Torque Converter Lock Control for Catalyst Cold-Start Heating
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Solution Overview
Problem
Aftertreatment systems in engine exhaust systems face challenges in achieving optimal catalytic converter light-off temperatures, particularly at cold conditions, where catalyst performance is reduced, leading to increased emission levels and longer times to reach effective reaction rates.
Innovation Solution
A transmission system lock is implemented to increase the load on the engine by preventing rotation of the torque converter, thereby enhancing the heating rate of the catalyst. This is controlled by a controller that determines the aftertreatment system's temperature and operational state, delaying ignition timing and shifting the transmission to park or neutral states to accelerate catalyst heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine operates at cold temperatures, then the catalyst has reduced ability to convert target compounds, but increasing temperature increases reaction rate and emission control effectiveness
Solution Approach 1:
The patent applies periodic action by implementing a lock control strategy that activates during specific cold start conditions and deactivates when the catalyst reaches light-off temperature. The controller periodically monitors catalyst temperature and transmission state, engaging the lock only when necessary (Park/Neutral state with cold catalyst) and disengaging when the catalyst warms up or the transmission is shifted out of Park/Neutral, creating a time-based periodic control pattern that optimizes heating while maintaining drivability
Solution Approach 2:
The patent implements parameter changes by modifying the engine load parameter through the lock mechanism. When the lock is engaged, it increases the engine load by preventing torque converter rotation, which in turn increases exhaust gas temperature and heating rate of the catalyst. The controller dynamically adjusts this parameter (lock engagement) based on catalyst temperature and transmission state, transforming the cold start condition into an effective heating scenario without permanent structural changes
2Loss of time
If the lock is engaged to increase engine load and heating rate, then catalyst light-off time is reduced, but engine performance and drivability are compromised
Solution Approach 1:
The patent applies dynamics by making the lock control adaptive and conditional rather than static. The controller continuously monitors transmission state (Park/Neutral vs. other gears) and catalyst temperature, dynamically engaging the lock only when both conditions are favorable (cold catalyst AND Park/Neutral state). This dynamic control allows the system to optimize light-off time when drivability impact is minimal (vehicle stopped) while automatically disengaging when the vehicle needs to move, creating a flexible time-based compromise
Solution Approach 2:
The patent implements preliminary action by proactively engaging the lock during cold starts before the catalyst reaches light-off temperature, specifically when the transmission is in Park or Neutral. This preliminary engagement of the lock during the cold start phase accelerates catalyst heating in advance, reducing light-off time before the vehicle begins moving or the catalyst becomes operational, thereby preparing the emission control system ahead of time
3Temperature
If the transmission is locked in Park or Neutral to enable lock control, then catalyst heating is enhanced, but transmission operational flexibility is reduced
Solution Approach 1:
The patent implements feedback by creating a closed-loop control system that continuously monitors transmission state and catalyst temperature. The controller receives feedback signals from the transmission control module about whether the transmission is in Park or Neutral, and from temperature sensors about catalyst status. Based on this feedback, the controller automatically adjusts lock engagement - engaging only when feedback indicates Park/Neutral state with cold catalyst, and disengaging when feedback shows the vehicle is in Drive/Reverse or catalyst is warm, thereby adapting transmission control to actual operating conditions
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
The solution effectively reduces the catalytic converter light-off time, improving emission control by increasing the heating rate of the aftertreatment system, thereby reducing hydrocarbon, carbon monoxide, and nitrogen oxide emissions during cold starts.
Implementation Method 1
A lock is included in the transmission system to selectively prevent rotation of the torque transfer element to increase a load on the engine by the torque converter
Implementation Method 2
a two-way catalytic converter converts hydrocarbon (HC) and carbon monoxide (CO) to innocuous elements or compounds
Implementation Method 3
a three-way catalytic converter is designed for converting HC, CO and nitrogen oxides
Implementation Method 4
Internal combustion engines convert fuel and air to various compounds while extracting energy to perform intended functions
Data Source
AI summary
An engine consumes fuel and air to generate an exhaust gas stream. An exhaust system channels the exhaust gas stream from the engine to a tailpipe. An aftertreatment system is included in the exhaust system and includes a catalyst. A transmission system is coupled with the engine. The transmission system includes a transmission and a torque converter coupled with the transmission through a shaft. A lock is included in the transmission system to selectively prevent rotation of the shaft to increase a load on the engine by the torque converter.