Coupler for coupling attachments to excavation machines

A quick coupler for coupling an attachment, such as a digging bucket, to an evacuator machine. The quick coupler includes a first fixed jaw for a first coupling pin of the attachment. The quick coupler includes a latch cooperating with the first fixed jaw, which is moveable to a latched position for retaining the first coupling pin. A moveable jaw is provided that is able to slide, under power of a hydraulic ram, to a closed position retaining the second coupling pin. A locking arm assumes a locked position, while the latch assumes the latched position, preventing withdrawal of the moveable jaw from the closed position. Consequently, in the event of a hydraulic failure the locking arm simultaneously locks both the first attachment coupling pin, by means of the latch, and the second attachment coupling pin by means of preventing movement of the movable jaw from the closed position.

The present application claims priority from Australian patent application No. 2014203664 filed 3 Jul. 2014 and granted 5 Feb. 2015, the content of which is hereby incorporated in it is entirety.

TECHNICAL FIELD

The present invention relates to a hydraulic, quick coupler for coupling an attachment, such as a bucket, to a machine such as an excavator.

BACKGROUND

Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

FIG. 1, depicts an earth moving machine1. The earth moving machine1includes a dipper arm3. A remote end of the dipper arm3is attached to a bucket attachment5by means of a quick coupler7. The quick coupler7has a dipper side which mounts to the dipper arm3by means of first and second dipper coupling pins9,11. It also has an attachment side which includes jaws that engage first and second attachment coupling pins13,15. As is known in the prior art the locking of the quick coupler's jaws to at least one of the first and second attachment coupling pins13,15is effected remotely from the cabin of the machine1by virtue of a hydraulic circuit that extends from controls in the cabin to one or more actuators of the coupler.

U.S. Pat. No. 6,964,122 describes a prior art quick coupler which includes a hydraulically operated moveable jaw that operates to capture the first attachment coupling pin and a latch mechanism that cooperates with a fixed jaw to capture the second attachment coupling pin. The quick coupler that is described in the '122 patent is explained to have the advantage of the latch continuing to retain the second attachment pin even if, due to a hydraulic circuit failure, the moveable jaw disengages from the first attachment coupling pin.

The quick coupler of the '122 patent and other similar quick couplers of the prior art manage to hold onto the bucket attachment by one pin in the event of a hydraulic failure. Consequently, the bucket attachment5does not fall from the dipper arm3. Nevertheless the bucket attachment will swing rapidly and unexpectedly around the second attachment pin and may pose a serious threat of injury or even death to workers in the area.

It is an object of the present invention to provide an improved quick coupler which addresses or at least ameliorates the above described problem of the prior art.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a quick coupler for coupling an attachment to a machine, the attachment having first and second coupling pins, the quick coupler including: a first fixed jaw for the first coupling pin, a moveable jaw moveable to a closed position for retaining the second coupling pin, a locking arm arranged to assume a locked position in which the arm prevents withdrawal of the moveable jaw from the closed position, a latch cooperating with the first fixed jaw and moveable to a latched position for retaining the first coupling pin the latch being fast with the locking arm and arranged to assume the latched position upon the locking arm assuming the locked position, and an actuator coupled to the locking arm and arranged to move the movable jaw, whereby operation of the actuator brings the jaw to the closed position and the arm to the locked position thereby preventing withdrawal of the jaw from the closed position while also bringing the latch to the latched position.

Preferably the locking arm is pivoted at one end for pivoting to the locked position.

In a preferred embodiment of the invention the locking arm and the movable jaw have complementary engagement formations which engage upon the locking arm assuming the locked position and the movable jaw assuming the closed position.

Preferably the complementary engagement formations comprise an angled cutout of the locking arm and a complementary corner of the movable jaw.

The quick coupler may include a biasing means to bias the locking arm to the locked position.

Preferably the locking arm includes a closed cam follower.

In a preferred embodiment of the present invention the closed cam follower follows a translation cam coupled to the actuator.

The translation cam may comprise a trunnion.

Preferably the actuator comprises a linear actuator and the trunnion is coupled to shaft of the linear actuator.

The linear actuator may comprise a hydraulic ram.

The trunnion may comprise a portion of a locking collar.

It is preferred that the movable jaw slides on guides formed on inner sides of a body of the quick coupler.

In a preferred embodiment of the invention the movable jaw is moved to the closed position by means of the linear actuator.

Preferably a resilient spacer is located between the translation cam and the movable jaw whereby upon the movable jaw reaching the closed position the resilient spacer is compressed to thereby allow the translation cam to progress in the closed cam follower to thereby bring the locking arm to the locked position.

For example, the resilient spacer may comprise a coil spring.

It is preferred that the quick coupler includes a second fixed jaw positioned to engage the second attachment coupler pin upon failure of the movable jaw while the first attachment coupler pin is retained by the latch and the first fixed jaw to thereby prevent swinging of the attachment.

The second fixed jaw may oppose the movable jaw.

