WO2008138932A2

WO2008138932A2 - A coupler for the working arm(s) of an excavator or the like

Info

Publication number: WO2008138932A2
Application number: PCT/EP2008/055853
Authority: WO
Inventors: Jack Sky; Tony Mckeown; Damien O'connor; Gareth Baker
Original assignee: Geith Patents Limited
Priority date: 2007-05-14
Filing date: 2008-05-13
Publication date: 2008-11-20
Also published as: WO2008138932A3; IES20070351A2

Abstract

A system for coupling an attachment (3) to a power-driven arm (5) of a machine such as an excavator including: a coupler (2) for fitting to said arm and an interengaging mechanism (22, 23) arranged so as to couple the attachment to the coupler. The at least one interengaging mechanism automatically interengages utilising a catch which has a resiliently biased action as the coupler is moved into the mated position with the attachment by the arm. The coupler push-fits to the attachment.

Description

Title

A Coupler for the Working Arm(s) of an Excavator or the like Field of the Invention

The present invention relates to a coupler for the working arm or arms of an excavator or the like. In particular, the coupler of the present invention is suitable for coupling an attachment to said working arm. Such working arms include those often termed "sticks" or "dippers".

Of particular interest within the present invention are working arms which can be used with various attachments. Those attachments are generally working implements for moving material, and include buckets, forks, grabs, and powered implements such as rock hammers etc.

The present invention is directed to all types of machines, in particular vehicles, equipped with one or more working arms. In particular the invention is applicable to the type of machine known as a mini-excavator or mini-digger (generally from about 1 (metric) ton to about 10 tons), but can be applied to larger machines also. It includes machines which travel on tracks or wheels.

Background to the Invention

The present invention will be described with respect to the working arm of an excavator, such as a backhoe or the like, but it will be appreciated that the coupler of the present invention may be utilised with other working arms.

Many couplers, often referred to as quick release couplers, have been made for picking up and releasing various attachments to the working arm of a machine. Indeed the present Applicants have produced and developed many types of couplers. The coupler generally is employed intermediate (between) the attachment and the arm. It can allow the operator of the machine to more quickly attach and release an attachment than if they were to fit the attachment directly to the arm without a coupler. It is desirable that the operator has ease of fitting and ease of removal of the attachment utilising a coupler. Conversely, there is a danger that inadvertent operation of a release mechanism of the coupler will cause a serious accident, as the attachment (and any load on the attachment) may be inadvertently dropped from the arm. Serious injury and damage can result. Accordingly, remote systems come with the danger that an operator can inadvertently operate the release mechanism at an inappropriate time.

Control systems have therefore also been developed to ensure that the release mechanism of the coupler is not inadvertently operated. One type of coupler and a related control system are described in EP 1 318 242 A assigned to the present

Applicants. Both the control system and the coupler described in that patent application are designed to ensure that the coupler is not inadvertently dropped if the release mechanism is operated when it is unsafe to do so.

Notwithstanding the various couplers and control systems which are available, it is desirable to produce alternative versions.

Summary of the Invention

The present invention provides a system for coupling an attachment to a power-driven arm of a machine comprising: a coupler for fitting to said arm; at least one interengaging mechanism arranged so as to couple the attachment to the coupler (and thus to the arm), characterised in that the at least one interengaging mechanism automatically interengages utilising a catch which has a resiliently biased action.

The interconnection occurs automatically as the coupler is moved into its coupled position with the attachment. In this coupled position the attachment moves with the arm of the machine. This allows working operation of the attachment.

The system of the present invention is thus simple in construction yet highly efficient, and can be considered an automatic push-fit (or click-fit or snap-fit) coupling system for coupling an attachment to one or more power-driven arms of a machine (utilising a coupler). The system of the invention is thus adapted to automatically pick up an attachment (solely) utilising the interengaging mechanism (which push-click fits into place). The mechanism engages simultaneously with the movement of the coupler into the mated position with the attachment.

The interengaging mechanism will generally comprise a catch and a corresponding retainer which automatically interengage when brought into an interengaging position, thus coupling the attachment to the coupler.

One simple configuration is where the catch mechanism is on the coupler and/or the machine with the retainer on the attachment. Such a construction allows for the catch mechanism to travel with the machine. The present invention includes the alternative arrangement where the catch mechanism is on the attachment and the retainer is on the coupler. Also within the present invention is a configuration where there is more than one interengaging mechanism.

Generally, the interengaging mechanism will be of a type which is of a standard type allowing for interchange of various sizes or types of attachment to be worked by the machine.

The present invention thus provides a system for coupling an attachment to a power- driven arm of a machine simply by having the operator of the machine bring the at least one interengaging mechanism into an interengaging position. This can be done by movement of the working arm alone. It does not require any additional (separate) operation of any function within the coupling system of the invention.

