Study On The Electric Shift Of The AMT Of Heavy-Duty Commercial Vehicle Without The Disengagement Of The Clutch

On the basis of the traditional fixed shaft transmission and the dry clutch,Automated Mechanical Transmission realizes the automatic operation of the start and the shift by applying the electronic technology and the automatic shift theory,taking the electronic control unit as the core and controlling the disengagement and engagement of the clutch,the shift performance and the adjustment of the accelerograph by the implement mechanism's control.Automated Mechanical Transmission is a type of product fit for our national condition and will become the main direction which our country's transmission gearbox will develop,which has the merit not only of Automated Transmission's easier operation but also of the quondam manual transmission's highly efficient gear drive,the low cost,the simple structure and the good manufacture heritage.The author will study the electric shift process of AMT without the disengagement of the clutch by analyzing the power train's characteristic deeply and studying the control theory of the shift process and simulating it.Then the author will finish the design of the control system of the AMT shift in this paper.The research contents are as follows:1. The analysis to the power train The main object of the power train is to transmit the power from the engine to the drive wheel to carry out the drive of the automobile.On the basis of the thorough research and the analysis to the engine's nonlinear characteristic and regulative characteristic,especially the transmission's characteristic,the author analyzes the kinematics and the dynamics and probes into the main factors during the shift process to lay the foundation for the establishment of the reasonable and effective control strategy.2. The research on the shift process controlThe author brings forward the realization project of the AMT's automatic shift system without the disengagement of the clutch and establishes the control stategy of the shift process by analyzing the function demand and the quality appraisal of the shift.3. The design of the AMT's system of Heavy-Duty Commercial Vehicle without the Disengagement of the ClutchOn the basis of the aforementioned research,the author accomplishes the development of the AMT's control system.The emphasis is to use the structured and modularized design concept to accomplish the design of the electronic control unit of the control system,the sensor and the implement mechanism.The power train has a potential difficulty,which is the problem that all the components don't match and coordinate well.It's a premise of the dynamic control to undersand the mutual factors of the power train thoroughly.It's helpful to understand,study and judge the system's work capability deeply and find the system's primary factors in the shift principle by analyzing the characteristic of the engine,the clutch and the gearbox during such a complicated dynamic process of such a system,namely the power train of the automobile.The author also analyzes the kinematics to the shift force situation during the automobile's shift process.Through the kinematics analysis,the author grasps the primary external factors during the process of the start and the shift.In order to guarantee the automobile's run smoothness during the shift process,the author brings forward the control idea of the electric shift without the disengagement of the clutch and discuss it's feasibility.The control strategy of the electric shift without the disengagement of the clutch is as follows:1) The shift can be down or up only when the intermediate shaft's torque tends to the zero during the shift process.So the engine's torque must be adjusted before the shift is down or up.2) The transmission ratio changes before or after the split second from one shift to another,but the change of the vehicle velocity almost equals to the zero.Therefore,the engine's rotate speed must be adjusted to adapt to the new conditions the vehicle run under and decrease the shift shock during the shift process at the same time.Generally speaking,on the one hand,decrease the engine's rotate speed before the shift is up.On the other hand,increase the engine's rotate speed before the shift is down.And use an mechanism to brake the engine before the shift is up at the same time.3) The accelerograph must be augmented to make the vehicle run regularly and the power must be resumed after the shift is finished.The signal of the throttle's augmentation is trasmited to the ECU by the throttle sensor,then the ECU transmits the signal to the accelerator pedal sensor to make the accelerator pedal be resumed to the normal position.During the power is resumed,the control strategy of the throttle affects the quality of the shift process very much. According to the aforementioned research to the power train and the shift process,the author designs a new AMT's control system and introduces its work theory,its function and its composition.The design of the control system begins from the transmission gearbox control module,the engine control module,the safety control module,the breakdown diagnosis module and the assistant function module.The author specifically introduces the basic components and the work theory of the electronic control unit,the sensor and the implement mechanism,which constitute the control system.Among them,the electronic control unit of the automobile computer control system is devided into two parts,the hardware and the software.The two parts depend on each other mutually,supplement each other mutually and are indispensable.Therefore,the design should display its software superiority fully on the basis of using the single chip computer's hardware resources fully.The sensor is the most important surveillance and control tache in the automatic transmission system,whether the sensor survey is accurate or not decides the reliability and the security of the automatic transmission system.The shift mechanism is electric.The selective shift electromotor is used to select the shift and the shift electromotor is used to perform the shift after they are adjusted their rotate speed.Otherwise,the electromotors must be adjusted their rotate speed to make the shift fork stop at the target position during its run process.