US20130177377A1 - Coupling arrangement - Google Patents

Abstract

A coupling arrangement for fluid coupling a work tool to a machine comprising at least one coupler assembly slideably mounted for coupling a machine fluid circuit and a worktool fluid circuit; at least one actuator for retracting the at least one coupler assembly from a connect position to a disconnect position; and a sensor to detect the position of the at least one actuator for actuation of a locking device.

Description

TECHNICAL FIELD
• The present disclosure is directed to a coupling arrangement, more particularly to a coupling arrangement for coupling a work tool to a machine.
BACKGROUND
• Work tools, such as shears, grabs, or buckets may be coupled with host machines, such as excavators, to perform work operations like cutting, grabbing or excavating. The work tools may be coupled to a boom or stick mechanism of the host machine via a fixed connection or a quick release connection.
• A quick release connection allows for a relatively easy exchange of the work tool whereby the operator may connect or change a work tool without leaving the cab. The machine mounting bracket is arranged to slide into the work tool mounting bracket, when the work tool is positioned on the ground. After aligning the mounting bracket of the work tool and the mounting bracket of the machine, a locking device may be moved into a locked position to lock the work tool to the machine.
• When connecting the work tool to the machine, the hydraulic hoses of the machine and work tool pressure fluid circuits may be connected for driving the work tool. Automatic hydraulic hose connection systems are known which may be activated by the operator from the cab for connection of the hydraulic hoses. Such systems may often be dependent on the connection of the work tool to the machine. Hydraulic hose couplers may be provided and arranged so that during connection of the work tool to the machine the hose couplers are also automatically connected. When the work tool mounting bracket is connected to the machine mounting bracket, the hose couplers may be contemporaneously connected.
• However, aligning the hose couplers may require a higher level of accuracy than alignment of the mounting brackets. In practice, when a coupling arrangement is provided with such hose couplers, an operator may try to avoid relatively rough movements and high forces that are typical when connecting the work tool to the machine. Such actions may result in loss in efficiency. Nevertheless, a relatively high risk to cause damage to the hydraulic hose couplers remains due to the high forces and potential rough alignments between the mounting brackets. When the hose couplers are not aligned accurately, at connection of the machine and work tool pressure fluid circuits, pressurized fluid may escape or the couplers and/or hoses may need to be changed. As the hydraulic circuits of host machines may operate under relatively high pressures, any leakage may cause major spillage of hydraulic fluid and significant downtime.
• EP1388616 discloses a coupling arrangement for coupling two ends of a pressurized hydraulic fluid circuit of a work tool and a machine. The coupling arrangement may comprise a quick release mounting bracket for coupling a work tool to a machine. The coupling arrangement may comprise a receiving fluid coupler and a moving fluid coupler, each coupler being connected to a hydraulic hose of a main hydraulic circuit.
• One of the couplers may be arranged on the work tool and the other coupler may be arranged on the machine. Both couplers may be connected to each other for providing a fluid passage between the hydraulic hoses so that pressurised fluid may circulate between the fluid circuit of a work tool and a machine. The moving fluid coupler may be moved on a sledge to and from the receiving fluid coupler by an actuator. When the respective moving coupler is coupled to the receiving coupler, a locking notch may engage the moving coupler to keep both couplers coupled so that the actuator may release its pressure while fluid flows through the couplers. The locking notch requires significant space in the coupling arrangement. Moreover, after multiple engagements, the locking notch may become damaged, or may allow for play to occur which may cause leakage of fluid between the couplers. However, without the locking notch, the actuator would have to withstand significant forces that are exerted by the pressurised fluid flowing through the circuit, which may disengage the couplers. Furthermore, during movement of the coupler, the hydraulic hose that is coupled to the moving coupler may become wedged, caught, or trapped in or between the structure of the machine and/or the work tool.
• WO2010062166, in the name of Caterpillar Work Tools B.V., discloses a coupling arrangement for coupling a work tool to a machine. The coupling arrangement may have a locking arrangement for locking the work tool to the machine. The locking arrangement may comprise a locking member which may be moved to a locked position where it abuts the locking member receiving elements.
• The coupling arrangement further may have at least two fluid couplers arranged to be connected to each other for establishing a fluid passage between a main pressurized fluid circuit channel of a work tool and a main pressurized fluid circuit channel of a machine. The coupling arrangement may further have a driving arrangement for driving at least one of the fluid couplers for connection to the other fluid coupler, the driving arrangement being separate from the main pressurized fluid circuit.
• The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of the prior art system.
BRIEF SUMMARY OF THE INVENTION
• In a first aspect, the present disclosure provides a coupling arrangement for fluid coupling a work tool to a machine comprising at least one coupler assembly slideably mounted for coupling a machine fluid circuit and a worktool fluid circuit; at least one actuator for retracting the at least one coupler assembly from a connect position to a disconnect position; and a sensor to detect the position of the at least one actuator for actuation of a locking device.