The push- fit action will generally be based upon a resiliently biased action of a catch. No further action is required to pick up the attachment. Most existing couplers are only partially automated and require an operator instigated movement of a hydraulic ram to complete the pick up function of the coupler. The system of the invention can thus be considered a coupling system for coupling an attachment to the working arm of a machine which comprises a coupler and wherein the system is pre-configured for automatic pick-up of the attachment by the coupler by pushing the coupler into the coupled position with the attachment using the arm. Pick-up of the attachment is achieved by this action alone.

The interengaging mechanism, and in particular the catch and a retainer for the catch are in their respective engaging positions both before and after engagement occurs. Resilient movement of the catch against the biasing action occurs during engagement to allow the catch to move past the retainer and spring back to engage the retainer.

The coupler may be attached to one or more working arms of a machine where appropriate.

Any suitable interconnection mechanism can be employed and the skilled person will appreciate that many different arrangements are possible. Generally any catch/ retainer arrangement can be employed as long as the desired automatic interconnection is provided. Included therefore is any arrangement that allows interconnection so that the attachment may be picked up by the arm (utilising the coupler). For example one or more recesses may be formed to accommodate a catch. Two or more catch arrangements may be provided for example in an opposing configuration. The interconnection mechanism may comprise a plug and socket type arrangement - for example where the coupler has a male member which is insertable into a female member of the attachment or vice versa.

The coupler will generally comprise a body member adapted for coupling to the working arm, and the part of the interengaging mechanism which is on the coupler will be mounted on the body member for engaging with the part of the interengaging mechanism which is on the attachment.

For example the coupler can comprise a fixed engaging means (any suitable engaging means can be employed for example one or more retaining jaws or hooks) mounted on the body member for engaging a first one of a pair of coupling pins mounted on the attachment or accessory, and a movable engaging means mounted on the body member for engaging a second one of the pair of coupling pins of the attachment. Again any suitable moveable engagement means can be employed. Generally the moveable engagement means will comprise a catch which has a resiliently biased action. The moveable engagement means (for example the catch) may be employed to trap a pin or other retainer in a recess in the coupler. Opposing jaws may be provided which are adapted to engage with opposing pins on the attachment.

In one arrangement which is suitable for use with the two -pin arrangement conventionally used for coupling an attachment to a coupler, the coupler may comprise a body member adapted for coupling to the working arm, a fixed engaging means mounted on the body member for engaging a first one of a pair of coupling pins mounted on the attachment or accessory, and a movable engaging means mounted on the body member for engaging a second one of the pair of coupling pins of the attachment. In such an arrangement it is desirable that the moveable engaging means includes the catch mechanism. In such an arrangement the coupling pins form the retainer.

The force creating the resiliently biased action of the mechanism will generally be the minimum force applied at all times within the mechanism. The biasing force will generally be preset to a force which allows automatic engagement with, and pick-up of, the attachment.

The present invention thus provides a system for coupling an attachment to one or more power-driven arms of a machine comprising: a coupler for fitting to said arm; a first engaging means for engaging a first one of a pair of coupling pins mounted on the attachment; a second engaging means for engaging a second one of a pair of coupling pins mounted on the attachment; characterised in that at least one of the engaging means includes a catch mechanism which, when movement of the arm is employed to bring the respective engaging means into register with the respective pins, it automatically locks into place to engage the respective pin. In the context of the present invention, movement of the arm includes movement of any part of the arm, including hydraulic cylinders employed to power movement of the arm or to power movement of the coupler (and any attachment) relative to the arm.

A coupler of the invention allows remote operation that does not require that the operator move out of his/her working position on the machine, either during the engagement or the disengagement process for attaching/releasing the attachment. The process is thus fast and safe.

A further significant advantage of the present invention is that it can be installed without the necessity to take any hydraulic power from the hydraulic system of the machine. This has the advantage that hydraulic lines from the hydraulic system of the machine do not need to be run to the coupler.

The system is thus non-powered in the sense that it does not require any machine- powered movement of any of the component parts of the catch mechanism in order to couple to an attachment. The movement necessary to couple is provided by movement of the catch against the resilient bias. The catch initially moves against the resilient bias and then springs back to form the interconnection. The catch will generally be moved past a retainer which may take the form of a keeper for example a retaining or coupling pin. In particular no hydraulic power from a source external to the coupler is required.

This is quite an advantage over at least certain prior art couplers as it means fast, efficient and simple instalment of the system of the invention.

