Variable Crankshaft Phasing for Opposed-Piston Engine Port Timing
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Solution Overview
Problem
Opposed-piston engines face challenges in dynamically adapting port timing and phasing to changing engine operating conditions, such as varying speeds and loads, which affects optimal blowdown, uniflow scavenging, and supercharger operations, and this is complicated by sleeve valve constructions that sacrifice the simplicity of opposed-piston engine designs.
Innovation Solution
The implementation of an electronically-controlled, hydraulically-actuated crankshaft phasing mechanism that adjusts the rotational position of one or both crankshafts using a coaxial vane assembly and hydraulic fluid control, allowing for dynamic variation of piston phasing and port timing based on engine operating parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sleeve valve constructions are used to control port timing, then port timing can be adjusted, but the simplicity of opposed-piston engine construction is sacrificed
Solution Approach 1:
The patent applies dynamics by making the crankshaft phasing adjustable rather than fixed. The variable crank phasing mechanism allows the phase relationship between the two crankshafts to be dynamically changed during operation, enabling port timing adjustment without adding sleeve valves or other complex moving parts to the cylinder assembly.
Solution Approach 2:
The patent uses an intermediary mechanism (variable crank phasing system) to achieve port timing control. Instead of directly controlling port timing through sleeve valves in the cylinder, the system uses a separate phasing mechanism that adjusts the relative rotational positions of the crankshafts, which in turn adjusts the port timing as an indirect effect.
2Adaptability or versatility
If fixed piston phasing is used, then engine construction remains simple, but the ability to adapt to changing engine conditions is limited
Solution Approach 1:
The patent transforms the static crankshaft phasing into a dynamic system. The variable crank phasing mechanism allows the phase angle between crankshafts to be adjusted during operation based on engine conditions such as load and speed, enabling the engine to adapt without requiring complex sleeve valve systems.
Solution Approach 2:
The patent changes the parameter of crankshaft phase angle from a fixed value to a variable parameter that can be adjusted during operation. By modifying this single parameter through the phasing mechanism, the engine can optimize performance across different operating conditions without changing other fundamental aspects of the engine construction.
3Productivity
If variable port timing is implemented through sleeve valves, then optimal blowdown and scavenging can be maintained, but the number of moving parts increases
Solution Approach 1:
The patent extracts the port timing control function from the cylinder assembly (where it would require sleeve valves) and relocates it to the crankshaft phasing system. This separation allows the timing control to be achieved through crankshaft position adjustment rather than through additional moving parts in the cylinder.
Solution Approach 2:
The variable crank phasing mechanism serves multiple functions: it controls port timing, optimizes blowdown and scavenging efficiency, and adapts to different engine operating conditions, all through a single mechanism that adjusts the relative phase between crankshafts.
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 enables the opposed-piston engine to maintain optimal port operation by dynamically adjusting piston phasing and timing, thereby adapting to changing engine conditions without compromising the simplicity of the opposed-piston construction, ensuring efficient engine performance across varying loads and speeds.
Implementation Method 1
an electronically-controlled, hydraulically-actuated crankshaft phasing mechanism that adjusts the rotational position of one or both crankshafts using a coaxial vane assembly and hydraulic fluid control
Data Source
AI summary
The timing or phasing of port openings and closings during operation of an opposed-piston engine is varied in response to changing engine speeds and loads by changing crankshaft phasing.