IES20020341A2 - Control system for a coupler for coupling an attachment to a hydraulically operated arm of an excavator - Google Patents

Abstract

A control system for controlling the release of an attachment from a coupler coupling the attachment to a hydraulically operable arm of a machine, operated by a pressurised hydraulic system. The coupler has a coupler body adapted for coupling to the arm. An engagement mechanism on the coupler body releasably engages the attachment. The control system incorporates a safety control for preventing actuation of the engagement mechanism from an attachment engaging position to an attachment release position if the hydraulic pressure in at least one selected part of the hydraulic system does not exceed a threshold value. The system prevents accidental release of the attachment to avoid injury/damage which might be caused if the attachment were released in a position where it could fall from the arm. <Figure 7>

Description

Control System for a Coupler for Coupling an Attachment to a Hydraulically Operated Arm of an Excavator.

Field of the Invention The present invention relates to a control or operating system for controlling/operating a coupling device for coupling an attachment to a or the hydraulically operated arm(s) of an excavator. The term “excavator” as used herein with reference to the present invention includes diggers or similar earth working apparatus, and usually in the context of a self-propelled vehicle having wheels or sectional tracks (“caterpillar tracks”) on which it moves.

Background to the Invention Coupling devices for coupling accessories to a hydraulically operated arm of excavators are well known. These devices typically are used to attach different types of attachments for example to a dipper arm of such apparatus, for example to attach different sizes of buckets or a jack hammer or other such implements to the excavator.

The coupling device (also commonly referred to as a “coupler” or “quick hitch”) is usually releasably attachable to both the (dipper) arm of an excavator and the attachment. The coupler is adapted for attachment to the arm and normally would remain on the arm and be utilised to interchangeably work different attachments on the arm for example by attaching the connecting pins on the attachment or any other suitable means. The coupler is normally attached to the dipper arm by attachment means for example by means of two removable pins which pass through both the arm and the coupler engaging them to each other. The coupler includes a releasably engageable attachment means to attach the accessories which is typically provided by engagement members (normally an opposed pair of members) on the coupling body which can releasably engage such attachments. The engagement means most usually is formed by for example a set of hooks typically at least two hooks. Typically at least one of the IHT CL —A J IE 0 2 Ο ϊ 4 engagement members is adapted so that its position can be moved so that the spacing between the two engagement members aligns with the coupling pins of the attachment when the attachment is to be locked in position. The engagement members are also adapted so that on full engagement the coupling pins are locked in position so as to couple the attachment to the dipper arm of the excavator so that the attachment may be worked by the arm (as if directly attached to the arm). On disengagement the engagement members can release the coupling pins from the locked position to enable removal of the attachment from the coupler. The operation of the engagement members of the coupler are typically controlled by a hydraulic (control) ram.

A hydraulic supply from the excavator to the hydraulic control ram for the coupler is controlled by the operator of the machine operating one or more controls.

To avoid the inadvertent or accidental release of the attachment by releasing the grip of the coupler on the attachment, manually and electrically operated locking systems have been incorporated into the coupling system to ensure the attachment is only released when it is desired to do so. It is a danger that the control ram for the adapter could inadvertently be activated to release the attachment.

Mechanical locks have been provided on the coupler which require that the operator of the machine (or another person) has to manually release the mechanical lock. On the other hand in order to be effective the operator must first engage the mechanical lock something that is not always done. Alternatively a hydraulically operated lock is provided. This lock must also be engaged by the operator.

Known electrical control systems for the release of the coupler can be operated remotely from the cab of the excavator by its operator. However there is a danger with such systems that they are accidentally operated (e.g. by accidentally hitting the remote release control) and thus release the attachment from the excavator. It will be appreciated that the release of the attachment when it is not intended to, causes a potential hazard as the attachment may fall off the coupler of the arm. If the (dipper) arm is above ground level this could potentially cause harm. In other positions the attachment might become stuck in some earth or cause damage to the dipper arm.

There is therefore a need for an alternative control system/mechanism for such couplers that addresses some of the problems discussed above.

Object of the Invention It is an object of the present invention to provide an alternative control system for controlling the release of an attachment for the arm(s) of an excavator or the like from a coupler which couples the attachment to the arm(s).

Summary of the Invention The present invention provides for a control system for the control of the release of an attachment which overcomes at least certain of the disadvantages of the present invention.

The present invention provides a control system for controlling the release of an attachment from a coupler coupling the attachment to a hydraulically operable arm of a machine such as an excavator, the hydraulically operable arm being operable by a pressurised hydraulic system of the machine the coupler having: a coupler body adapted for coupling to the arm; an engagement mechanism, arranged on the coupler body, for releasably engaging the attachment, the engagement mechanism being actuatable to move the engagement mechanism between a first attachment engaging position in which the engagement mechanism engages the attachment securely for working of the attachment by the arm and a second attachment release position in which the attachment is removable from the coupler; the control system incorporating a safety control for preventing actuation of the engagement mechanism from the attachment engaging position to the attachment release SE02 034 position if the hydraulic pressure in at least one selected part of the hydraulic system does not exceed a threshold value (and below which threshold value the safety control prevents actuation of the engagement mechanism to the release position). This is a simple yet effective way of ensuring that the attachment is not accidentally releasable at any time. It will be appreciated in this context that the threshold value will be relatively high, in particular it is desirable that the threshold value exceeds that normally required to operate the engagement mechanism.

Where the machine has a dipper arm and in particular a number of hydraulic cylinders controlling movement of that arm, one can choose one or more places in the hydraulic system which are suitable for selection to determine if the pressure there exceeds the threshold value. A typical threshold value would be about one third of the overall system pressure.