The attachment will be releasable by the system of the invention also. For example the interconnecting mechanism will generally be disengagable by moving the interconnection mechanism apart against the resiliently biased action of the catch. This could be achieved by having the system arranged to release the attachment solely by an opening action of the attachment. In one such arrangement, the system employs the weight of the attachment to effect disengagement, for example by positioning the attachment so that a moment such as a turning moment imparted by its own weight effects release. This will be achieved by having a softer catch action. The system could be configured with a harder catch action requiring greater force than that available from the attachments own weight, for example a force requiring the attachment to be leveraged away from the coupler such as by pressure exerted by the arm.

In order to retain the attachment on the arm during working operation of the attachment, it may be desirable to provide added safety against release of the attachment from the coupler to ensure that the attachment does not detach during such working operation. Most couplers have additional security to prevent the coupler detaching during working operation, such as additional catches/latch mechanisms which lock a pin within the engaging means .

One simple arrangement which achieves secure attachment, but which does not involve additional connections to the machine operating the arm is to employ a resiliently biased action which has both an active and a non-active state. By moving to a non-active state, the resiliently biased action is frozen so that the catch mechanism cannot move out of the engaged state. It will be appreciated that an active state is any state in which the resilient bias is functional to allow engagement and disengagement of the attachment, while the non-active state is a state in which the resiliently biasing action is negated sufficiently to prevent engagement and disengagement of the attachment (even during working operation of the attachment by the arm).

This means that the coupler of the invention can be fitted to the attachment by movement of the excavator arm alone. The engagement of the coupler and the attachment occurs when the locking mechanism operates. The non-active state of the resiliently biased action is then actuated automatically, or is actuated manually (though remotely) by the operator of the machine. This means that the attachment is securely fastened to the arm via the coupler. Normal working action of the arm and the attachment will not dislodge the attachment from the arm.

In one simple arrangement, the resiliently biasing action may be negated remotely for example by actuation of a remote switch. The negation of the resiliently biasing action may be achieved by (reversibly) bracing the biasing action. The catch mechanism can then be easily moved to its non-active state. In one simple arrangement the resiliently biasing action is provided by an expandable (including extendable) or compressible (including retractable) member. Examples include a compression or extension spring.

In one embodiment, the resilient bias is provided by a pressurised fluid system. This is a simple system which allows a desirable construction according to the invention to be achieved. In particular such a system will not require connection to any hydraulic supply of the machine. One configuration which may be employed is where the pressurised fluid system has an active state, in which hydraulic fluid is displaceable allowing resiliently biased action of the catch mechanism, and a non-active state in which hydraulic fluid is non-displaceable preventing resiliently biased action. Such a configuration can be easily set up with its own hydraulic fluid volume.

In order to negate the resiliently biasing action of such a hydraulic fluid system, a switching mechanism including for example a valve action may be utilised to switch the pressurised fluid system from the active to the non-active state and vice versa. In such an arrangement a remote operation of the switching mechanism can be provided. For example, an electrically powered valve actuator can be employed. In such a case the only potential connection required to the power of the machine may be to connect into an electrical supply of the machine. This would entail very little additional work to fit the system to the machine.

The resiliently biasing action may be provided by a member compressible or expandable under hydraulic fluid pressure for example a hydraulic spring arrangement. In such an arrangement the system may comprise an hydraulic fluid reservoir and a member compressible (including retractable) or expandable (including extendible) under hydraulic fluid pressure. For example an hydraulic accumulator may be employed. The member may be biased by the pressure of a gas or action of a spring.

The resiliently biasing action may be transmitted by an extendable cylinder arranged to transmit the resiliently biased action to the catch. In the hydraulic system of the invention it is desirable that the extendable cylinder is a hydraulic cylinder. For additional safety the system of the invention may further comprise a manual control for controlling the switching between the active and non-active states.

It is desirable that the non-active state is the default state of the system. This reduces the likelihood of inadvertent release of the attachment. In one suitable embodiment the active state is only activatable on a time-limited basis. In such an embodiment the non- active state is restored automatically after a set period. Furthermore, while the system is in the active state it is desirable to have an operator warning such as an audio and/or visual indicator of the active state. This means that, when used together, even if the operator were to inadvertently move to the active state while working the machine, the associated dangers are time limited and the operator is warned of the possibility that the system is not in the non-active state.

Generally the time limit will apply only to the removal procedure. There will be no time limitation to the attachment procedure.

In order to release an attachment, all that may be required of an operator is to activate the active state. The system of the invention is otherwise a system comprising a coupler which is automatically in a configuration to pick up or release an attachment by push- fit engagement or disengagement. Pick-up may be achieved without any operator activation.

In order to release the attachment, the operator will need to be prepared to release. For example the operator may have the attachment ready to force against the ground using the arm so as to create sufficient leverage to release the attachment from the catch mechanism. A time window of approximately 3 to 20 seconds is appropriate such as 5 to 15 seconds.

