Skip Fire Engine Valve Control via Exhaust Monitoring
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Solution Overview
Problem
In internal combustion engines, skip fire control requires precise management of intake and exhaust valves to prevent damage from high-pressure combustion gases when cylinders are deactivated, as existing systems struggle to ensure safe valve operation during rapid engine speed changes and variable displacement scenarios.
Innovation Solution
The implementation of a valve control system using collapsible lifters and solenoids, where the intake valve is deactivated based on exhaust valve actuation status, utilizing proximity sensors and safety circuits to prevent the intake valve from opening into a cylinder with high-pressure gases, and employing a single solenoid to activate and deactivate both intake and exhaust valves, allowing for rapid and safe valve deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the intake valve is deactivated during skip fire operation, then fuel efficiency is improved and pumping losses are reduced, but the risk of damage from high-pressure combustion gases increases if the exhaust valve fails to open
Solution Approach 1:
The safety circuit proactively prevents intake valve activation by monitoring exhaust valve operation before the intake valve could be damaged. When the exhaust valve fails to open, the safety circuit detects this condition and blocks the intake valve solenoid from activating, thereby preventing potential damage before it can occur.
Solution Approach 2:
The safety circuit acts as an intermediary between the exhaust valve operation and the intake valve control system. It monitors exhaust valve actuation and uses this information to control whether the intake valve can be activated, creating a protective barrier that prevents damage while allowing normal skip fire operation.
2Reliability
If a safety circuit is implemented to monitor exhaust valve actuation, then valve operation safety is improved, but device complexity increases
Solution Approach 1:
The safety circuit is integrated into the existing valve control system and uses the same solenoid and control architecture for both normal valve operation and safety monitoring. The intake valve solenoid serves dual purposes: controlling intake valve deactivation for fuel efficiency and responding to safety circuit signals to prevent damage, thereby reducing the need for separate dedicated safety components.
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 solution ensures safe operation by preventing intake valve activation during high-pressure conditions, reducing the risk of damage and optimizing engine efficiency through proactive and reactive control strategies, even at high engine speeds, thereby enhancing fuel efficiency and reducing pumping losses.
Implementation Method 1
an exhaust valve actuator including a solenoid
Implementation Method 2
an output of a proximity sensor that senses movement of the exhaust valve
Data Source
AI summary
A variety of methods and devices for controlling the operation of the intake and exhaust valves in an internal combustion engine during skip fire operation are described. In various embodiments, an exhaust valve monitor or other suitable mechanism is used to detect exhaust valve actuation faults. When an exhaust valve actuation fault is detected for a particular cylinder, the corresponding intake valve is deactivated (or not activated) in circumstances when it would otherwise be activated in order to prevent the intake valve from opening into a cylinder that contains high pressure combustion gases. The described approach is particularly beneficial when skip fire operation is combined with cylinder deactivation so that air is not pumped through the cylinders during the skipped working cycles.