HYDRAULIC CIRCUIT FOR CONSTRUCTION MACHINERY HAVING FLOATING FUNCTION AND METHOD FOR CONTROLLING FLOATING FUNCTION

摘要

Disclosed are a hydraulic circuit for using a hydraulic fluid in a hydraulic pump in another hydraulic actuator, during levelling and grading work by means of an excavator, and a method for controlling a floating function. A hydraulic circuit for construction machinery having a floating function, according to the present invention, is provided with: two or more hydraulic pumps; a hydraulic cylinder connected to the hydraulic pumps; a boom driving control valve provided on the flow path between the hydraulic pump on one side and the hydraulic cylinder; a boom confluence control valve provided on the flow path between the hydraulic pump on the other side and the hydraulic cylinder; an operating lever; a first sensor for measuring the hydraulic fluid pressure of a large chamber of the hydraulic cylinder; a second sensor for measuring the boom lowering pilot pressure applied to one end of the boom driving control valve; a control valve provided on the flow path between the operating lever and the other ends of the boom driving control valve and the boom confluence control valve.