The control system may incorporate one or more sensors for sensing the relative position of the coupler to an attachment. For example a proximity sensor may be employed. In the dual coupling pin arrangement, the control may be set so that a first pin must already be in place (as detected by the proximity sensor) before the control will allow the active state to become functional. The audio and/or visual signal can be triggered by a signal from the proximity sensor as appropriate. The control may alternatively be set to allow the active state at all times that no attachment/pin is present.

In one arrangement at least one angular position sensor is employed. The angular position sensor can be employed as a control to allow release of the attachment only in certain angular dispositions of the attachment relative to the arm. For example the angular position sensor can be employed to allow the active state to be activated only when the attachment and/or coupler is in a position relative to the arm so that even if released it will not fall from the arm. For example when one of the engagement means will still retain the attachment from falling. Suitable positional sensors include a tip-over switch (desirably an electrical one).

The positional sensor and the proximity sensors can be employed together. For example the proximity sensors may be used to indicate a condition of no attachment being present (in which case it can allow the active state of the resiliently biased mechanism to become operable irrespective of the relative position of the coupler to the arm). In such a case the proximity sensor(s) can deactivate or simply override the positional sensor (which means that with no attachment in place the coupler can remain in the active state for engagement). This configuration means that the operator does not have to instigate any initial action to ensure the coupler is in its configuration to pick-up an attachment. On the contrary when the operator wants to release an attachment the proximity sensors indicate the condition that an attachment is present and the signal from the angular position sensor is the determining control on whether or not the attachment is to be released. The angular position control is desirably used in conjunction with the time- limited mechanism so that even though the correct position of the attachment is indicated there is still a time-limited window of opportunity to release the attachment. The non-active state of the resiliently biasing mechanism may thus be the default state which is instigated when the condition is that an attachment is present. The active state may be the default state when the condition is that an attachment is not present. When an attachment is present the active state may only be activated on a time limited basis when the angular disposition of the coupler/attachment is such that the attachment will not fall from the coupler.

The system of the invention may further comprise a control box, for fitting proximate an operator's position on the machine to allow the catch mechanism of the invention to be operated remotely. Such a control can include also audio and visual signals.

The invention relates also to a machine having a working arm and a system of the invention arranged to couple an attachment thereto.

The invention relates to a system substantially as described herein and as shown in the accompanying drawings.

Brief Description of the Drawings

Figures 1 - 3 are a sequence of schematic representations each showing a side view of a coupling system according to the invention fitted to a backhoe arm of an excavator being brought into alignment by the arm to pick up an attachment; - in Figure 1 the arm is employed to align the coupler to the attachment;

- in Figure 2 the coupler has engaged one pin on the attachment and

- in Figure 3 the coupler is fully coupled to the attachment.

Figure 4 is a side sectional view of a coupler system of the present invention; Figure 5 is a part cut-away side perspective view of the coupler system of Figure 4. Figure 6 is a side sectional view of a further embodiment of a coupler system of the present invention in an attachment-working configuration;

Figure 7 is a side sectional view of the coupler system of Figure 6 in an attachment- releasing configuration; and Figure 8 is a schematic representation of a control system which may be incorporated into a system of the present invention.

Detailed Description of the Drawings Figures 1-3 show a sequential sequence whereby a system of the present invention is employed for coupling an attachment to a power driven arm of a machine. More particularly, Figure 1 shows a power driven arm 5, which in the embodiment is a dipper arm of an excavator. The coupler 2 has a body member 4 and is pivotally attached to the dipper arm 5 by a coupling pin 8. A linkage comprising link portions 7a, 7b which are pivotally attached to each other by pin 10 and respectively pivotally attached to the coupler 2 and dipper arm 5 by pins 9 and 11. A hydraulic ram 15 (shown only in part) powers the linkage which in turn effects rotation of the coupler about pin 8. The hydraulic ram 15 is often referred to as the curling ram. Such an arrangement is a conventional one for attaching a coupler to the working arm of a machine. In this embodiment, an attachment takes the form of a bucket 3.

The system of the invention comprises an interengaging mechanism which is arranged to couple the bucket 3 to the coupler 2. In the embodiment the bucket 3 is provided with two coupling pins 18,19. The coupling pin 18, because of the possibility of attaching it directly to the dipper arm, is often referred to as the dipper pin. The pin 19 may be directly connected to the linkage 7b, and accordingly is often referred to as the link pin. The coupler 2 is provided with means for attaching to the pins 18, 19. In particular the coupler 2 has a fixed engaging means in the form of a jaw or hook 22 for retaining pin 18. It additionally has a catch 23, which, under a resiliently biased action, is adapted to automatically push fit to pin 19. This happens automatically in the sequence shown in Figures 1-3. No further (later) sequential movement of any of the parts on the coupler is required in order to engage the attachment on the coupler.

