Modeling and experimental confirmation of a new start method utilizing mechanical resonance for the linear range extender

The linear range extender (LRE) features a special crankless engine and linear oscillation, which cannot achieve engine starting by accumulating the energy of the starting motor through the flywheel like traditional engines. This paper proposes a self-excited compression method using mechanical resonance mechanism to accumulate energy and enlarge piston reciprocating for starting of the LRE, and a mathematical model considering the coupling of thermodynamics, friction, heat transfer, electromagnetic force, and dynamics in the resonance process is proposed to describe the starting compression behavior, meanwhile the corresponding resonance compression experiment of the LRE is also conducted to verify the effectiveness of the resonance method and model. The results indicate that: this method effectively solves the compression problem of the LRE starting by inducing resonance through precise electromagnetic thrust phase synchronization control and thrust boundary optimization. It enables the LRE to increase the amplitude and reciprocating frequency of piston motion, thereby increasing the energy of compressed gas in the cylinder for fuel ignition. The greater the excitation force, the larger the amplitude of reciprocating and the compression ratio of the engine, the higher the peak gas pressure, and the shorter the resonance cycle period, thereby shortening the starting compression time and facilitating rapid engine compression starting.