| Due to its advantages of high cost-effectiveness,simple operation,convenient maintenance,and high uniformity of spraying,the hose reel irrigator has become one of the most promising and popular irrigation machinery in China.However,the current domestic hose reel irrigators mainly have the following problems: the efficiency of the water turbine drive is low and the power is low under low operating conditions.The compound drive system consisting of belt drive,gear drive and chain drive is inefficient,the drive structure is complex,and the key components of the drive system are of poor quality.The use of high efficiency DC motor instead of water turbine can greatly improve the performance of the original motive,but the motor speed is far higher than that of water turbine.The transmission ratio required by the whole transmission system is very large.If the existing transmission system is adopted,the efficiency of the transmission system will be low,the volume and quality of the gearbox are large and so on.In order to solve the above-mentioned problems,this paper redesigned and optimized a planetary gear transmission system with high efficiency and high transmission ratio of JP75 hose reel irrigator from the aspects of theoretical analysis,experimental verification and simulation analysis.1.A highly efficient planetary gear transmission system with a large transmission ratio was innovatively designed.For hose reel irrigators driven by DC motors,the reel load and the torque and speed characteristics of the DC motor were analyzed from the aspects of theory and experiments.According to the matching of DC motor and reel load,with the goal of high efficiency,power and economy,a planetary gear transmission system with high efficiency and high transmission ratio based on planetary gear transmission was redesigned.The first and second gear ratios of the gearbox in the transmission system were respectively 548.40 and 382.71,and the transmission ratio of the big gear was 19.23.2.An optimized design method based on the smallest volume and compact structure of the planetary gear train was adopted,and the shift speed of the machine under the condition of the lowest energy consumption was determined.With the objective of minimizing the overall volume of the three-level planetary gear train,the module,number of teeth and tooth width in the three-stage planetary gear train of the new transmission system scheme were optimized using the genetic algorithm toolbox.The overall volume after optimization was reduced by 12.9% before optimization.The energy consumption simulation of the complete machine was performed in SIMULINK,and the optimal shifting speed of the nozzle car speed was determined to be 35m/h,at this point,the efficiency of the DC motor was always greater than 71%.Finally,the newly designed transmission system was tested.The test results show that the drive system total efficiency of the new design increased by 35% or more than the drive system efficiency of the existing compound transmission system with belt transmission,gear transmission,and chain transmission.The maximum drive power was reduced from 500 W under the original worm gear drive system to 300 W,which verified the high efficiency of the planetary gear transmission system.3.The kinematics and dynamics simulation verified the rationality of the design of the planetary gear transmission system.In the UG software,the key parts of the JP75 planetary drive system of the hose reel irrigator were modeled and assembled.The three-dimensional model was imported into ADAMS software for kinematics and dynamics simulation.The simulation results showed that the ratios simulation errors of the gear trains in the transmission system were all lower than 0.18%,the simulation errors of the total gear ratios of the first gear and the second gear were 0.22% and 0.21%,and the simulation errors of the gear speed and gear ratio were within the acceptable range.The axial force of each gear was 0,the simulated error of the tangential force and axial force was less than 0.26%,and the error between the simulated value and the theoretical value was very small,which verified the rationality of the planetary gear transmission system.4.The finite element analysis method was used to estimate the fatigue life of the gears of the transmission system.The steady-state meshing of the gears of the transmission system was studied,and its static characteristics under a given working condition were analyzed.At last,the modal analysis of the planetary gear train system was carried out to determine the natural frequency and mode shape of the sun gear.The simulation results showed that the maximum stress of the fixed shaft gear and the planetary gear train were 40.917 Mpa and 116.72 Mpa,which were within the permissible material yield limit.All of the maximum deformation and equivalent strain were found at the tooth roots of the gears,and them would not affect the normal operation of gears;The safety factors of gear engagement at all levels were greater than the allowable safety factor of 1.25,and the fatigue life of all gears was greater than 2.47×105h,which met the design requirements.The natural frequency of the lowest order of the sun gear was 47576,which was much higher than the excitation response frequency caused by the maximum speed of the DC motor.Resonance did not occur during operation and it met the design requirements. |
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