Lubrication Theory And Experimental Investigation Of The Engine Cylinder Bore Surface With Laser Micro-texture

Cylinder bore-piston ring friction pair is one of the key friction pair of the engine,and the friction power consumption accounts for 50 ~ 60% of the engine. Laser micro texturing technology can effectively improve the lubrication performance of the cylinder bore-piston ring and the efficiency of the engine fuel, reduce friction and wear, achieve the target of energy conservation and emissions reduction. Based on a type engine application research, establish lubrication theory model, and the relationship of lubrication performance and texture morphology parameters were numerical simulated. Provide theoretical support for design engine test scheme.Processing experimental of laser micro texture was carried out, and the engine trailing and bench test for verify the theoretical results. The paper main contents are as follows.Considering the effect of time-dependent effect and gas pressure change in combustion chamber for the piston ring radius-directional pressure, establish lubrication model of cylinder bore-piston ring with micro-pits texture. Mathematical equations were dimensionless, use finite method for parameter discretization. Solute Reynolds equation by multigrid method, obtain the minimum oil film thickness and the friction force between the cylinder bore-piston ring. The study found that the micro-pit depth and density greatly influenced on the performance of friction pair lubrication, optimization of micro pit geometry parameters can significantly improve the lubrication performance of cylinder hole- piston ring.Carry out three series processing tests upon the cylinder bore laser micro texture technology. For play to the advantages of cylinder hole surface texture morphology,remove the interference of honing morphology, reduce the engine fuel consumption,the cylinder hole surface roughness parameter should be optimized before laser texture, carry out the mirror honing process experimental. Measure cylinder bore surface with the five key parameters, Rz≦2μm, Ra≦0.2μm and Rpk≦0.15μm,Rk≦0.4μm, Rvk≦1μm. The main research is about the influence of honing stones and honing pressure for the cylinder bore surface parameters. Honing stones and honing pressure effect on the surface of a cylinder hole parameters is remarkable,optimized parameters of the mirror honing; Second, the process of laser micro-texture was carried out. Results indicate that the single pulse energy, pulse number is the keyprocessing parameters, different material, coating and wavelength on the influence of geometric parameters of micro pit significantly; To remove bugle produced by the laser texture, reduce engine running-in time, avoid the abrasive wear, the post-processing of the cylinder hole was carried out. Optimization post-processing honing processing parameters by four factors two levels orthogonal method.Determine suitable post-processing parameters.For a certain type of four cylinder gasoline engine, process three different cylinder texture scheme prototype and carry on the trailing and bench test. Dimples morphology parameters impacts on the performance of engine power and fuel consumption were explored. The results showed that the texture density was 10% in central region and top dead center area of cylinder bore, the friction performance showed beneficial effects. Bench test indicates that compared with 24 hours oil consumption, two kinds of texture scheme is lower than the original engine, the oil consumption is reduced by 26.48%. The curve of engine fuel consumption characteristic found that, three kinds of texture engine is lower than the original in most operating conditions, especially the scheme with laser textured position in the top dead center and the central area, and micro-pit diameter of 70 mm, depth of 4 mm,texture density is 10%, the fuel consumption is decreased by 15%.