Research On The Piezoelectric Valve And Its Application In Train Braking System

Pneumatic technology is typically used in the braking system for pressure control in the urban mass transit. As the core of pneumatic technology, Electrical Conversion Unit, or pneumatic control valve, is directly related to the pneumatic control system performance. With the gradual maturity of piezoelectric materials and structure, the piezoelectric pneumatic control valves which are developed by the combined pneumatic technology and piezoelectric has better performance compared with electromagnetic valve. The thesis mainly puts the emphases on the design of piezoelectric valve model and the appliance technology in the braking system.The thesis describes the background of the pneumatic technology and train braking technology, analyzes the disadvantages of the braking technology, and studies the feasibility of combined pneumatic technology and new materials to the train braking system. The thesis still studies the piezoelectric bimorph working principle, the theoretical model and the manner of working; what's more, it tests the static and dynamic characteristics of piezoelectric bimorph, and does some comparison between the connection modes of piezoelectric bimorph.The thesis designs a proportional valve based on piezoelectric bimorph and the drive circuit, and builds closed-loop control model, and then it studies the performance of the response of the piezoelectric valve and the control precision of pressure control. We analysis the theory pressure control model of electrical proportional valve, and test the dynamic parameters of the response, then we design the control system using PID algorithm to testify the feasibility of the electrical proportional valve in the braking system.The thesis constructs a debugging verification platform of the newly braking system using virtual instrument--Labwindows/CVI, uses analog signals to simulate the train brake system incentives, and monitors the change process parameters during the braking process. That's the strong support for the development of SABC-I system based on piezoelectric valve.