Research On The Wear Behavior Of Timing Gear System Of Diesel Engine

Helical gear transmission device has the characteristics of compact structure,strong bearing capacity and stable transmission,and is widely used in various power transmission fields such as aviation,shipbuilding,automobile and industrial gearbox.With the development of science and technology,high precision gears with low vibration and noise have become the goal of every industry.During the operation of the system,vibration characteristics of the transmission system are greatly affected by gear wear,which is one of the main causes of gear failure.Therefore,the study of gear wear behavior plays an active role in improving the stability and reliability of gear transmission.In this paper,the influence of wear behavior on the transmission performance of timing helical gears of diesel engines is studied.The main work of this paper is as follows:(1)The wear behavior analysis of timing helical gear transmission of diesel engine based on Archard wear model is carried out.The effects of different torque,cycle times,displacement coefficient and meshing dislocation on gear tooth surface wear are analyzed.The fluctuations,mean square values and the first two harmonic amplitudes of transmission error and meshing stiffness under different tooth surface wear degrees are calculated,and the effects of tooth surface wear on transmission error,meshing stiffness and unit load are analyzed.The results show that the bigger the torque is,the worse the tooth surface wear is;the gear is modified with the objective of optimum sliding rate,minimum sliding speed,maximum root bending strength and maximum tooth surface contact strength,in which the gear with maximum gear bending strength as the index has the least wear degree;under the influence of various deviation dislocations,the offset load phenomenon occurs along the tooth width direction,which causes the wheel to be deformed.The transmission error and contact stiffness of gear transmission increase gradually with the increase of the maximum wear of gear,and the concentrated stress of tooth surface increases gradually.(2)The optimization analysis model of timing helical gear parameters of diesel engine is established.Under the condition of satisfying the bending strength of the tooth root and the strong contact strength of the tooth surface,taking the sliding coefficient and meshing coincidence degree as the optimization objective,by changing the basic parameters such as helix angle,number of teeth and pressure angle of the gear,the influence of different parameters on the tooth surface wear is analyzed,and the optimal tooth surface wear distribution is obtained.The results show that properly increasing helical angle and pressure angle or reducing the number of gear teeth is beneficial to reduce the wear of tooth surface,especially when the number of gear teeth is 23 and 46,the wear effect is the best.(3)The wear depth and transmission error fluctuation between gear teeth are taken as indexes to study the modification of timing gear.Four trimming curves,linear,parabolic,exponential and linear with transition radius,were used to analyze the gear transmission wear after different trimming curves were modified,and the influence of trimming on gear transmission characteristics was studied.The simulation analysis shows that the profile modification of the linear profile modification curve of the timing gear can reduce the wear between the tooth surfaces,effectively improve the meshing characteristics and prolong the service life of the gear.