Cylinder Deactivation Control for Engine Braking and Fuel Efficiency
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Solution Overview
Problem
Vehicles using all six cylinders in all operating conditions suffer from inefficiencies, particularly in low load, idle, or cruise conditions, leading to excessive fuel consumption due to full fueling of all cylinders, which is not optimal for engine output.
Innovation Solution
Implementing cylinder deactivation (CDA) modes that selectively deactivate intake and exhaust valves and fuel injection for one or more cylinders, allowing for controlled engine speed profiles and engine braking, while maintaining thermal management and pollution control, thereby reducing fuel consumption and extending coasting modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If all cylinders are fueled in low load, idle, or cruise conditions, then engine output is maintained, but fuel consumption becomes excessive
Solution Approach 1:
The engine is divided into active and deactivated cylinder groups, allowing selective fueling. The control system segments the cylinders based on operating conditions, enabling only necessary cylinders to consume fuel while maintaining required power output.
Solution Approach 2:
Instead of fueling all cylinders under every condition, the system applies partial action by fueling only the necessary number of cylinders based on current load requirements. This prevents excessive fuel consumption while maintaining adequate engine output.
2Use of energy by moving object
If the engine is turned off to coast the vehicle, then fuel consumption is reduced, but engine braking is unavailable
Solution Approach 1:
The engine operation is segmented into different cylinder groups - some cylinders are deactivated for fuel savings while others remain active to provide engine braking capability when needed during coasting.
Solution Approach 2:
The system dynamically adjusts cylinder deactivation status based on real-time operating conditions, allowing transition between different coasting modes and maintaining the ability to engage engine braking when required.
3Use of energy by moving object
If defueled coasting is used to coast the vehicle, then fuel consumption is reduced, but cold air pumping cools the aftertreatment system below efficiency point
Solution Approach 1:
The harmful effect of cold air pumping on aftertreatment temperature is extracted and eliminated by deactivating valve motion in selected cylinders, preventing cold air from being drawn through the engine and cooling the aftertreatment system.
Solution Approach 2:
Instead of complete valve deactivation which would cause cold air pumping, the system applies partial deactivation where only specific valves are closed while maintaining minimal necessary air flow to prevent aftertreatment cooling.
4Use of energy by moving object
If cylinder deactivation is implemented, then fuel consumption is reduced and aftertreatment temperature is maintained, but valve and fuel injection control complexity increases
Solution Approach 1:
The existing valve control mechanisms are made multi-functional, serving both their traditional role and the additional function of cylinder deactivation. This allows the system to achieve fuel savings without requiring entirely separate control systems.
Solution Approach 2:
The control system uses feedback from operating conditions to dynamically adjust which cylinders are deactivated, optimizing fuel consumption while maintaining aftertreatment temperature and managing the complexity through adaptive control strategies.
Data Source
AI summary
A method for controlling vehicle speed comprises selecting an engine speed profile for a vehicle. Road grade data is received and processed to determine a road grade for the vehicle. Vehicle speed data is received and processed to determine a vehicle speed for the vehicle. A cylinder deactivation mode for a valvetrain of a multi-cylinder engine of the vehicle is selected. The cylinder deactivation mode comprises deactivating one or more intake valve, exhaust valve, and fuel injection for one or more cylinder of the multi-cylinder engine. The selected cylinder deactivation mode provides a controlled deviation from the selected engine speed profile at the road grade and vehicle speed.