Patent ID: 9243385
Filing Date: 2016-01-26
CPC Classification: B62D,E02F,F15B,Y10T

Claim Text:
1. A hydraulic system for construction machinery having a steering unit for controlling steering of equipment, and a main control valve for controlling operating of a work tool, the hydraulic system comprising: a main pump configured to discharge working fluid supplied to the steering unit and the main control valve; a load sensing pressure sensor configured to sense a load sensing pressure of the steering unit; a priority valve installed in a supply passage for the working fluid discharged from the main pump, configured to divide and supply the working fluid discharged from the main pump to the steering unit and the main control valve, to correspond to the load sensing pressure; an auxiliary pump configured to supplement working fluid to the supply passage supplying the working fluid divided by the priority valve to the steering unit; an electric motor configured to operate the auxiliary pump; a controller configured to: a supply flow sensor configured to sense a supplied flow that is a flow of working fluid discharged from the main pump and supplied to the steering unit, wherein the controller operates the electric motor when the load sensing pressure is greater than a reference load sensing pressure and the supplied flow is less than a preset first reference flow.