Flow control apparatus for heavy construction equipment
View Patent ↗A flow control apparatus for heavy construction equipment is provided, which can prevent overspeed and abrupt operations of an actuator due to an excessive flow rate during an initial operation of the actuator when a composite work is performed by simultaneously operating an option device and another actuator, and can prevent the cut-off of hydraulic fluid supply to the option device due to an operation inability of a flow control valve when leakage of the hydraulic fluid occurs due to the increase of the temperature of the hydraulic fluid.
1. 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.
2. The flow control apparatus of claim 1 , further comprising a damping poppet orifice installed in a flow path for mutual connection between the back chamber of the logic poppet and the outlet-side path of the logic poppet.