Study On Improvement Of Metro Gearbox Structure

Gear box, as one of the key parts of metro power bogie, the reliability of its function directly affects the safety operation of the metro vehicle and the service life of gear and bearing. Oil leakage fault can be accounted for more than 80% in all the failure mode of gear box. According to a 100km/h metro gear box oil leakage phenomenon, this paper uses the simulation calculation and test method on the design to improve the labyrinth seal structure of the gear box and reduce the possibility of a gearbox oil spill.The gear box of this research is designed for reduction gear box whose domestic metro vehicle’s top speed is 100 km/h and its sealing structure is designed from a mature subway gear box with a maximum speed of 80 km/h. When conducting type test after the trial production, oil leakage phenomenon appears on labyrinth of driven gear shaft end. Oil leakage phenomenon appears on gear box that is not officia lly put into use. When the metro vehicles put into use in vibration and wear of incentive factors, the possibility of oil spill will increase. So it is essential to study the problem.In order to study the problem, first through the analysis of the gear box design, manufacture, assemble process, we known the main reason of oil leakage phenomenon of the gear box in the test process, cause the temperature rise increases is the motor speed increases and then the pressure in the tank is too large, causing the sealing structure cannot be effectively sealed by, and not fully considering the gear box seal structure is to adapt to the new situationTherefore the seal structure of the gearbox should be improved. In order to study the structural change can meet the use requirement, the paper of labyrinth seal structure used in Metro in the gear box is studied and discussed. Frist using FLUENT software to calculation shows that the leakage of stepped labyrinth seal is considerably smal er than the straight through labyrinth seal.According to the conclusions of simulation analysis, optimizates shaft end labyrinth seal structure of the gear box driven gear, puts forward the new gear box sealing structure, changes the straight through labyrinth seal for stepped labyrinth, reduces the seal clearance and increases the sealing cavity at the same time. This paper reduces the sealing leakage in many aspects.To further verify the structure optimization effect, this topic conducts no-load test and loading test for gear box improved structure by using the type test way and verifies the function, temperature and sealing performance of the gear box which adopts the improved seal structure by the type test. Verification result shows that oil leakage phenomenon does not appear on the gear box with the labyrinth seal structure.