Improvement of potato harvester with two segment of vibration and wave separation

Abstract: Potato is typical tuber crops, which is planted widely for food and for energy uses. During the mechanical procedure section, 70% bruising and damage of potato was from harvesting, which is the comprehensive effect including multiple collision caused by static load, shear, extrusion, vibration and impulse load, repeatedly rubbing and pressure of different direction. The main technical problem of potato mechanical harvest is comprehensive control of potato's bruising and damage, including realizing potato-soil, potato-stalk and potato-impurity separating efficiently and decreasing loss caused by dynamic damage and tangent bruising. It is widely recognized that there exists some problems like higher bruising rate and damage rate during the process of mechanical potato harvest. To solve these problems, based on two segment of vibration and wave separation, a new potato harvester was improved through setting vibration separation segment and wave separation segment. As such, the movement characteristics of separating sieve and potato block was analyzed during in the process of potato-soil separating. Adjustment vibration intensity for vibration separation section can meet the various requirements of potato-soil separating. Changeable gain of wave crest-trough for wave separation section can turn over the potato-soil mixture. In that way, it can improve soil breaking ability and benefit for potato-soil separating. The field harvesting experiments were conducted, and the single factor test showed that the total bruising rate, total damage rate and obvious rate were declined by 0.73%, 0.97% and 3.2%, respectively when the harvesting speed decreased from 0.726 to 1.167 m/s. With the harvesting speed decreased, the unit-time weight of potato-soil mixture decreased, and the potato lost the protection of soil in the delivery and separation segment of harvester's rear. At the meantime, it caused cumulative fatigue damage by repeated fiction between potato block and separating sieve bar. While the higher harvesting speed, the unit-time weight of potato-soil mixture and the separating load both increased, in which the soil-impurity separating rate and obvious rate decreased. Secondly, when the separation sieve speed increased from 1.52 to 2.80 m/s, the total bruising rate and the total damage rate showed a trend of decreasing first and then increasing, but the obvious rate just decreased from 99.8% to 96.4%. Thirdly, when the vibration intensity increased from level Ⅰ (non vibration) to level Ⅴ (strong vibration), the obvious rate increased by 3.3%, and bruising rate and damage rate increased by a large margin. Therefore, adjusting vibration intensity should give consideration to separating efficiency and harvest quality in the practical harvest. Besides, wave crest-trough difference increased from 40-40 mm to 200-200 mm, the obvious rate was raised from 97.2% to 99.8%, and both the bruising rate and damage rate increased. Orthogonal test showed that the effect law on bruising rate and damage rate caused by harvesting speed and vibration intensity was almost consistent. For separation sieve speed and wave crest-trough difference, the effects on bruising rate and damage rate caused by harvesting speed and vibration intensity were more significant (P＜0.05); while for harvesting speed and separation sieve speed, the effects on obvious rate caused by wave crest-trough difference and vibration intensity were more significant (P＜0.05). This study can provide a technical reference for development and optimization of potato harvester and comprehensive control of potato-soil separating efficiency and harvest quality.