Isochoric Combustion Engine Linkage for Extended TDC Dwell
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Solution Overview
Problem
Reciprocating internal combustion engines face limitations in efficiency due to fixed sinusoidal piston motion, which compromises combustion control, leading to higher peak temperatures, increased NOx production, and reduced efficiency, especially with multiple fuel injection events at or near Top Dead Center.
Innovation Solution
The Engine with Isochoric Combustion employs a unique linkage system involving a crankshaft, connecting rod, triangle link, and radius link to maintain constant or nearly constant cylinder volume during combustion, allowing extended dwell at top dead center and enabling multiple fuel injections, thereby controlling combustion conditions and reducing peak temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional crankshaft and connecting rod mechanism is used, then the engine can convert reciprocating motion into rotational motion, but the piston motion is fixedly sinusoidal which compromises combustion control
Solution Approach 1:
The conventional single connecting rod mechanism is segmented into multiple components: a connecting rod, a triangle link with three joints, and a radius link. This segmentation allows independent control of different motion phases, enabling the piston to maintain a dwell position at top dead center while the crankshaft continues rotating, thereby achieving precise combustion control.
Solution Approach 2:
The linkage mechanism transitions from a fixed sinusoidal motion pattern to a dynamic motion pattern with variable velocity. The triangle link and radius link create a mechanical advantage system that allows the piston to remain stationary at top dead center for an extended period during combustion, while still converting rotational motion to reciprocating motion through the varying geometry of the linkage during different strokes.
2Temperature
If the piston moves downward during combustion, then the engine can maintain continuous motion, but peak combustion temperatures increase and NOx production increases
Solution Approach 1:
The linkage mechanism is designed to hold the piston at top dead center position before, during, and after fuel injection. This preliminary positioning ensures that combustion occurs at constant volume with the piston stationary, preventing the downward motion that would otherwise cause temperature spikes and NOx formation. The dwell position is maintained throughout the entire combustion process.
3Productivity
If multiple fuel injection events are used at or near TDC, then efficiency increases and emissions are reduced, but the fixed sinusoidal motion limits maximum efficiency
Solution Approach 1:
The triangle link and radius link mechanism provides continuous control of piston position throughout the combustion process. The linkage maintains the piston at top dead center for an extended period, allowing multiple fuel injection events to occur at optimal positions without the piston moving away. This continuous positioning capability enables multiple injections to contribute effectively to combustion, maximizing engine efficiency.
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 enhances fuel efficiency, reduces NOx and greenhouse gas emissions, and maintains mechanical work production during constant volume combustion, improving overall engine performance.
Implementation Method 1
A crankshaft has at least one crankpin offset from the centerline of the crankshaft by at least one crank arm. A connecting rod is connected to the at least one piston and to an upper joint of a triangle link. The triangle link is connected to the at least one crankpin at a second joint of the triangle link. A radius link is pivotally connected to the engine by a pivot pin at one end and connected to the triangle link at a third joint of the triangle link at its other end.
Data Source
AI summary
An Engine with Isochoric Combustion has pistons arranged within cylinders, connecting rods connected to the pistons and to upper joints of triangle links, and a crankshaft with crankpins offset from the centerline of the crankshaft by crank arms. The triangle links are connected to the crankpins at additional joints of the triangle links. Radius links are pivotally connected to the engine by pivot pins at one end and to the triangle links at a further joint of the triangle links at their other end. By way of geometry of the linkages defined by the crank arms, the triangle links, the radius links, and the connecting rods, and by way of the relative positions of the crankshaft, the cylinders, and the pivot pins, during a crank angle segment, the Cylinder Volume during the combustion event is characterized by an extended dwell.