• In a second aspect, the present disclosure provides a method of decoupling a worktool from a machine comprising providing at least one coupler assembly slideably mounted for coupling a machine fluid circuit and a worktool fluid circuit; arranging at least one actuator to retract the at least one coupler assembly from a connect position to a disconnect position; arranging a sensor to detect the position of the at least one actuator; and activating the sensor when the at least one actuator is fully retracted to permit pressurised fluid to flow to the locking device for decoupling of the worktool.
• Other features and advantages of the present disclosure will be apparent from the following description of various embodiments, when read together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing and other features and advantages of the present disclosure will be more fully understood from the following description of various embodiments, when read together with the accompanying drawings, in which:
• FIG. 1 is a side view of a machine and a work tool provided with a coupling arrangement according to the present disclosure;
• FIG. 2 is a schematic representation of an embodiment of the coupling arrangement according to the present disclosure;
• FIG. 3 is an isometric view of an embodiment of a coupling assembly according to the present disclosure;
• FIG. 4 is a cross sectional view of a mounted coupling assembly ofFIG. 2 in a retracted position according to the present disclosure; and
• FIG. 5 is a cross sectional view of a mounted coupling assembly ofFIG. 2 in an extended position according to the present disclosure.
DETAILED DESCRIPTION
• This disclosure generally relates to acoupling arrangement10 for coupling a machine hydraulic fluid circuit to a work tool hydraulic fluid circuit.
• FIG. 1 illustrates a host machine1, as a hydraulic excavator, which may be provided with a hydraulic boom mechanism for driving aboom2 and a work tool3. In this description, aboom2 may be understood as comprising a hydraulic stick mechanism, or similar mechanisms.
• Machine1 may be a mobile machine such as for example an excavator, a back hoe, a digger, a loader, a knuckle boom loader, a harvester or a forest machine.
• The work tool3 may be coupled to the machine1 through theboom2. In the embodiment shown, the work tool3 may comprise a rotary cutter. In other embodiments, work tools3 may for example include buckets, grapples, hammers and pulverizers.
• The work tool3 may comprise a frame that which carries multiple exchangeable and/or interchangeable tools.
• The machine1 may be provided with acoupling arrangement10. Thecoupling arrangement10 may allow for fluid coupling between amachine bracket12 and awork tool bracket14. Themachine bracket12 may be connected to the machine1. Thework tool bracket14 may be connected to the work tool3.
• Apressurised fluid assembly15 may extend along theboom2 for moving theboom2 and the work tool3. Thepressurised fluid assembly15 may comprise multiple hydraulic circuits, including a machine fluid circuit and an actuation fluid circuit.
• The work tool3 may comprise a work tool fluid circuit for the hydraulic control thereof. The machine fluid circuit may control fluid flow through the work tool fluid circuit.
• The machine fluid circuit may be arranged to drive theboom2 and to pivot the boom parts with respect to each other. The machine fluid circuit may be arranged to move the work tool3. For example, the machine fluid circuit may be arranged to pivot and/or rotate the work tool3 or may be arranged to drive moving parts in the work tool3, such as rotary parts. The actuation fluid circuit may be arranged to enable fluid coupling between the machine fluid circuit and the work tool fluid circuit.
• FIG. 2 illustrates an embodiment of acoupling arrangement10 with hydraulic connections for connecting amachine bracket12 to awork tool bracket14 and for forming at least one fluid passage between the machine fluid circuit and the work tool fluid circuit.
• Thecoupling arrangement10 may comprise themachine bracket12 which may be provided with at least onecavity16. Thecavity16 may extend through themachine bracket12 and may have a cavitywide portion18 and a cavitynarrow portion20.
• Cavitynarrow portion20 may be formed as a plurality of extensions of the wall ofcavity16. In an embodiment, the cavitynarrow portion20 may be a single block extension of the wall ofcavity16. Ashoulder22 may be formed between the cavitywide portion18 and the cavitynarrow portion20.
• Thecoupling arrangement10 may comprise acoupler assembly24 movably mounted in thecavity16. Both thecavity16 and thecoupler assembly24 may be correspondingly shaped to allow for the relative movement of thecoupler assembly24. Thecoupler assembly24 may be slidably mounted with at least portions thereof being in sliding engagement with the wall of thecavity16. Thecoupler assembly24 may slide between a refracted position, where thecoupler assembly24 retracts fully or partially into thecavity16, and an extended position, where thecoupler assembly24 protrudes from themachine bracket12 for engagement with a corresponding fluid coupler in thework tool bracket14.
• Thecoupling arrangement10 may comprise achamber26 provided in thecavity16. In an embodiment thechamber26 may be formed in the cavitywide portion18 and may be bounded by the wall of the cavitywide portion18, theshoulder22 and thecoupler assembly24.
• The size ofchamber26 may vary through the movement of thecoupler assembly24 relative to themachine bracket12. The size ofchamber26 may be made to vary through the inflow and outflow of hydraulic fluid which may move thecoupler assembly24 relative to themachine bracket12. The changes in the size of thechamber26 may effect the corresponding retraction and extension of thecoupling assembly24.
• In an embodiment themachine bracket12 may be provided with a series ofcavities16. Eachcavity16 may have a movably mountedcoupler assembly24 and achamber26. For fluid coupling themachine bracket12 to awork tool bracket14, thework tool bracket14 may comprise fluid couplers which connect tocorresponding coupler assemblies24 mounted in themachine bracket12. Fluid coupling themachine bracket12 to awork tool bracket14 may be effected with thecoupler assemblies24 in the fully extended positions or the connect position. Thecoupler assemblies24 may be in a disconnect position when refracted from the fully extended position.
