The Frequency Variation Study Influenced by Spark Timing and Equivalence Ratio in a 2-Stroke Linear Engine

摘要

A small-bore 2-stroke linear engine has been designed to generate electricity linked with a linear alternator. In order to precisely control the operating frequency of the piston, the velocity of the piston accelerated by the combustion pressure was studied. The experiment was designed to investigate how some parameters – mainly spark timing (ST) delay and air/fuel equivalence ratio - influence the combustion. In this study, one side of the engine cylinder was used for the combustion and the other cylinder was used to accelerate the piston to the designated compressing velocity, to exactly examine the influence of the 2 parameters to the velocity change of the piston. The size of the piston diameter is 10 mm and the maximum available stroke is 19 mm. Dynamic parameters such as displacement, velocity, and acceleration data were acquired, and pressure data had also been analyzed to see the maximum peak pressure of the combustion. The indicated mean effective pressure (IMEP) was calculated to find out under which conditions the maximum work was done. The maximum IMEP was found as the spark timing delay increased, and the velocity increase had a similar increasing trend in response with IMEP.