Study And Design For Driving System Of Straddle-Type Monorail Tractor Based On Amesim/Simulink

In this thesis, the author makes a close study on the driving system ofStraddle-Type Monorail Tractor for Chongqing rail transit line3. For the problems ofrail transit line2in its actual operation, the author redesigns and analyses its drivingsystem in detail including optimalizing choice of driving ways, electro-hydraulicproportional control for variable displacement pump, driving automatic(DA) controltechnology which can resolve the problem of engine power matching, pressure cut-offvalve etc.The author proposes the general design program for straddle-type monorail tractorof the Chongqing monorail line3according to its actual operation situations. Based onthe analysis and calculation of the main loads of the tractor under different workingsituations, the author selects the way of hydraulic transmission as for its driving mode.Besides, the author calculates the main parameters of the hydraulic system and designsthe driving system which is suitable to monorail tractor. At last, the author draws theschematic diagram of the hydraulic system.Then the author builds a mathematical modeling for electro-hydraulic proportionalcontrol of hydraulic pump by using the AMEsim software and obtains the damping ratioof the proportional valve and the open-loop transfer function of the control system.Through the analysis of the frequency features for the control system, the author verifiesthat it meets the requirements of stability and speediness.In addition, the author employs DA control technology to solve the matchingproblem between engine and hydraulic system. Besides, a proportion relief valve isadded as a micro-motion auxiliary unit to avoid the control blind zone of DA-valvewhen the engine is at a high speed(>=1900rpm). In addition, the mentioned proportionrelief valve can optimize the effect of the DA control technology, reducing the pressureimpact on the pump control cylinder(PCC). The simulation results show that the DAcontrol technology with proportional relief valve can well control the displacement ofvariable pump and regulate the speed of the tractor in order to match the availablepower of the engine and prevent flameout of the engine because of overloading.Because the hydraulic system of the variable displacement pump will produce ahigh pressure peak when it speeds up or in other situations. As a result, it makes thehigh pressure relief valve open frequently which leads to the power loss and produces heat. Therefore, the author makes a study on the pressure shut-off valve which has thefunction of pressure regulating and analyzes its static and dynamic characteristics.Through the modeling and simulation in AMEsim, the result shows that the pressureshut-off valve can not only decline the rising ratio of system pressure but also reducethe energy loss. So the application of the pressure shut-off valve has broad developmentprospects.Up to now, there were few researches on straddle-type monorail tractors, moreoverthe price of the similar foreign products is relative high and the core technology iscontrolled. Therefore, this research has some significance in operation and maintenanceof the china-made monorail transit and the development of monorail tractor withself-owned intellectual property rights. Besides, some of the research methods andconclusions in this thesis can provide theoretical references for future research anddesign of the monorail tractors and the similar products.