A rotary actuator may be disposed between coupling points of the coupler for attachment to the machine and the first fixed jaw and the movable jaw whereby operation of the rotary actuator tilts the jaws relative to the coupling points. The coupling points for attachment to the machine typically comprised bushed bores for receiving coupling pins of the machine.

DETAILED DESCRIPTION

Referring now toFIG. 2there is depicted an exploded view of a quick coupler17according to a preferred embodiment of the present invention. The quick coupler17has a body19which includes first and second side walls21a,21binterconnected by a transverse spacer23.

The side walls21a,21bare formed with respective pairs of forward bushed bores25a,25band rear bushed bores27a,27b. The forward bushed bores25a,25breceive forward dipper coupling pin29and similarly the rear bushed bores27a,27breceive rear dipper coupling pin31, for fastening the quick coupler to a machine, for example the dipper arm of an earth moving machine.

Forwardly, the underside of the body19is formed with a first fixed jaw33for engagement with a first coupling pin80of an attachment. The attachment may be a bucket for example but it could also be any one of a variety of other attachments such as a hydraulic hammer or a chisel.

Between the first and second side walls21aand21bthere is located a movable jaw37which is formed with an upper jaw body portion39. Jaw body39is formed with opposed slots41a,41bwhich receive corresponding opposed rails43a,43bwhich extend inwardly from the sidewalls21aand21bof coupler body19. Accordingly the moveable jaw37, which faces rearwardly, is able to slide toward the second attachment pin79along the opposed rails41a,41bto a closed position wherein it abuts the pin79

The upper surface of jaw body39is formed with a concave cradle45. Forward of the cradle the movable jaw body39is formed with a ram rod retainer47. The ram rod retain47comprises a cylindrical body having an axial bore49therethrough. An actuator in the form of a hydraulic ram51is located between the side walls21a,21b.

A forward end of the hydraulic ram51is formed with a transverse bore53therethrough. A ram retaining pin55traverses the side walls21a,21band the bore53thereby retaining the hydraulic ram51. The hydraulic ram51has a rearwardly extending ram rod57. The ram rod57extends through locking collar59, movable jaw spring60and thence through the axial bore49of ram rod retainer47. The ram rod57has a threaded tip which is secured by jam nut62and locking nut64, both of which locate within cradle45of jaw body39. A grub screw56penetrates through a top wall of the locking collar59and acts to hold the locking collar fast with the ram rod57.

Accordingly, operation of the hydraulic ram51causes the locking collar59to move with the ram rod57. As will be explained, the ram rod57also acts to push and pull the movable jaw body39and hence jaw37so that it slides on rails43a,43binto and out of engagement with the second attachment coupling pin79.

Also located between side walls21aand21bof the coupler17is a locking arm61. The locking arm61is comprised of a pair of parallel locking arm members63a,63bwhich are rigidly interconnected and spaced apart by integral transverse bridging portions65,66. The hydraulic ram51locates in a space between the locking arm members63a,63b.

Toward a forward end of each locking arm member a pivot hole67a,67bis formed therethrough. The ram retaining pin55also penetrates through the locking arm member pivot holes67a,67b. Accordingly, the hydraulic ram51and the locking arm61are both retained at their forward end by the ram retaining pin55.

The locking arm members63a,63bof the locking arm are formed with closed cam follower slots69a,69bwhich respectively receive transversely extending trunnions71aand71bof the locking collar59. The trunnions71aand71beffectively act as translation cams for the cam follower slots69a,69b.

FIG. 3is a cross sectional view of the quick coupler17through section A-A′ as indicated inFIG. 2. The section A-A′ is through first locking arm member63a. Since locking arm members63aand63bare identical it is to be understood that the following description, which is made with reference toFIG. 3, also holds true for locking arm member63b. For convenience the features of the locking arm members will be generally referred to by a single identifier number, for example it will be understood that “pivot hole67” is to be understood as a shorthand for “pivot hole67aand pivot hole67b”.

With reference toFIG. 3, a biasing means in the form of locking arm member coil spring73is fastened under tension between spring detent bolt75and spring retaining formation77of locking arm member63. The spring detent bolt75is fastened to a side21of the body19of the coupler17. Accordingly, the coil spring73urges the locking arm member63to pivot clockwise about the ram retaining pin55. The biasing force of the coil spring73is offset by the action of the trunnion71against an upper edge of the closed cam follower slot69when the ram rod57is retracted as shown inFIG. 3.

The underside of the locking arm member63is fast with a latch78that extends downward from the locking arm member63and which is integrally formed therewith.

Upon the hydraulic actuator51being operated, the ram rod57extends pushing the locking collar59into contact with a resilient spacer in the form of movable jaw spring60. As the ram rod57continues to extend the spring60then urges the jaw body39along rails43a,43bso that the movable jaw37advances towards the second fixed jaw35.

The movable jaw37continues to advance until, as shown inFIG. 4, it assumes a closed position wherein it abuts the second coupling pin79of the attachment. In this closed position the movable jaw37cooperates with the second fixed jaw35to retain the second coupling pin79therebetween.

