EP2937472A1 - Construction machine with floating function - Google Patents
Construction machine with floating function Download PDFInfo
- Publication number
- EP2937472A1 EP2937472A1 EP12890478.6A EP12890478A EP2937472A1 EP 2937472 A1 EP2937472 A1 EP 2937472A1 EP 12890478 A EP12890478 A EP 12890478A EP 2937472 A1 EP2937472 A1 EP 2937472A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- dozer
- floating
- flow path
- check valve
- cylinder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/76—Graders, bulldozers, or the like with scraper plates or ploughshare-like elements; Levelling scarifying devices
- E02F3/80—Component parts
- E02F3/84—Drives or control devices therefor, e.g. hydraulic drive systems
- E02F3/844—Drives or control devices therefor, e.g. hydraulic drive systems for positioning the blade, e.g. hydraulically
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2285—Pilot-operated systems
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2292—Systems with two or more pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/003—Systems with load-holding valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/30505—Non-return valves, i.e. check valves
- F15B2211/3051—Cross-check valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3122—Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
- F15B2211/3127—Floating position connecting the working ports and the return line
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/77—Control of direction of movement of the output member
- F15B2211/7741—Control of direction of movement of the output member with floating mode, e.g. using a direct connection between both lines of a double-acting cylinder
Definitions
- the present invention relates to a construction machine having a floating function. More particularly, the present invention relates to such a construction machine having a floating function, which can perform a ground leveling work or a grading work in which the ground is flattened and leveled using a dozer blade.
- the floating function means a function in which a dozer blade is moved upwardly and downwardly along a rugged ground surface by its own weight or an external force even without a manipulation of a manipulation lever by an operator during the traveling of the construction machine. Even when the construction machine is simply manipulated to be traveled by the floating function, a ground leveling work or a grading work can be performed in which the ground is flattened and leveled by the dozer blade moved upwardly and downwardly.
- a construction machine having a floating function in accordance with the prior art includes:
- a hydraulic fluid discharged from the hydraulic pump 2 is adjusted in flow rate by a dozer spool 5a of the control valve 5, and then is supplied to the dozer check valve 6.
- the hydraulic fluid supplied to the dozer check valve 6 converts the state of a pair of check valves of the dozer check valve 6 into an open state, and is introduced into a large chamber or a small chamber of the dozer cylinder 4.
- the introduced hydraulic fluid drives a piston of the dozer cylinder 4 so that the dozer blade (not shown) can be moved vertically.
- a hydraulic fluid discharged from the dozer cylinder 4 by the drive of the piston of the dozer cylinder 4 passes through the dozer check valve 6, the dozer spool 5a, and the control valve 5 in this order and is returned to a hydraulic tank 7 via the return check valve 8.
- a spool of the solenoid valve 9 for floating is shifted to the bottom on the drawing sheet in response to an electrical control signal applied to the solenoid valve 9 for floating.
- a pair of check valves within the dozer check valve 6 is converted to an open state by a pilot signal pressure discharged from the pilot pump 3 and applied to the dozer check valve 6 via the solenoid valve for floating 9.
- the conversion of the dozer check valve 6 releases a check function of restricting the returning of a hydraulic fluid to the dozer cylinder 4.
- a piston of the dozer cylinder 4 is driven by the dozer clylinder' s own weight or an external force so that the dozer blade can be moved vertically along a rugged ground surface.
- the supply and discharge of the hydraulic fluid to and from the dozer cylinder 4 is not performed smoothly in the floating mode, thus leading to a decrease in the vertical movement speed of the dozer cylinder 4. That is, if the downward movement speed or the descending speed of the dozer blade is decreased, the dozer blade will ascend and will be kept for a long period of time in a state in which the dozer blade is spaced apart from the ground surface.
- the dozer blade in the process in which the dozer blade is moved upwardly or ascends in the floating mode, if a back pressure is formed in the flow path along which the hydraulic fluid discharged from the dozer cylinder 4 is returned, the dozer blade cannot ascend easily along the rugged ground surface.
- the hydraulic fluid discharged from the dozer cylinder 4 by the drive of the dozer cylinder 4 is returned to the hydraulic tank 7 via the control valve 5, the dozer spool 5a, and the return check valve 8 in this order.
- the ascending of the dozer blade is interfered by the back pressure formed in the flow path along which the hydraulic fluid discharged from the dozer cylinder 4 is returned.
- the conventional construction machine having a floating function entails a problem in that because the vertical movement speed of the dozer blade is relatively decreased as compared the traveling speed of the construction machine, the dozer blade does not ascend or descend smoothly along the rugged ground surface, resulting in a deterioration of workability in the ground leveling work.
- the present invention has been made to solve the aforementioned problems occurring in the prior art, and it is an object of the present invention to provide a construction machine having a floating function in which when a ground leveling work or a grading work is performed by a floating function of a dozer blade, the vertical movement speed of the dozer blade can be increased, thereby improving workability.
- a construction machine having a floating function including:
- a construction machine having a floating function including:
- a construction machine having a floating function including:
- a construction machine having a floating function including:
- the flow path for floating may be connected at the other end thereof to a large chamber of the dozer cylinder.
- the flow path for floating may be connected at the other end thereof to a small chamber of the dozer cylinder.
- the construction machine having a floating function in accordance with the present invention as constructed above has the following advantages.
- the hydraulic fluid is replenished to the dozer cylinder or the discharge of the hydraulic fluid from the dozer cylinder is promoted to increase the drive speed of the piston so that the dozer blade can be smoothly moved vertically along the rugged ground surface, thereby improving workability in the ground leveling work or the grading work.
- Fig. 2 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a first preferred embodiment of the present invention.
- the construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- the construction machine having a floating function in accordance with a first preferred embodiment of the present invention includes:
- the flow path 12 for floating may be connected at the other end thereof to a large chamber of the dozer cylinder 4.
- the flow path 12 for floating may be connected at the other end thereof to a small chamber of the dozer cylinder 4.
- a configuration of the construction machine having a floating function in accordance with a first preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the prior art shown in Fig. 1 , except the check valve 10 installed in the flow path 12 for floating.
- the check valve 10 installed in the flow path 12 for floating.
- a spool of the solenoid valve 9 for floating is shifted to the bottom on the drawing sheet in response to an electrical control signal applied to the solenoid valve 9 for floating.
