Study On Influencing Factors Of Dynamic Characteristics Of Timing Gear Driving System Of A Turbocharged Intercooled Diesel Engine

Timing drive mechanism is transmitting mechanism of internal combustion engine, valve, The timing of fuel injection pump and hydraulic pump is controlled by timing drive mechanism it is an important guarantee for the normal operation of the internal combustion engine. With the continuous improvement of internal combustion engine performance and working conditions deteriorating that Aggravates the shock and vibration of timing drive mechanism, so it puts forward higher requirements on the timing drive mechanism. The characteristics of timing drive mechanism could be predicted by analyzing the dynamics of driving mechanism dynamics, then the analysis provides the theoretical basis for the timing drive mechanism optimization.In this paper, taking a excavator with four-cylinder turbocharged intercooled diesel engine as the research object, combined with the gear meshing theory and the theory of multi body dynamics, considering the average meshing stiffness of gears, backlash damping of gears, crankshaft speed fluctuation, the load of hydraulic oil pump gear and fuel injection pump gear, thrust bearing stiffness, the load of valve train, the meshing condition and transmission stationarity of timing gears and gears meshing with crankshaft angle were discussed. Crankshaft speed fluctuation, hydraulic pump load and gear backlash effect on timing gear system dynamics was discussed in two cases of hydraulic pump output torque and without output torque, and studied there factors impact on the timing gear.The results show that:(1) Along with the increase of speed of diesel engine, torsional vibration of each gear is mounted, all of gear are significantly impact in the hydraulic pump output under the condition of no load torque. Gears meshing force increases the average of about3times when the diesel engine speed from1000r/min to3000r/min.(2) Increasing the speed fluctuation of crankshaft and gear side clearance of gear effect Impact and torsional vibration of timing gear train in the hydraulic pump output under the condition of no load torque, but the speed fluctuation of crankshaft is the main cause of the timing gear system produce high impact and torsional vibration. The maximum amplitude of speed fluctuation of crankshaft is reduced by about45%in the3000r/min of diesel engine, and the gear meshing impact force fell by an average of about50%, Thus, the shock state of gears and transfer smoothly has been greatly improved.(3) Along with the increase of hydraulic oil pump gear stable load, each gear of the gear system produces a polarization phenomenon in the condition of hydraulic pump output torque, but the vibration amplitude is smaller, Gear meshing state tends to be unilateral meshing and serious phenomenon of partial load, and the speed fluctuation of crankshaft and the increases of gear clearance the positive effect of gear meshing force decreases gradually.