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.

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.

The Effects of Piston Skirt Profiles on Secondary Motion and Friction

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Ozgur Gunelsu ◽  
Ozgen Akalin
Keyword(s):  
Power Loss ◽  
Radius Of Curvature ◽  
Cylinder Wall ◽  
Lateral Movement ◽  
Dynamics Model ◽  
Piston Skirt ◽  
Normal Forces ◽  
Oval Form ◽  
Secondary Motion ◽  
Frictional Performance

Piston skirt form deviating from a perfect cylinder is investigated numerically for an improved frictional performance. Three features defining the barrel and oval form of the skirt are compared in the search for lower friction power loss. Radius of curvature around the bulge of the barrel is changed to obtain a flatter or more-rounded lubricated area with respect to a hot-piston profile as well as the axial location of this bulge. On the other hand, the circumferential variation in the separation between the skirt and cylinder wall is represented by an elliptical piston and the aspect ratio is varied for comparison. These different skirt profiles are used in a developed piston secondary dynamics model solving for the lateral movement of the piston by calculating the hydrodynamic and boundary normal forces acting on the piston together with friction. Finally, an improved skirt profile is suggested to obtain better frictional efficiency.

The Study of Friction Power Loss of Piston Group of a Twin-Rotor Engine

2014 ◽  
Vol 620 ◽  
pp. 375-381 ◽  
Author(s):  
Jin Zhou Chen ◽  
Cun Yun Pan ◽  
Wen Min Li ◽  
Lei Zhang ◽  
Hu Chen
Keyword(s):  
Power Loss ◽  
Mechanical Efficiency ◽  
Scientific Basis ◽  
Low Friction ◽  
Frictional Loss ◽  
Friction Power ◽  
Rotary Engine ◽  
Piston Group ◽  
Higher Power ◽  
Asperity Contacts

Compared with the conventional piston engines, the new rotary engine has many significant advantages, such as smaller volume and higher power density. Current studies at home and abroad are mainly focusing on aspects of its structural design, kinematics, dynamics analysis, except mechanical efficiency. In conventional piston engines, frictional loss of the piston group accounted for 65% of the total friction power loss[1]. In order to provide the scientific basis for designing low friction piston of the rotary engine, this paper combine the average two-dimensional Reynolds equation, the asperity contacts equation, viscosity-temperature equation and loads balance equation, proposing a method for calculating the friction power loss, and the applying the method to calculate the friction power loss of piston group of a new rotary engine.

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.

The effect of lubricant viscosity model with improver on friction and lubrication of piston skirt-cylinder liner conjunction

2019 ◽  
Vol 72 (1) ◽  
pp. 157-164
Author(s):  
Gu Xin ◽  
Xiao-Ri Liu ◽  
Dong-Kang Cheng ◽  
Qing-Ping Zheng ◽  
Meng-Han Li ◽  
...  
Keyword(s):  
Shear Rate ◽  
Film Thickness ◽  
Friction Force ◽  
Cylinder Liner ◽  
Content Type ◽  
Oil Film ◽  
Friction Power ◽  
Piston Skirt ◽  
Lubricant Viscosity ◽  
Oil Film Pressure

Purpose This paper aims to investigate the effect of lubricant viscosity model with improver on friction and lubrication of piston skirt-cylinder liner conjunction. Design/methodology/approach A dynamic calculation model is established for the piston skirt-cylinder liner conjunction of a heavy-duty commercial diesel engine, to explore the effects of two kinds of lube oil viscosity models named after polyalkyle-metacrylate-1 (PAMA1) and styrene-isoprene-copolymer (SICP) improvers on the maximum oil film viscosity, the minimum oil film thickness, the peak oil film pressure, the maximum shear rate, the friction force and the total friction power loss. Findings The variation trends with the crank angle of the above parameters are not changed with the difference of improvers, while obvious numerical differences are found except the maximum oil film pressure. The minimum oil film thickness and maximum shear rate of PAMA1 are larger than that of SICP, the maximum oil film viscosity of SICP is larger than that of PAMA1, which indicates that the shear-thinning effect of PAMA1 is greater, the maximum friction force on the piston of SICP is larger than that of PAMA1, and the total friction power consumption is also larger, the average friction power consumptions of SICP and PAMA1 are 385.4 and 262.8 W, respectively, with the relative difference of 31.8 per cent. Originality/value The influence of different lubricating oil additive models on the lubrication and friction of piston skirt-cylinder liner conjunction is simulated and analyzed.