- a pair of check valves within the dozer check valve 6 is converted to an open state by a pilot signal pressure discharged from the pilot pump 3 and applied to the dozer check valve 6 via the solenoid valve for floating 9.
- the conversion of the dozer check valve 6 releases a check function of restricting the supply of a hydraulic fluid to the dozer cylinder 4.
- a piston of the dozer cylinder 4 is driven by the dozer clylinder' s own weight or an external force so that the dozer blade can be moved vertically along a rugged ground surface.
- the vertical movement speed of the dozer blade can be increased in the floating mode of the dozer blade. That is, a dozer spool 5a of the control valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from the hydraulic tank 7 can be supplied to the large chamber of the dozer cylinder 4 via the check valve 10 installed in the flow path 12 for floating in a state in which the supply of the hydraulic fluid from the hydraulic pump 2 to the dozer cylinder 4 is interrupted. For this reason, the hydraulic fluid from the hydraulic tank 7 is replenished to the large chamber of the dozer cylinder 4 via the flow path 12 for floating upon the descending of the dozer blade, thus leading to an increase in the downward movement speed or the descending speed of the dozer blade.
- the hydraulic fluid from the hydraulic tank 7 is replenished to the large chamber of the dozer cylinder 4 through the check valve 10 installed in the flow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased.
- Fig. 3 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a second preferred embodiment of the present invention.
- the construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- the construction machine having a floating function in accordance with a second preferred embodiment of the present invention includes:
- the flow path 12 for floating may be connected at the other end thereof to a large chamber of the dozer cylinder 4.
- the flow path 12 for floating may be connected at the other end thereof to a small chamber of the dozer cylinder 4.
- a configuration of the construction machine having a floating function in accordance with a second preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the first embodiment of the present invention, except the pilot check valve 11 installed in the flow path 12 for floating and shifted to an open or closed state by the pilot signal pressure supplied to the dozer check valve 6.
- the pilot check valve 11 installed in the flow path 12 for floating and shifted to an open or closed state by the pilot signal pressure supplied to the dozer check valve 6.
- the dozer spool 5a of the control valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from the hydraulic tank 7 can be supplied to the large chamber of the dozer cylinder 4 via the pilot check valve 11 installed in the flow path 12 for floating in a state in which the supply of the hydraulic fluid from the hydraulic pump 2 to the dozer cylinder 4 is interrupted. For this reason, it is possible to increase the downward movement speed or the descending speed of the dozer blade that is moved along the rugged ground surface in the floating mode.
- the hydraulic fluid discharged from the dozer cylinder 4 by the drive of the piston of the dozer cylinder 4 can be promptly returned to the hydraulic tank 7.
- the pilot check valve 11 installed in the flow path 12 for floating is changed to an open state by the pilot signal pressure supplied to the dozer check valve 6 so that the hydraulic fluid discharged from the dozer cylinder 4 can be returned to the hydraulic tank 7 via the pilot check valve 11 upon the ascending of the dozer blade.
- the hydraulic fluid discharged from the dozer cylinder 4 can be directly returned to the hydraulic tank 7 via the pilot check valve 11 without passing through the control valve 5 upon the ascending of the dozer blade.
- the generation of the back pressure in the flow path can be minimized to increase the ascending speed of the dozer blade.
- the hydraulic fluid discharged from the dozer cylinder 4 is returned to the hydraulic tank 7 via the control valve 5, the dozer spool 5a, and return check valve 8 in this order.
- the back pressure is generated in the flow path, leading to a restriction of the ascending of the dozer blade.
- the hydraulic fluid from the hydraulic tank 7 is replenished to the large chamber of the dozer cylinder 4 through the pilot check valve 11 installed in the flow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased.
- the hydraulic fluid discharged from the dozer cylinder 4 is promptly returned to the hydraulic tank 7 via the pilot check valve 11 so that the generation of the back pressure in the flow path along which the hydraulic fluid discharged from the dozer cylinder 4 is returned can be minimized to increase the ascending speed of the dozer blade.
- Fig. 4 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a third preferred embodiment of the present invention.
- the construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- the construction machine having a floating function in accordance with a third preferred embodiment of the present invention includes:
- the flow path 12 for floating may be connected at the other end thereof to a large chamber of the dozer cylinder 4.
- a configuration of the construction machine having a floating function in accordance with a third preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the first embodiment of the present invention, except the 3-way valve installed at the crossing point of the flow path 12 for floating and the flow path on the control valve 5 side and configured to replenish the hydraulic fluid from the hydraulic tank 7 to the dozer cylinder 4 in the floating mode, and the flow path 12 for floating connected at the other end thereof to a large chamber of the dozer cylinder 4.
- the detailed description of the same configuration and operation thereof will be omitted to avoid redundancy, and the same hydraulic parts are denoted by the same reference numerals.
- the dozer spool 5a of the control valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from the hydraulic tank 7 can be replenished to the dozer cylinder 4 by the shift of the 3-way valve 14 in a state in which the supply of the hydraulic fluid from the hydraulic pump 2 to the dozer cylinder 4 is interrupted.
- a spool of the 3-way valve 14 is shifted to the bottom on the drawing sheet, i.e., is shifted to the first position (I).
- the hydraulic fluid from the hydraulic tank 7 can be supplied to a large chamber of the dozer cylinder 4 via the flow path 12 for floating and the 3-way valve 14.
- the hydraulic fluid from the hydraulic tank 7 can be replenished to the large chamber of the dozer cylinder 4 via the flow path 12 for floating and the 3-way valve 14 upon the descending of the dozer blade so that the downward movement speed or the descending speed of the dozer blade that is moved along a rugged ground surface can be increased.
- the supply of the pilot signal pressure to the dozer check valve 6 is interrupted and thus the supply of the pilot signal pressure to the 3-way valve 14 is also interrupted.
- the 3-way valve 14 returns to its initial position by a valve spring thereof, i.e., the spool of the 3-way valve 14 is shifted to the second position (II).
- the hydraulic fluid from the hydraulic tank 7 is replenished to the large chamber of the dozer cylinder 4 through the 3-way valve 13 via the flow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased.
