Patent ID: 7059125

Claim:
A hydraulic controller for construction machine, comprising: a first and a second pump as variable capacity hydraulic pump; regulators provided in each of said first and second pumps to adjust a discharge flow rate of each of said pumps, said regulators being controlled in such a manner that one of said pumps absorbs a part of torque while the other thereof absorbs the remainder of the torque; a boom cylinder for driving a boom; a rotating motor for rotating an upper rotating body of the construction machine; a boom raising detection means for detecting a boom raising operation, said boom raising operation causing pressure oil from said first and second pumps to be joined together and then supplied to said boom cylinder; a rotation detection means for detecting a rotating operation of said upper rotating body, said rotating operation causing pressure oil from said second pump to be supplied to said rotating motor; a first pump pressure detection means for detecting a discharge pressure of said first pump; a second pump pressure detection means for detecting a discharge pressure of said second pump; and a flow rate distribution controller for controlling a flow rate distribution between said first and second pumps, said flow rate distribution controller being adapted to control said regulators, in case of a combined operation of boom raising and rotating detected by said boom raising detection means and said rotation detection means, in such a manner that a difference in discharge flow rate between said pumps is provided at the start of said combined operation so that said first pump has a higher discharge flow rate than said second pump, and then, on a steady rotating state of said upper rotating body with a difference in discharge pressure between said pumps to be a predetermined value or more, said difference in discharge flow rate is provided to be reduced.