Hydraulic Excavators Energy-saving Control Technology

Hydraulic excavator is a kind of construction equipment with high power, and the energy saving controls will directly affect the economics and reliability of the excavator. The purpose of this paper is to study the energy saving controls and controllability of excavators, which can reduce heat generation of hydraulic system and reduce fuel consumption, and improve the performance of excavator to achieve high quality work. This paper consists of the following parts:1 -. First of all, the significance and development of energy saving controls of hydraulic excavatorin china and aboard are related, and then the developing tendency is summarized in this paper. For the sake of energy saving control research, this paper presents the design of an experimental excavating robot, which include hydraulic system design, steering system design, computer control system design and engine control system design, and describes in details the selection and properties of various components of robot, and presents a general framework of control programs to achieve various energy saving controls.2 > On the basis of the experimental excavating robot, several energy saving controls with multifunction valve control are investigated in this paper, which include negative control, positive control and load sensing control. Because of some defaults of these controls, this paper proposes some improvements on them, which have been proved to be effective in experiments. Meanwhile, this paper investigate the servo control of the excavating robot, proposes a trajectory planning scheme for excavating robot in which the trajectory is divided based on time interval, which can realize steady and precise trajectory tracing. A new kind of energy saving control called "negative load sensing control" is also adopted in hydraulic servo control process and the result is satisfactory. Apart from these, the paper also proposes several improvements for pump control, which include changeable cut off control that can prevent several kinds of relief loss of hydraulic system, cross sensing control of pump that can enlarge the variable working range and compound control that combine two kinds of valve control method together. It has been proved in experiments that these methods not only improve the efficiency of the hydraulic system, but also the controllability of excavator.3 > The power-load matching control of pump and diesel is also investigated in this paper, whichincludes economic working control and load limit control of diesel. To get further improvement in energy saving, a new control method is put forward in this paper. According to the method, the load of excavator is estimated according to the output pressure of pumps. Based on the result of the estimation of load, the engine speed and the torque absorption of pump are controlled to ensure that the engine power and working load are matched, and substantial reductions in fuel consumption can be achieved.It has been proved in experiments that with the combination of the energy saving methods that mentioned above, a satisfied result could be achieved. These methods can be realized on the basis of most hydraulic system and diesel control system of excavators with low cost, and they will be valuable for the future applications.