Kinematics of an articulated connection rod and its effect on simulated compression pressures and port timings

[+] Author and Article Information
Kelsey Fieseler

Texas A&M University, College Station, Texas, USA

Timothy J. Jacobs

Texas A&M University, College Station, Texas, USA

Mark Patterson

GE Oil & Gas, Houston, Texas, USA

1Corresponding author.

ASME doi:10.1115/1.4039831 History: Received February 21, 2018; Revised March 21, 2018


In an integral-engine compressor with an articulated connecting rod, two power pistons share a crank throw with the compressor. Because of this, the hinge pins are offset, causing the piston locations for each cylinder to be out of phase with each other. This study discusses the motion of the articulated connecting rod of an integral-engine compressor and the effect of the kinematics on in-cylinder pressure and port timings. A piston position modeling technique based on kinematics and engine geometry is proposed in order to improve the accuracy of simulated in-cylinder compression pressures. In this study, the equations of motion for the pistons of the four possible compressor/piston configurations of a Cooper-Bessemer GMW were developed. With the piston profiles, the intake and exhaust port timings were determined and compared to those of a slider-crank mechanism. The piston profile was then inputted into an engine modeling software in order to obtain an accurate simulation match to the experimental in-cylinder pressure data. It was found that the hinge pin offset creates asymmetrical motion about 180°aTDC, causing the port timings to also be asymmetrical. The largest differences are shown in the intake port opening of about 10° and a difference in exhaust port opening of about 7° when comparing the motion of a slider-crank mechanism. Properly calculating the piston motion profiles according to the crank articulation and engine geometry provides a good method of simulating in-cylinder pressure data during the compression stroke.

Copyright (c) 2018 by ASME
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