A Boundary Lubrication Friction Model Sensitive to Detailed Engine Oil Formulation in an Automotive Cam/Follower Interface

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Rupesh Roshan ◽  
Martin Priest ◽  
Anne Neville ◽  
Ardian Morina ◽  
Xin Xia ◽  
...  
Keyword(s):  
Boundary Lubrication ◽  
Fuel Efficiency ◽  
Lubricant Additive ◽  
Friction Model ◽  
Operating Conditions ◽  
Valve Train ◽  
Engine Oil ◽  
Contact Friction ◽  
Boundary Lubrication Friction ◽  
Base Oil

Theoretical studies have shown that in severe operating conditions, valve train friction losses are significant and have an adverse effect on fuel efficiency. However, recent studies have shown that existing valve train friction models do not reliably predict friction in boundary and mixed lubrication conditions and are not sensitive to lubricant chemistry. In these conditions, the friction losses depend on the tribological performance of tribofilms formed as a result of surface–lubricant additive interactions. In this study, key tribological parameters were extracted from a direct acting tappet type Ford Zetec SE (Sigma) valve train, and controlled experiments were performed in a block-on-ring tribometer under conditions representative of boundary lubrication in a cam and follower contact. Friction was recorded for the tribofilms formed by molybdenum dithiocarbamate (MoDTC), zinc dialkyldithiophosphate (ZDDP), detergent (calcium sulfonate), and dispersant (polyisobutylene succinimide) additives in an ester-containing synthetic polyalphaolefin (PAO) base oil on AISI E52100 steel components. A multiple linear regression technique was used to obtain a friction model in boundary lubrication from the friction data taken from the block-on-ring tribometer tests. The model was developed empirically as a function of the ZDDP, MoDTC, detergent, and dispersant concentration in the oil and the temperature and sliding speed. The resulting friction model is sensitive to lubricant chemistry in boundary lubrication. The tribofilm friction model showed sensitivity to the ZDDP–MoDTC, MoDTC–dispersant, MoDTC–speed, ZDDP–temperature, detergent–temperature, and detergent–speed interactions. Friction decreases with an increase in the temperature for all ZDDP/MoDTC ratios, and oils containing detergent and dispersant showed high friction due to antagonistic interactions between MoDTC–detergent and MoDTC–dispersant additive combinations.

Demonstration of the Benefits of SAE 30 Stationary Gas Engine Oil in Full Scale Engine Tests

2021 ◽  
Author(s):  
Thijs Schasfoort ◽  
Zoe Fard ◽  
Torsten Gehrmann ◽  
Steffen Hollatz
Keyword(s):  
Positive Impact ◽  
Fuel Efficiency ◽  
Test Methods ◽  
Operating Conditions ◽  
Engine Oil ◽  
Gas Engine ◽  
Fuel Consumption Rate ◽  
Efficiency Performance ◽  
Endurance Testing ◽  
Efficiency Test

Abstract This paper evaluates the benefits of an SAE 30 monograde stationary gas engine oil (SGEO) in comparison with SAE 40 monograde SGEOs with the focus on two main areas. First, to demonstrate and quantify the positive impact of lower viscosity on the fuel consumption rate, and second to demonstrate the faster lubrication of hard to reach points in the engine during startup. The current industry recognized fuel efficiency test methods for passenger car and on-road diesel engine sectors are not suitable for evaluating the fuel efficiency performance of a gas engine oil because of the significant differences in fuel type, engine operating conditions, and oil formulations. This paper, therefore, describes comparative studies of three different gas engine oils in a modern MAN E3262 E302 gas engine that was carefully adapted and fully instrumented. The performance of each oil with respect to fuel efficiency was assessed in an extensive program comprising endurance testing, stationary tests on various load/speed points and dynamic tests running the engine fired as well as non-fired (motored). Another part of the test program explores the lubrication of hard to reach points in the engine, e.g. valve guide. The paper describes how the SAE 30 monograde oil results in faster lubrication of these parts during startup in comparison with the SAE 40 oils.

