Vehicle Exhaust Air-Circulation System for Cold Start
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Solution Overview
Problem
Vehicle exhaust system catalysts face challenges in achieving optimal heating during engine cold start, leading to inefficient emissions reduction and prolonged engine warm-up times, as existing systems struggle to quickly raise the catalyst temperature above light-off temperatures.
Innovation Solution
An air-circulation system is integrated with a heating element in the exhaust system, circulating heated air from the outlet cone through the engine and back to the intake manifold, ensuring the catalyst is warmed efficiently by energizing the heating element and air-circulation device when the catalyst temperature is below a threshold, and inhibiting engine start until the catalyst reaches the required temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the engine is started immediately during cold start, then the engine can begin operation quickly, but the catalyst temperature remains below light-off temperature leading to inefficient emissions reduction
Solution Approach 1:
The system performs preliminary heating of the catalyst using a heating element and circulates heated air through the exhaust system before the engine starts operating. This preliminary action raises the catalyst temperature above light-off temperature in advance, ensuring emissions are reduced from the moment the engine begins operation, thus resolving the contradiction between quick engine start and effective emissions control.
2Temperature
If a heating element is used to warm the catalyst, then the catalyst temperature increases, but the system complexity increases due to additional components
Solution Approach 1:
The air-circulation system serves multiple functions: it circulates air through the exhaust system to warm the catalyst, and the same circulated air is later used for engine cooling and emissions control. By making the air-circulation device multi-functional, the system reduces overall complexity despite adding the heating element, as one component performs several critical functions throughout the engine operation cycle.
3Productivity
If the air-circulation device is energized to circulate heated air, then the catalyst heating efficiency improves, but the energy consumption increases
Solution Approach 1:
The air-circulation device operates continuously through different phases: first circulating air to the heating element for catalyst warm-up, then redistributing the heated air through the exhaust system to maintain catalyst temperature, and finally directing air for engine cooling. This continuous operation eliminates idle periods where energy would be wasted, maintaining high heating efficiency while optimizing overall energy utilization throughout the engine cycle.
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 reduces emissions and shortens engine warm-up times by ensuring the catalyst is heated quickly, improving engine efficiency and reducing cold-start emissions by circulating heated air across the catalyst and engine components.
Implementation Method 1
energize the heating element... circulating heated air across the heating element, across the catalyst
Implementation Method 2
air-circulation device configured to circulate air from the outlet cone, through the conduit to the intake manifold, through the engine, to the inlet cone
Implementation Method 3
The catalytic converter includes a catalyst configured to convert raw exhaust gases into desired reaction products
Data Source
AI summary
A vehicle includes an engine having an intake manifold and an exhaust manifold. An exhaust system is connected to the exhaust manifold and has an aftertreatment device. The aftertreatment device has a body defining inlet and outlet cones, a heating element, and a catalyst disposed in the body between the cones. An air-circulation system has conduit extending from downstream of the catalyst to the intake manifold and an air-circulation device configured to circulate air from the outlet cone, through the conduit to the intake manifold, through the engine, to the inlet cone, and through the aftertreatment device.