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Technical Paper

The Investigation of Self-Balanced Property and Vibration on the Particular Crankshaft System for an Opposed Piston Engine

For an in-line diesel engine with four cylinder operating in four-stroke mode, the second-order reciprocating inertia forces generally cannot be well balanced with direct approach. The unbalanced second-order inertia forces are the main reason to cause vibration and noise in a diesel engine within low frequency range. The more superior tone quality for modern diesel engine has been expected even for bus application all the time, and there are tougher requirements for truck noise in developed countries, i.e. in Europe and USA. In present research a unique crankshaft system configuration was proposed, which including opposed piston, inner and outer connecting rod, and crankshaft but running in two-stroke mode, to eliminate the second-order inertia force considerably rather than by adding an extra balance shaft mechanism.
Technical Paper

Multi-Body Dynamic Simulation and Fatigue Analysis of the Unique Crank - train for a Creative Two-stoke Opposed Piston Diesel Engine

For an innovative opposed-piston diesel engine (OPE) with two-stroke operation mode, it attracted even more attentions than ever in some developed countries all around the world, attributed to the unique advantages of higher power density that conducive to downsize IC engine, as well as the potential of further reducing fuel consumption for outstanding thermal efficiency. To achieve fast practical application and ensure the feasibility in concept design stage, the performance characteristic of OPE crankshaft system was investigated, and thus a theoretical analytic model of crankshaft system in an OP2S (Opposed-piston two stroke) engine was established. The effects of all structural design variables on averaged output torque of OPE crankshaft were analyzed, respectively. It was found that the initial crank angle difference between inner crank web and outer crank web was considered as a most critical contributor to boost the averaged torque output than other design variables.
Technical Paper

The Effect of Port Timing and Exhaust Back Pressure on Uniflow Scavenging for a High Power Density OPE Engine

Currently the downsizing of IC Engine has become the mainstream to meet fuel economy and emission regulations. It is required that higher power output while with lighter weight that is actually a daunting challenge for a common four-stroke IC engine, because it needs lots of new technologies and high manufacturing cost. For recent years the two-stroke opposed piston engine has drawn much attention in many developed countries for fundamental advantages itself. Double firing frequency means the increased power density brings about smaller engine size and lighter weight. However, the low scavenge efficiency has been assumed the main disadvantage for a two-stroke engine for a long period, and adverse to combustion efficiency. The uniflow scavenging process was investigated by the transient CFD simulation for multiple Cases. The influence of port timing and exhaust back pressure on scavenging was analyzed for two different intake port layouts.
Technical Paper

Research on a New Electromagnetic Valve Actuator Based on Voice Coil Motor for Automobile Engines

The electromagnetic valve actuator (EMVA) is considered a technological solution for decoupling between crankshaft and camshaft to improve engine performance, emissions, and fuel efficiency. Conventional EMVA consists of two electromagnets, an armature, and two springs has been proved to have the drawbacks of fixed lift, impact noise, complex control method and large power consumption. This paper proposes a new type of EMVA that uses voice coil motor (VCM) as electromagnetic valve actuator. This new camless valvetrain (VEMA) is characterized by simple structure, flexible controllable and low actuating power. VCM provides an almost flat force versus stroke curve that is very useful for high precision trajectory control to achieve soft landing within simple control algorithm.