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The steam engine was the first practical means of producing mechanical power from the heat of combustion of a fuel, and its introduction was a vital factor in the progress of the Industrial Revolution. For many years the development of the steam reciprocating engine continued apace, but in the early years of the present century introduction of the steam turbine and internal combustion engine made available alternative methods of power production. From then on interest in the steam reciprocating engine tended to slacken and, although it has shown a number of notable improvements, far more spectacular advances have been made in other power units.

The Presidential Address to the Liverpool Engineering Society by Mr. Farthing (the salient points of which are reproduced in this issue) has particular bearing upon lubrication and especially on young lubrication engineers. Mr. Farthing stressed the very wide field open to young engineers and the difficulties associated with training in order to cover as wide a field as may be necessary. It is usually so important to gain a wide knowledge before one can specialise and this is certainly the case with lubrication engineers. One cannot begin to fully appreciate the intricacies of a lubrication system with all its accessory components lubricating and guarding, for example, a large motive power plant or rolling mill, until one has more than a mere working knowledge of the plant itself, the duties it must perform, how it performs them and the snags that arise which might be overcome by correct lubrication. In view of the fact that lubrication systems are just as important in a textile mill as in a power station or a large brick works, the almost impossible‐to‐achieve‐range of knowledge that would simplify the work of a lubrication engineer is very obvious. Fortunately, lubricating principles apply to most cases and knowing how to apply one's knowledge from basic principles is the key to success in this difficult profession.

A free-piston engine (FPE) is an unconventional engine that abandons the crank system. This paper aims to focus on a numerical simulation for the lubricating characteristics of piston rings in a single-piston hydraulic free-piston engine (HFPE).

A time-based numerical simulation program was built using Matlab to define the piston motion of the new engine. And a lubrication mode of piston rings was built which is based on the gas flow equation, hydrodynamic lubrication equation and the asperity contact equation. The piston motion and the lubrication model are coupled, and then the finite difference method is used to obtain the piston rings lubrication performances of the FPE. Meanwhile, the lubrication characteristics of the new engine were compared with those of a corresponding conventional crankshaft-driven engine.

The study results indicate that compared with the traditional engine, the expansion stroke of the HFPE is longer, and the compression stroke is shorter. Lubrication oil film of the new engine is thicker than the traditional engine during the initial stage of compression stroke and the final stage of the power stroke. The average friction force and power of the hydraulic free piston engine are slightly lower than those of the traditional engine, but the peak friction power of the FPE is significantly greater than that of the traditional engine. With an increase in load, the friction loss power and friction loss efficiency decrease, and with a decrease in equivalence ratio, the friction power loss reduces, but the friction loss efficiency decreases first and then increases.

In this paper, only qualitative analysis was performed on the tribological difference between conventional crankshaft engine and HFPE, instead of a quantitative one.

This paper contributes to the tribological design method of HFPE.

No social implications are available now, as the HFPE is under the development phase. However, the authors are positive that their work will be commercialized in the near future.

The main originality of the paper can be introduced as follows: the lubrication and friction characteristics of the new engine (HFPE) were investigated and revealed, which have not been studied before; the effect of the HFPE’s special piston motion on the tribological characteristics was considered in the lubrication simulation. The results show that compared with the traditional crankshaft engine, the new engine shows a different lubrication performance because of its free piston motion.

The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the service life.

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the Component Mode Synthesis (CMS) method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an elastohydrodynamic (EHD)-mixed lubrication model of the main bearings for the diesel engine is developed and researched with the finite volume method and the finite element method.

Obviously, the mixed lubrication of bearings is normal, while full hydrodynamic lubrication is transient. The results show that under the whole flexible block model, maximum oil film pressure, maximum asperity contact pressure and radial shell deformation decrease, while minimum oil film thickness increases. Oil flow over edge decreases, and so does friction loss. Therefore, coordination deformation ability of whole engine block is favorable to mean load. In the whole block model, friction contact happens on both upper shell and lower shell positions. In addition, average oil film fill ratio at the key position becomes smaller in the whole engine block model, and consequently increases the chances of cavitations erosion more. So, wearing resistance of both upper and lower shells and anti-cavitations erosion ability must be enhanced simultaneously.