One particularly desirable arrangement of the machine has a hydraulic ram which moves the coupler relative to the arm (normally acts between the coupler and the arm) and desirably the threshold value is measured from a hydraulic feed to that hydraulic ram. It will be appreciated that hydraulic rams may have two feeds one to outstroke (extend) the ram, the other to instroke (retract) the arm. In the present invention it is desirable that it is the pressure in the outstroke feed for the hydraulic ram that moves the coupler relative to the arm (the “crowd” ram) that is used by the control system. The pressure threshold could be exceeded even if the crowd ram were not at maximum outstroke for example if an attachment (on the coupler) were stuck into the ground etc. However this would involve a very conscious effort on the part of the operator of the machine and in any case the attachment is in a safe position even if it were to be fully released from the coupler.

It will be appreciated that taking the pressure measurement from the crowd ram can be used to ensure the coupler, and thus the attachment, is in a desired relative position to the arm.

Accordingly the present invention also provides a control system for controlling the release of an attachment from a coupler coupling the attachment to a hydraulically operable arm of a machine (for example an excavator), the coupler having: a coupler body adapted for coupling to the arm; an engagement mechanism, arranged on the coupler body, for releasably engaging the attachment, the engagement mechanism being actuatable to move the engagement mechanism between a first attachment engaging position in which the engagement mechanism engages the attachment securely for working of the attachment by the arm and a second attachment release position in which the attachment is removable from the coupler; the control system incorporating a safety control for preventing actuation of the engagement mechanism from the attachment engaging position to the attachment release position if the coupler is not in one or more predetermined positions relative to the arm. If an attachment is engaged on the coupler (so as to be workable by the arm) then the control system ensures that the release position is not selectable if the attachment is not in one or more predetermined positions relative to the arm.

The present invention thus assures that the release position of the coupler may only be selected (the attachment on the coupler may only be released) in certain positions or in a range of such positions. This means that an attachment on the coupler is much less likely to be released from the coupler during use of the attachment.

The control system will usually include at least one of hydraulic controls and electrical controls. In the preferred embodiments of the invention it includes both. The control system is suitably adapted for (retro-) fitting to an excavator. Alternatively it may be supplied already fitted to the machine.

The system of the present invention may be used with any type of known coupler which has the engagement system described above. Desirably the coupler is of the type sold by Geith International. Such a suitable coupler is described in Irish patent application no. S2000/0909 filed on 13 November 2000 and Irish Patent application no. S2001/1047 filed on 6 December 2001 of Geith Patents Limited. The latch mechanisms described therein are mechanical locks for preventing the inadvertent release of an attachment for example a bucket. The system of the present invention does not require such latches to be present.

It is desirable that the control system is remotely operable i.e. as distinct from the manually operable systems, operable at a position remote from the coupler. Desirably the remote position is from the operator’s operating position which will normally be within a cab of the machine.

In one preferred embodiment of the present invention, the position(s) (orientation(s)) of the coupler (and attachment) relative to the arm in which the safety control does not prevent actuation of the engagement mechanism to the release position is a position in which an attachment is removable from the coupler but in which the attachment is not (automatically) completely disengaged from the coupler. Desirably the relative position(s) of the coupler (and attachment) and the arm in which the safety control does prevent actuation of the engagement mechanism to the release position is a position in which an attachment is automatically completely disengageable from the coupler. In the latter positions) if the arm (and thus the attachment) of the excavator were at any significant height above ground level, the attachment (and any of its load) would be completely released by the coupler and fall from the arm, potentially landing on top of people or property causing injury/damage.

In other words the relative position(s) of the arm and the coupler at which the release of the attachment is allowed by the safety control are those in which the position to which the attachment is releasable is a partially disengaged position. The attachment can then be fully removed from the coupler if desired, for example by further moving the arm. Suitably said partially released position is one which holds an attachment from falling from the coupler under gravity.

For example in certain embodiments the coupler may be adapted to grip the attachment at two or more locations on the attachment, for example to grip two retaining pins on the I£02bs attachment. In such embodiments it is desirable that the coupler grips the attachment (i.e. the coupler and the attachment remain interengaged) at least one of said positions. In other words the attachment is released from the working position and releases to a release position which allows for removal of the attachment, but the attachment is not automatically dropped by the hitch.

For example with the coupler described in Irish patent application nos. S2000/0909 and S20011047 above a pair of engagement members are provided on the coupler for engaging with the attachment (in particular respectively engaging each of a pair of pins provided on the attachment). The present invention when used in conjunction which said engagement members allows the release of the attachment at a position at which at least one of said engagement members still engages with the attachment. It is particularly desirable that the partial release of the attachment achieved by the present invention holds the attachment from falling under the force of gravity.

In particular it is desirable that at least one of said engagement members are hookshaped and remain interengaged with the attachment (to hold the attachment to the coupler) even though the engagement mechanism has been moved to the release position.

Desirably the engagement mechanism comprises a hydraulic ram or other such mechanism ( for example a screw-drive mechanism) which is actuatable to move the engagement mechanism between the engaging and release positions. Desirably the hydraulic arm opens at least one side of opposing grips which close to grip the attachment for working thereof on the arm, and which open to at least partially engage the attachment.

In one particular construction of the system of the present invention the safety control prevents the flow of hydraulic fluid to the hydraulic ram of the engagement mechanism whenever the relative positions of the arm and the attachment are at a non-desirable release position for example positions in which the movement of the engagement mechanism to the release position would automatically completely disengage the attachment from the coupler.

