Engine Cylinder Airflow Control During Deceleration Fuel Cutoff
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Solution Overview
Problem
Engine control systems face challenges in managing airflow during deceleration fuel cutoff (DFCO) events, leading to catalyst saturation with oxygen, which diminishes emission reduction capabilities and causes combustibility issues upon fuel delivery resumption.
Innovation Solution
The system includes a fuel control module and a valve control module that adjust airflow through engine cylinders by actuating intake and exhaust valves to minimize airflow during DFCO, then increase it to maximize cylinder temperature and ensure effective compression ratios before restarting fuel delivery, thereby avoiding catalyst saturation and ensuring proper engine restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If airflow is allowed to flow freely through cylinders during DFCO, then fuel efficiency is improved, but catalyst becomes saturated with oxygen causing emission reduction capability to deteriorate
Solution Approach 1:
The patent applies dynamics by making the valve lift state adjustable and variable during DFCO operation. The system transitions from a static valve position to a dynamic control scheme where the intake valve lift is reduced from full lift to a partial lift state, allowing the system to adapt airflow conditions in real-time to prevent catalyst saturation while maintaining fuel cutoff benefits
Solution Approach 2:
The patent changes the physical parameter of valve lift height to control airflow characteristics. By adjusting the intake valve lift from a full open position to a restricted partial position, the system modifies the airflow rate and oxygen delivery to the catalyst, thereby preventing oxygen saturation while maintaining the fuel efficiency gains of DFCO
2Object-generated harmful factors
If airflow is restricted during DFCO to prevent catalyst saturation, then emission reduction capability is maintained, but cylinder temperature decreases causing combustibility issues upon fuel resumption
Solution Approach 1:
The patent applies preliminary action by adjusting the intake valve lift to a partial position before fuel delivery is resumed. This pre-adjustment ensures that sufficient airflow and oxygen are available in the cylinder at the moment fuel injection restarts, preventing combustibility issues while having previously maintained emission control during the DFCO period
Solution Approach 2:
The system dynamically transitions the valve lift state from a restricted position during DFCO to a more open position before fuel resumption. This dynamic adjustment allows the system to optimize cylinder temperature and airflow conditions at different stages of the DFCO event, ensuring both emission control and reliable restart
3Temperature
If intake valve lift is increased before fuel delivery resumption, then cylinder temperature is maximized for effective restart, but airflow amount increases potentially causing catalyst saturation
Solution Approach 1:
The patent applies preliminary action by timing the increase in intake valve lift to occur specifically before fuel delivery resumption rather than continuously during DFCO. This timed adjustment ensures cylinder temperature is maximized at the critical restart moment while limiting the duration of increased airflow to prevent catalyst saturation
Solution Approach 2:
The system employs periodic action by cycling the intake valve lift between restricted and more open states depending on the operational phase. During DFCO the valve maintains a partial lift, then periodically transitions to a more open state before fuel resumption to maximize temperature, then returns to the restricted state to prevent catalyst saturation
Data Source
AI summary
A system includes a fuel control module and a valve control module. The fuel control module controls a fuel injector to stop fuel delivery to each cylinder of an engine in a vehicle when the vehicle is decelerating. The valve control module controls a valve actuator to actuate intake and exhaust valves of each cylinder of the engine between open and closed positions when fuel delivery to each cylinder of the engine is stopped. The valve control module controls the valve actuator to adjust an amount of airflow through each cylinder of the engine to a minimum amount when fuel delivery to each cylinder of the engine is initially stopped. The valve control module controls the valve actuator to adjust the amount of airflow through each cylinder of the engine to an amount greater than the minimum amount before fuel delivery to each cylinder of the engine is restarted.