• For operation and control of thecoupling arrangement10 the hydraulic connections may be suitably provided. The machine fluid circuit may comprise hydraulic lines leading to thecavities16 for connection torespective coupler assemblies24. In an embodiment, hydraulic lines A, B, C, D and L of the machine fluid circuit may allow flow of hydraulic fluid to and from the work tool fluid circuit when fluid coupling between thebrackets12,14 are established. Hydraulic fluid may flow through thecoupler assemblies24 in the connect position to and from the corresponding fluid couplers in thework tool bracket14.
• Thecoupling arrangement10 may include hydraulic connections to a quick coupler mechanism for locking togetherbrackets12,14, such as a quick coupler wedge.
• The actuation fluid circuit may be controlled independently from the machine fluid circuit. The actuation fluid circuit includes at least oneactuator28. In an embodiment, the actuator may be a hydraulic cylinder. Theactuator28 may be connected contemporaneously to all thecoupler assemblies24. Theactuator28 may be connected to thecoupler assemblies24 through suitable linkages such as through a connecting rod.
• Refraction or extension of theactuator28 may correspondingly retract or extend thecoupler assemblies24 to a disconnect position or to a connect position respectively. Thecoupler assemblies24 may be uniformly retracted or extended by theactuator28. In an embodiment, a pair ofactuators28 may be provided to ensure an evenly balance load for fluid coupling or decoupling between thecoupler assemblies24 and the corresponding fluid couplers.
• The operation of the actuation fluid circuit may be controlled by abracket switch30.Bracket switch30 may control hydraulic fluid flow for the extension of thecoupler assemblies24.Bracket switch30 may be suitably disposed in order to detect when awork tool bracket14, having at least one corresponding fluid coupler, is mounted to amachine bracket12. In an embodiment, thebracket switch30 may be suitably positioned on themachine bracket12. Thebracket switch30 may not be activated if thework tool bracket14 does not carry any corresponding fluid couplers and fluid coupling may not be effected as no flow of hydraulic fluid to extend thecoupler assemblies24 to the connect position is permitted by thebracket switch30.Bracket switch30 may prevent actuation of thecoupler assemblies24 when no corresponding fluid couplers are present in the attachedwork tool bracket14.
• The operation of the machine fluid circuit may be further controlled by aswitch32.Switch32 may control the flow of hydraulic fluid to alocking device34 for the unlocking of thebrackets12,14.Switch32 may be arranged to be activated only when theactuator28 is in a fully retracted position. Theswitch32 may be arranged not to be activated when theactuator28 is in an extended position and unlocking of thebrackets12,14 may not be effected as no flow of hydraulic fluid to actuate thelocking device34 is permitted by theswitch32.Switch32 prevents premature decoupling between themachine bracket12 and thework tool bracket14 whencoupler assemblies24 have not been retracted from the connect position.
• In an embodiment theswitches30,32 may be sensors connected to actuating mechanisms. In an embodiment theswitches30,32 may be a solenoid or a hydro mechanical device. In an embodiment theswitches30,32 may be hydromechnical switches which are activated upon physical contact withwork tool bracket14 and theactuator28.
• Thecoupling arrangement10 may further comprise arail circuit13, denoted by a bold line inFIG. 2, which connects together eachchamber26. Therail circuit13 may be comprised of a single hydraulic line connected to each of thechambers26 through further hydraulic lines. Therail circuit13 may distribute the fluid pressure equally among thechambers26. Accordingly, the highest pressure in any onechamber26 may generate the load required to effect the corresponding extension of thecoupler assemblies24 in theother chambers26. Thechamber26 having the highest working pressure may define the force presented to allcoupler assemblies24.
• Therail circuit13 may be connected to theactuators28. In an embodiment, therail circuit13 may be connected to the piston side of theactuators28, provided as a hydraulic cylinder.
• Thecoupling arrangement10 may be connected to ahydraulic power circuit35 for providing hydraulic pressure to lock and unlockmachine bracket12 to thework tool bracket14. Unlocking of thebrackets12,14 by thehydraulic power circuit35 may be controlled by theswitch32 through hydraulic connections between thehydraulic power circuit35 and theswitch32.
• Thehydraulic power circuit35 may be connected to theactuator28. In an embodiment, thehydraulic power circuit35 may be connected to the rod side of theactuator28, provided as a hydraulic cylinder.
• Thehydraulic power circuit35 may be arranged to provide pressurised fluid to therail circuit13. Thebracket switch30 may be disposed in the connection between thehydraulic power circuit35 and therail circuit13.
• FIG. 3 illustrates acoupler assembly24. Thecoupler assembly24 may comprise ahollow plunger36.Plunger36 may have a suitable form and dimensions to be slidingly mounted within thecavity16.Plunger36 may have a plungernarrow portion38, agate portion39 and a plungerwide portion40. In an embodiment, thegate portion39 may be positioned within the plungerwide portion40 and adjacent to the plungernarrow portion38. Thegate portion39 may be recessed from the plungerwide portion40.
• The plungernarrow portion38 may be in sliding engagement with the cavitynarrow portion20. The plungernarrow portion38 may be arranged to sealingly engage with cavitynarrow portion20 to restrict leakage of hydraulic fluid between the plungernarrow portion38 and the cavitynarrow portion20.
• The plungerwide portion40 may be in sliding engagement with the cavitywide portion18. The plungerwide portion40 may be arranged to sealingly engage with cavitywide portion18 to restrict leakage of hydraulic fluid between the plungerwide portion40 and the cavitywide portion18.
