内燃机活塞环开口重叠的摩擦机理分析

根据曲轴扭矩传递原理得到了相关数学模型，进而计算了连杆轴颈偏转和活塞往复转动；在考虑燃气压力、往复惯性力和流体摩擦力，以及转动摩擦阻力矩、转动惯性力矩和气体摩擦力矩作用的基础上，提出了活塞环随活塞同步转动的判别条件，建立了活塞环相对转动的分析模型．结果表明：在内燃机工作循环中，连杆轴颈的正、负偏转引起活塞往复转动，在燃气爆发位置附近产生最大偏转和转动幅值；在少量曲轴转角区间内附着力矩小于转动阻力矩，此时活塞环不能与活塞保持同步而是与活塞之间发生相对转动；第二气环转动角度大于第一气环，当2个气环的开口转到相同位置时，活塞环出现开口重叠．

Analysis on Friction Mechanism of Superposition of End Gap of Piston Ring in Internal Combustion Engine

The deflection of crankpin and reciprocating rotation of piston were calculated according to the mathematic model based on the torque transmission theory of crankshaft. The discriminant of synchronous rotation of piston ring with piston was put forward. Moreover, the analytical model about the opposite rotation of the piston ring was established, by taking into account various forces including combustion gas pressure, liquid friction, and reciprocating inertia force, and various moments including rotational friction, rotational inertia, and gas friction moment. It was found that the positive and negative deflections of the crankpin resulted in the reciprocating rotation of the piston in the IC engine work cycles. The peak values of the deflection and rotation were near to the crank angle position in deflagration. Because the clingy moment of the compression ring was less than the rotational resistance moment in a few section of the crank angle, it was unable for the ring to keep synchronism with the piston and hence rotated opposite to the piston. Rotation angle of the second compression ring was larger than that of the first ring. The superposition of the end gaps of the two compression rings occurred when they turned to the same angle position.