Figure 1 is a position where the operator of the machine has aligned the coupler 2 for engagement with the bucket 3 utilising the arm 5. Figure 2 shows the next step in the engaging sequence whereby the arm 5, and in particular the hydraulic ram 15 has been employed (following the movement indicated by arrows in Figure 1) to bring the coupler into register with the attachment, and more particular by bringing the jaw 22 into register with the pin 18. The jaw 22 and the pin 18 are then interengaged. The arm, and in the embodiment shown the hydraulic ram 15, is then employed to interengage the catch 23 with pin 19 - the position shown in Figure 3. This is done by moving the coupler so that the catch 23 abuts, then moves sufficiently (against the biasing action and under urging force from the pin 19) to pass the pin 19 and to spring back into place engaging behind pin 19. The pin 19 thus acts as the retainer for the catch

23.

The interconnection thus occurs automatically as the coupler is moved into its coupling position with the attachment by movement of the arm. As can be seen from Figure 3, the bucket 3 is immediately available to be picked up by the arm 5. The bucket can then be operated by the arm 5 in the same way as if the bucket were directly attached to the arm 5 and the linkage 7a/7b.

Figure 4 shows the sectional view of the coupling system 1 of the present invention. The attachment 3 has been omitted from the Figure for the sake of clarity. Furthermore, the system is shown in the engaged position. Similar reference numerals have been employed for similar parts to those shown in the earlier Figures.

In the embodiment shown in Figure 4 the resilient biasing action on the catch 23 is provided by a cylinder 30 which includes an in-built resiliently biasing action. The cylinder territory has two concentric chambers, an inner (piston) chamber 31 and an outer (pressurising) chamber 32. It will be appreciated that relative positions of these chambers is not critical and they could be provided side by side, one on top of the other etc. Located within the inner chamber 31 is a piston 35 which has on its end 36 protruding from the cylinder housing 37 a head formed in the shape of latch 23. The latch 23 takes the form of a wedge shape. The latch can be integrally formed with the piston or as in the present embodiment, be a separate component. A fluid, in the embodiment hydraulic oil 33, partially fills both the inner chamber 31 and the outer chamber 32. A different fluid, in the embodiment a gas 38, occupies the remainder of the available space in the outer chamber 32. An annular sliding divider in the form of a sealing ring 40 provided with seals 41 separates the gas from the oil. The gas is permanently sealed in outer chamber 32. Oil within outer chamber 32 is in fluid communication with inner chamber 31 and vice versa. Fluid communication between the chambers is governed by a valve 50 which has a communication port 51 for communication with the inner chamber 31 and a communication port 52 for communication with the outer chamber 32. A series of annular seals 45-47 about the piston 35 prevent oil from escaping out of the inner chamber along the piston 35. A guide 60 for the latch 23 is also provided. The guide 60 guides the movement of the piston 35 and its associated latch 23. In particular the guide 60 acts to restrict any rotational moment of the latch/piston about a longitudinal axis of the piston and in the embodiment takes the form of two opposing (upper and lower) slide plates 60, 61 which guide the action of the piston/latch 35/23.

The valve 50 controls the active and non-active states of the resiliently biasing mechanism as will be now described. The active state is where the resiliently biasing mechanism is operative. The non-active state is where the resiliently biasing mechanism has been locked against the resilient motion.

In the active state, the valve 50 is open and oil can flow from the inner to outer chamber and vice versa. Motion against the biasing action of the biasing mechanism is in the embodiment (retractive) motion of the piston 35 in the direction indicated by arrow R. Resistance to movement in the direction of arrow R is caused by: oil 33 being displaced by the internal piston end or tail 39, causing oil to displace from inner chamber 31 through port 51 into valve 50 and out through port 52 into chamber 32; causing annular dividing ring 40 to compress gas 38; which compression imparts a reactive resilient force on the ring. The resilient reactive force on the ring is transmitted through the oil to the piston and thus to the catch 23. The configuration is such that the outer chamber 32 acts as a resilient biasing mechanism for the latch when the valve 50 is open.

The resilient bias is of sufficient strength to allow push fit engagement of the latch 23 with the pin 19. In particular, as shown in the sequence of Figures 1-3, latch 23 is brought to mate with pin 19 while the latch 19 is in its engaging position. This means that latch 23 and in particular a lower surface 24 thereof abuts the pin 19. Abutment of the catch 23 against the pin creates a resistance force which causes the latch 23 and thus piston 35 to move in the direction of arrow R. The surface 24 being oblique to the pin allows the catch 23 to be more easily pushed past the pin 19. Movement in direction R (with valve 50 open) causes oil 33 in the inner chamber 31 to be displaced into outer chamber 32 causing compression of the gas 38 by ring 40. The catch 23 retracts sufficiently on being urged against pin 19 to move past pin 19 and then springs back (in the direction of arrow F) into the engaged position shown in Figure 4. The pin 19 is now firmly engaged. As pin 18 has already been engaged in jaw 22 the attachment is now automatically picked up by the coupler simply by bringing the two into the mated position. It will be appreciated that the minimum resistance to movement experienced by the catch is that applied by the resiliently biasing action.