• Thegate portion39 may not be in contact with wall of the cavitywide portion18.
• Afluid coupler42 may be positioned within theplunger36.Plunger36 may be provided with retaining structures to hold thefluid coupler42 within the walls thereof.Fluid coupler42 may have a throughfluid channel43 along the longitudinal axis of theplunger36. Thefluid channel43 may communicate with the hollow of theplunger36.
• Thefluid coupler42 may couple with the corresponding fluid coupler, having a fluid channel disposed therein, in thework tool bracket14. Respective fluid channels form a fluid passage when the fluid couplers are connected. At fluid coupling hydraulic fluid from the machine fluid circuit may flow through the fluid channels to the work tool fluid circuit.Fluid coupler42 may be formed as a male or female element for coupling to the fluid coupler with the corresponding form.
• Extending laterally from theplunger36 may be apressure element44. In an embodiment thepressure element44 may encircle theplunger36 and may be formed as a rib or a protrusion. In an embodiment thepressure element44 may extend from and encircle the plungerwide portion40. With thecoupler assembly24 mounted in thecavity16, thepressure element44 may extend from theplunger36 through thecavity16 to slidingly engage the wall of the cavitywide portion18. Thepressure element44 may separate thechamber26 from rest of the cavitywide portion18.
• Thepressure element44 may be arranged to sealingly engage with the wall of the cavitywide portion18 to limit leakage of hydraulic fluid between the wall of the cavitywide portion18 and thepressure element44. Thepressure element44 may be suitably shaped or may be provided with a gasket to slidingly and sealingly engage cavitywide portion18.
• Thepressure element44 may have apressure surface45 which, in an embodiment, may face theshoulder22. The dimensions and/or shape of thepressure surface45 may be a function of the diameter of thecoupler assembly24, the diameter of thefluid coupler42, the diameter of the corresponding fluid coupler in thework tool bracket14 and/or the difference in the diameters of thefluid coupler42 and the corresponding fluid coupler. The dimensions and/or shape of thepressure surface45 may depend on the fluid dynamics of thefluid coupler42 and the corresponding fluid coupler. Fluid dynamics may be dependent on the structure of fluid couplers, the type of hydraulic fluid and/or the fluid pressure used for the fluid coupling.
• At least one bore46 may be provided in theplunger36 which may allow flow of hydraulic fluid from the exterior of theplunger36 into the hollow thereof. Thefluid channel43 of thefluid coupler42 may communicate through the hollow of theplunger36 with thebore46. Thebore46 may be provided in thegate portion39. In an embodiment, thegate portion39 may be provided with a plurality ofbores46. Hydraulic fluid may flow around thegate portion39 guided by walls formed by the plungerwide portion40 and into the hollow through the plurality ofbores46.
• In an embodiment, asingle bore46 may be provided in theplunger36, not provided with agate portion39. Thebore46 may be positioned between thepressure element44 and the plungerwide portion40.
• The size and the number of thebores46 may be a function of the diameter of thecoupler assembly24, the diameter of thefluid coupler42, the diameter of the corresponding fluid coupler in the work tool bracket and/or the difference in the diameters of thefluid coupler42 and the corresponding fluid coupler. The dimensions and/or shape of thebore46 may be dependent on the dimension and/or shape of thepressure surface45. The dimensions and/or shape of thebore46 may depend on the fluid dynamics of thefluid coupler42 and the corresponding fluid coupler.
• FIGS. 4 and 5 illustrate acoupler assembly24 slidingly mounted in themachine bracket12. InFIG. 4 thecoupler assembly24 may be retracted to the disconnect position and inFIG. 5 thecoupler assembly24 may be extracted to the connect position. The retraction of thecoupler assembly24 within thecavity16 may be limited by theshoulder22 which may abut pressuresurface45.
• Machine bracket12 may have amachine circuit line48, which forms part of the machine fluid circuit, leading to thecavity16. Fluid from the machine fluid circuit may flow through themachine circuit line48 to thecavity16 through aport49. In themachine bracket12 having plurality ofcavities16, eachcavity16 may be separately connected to the machine fluid circuit through a plurality of corresponding circuit lines48. In an embodiment, hydraulic lines A, B, C, D and L may allow flow of hydraulic fluid to and from theports49 through respective machine circuit lines48.
• Machine bracket12 may have arail circuit line50, which forms part of the rail fluid circuit, leading to thecavity16. In an embodiment therail circuit line50 leads to thechamber26. Fluid from the rail fluid circuit may flow through therail circuit line50 to thechamber26.
• Thechamber26 in the cavitywide portion18 may be bounded by the wall of the cavitywide portion18, theshoulder22, thepressure surface45 and the plungernarrow portion38. The size ofchamber26 may depend on the inflow and outflow of hydraulic fluid through therail circuit line50. Inflow of fluid into thechamber26 may result in an increase in fluid pressure therein, as thechamber26 may be fluid tight. The fluid pressure may act on the surfaces which bound thechamber26. The increasing fluid pressure acting on thepressure surface45 may effect extraction of thecoupler assembly24 slidingly mounted in themachine bracket12. Thecoupler assembly24 may be extracted to the connect position through continued inflow of hydraulic fluid under pressure to establish fluid coupling between thefluid coupler42 and the corresponding fluid coupler in thework tool bracket14.
• Adiversion passage52 may extend axially within theplunger36 from thegate portion39 toward thepressure element44. Thediversion passage52 may be axially aligned with the longitudinal axis of theplunger36. In an embodiment thediversion passage52 may extend beyond thepressure element44. Hydraulic fluid flowing through thebores46 may flow into the hollow of theplunger36 and to thediversion passage52.
