Xu Liyou

Simulation of Steady Turning Movement Trace of Tracked Vehicle of Double Power Flow Transmission

The turning process of tracked vehicle is the compound movement process. The hydro-mechanical differential turning system is the double power flow turning system of tracked vehicle. Basing on turning kinematics of tracked vehicle and hydro-mechanical differential turning theory, the simulation model of turning movement trace of tracked vehicle of double power flow transmission is established. The model is fit for all movement states of tracked vehicle. The steady turning movement trace of tracked vehicle is simulated and its changing rule is analyzed. The theoretic base that the hydro-mechanical differential turning performance is studied and the turning control system is developed is provided in this paper.

Study on Matching Strategies and Simulation of Hydro-mechanical Continuously Variable Transmission System of Tractor

In this paper, the engine output torque model and fuel consumption model are established based on engine test results. The engine rotary speed feature denotes the relationship between the engine rotary speed and the throttle opening when engine works in the optimal modes of economic and power operating. On the basis of the above work, the matching strategies of hydro-mechanical continuously variable transmission (HMCVT) system are put forward. According to the different fieldwork of tractor, the matching strategies of HMCVT system are studied by simulation method. The research provides theoretical foundation for design and control method determination of HMCVT system.

Efficiency analysis of an innovative multi-range hydro-mechanical continuously variable transmission

To study the calculating method of the total efficiency of the innovative multi-range hydro-mechanical continuously variable transmission (HMCVT) when factors such as the power cycle and the variation of the efficiency of hydraulic units with their input power are considered, this paper established an approximate efficiency formula of hydraulic units according to test data, given an efficiency algorithm of the closed pump-motor system, which varies with the speed, pressure and displacement of hydraulic units, derived the existence conditions of the power cycle in the closed planetary gear transmission, presented the efficiency formulas of typical structures of HMCVT, and described a reasonable efficiency calculating procedure. The efficiency of the innovative multi-range HMCVT is calculated by this procedure. The result shows that the average efficiency of HMCVT is higher than 0.93, although the efficiency varies with the transmission ratio, the input power and speed. The HMCVT can work in high efficiency ranges by properly adjusting its transmission ratio into the ranges that the pump displacement is near to zero.

TRANSMISSION EFFICIENCY RESEARCH OF MULTI-RANGE HYDRO-MECHANICAL CVT

The transmission efficiency of a multi-range hydro-mechanical continuously variable transmission (HMCVT) is researched, which considered the factors of the power cycle and the efficiency variation of hydraulic units with their input power and speed. An efficiency algorithm of the closed pump-motor system is given, which is relative to the speed, pressure and displacement of hydraulic units. Efficiency formulas of typical structures of HMCVT are derived by meshing power method. The efficiency of a multi-range HMCVT is calculated. The calculated efficiency is consistency with the measured efficiency. The result shows that the average efficiency of HMCVT is reasonably higher than the peak efficiency of pure hydraulic transmission, although the efficiency varies obviously with the transmission ratio, the input power or torque. When the output torque of engine is smaller, the efficiency of HMCVT is lower. However, the speed change of engine has a less influence on the efficiency of HMCVT.Copyright

Principle of Weight Dynamic Change Fuzzy-PID Integrated Control for the Displacement Ratio of Multi-range HMCVT

A weight dynamic change fuzzy-PID integrated control principle for the displacement ratio of multi-range hydro-mechanical continuously variable transmission (HMCVT) is presented, which enhances the control precision of transmission ratio by improves the dynamic characteristics of displacement ratio of variable pump-motor system. The weight dynamic change Fuzzy-PID integrated controller automatically adjusts the weight value according to the error of displacement ratio. When the error is larger, the fuzzy control is strengthened to improve the response speed; when the error is smaller, the PID control is strengthened to decrease the steady-state error. Bench test showed that this control method can improve the rapidity and accuracy, decrease dynamic tracking error for the control of transmission ratio of HMCVT.