Once the attachment is in place it is desirable to utilise the non-active state of the resilient biasing mechanism.

Closing of valve 50 switches the system to the non-active state. Closing of the valve interrupts (oil) flow from the inner to the outer (pressurising) chamber. This means that oil trying to displace due to force on the catch/piston in the direction of arrow R no longer can displace to the outer chamber 32 and experience the resiliently biasing action. Instead the oil is now retained within the inner chamber 31. This means that there is substantially increased resistance to movement in direction of arrow R, so much so that the piston/catch are effectively locked against any substantial movement in that direction. The valve 50 thus negates the resiliently biasing action, as the valve braces the piston/latch against movement by isolating the resiliently biasing action. Opening of the valve 50 switches the system to the active state again. It is to be noted that if the valve 50 is of a certain type, for example a reverse energised valve, it can, even when closed, allow pressurised fluid from the pressurising (outer) chamber into the piston/ram (inner) chamber. This allows the pressurising chamber to move the latch, for example to take up slack due to wear or movement, even if the valve is closed. It will also help to compensate for loss of pressure for example due to leakage from the cylinder. A control system which inter alia operates the valve 50 will be described below.

It will be appreciated that the system of the invention is very convenient for the working arm of a machine. This is because the mechanical power to engage the catch is within the system, for example on the coupler, so that connection to a power source of the machine for effecting movement of the catch is not required. Conventional couplers require such connection. The only connection from the machine that will be generally used with the present invention to power movement of any part of the system will be a connection for remotely operating the valve. This will generally be an electrical connection. It will be appreciated that no movement of any catch etc. is effected by such remote connection and none is required, as the attachment is already coupled to the coupler. Instead, the remote connection simply negates (isolates) the resiliently biasing action.

To disengage the coupler 2 from the attachment, the valve 50 is opened again and sufficient force is created between top surface 25 of catch 23 and pin 19 to urge the catch/piston to retract in the direction of arrow R (against the resiliently biasing action) to move the catch past the pin 19. The attachment is then released from pin 19. Complete removal occurs when pin 18 is also disengaged. This is easily achieved when release of pin 19 has already occurred. Resilient biasing to allow engagement and then locking of the resilient biasing action to prevent disengagement is a simple but very effective mechanism of the invention.

The system is configured so that the resiliently biasing action is sufficient to allow such interengagement and disengagement. Generally the resiliently biasing action can be preset to a desired level from "hard" to "soft". In any event it is desirable that the minimum resiliently biasing force employed is sufficient to pick up an attachment.

In particular, the active state can be tuned for an attachment to be worked. One desirable arrangement is where a predetermined proportion of the weight of the attachment must be on the resiliently biased catch mechanism before release occurs. For example, the resilient bias could be set so that if greater than 50% of the weight of the attachment is on the catch mechanism release will occur. Various settings are possible here including weight thresholds greater than 60%, for example greater than 70% of the weight. The weight distribution of the attachment can be varied by varying the position of the attachment relative to the arm. Curling of the attachment relative to the arm can thus be used to effect release.

Figure 5 shows a perspective view of the coupler of Figure 4 with some components removed to allow a better view of the internal arrangement of the coupler. The cylinder 30 can be seen mounted on the coupler 2. The valve 50 is mounted to the cylinder 30. As can be seen from Figure 5, the latch 23 comprises two separate head portions 26 and 27 which are spaced apart but mounted together through the same connection 43 to the piston 35. Upstanding bracket 12 comprises apertures 14 for retaining pins for mounting the coupler to the arm of a machine.

Figure 6 shows a side sectional view of an alternative embodiment of the present invention. In Figure 6 the parts similar to those used in Figures 4 and 5 are given similar reference numerals. There are two main distinctions in this embodiment from the earlier embodiment described. Firstly, in this embodiment, the resiliently biasing mechanism is not incorporated into the cylinder 30. Instead, it is provided by an external device, in this case an accumulator 55. Secondly, sensors in the form of proximity sensors 70, 71 are provided (for detecting the presence of the pins 19,18 respectively). A further distinction includes the fact that the cylinder 30 is a single- acting ram. In a single acting ram, oil 33 is prevented from moving past the end 39 of the piston 35 to any substantial extent. Seals 45-48 are provided on the piston 35 to prevent escape of oil past the piston 35. In this embodiment, a connecting conduit in the form of the pipe 53 connects an oil chamber 63 in the cylinder 30 with and oil chamber 64 in the accumulator 55. As can be seen from the drawings, the valve 50 is provided on the conduit between the two chambers. The valve thus regulates movement of oil between chambers 63 and 64 analogous to the manner in which it regulates movement of oil between inner and outer chambers 31,32 of the previous embodiment. In the accumulator 55 a dividing member 56 (provided with seals 57) separates the oil from a spring 58 also located within the accumulator. The resiliently biasing action is provided by the resilience of the spring 58 acting against the dividing member 56. Such action is analogous to the compression of the gas 38 by the dividing ring 40 of the previous embodiment. A spring mechanism is thus a mechanism that can be used (instead of a volume of gas as in previous embodiments) to impart the desired resilient bias.

