Engine controller for the hydraulic circuit of a construction machine

摘要

A hydraulic drive device for a construction machine (1) which can reliably judge whether or not the state of the construction machine is appropriate for stopping an engine is provided. The hydraulic drive device includes: a main pump (13); a regulator (15) that controls the discharge rate of the main pump (13) by a control pressure Pc; an engine (16) that drives the main pump (13); an engine stopping unit (83) that stops the engine (16) when a predetermined state of the construction machine has continued for a predetermined period of time; and a pressure sensor (72) that detects the control pressure Pc. The engine stopping unit (83) has a control signal judging unit (84) that judges whether or not the control pressure Pc detected by the pressure sensor (72) is lower than a predetermined pressure value Pc1, as a judgment of whether or not the predetermined state of the construction machine is present. The engine stopping unit (83) stops the engine (16) when a judgment result that the control pressure Pc is lower than the predetermined pressure value Pc1 is obtained. The predetermined pressure value Pc1 is a pressure value for controlling the discharge rate of the main pump (13) to the lower limit for use in the construction machine.