Zhou Zhili

Energy Saving Technology of Thermal Regenerative Compressed Air Dryer by Regenerates Adsorbent with Residual Heat

According to the characteristic of the compressed air dryer located at the same place with the air compressor, for the large capacity thermal regenerative compressed air dryer that the absorbent is regenerated by an electric heater, this thesis puts forward an energy saving method, which use the residual heat of compressed air from the grade II outlet of air compressor to preheat the regeneration airflow. The regenerate process is described and the power of electric heater is calculated. The energy can be saved about 40% by using this method and the complexity of the equipment doesn’t increase.

Speed Change and Range Shift Control Schedule of the Multi-Range Hydro-Mechanical CVT for Farm Tractors

For the multi-range hydro-mechanical continuously variable transmission (HMCVT) used in the farm tractor, on the purpose of getting the maximum driving capacity and avoiding shift circulation, a speed change and range shift control schedule is presented. An analysis of the pulling characteristics showed that: when engine runs on the maximum power point by governing transmission ratio, maximum pulling efficiency can be got at any polling force; and by means of the characteristic that the efficiency is different at the range shift point of two neighbor ranges, the changeable range of pulling force and engine speed can be located to avoid shift circulation. Thus a speed change and range shift control schedule that uses the speed control lever position, engine speed and range number as the calculation parameters is presented. This work laid the foundations of the development of the multi-range HMCVT automatic control system

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.

Modeling and control simulation for farm tractors with hydro-mechanical CVT

To develop the control system of hydro-mechanical continuously variable transmission (HMCVT), a tractor power train model is built by using the principle of dynamics and modular method, which includes the engine, HMCVT, running system and driven implement. According to the characteristic of power split, HMCVT is separated as axes set, variable displacement pump-motor system, clutch set and control system. The control logic model of range shift process is developed by using the theory of finite state machine. It is realized that TCU continuously controls the process of speed change and range shift. The dynamic characteristic of automatic speed changing and ranges shifting is simulated. The result indicates that it is an effective method to improve the dynamic performances of HMCVT by using the variable parameters PID control method which use engine speed and throttle values as control parameters and the feedforward control method which use throttle change rate as control parameters. The model can be used conveniently for the analysis of tractor dynamic performance and the research of HMCVT control method.

Design of Powershift Transmission Control System for Tractor Based on DSP

An electro hydraulic gearshift control system was designed based on DSP for the purpose of realizing automatic control of tractors with power shift transmission. The hardware design principle of input module such as pulse signal, analog signal and switching value, and the output drive module of gearshift solenoid valve were investigated. Utilizing the method of modularizing design and the core of real-time and multitask handling system-DSP/BIOS, the operational control process of tractor such as starting, gear shift and braking was investigated, which guaranteed the extensibility of software program. To validate the design, a semi-physical simulation test was tried out. The testing results showed that the control system can realize the automatic shift control based on the tractor speed and the operation of driver, which effectively improved the operating efficiency of tractor.

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

The Design of Communication Nodes in the Tractor Control Network Based on ISO11783 Protocol

This thesis introduces the structure of tractor electronic control network and the basic characteristics of ISO 11783 communication protocol in the serial communication network of agricultural vehicles, and presents the design scheme, which is based on C8051F040 chip, for software and hardware of ECU communication nodes in the tractor electronic control network.

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.