用双级谐波传动实现汽车发动机凸轮轴调相的研究

汽油机采用ＶＶＡ可改善怠速稳定性，提高中低速外特性扭矩，往往也有一定的节油效果。但ＶＶＡ机构研制难度很大，目前只有个别机构实用。作者研制了一个采用双级谐波传动的调相机构。试验表明，该机构能圆满实现调相功能，其长期工作的可靠性也经受了一定考验，考察了调相对发动机充量系数的影响，计算和实测结果基本一致，在全部转速范围内，充量系数都有提高。

Camshaft Timing Adjustment for Automotive Engines by Using Twin Harmonic Drives

Variable valve actuation(VVA)is one of the important developing subjects for automotive engines. The advantages of applying WA to gasoline engines include increasing the low speed torque, idle stability and sometimes improving the fuel economy. It is very difficult to develop a WA mechanism, and so far only two types of mechanisms have been used in production. In this paper, a new camshaft timing adjustment mechanism with twin harmonic drives which can be used in DOHC engines, is described and illustrated. The test showed that the mechanism could realize the expected functions satisfactorily . Also, the reliability of the mechanism for long-time working has been tested. To investigate the effects of intake timing adjustment on volumetric efficiency, a simulation calculation and measurement for a high speed gasoline engine were made and similar trend of the volumetric efficiency curves was obtained. It showed that the volumetric efficiency with optimum intake timing increases at all speed range.