The Research Of The Electro-hydraulic Automatic Level System Of The High-altitude Working Machine

The high-altitude working machine has been widely used in architecture, city planning, aerodrome, factory, garden, house and other places. It plays an important role in fire protection, dealing with an emergency, construction, installation, maintenance and so on. Aiming at the CDZ22 high-altitude working machine of XuZhou engineering machinery Group, this thesis adopts three electro-hydraulic methods to realize the automatic level control system. It does a lot of theoretical research and experiment test.In Chapter 1, firstly introduces the basic principle, the development and the research actuality in China and foreign contries of the automatic level system of the high-altitude working machine. Then summarizes the key factors which influence the system performance. Next, compares the high speed on/off valve and proportional servo valve which will be used in the next few chapters. At last, describes the research significance and the research contents.In Chapter 2, uses the high speed on/off valve as the pilot-operated valve and cone-shaped valve as the secondary valve, so it can reach the flow rate 40L/min. The system depends on the switch action of the high speed on/off valve in the return line to adjust the return oil, and then realizes the automatic level control of the working platform. So it's a meter-in circuit. In mechanism, chooses the type of some necessary components, designs the structure of the valve element, valve sleeve and the valve base which connects the flow pipeline. In circuit, designs a control board which adjusts the level automatically in real time. The board firstly receives the signal from the angle sensor, deals with it, and then outputs several signals to control the solenoids. Next, sets up the mathematic model of the high speed on/off valve controlling the cone-shaped valve, and uses Simulink toolbox in Matlab to programe S function to realize the simulation analysis. When inputs a PWM pulse to the high speed on/off valve, gains the movement curves of the valve element displacement, pressure and flow rate. At last, assembles the whole system to do the experiment, simulates the working state of the high-altitude working machine. The result proves that the system works very well.In Chapter 3, uses the high speed on/off valve as the pilot-operated valve and slide valve as the secondary valve. Firstly, chooses the type of some necessary components, designs the structure of the valve element, valve sleeve and valve base.Then designs a control board. At last, does several experiments with the whole system.