Figure 6 shows the system in the non-active state with the valve closed and the piston/latch in the engaged position engaging the pin 19 (pin 18 is also engaged). Figure 7 shows an active state of the embodiment of Figure 6 with the pin/latch retracted by displacement of oil into chamber 64 resulting in the movement of the dividing member 56 and compression of spring 58. It will be appreciated that the present invention will operate even where a pin is worn, as the position of the pins will be adjusted by the resiliently biasing action to abut the pin. Furthermore, the system will also operate even where a pin has been found with material which has adhered to the pin.

Figure 8 shows a schematic representation of a control system 80 which may be used with the coupling system of the present invention. The control system 80 includes a control box 81 which has an electrical current feed from a battery 87 of the machine through wiring 86. The control panel also has a required earth through connection 85. The proximity sensors 70, 71 (illustrated schematically) are also connected to the control box 81. An angular sensor in the form of a tilt switch 90 also connects into the control box. A further control line comprising an electrical connection 88 runs from the control box to the valve 50. The cylinder 30, the valve 50, and the accumulator 55 are all illustrated schematically in this drawing. Figure 8 will be used to describe the control of the valve 50. It will be appreciated that control of the valve 50 switches the coupler between the active and non-active states as described above.

The control system of the present invention has the ability to indicate three different attachment states to the operator of the machine. The first state is the unattached state, the second stage is the partially attached state and the third stage is the fully attached state. These states are shown respectively in Figures 1-3. In the unattached state, that is when the coupler is empty, a signal such as an audio or visual signal for example a green LED light indicates that the device is ready for an attachment (valve 50 is open). The operator must then move the arm of the vehicle so that the coupler can be mated with the attachment. Once the partial attachment position of Figure 2 is reached, a signal can be given to the operator that partial attachment has been achieved. For example an orange/amber light signal and/or an audible warning signal may be employed. It is desirable to have both so that the operator is alerted should the attachment be only partially attached at any stage.

The system knows that pin 18 has been attached by virtue of proximity sensor 70 which is connected to the control panel 81 and which can detect the proximity of pin 18. Following partial attachment, the operator then operates the arm, for example to curl the coupler so that the latch 23 automatically push fits to pin 19. Again an audio and/or visual signal such as a red LED may be used to indicate when this position is achieved. The proximity sensor 71 senses the presence of pin 19. The non-active state of the resiliently biasing mechanism (closing valve 50) is automatically executed by the control system (a signal through line 88 to the valve).

This means that all the operator has to do is offer the coupler to the attachment and position them for mating and then move them into the mated position. The system will then automatically indicate the sequence of positions from unattached to attached and then automatically engage the non-active state of the resiliently biasing mechanism. The operator does not need to operate any control other than a control that controls movement of the arm.

In the embodiment at least one angular position sensor in the form of tilt switch 90 is employed. The tilt switch 90 is employed as a control to allow release of the attachment only in certain angular dispositions of the attachment relative to the arm. For example the tilt switch 90 can be employed to allow the active state to be activated only when the attachment and/or coupler is in a position relative to the arm so that even if release is activated an attachment will not fall from the arm. For example when pin 18 will be held under gravity in jaw 22.

The tilt switch 90 and the proximity sensors 70,71 can be employed together. For example the proximity sensors may be used to indicate a condition of no attachment being present. Thus a "no-attachment" condition can be used to allow the active state to become operable irrespective of the relative position of the coupler to the arm. This means that, with no attachment in place, the coupler can change to the active state for engagement when the dipper pin 18 is engaged in the hook 22. This configuration means that the operator does not have to instigate any initial action to ensure the coupler is in its configuration to pick-up an attachment.

For example an angular position sensor may employ a tilt switch such as an accelerometer which is influenced by gravity. The angle of the coupler (and thus the attachment) to the ground can be determined by the tilt switch. The system can thus be set to allow release of the attachment only in certain angular dispositions relative to the ground (those positions in which the attachment will not fall under gravity).

Similarly the proximity sensor(s) can be employed to automatically engage the non- active state once an "attachment present" condition is indicated. This means the active state is the default state prior to engagement, and then immediately after engagement the non-active state is automatically activated. The non-active state is thus the default position when an attachment is present.

