Study On The Shifting Process Of Hydro-mechanical Continuously Variable Transmission Based On Electro-hydraulic Ratio Control

Hydro-mechanical Continuously Variable Transmission(HMCVT)has the advantages of hydraulic transmission and mechanical transmission,a high transmission efficiency and a large transmission power.It has used double power split transmission mode,the engine power allocated to the mechanical parts and the hydraulic parts.The device is mainly used in high-power tractors.Not only it is possible to improve the fuel economy and the dynamic,but also can it reduce the complexity of the actual operation substantially,better for the driver's driving operation.In this paper,based on the high-power tractor HMCVT,and studied the characteristics of HMCVT segment change process.According to electro-hydraulic proportional control system to study the other segments of the oil-filled pressure characteristic of wet clutch and the continuity of the HMCVT segment.And the factors of the HMCVT shift process were analyzed.In order to reduce the attack of the Shift process and shorten the time of the shift process,and achieve the goal to improve the quality of the shift.The main contents of this paper are as follows:1.First,the principle of HMCVT transmission are introduced.Then the speed characteristics,torque characteristics and power characteristics of each HMCVT section were analyzed as a careful.2.Analyzed the causes of the shift process that change section shocks,and listted the index of shift quality evaluation.Analyzed the characteristics of the segment change of solenoid valve wet clutch and designed electro-hydraulic proportional control system by proportional relief valve and proportional flow control valve,in order to achieve the continuity of the shift process.3.To Use AMESim modeling and simulation software to set up various components test models of the HMCVT to be used in the simulation,and analyzed the shift process by the overall model.4.To study exchange section process by electro-hydraulic proportional control system.The size of the flow was controlled by electro-hydraulic proportional,to change the overlap time of C1 clutch and C2 clutch exchange process segments;The pressure was adjusted by electro-proportional relief valve,in addition to load torque conditions,to change the time of sliding friction of the shift.Finally,the shift clutch charge pressure,transmission output shaft speed,transmission output shaft torque and the main oil pressure were analyzed.