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US20080121101A1 - Double check valve having floating function - Google Patents

Double check valve having floating function Download PDF

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Publication number
US20080121101A1
US20080121101A1 US11/825,637 US82563707A US2008121101A1 US 20080121101 A1 US20080121101 A1 US 20080121101A1 US 82563707 A US82563707 A US 82563707A US 2008121101 A1 US2008121101 A1 US 2008121101A1
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US
United States
Prior art keywords
check valve
hydraulic cylinder
flow paths
double check
control valve
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.)
Abandoned
Application number
US11/825,637
Other languages
English (en)
Inventor
Sung Bok Park
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Volvo Construction Equipment AB
Original Assignee
Volvo Construction Equipment AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Volvo Construction Equipment AB filed Critical Volvo Construction Equipment AB
Assigned to VOLVO CONSTRUCTION EQUIPMENT HOLDING SWEDEN AB reassignment VOLVO CONSTRUCTION EQUIPMENT HOLDING SWEDEN AB ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: PARK, SUNG BOK
Publication of US20080121101A1 publication Critical patent/US20080121101A1/en
Abandoned legal-status Critical Current

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Classifications

    • 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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/024—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits
    • 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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/01—Locking-valves or other detent i.e. load-holding devices
    • 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
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • 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
    • 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
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • 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
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
    • 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
    • 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
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
    • 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
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/35—Directional control combined with flow control

