A Dynamic Deformation based Lubrication Model between the Piston Rings and Cylinder Liner

The piston ring-cylinder liner friction pair is one of the most important friction pair in IC engines. In previous modelling studies, most researches were carried out based on a hypothesis that the inner surface of liner is an ideal cylindrical shell without considering the effects of dynamic deformation on oil film distribution. To investigate the potential influences of structural deformations on tribological behaviors of cylinder assemblies, the dynamic deformation of liner surface was obtained by FEM-based dynamic simulation, and then introduced into the lubrication model. Different from the traditional lubrication model where the pressure stress factor and shear stress factor are regarded as constant, this paper calculated these factors in real time by numerical integration to achieve more realistic simulation results. This study shows that the friction force obtained from the improved model manifests obvious fluctuations, and shows a significant reduction compared to original model

Application of Surface Treatments to Improve Fuel Efficiency of Internal Combustion Engines

To improve the tribological performance of contacting surfaces, different surface modification methods can be employed. Surface texturing and surface coating are examples of viable techniques developed for this purpose. Surface texturing involves creating micropatterns on the contacting surfaces while surface coating requires depositing a thin layer of a suitable material on the surface(s) to improve the component’s friction and wear characteristics. The performance of textured surfaces is affected by the geometric characteristic of textures.When dealing with surface coating parameters, the parameters of interests are the type of coating materials and their thicknesses. The current study aims to experimentally study the friction variation as a result of surface texturing and surface coating on the piston rings by using a custom made piston cylinder machine. Of particular interest are their running-in behavior and the associated transient friction characteristics. A new type of texturing is also proposed for the application in piston oil control rings to reduce engine friction. Experimental studies are conducted to compare their performance of grooves with three structural angles (0, 30 and 60 degrees) and two different depths (5 and 10 microns). The optimum texture with grooves parallel to the sliding direction and depth of 5 microns was found to yield a 10% reduction in the friction force. Combination of the texturing and coating showed 12.5% improvement in frictional behavior when compared to cases when only one of them was applied

Plasma texturing for enhanced tribological performance of cast iron

Cathodic plasma electrolysis (CPE) was used to create surface texturing on gray iron samples, which could reduce the friction and increase the wear resistance. During the treating process, cast iron sample served as a cathode where the plasma discharging occurred, increasing the surface hardness and leaving an irregular array of micro craters on the surface. Modified surface morphology was determined from scanning electron microscope (SEM) and surface profiler. Recessed and protruded surface textures were observed when the CPE was applied at low and high voltages, respectively. Pin-on-disk tribotests were conducted on CPE-treated samples and untextured sample. The friction of as-treated samples could be reduced in boundary lubrication regime at low sliding speed due to the ability to store lubricant. Besides that, the surface texture generated extra hydrodynamic pressure that separated two sliding surfaces, increased the oil film thickness and accelerated the transition from boundary to mixed lubrication at high sliding speeds

Development of a mathematical tool to predict engine in-cylinder friction

A better fuel-efficient automotive engine is more sought-after to promote greener environment in the era of global warming. One of the factors to cause the increase of fuel consumption in vehicles is the frictional loss within an internal combustion engine. In this study, the focus is to determine the tribological behaviour between the piston top compression ring and the engine cylinder liner for a full engine cycle. Mathematical models are derived from a 1-D Reynolds equation, assuming Half-Sommerfeld and Reynolds boundary conditions. Greenwood and Tripp rough surface contact model is applied to predict frictional properties along the ring-liner contact, considering viscous and boundary friction. It is found that the Half-Sommerfeld boundary condition predicts minimum lubricant film thickness that correlates well with literature data. However, the friction force predicted by the Reynolds boundary condition along dead centres correlates better with literature data. With friction along the cylinder liner dead centres being very significant, it is, therefore, suggested that the Reynolds boundary condition be the better mathematical model in studying the piston ring-liner tribological conjunction

Modeling of Surface Roughness in Honing Processes by Using Fuzzy Artificial Neural Networks

Honing processes are abrasive machining processes which are commonly employed to improve the surface of manufactured parts such as hydraulic or combustion engine cylinders. These processes can be employed to obtain a cross-hatched pattern on the internal surfaces of cylinders. In this present study, fuzzy artificial neural networks are employed for modeling surface roughness parameters obtained in finishing honing operations. As a general trend, main factors influencing roughness parameters are grain size and pressure. Mean spacing between profile peaks at the mean line parameter, on the contrary, depends mainly on tangential and linear velocity. Grain Size of 30 and pressure of 600 N/cm2 lead to the highest values of core roughness (Rk) and reduced valley depth (Rvk), which were 1.741 µm and 0.884 µm, respectively. On the other hand, the maximum peak-to-valley roughness parameter (Rz) so obtained was 4.44 µm, which is close to the maximum value of 4.47 µm. On the other hand, values of the grain size equal to 14 and density equal to 20, along with pressure 600 N/cm2 and both tangential and linear speed of 20 m/min and 40 m/min, respectively, lead to the minimum values of core roughness, reduced peak height (Rpk), reduced valley depth and maximum peak-to-valley height of the profile within a sampling length, which were, respectively, 0.141 µm, 0.065 µm, 0.142 µm, and 0.584 µm.Peer ReviewedPostprint (published version

Effect Of Electroless Plating On Wear And Surface Friction Of Alsi Cylinder Liner By Mukridz Bin Md Mohtar Effect Of Electroless Plating On Wear And Surface Friction Of Alsi Cylinder Liner

