cooling needs and heating needs.
Solution Approach 2:
The system dynamically switches between different recirculation configurations based on engine temperature. During cold start, the control unit directs exhaust gases through the second recirculation line to heat the lubricating fluid. Once the engine reaches operating temperature, the system switches to the first recirculation line to cool exhaust gases and reduce NOx emissions. This dynamic adaptation resolves the temperature contradiction.
2Speed
If exhaust gases are recirculated quickly during cold start, then engine heating is accelerated, but exhaust gas treatment systems cannot be activated effectively due to insufficient temperature
Solution Approach 1:
The recirculation system is divided into specialized paths: the second recirculation line is dedicated to heating the lubricating fluid during cold start, while the first recirculation line with its heat exchanger is reserved for when cooling is needed. This segmentation ensures that heating operations do not compromise the temperature requirements for exhaust gas treatment system activation.
Solution Approach 2:
The system maintains continuous monitoring of engine temperature and exhaust gas temperature, continuously adjusting the recirculation strategy. During cold start, exhaust gases are recirculated through the second line to heat lubricating fluid continuously until the engine reaches operating temperature, at which point the system continuously monitors and switches to the first line when cooling is required, ensuring both heating and treatment activation needs are met.
3Adaptability or versatility
If multiple heat exchangers are used in parallel recirculation lines, then selective heating and cooling is enabled, but device complexity increases
Solution Approach 1:
The second heat exchanger in the second recirculation line is designed to serve multiple functions: it can heat the lubricating fluid during cold start and also participate in exhaust gas recirculation during normal operation. This multi-functionality reduces the need for entirely separate systems, thereby limiting the increase in device complexity while maintaining selective heating and cooling capabilities.
Solution Approach 2:
The exhaust gas recirculation system uses the exhaust gases themselves as the heating medium during cold start, eliminating the need for an external heat source. The heat exchangers utilize the thermal energy already present in the exhaust gases to heat the lubricating fluid, making the system self-sufficient and reducing overall system complexity.
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 rapidly heats the engine and lubricating fluid, reducing fuel consumption and pollutant emissions by ensuring the exhaust gas treatment systems are activated sooner, thus improving energy efficiency and emission reduction.
Implementation Method 1
a first heat exchanger for cooling the recirculated exhaust gases
Implementation Method 2
a second heat exchanger between a flow of engine lubrication fluid and the recirculated exhaust gases
Implementation Method 3
the second heat exchanger also allows heat exchange between a cooling heat transfer fluid and the lubricating fluid
Data Source
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AI summary
The invention relates to a motor vehicle powertrain (10) comprising an exhaust gas recirculation circuit (34) which includes: - a first exhaust gas recirculation pipe (36) in which a first heat exchanger (38) for cooling the recirculated exhaust gases is interposed; - a second recirculation pipe (40) in parallel with the first heat exchanger (38) and in which a second heat exchanger (42, 54) is interposed between a flow of engine lubrication fluid and the recirculated exhaust gases; characterized in that the exhaust gas recirculation circuit (34) includes a third recirculation pipe (44) arranged in parallel with the first heat exchanger (38) and in parallel with the second heat exchanger (42, 54). The invention also relates to an associated method of implementation.