Definitions

  • the present invention relates to a double check valve having a floating function, whereby a working device (e.g., a dozer blade) that is used for a land readjustment work on a work surface can perform a floating function.
  • a working device e.g., a dozer blade
  • floating function means that a working device in a non-load state (that a large chamber and a small chamber of a hydraulic cylinder for operating the working device (e.g., a dozer blade) are connected to each other) is operated depending on the ruggedness of a work surface or road surface in a state that the supply of hydraulic fluid from a hydraulic pump to the hydraulic cylinder is temporarily intercepted.
  • a large chamber d 1 and a small chamber d 2 of a hydraulic cylinder d are connected to each other through a pipe h. Accordingly, when the equipment having a working device f mounted thereon travels along the rugged ground and is on a downhill road, the working device f descends due to its own weight, and thus the hydraulic cylinder d is driven to be extended. By contrast, when the equipment is on an uphill road, the hydraulic cylinder d is driven to be contracted.
  • the construction equipment having a conventional double check valve includes a hydraulic pump P; a hydraulic cylinder d connected to the hydraulic pump P to operate a dozer blade f; a control valve a installed in flow paths between the hydraulic pump P and the hydraulic cylinder d and shifted to control a start, a stop, and a direction change of the hydraulic cylinder d; and a double check valve k installed to open/close flow paths between the control valve a and the hydraulic cylinder d, and having a pair of check valves b and c supported by pressing members f 1 and f 2 that are elastically supported by first and second elastic members (e.g., compression coil springs) e 1 and e 2 , respectively, and a plunger h slidably installed between the check valves b and c to prevent the dozer blade f from sinking.
  • first and second elastic members e.g., compression coil springs
  • the double check valve k serves as a check valve through the check valves b and c elastically supported by the first and second elastic members e 1 and e 2 and the pressing members f 1 and f 2 .
  • the check valve b blocks first flow paths s 1 and s 3 that connect the control valve a to the small chamber d 2 of the hydraulic cylinder d
  • the check valve c blocks second flow paths S 2 and s 4 that connect the control valve a to the large chamber d 1 of the hydraulic cylinder d.
  • the hydraulic fluid bed from the hydraulic pump P is not supplied to the hydraulic cylinder d. Also, the hydraulic fluid fed from the hydraulic cylinder d is not returned to the hydraulic tank.
  • the dozer blade f is prevented from sinking.
  • the hydraulic fluid in the first flow path s 1 acts upon a diaphragm n 1 to shift the plunger h in the left direction, and presses the check valve b in the right direction as shown in the drawing to remove the check function (at this time, the first elastic member e 1 receives the compression force). That is, the first flow paths s 1 and s 3 of the check valve k are connected to each other.
  • the plunger h is shifted to press the check valve c in the left direction as shown in the drawing to remove the check function (at this time, the second elastic member e 2 receives the compression force). That is, the second flow paths S 2 and S 4 of the check valve k are connected to each other.
  • the hydraulic fluid fed from the hydraulic pump P is supplied to the small chamber d 2 of the hydraulic cylinder d after passing through the control valve a and the first flow paths s 1 and s 3 of the check valve k in order.
  • the hydraulic fluid fed from the large chamber d 1 of the hydraulic cylinder d is returned to the hydraulic tank after passing through the check valve c of which the check function has been removed, the second flow paths S 2 and S 4 , and the control valve a in order.
  • the hydraulic cylinder d is driven to be contracted by the hydraulic fluid from the hydraulic pump P.
  • the hydraulic fluid in the second flow path s 2 acts upon a diaphragm n 2 to shift the plunger h in the right direction, and presses the check valve c in the left direction as shown in the drawing to remove the check function (at this time, the second elastic member e 2 receives the compression force). That is, the second flow paths s 2 and s 4 of the check valve k are connected to each other.
  • the plunger h is shifted to press the check valve b in the right direction as shown in the drawing to remove the check function (at this time, the first elastic member e 1 receives the compression force). That is, the first flow paths S 1 and S 3 of the check valve k are connected to each other.
  • the hydraulic fluid fed from the hydraulic pump P is supplied to the large chamber d 1 of the hydraulic cylinder d after passing through the control valve a and the second flow paths s 2 and s 4 of the check valve k in order.
  • the hydraulic fluid fed from the small chamber d 2 of the hydraulic cylinder d is returned to the hydraulic tank after passing through the check valve b of which the check function has been removed, the first flow paths S 1 and S 3 , and the control valve a in order.
  • the hydraulic cylinder d is driven to be extended by the hydraulic fluid fed from the hydraulic pump P.
  • the construction equipment having the conventional double check valve has the problems that in the case where the control valve a is kept in a neutral state, the large chamber d 1 and the small chamber d 2 of the hydraulic cylinder d cannot be connected to each other through the check function of the check valves b and c installed in the double check valve k. Accordingly, in the case where the dozer blade f requires the floating function depending on the working condition, it is impossible to perform the floating function.
  • the present invention has been made to solve the above-mentioned problems occurring in the prior art while advantages achieved by the prior art are maintained intact.
  • One object of the present invention is to provide a double check valve having a floating function, whereby a working device that is operated by a hydraulic cylinder having a double check valve can perform a floating function when the working device performs land readjustment of a work surface, and thereby improving the workability.
  • a double check valve having a floating function which includes a hydraulic pump; a hydraulic cylinder connected to the hydraulic pump to operate a working device; a control valve installed to open/close 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 having a pair of plungers dividedly formed to be shifted in opposite directions to each other when a signal pressure is applied from an outside, and a pair of check valves being pressed to remove their check functions through a shifting of the plungers; wherein in the case where the control valve is shifted to a neutral state and a floating function mode of the working device is selected, a large chamber and a small chamber of the hydraulic cylinder are connected to each other by the double check valve.
  • the double check valve may further include a housing in which first flow paths connecting the control valve to the small chamber of the hydraulic cylinder and second flow paths connecting the control valve to the large chamber of the hydraulic cylinder are formed; a signal pressure flow path to which a signal pressure for shifting the plungers is supplied; a pressing member pressing the check valve for opening/closing the first flow paths; a first elastic member 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 pressing the check valve for opening/closing the second flow paths; and a second elastic member 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.
