High-security quick-release fastener

The present invention relates to a construction machine, for example a mechanical shovel, to which a tool, such as a bucket, is attached in a movable manner, by means of a device forming a quick coupler consisting of a coupler, also known as a quick-release fastener, attached to the machine, particularly to an arm of the machine, and a connection device attached to the tool to engage with the coupler. The present invention also relates to a device forming a quick coupler of this kind and a coupler or quick-release fastener of this kind.

The term ‘bucket’ will be used below. However, the term ‘bucket’ must be understood to also cover any other tool or equipment intended to be mounted on a construction machine by means of the quick-release fastener and connection device.

So-called reversible quick-release fasteners are already known in the art, i.e. which can be attached to the bucket, and in particular to the connection device attached to the bucket, by presenting the coupler or quick-release fastener in two possible orientations in relation to the bucket, the quick-release fastener being rotated through 180° to switch from one orientation to the other.

Traditionally, the connection device that is intended to be attached to the bucket comprises an element in the form of a cradle having a base element and two lateral left and right flanks, between which two parallel, cylindrical, circular trunnions or axles, at a distance from one another, extend, arranged such that they are each able to engage with at least one front hook, in particular two left and right front hooks originating from the coupler for coupling between the coupler or quick-release fastener and the connection device to thus achieve coupling of the bucket to the arm of the construction machine.

In these known reversible devices from the prior art, the or each front hook comprises a part forming a rod and a part forming a hook head which extends laterally from the part forming a rod to define a receiving cavity for one of the trunnions, the cavity being open at the top to allow the trunnion to enter or leave the cavity.

These couplers of the prior art are dangerous in use. In particular, during the attachment stage, the bucket can often fall out of its attachment with the hook or hooks before the coupler has been fully secured to the bucket, which may prove extremely dangerous on construction sites where people are present.

The object of the present invention is to overcome the disadvantages of the prior art by proposing a device forming a coupler, in particular a so-called reversible coupler, as well as a coupler or quick-release fastener to be used in a device of this type, which is safer in use.

According to the invention, a device forming a coupler comprising a coupler, or quick-release fastener, which is intended to be attached to a construction machine, such as a mechanical shovel, and a connection device, which is intended to be attached to a tool, such as a bucket, the connection device comprising at least one trunnion, preferably two trunnions, which are in particular parallel with one another; the coupler comprising a base body from which, on a front side, at least one front hook originates, the or each front hook having a part forming a rod and a part forming a hook head which extends upwards from the part forming a rod to define at least one receiving cavity for the trunnion or one of the trunnions, having an opening at the top which extends between the base body and the region forming the respective head of the respective hook, is characterised in that, when the trunnion or one of the trunnions in the or a receiving cavity comes into contact with the part forming a rod, the part forming a head extends upwards beyond the centre of the circular section of the trunnion.

Preferably, the part forming the head extends upwards beyond the trunnion.

Preferably, the or each receiving cavity comprises, on the rear side, a recessed area created in the base body in which the trunnion can penetrate at least in part.

Preferably, the recessed area has a shape that, in longitudinal section, complements substantially at least half of the circular section of the trunnion.

By thus providing at least one front hook having a part forming a hook head that extends, in relation to the trunnion, higher than in the prior art, this ensures that, when the or each front hook is attached to the trunnion and the driver of the machine raises the bucket away from the ground with a view to locking the quick-release fastener to the connection device, if the driver carries out an incorrect movement and causes the coupler to pivot in the wrong direction, the trunnion does not become disengaged from the or each hook and the bucket is thus prevented from falling back to the ground.

Furthermore, by providing the recessed area, which is in particular at least semi-circular, this ensures that, even if the driver continues rotating in the wrong direction, the upper edge of the recessed area will come up against the edges of the flanks of the connection device and prevent any further rotation of the coupler in relation to the bucket and thus prevent the bucket becoming detached from the coupler once the or each hook is engaged with the trunnion. A device forming a coupler which is particularly safe in use is thus obtained.

Thus, preferably, the connection device comprises a lower base plate and on the upper side two lateral flanks, two trunnions spaced apart from one another being attached to the two flanks so as to extend between them, at a distance from the base plate, to allow the or each front hook of the quick-release fastener to pass between them and the base plate.

Preferably, the coupler or quick-release fastener, comprises an upper base plate from which two lateral flanks protrude downwards, each flank terminating on the front side in a respective hook.

Preferably, in longitudinal section, the highest point of the part forming the hook head is beyond the trunnion when said trunnion is located in the cavity, in contact with the part forming a rod.

Preferably, in longitudinal section, the highest point of the inner wall of the part of the cavity formed by the part forming the hook head is beyond the centre of the trunnion section, and in particular substantially at a level between the radius and the diameter of the trunnion section, in particular equal to the diameter of the trunnion section.

The present invention also relates to a quick-release fastener intended to form part of a device according to the invention.

