| There are variety types of friction pair components and systems in the Internal Combustion Engine (ICE), and these tribological behaviors have a significant impact on the working performance and operation efficiency, and also have a great influence on the engine's performance of power, fuel consumption, emissions, stability and service life, and so on. With the ICE developing to the direction of energy saving, high efficient and environmental protection, it puts forward higher requirements to the friction pairs. This article expands the tribology research of ICE to the micro-scale, introduces Laser Surface Texturing(LST) technology which breaks through the bottleneck of traditional processing techniques and this paper researches from the new laser micro-manufacturing equipment and technology, lubrication and friction theory, friction and wear experiment, and engine performance test to explore the application of laser surface texture technology on the cylinder (bore), camshaft and other key friction pairs to achieve active optimum design and manufacture on the surface morphology of friction pair in order to achieve the comprehensive purpose of improving lubrication, reducing friction and wear, and improving the engine's performance, to lay the foundation for the formation of independent intellectual property rights of new surface texturing technologies on high-performance engine's friction pairs.Firstly, an analytical mixed lubrication model of cylinder liner-piston ring was established, synthetically considering the coupling effect between surface roughness of contacts area (non-texturing area) and micro-texturing, and introducing the average Reynolds equation, the film thickness equation and the equation of asperity contacts, etc. The presented model can most truly reflect the engine's tribological behavior in working cycle. The simulation results show that near the Top Dead Center (TDC) and the Below Dead Center (BDC) areas, the friction pair is under the mixed lubrication state, and the asperity contact plays a dominant role in balancing external load and the peak friction force appears. However, micro-dimples formed by LST can still bring some appropriate hydrodynamic lubrication effect. At the other areas except TDC and BDC, hydrodynamic lubrication effect is more obvious. But through the laser surface texturing it can still form some fluid film pressure, and greatly reduce the friction force of mixed lubrication region. The surface roughness of cylinder liner has a great influence on the cylinder liner-piston ring lubrication conditions. The minimum oil ratio increases with the decreasing surface roughness of the cylinder liner, while the dimensionless friction force and friction power decrease. The study of optimization design on the parameter of the surface morphology of cylinder liner shows that there are optimal parameters of micro-morphology on cylinder to achieve the best lubrication and friction performance. At the same time as the engine speed and load increase, the minimum oil ratio decreases and the dimensionless friction increase.For meeting the requirements of surface texturing processing on cylinder bore of the engine block; new LST processing equipment with rotating laser head was developped. It applied unique water-cooled laser resonator cavity and frequency doubling technology which can reduce the heat loss of cavity and increase laser output power. A new rotating laser head was designed which ensure auxiliary gas reliable sealing and the light path flow unblocked. By the designing of software and hardware of quick response control system, achieved high precision joint coordination control between single laser pulse and rotary motion of mechanical system. Maximally reduce the thermal effects side effects by laser micro-processing and improve quality and efficiency of micro-machining. And the proper laser control parameters range of the LST micro dimple and groove's morphology were determined by calibration on the LST processing equipment and based laser testing and other research.The experiment of the effects of different surface texture morphology on the lubrication and friction properties was studied in the LST samples, using the MMW-1A universal friction and wear test equment. The study found that the friction coefficient of the surface texturing sample can reduced by 30%-50%compared with the non-texturing sample, and the wear of the sample surface has also been effectively improved.Finally, the performance tests with LST cylinder liner (bore), camshaft of fuel pump were conducted. The results showed that the power performance of a single-cylinder diesel engine remained unchanged with LST cylinder liner, and the fuel consumption inproved about 1-1.54%, smoke decreased 53-65.3%, gas leakage declined 26.9-30.7%, the mechanical efficiency increased about 2.3%, compared to the original engine with plat-honing.The LST cross-groove is clear, uniform, and its depth is consistent, the working surface is more flat, which can increase the cylinder's bearing area, its cylinder liner surface assessment parameters were better than plat-honing, thereby improve the tribological properties of the cylinder liner. Another experiment results of a gasoline engine with LST cylinder bore show that it can maintain the power performance, while reducing fuel consumption 3%-4.7%, significantly improving the engine oil consumption nearly 56%.The engine durability test showed the wear value of LST nodular cast iron camshaft is only about 1-2μm, reaching the same level of steel camshaft, which confirmed that LST can improve the lubrication of camshaft, and effectively increase its wear resistance.
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