Research On Multi-way Directional Valve With High-speed On-off Valve As Its Pilot Valve

The history of the shovel loader development has been almost a hundred years.At present, hundreds thousand of shovel loaders are working at the mines, railroads, frontiers, ports and construction fields, the products are all over the nation. It becomes a widely used engineering plant and plays an important role in the development of the national economy. The hydraulic multitandem valve of the traditional shovel loader relies on lever principle, inverts direction by directly connecting or with wire flexible shaft connects to the valve handle. People need to overcome the spring force, hydraulic force and friction force to move the handle of the reversing valve. With the power augmentation of the wheeled shovel loader and the development of the hydraulic technology, the hydraulic system is developing to the high pressure and huge float rate.The operators are usually tired by long time operating the multitandem valve, because they should use enough strength to operate it.Meanwhile, with the augment of the float rate, the size of the hydraulic component are also increased, it is difficult to install the hydraulic component. The pilot hydraulic operating method can also operate the reversing valve, valve bank is made of pilot valve and main reversing valve,these two valves are connected by a pilot control hydraulic circuit, the operaters only need to operate the pilot valve to controll the main valve, this will largely ease the fatigue of the users, and it also brings lots of convenience to equip the hydraulic system. So the multichannel conversion valves are widely used in the engineering plants.High speed switch valves are simple, reliable,low price and easily repair. But with the limitation of the high speed switch valve, it is difficult to use on the huge float rate hydraulic system of the shovel loader. In view of this ,this paper aims to create a huge float rate digital ratio control system for the pilot multitandem switch valve,and this will largely increase the operability, security and comfort. The principle of the digital electrohydraulic control system in this paper is to control the pressure of multitandem valve by using the high speed switch valve,and get pressure difference,overcome the spring force to push the multitandem valve to control direction and size of the port to control the switch and float rate.This paper makes an analysis on the controll principle of high speed switch valve pressure and its dynamic characteristic,then creates a mathematical model and makes an emulation.In addition, this paper coMPares different controlling means and chooses the self-adapting fuzzy PID control,creats a emulation platform which combined AMESim with MATLAB and emulate the rotating bucket hydro cylinder system.By coMParing with the common PID control method,it shows that the self-adapting fuzzy PID controller works better.At last,makes a preparation for the entire experiment with the existing conditions in the laboratory.Firstly, designs the elementary diagram of the experiment, and then analyzes the hardware equipment and software equipment of the experiment respectively,marks the displacement sensor and the flow sensor,in the end, tests the idle load flow curved line of the high speed switch valves. Makes a preparation for the latter experiment. The following are the main work of this paper:1.Gives an outline of the development of the shovel loader and digital control,and makes a simple analysis on the working equipment of the hovel loader, describes the multitandem valve working principle of the traditional shovel loader and shows its deficiency,then raises a plan that uses the high speed switch valve to control the multitandem valve.Then,this paper proves the feasibility of this plan.2.Introduces the multitandem valve and high speed switch valve detailedly. Firstly,introduces the the structure,characteristic, loop control form, control plan and the principle of control of the high speed switch valve. and then introduces the model nummber, characteristic and working principle of the multitandem valve which this paper used.At last,creates the system principle diagram of high speed switch valve controls the multitandem valve.3.Analyzes the system by creating mathematical model.Firstly, introduces the characteristics of the software which this paper used, and then analyzes the dynamic characteristic of the multitandem valve pressure and makes an emulation on it.The result of the emulation shows that the system has a good dynamic characteristic. At last,analyzes the principle of high speed switch valve controls the main case,creats a model of the high speed switch valve controls the multitandem valve system in the AMESim, it shows that users can regulate the valve case of reversing valve by regulating the dutyfactor of high speed switch valve, proves the high speed switch valve can control the multitandem valve effectively,proves the feasibility of the system plan.4. Besides system controlled resolution, working reliability and using component properly,the design of controller is also very important. It is better to choose advanced control plan to solve practical problem, as the system control plan is the core of the whole system control technique. Different control plan has different control effect, so it is meaningful to make a research on the system control plan. In view of this,according to self-adapting fuzzy PID control theory, this paper designs a self-adapting fuzzy PID controller, makes an emulation with AMESim and MATLAB, and makes a fully use of these two software, creates a simulation model, designs a PID controller and self-adapting fuzzy PID controller. By coMParing these two controllers, it shows the effect of self-adapting fuzzy PID controller is much better, and it is feasible in theory.5.According to the system principle diagram, makes a preparation for the entire experiment. Firstly, designs the elementary diagram of the experiment, and then analyzes the hardware equipment and software equipment of the experiment respectively, marks the displacement sensor and the flow sensor, in the end, tests the idle load flow curved line of the high speed switch valves. Makes a preparation for the latter experiment.