Construction machine with floating function

Abstract

Disclosed is a construction machine with a floating function for performing soil preparation or the like for flattening the ground or the like using a dozer blade. The construction machine with a floating function according to the present invention comprises: a hydraulic pump and a pilot pump; a dozer cylinder connected to the hydraulic pump so as to move the dozer blade in the vertical direction; a control valve arranged in a channel between the hydraulic pump and the dozer cylinder; a dozer check valve arranged in the channel between the control valve and the dozer cylinder; a return check valve arranged in the channel between the control valve and a hydraulic tank; a solenoid valve for floating arranged in a signal path between the pilot pump and the dozer check valve such that the solenoid valve is capable of opening and closing; a channel for floating, one end of which is connected to the hydraulic tank and the other end of which is connected to the channel interconnecting the control valve and the dozer cylinder; and a check valve arranged in the channel for floating so as to supply working fluid to the dozer cylinder through the channel for floating from the hydraulic tank in a floating mode, and cut off the channel for floating when the floating mode is cancelled.

1 . A construction machine having a floating function, comprising:
 a hydraulic pump and a pilot pump, which are connected to an engine;   a dozer cylinder connected to the hydraulic pump and configured to move a dozer blade upwardly and downwardly;   a control valve installed in a flow path between the hydraulic pump and the dozer cylinder and configured to be shifted to control a start, a stop, and a direction change of the dozer cylinder;   a dozer check valve installed in a flow path between the control valve and the dozer cylinder;   a return check valve installed in a flow path between the control valve and a hydraulic tank;   a solenoid valve for floating openably/closably installed in a signal path between the pilot pump and the dozer check valve and configured to be shifted to an open state to supply a pilot signal pressure from the pilot pump to the dozer check valve to release a check function of the dozer check valve;   a flow path for floating connected at one end thereof to the hydraulic tank and connected at the other end thereof to a flow path for connecting the control valve to the dozer cylinder; and   a check valve installed in the flow path for floating, the check valve being configured to allow a hydraulic fluid to be supplied from the hydraulic tank to the dozer cylinder through the flow path for floating in a floating mode and to block the flow path for floating when the floating mode is released.   
     
     
         2 . The construction machine according to  claim 1 , wherein the flow path for floating is connected at the other end thereof to a large chamber of the dozer cylinder. 
     
     
         3 . The construction machine according to  claim 1 , wherein the flow path for floating is connected at the other end thereof to a small chamber of the dozer cylinder. 
     
     
         4 . A construction machine having a floating function, comprising:
 a hydraulic pump and a pilot pump, which are connected to an engine;   a dozer cylinder connected to the hydraulic pump and configured to move a dozer blade upwardly and downwardly;   a control valve installed in a flow path between the hydraulic pump and the dozer cylinder and configured to be shifted to control a start, a stop, and a direction change of the dozer cylinder;   a dozer check valve installed in a flow path between the control valve and the dozer cylinder;   a return check valve installed in a flow path between the control valve and a hydraulic tank;   a solenoid valve for floating openably/closably installed in a signal path between the pilot pump and the dozer check valve and configured to be shifted to an open state to supply a pilot signal pressure from the pilot pump to the dozer check valve to release a check function of the dozer check valve;   a flow path for floating connected at one end thereof to the hydraulic tank and connected at the other end thereof to a flow path for connecting the control valve to the dozer cylinder; and   a pilot check valve installed in the flow path for floating to open or close the flow path for floating, the pilot check valve being configured to be shifted to an open state by a pilot signal pressure supplied to the dozer check valve to supply a hydraulic fluid from the hydraulic tank to the dozer cylinder through the flow path for floating or to allow the hydraulic fluid discharged from the dozer cylinder to be returned to the hydraulic tank through the flow path for floating in a floating mode, and shifted to a closed state by interruption of the supply of the pilot signal pressure to the dozer check valve to block the flow path for floating when the floating mode is released.   
     
     
         5 . The construction machine according to  claim 4 , wherein the flow path for floating is connected at the other end thereof to a large chamber of the dozer cylinder. 
     
     
         6 . The construction machine according to  claim 4 , wherein the flow path for floating is connected at the other end thereof to a small chamber of the dozer cylinder. 
     
     
         7 . A construction machine having a floating function, comprising:
 a hydraulic pump and a pilot pump, which are connected to an engine;   a dozer cylinder connected to the hydraulic pump and configured to move a dozer blade upwardly and downwardly;   a control valve installed in a flow path between the hydraulic pump and the dozer cylinder and configured to be shifted to control a start, a stop, and a direction change of the dozer cylinder;   a dozer check valve installed in a flow path between the control valve and the dozer cylinder;   a return check valve installed in a flow path between the control valve and a hydraulic tank;   a solenoid valve for floating openably/closably installed in a signal path between the pilot pump and the dozer check valve and configured to be shifted to an open state to supply a pilot signal pressure from the pilot pump to the dozer check valve to release a check function of the dozer check valve;   a flow path for floating connected at one end thereof to the hydraulic tank and connected at the other end thereof to a flow path for connecting the control valve to the dozer cylinder;   a 3-way valve installed at a crossing point of the flow path for floating and the flow path on the control valve side, the 3-way valve being configured to be shifted to a first position (I) by a pilot signal pressure supplied to the dozer check valve to replenish a hydraulic fluid from the hydraulic tank to the dozer cylinder through the flow path for floating in a floating mode and shifted to a second position (II), in which the supply of the pilot signal pressure to the dozer check valve is interrupted to connect the flow path between the control valve and the dozer cylinder when the floating mode is released.   
     
     
         8 . The construction machine according to  claim 7 , wherein the flow path for floating is connected at the other end thereof to a large chamber of the dozer cylinder. 
     
     
         9 . A construction machine having a floating function, comprising:
 a hydraulic pump and a pilot pump, which are connected to an engine;   a dozer cylinder connected to the hydraulic pump and configured to move a dozer blade upwardly and downwardly;   a control valve installed in a flow path between the hydraulic pump and the dozer cylinder and configured to be shifted to control a start, a stop, and a direction change of the dozer cylinder;   a dozer check valve installed in a flow path between the control valve and the dozer cylinder;   a return check valve installed in a flow path between the control valve and a hydraulic tank;   a solenoid valve for floating openably/closably installed in a signal path between the pilot pump and the dozer check valve and configured to be shifted to an open state to supply a pilot signal pressure from the pilot pump to the dozer check valve to release a check function of the dozer check valve;   a flow path for floating connected at one end thereof to the hydraulic tank and connected at the other end thereof to a flow path for connecting the control valve to the dozer cylinder; and   a 3-way valve installed at a crossing point of the flow path for floating and the flow path on the control valve side, the 3-way valve being configured to be shifted to a first position by a pilot signal pressure supplied to the dozer check valve to allow the dozer cylinder, the control valve, and the hydraulic tank to fluidically communicate with one another in a floating mode and shifted to a second position in which the supply of the pilot signal pressure to the dozer check valve is interrupted to connect the flow path between the control valve and the dozer cylinder when the floating mode is released.   
     
     
         10 . The construction machine according to  claim 9 , wherein the flow path for floating is connected at the other end thereof to a large chamber of the dozer cylinder. 
     
     
         11 . The construction machine according to  claim 9 , wherein the flow path for floating is connected at the other end thereof to a small chamber of the dozer cylinder.