• The dimensions and/or shape of thediversion passage52 may be a function of the diameter of thecoupler assembly24, the diameter of thefluid coupler42, the diameter of the corresponding fluid coupler in the work tool bracket and/or the difference in the diameters of thefluid coupler42 and the corresponding fluid coupler. The dimensions and/or shape of thediversion passage52 may be dependent on the dimension and/or shape of thebore46. The dimensions and/or shape of thediversion passage52 may be dependent on the dimension and/or shape of thepressure surface45. The dimensions and/or shape of thediversion passage52 may depend on the fluid dynamics of thefluid coupler42 and the corresponding fluid coupler.
• Extending from thediversion passage52 may be adiversion line54. The diversion line connects thediversion passage52 to thechamber26. In an embodiment thediversion line54 may extend laterally from thediversion passage52 to thechamber26. In an embodiment, thediversion line54 may be disposed such that thepressure surface45 is positioned between thebores46 and thediversion line54. In an embodiment the diversion passage is a hose mounted externally to theplunger36. In an embodiment, thediversion line54 may have a smaller diameter thandiversion passage52 such that the fluid pressure increases as the hydraulic fluid enters thediversion line54. Hydraulic fluid flowing into thebore46 may flow through thediversion passage52 and the diversion line into thechamber26.
• Acheck valve56 may be provided at the junction of thediversion passage52 and thediversion line52. Thecheck valve56 may permit flow of fluid from thediversion passage52 todiversion lines54 and prevent flow of fluid from thediversion line54 todiversion passage52. In an embodiment,check valve56 may be disposed such that thepressure surface45 is positioned between thebore46 and thecheck valve56.
• With reference toFIG. 4 thecoupler assembly24 is retracted and may be disconnected from the corresponding fluid coupler. Thegate portion39 may be recessed into the cavitywide portion18. Thegate portion39 may be sealed from fluid entry by the cavitywide portion18.Port49 of themachine circuit line48 may be sealed by the plungerwide portion40.
• In an embodiment, bore46, in theplunger36 not provided with agate portion39, may be recessed into the cavitywide portion18 and may be sealed from fluid entry by the cavitywide portion18.
• With reference toFIG. 5 thecoupler assembly24 is extended and may be connected to the corresponding fluid coupler. Thegate portion39 may be positioned to be in fluid communication with theport49 of themachine circuit line48. Fluid may flow from themachine circuit line48 throughport49 and into thegate portion39. Hydraulic fluid may flow around thegate portion39 and into the hollow ofplunger36 through the plurality ofbores46.
• In an embodiment, when thegate portion39 is in fluid communication withmachine circuit line48 thecoupler assembly24 may be at a fully extended position. In an embodiment, thegate portion39 may have dimension and/or shape which corresponds to theport49.
• In an embodiment withplunger36 not provided with agate portion39, when thecoupler assembly24 is extended thebore46 may be positioned to be in fluid communication with theport49 of themachine circuit line48. Fluid may flow from themachine circuit line48 throughport49 and into thebore46. Hydraulic fluid may flow into the hollow ofplunger36 through thebore46.
• In an embodiment, thebore46 may have dimension and/or shape which corresponds to theport49. In an embodiment, when thebore46 is in fluid communication withmachine circuit line48 thecoupler assembly24 may be at a fully extended position.
• With reference toFIG. 2, the operation of thecoupling arrangement10 may be initiated by coupling amachine bracket12 to awork tool bracket14. Thehydraulic power circuit35 may be activated to actuate thelocking device34 to lockmachine bracket12 to thework tool bracket14. The lockingdevice34 may be actuated to lock thebrackets12,14 through increased fluid pressure through line X. In an embodiment, the increased fluid pressure may act on the rod side of thelocking device34.
• Upon locking of thebrackets12,14, pressure in the hydraulic lines may increase further. Apressure regulator58 may be connected to line X.Pressure regulator58 may open only when the locking pressure in thelocking device34 is higher than a preset value. In an embodiment, the value is selected from the range of 60 bar-90 bar. In an embodiment, the value is 70 bar. Flow of hydraulic fluid to thebracket switch30 and therail circuit13 may be prevented before thebrackets12,14 are mechanically locked.
• Hydraulic fluid may flow to thebracket switch30 when thepressure regulator58 opens to permit fluid flow.Bracket switch30 may be activated if thework tool bracket14, carrying a corresponding fluid coupler, is coupled to themachine bracket12. Activation of thebracket switch30 may effect the actuation of avalve60 to permit flow of fluid to checkvalve62.
• Checkvalve62 may permit fluid to flow into therail circuit13 and throughrail circuit lines50 to thechambers26. Increased flow of fluid in thechambers26 results in increased fluid pressure therein. The fluid pressure may act on the pressure surfaces45 of thecoupler assemblies24 effecting extension from the disconnect position to an extended position at which a fluid coupling between thefluid couplers42 and the corresponding fluid couplers in thework tool bracket14 is established. The build up of pressure inchamber26 may not enter the hollow ofplunger36 as a result of thecheck valve56 which blocks the flow of fluid from thediversion line54 to thediversion passage52.
• In an embodiment,check valve62 may permit fluid to flow through therail circuit13 to the piston side of theactuators28. Increased flow of fluid into the piston side chambers of theactuators28 may result in increased fluid pressure therein to effect extension of theactuators28. Theactuators28 may be connected to thecoupler assemblies24 and may effect a corresponding extension of thecoupler assemblies24. The extension of thecoupler assemblies24 through extension of theactuators28 may be optional or may be in addition to the extension effected by the action of the pressurised fluid on thepressure surface45.