It will be appreciated by those skilled in the art that the position of the arm could be sensed and the information about the position employed, for example in a logic circuit to determine if the engagement mechanism should be actuated or not. The present inventors however propose a simpler solution.

With certain couplers a position at which the engagement mechanism can be actuated to move to the release position yet not cause the attachment to automatically disengage from the coupler is a position in which a hydraulic ram (in particular the “crowd ram”) operating the attachment (by operation of the coupler) is in certain positions, for example fully extended or substantially fully extended. For example the attachment could be a bucket attached by the coupler to the dipper arm of an excavator and a position at which the bucket could be released from the engaged (working) position but still held by the coupler is a position in which the bucket is fully intumed (curled or folded in) toward the arm. Another way of determining the position(s) at which the safety control prevents release is to consider the angular position of the coupler relative to the arm.

Previously the hydraulic arm which operates the engagement means can be activated and fed to the ram in the coupler regardless of the angular position of the coupler or quick hitch. As pointed out this operation is a safety hazard, as in the instance where there is an attachment fitted to the coupler and the coupler is orientated in a position where the open jaw of an engagement member is facing downwards. If the coupler ram is activated by pressure from the excavator to in-stroke the ram and release the attachment pins from being locked in position, then the attachment could possibly fall out of the coupler.

In one embodiment of the invention a sensor which detects the relative position of the coupler and the arm is a pressure sensor. For example the pressure in a hydraulic supply line can be sensed and employed to control the operation of the coupler, more ΪΕΟ2 034 specifically preventing actuation of the engagement mechanism from the attachment engaging position to the attachment release position if the attachment is not in one or more predetermined positions relative to the arm. In one preferred embodiment the control system incorporates a pressure sensor in (fluid) communication with a hydraulic line of a machine to which the control system is fitted; the pressure sensor controlling the actuation of the engagement mechanism from the attachment engaging position to the attachment release position if the attachment is not in one or more predetermined positions relative to the arm. More particularly the pressure sensor could be incorporated in a pressure sensitive valve in (fluid) communication with a hydraulic feed line to a hydraulic cylinder for actuating the engagement mechanism. In this latter arrangement direct control of hydraulic fluid flow to the hydraulic cylinder is achievable. This is a particularly simple yet effective arrangement.

It is desirable that the pressure sensor activates when a control pressure is reached within the hydraulic line. For example the pressure sensor may be selected so that it is activated only when a certain minimum pressure in the line is reached or the ratio of the pressure in the line to the pressure elsewhere in the hydraulic system reaches a certain value. One simple construction which employs such an arrangement is where the pressure sensor senses pressure in a line to a hydraulic cylinder for moving at least part of the arm of an hydraulic arm. In one preferred arrangement (mentioned above) the control pressure is set to be the pressure reached in a line when at least one of the hydraulic cylinders supplied by the line is in a maximum extended position. As above it is preferred that the pressure sensor is in fluid communication with a hydraulic fluid supply line to the or at least one of the hydraulic cylinders which control the relative angle of the coupler to the arm (control articulation of the coupler on the arm).

The control pressure may be a set pressure above which the safety control allows operation of the engagement mechanism or may be a relative pressure ratio i.e the pressure in one part of the sytem relative to another.

In one embodiment the pressure control prevents hydraulic fluid from exiting a hydraulic ram for operating the engagement mechanism on instroke action of the ram until the control pressure is reached. In one particular arrangement the pressure control allows the hydraulic fluid to exit the hydraulic ram for operating the engagement mechanism on instroke action of the ram when a control pressure is reached in the line feeding the instroke action of the ram. One arrangement for achieving this functionality is to employ a check valve on the line the hydraulic fluid exits through (on instroke action of the ram)and which opens when a control pressure is reached in the feed line.

In one construction the pressure in the hydraulic line for feeding the instroke of the hydraulic ram is pressure from the line feeding the outstroke action of a hydraulic ram operating the coupler. It is desirable that at least one other control feature such as a second valve which must be activated to allow hydraulic fluid to flow to the instroke line of the hydraulic ram is in place. In one arrangement said second valve is arranged to prevent hydraulic fluid flow to the instroke line of the hydraulic cylinder. Desirably said second valve is arranged to control hydraulic fluid flow from the outstroke line for the (crowd) ram for moving the coupler, to the instroke line for the hydraulic ram of the engagement mechanism. The second valve is desirably actuatable by the operator of the machine, for example by way of a switch such as one incorporating a time delay mechanism.

In an alternative arrangement it is desirable that a system such as that described above has a pressure sensor which activates a valve on the hydraulic feed line for the instroke of the hydraulic cylinder and in which the hydraulic fluid flow for the instroke of the coupler cylinder does not necessarily come from the outstroke line of the crowd cylinder. Instead it is preferred that the hydraulic fluid in the outstroke line of the crowd cylinder is used to build up the control pressure to which the pressure sensor is subjected. The hydraulic fluid to instroking of the coupler ram comes from elsewhere in the system.

It will be appreciated that the term “instroking” used above refers to the movement of the ram to release the attachment - it will be appreciated that the coupler could be configured so that outstroking the ram causes release of the attachment also.

It is desirable also that the system above is not the sole control for actuation of the engagement mechanism from the attachment engaging position to the attachment release position if the attachment is not in one or more predetermined positions relative to the IE u 2 0 0 4 arm. In particular it is desirable that one or more other controls are incorporated in the system for example, one or more other controls for actuation of the engagement mechanism. Typically such a control would include a electrical and/or hydraulic signal which typically operate a valve which must be opened or closed to actuate the engagement mechanism as desired.