A piston - liner wear simulator with a stroke length of 15mm is developed which can carry out testing at maximum speed of 500 rpm with temperature of 300°C. Aluminium-silicon (AlSi) alloy specimens are prepared from cast the AlSi alloy (ADC12) and cut to shape representing the circular profile of a 36mm diameter cylinder. The specimen is coated using electroless process with Ni-P-Cg-SiC composite coating of 35μm nominal thickness. The study covers the wear and friction measurement at 300 rpm and 200°C using the mineral oil SAE 40 and semi-synthetic oil SAE 5W-30. Wear measurement is evaluated progressively for 100 hours of the wear test using Alicona Infinite Focus G4 Microscope where the wear- depth, rate and volume together with the surface roughness are monitored. For the uncoated liners, the average roughness (Ra) decreases with time as the surface became smoother because of the surface peaks being removed during the experiment before it reaches a steady state. This trend is comparable to what have been obtained by previous researchers. The trends of the wear volume and wear depth for the uncoated liners are also very similar. The higher wear rate in the beginning before reaching steady state is comparable to the previous studies. Meanwhile, for the coated liner, the superior wear resistance of the Ni-P-Cg-SiC composite coating on the AlSi-alloy liner withstand only up to 40 hours of the wear test. Subsequently, a subsurface fatigue phenomenon is observed after 60 hours of the test which resulted in the exfoliation of some part of the coating film. In general, the highest wear loss is at dead centres compared to the middle stroke with the maximum wear depth for the coated liner is 14.4μm, followed by 6.4μm for the uncoated liner with SAE 40 lubrication and 6.3μm for the uncoated liner with SAE 5W-30 lubrication, respectively. For the piston ring which is harder than the uncoated AlSi-alloy liner, the wear depth is minimal. However, severe wear loss with a total wear depth of 315μm is observed for the piston ring of the coated liner due to rougher and harder Ni-P-Cg-SiC composite coating film. Measurement of the friction force shows that the differences between friction coefficient (μ) values at each location of the coated and uncoated liner specimens with different lubricant types are very small with the highest μ values is at dead centres which ranges between 0.18 to 0.19, while ranges between 0.10 to 0.11 at middle strokes. Unfortunately, the effect of the graphite particles as friction reducer for the coated liner is not observed in this study. In fact, the uncoated liner produces a lower μ value

The detection of adhesive wear on cylinder liners for slow speed diesel engine through tribology, temperature, eddy current and acoustic emission measurement and analysis

PhD ThesisThe research concerns the condition monitoring of cylinder liner of large bore diesel engines using various methodologies to identify the onset of scuffing. The reasons of scuffing, improved designs and operational processes to prevent its occurrence were discussed. The research focused on modeling the normal condition of the cylinder liner with sufficient lubrication and detecting the precursor of scuffing by reducing the lubrication. The four detection systems used on the test facilities and field tests of the cylinder liners used tribology, temperature sensor, eddy current sensor and acoustic emission sensor. Experimental assessment of eddy current sensor was conducted for insufficient lubricating oil conditions for different cylinder liner wall pressures using a specially designed test facility. Field tests of temperature sensor and eddy current sensor were carried out on a 800mm bore worn cylinder liner of a container ship in service. Field test of acoustic emission sensor was carried out on a high speed automobile engine. Scuffing detection by temperature sensing should be considered as the last safety barrier, as it registers the after effect of scuffing and solely depends on the localized condition and the material’s thermal status. Mounting eddy current sensors are considered intrusive. Four sensors per cylinder are needed, which are prone to damage by the rings when the liner wears out. Additionally, the sensors measure only small section of the rings and their lubrication condition. Acoustic emission analysis effectively detects onset of scuffing on the cylinder liners and the rings. Initial findings from the lab and the field test on a four stroke engine confirmed this. However, more field tests under various loading condition on a slow speed engine is needed to understand the various event alignment and the non-routine detection, such as scuffing. They can be coupled with thermocouples to serve as a secondary protection

Correlation analysis of biodegradable additives, temperature and loading toward tribology behaviour of musa aluminata balbisiana (MBS) oil

Identification of the effect of the tribological characteristics in lubricant application is a critical part of the experimental process. A correlation study is used to identify the effect of temperature, load and biodegradable additive on the coefficient of friction (COF) and specific wear (Ws) from the experimental data. Pearson correlation coefficient (r) and analysis of variance (ANOVA) are the statistical analysis used to identify the relationship between the parameters and the significant difference in response variable which are COF and Ws. Based on the result, there is a positive moderate linear relationship between temperature to both COF and Ws with a score of r between 0.354 to 0.676. In contrast, there is a negative linear relationship between load towards COF and Ws with a -0.285 to -0.460 score of r. There is approximately no correlation with the percentage of biodegradable additives respecting COF and Ws. The result also shows that there is no significant difference between COF and Ws using ANOVA testing with a p-value is more than 0.05. This work may facilitate improvements for other researchers to identify the variable in the experimental design proces

Tribological Behaviours Influenced by Surface Coatings and Morphology

Plasma electrolytic oxidizing (PEO) is an advanced technique that has been widely used in automotive industry to produce ceramic coatings on light metal components due to their high hardness, wear resistance, corrosion resistance and low friction coefficient. In this work, PEO process was used to produce a relatively thick (~20 μm) coating on A356 Al alloy for improving the wear resistance and tribological properties of the Al alloy. Effects of surface roughness and sliding velocity on the coefficient of friction (COF) of PEO coatings were particularly investigated in different tribological tests including low speed pin-on-disc tests, high speed pin-on-disc tests, and high speed piston ring on liner tests. Cast iron was used as reference material for comparison with PEO coatings. The research results indicated that the PEO coatings could have excellent tribological properties potential for linerless aluminium engine applications