  • a pilot signal pressure which is supplied from the hydraulic pump to the signal pressure flow path, is used as a signal pressure for shifting the plungers.
  • FIG. 1 is a view explaining a floating function of a working device
  • FIG. 2 is a schematic view of construction equipment having a conventional double check valve installed thereon;
  • FIG. 3 is a view illustrating the use state of the double check valve when the control valve as illustrated in FIG. 2 is in a neutral state;
  • FIG. 4 is a view illustrating the use state of the double check valve when the control valve as illustrated in FIG. 2 is shifted;
  • FIG. 5 is a view illustrating the use state of the double check valve when the control valve as illustrated in FIG. 2 is shifted;
  • FIG. 6 is a sectional view of a double check valve having a floating function according to an embodiment of the present invention.
  • FIG. 7 is a view illustrating the use state of the double check valve when the control valve as illustrated in FIG. 6 is shifted;
  • FIG. 8 is a view illustrating the use state of the double check valve when the control valve as illustrated in FIG. 6 is shifted.
  • FIG. 9 is a view illustrating the use state of the double check valve when the control valve as illustrated in FIG. 6 is in a neutral state.
  • a double check valve having a floating function includes a hydraulic pump P; a hydraulic cylinder d connected to the hydraulic pump P to operate a working device; a control valve a installed in flow paths between the hydraulic pump P and the hydraulic cylinder d and shifted to control a start, a stop, and a direction change of the hydraulic cylinder d; and a double check valve k installed in first flow paths S 1 and s 3 and second flow paths S 2 and s 4 between the control valve a and the hydraulic cylinder d, and having a pair of plungers h 1 and h 2 dividedly formed to be shifted in opposite directions to each other when a signal pressure is applied from an outside to diaphragms n 3 and n 4 , and a pair of check valves b and c (e.g., ball type or poppet valves) being pressed to remove their check functions through a shifting of the plungers h 1 and h 2 .
  • a double check valve k installed in first flow paths S 1 and
  • a large chamber d 1 and a small chamber d 2 of the hydraulic cylinder d are connected to each other by the double check valve k.
  • the double check valve k may further include a housing m in which the first flow paths s 1 and s 3 connecting the control valve a to the small chamber d 2 of the hydraulic cylinder d and the second flow paths S 2 and s 4 connecting the control valve a to the large chamber d 1 of the hydraulic cylinder d are formed; a signal pressure flow path j to which a signal pressure for shifting the plungers is supplied from a pilot pump Pp; a pressing member f 1 pressing the check valve b for opening/closing the first flow paths s 1 and s 3 ; a first elastic member e 1 elastically supporting the pressing member f 1 so as to elastically bias the first flow paths s 1 and s 3 , which have been blocked by the check valve b, to their initial states; a pressing member f 2 pressing the check valve c for opening/closing the second flow paths s 2 and s 4 ; and a second elastic member f 2 elastically supporting the pressing member f 2 so as to elastically bias the second flow
  • a pilot signal pressure which is supplied from the hydraulic pump Pp to the signal pressure flow path j, is used as a signal pressure for shifting the plungers h 1 and h 2 .
  • the double check valve k may be driven by the hydraulic fluid fed from the hydraulic pump P or air pressure applied from a compressed air source (not illustrated).
  • the double check valve k serves as a check valve through the check valves b and c elastically supported by the first and second elastic members e 1 and e 2 and the pressing members f 1 and f 2 .
  • the pair of plungers h 1 and h 2 dividedly formed are kept in close contact with each other.
  • the check valve b blocks the first flow paths s 1 and s 3 that connect the control valve a to the small chamber d 2 of the hydraulic cylinder d
  • the check valve c blocks the second flow paths S 2 and s 4 that connect the control valve a to the large chamber d 1 of the hydraulic cylinder d.
  • the hydraulic fluid bed from the hydraulic pump P is not supplied to the hydraulic cylinder d. Also, the hydraulic fluid fed from the hydraulic cylinder d is not returned to the hydraulic tank.
  • the dozer blade f is prevented from sinking.
  • the check valve b is pressed to remove the check function, and the first flow paths s 1 and s 3 are connected to each other. Accordingly, the hydraulic fluid fed from the hydraulic pump P is supplied to the small chamber d 2 of the hydraulic cylinder d after passing through the control valve a and the first flow paths s 1 and s 3 in order.
  • the check valve c is pressed to remove the check function, and the second flow paths s 2 and s 4 are connected to each other. Accordingly, the hydraulic fluid fed from large chamber d 1 of the hydraulic cylinder d is returned to the hydraulic tank after passing through the second flow paths s 2 and s 4 and the control valve a in order.
  • the check valve c is pressed to remove the check function, and the second flow paths s 2 and s 4 are connected to each other. Accordingly, the hydraulic fluid fed from the hydraulic pump P is supplied to the large chamber d 1 of the hydraulic cylinder d after passing through the control valve a and the second flow paths s 2 and s 4 in order.
  • the check valve b is pressed to remove the check function, and the second flow paths s 2 and s 4 are connected to each other. Accordingly, the hydraulic fluid fed from small chamber d 2 of the hydraulic cylinder d is returned to the hydraulic tank after passing through the first flow paths s 1 and s 3 and the control valve a in order.
  • FIG. 9 is a view illustrating the use state of the double check valve when the control valve a is shifted to a neutral state and the floating function of the dozer blade f is selected.
  • the check valve b is pressed in the right direction to remove its check function (at this time, the first elastic member e 1 receives the compression force). That is, the first flow paths s 1 and s 3 of the check valve k are connected to each other.
  • the check valve c is pressed in the left direction to remove its check function (at this time, the second elastic member e 2 receives the compression force). That is, the second flow paths s 2 and s 4 of the check valve k are connected to each other.
  • control valve a and the small chamber d 2 of the hydraulic cylinder d are connected to each other by the first flow paths s 1 and s 3
  • control valve a and the large chamber d 1 of the hydraulic cylinder d are connected to each other by the second flow paths s 2 and s 4 .
  • the small chamber d 2 and the large chamber d 1 of the hydraulic cylinder d are connected to each other. That is, in the case where the hydraulic fluid fed from the large chamber d 1 of the hydraulic cylinder d in a non-load state is transferred to the small chamber d 2 of the hydraulic cylinder d (as indicated by an arrow) after passing through the second flow paths s 4 and s 2 , the control valve a, and the first flow paths s 1 and s 3 in order, the hydraulic cylinder d is driven to be contracted.
  • the double check valve having a floating function has the following advantages.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Check Valves (AREA)
  • Operation Control Of Excavators (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Valve Device For Special Equipments (AREA)
US11/825,637 2006-11-29 2007-07-06 Double check valve having floating function Abandoned US20080121101A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020060119035A KR100849500B1 (ko) 2006-11-29 2006-11-29 플로팅 기능이 구비된 더블 체크밸브
KR10-2006-0119035 2006-11-29

