Computer simulation of piston-piston ring—cylinder liner coactions in combustion engines

Author(s):  
A Kaźmierczak
Author(s):  
Mohamed Kamal Ahmed Ali ◽  
Hou Xianjun ◽  
Richard Fiifi Turkson ◽  
Muhammad Ezzat

This paper presents a model to study the effect of piston ring dynamics on basic tribological parameters that affect the performance of internal combustion engines by using dynamics analysis software (AVL Excite Designer). The paramount tribological parameters include friction force, frictional power losses, and oil film thickness of piston ring assembly. The piston and rings assembly is one of the highest mechanically loaded components in engines. Relevant literature reports that the piston ring assembly accounts for 40% to 50% of the frictional losses, making it imperative for the piston ring dynamics to be understood thoroughly. This analytical study of the piston ring dynamics describes the significant correlation between the tribological parameters of piston and rings assembly and the performance of engines. The model was able to predict the effects of engine speed and oil viscosity on asperity and hydrodynamic friction forces, power losses, oil film thickness and lube oil consumption. This model of mixed film lubrication of piston rings is based on the hydrodynamic action described by Reynolds equation and dry contact action as described by the Greenwood–Tripp rough surface asperity contact model. The results in the current analysis demonstrated that engine speed and oil viscosity had a remarkable effect on oil film thickness and hydrodynamic friction between the rings and cylinder liner. Hence, the mixed lubrication model, which unifies the lubricant flow under different ring–liner gaps, is needed via the balance between the hydrodynamic and boundary lubrication modes to obtain minimum friction between rings and liner and to ultimately help in improving the performance of engines.


2021 ◽  
Vol 2074 (1) ◽  
pp. 012033
Author(s):  
Chen Peng

Abstract With the development of computer technology, computer simulation has become a powerful tool to carry out liner - piston ring wear experiment of Marine diesel engines. Turbocharged diesel engine is a typical multi-system and multi-level complex power plant. There are many factors that affect the piston change and wear speed of diesel engine in practical operation, and many factors are interrelated and influence each other. Marine diesel engine is the most important mechanical equipment in Marine engine room, which has a complex system structure. If the diesel engine fails, it will seriously affect the navigation safety of the ship. In order to reduce the loss of Marine diesel engine piston ring wear, it is necessary to rely on fault diagnosis technology for timely and reliable diagnosis and maintenance.


2019 ◽  
pp. 146808741989389 ◽  
Author(s):  
Ahmad Alshwawra ◽  
Henning Pasligh ◽  
Hauke Hansen ◽  
Friedrich Dinkelacker

Increasing the efficiency of internal combustion engines is of major interest for reduced greenhouse gas emission. A significant improvement potential is given with the reduction of friction losses. Here, especially the friction between the piston ring and the cylinder liner is of interest. This article describes a study with the target to enhance the piston ring–cylinder liner conformation through increasing the roundness of the deformed liner during the warm operation state. The approach is based on the assumption that a non-circular liner in the cold state can deform due to thermal and mechanical stresses toward a circular shape under typical hot operation conditions. To test this hypothesis, a computational model for a gasoline engine was built and simulated using advanced finite element methods. The simulation describes the deformation process of the liner from the thermal and mechanical stresses. First, the deformation of a circular liner is simulated, showing asymmetric deformations of up to 30 µm in the warm state for the cylinder positioned at the end of the four-cylinder bank. As experimental data are readily available, a comparison was possible, showing good agreement. Then, three liner configurations with non-circular shape in the cold stage are investigated. For an elliptically shaped configuration, a nearly circular-shaped liner is reached under typical operation conditions. This numerical approach shows the potential for reduced friction of the piston–liner arrangement within internal combustion engines. The planned next step is the extension of this method to three-dimensional shape aspects and the application to the geometry of our test engine of our lab where friction can be measured in detail with a floating-liner measurement system.


2016 ◽  
Vol 821 ◽  
pp. 166-171
Author(s):  
Peter Raffai ◽  
Pavel Novotný ◽  
Jozef Dlugoš

The continuously tightening regulations limiting the amount of exhaust gas components of internal combustion engines force the manufacturers to further increase the effectivity of their power units. Due to the already relatively highly-developed state of engines result in the need of research and development of even smaller engine parts – e.g. piston rings. The main aim of this project was to develop a tool for the computer simulation of the behavior of the piston ring pack, which could aid the optimization process of the piston ring pack towards lowered friction losses.


Author(s):  
Ana López Rodríguez ◽  
Anders Vølund ◽  
Peder Klit

A theoretical study of piston ring wear in large two-stroke engines is presented. Piston rings in combustion engines are manufactured with an initially defined shape of the surface contacting the cylinder liner. Further the ring surface working against the cylinder liner is coated with layers of ceramic materials to accommodate the running-in process. Most rings have a nonflat shape (parabolic) when delivered from the ring supplier. After running in which is typically many hours of operation( >1000 h) the ceramic layers are worn and the ring geometry is typically changed significantly by surface wear. It is shown in the present study that the geometry of the worn ring depends on the operation scheme of the engine. Both the load pattern and the order in which the loads are applied influences the final shape of the piston ring surface.


Author(s):  
A Kazmierczak

The research presented in this paper has shown that the physical aspects of interfacial phenomena, described by the total value of surface free energy and the values of its components, make it possible to select more suitable materials for sliding pairs. The total value of surface free energy depends on the molecular structure and the bonds characteristic of a given material, and determines its hardness. In order to reduce friction losses in a sliding pair that is being designed, it is proposed to match such materials for the pair in such a way that the surface of one of them has a high sum of surface free energy components originating from van der Waals interactions, while the other material's surface has a possibly low value of the sum. Furthermore, proper values of the components of surface free energy ensure proper wettability with lubricating oil. In order to minimize friction in a sliding contact, the element with the larger surface area (e.g. a cylinder sleeve) should have larger dispersion and van der Waals forces compared with those of the oil, while the element with the smaller area (e.g. a piston ring) has to have smaller (as low as possible) dispersion and van der Waals forces compared with those of the lubricating oil. Thus a basis for reducing friction losses, particularly during mixed friction and boundary friction, has been created. Pursuing the practical goal of this research, a new cylinder liner sliding pair of a piston-ring—cylinder (PRC) set (in which the ring has a titanium nitride (TiN) coating and the cylinder liner has a surface layer with varying properties, applied by vacuum nitriding) of a piston packing ring—combustion engine was designed and made. The sliding pair can be used in self-ignition combustion engines and in spark-ignition engines. The sliding pair is the result of the research carried out as part of this paper, including tests in a tribotester and three-stage testing embracing numerical simulations, preliminary tests on the real object, and tests proper on the real object.


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