AIS Throttle Control for Transient Torque Response
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Solution Overview
Problem
Engine systems with low-pressure exhaust gas recirculation (LP-EGR) face challenges in providing quick torque response during transient conditions, leading to noticeable 'dead/spongy pedal' zones and excessive torque increases, which compromise fuel efficiency and driver experience.
Innovation Solution
A method that involves opening the secondary air intake system (AIS) throttle during transient conditions to increase throttle inlet pressure, adjusting variable valve timing to reduce internal EGR trapping, and reducing EGR flow when excessive, to provide just enough torque without overshooting the desired output while maintaining fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If throttling is used to hold torque in reserve for quick pedal response, then vehicle performance is improved, but fuel economy deteriorates due to throttling losses
Solution Approach 1:
The patent segments the throttle control into two independent throttles: a primary engine throttle for main airflow control and a secondary air intake system (AIS) throttle for EGR airflow control. This segmentation allows the primary throttle to remain open (reducing throttling losses) while the secondary throttle provides the necessary torque response by controlling EGR flow, thus resolving the contradiction between quick torque response and fuel economy.
2Loss of energy
If LP-EGR system is used to recirculate exhaust gas, then fuel economy is improved, but torque response deteriorates due to large diluted volume causing torque shortfall
Solution Approach 1:
The patent implements dynamic control of the secondary AIS throttle to adjust EGR flow in real-time based on engine operating conditions. During transient conditions, the secondary throttle opens to increase throttle inlet pressure and provide quick torque response. During steady-state operation, it maintains EGR recirculation for fuel economy. This dynamic adjustment resolves the contradiction between torque response speed and fuel economy.
3Power
If pre-planned actions are triggered to increase torque output, then vehicle performance is improved, but fuel efficiency deteriorates and driver experience worsens due to excessive torque increase
Solution Approach 1:
The patent employs feedback control where the controller continuously monitors throttle inlet pressure, manifold pressure, and engine operating conditions. Based on this feedback, the controller dynamically adjusts the secondary AIS throttle position to provide precisely the right amount of torque increase needed, avoiding excessive torque increases. This feedback mechanism ensures fuel-efficient operation while maintaining good driver experience by preventing torque overshoot.
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 ensures a quick and appropriate torque response during transient conditions without incurring throttling losses, thereby enhancing fuel economy and reducing driver corrections.
Implementation Method 1
a turbine is rotated using energy from an exhaust flow. The turbine drives a compressor which delivers a boosted air charge to the engine intake
Implementation Method 2
The turbine drives a compressor which delivers a boosted air charge to the engine intake
Data Source
AI summary
A method and system for providing a suitable engine torque response during a transient condition is presented. In one example, when a desired inlet manifold pressure is greater than a throttle inlet pressure of a first throttle, a second throttle positioned upstream from the first throttle is opened to increase the throttle inlet pressure. The method may provide an appropriate torque response while minimizing impact on fuel economy.