- the dozer blade when the floating mode of the dozer blade is released, the dozer blade can be moved vertically by the hydraulic fluid supplied from the hydraulic pump 2 to the large chamber of the dozer cylinder 4 via the control valve 5 and the 3-way valve 14.
- Fig. 5 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a fourth preferred embodiment of the present invention.
- the construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- the construction machine having a floating function in accordance with a fourth preferred embodiment of the present invention includes:
- the flow path 12 for floating may be connected at the other end thereof to a large chamber of the dozer cylinder 4.
- the flow path 12 for floating may be connected at the other end thereof to a small chamber of the dozer cylinder 4.
- a configuration of the construction machine having a floating function in accordance with a fourth preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the third embodiment of the present invention, except the 3-way valve installed at a crossing point of the flow path 12 for floating and the flow path on the control valve 5 side and configured to be shifted to allow the dozer cylinder 4, the control valve 5, and the hydraulic tank 7 to fluidically communicate with one another in a floating mode and to supply the hydraulic fluid from the hydraulic pump 2 to the dozer cylinder 4 when the floating mode is released, and the flow path 12 for floating connected at the other end thereof to a large or small chamber of the dozer cylinder 4.
- the detailed description of the same configuration and operation thereof will be omitted to avoid redundancy, and the same hydraulic parts are denoted by the same reference numerals.
- the dozer spool 5a of the control valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from the hydraulic tank 7 can be replenished to the dozer cylinder 4 by the shift of the 3-way valve 15 in a state in which the supply of the hydraulic fluid from the hydraulic pump 2 to the large chamber of the dozer cylinder 4 is interrupted.
- a spool of the 3-way valve 15 is shifted to the bottom on the drawing sheet, i.e., is shifted to the first position (I).
- the hydraulic fluid from the hydraulic tank 7 can be supplied to the large chamber of the dozer cylinder 4 via the flow path 12 for floating and the 3-way valve 15.
- the hydraulic fluid from the hydraulic tank 7 can be replenished to the large chamber of the dozer cylinder 4 via the flow path 12 for floating and the 3-way valve 15 upon the descending of the dozer blade so that the downward movement speed or the descending speed of the dozer blade that is moved along a rugged ground surface can be increased.
- the hydraulic fluid discharged from the dozer cylinder 4 by the drive of the piston of the dozer cylinder 4 can be promptly returned to the hydraulic tank 7.
- a spool of the 3-way valve 15 is shifted to the first position (I) by the pilot signal pressure supplied to the dozer check valve 6 so that the hydraulic fluid discharged from the large chamber of the dozer cylinder 4 can be returned to the hydraulic tank 7 via the 3-way valve 15 upon the ascending of the dozer blade.
- the hydraulic fluid discharged from the dozer cylinder 4 can be directly returned to the hydraulic tank 7 via the 3-way valve 15 without passing through the control valve 5 upon the ascending of the dozer blade.
- the generation of the back pressure in the flow path can be minimized to increase the ascending speed of the dozer blade.
- the supply of the pilot signal pressure to the dozer check valve 6 is interrupted and thus the supply of the pilot signal pressure to the 3-way valve 15 is also interrupted.
- the 3-way valve 15 returns to its initial position by a valve spring thereof, i.e., the spool of the 3-way valve 15 is shifted to the second position (II)(see a state shown in Fig. 5 ).
- the hydraulic fluid from the hydraulic tank 7 is replenished to the large chamber of the dozer cylinder 4 through the 3-way valve 15 via the flow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased.
- the hydraulic fluid discharged from the dozer cylinder 4 can be promptly returned to the hydraulic tank 7 without passing through the control valve 5 so that the generation of the back pressure in the flow path along which the hydraulic fluid discharged from the dozer cylinder 4 is returned to the hydraulic tank can be minimized to increase the ascending speed of the dozer blade.
- the floating mode of the dozer blade is released, the dozer blade can be moved vertically by the hydraulic fluid supplied from the hydraulic pump 2 to the dozer cylinder 4 via the control valve 5 and the 3-way valve 15.
- the construction machine having a floating function in accordance with the present invention as constructed above has an effect in that when a ground leveling work or a grading work is performed by the floating function of the dozer blade, the vertical movement speed of the dozer blade can be increased, thereby improving workability.
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Abstract
Description
- The present invention relates to a construction machine having a floating function. More particularly, the present invention relates to such a construction machine having a floating function, which can perform a ground leveling work or a grading work in which the ground is flattened and leveled using a dozer blade.
- The floating function means a function in which a dozer blade is moved upwardly and downwardly along a rugged ground surface by its own weight or an external force even without a manipulation of a manipulation lever by an operator during the traveling of the construction machine. Even when the construction machine is simply manipulated to be traveled by the floating function, a ground leveling work or a grading work can be performed in which the ground is flattened and leveled by the dozer blade moved upwardly and downwardly.
