| With the emergence of problems,such as increasing storage of oil resources and more and more serious environmental pollution,the power of agricultural tractors is developing in the direction of powering by motors,in which the electric tractor powered by bi-motor coupling has become a research focus in recent years,which is characterized by energy saving and environmental protection in operation,low noise,easy to operate and easy to be intelligentized.Based on the transmission theory of bi-motor power coupling,this paper designs a power coupler of electric tractor,which is powered by bi-motor coupling with planetary gear and fixed shaft gear.The main work of the paper is as follows:(1)According to the transmission theory of vehicle bi-motor coupling power and the turn and reverse features of motor based on controller,by drawing lessons from the completed bi-motor power coupling scheme,it designs a bi-motor power coupler to meet the requirements of different agricultural operating modes and road driving of electric tractor in greenhouse on the basis of the analysis of the agricultural operating modes of tractor in greenhouse and the features of road driving under different working conditions.(2)Based on the power demand of the electric tractor powered by the bi-motor coupling operates in the greenhouse under different working conditions,it puts forward the transmission scheme of bi-motor power coupler based on turn and reverse rotation of motor according to the transmission mechanism of the existing bi-motor coupling system,briefly creates a 3D model in combination with the bi-motor power coupler transmission scheme,and works out different working modes according to the actual working conditions of electric tractor,so as to ensure that the power coupling system can meet the operating requirements of the electric tractor under different working conditions.It also determines the coupling mode and mode switching process of the bi-motor under different working conditions,and analyzes the operative modes of clutch,synchronizer and brake in each operating mode.(3)In view of working features of electric tractor powered by bi-motor in greenhouse,it calculates and confirms the transmission ratio,number of teeth,material of transmission gear,modulus,width of teeth,all minimum shaft diameter,critical cross section,safety factor and bearing type of the coupler in each mode according to the operative mode of electric tractor powered by the bi-motor coupling in different working conditions,in addition,it also selects the coupler’ s control terminal,which provides constraints for subsequent simulation model building and mechanical analysis.(4)It verifies the feasibility of the bi-motor power coupler.Based on the working results of electric tractor under light and heavy load conditions,it simulates the tractor field transportation condition and bi-motor coupling driving condition,and tests the traction resistance under the corresponding conditions by making use of the bi-motor test platform and electric tractor test platform,then analyzes the test data by MATLAB,which provides data support for the subsequent model simulation.It also analyzes the relation between the power demand of the electric tractor and the power matching of the driving motor in different working conditions,builds the simulation model of power coupler of electric tractor based on Adams,designs the switching strategies of corresponding operating modes under different working conditions.The simulation result indicates that the designed coupler of electric tractor powered by the bi-motor coupling can meet the power demand of electric tractor under different working conditions and improve the energy efficiency of the bi-motor coupling. |
