Parameters matching requirements for diesel free piston linear alternator start-up

Abstract

It is important to identify the relationship between the starting requirements and the structure parameters of the diesel free piston linear alternator on the structural design stage. In this article, the forces applied on the moving part during the starting process are analyzed, and an oscillation model is established. The numerical simulation results of the oscillation model are presented, and the energy-transfer mechanism is analyzed. Then, the oscillation model is simplified by utilizing the energy balance theory. Expressions of the achieved starting frequency and required starting force are derived and the effects of different design variables on them are investigated. The results show that the achieved compression ratio is determined by the energy balance between the friction consumption and the energy supplied by the starting force. The starting frequency achieved and starting force required are associated with the cylinder bore, the moving mass, and effective stroke of the engine, which can be applied to the matching design and optimization of the prototype.

Performance Analysis of a Flexi-Fuel Turbine-Combined Free-Piston Engine Generator

“…Toyota Central R&D Labs Inc. similarly established an FPEG prototype (single-piston) that was found to be steady for a prolonged duration of time [20,21]. Several studies on dual piston FPEGs are cited in the works of [1,14,[22][23][24].…”

Experimental study of the operation characteristics of an air-driven free-piston linear expander

“…Now there have been many different free-piston engines are investigated by numerous research groups due to the potential advantages in terms of high fuel efficiency and low engine emissions. For modern applications, the free-piston engine concept has been proposed for applying as hydraulic free-piston engines aiming for smaller scale applications, free-piston engine generator that aims for application in hybrid electric vehicles, and two-stroke high-speed free-piston diesel engine concept aims for marine application [21][22][23][24][25][26].…”

A comparison of alternative linear machines for use with a direct drive free piston engine

“…When designed for a free piston engine, there are two electrical machine parameters limited by the mechanical requirement: the required electrical force and the translator mass limit [9].…”

“…Eq. 1 [9] relates the output force, Fe, to, Cf the viscous friction force coefficient, Kf the static friction force coefficient, D the cylinder bore, b the ring width, p0 the ambient pressure, L the effective stroke, m the translator mass, ε the compression ratio and ϓ the adiabatic exponent . For a free piston engine design in completion, the electrical force and moving part mass will directly influence the compression ratio (stroke) and speed profile (acceleration).…”