Study on the Shifting Quality of the CVT Tractor under Hydraulic System Failure

Abstract

The failure of a hydraulic system will affect the shifting quality and driving safety of a CVT tractor. In order to reveal the response of the tractor under different hydraulic system failures without destroying the transmission, the following methods are proposed in this paper: firstly, building the simulation model of CVT; secondly, building a test bench to test and verify the transmission model to ensure that the simulation model can accurately predict the response of CVT under different clutch oil pressures; thirdly, obtaining the fault oil pressure data without starting the engine and taking the data of fault oil pressure as the input variable of the simulation model; finally, obtaining the response of the CVT tractor under different hydraulic system failures by simulation. It is found that the damage of the seal ring inside the rotary joint has little effect on shifting quality; oil way block can lead to greater shift impact; when seal ring damage and oil way block occur together, the clutch cannot reach the minimum working pressure; clutch piston jamming and oil leak can cause power interruption of the tractor. The results show that it is feasible to study the response of CVT in fault mode by simulation.