Patent ID: 7878770
Filing Date: 2011-02-01
Classification: E02F,F15B

Abstract:
1. A hydraulic circuit of construction machine comprising: operation means; a controller for outputting a command current based on an operation amount of the operation means; an electromagnetic proportional pressure reducing valve actuated by the command current outputted from the controller; and a hydraulic spool valve actuated by a secondary pressure from the electromagnetic proportional pressure reducing valve, the spool valve being configured to change a pump pressure in response to a change in an opening area of the spool valve, wherein a degree of change in the pump pressure by the hydraulic spool valve to a change in the proportional valve command value exhibits at least one inflection point at which there is an inflection in the degree of change in the pump pressure for a predetermined change of the proportional valve command value; the controller having correction processing means for correcting the proportional valve command value, comprising: