Research on the lubrication performance of engine piston skirt–cylinder liner frictional pair considering lubricating oil transport

2018 ◽  
Vol 21 (4) ◽  
pp. 713-722 ◽  
Author(s):  
Jun Sun ◽  
Feifei Hao ◽  
Guangsheng Liu ◽  
Hu Wang ◽  
Qin Teng ◽  
...  
Keyword(s):  
Cylinder Liner ◽  
Lubricating Oil ◽  
Frictional Pair ◽  
Operating Cycle ◽  
Piston Skirt ◽  
Oil Transport ◽  
Bottom Dead Center ◽  
Lubrication Performance ◽  
Oil Flow ◽  
Secondary Motion

In current lubrication analysis of piston skirt, the flooded status is generally considered in the piston skirt–cylinder liner frictional pair in all strokes of an engine operating cycle. However, the quantity of lubricating oil at the entrance of piston skirt cannot always ensure the sufficient lubrication status of piston skirt–cylinder liner frictional pair when the piston moves from the bottom dead center to the top dead center in actual engine. In this article, based on the model of piston secondary motion, fluid lubrication, and lubricating oil flow, the lubrication performance of piston skirt–cylinder liner frictional pair is analyzed, in which the quantity of lubricating oil detained on the surface of cylinder liner after the piston skirt moves from the top dead center to the bottom dead center and is considered as the quantity of lubricating oil at entrance of piston skirt when the piston moves from the bottom dead center to the top dead center. The results show that compared with current analysis, in which the sufficient lubrication of piston skirt–cylinder liner frictional pair is assumed in all strokes of engine, there are remarkable changes for the lubrication performance of piston skirt–cylinder liner frictional pair and the piston secondary motion when the lubrication status of the frictional pair in the upstroke of piston is determined by considering actual lubricating oil transport in the lubrication analysis of piston skirt.

Research on the Status of Lubricating Oil Transport in Piston Skirt-Cylinder Liner of Engine

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Jun Sun ◽  
Xiang Huang ◽  
Guangsheng Liu ◽  
Xiaoyong Zhao ◽  
Enming Miao ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Cylinder Liner ◽  
Lubricating Oil ◽  
Engine Load ◽  
Piston Skirt ◽  
Oil Transport ◽  
Bottom Dead Center ◽  
The Status ◽  
Intake Stroke ◽  
Engine Operating Condition

The status of the lubricating oil transport in the piston skirt-cylinder liner has important influence on the lubrication of piston assembly frictional pair, the consumption of lubricating oil, the emission, and the performance degradation of lubrication oil. In this paper, based on the model of piston secondary motion, fluid lubrication and lubricating oil flow, the status of the lubricating oil transport between the piston skirt and the cylinder liner on different engine operating condition is calculated, and the quantity of lubricating oil retained on the surface of cylinder liner is mainly analyzed when the piston skirt moves from the top dead center to the bottom dead center. The results show that the variation of the quantity of retained lubricating oil is almost same in the corresponding stroke on different engine operating condition; the quantity of retained lubricating oil is dissimilar at different moment and is equal in principle at the piston top and bottom dead center. The quantity of lubricating oil retention is dissimilar at different moment in the intake stroke or expansion stroke, but the quantity of lubricating oil retention is equal in principle at the top and bottom dead center on different engine operating condition. When the engine is on the same load condition, as the engine rotational speed increasing, the quantity of retained lubricating oil is decreased in the whole intake stroke and the middle and later parts of expansion stroke, but the quantity of retained lubricating oil is increased in the front part of expansion stroke. When the engine is on the same rotational speed condition, the quantity of retained lubricating oil increases with the increasing engine load in the front part of expansion stroke, it does not vary with the engine load in principle in the middle and later part of expansion stroke, the variation that the quantity of retained lubricating oil varies with the engine load is dissimilar in the intake stroke on different engine rotational speed condition.

scholarly journals The Analysis of Secondary Motion and Lubrication Performance of Piston considering the Piston Skirt Profile

2018 ◽  
Vol 2018 ◽  
pp. 1-27 ◽  
Author(s):  
Yanjun Lu ◽  
Sha Li ◽  
Peng Wang ◽  
Cheng Liu ◽  
Yongfang Zhang ◽  
...  
Keyword(s):  
Thermal Deformation ◽  
Work Performance ◽  
Cylinder Liner ◽  
Connecting Rod ◽  
Piston Skirt ◽  
Piston Cylinder ◽  
Lubrication Performance ◽  
Rod System ◽  
Liner System ◽  
Secondary Motion

