Research Progress on Cleaning Technology and Device of Grain Combine Harvester

The grain combine harvesters of China generally exist problems such as low reliability, low adaptability, and low intelligence and informationize. The cleaning device is one of the core working components of the combine harvester, and its performance is an important factor that directly affects the performance of the whole machine. How to improve the performance and efficiency of the cleaning device is the difficulty and focus of the development of grain combine harvester at this stage. To this end, the research status of domestic and foreign combine harvesting technology and equipment was reviewed from the aspects of cleaning device structure, airflow field and material movement in the cleaning device and intelligent cleaning device. At present, in the basic structure of the combine harvester cleaning device, research was mostly concentrated on multi-fan, multi-layer vibrating screens, shaking plates, etc. In the aspect of the cleaning device fan structure, the fan performance, efficiency, and airflow uniformity of the air outlet were optimized by optimizing the fan volute, impeller, and multi-duct structure. In the aspect of cleaning sieve, the sieve surface structure and motion form of the vibrating screen were studied. In the research of the airflow field, a more complete simulation model can be established, and a more accurate airflow field measuring instrument can be established, so that the internal airflow field distributions of the simulation and experiment for cleaning device were closer to that of the real situation. In the research of material movement, the EDEM software was usually used to simulate the movement of material particles on vibration, which can reflect the movement law of materials to a certain extent, but still cannot reflect the internal material movement of the actual cleaning device. Most of the existing gas-solid two-phase flow in the cleaning device adopted the CFD-DEM software coupling method, but they all simplified the model as much as possible, which caused the numerical simulation results to be different from the actual test results. Most of the researches on the grain loss monitoring sensor adopted the principle of piezoelectric type, which had the characteristics of simple structure, high resolution and suitable for complex working environment. Modern control theory and method were adopted to make the cleaning loss automatically adapt to the working object and environment. The development trend of the combine harvester cleaning device was proposed: development in the direction of light weight; development in the direction of low vibration and low noise; development in the direction of versatility; development in the direction of intelligence and informationize; acceleration of the development of industry, academia and research; cleaning device design by big data fusion. It had important reference significance for improving the working performance and efficiency of the cleaning device and the combine harvester, and further promoting the comprehensive high quality and high efficiency development of the mechanized harvesting of crops in China, which provided a basis for modern harvesting, intelligent harvesting and accurate harvesting. © 2019, Chinese Society of Agricultural Machinery. All right reserved.