Experimental and Theoretical Study of Instantaneous Engine Valve Train Friction

2003 ◽  
Vol 125 (3) ◽  
pp. 628-637 ◽  
Author(s):  
Riaz A. Mufti ◽  
Martin Priest
Keyword(s):  
Engine Speed ◽  
Gasoline Engine ◽  
Elastohydrodynamic Lubrication ◽  
Friction Model ◽  
Friction Torque ◽  
Operating Conditions ◽  
Valve Train ◽  
Friction Modifier ◽  
Timing Belt ◽  
Economy Benefit

A new method has been developed to directly measure valve train friction as a function of crank angle using specially designed timing belt pulley torque transducers fitted to the inlet and exhaust camshafts of a single-cylinder gasoline engine. Simultaneous and instantaneous friction torque of both the inlet and exhaust camshafts at any engine speed can be measured, with no apparent detrimental effect of timing belt loading on the output reading. Experiments are reported for valve train friction at a range of motored engine operating conditions with different lubricant formulations, with and without a friction modifier. These are compared with the predictions of an existing valve train friction model based upon elastohydrodynamic lubrication theory. Measured friction decreased with increasing engine speed but increased with increasing oil temperature and the fuel economy benefit of friction modifiers was observed. The model yielded similar magnitudes of friction at medium engine speeds and above but predicted much lower friction with high oil temperatures at low speed. Comparison of theory and experiments also suggests that some oil may leak from hydraulic lash adjusters during the cam event with a consequent reduction in geometric torque.

Predictions of Rotordynamic Performance for Electric Turbocompound

2012 ◽  
Author(s):  
Keun Ryu ◽  
Augustine Cavagnaro
Keyword(s):  
High Speed ◽  
Fuel Efficiency ◽  
Element Model ◽  
Operating Conditions ◽  
System Level ◽  
Engine Oil ◽  
Storage Device ◽  
Prototype Development ◽  
Linear And Nonlinear ◽  
Type Motor

An electric turbocompound (ETC) system for heavy duty diesel engines offers significant system level benefits, such as improved fuel efficiency and reduced NOx emissions with a lower CO2 footprint. Presently, a high speed switched reluctance type motor/generator is integrated into a turbocharger shaft between the turbine and compressor wheels. The motor assists rapid acceleration of the turbocharger shaft, thereby rendering faster transient response. At steady or over-boost operating conditions, the generator provides electric power which can be used directly or stored in an on-board storage device. ETCs operate at high rotational speeds and, if equipped with fluid film bearings, use pressurized engine oil to lubricate the bearings (journal and thrust). This paper presents comprehensive predictions of the linear and nonlinear shaft motions of an ETC supported on floating ring bearings. A rotor structural finite element model integrates the floating ring bearing model for prediction of the rotor-bearing system (RBS) linear and nonlinear forced responses under actual operating conditions. Predictions show a complex rotordynamic behavior of the RBS with large amplitude subsynchronous motions over a wide speed range. However, the subsynchronous whirl motions reach a limit cycle enabling continuous operation without system failure. Most importantly, stiffness of the lamination stack mounted on the shaft has a significant effect on the amplitude and frequency content of the shaft motion. The present analysis effectively aids to accelerate ETC prototype development with increased reliability and product troubleshooting.

scholarly journals A Comprehensive Numerical Study on Friction Reduction and Wear Resistance by Surface Coating on Cam/Tappet Pairs under Different Conditions

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 485
Author(s):  
Bugao Lyu ◽  
Xianghui Meng ◽  
Rui Zhang ◽  
Yi Cui
Keyword(s):  
Wear Resistance ◽  
Internal Combustion Engines ◽  
Numerical Study ◽  
Fuel Efficiency ◽  
Friction Reduction ◽  
Valve Train ◽  
Friction Loss ◽  
Contact Friction ◽  
Asperity Contact ◽  
Dlc Coatings

As a vital component in the valve train of internal combustion engines (ICEs), the cam/tappet pair undergoes high mechanical and thermal loads and usually works in a mixed and boundary lubrication regime. This leads to considerable friction loss and severe surface wear. Currently, the applications of diamond-like carbon (DLC) coatings for automotive components are becoming a promising strategy to reduce the friction and lower the wear. However, the practical performance of the coating is related to many factors, including friction coefficient, thermal properties, load conditions, and surface topography. In order to investigate these factors and successively improve the fuel efficiency and durability of the cam/tappet pair, a comprehensive multi-physics analytical model considering the mechanical, thermal and tribological properties of DLC coatings is established in this paper. Simulations are carried out for the coated as well as the uncoated cam/tappet conjunctions with different roughness at various ambient temperatures. The results show that both the fluid and asperity contact friction for the coated cam/tappet conjunction are significantly reduced due to their favourable characteristics. As a result, the friction loss of the coated cam/tappet pair is noticeably lower by almost 40% than that of the uncoated, despite a slightly higher asperity contact. In addition, the wear resistance of DLC coatings is also impressive, although the wear condition becomes progressively more severe with the increasing ambient temperature. Moreover, the roughness has complex effects on the friction and wear under different conditions.

