Wastegate Valve Position Calibration for Turbocharger Thermal Deformation
Solution Overview
Problem
The accuracy of wastegate valve position sensing decreases due to thermal deformation in high-temperature environments, leading to inaccurate boost control in turbocharged engines.
Innovation Solution
A method is implemented to determine the fully closed position of the wastegate valve by temporarily closing it in a low-lift region, allowing for accurate boost control by mitigating the effects of thermal deformation and ensuring precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the wastegate valve and linkage are exposed to high temperatures in the turbocharger environment, then the turbocharger can function properly to increase engine torque/power output density, but thermal deformation occurs causing elongation or contraction in the valve-actuator linkage and turbine housing deformation, which decreases the accuracy of wastegate valve position sensing
Solution Approach 1:
The system performs preliminary action by temporarily closing the wastegate valve to a fully closed position before normal operation to determine and store the actual fully closed position. This preliminary determination compensates for thermal deformation effects that occur during engine operation, ensuring accurate boost control despite temperature-induced dimensional changes in the linkage and housing.
Solution Approach 2:
The system changes the operational parameter by temporarily moving the wastegate valve to a reference position (fully closed) to calibrate the position sensor. This parameter change allows the controller to learn and compensate for thermal deformation effects on the linkage length and housing geometry, maintaining measurement precision across varying temperature conditions.
2Reliability
If the wastegate valve position sensing accuracy decreases due to thermal deformation, then the system continues to operate in high-temperature environments, but inaccurate boost supply occurs leading to degraded engine performance
Solution Approach 1:
The system implements feedback by continuously monitoring the wastegate valve position sensor and comparing it against the stored reference position. When thermal deformation causes deviation from the expected position, the controller uses the feedback from the temporary full-closure determination to compensate and maintain accurate boost control, preventing productivity degradation while operating reliably in high-temperature environments.
3Measurement precision
If the wastegate valve is temporarily closed to determine the fully closed position, then the accuracy of wastegate control is enhanced, but this requires additional control actions that may affect response time
Solution Approach 1:
The temporary closure to determine full closed position is performed as a preliminary calibration action during low-load conditions or startup, before full power demands arise. This preliminary measurement establishes the reference position once, eliminating the need for repeated time-consuming adjustments during critical acceleration or power-demand scenarios, thus minimizing time loss while maintaining precision.
Solution Approach 2:
The system performs the temporary full-closure determination periodically rather than continuously, typically during low-power conditions or at scheduled intervals. This periodic calibration maintains measurement precision without continuously interrupting normal operation, balancing the need for accuracy with the requirement for rapid response during dynamic driving 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
This approach enhances the accuracy of wastegate control, preventing inaccurate boost supply and maintaining engine performance by periodically determining the fully closed position under varying operating conditions.
Implementation Method 1
thermal deformation may occur, causing, for example, elongation or contraction in the valve-actuator linkage, and turbine housing deformation
Data Source
AI summary
Various methods for determining the fully closed position of a wastegate valve are provided. In one example, a non-closed position command for a wastegate valve in a low-lift region relative to a valve seat is received. Prior to executing the position command, the wastegate valve is only temporarily closed to thereby determine a fully closed position.