Publications (1)

Publication Number Publication Date
US20080121101A1 true US20080121101A1 (en) 2008-05-29

Family

ID=39167691

Family Applications (1)

Application Number Title Priority Date Filing Date
US11/825,637 Abandoned US20080121101A1 (en) 2006-11-29 2007-07-06 Double check valve having floating function

Country Status (5)

Country Link
US (1) US20080121101A1 (ja)
EP (1) EP1927759A1 (ja)
JP (1) JP2008138870A (ja)
KR (1) KR100849500B1 (ja)
CN (1) CN101191506A (ja)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090078111A1 (en) * 2007-09-20 2009-03-26 Volvo Construction Equipment Holding Sweden Ab. Double check valve having floating function
US20100139791A1 (en) * 2007-06-05 2010-06-10 Masahiro Tanino Hydraulic controller
US9068322B2 (en) 2010-05-18 2015-06-30 Volvo Construction Equipment Ab Double check valve for construction equipment
AU2012397386B2 (en) * 2012-12-20 2016-05-19 Volvo Construction Equipment Ab Construction machine with floating function
US10306827B2 (en) 2014-11-04 2019-06-04 Cnh Industrial Canada, Ltd. Hydraulic system for an air cart
US11332911B2 (en) * 2017-09-29 2022-05-17 Hitachi Construction Machinery Tierra Co., Ltd. Construction machine

