Study On The Clutch Automatic Operating System Of Heavy-duty Commercial Vehicle

The automated mechanical transmission (AMT) holds the merits of the conventional manual transmission, such as high efficiency and good economic efficiency and good manufacturing inherit performance, it greatly meets the realistic demand of China's automobile development. Along with the development of multi-gear and automatic technology, the automated mechanical transmission is widely used on heavy-duty vehicles.According to the difference of power source, the clutch automatic operating system mainly has three types, the electrical-hydraulic, the fully electrical and the electrical-pneumatic. The electrical-pneumatic type is picked as the research heavy-duty vehicle has pneumatic power source, it doesn't need extra power source, so it's good for reducing cost efficiently; at the same time, in order to overcome the defect of its low control precision, slow response and rough action, combined with the advantage of electrical-hydraulic, the pneumohydraulic method is finally selected.Its function principle and structure form are brought based on the feature of pneumohydraulic and its manipulation process is studied, so it can get the advantage and disadvantage of the system and the key issues during system design. According to the design specification, it calculates the structure parameters and adjusted by the reference design manual. The fluid state is confirmed by the calculated Reynolds number, and the corresponding resistance and pressure drop is calculated in different situations. And then it analyzes shearing stress when fluid flows in the gap between the cylinder wall and piston. Combined with previous experimental and design experience, the pneumatic and hydraulic valves an displacement and pressure transducer are picked. Finally accessories are selected and designed, such as sealing, guides, gas exhaust and so on.Several important properties of clutch are analyzed before the pneumohydraulic system's simulation and analysis: the load and disengagement characteristic of diaphragm spring which means the load-distortion relation of its big and small end during the process of clutch engagement and disengagement; the torque transmission property of three phases during the process of clutch engagement, analyzes those factors which influence the torque transmission; the wear abrasion property analyzes the relation between abrasion loss and friction work and how the application factors work on the relation between abrasion loss and friction work, and studies how the change of abrasion loss affects torque transmission. The software AMESim is selected to simulation and analysis. Firstly it introduces the feature of the software and the four steps of modeling, simulation and analysis. The viscosity of hydraulic oil is chosen by previous experimental experience and then sets the initial condition of pneumatic and hydraulic valves and the properties of fluid. The simplified model of clutch disengagement and engagement process is built respectively, the simulation and analysis work is taken based on those calculated structure parameters. The pressure and flow change at the output port of pneumatic and hydraulic valves, the volume and pressure change and the displacement of piston of pneumatic and actuator cylinder, and the load and displacement change at both side of disengagement poking fork are analyzed and then get the shortest time during disengagement process. The simulation and analysis work of engagement process is followed when both the pneumatic and hydraulic valves are fully opened and based on the final state in the end of disengagement process, so it gets the faster engaging speed. It will provide some advice for structure optimization after the simulation and analysis work. The control rule during clutch engagement is gained through stressing the analysis of three phases of clutch engagement. The respective feature and range of application of fuzzy control, self-adapting control, intelligent control and PID control is introduced and then choose PID as the control algorithm. According to the feature of system structure and control, a clutch engagement model is established which takes the current of hydraulic as the control output, and then simulate and analyze the engagement process. It will give some help to the next experimental work.A information acquisition system is built based on the CAN bus technology aiming at the clutch automatic operating system. It takes PC as position machine and use CANoe to monitor the run state, and sets CANdatabase and CAPL and the variables according to the test requirement, such as the piston displacement and pressure, and then design the panel which can appropriately control those variables. It uses the built MATLAB/Smulink model to produce program code and transfer to Cosmic to run, the control program and bottom API could be compiled in Cosmic. It debugs program by changing the control variables on panel while running CANoe to monitor the system state. It uses the panel to control the action of pneumatic and hydraulic valves, collect the data about the displacement and velocity change during disengagement and engagement, and oil pressure in accessorial hydraulic cylinder, and then convert these data to pass to position machine. It analyzes and adjusts the PID control algorithm by comparing the difference between the target and realistic position and the control purpose is gained properly.