Turbocharged Engine Torque Response via Predicted Load Shortfall
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Solution Overview
Problem
Boosted engines experience reduced fuel economy during transient conditions due to slower torque build-up and interaction with vehicle operator actions, leading to inefficient engine operation and excessive torque production.
Innovation Solution
A method for a turbocharged engine that adjusts intake throttle and exhaust waste-gate valve positions independently of EGR and VCT schedules, and schedules EGR and VCT based on a predicted load shortfall ratio to improve torque response, ensuring sufficient airflow and boost pressure during transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If LP-EGR is introduced to increase throttle inlet pressure during transient conditions, then torque response is improved, but response time increases due to long transport delay through compressor, plumbing, cooler, and intake manifold
Solution Approach 1:
The controller predicts the load shortfall ratio in advance and proactively adjusts the HP-EGR valve and VCT before the actual torque deficit occurs. This preliminary action compensates for the inherent delays in the LP-EGR system, ensuring that sufficient airflow is available when needed without waiting for the delayed LP-EGR response.
Solution Approach 2:
The patent introduces HP-EGR as an intermediary system that operates independently of the delayed LP-EGR pathway. By creating a separate, faster EGR route that bypasses the compressor and long plumbing, the system mediates the torque response issue without being constrained by the LP-EGR transport delay.
2Power
If intake throttle is opened and waste-gate valve is closed to increase boost pressure, then torque demand is met, but fuel economy deteriorates due to slower initial build-up requiring operator over-compensation
Solution Approach 1:
The controller continuously monitors the actual torque output and compares it with the demanded torque, using this feedback to dynamically adjust the HP-EGR valve position and VCT. This closed-loop control ensures that torque is delivered efficiently without excessive build-up delays that would trigger operator over-compensation and subsequent fuel-wasting corrections.
Solution Approach 2:
By predicting the load shortfall ratio in advance, the system proactively adjusts airflow parameters before the torque deficit manifests. This preliminary action prevents the characteristic torque lag that causes operators to over-compensate, thereby avoiding the fuel economy penalties associated with corrective pedal adjustments.
3Measurement precision
If EGR and VCT are coordinated with boost actuators based on predicted load shortfall ratio, then torque profile tracking is improved, but device complexity increases due to independent control of multiple actuators
Solution Approach 1:
The patent merges the control of HP-EGR valve, VCT, and boost actuators into a unified control strategy centered on the predicted load shortfall ratio. Rather than managing these actuators as separate independent systems, they are coordinated through a common predictive framework that simplifies the overall control architecture while maintaining precise torque profile tracking.
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 enhances engine torque response by better tracking the desired torque profile, reducing fuel inefficiencies and unnecessary torque production, and enables a smoother transition from transient to steady-state operation.
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
an exhaust gas recirculation (EGR) system wherein at least a portion of the exhaust gas is recirculated to the engine intake
Data Source
AI summary
Methods and systems are provided for improving engine torque response during transient condition. In one example, a method may include adjusting intake throttle and exhaust waste-gate valve based on the operator torque demand and concurrently, scheduling exhaust gas recirculation (EGR) and variable cam timing (VCT) based on a predicted torque shortfall ratio. The scheduling of EGR and VCT is independent of the actual position of intake throttle and exhaust waste-gate valve.