Preferably, the connection device comprises two trunnions and, in the base body of the coupler, at least one second rear cavity for receiving the trunnion is defined, intended to receive the other trunnion once the first trunnion is attached to the hook or to each hook, said second rear cavity being open at the bottom, i.e. in the opposite direction to the direction towards which the opening of the first front receiving cavity faces.

The present invention also relates to a construction machine comprising a lifting element, in particular a lifting arm, and a tool, in particular a bucket, and a device forming a quick coupler according to the invention, the coupler or quick-release fastener being attached to the lifting element of the machine, while the connection device is attached to the tool.

According to the invention, the or each hook is not mobile in relation to the base body, in particular is immobile in relation to the base body, in particular is in just one piece or in one uninterrupted section with the latter, in particular is integrally formed with the base body, in particular is an integral part of the base body.

The figures show a quick-release fastenerwhich engages with a connection device, which is itself attached to a bucket.

The connection devicecomprises a base plate from the upper face of which two lateral flanksextend in a perpendicular manner. Two parallel, cylindrical-circular-shaped trunnions, topand bottomrespectively (when the bucket is placed on the ground), are attached to the two flanks such as to extend from one to the other at a distance from the base plate to allow two front hooksoriginating from the quick-release fastener to pass between them and the base plate.

The quick-release coupler is shown in detail, in an exploded view, in. The only items missing from this figure are the two lateral wingssupporting the axles enabling the quick-release fastenerto be attached to the arm of the lever of a construction machine such as the arm of a mechanical shovel.

The quick-release fastenercomprises a bottom body comprising an upper base plateand two lower lateral flanks(only one is visible on) originating from the upper plate, each flankterminating, on a side subsequently referred to as the front side, in a respective front hook.

A componentforming a lever is mounted such that it pivots with respect to an axleparallel to the axle of the trunnions when the quick-release fastener and the connection device are locked together. The axleis connected to the quick-release fastener but is able to undergo a limited movement through the oblong openingsformed by the lateral flanks.

Two rollerswhich are able to roll from one side to the other of the oblong openingsare attached by bolts (shown in the figure but not referred to by reference numerals) on each side of the axle. However, this attachment does not prevent relative rotation of the rollers around the axle, thus allowing the axle, and thus also the lever, to be driven in translation, even if said lever does not pivot.

The levercomprises two upper left and right branchesand two lower left and right branches, which extend backwards from the axle. The upper branches extend further backwards than the lower branches. The left upper and lower branches define a left-hand, C-shaped space, the opening of which is turned towards the back and in the same manner, the right upper and lower branches define a right-hand C-shaped space, the opening of which is turned towards the back.

Two right and left front branchesextend forwards from the axle. They each consist of a proximal portionfollowed by a distal portion, which extends in an inclined manner in relation to the proximal portion, in particular substantially at 90°. The two distal portionspass through two through openings, left and right respectively, formed through the base plateof the quick-release fastener to emerge from the upper surface of the base plate and are each fixed to a front end of a spring, left and right respectively, while the other respective ends of each springare attached to two left and right studsin the form of hooks originating from the upper face of the base plate, substantially in the region of the rear edge of the base plate. The springsare tension springs that tend to draw the front ends of the distal portions backwards. Two left and right coversare attached by bolts (shown but not referred to in the figure) against the lateral flanksto conceal and/or protect the openingsfrom the exterior, in particular to prevent earth getting lodged in the oblong openingsand impeding movement of the rollers.

A rear platewhich substantially takes the shape of a rectangular parallelepiped extends transversely between the two lateral flanks, substantially in the region of the rear edge of the base plate. The rear plateis attached to the flanks by bolts and holes, shown inbut without reference numerals. A rear notchis formed centrally in the upper edge of the rear plate, on the rear side of the plate.

In longitudinal section, the rear face of the rear plateis substantially rectilinear and vertical. The front face of the rear platein turn comprises a first substantially vertical lower portion, followed by an upper portion inclined upwards towards the rear.

A component, referred to as a lug, is mounted on the lever, between the left and right upper branches, being able to pivot with respect to the lever, with respect to an axle, parallel to the axleand which extends into the space between the two upper branchesof the lever. The axleof the lugis attached to the leverby means of a support componentin the form of a bridge attached to the upper face of the upper branchesby corresponding bolts and holes shown onbut not referred to by reference numerals. A torsion springis attached such that it acts on the lug. The lugcomprises, on either side of the axle, a rear partand a front part, the front parthaving smaller dimensions than the rear part, and thus a lower weight, such that the lug tends, under the effect of its own weight, to swing in a direction such as to cause its rear part to fall downwards (anticlockwise direction in the figures). The torsion springis mounted such as to act on the lugin a manner that also loads the rear part downwards. The rear partcomprises an upper protrusionand terminates in a rear tooth, which projects towards the bottom of the remainder of the rear part and which has dimensions enabling it to penetrate the rear notchof the plate. A groovewhich is intended to receive the upper protrusionis formed in the lower face of the base platewhen the upper branchesof the leverare positioned such that they are abutted against the lower face of the base plate.