The work performance of piston-cylinder liner system is affected by the lubrication condition and the secondary motion of the piston. Therefore, more and more attention has been paid to the secondary motion and lubrication of the piston. In this paper, the Jakobson-Floberg-Olsson (JFO) boundary condition is employed to describe the rupture and reformation of oil film. The average Reynolds equation of skirt lubrication is solved by the finite difference method (FDM). The secondary motion of piston-connecting rod system is modeled; the trajectory of the piston is calculated by the Runge-Kutta method. By considering the inertia of the connecting rod, the influence of the longitudinal and horizontal profiles of piston skirt, the offset of the piston pin, and the thermal deformation on the secondary motion and lubrication performance is investigated. The parabolic longitudinal profile, the smaller top radial reduction and ellipticities of the middle-convex piston, and the bigger bottom radial reduction and ellipticities can effectively reduce the secondary displacement and velocity, the skirt thrust, friction, and the friction power loss. The results show that the connecting rod inertia, piston skirt profile, and thermal deformation have important influence on secondary motion and lubrication performance of the piston.

Impact of the Piston Secondary Motion on its Slap Force

2014 ◽  
Vol 553 ◽  
pp. 582-587
Author(s):  
Bao Cheng Zhang ◽  
Tong Li ◽  
Hai Fei Zhan ◽  
Yuan Tong Gu
Keyword(s):  
Theoretical Model ◽  
Boundary Conditions ◽  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Cylinder Liner ◽  
Internal Combustion ◽  
Lubricating Oil ◽  
Actual Condition ◽  
Piston Skirt ◽  
Secondary Motion

A theoretical model is developed for the analysis of piston secondary motion. Based on this model, the slap force of a specific L6 diesel engine was compared when considering different boundary conditions, such as lubricating oil on cylinder liner, surface roughness, deformation of cylinder liner and piston skirt. It is concluded that it is necessary to consider the secondary motion of piston in the analysis of the inner excitation for an internal combustion engine. A more comprehensive consideration of the boundary condition (i.e., more close to the actual condition) will lead to a smaller maximum slap force, and among all boundary conditions considered in this paper, the structural deformation of the piston skirt and cylinder liner is the most influential factor. The theoretical model developed and findings obtained in this study will benefit the future analysis and design of advanced internal combustion engine structures.

scholarly journals Research on the influence of key structural parameters on piston secondary motion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haixiang Yang ◽  
Jilin Lei ◽  
Xiwen Deng ◽  
Jun Wen ◽  
Zhigao Wen ◽  
...  
Keyword(s):  
Power Loss ◽  
Structural Parameters ◽  
Cylinder Liner ◽  
Oil Consumption ◽  
Frictional Loss ◽  
Significance Level ◽  
Friction Power ◽  
Piston Skirt ◽  
Secondary Motion ◽  
Response Method

AbstractPiston secondary motion not only influences the side knocking of piston and frictional loss, but also influence the in-cylinder oil consumption and gas blow-by. An inline four-cylinder common rail diesel engine was chosen as the research object. Dynamic simulation model of piston assembly was built based on the piston and cylinder liner temperature field test. The impacts of pinhole offset, liner clearance and piston skirt ovality on piston secondary motion were researched. Based on the surface response method, the influence of multiple factors on friction power loss and slapping energy is estimated. The results indicate that: in-cylinder stress condition of piston will change with its structural parameters, then the secondary motion of piston will be affected as a result. Pinhole offset, liner clearance, piston skirt ovality and the interaction of the latter two all have significant effects on the friction power loss, while the slapping energy is significantly affected by liner clearance. Therefore, the parameters can be designed based on the significance level to optimize the secondary motion characteristics of the piston.

Numerical Study of Piston Skirt-Liner Lubrication Considering the Effects of Deformation in Internal Combustion Engines

2012 ◽  
Author(s):  
Lipu Ning ◽  
Xianghui Meng ◽  
Youbai Xie
Keyword(s):  
Elastic Deformation ◽  
Internal Combustion Engines ◽  
Numerical Study ◽  
Cylinder Liner ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Surface Geometry ◽  
Piston Skirt ◽  
Lubrication Performance ◽  
Liner System

This paper presents a comprehensive lubrication model for piston skirt-liner system of internal combustion engines. In the model it is included that the effects of the surface roughness, the piston skirt surface geometry, the piston pin offset, the crankshaft offset, and the lubricant viscosity on the piston secondary motion and lubrication performance. Especially, the effects of the thermal and the elastic deformation of the piston skirt and the cylinder liner, and the piston skirt deformations due to the combustion pressure and the piston axial inertia, are considered as the key task in this study. The results show that the combustion force, the working temperature and the piston axial inertia all play important roles in the piston-skirt lubrication. Also, considering the elastic deformation of the piston skirt and the cylinder liner is beneficial to the prediction of piston-skirt lubrication more accurately. The developed program in this study can provide a useful tool for the analysis of the piston-liner system lubrication problem.

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