• Extraction of thecoupler assemblies24 through the pressure build up in thechambers26 and/or extension of theactuators28, may connect lines A,B,C,D and L throughrespective lines48 andports49 to the hollows ofplungers36 to allow fluid flow from the machine fluid circuit into the hollow ofplunger36. If the machine fluid circuit is not actuated, fluid inside the hollow ofplunger36 may remain at atmospheric or tank pressure. Upon actuation of the machine fluid circuit the pressure in thelines48 and the hollow ofplunger36 may increase.
• At fluid coupling between thefluid couplers42 and the corresponding fluid couplers, thegate portions39 may be in fluid communication withports49 allowing fluid to flow throughmachine circuit lines48 into the hollow ofplunger36. Fluid may then pass throughfluid channels43 in thefluid couplers42 to the respective channels in the corresponding fluid couplers.
• In an embodiment, at fluid coupling between thefluid couplers42 and the corresponding fluid couplers, thebores46 of eachplunger36 may be in fluid communication withports49 allowing fluid to flow throughmachine circuit lines48 into the hollow ofplunger36. Fluid may then pass throughfluid channels43 in thefluid couplers42 to the respective channels in the corresponding fluid couplers.
• At fluid coupling between thefluid couplers42 and the corresponding fluid couplers and flow of pressurised fluid through the respective fluid channels, separation forces may be generated which act on the fluid couplers. The separation forces may be countered by the fluid pressure acting on thepressure surface45 and/or theactuators28. In an embodiment, pressure in thechamber26 may be sufficient to generate a force on thepressure surface45 to maintain fluid coupling between the fluid couplers. In an embodiment, fluid coupling between the fluid couplers may be maintained through the pressure in theactuators28 and the pressure in thechamber26 acting on thepressure surface45.
• The separation forces generated may be dependent on the pressure of the fluid in the machine circuit. In an embodiment, an increase in the machine fluid circuit pressure may result in a higher separation force between the fluid couplers. Thepressure surface45 may be provided such that the difference in the ratio between the fluid coupler surfaces andpressure surface45 is greater than 1 so that force acting onpressure surface45 is greater than the separation force.
• Thechamber26 may be connected to the machine fluid circuit via thecheck valve56 mounted in theplunger36. If pressure in the machine fluid circuit is higher than the pressure in thechamber26, the fluid in the hollow of theplunger36 may be at a higher pressure value and may flow to thechamber26 where the fluid pressure has a lower pressure value. The fluid at a higher pressure will flow from the hollow of theplunger36 through thediversion passage52, thecheck valve56 and thediversion line54 into thechamber26. The flow of fluid may continue till the pressure in thechamber36 and pressure in the hollow of theplunger36 equalise.
• As the pressure in thechamber26 generates a force on thepressure surface45, the force acting on thepressure surface45 may be equal to the separation forces generated by the fluid flowing from the hollow ofplunger36 through the fluid channels and which act on the fluid couplers. The equalising of pressures in thechamber26 and the hollow ofplunger36 may serve to lock thecoupler assemblies24. As allchambers26 are connected through therail circuit13, a higher pressure load in onechamber26 may be distributed to theother chambers26, even if the pressures in the hollow of therespective plungers36 may be at a lower pressure value.
• As fluid may not flow from thechamber26 to the hollow ofplunger36, due to thecheck valve56, the pressure in thechamber26 may remain even when the pressure in the machine fluid circuit drops to a pressure value lower than the pressure value in thechamber26. The pressure level may be available in thechambers26 independent of the pressure in the hydraulic lines A, B, C, D and L of the machine circuit. As allchambers26 are connected through therail circuit13, a balanced pressure load may be present to allcoupler assemblies24, even if the machine circuit pressure is lower or absent.
• In an embodiment, checkvale62 may be pilot operated to block inflow of fluid having potentially damaging fluid pressures so as to avoid damage to components that may not be designed to withstand a high pressure. Thecheck valve62 may block high pressure in therail circuit13 from reaching thelocking device34.
• In an embodiment, apressure relief valve64 may connect therail circuit13 to machine fluid circuit. Thepressure relief valve64 may be an adjustable pilot operated valve that is mounted to remove excessive pressure peaks generated in the machine fluid circuit that may be transmitted to thechambers26 through thecheck valve56 and therail circuit13. Thepressure relief valve64 may have pressure setting that is significantly higher than the maximum pressure tolerable in thechambers26 and therail circuit13 to avoid unintended loss of force needed to maintain fluid coupling. In an embodiment, thepressure relief valve64 may have pressure setting selected from the range of 390 bar-420 bar. In an embodiment, the pressure setting is 420 bar.
• With reference toFIG. 2, operation of thecoupling arrangement10 to decouplemachine bracket12 from thework tool bracket14 may be initiated by relieving pressure in thechambers26 and therail circuit line50 through therail circuit13.
• In an embodiment, a primary drain circuit for therail circuit13 may be provided through a normally-open drainage switch66 and primarydrainage check valves68,70.Drainage switch66 may close to block the drain function, only when thechambers26 and therail circuit line50 are pressurised.
• Primarydrainage check valves68,70 may be connected to the machine fluid circuit. In an embodiment primarydrainage check valves68,70 may be connected to lines A and B, wherein either one of these lines may be depressurized to allow return fluid to flow back to the tank. The return fluid may consist of a fluid volume in the piston side of theactuators28 and in thechambers26.
• In an embodiment, further primary drainage check valves may be provided which are connected to the other hydraulic lines.
