eTurbine EGR Air Depletion for Lower Cold-Start Emissions
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Solution Overview
Problem
Existing solutions for reducing cold start emissions and noise vibration and harshness (NVH) in internal combustion engines are expensive and inefficient, particularly due to excessive airflow during cold starts when the catalyst has not reached operating temperature.
Innovation Solution
An engine system incorporating an electric turbine (eTurbine) and high-pressure exhaust gas recirculation (EGR) circuit, controlled by a controller, which depletes manifold air before engine start by drawing air out through the EGR circuit using the eTurbine, monitored by a manifold pressure sensor, and adjusts the EGR valve and throttle positions to achieve optimal manifold pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If variable lift camshafts with small lift are used to reduce airflow into the cylinder, then cold start emissions are reduced, but the system cost increases significantly
Solution Approach 1:
The system performs preliminary action by depleting the manifold of excess air before the engine start event. The eTurbine operates in reverse during a predetermined period before start to create negative manifold pressure, removing excess air that would otherwise be drawn into the cylinders during cold start. This preliminary depletion reduces emissions without requiring expensive variable camshaft mechanisms.
2Ease of operation
If excess airflow is allowed during cold start, then the engine starts more easily, but emissions and noise vibration harshness increase
Solution Approach 1:
The system employs periodic action by controlling the eTurbine operation in distinct phases: a first predetermined period before start where the eTurbine operates in reverse to deplete the manifold, and a second predetermined period where the eTurbine transitions to forward rotation to assist engine acceleration. This periodic control sequence reduces emissions during the critical cold start window while maintaining ease of starting.
3Object-generated harmful factors
If the eTurbine operates in reverse to deplete the manifold, then emissions are reduced, but the eTurbine mechanical stress increases
Solution Approach 1:
The system applies partial action by limiting the reverse operation of the eTurbine to a predetermined period before engine start, rather than continuous reverse operation. The controller monitors manifold pressure and transitions the eTurbine back to forward rotation when the manifold is sufficiently depleted or when a predetermined time elapses. This partial reverse operation reduces emissions while minimizing cumulative mechanical stress on the eTurbine.
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
Reduces emissions and NVH by minimizing airflow and fuel consumption during cold starts without additional hardware, leveraging existing eTurbine and EGR components, resulting in a smoother engine start and reduced emissions.
Implementation Method 1
rotate a turbine to move air in a direction out of the manifold thereby creating a vacuum through the EGR circuit
Implementation Method 2
The EGR circuit has an EGR valve that selectively moves between an open position and a closed position
Implementation Method 3
the electric motor rotates a shaft associated with the compressor and the turbine
Data Source
AI summary
An engine system that delivers torque to a driveline of a vehicle includes an internal combustion engine (ICE), a manifold, an exhaust gas recirculation (EGR) circuit, an electric turbine (eTurbine) and a controller. The EGR circuit has an EGR valve that selectively moves between open and closed positions. The eTurbine is driven by an electric motor and is configured to deliver air away from the manifold. The controller determines an ICE start request and, based on the ICE start request, sends a signal to the EGR valve to open thereby fluidly connecting the manifold and the eTurbine. The controller sends a signal to the eTurbine to rotate and move air out of the manifold through the EGR circuit. The eTurbine is used to deplete air in the manifold before starting the ICE. As a result, a reduction in fuel used and therefore a reduction in emissions at startup is achieved.