Two-Stroke Opposed Piston Engine Air Intake Control
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Solution Overview
Problem
Two-stroke opposed piston internal combustion engines experience poor performance of the exhaust after treatment system (EATS) due to low exhaust temperature and pressure at low engine loads, particularly in diesel engines, where the EATS is located downstream of a turbocharger, leading to cooling of exhaust gases and reduced efficiency.
Innovation Solution
Incorporating an additional port and valve system that allows air to escape through an additional port during the compression stroke, even after intake and exhaust ports are blocked by the pistons, to maintain higher exhaust temperatures, and selectively reducing air admittance to cylinders during low loads using intake valves, thereby enhancing EATS performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine operates at low load with standard intake and exhaust ports, then fuel consumption is reduced, but exhaust temperature becomes too low for effective EATS operation
Solution Approach 1:
The cylinder is divided into multiple sealed compartments by additional pistons, creating isolated chambers that can be individually controlled. This segmentation allows specific compartments to be deactivated or have reduced air intake while maintaining operation in other compartments, thereby reducing overall air consumption and fuel usage while maintaining sufficient exhaust temperature from the active compartments for EATS operation.
Solution Approach 2:
The system dynamically changes operational parameters by controlling the position and sealing of additional pistons to adjust the number of active combustion chambers. By varying the effective displacement and air intake per chamber based on load conditions, the engine maintains optimal exhaust temperature for EATS operation during low-load conditions while minimizing fuel consumption.
2Use of energy by moving object
If additional pistons are added to seal compartments and control air intake, then air intake is reduced improving fuel efficiency, but device complexity increases
Solution Approach 1:
The additional pistons perform multiple functions simultaneously: they seal compartment boundaries, control air intake timing, and regulate exhaust flow. By merging these functions into single moving components rather than using separate valves and seals for each function, the system reduces overall mechanical complexity while achieving precise control over air intake and exhaust parameters.
Solution Approach 2:
The additional pistons are designed as multi-functional components that serve as both sealing elements for compartment isolation and as flow control valves for air and exhaust management. This universal design allows a single component to replace multiple specialized parts, reducing the overall complexity of the valve train and sealing system.
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 effectively increases exhaust gas temperature and improves EATS performance during low engine loads by reducing the amount of air trapped in the cylinders, ensuring efficient operation of the exhaust after treatment system, even when the turbocharger may cool the exhaust gases.
Implementation Method 1
a communication between the cylinder and an additional conduit externally of the cylinder, via the additional port, being controllable with the additional port valve
Implementation Method 2
the performance of an EATS can be poor... effectively increases exhaust gas temperature and improves EATS performance
Implementation Method 3
exhaust after treatment system (EATS) of such an engine operating efficiently
Data Source
AI summary
A two-stroke opposed piston internal combustion engine including a plurality of cylinders, each cylinder being provided with a first piston and a second piston adapted to perform opposed motions in the cylinder, each cylinder being provided with at least one intake port, a communication between an air intake arrangement and the cylinder via the intake port being dependent on the position of the first piston, each cylinder further being provided with at least one exhaust port, a communication between an exhaust guiding arrangement and the cylinder via the exhaust port being dependent on the position of the second piston, at least one of the cylinders being provided with an additional port and an additional port valve, a communication between the cylinder and an additional conduit externally of the cylinder, via the additional port, being controllable with the additional port valve, the air intake arrangement including at least one intake valve for selectively reducing or inhibiting air admittance to at least one of the cylinders.