Research On Prediction Of Target Range State Of The Hydro-mechanical Continuously Variable Transmission Based On The Key Parameters

Hydro-mechanical Continuously Variable Transmission(HMT)is a kind of double power flows transmission with characteristics of high efficiency and stepless speed variation,which is compounded by hydraulic and mechanical transmissions.It has ability to achieve several high-power and high efficient stepless transmission.The process of hydraulic mechanical power shift is constituted by adjacent power transitions.In the shift process,the high and low pressure circuits in hydraulic circuit interchange,causing the fluctuations of rotational speed and power and influencing the quality of power shift.It is significant to accurately predict the characteristics of target range,which combines theoretical analysis experimental studies,for smoothing out the fluctuation,improving the quality of shift and achieving full power shift.This paper uses a two-range arithmetic HMT as research object to carry out the studies about characteristics of target range basing on the key parameters of current range.The main research contents include:(1)Hydraulic efficiency models were built for each range.The models take into consideration the changing efficiency of hydraulic transmission unit which is caused by interchanging the functions of pump and motor.An appropriate prediction models were built by combining current status and load of hydraulic system and studied the connection between hydraulic mechanical power and mechanical loss.(2)The connection among the power flow of hydraulic mechanical,mechanical loss of current range and power flow of target range were analyzed to determine key parameters at target range.The predictive-observer models of target range were built to predict the work status and obtain the predicted value of key parameters at target range.And the prediction simulation analyzes of target range state and studied influence laws of oil temperature and input speed in target range prediction were carried out.(3)A HMT experiment bench was established for carrying out the power shift experiment under different input speed and load to verify the correctness of prediction model.This result laid the foundation for the full power shift control of HMT.