Staged Boost Engine Bypass Valve Control for Transient Response
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Solution Overview
Problem
In boosted engine systems with staged charge boosting devices, the electric supercharger bypass valve (ESBV) transitions between open and closed states cause significant delays and valve degradation, affecting transient engine performance and fuel economy.
Innovation Solution
The ESBV is maintained closed during low load conditions when the electric supercharger is not activated, reducing communication and mechanical delays, and the engine controller ensures that fuel efficiency is maintained above a threshold by directing all intake air through the turbocharger compressor, thereby reducing the duty cycle of high current events that degrade the valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the ESBV is opened to bypass the electric supercharger during low load conditions, then fuel economy is improved, but transient boost response is degraded due to communication and mechanical delays
Solution Approach 1:
The bypass valve is maintained in a predetermined position (closed) in advance during low load conditions so that when torque demand increases, the valve is already in the correct position to direct air through the electric supercharger, eliminating transition delays and improving transient boost response
2Productivity
If the ESBV is frequently cycled between open and closed states to optimize performance, then transient performance is improved, but valve durability is degraded
Solution Approach 1:
The valve position is predetermined and maintained during low load conditions, avoiding frequent cycling and high current events that cause degradation, thereby extending valve durability while still enabling improved transient performance when needed
Solution Approach 2:
The patent converts the potential harm of frequent valve cycling into a benefit by using a predetermined valve position strategy that reduces cycling frequency, thereby extending valve life while maintaining the ability to provide transient boost enhancement when torque demand increases
3Stress or pressure
If the ESBV is closed to direct air through the electric supercharger, then transient boost pressure is improved, but fuel economy is degraded due to flow restrictions
Solution Approach 1:
The valve position is dynamically adjusted based on operating conditions: maintained closed during low load conditions to prepare for transient response, and opened during steady-state operation to reduce flow restrictions and improve fuel economy
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 improves transient boost response, reduces valve degradation, and maintains fuel efficiency by minimizing the ESBV's transition delays and high current events, enhancing overall engine performance.
Implementation Method 1
Turbochargers and superchargers compress intake air entering the engine using an intake compressor
Implementation Method 2
an electric supercharger includes a compressor that is electrically driven by a motor
Implementation Method 3
a turbocharger includes a compressor that is mechanically driven by an exhaust turbine
Data Source
AI summary
Methods and systems are provided for improving transient performance in a boosted engine having staged air compression systems. An electric supercharger compressor is staged downstream of a turbocharger compressor in a bypass, airflow diverted from a main intake passage to the bypass via closure of a bypass valve. During selected conditions when the supercharger compressor is not being spun, the bypass valve may be closed to direct air to the engine after flowing through the supercharger in a stand-by mode, thereby enabling a transient increase in torque demand to be rapidly met.