Hydraulic circuit having holding valve of external pilot pressure operation type

Abstract

A hydraulic circuit having a holding valve of an external pilot pressure operation type is provided, which can make a double check valve, which is installed to prevent an actuator from being pushed due to leakage of hydraulic fluid of a main control valve, be opened by an external signal pressure being supplied to shift the main control valve. The hydraulic circuit includes a hydraulic pump connected to an engine and a pilot pump, a hydraulic cylinder connected to the hydraulic pump to expand and contract when hydraulic fluid is supplied thereto, a main control valve installed in a flow path between the hydraulic pump and the hydraulic cylinder and shifted to control a start, a stop, and a direction change of the hydraulic cylinder, a joystick outputting a pilot signal pressure from the pilot pump in accordance with an amount of user's manipulation thereof, a double check valve installed in a flow path between the main control valve and the hydraulic cylinder to be opened by the pilot signal pressure for shifting the main control valve, and preventing the hydraulic cylinder from being moved due to leakage of hydraulic fluid of the main control valve, and a select valve shifted to open the double check valve in response to the pilot signal pressure being supplied in accordance with the manipulation of the joystick.

Description

[0001] Cross References to Related Applications [0002] This application is based upon and claims the benefit of priority from Korean Patent Application No. 10-2007-0127657 filed with the Korean Intellectual Property Office on December 10, 2007, the entire disclosure of which is incorporated herein by reference. technical field [0003] The present invention relates to a hydraulic circuit having an external pilot pressure operated type lock valve capable of preventing or attenuating an actuator (such as a hydraulic cylinder, etc.) Consistent push phenomenon (push phenomenon). [0004] More specifically, the present invention relates to a hydraulic circuit having an external pilot pressure-operated lock valve, which enables double check valves installed to prevent actuator advancement due to leakage of hydraulic fluid from the main control valve, by External signal pressure supplied to shift the main control valve to open. Background technique [0005] Such as figure 1 As...

AI Technical Summary

Problems solved by technology

Therefore, it is difficult to manipulate the work implement sensitively, thereby lowering the maneuverability, and this may cause sudden operation of the hydraulic cylinder 1

[0012] Also, the check valve 4 repeats the instant opening / closing operation under certain working conditions, and thus a chattering phenomenon occurs, resulting in severe vibration and noise