Dual Stage Turbocharger Control System for Boost Pressure Management
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Solution Overview
Problem
In dual stage turbochargers, the separate control of a variable geometry turbine (VGT) and a bypass valve often results in the bypass valve opening before the VGT is fully open, leading to undesirable boost pressure management.
Innovation Solution
A control system that generates coordinated turbo and bypass control signals based on manifold absolute pressure and desired boost pressure, ensuring the VGT is in a predetermined position before the bypass valve opens, using a control module, VGT module, and bypass valve module to actuate the vanes and valve accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bypass valve and VGT are controlled separately using independent control strategies, then the control system is simpler to implement, but the bypass valve may open before the VGT is fully open causing undesirable boost pressure management
Solution Approach 1:
The patent merges the control of the bypass valve and VGT into a unified control system where the bypass valve control signal is generated based on both the turbo control signal and the VGT control signal. This ensures coordinated operation where the bypass valve only opens after the VGT is fully open, preventing premature bypass that would cause undesirable boost pressure management while maintaining implementation simplicity through integrated control logic.
2Speed
If the bypass valve opens early to respond to increasing engine speed, then the response time is faster, but it causes excessive boost pressure when the VGT is not yet fully open
Solution Approach 1:
The control system waits for the VGT to reach its fully open position (predetermined position) before allowing the bypass valve to open. This preliminary condition ensures that the VGT has completed its transition first, preventing excessive boost pressure from occurring while maintaining fast response when the condition is met.
Solution Approach 2:
The bypass control signal is generated based on feedback from both the turbo control signal (reflecting desired boost pressure) and the VGT control signal (reflecting VGT position). This feedback mechanism ensures the bypass valve responds appropriately only when the VGT is fully open, preventing premature opening that would cause excessive boost pressure while maintaining responsive control.
Data Source
AI summary
A control system for a dual stage turbo includes a control module, a variable geometry turbine (VGT) module, and a bypass valve module. The control module generates a turbo control signal based on an manifold absolute pressure (MAP) and a desired MAP. The VGT module generates a VGT control signal to actuate vanes in a VGT based on the turbo control signal. The bypass valve module generates a bypass control signal based on the turbo control signal and the VGT control signal. The bypass control signal actuates a valve to bypass the VGT.