In one preferred embodiment a valve may be provided in the hydraulic line to a hydraulic cylinder for actuation of the engagement mechanism which can only be actuated to move to the release position if two or more conditions are fulfilled simultaneously (and/or within a selected time interval of each other), for example the pressure in a given hydraulic line has reached a desired level and a second signal, for example an electrical signal, from an operator control, has been received. In one particular construction the second signal is an electrical signal from an operator control. The electrical signal from the operator control can also be controlled by some further safety controls for example having two or more controls which must be activated independently to send the signal. For example an arrangement whereby the operator must actuate two or more controls within a predetermined time of each other (and preferably in a set sequence) to send the electrical signal is of particular interest.

Furthermore it is desirable to provide a visual and/or audible signal to the operator that the release mechanism has been activated. This may be done simply by including a buzzer and/or flashing light or the like for the operator, for example on a control console within the operator cab of the machine.

It is desirable that the hydraulic system of the vehicle to which the control system is fitted include pressure sensitive valves which act to prevent release of hydraulic fluid from the machine should for example a leakage occur (burst hydraulic hose or pipe etc.).

The invention also relates to a hydraulically operated arm having a control system of the invention fitted thereto. The invention also relates to a machine having at least one hydraulic arm and having a control system of the invention fitted thereto.

Brief Description of the Drawings Accordingly, the present invention will now be described in greater detail with reference to the accompanying drawings in which: Figure 1 is a perspective view of an earth working apparatus having a control system of the present invention; Figure 2 is a perspective (part cut-away) view of a coupler with an engagement mechanism for releasably engaging an attachment; Figure 3 is an elevation view of the coupler of Figure 2 with the engagement mechanism in a release position, in which the attachment is removeable from the coupler; Figure 4 is an elevation view of the coupler of Figure 2 with the engagement mechanism engaging the attachment securely for working of the attachment by the hydraulic arm of the machine; Figure 5 is a perspective partial view showing the coupler of Figure 2 fitted to the arm of the machine; the arm and the coupler being in relative position in which the control system of the invention does not allow the engagement mechanism to be actuated to a release position in which an attachment (bucket) is removeable from the coupler; Figure 6 is a perspective partial view showing the coupler of Figure 2 fitted to the arm of the machine, the arm and the coupler being in a selected relative position in which the control system of the invention allows the engagement mechanism to be actuated to a release position so that an attachment (bucket) is removeable from the coupler; Figure 7 is a diagramatic representation showing hydraulic and electrical circuits forming part of a control system of a first embodiment of the present invention; the control system configured to select the engaging position of the engagement mechanism; Figure 8 is a diagramatic representation showing hydraulic and electrical circuits forming part of a control system of a first embodiment of the present invention; the control system configured to select the release position of the engagement mechanism; Figure 9 is a diagramatic representation showing hydraulic and electrical circuits forming part of a control system of a second embodiment of the present invention; the control system configured to select the engaging position of the engagement mechanism; and Figure 10 is a diagramatic representation showing hydraulic and electrical circuits forming part of a control system of a second embodiment of the present invention; the control system configured to select the release position of the engagement mechanism.

Detailed Description of the Drawings The present invention provides a control system for controlling the release of an attachment from a coupler coupling the attachment to a hydraulically operable arm of an excavator, certain embodiments of which are described with reference to the accompanying drawings below. The invention is not limited to the detailed description below.

Referring to the drawings, Figure 1 shows an earth working apparatus 1 according to the present invention indicated generally by the reference numeral 1. It comprises a rotatable main excavator body 2 mounted on a chassis 20 which travels on a pair of caterpillar tracks 3. The excavator 1 has a hydraulic arm in the form of a back acter arm 21 is mounted on the chassis 20. The back acter arm 21 comprises a boom 4,which may be raised and lowered by the operator as required by actuation of hydraulic cylinders or rams 22 acting between the boom 4 and the body 2. Attached to the distal end of the boom 4 is a dipper arm 5, which is articulated to the boom 4. The distal (free) end of the dipper arm is adapted to enable attachment of excavator accessories. According to the present invention a quick hitch or coupler 6 is attached to the distal end of the dipper arm 5 for releasably attaching an excavator bucket 7 or other accessory. Any type of known coupler may be employed in the present invention but it is desirable that the coupler is of the type shown inthe drawings. ΪΕ 0 2 03 4 The operation of the dipper arm 5 is controlled by a hydraulic ram 8. The ram 8 controls the reach of the arm 21 by controlling the angle of the dipper arm 5 relative to the boom 4. The operation of the quick hitch or coupler 6 is controlled by a hydraulic ram 16 (best seen in Figures 2-4) and as will be described in more detail below. The angle of the coupler 6 relative to the arm 21 (and in particular relative to the dipper arm 5) is controlled by a hydraulic ram 24 hereinafter referred to as a “crowd” rain.

As shown in Figure 1 the bucket 7 (and as is conventional for excavator accessories) comprises a pair of coupling pins in particular a first coupling pin 14 and a second coupling pin 15. The coupling pins 14,15 are engaged through bores in the attachment to provide coupling means for attaching the attachment, (in this case the bucket 7) to the dipper arm 5 of the excavator. In the case of the present invention, the coupling pins 14,15 are grippable by the coupler 6, which in turn is attached to the dipper arm 5 of the excavator 1.

Figure 2 shows a section view of the coupler 6. The coupler 6 comprises a coupler or main body 11. An upstanding member 9 is mounted on the main body 11 of the coupler. A similar opposing member is normally provided on the body 11 but has been omitted so that the engagement mechanism is more easily seen. The member 11 has bores 27,28 for receiving pins for attachment to the dipper arm 5.

