Patent ID: 7987764

Claim:
A flow control apparatus for heavy construction equipment, comprising: a hydraulic pump; an actuator for option devices connected to the hydraulic pump; a variable control spool installed to be shifted by pilot signal pressure in a flow path between the hydraulic pump and the actuator; a switching valve installed to be shifted by a difference between pressure in an inlet-side path and pressure in an outlet-side path of the variable control spool; a logic poppet installed to open/close a high-pressure path of the hydraulic pump by a difference between pressure in the high-pressure path and pressure passing through the switching valve; a groove formed on a sliding surface of the logic poppet; and a flow path for connecting the groove to an outlet-side path of the logic poppet; wherein, if leakage of hydraulic fluid through a gap formed on the sliding surface of the logic poppet occurs due to an increase of hydraulic fluid fed from the hydraulic pump or an increase of a temperature of the hydraulic fluid to a high temperature, mutual connection between the outlet-side path and a back chamber of the logic poppet is intercepted by the groove and the flow path.