As the ram rod57extends from the position shown inFIG. 3to the position shown inFIG. 4, it brings with it the locking collar59as previously explained. Consequently, trunnion71forces against the walls of the closed cam follower slot69. As the trunnion71proceeds within the cam follower slot69it urges the arm63to pivot clockwise about the ram retaining pin55and is assisted by the locking arm member spring73. A forward portion of the locking arm member63is formed with an angled cutaway81that has sides which complement a corner83of the movable jaw body39. As the locking arm member63pivots clockwise about the ram retaining pin55the movable jaw body advances so that the position of the corner83corresponds to that of the angled cutaway81. The locking collar59then compresses the movable jaw spring60thereby allowing the trunnion71to progress a little further in cam follower slot69so that it reaches a final station in the slot69. The final station in the slot69has a flat upper edge thereby preventing the locking arm member63from pivoting back up should the trunnion71move slightly, either back or forth. Consequently, in the state shown inFIG. 4the locking arm member63has assumed a locked position wherein it prevents withdrawal of the movable jaw37from its closed position. In the closed position shown inFIG. 4the movable jaw37abuts and retains the second attachment pin79.

As the locking arm member63pivots clockwise about the ram retaining pin55from the unlocked configuration shown inFIG. 3to the locked configuration ofFIG. 4, the latch78descends so that it cooperates with the first fixed jaw33to thereby retain the first attachment coupling pin80.

It will be noted that the latch78assumes the latched position shown inFIG. 4as the locking arm member63locks the movable jaw39to the closed position.

Although a pivoting locking arm61is preferred, the locking arm could, in other embodiments of the invention slide downward from an unlocked to a locked position. However, such an arrangement may involve a second hydraulic actuator which is less than desirable.

In order to unlock the quick coupler17from the first and second attachment coupling pins hydraulic pressure is initially applied to the hydraulic ram51in a direction to cause the ram rod57to retract from its extended, locked, position.

The rod57slides forward through the ram rod retainer47, which is fast with the movable jaw body39. With retraction of the rod57the locking collar59and hence trunnion71move forward. As the trunnion71moves forward it acts as a translation cam against the closed cam follower slot69and so causes the locking arm member63to overcome the locking arm member spring73and to pivot counterclockwise about ram retaining pin55. As the locking arm member63pivots counterclockwise the angled cutaway81comes clear of corner83of the movable jaw body39. Consequently the locking arm member63no longer prevents sliding of the movable jaw body39.

Initial retraction of the rod57does not move the movable jaw body39since in its extended position there is a length “d” of the rod57between retainer47and the jam nut62. After the ram rod57has been retracted through the distance “d” the jam nut62comes into contact with the rear of retainer47so that the movable jaw body39commences to slide forward thereby bringing the movable jaw37away from abutment with the second attachment coupling pin79and thereby out of the closed position. Consequently the second attachment coupling pin79is now longer locked in place. Simultaneously the locking collar59, which is fast with the ram rod57by virtue of grub screw56, continues to move forward, so that its trunnion71continues to act against the closed cam follower slot69and pivots the locking arm member63anticlockwise. As the locking arm member63continues to pivot to the final position shown inFIG. 3the latch79clears the first fixed jaw and so the first attachment coupling pin80is no longer locked in place.

It will be realized that once in the locked position, that is shown inFIG. 4, the coupler will maintain locking of both the first and second attachment coupler pins80,79even if the hydraulic ram51fails or if there is a failure in the hydraulic circuit that powers the hydraulic ram. This is because the locking arm members63a,63bof the locking arm61simultaneously lock both the first attachment coupling pin, by means of latch78, and the second attachment coupling pin, by means of the angled cutaway81engaging the corner83of the movable jaw body69.

FIG. 5shows the coupler17in use coupling an attachment, in the form of a hydraulic rock grab85, to the dipper arm of an excavator87.

Once the coupler17is in in the locked configuration ofFIG. 4then even if movable jaw37fractures and falls away as shown inFIG. 6, the second fixed jaw35prevents pivoting of the coupler17and attachment about the first attachment coupling pin80. Furthermore, the second fixed jaw35cooperates with latch78and first fixed jaw33to retain the attachment coupling pins80,79and so also the attachment85so that the attachment does not drop or swing.

FIG. 7shows a coupler89which comprises a further embodiment of the present invention. The coupler89has an identical mechanism to the coupler17that has previously been described save that coupler89includes a hydraulic rotary actuator91. The hydraulic tilt barrel provides for tilting between coupling points in the form of the bushed bores25,27that receive the forward and rear dipper coupler pins and the jaws33and37that project from the underside of the coupler. Consequently an operator of the excavation machine to which the coupler89is installed is able to tilt the attachment by operating the hydraulic rotary actuator91.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term “comprises” and its variations, such as “comprising” and “comprised of” is used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Throughout the specification and claims (if present), unless the context requires otherwise, the term “substantially” or “about” will be understood to not be limited to the value for the range qualified by the terms.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.