Optimization Design and Experimental Analysis of Spraying Device for High Ground Clearance Plant Protection Machine

The spraying operation of an upland clearance plant protection machine is highly susceptible to resonance with external transient excitation, and this resonance not only triggers the elastic deformation of the spray bar structure, but also affects the overall effect of the spraying operation. In order to solve these problems, the design of the spraying device was optimised in this study, and in-depth experimental analyses were conducted to evaluate its effectiveness. Firstly, the spraying device was designed and a finite element model was established, and then a modal analysis was carried out. In order to effectively suppress the undesirable effects of resonance and elastic deformation, the pre-stressing method was innovatively adopted to provide additional tension by the addition of tension cables. Finally, a comparative field spraying test before and after optimisation was carried out. The results of modal analysis show that the first two orders of intrinsic frequency are lower than 5 Hz, which is easy to resonate with the ground excitation source; in order to avoid resonance, it is found that the best effect is achieved by installing a tie rope on 3/4 part of the spray boom, and the optimised spray boom’s intrinsic frequency are increased to 6.3927 Hz and 7.8531 Hz respectively, and the amount of deformation at each place is lower than 10 mm, and the area of spray droplet coverage is increased by 16.2%, and the amount of deposition is increased by 38.4%. The optimised device effectively suppresses the vibration and deformation of the spray boom and improves the spraying effect of the operation. The results of this study can provide a reference for the analysis of the vibration characteristics of the spray boom of the high clearance sprayer, the optimisation of the spray boom structure and the improvement of the spraying effect of the high clearance sprayer.