| As a large agricultural country,the development of agricultural vehicles for China from the traditional agriculture to modern agriculture has its extremely important strategic significance.In recent years,with the rapid development of agricultural electrification,electric agricultural vehicles are becoming the hot spot of vehicle dynamics research.At present,pure electric power transmission is mainly fixed speed ratio transmission and multi-stage speed ratio transmission structural forms.It is difficult to adjust the vehicle speed according to the real-time traffic condition for the vehicle of fixed ratio transmission,which is easy to cause the waste of energy.The speed range of the multi-stage speed ratio drive is small,which is easy to be damaged by the motor power shortage and cannot meet the power demand of the agricultural vehicle.Based on the theory of coupled drive and the research status of agricultural vehicle dynamic coupling mechanism in China,a double-row planetary dynamic coupling test rig is designed in this paper.The double-row planetary gears as a dynamic coupling mechanism,while increasing the range of stepless speed control,but also according to real-time traffic to achieve a variety of drive mode conversion between the single motor to solve the single motor The speed of driving is small,the power is insufficient and the stability of the process is poor,so as to improve the economic performance of the vehicle and provide a theoretical research platform for the subsequent study of the power balance matching of electric agricultural vehicles,which solves the problem of low speed range,lack of power and poor stability when single motor drives.At the same time,it provides an experimental platform for the study of the power balance of electric vehicles.The main work is summarized as follows:1.Based on the coupled drive theory,the design of the double row planetary dynamic coupling mechanism is completed.Based on the comparative analysis of the structure and transmission characteristics of the front and rear wheel train in the double row planetary gears,the double-row planetary gears are selected as the research objects and a double-row planetary dynamic coupling mechanism for agricultural vehicles is designed,and the main design parameters such as the characteristic parameters,the gear modulus and the number of teeth of the planetary gears before and after the configuration are selected.Finally,the operation mode of the double-row planetary dynamic coupling mechanism is analyzed,which provides the theoretical basis for the subsequent simulation and design of the test bench.2.The correctness of the theoretical calculation of the dynamic coupling mechanism and the validity of the simulation model are verified by parametric modeling and simulation analysis of the double-row planetary dynamic coupling mechanism.Three-dimensional modeling software UG and dynamic simulation platform ADAMS are used to parametric modeling and simulation analysis of double-planetary dynamic coupling mechanism.The relationship between the output torque and the input torque in the different operating modes is plotted.Simulation results show that:in the case of no-load and load,the relationship between the output torque and the input torque is consistent with the theoretical derivation in different operating modes,which proves the feasibility of the design of the double-row planetary gear dynamic coupling mechanism and the validity of the simulation model.Compared with the single motor operating mode,the dual motor coupling operation mode has a large speed range and excellent dynamic performance.3.According to the design target of the test platform,the hardware and software system of the test bench is designed.Hardware system design includes four parts:Design of driving control system.The double motor coupling structure is adopted to improve the stability of DC brushless motor stepless speed regulation.The bottom of the motor is equipped with an external electromagnetic brake,which can realize the conversion between the different operating modes of the test bench by controlling the power supply and the power supply of the external electromagnetic brake;Dynamic coupling system design.The utility model is mainly composed of a double row planetary gear box,which is connected with the other systems of the test bench through the coupling of the elastic coupling of the plum blossom,and realizes the power transmission mode of the double power source input single shaft output;Design of sensor detection system.To test the input speed of the output end of the real-time monitoring and transmission using digital sensor;load simulation system design,including the magnetic powder brake and tension controller,magnetic powder brake is fixed on the control cabinet.The software system design mainly includes two parts:the design of communication system,the bus structure will be aggregated to motor control and sensor detection,realize the communication with the host computer by Modbus protocol software;measurement and control system,using LabVIEW as the design of measurement and control software development platform,to achieve real-time display of test data.4.The two-planetary dynamic coupling test-bed was tested and studied by means of theoretical calculation,simulation and experimental analysis.The results showed that:the output speed of the measured surface coincides with the theoretical surface in the case of no load and load,which indicates that the test results are consistent with theoretical calculations and simulations and verifies the feasibility of the test bed design.From the analysis of output speed error,the relative mean error of the output speed is less than 6%in the no-load test and less than 8%the load test,which indicates that the stability of the double-motor coupling operation is also enhanced.In the application of agricultural vehicles,when the dual motor is running,as the main motor,the motor M1 has played a very good effect of reducing the speed and meets the power demand in different conditions for agricultural vehicles.As an auxiliary motor motor M2 has a significant speed control function,increasing the stepless speed range,can make agricultural vehicles in a wide range of speed to work,without the need to frequently adjust the gear Motor M2 as an auxiliary motor has a significant speed control function,increasing the range of stepless speed range,making agricultural vehicles works stably in a wide range of speed no need to adjust the gear frequently,which improves the efficiency of the operation and achieves the desired test design goals.Finally,the problems existing in the application of test benches in agricultural vehicles are analyzed,and the corresponding improvement methods are put forward. |
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