The coupler 6 has an engagement mechanism 10 adapted for gripping and releasing coupling pins 14,15 and thereby the bucket 7. The engagement mechanism 10 has first and second engagement members in the form of opposing gripping members in particular opposing jaws which are, in the embodiment shown, a slideable jaw 13 and a fixed jaw 12 (jaw 12 is best seen from Figures 3 and 4). The jaw 13 has an open mouth 25 which is opposed in direction to the open mouth 26 of the jaw 12. The jaws are arranged to receive (in the mouths thereof) a coupling pin of an attachment. In particular jaw 13 is arranged to engage with pin 15 and jaw 12 is arranged to engage with pin 14.

In use the pins 14,15 are held in the position shown in Figure 2 by virtue of being held in bores defined in the attachment as referred to above with respect to Figure 1. In Figures 2 to 4 the attachment has been omitted for the sake of clarity. 034 j The coupler ram 16 actuates the jaws so as to move them between a first attachment engaging position in which the engagement mechanism 10 engages the attachment securely for working of the attachment by the arm and a second attachment release position in which the attachment is removable from the coupler. In particular the coupler ram 16 moves slideable jaw 13 away from jaw 12 to engage the respective pins 15,14 to grip the pins and retracts jaw 13 toward jaw 12 to release the pins.

The release position of the engagement mechanism is shown in Figures 2 and 3 while the engaged position is shown in Figure 4. It is desirable that the coupler 6 is provided with a moveable latch 17 which acts as a lock to lock the pin 14 in the jaw 12. In particular in the embodiment shown the latch 17 is pivotable between an open position where the latch is aligned with the jaw 12 to enable reception of a coupling pin 14, and a closed position where it extends across the mouth of the jaw 12 for locking the coupling pin 14 in position.

Figure 2 and 3 illustrates the disengaged position of the coupler 6. To lock an attachment in position, the coupler 6 is lined up with the attachment so that the first coupling pin 14 of the attachment is positioned in the jaw 12 and jaw 13 is arranged for gripping coupling pin 15. The jaw 13 is then moved (by extension of the ram 16) so as to grip the second coupling pin 15 of the attachment. This causes the second coupling pin 15 to be gripped firmly in the mouth 25 of jaw 13.

In the embodiments of the coupler where a latch 17 is also provided, with the first outstroke movements of the ram 16 the latch 17 closes around the first coupling pin 14 to lock it in place. Figure 5 shows a partial view of part of the dipper arm 5 with the coupler 6 attached thereto. In the configuration of Figure 5 the latch 17 is closed over the coupling pin 15, preventing the bucket from being released. The relative orientation of the arm 21 (in particular the dipper arm 5) and the coupler 6 are such that if the front pin lock is open bucket 7 can fall from the coupler 6. It is a feature of the control system of the present invention that it will not allow the engagement mechanism to be actuated to a release position when in such a position.

Figure 6 shows a partial view of part of the dipper arm 5 with the coupler 6 attached thereto. In the relative orientation of the arm 21 (in particular the dipper arm 5) and the coupler 6 shown the bucket 7 cannot fall from the coupler 6. In particular the pin 14 is retained within the jaw 12 and even though pin 15 is released from jaw 13 the bucket is safely held in place and will not automatically fall from the arm. This is an important advantage of the control system of the present invention that it will only allow the engagement mechanism to be actuated to a release position when in such a position. In particular it is to be noted from Figure 6 that the crowd ram 24 is in the fully extended position (the bucket 7 is tucked into the arm). As shown in Figure 6 also it is desirable that the release of the attachment occurs on or close to the ground level 29.

The control system for controlling the engaging and release actions of the coupler 6 will be described now with reference to Figures 7-10. The control system is adapted to provide a safety mechanism which prevents the hydraulic ram 16 to the coupler 6 from operating so as to disengage the coupling pins 14,15 of the attachment from their locked position when the open jaw 26 of the coupler 6 is facing downwards.

Figures 7 and 8 are diagramatic representations showing hydraulic and electrical circuits forming part of a control system of a first embodiment of the present invention In Figure 7 the control system 100 is configured to select the engaging position of the engagement mechanism 10, while in Figure 8 the control system 100 is configured to select the release position of the engagement mechanism 10.

The main components of the control system 100 include a control console 130, and a valve system 101. The valve system 101 can be considered to be a solenoid operated directional control logic valve. The solenoid operated directional control valve 101 comprises a 4 port 2 position solenoid operated spring return valve 118 and a sensor in the form of a pressure sensitive valve 119. A pilot operated check valve 117 is provided to prevent flow of oil out of the coupler ram 16 in the event of a pressure drop in the system for example a burst pipe etc. ΙΕΟ2 034 1 A main oil reservoir 102 holds the oil required for operating the hydraulic rams of the machine. There is a breather 103, a motor 107 which is coupled by a coupling 106 to two oil pumps 104 and 105. Pumps 104 and 105 are the main source of hydraulic pressure in the machine’s system and in particular pump oil to the valve block 108. Typically pump 104 supplies the oil for the operation of the excavator tracks 3 while pump 105 supplies the oil for the hydraulic operation of the excavator rams. Valve block 108 represents the main valve controls operated by levers by the operator to control the rams for moving the arm 21 or the machine itself.

The bucket crowd ram 24 comprises a ram housing 111 and a piston rod 112 extending from the ram housing 111. Hydraulic lines 109 and 110 respectively provide the flow of oil in to and out of each end of the bucket crowd ram housing 111. The ram housing comprises a bore area 113 located at one side of the piston rod 112 and an annulus area 114 located at the other side of the piston rod 112. The direction of the oil flow through the hydraulic lines 109 and 110 is dictated by whether the control (on the valve block 108) for the bucket crowd ram 24 is set for it to instroke or outstroke.