• Pressure in line X may relieved while line Y may be pressurised though thehydraulic power circuit35. Fluid from line Y may flow into the rod side of theactuators28. Increase in pressure in the rod side and the reduction of pressure in the piston side may effect a retraction of theactuators28. As theactuators28 are connected to thecoupler assemblies24, thecoupler assemblies24 may be correspondingly retracted and disconnected from fluid coupling. The full retraction of theactuators28 may correspondingly effect complete retraction of thecoupler assemblies24 into themachine bracket12.
• A secondary drain circuit may consist ofcheck valve62 and secondarydrainage check valve72. Thevalves62 and72 may allow fluid to flow back to the tank through line X but only if line Y is pressurised. The return fluid may consist of a fluid volume in the piston side of theactuators28 and in thechambers26.
• Switch32 may detect the position of theactuators28.Switch32 may be normally closed and may block flow of fluid from thehydraulic power circuit35 through line Y to lockingdevice34. At complete retraction of theactuators28 theswitch32 may effect the actuation of thevalve73 to permit flow of fluid from thehydraulic power circuit35 to the piston side of thelocking device34 to unlock thebrackets12,14. This is a safety measure to avoid unintended operation of thelocking device34 if the coupler assemblies have not been retracted completely into themachine bracket12.
• Arelief valve74 may be provided in the hydraulic line connecting line Y and the rod sides of theactuators28 to avoid any unintended drift of theactuators28 in the disconnected position. Therelief valve74 may be pilot operated. The fluid in the rod side of theactuators28 may be trapped unlesschambers26 and thelines50 are pressurized to such level as topressure regulator58.
• The skilled person would appreciate that foregoing embodiments may be modified to obtain the apparatus of the present disclosure.
INDUSTRIAL APPLICABILITY
• This disclosure describes acoupling arrangement10 for coupling a machine hydraulic fluid circuit to a work tool hydraulic fluid circuit. In a machine1, work tools3 may be used for handling heavy materials. Work tools3 may demolish, drill, dig, plow, cut, grab and/or carry heavy materials which may include sand, stone, metal, and more. Work tools3 may be coupled to and powered by machines1, in particular mobile host machines. The machine1 may be provided with transmissions, hydraulic equipment,booms2 and/or sticks for driving the work tool3. Work tool operations may be controlled by the operator via an operating panel in the cab of the machine1.
• Thecoupling arrangement10 may have at least onehollow plunger36 provided with acheck valve56. Thehollow plunger36 may connect the machine fluid circuit to the rail fluid circuit throughdiversion passage52 anddiversion line54. The fluid pressure in the machine fluid circuit may be used to retain the fluid coupling of the fluid couplers. Thecheck valve56 may restrict the fluid flow from the rail fluid circuit to the machine fluid circuit.
• In operation of thecoupling arrangement10, pressure in thechambers26 may be provided from either the rail fluid circuit, during the connection process, or the machine fluid circuit, during operation of the work tool. Checkvalves56 and62 may allow pressure to build up in thechambers26. The prevailing pressure value in thechambers26 may be the higher of the pressure values of the machine fluid circuit or the rail fluid circuit. This pressure in thechambers26 may remain even if the pressure source is no longer available.Pressure relief valve64 may protect thechambers26, therail circuit line50 and therail circuit13 against damage as a result of excessive pressure.
• Thecoupling arrangement10 may have at least onehollow plunger36 provided with agate portion39 having a plurality ofbores46 or abore46. When thecoupler assemblies24 are retracted to a disconnect position, thechambers26 may be sealed from the hydraulic lines of the machine fluid circuit. At disconnection, thecoupler assembly24 may not be actuated unintentionally as a result of pressure build up in the hydraulic lines of the machine fluid circuit when fluid coupling has not yet been established.
• Thecoupling arrangement10 may have a rail fluid circuit to ensure a balanced load on thecoupler assemblies24. Allchambers26 may be connected through the rail fluid circuit to allow the highest pressure in any of the hydraulic lines of the machine fluid circuit or of the rail fluid circuit to generate the load required to retain fluid coupling between the fluid couplers.
• Thecoupling arrangement10 may have abracket switch30 to detect whether thework tool bracket14 carries a corresponding fluid coupler.Bracket switch30 may not permit fluid pressurisation of the rail fluid circuit when awork tool bracket14 carrying a corresponding fluid coupler is not detected. Thebracket switch30 may avoid inefficient coupling present in devices wherein fluid connections are established simultaneously at mechanical coupling of the machine bracket and the work tool bracket.
• Thecoupling arrangement10 may have aswitch32 to detect whether theactuators28 are fully retracted. The activation ofswitch32 determines whether the lockingdevice34 may be actuated to unlock thebrackets12,14 without the risk of potential damage to the fluid couplers and/orcouplers assemblies24.
• The industrial applicability of thecoupling arrangement10 as described herein will have been readily appreciated from the foregoing discussion.
• Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein.
• Where technical features mentioned in any claim are followed by references signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, neither the reference signs nor their absence have any limiting effect on the technical features as described above or on the scope of any claim elements.
• One skilled in the art will realise the disclosure may be embodied in other specific forms without departing from the disclosure or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the disclosure described herein. Scope of the invention is thus indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.

