Rotary hydraulic system is one of the most important systems in excavator hydraulic system. It directly affects the safety, operation efficiency, energy consumption and operation comfort of the whole machine. This paper analyzes the constant power hydraulic system of small hydraulic excavator in detail, and divides it into several basic circuits, so as to analyze the operation principle of each circuit and the relationship between different circuits; On the premise of meeting the performance requirements of multi-way valve, the structure of throttle groove of rotary coupling valve core of multi-way valve is improved to simplify the processing technology, reduce the processing difficulty and improve the processing efficiency. The internal flow field of old and new valves is simulated; The rotary hydraulic system with old and new valves is simulated with AMESim software. The following conclusions are drawn:
(1) The complex hydraulic excavator system is divided into several simple basic circuits. It is conducive to the detailed analysis of the characteristics of each action and the trend of hydraulic oil circuit, which is convenient for system improvement and fault analysis.
(2) The area curve of gradually expanding U-groove valve port of multi-way valve is obtained. Using Mathcad software to draw the area function of the old valve port, it is found that the change trend of the valve port area conforms to the operation characteristics of the rotary motor. At the same time, the new valve port area curve is drawn, and it is found that the new and old multi-channel valve port area curves are basically consistent. This shows that the rotation speed, starting and braking performance of the swing motor have not changed.
(3) Compared with the original valve, the steady-state hydrodynamic force of the new valve is reduced, the left-right oscillation of the valve core is small, the flow fluctuation at the valve port is small, and the speed stability of the hydraulic actuator is good; The lateral force of the new valve is very small, almost zero, which effectively reduces the additional resistance of the main valve core caused by the lateral force and prevents the main valve core from moving inflexibly, blocking and blocking.
(4) Through AMESim system simulation of the rotary hydraulic system, it is found that the motor inlet and outlet pressure, output flow and output torque in the new valve rotary system are basically consistent with the original valve system.
This paper has some innovations in the following aspects:
(1) The geometric calculation model is established, and the calculation formula of gradually expanding U-groove valve port area machined by end milling cutter is deduced.
(2) Based on the principle of constant performance, the structure of multi-channel valve core throttling groove is improved to simplify the processing technology and improve the processing efficiency.