On the front side, the quick-release fastenerdefines two respective receiving cavitiesfor one or other of the two trunnionsandof the connection device. Two receiving cutoutsfor the other of the two axlesandof the connection device are formed in the lateral flankson the rear side of the plate.

Each hookcomprises a partforming a rod that extends at the front end of one of the respective flanks, parallel to the plane of the plate, and terminates in a partforming a coupling head, which extends upwards from the end of the partforming a rod. Each hookthus defines, with the front edges of the lateral flanks, two cavitiesin which one or other, depending on the direction in which they are inserted in relation to the bucket, of the two axlesandoriginating from the connection deviceattached to the bucketare intended to be inserted through respective upper openings. The cavitycomprises a respective recessed areacreated in the front edge of each lateral flankand with a shape that complements at least half of the circular transverse cross-section of the axlesandsuch that, when the axleororiginating from the bucket is inserted in the receiving cavitiesthrough the openings, the axle can be inserted in the recessover at least half of its transverse cross-section, i.e. over a sector with an angle of at least 180°.

In relation to the lower, or bottom, surfaceof each cavity, the uppermost endof the partforming the head extends in the vertical direction at least in the region of the centre of the cross-section of the axleorwhen this is located in the cavity, in particular above the centre, and in particular substantially in the region of the diameter, or even above the diameter. Similarly, the uppermost endof the surface of the part forming the head of the side of the cavityextends above the centre of the axleor, in particular at a height between the radius and the diameter, or could even extend substantially to a height equal to the diameter of the axle.

The respective dimensions of the axles of the trunnions of the connection device attached to the bucket and the cavitiesformed by the hooksare selected such that once the headpart has been inserted beneath the axleorof the bucket, as shown onfor example, and the operator of the lifting machine causes the coupler to turn in the wrong direction, i.e. in the clockwise direction in, the shoulder formed between the edgeof the openingand the upper edgeof the plateof the quick-release fastenerwill abut against the edges of the flanksof the connection device originating from the bucketsuch that even though the operator has started to raise the bucket away from the ground, the quick-release fastener and the connection device can no longer pivot in relation to one another, the top part of the hook thus still remaining beneath the axle and preventing this axle, and thus also the bucket, from falling back to the ground, the stop in the region of the shoulder preventing any sudden withdrawal of the axle from the cavities. This stop comes into play beyond a rotation in the wrong direction of approximately 15°.

If the bucket operator causes the quick-release fastener to turn in the right direction (in the anticlockwise direction in) to lock the coupler to the connection device of the bucket, the cutoutscover the other axleof the bucket from above.

As the operator causes the quick-release fastener to pivot to insert the second axlein the cutouts, the second axleof the bucket comes to bear against the upper branchesof the lever, causing said lever to pivot and retreat (towards the front). At the limit of travel, the upper faces of the two upper branchesare parallel with the lower face of the base plateand, at the same time, the lug, which is mounted such that it pivots in relation to the leveris pushed by the springstowards the rear such that its toothpasses over the upper edge of the rear plateand penetrates the notch.

This backwards movement, under the effect of the springs, also drives the rear lower branches of the lever, which thus pass beneath the trunnion, trapping it in the cavity.

Thus, as shown on, the quick-release fastener is locked to the bucket. This is a well secured locking mechanism, and, in particular, even if one or more springswere to break or become detached, the quick-release fastener of the bucket would not become unlocked, thus being held in a secure manner.

The toothhas a rear surface that is inclined upwards and backwards such that when the springspush the leverbackwards again once this is in position with the rear upper branches in the horizontal direction, the pushing force, in conjunction with the inclined shape of the rear face of the tooth, causes the lug to pivot away from the torsion spring and allows the toothto pass into the notch.

shows a wrenchenabling the fastener to be unlocked once said fastener has been locked, i.e. once the toothhas swung into the notchof the plate.

The wrench comprises an extended handle(only part of said handle is shown in the figure) terminating in a head part comprising two upperand lowerlateral arms and a central projection. A studextends transversely from the end of the upper arm, in a direction perpendicular to the handle such that it can penetrate an eyelet formed in a studoriginating from the upper face of the plateof the fastener. A noseoriginates from the lower lateral arm, said nose extending towards the upper arm.

In order to unlock the fastener, the user inserts the studin the eyelet and causes the end of the noseto move against the rear face of the protrusionof the tooth, the dimensions of the nosebeing such that it can penetrate the groovein which the protrusionis received, then exerts a rotation movement such that the proximal end of the handle (the opposite end to the head) is moved downwards, which has the effect of causing the lug to pivot away from the torsion springand causing the toothto come out of the notch, thus unlocking the quick-release fastener.

In this description, the vertical direction is defined as being perpendicular to the plane of the upper face of the base plateof the quick-release fastener, the top side being the side towards which the opening of the cavityis turned. The terms proximal and distal are defined in relation to the centre of the quick-release fastener.

In particular, the terms top and bottom and lower and upper are defined in relation to this vertical direction, the connection device, which is attached to the bucket, being located beneath the quick-release fastener in the locked position.