Research On Gearshift Process Of A Heavy Wheeled Hybrid Off-road Vehicle

For military wheeled armored vehicles,the use of new energy hybrids can not only save fuel,but also reduce the height of the vehicle by reducing the engine’s displacement.It can achieve pure electric quiet driving at a certain distance,and improve the power by the peak power of the motor in a short time,and provide better battery power for various vehicle command and control electrical equipment in the vehicle.Therefore,military hybrid armored vehicles are a major trend in the future.At this stage,the tandem type electric transmission hybrid armored vehicle needs to redesign the chassis and the wheel or hub motor,while the single axis parallel hybrid system has little modification to the original traditional vehicle,so the single axis parallel hybrid form is more suitable for the Wheeled armored vehicle in current stage.In order to solve the problem of the inconvenience of gear shift caused by the increase of the inertia of the active end and the influence of torque of the power source on the shift process of the hybrid vehicle without clutch separation,the research relies on the project of reserch of 8x8 heavy wheeled hybrid off-road vehicle,carrying out the reserch on the dynamic coordination control of the shift process of a single-axis parallel hybrid vehicle with AMT,it aims to improve the overall performance of a single-axis parallel hybrid power transmission system and achieve improved shift reliability and shorten overall shift time.Firstly,through the longitudinal dynamics analysis of the whole vehicle,the equivalent drag torque at the wheel end is obtained,and then the dynamics of the transmission system is analyzed.Based on this,the working process of the synchronizer during the gearing process is analyzed in detail,and the stages of shifting are described in detail.The linkage between the evaluation index of the shifting gear and the control volume of the shifting process and the overall control method of the shifting process are obtained.Second,a control strategy was developed in stages for the shift process.The“zero torque”control between the currently meshing gears in the gearbox before the pick-up is performed so that the active end and the driven end are equivalent to the angular deceleration equivalent to the neutral gear;the test data is fitted by a neural network.Positive resistance torque;after the smooth picking of the neutral gear,the motor’s torque mode and fuzzy PID control are used to realize the rapid synchronization of the active end speed;after the speed regulation is completed,before the shift,the active end adopts the torque synchronization,which makes the angular deceleration of the active end.The angular deceleration of the driven end is consistent,and the difference between the rotational speed of the master driven end is maintained at a certain value and has the same movement tendency,so that the master end is a free inertia with respect to the slave end.In the stage in which the torque changes rapidly for a short period of time,in order to limit the degree of impact,the control strategy for limiting the difference between the total torque change rate and the motor torque to rapidly compensate for the difference between the total target torque and the actual engine torque is employed.Then,through the matlab/simulink software to build the control model and AMEsim software to build the physical model for the joint simulation analysis,the initial validation of the proposed control strategy.The simulation results show that the comprehensive coordinated control strategy of the shift process can effectively reduce the power interruption time and impact of the shift process while successfully implementing the clutch shift without separation.Lastly,the bench test was conducted.The controller C language program and the VB data acquisition program were prepared based on Freescale high-performance single-chip microcomputer.Each electronic control unit used CAN communication,from impact degree,shift time and reliability.The shift control method was evaluated to verify the effectiveness and practicability of the single-shaft parallel hybrid system without separating the clutch shift control strategy.The experimental results show that this strategy can effectively improve the reliability of shifting the clutch without separation,notify the reduction of the power interruption time and impact of the shift process,and improve the shift quality.