When the bucket crowd ram 24 is set to outstroke, pump 105 pumps oil through the high pressure hydraulic line 109 into the bore end 113 of the bucket crowd ram housing 111. As the oil pressure increases, the piston rod 112 is gradually urged toward its extended position. This outstroking of the piston rod 112 causes the oil in the annulus area 114 of the bucket crowd ram housing 111 to be pushed into the (return) hydraulic line 110, through the valve block 108 and is returned to the oil reservoir 115. In practice the oil reservoir 115 will be the oil reservoir 102. Conversely, when the bucket crowd ram 24 is required to instroke the oil direction is reversed.

The hydraulic operation of the coupler ram 16 is controlled by a solenoid operated directional control logic valve 101. As stated above the solenoid operated directional control valve comprises a 4 port 2 position solenoid operated spring return valve 118 and a pressure valve 119. The pressure valve 119 only opens when a certain pressure is detected in line 132. When the valve 119 is closed, oil flowing towards the 4 port 2 position solenoid operated spring return valve 118 bypasses the valve 119 by flowing through the hydraulic line 136. Pump 105 supplies the oil from the main reservoir 102 to the 4 port 2 position solenoid operated spring return valve 118 via a high pressure hydraulic line 120. The return path for the flow of oil from the 4 port 2 position solenoid operated spring return valve 118 to an oil reservoir 121 is provided by the hydraulic line 122.

Another high presure hydraulic line 123 connects the 4 port 2 position solenoid operated spring return valve 118 to the pilot operated check valve 117. The pilot operated check valve 117 is connected to the bore area 124 and annulus area 125 of the coupler ram housing 116 by the high presure hydraulic lines 126 and 127 respectively. The pilot operated check valve 117 is also connected to the pressure valve 119 by the hydraulic line 128. The connection between the pressure valve 119 and the 4 port 2 position solenoid operated spring return valve 118 is represented by the hydraulic line 129. It will be appreciated that the hydraulic lines are represented diagramatically to show hydraulic fluid communication rather than the exact physical configurtation of the system, for example valves 118 and 119 could be formed in one unit.

The 4 port valve 118 controls the direction of the flow of oil to and from the coupler ram 16. The control signal for this valve is an electrical signal from the control console 130.

An electrical connection 131 connects the 4 port valve 118 to the control console 130. The control console 130 may be located remotely from the hydraulic control circuit, preferably on the excavator cab side window. A battery 150 powers the control console 140. On (sequential) depression of two switches 134,135 on the control console 130 (the switches may be on a timed interval so that the activation signal is ineffective unless the switches are both pressed within a set period one from another) an electrical signal is transmitted by connection 131 to open a valve in the 4 port valve 118. Oil is then pumped (from pump 105) to flow through the 4 port valve 118 to the pressure valve 119 via the hydraulic line 129. This is the first of a number of conditions which ΙΕΟ20345 must be met before the hydraulic coupler ram 16 can move the engagement mechanism to the release position (as described above).

The pressure valve 119 controls the flow of oil to the coupler ram 16. The control signal for the valve is a pressure control signal received through hydaulic line 132. In the embodiment the hydraulic signal is taken from line 132 which is branched from the hydraulic line 109 which provides the path for the flow of oil to and from the bucket crowd ram 24. This allows the pressure in line 109 to be transmitted through line 132 to the pressure valve 119.

The default position (shown in Figure 7) of the coupler ram 16 is for the ram 16 to receive hydraulic pressure to urge it towards its maximum extended (outstroke) position. As described above the hydraulic coupler ram 16 will in its extended position hold the coupler 6 in the engaging position (see Figures 2-4 above).

In this default position the pump 105 pumps oil from the main reservoir 102 through the hydraulic line 120 into the 4 port valve 118. The oil then flows through the 4 port valve 118 and through to the pilot check valve 117 via the hydraulic line 123. The oil passes through the cheek valve 117 into the bore area 124 of the coupler ram housing 116 via the hydraulic line 126. This flow of oil into the coupler ram housing 116 urges the piston rod 133 towards the extended position .

This urging of the piston rod 133 outwards forces the oil in the annulus area 125 of the ram housing 116 to flow into the hydraulic line 127 to the pilot operated check valve 117. The oil passes through the check valve 117 and bypasses the pressure valve 119 by flowing via the hydraulic lines 128 and 136. The oil then flows through the hydraulic line 129 to the 4 port valve 118. Finally the oil flows from the valve 118 into the hydraulic line 122 where it is fed back into the oil reservoir 121. Again reservoir 121 and oil reservoir 102 will normally be one and the same.

In order to release the attachment from the coupler 6, the moveable jaw 13 must be moved from its engaged to disengaged position by action of an instroke of the coupler ram 16. Figure 8 shows the configuration of the control system 100 required to set the ram 16 to instroke (release an attachment on the coupler 6).

The control system 100 requires the presence of two conditions before the ram 16 is enabled to perform an instroke. The first condition required is the activation signal originating from the control console 130.

