Engine Fuel Cut-Out Control via Valve Timing and EGR
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Solution Overview
Problem
Operating an engine in fuel cut-out mode reduces fuel consumption but can disrupt the balance of oxidants and reductants in exhaust aftertreatment devices, leading to increased NOx breakthrough, which requires additional fuel to reestablish balance and meet emissions standards.
Innovation Solution
Adjusting intake valve closing timing and opening an exhaust gas recirculation (EGR) valve to reduce the amount of fresh air and oxygen pumped to the aftertreatment device, allowing for more efficient reactivation with less fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine operates in fuel cut-out mode to reduce fuel consumption, then fuel efficiency is improved, but the balance of oxidants and reductants in the aftertreatment device is disrupted causing increased NOx breakthrough
Solution Approach 1:
The system performs preliminary actions by storing reductant (ammonia) in the aftertreatment device before fuel cut-out mode begins, and by predicting the duration of fuel cut-out events. This allows the control strategy to pre-position necessary chemicals and plan reactivation sequences, ensuring the reductant/oxidant balance is maintained even when fuel injection is interrupted
Solution Approach 2:
The control system dynamically adjusts the reactivation strategy based on the predicted duration of fuel cut-out events. For short-duration events, a different reactivation approach is used compared to long-duration events. The system continuously monitors and adapts the aftertreatment device operation based on real-time conditions, optimizing the balance between fuel savings and emissions control
2Speed
If the engine pumps fresh air to the aftertreatment device during fuel cut-out mode, then engine rotation is maintained, but the aftertreatment device requires additional fuel to reestablish oxidant-reductant balance
Solution Approach 1:
The system stores reductant in the aftertreatment device before fuel cut-out mode begins, so that when the engine is reactivated, the reductant is already available and the system only needs to provide oxidant (fresh air) to restore balance. This preliminary storage reduces the fuel required during reactivation
Solution Approach 2:
The control system changes operational parameters by adjusting the air-fuel ratio and EGR rates during and after fuel cut-out events. By controlling the amount of fresh air pumped to the aftertreatment device and managing the oxidation/reduction balance through parameter adjustments, the system minimizes the fuel required for reactivation while maintaining engine rotation
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 reduces fuel consumption, improves aftertreatment device efficiency, and minimizes the cooling of the aftertreatment device, enabling it to operate more efficiently during and after fuel cut-out mode.
Implementation Method 1
opening an exhaust gas recirculation (EGR) valve via a controller in response to an engine entering a fuel cut-out mode
Implementation Method 2
adjusting intake valve closing timing in response to an engine entering a fuel cut-out mode
Data Source
AI summary
Methods and systems for operating an engine that includes adjustable poppet valve timing and an exhaust gas recirculation valve are described. In one example, the exhaust gas recirculation valve is opened and the timing of the poppet valves is retarded so that an amount of fresh air that is pumped by the engine to an after treatment device may be reduced.