Boom-swivel compound drive hydraulic control system of construction machine

Abstract

Disclosed is a hydraulic control system for matching the drive speed of a boom up and a swing device according to the operation environment when compound-driving for manipulating boom and swing for excavation compensating error operation. The hydraulic control system of the present invention comprises: an operation mode selection switch for enabling the selection of an operation mode according to the operation environment; an electronic proportional pressure control valve for outputting a control signal pressure that is proportional to the manipulation of the operation mode selection switch when manipulating a boom operation lever for driving the boom up; a variable flow control valve that is placed on a flow channel between a first hydraulic pump and a spool for the swing device, and has an open area thereof that is variably matched proportional to the control signal pressure from the electronic proportional pressure control valve; and a controller having various types of operation modes previously set and stored thereon so as to control the flow being supplied to the spool for the swing device and a spool for the boom merge, according to the operation mode selected when manipulating the operation mode selection switch.

1 . A hydraulic control system for a combined boom and swing operation of a construction machine, which includes first and second variable displacement hydraulic pumps, an actuator for a swing device and a work apparatus, which is connected to the first hydraulic pump, an actuator for a work apparatus connected to the second hydraulic pump, and a flow rate control valve configured to control a flow rate of a hydraulic fluid supplied respectively to the actuators for the swing device and the work apparatus from the first and second hydraulic pumps, the hydraulic control system comprising:
 a work mode selection switch configured to select a preset work mode according to working conditions;   an electronic proportional pressure control valve mounted in a pilot fluid path that discharges a pilot signal pressure according to a manipulation amount of a boom manipulation lever when the boom manipulation lever is manipulated to perform a boom-up operation, the electronic proportional pressure control valve being configured to output a control signal pressure that is in proportion to the manipulation of the work mode selection switch;   a variable flow rate control valve mounted in a flow path between the first hydraulic pump and a spool for the swing device, the variable flow rate control valve having an opening area variably adjusted in proportion to the control signal pressure of the electronic proportional pressure control valve; and   a controller configured to previously set and store various kinds of work modes according to working conditions to control a flow rate of the hydraulic fluid supplied to the swing device spool and a boom confluence spool according to a work mode selected when the work mode selection switch is manipulated,   wherein in the case where an operator selects a certain work mode according to the working conditions during a combined operation in which boom-up and swing manipulations are carried out, the flow rate of the hydraulic fluid supplied to the swing device spool and the boom confluence spool is variably controlled according to the selected work mode to adjust the driving speeds of the boom and the swing device.   
     
     
         2 . The hydraulic control system according to  claim 1 , wherein the electronic proportional pressure control valve is mounted inside the flow rate control valve. 
     
     
         3 . The hydraulic control system according to  claim 1 , wherein the electronic proportional pressure control valve is mounted outside the flow rate control valve. 
     
     
         4 . The hydraulic control system according to  claim 1 , wherein the variable flow rate control valve uses a variable orifice whose opening area is variably adjusted in proportion to the control signal pressure from the electronic proportional pressure control valve.