Electric Supercharger Reverse Rotation for Engine Speed Flare Control
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Solution Overview
Problem
Engine start speed flare-up in staged boosted engine systems leads to higher fuel consumption, NVH issues, and increased component and control costs, as existing solutions like spark timing adjustments and intake manifold volume variations have limitations such as reduced fuel economy and additional costs.
Innovation Solution
Operating an electric supercharger in reverse during engine start to generate intake manifold vacuum, reducing intake pressure and subsequently the engine torque output, thereby minimizing speed flare-up, while utilizing existing engine components for cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If spark timing retard is used to control engine speed at start, then engine speed flare is reduced, but fuel economy deteriorates
Solution Approach 1:
The patent applies reverse rotation of the supercharger compressor during engine start to create intake manifold vacuum, which is the opposite approach of conventional spark timing retard. This inversion principle reduces engine torque and speed flare while maintaining fuel economy by lowering the fuel requirement through reduced cylinder charge, rather than retarding spark timing which directly reduces fuel efficiency.
Solution Approach 2:
The patent changes the intake manifold pressure parameter by using reverse compressor rotation to create vacuum conditions during engine start. This parameter change reduces the cylinder charge requirement, which subsequently reduces the fuel requirement and engine torque, achieving speed control without the fuel economy penalty of spark timing retard.
2Speed
If a dedicated assembly is used to vary intake manifold volume, then engine flare is reduced, but component and control costs increase
Solution Approach 1:
The patent makes the supercharger compressor multi-functional by using it for both its conventional boost function and for generating intake manifold vacuum during engine start. This universality principle eliminates the need for a dedicated assembly to vary intake manifold volume, as the existing compressor serves dual purposes, thereby reducing component and control costs while maintaining engine speed control effectiveness.
Solution Approach 2:
The supercharger compressor serves itself by performing both boost delivery and vacuum generation functions. During engine start, the compressor reverses rotation to create vacuum, and during normal operation, it returns to forward rotation for boost delivery. This self-service approach eliminates the need for separate dedicated assemblies, reducing system complexity and costs.
3Loss of energy
If compressor is spun backwards to lower intake manifold pressure, then fuel consumption is reduced, but device complexity increases
Solution Approach 1:
The patent uses the existing supercharger compressor for dual functions: generating intake manifold vacuum during engine start to reduce fuel consumption, and providing boost during normal operation. This multi-functionality approach reduces fuel consumption without adding significant device complexity, as the same component performs both functions under different operating conditions.
Solution Approach 2:
The patent implements dynamic operation of the supercharger compressor by reversing its rotation direction during engine start and returning to forward rotation during normal operation. This dynamic control allows the system to adapt to different operating conditions, achieving fuel consumption reduction during start while maintaining standard boost function during operation, without requiring permanently complex modifications.
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 engine start quality and fuel economy by reducing engine torque and speed flare, addressing NVH issues and lowering fuel consumption without adding complex components or control systems.
Implementation Method 1
the compressor of an electric supercharger may be selectively operated in a reverse direction during the engine start-up to generate intake manifold vacuum
Implementation Method 2
the lower intake manifold pressure reduces the engine start fuel requirement, producing lowering engine torque, and reducing engine flare
Data Source
AI summary
Methods and systems are provided for engine speed flare control in an engine system having multiple staged charge boosting devices. In one example, during an engine start, an upstream compressor is rotated backwards via an electric motor to reduce the intake manifold pressure. The engine is then fueled based on the lower manifold pressure to reduce torque and engine speed flare until idle engine speed conditions are reached.