助力车发动机在出厂前,不论生产厂是否进行过冷磨、热磨,其各个摩擦副均未达到最佳的配合状态。尤其是活塞环与气缸孔、滑动轴承与轴、主动齿轮与从动齿轮的啮合面等。根据科学家多年的研究和经验积累,机械产品的故障率在使用过程中呈盆形曲线(见图)。在使用初期阶段,由于摩擦副尚未达到最佳配合状态,而磨损较快,如果再使用不当,会加剧磨损,而使故障频繁出现;当使用到一定时间之后,摩擦副达到最 Bicycle engine before leaving the factory, regardless of whether the factory had been cold mill, hot mill, the friction pair did not achieve the best with the state. In particular, the piston ring and the cylinder bore, sliding bearings and shaft, the driving gear and driven gear meshing surface. Based on years of research and experience accumulated by scientists, the failure rate of mechanical products shows a basin-shaped curve during use (see figure). In the early stages of use, the friction pair has not yet reached the best fit state, and wear faster, if re-used improperly, will exacerbate the wear and tear, and make frequent failures; when used for a certain time, the friction pair to achieve the most