Study On Shaft Electromechanical Coupled Vibration Of Hybrid Construction Machinery Power System

Abstract:This thesis studies the vibration problem of hybrid system shafts coupled by the engine and electricity system, according to the structural characteristics of hybrid systems. The cause and characteristics of vibration are analyzed, which has a guiding significance for the design and vibration reduction of hybrid system shafts.Firstly, on the basis of a single crank model of the engine crankshaft, the reason why mechanical vibration coupling takes place was analyzed, and the vibration coupling equations were derived. The shafts made up of engine and motor were simplified into a two-degree-of-freedom system, according to the multi-power source characteristic of hybrid systems, and the equations of hybrid electromechanical coupling shafting vibration were obtained.Secondly, the models of the drive system, load system, dynamic coordination controller and the parallel hybrid system were built, respectively, according to the characteristics of hybrid construction machinery. The incentive force data of shaft was obtained through simulation, and that laid a foundation for the study of multi-body shaft vibration. Thirdly, the multi-body-dynamic model of electromechanical coupling vibration for the shaft of hybrid construction machinery was constructed and the simulation under different operating conditions was performed. The results show that the amplitude of torsional and horizontal bending vibration are slightly increased in the boost mode, and the harmonic and natural frequency are more, the amplitude of vertical and longitudinal vibration is increased. In the power generation mode, torsional and bending vibration are reduced, the longitudinal oscillation amplitude is increased.Finally, the experimental study of electromechanical coupling vibration for the shaft of hybrid system was conducted. The results show that the amplitude of2-order harmonic torsional vibration is the largest in a different throttle opening degree. The torsional and bending vibration are different in different operating modes. The shafting vibration of the boost mode relative to the engine mode has intensified. When the ON-time cycle of the motor access to the hybrid system is not the same, the shorter the cycle, the more violent vibration of shafting.