Research Of Friction Of Crankshaft Thrust Washer Of Hybrid Engine

In this thesis, a failure case of a worn crankshaft thrust washer on a type A engine for a hybrid-power bus model is studied. With cooperation with the bus maker and through failure statistics and FTA-PA to rule out the normal factors that cause thrust washer failure, eventually we conclude the main cause of failure lies in vehicle controlling strategy:(1) Starting and stopping frequently;(2) Disengagement of clutch is too long, and when clutch is disengaged the engine continues running to charge the generator and the rear end of crankshaft is continuously subject to axial force. Secondary reason is: thrust washers of crankshaft for normal engines aren’t fit for working conditions of hybrid engines. Improvement is made: by optimizing the hybrid power system of vehicle, an ISG electric motor is connected the rear end of engine through a torsion dumper. This is a long engagement connection. Then a clutch is connected to the driving motor, and driving shaft and back axle are connected after. The ISG motor and torsion dumper are jointed with a spline groove, thus axial movement is realized. This structure realizes the engine driving ISG motor to generate electricity when the driving motor is disengaged from ISG motor, and greatly reduces the forward axial force on rear end of crankshaft, therefore the operating circumstances of thrust washer are greatly improved. With comparative experiments, a scenario of forced-lubrication edge tile is concluded to be the best scenario to improve friction-resistance of crankshaft thrust washer. Eventually the friction of engine thrust washer is solved.