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. Many integral-engine compressors operate with an articulated connecting rod. For this type of engine-driven compressor, two power pistons share a crank throw with the compressor. The hinge pins that attach the power piston connecting rods to the crank are offset, causing the piston locations for each cylinder to be out of phase with each other. This causes top dead center (TDC) to occur at different crank angles, alters the geometric compression ratio, and also changes the port timings for each cylinder. In this study, the equations of motion for the pistons of the four possible compressor/piston configurations of a Cooper-Bessemer GMW are 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 GT-POWER, an engine modeling software developed by Gamma Technologies, in order to obtain an accurate simulation match to the experimental in-cylinder pressure data collected from a Cooper-Bessemer GMWH-10C. Assuming the piston motion of an engine with an articulated connecting rod is similar to a slider-crank mechanism can create a difference in port timings. The hinge pin offset creates asymmetrical motion about 180°aTDC, causing the port timings to also be asymmetrical about this location. The largest differences are shown in the intake port opening of about 10 deg and a difference in exhaust port opening of about 7 deg when comparing the motion of the correct configuration to the motion of a slider-crank mechanism. It is shown that 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.

References

References
1.
Blair
,
G.
,
1996
,
Design and Simulation of Two-Stroke Engines
,
Society of Automotive Engineers
, Warrendale, PA.
2.
Heywood
,
J. B.
,
1988
,
Internal Combustion Engine Fundamentals
,
McGraw-Hill
, New York.
3.
Wilson
,
R.
, and
Fawcett
,
J.
,
1974
, “
Dynamics of the Slider-Crank Mechanism With Clearance in the Sliding Bearing
,”
Mech. Mach. Theory
,
9
(
1
), pp.
61
80
.
4.
Patel
,
P.
,
Mourelatos
,
Z.
, and
Shah
,
P.
,
2007
, “
A Comprehensive Method for Piston Secondary Dynamics and Piston-Bore Contact
,”
SAE
Paper No. 2007-01-1249.
5.
Cheng
,
C.
, and
Akinola
,
A.
,
2017
, “
Piston Friction Reduction by Reducting Piston Compression Height for Large Bore Engine Applications
,”
SAE Int. J. Engines
,
10
(
4
), pp. 1940–1947
6.
Wong
,
V.
,
Tian
,
T.
,
Moughon
,
L.
,
Takata
,
R.
, and
Jocsak
,
J.
,
2006
, “
Low-Engine-Friction Technology for Advanced Natural-Gas Reciprocating Engines
,” Department of Energy of National Energy Technology Laboratory, Cambridge, MA, DoE Cooperative Agreement No.
DE-FC26-02NT41339
.https://digital.library.unt.edu/ark:/67531/metadc794376/
7.
Panayi
,
A.
,
Schock
,
H.
,
Chui
,
B.
, and
Ejakov
,
M.
,
2006
, “
Parameterization and FEA Approach for the Assessment of Piston Characteristics
,”
SAE
Paper No. 2006-01-0429.
8.
Haddad
,
S.
, and
Tjan
,
K.
,
1995
, “
An Analytical Study of Offset Piston and Crankshaft Designs and the Effect of Oil Film on Piston Slap Excitation in a Diesel Engine
,”
Mech. Mach. Theory
,
30
(
2
), pp.
271
284
.
9.
Dursunkaya
,
Z.
, and
Keribar
,
R.
,
1992
, “
Simulation of Secondary Dynamics of Articulated and Conventional Piston Assemblies
,”
SAE
Paper No. 920484.
10.
Adair
,
J.
,
Kirkpatrick
,
A.
,
Olsen
,
D.
, and
Gitano-Briggs
,
H.
,
2003
, “
Simulation of the Airflow Characteristics of a Two-Stroke Natural Gas Engine With an Articulated Crank
,”
ASME
Paper No. ICES2003-552.
11.
Evans
,
K.
,
Olsen
,
D.
, and
Willson
,
B.
,
2005
, “
Fuel and Ignition Control Methodologies for Engines With Articulated Connecting Rods
,”
Int. J. Engine Res.
,
6
(
3
), pp.
207
214
.
12.
Rojewski
,
J.
,
2014
, “
Optimization of Combustion Process in Industrial Gas Engines
,”
Doctoral dissertation
, Poznan University of Technology, Poznan, Poland.http://repozytorium.put.poznan.pl/Content/315565/Jakub_Lukasz_Rojewski_Optimization_of_combustion_process_in_industrial_gas_engines.pdf
13.
Gamma Technologies
,
2016
,
GT-SUITE Flow Theory Manual
, Version 7.5,
Gamma Technologies
, Westmont, IL.
14.
Gamma Technologies
,
2016
,
GT-SUITE Mechanics Theory Manual
, Version 7.5,
Gamma Technologies
, Westmont, IL.
You do not currently have access to this content.