| Forklift widely applied in railway, ports, airports, railway stations, warehouses and factories and such places, it used to complete loading and unloading, and palletizing, and short handling work. The use of forklift eased the labor intensity, realized the logistics mechanical work, promoted the development of the logistics industry. Along with our country the rapid development of economy, the market for forklift truck demand is growing rapidly, the standard for forklift truck working control system is getting higher and higher.At present, In our country, forklift working device control system, generally adopted manual-control hydraulic reversing valves movement, to control the oil-way direction, and achieve control of hydraulic cylinders work. Use this control system, working efficiency is low, couldn't achieve fine control, also did not realize intelligent, need larger manipulate force, working noise, operation is not even etc. This kind of situation, put forward higher requirement for our country forklift working device control system.Reference some engineering vehicles working device control system, to the original forklift job device control system were improved, this thesis proposes a set of digital electro-hydraulic proportional control system:adopt computer module control electro-hydraulic proportional valve, and electro-hydraulic proportional valve control reversing valves, and to control the hydraulic cylinder work, finally complete homework tasks; at the same time, computer control module receiving forklift work feedback information. The computer control module is high technology products in national "863" high-tech project, which has been successful in development, and has independent intellectual property rights. The core of the system is to control the pilot valve. Control signal is PWM signal. Around forklift job device electro-hydraulic proportional control system, the thesis mainly completed the following several studies work:1. Sure improved forklift job device electro-hydraulic proportional control system composition, studies the control process and principles.2. Research the control system PID control algorithm and PWM control principle; Introduces the system control software and work device automatic positioning system; Design a new scheme that the goods fork movement.3. Proportion pilot valve and multi-way directional valve established the mathematical model, with MATLAB/simulink software for computer simulation, to verify they work in the system.4. Do the experiment for forklift truck electro-hydraulic proportional control system in the laboratory and forklift.Simulation and experimental results show that, using the improved control system control forklift job is feasible. It improved the original domestic forklift job equipment control performance, improved forklift truck operation control performance, improve the working efficiency. After using the control mode, hydraulic valves no rigid connection, can according to the condition, remote decorate hydraulic loop; Introducing computer control module for forklifts introduced intelligent control system, which can realize automatic positioning function.The 21st century is the highly developing century in electromechanical integration, automation and intelligent. In order to promote our country logistics rapid development, to narrow the gap with foreign advanced forklift, we need unremitting efforts and exploration, continuously research high quality forklift that could meet various needs.
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