Bearing Capacity Research On The Transimission Gear Of High Contact Ratio

Gears of automotive transmission are the key part of gearbox. The bearingcapacity is related to the transmission quality of the whole transmission system, thusaffecting the overall performance of the car. In order to meet the needs of normalwork in gear’s service life, it should make the gear have a certain ability resistancecontact failure and bending failure. Use ISO formula or AGMA formula to calculatethe gear contact stress and bending stress. GB/T3480-1997gear strength calculationmethod is derived from ISO. The exiting gear stress calculation formula is based onthe normal contact ratio. There is no special formal for the high contact ratio gear.Use the formal of normal contact ratio gear, and modify the related coefficient. Thereare two pairs of mesh gear in the meshing process of high contact ratio gears at least.It is a large error selecting the single point load to calculate the stress using the usedmethod. It should select the load of two pairs’ meshing area to calculate the stress ofhigh contact ratio gear. However, when two pairs of teeth are meshing, the load is notevenly distributed on the meshing teeth, due to different contact situations. Thispaper calculates the gear meshing stress based on the theory of gear meshing contactline.For this problem, this paper makes use of gear meshing contact line changingsituation, calculate the gear load theoretical distribution on each gear. The contactline varying from short to long then to short during the helical gear meshing by thecontact area. The gear load is in proportional to the length of contact line. Use thisresult to calculate the gear meshing stress. Learned that is closer to the softwareanalysis value. Because of the software analysis value is closer to the real, treat thesoftware analysis value as the real value. It is proved that this method is feasible.This paper analyses the effect of the helix angle and modification coefficient on thegear contact ratio, contact stress and bending stress effect, considering the effect ofthe gear parameters on the gear contact ratio. The gear modification coefficientclosed graph is a model to make a regional map of gear helix angle. Finally, optimizea gearbox to obtain the gear parameter closer to real.