Research And Application Of The Throttling Grooves On Multi-Way Valve Spool Of Mini-Hydraulic Excavator

Hydraulic system is the key part of hydraulic excavator.It determines whether a excavator can complete operation requirements efficiently and in low-energy consumption.Multi-way valve,as one of the key components of hydraulic system in excavator,determines the oil direction and flow rate which is supplied by the hydraulic pump,so as to control the motion direction and speed of hydraulic actuator.This paper takes the multi-way valve in hydraulic excavator with LUDV system as the research object.In oeder to meet the operation requirements of excavator,some notches with different shape and dimention are sloted on the piston endstops of the multi-way valve main spool.Different orifices are generated when the valve body and spool are combined in different positions. When the valve spool moves in valve body, each of the inlet and outlet oil line has one orifice to act at the same time.The flow area of the orifice determines the flow rate into actuator. So the matching conditions of the notches in the two orifices determines the motion speed and loading capacity of the actuator.Designing the notches reasonably is the foundation of multi-way valve design.This paper analyzed the calculation methods of flow area for throttling groove such as U-notch,triangular notch,U+U notch and so on, and then builded the mathematical model. Based on the theoretical analysis,a interactive calculation system was developed by using Visual Basic language. This system possessed the function of flow area calculation of throttling grooves and saving & searching data.Furthermore, it can analyze and compare the flow areas for different kinds of throtling grooves and then obtain the flow characteristics.Based on the calculation system,this paper took a 7t excavator prototype to analyze the influence of the throttling grooves in the multi-way valve main spool on the rising and descending speed of swing arm,and calculate the rising and descending time.In addition,this system calculated the propotion of the flow areas in inlet and outlet oil line to guarantee the bucket rod descending in stable speed,which can solve the problem that the bucket rod descending speed would decrease when the load direction of the bucket rod hydraulic cylinder change.In the end,experiments were done to test the fast rising and descending time.The error between the test results and the calculation results is small,which proves that the mathematical model of the flow area is correct and the analysis results of the prototype are reasonable.