Adaptive Exhaust Valve Control for Compression Release Braking
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Solution Overview
Problem
Compression release braking in internal combustion engines is not efficient across a wide range of cylinder pressures, limiting its effectiveness in heavy-duty vehicles.
Innovation Solution
A method for controlling an exhaust valve arrangement in internal combustion engines, where the pressure level in the combustion chamber determines whether one or both exhaust valves are opened during compression release braking, allowing for adaptive control based on pressure levels, using pneumatically operated actuators independent of crankshaft rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If exhaust valves are opened during compression release braking, then compressed air is released to provide braking force, but the braking efficiency is insufficient at high cylinder pressures
Solution Approach 1:
The exhaust valve arrangement dynamically adjusts the number of open exhaust valves based on real-time cylinder pressure conditions. The control system transitions from a static valve configuration to a dynamic one, opening one or two exhaust valves according to whether the cylinder pressure is below or above a predetermined threshold, thereby optimizing braking efficiency across different pressure ranges
Solution Approach 2:
The system changes the operational parameters of the exhaust valve arrangement by varying the number of open exhaust valves (one or two) based on cylinder pressure levels. This parameter change allows the system to adapt to different pressure conditions, improving braking efficiency at both high and low pressure ranges
2Speed
If a single exhaust valve is opened during compression release braking, then the valve responds quickly, but the braking duration is limited
Solution Approach 1:
The control system implements periodic adjustment of exhaust valve opening based on cylinder pressure thresholds. When pressure drops below the threshold, additional exhaust valves are opened to extend braking duration; when pressure rises above the threshold, the system returns to opening fewer valves, creating a periodic control pattern that balances response speed and braking duration
3Duration of action of moving object
If multiple exhaust valves are opened during compression release braking, then braking duration increases, but the system becomes less responsive
Solution Approach 1:
The system dynamically adjusts the number of open exhaust valves based on real-time pressure feedback, creating a responsive control mechanism that prevents excessive valve opening while maintaining adequate braking duration. The dynamic adjustment ensures the system responds appropriately to changing pressure conditions without maintaining a constantly extended braking state
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 enables more versatile and responsive compression release braking, efficient at both high and low pressure levels, enhancing braking performance and duration.
Implementation Method 1
the exhaust valve arrangement is operable to direct combusted exhaust gas out from a combustion chamber of the internal combustion engine
Implementation Method 2
the energy contained in the compressed air is released into the atmosphere instead of being returned to the crankshaft
Data Source
AI summary
A method of controlling an exhaust valve arrangement of an internal combustion engine is provided. The exhaust valve arrangement is operable to direct combusted exhaust gas out from a combustion chamber of the internal combustion engine. The exhaust valve arrangement comprises a first exhaust valve and a second exhaust valve. The method includes determining a pressure level in the combustion chamber during compression release braking, comparing the pressure level with a predetermined threshold pressure; and controlling the exhaust valve arrangement to control either a single one, or both, of the first and second exhaust valves to be arranged in an open position during compression release braking in response to the pressure level being below or above the predetermined threshold pressure.