How much mixed/boundary friction is there in an engine — and where is it?

2019 ◽  
Vol 234 (10) ◽  
pp. 1563-1579 ◽  
Author(s):  
RI Taylor ◽  
N Morgan ◽  
R Mainwaring ◽  
T Davenport
Keyword(s):  
Boundary Lubrication ◽  
Mixed Boundary ◽  
Operating Conditions ◽  
Valve Train ◽  
Friction Modifier ◽  
Direct Measurements ◽  
Full Discussion ◽  
Engine Friction ◽  
The Individual ◽  
The Impact

Automotive engines are believed to operate predominantly in the hydrodynamic regime, as evidenced by the (1) the successful strategy of reducing lubricant viscosity to reduce engine friction and improve vehicle fuel consumption, and (2) for most engine operating conditions, direct measurements of engine friction (either motored or fired) find that engine friction increases with increasing engine speed. However, certain components in an engine are known to operate mainly in the mixed/boundary lubrication (e.g. the valve train) and other components (such as the piston rings) operate in the mixed/boundary regime for a portion of the time. In order to quantify the amount of mixed/boundary lubrication in an engine, and in the individual components of the engine, motored and fired friction tests have been carried out for a range of lubricants (of differing viscosity grade, and with/without friction modifier additives). A full discussion of the implications of this work, which includes the impact of fuel dilution and “running-in” is included with insights given into how the work reported here guides the development of future fuel-efficient engine lubricants.

scholarly journals Tribological interaction of plasma functionalized CaCO3 nanoparticles with zinc and ashless dithiophosphate additives

2021 ◽  
Author(s):  
Kimaya P Vyavhare ◽  
Richard B. Timmons ◽  
Ali Erdemir ◽  
Pranesh B. Aswath
Keyword(s):  
Boundary Lubrication ◽  
Internal Combustion Engines ◽  
Strong Support ◽  
Chemical Vapor ◽  
Lubricant Additive ◽  
Engine Oil ◽  
Wear Protection ◽  
Low Concentrations ◽  
Surface Modified ◽  
Dialkyl Dithiophosphate

Abstract Surface-modified CaCO3 nanoparticles, synthesized through plasma-enhanced chemical vapor deposition (PECVD), were employed to improve lubricant additive technology for internal combustion engines via reduction and/or replacement of additives, such as zinc dialkyl dithiophosphate (ZDDP), in engine oil. Various oil formulations were prepared with functionalized CaCO3 nanoparticles, in combination with ashless dialkyl dithiophosphate (DDP) and ZDDP at low concentrations of phosphorus. Tribological test results indicate synergistic interaction of functionalized CaCO3 nanoparticles with ZDDP and DDP, providing enhanced friction and wear performance under boundary lubrication. A comparative study of the tribo-surfaces morphology and chemistry was assessed via atomic force microscopy and X-ray absorption near-edge spectroscopy. Improved wear protection by functionalized CaCO3BM (borate and methacrylate coated) nanoparticles under boundary lubrication was attributed to the formation of calcium and boron-rich 50–80 nm thick tribofilms on the worn surfaces. XANES results revealed that plasma functionalized CaCO3 nanoparticles interact with ZDDP and DDP and participate in tribofilm formation through tribo-chemical reactions and metal cation supply to form stable and wear-resistant tribofilms. These results provide strong support for the potential application of plasma functionalized CaCO3 nano-additives to reduce the concentration of harmful P-based additives in automotive lubricants.

Experimental and Theoretical Evaluation of Simultaneous Piston Assembly, Valve Train and Engine Bearing Friction in a Fired Engine

2005 ◽  
Author(s):  
Riaz A. Mufti ◽  
Martin Priest
Keyword(s):  
Gasoline Engine ◽  
Fuel Efficiency ◽  
Research Work ◽  
Friction Model ◽  
Valve Train ◽  
Analysis Model ◽  
Theoretical Evaluation ◽  
Component Design ◽  
Analytical Tools ◽  
Piston Assembly

