Experimental Study And Structure Optimization On Cleaning Device Of Single Axial-airflow Combine

In this paper, it aim at the impurity rate of grain falling from the back of threshing cylinder is relatively high of DR25 A combine harvester with single longitudinal axial-airflow. When feeding amount of combine harvester exceed 5kg/s, the loss rate and impurity rate of grain are very high. Optimized the working parameters of cleaning device through simulation analysis and experimental. At the same time the structure optimization scheme with return of the sieve plate is proposed. Concrete research content are as follows:(1)Analyzed the main composition and characteristics of rotor in cleaning room of combine harvester with single longitudinal axial airflow. The rotor distribution are researched too. Started from the airflow in cleaning room, measured the critical speed of the rotor of the main ingredients in cleaning room. Summarized the structure characteristics of the cleaning device, the main working parameters and so on.(2)The software Pro-E is used to establish three dimensional airflow model of cleaning room. Based on simulation software of Fluent to simulate the airflow field in cleaning room. Selecting the velocity vector diagram in the typical cross sectionlongitudinal section in the middle of screen surface. Studied and analyzed the effect of three parameters including different angle of air distributing plate I, different angle of air distributing plate II on the airflow field distribution in cleaning room.(3) In order to find the optimal working parameters combination of cleaning device. Orthogonal experiment was used to optimize the main working parameters of cleaning device including fan rotational speed and air distributing plate I Angle, the wind plate II Angle.(4)The grain falling from the back of threshing cylinder fall into the screen surface directly. It causes the grain’s impurity rate and loss rate. In order to solve this problem, structure optimization scheme of cleaning device is put forward. Analysis shows that, the grains falling from the concave plate screen moved to near the nine fin-type chaffer where cleaning ability is higher. It can reduce the vibrating screen cleaning load and reduce the secondary miscellaneous allowance, thus the cleaning performance of the engine is improved.(5) Field performance test was conducted to analyze the effect of four parameters on cleaning performance indicators(loss rate and impurity rate). The experiment results show that the optimal working parameters of cleaning room in the process of practical working, the fan rotation speed is 1400 r/min, the angle of wind plate I is 30°, the angle of wind plate II is 15° and the scales of fin-type chaffer is 24.5mm. Under the above mentioned circumstances, the loss speed is 1.02% and the impurity speed is 0.90% before improvement. The loss speed is 0.32% and the impurity speed is 0.31% after improvement. When the installation angle of return sieve plate is 30°, the cleaning performance is the best. Besides, the loss speed is 0.20% and the impurity speed is 0.17%.