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FR2933471B1 (fr) * 2008-07-03 2013-02-15 Vianney Rabhi Vanne electro-hydraulique a levee de bille pour centrale hydraulique de moteur a taux de compression variable
KR100985814B1 (ko) 2010-02-18 2010-10-08 파카코리아 주식회사 캐비테이션 방지장치가 구비된 더블 파일롯 체크밸브
KR101294673B1 (ko) * 2010-08-16 2013-08-09 국방과학연구소 자동 밀폐형 급속 유로전환 밸브
US20120324880A1 (en) * 2011-06-23 2012-12-27 Norihiro Kuzuu Electric-hydraulic hybrid driver
EP2696080B1 (de) * 2012-08-09 2016-12-14 HAWE Hydraulik SE Elektrohydrauliksteuerung
KR101570390B1 (ko) 2015-05-12 2015-11-19 주식회사 에프피씨 자동 유량보상 밸브 유닛
FR3049663B1 (fr) * 2016-03-31 2018-03-16 Lohr Industrie Bloc de securite a double clapet pour verin hydraulique
KR101835691B1 (ko) * 2017-11-06 2018-04-19 주식회사 에프피씨 유압작동 보조밸브
KR102772531B1 (ko) * 2022-11-22 2025-02-28 (주)한빛산업 볼 시트형 방향제어 밸브

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US3274902A (en) * 1965-10-22 1966-09-27 Deere & Co Hydraulic control system
US3908515A (en) * 1973-09-10 1975-09-30 Caterpillar Tractor Co Hydraulic circuit with selectively actuatable float control
US4286432A (en) * 1979-08-30 1981-09-01 Caterpillar Tractor Co. Lock valve with variable length piston and hydraulic system for a work implement using the same
US6997210B2 (en) * 1999-12-13 2006-02-14 Aladdin Engineering & Manufacturing, Inc. Valve arrangement including release valve

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US4166506A (en) 1975-06-30 1979-09-04 Kabushiki Kaisha Komatsu Seisakusho Controlling apparatus for bulldozer blade
US4506700A (en) 1983-10-07 1985-03-26 Deere & Company Poppet valve with float function
JPH06128984A (ja) * 1992-10-15 1994-05-10 Kubota Corp 作業車のドーザ装置
JPH10183674A (ja) 1996-12-25 1998-07-14 Toyo Umpanki Co Ltd 土工具昇降装置
DE19919014C2 (de) 1999-04-27 2001-03-01 Danfoss Fluid Power As Nordbor Hydraulikventil mit einer Verriegelungs- und einer Schwimmfunktion

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
US3274902A (en) * 1965-10-22 1966-09-27 Deere & Co Hydraulic control system
US3908515A (en) * 1973-09-10 1975-09-30 Caterpillar Tractor Co Hydraulic circuit with selectively actuatable float control
US4286432A (en) * 1979-08-30 1981-09-01 Caterpillar Tractor Co. Lock valve with variable length piston and hydraulic system for a work implement using the same
US6997210B2 (en) * 1999-12-13 2006-02-14 Aladdin Engineering & Manufacturing, Inc. Valve arrangement including release valve

Cited By (9)

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KR100849500B1 (ko) 2008-07-31
JP2008138870A (ja) 2008-06-19
CN101191506A (zh) 2008-06-04
KR20080048711A (ko) 2008-06-03
EP1927759A1 (en) 2008-06-04

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