Claims (9)

1. A coupling arrangement for fluid coupling a work tool to a machine comprising:

at least one coupler assembly slideably mounted for coupling a machine fluid circuit and a work tool fluid circuit;

at least one actuator for retracting the at least one coupler assembly from a connect position to a disconnect position; and

a sensor to detect the position of the at least one actuator for actuation of a locking device.

2. A coupling arrangement according toclaim 1 wherein the sensor is arranged to actuate a valve to permit pressurize fluid to flow to the locking device when the at least one actuator is in the fully retracted position.

3. A coupling arrangement according toclaim 2 wherein the sensor is a solenoid switch.

4. A coupling arrangement according toclaim 2 wherein the sensor is a hydro mechanical switch.

5. A coupling arrangement according toclaim 4 wherein the coupler assembly is slideable in a cavity.

6. A coupling arrangement according toclaim 5 comprising a plurality of coupler assemblies slideable in a plurality of cavities.

7. A coupling arrangement according toclaim 6 comprising a plurality of actuators.

8. A coupling arrangement according toclaim 7 wherein the plurality of actuators are connected to a rail circuit.

9. A method of decoupling a worktool from a machine comprising:

providing at least one coupler assembly slideably mounted for coupling a machine fluid circuit and a worktool fluid circuit;

arranging at least one actuator to retract the at least one coupler assembly from a connect position to a disconnect position;

arranging a sensor to detect the position of the at least one actuator; and

activating the sensor when the at least one actuator is fully retracted to permit pressurised fluid to flow to the locking device for decoupling of the worktool.

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