On the contrary when the operator wants to release an attachment the proximity sensors 70,71 can be utilised to provide a signal which can indicate the condition that an attachment is present and the signal from the tilt sensor 90 is the determining control on whether or not the attachment is to be released. In the embodiment the tilt sensor senses the degree of curl of the coupler relative to the vertical. The tilt control is used in conjunction with the time-limited mechanism so that even though the correct position of the attachment is indicated there is still a time-limited window of opportunity to release the attachment. The non-active state of the resiliently biasing mechanism is thus the default state which is instigated when the condition is that an attachment is present. The active state may be the default state when the condition is that an attachment is not present.

When an attachment is present the active state may only be activated on a time limited basis when the angular disposition of the coupler/attachment is such that the attachment will not fall from the coupler. No button needs to be pressed by the operator to have the coupler in the active state for engagement of an attachment because proximity sensors 70,71 signal the attachment procedure.

The release sequence is the reverse of the above. In the release sequence, the operator may operate a time limited release button on the control panel which will temporarily (for a period of a few seconds) switch the resiliently biasing mechanism into the active state, in which state the attachment can be removed as described above. It returns the system to the non-active state when the period has elapsed. Once the attachment is partially disengaged, the appropriate signals will be given and when the attachment is fully disengaged that signal will be given also in the reverse sequence of that described immediately above. The release sequence is the reverse sequence illustrated by the sequence from Figures 3 to Figure 1. An audible signal may also be given to indicate that the time release is operative.

The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Claims

1. A system for coupling an attachment to a power-driven arm of a machine comprising: a coupler for fitting to said arm; at least one interengaging mechanism arranged so as to couple the attachment to the coupler, characterised in that the at least one interengaging mechanism automatically interengages utilising a catch which has a resiliently biased action.

2. A system according to Claim 1 wherein the interengaging mechanism is disengagable utilising the catch mechanism.

3. A system according to Claim 1 or Claim 2 wherein the resiliently biased action has both an active and a non-active state.

4. A system according to Claim 3 wherein the non-active state is one in which the resiliently biased action is negated.

5. A system according to any preceding claim wherein the resilient bias is provided by an expandable or compressible member.

6. A system according to any preceding claim wherein the resilient bias is provided by a mechanism on the coupler.

7. A system according to any preceding claim wherein the resilient bias is provided by a pressurised fluid system.

8. A system according to Claim 7 wherein the pressurised fluid system has an active state, in which hydraulic fluid is displaceable allowing resiliently biased action of the catch mechanism, and a substantially non-active state in which hydraulic fluid is non-displaceable preventing resiliently biased action.

9. A system according to Claim 8 wherein valve action is utilised to switch the pressurised fluid system from the active to the non-active states.

10. A system according to any one of Claims 6 to 9 wherein the resilient bias is provided by a member compressible or expandable under hydraulic fluid pressure.

11. A system according to Claim 10 wherein the system comprises an hydraulic fluid reservoir which includes a member compressible or expandable under hydraulic fluid pressure.

12. A system according to Claim 10 wherein the member within the reservoir is biased by the pressure of a gas or action of a spring.

13. A system according to Claim 11 or 12 wherein the reservoir is on the coupler.

14. A system according to any preceding claim wherein an extendable cylinder is arranged to transmit the resiliently biased action to the catch.

15. A system according to any one of Claims 3 to 14 further comprising a control for controlling switching between the active and non-active states.

16. A system according to any one of Claims 3 to 15 wherein the non-active state is a default state of the system.

17. A system according to any one of Claims 15 to 17 wherein the control includes a time limitation for the active state.

18. A system according to any preceding claim further including at least one sensor for sensing the relative position of the coupler to the attachment.

19. A system according to Claim 18 wherein the sensor is a proximity sensor.

20. A system according to Claim 18 or 19 wherein the sensor detects the presence or absence of an attachment.

21. A system according to Claim 20 wherein the sensor is utilised to activate the non- active state when an attachment is present.

22. A system according to Claim 20 or Claim 21 wherein the sensor is utilised to activate the active state when an attachment is absent.

23. A system according to any one of Claims 18 to 22 further comprising a sensor for detecting the relative angular position of the coupler and/or attachment to the arm.

24. A system according to Claim 23 wherein the relative angular position of the coupler to the arm must be a position in which the attachment will not fall from the coupler, before the active state can be activated for release of the attachment.

25. A system according to Claim 24 wherein the active state is activatable for a time limited period.

26. A system according to any one of Claims 15 to 25 further comprising a control box for fitting proximate to an operator's position on the machine.

27. A system substantially as described herein with reference to and as illustrated in the accompanying drawings.