Electric Supercharger Bypass Valve for Boost Pressure Control
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Solution Overview
Problem
Existing engine systems with staged boosting devices face challenges in controlling boost pressure overshoot, leading to turbo lag and excessive engine torque due to the inability to rapidly decelerate electric superchargers and the resulting delays in reducing boost pressure, which can cause drivability issues.
Innovation Solution
Implementing an electric supercharger bypass valve (ESBV) and wastegate control adjustments in coordination with electric supercharger speed adjustments to rapidly bleed down boost pressure and regulate airflow, allowing for immediate reduction of boost pressure and torque output, while also enabling faster turbocharger spin-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the electric supercharger is operated aggressively to reduce turbo lag, then the transient positive boost pressure is improved, but electric boost overshoot occurs which is difficult to control
Solution Approach 1:
A bypass valve is introduced as an intermediary component that provides an alternative flow path around the electric supercharger. This mediator allows rapid reduction of boost pressure by diverting airflow when the supercharger is disabled, enabling aggressive operation during transient conditions while maintaining control during deceleration.
Solution Approach 2:
The boosting system is segmented into two independent pathways: one through the electric supercharger for rapid transient response, and another bypass pathway for controlled pressure reduction. This segmentation allows each pathway to be optimized for its specific function without interfering with the other.
2Reliability
If the electric supercharger is disabled to leverage natural decay for addressing boost overshoot, then the boost pressure control is improved, but the time to torque increases resulting in boost lag
Solution Approach 1:
The bypass valve acts as a mediator that accelerates the natural decay process. Instead of relying solely on slow friction and air resistance, the bypass valve provides a controlled pathway that rapidly reduces pressure when needed, bridging the gap between aggressive supercharger operation and safe pressure reduction.
Solution Approach 2:
The system dynamically switches between two operational modes: aggressive supercharger operation with bypass valve closed for rapid boost build-up, and controlled decay mode with bypass valve open for safe pressure reduction. This dynamic adaptation allows the system to optimize performance at different stages of the boosting cycle.
3Speed
If the electric supercharger speed is reduced using natural decay including resistive effects of friction and air resistance, then the supercharger deceleration is achieved, but the actual boost pressure continues to overshoot resulting in excessive engine torque output
Solution Approach 1:
The bypass valve serves as a mediator that decouples supercharger speed reduction from boost pressure reduction. By providing an alternative airflow path, it allows the supercharger to slow down naturally while simultaneously managing the boost pressure through controlled diversion of compressed air, preventing pressure overshoot during deceleration.
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 effectively controls boost pressure overshoot, reduces turbo lag, and improves drivability by allowing for more precise and rapid regulation of engine torque, enhancing the engine's response to driver demand without degrading time to torque.
Implementation Method 1
accelerating an upstream compressor with a bypass valve coupled in a bypass across the first compressor closed to provide a flow of compressed air to a piston engine
Implementation Method 2
in response to a boost pressure overshoot, opening the bypass valve
Implementation Method 3
while a downstream compressor spins up
Implementation Method 4
the motor may be disabled enabling the high electric supercharger speeds to be reduced using natural decay including resistive effects of friction and air resistance
Implementation Method 5
the motor may be disabled enabling the high electric supercharger speeds to be reduced using natural decay including resistive effects of friction and air resistance
Data Source
AI summary
Methods and systems are provided for controlling boost pressure in a staged engine system comprising a turbocharger and an upstream electric supercharger. In one example, a method may include coordinating the operation of the electric supercharger and an electric supercharger bypass valve and to open the electric supercharger bypass valve to reduce the extent and duration of electric supercharger overboost.