Patent ID: 8875736
Filing Date: 2014-11-04
Classification: E02F,F15B,Y10T

Abstract:
1. A hydraulic control valve for heavy equipment, comprising: a valve body including a supply passage supplied with a hydraulic fluid from a hydraulic pump, ports for supplying the hydraulic fluid to an actuator from the supply passage or receiving the hydraulic fluid from the actuator, tank passages for returning the hydraulic fluid discharged from the actuator to a hydraulic tank, and a first regeneration passage for supplying a part of the hydraulic fluid returned from the actuator to the supply passage; a spool slidably installed in the valve body in accordance with supply of a pilot signal pressure from an exterior, and controlling flow of the hydraulic fluid supplied to the actuator from the supply passage during shifting, the spool having a second regeneration passage, formed therein, for supplying the hydraulic fluid from the first regeneration passage to the supply passage; a regeneration valve installed between the first regeneration passage and the tank passage, and including a piston moved by the hydraulic fluid from the hydraulic pump, a regeneration spool shifted by pressure fluctuation of the supply passage to variably adjust a flow rate of the hydraulic fluid discharged from the first regeneration passage to the tank passage via a return passage, a first resilient member for resiliently supporting the regeneration spool in a direction opposite to a shifted direction of the regeneration spool to increase an opening rate of the return passage, and a pilot piston for resiliently supporting a set pressure of the first resilient member; a stopper engaged with the pilot piston for controlling stroke of the regeneration spool such that the stopper is opposite to one end of the regeneration spool; an O ring mounted on an outer periphery of the regeneration spool for preventing a back pressure from being increased due to leakage of the hydraulic fluid from the first regeneration chamber to the back pressure chamber during the shifting of the regeneration spool; a pilot valve having a first state where the signal pressure supplied to the pilot piston from an exterior is interrupted, and a second state where the signal pressure is supplied to the pilot piston from the exterior by the supply of a signal pressure during the shifting of the regeneration spool; wherein the regeneration spool comprises a back pressure chamber, a sleeve and an external drain port formed on the sleeve that communicates with the back pressure chamber; and wherein the regeneration spool includes means, formed on a portion of an outer periphery of the regeneration spool, for preventing a flow force due to a flow rate generated during the shifting of the regeneration spool and for varying an opening rate of the return passage which communicates with the tank passage.