Dual Throttle Control for Cold Start Hydrocarbon Emission Reduction
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Solution Overview
Problem
Cold start emissions of hydrocarbons from internal combustion engines are high due to inefficient catalyst conversion at low temperatures, leading to increased hydrocarbon release into the atmosphere from hydrocarbon traps before the catalyst reaches light-off temperature.
Innovation Solution
A method involving a controller that adjusts the positions of dual throttles to partially open the throttle with fewer hydrocarbons stored and fully close the throttle with more hydrocarbons, preventing air flow across the hydrocarbon trap during cold starts, ensuring hydrocarbons remain trapped until the catalyst reaches light-off temperature for efficient conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dual throttles are installed to reduce pressure drop and increase engine output power, then engine performance is improved, but hydrocarbon emissions increase during cold start because two paths allow hydrocarbons to migrate from the engine to the atmosphere
Solution Approach 1:
The dual throttle system is segmented into two independent intake passages, each with its own throttle and hydrocarbon trap. This allows selective control of each passage during cold start, enabling one throttle to be fully closed while the other is partially opened, thus preventing hydrocarbon release from the trap with higher hydrocarbon content while maintaining engine operation
Solution Approach 2:
Different throttle positions are applied to different intake passages based on the hydrocarbon content in each trap. The controller selectively closes the throttle associated with the trap containing more hydrocarbons, while keeping the other throttle partially open. This localized control strategy prevents hydrocarbon emissions from specific passages without compromising overall engine performance
2Ease of operation
If hydrocarbons are released from the trap during cold start to maintain engine operation, then engine idle is maintained, but hydrocarbon emissions increase because the catalyst has not reached light-off temperature
Solution Approach 1:
The throttle positions are dynamically adjusted based on real-time conditions including catalyst temperature and hydrocarbon trap content. During cold start, the system transitions from a state where both throttles might be partially open to a state where one throttle is fully closed and the other is partially opened. This dynamic control allows the system to adapt to changing conditions and prevent hydrocarbon emissions when the catalyst is not operational
Solution Approach 2:
The controller uses feedback from sensors monitoring catalyst temperature and hydrocarbon trap content to make real-time adjustments to throttle positions. When the catalyst has not reached light-off temperature and the trap contains high hydrocarbon content, the controller responds by closing the associated throttle, preventing harmful emissions while maintaining proper engine operation through the other passage
3Object-generated harmful factors
If the throttle is fully closed to prevent hydrocarbon release from the trap, then hydrocarbon emissions are reduced, but engine idle cannot be maintained
Solution Approach 1:
By segmenting the intake system into two independent passages with separate throttles, the system can close one throttle to prevent hydrocarbon emissions while keeping the other throttle partially open to maintain engine idle. This segmentation allows simultaneous achievement of emission reduction and engine operation
Solution Approach 2:
The control strategy applies local quality by treating each intake passage differently based on its hydrocarbon trap content. One passage is fully closed to prevent emissions, while the other is kept partially open to maintain engine operation. This localized differential control resolves the contradiction between emission reduction and idle maintenance
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 reduces hydrocarbon emissions by keeping hydrocarbons trapped until the catalyst is operational, minimizing their release into the atmosphere and meeting emissions regulations, especially for high-performance engines.
Implementation Method 1
a first hydrocarbon trap and a second hydrocarbon trap positioned in the first and second intake passages, respectively
Implementation Method 2
due to low catalyst temperature, the hydrocarbons that were once trapped in the hydrocarbon trap may make it to the atmosphere
Implementation Method 3
the hydrocarbons may be released into the engine after the catalyst reaches light-off temperature so that there may be less possibility of the hydrocarbons reaching the atmosphere
Data Source
AI summary
Systems and methods for operating an engine that includes dual throttles are disclosed. In one example, positions of the dual throttles may be adjusted to limit flow of hydrocarbons from a hydrocarbon trap during cold engine starting so that an amount of hydrocarbons that reach atmosphere may be reduced. Each of the dual throttles may be positioned in a separate engine air intake passage.