Research On The Hydraulic System Of A Trawler

The ocean covers about71%of the earth’s surface, and its vast area has bred abundant natural resources. With the growing shortage of land resources, more and more countries are turning their attention to the ocean. Fishery resources are the earliest ocean resources that human have developed, and it supplies plenty food and nutrients for people’s lives. Trawling has relatively high production efficiency among all fishing operations, and it accounts for40%of the total ocean fishing production. Ocean fishing is the main body of domestic fishery, and it accounts for more than80%of the total domestic fishing production. Most fishing equipments in domestic fishing vessels are relatively undeveloped, and large sums of foreign exchange are spent on purchasing fishing equipments. Developing advanced fishing equipments is the key technique of trawlers. It can not only reduce the cost of fishing, but also improve the efficiency and reliability of fishing system.The first chapter introduces the present situation of ocean fishing and the important role of trawling in ocean fishing, and then puts forward constant tension trawling; based on a large number of domestic and foreign patents and literature, the advantages of constant tension trawling were discussed; combined with the present situation of domestic trawling, the significance and main research content of the subject are presented.In Chapter2, the overall design of hydraulic system of the trawler basing on the needs of winches are completed; the pressure and flow rate of each winch hydraulic system are calculated according the demanded power, and then the hydraulic schematics are designs. The type selection and structure design of key valves are also finished.In Chapter3, the pumping station basing on the pressure and flow rate demand of winch hydraulic systems is designed, and two feasible schemes are also put forward, and then the two solutions were compared. The relationship diagrams of pumping stations and winch hydraulic system were created, and then the installation form of pumping stations were designed according to the installation space.In Chapter4, the mathematical models of proportional pressure relief valves, proportional flow valves and hydraulic motors are established, transfer function of key components are calculated, and then the control diagrams of the hydraulic system were drawn.In Chapter5, the key components and the functions of the trawling hydraulic system are simulated by modeling. The correctness of the loop is verified and then constant tension trawling experiments were carried out which further proves the feasibility and practicability of the hydraulic systems.