| The vehicle steering system is one of the main systems in the vehicle system,with the rapid development of the vehicle industry and the wide range of technology applications.Hydraulic power steering systems have been developed in many categories,such as: Hydraulic Power Steering Systems,electronic hydraulic power steering systems,electric hydraulic power steering systems,full hydraulic steering systems.Hydraulic steering systems are commonly used in agricultural machinery vehicles and construction machinery vehicles.The hydraulic steering system should firstly ensure the vehicle to have good handling stability and vehicle running safety.The working environment of the tractor is bad,the road condition in the field is complex and changeable,and the working objects have particularity,which makes the tractor have higher performance requirements on the handling stability and driving safety of the tractor.The tractor hydraulic steering system often appears the steering heavy,the malfunction and so on in the actual production process,therefore to the full hydraulic steering system performance test is an indispensable link.However,there are few loading systems developed for tractor hydraulic steering system,and the technology is not mature.Therefore,this paper designs a loading system for the full hydraulic steering system based on the full hydraulic steering system of The East Is Red The East Is Red tractor chassis,conduct in-depth experimental research.The main research contents are as follows:Hydraulic steering is the key component of the steering system in both agricultural machinery and construction machinery.The performance of the steering gear mainly determines the efficiency of the steering system.In this paper,the chassis of The East Is Red tractor’s hydraulic steering system is optimized and improved as the test object,and its hydraulic steering system is loaded.The main tasks are as follows:(1)Firstly,the paper summarizes the working principle,development status and loading system research status of several vehicle steering systems.The principle of turning resistance moment of tractor steering system is described,and the dynamic model of turning resistance moment of Dongfanghong 1204 tractor is established from axial and radial aspects of tractor steering system.The influence factors of each steering resistance moment of 1204 tractor are determined in two aspects.According to the empirical formula,the resistance range of the hydraulic steering system of Dongfanghong 1204 tractor under different ground conditions is calculated,and the load range of the hydraulic steering system is determined.It provides a theoretical basis for the design and research of hydraulic loading system.(2)To list the characteristics,functional differences and advantages and disadvantages of the existing loading modes on the market.According to the characteristics of the research object,the electro-hydraulic proportional loading is adopted in this research.The structure of full hydraulic steering loading test-bed is designed.The full hydraulic steering loading test-bed includes three parts: Hydraulic Pump Station,control unit and hydraulic loading system.The reasonable components are selected for three parts by type selection calculation.The designed hydraulic loading system can provide 0MPA,2 MPA,5MPA,6 MPA,8 MPA,9 MPA,10 MPAloading pressures for the Dongfanghong 1204 tractor to simulate the actual blocking of the full hydraulic steering system of the The East Is Red 1204 tractor.(3)Based on AMESIM simulation software,the designed full hydraulic steering loading system is built and simulated in the software.The loading performance curve of proportional relief valve and the parameter change curve of hydraulic components of 1204 tractor steering system were obtained by simulation test.The simulation results show that the designed hydraulic steering loading system has rapid response and stable loading pressure effect.It can meet the preliminary expected goal and provide the precondition and Test Foundation for the bench test.(4)Build and debug all parts of the test bench.Three tests(one for the hydraulic loading system and two for the full hydraulic steering system of The East Is Red 1204 tractor)were designed with reference to jbt5183-2002“Test methods for the static hydraulic steering system of wheeled tractors”.The actual dynamic response characteristics of the hydraulic loading system meet the design requirements,and the change law of the steering assist characteristic curve under the load pressure of 1204 tractor is obtained. |
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