Double check valve having floating function
View Patent ↗A double check valve having a floating function is disclosed, which can prevent construction equipment from overturning through intercepting of a floating function even if a signal pressure is fed to the double check valve to perform the floating function in a state that an excavator is supported by a working device (e.g. a dozer blade), i.e. in a jack-up state, on a sloping site and so on. The double check valve includes a hydraulic pump; a hydraulic cylinder connected to the hydraulic pump to operate a working device; a control valve installed in flow paths between the hydraulic pump and the hydraulic cylinder, and shifted to control a start, a stop, and a direction change of the hydraulic cylinder; and a double check valve installed in flow paths between the control valve and the hydraulic cylinder, and including a pair of plungers having first diaphragms formed thereon to receive an operating pressure being applied to the hydraulic cylinder and second diaphragms formed thereon to receive a signal pressure being applied to the signal pressure flow path, and a pair of check valves being pressed to remove their check function through shifting of the plungers. Sectional areas of the first diaphragms and the second diaphragms are different from each other.
1. A double check valve having a floating function, comprising:
a hydraulic pump;
a hydraulic cylinder connected to the hydraulic pump to operate a working device;
a control valve installed in flow paths between the hydraulic pump and the hydraulic cylinder, and shifted to control a start, a stop, and a direction change of the hydraulic cylinder; and
a double check valve installed in flow paths between the control valve and the hydraulic cylinder, and including a pair of plungers dividedly formed to be shifted in directions opposite to each other when a signal pressure is applied from an outside to a signal pressure flow path, and having first diaphragms formed thereon to receive an operating pressure being applied to the hydraulic cylinder and second diaphragms formed thereon to receive a signal pressure being applied to the signal pressure flow path in order to perform a floating function of the working device, sectional areas of the first diaphragms and the second diaphragms being different from each other, and a pair of check valves being pressed to remove their check function through shifting of the plungers;
wherein, if the signal pressure is applied from the outside to the signal pressure flow path and the operating pressure in the hydraulic cylinder is lower than a predetermined pressure, the check function of the check valves is removed, while if the signal pressure is applied from the outside to the signal pressure flow path and the operating pressure in the hydraulic cylinder is higher than the predetermined pressure, the check function of the check valves is maintained.
2. The double check valve of claim 1 , wherein the double check valve comprises:
a housing in which first flow paths for connecting the control valve to the small chamber of the hydraulic cylinder, second flow paths for connecting the control valve to the large chamber of the hydraulic cylinder, and the signal pressure flow path, into which a signal pressure for shifting the plungers is applied from an outside, are formed;
a pressing member for pressing the check valve for opening/closing the first flow paths;
a first elastic member for elastically supporting the pressing member so as to elastically bias the first flow paths, which have been blocked by the check valve, to their initial states;
a pressing member for pressing the check valve for opening/closing the second flow paths; and
a second elastic member for elastically supporting the pressing member so as to elastically bias the second flow paths, which have been blocked by the check valve, to their initial states.