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the CMS method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an EHD-mixed lubrication model of the main bearings for the diesel engine is built, which can predict the lubrication of journal bearings more accurately.

The following are the main points of interest to our readers from some of the papers presented at the Institute of Petroleum Summer Meeting at Llandudno last month.

The SATISFACTORY LUBRICATION OF Diesel engines presents some of the most difficult problems encountered by oil technologists. This is especially true of large marine engines, where, due to low speeds and high loads, it is difficult to establish fluid film lubrication. Cylinder lubrication is particularly difficult due to the high temperatures encountered. This problem is more difficult in two‐stroke engines than in four‐stroke engines as, in the former, there is no non‐working stroke during which it is easier to form an oil film on the cylinder walls. Pressure‐charged two‐stroke engines are the most difficult of all to lubricate satisfactorily. The problem is aggravated in engines operating on residual fuel due to the high sulphur content increasing corrosive wear, and to the abrasive ash forming constituents present in such fuels. In addition, the contaminating influences of partially burnt products of combustion on the crankcase oil have to be considered. The ever‐present risk of water leakage into the crankcase oil, either from condensation, or from leakage of the cooling system, influences and often restricts the use of otherwise beneficial additives.

Two papers were presented at a meeting of the Automobile Division in conjunction with the Lubrication Group of the Institution of Mechanical Engineers in London on 10th February, dealing with the lubrication of small 2‐stroke petrol engines. These were as follows:— “Problems Encountered in the Lubrication of small 2‐Stroke Engines,” by A. Towle, M.Sc., M.I.Mech.E., (Lubrizol International Laboratories), and “Influence of the Lubricating Oil on Some Operating Problems of the 2‐Stroke Gasoline Engine.” by D. W. Golothan, A.M.I.Mech.E. (“Shell” Research Ltd.). We give shortened versions of these papers. The Institution of Mechanical Engineers welcome written communications on these papers, which should reach them at 1 Birdcage Walk, Westminster, London, S.W.1., before 30th April. Those wishing to do this can obtain copies of the complete papers from the Secretary of the Institution. The meetings were held at short notice, but in spite of this about 150 members were present and the ensuing discussion showed the importance and interest in this subject.

Lubricants for four‐stroke motorcycles have traditionally been rebranded versions of those used for passenger car engine lubrication. Recent developments in passenger car engine oils with the intention of improving fuel utilisation efficiencies were not compatible with some of the specific requirements of four‐stroke motorcycle powertrain lubrication. The effect of using such lubricants on the various components of the motorcycle powertrain, including the engine, clutch, gearbox, starter system drive and back torque limiter is described. The subsequent development of a new specification specifically for use in four‐stroke motorcycles is described.

MOST modern internal combustion piston engines when under power have such a contented purr that many people contend that no serious lubrication problems of a technical variety remain to be solved, and that the only problems worth mentioning are those which are solely of an economic nature. Such views are, in their own way, flattering to the oil manufacturer who has striven hard, in conjunction with engine manufacturers, to bring these engines to a high pitch of reliability in a relatively short time. However, complacency in a world of change can be a dangerous thing.

Nanoparticles have been studied as additives to lubrication oils for reducing friction and wear. The purpose of this paper is to investigate the effect of nanofluid on engine oil and friction reduction in a real engine.

The nanoparticles were prepared using a high‐temperature arc in a vacuum chamber to vaporize the Ti metal, and then condensed into a dispersant to form the TiO₂ nanofluid, which was used as lubricant additive. Experiments were performed in both real engine running and test rig.

It was found that the engine oil with nanofluid additive with an ethylene glycol dispersant of nanoparticles, had gelled after 10‐h of engine running. The problem of oil gelation (jelly‐like) was solved by replacing the dispersant with paraffin oil. The engine oil with TiO₂ nanoparticle additive exhibited lower friction force as compared to the original oil. The experiment showed that a smaller particle size exhibits better friction reduction with particle size ranging from 59 to 220 nm.

The paper is restricted to findings based on the dispersed nanoparticles in fluid as additive for engine lubrication oil.

The test results are useful for the application of nanofluid additive for engine oil.

Most previous researches in this field were executed on tribotester, rather than the actual engine. This paper describes experimental methods and equipment designed to investigate the application of TiO₂ nanofluid as lubricant additive in internal combustion engine.