HYDRAULIC CONTROL DEVICE OF OPERATING MACHINE

摘要

An engine-driven hydraulic pump (2), a hydraulic actuator (3), and a negative control circuit (4) are provided on an open-center hydraulic circuit (10), and the hydraulic pressure of a center bypass is introduced as a negative control pressure to the hydraulic pump (2). Further, a negative control pressure control means (6) which controls the negative control pressure at a predetermined value is provided on the negative control circuit (4). The characteristics of the hydraulic pump (2) are determined so that the discharge flow rate is minimum when the negative control pressure of the negative control circuit (4) is not less than a first predetermined pressure. Further, an idling detection means (5) which detects whether or not the hydraulic actuator (3) is in the inactive state is provided to forcedly control the negative control pressure so that the negative control pressure is equal to or more than the first predetermined pressure when the inactive state is detected.