Engineers are constantly challenged to develop advanced products to meet more demanding emissions and fuel economy targets. In the past 20 years the automotive industry has greatly improved vehicle fuel efficiency by detailed engine component design improvement and formulating compatible lubricants, heavily relying on the computer based analytical tools. The sophistication and other complexity of these tools are growing rapidly. It is therefore important that the models, on which these techniques are based, are validated and continually improved by experimental techniques. For validating a predictive friction model, very accurate friction force data is required. Truly representative results can only be obtained if experiments are undertaken on a real fired engine and the friction loss in each component is recorded. The main aim of this research work is to validate an engine friction mathematical model called FLAME (Friction and Lubrication Analysis Model for Engines), over a range of load, engine speeds and lubricant temperatures, using 0W20 lubricant. The model was developed in a separate study and comprises of three parts, addressing each of the main tribological components (piston assembly, valve train and engine bearings). The validation was carried out by characterising the frictional losses generated from the major tribological components of a real fired engine. This was achieved by experimentally determining simultaneously the power loss in each component of a single cylinder, four valve, Ricardo Hydra gasoline engine under fired conditions.

scholarly journals Non-Newtonian mixed thermo-elastohydrodynamics of hypoid gear pairs

2017 ◽  
Vol 232 (9) ◽  
pp. 1105-1125 ◽  
Author(s):  
M Mohammadpour ◽  
S Theodossiades ◽  
H Rahnejat ◽  
D Dowson
Keyword(s):  
Fuel Efficiency ◽  
Transmission Efficiency ◽  
Operating Conditions ◽  
Predictive Analysis ◽  
Hypoid Gear ◽  
Shear Rates ◽  
Contact Loads ◽  
Harmful Emissions ◽  
Vehicle Fuel Efficiency ◽  
Hypoid Gear Pairs

Transmission efficiency is the main objective in the development of vehicular differential systems, comprising hypoid gear pairs. The overall aim is to contribute to improved vehicle fuel efficiency and thus levels of harmful emissions for modern desired eco-drive axles. Detailed predictive analysis plays an important role in this quest, particularly under realistic operating conditions, comprising high contact loads and shear rates. Under these conditions, the hypoid gear pairs are subject to mixed non-Newtonian thermo-elastohydrodynamic conditions, which is the approach undertaken in this paper. Such an approach for hypoid gear pair has not hitherto been reported in the literature.

The effects of DLC-coated journal on improving seizure limit and reducing friction under engine oil lubrication

2021 ◽  
pp. 146808742110129
Author(s):  
Hidemi Ogihara ◽  
Takumi Iwata ◽  
Yuji Mihara ◽  
Makoto Kano
Keyword(s):  
Internal Combustion Engines ◽  
Fuel Efficiency ◽  
Internal Combustion ◽  
Engine Oil ◽  
Combustion Engines ◽  
Main Bearing ◽  
Dlc Coating ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
Reduce Emissions

Internal combustion engines have been improved markedly in recent years through efforts to conserve resources, reduce emissions and improve fuel efficiency. In this regard, the authors have been working to reduce friction and improve the seizure properties of the crankshaft main journal and main bearing. These mechanical components of internal combustion engines incur large friction losses. In order to reduce friction, journals have been coated with a diamond-like carbon (DLC) coating, which has been reported to reduce friction in the fluid lubrication regime in recent years. Another current issue of journals and bearings is the need to improve seizure resistance. Therefore, these properties were evaluated for material combinations of aluminium alloy bearings and DLC-coated journals, which have low affinity. The results revealed that friction was reduced under a fluid lubrication regime and seizure resistance was improved under a mixed lubrication regime.

Boundary Friction for a Line Contact Model: An Empirical Approach

2015 ◽  
Vol 642 ◽  
pp. 8-12
Author(s):  
William W.F. Chong ◽  
Miguel de La Cruz
Keyword(s):  
Steel Plate ◽  
Friction Model ◽  
Boundary Friction ◽  
Slider Bearing ◽  
Base Oil ◽  
Atomic Force ◽  
Alternative Approach ◽  
Nanoscale Friction ◽  
Friction Measurements ◽  
Good Agreement

The paper introduces an alternative approach to predict boundary friction for rough surfaces at micros-scale through the empirical integration of asperity-like nanoscale friction measurements. The nanoscale friction is measured using an atomic force microscope (AFM) tip sliding on a steel plate, confining the test lubricant, i.e. base oil for the fully formulated SAE grade 10w40. The approach, based on the Greenwood and Tripp’s friction model, is combined with the modified Elrod’s cavitation algorithm in order to predict the friction generated by a slider-bearing test rig. The numerical simulation results, using an improved boundary friction model, showed good agreement with the measured friction data.

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