Effects of Piston Design Parameters on Piston Secondary Motion and Skirt - Liner Friction

2005 ◽  
Vol 219 (6) ◽  
pp. 435-449 ◽  
Author(s):  
S. H. Mansouri ◽  
V. W. Wong
Keyword(s):  
Scaling Laws ◽  
Cylinder Liner ◽  
Design Guidelines ◽  
Design Parameters ◽  
Piston Skirt ◽  
Lubrication Regimes ◽  
Impact Forces ◽  
Crank Angle ◽  
Secondary Motion ◽  
Quantitative Design

In this article, a previously developed and experimentally validated piston secondary motion model has been improved further numerically and applied to understand the detailed interactions between the piston skirt and the cylinder liner for various piston design parameters. The model considers the roughness of the surfaces and the topography of the skirt in both the axial (barrel profile) and circumferential (ovality) directions. Three modes of lubrication: hydro-dynamic, mixed, and boundary lubrication regimes have been considered and the skirt is partially flooded in most cases. Elastic deformation of the skirt is an essential part of the model. In this model, the piston dynamic behaviour and frictional and impact forces are predicted as functions of crank angle and are examined in detail. Parameters investigated include piston skirt profile, piston-to-liner clearance, surface roughness, and oil availability. The results show that some of these parameters have profound effects on the frictional and impact forces at the piston skirt/liner interface, and therefore, they have the potential to optimize the piston frictional power loss. Correlations and non-dimensional scaling laws are developed to illustrate the basic governing phenomena. These results aim to provide a set of quantitative design guidelines.

Piston dynamics, lubrication and tribological performance evaluation: A review

2018 ◽  
Vol 21 (5) ◽  
pp. 725-741 ◽  
Author(s):  
Cristiana Delprete ◽  
Abbas Razavykia
Keyword(s):  
Power Loss ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Tribological Performance ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Design Parameters ◽  
Combustion Engines ◽  
Piston Skirt ◽  
Secondary Motion

Mechanical power loss of lubricated and bearing surfaces serves as an attractive domain for study and research in the field of internal combustion engines. Friction reduction at lubricated and bearing surface is one of the most cost-effective ways to reduce gas emission and improve internal combustion engines’ efficiency. This thus motivates automotive industries and researchers to investigate tribological performance of internal combustion engines. Piston secondary motion has prime importance in internal combustion engines and occurs due to unbalanced forces and moments in a plane normal to the wrist pin axis. Consequently, piston executes small translations and rotations within the defined clearance during the piston reciprocating motion. Mechanical friction power loss and lubrication at piston skirt/liner and radiated engine noise are dramatically affected by piston secondary dynamics. The lubrication mechanism, piston secondary motion and tribological performance are affected by piston design parameters (piston/liner clearance, wrist pin offset, skirt profile, etc.), lubricant rheology, oil transport mechanism and operating conditions. Therefore, this review is devoted to summarize the synthesis of main technical aspects, research efforts, conclusions and challenges that must be highlighted regarding piston skirt/liner lubrication and piston dynamics and slap.

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.

An efficient procedure to predict the dynamic loads for piston liner systems in marine engines

2021 ◽  
pp. 146808742199698
Author(s):  
Lyu Xiuyi ◽  
Abdullah Azam ◽  
Wang Yuechang ◽  
Lu Xiqun ◽  
Li Tongyang ◽  
...  
Keyword(s):  
Simulation Analysis ◽  
Structural Parameters ◽  
Computation Time ◽  
Primary Source ◽  
Cylinder Liner ◽  
Accurate Method ◽  
Friction Behavior ◽  
Accuracy Requirement ◽  
Precise Prediction ◽  
Friction Prediction

The piston ring-cylinder liner (PRCL) is one of the most important parts of marine diesel engines and contributes 25% to 50% of total friction loss. The lubrication simulation analysis of the PRCL system is a challenging task. Complete understanding and precise prediction of lubrication loads is a key to understanding the friction behavior of PRCL systems as the accuracy of the friction prediction depends upon precise prediction of lubrication loads. Therefore, this paper focuses on the gas pressure calculation which is the primary source of lubrication loads. The procedure presented combines the advantages of two mainstream methods to predict loads in the PRCL system. The result is a significant reduction in the computation time without compromising on accuracy. Firstly, a comparison of both approaches is presented which suggests that each technique has its limitations (one is time-bound, and one is accuracy-bound). Then, the results from both calculation methods are verified against literature and a parametric study is performed to identify the key structural parameters of PRCL system that affect the calculation efficiency. Finally, a correlation coefficient is introduced into the analysis to combine the two approaches which then identifies the conditions under which the use of the faster method becomes invalid and replaces it with the more accurate approach. This ensures optimum performance of the calculation procedure by switching between the fast and the accurate method depending upon the accuracy requirement under given conditions, thereby, simplifying the dynamic and lubrication model of PRCL systems. The study has direct implications for the tribological design of the PRCL interface.

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