Internal Combustion Engine Exhaust Valve Phase Offset
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Solution Overview
Problem
Internal combustion engines with supercharged or turbocharged systems face issues of crosstalk between combustion chambers due to backflow of exhaust gas, leading to increased residual gas rates and knock tendencies, which are exacerbated by high exhaust backpressure caused by segmented or twin-scroll turbines.
Innovation Solution
An internal combustion engine design with at least two exhaust valves per combustion chamber, where the first and second exhaust valves are actuated with a phase offset and shorter opening duration than the firing interval, minimizing crosstalk by ensuring exhaust gas flows through both exhaust gas flows to the turbine, thereby reducing exhaust backpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a segmented turbine is used with separate exhaust streams, then crosstalk between combustion chambers is significantly reduced, but exhaust backpressure increases leading to high exhaust losses
Solution Approach 1:
The exhaust system is divided into multiple separate exhaust streams (first exhaust stream and second exhaust stream) that are kept separate as long as possible. Each stream connects to different circumferential sections of the turbine impeller, preventing crosstalk between combustion chambers while maintaining efficient exhaust flow paths.
Solution Approach 2:
The separate exhaust streams are arranged in different spatial dimensions and only merge at the turbine housing level. The first exhaust stream enters the turbine impeller at a first circumferential section while the second exhaust stream enters at a second circumferential section, utilizing spatial separation to eliminate crosstalk.
2Object-affected harmful factors
If separate exhaust streams are used to reduce crosstalk, then residual gas rates decrease, but device complexity increases due to multiple exhaust valves and valve train modifications
Solution Approach 1:
Each combustion chamber is equipped with multiple exhaust valves (first exhaust valve and second exhaust valve) that are assigned to different exhaust streams. This segmentation of exhaust valve functions allows separate control of exhaust gas flow paths, reducing residual gas mixing while maintaining manageable valve train complexity through systematic assignment.
Solution Approach 2:
The valve train is designed to actuate multiple exhaust valves per combustion chamber with different opening durations. The same valve train mechanism serves dual purposes: controlling individual exhaust valve timing for crosstalk reduction and managing overall exhaust flow to the turbine, eliminating the need for separate control systems.
3Object-affected harmful factors
If exhaust valve opening duration is shortened to prevent crosstalk, then crosstalk between streams is minimized, but exhaust gas expulsion completeness is reduced
Solution Approach 1:
The exhaust valve operation is segmented into different duration patterns. First exhaust valves are actuated with a first opening duration while second exhaust valves are actuated with a second opening duration. This segmented timing approach allows optimization of each valve's function: shorter duration for crosstalk prevention and longer duration for complete exhaust expulsion.
Solution Approach 2:
The exhaust valves are actuated with periodic timing patterns that coordinate with the combustion cycle and turbine operation. The valve train controls the timing and duration of each exhaust valve opening in a periodic manner, ensuring that exhaust gases are completely expelled while maintaining the timing needed to prevent crosstalk between streams.
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 design effectively reduces crosstalk between combustion chambers and minimizes exhaust backpressure, enhancing combustion efficiency and reducing knock tendencies in internal combustion engines.
Implementation Method 1
an exhaust turbine integrated into the exhaust system are provided
Implementation Method 2
exhaust gases from the combustion chamber are transferred to the other cylinders
Implementation Method 3
the first exhaust valve and the second exhaust valve of each combustion chamber with a phase offset relative to each other are actuated
Implementation Method 4
separate exhaust streams, each connecting only a portion of the combustion chambers to the turbocharger's exhaust turbine
Implementation Method 5
actuated with an opening duration that is smaller than or at most equal to the ignition interval of the combustion chambers
Implementation Method 6
High exhaust backpressures generally result in high exhaust losses and increased... Residual gas rates
Data Source
AI summary
An internal combustion engine having a combustion engine (10), an exhaust train and an exhaust turbine (26) which is integrated into the exhaust gas train, wherein the internal combustion engine (10) forms at least two combustion chambers (14), to each of which at least two outlet valves (46, 48) are assigned, and wherein the outlet valves (46, 48) can be actuated by means of a valve drive, wherein first outlet valves (46) which are assigned to the combustion chambers (14) are connected to the exhaust gas turbine (26) in an exhaust-gas-conducting fashion via a first common stream of exhaust gas (42), and second outlet valves (48) which are assigned to said combustion chambers (14) are connected to said exhaust gas turbine (26) in an exhaust-gas-conducting fashion via a second common stream of exhaust gas (44), is characterized in that the valve drive is embodied in such a way that said valve drive - activates the first outlet valves (46) and the second outlet valves (48) with, in each case, an opening period which is less than the ignition interval of the combustion chambers of bracket (14) or corresponds at maximum thereto, and - activates the first outlet valve (46) and the second outlet valve (48) of each combustion chamber (14) with a phase offset with respect to one another.