李佳家

摘 要：汽车动力系统发展日益多元化，混合动力效降低燃油消耗及排放，同时有效的解决了纯电动汽车的里程焦虑问题，市场份额不断增加。由于混合动力发动机运行工况较传统发动机更窄，更多的利用自然吸气发动机的高效率区。但是，由于混动系统较传统动力增加了电动系统，为解决整车布置问题，需要匹配更紧凑的三缸发动机。本文基于四缸自然吸气发动机，研究三缸自然吸气发动机曲轴结构及平衡重的设计，并对曲轴的扭振进行评估。结果表明：采用四平衡重结构并将平衡重偏心30°布置，可以使得在最小力偶的情况下，实现旋转惯性力矩的平衡;该三缸自然吸气发动机曲轴扭振的最大振幅为0.070 deg，满足扭振评价要求。

关键词：汽油机;混合动力;曲轴平衡;平衡重

Abstract： The development of automobile power system is becoming more and more diversified. The hybrid efficiency reduces fuel consumption and emissions. At the same time， it effectively solves the mileage anxiety problem of pure electric vehicles， and the market share is increasing. Because the operation condition of the hybrid engine is narrower than that of the traditional engine， more efficient areas of the naturally aspirated engine are used. However， because the hybrid system adds an electric system to the traditional power， in order to solve the vehicle layout problem， it needs to match a more compact 3-cylinder engine. Based on the 4-cylinder naturally aspirated gasoline engine， this paper studies the design of crankshaft structure and balance weight of 3-cylinder engine， and evaluates the torsional vibration of crankshaft. The results show that the balance of the moment of inertia can be achieved with the minimum couple of forces by adopting the four balance weight structure and arranging the balance weight at an eccentricity of 30 °. The maximum amplitude of the crankshaft torsional vibration of the three cylinder naturally aspirated engine is 0.070 deg， which meets the requirements of torsional vibration evaluation.

Keyword： Gasoline engine; Hybrid Vehicle; Crankshaft balancing; Balance weight

前言

为了满足日益严格的油耗及排放法规，实现节能减排的目的，汽车动力系统呈现多元化发展的趋势，在未来很长一段时间内，内燃机仍然占据着汽车动力的主要份额，其将主要以混合动力及纯内燃机两种形式存在[1]。由于小排量三缸发动机，相对于四缸机，其运动部件更少，摩擦损失更低，相对来说效率更高;同时，自然吸气发动机热效率也较增压发动机更高;外形尺寸更紧凑，对于微小型车及混合动力车，发动机舱布置兼容性更好;与成熟的四缸机产品形成平台化，减少对现有生产制造系统的改造[1-2]。三缸机由于点火间隔、曲轴平衡特性等问题导致的NVH问题一直是限制其大范围应用的关键所在，但是，由于混合动力的应用，其工况运行范围较传统纯内燃机动力更窄，主要利用发动机的高效率区间，其振动问题得到很大程度的缓解。……