Piston-liner System Low Friction Technology Applications Of Internal Combustion Engine And Research On Friction Force Measurement Method

Internal combustion engine is still the main power source in life. Withever-tensioning status of energy supply and the improvement of people’sconsciousness about environment protection, more and more criticalrequirements are put forward to the cost efficiency of engine. It isnecessary to tap the application potential of tribology design in the internalcombustion compared with high efficient combustion,electronic-controlled fuel injection, turbocharger technology etc. In thepaper, low friction techniques and methods are sought to reduce thefriction of the piston-liner system through theoretical simulation, frictiondesign optimization, sample processing and experimental verification, andthe friction measurement method of the piston-liner system is studied. Themain contents are as follows:1. Ttribological theory modeling of the piston-liner system andselection of the improvement schemes of the firction pairs. In the paper,the mixed lubrication modeling of the piston skirt-liner system is built based on the average Reynolds equation, rough surface asperity contactmodel and Reynolds boundary conditions, further consideration of theeffects of piston ring and connecting rod on the piston, the deformations atthe interface, the physical properties of lubricant. With the model underdifferent conditions, the relationships between tribological performanceparameters and crank angle are obtained in the entire working cycle,including the friction losses, oil film thickness, the asperity contact. Basedon this, the factors that affect the tribological properties of the piston-linersystem are compared and analyzed, and some possible frictionoptimization schemes are identified to reduce friction losses.2. Sample processing of the piston-liner friction pairs andexperimental verification. The samples for a specific engine are carried outbased on the friction optimization schemes. On the motored experimentalbench, the friction losses are tested and compared between before and afterfriction optimization, and the results show that the friction losses of thepiston-liner system are decreased more than10percent at all engine speeds.On the performance test bench, the specific fuel consumption is tested andcompared before and after friction optimization of multiple friction pairsincluding the piston-liner system, it is indicated that the fuel consumptionis lowed by an average of2.5percent. 3. Piston-liner system friction force measurement is achieved bywireless method. The wireless module is designed to solve thetransmission difficulty of connecting rod stress signal for IMEP method,and the friction force is successfully measured in motored/fired conditions.The trend of the measurement effects is similar with published datas andthe method is proved to be effective.4. Based on the studies above, engine tribological knowledge servicespecifications and models are obtained. Tribological knowledge service isthe effective way to improve the domestic tribology design of the internalcombustion engine. In the paper, the service models about thecold-motoring measurement of mechanical friction losses and the wirelessmeasurement of the friction force are studied.