- As shown in
Fig. 1 , a construction machine having a floating function in accordance with the prior art includes: - a
hydraulic pump 2 and apilot pump 3, which are connected to an engine 1; - a
dozer cylinder 4 connected to the hydraulic pump and configured to move a dozer blade (not shown) upwardly and downwardly; - a control valve (MCV) 5 installed in a flow path between the
hydraulic pump 2 and thedozer cylinder 4 and configured to be shifted to control a start, a stop, and a direction change of thedozer cylinder 4; - a
dozer check valve 6 installed in a flow path between thecontrol valve 5 and thedozer cylinder 4; - a
return check valve 8 installed in a flow path between thecontrol valve 5 and ahydraulic tank 7; and - a
solenoid valve 9 for floating openably/closably installed in asignal path 13 between thepilot pump 3 and thedozer check valve 6 and configured to be shifted to an open state to supply a pilot signal pressure from thepilot pump 3 to thedozer check valve 6 to release a check function of thedozer check valve 6. - Thus, a hydraulic fluid discharged from the
hydraulic pump 2 is adjusted in flow rate by adozer spool 5a of thecontrol valve 5, and then is supplied to thedozer check valve 6. The hydraulic fluid supplied to thedozer check valve 6 converts the state of a pair of check valves of thedozer check valve 6 into an open state, and is introduced into a large chamber or a small chamber of thedozer cylinder 4. The introduced hydraulic fluid drives a piston of thedozer cylinder 4 so that the dozer blade (not shown) can be moved vertically. - A hydraulic fluid discharged from the
dozer cylinder 4 by the drive of the piston of thedozer cylinder 4 passes through thedozer check valve 6, thedozer spool 5a, and thecontrol valve 5 in this order and is returned to ahydraulic tank 7 via thereturn check valve 8. - Meanwhile, when an operation mode of the dozer blade is converted from a normal mode to a floating mode, a spool of the
solenoid valve 9 for floating is shifted to the bottom on the drawing sheet in response to an electrical control signal applied to thesolenoid valve 9 for floating. Thus, a pair of check valves within thedozer check valve 6 is converted to an open state by a pilot signal pressure discharged from thepilot pump 3 and applied to thedozer check valve 6 via the solenoid valve for floating 9. In other words, the conversion of thedozer check valve 6 releases a check function of restricting the returning of a hydraulic fluid to thedozer cylinder 4. - Resultantly, a piston of the
dozer cylinder 4 is driven by the dozer clylinder' s own weight or an external force so that the dozer blade can be moved vertically along a rugged ground surface. - As shown in
Fig. 1 , in case of the construction machine having a floating function in accordance with the prior art, in the case where the operation mode of the dozer blade is converted from the normal mode to the floating mode to perform the ground leveling work on a work surface, when thedozer spool 5a of thecontrol valve 5 is maintained in a neutral state, thedozer cylinder 4 is not supplied with the hydraulic fluid from thehydraulic pump 2. In other words, in the case where the operation mode of the dozer blade is converted from the normal mode to the floating mode, thedozer cylinder 4 is driven by only the dozer blade's own weight or an external force. - Thus, the supply and discharge of the hydraulic fluid to and from the
dozer cylinder 4 is not performed smoothly in the floating mode, thus leading to a decrease in the vertical movement speed of thedozer cylinder 4. That is, if the downward movement speed or the descending speed of the dozer blade is decreased, the dozer blade will ascend and will be kept for a long period of time in a state in which the dozer blade is spaced apart from the ground surface. - In addition, in the process in which the dozer blade is moved upwardly or ascends in the floating mode, if a back pressure is formed in the flow path along which the hydraulic fluid discharged from the
dozer cylinder 4 is returned, the dozer blade cannot ascend easily along the rugged ground surface. In other words, the hydraulic fluid discharged from thedozer cylinder 4 by the drive of thedozer cylinder 4 is returned to thehydraulic tank 7 via thecontrol valve 5, thedozer spool 5a, and thereturn check valve 8 in this order. Thus, the ascending of the dozer blade is interfered by the back pressure formed in the flow path along which the hydraulic fluid discharged from thedozer cylinder 4 is returned. - For this reason, the conventional construction machine having a floating function entails a problem in that because the vertical movement speed of the dozer blade is relatively decreased as compared the traveling speed of the construction machine, the dozer blade does not ascend or descend smoothly along the rugged ground surface, resulting in a deterioration of workability in the ground leveling work.
- Accordingly, the present invention has been made to solve the aforementioned problems occurring in the prior art, and it is an object of the present invention to provide a construction machine having a floating function in which when a ground leveling work or a grading work is performed by a floating function of a dozer blade, the vertical movement speed of the dozer blade can be increased, thereby improving workability.
- To achieve the above object, in accordance with a first embodiment of the present invention, there is provided a construction machine having a floating function, including:
- 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.
- In accordance with a second embodiment of the present invention, there is provided a construction machine having a floating function, including:
- 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.
- In accordance with a third embodiment of the present invention, there is provided a construction machine having a floating function, including:
- 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 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, 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.
- In accordance with a fourth embodiment of the present invention, there is provided a construction machine having a floating function, including:
- 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.
- The flow path for floating may be connected at the other end thereof to a large chamber of the dozer cylinder.
- The flow path for floating may be connected at the other end thereof to a small chamber of the dozer cylinder.
- The construction machine having a floating function in accordance with the present invention as constructed above has the following advantages.
- In the floating mode of the dozer blade, the hydraulic fluid is replenished to the dozer cylinder or the discharge of the hydraulic fluid from the dozer cylinder is promoted to increase the drive speed of the piston so that the dozer blade can be smoothly moved vertically along the rugged ground surface, thereby improving workability in the ground leveling work or the grading work.
- The above objects, other features and advantages of the present invention will become more apparent by describing the preferred embodiments thereof with reference to the accompanying drawings, in which:
-
Fig. 1 is a hydraulic circuit diagram of a construction machine in accordance with the prior art; -
Fig. 2 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a first preferred embodiment of the present invention; -
Fig. 3 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a second preferred embodiment of the present invention; -
Fig. 4 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a third preferred embodiment of the present invention; andFig. 5 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a fourth preferred embodiment of the present invention. -
- 110: vehicle information collection unit
- 1: engine
- 2: hydraulic pump
- 3: pilot pump
- 4: dozer cylinder
- 5: control valve
- 6: dozer check valve
- 7: hydraulic tank
- 8: return check valve
- 9: solenoid valve for floating
- 10: check valve
- 11: pilot check valve
- 12: flow path for floating
- 13: signal path
- 14, 15: 3-way valve
- Now, a construction machine having a floating function in accordance with preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is not limited to the embodiments disclosed hereinafter.
-
Fig. 2 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a first preferred embodiment of the present invention. - The construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- Referring to
Fig. 2 , the construction machine having a floating function in accordance with a first preferred embodiment of the present invention includes: - a
hydraulic pump 2 and apilot pump 3, which are connected to an engine 1; - a
dozer cylinder 4 connected to the hydraulic pump and configured to move a dozer blade (not shown) upwardly and downwardly; - a
control valve 5 installed in a flow path between thehydraulic pump 2 and thedozer cylinder 4 and configured to be shifted to control a start, a stop, and a direction change of thedozer cylinder 4; - a
dozer check valve 6 installed in a flow path between thecontrol valve 5 and thedozer cylinder 4; - a
return check valve 8 installed in a flow path between thecontrol valve 5 and ahydraulic tank 7; - a
solenoid valve 9 for floating openably/closably installed in asignal path 13 between thepilot pump 3 and thedozer check valve 6 and configured to be shifted to an open state to supply a pilot signal pressure from thepilot pump 3 to thedozer check valve 6 to release a check function of thedozer check valve 6; - a
flow path 12 for floating connected at one end thereof to thehydraulic tank 7 and connected at the other end thereof to a flow path for connecting thecontrol valve 5 to thedozer cylinder 4; and - a
check valve 10 installed in theflow path 12 for floating, the check valve being configured to allow a hydraulic fluid to be supplied from thehydraulic tank 7 to thedozer cylinder 4 through theflow path 12 for floating in a floating mode and to block the flow path for floating when the floating mode is released. - The
flow path 12 for floating may be connected at the other end thereof to a large chamber of thedozer cylinder 4. - Although not shown in the drawings, the
flow path 12 for floating may be connected at the other end thereof to a small chamber of thedozer cylinder 4. - In this case, a configuration of the construction machine having a floating function in accordance with a first preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the prior art shown in
Fig. 1 , except thecheck valve 10 installed in theflow path 12 for floating. Thus, the detailed description of the same configuration and operation thereof will be omitted to avoid redundancy, and the same hydraulic parts are denoted by the same reference numerals. - According to the above-described configuration, when an operation mode of the dozer blade is converted from the normal mode to the floating mode, a spool of the
solenoid valve 9 for floating is shifted to the bottom on the drawing sheet in response to an electrical control signal applied to thesolenoid valve 9 for floating. Thus, a pair of check valves within thedozer check valve 6 is converted to an open state by a pilot signal pressure discharged from thepilot pump 3 and applied to thedozer check valve 6 via the solenoid valve for floating 9. In other words, the conversion of thedozer check valve 6 releases a check function of restricting the supply of a hydraulic fluid to thedozer cylinder 4. Resultantly, a piston of thedozer cylinder 4 is driven by the dozer clylinder' s own weight or an external force so that the dozer blade can be moved vertically along a rugged ground surface. - Meanwhile, the vertical movement speed of the dozer blade can be increased in the floating mode of the dozer blade. That is, a
dozer spool 5a of thecontrol valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from thehydraulic tank 7 can be supplied to the large chamber of thedozer cylinder 4 via thecheck valve 10 installed in theflow path 12 for floating in a state in which the supply of the hydraulic fluid from thehydraulic pump 2 to thedozer cylinder 4 is interrupted. For this reason, the hydraulic fluid from thehydraulic tank 7 is replenished to the large chamber of thedozer cylinder 4 via theflow path 12 for floating upon the descending of the dozer blade, thus leading to an increase in the downward movement speed or the descending speed of the dozer blade. - On the other hand, when the floating mode of the dozer blade is released, the returning of the hydraulic fluid discharged from the
dozer cylinder 4 to thehydraulic tank 7 can be interrupted by the check function of thecheck valve 10 installed in theflow path 12 for floating. - As described above, in case of the construction machine having a floating function in accordance with the first embodiment of the present invention, when the dozer blade is moved downwardly or descends in the floating mode, the hydraulic fluid from the
hydraulic tank 7 is replenished to the large chamber of thedozer cylinder 4 through thecheck valve 10 installed in theflow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased. -
Fig. 3 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a second preferred embodiment of the present invention. - The construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- Referring to
Fig. 3 , the construction machine having a floating function in accordance with a second preferred embodiment of the present invention includes: - a
hydraulic pump 2 and apilot pump 3, which are connected to an engine 1; - a
dozer cylinder 4 connected to the hydraulic pump and configured to move a dozer blade (not shown) upwardly and downwardly; - a
control valve 5 installed in a flow path between thehydraulic pump 2 and thedozer cylinder 4 and configured to be shifted to control a start, a stop, and a direction change of thedozer cylinder 4; - a
dozer check valve 6 installed in a flow path between thecontrol valve 5 and thedozer cylinder 4; - a
return check valve 8 installed in a flow path between thecontrol valve 5 and ahydraulic tank 7; - a
solenoid valve 9 for floating openably/closably installed in asignal path 13 between thepilot pump 3 and thedozer check valve 6 and configured to be shifted to an open state to supply a pilot signal pressure from thepilot pump 3 to thedozer check valve 6 to release a check function of thedozer check valve 6; - a
flow path 12 for floating connected at one end thereof to thehydraulic tank 7 and connected at the other end thereof to a flow path for connecting thecontrol valve 5 to thedozer cylinder 4; and - a
pilot check valve 11 installed in theflow path 12 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 thedozer check valve 6 to supply a hydraulic fluid from thehydraulic tank 7 to thedozer cylinder 4 through theflow path 12 for floating or to allow the hydraulic fluid discharged from thedozer cylinder 4 to be returned to thehydraulic tank 7 through theflow path 12 for floating in a floating mode, and shifted to a closed state by interruption of the supply of the pilot signal pressure to thedozer check valve 6 to block theflow path 12 for floating when the floating mode is released. - The
flow path 12 for floating may be connected at the other end thereof to a large chamber of thedozer cylinder 4. - Although not shown in the drawings, the
flow path 12 for floating may be connected at the other end thereof to a small chamber of thedozer cylinder 4. - In this case, a configuration of the construction machine having a floating function in accordance with a second preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the first embodiment of the present invention, except the
pilot check valve 11 installed in theflow path 12 for floating and shifted to an open or closed state by the pilot signal pressure supplied to thedozer check valve 6. Thus, the detailed description of the same configuration and operation thereof will be omitted to avoid redundancy, and the same hydraulic parts are denoted by the same reference numerals. - According to the above-described configuration, when an operation mode of the dozer blade is converted from the normal mode to the floating mode, the
dozer spool 5a of thecontrol valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from thehydraulic tank 7 can be supplied to the large chamber of thedozer cylinder 4 via thepilot check valve 11 installed in theflow path 12 for floating in a state in which the supply of the hydraulic fluid from thehydraulic pump 2 to thedozer cylinder 4 is interrupted. For this reason, it is possible to increase the downward movement speed or the descending speed of the dozer blade that is moved along the rugged ground surface in the floating mode. - Meanwhile, when the dozer blade ascends in the floating mode, the hydraulic fluid discharged from the
dozer cylinder 4 by the drive of the piston of thedozer cylinder 4 can be promptly returned to thehydraulic tank 7. In other words, thepilot check valve 11 installed in theflow path 12 for floating is changed to an open state by the pilot signal pressure supplied to thedozer check valve 6 so that the hydraulic fluid discharged from thedozer cylinder 4 can be returned to thehydraulic tank 7 via thepilot check valve 11 upon the ascending of the dozer blade. - As such, the hydraulic fluid discharged from the
dozer cylinder 4 can be directly returned to thehydraulic tank 7 via thepilot check valve 11 without passing through thecontrol valve 5 upon the ascending of the dozer blade. - Thus, in the process in which the hydraulic fluid discharged from the
dozer cylinder 4 is returned to thehydraulic tank 7, the generation of the back pressure in the flow path can be minimized to increase the ascending speed of the dozer blade. On the other hand, conventionally, the hydraulic fluid discharged from thedozer cylinder 4 is returned to thehydraulic tank 7 via thecontrol valve 5, thedozer spool 5a, and returncheck valve 8 in this order. As a result, in the process in which the hydraulic fluid discharged from thedozer cylinder 4 is returned to thehydraulic tank 7, the back pressure is generated in the flow path, leading to a restriction of the ascending of the dozer blade. - As described above, in case of the construction machine having a floating function in accordance with the second embodiment of the present invention, when the dozer blade is moved downwardly or descends in the floating mode, the hydraulic fluid from the
hydraulic tank 7 is replenished to the large chamber of thedozer cylinder 4 through thepilot check valve 11 installed in theflow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased. In addition, when the dozer blade is moved upwardly or ascends in the floating mode, the hydraulic fluid discharged from thedozer cylinder 4 is promptly returned to thehydraulic tank 7 via thepilot check valve 11 so that the generation of the back pressure in the flow path along which the hydraulic fluid discharged from thedozer cylinder 4 is returned can be minimized to increase the ascending speed of the dozer blade. -
Fig. 4 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a third preferred embodiment of the present invention. - The construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- Referring to
Fig. 4 , the construction machine having a floating function in accordance with a third preferred embodiment of the present invention includes: - a
hydraulic pump 2 and apilot pump 3, which are connected to an engine 1; - a
dozer cylinder 4 connected to the hydraulic pump and configured to move a dozer blade (not shown) upwardly and downwardly; - a
control valve 5 installed in a flow path between thehydraulic pump 2 and thedozer cylinder 4 and configured to be shifted to control a start, a stop, and a direction change of thedozer cylinder 4; - a
dozer check valve 6 installed in a flow path between thecontrol valve 5 and thedozer cylinder 4; - a
return check valve 8 installed in a flow path between thecontrol valve 5 and ahydraulic tank 7; - a
solenoid valve 9 for floating openably/closably installed in asignal path 13 between thepilot pump 3 and thedozer check valve 6 and configured to be shifted to an open state to supply a pilot signal pressure from thepilot pump 3 to thedozer check valve 6 to release a check function of thedozer check valve 6; - a
flow path 12 for floating connected at one end thereof to thehydraulic tank 7 and connected at the other end thereof to a flow path for connecting thecontrol valve 5 to thedozer cylinder 4; and - a 3-way valve installed at a crossing point of the
flow path 12 for floating and the flow path on thecontrol valve 5 side, the 3-way valve being configured to be shifted to a first position (I) by a pilot signal pressure supplied to thedozer check valve 6 to replenish a hydraulic fluid from thehydraulic tank 7 to thedozer cylinder 4 through theflow path 12 for floating in a floating mode and shifted to a second position (II), in which the supply of the pilot signal pressure to thedozer check valve 6 is interrupted to connect the flow path between thecontrol valve 5 and thedozer cylinder 4 when the floating mode is released. - The
flow path 12 for floating may be connected at the other end thereof to a large chamber of thedozer cylinder 4. - In this case, a configuration of the construction machine having a floating function in accordance with a third preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the first embodiment of the present invention, except the 3-way valve installed at the crossing point of the
flow path 12 for floating and the flow path on thecontrol valve 5 side and configured to replenish the hydraulic fluid from thehydraulic tank 7 to thedozer cylinder 4 in the floating mode, and theflow path 12 for floating connected at the other end thereof to a large chamber of thedozer cylinder 4. Thus, the detailed description of the same configuration and operation thereof will be omitted to avoid redundancy, and the same hydraulic parts are denoted by the same reference numerals. - According to the above-described configuration, when an operation mode of the dozer blade is converted from the normal mode to the floating mode, the
dozer spool 5a of thecontrol valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from thehydraulic tank 7 can be replenished to thedozer cylinder 4 by the shift of the 3-way valve 14 in a state in which the supply of the hydraulic fluid from thehydraulic pump 2 to thedozer cylinder 4 is interrupted. - In other words, a spool of the 3-
way valve 14 is shifted to the bottom on the drawing sheet, i.e., is shifted to the first position (I). The hydraulic fluid from thehydraulic tank 7 can be supplied to a large chamber of thedozer cylinder 4 via theflow path 12 for floating and the 3-way valve 14. As a result, the hydraulic fluid from thehydraulic tank 7 can be replenished to the large chamber of thedozer cylinder 4 via theflow path 12 for floating and the 3-way valve 14 upon the descending of the dozer blade so that the downward movement speed or the descending speed of the dozer blade that is moved along a rugged ground surface can be increased. - Meanwhile, when the floating mode of the dozer blade is released, the supply of the pilot signal pressure to the
dozer check valve 6 is interrupted and thus the supply of the pilot signal pressure to the 3-way valve 14 is also interrupted. As a result, the 3-way valve 14 returns to its initial position by a valve spring thereof, i.e., the spool of the 3-way valve 14 is shifted to the second position (II). - For this reason, because the
flow path 12 for floating is blocked, the returning of the hydraulic fluid discharged from thedozer cylinder 4 to thehydraulic tank 7 is interrupted. In the meantime, the flow paths between thedozer cylinder 4 and thecontrol valve 5 fluidically communicate with each other so that the dozer blade can be moved vertically by the hydraulic fluid discharged from thehydraulic pump 2 and supplied to thedozer cylinder 4. - As described above, in case of the construction machine having a floating function in accordance with the third embodiment of the present invention, when the dozer blade is moved downwardly or descends in the floating mode, the hydraulic fluid from the
hydraulic tank 7 is replenished to the large chamber of thedozer cylinder 4 through the 3-way valve 13 via theflow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased. - On the other hand, when the floating mode of the dozer blade is released, the dozer blade can be moved vertically by the hydraulic fluid supplied from the
hydraulic pump 2 to the large chamber of thedozer cylinder 4 via thecontrol valve 5 and the 3-way valve 14. -
Fig. 5 is a hydraulic circuit diagram of a construction machine having a floating function in accordance with a fourth preferred embodiment of the present invention. - The construction machine having a floating function includes a normal mode in which a dozer blade is moved vertically by the manipulation of a manipulation lever and a floating mode in which the dozer blade is moved vertically along a rugged ground surface by its own weight or an external force during the traveling of the construction machine.
- Referring to
Fig. 5 , the construction machine having a floating function in accordance with a fourth preferred embodiment of the present invention includes: - a
hydraulic pump 2 and apilot pump 3, which are connected to an engine 1; - a
dozer cylinder 4 connected to the hydraulic pump and configured to move a dozer blade (not shown) upwardly and downwardly; - a
control valve 5 installed in a flow path between thehydraulic pump 2 and thedozer cylinder 4 and configured to be shifted to control a start, a stop, and a direction change of thedozer cylinder 4; - a
dozer check valve 6 installed in a flow path between thecontrol valve 5 and thedozer cylinder 4; - a
return check valve 8 installed in a flow path between thecontrol valve 5 and ahydraulic tank 7; - a
solenoid valve 9 for floating openably/closably installed in asignal path 13 between thepilot pump 3 and thedozer check valve 6 and configured to be shifted to an open state to supply a pilot signal pressure from thepilot pump 3 to thedozer check valve 6 to release a check function of thedozer check valve 6; - a
flow path 12 for floating connected at one end thereof to thehydraulic tank 7 and connected at the other end thereof to a flow path for connecting thecontrol valve 5 to thedozer cylinder 4; and - a 3-
way valve 15 installed at a crossing point of theflow path 12 for floating and the flow path on thecontrol valve 5 side, the 3-way valve being configured to be shifted to a first position (I) by a pilot signal pressure supplied to thedozer check valve 6 to allow thedozer cylinder 4, thecontrol valve 5, and thehydraulic tank 7 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 thedozer check valve 6 is interrupted to connect the flow path between thecontrol valve 5 and thedozer cylinder 4 when the floating mode is released. - The
flow path 12 for floating may be connected at the other end thereof to a large chamber of thedozer cylinder 4. - Although not shown in the drawings, the
flow path 12 for floating may be connected at the other end thereof to a small chamber of thedozer cylinder 4. - In this case, a configuration of the construction machine having a floating function in accordance with a fourth preferred embodiment of the present invention is the same as that of the construction machine having a floating function in accordance with the third embodiment of the present invention, except the 3-way valve installed at a crossing point of the
flow path 12 for floating and the flow path on thecontrol valve 5 side and configured to be shifted to allow thedozer cylinder 4, thecontrol valve 5, and thehydraulic tank 7 to fluidically communicate with one another in a floating mode and to supply the hydraulic fluid from thehydraulic pump 2 to thedozer cylinder 4 when the floating mode is released, and theflow path 12 for floating connected at the other end thereof to a large or small chamber of thedozer cylinder 4. Thus, the detailed description of the same configuration and operation thereof will be omitted to avoid redundancy, and the same hydraulic parts are denoted by the same reference numerals. - According to the above-described configuration, when an operation mode of the dozer blade is converted from the normal mode to the floating mode, the
dozer spool 5a of thecontrol valve 5 is maintained in a neutral state in the floating mode so that the hydraulic fluid from thehydraulic tank 7 can be replenished to thedozer cylinder 4 by the shift of the 3-way valve 15 in a state in which the supply of the hydraulic fluid from thehydraulic pump 2 to the large chamber of thedozer cylinder 4 is interrupted. - In other words, a spool of the 3-
way valve 15 is shifted to the bottom on the drawing sheet, i.e., is shifted to the first position (I). Thus, the hydraulic fluid from thehydraulic tank 7 can be supplied to the large chamber of thedozer cylinder 4 via theflow path 12 for floating and the 3-way valve 15. As a result, the hydraulic fluid from thehydraulic tank 7 can be replenished to the large chamber of thedozer cylinder 4 via theflow path 12 for floating and the 3-way valve 15 upon the descending of the dozer blade so that the downward movement speed or the descending speed of the dozer blade that is moved along a rugged ground surface can be increased. - Meanwhile, when the dozer blade ascends in the floating mode, the hydraulic fluid discharged from the
dozer cylinder 4 by the drive of the piston of thedozer cylinder 4 can be promptly returned to thehydraulic tank 7. In other words, a spool of the 3-way valve 15 is shifted to the first position (I) by the pilot signal pressure supplied to thedozer check valve 6 so that the hydraulic fluid discharged from the large chamber of thedozer cylinder 4 can be returned to thehydraulic tank 7 via the 3-way valve 15 upon the ascending of the dozer blade. As such, the hydraulic fluid discharged from thedozer cylinder 4 can be directly returned to thehydraulic tank 7 via the 3-way valve 15 without passing through thecontrol valve 5 upon the ascending of the dozer blade. Thus, in the process in which the hydraulic fluid discharged from thedozer cylinder 4 is returned to thehydraulic tank 7, the generation of the back pressure in the flow path can be minimized to increase the ascending speed of the dozer blade. - Meanwhile, when the floating mode of the dozer blade is released, the supply of the pilot signal pressure to the
dozer check valve 6 is interrupted and thus the supply of the pilot signal pressure to the 3-way valve 15 is also interrupted. As a result, the 3-way valve 15 returns to its initial position by a valve spring thereof, i.e., the spool of the 3-way valve 15 is shifted to the second position (II)(see a state shown inFig. 5 ). - For this reason, because the
flow path 12 for floating is blocked, the returning of the hydraulic fluid discharged from thedozer cylinder 4 to thehydraulic tank 7 is interrupted. In the meantime, the flow paths between thedozer cylinder 4 and thecontrol valve 5 fluidically communicate with each other so that the dozer blade can be moved vertically by the hydraulic fluid discharged from thehydraulic pump 2 and supplied to thedozer cylinder 4. - As described above, in case of the construction machine having a floating function in accordance with the fourth embodiment of the present invention, when the dozer blade is moved downwardly or descends in the floating mode, the hydraulic fluid from the
hydraulic tank 7 is replenished to the large chamber of thedozer cylinder 4 through the 3-way valve 15 via theflow path 12 for floating so that the downward movement speed or the descending speed of the dozer blade can be increased. When the dozer blade ascends in the floating mode, the hydraulic fluid discharged from thedozer cylinder 4 can be promptly returned to thehydraulic tank 7 without passing through thecontrol valve 5 so that the generation of the back pressure in the flow path along which the hydraulic fluid discharged from thedozer cylinder 4 is returned to the hydraulic tank can be minimized to increase the ascending speed of the dozer blade. On the other hand, when the floating mode of the dozer blade is released, the dozer blade can be moved vertically by the hydraulic fluid supplied from thehydraulic pump 2 to thedozer cylinder 4 via thecontrol valve 5 and the 3-way valve 15. - The construction machine having a floating function in accordance with the present invention as constructed above has an effect in that when a ground leveling work or a grading work is performed by the floating function of the dozer blade, the vertical movement speed of the dozer blade can be increased, thereby improving workability.
- While the present invention has been described in connection with the specific embodiments illustrated in the drawings, they are merely illustrative, and the invention is not limited to these embodiments. It is to be understood that various equivalent modifications and variations of the embodiments can be made by a person having an ordinary skill in the art without departing from the spirit and scope of the present invention. Therefore, the true technical scope of the present invention should not be defined by the above-mentioned embodiments but should be defined by the appended claims and equivalents thereof.
Claims (11)
- 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; anda 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.
- 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.
- 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.
- 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; anda 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.
- 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.
- 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.
- 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.
- 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.
- 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; anda 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.
- 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.
- 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.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/KR2012/011178 WO2014098284A1 (en) | 2012-12-20 | 2012-12-20 | Construction machine with floating function |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2937472A1 true EP2937472A1 (en) | 2015-10-28 |
EP2937472A4 EP2937472A4 (en) | 2016-09-07 |
Family
ID=50978579
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP12890478.6A Withdrawn EP2937472A4 (en) | 2012-12-20 | 2012-12-20 | Construction machine with floating function |
Country Status (5)
Country | Link |
---|---|
US (1) | US20150315768A1 (en) |
EP (1) | EP2937472A4 (en) |
KR (1) | KR101741702B1 (en) |
AU (1) | AU2012397386B2 (en) |
WO (1) | WO2014098284A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9725882B2 (en) * | 2013-01-24 | 2017-08-08 | Volvo Construction Equipment Ab | Device and method for controlling flow rate in construction machinery |
CN107683359B (en) | 2015-06-02 | 2020-01-21 | 斗山英维高株式会社 | Hydraulic system for construction machine |
US10641388B2 (en) * | 2015-12-07 | 2020-05-05 | Kubota Corporation | Hydraulic system of work machine and work machine |
KR102491222B1 (en) * | 2015-12-11 | 2023-01-25 | 주식회사 대동 | Hydraulic circuit for working machine lifting and floating |
CN110158682B (en) * | 2019-05-06 | 2021-07-02 | 广西柳工机械股份有限公司 | Hydraulic system of land leveler working device |
CN113323071B (en) * | 2021-05-14 | 2023-02-24 | 安徽铜冠机械股份有限公司 | Floating control unit of underground carry scraper bucket |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4166506A (en) * | 1975-06-30 | 1979-09-04 | Kabushiki Kaisha Komatsu Seisakusho | Controlling apparatus for bulldozer blade |
US4282798A (en) * | 1979-10-22 | 1981-08-11 | Ex-Cell-O Corporation | Control valve unit for hydraulic linear actuator |
US4359931A (en) * | 1981-01-19 | 1982-11-23 | The Warner & Swasey Company | Regenerative and anticavitation hydraulic system for an excavator |
JP3478931B2 (en) * | 1996-09-20 | 2003-12-15 | 新キャタピラー三菱株式会社 | Hydraulic circuit |
US6092454A (en) * | 1998-07-23 | 2000-07-25 | Caterpillar Inc. | Controlled float circuit for an actuator |
JP2002088796A (en) * | 2000-09-19 | 2002-03-27 | Kobelco Contstruction Machinery Ltd | Dozer device |
US6892535B2 (en) * | 2002-06-14 | 2005-05-17 | Volvo Construction Equipment Holding Sweden Ab | Hydraulic circuit for boom cylinder combination having float function |
DE10307346A1 (en) * | 2003-02-21 | 2004-09-02 | Deere & Company, Moline | valve assembly |
CN101220823A (en) * | 2006-11-14 | 2008-07-16 | 胡斯可国际股份有限公司 | Energy recovery and reuse methods for a hydraulic system |
KR100849500B1 (en) * | 2006-11-29 | 2008-07-31 | 볼보 컨스트럭션 이키프먼트 홀딩 스웨덴 에이비 | double check valve with floating function |
KR101500744B1 (en) * | 2008-11-19 | 2015-03-09 | 두산인프라코어 주식회사 | Boom cylinder control circuit for construction machinery |
-
2012
- 2012-12-20 US US14/652,012 patent/US20150315768A1/en not_active Abandoned
- 2012-12-20 WO PCT/KR2012/011178 patent/WO2014098284A1/en active Application Filing
- 2012-12-20 EP EP12890478.6A patent/EP2937472A4/en not_active Withdrawn
- 2012-12-20 AU AU2012397386A patent/AU2012397386B2/en not_active Ceased
- 2012-12-20 KR KR1020157015833A patent/KR101741702B1/en active IP Right Grant
Also Published As
Publication number | Publication date |
---|---|
KR101741702B1 (en) | 2017-05-30 |
WO2014098284A1 (en) | 2014-06-26 |
AU2012397386A1 (en) | 2015-07-09 |
US20150315768A1 (en) | 2015-11-05 |
AU2012397386B2 (en) | 2016-05-19 |
EP2937472A4 (en) | 2016-09-07 |
KR20150092168A (en) | 2015-08-12 |
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