A method of operating a digging machine, including damping the response of a boom hydraulic cylinder operationally connected to a boom arm and actuating a bucket hydraulic cylinder operationally connected to a bucket.

Apparatus and method for enhanced grading control

The working equipment mass reduction is performed proceeding from the condition of the kinetic energy equality of the reduced mass and kinetic energy of the working equipment. Analytic connections of the boom hydraulic cylinder piston kinematic characteristics with the kinematic characteristics of the working equipment rotation are determined for the establishing of this dependence. Dependences of the working equipment reduced masses are obtained for different boom positions: transport, horizontal and maximum raised position of the working equipment. As opposed to similar researches in mechanical engineering the results of this research consist in the establishing of reduced masses dependences on the machine weight, its lifting capacity, boom positions for the machines size standard. Relative characteristics of the reduced mass depending on the lifting capacity and weight of the machine are obtained.

https://iopscience.iop.org/article/10.1088/1742-6596/858/1/012006/pdf

Regularities of the working equipment elements mass reduction to the hydraulic power cylinder piston for the bucket boom machines size standard

In the industrial, the level of liquid control in the tank is important. Level control in the tank can be done by manipulating the liquid flow rate, in order to obtain the appropriate level of the liquid set point. For that required selection of control mode and tuning method accordingly. Despite its popularity, PI (Proportional-Integral) control tuned with Ziegler-Nichols method, suffers from weird oscillation. In this paper, a remedy for PI controller is proposed with and the St. Clair method. As results, based on the level control of manipulated value (MV), the output trend is obtained with 0% oscillation change, the rise time is 1.71 seconds, and the settling time is 4.9 seconds. It shows a level control system with PI control and St. Clair is able to make the system stable against MV.

A remedy design of PI controller for liquid level control

This paper reports the simulation and experimental results of a type of widely used load control valve. The investigated load control valve is usually applied to the mobile crane booming hydraulic circuit. It is used to balance the overrunning load due to gravity and to modulate the flow of oil when lowering the load. The load control valve has a significant influence on the performance of mobile crane booming system. A simulation model of the load control valve is established based on AMESim, moreover, a bench-test is conducted to evaluate the performance of the load control valve. The simulation results and the experiment data agree well and both results show a good performance of the valve. Further study of the effect and the inner principle of the key design parameters of the load control valve are also presented.

Research on Characteristics and Key Design Parameters of a Pilot-Assisted Load Control Valve

In this work, a new solution of load control valve based on a hydraulic coupling two-stage principle is proposed. A detailed mathematical model of the valve has been developed. According the model, the steady-state and dynamic characteristics have been studied. The steady state study shows that the valve has an ideal piloted opening function which is not affected by the load pressure or back pressure alteration. Through an insightful analysis based on the linearized model, the dynamic study reveals that the main stage respond as a 1st order model which is smooth and fast enough compared to the pilot stage, while the pilot stage can be simplified as 2nd order model which may cause a problem of oscillation or overshot. The transition response of the valve is mainly decided by the pilot stage. Through the study of various parameters, the diameter of the orifice on the pilot piston shows its efficient influence in adjusting the poles in the pilot stage without affecting the steady state operation of the valve. An optimization based on root locus method is implemented and the poles have been deployed to the fastest points without oscillation.

Modeling and Characteristics Investigation on a Load Control Valve

Automobile crane luffing system is a variable load system. While the boom is being lowered, the constantly changing geometry results in a steadily increasing load pressure acting on the luffing cylinder. This requests the load control valve to have perfect performance including opening characteristic, jiggle characteristic, load pressure over-compensation characteristic and dynamic response characteristic. However the luffing hydraulic system with traditional load control valve has the problems of high system pressure, large impact and easily vibrated. This paper introduces the working principle of a new piloted follow-up load control valve first, and then develops a simulation model, which is validated by a series of experiments conducted on the automobile crane. Based on theory research and simulation, the working mechanism is analyzed and it demonstrates that the piloted follow-up load control valve have a opening characteristic independent of load, good jiggle characteristic under low control pressure, load pressure over-compensation, and smooth dynamic response without overshoot, which are all essential in automobile crane luffing system.

Haibo Xie

Papers

Research on Characteristics of the Piloted Follow-up Load Control Valve in Automobile Crane Luffing System