The Flow Characteristic Of Nonsymmetrical Piston Pump And Its Use In Hydraulic Excavator Boom Loop

Hydraulic excavator is one of the most commonly used earth mover, as one kind of the multi-functional engineering machineries, because of its powerful multi-functional adaptation,Hydraulic excavator has a very important role in the construction machinery, and has a great potential in the whole world market. Currently, most of the hydraulic excavators used the variety of valves to control the pressure, flow and direction of hydraulic system, this based on the hydraulic control system traditional hydraulic excavator is called valve excavator. Because of the rapid development of various types of direction valves, pressure valves and flow control valve,valve-hydraulic system theory has developed very completely, Valve-hydraulic excavators has a very large market shareBecause of the unavoidable valve throttling losing issues on the valve-hydraulic system, the installed power must be increased, at the same time, the valve-hydraulic excavators appears a lot of other problems:in using too much fuel, high fuel consumption, poor emissions, hydraulic system heat, low efficiency. In recent years, with people's environmental awareness is growing, the demands for energy efficiency is increased, the competition between various control technologies and the transmission of hydraulic system is increasingly fierce, the energy saving excavator will inevitably be the direction and trend of excavator, hydraulic excavator engineering facing the great technical innovation in energy saving. How to reduce the energy consumption of hydraulic excavators and improve the energy efficiency is the main objective of national manufacturers. And this is the basic starting point of the paper, too. Valve-hydraulic system itself has been the technical problem in constraints the further development of excavator technology.In this paper, the author attempts to introduce the pump directly control system into the working part of a mini-hydraulic excavator system, the working parts of the mini-hydraulic excavator hydraulic system is derived by a group of differential hydraulic cylinders, as the two chambers'area of the differential hydraulic cylinder are not equal, so the oil flow in two chambers are not equal to. In order to use the pump direct control hydraulic system to closed control the differential cylinder loop, the two ports output of the hydraulic pump must meet the oil outputting are not equal, so as to compensate the two chamber flow. The traditional axial piston pump has two symmetrical arranged flow windows, so the oil outputting of the two oil ports are equal. When it used in the closed control loop, it only fit in controlling of hydraulic motor and a symmetrical double-rod hydraulic cylinders system. When it used in closed control loop of differential hydraulic cylinder system, there will be a lot of problems, such as over-pressure, cavitations, so the traditional axial piston pump can not be directly implemented in the closed control loop of differential hydraulic cylinder system.To address the above problems, this paper based on the new assignment principle of the research group, and designed the new types of hydraulic pump to put in use of closed control differential hydraulic cylinder loop. Based on the new assignment principles, there are two forms of the new hydraulic pump, which are series three windows axial piston pump and parallel double-acting axial piston pump. This paper is begin from the realization method of control system in the new hydraulic excavator, detailed introduced the pump control system key components the new hydraulic pump, from the modeling analysis, simulation calculation, and the three-dimensional solid modeling to create the physical prototypes, and by the comparison between the simulation results and the physical prototypes experimental results in different working mode, we finally get the reasonable structure parameters of the new pump key components, and the effection of pressure fluctuation in the prototype is reach to the same level of the existing pump.This paper is by using of variable pump integration solutions on direct closed control differential hydraulic cylinder loop, and the new complete hydraulic pump model is used in the small hydraulic excavator arms cycle, so as to built up the pump controlled mini-hydraulic excavator model, and the comparison and analyzing between the traditional one and the new pump controlled one will be list in this paper. By the comparison, we can get that by using the new single pump can realize the closed pump controlled system in the mini-hydraulic excavator system. The aim of this paper is to make a certain theoretical basis and test trying to further promote the using of direct pump controlled system in engineering areas.The research is following the principle of the key components analysis, at the same time; this paper systematically introduces the software platform-multi-disciplinary simulation software SIMULATIONX. This paper is begin from the subject characteristics, build up the 3d models in software of Pro/E, then import the 3D models to the multidisciplinary simulation software SIMULATIONX, and by this software platform, this paper finish all the simulation calculation and multibody dynamics analysis.