Development status and prospect of mechanical rolling shutter technology in solar greenhouse in China

Abstract: This paper describes the development of facility agriculture, which is represented by the facility vegetable. The facility vegetable has promoted the production of mechanical rolling shutter technology in solar greenhouse in the north of China since the 2000s. Solar greenhouse is a typical greenhouse type in the northern China, which can reduce greenhouse heat loss in the cold night by covering roller shutter and maintain the temperature indoor at a relatively steady state to meet the needs of crops growth inside solar greenhouse. The roller shutter can prevent crops from being irradiated by strong sunshine in the daytime and provide the necessary protection for the crops in the rain and snow weather. The length of a solar greenhouse is longer, if covering roller shutter completely relies on manpower. It is time-consuming and difficult to meet the light demands of crops growth in the daytime, which dominates crop production. In order to address this problem and meet the market demand, solar greenhouse rolling machine begins to appear on the market, which can replace manpower to achieve the rolling works and reduce the intensity of labor. And work time for rolling can be reduced to less than 20 min from 2 h in traditional manual work. Besides, solar greenhouse rolling machine can increase the illumination time of greenhouse crops, and promote crop growth and develop by its fast shutter speed. The paper points out that mechanical rolling shutter technology of solar greenhouse provides people a lot of convenience. Especially the rolling shade machine plays a positive role in planting crops in greenhouses in cold area of North China and promotes farmers to become rich. Rolling shade machine in China has the full intellectual property rights in technology. There are many types of rolling shade machines on the market. According to the different forms of the rolling shutter, the rolling shade machine can be divided into 2 types, the rear upper pulling type and the front upper pushing type. Besides, according to the difference of the support bar position, the front upper pushing type rolling shade machine can be divided side reel push type and push on the front reel. This paper introduces the development history of 2 kinds of rolling shade machines, and makes a comparison and detailed analysis of them, including the mechanical structure, working principle, and so on. In addition, in the development of mechanical rolling shutter technology, there are 3 key technologies: the speed redactor for mechanical rolling shutter, position measuring and controlling of rolling shutter. The speed redactor of rolling shade machine mainly includes spur geared wheel, worm and wormwheel, spur geared worm and worm-wheel, planetary gear with small teeth difference and external cylinder bevel gear. The position measuring and controlling part and technology of rolling shade machine mainly include mechanical limit switch, angle sensor and non-contact type position, sensor time-delay relay and indoor environmental sensor. In order to ensure the safety of rolling shade machine, the paper points out the present problems which occur frequently in solar greenhouse. The paper also puts forward a series of solutions which can be divided into 2 parts i.e. execution security and control security. At last, the paper points out the development trend of mechanical rolling shutter technology in solar greenhouse: The mechanical rolling shutter device will have higher efficiency and applicability, and mechanical rolling shutter security technology will get more attention. With the application of environmental sensor technology, and non contact measurement and control technology, the environment prediction model and control system for mechanical rolling shutter in solar greenhouse will get quick development and application.