The second condition to be met is that the pressure signal in the line 132 is such that it activates pressure valve 119. When the required signal is received the valve 119 moves to the position shown in Figure 8 reversing the direction of hydraulic fluid flow to the ram 16. The required pressure signal is generated when the pressure in the hydraulic line 132 exceeds a specific value, typically of the order of 300bars SI Units. The pressure selected is desirably a pressure threshold that is exceeded only after the pressure in the line has fully outstroked the crowd ram 24 and increased pressure results due to the fact that pressure builds up further as the ram 24 is at the limit of its extension. When the pressure valve 119 receives this signal, the valve is opened to allow the flow of oil through it to the pilot operated check valve 117. The oil then flows into the annulus area 125 of the coupler ram housing 116, thus enabling the ram 16 to be instroked. Of course ram 16 will only receive pressurised hydraulic fluid through lines 128 and 127 if valve 118 has already been activated to allow oil from line 120 to 129 (as is shown in Figure 8).

It will be appreciated that activation alone of valve 119 or valve 118 is not by itself sufficient to achieve the release of an attachment by the coupler 6. Both must be activated at the same time. This means that it is unlikely that the operator of the machine could inadvertently release the attachment. Even if the attachment is inadvertently released it will only happen in selected.relative positions of the attachment and the arm. It is a further advantage of the present invention that the attachment will not automatically fall from the coupler, but will remain partially held by the coupling as described above.

After activation of the release mechanism the system will return to the default position where only valve 118 need be operated to close the coupler again on an attachment.

Accordingly when it is required to operate the coupler ram 16 to disengage the attachment from the coupler 6 i.e. to instroke the coupler ram 16, the two activation signals must be present. The generation of these signals is enabled through the actions of an operator.

The operator must first operate a lever so as to outstroke the bucket crowd ram 24. This pressure from the maximum outstroke of the bucket crowd ram 24 feeds to the pressure valve 119 to activate the signal to enable the flow of oil through the valve towards the pilot operated check valve 117. Once the bucket crowd ram 24 is fully outstroked, the operator should then depress the two control switches 134 and 135 on the control console 130 (as above) to generate the electrical signal so as to activate the signal which reverses the direction of flow through the 4 port valve 118. This signal allows the pump 105 to pump oil through the hydraulic line 120 out through the valve 118 and then through the hydraulic line 129 to the directional control valve 119. As the directional control valve 119 is now open, oil may flow up through the hydraulic line 128 to the pilot operated cheek valve 117 and into the coupler ram 116 via the hydraulic line 127. This flow of oil into the annulus area 125 of the coupler ram housing 116 urges the piston rod 133 back into the ram housing 116. The oil contained in the bore area 124 of the ram housing 116 is then pushed into the the hydraulic line 126 and flows to the check valve 117. As the pressure on the hydraulic line 128 is sufficiently high the check valve 117 is in the open position, allowing oil to flow through it to the hydraulic line 123 into the 4 port 2 position solenoid operated control valve 118 and finally back to the oil reservoir 121 via the hydraulic line 122. Again, as the piston rod 133 of the ram coupler 116 is connected to the moveable jaw 13 of the coupler 6, this process of operating the coupler ram 16 as described above results in the movement of the moveable jaw 13 so as to disengage the coupling pins 14,15 of the attachment from the locked position.

An alternative embodiment of the control system 100 is illustrated in Figures 9 and 10. This embodiment is similar to the preferred embodiment, but without the inclusion of the pressure control valve 119. The same reference numerals have been used to identify the components that are the same as in the previous embodiment.

The hydraulic line 141 now connects the pilot operated check valve 117 directly with the 4 port valve 118. A hydraulic line 142 branches off the hydraulic line 109 and connects to the 4 port valve 118. This hydraulic line 142 has a valve 145. Another hydraulic line 143 now connects the pump 105 with the hydraulic line 123. This hydraulic line 143 has a valve 144. The control console of the previously described embodiment is now replaced in this embodiment with a simple on/off switch 140 (however it will be appreciated that a control console 130 such as that provided in the previous embodiment could also be used). A buzzer 160 is connected to the switch 140 which sounds when the switch 140 is in the on position. A fuse 170 is connected to the power supply 150. Similarly to the previous embodiment, the default operation for the coupler ram 16 is to be clamped in the outstroke position, corresponding to when the engaging mechanism 10 is in the attachment engaging position.

In Figure 9 the pump 105 pumps the oil from the reservoir 102 via the hydraulic lines 143 and 123 to the pilot operated check valve 117. The oil passes through valve 117 and into the bore area 124 of the coupler ram housing 116 via the hydraulic line 126. The pressure forces the oil contained in the annulus area 125 of the coupler ram housing 116 to flow through the hydraulic line 127 to the pilot operated check valve 117. The oil then continues through this valve 117 into the hydraulic line 141 to the 4 port valve 118. The oil then finally flows through line 122 into reservoir 121.

According to this embodiment of the present invention, the control system 100 responsible for the operation of the engagement mechanism 10 to release the attachment from the engaged position is configured so that the coupler ram 16 can only begin to instroke on reception of 2 activation signals (or when two conditions are met). One activation signal (condition) is generated by the closing of the on/off switch 140. On IE0 2 OS closing the switch, a signal is received by the 4 port valve 118. This signal results a reversal of the flow of oil through the ports of the valve 118 as shown in Figure 10.

The second activation condition or signal is a pressure signal. The pressure generated in hydraulic line 141 must be great enough to to cause the check valve 117 to open to allow the return of oil from the bore area 124 of the ram housing 116 through line 126 and into the reservoir 121. In particular the hydraulic pressure in the line 141 will reach a sufficiently high pressure to operate the valve 117 when the bucket crowd ram 24 is fully outstroked. The check valve 117 then opens to allow return of hydraulic fluid as described above when the pressure in the line 141 is sufficiently high. The determination of the value of the incoming pressure is taken from line 142.

