Speed Sensitive Control Closed Hydraulic System Engine Stall Issue Research

The closed hydraulic system widely applies in walking system of wheeled machinery because it has more advantages than open circuit hydraulic system, such as:better stability, more compact structure and avoiding the reversing impact. Throughout the existing walking system of wheeled machinery, the hydraulic pump adopts DA control and hydraulic motor uses HA control, which is the typical control mode. In some conditions, closed hydraulic system with this typical control method will appear engine stall phenomenon. According to walking system of wheeled machinery, this paper analyzes the principle of engine stall phenomena, proposes solutions and does relative experimental test.Firstly, analyze wheeled machinery from the following four aspects, power system, kinematics and dynamics and hydraulic system.Secondly, take general walk closed hydraulic system of wheeled machinery as the research object, establish and analyze the mathematic and simulation model. Analyze the flow continuity of walk closed hydraulic system with the hydraulic fluid mechanics, obtain mathematic model of general variable pump-variable motor. By AMESim simulation, in some conditions walk closed hydraulic system of wheeled machinery will appear engine stall phenomena. Get the reason of engine stall. On the above basis, the paper proposes programs of solving engine stall issue and build simulation model of these programs and analyze the results.Finally, build test platform of walk closed hydraulic system of wheeled machinery, and test speed curves of engine and motor, pressure curves of hydraulic system. The results show that:the split-flow program of this paper putting forward is sure to solve engine stall issue and verify the correctness of theoretical research and simulation model.