Vane Position Estimation for Variable Geometry Turbocharger
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Solution Overview
Problem
Existing variable geometry turbocharger systems face challenges in accurately controlling vane position without a sensor, often requiring additional diagnostics and complexity due to sensor degradation, and may not function effectively without a reliable exhaust back pressure sensor.
Innovation Solution
A method that adjusts the vane of the variable geometry turbocharger through a range of positions to calibrate a response parameter, allowing accurate estimation of vane position without a sensor, and uses inferred vane position to eliminate the need for an exhaust back pressure sensor, improving system robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vane position sensor is implemented to measure vane position, then control accuracy of the variable geometry turbocharger is improved, but sensor degradation over time decreases control accuracy and necessitates additional sensor diagnostics which add system complexity
Solution Approach 1:
The patent replaces the mechanical/electrical vane position sensor with an inferential system using mathematical models and exhaust back pressure measurements. The controller estimates vane position by processing exhaust back pressure signals through a transfer function that relates back pressure to vane position, eliminating the need for direct physical sensing of vane position.
Solution Approach 2:
The patent introduces exhaust back pressure as an intermediary measurement to indirectly determine vane position. Instead of directly measuring vane position, the system measures exhaust back pressure and uses this intermediate parameter to infer the vane position through established relationships between back pressure and vane geometry.
2Measurement precision
If exhaust back pressure sensor is used to estimate vane position, then vane position estimation is achieved, but the sensor may not be present or may be of insufficient accuracy to provide accurate position sensor estimation
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors exhaust back pressure and adjusts vane position commands based on the difference between desired and actual back pressure. This closed-loop feedback ensures accurate vane position control even without a direct position sensor, as the system self-corrects based on back pressure measurements.
Solution Approach 2:
The patent replaces the requirement for an exhaust back pressure sensor with an inferential approach, using the existing exhaust back pressure information (available from other system measurements) combined with mathematical models to estimate vane position, eliminating the need for additional sensing hardware.
3Reliability
If additional sensor diagnostics are implemented to detect sensor performance degradation, then sensor reliability is monitored, but system complexity increases considerably
Solution Approach 1:
The patent enables the system to self-diagnose sensor degradation by comparing the inferred vane position (from exhaust back pressure) with the actual vane position (from the position sensor). This self-service diagnostic approach detects sensor drift or degradation without requiring additional diagnostic hardware or complex monitoring systems.
Data Source
AI summary
A method of operation for an engine system having a variable geometry turbocharger with a vane is disclosed. In one example, an EGR valve is closed while vane position is adjusted. The method can reduce vane positioning errors during engine operation.