The opening of the check valve 117 allows oil to flow from the bore area 124 of the coupler ram housing 116 back to the 4 port valve 118. The valve 117 may for example be configured so that it requires a pressure of a least a third of the system pressure to affect its opening. In order to achieve a pressure valve of this magnitude, it is necessary to build up the pressure in the hydraulic line 109. This typically occurs when the bucket crowd ram 24 is in the fully outstroked position.

As in the case of the preferred embodiment, to operate the instroking of the coupler ram 16 the operator must close the on/off switch 140 to cause the (4 port) valve 118 to switch to the position shown in Figure 10. The lever to outstroke the bucket crowd ram 24 must be operated at the same time and in particular towards full oustroking so that sufficient pressure builds up in the hydraulic line 141 to act as an activation signal to open the check valve 117 once a third of the system pressure is reached. This causes the oil to pump through the hydraulic line 142 into the 4 port valve 118. It then flows to the pilot operated check valve 117 via the hydraulic line 141. With the check valve now open it flows into the annulus area 125 of the coupler ram housing 116. This forces the piston rod 133 into the ram housing. The oil in the bore area 124 is pushed out into the hydraulic line 126, and through the open check valve 117. It then passes via the hydraulic line 123 to the 4 port valve 118, and from there into the oil reservoir 121 via the hydraulic line 122. Oil from the pump 105 returns to the reservoir 121 via line 143 and 122 due to the switching of the valve 118.

The words “comprises/comprising” and the words “having/including” when used herein 5 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.

Claims (19)

Claims

1. A control system for controlling the release of an attachment from a coupler coupling the attachment to a hydraulically operable arm of a machine, the hydraulically 5 operable arm being operable by a pressurised hydraulic system of the machine the coupler having: a coupler body adapted for coupling to the arm; an engagement mechanism, arranged on the coupler body, for releasably engaging the attachment, the engagement mechanism being actuatable to move 10 the engagement mechanism between a first attachment engaging position in which the engagement mechanism engages the attachment securely for working of the attachment by the arm and a second attachment release position in which the attachment is removable from the coupler; the control system incorporating a safety control for preventing actuation of the 15 engagement mechanism from the attachment engaging position to the attachment release position if the hydraulic pressure in at least one selected part of the hydraulic system does not exceed a threshold value.

2. A control system according to claim 1 wherein the machine has a hydraulic ram 20 which moves the coupler relative to the arm and the threshold value is measured from a hydraulic feed to that hydraulic ram.

3. A control system according to claim 2 wherein the pressure in the outstroke feed for the hydraulic ram is used by the control system to determine if the threshold value 25 has been exceeded.

4. A control system for controlling the release of an attachment from a coupler coupling the attachment to a hydraulically operable arm of a machine, the coupler having: a coupler body adapted for coupling to the arm; 30 an engagement mechanism, arranged on the coupler body, for releasably engaging the attachment, the engagement mechanism being actuatable to move the engagement mechanism between a first attachment engaging position in ^02054 which the engagement mechanism engages the attachment securely for working of the attachment by the arm and a second attachment release position in which the attachment is removable from the coupler; the control system incorporating a safety control for preventing actuation of the engagement mechanism from the attachment engaging position to the attachment release position if the coupler is not in one or more predetermined positions relative to the arm.

5. A control system according to any preceding claim wherein the control system is remotely operable.

6. A control system according to claim 4 or claim 5 wherein said one or more predetermined positions relative to the arm in which the safety control does not prevent actuation of the engagement mechanism to the release position is a position in which an attachment is removable from the coupler but in which the attachment is not completely disengaged from the coupler.

7. A control system according to any one of claims 4 to 6 wherein said one or more predetermined positions relative to the arm in which the safety control does prevent actuation of the engagement mechanism to the release position is a position in which an attachment is automatically completely disengageable from the coupler.

8. A control system according to claim 6 or claim 7 wherein said one or more predetermined positions at which the release of the attachment is allowed by the safety control are those in which the position to which the attachment is releasable is a partially disengaged position from which the attachment.

9. A control system according to claim 6 wherein said partially released position is one which holds an attachment from falling from the coupler under gravity.

10. A control system according to any preceding claim wherein the engagement mechanism comprises a hydraulically driven mechanism which is actuatable to move the engagement mechanism between the engaging and release positions.

11. A control system according to claim 10 wherein the hydraulic mechanism opens at least one side of opposing grips which close to grip the attachment for working thereof on the arm, and which open to at least partially engage the attachment.

12. A control system according to claim 10 or claim 11 wherein the safety control prevents the flow of hydraulic fluid to the hydraulic mechanism of the engagement mechanism whenever the relative positions of the arm and the attachment are at anondesirable release position.

13. A control system according to any preceding claim further comprising a pressure sensor for communication with a hydraulic line of a machine to which the control system is fitted; the pressure sensor for controlling the actuation of the engagement mechanism from the attachment engaging position to the attachment release position if the attachment is not in one or more predetermined positions relative to the arm.

14. A control system according to claim 13 wherein the pressure sensor is a pressure sensitive valve in communication with a hydraulic feed line of the hydraulic mechanism.

15. A control system according to claim 13 or claim 14 wherein the pressure sensor activates when a control pressure is reached within the hydraulic line.

16. A control system according to any preceding claim further comprising one or more other controls for preventing inadvertent actuation of the engagement mechanism from the attachment engaging position to the attachment release position.

17. A control system according to claim 16 wherein the engagement mechanism can only be actuated to move to the release position if two or more conditions are fulfilled simultaneously. IS. A hydraulically operated arm having a control system according to any preceding claim fitted thereto.

18.

19. A machine having at least one hydraulic arm and having a control system of the invention fitted thereto.