发动机活塞销孔偏心对摩擦磨损影响的研究

对不同发动机运转工况及不同销孔偏心进行了发动机试验和活塞动力学模拟对比研究。研究结果表明:柴油机活塞接触压力对偏心量的敏感程度要高于汽油机活塞,小偏心量往往会产生较大的裙部接触压力,而随着偏心量增大,裙部最大接触压力会逐渐减小,但当偏心量增大到一定程度后,裙部最大接触压力反而会有增大趋势;活塞主推力面累积磨损载荷增长主要发生在做功行程前半段,在排气和进气行程几乎没有增加,次推力面累积磨损载荷增长则主要发生在排气行程中间时刻,在进气行程几乎没有增加。销孔中心改变导致活塞质心位置发生了改变,引起了相关性能改变,通过对某汽油机活塞销孔偏心进行优化,活塞裙部主推力侧磨损载荷由27.46MW/m~2变为1.12MW/m~2,降低了近25倍,解决了活塞裙部磨损问题。模拟结果与试验结果十分吻合。

Study on the Influence of Piston Pin Hole Offset on Piston Friction and Wear

The effect of different engine operating conditions and piston pin hole offset parameters on piston friction and wear was compared by the engine bench test and piston dynamical simulation. Results show that the sensitivity of the contact pressure on diesel engine piston to the piston pin hole offset is higher than that of gasoline engine piston. Smaller offset will often make the piston skirt produced larger. With the increase of pin hole offset, the maximum contact pressure on piston skirt will gradually reduce, but when it increases to a certain degree, the maximum contact pressure will have a reverse trend to increase. The cumulative wear load growth of piston skirt main thrust side occurs mainly in the first half of the power stroke, almost no increase in the exhaust stroke and intake stroke. The cumulative wear load growth of piston skirt secondary thrust side occurs mainly in the middle of the exhaust stroke, but almost no increase in the intake stroke. The change of pin hole center leads to the change of piston mass center, which will change the engine related performance. By optimizing the pin hole offset of the gasoline engine, the wear load on the piston skirt thrust side is changed from 27.46 MW/m2 to 1.12 MW/m2, which is almost 25 times compared with the original one. This simulation can solve the problem of piston skirt wear, and the results agree with the experimental date very well.